JP2014091482A - Brake liquid pressure controller for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a brake liquid pressure controller for vehicles which is capable of automatic pressurization control of a wheel brake and suppresses occurrence of different release feelings according to kept brake liquid pressures.SOLUTION: A brake liquid pressure controller for vehicles can perform an automatic pressurization control (S2) of a wheel brake according the distance to a counterpart object during running of a vehicle and includes a keeping control part keeping a control pressure for a wheel brake after the pressurization control and a pressure reduction control part reducing the control pressure after the keeping control by the keeping control part. The pressure reduction control part calculates a pressure reduction gradient value (G1) by dividing a control pressure P1 kept by the keeping control by the specified time T1 specified preliminarily (S6) and reducing the control pressure with a pressure reduction gradient G set as the calculated value of the pressure reduction gradient (S7 and S11).

Description

  The present invention relates to a vehicular brake hydraulic pressure control device that can automatically pressurize and control a wheel brake based on a distance from an opposing object while the vehicle is running.

  Conventionally, as a vehicle brake fluid pressure control device for preventing a collision, a configuration has been disclosed in which an object facing the vehicle is detected during traveling and the brake fluid pressure is automatically increased based on the distance from the object. (See Patent Document 1).

JP-A-6-72297

  By the way, after automatically pressurizing, for example, as shown in FIG. 8A, it is conceivable to reduce the held brake fluid pressure with a constant gradient GA. However, when such a control is applied to a vehicle brake hydraulic pressure control device that supports collision prevention, the holding hydraulic pressure is greatly different depending on the vehicle speed and the distance to the object. The brake fluid pressure held in can vary greatly.

  If the brake fluid pressure to be held is greatly different in this way, when the holding control is released and the brake fluid pressure is lowered with a constant gradient GA, the longer the holding fluid pressure is, the longer it takes to complete the pressure reduction. There is a problem that the release feeling becomes worse (a so-called drag feeling is generated). That is, there is a problem that the release feeling varies depending on the brake fluid pressure to be held.

  In order to solve this problem, as shown in FIG. 8 (b), in the initial stage of the pressure reduction control, the brake fluid pressure is lowered at a constant gradient GA, and when a certain pressure reduction time TA is reached. It is also conceivable to reduce the brake fluid pressure to 0 at once. However, even in this case, when the brake fluid pressure to be held is large, the release feeling is deteriorated by reducing the brake fluid pressure to 0 at a stroke (the vehicle starts to move suddenly). There arises a problem that the release feeling is different.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to suppress a release feeling from being different depending on a brake fluid pressure to be held in a vehicle brake fluid pressure control device capable of automatically pressurizing and controlling a wheel brake. And

  The present invention for solving the above-described problems is a vehicle brake hydraulic pressure control device capable of automatically pressurizing and controlling wheel brakes based on a distance from an opposing object while the vehicle is running. A holding control unit that holds the control pressure of the wheel brake after the pressure control, and a pressure reduction control unit that reduces the control pressure after the holding control by the holding control unit, and the pressure reduction control unit is held by the holding control The calculated control pressure is divided by a predetermined time defined in advance to calculate a reduced pressure gradient calculation value, and the control pressure is reduced with the reduced pressure gradient set to the reduced pressure gradient calculation value.

  According to this configuration, since the pressure is reduced at the pressure reduction gradient set to the pressure reduction gradient calculation value calculated based on the control pressure held in the holding control and the specified time, the control held after the pressurization control ends. It is possible to suppress the release feeling from being different due to the difference in pressure.

  Further, in the above-described configuration, a storage unit for storing a preset decompression gradient lower limit value is provided, and the decompression control unit is configured to calculate the decompression gradient when the calculated decompression gradient value is lower than the decompression gradient lower limit value. You may be comprised so that it may set to the said pressure reduction gradient lower limit.

  According to this, when the calculated pressure reduction gradient is very small, the actual hydraulic pressure can be reduced well without reducing the minute pressure reduction amount per unit time due to the performance of the machine. Although there is a possibility that it will disappear, the hydraulic pressure can be reduced well by changing the reduced pressure gradient calculated value to the reduced pressure gradient lower limit value when the reduced pressure gradient calculated value is lower than the reduced pressure gradient lower limit value.

  Further, in the above-described configuration, a determination unit that determines whether or not an accelerator operation has been performed is provided, and when the determination unit determines that the accelerator operation has been performed, the decompression control unit determines the decompression gradient. The accelerator operation decompression gradient and the decompression gradient calculated value may be set to the larger one.

  According to this, at the time of the accelerator operation, the pressure reduction can be completed quickly with a steep pressure reduction gradient, so that the drag feeling of the vehicle can be suppressed.

  In the above-described configuration, the pressure reduction control unit may be configured to perform pressure reduction by controlling a proportional solenoid valve capable of adjusting the brake fluid pressure.

  According to this, by controlling the proportional solenoid valve, the actual pressure reduction gradient of the brake fluid pressure can be made a smooth gradient corresponding to the control pressure.

  According to the present invention, in the vehicle brake hydraulic pressure control device capable of automatically controlling the pressurization of the wheel brake, it is possible to suppress the release feeling from being different depending on the brake hydraulic pressure to be held. .

It is a lineblock diagram of vehicles provided with a brake fluid pressure control device for vehicles concerning an embodiment of the present invention. It is a brake fluid pressure circuit diagram of a brake fluid pressure control device for vehicles. It is a block diagram which shows the structure of a control part. It is a flowchart which shows operation | movement of a control part. It is a time chart which shows the change of various parameters in the case of performing pressure reduction control after a comparatively big brake fluid pressure is held. It is a time chart which shows the change of various parameters when an accelerator opening sensor is turned ON during pressure reduction control. It is a time chart which shows the change of various parameters in the case of performing pressure reduction control after a comparatively small brake fluid pressure is held. A graph (a) showing a reference example in which pressure reduction control is performed with a constant gradient after holding control, and a graph (b) showing a reference example in which the brake fluid pressure is reduced to 0 at once when a certain pressure reduction time is reached.

Next, embodiments of the present invention will be described in detail with reference to the drawings as appropriate.
As shown in FIG. 1, the vehicle brake hydraulic pressure control device 100 is for appropriately controlling a braking force (brake hydraulic pressure) applied to each wheel W of the vehicle CR, and an oil passage (hydraulic pressure passage). And a hydraulic unit 10 provided with various components, and a control unit 20 for appropriately controlling various components in the hydraulic unit 10. An accelerator opening sensor 30, an inter-vehicle distance sensor 40, and a wheel speed sensor 50 are connected to the control unit 20 of the vehicle brake hydraulic pressure control device 100, and signals from the sensors 30 to 50 are input. It has become so.

The accelerator opening sensor 30 is a sensor that detects the accelerator opening according to the amount of depression of the accelerator pedal AP, and is provided in the vicinity of the accelerator pedal AP, for example.
The inter-vehicle distance sensor 40 is a sensor that detects a distance (hereinafter referred to as an inter-vehicle distance) with an object (such as a vehicle) that faces the front of the vehicle CR, and is provided on the front side of the vehicle body.

  The wheel speed sensor 50 is a sensor that detects the wheel speed of the wheel W, and is provided in each wheel W.

  The control unit 20 includes, for example, a CPU, a RAM, a ROM, and an input / output circuit. The control unit 20 includes inputs from the accelerator opening sensor 30, the inter-vehicle distance sensor 40, and the wheel speed sensor 50, and programs and data stored in the ROM. Control is performed by performing each arithmetic processing based on it.

  The wheel cylinder H is a fluid that converts the brake fluid pressure generated by the master cylinder MC and the vehicle brake fluid pressure control device 100 into the operating force of the wheel brakes FR, FL, RR, RL provided on each wheel W. Each of which is connected to the hydraulic unit 10 of the vehicle brake hydraulic pressure control device 100 via a pipe.

  As shown in FIG. 2, the hydraulic unit 10 of the vehicular brake hydraulic pressure control device 100 includes a master cylinder MC that is a hydraulic pressure source that generates a brake hydraulic pressure in accordance with the pedaling force applied to the brake pedal BP by the driver, It arrange | positions between wheel brakes FR, FL, RR, RL. The hydraulic unit 10 includes a pump body 10a that is a base body having an oil passage through which brake fluid flows, a plurality of inlet valves 1 and outlet valves 2 arranged on the oil passage. The two output ports M1, 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 normal times, the oil passage is communicated from the inlet port 121 to the outlet port 122 in the pump body 10a, so that the depression force of the brake pedal BP is transmitted to the wheel brakes FL, RR, RL, FR. It is like that.

  Here, the oil path 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 path starting from the output port M2 is set to the wheel brake FR on the right side of the front wheel and the left side of the rear wheel. To the wheel brake RL. Hereinafter, the oil passage starting from the output port M1 is referred to as “first system”, and the oil passage starting from the output port M2 is referred to as “second system”.

  The hydraulic unit 10 is provided with two control valve means V corresponding to each wheel brake FL, RR in the first system, and similarly corresponding to each wheel brake RL, FR in the second system. Two control valve means V are provided. The hydraulic 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. The hydraulic unit 10 is provided with a common motor 9 for driving the first system pump 4 and the second system pump 4. The motor 9 is a motor capable of controlling the rotational speed. In the present embodiment, the rotational speed is controlled by duty control.

  In the following, the oil passages from the output ports M1 and M2 of the master cylinder MC to the respective pressure regulating valves R are referred to as “output hydraulic pressure passages A1”, and the oil from the first system pressure regulating valve R to the wheel brakes FL and RR. The oil passages from the road and the second system pressure regulating valve R to the wheel brakes RL and FR are respectively referred to as “wheel hydraulic pressure passage B”. In addition, an oil path from the output hydraulic pressure path A1 to the pump 4 is referred to as “suction hydraulic pressure path C”, an oil path from the pump 4 to the wheel hydraulic pressure path B is referred to as “discharge hydraulic pressure path D”, and The oil passage from the wheel fluid pressure passage B to the suction fluid pressure passage C is referred to as “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). 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 proportional solenoid valve provided between each wheel brake FL, RR, RL, FR and the master cylinder MC, that is, in the wheel hydraulic pressure passage B. Therefore, the differential pressure 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 electromagnetic valve interposed between each wheel brake FL, RR, RL, FR and each reservoir 3, that is, between the wheel hydraulic pressure path B and the release path E. The outlet valve 2 is normally closed, but is released by the control unit 20 when the wheel W is about to be locked, so that the brake fluid pressure acting on each wheel brake FL, FR, RL, RR is reduced. Relief to each reservoir 3

  The check valve 1a is connected to each inlet valve 1 in parallel. This check valve 1a is a valve that only allows the brake fluid to flow from each wheel brake FL, FR, RL, RR side to the master cylinder MC side, and when the input from the brake pedal BP is released, Even when the valve 1 is closed, 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 release path E, and has a function of storing brake fluid pressure that is released when each outlet valve 2 is opened. Further, between the reservoir 3 and the pump 4, a check valve 3a that allows only the flow of brake fluid from the reservoir 3 side to the pump 4 side is interposed.

  The pump 4 is interposed between the suction hydraulic pressure path C leading to the output hydraulic pressure path A1 and the discharge hydraulic pressure path D leading to the wheel hydraulic pressure path B, and sucks the brake fluid stored in the reservoir 3 And has a function of discharging to the discharge hydraulic pressure path D. In other words, the pump 4 has a function of pressurizing the brake fluid and discharging it to the wheel fluid pressure path B on the side of the wheel brakes FL, RR, RL, RR from the pressure regulating valve R.

  Thus, 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, as will be described later, and the wheel brakes FL, RR, A braking force can be generated in RL and FR. 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 allows the brake fluid from the master cylinder MC to flow to the wheel brakes FL, RR, RL, FR at normal times, and increases the pressure on the wheel cylinder H side by the brake fluid pressure generated by the pump 4. Sometimes, this flow is cut off (the flow from the wheel brakes FL, RR, RL, FR side to the master cylinder MC side is suppressed) and the pressure on the wheel cylinder H side is adjusted to a set value or less. . Specifically, the pressure regulating valve R includes a switching valve 6 and a check valve 6a.

  The switching valve 6 is a normally open proportional solenoid valve interposed between the output hydraulic pressure path A1 leading to the master cylinder MC and the wheel hydraulic pressure path B leading to each wheel brake FL, FR, RL, RR. . Therefore, the differential pressure between the upstream and downstream of the switching valve 6 is adjusted by arbitrarily changing the valve closing force according to the value of the drive current (indicated current value) input to the switching valve 6, and the wheel hydraulic pressure path The pressure of B can be adjusted below the set value.

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

  The suction valve 7 is a normally closed electromagnetic valve provided in the suction fluid pressure passage C, and switches between a state in which the suction fluid pressure passage C is opened and a state in which the suction fluid pressure passage C is shut off. The suction valve 7 is opened by the control of the control unit 20 when the hydraulic pressure in each wheel brake FL, FR, RL, RR is increased by the pump 4, for example.

Next, details of the control unit 20 will be described.
As shown in FIG. 3 (a), the control unit 20 controls the pressure regulating valve R (switching valve) in the hydraulic unit 10 based on signals input from the accelerator opening sensor 30, the inter-vehicle distance sensor 40, and the wheel speed sensor 50. The operation of each wheel brake FL, RR, RL, FR is controlled by controlling the opening / closing operation of 6) and the intake valve 7 and the operation of the motor 9. Specifically, the control unit 20 performs well-known ABS control and the like, as well as pressurization control by the pump 4, for example, automatic addition for suppressing a collision with an object in front of the vehicle CR when the vehicle CR is traveling. Pressure control is executed.

  The control unit 20 includes a pressurization control unit 21, a holding control unit 22, a decompression control unit 23, a motor drive unit 24, a valve drive unit 25, and a storage unit 26.

  The pressurization control unit 21 has a function of automatically pressurizing and controlling the wheel brakes FL, RR, RL, FR based on the distance from the object facing the front surface of the vehicle CR while the vehicle CR is traveling. ing. Specifically, the pressurization control unit 21 calculates an inter-vehicle distance based on a signal output from the inter-vehicle distance sensor 40 and calculates a vehicle body speed based on each wheel speed output from each wheel speed sensor 50. To do.

  Then, the pressurization control unit 21 determines whether the inter-vehicle distance is equal to or less than the second threshold when the vehicle body speed is equal to or greater than the first threshold. Here, the first threshold value is a value that is appropriately determined through experiments, simulations, and the like, and is stored in the storage unit 26. Further, the second threshold value (target value of the inter-vehicle distance) changes according to the vehicle body speed as is well known. Specifically, for example, a map indicating the relationship between the vehicle body speed and the target value of the inter-vehicle distance is stored in the storage unit 26, and the target value of the inter-vehicle distance (second threshold) is calculated from the map and the vehicle body speed. Is done.

  When the inter-vehicle distance becomes equal to or less than the second threshold value, the pressurization control unit 21 automatically pressurizes the hydraulic pressure in the wheel brakes FR, FL, RR, RL (wheel cylinder H) by the pump 4. Therefore, the pressurization control unit 21 outputs a motor drive signal to the motor drive unit 24, outputs a signal for opening the intake valve 7 to the intake valve drive unit 25a, and instructs the pressure regulating valve drive unit 25b to correspond to the control pressure. Indicates the current value. Here, the “control pressure” is a target value of the hydraulic pressure in each wheel brake FR, FL, RR, RL, corresponds to the differential pressure upstream and downstream of the pressure regulating valve R, and flows to the pressure regulating valve R as a result. It corresponds to the indicated current value that is the target value of the current.

  The holding control unit 22 can execute holding control for holding the control pressures of the wheel brakes FR, FL, RR, RL after the pressure control described above. Specifically, the holding control unit 22 holds the brake fluid pressure at the control pressure set in the pressurization control when the vehicle body speed that is lowered by the pressurization control becomes a predetermined value or less. Therefore, the holding control unit 22 stops outputting the signal from the motor driving unit 24 to the motor 9 and instructs the pressure regulating valve driving unit 25b to indicate an instruction current value corresponding to the control pressure. Here, the predetermined value is a value that is appropriately determined by experiment, simulation, or the like, and is stored in the storage unit 26.

  The pressure reduction control unit 23 can execute pressure reduction control for reducing the control pressure after the holding control by the holding control unit 22, that is, when the pressure reducing conditions are met during the holding control. Here, in the present embodiment, it is determined that the decompression condition has been met when either of the condition that the predetermined time has elapsed since the start of the holding control and the condition that the accelerator operation has been performed is met. It will be done.

  Specifically, the depressurization control unit 23 calculates the depressurization gradient calculation value G1 (P1 / T1) by dividing the control pressure P1 held in the holding control by a predetermined time T1, and calculates the depressurization gradient calculation. The control pressure is reduced with the pressure reduction gradient G set to the value G1. Here, the specified time T <b> 1 is a value that is appropriately determined through experiments, simulations, and the like, and is stored in the storage unit 26.

  As a result, the pressure reduction control can be completed within a specified time T1 that is defined in advance regardless of the value of the control pressure that is retained after the pressurization control is completed. It is possible to suppress the feeling. In addition, the control pressure is reduced by the pressure reduction gradient set to the pressure reduction gradient calculation value G1, compared to the control that lowers the control pressure to 0 at once, so that it is possible to suppress the sudden start of the vehicle CR when the vehicle CR starts. It has become.

  The decompression control unit 23 includes a determination unit 23a that determines whether or not the decompression gradient G is set to a numerical value other than the above-described decompression gradient calculation value G1. The determination unit 23a determines whether or not the decompression gradient calculated value G1 is below a preset decompression gradient lower limit value Gmin, and if it is below, has a function of setting the decompression gradient G to the decompression gradient lower limit value Gmin. doing. The decompression gradient lower limit Gmin is a value that is appropriately determined through experiments, simulations, and the like, and is stored in the storage unit 26.

  Here, when the pressure reduction gradient calculation value G1 is extremely small, a minute pressure reduction amount per unit time cannot be reduced due to machine performance, and the actual hydraulic pressure cannot be reduced well. There is a fear. However, when the reduced pressure gradient calculated value G1 is lower than the reduced pressure gradient lower limit value Gmin as described above, it is possible to reduce the hydraulic pressure well by changing the reduced pressure gradient calculated value G1 to the reduced pressure gradient lower limit value Gmin. It has become.

  The determination unit 23a determines whether or not an accelerator operation has been performed based on a signal from the accelerator opening sensor 30, and if the accelerator operation has been performed, the decompression gradient G is calculated as a decompression gradient calculation. It has a function of setting the larger one of the value G1 and the accelerator operation decompression gradient G2 set in advance. According to this, since the pressure reduction can be completed quickly with a steep pressure reduction gradient at the time of the accelerator operation, it is possible to suppress the drag feeling of the vehicle.

  Here, in the present embodiment, the accelerator operation decompression gradient G2 is calculated based on the map shown in FIG. 3B and the accelerator opening. Specifically, this map is a map in which the accelerator opening is associated with the accelerator operation decompression gradient G2, and is set such that the accelerator operation decompression gradient G2 increases as the accelerator opening increases. This map is stored in the storage unit 26.

  When the control pressure is reduced by the pressure reduction gradient G set by the above-described method, the pressure reduction control unit 23 gradually increases the control pressure (indicated current value) output to the pressure regulating valve drive unit 25b according to the pressure reduction gradient G. To lower.

  The motor drive unit 24 determines the number of rotations of the motor 9 based on instructions from the pressurization control unit 21 and the holding control unit 22, and drives and stops the motor 9. That is, the motor drive unit 24 drives the motor 9 by rotational speed control, and performs rotational speed control by, for example, duty control.

  The valve drive unit 25 is a part that controls the pressure regulating valve R and the suction valve 7 based on instructions from the pressurization control unit 21, the holding control unit 22, and the pressure reduction control unit 23. Therefore, the valve drive unit 25 includes a suction valve drive unit 25a and a pressure regulating valve drive unit 25b.

  The suction valve drive unit 25a does not flow current to the suction valve 7 during normal operation. When there is an instruction from the pressurization control unit 21, a signal is output to the intake valve 7 in accordance with this instruction. As a result, the suction valve 7 is opened and the brake fluid is sucked into the pump 4 from the master cylinder MC.

  The pressure regulating valve drive unit 25b does not flow current to the pressure regulating valve R during normal operation. When an instruction current value is output from the pressurization control unit 21, the holding control unit 22, or the pressure reduction control unit 23, a drive current is supplied to the pressure regulating valve R according to the instruction current value. When a drive current is supplied to the pressure regulating valve R, a differential pressure corresponding to the drive current can be formed on the upstream and downstream sides of the pressure regulating valve R. When a pressure difference higher than this is generated, the pressure regulating valve R is opened. Maintain the differential pressure according to the drive current. As a result, the hydraulic pressure in the wheel brake is regulated.

Next, the operation of the control unit 20 will be described with reference to FIG.
The controller 20 repeatedly executes the flowchart shown in FIG. 4 when the vehicle CR is traveling.

  In this control, the control unit 20 first determines whether or not the conditions for automatic pressurization as described above are met (S1). In step S1, if the control part 20 judges that the conditions of automatic pressurization have been prepared (Yes), it starts pressurization control (S2).

  After step S2, the control unit 20 determines whether or not the vehicle body speed is equal to or lower than a predetermined value (S3). If the vehicle speed is equal to or lower than the predetermined value (Yes), the holding control is started (S4). After step S4, the control unit 20 determines whether or not the decompression conditions as described above are met (S5).

  In step S5, when the controller 20 determines that the decompression conditions are met (Yes), the controller 20 calculates the decompression gradient calculated value G1 by dividing the control pressure P1 retained in the retention control by the predefined time T1. (S6) The decompression gradient G is set to the decompression gradient calculated value G1 (S7). After step S7, the control unit 20 determines whether or not the accelerator operation is performed, specifically, whether or not the accelerator opening is equal to or greater than a predetermined value θ1 (see FIG. 5D) (S8).

  In step S8, when determining that the accelerator operation is not performed (Yes), the control unit 20 determines whether or not the decompression gradient calculation value G1 is smaller than the decompression gradient lower limit value Gmin (S9). In step S9, if the controller 20 determines that the decompression gradient calculated value G1 is smaller than the decompression gradient lower limit value Gmin (Yes), the decompression gradient G is set to the decompression gradient lower limit value Gmin (S10), and decompression control is performed. Execute (S11).

  In Step S9, when the controller 20 determines that the pressure reduction gradient calculation value G1 is equal to or greater than the pressure reduction gradient lower limit value Gmin (No), the pressure reduction gradient G is set to the pressure reduction gradient calculation value G1, and the pressure reduction control is performed. Is executed (S11). After step S11, the control unit 20 determines whether or not the pressure reduction is completed, for example, whether or not the control pressure has reached 0 (S12). The process returns to S8.

  In step S8, when it is determined that the accelerator operation has been performed (No), the control unit 20 determines whether or not the decompression gradient calculation value G1 is smaller than the accelerator operation decompression gradient G2 (S13). In step S13, when it is determined that the decompression gradient calculated value G1 is smaller than the accelerator operation decompression gradient G2 (Yes), the control unit 20 sets the decompression gradient G to the accelerator operation decompression gradient G2 (S14). ), Pressure reduction control is executed (S11).

  In step S13, when the decompression gradient calculated value G1 is equal to or greater than the accelerator operation decompression gradient G2 (No), the control unit 20 keeps the decompression gradient G set to the decompression gradient calculated value G1, Control is executed (S11). In step S12, when the control unit 20 determines that the pressure reduction has been completed (Yes), the control is terminated.

  Next, an example of setting the control pressure in the pressure reduction control of the control unit 20 will be described in detail with reference to FIGS. Here, in each figure, for the sake of convenience, the graph of the pump 4 shows ON when the pump 4 is being driven and OFF when it is stopped regardless of the output of the pump 4.

  As shown in FIG. 5A, when the vehicle CR travels at a vehicle body speed V2 that is equal to or higher than the first threshold, and the inter-vehicle distance becomes equal to or lower than the second threshold (time t1), FIG. As shown in c) and (e), the pressurization control is automatically executed by driving the pump 4 or the like so that the control pressure P1 corresponds to the vehicle body speed V2 or the like. As a result, as shown in FIGS. 5B and 5A, the brake fluid pressure increases and the vehicle body speed gradually decreases.

  When the vehicle body speed drops to the predetermined value V1 (time t2), the pump 4 is stopped as shown in FIG. 5 (e), and the same control pressure as during pressurization control is shown as shown in FIG. 5 (c). Holding control is executed at P1. Then, when the predetermined time T2 has elapsed from the start of the holding control (time t3), the pressure reduction control is executed.

  At this time, as shown by solid lines in FIGS. 5C and 5D, if the accelerator operation is not performed (the accelerator opening is less than θ1), the control pressure is set to the control pressure P1 during the holding control for a specified time T1. It is gradually lowered by the decompression gradient calculation value G1 calculated by dividing by. For this reason, the pressure reduction control can be completed within a predetermined time T1 that is defined in advance regardless of the value of the control pressure that is retained after the pressurization control is completed. Can be suppressed. Further, since the control pressure is reduced by the pressure reduction gradient set to the pressure reduction gradient calculation value G1 as compared with the control in which the control pressure is reduced to 0 at once, it is possible to suppress the sudden start of the vehicle CR when the vehicle CR starts. .

  Further, as indicated by broken lines in FIGS. 5C and 5D, the accelerator operation is performed at the start of the pressure reduction control (the accelerator opening is equal to or larger than θ1), and the accelerator is operated more than the pressure reduction gradient calculated value G1. When the operation decompression gradient G2 is large, the control pressure is gradually reduced by the larger accelerator operation decompression gradient G2. Therefore, since the pressure reduction can be completed quickly with a steep pressure reduction gradient (larger accelerator operation pressure reduction gradient G2) during the accelerator operation, the feeling of dragging of the vehicle can be suppressed.

  Further, as shown by broken lines in FIGS. 6C and 6D, when the accelerator operation is performed at a time t4 slightly after the start of the pressure reduction control (time t3), the control pressure is From T4, the pressure is gradually lowered at the larger accelerator operation pressure reduction gradient G2. As a result, even when the accelerator operation is performed during the decompression control, the decompression can be completed quickly with a steep decompression gradient (the larger accelerator operation decompression gradient G2). Can be suppressed.

  Also, as shown in FIG. 7A, for example, when the vehicle CR is traveling at a slow vehicle body speed V3 (first threshold value or more) and the inter-vehicle distance becomes equal to or less than the second threshold value ( At time t11), as shown in FIGS. 7C and 7D, the pressure control is automatically executed by driving the pump 4 or the like so that the control pressure P2 becomes smaller according to the vehicle body speed V3 or the like. Is done. Even in this case, the control pressure is gradually lowered by the pressure reduction gradient calculated value G1 calculated by dividing the control pressure P2 held at time t12 by the specified time T1 (time t13), The pressure-reducing control can be completed at a specified time T1 specified in advance, and the drag feeling at the start of the vehicle CR can be suppressed.

  Further, as indicated by a broken line in FIG. 7C, when the control pressure during the holding control is held at P3 smaller than P2, the pressure reduction gradient calculation value G1 (P3 / T1) indicated by the two-dot chain line in the figure. ) May be smaller than the decompression gradient lower limit Gmin. In this case, the control pressure is gradually lowered at the decompression gradient lower limit Gmin. For this reason, it is possible to suppress a problem (problem in which a minute pressure reduction amount per unit time cannot be reduced due to machine performance) caused by a very small pressure reduction gradient calculation value G1.

According to the above, the following effects can be obtained in the present embodiment.
In the vehicle brake hydraulic pressure control device 100 capable of automatically pressurizing and controlling the wheel brakes FR, FL, RR, RL, it is possible to suppress the release feeling from being different depending on the brake hydraulic pressure to be held. Can do.

  Moreover, since the control part 20 controls the switching valve 6 (pressure regulation valve R) which is a proportional solenoid valve, an actual brake fluid pressure can be made into the smooth gradient corresponding to a control pressure.

In addition, this invention is not limited to the said embodiment, It can utilize with various forms so that it may illustrate below.
In the embodiment, the determination as to whether or not the accelerator operation has been performed is performed based on the signal from the accelerator opening sensor 30. However, the present invention is not limited to this. For example, when the accelerator pedal is depressed by a predetermined amount. The determination may be made based on a signal from an ON / OFF sensor that is turned ON. Further, when the ON / OFF sensor is employed, the accelerator operation decompression gradient G2 may be a constant value that is appropriately determined by experiments, simulations, or the like. Even when the accelerator opening sensor 30 is employed, G2 is not calculated by the calculation based on the map described above, but G2 = 0 when the accelerator opening is equal to or less than a predetermined value, and the accelerator opening is predetermined. G2 may be calculated using a map in which G2 becomes a relatively large constant value when the value is exceeded.

  In the above embodiment, the pressure reduction control is performed by controlling the pressure regulating valve R, but the present invention is not limited to this. For example, an electric booster that moves the piston in the master cylinder by driving a motor. When maintaining and reducing the brake fluid pressure, the pressure reduction control according to the present invention may be performed by controlling the electric booster.

DESCRIPTION OF SYMBOLS 20 Control part 21 Pressurization control part 22 Holding | maintenance control part 23 Depressurization control part 23a Judgment part 100 Brake fluid pressure control device for vehicles CR Vehicle FL, FR, RL, RR Wheel brake G Decompression gradient G1 Decompression gradient calculation value P1 Control pressure R Regulating valve T1 Specified time

Claims (4)

A vehicle brake hydraulic pressure control device capable of automatically pressurizing and controlling a wheel brake based on a distance from an opposing object while the vehicle is running,
A holding control unit for holding the control pressure of the wheel brake after the pressurization control;
A pressure reduction control unit for reducing the control pressure after the holding control by the holding control unit,
The depressurization control unit calculates a depressurization gradient calculation value by dividing the control pressure held in the holding control by a preliminarily specified time, and calculates the control pressure with the depressurization gradient set to the depressurization gradient calculation value. A brake fluid pressure control device for a vehicle, wherein the pressure is reduced. A storage unit that stores a preset lower limit value of the decompression gradient,
2. The vehicle brake fluid according to claim 1, wherein the decompression control unit sets the decompression gradient to the decompression gradient lower limit value when the decompression gradient calculated value is lower than the decompression gradient lower limit value. Pressure control device. A determination unit that determines whether or not an accelerator operation has been performed;
When the determination unit determines that the accelerator operation has been performed, the decompression control unit sets the decompression gradient to a larger one of the preset accelerator operation decompression gradient and the decompression gradient calculation value. The vehicular brake hydraulic pressure control device according to claim 1, wherein the vehicular brake hydraulic pressure control device is provided.   4. The vehicle brake fluid pressure according to claim 1, wherein the pressure reduction control unit performs pressure reduction by controlling a proportional solenoid valve capable of adjusting a brake fluid pressure. 5. Control device.

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