JP4920640B2 - Brake control device - Google Patents

Description

  The present invention relates to a vehicle brake device that increases pressure of a wheel cylinder by a pump.

2. Description of the Related Art Conventionally, in a vehicular brake device that increases the pressure of a wheel cylinder by a pump, a gate-in valve is opened when the pressure is increased, and is closed when the pressure is maintained or reduced.
JP 11-129878 A

  However, in the above prior art, when switching from holding / depressurization to pressure increase, the pressure increase response must be delayed because the pressure increase must be started from the pump stop state. Further, conventionally, when switching from pressure reduction / holding to pressure increase, it is necessary to open and close the electromagnetic valve, and there is a problem that the frequency of opening and closing the electromagnetic valve increases and the sound of the opening and closing of the valve increases.

  The present invention has been made paying attention to the above-mentioned problems, and an object of the present invention is to provide a brake control device with improved response when switching from the holding / depressurized state to the increased pressure.

To achieve the above object, in the present invention, the gate-out valve in accordance with the state of the vehicle, the gate-in valve, by driving the and pump pressure increasing the pressure of said wheel cylinder, holding, vacuum A control unit that performs automatic brake control that is automatically performed is provided. The control unit continuously drives at least the pump during automatic brake control, and opens a differential pressure that acts on the gate-in valve and opens the gate-in valve. The gate-in valve is continuously driven by controlling the electromagnetic force so that the biasing force biased in the valve or valve closing direction and the electromagnetic force are balanced, and at the time of pressure reduction by the automatic brake control, the gate-out valve is While controlling the valve opening direction to return the brake fluid in the wheel cylinder to the master cylinder, the pump supplies the brake fluid via the gate-in valve. Type, it was decided to control the opening amount of the said gate-in valve so that the amount of brake fluid is less that the pump than the amount of brake fluid returned to the master cylinder is sucked and the gate-out valve.

  Therefore, it is possible to provide a brake control device that improves the response when switching from the held / depressurized state to the increased pressure, and reduces the frequency of opening and closing of the electromagnetic valve to suppress the hitting sound when the valve is opened and closed.

  Hereinafter, the best mode for realizing the brake control device of the present invention will be described based on the embodiments shown in the drawings.

[System configuration]
Example 1 will be described. FIG. 1 is a system configuration diagram of a brake control device. The brake control device has a so-called tandem master cylinder M / C, and is connected to FL and FR wheel cylinders W / C (FL, FR) by manual circuits A (FL) and A (FR).

  The master cylinder M / C is provided with a booster BS. As the brake pedal BP is depressed, hydraulic pressure is generated in the master cylinder M / C. SW outputs ON signal to ACC / CU300.

  The hydraulic unit HU supplies the master cylinder pressure Pmc boosted through the oil passage D (FL to RR) to each wheel cylinder W / C (FL to RR), and generates a braking force.

  The control unit 1 is provided with an engine ECU 200 in addition to the ACC / CU 300 and the brake ECU 100, and is connected to each other via a CAN bus so that bidirectional communication is possible. The steering angle θ detected by the steering angle sensor 2 provided on the steering wheel SW is output to the ACC / CU 300, the brake ECU 100, and the engine ECU 200 via the CAN bus.

  During automatic braking such as ACC control (adaptive cruise control), the ACC / CU 300 calculates FL to RR wheel target wheel cylinder pressures P * FL to P * RR and drives the hydraulic unit HU via the brake ECU 100. The hydraulic pressure of each wheel cylinder W / C (FL to RR) is controlled. Further, wheel speed VWS (FL to RR) is detected by a wheel speed sensor provided on each wheel FL to RR, and is output to brake ECU 100.

  Engine ECU 200 controls the throttle and ignition timing of the engine based on accelerator opening APO and steering angle θ.

[Hydraulic circuit]
FIG. 2 is a hydraulic circuit diagram of the hydraulic unit HU. The hydraulic unit HU is connected to the wheel cylinder W / C and the master cylinder M / C.

  The brake circuit is divided into two independent systems, that is, P system and S system, and has brake circuits 10P and 20S corresponding to each system. The brake circuit 10P is connected to the wheel cylinder W / C (FL) for the left front wheel and the wheel cylinder W / C (RR) for the right rear wheel, and the brake circuit 20S is connected to the wheel cylinder W / C (FR) for the right front wheel. It is connected to the wheel cylinder W / C (RL) of the rear wheel, and has a so-called X piping structure. Note that the brake circuit need not be X piping.

  The brake pedal BP transmits the driver's stepping operation to the master cylinder M / C via the booster BS and the input rod IR.

  The master cylinder M / C is a tandem type, and two hydraulic chambers are separated in the cylinder by two master cylinder pistons arranged in front and rear. Each of the two hydraulic chambers is supplied with hydraulic oil from the reservoir tank RES. One hydraulic chamber is connected to the brake circuit 10P, and the other hydraulic chamber is connected to the brake circuit 20S.

  When the brake pedal BP is depressed, the master cylinder M / C generates fluid pressure (hereinafter referred to as master cylinder pressure Pmc) in the two fluid pressure chambers according to the depression amount of the brake pedal BP. The master cylinder pressure Pmc is supplied to the brake circuits 10P and 20S, respectively.

  A known cup-shaped seal member is provided on the outer periphery of each master cylinder piston, and during the piston stroke, the communication between each hydraulic chamber and the reservoir tank RES is blocked by this seal member. Pressurization in the hydraulic chamber is possible.

  At this time, hydraulic oil is not supplied from the reservoir tank RES to the brake circuits 10P and 20S, and hydraulic oil is supplied to the brake circuits 10P and 20S only from the hydraulic chamber of the master cylinder M / C.

  On the other hand, when the brake pedal BP is returned, each master cylinder piston is returned by the force of the return spring (provided in the hydraulic pressure chamber). At this time, the hydraulic chamber of the master cylinder M / C and the reservoir tank RES communicate with each other due to the structure of the seal member. As a result, the hydraulic oil in the reservoir tank RES can be supplied again to the hydraulic chamber of the master cylinder M / C.

  On the way from the master cylinder M / C side (hereinafter referred to as upstream) of the brake circuit 10P to the wheel cylinder W / C side (hereinafter referred to as downstream), a gate-out valve GV-OUT (a normally open proportional solenoid valve) P) is provided. An oil passage 10J is connected to the brake circuit 10P in parallel with the gate-out valve GV-OUT (P).

  A check valve 10P is provided on the oil passage 10J to prevent the flow of hydraulic oil from the downstream side toward the upstream side. Hereinafter, the brake circuit 10P upstream of the gate-out valve GV-OUT (P) is referred to as a second oil passage 10N, and the brake circuit 10P downstream of the gate-out valve GV-OUT (P) is referred to as a second oil passage 10K.

  The second oil passage 10K branches to the brake circuits 10A and 10B. Brake circuits 10A and 10B are connected to wheel cylinders W / C (FL, RR), respectively. On the brake circuits 10A and 10B, pressure increasing valves IN / V (FL, RR), which are normally open proportional solenoid valves, are respectively provided.

  An oil passage 10L is connected to the brake circuit 10A in parallel with the pressure increasing valve IN / V (FL). A check valve 10Q that prevents the flow of hydraulic oil from the upstream side to the downstream side is provided on the oil passage 10L. Similarly, a check valve 10R that prevents the flow of hydraulic oil from the upstream side to the downstream side is provided on the oil passage 10M connected in parallel with the pressure increasing valve IN / V (RR).

  Return circuits 10C and 10D are connected to the brake circuits 10A and 10B on the downstream side of the pressure increasing valves IN / V (FL and RR), respectively. The return circuits 10C and 10D are each provided with a pressure reducing valve OUT / V (FL, RR) which is a normally closed on / off solenoid valve. The return circuits 10C and 10D merge to form a return circuit 10E. The return circuit 10E is connected to a reservoir 16 provided in the hydraulic unit HU.

  On the other hand, the first oil passage 10G is connected to the second oil passage 10N on the upstream side of the gate-out valve GV-OUT (P). On the first oil passage 10G, a gate-in valve GV-IN (P) which is a normally closed on / off solenoid valve for switching communication / interruption of the first oil passage 10G is provided. The first oil passage 10G joins with the return circuit 10F from the reservoir 16 to form a suction circuit 10H.

  The hydraulic pressure unit HU is provided with a pump P that sucks and discharges hydraulic oil as a hydraulic pressure source other than the master cylinder M / C. The pump P is a gear pump operated by the motor M, and includes a first pump P1 (P system) and a second pump P2 (S system). The gear pump may not be used.

  The suction side of the first pump P1 is connected to the suction circuit 10H. The discharge side of the first pump P1 is connected to the discharge circuit 10I and is connected to the second oil passage 10K via the discharge circuit 10I.

  A check valve 10S is provided on the return circuit 10F to prevent the flow of hydraulic oil from the first oil passage 10G (gate-in valve GV-IN (P)) toward the reservoir 16.

  A check valve 10U is provided on the discharge circuit 10I. The first pump P1 is provided from the second oil passage 10K (gate-out valve GV-OUT (P)) or the brake circuits 10A and 10B (wheel cylinder W / C). Prevents the flow of hydraulic fluid toward (discharge side). The hydraulic circuit on the brake circuit 20S side is configured similarly to the brake circuit 10P.

(Brake control)
The hydraulic unit HU having the above-described configuration can execute the following boost control during normal braking, as well as automatic brake control and anti-skid control such as ACC (adaptive cruise control: inter-vehicle distance control) and VDC (vehicle behavior control). Can be executed.

  At the time of automatic brake control such as vehicle behavior control, taking the brake circuit 10P side as an example, the gate-out valve GV-OUT (P) is closed while the gate-in valve GV-IN (P) is opened. At the same time, the pump P is operated to supply hydraulic oil from the master cylinder M / C to the brake circuits 10A and 10B via the first oil passages 10G and 10H and the discharge circuit 10I.

  Further, the gate-out valve GV-OUT (P) or the pressure-increasing valve IN / V (FL, RR) is controlled so as to generate the wheel cylinder target hydraulic pressure Pwc * corresponding to the braking force necessary for vehicle behavior stabilization. The same applies to the brake circuit 20S side.

  In anti-skid control, taking the wheel FL as an example, the pressure reducing valve OUT / V (FL) connected to the wheel cylinder W / C is opened and the pressure increasing valve IN / V (FL) is closed. The hydraulic oil in the wheel cylinder W / C is discharged to the reservoir 16 to reduce the pressure. When the wheel FL recovers from the locking tendency, the pressure reducing valve OUT / V (FL) is closed to maintain the wheel cylinder pressure Pwc.

  Further, the pump P is operated and the pressure increasing valve IN / V (FL) is opened to increase the pressure appropriately. The pump P plays a role of returning the hydraulic oil that has escaped to the reservoir 16 during decompression to the second oil passage 10K.

[Automatic brake pump drive control]
Conventionally, since the pump P is stopped in the holding / depressurization state during automatic braking, the pressure increase response is delayed when the pump P starts increasing pressure from the stop state when switching from the holding / depressurization state to the increase in pressure.

  Therefore, in the present application, the pump P is always driven during automatic braking, and the gate-in valve GV-IN and the gate-out valve GV-OUT are opened and closed in accordance with pressure increase / reduction / holding. As a result, the pump P is driven and the hydraulic oil is circulated even during holding and decompression, thereby improving the response when switching to pressure increase.

  In addition, conventionally, when switching from pressure reduction / holding to pressure increase, it is necessary to open and close the solenoid valve, which increases the frequency of opening and closing the solenoid valve and increases the sound of opening and closing the valve. Since the operation frequency of the side gate valve GV-IN is reduced, the hitting sound when the in-side gate valve GV-IN is opened and closed is reduced.

(When pressure is increased)
When the pressure is increased, the gate-out valve GV-OUT is closed (or the valve opening degree is set small), and the gate-in valve GV-IN is opened to supply the pump discharge pressure to the wheel cylinder W / C.

(When holding)
When holding, both the gate-out valve GV-OUT and the gate-in valve GV-IN are opened, and the master cylinder M / C → gate-in valve GV-IN → pump P → gate-out valve GV-OUT → master cylinder M / C Circulate hydraulic oil in order. At that time, the amount of circulating hydraulic oil may be made variable by controlling the valve opening amounts of the gate-in valve GV-IN and the gate-out valve GV-OUT.

(At reduced pressure)
When the pressure is reduced, the gate-out valve GV-OUT is opened to return the wheel cylinder pressure Pwc to the master cylinder M / C. The pressure reduction amount is controlled by controlling the valve opening amount of the gate-out valve GV-OUT.
At this time, the gate-in valve GV-IN is also opened, but the valve opening amount is set to be small, and the suction amount is also reduced from the master cylinder M / C.
If the relationship of the suction amount from the master cylinder M / C by the pump P <the recirculation amount from the wheel cylinder W / C to the master cylinder M / C is established, the pressure reduction is performed while the pump P is driven.

[Balance control]
Since the gate-in valve GV-IN is a normally closed electromagnetic valve, the valve body is urged in the valve closing direction by the urging member. Therefore, when controlling the valve opening amount of the gate-in valve GV-IN, it is necessary to generate an electromagnetic force in the valve opening direction against the urging force of the urging member.

Here, since the gate-in valve GV-IN has a force in the valve opening direction due to the differential pressure, the force acting on the valve element is the force in the valve opening direction: differential pressure + electromagnetic force The force in the valve closing direction: urging force Thus, when the valve opening amount control is performed, the electromagnetic force is applied by an amount corresponding to the balance between the two forces, whereby the valve opening amount control of the gate-in valve GV-IN can be performed with the minimum electromagnetic force. Hereinafter, this control is referred to as balance control.

[Automatic brake pump drive control process]
FIG. 3 is a flowchart of a pump constant drive control process during automatic brake control such as ACC.

  In step S1, it is determined whether or not the hydraulic pressure command in the automatic brake control is not 0. If YES, the process proceeds to step S2, and if NO, the process proceeds to step S3.

  In step S2, the current of the gate-in valve GV-IN is set to execute automatic brake control, and the process proceeds to step S4.

  In step S3, since automatic brake control is unnecessary, the currents of the gate-in valve GV-IN and the gate-out valve GV-OUT are set to zero, the motor M is stopped, and the control is finished.

  In step S4, it is determined whether or not the hydraulic pressure command in the automatic brake control is greater than the wheel cylinder pressure Pwc. To do.

  In step S5, it is determined whether or not the hydraulic pressure command is greater than a predetermined value. If YES, execution of the hydraulic pressure control is permitted and the process proceeds to step S7. If NO, the hydraulic pressure control is not permitted and the process proceeds to step S8. .

  In step S6, it is determined whether or not the hydraulic pressure command in the automatic brake control is smaller than the wheel cylinder pressure Pwc. If YES, the process proceeds to step S9 as a depressurization command, and if NO, the process proceeds to step S10 as a holding command.

  In step S7, the current of the gate-out valve GV-OUT at the time of pressure increase is set, the motor M is driven, and the control is finished.

  In step S8, since the hydraulic pressure control is not required, the current of the gate-out valve GV-OUT is set to 0, the number of revolutions of the motor M is controlled, and the control is terminated.

  In step S9, the current of the gate-out valve GV-OUT during decompression is set, and the control ends.

  In step S10, the current of the gate-out valve GV-OUT at the time of holding is set, and the control is finished.

[Change in pump drive control over time during automatic braking]
FIG. 4 is a time chart during automatic braking.
(Time t1)
At time t1, a pressure increase command by automatic braking is output, the normally closed gate-in valve GV-IN is opened, and the motor P drives the pump P. Since the hydraulic pressure command value is less than or equal to the predetermined value, the normally open gate-out valve GV-OUT is not energized and remains open (step S8).
That is, when the hydraulic pressure command value is less than the predetermined value and larger than the wheel cylinder pressure Pwc, the current of the gate-out valve GV-OUT is controlled to zero. The in-side gate valve GV-IN performs current control and supplies a current necessary for opening the flow path, thereby suppressing unnecessary energization and reducing heat generation of the coil as compared with the case of performing non-current control.
Further, by controlling the number of revolutions of the motor M, the discharge amount of the pump P per unit time is changed, and hydraulic pressure control is performed.

(Time t2)
At time t2, the hydraulic pressure command value> predetermined value, and the gate-out valve GV-OUT is energized when the pressure is increased (step S7).
When the hydraulic pressure command value exceeds a predetermined value, a current that balances the wheel cylinder pressure Pwc and the urging force against the valve body is applied to the out-side gate valve GV-OUT at a level that does not block the flow path (balance control). The hydraulic oil exceeding the required hydraulic pressure is allowed to flow to maintain the wheel cylinder pressure Pwc.

(Time t3)
At time t3, the automatic brake hydraulic pressure command is switched from increasing pressure to holding, the energization amount of the gate-in valve GV-IN is controlled, and the suction fluid amount of the pump P is limited. At the same time, the energization amount of the gate-out valve GV-OUT is maximized and is fully closed.
Even if the hydraulic pressure command value is constant, the hydraulic oil is discharged from the pump P, and a current that balances the urging force that urges the valve body of the out-side gate valve GV-OUT in the valve closing direction and the wheel cylinder pressure Pwc is given. In this way (balance control), more hydraulic oil than necessary is discharged to maintain the wheel cylinder pressure Pwc.
Since the hydraulic oil in the wheel cylinder W / C does not need to be increased during the holding, the current applied to the in-side gate valve GV-IN is reduced to suppress the heat generation of the coil, and the in-side gate valve GV-IN The hydraulic fluid discharged to the wheel cylinder W / C is reduced by reducing the opening degree of.

(Time t4)
At time t4, the hydraulic pressure command for automatic braking is switched to pressure reduction, and the energization amount of the gate-out valve GV-OUT is gradually reduced. The energization amount of the gate-in valve GV-IN remains controlled.

(Time t5)
At time t5, the automatic brake is not controlled, and the energization of the gate valves GV-IN, GV-OUT and the motor M is stopped, and the pump P is also stopped.

[Effect of Example 1]
(1) a pump P for generating hydraulic pressure;
First oil passages 10G, 20G connecting the master cylinder M / C and the suction side of the pump P;
Second oil passages 10K, 10N and 20K, 20N connecting the discharge side of the pump P and the master cylinder M / C;
Third oil passages 10A, 10B and 20A, 20B connecting the discharge side of the pump P and the wheel cylinder W / C;
Gate-in valves GV-IN provided in the second oil passages 10K, 10N and 20K, 20N;
A gate-out valve GV-OUT provided in the first oil passages 10G, 20G;
A control unit 1 that performs automatic brake control by driving a gate-in valve GV-IN, a gate-out valve GV-OUT, and a pump P in accordance with the state of the vehicle,
The control unit 1 continuously drives at least the pump P during the automatic brake control.

  During automatic braking, the pump P is always driven and the hydraulic oil is circulated, so that the response when switching from holding / reducing pressure to increasing pressure can be improved. Further, since the operation frequency of the in-side gate valve GV-IN is reduced, it is possible to reduce the hitting sound when the in-side gate valve GV-IN is opened and closed.

(2) The gate-out valve GV-OUT is a solenoid valve,
During the automatic brake control, the control unit 1 balances the differential pressure acting on the gate-out valve GV-OUT, the urging force that urges the gate-out valve GV-OUT in the valve opening or closing direction, and the electromagnetic force. Thus, the electromagnetic force was controlled.

  As a result, hydraulic oil greater than the required fluid amount in the pump discharge amount can be leaked from the gate-out valve GV-OUT, and fluid pressure control by feedforward becomes possible, and smooth fluid pressure control can be achieved.

(3) The gate-in valve GV-IN is normally closed,
The control unit 1 controls the gate-in valve GV-IN to a predetermined valve opening amount. Thereby, the circulation amount of the hydraulic oil can be controlled with a small current.

  (4) The control unit 1 continuously drives the pump P and the gate-in valve GV-IN during the automatic brake control. Thereby, the frequency | count of an operation | movement can be reduced and the sound of a valve | bulb can be reduced, and the effect similar to said (1) can be acquired.

  (5) Not limited to the automatic brake, the pump P and the gate-in valve GV-IN may be continuously driven when the wheel cylinder W / C is increased, held, or depressurized. Thereby, the effect similar to said (4) can be acquired.

  Example 2 will be described. The basic configuration is the same as that of the first embodiment. The second embodiment is different in that the opening degree of the gate-in valve GV-IN is controlled by the differential value of the master cylinder pressure Pmc.

[Opening correction based on master cylinder pressure Pmc differential value]
FIG. 5 is a diagram showing the relationship between the master cylinder pressure Pmc differential value and the correction amount of the gate-in valve GV-IN opening.

  When the depression speed of the brake pedal BP increases, the differential value of the master cylinder pressure Pmc increases, and the differential value of the amount of hydraulic fluid flowing out from the master cylinder M / C also increases. At this time, if the opening of the gate-in valve GV-IN is small, the hydraulic oil is difficult to flow out of the master cylinder M / C, and the brake pedal BP is also difficult to stroke, and the pedal feeling is deteriorated.

  Therefore, in the second embodiment, the opening degree of the gate-in valve GV-IN is controlled by the differential value of the master cylinder pressure Pmc. If the master cylinder pressure Pmc differential value is larger than the threshold value + a, the correction amount is increased to the plus side to increase the opening, and the hydraulic oil outflow from the master cylinder M / C is increased to stroke the brake pedal BP. Make it easier.

  On the other hand, if the master cylinder pressure Pmc differential value is smaller than the threshold value -a, the correction amount is increased to the minus side to decrease the opening, thereby suppressing excessive hydraulic oil outflow from the master cylinder M / C, and braking. This prevents the pedal BP from making a stroke too much and the pedal feeling from becoming too soft.

[Gate-in valve opening control process in the second embodiment]
FIG. 6 is a flowchart for controlling the opening of the gate-in valve GV-IN based on the differential value of the master cylinder pressure Pmc.

  In step S11, the brake switch B. It is determined whether the SW is ON. If YES, the process proceeds to step S12, and if NO, the process proceeds to step S13.

  In step S12, the opening of the gate-in valve GV-IN is set as a reference value for automatic braking, and the process proceeds to step S14.

  In step S13, it is determined whether or not the hydraulic pressure command value in the automatic brake is greater than the wheel cylinder pressure Pwc. If YES, the process proceeds to step S15 as an automatic brake pressure increase. Transition.

  In step S14, the opening degree of the in-side gate valve GV-IN is set to a correction amount (see FIG. 5) based on the reference value + master cylinder pressure Pmc differential value, and the process proceeds to step S19.

  In step S15, the opening of the gate-in valve GV-IN is set to a predetermined value at the time of automatic brake pressure increase, and the process proceeds to step S19.

  In step S16, it is determined whether or not the hydraulic pressure command value in the automatic brake is smaller than the wheel cylinder pressure Pwc. If YES, the process proceeds to step S17 as the automatic brake pressure reduction, and if NO, the process proceeds to step S18 as the automatic brake holding. .

  In step S17, the opening of the gate-in valve GV-IN is set to a predetermined value at the time of automatic brake pressure reduction, and the process proceeds to step S19.

  In step S18, the opening of the gate-in valve GV-IN is set to a predetermined value when the automatic brake is held, and the process proceeds to step S19.

  In step S19, the current of the in-side gate valve GV-IN is set so that the opening degree determined in steps S14, S15, S17, and S18 is reached, and the control is terminated.

[Time-dependent change of gate-in valve opening control]
FIG. 7 is a time chart when the opening degree of the gate-in valve GV-IN is controlled by the master cylinder pressure Pmc differential value.

(Time t11)
At time t11, a pressure increase command by automatic braking is output, the normally closed gate-in valve GV-IN is opened, and the pump P is driven by the motor M. Since the hydraulic pressure command value is less than or equal to the predetermined value, the normally open gate-out valve GV-OUT is not energized and remains open (step S8).

(Time t12)
At time t12, the hydraulic pressure command value> predetermined value, and the gate-out valve GV-OUT is energized when the pressure is increased (step S7).

(Time t13)
At time t13, the brake switch B. SW is turned on. Along with this, the current of the normally closed gate-in valve GV-IN is reduced, the opening degree is lowered, the excessive stroke of the brake pedal BP is suppressed, and the pedal feeling is obtained.
In addition, the energization amount of the normally open gate-out valve GV-OUT is decreased to increase the opening, and the recirculation amount to the master cylinder M / C is increased to ensure the stroke of the brake pedal BP.
Further, the master cylinder pressure Pmc is increased by the operation of the brake pedal BP, and the differential value is also increased. Since master cylinder pressure Pmc differential value <threshold value a, the opening degree of gate-in valve GV-IN is not increased.

(Time t14)
Automatic brake holding control is started at time t14, and the hydraulic pressure command value becomes constant.
Further, the master cylinder pressure Pmc differential value ≧ the threshold value a. Along with this, in order to secure the amount of hydraulic oil flowing out from the master cylinder M / C and improve pedal feeling, the current of the gate-in valve GV-IN is increased to increase the opening.

(Time t15)
At time t15, the master cylinder pressure Pmc differential value <threshold value a, the energization amount of the gate-in valve GV-IN is reduced, and the opening degree is reduced.

(Time t16)
Although the master cylinder pressure Pmc decreases and the differential value becomes negative, it does not reach the negative threshold value -a, and the opening control of the gate-in valve GV-IN based on the differential value is not performed.
Further, as the master cylinder pressure Pmc decreases, the energization amount of the gate-out valve GV-OUT is increased to lower the opening and decrease the recirculation amount.

(Time t17)
At time t17, the brake switch B. SW is turned OFF and the master cylinder pressure Pmc becomes zero. In order to maintain the automatic brake holding pressure, the in-side gate valve GV-IN is opened to continue the suction of hydraulic oil.

(Time t18)
At time t18, the hydraulic pressure command of the automatic brake is switched to pressure reduction, and the energization amount of the gate-out valve GV-OUT is gradually decreased. The energization amount of the gate-in valve GV-IN remains controlled.

(Time t19)
At time t19, the automatic brake non-control state is established, the energization of the gate valves GV-IN and GV-OUT and the motor M is stopped, and the pump P is also stopped.

[Effect of Example 2]
In the second embodiment, the opening degree of the gate-in valve GV-IN is controlled by the differential value of the master cylinder pressure Pmc. If the master cylinder pressure Pmc differential value is larger than the threshold value + a, the correction amount is increased to the plus side to increase the opening degree. If it is smaller than the threshold value −a, the correction amount is increased to the minus side and the opening degree is increased. Decrease.

  Thereby, when the differential value is large on the positive side, the brake pedal BP can be easily stroked, and when the differential value is large on the negative side, an excessive stroke of the brake pedal BP can be prevented. Therefore, in addition to the effects of the first embodiment, the operational feeling of the brake pedal BP can be improved.

[Other embodiments]
The best mode for carrying out the present invention has been described based on the embodiments. However, the specific configuration of the present invention is not limited to each embodiment, and the scope of the invention is not deviated. Design changes and the like are included in the present invention.

It is a system configuration figure of a brake control device. It is a hydraulic circuit diagram of a hydraulic unit. 3 is a flowchart of pump constant drive control processing during automatic brake control according to the first embodiment. 3 is a time chart at the time of automatic braking according to the first embodiment. It is a figure which shows the relationship between the master cylinder pressure differential value in Example 2, and the correction amount of a gate in valve opening. It is a flowchart of the opening degree control of a gate-in valve based on a master cylinder pressure differential value in Example 2. It is a time chart at the time of controlling the opening degree of a gate in valve by the master cylinder pressure differential value in Example 2.

Explanation of symbols

1 Control unit 10G, 20G 1st oil path 10K, 10N, 20K, 20N 2nd oil path 10A, 10B, 20A, 20B 3rd oil path GV-IN Gate-in valve GV-OUT Gate-out valve P Pump M / C Master Cylinder W / C Wheel cylinder

Claims (2)

A pump for generating hydraulic pressure,
A first oil passage connecting the master cylinder and the suction side of the pump;
A second oil passage connecting the discharge side of the pump and the master cylinder;
A third oil passage connecting the discharge side of the pump and the wheel cylinder;
A gate-out valve composed of a solenoid valve provided in the second oil passage;
A gate-in valve comprising an electromagnetic valve provided in the first oil passage;
A control unit that performs automatic brake control to automatically increase, hold, and reduce the pressure of the wheel cylinder by driving the gate-out valve, the gate-in valve, and the pump according to the state of the vehicle; With
The control unit continuously drives at least the pump during the automatic brake control, a differential pressure acting on the gate-in valve, and an urging force that urges the gate-in valve in the valve opening or closing direction. , The electromagnetic force is controlled so as to balance with the electromagnetic force, and the gate-in valve is continuously driven, and the gate-out valve is controlled in the valve opening direction when the pressure is reduced by the automatic brake control. While returning the brake fluid to the master cylinder, the pump sucks brake fluid through the gate-in valve so that the amount of brake fluid sucked by the pump is smaller than the amount of brake fluid returned to the master cylinder. A brake control device that controls a valve opening amount of the gate-in valve and the gate-out valve . The brake control device according to claim 1, wherein
The gate-in valve is normally closed,
The control unit controls the gate-in valve to a predetermined valve opening amount.
Brake control device.

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