JP4789882B2 - Brake control device - Google Patents

Description

  The present invention relates to a brake control device capable of increasing and decreasing a wheel cylinder hydraulic pressure so as to achieve a target deceleration.

  As a brake control device, a technique described in Patent Document 1 is known. The brake control device generates wheel cylinder pressure according to the operating force of the brake pedal, the state of the vehicle, etc., and applies a braking force to the vehicle. The brake fluid pressure control device includes two pumps for pressurizing brake fluid in the wheel cylinder, a pressure increasing valve and a pressure reducing valve provided for each wheel cylinder, and further, communication between the master cylinder and the wheel cylinder is shut off. And a shut-off valve. When this shut-off valve is closed, the wheel cylinder pressure is controlled by two pumps, a pressure increasing valve, and a pressure reducing valve.

Basically, pressure increase in the wheel cylinder is performed by supplying brake fluid from at least one pump to the wheel cylinder, opening the pressure increasing valve, and closing the pressure reducing valve. The wheel cylinder is depressurized by closing the pressure increasing valve and opening the pressure reducing valve. At this time, the pump is driven and controlled so that the pump pressure becomes the maximum value of all the command wheel cylinder pressures or a pressure obtained by adding a predetermined value to the maximum value.
Japanese Patent No. 3409721

  In the configuration of the prior art, during brake-by-wire control, for example, when the command hydraulic pressure of a certain wheel cylinder is increasing, the deviation from the command value of the wheel cylinder pressure is increased for some reason, and pressure reduction is performed. Closes the booster valve. At this time, since the capacity on the pump discharge side is reduced, if the pump response is slow, the pump discharge pressure increases rapidly. Thereafter, when the decompression of the wheel cylinder is completed and the command hydraulic pressure of the wheel cylinder is increased, the pressure increasing valve is opened again. However, since the pump discharge pressure is increasing, it is difficult to adjust the pressure increase valve opening unless at least feedback using the pump discharge pressure sensor is executed. If adjustment of the opening of the booster valve is not successful, the wheel cylinder pressure will increase excessively again, and this may cause repeated pressure reduction, which may cause the wheel cylinder pressure to vibrate. was there.

  The present invention has been made paying attention to the above problem, and an object of the present invention is to provide a brake control device capable of stabilizing the wheel cylinder pressure without using a pump discharge pressure sensor or the like. .

  To achieve the above object, according to the present invention, there are provided a wheel cylinder provided on each of a plurality of wheels, a hydraulic pressure source capable of pressurizing brake fluid in the wheel cylinder, the hydraulic pressure source, and the wheel cylinder. A check valve that is provided between the hydraulic pressure source side and the wheel cylinder side to allow only a brake fluid flow, and a pressure increasing valve that adjusts a flow rate of the brake fluid flowing from the hydraulic pressure source to the wheel cylinder; A pressure reducing valve for adjusting a flow rate of brake fluid flowing out from the wheel cylinder to the reservoir, target hydraulic pressure calculating means for calculating a target hydraulic pressure in each wheel cylinder, and a pressure increasing valve corresponding to each target hydraulic pressure. Based on the target fluid pressure detecting means for calculating the target flow rate, the actual fluid pressure detecting means for detecting the fluid pressure in the wheel cylinder, and the target fluid pressure and the actual fluid pressure, the pressure reducing valve is fully closed. Control mode determination for determining one of a pressure increasing mode for proportionally controlling the pressure increasing valve, a holding mode in which the pressure increasing valve and the pressure reducing valve are fully closed, and a pressure reducing mode in which the pressure increasing valve is fully closed and the pressure reducing valve is proportionally controlled. Based on the control mode, the hydraulic pressure source control means for controlling the discharge hydraulic pressure of the hydraulic pressure source so as to be the maximum value of the target hydraulic pressure of the wheel cylinder in the pressure increasing mode, An electromagnetic valve control means for fully opening, proportionally and fully closing the pressure increasing valve and the pressure reducing valve, and a pressure increasing valve for fully opening at least one of the pressure increasing valves regardless of a control command by the electromagnetic valve control means A full-opening control means, wherein the pressure-increasing valve full-opening control means is configured such that when a certain wheel cylinder is in the pressure-increasing mode and both the target hydraulic pressure and the target flow rate are maximum among the plurality of wheel cylinders. The ho The pressure increase valve belonging to the wheel cylinder is fully opened, and when a certain wheel cylinder is in the holding mode or the pressure reduction mode and the target hydraulic pressure is the maximum among the plurality of wheel cylinders, the pressure increase valve belonging to the wheel cylinder is In other cases, the pressure increasing valve that is proportionally controlled by the electromagnetic valve control means is fully opened, among the pressure increasing valves that are proportionally controlled by the electromagnetic valve control means.

  In this way, considering the target flow rate, by fully opening at least one pressure increasing valve, the capacity on the hydraulic pressure source side is sufficiently secured, the pressure of the hydraulic pressure source is stabilized, and the wheel cylinder pressure is stabilized. Can be controlled. Further, since it can be predicted that the pressure of the wheel cylinder with the pressure increasing valve fully opened is substantially equal to the pressure of the hydraulic pressure source, the control system can be configured without using the pressure sensor attached to the hydraulic pressure source. it can. Further, even when the wheel cylinders having different capacities and pipe lengths are controlled by one hydraulic pressure source, the wheel cylinder pressure can be controlled according to the command value. Further, when the environment such as the temperature and the viscosity of the brake fluid changes, even when there is a variation for each brake fluid pressure control device, the vibration of the wheel cylinder pressure can be suppressed.

  Hereinafter, the best embodiment of the present invention will be described with reference to the drawings.

[Brake-by-wire system configuration]
FIG. 1 is an overall block diagram of a brake-by-wire system. The hydraulic brake-by-wire system is a system in which a pump is driven by an electric motor, and the hydraulic pressure in the wheel cylinder is controlled by the pump hydraulic pressure (or the hydraulic pressure accumulated in the accumulator), thereby generating a braking force. To tell.

  The brake-by-wire system according to the first embodiment includes two hydraulic units HU1 and HU2. The hydraulic unit HU1 is a hydraulic unit that controls the hydraulic pressure of the left front wheel FL and the right rear wheel RR, and the hydraulic unit HU2 is a hydraulic unit that controls the hydraulic pressure of the right front wheel FR and the left rear wheel RL. is there. These two hydraulic units HU1,2 constitute the X piping structure.

  The main ECU is based on the input signals of the sensors that detect various vehicle conditions and the driver's brake pedal operation state, etc., and the normal brake control calculation according to the driver's operation, anti-skid brake control (hereinafter, ABS), Performs calculations to control tire slip and vehicle behavior using vehicle information such as vehicle behavior control (hereinafter referred to as VDC), inter-vehicle distance control, obstacle avoidance control, etc., and the braking force required for the vehicle (all wheels ) To calculate the braking force target value required for each wheel.

  Controllers ECU1 and ECU2 are attached to the hydraulic units HU1 and HU2 respectively, and are connected to the main ECU via a communication line. Each controller ECU1, ECU2 receives the braking force target value calculated by the main ECU, calculates the target hydraulic pressure at which the hydraulic pressure of each wheel can achieve the braking force target value, and the wheel cylinder pressure becomes the target hydraulic pressure. The wheel cylinder hydraulic pressure is controlled so that Here, examples of the sensors that detect various vehicle states include a longitudinal acceleration sensor, a lateral acceleration sensor, a yaw rate sensor, a rudder angle sensor, a wheel speed sensor, a CCD camera, a laser radar, and a millimeter wave radar.

  The master cylinder M / C is provided with a stroke sensor S / Sen and a stroke simulator S / Sim. As the brake pedal BP is depressed, hydraulic pressure is generated in the master cylinder M / C, and the stroke signal S of the brake pedal BP is output to the control unit CU.

  Here, the stroke simulator S / Sim is a configuration for ensuring a driver's brake pedal stroke and brake pedal depression force. This is because, in the brake-by-wire system, the hydraulic circuit between the master cylinder side and the wheel cylinder side is shut off in order to independently control the relationship between the driver's brake pedal operation amount and the actual wheel cylinder pressure.

  The master cylinder M / C is a tandem type with two cylinder chambers. The oil is supplied from one cylinder chamber to the hydraulic unit HU1 through the oil passage A (FR, RL), and is supplied from the other cylinder chamber to the hydraulic unit HU2 through the oil passage A (FL, RR). The hydraulic unit HU1 and the hydraulic unit HU2 are the same except for the target wheels. Therefore, only the hydraulic unit HU1 will be described below. The hydraulic unit HU1 is driven by the control unit ECU1 and hydraulic pressure control is performed, and then supplied to the wheel cylinder W / C (FL, RR) belonging to the diagonal wheel via the oil passage D (FL, RR). The

  The main ECU calculates the regenerative braking force and the friction brake force in consideration of limitations such as battery SOC (State Of Charge) and actuator response while achieving the required braking force. The braking force is generated by the regenerative braking device MGB, and in the case of the friction braking force, the FR and FL wheel target hydraulic pressures P * fr and P * fl are calculated and transmitted to both control units ECU1 and ECU2. As a result, both hydraulic units HU1, 2 are driven, and the braking force is generated by controlling the hydraulic pressure of the wheel cylinders W / C (FL, FR).

  The hydraulic unit HU1 cuts off the communication between the master cylinder and the wheel cylinders W / C (FL, RR) during normal braking in the brake-by-wire system. On the other hand, a hydraulic pressure is supplied to the wheel cylinder W / C (FL, RR) by the pump P to generate a braking force.

  Then, the hydraulic pressure in the front wheel cylinder W / C (FL, RR) is reduced by appropriately driving a pressure reducing valve. Also, when the brake-by-wire function fails, the master cylinder pressure is supplied to the FL wheel wheel cylinder W / C (FL) in the hydraulic unit HU1, and the master cylinder pressure is supplied to the FR wheel cylinder in the hydraulic unit HU2. Supply to W / C (FR) to obtain braking force.

[Hydraulic circuit]
FIG. 2 is a hydraulic circuit diagram of the hydraulic unit HU1 according to the first embodiment. Since the same applies to the hydraulic unit HU2, only the hydraulic unit HU1 is shown. The discharge side of the pump P is connected to the FL and RR wheel wheel cylinders W / C (FL, RR) via the oil passage C (FL, RR) and the oil passage D (FL, RR), respectively, and the suction side is the oil passage. Connect to reservoir RSV via B. The oil passage C (FL, RR) is connected to the oil passage B via the oil passage E (FL, RR).

  The connection point I (FL) between the oil passage C (FL) and the oil passage E (FL) is connected to the master cylinder M / C via the oil passage A (FL, RR). A connection point I (RR) between the oil passage C (RR) and the oil passage E (RR) is connected to the pump P through the oil passage C (RR). Further, the connection point J of the oil passage C (FL, RR) is connected to the oil passage B through the oil passage G.

  Shut-off valve S. OFF / V (FL) is a normally open solenoid valve, which is provided on the oil passage A (FL, RR) and communicates / cuts off the master cylinder M / C and the connection point I (FL).

  The FL and RR wheel booster valves IN / V (FL, RR) are normally open proportional valves provided on the oil passage C (FL, RR), respectively, and the discharge pressure of the pump P is proportionally controlled to control the FL and RR wheels. Supply to wheel cylinder W / C (FL, RR). In addition, a check valve C / V (FL, RR) on the oil passage C (FL, RR) and between the FL and RR wheel booster valves IN / V (FL, RR) for preventing backflow to the pump P side. ) Is provided.

  The FL and RR wheel pressure reducing valves OUT / V (FL, RR) are normally closed proportional valves and are provided on the oil passages E (FL, RR), respectively. A relief valve Ref / V is provided on the oil passage G connecting the connection point J and the oil passage B.

  Shut-off valve S. The oil path A (FL) between the OFF / V (FL) and the master cylinder M / C is provided with a first M / C pressure sensor MC / Sen1, and outputs the M / C pressure PM1 to the control unit ECU1. Also, FL and RR wheel hydraulic pressure sensors WC / Sen (FL, RR) are provided in the hydraulic unit HU1 and on the oil passage D (FL, RR), and the detected values Pfl and Prr are sent to the control unit ECU1. Output.

[Normal brake in brake-by-wire control]
(When pressure is increased)
Shut-off valve S during normal brake pressure increase in brake-by-wire control. OFF / V (FL) is closed, booster valve IN / V (FL, RR) is opened, decompression valve OUT / V (FL, RR) is closed, motor M is driven, booster valve IN / V Increase the pressure by controlling the fluid pressure with (FL, RR).

(At reduced pressure)
During normal brake pressure reduction, the predetermined pressure increase valve IN / V (FL, RR) is closed, the pressure reduction valve OUT / V (FL, RR) is opened, the hydraulic pressure is discharged to the reservoir RSV, and pressure reduction is performed. Note that the booster valve that performs full-opening control of the booster valve described later is not closed.

(When holding)
When holding the normal brake, the predetermined pressure increasing valve IN / V (FL, RR) and pressure reducing valve OUT / V (FL, RR) are closed to maintain the hydraulic pressure. As in the case of the pressure reduction, the pressure increasing valve that performs the pressure increasing valve full open control described later is not closed.

[Manual brake]
Normally open shut-off valve S. OFF / V and pressure increase valve IN / V (FL, RR) are opened, and normally closed pressure reducing valve OUT / V (FL, RR) is closed. Therefore, the master cylinder pressure Pm acts on the FL wheel wheel cylinder W / C (FL). This ensures a manual brake. That is, the braking force is generated only on the front wheel side.

[Brake-by-wire booster valve fully open control]
If the oil passage volume from the pump discharge side to the booster valve is set small to reduce the size of the device, the oil passage volume that absorbs pump pulsation will be reduced when the booster valve is closed, and pressure fluctuation on the pump discharge side will be reduced. It becomes larger and the controllability deteriorates. Therefore, in Example 1 of the present application, among the wheel cylinders W / C (FL, RR) using the hydraulic brake, the pressure increasing valve IN / V_H on the side with the higher target hydraulic pressure P * is fully opened (the flow path area is maximized). .

  Since the hydraulic circuit of the first embodiment increases the pressure of the FL and RR wheel cylinders W / C (FL, RR) with a single pump P, the pump discharge pressure Pp is at least the high pressure wheel cylinder when there is a pressure increasing wheel. The target hydraulic pressure of P * _H must be exceeded. On the other hand, the target hydraulic pressure P * _L of the low pressure side wheel cylinder may be obtained by proportionally controlling the discharge pressure Pp by the pressure increasing valve IN / V.

  Therefore, the pressure increasing valve IN / V_H on the side with the higher target hydraulic pressure P * is fully opened, and the wheel cylinder W / C_H on the side with the higher target hydraulic pressure P * is directly controlled by the pump discharge pressure Pp. As a result, the discharge side of the pump P and the wheel cylinder W / C_H on the side with the higher target hydraulic pressure P * are in communication with each other, and the oil passage volume on the pump discharge side is increased to reduce the vibration of the hydraulic oil on the pump discharge side. To do. Further, since the wheel cylinder W / C_H on the side where the target hydraulic pressure P * is higher is directly controlled by the pump discharge pressure Pp, the discharge pressure Pp of the pump P may be the minimum necessary.

  Here, in order to feedback control the discharge pressure Pp of the pump P, it is necessary to provide a pump discharge pressure sensor for detecting the pump discharge pressure. In the first embodiment, since the pressure increasing valve IN / V_H on the high target hydraulic pressure P * _H side is fully opened, the pump discharge pressure Pp and the hydraulic pressure P_H on the high target hydraulic pressure P * _H side are substantially equal. Therefore, the pump discharge pressure sensor can be omitted by detecting the pump discharge pressure Pp with the hydraulic sensor WC / Sen_H on the high target hydraulic pressure side. That is, in the first embodiment, the hydraulic pressure of the wheel that maximizes the flow path area among the plurality of wheels is selected, and this hydraulic pressure is estimated as the pressure of the hydraulic pressure source, thereby reducing the discharge pressure of the hydraulic pressure source. The hydraulic pressure sensor to be detected is omitted.

  That is, in the pressure-increasing valve full-opening control in the brake-by-wire according to the first embodiment, a wheel that requires the maximum hydraulic pressure is selected, and a feedback loop is configured between the wheel cylinder pressure of the wheel and the pump P (hereinafter referred to as the following). The other wheels independently form a feedback loop between the wheel cylinder pressure and the pressure increasing valve IN / V (hereinafter referred to as a second feedback loop).

  Normally, when the opening degree of the booster valve IN / V changes, the hydraulic pressure downstream of the booster valve IN / V can be controlled, while the hydraulic pressure upstream of the booster valve IN / V also changes. Therefore, the influence of the second feedback loop may affect the second feedback loop of other wheels, and the control system may diverge. On the other hand, in the first embodiment, a stable control system is configured by acting so as to absorb the influence of the first feedback loop on the upstream side of the pressure increasing valve IN / V in the second feedback loop.

  Here, the problem of fully opening the pressure increasing valve attached to the wheel cylinder having the maximum target hydraulic pressure will be described. Generally, the maximum value of the required braking force differs between the front wheel and the rear wheel of the vehicle, and an appropriate braking force distribution ratio exists regardless of the maximum value. This is because μ varies depending on load movement and vehicle weight distribution during braking.

  In a normal vehicle, this braking force distribution ratio is distributed to about 7: 3 on the front wheel side: rear wheel side, for example. Accordingly, naturally, the required maximum braking force is different and the size of the caliper that presses the brake pad is different, so that the volume of the wheel cylinder is configured larger on the front wheel side than on the rear wheel side.

  As in the first embodiment, one pump P is provided as a hydraulic pressure source, each wheel cylinder is provided with a pressure increasing valve and a pressure reducing valve, a wheel cylinder on the front wheel side having a large capacity, and a wheel on the vehicle rear wheel side having a small capacity. In the case where the cylinder is controlled by a single hydraulic unit, it is considered that the front wheel and the rear wheel are increased to the same pressure.

  Since the target hydraulic pressure of each wheel cylinder is the same, if the pressure increasing valve attached to each wheel cylinder is fully opened in the same manner, the wheel cylinder capacity on the rear wheel side is small. The pressure is increased faster than the front wheel cylinder, resulting in a difference between the front and rear wheel cylinder pressures. This difference increases as the flow rate increases, and becomes more significant when a step-like target hydraulic pressure is output. In other words, since the flow rate of the valve is determined from the pressure loss and the valve opening, it is necessary to consider not only the target hydraulic pressure of the wheel cylinder to which the pressure increasing valve is attached, but also the target flow rate. is there.

  When the wheel cylinder pressure control mode is maintained or reduced on the high pressure side and suddenly increased on the low pressure side, strictly speaking, the low pressure side pressure increasing valve may be fully opened and the high pressure side pressure increasing valve may be fully closed. However, such booster control cannot be achieved by simply selecting the maximum target hydraulic pressure and fully opening the booster.

  Here, if the amount of leakage during holding of the high-pressure side wheel cylinder is large or if the pressure reduction of the high-pressure side wheel cylinder is too large relative to the target hydraulic pressure, the high-pressure side wheel cylinder pressure control mode is The pressure increase may be repeated in a short cycle. Even in such a case, if the pressure increasing valve control mode does not change, the pressure of the hydraulic pressure source and the wheel cylinder pressure are stabilized.

  The pressure increase valve on the low pressure side should be fully opened in a limited case where the pressure increase gradient on the low pressure side is very large and the hydraulic pressure difference from the high pressure side is very small. The time until the side exceeds the target hydraulic pressure on the high pressure side is very short.

  Therefore, the pressure increasing valve is fully opened only when the target flow rate is the maximum value even in the pressure increasing mode and the target fluid pressure is the maximum value. On the other hand, since the check valve C / V exists in the holding or pressure reducing mode, the pressure increasing valve is fully opened when the target hydraulic pressure is the maximum value.

  Here, if the booster valve is fully opened in accordance with the above logic, for example, the target hydraulic pressure of the rear wheel is higher in the booster mode, but the flow rate is higher in the booster valve as in the case of the front wheel being larger. There is a case where both are not fully opened and both are proportionally controlled. Therefore, at that time, the control mode is corrected so that the booster valve corresponding to the target current closest to the fully opened current among the target currents of the proportional control is set to the fully opened control. Hereinafter, a specific flowchart based on the logical configuration will be described.

[Brake-by-wire control processing]
FIG. 3 is a flowchart showing the flow of the brake-by-wire control process. Hereinafter, each step will be described.

In step S10, it is determined whether the target hydraulic pressure mode is increased, held, or reduced, and the process proceeds to step S20.
In step S20A, correction processing for the pressure increase threshold value and the pressure reduction threshold value is executed based on the target hydraulic pressure mode determined in step S10.
In step S20, based on the pressure increase threshold value and pressure reduction threshold value set in step S20A and the wheel cylinder hydraulic pressure deviation, it is determined whether the W / C hydraulic pressure control mode is to be increased, held, or reduced.

In step S30, it is determined whether the pressure increasing valve control mode is fully opened, fully closed, or proportional control (intermediate opening), and the process proceeds to step S30A.
In step S30A, it is determined whether the pressure reducing valve control mode is fully open, fully closed, or proportional control (intermediate opening), and the process proceeds to step S40.

  In step S40, it is determined whether or not there is at least one W / C whose W / C hydraulic pressure control mode is increased. If YES, the process proceeds to step S50, and if NO, the process proceeds to step S60.

In step S50, a pump control process is executed, and the process proceeds to step S60.
In step S60, it is determined whether the pressure increasing valve control mode is proportional control. If YES, the process proceeds to step S70, and if NO, the control is terminated.

  In step S70, the target current of the pressure increasing valve corresponding to the proportional control is determined as the pressure increasing valve control processing.

  In step S80, the pressure increasing valve control mode is corrected (see FIG. 8).

In step S90, the final target pressure of the booster valve is output according to the corrected booster valve control mode, and the control is terminated. For example, even if it is determined in step S60 that proportional control is to be performed, there is a case where full open control should be performed. At this time, the target current of the pressure increasing valve corresponding to the full open control is output, and otherwise, the target current of the pressure increasing valve determined in step S70 is output.
In step S60A, it is determined whether the pressure reducing valve control mode is proportional control. If YES, the process proceeds to step S70A, and if NO, the control is terminated.
In step S70A, the target current of the pressure reducing valve corresponding to the proportional control is determined as the pressure reducing valve control process.

  In step S90A, the target current of the pressure reducing valve is output and the control is terminated.

[Target hydraulic pressure mode decision processing]
FIG. 4 is a flowchart showing the flow of the target hydraulic pressure mode determination process (FIG. 3: step S10).
In step S11, it is determined whether or not the gradient ΔP * of the target hydraulic pressure P * is equal to or greater than the pressure increase command threshold. If YES, the process proceeds to step S13, and if NO, the process proceeds to step S12.
In step S12, it is determined whether or not the target hydraulic pressure gradient ΔP * ≦ the pressure reduction command threshold value. If YES, the process proceeds to step S14, and if NO, the process proceeds to step S15.

In step S13, the target hydraulic pressure mode is increased and the control is terminated.
In step S14, the target hydraulic pressure mode is reduced, and the control is terminated.
In step S15, the target hydraulic pressure mode is maintained and the control is terminated.

[Threshold correction processing]
FIG. 5 is a correction table showing the relationship of threshold correction processing (FIG. 3: step S20A). When the pressure is increased by the target hydraulic pressure mode determination process, the pressure increase threshold is corrected to be smaller than a preset reference pressure increase threshold, and the pressure reduction threshold is set to a preset reference pressure reduction. Correction is made to be larger than the threshold value. As a result, a threshold value that is easy to increase in pressure and difficult to decrease in pressure is set.

  Similarly, when the pressure is reduced by the target hydraulic pressure mode determination process, the pressure increase threshold is corrected to be larger than a preset reference pressure increase threshold, and the pressure reduction threshold is set in advance. Correction is made to be smaller than the reference decompression threshold. As a result, a threshold value that is easy to be depressurized and difficult to increase is set. Note that when the target hydraulic pressure mode is determined to be retained, the threshold value is not particularly corrected.

[W / C fluid pressure control mode decision processing]
FIG. 6 is a flowchart showing the flow of the W / C hydraulic pressure control mode determination process (FIG. 3: step S20). As the threshold value in this step, the increasing / decreasing threshold value corrected in step S20A is used.
In step S21, it is determined whether or not the deviation ΔP of the W / C target hydraulic pressure P * and the actual hydraulic pressure is equal to or greater than the pressure increase threshold. If YES, the process proceeds to step S23, and if NO, the process proceeds to step S22. .
In step S22, it is determined whether or not the deviation ΔP between the target hydraulic pressure P * of W / C and the actual hydraulic pressure is equal to or less than the pressure reduction threshold. If YES, the process proceeds to step S24, and if NO, the process proceeds to step S25.

In step S23, the W / C hydraulic pressure control mode is increased and the control is terminated.
In step S24, the W / C hydraulic pressure control mode is reduced, and the control is terminated.
In step S25, the W / C hydraulic pressure control mode is maintained and the control is terminated.

[Pressure increase valve control mode decision processing]
FIG. 7 is a flowchart showing the flow of the booster valve control mode determination process (FIG. 3: step S30).

  In step S31, it is determined whether or not the W / C hydraulic pressure control mode is increased. If the pressure is increased, the process proceeds to step S32. Otherwise, the process proceeds to step S36.

  In step S32, it is determined whether or not the target W / C hydraulic pressure P * (for example, the FL wheel) is the maximum value among the respective W / C target hydraulic pressures P * fl and P * rr. If YES, the process proceeds to step S33. If NO, the process proceeds to step S32.

  In step S33, it is determined whether the target flow rate Q * vfl or Q * vrr is the maximum. If YES, the process proceeds to step S34, and otherwise, the process proceeds to step S35.

In step S34, the pressure increasing valve control mode is fully opened, and the control is terminated.
In step S35, the pressure increasing valve control mode is set to proportional control, and the control is terminated.

In step S36, it is determined whether or not the target W / C hydraulic pressure P * (for example, the FL wheel) is the maximum value among the respective W / C target hydraulic pressures P * fl and P * rr. If YES, the process proceeds to step S34. If NO, the process proceeds to step S37.
In step S37, the pressure increasing valve control mode is fully closed, and the control is terminated.

[Intensification valve control correction processing]
In step S41, it is determined whether or not a wheel cylinder that is fully opened as the pressure increasing valve control mode is present. If not, the process proceeds to step S42, and otherwise, the present control process is terminated.

  In step S42, it is determined whether or not the pressure increasing valve control mode is proportional control. If proportional control is performed, the process proceeds to step S43. Otherwise, the control flow is terminated because full-closed control is performed.

  In step S43, it is determined whether or not the pressure increase valve target current by proportional control is the maximum in each wheel cylinder. If it is the maximum, the process proceeds to step S44, and otherwise, the control flow ends.

  In step S44, the pressure increasing valve control mode is corrected to be fully open, and this control flow is terminated.

[Pressure booster valve target current determination processing]
In step S51, it is determined whether or not the pressure increasing valve control mode is fully open. If fully open, the process proceeds to step S52. Otherwise, the process proceeds to step S53.

  In step S52, the target current of the pressure increasing valve is set to a fully open current, and this control is terminated.

  In step S53, it is determined whether or not the pressure increasing valve control mode is fully closed. If it is fully closed, the process proceeds to step S54. Otherwise, the process proceeds to step S55.

  In step S54, the booster valve target current is set to a fully closed current, and this control is terminated.

  In step S55, the booster valve target current is set to the target current set in the booster valve control mode determination process, and this control is terminated.

[Pressure reducing valve control mode determination process]
FIG. 10 is a flowchart showing the flow of the pressure reducing valve control mode determination process (FIG. 3: step S30A).

  In step S201, it is determined whether or not the W / C hydraulic pressure control mode is reduced pressure. If the pressure is reduced, the process proceeds to step S202. Otherwise, the process proceeds to step S203.

In step S202, the pressure reducing valve control mode is set to proportional control.
In step S203, the pressure reducing valve control mode is fully closed.

[Pump control processing block diagram]
FIG. 11 is a block diagram of the pump control process executed in step S50 of FIG. The pump control is controlled by the pump control unit P.1 in the control unit ECU1,2. It shall be executed in CU.

  Pump control unit P. The CU includes a target amount calculation unit 110, a target pump pressure calculation unit 111, a W / C fluid amount deviation FB (feedback) calculation unit 112, a pump leak amount calculation unit 113, a motor target rotation number calculation unit 114, a loss torque calculation unit 115, It has a target rotation speed differential calculation unit 116 and a rotation speed deviation FB (feedback) calculation unit 117.

  The target amount calculation unit 110 uses the experimental data of the load stiffness of the caliper and its accessories as shown in FIG. 12 and based on the target hydraulic pressure P * (FL, RR) of each wheel FL, RR. The flow rate Qp * is calculated and output to the multiplication unit 122. Further, the target fluid amount Vw * (FL, RR) of each wheel cylinder W / C (FL, RR) is calculated and output to the adding unit 131. Further, the target hydraulic pressure P * _H of the pressure increasing valve IN / V system wheel cylinder that is fully open is output to the target pump pressure calculation unit 111.

  The target pump pressure calculation unit 111 calculates the target pump pressure Pp * based on the target hydraulic pressure P * _H of the pressure increasing valve IN / V system wheel cylinder that is fully open, the pump leak amount calculation unit 113, the loss torque calculation unit 115 And to the multiplication unit 121.

  The multiplication unit 121 multiplies the target pump pressure Pp * by the theoretical discharge amount Vth / 2π per rotation of the pump P, calculates the required theoretical torque Tth of the pump P required to output the target pump pressure Pp *, and adds it. Output to 134.

  The W / C fluid amount deviation FB calculating unit 112 calculates the target fluid amount Vw * (FL, RR) and the actual fluid amount Vw (FL, RR) of the wheel cylinder W / C (FL, RR) calculated in the adding unit 131. The feedback control calculation is performed using the deviation ΔVw (FL, RR) of the output, and the feedback component ΔVw (FB) is output to the adder 132.

  The pump leak amount calculation unit 113 calculates a pump leak amount Qpl based on an experimental value or the like, and outputs it to the addition unit 132.

  The adding unit 132 adds the pump leak amount Qpl, the fluid amount deviation FB component ΔVw (FB), and the product of the pump target flow rate Qp * and the inverse of the theoretical discharge amount Vth (calculated by the multiplying unit 122), and adds the motor target Output to rotation number calculation unit 114.

  Motor target rotation number calculation unit 114 calculates motor target rotation number N * based on the addition value calculated by addition unit 132, and outputs the result to loss torque calculation unit 115, target rotation number differentiation calculation unit 116, and addition unit 133.

  The loss torque calculation unit 115 calculates the loss torque Tlo of the motor M from the experimental data and the like based on the motor target rotation speed N * and the target pump pressure Pp *, and outputs it to the addition unit 134.

  Target rotation speed differential calculation section 116 differentiates motor target rotation speed N * and outputs the result to inertia moment calculation section 123.

  The inertia moment calculation unit 123 calculates a torque necessary for acceleration / deceleration of the angular velocity of the motor M, and outputs the torque to the addition unit 135.

  A rotation speed deviation FB (feedback) calculation unit 117 performs feedback control calculation based on a deviation ΔN (calculated by the addition unit 133) between the target rotation speed N * of the motor M and the actual rotation speed N, and a feedback component ΔN of the rotation speed deviation ΔN. (FB) is output to the adding unit 135.

  The adding unit 134 adds the theoretical torque Tth and the loss torque Tlo of the motor M to calculate the load torque Td and outputs it to the adding unit 135.

  The adder 135 calculates the target torque T * of the motor M by adding the load torque Td of the motor M, the rotational speed deviation FB component ΔN (FB), and the torque necessary for acceleration / deceleration of the angular velocity of the motor M, and converts the current. To the unit 124.

  The current converter 124 converts the target torque T * into a target torque current and outputs it to the motor M to drive the pump P.

[Pressure increase valve control processing block diagram]
FIG. 13 is a block diagram of the pressure increasing valve control process executed in step S70 of FIG. FIG. 13 shows a case where P * fl> P * rr, the RR wheel booster valve IN / V (RR) is proportionally controlled, and the FL wheel booster valve IN / V (FL) is fully opened.

  The booster valve control process includes a target amount calculator 150, a target pump pressure calculator 161, a wheel cylinder differential pressure deviation FB (feedback) calculator 162, a booster valve target current calculator 163, a current deviation FB (feedback) calculator 164, The booster valve voltage Duty calculation unit 165 is configured.

  Based on the target hydraulic pressure P * (FL, RR) of each wheel FL, RR, the target amount calculating unit 150 sets the target hydraulic pressure P * _H (here, P * _H = P * fl), the target flow rate Qvrr of the RR wheel booster valve IN / V (RR), and the RR wheel target hydraulic pressure P * rr are output. The target flow rate Qv * rr of the RR wheel wheel cylinder is output as a value obtained by differentiating the value converted from the target hydraulic pressure P * rr into the target fluid amount.

  The RR wheel target hydraulic pressure P * rr is output to the adders 171 and 172. Further, the RR wheel booster valve target flow rate Qvrr is output to the booster valve target current calculator 163.

  The target pump pressure calculation unit 161 calculates the target pump pressure Pp * based on the fully opened target W / C pressure P * _H (P * _H = P * fl), and outputs Pp * to the addition unit 171. .

  The adding unit 171 calculates the difference between the target pump pressure Pp * and the RR wheel target hydraulic pressure P * rr and outputs the difference to the pressure increasing valve target current calculating unit 163 as the RR wheel pressure increasing valve target differential pressure ΔPv * rr.

  The adding unit 172 calculates a deviation ΔPwrr between the target hydraulic pressure P * rr of the RR wheel hydraulic pressure and the actual hydraulic pressure Prr, and outputs it to the wheel cylinder differential pressure deviation FB calculating unit 162.

  The wheel cylinder differential pressure deviation FB calculation unit 162 feedback-controls the differential pressure deviation ΔPwrr and outputs a feedback component ΔPwrr (FB) of the differential pressure deviation ΔPwrr to the pressure increase valve target current calculation unit 163.

  The booster valve target current calculation unit 163 increases the RR wheel based on the target differential pressure ΔPv * rr and the differential pressure deviation FB component ΔPwrr (FB) of the RR wheel booster valve and the target flow rate Qvrr of the RR wheel booster valve IN / V (rr). The pressure valve target current I * rr is calculated and output to the pressure increasing valve voltage duty calculation unit 165 and the addition unit 173.

  The adding unit 173 calculates a deviation ΔIrr (FB) between the target current I * rr of the FL wheel booster valve IN / V (RR) and the actual current Irr, and outputs the deviation ΔIrr (FB) to the current deviation FB calculating unit 164.

  The current deviation FB calculator 164 outputs the feedback component ΔIrr (FB) of the current deviation ΔIrr of the RR wheel booster valve IN / V (RR) to the booster valve voltage duty calculator 165.

  The booster voltage Duty calculation unit 165 calculates the RR wheel booster valve IN / V (RR) based on the power monitor value from the power monitor 180, the RR wheel booster valve target current I * rr, and the current deviation feedback component ΔIrr (FB). The voltage Duty is calculated, and the RR wheel pressure increasing valve IN / V (rr) is driven to proportionally control the RR wheel hydraulic pressure Prr.

[Reducing valve proportional control]
FIG. 14 is a block diagram showing the pressure reducing valve control performed in step S70A.

  The target amount calculation unit 250 outputs each wheel target hydraulic pressure P * to the target differential pressure calculation unit 261 and the deviation calculation unit 272. Further, the fully-opened OUT / V target flow rate Qvout is calculated and output to the OUT / V target current calculation unit 263. The calculation of the target flow rate will be described later.

  When the target hydraulic pressure P * is determined, the differential pressure upstream and downstream of the pressure reducing valve OUT / V may be the target hydraulic pressure P *. Since the downstream of the pressure reducing valve OUT / V is almost atmospheric pressure, the target differential pressure is equal to the target hydraulic pressure. When the target differential pressure is large, it is necessary to reduce the amount of liquid flowing out from the pressure reducing valve OUT / V.Therefore, the target current value I * out is set to a small value, and when the target differential pressure is small, from the pressure reducing valve OUT / V The target current value I * out is set large because there is no need to reduce the amount of liquid flowing out.

(About target flow rate component)
The amount of fluid corresponding to the fluid pressure means that if this amount of fluid flows into the wheel cylinder system, this amount of pressure is generated. Since the change in the liquid amount is a flow rate, the target flow rate per unit time when flowing into the wheel cylinder system is calculated as a differential value of the liquid amount. Therefore, the target amount calculation unit 250 first converts the wheel cylinder target fluid pressure P * into the wheel cylinder target fluid amount using the experimental data of the load stiffness of the caliper and its accessories shown in FIG. Is the wheel cylinder target flow rate.

  Here, the pressure reducing valve OUT / V is an element that controls the amount of outflow from the wheel cylinder system. The target flow rate described above represents the flow rate that flows into the wheel cylinder system, and does not represent the flow rate that flows out from the pressure reducing valve OUT / V. Therefore, when the wheel cylinder target flow rate is positive, the pressure reducing valve OUT / V should not be opened because there is a pressure increase request, so 0 is output to the OUT / V target current calculation unit 263 as the pressure reducing valve target flow rate Qvout.

  On the other hand, when the wheel cylinder target flow rate is negative, since there is a pressure reduction request, the pressure reducing valve target flow rate Qvout is converted to an absolute value of the wheel cylinder target flow rate and a value obtained by reversing the sign is output. As a result, when the wheel cylinder target flow rate is negative, it is necessary to reduce the pressure by causing the brake fluid to flow out from the pressure reducing valve OUT / V, so the target current value to the pressure reducing valve OUT / V increases.

(About current feedback control)
When the target current value I * out is determined as described above, feedback control of the pressure reducing valve OUT / V is performed by feedback control with the current value detected from the solenoid of the pressure reducing valve OUT / V, and the wheel cylinder pressure is reduced. It is controlled appropriately.

[Pressure increasing valve control time chart when the target hydraulic pressure is the same for the front and rear wheels]
FIG. 15 shows a comparison of the FL and RR wheel hydraulic pressures, the target current of the pressure increasing valve, the actual current, and the motor rotation speed when the target hydraulic pressures of the FL and RR wheels are set to the same pressure by the control of the first embodiment. It is a chart. In FIG. 15A, the thick solid line indicates the target hydraulic pressures P * fl and P * rr of the FL and RR wheels, the thin solid line indicates the actual hydraulic pressure of the FL wheel, and the dotted line indicates the actual hydraulic pressure of the RR wheel. In FIG. 15B, the thick solid line represents the motor rotation speed, the thin solid line represents the actual current value of the FL wheel booster valve IN / V (FR), and the dotted line represents the actual pressure of the RR wheel booster valve IN / V (rr). Represents the current value.

  At time t1, each wheel pressure increase command is output, and the target hydraulic pressures P * fl and P * rr rise. Both FL and RR wheels have increased pressure. Here, although P * fl = P * fr, since the capacity of the wheel cylinder on the rear wheel side is smaller than that on the wheel cylinder on the front wheel side, the target flow rate is calculated to be small. Therefore, the high-pressure side FL wheel booster valve IN / V (FL) is fully opened, and the low-pressure side RR wheel booster valve IN / V (RR) is proportionally controlled. At this time, both pressure reducing valves are fully closed. In this way, by slightly reducing the RR wheel booster valve IN / V (RR), the same pressure can be maintained on the FL wheel side, which is the front wheel side with the larger capacity, and the RR wheel side, which is the rear wheel side with the smaller capacity. Can do.

[Time chart during holding]
Next, a comparison between the control (hereinafter referred to as a comparative example) in which the pressure increasing valve is proportionally controlled or fully closed in the holding or pressure reducing mode and the control in the first embodiment will be shown. FIG. 16 is a time chart when different target hydraulic pressures are set for the FL wheel and the RR wheel by the control of the comparative example, and only the FL wheel is held and controlled, and FIG. 17 is the FL wheel and the RR wheel by the control of the first embodiment. FIG. 18 is a time chart showing the pump speed of the comparative example, and FIG. 19 is a time showing the pump speed of the first embodiment. FIG. 20 is a time chart showing the current values of the pressure increasing valve / pressure reducing valve of the comparative example, and FIG. 21 is a time chart showing the current values of the pressure increasing valve / pressure reducing valve of the first embodiment. Although the pump pressure is measured in FIGS. 16 and 17, the detected pump pressure is not used for control.

(Time t101)
At time t101, the FL and RR wheel target hydraulic pressure P * (fl, rr) is output for both the comparative example and the first embodiment.
Since the pressure increasing gradient is RR wheel> FL wheel (see FIGS. 16 and 17), the in-valve IN / V (RR) is fully open and the out valve OUT / V (RR) is fully closed on the high-pressure RR wheel side. . For this reason, both the normally open in-valve IN / V (RR) and the normally closed out-valve OUT / V (RR) are deenergized on the RR wheel side.
On the other hand, the in-valve IN / V (FL) is proportionally controlled on the low-pressure FL wheel side. Therefore, on the FL wheel side, the normally open in-valve IN / V (FL) is energized, and the normally closed out valve OUT / V (FL) is de-energized.

(Time t102)
At time t102, a holding command is output to the RR wheel, and the RR wheel target hydraulic pressure P * rr is held. The pressure increase continues for the FL wheel. The RR wheel out valve OUT / V (rr) on the holding side drives the RR wheel out valve OUT / V (RR) to keep the RR wheel hydraulic pressure Prr, which is the holding wheel, constant. Drain pressure. The FL wheel out valve OUT / V (FL) during pressure increase is closed.

  In the comparative example, the RR wheel on the high pressure side is also held by proportional control or closing of the in-valve IN / V (RR), so that the pump P rotates with the in-valve IN / V (RR) set to an intermediate opening or valve closing. That is, since the pump P rotates while repeating both the state where both the in-valves IN / V (RR) and IN / V (FL) are throttled and the state where one is fully open, the capacity on the pump discharge side fluctuates. The pump pressure is oscillating. Therefore, the vibration of the RR wheel actual hydraulic pressure Prr increases. In addition, proportional control or closing of the in-valve IN / V (RR) is performed against this hydraulic vibration, and the FL-wheel in-valve IN / V connected to the RR-wheel in-valve IN / V (RR) via an oil passage. The hydraulic oil in V (FL) also vibrates, and the FL wheel in-valve current IINfl also vibrates.

  On the other hand, in Example 1, the RR wheel in-valve IN / V (RR) on the high pressure side is fully opened (current IINrr = zero), so compared with the comparative example in which the RR wheel in valve on the high pressure side is proportionally controlled or closed. The oil path volume between the RR wheel wheel cylinder W / C (FR) and the pump P discharge side increases, and the pump pressure is reduced to the wheel cylinder W / C (RR) without being reduced by the in-valve IN / V (RR). To reach.

  Therefore, the vibration of the RR wheel actual hydraulic pressure Pfr is smaller than that of the comparative example. In addition, since the vibration of the FL wheel actual hydraulic pressure Pfl on the low pressure side is also reduced, the FL wheel in-valve current IINfl becomes stable.

(Time t103)
At time t103, a pressure increase command is output to the RR wheel, and the RR wheel target hydraulic pressure P * rr increases. The pressure increase continues for the FL wheel. Therefore, on the high-pressure RR wheel side, the normally open in-valve IN / V (RR) is fully open (current IINrr = 0) and the normally closed out valve OUT / V (RR) is fully closed (current IOUTrr = 0). . On the low-pressure FL wheel side, the normally open in-valve IN / V (FL) is proportionally controlled (current IINfl> 0), and the normally closed out-valve OUT / V (FL) is closed.

(Time t104)
At time t104, a holding command is output to the RR wheel, and the RR wheel target hydraulic pressure P * rr is held. The pressure increase continues for the FL wheel. In order to keep the RR wheel hydraulic pressure Pfr as the holding wheel at a constant pressure, the RR wheel out valve OUT / V (RR) is driven to discharge the excess pressure from the pump P.
Similar to the time t102, in the comparative example in which the RR wheel in-valve IN / V (RR) is not fully opened, the FL and RR wheel in-valve current IIN (fl, rr) vibrates due to the vibration of the actual hydraulic pressure P (fl, rr). In the first embodiment in which the RR wheel in-valve IN / V (RR) on the high pressure side is fully opened, vibration is suppressed.

As described above, the effects listed below can be obtained in the first embodiment.
(1) When a wheel cylinder is in the pressure-increasing mode and both the target hydraulic pressure and the target flow rate are the maximum among the plurality of wheel cylinders, the pressure-increasing valve belonging to this wheel cylinder is fully opened, and a certain wheel cylinder When the target hydraulic pressure is the maximum among the plurality of wheel cylinders in the holding mode or the pressure reducing mode, the pressure increasing valve belonging to the wheel cylinder is fully opened, and in other cases, the proportional control is performed. Among the pressure valves, the pressure increasing valve closest to the fully opened control amount is determined to be fully opened.

  As described above, when at least one pressure increasing valve is fully opened, the capacity on the hydraulic pressure source side is sufficiently secured, the pressure of the hydraulic pressure source is stabilized, and the wheel cylinder pressure can be stably controlled. . Further, since it can be predicted that the pressure of the wheel cylinder with the pressure increasing valve fully opened is substantially equal to the pressure of the hydraulic pressure source, the control system can be configured without using the pressure sensor attached to the hydraulic pressure source. it can. Further, even when the wheel cylinders having different capacities and pipe lengths are controlled by one hydraulic pressure source, the wheel cylinder pressure can be controlled according to the command value. Further, when the environment such as the temperature and the viscosity of the brake fluid changes, even when there is a variation for each brake fluid pressure control device, the vibration of the wheel cylinder pressure can be suppressed.

  (2) As a pressure increasing valve and / or a pressure reducing valve, a proportional solenoid valve whose opening degree can be arbitrarily set in a range from fully closed to fully open is used. Thereby, the good hydraulic pressure control of the system excellent in silence can be achieved.

  (3) A gear pump driven by a brushless motor was provided as a hydraulic pressure source. Therefore, in addition to fine motor control, fluid pressure control with good system can be achieved by a pump having a small discharge amount per motor rotation angle.

  (4) In addition, the booster valve and / or the pressure reducing valve can only be set to fully open and fully open, and execute proportional control based on the ratio of the fully open time and / or fully closed time within a predetermined time. It is good also as an electromagnetic valve to do. That is, by controlling the on / off valve by duty control or PWM control, high controllability can be ensured by an inexpensive solenoid valve.

  (5) The hydraulic pressure source may be a gear pump driven by a brush motor. Since the brush motor is inexpensive, the cost can be reduced.

  (6) The hydraulic pressure source may be a plunger pump driven by a brush motor. Since both the brush motor and the plunger pump are inexpensive, the cost can be further reduced.

  (7) The hydraulic pressure source may be a plunger pump driven by a brushless motor. Controllability can be improved by a brushless motor.

  A second embodiment will be described with reference to FIGS. The basic configuration is the same as that of the first embodiment. In the first embodiment, the hydraulic brake by wire control of the X pipe having two hydraulic units HU1 and HU2 is used. However, the second embodiment differs in that the hydraulic brake by wire control is performed on all four wheels by one hydraulic unit. .

  FIG. 22 is a system configuration diagram in the second embodiment, and FIG. 23 is a hydraulic circuit diagram. The brake hydraulic device is a hydraulic brake-by-wire system that normally increases the pressure of the wheel cylinders W / C (FL to RR) of all four wheels by one pump Main / P. The master cylinder M / C is a so-called tandem type and is connected to the FL and RR wheel cylinders W / C (FL, FR) by manual circuits A (FL), A (FR).

  The master cylinder M / C is connected to the reservoir RSV, and each solenoid valve is driven by the control unit CU. The pump, which is the hydraulic pressure source, is provided with a main pump Main / P for normal use and a sub pump Sub / P for emergency use, which are driven by the main motor Main / M and the sub motor Sub / M based on commands from the control unit CU. The

  The manual circuit A (FL, FR) is provided with a shut-off valve S.OFF/V (FL, FR), which is a normally open solenoid valve (ON / OFF valve), and the first and second master cylinders M / C / M / C2 and FL / FR wheel cylinder W / C (FL, FR) are connected / disconnected.

  A stroke simulator S / Sim is provided on the manual circuit A (FR) and between the first master cylinder M / C and the shut-off valve S.OFF/V (FR). This stroke simulator S / Sim is connected to the manual circuit A (FR) via a cancel valve Can / V which is a normally closed solenoid valve (ON / OFF valve).

  When the FR shut-off valve S.OFF/V (FR) is closed and the cancel valve Can / V is opened, the hydraulic oil in the first master cylinder M / C is released as the brake pedal BP is depressed. Introduced to the stroke simulator S / Sim to secure the pedal stroke.

  The discharge sides of the main and sub pumps Main / P and Sub / P are connected to a pressure-increasing circuit C and connected to each wheel cylinder W / C (FL to RR) at a connection point I (FL to RR). On the other hand, the suction side of each pump Main / P, Sub / P is connected to a decompression circuit B.

  On this pressure increasing circuit C, pressure increasing valves IN / V (FL to RR), which are normally closed solenoid valves (proportional valves), are provided. Each pump Main / P, Sub / P and each wheel cylinder W / C (FL Switch between communication / blocking (~ RR).

  Each wheel cylinder W / C (FL to RR) is connected to the decompression circuit B at the connection point I (FL to RR). On this pressure reducing circuit B, a pressure reducing valve OUT / V (FL to RR), which is a normally closed solenoid valve (proportional valve), is provided, and communication / blocking between each wheel cylinder W / C (FL to RR) and the reservoir RSV is provided. Switch.

  A check valve C / V is provided on the discharge side of each pump Main / P and Sub / P, and hydraulic fluid flows backward from the pressure increasing circuit C to the pressure reducing circuit B via each pump Main / P and Sub / P. Avoid that. Further, the pressure increasing circuit C and the pressure reducing circuit B are connected via a relief valve Ref / V, and when the pressure in the pressure increasing circuit C becomes equal to or higher than a specified value, hydraulic fluid is released to the pressure reducing circuit B.

  On the manual circuit A (FL, RR) between the shutoff valve S.OFF/V (FL, RR) and the master cylinder M / C, the first and second master cylinder pressure sensors MC / Sen1 , 2 are provided, and each wheel cylinder W / C (FL to RR) is provided with a hydraulic pressure sensor WC / Sen (FL to RR). A pump discharge pressure sensor P / Sen is provided on the pressure increasing circuit C.

  The control unit CU receives the detected first and second master cylinder pressures Pm1 and Pm2, the hydraulic pressures P (FL to RR), and the detection value of the stroke sensor S / Sen that detects the stroke of the brake pedal BP. The

  Based on these detected values, the control unit CU calculates the target hydraulic pressure P * (FL to RR) of each wheel FL to RR, and each motor Main / M, Sub / M and the pressure increasing valve IN / V (FL to RR). ), Driving the pressure reducing valve OUT / V (FL to RR). During normal braking, the shut-off valve S.OFF/V (FL, RR) is closed and the cancel valve Can / V is opened.

  The control unit CU also compares the target hydraulic pressure P * (FL to RR) and actual hydraulic pressure P (FL to RR) of each wheel cylinder W / C (FL to RR) to When the hydraulic pressure shows an abnormal response, an abnormal signal is output to the warning lamp WL. In addition, the wheel speed VSP is input to the control unit CU to determine whether the vehicle is running / stopped.

[Brake control]
(Normal pressure increase)
During normal pressure increase, cancel valve Can / V is opened and shut-off valve S. OFF / V (FL, RR) is cut off and the depression of the brake pedal BP by the driver is detected by the stroke sensor S / Sen. Based on this detection value, each wheel cylinder W / C (FL to RR) is detected in the control unit CU. The target hydraulic pressure P * (FL to RR) is calculated.

  Further, the control unit CU drives the main motor Main / M or the sub motor Sub / M to apply the discharge pressure to the pressure increasing circuit C. Furthermore, each booster valve IN / V (FL to RR) is driven according to the calculated target hydraulic pressure P * (FL to RR), and hydraulic oil is supplied to each wheel cylinder W / C (FL to RR). Get braking force.

(At reduced pressure)
At the time of decompression, each decompression valve OUT / V (FL to RR) is driven by the control unit CU, and hydraulic oil is discharged from each wheel cylinder W / C (FL to RR) to the reservoir RSV via the decompression circuit B. .

(When holding)
At the time of holding, the specified pressure increasing valve IN / V (FL to RR) and each pressure reducing valve OUT / V (FL to RR) are closed, each wheel cylinder W / C (FL to RR) and pressure increasing and pressure reducing circuit Shut off C and B. The booster valve that performs full-opening control of the booster valve described later is not closed.

(Manual brake)
Normally open shut-off valve in case of system failure. OFF / V (FL, RR) is opened, each normally closed pressure increasing valve IN / V (FL to RR) and FL, RR wheel pressure reducing valve OUT / V (FL, RR) are closed, RL, RR The ring pressure reducing valve OUT / V (RL, RR) is opened.

  As a result, the master cylinder M / C communicates with the FL and RR wheel wheel cylinders W / C (FL, FR), and a manual brake is secured. On the other hand, the RL and RR wheel wheel cylinder pressures Prl and Prr are substantially zero to prevent locking.

  Even when all of the four wheels are controlled by the hydraulic unit HU, the same effects as in the first embodiment can be obtained by performing the same control as in the first embodiment. However, in Example 2, since the pressure increasing valve is a normally closed valve, the process shown in FIG. 24 is added between step S80 and step S90 of FIG.

  In step S61, it is determined whether or not at least one of the following conditions is satisfied. If satisfied, the process proceeds to step S62, and the pressure increasing valve control mode is fully closed. In other cases, the control flow ends and the process proceeds to step S90.

(List of conditions)
Condition 1: If the vehicle is stopped, the increase / decrease request is not frequently issued, and it is not necessary to suppress the vibration of the pump.

Condition 2: If all target W / C pressure modes are not increasing pressure, and the holding or depressurizing mode has been requested continuously for a certain period of time, it is necessary to drive the pump. This is because there is no need to suppress vibration of the pump.

Condition 3: Booster valve temperature ≧ threshold pressure When the temperature of the booster valve becomes equal to or higher than the threshold value, normal operation of the booster valve cannot be expected. In such a case, the durability of the booster valve itself is ensured rather than the vibration of the pump. Because. The pressure increasing valve temperature may be estimated from the integrated value of the energized current or the like, or may be directly measured using a temperature sensor or the like, and is not particularly limited.

Condition 4: When the pressure increasing valve energizing time ≧ threshold energizing time is long, the temperature of the pressure increasing valve may be increased.

[Other Examples]
As mentioned above, although this invention has been demonstrated based on Example 1, 2, this invention is not restricted to the said structure, Even if it applies to another structure, the same effect can be acquired.

  For example, in the second embodiment, the hydraulic pressure of the four wheels is controlled by one hydraulic pressure unit HU. However, even if the configuration includes separate hydraulic pressure units HU on the front wheel side and the rear wheel side, The same control as that in the first embodiment can be executed in the hydraulic unit HU.

1 is a system configuration diagram of a vehicle to which a brake control device of Embodiment 1 is applied. It is a figure which shows the structure of the hydraulic circuit and control unit in the system of Example 1. FIG. It is a flowchart which shows the flow of the brake-by-wire control process of Example 1. 3 is a flowchart illustrating a flow of target hydraulic pressure mode determination processing according to the first embodiment. 3 is a correction table for correcting an increase / decrease threshold value according to the first embodiment. 3 is a flowchart illustrating a flow of W / C hydraulic pressure control mode determination processing according to the first embodiment. 3 is a flowchart illustrating a flow of a pressure increasing valve control mode determination process according to the first embodiment. 6 is a flowchart illustrating a flow of a correction process in a pressure increasing valve control mode according to the first embodiment. 3 is a flowchart illustrating a flow of determining a command current according to a pressure increasing valve control mode according to the first embodiment. 3 is a flowchart illustrating a flow of a pressure reducing valve control mode determination process according to the first embodiment. FIG. 3 is a block diagram of pump control processing according to the first embodiment. It is experimental data of the load rigidity of the caliper and its accessories, which is the relationship between the fluid pressure and the fluid volume. FIG. 3 is a block diagram of a pressure increasing valve control process according to the first embodiment. FIG. 3 is a block diagram illustrating pressure reducing valve control according to the first embodiment. 3 is a time chart showing a relationship between a hydraulic pressure, a motor rotation speed, and a pressure increasing valve current in the control of the first embodiment. It is a time chart showing the change of the hydraulic pressure in a comparative example. 3 is a time chart showing a change in hydraulic pressure in Example 1. It is a time chart showing the pump rotation speed in a comparative example. 3 is a time chart showing pump rotation speed in the first embodiment. It is a time chart showing each solenoid valve current in a comparative example. 3 is a time chart showing each solenoid valve current in Example 1. FIG. It is a system configuration | structure figure of the vehicle to which the brake control apparatus of Example 2 was applied. It is a figure which shows the structure of the hydraulic circuit and control unit in the system of Example 2. FIG. 6 is a flowchart illustrating a pressure increasing valve control mode correction process according to a second embodiment.

Explanation of symbols

MGB regenerative braking device
BP brake pedal
C / V check valve
Can / V cancel valve
ECU1,2 Control unit
HU1,2 1st and 2nd hydraulic unit
IN / V Booster Valve M Motor
M / C master cylinder
MC / Sen1, MC / Sen2 Master cylinder pressure sensor
OUT / V Pressure reducing valve P Pump (gear pump)
P / Sen pump discharge pressure sensor
Ref / V relief valve
RSV reservoir
S Shutoff valve
S / Sen Stroke sensor
S / Sim stroke simulator
W / C wheel cylinder
WC / Sen hydraulic pressure sensor

Claims (7)

A wheel cylinder provided on each of a plurality of wheels;
A hydraulic pressure source capable of pressurizing the brake fluid in the wheel cylinder;
A check valve provided between the hydraulic pressure source and the wheel cylinder, which allows only a flow of brake fluid from the hydraulic pressure source side to the wheel cylinder side;
A pressure increasing valve that adjusts the flow rate of brake fluid flowing from the hydraulic pressure source into the wheel cylinder;
A pressure reducing valve for adjusting a flow rate of the brake fluid flowing out from the wheel cylinder to the reservoir;
Target hydraulic pressure calculating means for calculating the target hydraulic pressure in each of the wheel cylinders;
Target flow rate calculation means for calculating a target flow rate of the pressure increasing valve according to each target hydraulic pressure;
An actual hydraulic pressure detecting means for detecting the hydraulic pressure in the wheel cylinder;
Based on the target hydraulic pressure and the actual hydraulic pressure, a pressure increasing mode in which the pressure reducing valve is fully closed and the pressure increasing valve is proportionally controlled, a holding mode in which the pressure increasing valve and the pressure reducing valve are fully closed, and the pressure increasing valve are Control mode determining means for determining the pressure reducing mode to be fully closed and proportionally controlling the pressure reducing valve;
Hydraulic pressure source control means for controlling the discharge hydraulic pressure of the hydraulic pressure source so as to be the maximum value among the target hydraulic pressures of the wheel cylinders in the pressure increasing mode;
Based on the control mode, electromagnetic valve control means for controlling the full-opening, proportional and full-closing of the pressure increasing valve and the pressure reducing valve;
Regardless of the control command by the electromagnetic valve control means, the pressure increase valve full open control means for fully opening at least one pressure increase valve among the pressure increase valves;
With
The pressure increasing valve full open control means
When a certain wheel cylinder is in the pressure increasing mode and both the target hydraulic pressure and the target flow rate are the maximum among the plurality of wheel cylinders, the pressure increasing valve belonging to the wheel cylinder is fully opened,
When a certain wheel cylinder is in the holding mode or the pressure-reducing mode and the target hydraulic pressure is the maximum among the plurality of wheel cylinders, the pressure increasing valve belonging to the wheel cylinder is fully opened,
In other cases, the brake control device is characterized in that, among the pressure increasing valves that are proportionally controlled by the electromagnetic valve control means, the pressure increasing valve closest to the fully opened control amount is fully opened. The brake control device according to claim 1, wherein
The brake control device according to claim 1, wherein the pressure increasing valve and / or the pressure reducing valve is a proportional solenoid valve whose opening degree can be arbitrarily set in a range from fully closed to fully open. The brake control device according to claim 1, wherein
The pressure-increasing valve and / or the pressure-reducing valve is an electromagnetic valve whose opening degree can be set only in a fully-closed state and a fully-opened state, and that performs proportional control based on the ratio of the fully-open time and / or the fully-closed time within a predetermined time Brake control device characterized by being. The brake control device according to any one of claims 1 to 3,
The brake control device according to claim 1, wherein the hydraulic pressure source is a gear pump driven by a brush motor. The brake control device according to any one of claims 1 to 3,
The brake control device according to claim 1, wherein the hydraulic pressure source is a gear pump driven by a brushless motor. The brake control device according to any one of claims 1 to 3,
The brake control device according to claim 1, wherein the hydraulic pressure source is a plunger pump driven by a brush motor. The brake control device according to any one of claims 1 to 3,
The brake control device according to claim 1, wherein the hydraulic pressure source is a plunger pump driven by a brushless motor.

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