JP2013043536A - Vehicle brake control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ensure reliability by suppressing excessive operation of a linear control valve while establishing brake operation feelings when pulsation of a hydraulic fluid occurs.SOLUTION: There is such a characteristic that a pulsation amplitude of a hydraulic pressure of a hydraulic fluid becomes small when the hydraulic pressure is low. Furthermore, when the hydraulic pressure of the hydraulic fluid is low, hydraulic pressure rigidity becomes low and a brake response is delayed. Then, when pulsation of the hydraulic fluid occurs and a hydraulic pressure Pxave representing a center value of pulsation of detected hydraulic pressure is low, a control start threshold value X is set which is smaller than in the case where the hydraulic pressure Pxave is high, on the basis of the hydraulic pressure Pxave.

Description

  The present invention relates to a vehicle brake control device that controls a hydraulic pressure of a wheel cylinder to a target hydraulic pressure by a linear control valve.

  Generally, in this type of brake control device, when the deviation between the target hydraulic pressure of the wheel cylinder and the actual hydraulic pressure that is actually detected exceeds the dead band, the linear control valve (pressure-increasing side linear valve) Alternatively, the hydraulic pressure of the wheel cylinder is controlled to follow the target hydraulic pressure by driving the pressure reducing side linear valve. In the drum brake, when the drum is mounted with the rotation center axis of the drum being eccentric with respect to the rotation center axis of the wheel, or when the drum is not round, the drum and the friction engagement member The force acting during the period fluctuates periodically as the drum rotates. For this reason, the hydraulic pressure of the wheel cylinder fluctuates periodically, and in response to this, the operation of the linear control valve is repeated. Therefore, in the brake device proposed in Patent Document 1, the dead zone width for drum brake control is set wider than the dead zone width for disc brake control, so that control hunting caused by hydraulic pressure pulsation of the wheel cylinder is performed. Suppress.

JP 2005-28975 A

  When the dead zone width is widened and control hunting is suppressed, excessive operation of the linear control valve is suppressed, so that the durability performance of the linear control valve can be maintained and the reliability is improved. However, as a contradiction, the control start timing of the linear control valve is delayed. For this reason, it is not preferable as a brake operation feeling.

  The present invention has been made to solve the above-described problems, and aims to establish a brake operation feeling and ensure the reliability of the linear control valve.

A feature of the present invention that solves the above-described problems is that a wheel cylinder (42) that receives a hydraulic pressure of hydraulic fluid to apply a braking force to the wheel, a brake operation amount detection means (104) that detects a brake operation amount, and the wheel Linear control valves (67A, 67B) for adjusting the hydraulic pressure transmitted to the cylinder, hydraulic pressure detecting means (103) for detecting the hydraulic pressure transmitted to the wheel cylinder, and detected by the hydraulic pressure detecting means Liquid that starts drive control of the linear control valve so that the detected hydraulic pressure approaches the target hydraulic pressure when the absolute value of the deviation between the detected hydraulic pressure and the target hydraulic pressure exceeds the control start threshold In a vehicle brake control device comprising a pressure control means (100),
Control start threshold value changing means (S16, S26) for changing the control start threshold value according to a parameter affecting the amplitude characteristic of the hydraulic pressure pulsation generated by the periodic external force acting on the wheel cylinder is provided. is there.

  In the present invention, the hydraulic pressure control means controls the drive of the linear control valve so that the detected hydraulic pressure approaches the target hydraulic pressure when the absolute value of the deviation between the detected hydraulic pressure and the target hydraulic pressure exceeds the control start threshold. To start. If the brake unit with the wheel cylinder is not appropriate, for example, if the disc brake unit is not uniform in thickness, or if it is a drum brake unit, the roundness of the drum is poor, etc. The piston of the cylinder is periodically pushed, and the volume fluctuation of the wheel cylinder occurs and the hydraulic pressure pulsates. In such a case, when the hydraulic pressure control means captures fluctuations in the detected hydraulic pressure and drives and controls the linear control valve, the linear control valve repeatedly opens and closes, so the durability life of the linear control valve is shortened and reliability is reduced. .

  Therefore, in the present invention, the control start threshold value changing means starts control according to a parameter that affects the amplitude characteristics of the hydraulic pressure pulsation generated by the periodic external force acting on the wheel cylinder (force acting from the wheel side). Change the threshold. Therefore, the control start threshold value can be increased in a situation where the amplitude of hydraulic fluid pulsation generated in the wheel cylinder is large, and conversely, the control start threshold value can be reduced in a situation where the amplitude of hydraulic fluid pulsation is small. That is, the control start threshold value can be changed in accordance with the pulsation amplitude characteristic. As a result, according to the present invention, when the hydraulic fluid of the wheel cylinder pulsates due to an external force, the control start threshold can be appropriately changed, so that the linear control valve is excessively operated while the brake operation feeling is established. (Repeating the opening / closing operation) can be suppressed, and the reliability of the linear control valve can be ensured.

  Another feature of the present invention is that the parameter is a hydraulic pressure of the hydraulic fluid. In this case, the parameter is the hydraulic pressure of the hydraulic fluid, and the control start threshold value changing means (S16) may reduce the control start threshold value when the hydraulic pressure is small compared to when it is high.

  In a normal brake operation range (low hydraulic pressure region), there is a characteristic (amplitude characteristic) in which the amplitude of pulsation decreases as the hydraulic pressure of the hydraulic fluid decreases. This is because the pulsation of the hydraulic fluid changes depending on the hydraulic rigidity, and the hydraulic rigidity becomes smaller as the hydraulic pressure becomes lower. Therefore, in the present invention, the hydraulic pressure of the hydraulic fluid is a parameter that affects the amplitude characteristics of the hydraulic pressure pulsation generated by the periodic external force acting on the wheel cylinder.

  The control start threshold value changing means reduces the control start threshold value when the hydraulic pressure of the hydraulic fluid is small compared to when it is high. Therefore, according to the present invention, the control start threshold value can be changed according to the amplitude characteristic of the hydraulic pressure.

  In addition, “when the hydraulic pressure of the hydraulic fluid is low, the control start threshold value is reduced compared to when it is high” means at least when the hydraulic pressure is low at a specific hydraulic pressure, compared to when it is high. What is necessary is just to make a control start threshold value small. Of course, the control start threshold value changing means may be configured to decrease the control start threshold value as the hydraulic fluid pressure decreases.

  Another feature of the present invention is that the control start threshold value changing unit (S16) is configured to detect the detected hydraulic pressure, the target hydraulic pressure, or the brake operation based on the detected hydraulic pressure, the target hydraulic pressure, or the brake operation amount. When the amount is small, the control start threshold value is made smaller than when the amount is large.

  If the control start threshold is changed based on the detected hydraulic pressure of the hydraulic fluid, the control start threshold can be changed according to the amplitude characteristic of the hydraulic pressure. In this case, since the detected hydraulic pressure pulsates, the control start threshold value may be changed based on the pulsation center value that is an average value thereof. Further, since the hydraulic pressure of the hydraulic fluid is controlled so as to approach the target hydraulic pressure by the hydraulic pressure control means, it changes with the target hydraulic pressure. Therefore, the hydraulic pressure of the hydraulic fluid may be regarded as the target hydraulic pressure, and the control start threshold value may be changed based on the target hydraulic pressure. Further, since the target hydraulic pressure is set based on the brake operation amount, the hydraulic pressure of the hydraulic fluid also changes according to the magnitude of the brake operation amount. Therefore, the control start threshold value may be changed based on the brake operation amount.

  Therefore, according to the present invention, since the control start threshold value can be changed in accordance with the amplitude characteristic of the hydraulic pressure, excessive operation of the linear control valve is suppressed while establishing the brake operation feeling, and the linear control valve Reliability can be ensured.

  Another feature of the present invention is that the target hydraulic pressure and the detection are detected when a pulsation of the hydraulic pressure at which the absolute value of the deviation between the target hydraulic pressure and the detected hydraulic pressure is greater than the control start threshold is detected. Deviation-corresponding control start threshold value calculating means (S30) for calculating a control start threshold value that is increased until the absolute value of the deviation from the hydraulic pressure is equal to or less than the control start threshold value, and the control start threshold value changing means is the detection liquid Hydraulic pressure corresponding control start threshold value calculating means (S16) for calculating a control start threshold value that is smaller than when the pressure or the target hydraulic pressure or the brake operation amount is large, and the deviation corresponding control start threshold value calculating means. Control start threshold selection means (S) for selecting the smaller control start threshold value among the control start threshold value calculated by the above and the control start threshold value calculated by the hydraulic pressure corresponding control start threshold value calculation means. In further comprising a 1～S43) and.

  The linear control valve does not operate excessively if the absolute value of the deviation between the target hydraulic pressure and the detected hydraulic pressure does not exceed the control start threshold. Therefore, the deviation corresponding control start threshold value calculating means detects the target hydraulic pressure and the detected liquid when a pulsation of the hydraulic pressure at which the absolute value of the deviation between the target hydraulic pressure and the detected hydraulic pressure is larger than the control start threshold is detected. The control start threshold value increased until the absolute value of the deviation from the pressure becomes equal to or less than the control start threshold value is calculated. On the other hand, the hydraulic pressure corresponding control start threshold value calculation means calculates a control start threshold value that is smaller than when the detected hydraulic pressure, the target hydraulic pressure, or the brake operation amount is small.

  If the control start threshold value calculated by the deviation corresponding control start threshold value calculation means is used, excessive operation of the linear control valve can be reliably suppressed, but in the case where the pulsation amplitude of the hydraulic pressure has been reduced, The control start threshold value may become larger than necessary. Therefore, the control start threshold selection means has a smaller control start threshold value between the control start threshold value calculated by the deviation corresponding control start threshold value calculating means and the control start threshold value calculated by the hydraulic pressure corresponding control start threshold value calculating means. Select. Therefore, according to the present invention, the reliability of the linear control valve can be ensured by suppressing the excessive operation of the linear control valve while better establishing the brake operation feeling.

  Another feature of the present invention is that the parameter is a vehicle speed, and the control start threshold value changing means (S26) reduces the control start threshold value when the vehicle speed is high compared to when it is low.

  The pulsation of the hydraulic fluid has a characteristic (amplitude characteristic) that the amplitude decreases as the vehicle speed increases. Therefore, in the present invention, the vehicle speed is a parameter that affects the amplitude characteristics of the hydraulic pressure pulsation generated by the periodic external force acting on the wheel cylinder.

  The control start threshold value changing means decreases the control start threshold value when the vehicle speed is high compared to when the vehicle speed is low. Therefore, the control start threshold value can be set according to the amplitude characteristic of the hydraulic pressure pulsation, and the control start threshold value is set according to both the amplitude characteristic of the hydraulic pressure pulsation and the brake operation feeling given to the driver. be able to. As a result, according to the present invention, the reliability of the linear control valve can be ensured by suppressing the excessive operation of the linear control valve while establishing the brake operation feeling.

  Note that “when the vehicle speed is high, the control start threshold is reduced compared to when the vehicle speed is low” at least when the vehicle speed is high at a specific vehicle speed, the control start threshold is reduced compared to when the vehicle speed is low. Anything to do. Of course, the control start threshold value changing means may be configured to decrease the control start threshold value as the vehicle speed increases.

  Another feature of the present invention is that the parameter is both a hydraulic pressure of the hydraulic fluid and a vehicle speed, and the control start threshold value changing means is configured to determine whether the detected hydraulic pressure, the target hydraulic pressure, or the brake operation amount is A hydraulic pressure corresponding control start threshold value calculation means (S16) that calculates a control start threshold value that is smaller than that when the vehicle speed is large, and a vehicle speed that calculates a control start threshold value that is smaller than when the vehicle speed is small. The larger one of the corresponding control start threshold value calculating means (S17), the control start threshold value calculated by the hydraulic pressure corresponding control start threshold value calculating means, and the control start threshold value calculated by the vehicle speed corresponding control start threshold value calculating means. Control start threshold selection means (S18 to S20) for selecting the control start threshold.

  In the present invention, the control start threshold is set based on both the hydraulic fluid pressure and the vehicle speed. For this purpose, the control start threshold value changing means includes a fluid pressure corresponding control start threshold value calculating means, a vehicle speed corresponding control start threshold value calculating means, and a control start threshold value selecting means. The hydraulic pressure corresponding control start threshold value calculating means calculates a control start threshold value that is smaller than that when the detected hydraulic pressure, the target hydraulic pressure, or the brake operation amount is small, and the vehicle speed corresponding control start threshold value calculating means is When the value is large, a control start threshold value that is smaller than the small value is calculated. Then, the control start threshold selection means has a larger control start threshold value between the control start threshold value calculated by the hydraulic pressure corresponding control start threshold value calculating means and the control start threshold value calculated by the vehicle speed corresponding control start threshold value calculating means. Select.

  Therefore, according to the present invention, it is possible to set a control start threshold that takes into account the hydraulic pressure of the hydraulic fluid and the vehicle speed, so that excessive operation of the linear control valve can be more appropriately suppressed while establishing the brake operation feeling. can do.

  Another feature of the present invention includes pulsation detecting means (S14) for detecting that the hydraulic pressure of the hydraulic fluid is pulsating, and the control start threshold value changing means is configured to detect pulsation of hydraulic pressure by the pulsation detecting means. When detected, the control start threshold value is changed to a value larger than a normal control start threshold value indicating a control start threshold value when the pulsation of the hydraulic pressure is not detected.

  In the present invention, since the control start threshold value is increased and changed when the pulsation of the hydraulic fluid is actually detected, the control start threshold value is not changed in an unnecessary situation, and the change in the wasteful brake operation feeling is achieved. Can be suppressed.

  In the above description, in order to help the understanding of the invention, the reference numerals used in the embodiments are attached to the configuration of the invention corresponding to the embodiment in parentheses, but each constituent element of the invention is the reference numeral. It is not limited to the embodiment defined by.

It is a schematic system block diagram of the brake control apparatus in this embodiment. It is explanatory drawing showing the propagation path of hydraulic pressure pulsation. It is a graph showing the state in which the linear control valve is operating excessively. It is experimental data showing the relationship (amplitude characteristic) between the hydraulic pressure of hydraulic fluid and pulsation amplitude. It is a graph showing the control start threshold value setting map showing the relationship between a hydraulic pressure and a control start threshold value. It is a flowchart showing the threshold variable control routine concerning 1st Embodiment. It is a flowchart showing a pulsation detection routine. It is a flowchart showing a pulsation cycle detection routine. It is a graph showing the method of calculating | requiring a pulsation period. It is a graph showing the detection liquid pressure which changes with liquid leaks. It is experimental data showing the relationship (amplitude characteristic) of a vehicle speed and the pulsation amplitude of a hydraulic fluid. It is a graph showing the control start threshold value setting map showing the relationship between a vehicle speed and a control start threshold value. It is a flowchart showing the threshold variable control routine concerning 2nd Embodiment. It is a graph showing the control start threshold value setting map as a modification. It is a flowchart showing the threshold variable control routine concerning 3rd Embodiment. It is a flowchart showing the threshold variable control routine concerning 4th Embodiment. It is a flowchart showing the deviation corresponding | compatible control start threshold value calculation routine concerning 4th Embodiment. It is the graph showing the image where the deviation corresponding | compatible control start threshold value is set to increase. It is a graph explaining the setting of a control start threshold value. It is a graph showing the control start threshold value setting map concerning a modification.

  A vehicle brake control device according to an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic system configuration diagram of a vehicle brake control device according to the present embodiment.

  The brake control device of the present embodiment includes a brake pedal 10, a master cylinder unit 20, a power hydraulic pressure generating device 30, a hydraulic pressure control valve device 50, and brake units 40FR, 40FL, 40RR provided on each wheel, respectively. 40RL and a brake ECU 100 for controlling the brake. The brake units 40FR, 40FL, 40RR, 40RL include brake disks 41FR, 41FL, 41RR, 41RL and wheel cylinders 42FR, 42FL, 42RR, 42RL built in the brake caliper. The brake unit 40 is not limited to the disc brake type for all four wheels. For example, all the four wheels may be a drum brake type, or the front wheel may be a disc brake type and the rear wheel may be a drum brake type. May be good.

  Hereinafter, for the configuration provided for each wheel, the reference numeral is suffixed with FR for the right front wheel, FL for the left front wheel, RR for the right rear wheel, and RL for the left rear wheel. When the wheel position is not specified, the last symbol is omitted.

  The wheel cylinders 42FR, 42FL, 42RR, and 42RL are connected to the hydraulic pressure control valve device 50, and the hydraulic pressure of the hydraulic fluid (brake fluid) supplied from the hydraulic pressure control valve device 50 is transmitted. The brake pads are pressed against the brake discs 41FR, 41FL, 41RR, 41RL that rotate with the brake discs, and braking force is applied to the wheels.

  The master cylinder unit 20 includes a hydraulic booster 21, a master cylinder 22, a regulator 23, and a reservoir 24. The hydraulic booster 21 is connected to the brake pedal 10, amplifies the pedal effort applied to the brake pedal 10, and transmits it to the master cylinder 22. The hydraulic pressure booster 21 amplifies the pedal depression force and transmits it to the master cylinder 22 when hydraulic fluid is supplied from the power hydraulic pressure generator 30 via the regulator 23. The master cylinder 22 generates a master cylinder pressure having a predetermined boost ratio with respect to the pedal effort.

  A reservoir 24 that stores hydraulic fluid is provided above the master cylinder 22 and the regulator 23. The master cylinder 22 communicates with the reservoir 24 when the depression of the brake pedal 10 is released. The regulator 23 communicates with both the reservoir 24 and the accumulator 32 of the power hydraulic pressure generator 30, and generates a hydraulic pressure substantially equal to the master cylinder pressure using the reservoir 24 as a low pressure source and the accumulator 32 as a high pressure source. Hereinafter, the hydraulic pressure of the regulator 23 is referred to as regulator pressure. Note that the master cylinder pressure and the regulator pressure need not be exactly the same. For example, the regulator pressure may be set to be slightly higher than the master cylinder pressure.

  The power hydraulic pressure generator 30 is a power hydraulic pressure source, and includes a pump 31 and an accumulator 32. The pump 31 has a suction port connected to the reservoir 24, a discharge port connected to the accumulator 32, and pressurizes the hydraulic fluid by driving the motor 33. The accumulator 32 converts the pressure energy of the hydraulic fluid pressurized by the pump 31 into the pressure energy of an enclosed gas such as nitrogen and stores it. The accumulator 32 is connected to a relief valve 25 provided in the master cylinder unit 20. The relief valve 25 opens to return the working fluid to the reservoir 24 when the pressure of the working fluid increases abnormally.

  As described above, the brake control device includes the master cylinder 22 that uses the driver's brake depression force (the force to depress the brake pedal 10), the regulator 23, and the driver as a hydraulic pressure source that applies hydraulic pressure to the wheel cylinder 42. And a power hydraulic pressure generator 30 that applies a hydraulic pressure regardless of the brake pedal force. The master cylinder 22, the regulator 23, and the power hydraulic pressure generator 30 are connected to the hydraulic control valve device 50 via the master pipe 11, the regulator pipe 12, and the accumulator pipe 13, respectively. The reservoir 24 is connected to the hydraulic control valve device 50 through the reservoir pipe 14.

  The hydraulic control valve device 50 is a mainstream that communicates the four individual flow paths 51FR, 51FL, 51RR, 51RL connected to the wheel cylinders 42FR, 42FL, 42RR, 42RL and the individual flow paths 51FR, 51FL, 51RR, 51RL. A passage 52, a master passage 53 connecting the main passage 52 and the master pipe 11, a regulator passage 54 connecting the main passage 52 and the regulator pipe 12, and an accumulator connecting the main passage 52 and the accumulator pipe 13. And a flow path 55. Master channel 53, regulator channel 54, and accumulator channel 55 are connected in parallel to main channel 52.

  Each individual flow path 51FR, 51FL, 51RR, 51RL is provided with an ABS holding valve 61FR, 61FL, 61RR, 61RL in the middle thereof. The ABS holding valve 61 is a normally-open electromagnetic on-off valve that maintains a valve open state by a biasing force of a spring when the solenoid is not energized and is closed only when the solenoid is energized. In the open state, the ABS holding valve 61 can flow the hydraulic fluid in both directions and has no directionality.

  Further, return check valves 62FR, 62FL, 62RR, 62RL are provided in parallel to the ABS holding valves 61FR, 61FL, 61RR, 61RL in the individual flow paths 51FR, 51FL, 51RR, 51RL. The return check valve 62 is a valve that blocks the flow of hydraulic fluid from the main flow path 52 toward the wheel cylinder 42 and allows the flow of hydraulic fluid from the wheel cylinder 42 toward the main flow path 52. That is, when the hydraulic pressure of the wheel cylinder 42 (referred to as wheel cylinder pressure) is higher than the hydraulic pressure of the main flow path 52, the valve body is mechanically opened and the hydraulic fluid in the wheel cylinder 42 is caused to flow toward the main flow path 52. The valve element is configured to close when the wheel cylinder pressure becomes equal to the hydraulic pressure in the main flow path 52. Therefore, when the ABS holding valve 61 is closed and the wheel cylinder pressure is held, if the control hydraulic pressure in the main flow path 52 decreases and falls below the wheel cylinder pressure, the ABS holding valve 61 is closed. The wheel cylinder pressure can be reduced to the control fluid pressure of the main flow path 52 while maintaining the state.

  In addition, the individual flow paths 56FR, 56FL, 56RR, 56RL for decompression are connected to the individual flow paths 51FR, 51FL, 51RR, 51RL, respectively. Each decompression individual channel 56 is connected to a reservoir channel 57. The reservoir channel 57 is connected to the reservoir 24 via the reservoir pipe 14. ABS pressure reducing valves 63FR, 63FL, 63RR, 63RL are provided in the middle of the individual pressure reducing flow paths 56FR, 56FL, 56RR, 56RL, respectively. Each ABS pressure reducing valve 63 is a normally closed electromagnetic on-off valve that maintains a closed state by a biasing force of a spring when the solenoid is not energized and opens only when the solenoid is energized. Each ABS pressure reducing valve 63 reduces the wheel cylinder pressure by flowing the hydraulic fluid from the wheel cylinder 42 to the reservoir flow path 57 via the pressure reducing individual flow path 56 in the open state.

  The ABS holding valve 61 and the ABS pressure-reducing valve 63 are controlled to open and close when an anti-lock brake control is activated to reduce the wheel cylinder pressure and prevent the wheels from being locked when the wheels are locked and slip.

  The main flow path 52 is provided with a communication valve 64 in the middle thereof. The communication valve 64 is a normally-closed electromagnetic on-off valve that maintains a closed state by a biasing force of a spring when the solenoid is not energized and opens only when the solenoid is energized. The main flow path 52 is divided into a first main flow path 521 connected on one side to the master flow path 53 and a second main flow path 522 connected on the other side to the regulator flow path 54 and the accumulator flow path 55 with the communication valve 64 as a boundary. Is done. When the communication valve 64 is in the closed state, the flow of the hydraulic fluid between the first main flow path 521 and the second main flow path 522 is blocked, and when the communication valve 64 is in the open state, the first main flow path 521 is closed. And the second main flow path 522 are allowed to flow in both directions.

  The master flow path 53 is provided with a master cut valve 65 in the middle thereof. The master cut valve 65 is a normally-open electromagnetic on-off valve that maintains a valve open state by the biasing force of a spring when the solenoid is not energized and is closed only when the solenoid is energized. When the master cut valve 65 is in the closed state, the flow of hydraulic fluid between the master cylinder 22 and the first main flow path 521 is interrupted, and when the master cut valve 65 is in the open state, the master cylinder 22 and the first main flow path 521 are closed. The flow of the hydraulic fluid between the 1 main flow path 521 is allowed in both directions.

  In the master channel 53, a simulator channel 71 is branched and provided on the master cylinder 22 side from the position where the master cut valve 65 is provided. A stroke simulator 70 is connected to the simulator flow path 71 via a simulator cut valve 72. The simulator cut valve 72 is a normally closed electromagnetic on-off valve that maintains a closed state by a biasing force of a spring when the solenoid is not energized and is opened only when the solenoid is energized. When the simulator cut valve 72 is in the closed state, the flow of hydraulic fluid between the master flow path 53 and the stroke simulator 70 is interrupted, and when the simulator cut valve 72 is in the open state, the stroke of the master flow path 53 and The flow of the hydraulic fluid between the simulator 70 is allowed in both directions.

  The stroke simulator 70 includes a plurality of pistons and springs. When the simulator cut valve 72 is in an open state, the stroke simulator 70 is operated by introducing an amount of hydraulic fluid corresponding to the amount of brake operation. And a reaction force according to the pedal operation amount is generated to improve the driver's brake operation feeling.

  The regulator flow path 54 is provided with a regulator cut valve 66 in the middle thereof. The regulator cut valve 66 is a normally open electromagnetic on-off valve that maintains the valve open state by the biasing force of the spring when the solenoid is not energized and is closed only when the solenoid is energized. When the regulator cut valve 66 is in the closed state, the flow of hydraulic fluid between the regulator 23 and the second main flow path 522 is interrupted, and when the regulator cut valve 66 is in the open state, the regulator 23 and the second main flow The flow of hydraulic fluid to and from the path 522 is allowed in both directions.

  The accumulator channel 55 is provided with a pressure increasing linear control valve 67A in the middle thereof. The second main flow path 522 to which the accumulator flow path 55 is connected is connected to the reservoir flow path 57 via the pressure-reducing linear control valve 67B. The pressure-increasing linear control valve 67A and the pressure-decreasing linear control valve 67B are normally maintained in a closed state by the spring urging force when the solenoid is not energized, and increase in opening as the energization amount (current value) to the solenoid increases. It is a closed electromagnetic linear control valve. The pressure-increasing linear control valve 67A and the pressure-decreasing linear control valve 67B are configured so that the spring is biased by the force by which the spring urges the valve body in the valve closing direction and the differential pressure between the primary side (inlet side) and the secondary side (outlet side). When the valve closing force, which is the difference from the force urged in the valve opening direction, is maintained, and the force that opens the valve element generated by energizing the solenoid exceeds this valve closing force. The valve is opened at an opening corresponding to the balance of the force acting on the valve body. Therefore, the opening degree can be adjusted by controlling the energization amount (current value) to the solenoid. The pressure-increasing linear control valve 67A and the pressure-decreasing linear control valve 67B correspond to the linear control valve in the present invention. Hereinafter, when it is not necessary to distinguish between the pressure-increasing linear control valve 67A and the pressure-decreasing linear control valve 67B, they are collectively referred to as the linear control valve 67.

  The power hydraulic pressure generating device 30 and the hydraulic pressure control valve device 50 are driven and controlled by the brake ECU 100. The brake ECU 100 includes a microcomputer as a main part, and also includes a pump drive circuit, an electromagnetic valve drive circuit, an input interface for inputting various sensor signals, a communication interface, and the like. The electromagnetic open / close valve and the linear control valve 67 provided in the hydraulic control valve device 50 are all connected to the brake ECU 100, and the open / close state and the opening degree (in the case of the linear control valve 67) by a solenoid drive signal output from the brake ECU 100. Is controlled. Further, the motor 33 provided in the power hydraulic pressure generator 30 is also connected to the brake ECU 100 and driven and controlled by a motor drive signal output from the brake ECU 100.

  The hydraulic pressure control valve device 50 is provided with an accumulator pressure sensor 101, a regulator pressure sensor 102, and a control pressure sensor 103. The accumulator pressure sensor 101 detects an accumulator pressure Pacc that is the pressure of the working fluid in the accumulator flow channel 55 on the power hydraulic pressure generator 30 side (upstream side) from the pressure-increasing linear control valve 67A. The accumulator pressure sensor 101 outputs a signal representing the detected accumulator pressure Pacc to the brake ECU 100. The brake ECU 100 reads the accumulator pressure Pacc at a predetermined cycle. When the accumulator pressure Pacc falls below a preset minimum set pressure, the brake ECU 100 drives the motor 33 to pressurize the hydraulic fluid by the pump 31, and the accumulator pressure Pacc is always set. Control to maintain pressure range.

  The regulator pressure sensor 102 detects the regulator pressure Preg that is the pressure of the hydraulic fluid in the regulator flow path 54 on the regulator 23 side (upstream side) than the regulator cut valve 66. The regulator pressure sensor 102 outputs a signal representing the detected regulator pressure Preg to the brake ECU 100. The control pressure sensor 103 outputs a signal representing the control pressure Px that is the pressure of the hydraulic fluid in the first main flow path 521 to the brake ECU 100.

  The brake ECU 100 is connected to a stroke sensor 104 provided on the brake pedal 10. The stroke sensor 104 detects a pedal stroke that is a depression amount (operation amount) of the brake pedal 10 and outputs a signal representing the detected pedal stroke Sp to the brake ECU 100. A wheel speed sensor 105 is connected to the brake ECU 100. The wheel speed sensor 105 detects the wheel speed, which is the rotational speed of the left and right front and rear wheels, and outputs a signal representing the detected wheel speed Vx to the brake ECU 100. The wheel speed Vx is used for detection of a rotation period of a wheel, which will be described later, and detection of a vehicle speed.

  Next, brake control executed by the brake ECU 100 will be described. The brake ECU 100 adjusts the hydraulic pressure output from the power hydraulic pressure generator 30 by the linear control valve 67 and transmits it to the wheel cylinder 42, and transmits the hydraulic pressure generated by the driver's stepping force to the wheel cylinder. Brake control is selectively executed in at least two braking modes including the backup mode. Since the feature in the present embodiment is applied in the linear control mode, description of the backup mode is omitted.

  In the linear control mode, the master cut valve 65 and the regulator cut valve 66 are kept closed by energizing the solenoid, and the communication valve 64 is kept open by energizing the solenoid. Further, the simulator cut valve 72 is maintained in an open state by energizing the solenoid. Further, the pressure-increasing linear control valve 67A and the pressure-decreasing linear control valve 67B are controlled to the opening degree corresponding to the energization amount when the solenoid is in the energization control state. The ABS holding valve 61 and the ABS pressure reducing valve 63 are opened and closed as necessary, such as anti-lock brake control. Normally, the ABS holding valve 61 is maintained in an open state, and the ABS pressure reducing valve 63 is in a closed state. Maintained.

  In the linear control mode, the master cut valve 65 and the regulator cut valve 66 are closed, so that the hydraulic pressure output from the master cylinder unit 20 is not transmitted to the wheel cylinder 42. Further, the communication valve 64 is maintained in the open state, and the pressure-increasing linear control valve 67A and the pressure-decreasing linear control valve 67B are put in the energization control state. Therefore, the hydraulic pressure (accumulator pressure) output from the power hydraulic pressure generator 30 is adjusted by the pressure-increasing linear control valve 67A and the pressure-decreasing linear control valve 67B and transmitted to the four-wheel wheel cylinder 42. In this case, since each wheel cylinder 42 is communicated by the main flow path 52, the wheel cylinder pressure is the same for all four wheels. This wheel cylinder pressure can be detected by the control pressure sensor 103.

  The vehicle provided with the brake control device of the present embodiment is, for example, a hybrid vehicle including a motor driven by a battery power source and an internal combustion engine driven by gasoline fuel. In a hybrid vehicle, regenerative braking is performed in which a motor is generated by the rotational force of a wheel and braking power is obtained by regenerating the generated power in a battery. When performing such regenerative braking, regenerative braking and hydraulic braking are used in combination by generating a braking force, which is the total braking force required to brake the vehicle, excluding the regenerative braking force by the brake control device. Brake regeneration cooperative control can be performed.

  The brake ECU 100 starts the brake regeneration cooperative control in response to the braking request. The braking request is generated when a braking force should be applied to the vehicle, for example, when the driver depresses the brake pedal 10. When receiving a braking request, the brake ECU 100 calculates a target braking force based on the pedal stroke Sp detected by the stroke sensor 104. The target braking force is set to a larger value as the pedal stroke Sp is larger. Instead of the pedal stroke Sp detected by the stroke sensor 104, the brake operation amount may be detected based on the regulator pressure Preg detected by the regulator pressure sensor 102. In addition, a pedal force sensor that detects the depression force of the brake pedal 10 may be provided to detect the brake operation amount based on the pedal force.

  The brake ECU 100 transmits information representing the calculated target braking force to the hybrid ECU (not shown). The hybrid ECU calculates a braking force generated by power regeneration from the target braking force, and transmits information representing the regenerative braking force, which is the calculation result, to the brake ECU 100. Thus, the brake ECU 100 calculates a target hydraulic braking force that is a braking force to be generated by the brake control device by subtracting the regenerative braking force from the target braking force. The regenerative braking force generated by the power regeneration performed by the hybrid ECU not only changes depending on the rotation speed of the motor, but also changes due to the regenerative current control depending on the state of charge (SOC) of the battery. Accordingly, an appropriate target hydraulic braking force can be calculated by subtracting the regenerative braking force from the target braking force.

  The brake ECU 100 calculates the target hydraulic pressure of each wheel cylinder 42 corresponding to the target hydraulic braking force based on the calculated target hydraulic braking force, and performs feedback control so that the wheel cylinder pressure becomes equal to the target hydraulic pressure. The drive current of the pressure-increasing linear control valve 67A and the pressure-decreasing linear control valve 67B is controlled. That is, the current flowing through the solenoids of the pressure-increasing linear control valve 67A and the pressure-decreasing linear control valve 67B is controlled so that the control pressure Px (= wheel cylinder pressure) detected by the control pressure sensor 103 follows the target hydraulic pressure. .

  Thereby, hydraulic fluid is supplied to each wheel cylinder 42 from the power hydraulic pressure generator 30 via the pressure-increasing linear control valve 67A, and braking force is generated on the wheels. Further, if necessary, the hydraulic fluid is discharged from the wheel cylinder 42 via the pressure-reducing linear control valve 67B, and the braking force generated on the wheel is adjusted.

  In addition, since this invention does not make it essential to perform brake regenerative cooperative control, it is applicable also to the vehicle which does not generate | occur | produce regenerative braking force. In this case, the target hydraulic pressure may be directly calculated based on the brake operation amount. The target hydraulic pressure is set to a larger value as the brake operation amount increases, for example, using a map or a calculation formula.

As described above, in the linear control mode, the brake ECU 100 controls the linear control valve so that the control pressure Px detected by the control pressure sensor 103 (hereinafter referred to as the detected hydraulic pressure Px) follows the target hydraulic pressure P ^*. The electric current which flows into each solenoid of 67 (pressure increase linear control valve 67 and pressure reduction linear control valve 67B) is controlled. When performing such current control, the brake ECU 100 sets a dead zone in which the linear control valve 67 is not energized. The dead zone is set with a predetermined width on the plus side and the minus side around the target hydraulic pressure P ^* . When the detected hydraulic pressure Px is in the dead zone, the brake ECU 100 does not energize the linear control valve 67, and if the detected hydraulic pressure Px is out of the dead zone, the deviation between the target hydraulic pressure P ^* and the detected hydraulic pressure Px. Accordingly, the energization of the linear control valve 67 is controlled so that the deviation approaches zero. For example, feedback control such as PID control using a deviation (P ^* −Px) between the target hydraulic pressure P ^* and the detected hydraulic pressure Px is performed.

Since the dead zone boundary is a point at which energization of the linear control valve 67 is started, in this embodiment, the width from the target hydraulic pressure P ^* to the dead zone boundary is referred to as a control start threshold value X. The control start threshold value may be defined as the target hydraulic pressure P ^* ± (dead zone width). In this embodiment, since the width of the dead zone is variable, the width from the target hydraulic pressure to the boundary of the dead zone is defined as a control start threshold so that the description is not complicated, and control of changing the width of the dead zone is started. Treated as the same meaning as changing the threshold. Further, in the present embodiment, the control start threshold value has the same value on the plus side and the value on the minus side with respect to the target hydraulic pressure P ^* , but may be different from each other.

  In the brake unit 40, the brake pad is pressed against the rotating brake disc 41 to apply a braking force to the wheel. However, as the brake pad and the brake disc 41 slide, the thickness of the brake disc 41 decreases, Wall thickness differences may occur. In this case, when the brake disk 41 is rotating, the piston in the wheel cylinder 42 is moved due to the thickness difference, and the hydraulic pressure in the wheel cylinder 42 pulsates.

  In the present embodiment, a disc brake is used, but a drum brake can be used instead. In the case of a drum brake, a drum that can rotate integrally with a wheel, a pair of shoes provided inside the drum, and a wheel cylinder that expands the shoe is provided, and hydraulic pressure is supplied to the wheel cylinder. As a result, the pair of shoes expands and presses the inner peripheral surface of the drum to apply a braking force to the wheels. In the case of a drum brake, if the drum is installed with the drum rotation center axis eccentric with respect to the wheel rotation center axis, or if the drum is not round, the drum rotates. The piston of the wheel cylinder is moved while the fluid pressure of the wheel cylinder is pulsating.

Therefore, in both the disc brake and the drum brake, when the above situation occurs, the brake vibration is generated. Further, the pulsation of the hydraulic pressure is transmitted to the control pressure sensor 103 through a propagation path (an example of the left rear wheel) shown in FIG. For this reason, as shown in the upper graph of FIG. 3, when the detected hydraulic pressure Px pulsates and the deviation between the detected hydraulic pressure Px and the target hydraulic pressure P ^* periodically exceeds the control start threshold value X, 3, the linear control valve 67 repeats the valve opening operation and the valve closing operation. That is, the linear control valve 67 operates excessively. Thereby, the durable life of the linear control valve 67 is reduced.

  Therefore, in this embodiment, when the hydraulic pressure of the working fluid is pulsating, the control start threshold value is changed so that the linear control valve 67 does not operate excessively. If the control start threshold value X is increased, the linear control valve 67 can be prevented from operating excessively. However, as a contradiction, the control start timing of the linear control valve 67 is delayed, which is not preferable as a brake operation feeling. . Therefore, it is desired to set the control start threshold value X so that the brake operation feeling is established and the linear control valve 67 does not operate excessively.

  The amplitude of the hydraulic fluid pulsation has a characteristic that it varies depending on the hydraulic rigidity. Further, the hydraulic rigidity and the hydraulic pressure of the hydraulic fluid have a correlation, and the higher the hydraulic pressure, the higher the hydraulic rigidity. Therefore, the amplitude of hydraulic fluid pulsation varies depending on the hydraulic pressure. FIG. 4 is experimental data showing the relationship (amplitude characteristics) between the hydraulic pressure of the hydraulic fluid and the pulsation width. In this figure, the hydraulic pressure on the horizontal axis is the central value of hydraulic fluid pulsation (average value of hydraulic pressure). As shown in the figure, in the region where the hydraulic pressure is equal to or lower than Pa, the amplitude of the pulsation decreases as the hydraulic pressure decreases, and increases as the hydraulic pressure increases. In the region where the hydraulic pressure exceeds Pa, the pulsation amplitude gradually decreases as the hydraulic pressure increases.

  Moreover, there exists the following tendency about the relationship between hydraulic pressure and brake response. When the hydraulic pressure is low, the hydraulic stiffness is low and the amount of ineffective liquid is large, so that the hydraulic pressure of the wheel cylinder is less likely to increase than when the hydraulic pressure is high. Therefore, it is desired to speed up the control start point of the linear control valve 67.

  Therefore, in the present embodiment, the control start threshold value X indicated by the solid line in FIG. 5 is set in consideration of the relationship between the fluid pressure and the pulsation amplitude and the relationship between the fluid pressure and the brake response. That is, the control start threshold value X in the low hydraulic pressure region where the hydraulic pressure is less than Pb is set smaller than the control start threshold value X in the high hydraulic pressure region where the hydraulic pressure is equal to or higher than Pb. The brake operation area normally used is this low hydraulic pressure area. Further, in the low hydraulic pressure region, a control start threshold value X that increases as the hydraulic pressure increases (decreases as the hydraulic pressure decreases) is set. In the high hydraulic pressure region, a constant control start threshold value X is set. Set. The brake ECU 100 stores a control start threshold setting map that represents the relationship between the hydraulic pressure and the control start threshold X. The relationship between the hydraulic pressure and the control start threshold value X is not limited to a map, and may be stored using a calculation formula or the like.

  Next, a variable threshold control process executed by the brake ECU 100 will be described. FIG. 6 is a flowchart showing a threshold variable control routine. The variable threshold control routine is repeatedly executed at a predetermined short period in parallel with the brake control (energization control of the linear control valve 67) described above.

  When the threshold variable control routine is started, the brake ECU 100 reads the pedal stroke Sp detected by the stroke sensor 104 in step S11, and based on the pedal stroke Sp and the differential value (change amount per unit time) of the pedal stroke Sp. Then, it is determined whether or not the brake pedal 10 is being held. If the pedal stroke Sp is larger than the operation presence / absence determination reference value and the absolute value of the differential value Sp ′ of the pedal stroke Sp is equal to or less than the holding determination reference value, it is determined that the brake pedal 10 is in the holding operation ( S11: Yes), otherwise, it is determined that the brake pedal 10 is not in a holding operation (S11: No).

Since the determination processing in step S11 is to detect the operation amount of the brake pedal 10 and its change, the regulator pressure Preg detected by the regulator pressure sensor 102 and its differential value are used instead of the pedal stroke Sp. May be used, or may be determined by other methods such as using the target hydraulic pressure P ^* calculated by the brake control and its differential value.

  If the brake ECU 100 determines in step S11 that the brake pedal 10 is not in a holding operation, the brake ECU 100 sets the control start threshold value X to the normal control start threshold value X0 in step S12. The normal control start threshold value X0 represents a normal value that does not increase the control start threshold value X. The normal control start threshold value X0 is set to a constant value that is less than or equal to the control start threshold value X that is changed and set in step S16 described later.

Since the target hydraulic pressure P ^* changes when the brake pedal 10 is stepped on or returned, the brake ECU 100 continuously outputs a pressure increase command or a pressure reduction command. For this reason, even if hydraulic pressure pulsation occurs in the wheel cylinder 42, the linear control valve 67 does not operate excessively (the opening and closing operation is not repeated). Accordingly, the linear control valve 67 is not in an excessively activated state when the brake pedal 10 is stepped on or returned.

  Further, if the control start threshold value X is changed (increased) when the brake pedal 10 is stepped on or returned, the brake operation feeling is likely to change. On the other hand, at the time of the pedal holding operation where the driver's willingness to operate the pedal is small, the change in the brake operation feeling is very small even if the control start threshold value X is changed. Therefore, in this embodiment, it is set as the timing which can change the control start threshold value X in a pedal holding | maintenance operation state.

  If the brake ECU 100 determines that the brake pedal 10 is being held, the brake ECU 100 reads the wheel speed Vx detected by the wheel speed sensor 105 in the subsequent step S13, and the vehicle is traveling based on the wheel speed Vx. It is determined whether or not. For example, it is determined whether or not the wheel speed Vx is greater than zero. The wheel speed sensor 105 detects the wheel speed Vx for each wheel. Here, the wheel speed Vx of an arbitrary wheel may be read, or the wheel speed Vx of four wheels may be read and the average value thereof may be calculated as the wheel speed. Vx may be used as long as it can determine the running state of the vehicle.

  In a state where the vehicle is not running, because the wheels do not rotate (the brake disc 41 or the brake drum does not rotate), the piston in the wheel cylinder 42 is not moved. For this reason, hydraulic pulsation caused by an unbalanced structure of the brake unit 40 (non-uniform thickness of the brake disc, poor roundness of the drum, etc.) does not occur. If the brake ECU 100 determines that the vehicle is not traveling, there is no need to change the control start threshold value X. Therefore, the process proceeds to step S12, and the control start threshold value X is set to the normal control start threshold value X0. To do.

  If the brake ECU 100 determines that the vehicle is running, the brake ECU 100 performs pulsation detection processing in subsequent step S14, and in subsequent step S15, reads the determination result of the pulsation detection processing to determine whether pulsation is detected. Judging. The pulsation detection process will be described later. If no pulsation is detected (S15: No), there is no need to change (increase) the control start threshold value X. Therefore, in step S12, the control start threshold value X is set to the normal control start threshold value X0.

  On the other hand, if pulsation is detected (S15: Yes), the process proceeds to step S16. In step S16, the brake ECU 100 sets a control start threshold value X corresponding to the hydraulic pressure of the hydraulic fluid with reference to a control start threshold value setting map indicated by a solid line in FIG. In this case, since the detected hydraulic pressure Px detected by the control pressure sensor 103 is pulsating, the brake ECU 100 sets the detected hydraulic pressure Px to the pulsation center value of the detected hydraulic pressure Px by performing low-pass filtering and averaging. The corresponding fluid pressure Pxave is calculated, and the control start threshold value X corresponding to the fluid pressure Pxave is obtained from the control start threshold value setting map. In this case, the hydraulic pressure Pxave may be calculated from, for example, an average value of the detected hydraulic pressure Px during one rotation of the wheel. The period during which the wheel rotates once may be obtained from the wheel speed Vx detected by the wheel speed sensor 105.

  The control start threshold setting map shown in FIG. 5 starts the control in the low hydraulic pressure region where the hydraulic pressure Pxave is less than Pb, and increases as the hydraulic pressure Pxave increases (decreases as the hydraulic pressure Pxave decreases). A threshold value X is set, and a constant control start threshold value X is set in a high hydraulic pressure region where the hydraulic pressure Pave is equal to or higher than Pb. The control start threshold value X in the high hydraulic pressure region is set to a value larger than the control start threshold value X in the low hydraulic pressure region. Further, the control start threshold value X in the low hydraulic pressure region is set to a value larger than the normal control start threshold value X0. Therefore, when the pulsation of the hydraulic pressure is detected, the control start threshold value X is set larger than the normal control start threshold value X0.

  The threshold variable control routine is repeated at a predetermined short cycle. Therefore, when the pulsation of the hydraulic fluid is detected when the vehicle is running and the brake pedal is being held, the control start threshold value X corresponding to the hydraulic fluid pressure Pxave is set.

Here, the pulsation detection process in step S14 will be described. FIG. 7 shows a pulsation detection routine incorporated as step S14. When the pulsation detection routine is started, the brake ECU 100 reads the detected hydraulic pressure Px detected by the control pressure sensor 103 in step S101, and calculates the current target hydraulic pressure P ^* and the detected hydraulic pressure Px by the following equation. An absolute value ΔP of the deviation (hereinafter referred to as a hydraulic pressure deviation ΔP) is calculated.
ΔP = | P ^* −Px |

  Subsequently, in step S102, the brake ECU 100 determines whether or not the hydraulic pressure deviation ΔP is larger than the normal control start threshold value X0. When the brake ECU 100 determines that the hydraulic pressure deviation ΔP is equal to or less than the normal control start threshold value X, the brake ECU 100 once ends the pulsation detection routine and advances the process to step S15 of the main routine (FIG. 6). In this case, as the pulsation detection determination result, the determination result stored in the memory until immediately before is used. At the start of the pulsation detection routine, the initial value “no pulsation” is used as the determination result.

  If the brake ECU 100 determines in step S102 that the hydraulic pressure deviation ΔP is greater than the normal control start threshold value X0, the brake ECU 100 reads a pulsation cycle detected by a pulsation cycle detection routine described later in step S103. Subsequently, in step S104, the wheel speed Vx detected by the wheel speed sensor 105 is read.

  Subsequently, in step S105, the brake ECU 100 calculates the wheel rotation period (the time required for the wheel to make one rotation) based on the wheel speed Vx, and whether or not the pulsation period is equal to or less than the wheel rotation period. Judging. The wheel speed sensor 105 detects the wheel speed Vx for each wheel. Here, the wheel speed Vx of an arbitrary wheel may be read, or the wheel speed Vx of four wheels may be read and the average value thereof may be calculated as the wheel speed. The wheel speed Vx can be detected by an arbitrary method such as obtaining as Vx.

  If the pulsation period is greater than the rotation period of the wheel, the brake ECU 100 determines that the liquid caused by the unbalanced structure of the brake unit 40 (such as uneven thickness of the brake disk, poor roundness of the drum) in step S106. It is determined that there is no pressure pulsation, that is, no hydraulic pulsation generated from the brake unit 40 (no pulsation). On the other hand, when it is determined in step S105 that the pulsation period is equal to or less than the rotation period of the wheel, the brake ECU 100 causes a hydraulic pressure pulsation due to the unbalanced structure of the brake unit 40 to occur in step S107. It is determined that there is (pulsation).

  Subsequently, in step S108, the brake ECU 100 stores the pulsation determination result in the memory, and advances the processing to step S15 of the main routine (threshold variable control routine in FIG. 6). The pulsation determination result is used for determination in step S15 in the main routine.

  Next, the pulsation cycle detection routine will be described. FIG. 8 is a flowchart showing a pulsation cycle detection routine executed by the brake ECU 100. The pulsation cycle detection routine is repeatedly executed at a predetermined short cycle in parallel with the above pulsation detection routine.

  In step S121, the brake ECU 100 determines whether or not the timer flag F is set to “0”. This timer flag F indicates whether or not a clock timer described later is measuring time, and is set to “0” when the pulsation cycle detection routine is started. If the brake ECU 100 determines “Yes” in step S121, then, in step S122, the hydraulic pressure deviation ΔP (n−1) detected until immediately before is smaller than the pulsation detection threshold value P1 and is detected this time. It is determined whether or not the hydraulic pressure deviation ΔP (n) exceeds the pulsation detection threshold value P1. As the hydraulic pressure deviation ΔP, the result calculated in step S101 of the pulsation detection routine described above can be used. In addition, the hydraulic pressure deviation ΔP (n) detected this time may be a value obtained from the current detected value, but it is preferable to use the average value of the most recent detected values. Similarly, the hydraulic pressure deviation ΔP (n−1) that has been detected until immediately before may be a value obtained from the previous detection value of the previous time, but it is earlier than the detection value used for the calculation for this time. It is preferable to use an average value of a plurality of detection values.

  The determination in step S122 is a process for determining whether or not the hydraulic pressure deviation ΔP is the timing at which the pulsation detection threshold value P1 crosses (crosses from small to large) as shown at time t1 in FIG. . The pulsation detection threshold value P1 is set to a value that is ½ of the normal control start threshold value X0. If the determination in step S122 is “No”, the brake ECU 100 once ends the pulsation cycle detection routine. The brake ECU 100 repeats such processing at a predetermined cycle.

  When the brake ECU 100 detects the timing at which the hydraulic pressure deviation ΔP crosses the pulsation detection threshold value P1 (S122: Yes), the brake ECU 100 sets the timer flag F to “1” in the subsequent step S123. Subsequently, in step S124, the value T of the timer is incremented by 1. In other words, timing is started. The initial value of the timer value T is set to zero.

  Subsequently, in step S125, the brake ECU 100 detects that the hydraulic pressure deviation ΔP (n−1) detected until immediately before is smaller than the pulsation detection threshold value P1, and the detected hydraulic pressure deviation ΔP (n) is pulsation detected. It is determined whether or not the threshold value P1 is exceeded. This step S125 is a determination process for detecting the next timing when the hydraulic pressure deviation ΔP crosses the pulsation detection threshold value P1 (crosses from small to large). For example, it is a determination process for detecting the timing at time t2 in FIG. In this case, when the process proceeds from step S124 to step S125, it is preferable not to determine “Yes” at the overlapping timing by waiting for a predetermined time and updating the read value of the hydraulic pressure deviation ΔP.

  If the determination in step S125 is “No”, the brake ECU 100 once ends the pulsation cycle detection routine. The brake ECU 100 starts the pulsation cycle detection routine again when a predetermined interval elapses. In this case, since the timer flag F is set to “1”, the processing of steps S122 to S123 is skipped. . Therefore, the brake ECU 100 repeats the determination in step S125 at a predetermined cycle while incrementing the time count timer value T (S124).

  When the brake ECU 100 repeats such processing and detects that the hydraulic pressure deviation ΔP crosses the pulsation detection threshold value P1 (from small to large) (S125: Yes), the brake ECU 100 pulsates the time corresponding to the time count timer value T in step S126. Set as period. Subsequently, the time count timer value T is cleared to zero in step S127, the timer flag F is reset to “0” in step S128, and the pulsation cycle detection routine is once ended.

  In this embodiment, the timing at which the hydraulic pressure deviation ΔP shifts from a state where the hydraulic pressure deviation ΔP is smaller than the pulsation detection threshold value P1 is captured, but the hydraulic pressure deviation ΔP decreases from a state where the hydraulic pressure deviation ΔP is larger than the pulsation detection threshold value P1. The timing (time t1 ′ and time t2 ′ in FIG. 9) may be captured.

  According to the brake control device of the present embodiment described above, it is determined whether or not the hydraulic fluid is pulsating, and when the hydraulic fluid is pulsating, the control start threshold value X is set higher than the normal control start threshold value X0. increase. In this case, with reference to a control start threshold setting map set in consideration of the relationship between the hydraulic pressure and the pulsation amplitude and the relationship between the hydraulic pressure and the brake response, the control start threshold corresponding to the hydraulic pressure Pxave of the hydraulic fluid Set X. Therefore, when the hydraulic pressure Pxave enters the low hydraulic pressure region, the control start threshold value X is set to be smaller as the hydraulic pressure Pxave is reduced in accordance with the pulsation amplitude characteristics (the amount of increase from the normal control start threshold value X0 is increased). Therefore, excessive operation (repeated operation of opening and closing) of the linear control valve 67 can be suppressed while maintaining brake response. Further, when the hydraulic pressure Pxave enters the high hydraulic pressure region, a large control start threshold value X is set (because the amount of increase from the normal control start threshold value X0 is set large). Can be suppressed.

  Therefore, according to the brake control device of the present embodiment, it is possible to ensure the reliability of the linear control valve 67 by suppressing the excessive operation of the linear control valve 67 while establishing the brake operation feeling. That is, both the brake operation feeling and the reliability of the linear control valve 67 can be achieved.

  Further, in the present embodiment, the control start threshold value X is changed in an appropriate situation in order to change the control start threshold value X on condition that a hydraulic pressure pulsation is detected during a brake holding operation during vehicle travel ( Increase). Therefore, it is possible to prevent the brake operation feeling from being changed by changing the control start threshold value X unnecessarily.

Further, when detecting the pulsation of the hydraulic pressure, it is determined whether or not the hydraulic pressure deviation ΔP is larger than the normal control start threshold value X0, so that the pulsation of the hydraulic pressure at which the linear control valve 67 operates excessively is reliably detected. can do. Further, when the cycle of pulsation is longer than the cycle of one rotation of the wheel, it is determined that the pulsation is not hydraulic pulsation generated from the brake unit 40 (no pulsation), and the control start threshold value X is not changed. However, it is possible to prevent the brake operation feeling from being changed by changing the control start threshold value X unnecessarily. For example, when hydraulic fluid leaks due to aging deterioration of parts such as valves, as shown in FIG. 10, the detected hydraulic pressure Px is lowered and then regulated by the linear control valve 67 to achieve the target hydraulic pressure. Approaches P ^* . Accordingly, the detected hydraulic pressure Px repeatedly fluctuates due to the hydraulic pressure adjustment, so that it is erroneously determined as a hydraulic pressure pulsation. Even in such a case, in the present embodiment, erroneous determination can be suppressed by determining the pulsation cycle.

In the above description, in setting the control start threshold value X, the fluid pressure Pxave obtained by averaging the detected fluid pressure Px is used. However, instead of the fluid pressure Pxave, the target fluid pressure P ^* is used to control the control start threshold value X. X may be set. This is because the hydraulic pressure of the hydraulic fluid is controlled so as to approach the target hydraulic pressure P ^* by the feedback control described above, and thus the hydraulic pressure of the hydraulic fluid can be regarded as the target hydraulic pressure P ^* . In this case, the horizontal axis of the control start threshold setting map shown in FIG. 5 may be the target hydraulic pressure P ^* . Further, in step S16 of the variable threshold control routine of FIG. 6, the control start threshold value X corresponding to the target hydraulic pressure P ^* may be obtained from this control start threshold value setting map.

Further, the control start threshold value X may be set using a brake operation amount instead of the hydraulic pressure Pxave. The brake operation amount is used for setting the target hydraulic pressure P ^* . Accordingly, since the hydraulic pressure of the hydraulic fluid also changes according to the magnitude of the brake operation amount, the brake operation amount can be used as a variable for setting the control start threshold value X. In this case, although the relationship between the brake operation amount and the target hydraulic pressure P ^* changes depending on the magnitude of the regenerative braking force, the hydraulic fluid pressure also increases / decreases as the brake operation amount increases / decreases. The liquid pressure of the liquid can be estimated to some extent. If necessary, the brake operation amount may be corrected based on the regenerative braking force information received from the hybrid ECU, and the corrected brake operation amount may be used. Further, if the vehicle does not use the regenerative braking force, the target hydraulic pressure P ^* is uniquely set from the brake operation amount, so that the hydraulic pressure of the hydraulic fluid can be accurately estimated from the brake operation amount.

  As the brake operation amount, a pedal stroke Sp detected by the stroke sensor 104, a regulator pressure Preg detected by the regulator pressure sensor 102, or the like can be used. Further, a pedal force sensor that detects the depression force of the brake pedal 10 may be provided, and the pedal force may be used as the brake operation amount. In this case, the horizontal axis of the control start threshold setting map shown in FIG. In step S16 of the variable threshold control routine of FIG. 6, the control start threshold value X corresponding to the brake operation amount may be obtained from this control start threshold value setting map.

  Next, threshold variable control according to the second embodiment will be described. Hereinafter, the variable threshold control that changes the control start threshold according to the above-described hydraulic pressure is referred to as a first embodiment. In the variable threshold control of the second embodiment, the control start threshold X is changed according to the vehicle speed.

  The hydraulic pressure pulsation amplitude of hydraulic fluid is characterized in that it varies depending on the vehicle speed. FIG. 11 shows experimental data representing the relationship between the vehicle speed and the pulsation amplitude of the hydraulic fluid (amplitude characteristics). FIG. 11 shows amplitude characteristics for six hydraulic pressures. As shown in the figure, the amplitude of the pulsation has a characteristic that it decreases as the vehicle speed increases (increases as the vehicle speed decreases).

  Further, the relationship between the vehicle speed and the brake operation sensitivity has the following tendency. The response delay increases as the control start threshold increases. Therefore, if the control start threshold is set small so that the driver does not feel a delay in response to braking force during high-speed driving, depending on the driver, braking control operation may become difficult or braking may be too effective during low-speed driving. I sometimes feel it.

  Therefore, in the second embodiment, the control start threshold value X shown by the solid line in FIG. 12 is set in consideration of the relationship between the vehicle speed and the pulsation amplitude and the relationship between the vehicle speed and the brake operation sensitivity. That is, the control start threshold value X is set such that it decreases as the vehicle speed increases (increases as the vehicle speed decreases). The brake ECU 100 stores a control start threshold setting map representing the relationship between the vehicle speed and the control start threshold X. The control start threshold value X in this control start threshold value setting map is set to a value larger than the normal control start threshold value X0. The relationship between the hydraulic pressure and the control start threshold value X is not limited to a map, and may be stored using a calculation formula or the like.

  Next, the threshold variable control process of the second embodiment executed by the brake ECU 100 will be described. FIG. 13 is a flowchart showing a threshold variable control routine of the second embodiment. The threshold variable control routine performs the process of step S26 instead of the process of step S16 of the threshold variable control routine of the first embodiment, and other processes (including a pulsation detection process and a pulsation cycle detection process) are also performed. The same as in the first embodiment.

  If the brake ECU 100 determines that there is pulsation in step S15, the brake ECU 100 refers to the control start threshold setting map shown by the solid line in FIG. In this case, the brake ECU 100 reads the wheel speed Vx detected by the wheel speed sensor 105, and obtains the control start threshold value X corresponding to the vehicle speed V determined from the wheel speed Vx from the control start threshold value setting map. Note that it is not necessary to distinguish between the vehicle speed and the wheel speed as a parameter that affects the amplitude characteristic of the hydraulic pressure, and in the present invention, both are treated as equivalent. Hereinafter, the wheel speed Vx and the vehicle speed V are collectively referred to as a vehicle speed V. Therefore, the control start threshold value setting map may store the relationship between the wheel speed Vx and the control start threshold value X. Further, instead of reading the detection value of the wheel speed sensor 105, for example, vehicle speed information may be read via a CAN communication line or the like, and the vehicle speed for detecting the vehicle speed (including wheel speed) in the brake control device. What is necessary is just to provide the detection means.

  As in the first embodiment, the brake ECU 100 repeatedly executes the variable threshold control routine at a predetermined short cycle.

  According to the second embodiment, it is determined whether or not the hydraulic fluid is pulsating. When the hydraulic fluid is pulsating, the control start threshold value X is increased more than the normal control start threshold value X0. In this case, the control start threshold value X corresponding to the vehicle speed V is set with reference to the control start threshold value setting map set in consideration of the relationship between the vehicle speed and the pulsation amplitude and the relationship between the vehicle speed and the brake operation sensitivity.

  Therefore, the control start threshold value X is set small during high-speed driving where brake response is required (because the amount of increase from the normal control start threshold value X0 is set small), the driver feels a delay in brake response. I won't let you. Further, during high speed traveling, the pulsation amplitude becomes small, so that excessive operation of the linear control valve 67 can be suppressed.

  In addition, during low speed travel where the pulsation amplitude increases, the control start threshold value X is set to be large (because the amount of increase from the normal control start threshold value X0 is set to be large). Can be suppressed.

  As a result, according to the second embodiment, it is possible to suppress the excessive operation of the linear control valve 67 while ensuring the brake operation feeling and to ensure the reliability of the linear control valve 67.

In the second embodiment, the control start threshold value X is uniquely set from the vehicle speed V. However, the control start threshold value X may be set by combining the hydraulic pressure and the vehicle speed. For example, as shown in FIG. 14, a control start threshold setting map in which a control start threshold X corresponding to the vehicle speed V is set for each of a plurality of representative hydraulic pressures Pxave1 to PxaveN is stored in the microcomputer of the brake ECU 100. In the threshold change processing routine, the control start threshold setting map of the hydraulic pressure Pxave closest to the detected hydraulic pressure Pxave is selected, and the control start is started based on the vehicle speed V with reference to the selected control start threshold setting map. The threshold value X may be calculated. In setting the control start threshold value setting map, it may be set based on the experimental data shown in FIG. A three-dimensional map that calculates the control start threshold value X from the vehicle speed V and the hydraulic pressure Pxave can also be used. In this modification, as described above, the target hydraulic pressure P ^* and the brake operation amount can be used instead of the hydraulic pressure Pxave.

  Next, the threshold variable control process of the third embodiment that combines the first embodiment and the second embodiment will be described. FIG. 15 is a flowchart illustrating a threshold variable control routine according to the third embodiment. The threshold variable control routine is obtained by adding the processes of step S17 to step S20 after the process of step S16 of the threshold variable control routine of the first embodiment, and includes other processes (including a pulsation detection process and a pulsation cycle detection). ) Is the same as in the first embodiment.

  In step S16, the brake ECU 100 calculates the control start threshold value X corresponding to the hydraulic fluid pressure Pxave from the control start threshold value setting map shown in FIG. This control start threshold value X is referred to as a hydraulic pressure corresponding control start threshold value X1. Subsequently, in step S17, the brake ECU 100 calculates a control start threshold value X corresponding to the vehicle speed V from the control start threshold value setting map shown in FIG. The control start threshold value X corresponding to the vehicle speed V is referred to as a vehicle speed corresponding control start threshold value X2. The process of step S17 is the same as the process of step S26 of the second embodiment.

  Subsequently, in step S18, the brake ECU 100 compares the hydraulic pressure corresponding control start threshold value X1 with the vehicle speed corresponding control start threshold value X2, and determines whether or not the hydraulic pressure corresponding control start threshold value X1 is larger than the vehicle speed corresponding control start threshold value X2. Judging. If the hydraulic pressure corresponding control start threshold value X1 is larger than the vehicle speed corresponding control start threshold value X2, the final control start threshold value X is set to the hydraulic pressure corresponding control start threshold value X1 in step S19. If the start threshold value X2 is equal to or greater than the hydraulic pressure corresponding control start threshold value X1, the final control start threshold value X is set to the vehicle speed corresponding control start threshold value X2 in step S20.

  As in the first embodiment, the brake ECU 100 repeatedly executes the variable threshold control routine at a predetermined short cycle.

  According to the third embodiment, the hydraulic pressure corresponding control start threshold value X1 and the vehicle speed corresponding control start threshold value X2 are respectively calculated, and the larger value is set as the control start threshold value X. Therefore, the excessive operation of the linear control valve 67 can be further suppressed.

  Next, the threshold variable control process of the fourth embodiment will be described. In the control start threshold processing of the fourth embodiment, the deviation corresponding control start threshold X3 that is increased according to the deviation between the target hydraulic pressure and the detected hydraulic pressure, and the hydraulic pressure corresponding control start described in the third embodiment. The threshold value X1 is calculated, and the smaller one of the two threshold values X3 and X1 is used as the control start threshold value X.

  FIG. 16 is a flowchart showing a threshold variable control routine according to the fourth embodiment. The threshold variable control routine is obtained by adding the processing of step S30 to step S43 after the processing of step S16 of the threshold variable control routine of the first embodiment, and includes other processing (including pulsation detection processing and pulsation cycle detection). ) Is the same as in the first embodiment.

  In step S16, the brake ECU 100 calculates a control start threshold value X corresponding to the hydraulic fluid pressure Pxave from the control start threshold value setting map shown in FIG. This control start threshold value X is referred to as a hydraulic pressure corresponding control start threshold value X1. Subsequently, the brake ECU 100 performs a calculation process of the deviation corresponding control start threshold value X3 in step S30.

FIG. 17 is a flowchart showing a deviation corresponding control start threshold value calculation routine which is the process of step S30. When the brake ECU 100 starts the deviation corresponding control start threshold value calculation routine, in step S31, the brake ECU 100 determines whether or not the hydraulic pressure deviation ΔP (= | P ^* −Px |) exceeds the deviation corresponding control start threshold value X3. The initial value of the deviation corresponding control start threshold value X3 is set to the normal control start threshold value X0. Since this deviation corresponding control start threshold value calculation routine is executed when it is determined that there is pulsation, it is determined as “Yes” at the time of activation. In this case, the brake ECU 100 increases the deviation handling control start threshold value X3 by a preset specified value ΔX in step S32. That is, a value obtained by adding the specified value ΔX to the current deviation handling control start threshold value X3 is set as a new deviation handling control start threshold value X3 (X3 = X3 + ΔX). Subsequently, in step S33, the brake ECU 100 stores the increased deviation corresponding control start threshold value X3 in the memory, and in step S34, outputs the deviation corresponding control start threshold value X3 as a calculation result to calculate the deviation corresponding control start threshold value. The routine is temporarily exited and the routine proceeds to step S41 of the main routine.

  Since the deviation corresponding control start threshold value calculation routine is incorporated in the threshold value variable control routine, it is repeated at a predetermined short cycle. After the deviation corresponding control start threshold value X3 is set to increase, the determination reference value (= deviation corresponding control start threshold value X3) for determining the magnitude of the hydraulic pressure difference ΔP in step S31 also increases. Therefore, the brake ECU 100 increases the deviation corresponding control start threshold X3 by the specified value ΔX until the hydraulic pressure difference ΔP becomes equal to or less than the deviation corresponding control start threshold X3, and stores the increased deviation corresponding control start threshold X3 each time. At the same time, it is output as a calculation result. When the hydraulic pressure deviation ΔP becomes equal to or less than the deviation corresponding control start threshold value X3 (S31: No), the brake ECU 100 reads the latest deviation corresponding control start threshold value X3 stored in the memory in step S35, and in step S34. The read deviation correspondence control start threshold value X3 is output as a calculation result.

  The deviation corresponding control start threshold value calculation routine temporarily stops the calculation when the brake pedal 10 is depressed from the holding state (S11: No), but the deviation corresponding control start threshold value X3 is stored in the memory. When the brake pedal 10 is returned to the holding state again, the calculation is started using the deviation corresponding control start threshold value X3 stored in the memory as an initial value. Therefore, a change in the brake operation feeling can be suppressed during the brake operation. The brake ECU 100 resets the deviation corresponding control start threshold value X3 stored in the memory to return to the normal control start threshold value X0 when the brake pedal operation is released (when braking is off).

  FIG. 18 is a diagram showing an image in which the deviation corresponding control start threshold value X3 is set to be increased. As shown in the figure, the deviation corresponding control start threshold value X3 increases by a specified value ΔX until the hydraulic pressure difference ΔP becomes equal to or less than the deviation corresponding control start threshold value X3. Therefore, if this deviation corresponding control start threshold value X3 is used, excessive operation of the linear control valve 67 can be reliably prevented while minimizing changes in the brake operation feeling.

  Returning to the description of FIG. 16, when the brake ECU 100 calculates the deviation corresponding control start threshold value X3, in a subsequent step S41, the brake pressure corresponding control start threshold value X1 is compared with the deviation corresponding control start threshold value X3, and the deviation corresponding control start threshold value is calculated. It is determined whether X3 is smaller than the hydraulic pressure corresponding control start threshold value X1. If the deviation corresponding control start threshold X3 is smaller than the hydraulic pressure corresponding control start threshold X1, the final control start threshold X is set to the deviation corresponding control start threshold X3 in step S42, and the deviation corresponding control start threshold X3 is If it is equal to or greater than the hydraulic pressure corresponding control start threshold X1, the final control start threshold X is set to the hydraulic pressure corresponding control start threshold X1 in step S43.

  In other words, in the fourth embodiment, the hydraulic pressure corresponding control start threshold value X1 and the deviation corresponding control start threshold value X3 are respectively calculated and compared, and the smaller value is set as the control start threshold value X.

  For example, when only the deviation corresponding control start threshold value X3 is used, the control start threshold value increases stepwise until the hydraulic pressure deviation becomes equal to or less than the control start threshold value. Can be prevented. However, in some cases, the control start threshold value may become larger than necessary. For example, as shown in FIG. 19, a state is considered in which a hydraulic pulsation is detected during a brake holding operation, and the control start threshold value X (deviation corresponding control start threshold value X3) is set to increase gradually to the F point. From this state, when the brake operation is loosened and held again, the control start threshold value X maintains the previous value. However, in reality, since the hydraulic pressure of the hydraulic fluid has decreased from Pf to Pg, the hydraulic rigidity is small and the pulsation amplitude is also small. Therefore, when the brake pedal 10 is depressed from this state, the brake response is reduced. Will be delayed.

  Therefore, in the fourth embodiment, the fluid pressure corresponding control start threshold value X1 is used as the upper limit value so that the control start threshold value X does not exceed the fluid pressure corresponding control start threshold value X1. Therefore, as shown in FIG. 19, when the brake operation is relaxed, the control start threshold value can be reduced to point G, and a delay in brake response can be prevented.

  Thus, according to the fourth embodiment, it is possible to more satisfactorily achieve suppression of excessive operation of the linear control valve while establishing a brake operation feeling.

  Although the brake control device according to the present embodiment has been described above, the present invention is not limited to the above-described embodiment and modifications, and various modifications can be made without departing from the object of the present invention.

  For example, the brake control device of the present embodiment is applied to a brake control device that commonly controls the hydraulic pressures of four wheel cylinders 42 with a linear control valve composed of a pressure-increasing linear control valve 67A and a pressure-decreasing linear control valve 67B. However, the present invention may be applied to a brake control device in which a separate linear control valve is provided for each wheel and the hydraulic pressure of the wheel cylinder of each wheel is independently regulated by the linear control valve.

  Further, in the present embodiment, the control start threshold value X is changed when the hydraulic pressure pulsation of the hydraulic fluid is detected. However, this is related to whether the hydraulic pressure pulsation of the hydraulic fluid is detected. Instead, the control start threshold value X may always be set according to the hydraulic pressure of the hydraulic fluid or the vehicle speed.

  In this embodiment, the control start threshold value X is set so as to change linearly according to the hydraulic pressure or the vehicle speed. For example, as shown in FIGS. Two control start threshold values X may be set according to the pressure or the vehicle speed.

  Further, in the threshold variable control routine (FIG. 16) of the fourth embodiment, instead of the processing of step S16 (calculation of the hydraulic pressure corresponding control start threshold X1), step S17 (vehicle speed corresponding control start threshold X2) of the third embodiment. May be executed. In this case, in the processing of steps S41 to S43, the vehicle speed corresponding control start threshold value X2 and the deviation corresponding control start threshold value X3 may be compared and the smaller value may be set as the control start threshold value X.

  Further, the control start threshold value X may be set based on the hydraulic pressure corresponding control start threshold value X1, the vehicle speed corresponding control start threshold value X2, and the deviation corresponding control start threshold value X3. For example, the larger value (MAX (X1, X2)) of the hydraulic pressure corresponding control start threshold value X1 and the vehicle speed corresponding control start threshold value X2 is compared with the deviation corresponding control start threshold value X3, and the smaller value is started to control. The threshold value X may be set. That is, the deviation corresponding control start threshold value X3 may be set to the control start threshold value X by adding an upper limit to the hydraulic pressure corresponding control start threshold value X1 and the vehicle speed corresponding control start threshold value X2.

  Moreover, although the brake control apparatus of this embodiment is applied to a hybrid vehicle, it may be applied to an electric vehicle (EV). Even in this case, the brake regeneration cooperative control can be executed. Moreover, you may apply to the vehicle driven only with an internal combustion engine.

  DESCRIPTION OF SYMBOLS 10 ... Brake pedal, 20 ... Master cylinder unit, 30 ... Power hydraulic pressure generator, 42FR, 42FL, 42RR, 42RL ... Wheel cylinder, 50 ... Fluid pressure control valve device, 67A ... Pressure increase linear control valve, 67B ... Pressure reduction linear Control valve 100 ... Brake ECU 101 ... Accumulator pressure sensor 102 ... Regulator pressure sensor 103 ... Control pressure sensor 104 ... Stroke sensor 105 ... Wheel speed sensor X ... Control start threshold value X0 ... Normal control start threshold value X1 ... Fluid pressure corresponding control start threshold, X2 ... Vehicle speed corresponding control start threshold, X3 ... Deviation corresponding control start threshold.

Claims (8)

A wheel cylinder that receives the hydraulic pressure of the hydraulic fluid and applies braking force to the wheel;
Brake operation amount detection means for detecting the brake operation amount;
A linear control valve that adjusts the hydraulic pressure transmitted to the wheel cylinder;
Hydraulic pressure detecting means for detecting hydraulic pressure transmitted to the wheel cylinder;
When the absolute value of the deviation between the detected hydraulic pressure, which is the hydraulic pressure detected by the hydraulic pressure detecting means, and the target hydraulic pressure exceeds a control start threshold, the linear pressure is set so that the detected hydraulic pressure approaches the target hydraulic pressure. In a vehicle brake control device comprising: a hydraulic pressure control means for starting drive control of a control valve;
A vehicle having a control start threshold value changing means for changing the control start threshold value in accordance with a parameter affecting the amplitude characteristic of a hydraulic pressure pulsation generated by a periodic external force acting on the wheel cylinder. Brake control device.   The vehicle brake control device according to claim 1, wherein the parameter is a hydraulic pressure of the hydraulic fluid.   3. The parameter according to claim 2, wherein the parameter is a hydraulic pressure of the hydraulic fluid, and the control start threshold value changing unit decreases the control start threshold value when the hydraulic pressure is small compared to when the hydraulic pressure is high. A brake control device for a vehicle according to claim.   The control start threshold value changing means is based on the detected fluid pressure, the target fluid pressure, or the brake operation amount, and when the detected fluid pressure, the target fluid pressure, or the brake operation amount is small, compared to a case where it is large. 4. The vehicle brake control device according to claim 3, wherein the control start threshold value is reduced. The absolute value of the deviation between the target hydraulic pressure and the detected hydraulic pressure is detected when a pulsation of the hydraulic pressure at which the absolute value of the deviation between the target hydraulic pressure and the detected hydraulic pressure is greater than the control start threshold is detected. Comprises a deviation corresponding control start threshold value calculating means for calculating a control start threshold value increased until the control start threshold value becomes equal to or less than the control start threshold value,
The control start threshold value changing means is
Hydraulic pressure corresponding control start threshold value calculating means for calculating a control start threshold value that is smaller than when the detected hydraulic pressure or the target hydraulic pressure or the brake operation amount is small;
Control start threshold selection for selecting the smaller control start threshold among the control start threshold calculated by the deviation corresponding control start threshold calculating means and the control start threshold calculated by the hydraulic pressure corresponding control start threshold calculating means The vehicle brake control device according to any one of claims 1 to 4, further comprising: means.   6. The control parameter according to claim 1, wherein the parameter is a vehicle speed, and the control start threshold value changing unit reduces the control start threshold value when the vehicle speed is high compared to when the vehicle speed is low. The brake control device for a vehicle according to one item. The parameters are both hydraulic pressure and vehicle speed of the hydraulic fluid,
The control start threshold value changing means is
Hydraulic pressure corresponding control start threshold value calculating means for calculating a control start threshold value that is smaller than when the detected hydraulic pressure or the target hydraulic pressure or the brake operation amount is small;
Vehicle speed corresponding control start threshold value calculating means for calculating a control start threshold value that is smaller than when the vehicle speed is small, and
Control start threshold selection for selecting the larger control start threshold value among the control start threshold value calculated by the hydraulic pressure corresponding control start threshold value calculating means and the control start threshold value calculated by the vehicle speed corresponding control start threshold value calculating means. The vehicle brake control device according to claim 6, further comprising: means. Comprising pulsation detection means for detecting that the hydraulic pressure of the hydraulic fluid is pulsating;
The control start threshold value changing means is a normal control that represents the control start threshold value when the hydraulic pressure pulsation is detected by the pulsation detecting means, and the control start threshold value when the hydraulic pressure pulsation is not detected. The vehicle brake control device according to any one of claims 1 to 7, wherein the vehicle brake control device is changed to a value larger than a start threshold value.

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