JP2016097893A - Vehicular braking device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vehicular braking device capable of suppressing an increase of load pressure to the components of a braking force applying portion, even if an abnormal condition occurs in a part of the braking force applying portion.SOLUTION: A vehicular braking device includes: a pressure accumulating portion 15c1; a pressure accumulation control portion 17a which controls hydraulic pressure in the pressure accumulating portion 15c1 so as to stop a rise of the hydraulic pressure in the pressure accumulating portion 15c1 when the hydraulic pressure in the pressure accumulating portion 15c1 is predetermined off-pressure or more; a hydraulic pressure generating portion 15d which mechanically generates hydraulic pressure according to brake operation with the hydraulic pressure accumulated in the pressure accumulating portion 15c1 as an upper limit on the basis of the hydraulic pressure in the pressure accumulating portion 15c1; a braking force applying portion 16 which applies braking force on wheels of a vehicle on the basis of the hydraulic pressure generated by the hydraulic pressure generating portion 15d; and an obtaining portion 16a which obtains required braking force. The pressure accumulation control portion 17a lowers the off-pressure when the required braking force obtained by the obtaining portion 16a is a first predetermined value or more.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a braking device for a vehicle.

  In a vehicle braking device, a servo pressure for driving a master piston is increased by a booster in accordance with a brake operation, and the hydraulic pressure in the master cylinder is increased by the servo pressure, and the master cylinder pressure is passed through an ABS device or the like. There is a type of device that is supplied to the wheel cylinder. In this case, the accumulator (accumulation unit) of the booster is used for increasing the servo pressure and thus for increasing the master cylinder pressure. Such a vehicle braking device is described in, for example, Japanese Patent Application Laid-Open No. 2006-123889.

JP 2006-123889 A

  In such an apparatus, when applied to a large vehicle, it is conceivable that the total length of the master cylinder increases as the amount of oil increases, and mountability decreases. Therefore, the inventor has an accumulator (for example, an accumulator), a hydraulic pressure generator that mechanically generates a hydraulic pressure according to a brake operation based on the hydraulic pressure in the accumulator and with the hydraulic pressure in the accumulator as an upper limit, A new braking device for a vehicle has been devised that includes a braking force applying unit (for example, an actuator) that applies a braking force to the wheel based on the hydraulic pressure generated by the pressure generating unit. In this configuration, the pressure accumulating unit directly supplies the hydraulic pressure to the braking force applying unit by the mechanical operation of the hydraulic pressure generating unit according to the brake operation. With this configuration, an increase in the size of the vehicle braking device can be suppressed.

  However, in this configuration, when a part of the components (for example, a solenoid valve) of the braking force application unit becomes abnormal, other components of the braking force application unit in which the hydraulic pressure is not applied from the hydraulic pressure generation unit at the normal time ( For example, the hydraulic pressure generated by the hydraulic pressure generating unit may be applied to the reservoir. Thereby, durability of the said other component of a braking force provision part falls.

  The present invention has been made in view of such circumstances, and suppresses an increase in load pressure to other components of the braking force application unit even when an abnormality occurs in a part of the braking force application unit. It is an object of the present invention to provide a braking device for a vehicle that can be used.

  The braking device for a vehicle according to the present invention includes a pressure accumulating portion for accumulating hydraulic fluid, and the pressure accumulating portion so that the increase in the fluid pressure in the pressure accumulating portion stops when the fluid pressure in the pressure accumulating portion is equal to or higher than a predetermined off pressure. And a hydraulic pressure that mechanically generates a hydraulic pressure corresponding to a brake operation with the hydraulic pressure accumulated in the pressure accumulating portion as an upper limit based on the hydraulic pressure in the pressure accumulating portion. A pressure generating control unit including: a generating unit; a braking force applying unit that applies a braking force to a vehicle wheel based on the hydraulic pressure generated by the hydraulic pressure generating unit; and an acquisition unit that acquires a required braking force. When the required braking force acquired by the acquiring unit is equal to or greater than a predetermined value, the off-pressure is set lower than when the required braking force acquired by the acquiring unit is less than the predetermined value. To do.

  According to the present invention, when the required braking force is greater than or equal to the first predetermined value, that is, in a state where a high hydraulic pressure is supplied to the braking force application unit, the “off pressure” relating to the upper limit of the hydraulic pressure in the pressure accumulating unit is low. Become. When this off-pressure decreases, when the hydraulic pressure in the pressure accumulator increases (or increases later), the increase in the hydraulic pressure in the pressure accumulator is stopped earlier than usual, and the hydraulic pressure in the pressure accumulator becomes lower than normal. Kept low. That is, the load applied to the braking force applying unit by the pressure accumulating unit can be made smaller than usual. As a result, it is suppressed that a hydraulic pressure higher than necessary is supplied to the braking force application unit for a long time, and even if some components of the braking force application unit have a failure, An increase in the load pressure on the component can be suppressed.

It is a block diagram which shows the structure of the braking device of the vehicle of 1st embodiment. It is a time chart for demonstrating the off-pressure change control of the braking device of the vehicle of 1st embodiment. It is a flowchart for demonstrating the off pressure change control of the braking device of the vehicle of 1st embodiment. It is a block diagram which shows the structure of brake ECU of 2nd embodiment. It is a flowchart for demonstrating the off-pressure change control of the braking device of the vehicle of 2nd embodiment.

<First embodiment>
Hereinafter, a first embodiment in which a vehicle braking device according to the present invention is applied to a vehicle will be described with reference to the drawings. The vehicle of this embodiment is not a hybrid vehicle but a vehicle that uses only an engine as a drive source. The vehicle includes a hydraulic braking unit A that directly applies a hydraulic braking force to each wheel Wfl, Wfr, Wrl, Wrr to brake the vehicle. As shown in FIG. 1, the hydraulic braking unit A includes a brake pedal 11 that is a brake operation member, a stroke simulator unit 12, a reservoir tank 14, a booster mechanism 15, and an actuator (corresponding to a “braking force applying unit”) 16. A brake ECU 17 and a wheel cylinder WC are provided.

  The wheel cylinder WC regulates the rotation of the wheel W, and is provided in the caliper CL. The wheel cylinder WC is a braking force applying mechanism that applies a braking force to the vehicle wheel W based on a first hydraulic pressure (described later). The braking force applying mechanism is configured to be able to apply a braking force to the wheel W based on the first hydraulic pressure and the second hydraulic pressure. When the brake fluid pressure (brake fluid pressure: first fluid pressure, second fluid pressure) from the actuator 16 or the booster mechanism 15 is supplied to the wheel cylinder WC, each piston (not shown) of the wheel cylinder WC frictions. A pair of brake pads (not shown) that are members are pressed to restrict rotation of the disc rotor DR that is a rotating member that rotates integrally with the wheel W from both sides. In this embodiment, the disc type brake is adopted, but a drum type brake may be adopted. The wheel W is any one of the left and right front and rear wheels Wfl, Wfr, Wrl, and Wrr.

  In the vicinity of the brake pedal 11, a pedal stroke sensor 11 a that detects a brake pedal stroke (operation amount) that is a brake operation state by the depression of the brake pedal 11 is provided. The pedal stroke sensor 11 a is connected to the brake ECU 17, and a detection signal is output to the brake ECU 17.

  The brake pedal 11 is connected to the stroke simulator unit 12 via a push rod 19. The stroke simulator section 12 includes a cylinder section 12a, a piston 12b that can slide fluidly in the cylinder section 12a, a hydraulic chamber 12c formed by the cylinder section 12a, the piston 12b, and the piston 13b, and a hydraulic chamber. And a stroke simulator 12d communicated with 12c.

  A push rod 19 is connected to one end side (the right side in the drawing) of the sliding direction (axial direction) of the piston 12b. The piston 12b is disposed in the hydraulic chamber 12c. The hydraulic chamber 12c is provided with a spring 12e that is interposed between the piston 12b and the bottom wall 12a3 of the cylinder portion 12a and biases the piston 12c in the direction of expanding the hydraulic chamber 12c.

  The hydraulic chamber 12c communicates with the stroke simulator 12d through an oil passage 12f connected to the input / output port 12a2. The hydraulic chamber 12c communicates with the reservoir tank 14 via a connection oil passage (not shown).

  The stroke simulator 12 d causes the brake pedal 11 to generate a stroke (reaction force) having a magnitude corresponding to the operation state of the brake pedal 11. That is, the stroke simulator 12d is an operation corresponding pressure generating mechanism that generates a hydraulic pressure corresponding to the brake operation in the hydraulic pressure chamber 12d3. The stroke simulator 12d includes a cylinder part 12d1, a piston part 12d2, a hydraulic chamber 12d3, and a spring 12d4. The piston portion 12d2 slides liquid-tightly in the cylinder portion 12d1 in accordance with the brake operation for operating the brake pedal 11. The hydraulic chamber (first hydraulic chamber) 12d3 is formed by being partitioned between the cylinder portion 12d1 and the piston portion 12d2. The hydraulic chamber 12d3 communicates with the hydraulic chamber 12c through an oil passage 12f connected to the input / output port 12d5. The spring 12d4 biases the piston portion 12d2 in a direction to reduce the volume of the hydraulic chamber 12d3. The spring 12d4 is an interposed member interposed between the piston portion 12d2 and the input portion 15b. As the interposition member, another elastic member such as a rubber member may be employed instead of the spring.

  When the piston portion 12d2 is pressed toward the left side, the input portion 15b does not move regardless of the sliding of the piston portion 12d2 in the initial first period of the brake operation. The input portion 15b starts to move to the left side only when the force pressing the piston portion 12d2 to the left is greater than the sum of the urging force of the spring 12d4, the urging force of the spring 15e, and the sliding resistance of the input portion 15b. Until then, when the force pressing the piston portion 12d2 to the left is smaller than the total force described above, the input portion 15b does not move. Furthermore, after the end of the first period and when the brake operation increases, the input portion 15b moves as the piston portion 12d2 slides.

  The booster mechanism 15 generates a first hydraulic pressure corresponding to the movement of the input unit 15b based on the hydraulic pressure of an accumulator (corresponding to a “pressure accumulating unit”) 15c1 that accumulates hydraulic fluid (brake fluid). This is output to the piping system 20 and the second piping system 30 (actuator 16) (first hydraulic pressure generating mechanism). The booster mechanism 15 includes a cylinder 15a, an input unit 15b, a pressure supply device 15c, and a hydraulic pressure generation unit 15d.

  The cylinder 15a is coaxially and integrally connected to the cylinder portion 12d1 of the stroke simulator 12d. The input unit 15 b is for inputting a brake operation (hydraulic pressure corresponding to the brake operation) to the booster mechanism 15. The input portion 15b is directly pressed by the piston portion 12d2 or pressed by a spring 12d4 that is an interposed member between the piston portion 12d2 and the piston portion 12d2 of the stroke simulator 12d. Is slid and moved in the cylinder 15a. The input portion 15b is formed in a piston shape and slides in a liquid-tight manner in the cylinder 15a. The peripheral edge portion of the input portion 15b comes into contact with the step portion 12d6. A step portion 15b1 is provided on the other end of the input portion 15b. The tip of the step portion 15b1 comes into contact with one end of the spool portion 15d1. The input portion 15b is biased toward one end by a spring 15e having one end abutting against the other end of the input portion 15b and the other end abutting against the convex portion 15a1 of the cylinder 15a.

  A hydraulic chamber 12d7 is defined between the input portion 15b and the piston portion 12d2. The hydraulic chamber 12d7 communicates with the reservoir tank 14 through an oil passage 41 connected to the input / output port 12d8. The oil passage 41 is provided with an electromagnetic valve 41a that is opened and closed according to an opening / closing instruction of the brake ECU 17. The solenoid valve 41a is a two-position solenoid valve that can control the communication / blocking state. The solenoid valve 41a is cut off when the control current to the solenoid coil provided in the solenoid valve 41a is zero (when not energized), and when the control current is passed through the solenoid coil (when energized). It is a normally closed type controlled to a communication state.

  The pressure supply device 15c includes a reservoir tank 14 that is a low pressure source, an accumulator 15c1 that is a high pressure source and accumulates hydraulic fluid, a pump 15c2 that sucks brake fluid in the reservoir tank 14 and pumps it to the accumulator 15c1, and a pump 15c2. Is provided with an electric motor 15c3. The reservoir tank 14 is open to the atmosphere, and the hydraulic pressure in the reservoir tank 14 is the same as the atmospheric pressure. The low pressure source is at a lower pressure than the high pressure source. Although the reservoir tank 14 is shared as a low pressure source of the pressure supply device 15c, another reservoir tank may be provided. The pressure supply device 15c includes a pressure sensor 15c4 that detects the pressure of the brake fluid supplied from the accumulator 15c1 and outputs the detected pressure to the brake ECU 17.

  The hydraulic pressure generating unit 15d generates a first hydraulic pressure corresponding to the movement of the input unit 15b based on the hydraulic pressure of the accumulator 15c1 that accumulates the hydraulic fluid. That is, the hydraulic pressure generating unit 15d mechanically generates a hydraulic pressure corresponding to the brake operation with the hydraulic pressure accumulated in the accumulator 15c1 as an upper limit based on the hydraulic pressure in the accumulator 15c1. The hydraulic pressure generating portion 15d includes a spool portion 15d1 that slides fluidly in the cylinder 15a. A high pressure port 15d2, a low pressure port 15d3, and an output port 15d4 are formed in the hydraulic pressure generating unit 15d. The high pressure port 15d2 is directly connected to the accumulator 15c1 via the oil passage 42. The low pressure port 15 d 3 is directly connected to the reservoir tank 14 through an oil passage 43 connected to the oil passage 41. The output port 15d4 is connected to the actuator 16 (and thus the wheel cylinder WC) via the oil passage 44.

  The oil passage 44 is connected to the oil passages 30 a and 30 d of the second second piping system 30. The oil passage 45 branched from the middle of the oil passage 44 is connected to the oil passages 20 a and 20 d of the first first piping system 20. The oil passage 44 is provided with an opening / closing control valve 44a that is opened and closed according to an opening / closing instruction of the brake ECU 17. The open / close control valve 44a is a two-position electromagnetic valve that can control the communication / blocking state. The open / close control valve 44a is cut off when the control current to the solenoid coil provided in the open / close control valve 44a is zero (when not energized), and when the control current flows through the solenoid coil (when energized). ) Is a normally closed type that is controlled to communicate.

  A hydraulic chamber 15d5 is defined between the cylinder 15a (bottom wall) and the spool portion 15d1. In the hydraulic pressure chamber 15d5, there is disposed a spring 15d6 that is interposed between the cylinder 15a (bottom wall) and the spool portion 15d1 and urges the hydraulic pressure chamber 15d5 to expand. The spool portion 15d1 is biased by a spring 15d6 and is in a predetermined position (see FIG. 1). The predetermined position of the spool portion 15d1 is a position where one end side of the spool portion 15d1 abuts on the convex portion 15a1 and is positioned and fixed, and the other end side end of the spool portion 15d1 is a position immediately before closing the low pressure port 15d3. .

  The spool portion 15d1 has an oil passage 15d8 communicating with the hydraulic chamber 15d7. As shown in FIG. 1, when the spool portion 15d1 is in a predetermined position, the low pressure port 15d3 and the output port 15d4 communicate with each other via an oil passage 15d8, and the high pressure port 15d2 is closed by the spool portion 15d1.

  When the input portion 15b is moved to the left side, abuts against the spool portion 15d1, and the spool portion 15d1 moves to the left side, the high pressure port 15d2 and the output port 15d4 communicate with each other via the hydraulic pressure chamber 15d7. At this time, the low pressure port 15d3 is closed by the spool portion 15d1. Therefore, the other end of the spool portion 15d1 receives a force corresponding to the servo pressure (when pressure is increased).

  When the pressing force of the spool portion 15d1 by the input portion 15b is balanced with the force corresponding to the servo pressure, the high pressure port 15d2 and the low pressure port 15d3 are closed by the spool portion 15d1 (during holding).

  When the input unit 15b moves to the right side, the spool unit 15d1 also moves to the right side (during decompression). At this time, the low pressure port 15d3 and the output port 15d4 communicate with each other via the oil passage 15d8, and the high pressure port 15d2 is closed by the spool portion 15d1.

  The detailed structure of the actuator 16 will be described with reference to FIG. The actuator 16 generates a hydraulic pressure corresponding to the brake operation within the first period, and increases the differential pressure between the target wheel cylinder pressure and the hydraulic pressure generated by the booster mechanism 15 outside the first period. This is a pressurizing mechanism that pressurizes the hydraulic pressure generated by the mechanism 15. The actuator 16 is also a second hydraulic pressure generating mechanism that generates a desired second hydraulic pressure. The second hydraulic pressure generating mechanism generates a second hydraulic pressure corresponding to a brake operation, for example. First and second second piping systems 20 and 30 are formed in the actuator 16. The first first piping system 20 controls the brake fluid pressure applied to the left rear wheel Wrl and the right rear wheel Wrr, and the second second piping system 30 controls the brake fluid pressure applied to the right front wheel Wfr and the left front wheel Wfl. To control. That is, it is set as the piping structure of front and rear piping.

  The hydraulic pressure supplied from the booster mechanism 15 is transmitted to the wheel cylinders WCrl, WCrr, WCfr, WCfl through the first first piping system 20 and the second second piping system 30. The first first piping system 20 is provided with an oil passage 20a that connects the oil passage 45 and the wheel cylinders WCrl and WCrr. The second second piping system 30 is provided with an oil passage 30a that connects the oil passage 44 and the wheel cylinders WCfr, WCfl, and the hydraulic pressure supplied from the booster mechanism 15 through each of the oil passages 20a, 30a is a wheel. It is transmitted to the cylinders WCrl, WCrr, WCfr, WCfl.

  The oil passages 20a and 30a include differential pressure control valves 21 and 31 that can be controlled to be in a communication state and a differential pressure state. The valve positions of the differential pressure control valves 21 and 31 are adjusted so that they are in a communicating state during braking when the driver operates the brake pedal 11. When a current is passed through the solenoid coils provided in the differential pressure control valves 21 and 31, the valve positions of the differential pressure control valves 21 and 31 are adjusted so that the differential pressure is increased as the current value increases.

  When the differential pressure control valves 21 and 31 are in the differential pressure state, only when the brake fluid pressure on the wheel cylinders WCrl, WCrr, WCfr, WCfl side is higher than the fluid pressure supplied from the booster mechanism 15 by a predetermined pressure or more. The brake fluid is allowed to flow only from the wheel cylinders WCrl, WCrr, WCfr, WCfl side to the booster mechanism 15 side. For this reason, a state in which the wheel cylinders WCrl, WCrr, WCfr, and WCfl are always at a predetermined pressure higher than the booster mechanism 15 is maintained.

  The oil passages 20a and 30a branch into two oil passages 20a1, 20a2, 30a1, and 30a2, respectively, on the wheel cylinders WCrl, WCrr, WCfr, and WCfl side downstream of the differential pressure control valves 21 and 31. The oil passages 20a1 and 30a1 are provided with first and first pressure increase control valves 22 and 32 for controlling an increase in brake fluid pressure to the wheel cylinders WCrl and WCfr. The oil passages 20a2 and 30a2 are provided with second and second pressure increase control valves 23 and 33 for controlling the increase of the brake fluid pressure to the wheel cylinders WCrr and WCfl.

  These first and second pressure increase control valves 22, 23, 32, 33 are constituted by two-position solenoid valves that can control the communication / blocking state. The first and second pressure increase control valves 22, 23, 32, 33 are set to zero when the control current to the solenoid coil provided in the first, second pressure increase control valves 22, 23, 32, 33 is zero ( It is in a communication state when not energized, and is a normally open type that is controlled to be shut off when a control current flows through the solenoid coil (when energized).

  Between the first and second pressure increase control valves 22, 23, 32, 33 in the oil passages 20 a, 30 a and the wheel cylinders WCrl, WCrr, WCfr, WCfl are adjusted through oil passages 20 b, 30 b as pressure reducing oil passages. The pressure reservoirs 24 and 34 are connected. The oil passages 20b and 30b are respectively provided with first and second pressure reduction control valves 25, 26, 35 and 36 constituted by two-position electromagnetic valves capable of controlling the communication / blocking state. These first and second pressure reduction control valves 25, 26, 35, and 36 are used when the control current to the solenoid coils provided in the first and second pressure reduction control valves 25, 26, 35, and 36 is set to zero (non- When the current is energized, it is in a cut-off state, and when the control current is supplied to the solenoid coil (when it is energized), it is a normally closed type that is controlled to be in a communication state.

  Oil passages 20c and 30c serving as reflux oil passages are disposed between the pressure adjusting reservoirs 24 and 34 and the oil passages 20a and 30a serving as main oil passages. The oil passages 20c, 30c are self-priming pumps driven by a motor 28 that sucks and discharges brake fluid from the pressure regulating reservoirs 24, 34 toward the booster mechanism 15 or the wheel cylinders WCrl, WCrr, WCfr, WCfl. 27 and 37 are provided. The motor 28 is driven by controlling energization to a motor relay (not shown).

  Oil passages 20 d and 30 d serving as auxiliary oil passages are provided between the pressure regulating reservoirs 24 and 34 and the booster mechanism 15. The pumps 27 and 37 suck the brake fluid from the booster mechanism 15 through the oil passages 20d and 30d, and discharge the brake fluid to the oil passages 20a and 30a, thereby supplying the brake fluid to the wheel cylinders WCrl, WCrr, WCfr, and WCfl side. .

  The brake ECU 17 receives detection signals from wheel speed sensors Sfl, Srr, Sfr, Srl provided for each vehicle wheel Wfl, Wrr, Wfr, Wrl. The brake ECU 17 calculates each wheel speed, estimated vehicle body speed, slip ratio, and the like based on detection signals from the wheel speed sensors Sfl, Srr, Sfr, Srl. The brake ECU 17 executes anti-skid control and the like based on these calculation results. In addition, the actuator 16 is provided with a hydraulic pressure sensor (corresponding to “acquisition unit”) 16 a that detects the hydraulic pressure supplied from the booster mechanism 15. The hydraulic pressure sensor 16 a is preferably provided in the oil passage 20 a of the first first piping system 20. A detection signal from the hydraulic pressure sensor 16 a is input to the brake ECU 17, and the brake ECU 17 can monitor the hydraulic pressure supplied from the booster mechanism 15.

  Various controls using the actuator 16 are executed by the brake ECU 17. For example, the brake ECU 17 outputs a control current for controlling the various control valves 21 to 23, 25, 26, 31 to 33, 35 and 36, and the pump driving motor 28 provided in the actuator 16, The hydraulic circuit provided in the actuator 16 is controlled, and the wheel cylinder pressure transmitted to the wheel cylinders WCrl, WCrr, WCfr, WCfl is individually controlled. For example, the brake ECU 17 performs anti-skid control for preventing wheel lock by reducing, maintaining, and increasing the wheel cylinder pressure when the wheel slips during braking, and skidding by automatically increasing the wheel cylinder pressure of the wheel to be controlled. Side slip prevention control that suppresses the tendency (understeering tendency or oversteering tendency) and enables turning on an ideal trajectory can be performed.

  In addition, when the ignition switch is in an off state or when there is a power failure, the solenoid valve 41a is in a closed state. When the ignition switch is on and there is no power failure, the solenoid valve 41a is opened.

  During normal braking, the brake ECU 17 causes the actuator 16 to generate a hydraulic pressure corresponding to the brake operation during the first period in which the input portion 15b does not move despite the sliding of the piston portion 12d2 (hydraulic pressure control). Part). Further, the brake ECU 17 generates a second hydraulic pressure corresponding to the brake operation by the actuator 16 (second hydraulic pressure generating mechanism) during the first period, and the second hydraulic pressure by the wheel cylinder WC (braking force applying mechanism). A braking force is applied to the wheel W based on the pressure (hydraulic pressure control unit). When the brake ECU 17 detects the start of the operation of the brake pedal 11 based on the detection signal acquired from the pedal stroke sensor 11a, the hydraulic pressure sensor 16a detects a hydraulic pressure greater than a predetermined pressure value (for example, 0 Pa) from the operation start time. Until then, the hydraulic pressure corresponding to the brake operation is generated by the actuator 16. The normal braking is when the brake operation is performed, a wheel cylinder pressure corresponding to the operation is formed, and the wheel cylinder pressure is applied to the wheel to obtain a braking force, such as ESC control. It differs from the one that gives braking force when there is no brake operation.

  When the ignition switch is on and there is no power failure, the solenoid valve 41a is open. Accordingly, since the hydraulic chamber 12d7 communicates with the reservoir tank 14 via the oil passage 41, the brake fluid in the hydraulic chamber 12d7 passes through the oil passage 41 when the piston portion 12d2 moves to the left according to the brake operation. Thus, it can flow out to the reservoir tank 14. Therefore, the input portion 15b does not move to the left side until the force that presses the piston portion 12d2 to the left is greater than the sum of the urging force of the spring 12d4, the urging force of the spring 15e, and the sliding resistance of the input portion 15b. start. Until then, when the force pressing the piston portion 12d2 to the left is smaller than the total force described above, the input portion 15b does not move. The brake ECU 17 ends the pressurization by the actuator 16 when the hydraulic pressure sensor 16a detects a hydraulic pressure greater than a predetermined pressure value (for example, 0 Pa). Thereby, only the hydraulic pressure generated according to the brake operation by the booster mechanism 15 is supplied to the wheel cylinder WC.

(Off pressure change control)
Here, the off-pressure change control of the vehicle braking device of the present embodiment will be described. As described above, the vehicle braking device according to the present embodiment has a configuration in which the hydraulic pressure of the accumulator 15c1 is directly supplied to the actuator 16 by the hydraulic pressure generator 15d that mechanically operates in response to the brake operation. doing. The off pressure change control in this configuration will be described below.

  The brake ECU 17 includes a first predetermined value and a second predetermined value relating to a hydraulic pressure (hereinafter referred to as “master pressure”) supplied to the actuator 16, and a hydraulic pressure (hereinafter referred to as “Acc pressure”) in the accumulator 15 c 1. ) Are recorded. Reference off pressure, reference on pressure, correction off pressure, and correction on pressure are recorded. The off pressure is a set pressure for stopping (turning off) the pump 15c2. When the Acc pressure becomes equal to or higher than the off pressure, the pump 15c2 is stopped. The on pressure is a set pressure for driving (turning on) the pump, and the pump 15c2 is driven when the Acc pressure becomes lower than the on pressure.

  The second predetermined value is set to a value smaller than the first predetermined value (first predetermined value> second predetermined value). The corrected off pressure is set to a value smaller than the reference off pressure, and the corrected on pressure is set to a value smaller than the reference on pressure. The corrected off pressure is set to a value equal to or lower than the reference on pressure. In the present embodiment, the reference off pressure> the reference on pressure> the corrected off pressure> the corrected on pressure is set.

  The brake ECU 17 obtains the master pressure information from the hydraulic pressure sensor 16a, and when the master pressure becomes equal to or higher than the first predetermined value, the brake ECU 17 changes the reference off pressure of the pump 15c2 to the corrected off pressure and sets the reference on pressure. Change to corrected ON pressure. That is, the brake ECU 17 decreases the set off pressure and on pressure of the pump 15c2 when the master pressure is equal to or higher than the first predetermined value. As described above, the brake ECU 17 has a pressure accumulation control unit 17a for controlling the off pressure and the on pressure of the Acc pressure in addition to the function of controlling the actuator 16 and the like.

  Further, the pressure accumulation control unit 17a changes the off pressure from the corrected off pressure to the reference off pressure when the master pressure becomes less than the second predetermined value after reducing the off pressure and the on pressure. Is changed from the corrected ON pressure to the reference ON pressure. That is, after reducing the off pressure and the on pressure, the brake ECU 17 increases the off pressure and the on pressure when the master pressure is less than the second predetermined value. At this time, the pressure accumulation control unit 17a of the present embodiment is set so that the off pressure and the on pressure return to the original values. The brake ECU 17 acquires information on the Acc pressure from the pressure sensor 15c4. The initial Acc pressure is maintained between the reference on pressure and the reference off pressure, and in this state, the pump 15c2 is in the off state.

  This off-pressure change control will be described in the case where the brake pedal 11 is depressed once (the case where there is no additional depression). As shown in FIG. 2, when the brake operation is started, the accumulator 15c1 and the actuator 16 communicate with each other at t1, and the hydraulic fluid starts to be supplied from the accumulator 15c1 to the actuator 16 via the hydraulic pressure generator 15d. As a result, the Acc pressure decreases and the master pressure increases. At t2, the Acc pressure becomes less than the reference ON pressure, and the pump 15c2 is driven (ON) by the brake ECU 17.

  At t3, the master pressure becomes equal to or higher than the first predetermined value, and the brake ECU 17 reduces the off pressure from the reference off pressure to the corrected off pressure, and reduces the on pressure from the reference on pressure to the corrected on pressure. By this change, the Acc pressure becomes a value equal to or higher than the off pressure (corrected off pressure), and the brake ECU 17 stops the pump 15c2 and stops the increase in the Acc pressure. As shown in FIG. 2, the pump 15c2 stops at an earlier timing than usual by lowering the off pressure. That is, the increase in the Acc pressure is stopped at time t3 when it does not normally stop. Then, the master pressure reaches the maximum point at t4, the brake operation starts to be released at t5, and the master pressure starts to decrease. The first predetermined value is preferably set at a timing at which it is not necessary to increase the Acc pressure. In the present embodiment, the first predetermined value is set to a value close to the maximum point (t4) of the master pressure.

  At t6, the master pressure becomes less than the second predetermined value, and the brake ECU 17 returns the off pressure and the on pressure to the original values (reference off pressure and reference on pressure). Thereby, in the next brake operation, the off pressure and the on pressure are performed with the initial reference values. The Acc pressure is maintained after t3 or t4. By increasing the off pressure and the on pressure at t6, the off pressure and the on pressure can be returned to the reference value before the change or a value close thereto.

  To summarize the flow of the off pressure change control, as shown in FIG. 3, when the brake operation is started and the master pressure becomes equal to or higher than the first predetermined value (S101: Yes), the brake ECU 17 sets the off pressure and the on pressure. Lower (S102). After that, the detection of the master pressure is repeatedly performed, and when the master pressure becomes less than the second predetermined value (S103: Yes), the brake ECU 17 increases the off pressure and the on pressure and restores them (S104).

  In the device in which the accumulator 15c1 mechanically and directly supplies the hydraulic pressure to the actuator 16 as in the present embodiment, if a failure (abnormality) occurs in a part of the device in the actuator 16, it may be long in an unexpected part. There is a risk that high fluid pressure will be applied for a long time. For example, if any of the first and second pressure reducing control valves 25, 26, 35, and 36 fails (leakage abnormality) and the control is not effective and the open state (open state) is maintained, the failure The high hydraulic pressure of the accumulator 15c1 is supplied to the reservoirs (here, the pressure regulating reservoirs 24 and 34) connected to the pressure reduction control valve. The pressure regulating reservoirs 24 and 34 are not assumed to be subjected to high pressure for a long time, and are not designed to continue to receive high fluid pressure. Therefore, when at least one of the first and second pressure reduction control valves 25, 26, 35, 36 becomes abnormal in leakage, the durability of the pressure regulating reservoirs 24, 34 is lowered.

  Even when the first and second pressure reduction control valves 25, 26, 35, and 36 are out of order, a high hydraulic pressure is supplied from the accumulator 15c1 to the actuator 16 via the hydraulic pressure generator 15d. There is almost no impact on the brake feeling. Therefore, the driver can continue the brake operation continuously without noticing the failure of the first and second pressure reducing control valves 25, 26, 35, and 36, and further to the pressure regulating reservoirs 24 and 34. The load may continue.

  However, according to the present embodiment, when the high hydraulic pressure is supplied to the actuator 16 and the master pressure becomes higher than a certain value (master pressure ≧ first predetermined value), the off pressure and the on pressure related to the Acc pressure are increased. Lower. As a result, the increase in the Acc pressure stops earlier than usual, or the upper limit of the increase in Acc pressure when the pump 15c2 is turned on after the change is reduced, and the Acc pressure is maintained at a lower hydraulic pressure than during normal control. be able to. In the case of normal control, for example, after t3 in FIG. 2, the Acc pressure increases until the reference off pressure is reached. Thereby, even when there is a failure in the first and second pressure reduction control valves 25, 26, 35, 36, an increase in load pressure to the pressure regulating reservoirs 24, 34 is suppressed. Further, the off pressure change control is not a control for lowering the Acc pressure itself, but a control for lowering at least the off pressure. Therefore, even if there is no failure in the first and second pressure reduction control valves 25, 26, 35, 36, the supply of hydraulic pressure to the actuator 16 is not affected.

  Further, according to the present embodiment, at the timing when the brake operation starts to be released and the master pressure becomes less than a certain value (master pressure <second predetermined value), the off pressure and the on pressure increase, and the original reference value Return to. Thus, the initial setting state is realized in the next brake operation. As shown in FIG. 2, the first predetermined value is preferably set to a value larger than the master pressure at which the Acc pressure is less than the on pressure (reference on pressure) during the brake operation.

  In the off pressure change control, the master pressure corresponds to “required braking force”. The required braking force may be the hydraulic pressure supplied to the actuator 16 (that is, the hydraulic pressure that changes according to the brake operation) as in the present embodiment, or the brake operation amount (for example, a value detected by the pedal stroke sensor 11a). ). As described above, the vehicle braking device according to the present embodiment includes at least the accumulator 15c1, the brake ECU 17 (the pressure accumulation control unit 17a), the hydraulic pressure generation unit 15d, the actuator 16, and the hydraulic pressure sensor 16a or the pedal stroke sensor 11a. It is equipped with.

(Other)
The present invention is not limited to the above embodiment. For example, the off pressure change control may be a control that changes only the off pressure without changing the on pressure. This also stops the increase of the Acc pressure at an early timing, or lowers the upper limit of the Acc pressure increase when the pump 15c2 is turned on after the change, and the same effect as described above is exhibited. However, by changing both the off pressure and the on pressure, the hysteresis including the on pressure can be given overall hysteresis for the off pressure change control. Further, the method of changing the off pressure and the on pressure is not limited to the above, and may be changed in any manner such as gradually decreasing. Further, it can be said that the wheel cylinder WC is a “braking force applying portion”. The braking force application unit is the actuator 16 and / or the wheel cylinder WC.

<Second embodiment>
The vehicle braking device of the second embodiment is different from the first embodiment in that it determines “whether the brake pad is in a fade state” before the off pressure change control. Therefore, a different part is demonstrated. The same reference numerals as those in the first embodiment indicate the same configurations as those in the first embodiment, and the preceding description is referred to.

  As shown in FIG. 4, the brake ECU 17 includes a pressure accumulation control unit 17 a and a pad determination unit 17 b. The pad determination unit 17b determines whether or not the brake pad provided on the caliper CL is normal. Specifically, the pad determination unit 17b indicates that the brake pad is in a fade state based on the temperature of the brake pad that is calculated and estimated from the pressurization time of the wheel speed, master pressure, and wheel cylinder pressure acquired by the brake ECU 17. It is determined whether or not. The pad determination unit 17b determines that “the brake pad is normal (that is, not in a fade state)” when the estimated temperature of the brake pad is lower than the predetermined temperature, and “the brake pad is normal” when the estimated temperature is equal to or higher than the predetermined temperature. Is not (ie, it is in a fade state) ”. The pressure accumulation control unit 17a executes the off-pressure change control of the first embodiment when the pad determination unit 17b determines “normal”.

  As shown in FIG. 5, in the second embodiment, when the brake operation is started, it is determined whether or not the brake pad is normal (whether or not it is not in a fade state) (S201). When it is determined that the brake pad is normal (S201: Yes), the same off-pressure change control as that in the first embodiment is executed (S202 to S205). Whether or not the brake pad is normal and the detection of the master pressure are repeatedly performed, and the off-pressure change control similar to the first embodiment is performed.

  According to the second embodiment, the off pressure change control is executed only when the brake pad is in a normal state that is not a fade state. Thereby, it is possible to avoid unnecessary off pressure change control in a fade state in which the Acc pressure tends to be low. The brake ECU 17 may determine whether or not the first and second pressure reduction control valves 25, 26, 35, and 36 are out of order (for example, leakage abnormality). In this case, for example, the brake ECU 17 may be set to execute the off-pressure change control when there is a leakage abnormality or when there is a leakage abnormality and is not in a fade state. In addition, the number of brake operations may be added to the brake pad temperature estimation factor. Also, other configurations of the first embodiment can be applied to the second embodiment.

  Here, when the off pressure is lowered in the off pressure change control, the required braking force corresponds to the off pressure (the braking force applied to the wheel by the caliper CL when the off pressure is supplied to the wheel cylinder WC). It may be higher than Therefore, when the required braking force is higher than the braking force corresponding to the off pressure, the hydraulic pressure corresponding to the difference between the required braking force and the braking force corresponding to the off pressure is the hydraulic pressure generated by the booster mechanism 15. Is preferably pressed by an actuator 16 (corresponding to an “auxiliary braking force applying portion”) 16. Thereby, the hydraulic pressure corresponding to the required braking force is supplied to the wheel cylinder WC, and the required braking force can be applied to the wheel by the caliper CL. Further, when the required braking force is higher than the braking force corresponding to the off pressure, instead of pressurizing by the actuator 16 as described above, a braking device other than the caliper CL (for example, an electric parking brake) A braking force that is the difference between the required braking force and the braking force corresponding to the off pressure may be applied to the wheels. These controls are commanded by a brake ECU (corresponding to an “auxiliary braking control unit”) 17. Moreover, these structures are applicable to 1st embodiment or 2nd embodiment.

(Summary)
The vehicle braking apparatus according to the present embodiment includes a pressure accumulating portion 15c1 that accumulates hydraulic fluid, and the hydraulic pressure in the pressure accumulating portion 15c1 when the fluid pressure in the pressure accumulating portion 15c1 is equal to or higher than a predetermined off pressure (reference off pressure). Based on the hydraulic pressure in the pressure accumulating portion 15c1 and the pressure accumulating control portion 17a for controlling the hydraulic pressure in the pressure accumulating portion 15c1 so as to stop the increase, the hydraulic pressure accumulated in the pressure accumulating portion 15c1 is set as an upper limit for brake operation. A hydraulic pressure generating unit 15d that mechanically generates a corresponding hydraulic pressure, and a braking force applying unit 16 that applies a braking force to the wheels of the vehicle based on the hydraulic pressure generated by the hydraulic pressure generating unit 15d (and / or WC) and an acquisition unit 16a that acquires the required braking force, and the accumulator control unit 17a is configured by the acquisition unit 16a when the required braking force acquired by the acquisition unit 16a is greater than or equal to a first predetermined value. Obtained demand braking force Than is less than a first predetermined value, to reduce the off pressure.

  The pressure accumulation control unit 17a may increase the off pressure when the required braking force acquired by the acquisition unit 16a is less than a second predetermined value that is smaller than the first predetermined value after reducing the off pressure. preferable. In addition, the pressure accumulation control unit 17a is configured so that the liquid pressure in the pressure accumulation unit 15c1 increases so that the liquid pressure in the pressure accumulation unit 15c1 increases when the liquid pressure in the pressure accumulation unit 15c1 becomes less than a predetermined on pressure (reference on pressure). When the required braking force acquired by the acquisition unit 16a is greater than or equal to the first predetermined value by controlling the pressure, than when the required braking force acquired by the acquisition unit 16a is less than the first predetermined value, It is preferable to lower the on pressure.

In addition, the vehicle braking device of the present embodiment may include a pad determination unit 17b that determines whether or not the brake pad (caliper CL) is normal. In this case, the pressure accumulation control unit 17a includes the pad determination unit. The required braking force acquired by the acquisition unit 16a when it is determined by 17b that the brake pad is not normal and the required braking force acquired by the acquisition unit 16a is greater than or equal to the first predetermined value. It is preferable to lower the off pressure than when the value is less than the first predetermined value.
In addition, the vehicle braking device of the present embodiment applies pressure to the hydraulic pressure generated by the hydraulic pressure generating unit 15d or applies to the wheel in addition to the braking force applied to the wheel by the braking force applying unit 16 (WC). The auxiliary braking force applying unit 16 that applies the braking force, and the required braking force acquired by the acquiring unit 16a when the required braking force acquired by the acquiring unit 16a is higher than the braking force corresponding to the off pressure. A hydraulic pressure corresponding to the difference from the braking force corresponding to the off pressure is increased by the auxiliary braking force applying unit 16 or an auxiliary braking control unit 17 for applying the differential braking force by the auxiliary braking force applying unit 16; It is preferable to provide.
In addition, the vehicle braking device of the present embodiment includes a cylinder portion and a piston portion that slides in the cylinder portion in accordance with a brake operation for operating a brake operation member, and is partitioned by the piston portion. An operation corresponding pressure generating mechanism for generating a hydraulic pressure corresponding to the brake operation in the first hydraulic pressure chamber,
As the piston part slides, the input part is slid and moved in the cylinder part by being pressed directly by the piston part or by an intermediate member interposed between the piston part. And a first hydraulic pressure generating mechanism having a hydraulic pressure generating unit that generates a first hydraulic pressure according to the movement of the input unit based on the hydraulic pressure of the pressure accumulating unit that accumulates hydraulic fluid,
A braking force applying mechanism for applying a braking force to the wheels of the vehicle based on the first hydraulic pressure;
It can be said that it has. The braking device may further include a second hydraulic pressure generation mechanism that generates a desired second hydraulic pressure.

11: Brake pedal, 11a: Pedal stroke sensor,
12: Stroke simulator section, 14: Reservoir tank,
15: Booster mechanism, 15c1: Accumulator (accumulation unit), 15c2: Pump,
15c3: Electric motor, 15c4: Pressure sensor, 15d: Fluid pressure generating unit,
16: Actuator (braking force application unit, auxiliary braking force application unit),
16a: Hydraulic pressure sensor (acquisition part), 17: Brake ECU (auxiliary braking control part),
17a: Pressure accumulation control unit, 17b: Pad determination unit,
24, 34: Pressure regulating reservoir, 25, 26, 35, 36: Pressure reducing control valve,
CL: Caliper, WC: Wheel cylinder

Claims (5)

A pressure accumulator for accumulating hydraulic fluid;
An accumulator controller for controlling the hydraulic pressure in the accumulator so that the increase in the hydraulic pressure in the accumulator stops when the hydraulic pressure in the accumulator is equal to or higher than a predetermined off pressure;
Based on the hydraulic pressure in the pressure accumulating section, the hydraulic pressure generating section that mechanically generates the hydraulic pressure according to the brake operation, with the hydraulic pressure accumulated in the accumulating section as an upper limit,
A braking force applying unit that applies a braking force to the wheels of the vehicle based on the hydraulic pressure generated by the hydraulic pressure generating unit;
An acquisition unit for acquiring the required braking force;
With
When the required braking force acquired by the acquisition unit is greater than or equal to a first predetermined value, the pressure accumulation control unit is more than when the required braking force acquired by the acquisition unit is less than the first predetermined value. Also, a braking device for a vehicle that lowers the off pressure.   The pressure accumulation control unit increases the off pressure when the required braking force acquired by the acquisition unit is less than a second predetermined value smaller than the first predetermined value after reducing the off pressure. The vehicle braking device according to claim 1.   The pressure accumulation control unit controls the hydraulic pressure in the pressure accumulating unit so that the hydraulic pressure in the pressure accumulating unit increases when the hydraulic pressure in the pressure accumulating unit becomes lower than a predetermined on-pressure, and is acquired by the acquisition unit. The on-pressure is set to be lower when the required braking force is greater than or equal to the first predetermined value than when the required braking force acquired by the acquisition unit is less than the first predetermined value. Or the braking device of the vehicle of 2. A pad determination unit that determines whether or not the brake pad is normal,
The pressure accumulation control unit, when it is determined that the brake pad is not normal by the pad determination unit, and when the required braking force acquired by the acquisition unit is greater than or equal to the first predetermined value, The vehicle braking device according to any one of claims 1 to 3, wherein the off pressure is made lower than when the required braking force acquired by the acquisition unit is less than the first predetermined value. An auxiliary braking force applying unit that applies a braking force to the wheel in addition to the braking force applied to the wheel by the hydraulic pressure generated by the hydraulic pressure generating unit or the braking force applying unit;
When the required braking force acquired by the acquisition unit is higher than the braking force corresponding to the off pressure, the required braking force acquired by the acquisition unit and the braking force corresponding to the off pressure An auxiliary braking control unit that applies a hydraulic pressure corresponding to the difference by the auxiliary braking force applying unit, or applies the differential braking force by the auxiliary braking force applying unit;
The vehicle braking device according to any one of claims 1 to 4, further comprising:

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