JP2022011485A - Vehicle brake fluid pressure control device - Google Patents

Abstract

To suppress a decrease in brake fluid pressure against a driver's intention during vehicle stop time holding control.SOLUTION: A vehicle brake fluid pressure control device is a vehicle brake fluid pressure control device capable of executing vehicle stop time holding control (time t2 to t3) for holding brake fluid pressure when it is determined that a vehicle has stopped. The vehicle brake fluid pressure control device releases the vehicle stop time holding control even if there is no operation of an operation member for operating the vehicle when a first condition is satisfied (time t3), the first condition including a fact that a vehicle body speed Vb at the time of brake input is equal to or greater than a speed specified value Vth, a fact that an absolute value (maximum value Awmax) of a wheel deceleration has exceeded a deceleration specified value Ath after the brake input, and a fact that a lateral behavior amount (yaw rate Y) of the vehicle is equal to or greater than the specified value Yth during the vehicle stop time holding control.SELECTED DRAWING: Figure 7

Description

The present invention relates to a vehicle brake fluid pressure control device.

Conventionally, for example, as a vehicle brake fluid pressure control device that executes a stop hold control for holding a brake fluid pressure when the vehicle is stopped, the brake fluid pressure is lowered when a yaw rate is applied to the vehicle during the stop hold control. Is known (see Patent Document 1). With this technology, when a vehicle that was stopped on a low μ road surface such as an ice road slides down while rotating, the brake fluid pressure that was held drops, so the wheel lock is released and the driver operates it. It is possible to rebuild the vehicle.

Special Table 2006-528579

However, if the brake fluid pressure is lowered based only on the yaw rate during the holding control at the time of stopping as in the conventional case, for example, when the yaw rate is added by the rotation of the turntable to the vehicle stopped on the turntable of the multi-storey car park. There was a risk that the brake fluid pressure would drop against the driver's intention.

Therefore, an object of the present invention is to provide a vehicle brake fluid pressure control device capable of suppressing a decrease in brake fluid pressure contrary to the driver's intention during holding control when the vehicle is stopped.

In order to solve the above problems, the vehicle brake hydraulic pressure control device according to the present invention is a vehicle brake hydraulic pressure control device capable of executing holding control at the time of stopping to hold the brake hydraulic pressure when it is determined that the vehicle has stopped. The vehicle body speed at the time of brake input was equal to or higher than the specified speed value, the absolute value of wheel deceleration became equal to or higher than the specified deceleration value after brake input, and the vehicle was held during the stop control. When the first condition including that the lateral behavior amount of the vehicle is equal to or more than the specified value is satisfied, the holding control when the vehicle is stopped is canceled even if the operating member for operating the vehicle is not operated. It is characterized by.

According to this configuration, when the first condition is satisfied, the vehicle stop holding control is released without operating the operating member, so that the vehicle stop holding control can be quickly released. Also, when the vehicle is stopped on the turntable, it is usually rare to stop suddenly from a high speed. Therefore, by setting the speed regulation value and the deceleration regulation value to a value larger than the value that can be assumed at the time of entering the turntable, even if the vehicle has a lateral behavior amount on the turntable, the driver It is possible to suppress a decrease in brake fluid pressure contrary to the intention of.

Further, during the holding control when the vehicle is stopped, the first condition or the second condition including that the lateral behavior amount of the vehicle is equal to or more than the specified value and that the operation member is operated. When is satisfied, the holding control when the vehicle is stopped may be canceled.

According to this, even if the amount of behavior exceeds the specified value during the holding control when the vehicle is stopped, the holding control when the vehicle is stopped is not released unless the operation member is operated. Therefore, for example, on a turntable of a multi-storey car park. Even if the amount of lateral movement occurs in the vehicle, it is possible to suppress a decrease in brake fluid pressure contrary to the driver's intention. If the vehicle slides down while rotating during stop control on a low μ road surface such as an ice road, the vehicle will generate lateral behavior and the driver will try to rebuild the vehicle. By operating the member, the holding control when the vehicle is stopped is released and the brake fluid pressure is lowered, so that the vehicle can be rebuilt.

Further, the vehicle brake fluid pressure control device can execute wheel lock suppression control for suppressing the wheels from locking when the vehicle body speed is equal to or higher than the predetermined speed, and the specified speed value is the predetermined speed. It may be set to a value less than.

In the low speed range where the wheel lock suppression control is not executed, even if the wheel is locked due to an erroneous intervention of the holding control when the vehicle is stopped, if the first condition is satisfied, the holding control when the vehicle is stopped is released, so the vehicle must be rebuilt. It can be carried out.

Further, the vehicle body speed to be compared with the speed specified value may be updated every time the brake is input.

According to the present invention, it is possible to suppress a decrease in brake fluid pressure contrary to the driver's intention during holding control when the vehicle is stopped.

It is a block diagram of the vehicle provided with the brake fluid pressure control device for a vehicle which concerns on embodiment of this invention. It is a brake fluid pressure circuit diagram of the brake fluid pressure control device for a vehicle. It is a block block diagram of a control part. It is a flowchart which shows the determination process whether the 1st condition is satisfied. It is a flowchart which shows the determination process whether the 2nd condition is satisfied. It is a flowchart which shows the process for canceling the holding control at the time of a stop. 6 is a time chart (a) to (h) showing changes in various parameters when the holding control at the time of stopping is canceled under the first condition. 6 is a time chart (a) to (g) showing changes in various parameters when the holding control at the time of stopping is canceled under the second condition.

Next, an embodiment of the present invention will be described in detail with reference to the drawings as appropriate.
As shown in FIG. 1, the vehicle brake fluid pressure control device 100 is for appropriately controlling the braking force (brake fluid pressure) applied to each wheel W of the vehicle CR, and is for appropriately controlling the oil passage (hydraulic passage). It mainly includes a hydraulic unit 10 provided with various parts and a control unit 20 for appropriately controlling various parts in the hydraulic unit 10.

The control unit 20 includes a wheel speed sensor 91 that detects the wheel speed of the wheel W, a steering angle sensor 92 that detects the steering angle of the steering ST as an example of the operating member, and a lateral acceleration that detects the acceleration acting in the lateral direction of the vehicle CR. An acceleration sensor 93, a yaw rate sensor 94 that detects the turning angle speed (yaw rate) of the vehicle CR as a lateral behavior amount of the vehicle CR, and an acceleration sensor 95 that detects the acceleration in the front-rear direction of the vehicle CR are connected. The detection results of the sensors 91 to 95 are output to the control unit 20.

The control unit 20 includes, for example, a CPU, RAM, ROM, and an input / output circuit, and includes a wheel speed sensor 91, a steering angle sensor 92, a lateral acceleration sensor 93, a yaw rate sensor 94, an acceleration sensor 95, and a pressure sensor 8 (described later). Control is executed by performing each arithmetic processing based on the input from (see FIG. 2) and the programs and data stored in the ROM. Further, the wheel cylinder H is a liquid that converts the brake fluid pressure generated by the master cylinder MC and the vehicle brake hydraulic pressure control device 100 into the operating force of the wheel brakes FR, FL, RR, RL provided on each wheel W. It is a pressure device, and each is connected to the hydraulic unit 10 of the vehicle brake fluid pressure control device 100 via a pipe.

As shown in FIG. 2, the hydraulic unit 10 of the vehicle brake hydraulic pressure control device 100 includes a master cylinder MC, which is a hydraulic pressure source that generates brake hydraulic pressure according to the pedaling force applied to the brake pedal BP by the driver. It is arranged between the wheel brakes FR, FL, RR, and RL. The hydraulic pressure unit 10 is composed of a pump body 10a, which is a substrate having an oil passage through which brake fluid flows, an inlet valve 1 and an outlet valve 2 arranged in a plurality on the oil passage. The two output ports M1 and M2 of the master cylinder MC are connected to the inlet port 121 of the pump body 10a, and the outlet port 122 of the pump body 10a is connected to each wheel brake FR, FL, RR, RL. In the normal state, the pedaling force of the brake pedal BP is transmitted to each wheel brake FL, RR, RL, FR because the oil passage from the inlet port 121 to the outlet port 122 in the pump body 10a communicates with each other. It has become like.

Here, the oil passage starting from the output port M1 leads to the wheel brake FL on the left side of the front wheel and the wheel brake RR on the right side of the rear wheel, and the oil passage starting from the output port M2 is connected to the wheel brake FR on the right side of the front wheel and the left side of the rear wheel. It is familiar with the wheel brake RL. In the following, the oil passage starting from the output port M1 will be referred to as a "first system", and the oil passage starting from the output port M2 will be referred to as a "second system".

The hydraulic unit 10 is provided with two control valve means V corresponding to the wheel brakes FL and RR in the first system thereof, and similarly, the second system thereof corresponds to the wheel brakes RL and FR. Therefore, two control valve means V are provided. Further, the hydraulic pressure unit 10 is provided with a reservoir 3, a pump 4, an orifice 5a, a pressure regulating valve (regulator) R, and a suction valve 7 in each of the first system and the second system. Further, the hydraulic pressure unit 10 is provided with a common motor 9 for driving the pump 4 of the first system and the pump 4 of the second system. The motor 9 is a motor capable of controlling the rotation speed, and in the present embodiment, the rotation speed is controlled by duty control. Further, in the present embodiment, the pressure sensor 8 is provided only in the second system.

In the following, the oil passage from the output ports M1 and M2 of the master cylinder MC to each pressure regulating valve R will be referred to as "output hydraulic passage A1", and the oil from the pressure regulating valve R of the first system to the wheel brakes FL and RR will be referred to. The oil passages from the road and the pressure regulating valve R of the second system to the wheel brakes RL and FR are referred to as "wheel hydraulic passages B", respectively. Further, the oil passage from the output hydraulic passage A1 to the pump 4 is referred to as "suction hydraulic passage C", the oil passage from the pump 4 to the wheel hydraulic passage B is referred to as "discharge hydraulic passage D", and further. The oil passage from the wheel hydraulic passage B to the suction hydraulic passage C is referred to as an "open passage E".

The control valve means V is a valve that controls the flow of hydraulic pressure from the master cylinder MC or the pump 4 to the wheel brakes FL, RR, RL, FR (specifically, the wheel cylinder H), and controls the pressure of the wheel cylinder H. Can be increased, retained or decreased. Therefore, the control valve means V includes an inlet valve 1, an outlet valve 2, and a check valve 1a.

The inlet valve 1 is a normally open type proportional solenoid valve provided between each wheel brake FL, RR, RL, FR and the master cylinder MC, that is, in the wheel hydraulic path B. Therefore, the differential pressure between the upstream and downstream of the inlet valve 1 can be adjusted according to the value of the drive current flowing through the inlet valve 1.

The outlet valve 2 is a normally closed solenoid valve interposed between each wheel brake FL, RR, RL, FR and each reservoir 3, that is, between the wheel hydraulic path B and the open path E. The outlet valve 2 is normally closed, but when the wheel W is about to lock, it is opened by the control unit 20, so that the brake fluid pressure acting on each wheel brake FL, FR, RL, RR is applied. Let it escape to each reservoir 3.

The check valve 1a is connected in parallel to each inlet valve 1. This check valve 1a is a valve that allows only the inflow of brake fluid from each wheel brake FL, FR, RL, RR side to the master cylinder MC side, and is an inlet when the input from the brake pedal BP is released. Even when the valve 1 is closed, the inflow of brake fluid from each wheel brake FL, FR, RL, RR side to the master cylinder MC side is allowed.

The reservoir 3 is provided in the open path E, and has a function of temporarily storing the brake fluid that is released by opening each outlet valve 2. Further, a check valve 3a that allows only the flow of brake fluid from the reservoir 3 side to the pump 4 side is interposed between the reservoir 3 and the pump 4.

The pump 4 is interposed between the suction hydraulic path C leading to the output hydraulic path A1 and the discharge hydraulic path D leading to the wheel hydraulic path B, and sucks the brake fluid stored in the reservoir 3. It has a function of discharging to the discharge liquid pressure path D. As a result, the brake fluid absorbed by the reservoir 3 can be returned to the master cylinder MC, and the brake fluid pressure is generated regardless of whether or not the brake pedal BP is operated, and the wheel brakes FL, RR, RL, and FR are generated. Braking force can be generated.
The amount of brake fluid discharged by the pump 4 depends on the rotation speed (duty ratio) of the motor 9. That is, as the rotation speed (duty ratio) of the motor 9 increases, the amount of brake fluid discharged by the pump 4 also increases.

The orifice 5a attenuates the pulsation of the pressure of the brake fluid discharged from the pump 4.

The pressure regulating valve R normally allows the flow of brake fluid from the output hydraulic path A1 to the wheel hydraulic path B, and when the pressure on the wheel cylinder H side is increased by the brake hydraulic pressure generated by the pump 4, this is used. It has a function of adjusting the pressure on the wheel hydraulic path B and the wheel cylinder H side to a set value or less while shutting off the flow, and is configured to include a switching valve 6 and a check valve 6a.

The switching valve 6 is a normally open type proportional solenoid valve interposed between the output hydraulic path A1 leading to the master cylinder MC and the wheel hydraulic path B leading to each wheel brake FL, FR, RL, RR. .. Although details are not shown, the valve body of the switching valve 6 is urged in the valve closing direction by an electromagnetic force corresponding to the applied current, and the pressure in the wheel hydraulic path B is higher than the pressure in the output hydraulic path A1. When the value becomes higher than a predetermined value (this predetermined value depends on the applied current), the brake fluid escapes from the wheel hydraulic path B toward the output hydraulic path A1 so that the brake fluid escapes to the wheel hydraulic path B side. The pressure is adjusted to a predetermined pressure. That is, by arbitrarily changing the valve closing force according to the value of the drive current (indicated current value) input to the switching valve 6, the differential pressure between the upstream and downstream of the switching valve 6 is adjusted, and the wheel hydraulic path. The pressure of B can be adjusted below the set value.

The check valve 6a is connected in parallel to each switching valve 6. The check valve 6a is a one-way valve that allows the flow of brake fluid from the output hydraulic path A1 to the wheel hydraulic path B.

The suction valve 7 is a normally closed solenoid valve provided in the suction liquid pressure passage C, and switches between a state in which the suction liquid pressure passage C is opened and a state in which the suction liquid pressure passage C is closed. The suction valve 7 is opened under the control of the control unit 20 when, for example, the pump 4 pressurizes the hydraulic pressure in each of the wheel brakes FL, FR, RL, and RR.

The pressure sensor 8 detects the brake fluid pressure of the output hydraulic path A1, and the detection result is input to the control unit 20.

Next, the details of the control unit 20 will be described.
As shown in FIG. 3, the control unit 20 has a control valve means V, a pressure regulating valve R (switching valve 6), and a suction valve 7 in the hydraulic pressure unit 10 based on the signals input from the sensors 91 to 95, 8. The operation of each wheel brake FL, RR, RL, and FR is controlled by controlling the opening / closing operation and the operation of the motor 9. The control unit 20 includes a behavior determination unit 21, an operation determination unit 22, a hydraulic pressure control unit 23, a valve drive unit 24, a motor drive unit 25, and a storage unit 26.

The behavior determining means 21 has a function of determining whether or not the absolute value of the yaw rate Y output from the yaw rate sensor 94 (hereinafter, also simply referred to as “yaw rate Y”) is equal to or higher than the specified value Yth. Then, when the behavior determining means 21 determines that the yaw rate Y is equal to or higher than the specified value Yth, the behavior determining means 21 outputs a yaw rate generation signal indicating that to the hydraulic pressure controlling means 23.

The operation determining means 22 determines whether or not the steering ST has been operated by determining whether or not the steering angle θ (absolute value) output from the steering angle sensor 92 is equal to or greater than the steering angle specified value θth. Has the function of Then, when the operation determination means 22 determines that the operation has been performed, the operation determination means 22 outputs an operation signal indicating that to the hydraulic pressure control means 23.

The above-mentioned specified value Yth and the steering angle specified value θth may be appropriately set by experiments, simulations, or the like.

The hydraulic pressure control means 23 has a plurality of known sideslip suppression control modes, traction control modes, stop control, wheel lock suppression control, etc., based on the signals input from the sensors 91 to 95, 8. In order to control the brake fluid pressure in various control modes, it has a function of instructing the valve drive unit 24 and the motor drive unit 25 to operate various valves and drive the motor 9. Here, the stop control is a mode in which the brake fluid pressure is held when the vehicle is stopped. For example, the brake fluid pressure is held according to the depression force of the brake pedal BP when the vehicle is stopped, or when the vehicle is stopped. This mode refers to a mode in which the hydraulic pressure is maintained at a hydraulic pressure higher than the brake fluid pressure (hydraulic pressure boosted by the pump 4) according to the depression force of the brake pedal BP. The various control modes are stored in the storage unit 26.

The wheel lock suppression control is a control for suppressing the wheel W from locking when the wheel W tends to lock. The hydraulic pressure control means 23 determines whether the brake hydraulic pressure of each wheel W is in the reduced pressure state, the increased pressure state, or the holding state based on the wheel acceleration estimated from the wheel speed and the slip amount, and the valve. It has a function to output to the drive unit 140. The hydraulic pressure control means 23 determines that the wheel W tends to lock when the slip amount becomes larger than a predetermined threshold value and the wheel acceleration is 0 or less, and determines that the brake fluid pressure is reduced. .. Further, the hydraulic pressure control means 23 determines that the brake fluid pressure is kept in the holding state when the wheel acceleration is larger than 0, the slip amount is equal to or less than a predetermined threshold value, and the wheel acceleration is 0 or less. In some cases, it is decided to increase the brake fluid pressure.

Then, when the hydraulic pressure control means 23 determines that the wheel W tends to lock when the vehicle body speed is equal to or higher than the predetermined speed, the hydraulic pressure control means 23 executes (starts) the wheel lock suppression control. When the vehicle body speed is less than the predetermined speed, the hydraulic pressure control means 23 does not execute the wheel lock suppression control even if the above-mentioned conditions (conditions for determining the lock tendency of the wheels W) are satisfied.

Further, the hydraulic pressure control means 23 determines whether or not the vehicle CR is in a skid state (sideslip state) during the holding control when the vehicle is stopped, based on the signals output from the behavior determination means 21 and the operation determination means 22. It has a skid determination means 23a. Specifically, in the skid determination means 23a, the vehicle body speed Vb at the time of brake input was equal to or higher than the specified speed value Vth, and the absolute value Aw of wheel deceleration after the brake input was equal to or higher than the specified deceleration value Ath. When the first condition including that the yaw rate Y is equal to or higher than the specified value Yth is satisfied during the holding control when the vehicle is stopped, the first flag F1 indicating that the skid is generated by the satisfaction of the first condition is set to 1. Has the function of

Specifically, the skid determination means 23a stores the vehicle body speed Vb at the time of brake input in the storage unit 26 when the driver depresses the brake pedal BP, and is the maximum of the absolute value Aw of the wheel deceleration after the brake input. The value Awmax is stored in the storage unit 26. Then, the skid determination means 23a compares the vehicle body speed Vb and the maximum value Awmax of the wheel deceleration stored in the storage unit 26 with the respective threshold values (Vth, Ath) during the holding control when the vehicle is stopped, and the behavior determination means 21. By determining whether or not the yaw rate generation signal is output from, it is determined whether or not the first condition is satisfied.

The vehicle body speed Vb at the time of brake input, which is compared with the speed specified value Vth, is updated every time the brake is input. Further, the maximum value Awmax of the wheel deceleration after the brake input, which is compared with the deceleration specified value Ath, is reset to 0 each time the brake is input.

The vehicle body speed Vb may be, for example, the maximum wheel speed among the wheel speeds detected by each wheel speed sensor 91, or may be an average value of the wheel speeds of the four wheels. Further, the wheel deceleration can be calculated based on, for example, the wheel speed detected by the wheel speed sensor 91. Then, the skid determination means 23a stores the maximum value Awmax of the wheel deceleration of the four wheels in the storage unit 26 after the brake input, and in the determination of the first condition, any of the maximum values Awmax of the deceleration of each wheel. It may be determined whether or not the deceleration specified value Ath or more is reached.

Further, the speed specified value Vth and the deceleration specified value Ath are set to values larger than the maximum speed and the maximum deceleration that can be assumed when the vehicle CR enters the turntable. The specified speed value Vth can be set to a value less than a predetermined speed constituting one of the start conditions of the wheel lock suppression control described above, and can be set to a value of 10 km / h or more, for example.

Further, the skid determining means 23a satisfies the second condition including that the yaw rate Y is equal to or higher than the specified value Yth and that the steering ST is operated during the holding control when the vehicle is stopped. It has a function of setting the second flag F2, which indicates that a skid is generated by the satisfaction of the second condition, to 1.

The hydraulic pressure control means 23 has a function of determining whether or not the vehicle CR has stopped, and when it is determined that the vehicle CR has stopped, the function of starting the holding control when the vehicle is stopped. Here, the method for determining whether or not the vehicle CR has stopped may be any method. For example, the vehicle body speed calculated based on the signal from the wheel speed sensor 91 is a predetermined value V1 (FIG. 7 (FIG. 7). a) Refer to) A method of determining the stop of the vehicle CR by determining whether or not the following is the case.

Further, when the first flag F1 or the second flag F2 is 1 during the stop control, the hydraulic pressure control means 23 cancels the stop hold control regardless of the establishment of the known release condition. It is configured as follows. That is, the hydraulic pressure control means 23 is configured to release the holding control when the vehicle is stopped when the first condition or the second condition is satisfied during the holding control when the vehicle is stopped. In particular, the hydraulic pressure control means 23 cancels the stop hold control when the first condition is satisfied during the stop hold control, even if the stop hold control switch and the steering ST are not operated. It is configured in.

Here, the vehicle stop holding control switch is a switch for determining whether or not the vehicle stop holding control can be executed by the control unit 20. When the stop hold control switch is ON, the control unit 20 executes the stop hold control when the start condition of the stop hold control is satisfied. Further, when the stop hold control switch is OFF, the control unit 20 does not execute the stop hold control even if the start condition of the stop hold control is satisfied. Further, the control unit 20 cancels the stop hold control when the stop hold control switch is turned from ON to OFF during the stop hold control.

The known release condition includes, for example, that the start operation is performed when the shift position is "D" or "R".

The valve drive unit 24 is a part that controls the control valve means V, the pressure regulating valve R, and the suction valve 7 based on the instruction of the hydraulic pressure control means 23. Therefore, the valve drive unit 24 includes a control valve means drive unit 24a, a pressure regulating valve drive unit 24b, and a suction valve drive unit 24c.

The control valve means driving unit 24a controls the inlet valve 1 and the outlet valve 2 based on the instruction of increasing the pressure, holding the pressure, or reducing the pressure of the hydraulic pressure control means 23. Specifically, when the pressure of the wheel cylinder H should be increased, no current flows through both the inlet valve 1 and the outlet valve 2. Then, when the pressure of the wheel cylinder H should be reduced, a signal is sent to both the inlet valve 1 and the outlet valve 2, the inlet valve 1 is closed, and the outlet valve 2 is opened, so that the brake fluid of the wheel cylinder H is liquid. Is discharged from the outlet valve 2. Further, when the pressure of the wheel cylinder H is maintained, a signal is sent to the inlet valve 1 and no current is passed through the outlet valve 2, so that both the inlet valve 1 and the outlet valve 2 are closed.

The pressure regulating valve drive unit 24b normally does not pass a current through the pressure regulating valve R. Then, when a drive instruction is given from the hydraulic pressure control means 23, a current is supplied to the pressure regulating valve R by duty control according to this instruction. When a current is supplied to the pressure regulating valve R, a differential pressure corresponding to this current is formed between the master cylinder MC side of the pressure regulating valve R and the control valve means V (wheel cylinder H) side. As a result, the hydraulic pressure in the discharge hydraulic passage D between the pressure regulating valve R and the control valve means V is adjusted.

The suction valve drive unit 24c normally does not pass a current through the suction valve 7. Then, when instructed by the hydraulic pressure control means 23, a signal is output to the suction valve 7 according to this instruction. As a result, the suction valve 7 is opened so that the brake fluid is sucked from the master cylinder MC to the pump 4.

The motor driving unit 25 determines the rotation speed of the motor 9 based on the instruction of the hydraulic pressure control means 23 and drives the motor 9. That is, the motor drive unit 25 drives the motor 9 by the rotation speed control, and in the present embodiment, the rotation speed control is performed by the duty control.

Next, the operation of the control unit 20 will be described with reference to FIGS. 4 to 6.
The control unit 20 constantly repeatedly executes the skid determination process shown in FIGS. 4 and 5 and the process for releasing the holding control when the vehicle is stopped shown in FIG.

In the process shown in FIG. 4, the control unit 20 first determines whether or not braking is in progress (S1). Here, the determination as to whether or not the brake is in progress may be made based on the signal from the pressure sensor 8, or the determination based on the signal from the sensor that detects the operation amount of the brake pedal BP (not shown). You may.

If it is determined in step S1 that the brake is not being applied (No), the control unit 20 ends this control. If it is determined in step S1 that the brake is in progress (Yes), it is determined whether or not it is the timing when the brake is switched from OFF to ON (S2). The determination in step S2 may be determined based on the signal from the pressure sensor 8 or the like, as in the determination in step S1.

If it is determined in step S2 that it is the timing when the brake is switched to ON (Yes), the control unit 20 updates the vehicle body speed at that time as the vehicle body speed Vb at the time of brake input, and stores the vehicle body speed Vb in the storage unit 26. Remember (S3). After step S3, the control unit 20 resets the maximum wheel deceleration value Awmax to 0 (S4).

If it is determined in step S2 that the timing is not the timing at which the brake is switched to ON (No), the control unit 20 determines whether or not the absolute value Aw of the wheel deceleration exceeds the maximum value Awmax (S5). If it is determined in step S5 that Aw> Awmax (Yes), the control unit 20 updates the absolute value Aw of the wheel deceleration at that time as the maximum value Awmax (S6).

After step S4, S6, or when it is determined as No in step S5, the control unit 20 determines whether or not the vehicle is in the holding control when the vehicle is stopped (S7). If it is determined in step S7 that the vehicle is being held and controlled when the vehicle is stopped (Yes), the control unit 20 determines whether or not the yaw rate Y applied to the vehicle CR is equal to or greater than the specified value Yth (S8).

When it is determined in step S8 that Y ≧ Yth (Yes), the control unit 20 determines whether or not the vehicle body speed Vb at the time of brake input is equal to or higher than the speed specified value Vth (S9). When it is determined in step S9 that Vb ≧ Vth (Yes), the control unit 20 determines whether or not the maximum value Awmax of the wheel deceleration is equal to or greater than the deceleration specified value Ath (S10).

When it is determined in step S10 that Awmax ≧ Ath (Yes), the control unit 20 determines that the first condition is satisfied, sets the first flag F1 to 1 (S11), and performs this control. finish.

If the control unit 20 determines No in any of steps S7 to S10, the control unit 20 sets the first flag F1 to 0 (S12) and ends this control.

In the process shown in FIG. 5, the control unit 20 first determines whether or not the vehicle is in the holding control when the vehicle is stopped (S21). If it is determined in step S21 that the vehicle is being held and controlled when the vehicle is stopped (Yes), the control unit 20 determines whether or not the yaw rate Y applied to the vehicle CR is equal to or greater than the specified value Yth (S22).

When it is determined in step S22 that Y ≧ Yth (Yes), the control unit 20 determines whether or not the steering angle θ of the steering ST is equal to or greater than the steering angle specified value θth (S23).

If it is determined in step S23 that θ ≧ θth (Yes), the control unit 20 determines that the second condition is satisfied, sets the second flag F2 to 1 (S24), and performs this control. finish.

Further, if the control unit 20 determines No in any of steps S21 to S23, the second flag F2 is set to 0 (S25), and the control is terminated.

In the process shown in FIG. 6, the control unit 20 first determines whether or not the vehicle is being held and controlled when the vehicle is stopped (S31). If it is determined in step S31 that the vehicle is not in the holding control when the vehicle is stopped (No), the control unit 20 ends this control.

If it is determined in step S31 that the vehicle is being held and controlled when the vehicle is stopped (Yes), the control unit 20 determines whether or not the first flag F1 is 1. (S32). If it is determined in step S32 that F1 = 1 is not (No), the control unit 20 determines whether or not the second flag F2 is 1 (S33). If it is determined in step S33 that F2 = 1 is not (No), the control unit 20 determines whether or not other cancellation conditions are satisfied (S34).

When the control unit 20 determines that the first flag F1 is 1 in step S32 (Yes), when it determines that the second flag F2 is 1 in step S33 (Yes), or in step S34, another When it is determined that the cancellation condition is satisfied (Yes), the holding control at the time of stopping is canceled (S35), and this control is terminated. If it is determined in step S34 that the other release conditions are not satisfied, the control unit 20 terminates this control as it is without canceling the holding control when the vehicle is stopped (No). That is, in this case, the holding control when the vehicle is stopped is continued.

Next, control when the first condition or the second condition is satisfied during the holding control when the vehicle is stopped will be described with reference to FIGS. 7 and 8. The maximum values Awmax of the yaw rate, the steering angle, and the wheel deceleration in FIGS. 7 and 8 are shown as absolute values for convenience. Further, the vehicle body speed is shown as a value estimated from the wheel speed. First, with reference to FIG. 7, the control when the first condition is satisfied during the holding control when the vehicle is stopped will be described.

As shown in FIGS. 7A, 7B, and 7G, when the driver steps on the brake pedal BP while the vehicle CR is traveling at the vehicle body speed V2 (time t1), the inside of the wheel cylinder H As the brake fluid pressure gradually increases, the vehicle body speed gradually decreases. At this time, the control unit 20 updates the vehicle body speed Vb at the time of brake input to the vehicle body speed V2 and stores it in the storage unit 26.

When the vehicle body speed drops to a predetermined value V1 (time t2), it is determined that the vehicle CR is stopped, and for example, the vehicle stop holding control is executed at the brake fluid pressure P1 at that time (see FIG. 7 (h)). Since wheel deceleration occurs after the brake is input, the control unit 20 stores the maximum value Awmax of the wheel deceleration after the brake input in the storage unit 26 while updating it as needed.

Then, when the control unit 20 starts the holding control when the vehicle is stopped (time t2), the control unit 20 sets the maximum value Awmax of the vehicle body speed Vb at the time of brake input and the wheel deceleration after brake input stored in the storage unit 26 as threshold values (Vth). , Ath). In the example of FIG. 7, it is assumed that the vehicle body speed Vb is the speed specified value Vth or more, and the maximum wheel deceleration value Awmax is the deceleration specified value Ath or more.

If the vehicle body speed Vb at the time of brake input is high to some extent and a large wheel deceleration occurs after brake input, the vehicle CR actually rotates even though it is determined that the vehicle CR has stopped. While skidding, it may slip. It should be noted that such a phenomenon can occur even on a flat ground, for example, when the road surface is a low μ road surface such as an ice road.

In this case, as shown in FIG. 7 (c), the yaw rate Y of the specified value Yth or more is generated in the vehicle CR (time t3), so that at this time point as shown in FIGS. 7 (f) and 7 (h). The first condition is satisfied, the first flag F1 becomes 1, and the holding control when the vehicle is stopped is released. As a result, after time t3, the brake fluid pressure drops, the wheel lock is released, and the grip force of the wheel W is restored, so that the vehicle CR can be steered. Therefore, when the driver performs a steering operation in order to regain the posture of the vehicle CR (time t4), the posture of the vehicle CR can be repositioned by the driver's operation.

Next, with reference to FIG. 8, the control when the second condition is satisfied during the holding control when the vehicle is stopped will be described.

As shown in FIGS. 8A, 8B, and 8F, when the driver steps on the brake pedal BP while the vehicle CR is traveling at the vehicle body speed V2 (time t11), the inside of the wheel cylinder H As the brake fluid pressure gradually increases, the vehicle body speed gradually decreases. When the vehicle body speed drops to a predetermined value V1 (time t12), it is determined that the vehicle CR is stopped, and for example, the vehicle stop holding control is executed at the brake fluid pressure P1 at that time (see FIG. 8 (g)).

When the road surface is a low μ road surface such as an ice road, the vehicle CR continues to slide while rotating without actually stopping after the control unit 20 determines that the vehicle CR is stopped even on a flat ground. Sometimes.

When such a phenomenon occurs, as shown in FIGS. 8 (c) and 8 (g), a yaw rate Y occurs during the holding control when the vehicle is stopped (time t12 to t14), and the yaw rate Y exceeds the specified value Yth. Sometimes (time t13). In this case, the driver performs a steering operation in order to restore the posture of the vehicle CR. As a result of this steering operation, when the steering angle θ exceeds the steering angle specified value θth as shown in FIG. 8 (d) (time t14), as shown in FIGS. When the two conditions are satisfied, the second flag F2 becomes 1, and the holding control when the vehicle is stopped is released.

As a result, as shown in FIG. 8B, the brake fluid pressure held by the holding control when the vehicle is stopped decreases, so that the locked state of the wheel W is released as shown in FIG. 8A. (Time t15). Therefore, the grip force of the wheel W is restored and the vehicle CR can be steered, so that the posture of the vehicle CR can be restored by the operation of the driver.

Based on the above, the following effects can be obtained in the present embodiment.
When the first condition is satisfied, the vehicle stop holding control is released without operating the steering ST, so that the vehicle stop holding control can be quickly released. Further, when the vehicle CR is stopped on the turntable, it is usually rare to stop suddenly from a high speed. Therefore, by setting the speed specified value Vth and the deceleration specified value Ath to values larger than the values that can be assumed when entering the turntable, even if the yaw rate Y occurs in the vehicle CR on the turntable, the driver It is possible to suppress a decrease in brake fluid pressure contrary to the intention of.

Even if the yaw rate Y becomes the specified value Yth or more during the holding control when the vehicle is stopped, the holding control when the vehicle is stopped is not released unless the steering ST is operated. Even if the yaw rate Y is generated, it is possible to suppress a decrease in the brake fluid pressure contrary to the driver's intention. If the vehicle CR slides down while rotating during stop control on a low μ road surface such as an ice road, a yaw rate Y is generated in the vehicle CR and the driver tries to rebuild the vehicle in the steering ST. By operating, the holding control when the vehicle is stopped is released and the brake fluid pressure is lowered, so that the vehicle CR can be rebuilt.

When entering the turntable, it is common sense to drive the vehicle CR at a speed of less than 10 km / h, so by setting the specified speed value Vth to a value of 10 km / h or more, erroneous judgment on the turntable is suppressed. can do.

By setting the specified speed value Vth to a value less than the predetermined speed that constitutes one of the start conditions of the wheel lock suppression control, the holding control at the time of stopping intervenes erroneously in the low speed range where the wheel lock suppression control is not executed. Even when the wheel W is locked, if the first condition is satisfied, the holding control when the vehicle is stopped is released, so that the vehicle CR can be rebuilt.

The present invention is not limited to the above embodiment, and can be used in various forms as illustrated below.

In the above embodiment, the vehicle body speed Vb stored in the storage unit 26 and the absolute value Aw (maximum value Awmax) of the wheel deceleration are compared with the respective threshold values (Vth, Ath) during the holding control when the vehicle is stopped. Is not limited to this. For example, at the time of brake input, it may be determined whether the vehicle body speed Vb is equal to or higher than the specified speed value Vth, and if Vb ≧ Vth, a speed condition flag indicating that may be set. Similarly, after the brake is input, it is determined whether or not the absolute value Aw of the wheel deceleration becomes the deceleration specified value Ath or more, and if Aw ≧ Ath, a deceleration condition flag indicating that is set. good. Then, in this case, the conditions of the vehicle body speed and the wheel deceleration may be determined by determining whether or not each flag is set during the holding control when the vehicle is stopped.

In the above embodiment, the yaw rate is exemplified as the lateral behavior amount of the vehicle, but the present invention is not limited to this, and may be, for example, the lateral acceleration detected by the lateral acceleration sensor. However, when the yaw rate is adopted as the amount of behavior as in the above-described embodiment, the skid state (skid state) of the vehicle can be satisfactorily determined based on the yaw rate.

In the above embodiment, the vehicle stop holding control switch and the steering ST are exemplified as the operating member, but the present invention is not limited to this, and the operating member may be, for example, a brake or an accelerator.

In the above embodiment, depressurization control (decompression control when the holding control when the vehicle is stopped is released) is performed by controlling the pressure regulating valve R, but the present invention is not limited to this, and for example, a master is performed by driving a motor. When the brake hydraulic pressure is held and depressurized by an electric booster that moves the piston in the cylinder, the holding control when the vehicle is stopped or the release thereof may be performed by controlling the electric booster.

Each element described in the above-described embodiment and modification may be arbitrarily combined and carried out.

100 Vehicle brake fluid pressure control device Ath deceleration specified value Awmax maximum value CR vehicle ST steering Vb vehicle body speed Vth speed specified value Y yaw rate Yth specified value

Claims (4)

A vehicle brake fluid pressure control device that can execute holding control when the vehicle is stopped to hold the brake fluid pressure when it is determined that the vehicle has stopped.
The vehicle body speed at the time of brake input was equal to or higher than the specified speed value, the absolute value of wheel deceleration became equal to or higher than the specified deceleration value after brake input, and the vehicle was laterally held during the stop control. When the first condition including that the amount of behavior is equal to or more than a specified value is satisfied, the holding control at the time of stopping is canceled even if the operating member for operating the vehicle is not operated. Brake fluid pressure control device for vehicles. During the holding control when the vehicle is stopped, the first condition or the second condition including that the lateral behavior amount of the vehicle is equal to or more than the specified value and that the operation member is operated is satisfied. The vehicle brake fluid pressure control device according to claim 1, wherein when the vehicle is stopped, the holding control when the vehicle is stopped is released. It is possible to execute wheel lock suppression control that suppresses wheel lock when the vehicle body speed is equal to or higher than a predetermined speed.
The vehicle brake fluid pressure control device according to claim 1 or 2, wherein the specified speed value is set to a value less than the predetermined speed. The vehicle brake fluid pressure control device according to any one of claims 1 to 3, wherein the vehicle body speed to be compared with the speed specified value is updated each time a brake is input.

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