JP2012046136A - Braking power control device and the braking power control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a braking power controlling device and a braking power controlling method capable of reducing a feeling of strangeness provided to a driver when the driver rapidly reduces an operating amount of a brake pedal.SOLUTION: The fluid pressure of a wheel cylinder which is connected to a master cylinder that is connected to a reserve tank through a first connection passage when the brake pedal is not operated by the driver through a second connection passage and applies braking power to the wheels is increased to a high fluid pressure exceeding the master cylinder pressure generated in the master cylinder according to the operating amount of the brake pedal. When the operating amount of the brake pedal is reduced to less than a preset operating amount threshold value from above such operating amount threshold value the pressure increased amount against the fluid pressure increased to the fluid pressure exceeding the master cylinder pressure is reduced and when the operating speed towards a return direction of the brake pedal exceeds a preset operating speed threshold value the reducing speed of the pressure increased amount becomes bigger than when the operating speed is less than the operating speed threshold value.

Description

  The present invention relates to a braking force control device and a braking force control method for performing driver brake assist control during braking of a vehicle.

2. Description of the Related Art Conventionally, there is a brake device including a wheel cylinder that applies a braking force to a wheel using a master cylinder pressure (pressure exerted by a brake fluid) generated in a master cylinder in accordance with an operation amount of a brake pedal by a driver. An example of such a brake device is described in Patent Document 1.
In the brake device described in Patent Document 1, a braking force equal to or higher than the braking force corresponding to the master cylinder pressure is applied to the wheel by the wheel cylinder pressure increased to a hydraulic pressure equal to or higher than the master cylinder pressure. Here, when the operation amount of the brake pedal becomes the operation amount at the time of non-operation (including the state where the operation amount of the brake pedal is substantially “0”), the master cylinder passes through the first series passage, Communicates with the reserve tank that stores brake fluid. The wheel cylinder communicates with the master cylinder through the second communication path.

JP 2000-142369 A

  However, in the brake device described in Patent Document 1, when the amount of operation of the brake pedal by the driver is rapidly reduced to the amount of operation when the driver is not operated, the brake fluid of the wheel cylinder is transferred to the master cylinder via the second communication path. May flow in rapidly. Furthermore, when the operation amount of the brake pedal becomes the operation amount at the time of non-operation, the brake fluid that rapidly flows into the master cylinder may rapidly flow into the reserve tank through the first series passage. .

  If the brake fluid that rapidly flows from the wheel cylinder into the master cylinder rapidly flows into the reserve tank, there is a possibility that the sound generated by the brake fluid flowing through the first series passage may give the driver a sense of incongruity. .

  The present invention has been made paying attention to the above-described problems, and is capable of reducing the uncomfortable feeling given to the driver when the driver rapidly decreases the operation amount of the brake pedal. It is an object of the present invention to provide a power control device and a braking force control method.

  In order to solve the above-described problem, the present invention provides a hydraulic pressure increased to a hydraulic pressure equal to or higher than the master cylinder pressure when an operation amount of the brake pedal decreases from a predetermined operation amount threshold value or more to less than the operation amount threshold value. Reduce pressure increase. In addition to this, when the operation speed in the return direction of the brake pedal is equal to or higher than a preset operation speed threshold, the hydraulic pressure increased to a pressure higher than the master cylinder pressure than when the operation speed is lower than the operation speed threshold. Increase the decrease rate of the pressure increase.

  According to the present invention, when the operation amount of the brake pedal by the driver is rapidly decreased, if the operation speed in the return direction of the brake pedal is high, the decrease speed for decreasing the degree of increase of the hydraulic pressure is increased. It will be. For this reason, it is possible to increase the flow rate of brake fluid flowing from the wheel cylinder to the master cylinder when the amount of brake pedal operation decreases rapidly, and to reduce the difference in hydraulic pressure between the wheel cylinder and the master cylinder. Become. This reduces the flow rate of the brake fluid flowing through the first series passage when the brake pedal operation amount becomes the non-operating operation amount, and suppresses the generation of sound by the brake fluid flowing through the first series passage. It is possible to reduce the uncomfortable feeling given to the driver.

1 is a diagram illustrating a schematic configuration of a vehicle to which a braking force control device according to a first embodiment of the present invention is applied. It is a figure which shows the hydraulic circuit of a hydraulic unit. It is a figure which shows the detailed structure of a brake controller. 4 is a flowchart illustrating processing performed by a brake controller in the first embodiment of the present invention. It is a flowchart which shows the process which a braking force control apparatus performs. It is a figure which shows the relationship between the master cylinder pressure and the hydraulic pressure of each wheel cylinder, and elapsed time in the process which complete | finishes brake assist control. It is a flowchart which shows the process which a brake controller performs in 2nd embodiment of this invention.

Embodiments of the present invention will be described below with reference to the drawings.
(First embodiment)
Hereinafter, a first embodiment of the present invention (hereinafter referred to as the present embodiment) will be described with reference to the drawings.
(Constitution)
FIG. 1 is a diagram illustrating a schematic configuration of a vehicle V to which the braking force control device of the present embodiment is applied.

As shown in FIG. 1, the vehicle V includes wheels W, a wheel cylinder 1, a brake pedal 2, a master cylinder 4, a hydraulic unit 6, and a brake controller 8.
The wheels W are a pair of left and right front wheels WF connected to the drive shaft of the engine 12 via the automatic transmission 10 and the like, and a pair of left and right rear wheels WR arranged offset from the front wheels WF in the vehicle longitudinal direction rearward. Consists of. In the following description, the pair of left and right front wheels WF may be referred to as a left front wheel WFL and a right front wheel WFR, and the pair of left and right rear wheels WR may be referred to as a left rear wheel WRL and a right rear wheel WRR.

  A wheel speed sensor 14 is provided on each of the left front wheel WFL, the right front wheel WFR, the left rear wheel WRL, and the right rear wheel WRR. Each wheel speed sensor 14 detects the rotation state (number of rotations, rotation speed) of the corresponding wheel W, and outputs an information signal including the detected rotation state to the brake controller 8. In the following description, the wheel speed sensor 14 provided on the left front wheel WFL may be referred to as a wheel speed sensor 14FL, and the wheel speed sensor 14 provided on the right front wheel WFR may be referred to as a wheel speed sensor 14FR. Similarly, in the following description, the wheel speed sensor 14 provided on the left rear wheel WRL is described as a wheel speed sensor 14RL, and the wheel speed sensor 14 provided on the right rear wheel WRR is described as a wheel speed sensor 14RR. There is.

The automatic transmission 10 transmits the driving force generated by the engine 12 to the front wheels WF at a gear ratio controlled by the transmission controller 16.
The transmission controller 16 controls the gear ratio of the automatic transmission 10 according to the amount of operation of the accelerator pedal 18 by the driver, a speed change operation (for example, operation of a shift lever), or the like. Further, the transmission controller 16 outputs an information signal including a gear position signal (range positions of the automatic transmission 10: “P”, “N”, “D”, “R”, etc.) to the brake controller 8.

The engine 12 is an internal combustion engine capable of generating a driving force, and is formed using a gasoline engine or a diesel engine, and is controlled by the engine controller 20 to rotate a driving shaft.
The engine controller 20 controls the engine 12 by controlling the torque, rotation speed, throttle opening, and the like of the engine 12 according to the amount of operation of the accelerator pedal 18 by the driver. Thereby, the engine controller 20 performs acceleration / deceleration control of the vehicle V reflecting the driver's intention. Further, the engine controller 20 outputs an information signal including the torque generated by the engine 12 and an information signal including the operation amount of the accelerator pedal 18 to the brake controller 8.

  The wheel cylinder 1 is provided on each of the left front wheel WFL, the right front wheel WFR, the left rear wheel WRL, and the right rear wheel WRR, and applies a braking force to the corresponding wheel W by hydraulic pressure. In the following description, the wheel cylinder 1 provided on the left front wheel WFL may be referred to as a wheel cylinder 1FL, and the wheel cylinder 1 provided on the right front wheel WFR may be referred to as a wheel cylinder 1FR. Similarly, in the following description, the wheel cylinder 1 provided on the left rear wheel WRL may be referred to as a wheel cylinder 1RL, and the wheel cylinder 1 provided on the right rear wheel WRR may be referred to as a wheel cylinder 1RR.

Each wheel cylinder 1 communicates with the master cylinder 4 via the hydraulic unit 6 and applies a braking force to the corresponding wheel W using the hydraulic pressure supplied from the hydraulic unit 6 (pressure exerted by the brake fluid). To do.
The brake pedal 2 is a pedal that is operated when the vehicle V is braked by the driver, and is connected to the master cylinder 4 via the brake booster 22.

  The brake booster 22 is formed using, for example, an electric booster, and boosts the amount of operation of the driver's brake pedal 2 at a preset ratio when the vehicle V is braked.

The brake pedal 2 is provided with a brake sensor 24.
The brake sensor 24 is formed using, for example, a brake stroke sensor capable of detecting the stroke of the brake pedal 2 and detects the stroke of the brake pedal 2 by the driver. Then, an information signal including the detected stroke of the brake pedal 2 is output to the brake controller 8.

The master cylinder 4 generates a hydraulic pressure (master cylinder pressure) according to the amount of operation of the brake pedal 2 by the driver, boosted by the brake booster 22, and sends the generated hydraulic pressure to the hydraulic unit 6. Supply.
The master cylinder 4 communicates with a reserve tank 28 that stores brake fluid via the first series passage 26 when the brake pedal 2 is not operated. That is, one end of the first series passage 26 always communicates with the reserve tank 28, and the other end of the first series passage 26 is closed by a piston (not shown) in the master cylinder 4 when the brake pedal 2 is not operated. It communicates with the master cylinder 4 at a position where no operation is performed.

  Here, when the brake pedal 2 is not operated, the amount of operation of the brake pedal 2 by the driver is “0”. In this embodiment, the amount of operation of the brake pedal 2 by the driver includes a state of approximately “0”. The state in which the amount of operation of the brake pedal 2 by the driver is substantially “0” is, for example, a state in which the amount of operation of the brake pedal 2 by the driver is within the play range set for the brake pedal 2. .

  The hydraulic unit 6 increases the hydraulic pressure supplied from the master cylinder 4 to a hydraulic pressure equal to or higher than the master cylinder pressure based on the command signal output from the brake controller 8, and the increased hydraulic pressure is supplied to each wheel cylinder. 1 is supplied. Here, the hydraulic unit 6 supplies each wheel cylinder 1 with a hydraulic pressure in which the degree of the pressure increase is controlled (increased, reduced or maintained) with respect to the increased hydraulic pressure. The specific configuration of the hydraulic unit 6 will be described later.

  The brake controller 8 receives information signals output from the automatic transmission controller 16, engine controller 20, wheel speed sensor 14, and brake sensor 24 described above. In addition, the brake controller 8 receives input of information signals output from a yaw rate / lateral acceleration sensor 30 and a steering angle sensor 32 described later. In this embodiment, as an example, the input / output of information signals between the controllers (16, 20) and the sensors (14, 24, 30, 32) and the brake controller 8 is performed by a CAN (Controller Area Network). The case where it carries out via will be described.

  Moreover, the brake controller 8 performs the process which performs brake assist control based on the various information signals input from each controller (16, 20) and each sensor (14, 24, 30, 32). Here, the brake assist control is control for generating a larger braking force with respect to the braking force corresponding to the braking operation of the driver. The braking force according to the driver's braking operation is a braking force applied to the wheel W according to the amount of operation of the brake pedal 2 by the driver.

Furthermore, the brake controller 8 sends command signals related to hydraulic pressure control to the hydraulic unit 6 based on various information signals input from the controllers (16, 20) and the sensors (14, 24, 30, 32). Output.
The detailed configuration of the brake controller 8 will be described later.
The yaw rate / lateral acceleration sensor 30 detects the yaw rate and lateral acceleration of the vehicle V, and outputs an information signal including the detected yaw rate and lateral acceleration to the brake controller 8.

  The steering angle sensor 32 is attached to, for example, a steering column, detects the steering angle of the steering wheel 34 by the driver, and outputs an information signal including the detected steering angle to the brake controller 8.

(Specific configuration of the hydraulic unit 6)
Hereinafter, a specific configuration of the hydraulic unit 6 will be described with reference to FIG. 1 and FIG. 2.
FIG. 2 is a diagram showing a hydraulic circuit of the hydraulic unit 6.
As shown in FIG. 2, the hydraulic unit 6 has two systems, a P (primary) system and an S (secondary) system, as a hydraulic system through which the brake fluid moves. It has a structure.

(Schematic configuration of P system and S system)
Hereinafter, schematic configurations of the P system and the S system will be described.
A master cylinder 4 is connected to one end of the P system, and a wheel cylinder 1FL and a wheel cylinder 1RR are connected to the other end of the P system. The P system is provided with a P system pump 36P. The detailed configuration of the P system will be described later.

  A master cylinder 4 is connected to one end of the S system, and a wheel cylinder 1FR and a wheel cylinder 1RL are connected to the other end of the S system. The S system is provided with an S system side pump 36S. The detailed configuration of the S system will be described later.

  Here, the P system side pump 36 </ b> P and the S system side pump 36 </ b> S are driven by one brake assist motor 38. The brake assist motor 38 is driven by a command signal output from the brake controller 8.

(Detailed configuration of P system)
Hereinafter, a detailed configuration of the P system will be described.
The master cylinder 4 and the suction side of the P system side pump 36P are connected by a P system side first pipeline 40P, and a P system side gate-in valve 42P is provided on the P system side first pipeline 40P. Yes. The P system side gate-in valve 42P is a normally closed solenoid valve, and operates (opens and closes) in response to a command signal output from the brake controller 8.

  Further, on the P system side first pipeline 40P, a P system side first check valve 44P is provided between the P system side gate-in valve 42P and the P system side pump 36P. The P system side first check valve 44P is a valve that allows the flow of brake fluid in the direction from the P system side gate-in valve 42P to the P system side pump 36P. Moreover, it is a valve which prohibits the flow of the brake fluid in the direction from the P system side pump 36P toward the P system side gate-in valve 42P.

The discharge side of the P system side pump 36P and the wheel cylinder 1FL and the wheel cylinder 1RR are connected by a P system side second pipeline 46P.
The P system side second conduit 46P branches into a P system side first branch path 48FL connected to the wheel cylinder 1FL and a P system side first branch path 48RR connected to the wheel cylinder 1RR.

  A P system side solenoid-in valve 50FL is provided in the P system side first branch path 48FL. The P-system side solenoid-in valve 50FL is a normally open solenoid valve corresponding to the wheel cylinder 1FL, and operates (opens / closes) in response to a command signal output from the brake controller 8.

  The P system side first branch path 48FL is provided with a P system side first bypass pipe 52FL that bypasses the P system side solenoid in valve 50FL, and the P system side first bypass pipe 52FL includes P A system-side first detour check valve 54FL is provided. The P system side first bypass check valve 54FL allows the flow of brake fluid in the direction from the wheel cylinder 1FL toward the P system side pump 36P, and the brake fluid in the direction from the P system side pump 36P toward the wheel cylinder 1FL. This valve prohibits flow.

  A P system side solenoid-in valve 50RR is provided in the P system side first branch path 48RR. The P-system side solenoid-in valve 50RR is a normally-open electromagnetic valve corresponding to the wheel cylinder 1RR, and operates (opens and closes) in response to a command signal output from the brake controller 8.

  The P system side first branch path 48RR is provided with a P system side first bypass pipe 52RR that bypasses the P system side solenoid in valve 50RR, and the P system side first bypass pipe 52RR includes P A system-side first detour check valve 54RR is provided. The P system side first bypass check valve 54RR allows the flow of brake fluid in the direction from the wheel cylinder 1RR toward the P system side pump 36P, and the brake fluid in the direction from the P system side pump 36P toward the wheel cylinder 1RR. This valve prohibits flow.

  Further, on the P system side second conduit 46P, between the discharge side of the P system side pump 36P and the portion branched to the P system side first branch path 48FL and the P system side first branch path 48RR, P A system side second check valve 56P is provided. The P system side second check valve 56P is a valve that allows the flow of brake fluid in the direction from the P system side pump 36P toward the P system side solenoid in valve 50FL and the P system side solenoid in valve 50RR. The P system side second check valve 56P is a valve that prohibits the flow of brake fluid from the P system side solenoid in valve 50FL and the P system side solenoid in valve 50RR toward the P system side pump 36P.

  The master cylinder 4 and the P system side second pipe 46P are connected by a P system side third pipe 58P. The P system side second pipe 46P and the P system side third pipe 58P merge between the P system side pump 36P, the P system side solenoid in valve 50FL, and the P system side solenoid in valve 50RR.

  A P-system side gate-out valve 60P is provided on the P-system side third pipeline 58P. The P-system side gate-out valve 60P is a normally open solenoid valve, and operates (opens and closes) in response to a command signal output from the brake controller 8.

  The P system side third pipeline 58P is provided with a P system side second bypass pipeline 62P that bypasses the P system side gate-out valve 60P, and the P system side second bypass pipeline 62P includes P A system side second bypass check valve 64P is provided.

  The P system side second bypass check valve 64P is a valve that allows the flow of brake fluid in a direction from the master cylinder 4 toward the P system side solenoid in valve 50FL and the P system side solenoid in valve 50RR. The P system side second bypass check valve 64P is a valve that prohibits the flow of brake fluid in the direction from the P system side solenoid in valve 50FL and the P system side solenoid in valve 50RR toward the master cylinder 4.

On the P system side first pipeline 40P, a P system side fourth pipeline 66P is branched between the P system side gate-in valve 42P and the P system side first check valve 44P.
One end of the P system side fourth pipeline 66P is connected to the P system side first pipeline 40P, and the other end of the P system side fourth pipeline 66P is provided with a P system side reservoir 68P. The P-system side reservoir 68P is a tank that stores and discharges the brake fluid that moves in the pipeline of the P system.

  A P system side third check valve 70P is provided between the P system side reservoir 68P and the P system side pump 36P. The P system side third check valve 70P allows the flow of brake fluid in the direction from the P system side reservoir 68P to the P system side pump 36P, and the brake fluid in the direction from the P system side pump 36P to the P system side reservoir 68P. It is a valve that prohibits the flow of air.

  The wheel cylinder 1FL and the wheel cylinder 1RR are connected to the P system side fourth pipeline 66P by the P system side fifth pipeline 72P. The P system side fourth pipeline 66P and the P system side fifth pipeline 72P merge between the P system side third check valve 70P and the P system side reservoir 68P.

  The P system side fifth pipeline 72P branches off into a P system side second branch path 74FL communicating with the wheel cylinder 1FL and a P system side second branch path 74RR communicating with the wheel cylinder 1RR.

The P system side second branch path 74FL is provided with a P system side solenoid out valve 76FL. The P system side solenoid out valve 76FL is a normally closed electromagnetic valve corresponding to the wheel cylinder 1FL, and operates (opens and closes) in response to a command signal output from the brake controller 8.
The P system side second branch path 74RR is provided with a P system side solenoid out valve 76RR. The P system side solenoid out valve 76RR is a normally closed electromagnetic valve corresponding to the wheel cylinder 1RR, and operates (opens and closes) in response to a command signal output from the brake controller 8.

A P system side master cylinder pressure sensor 78P is provided in an oil path (pipe) between the master cylinder 4 and the P system side gate in valve 42P and the P system side gate out valve 60P.
The P system side master cylinder pressure sensor 78P detects the hydraulic pressure of the brake fluid supplied from the master cylinder 4 to the P system, and outputs an information signal including the detected hydraulic pressure to the brake controller 8.

(Detailed configuration of S system)
Hereinafter, a detailed configuration of the S system will be described.
The master cylinder 4 and the suction side of the S system side pump 36S are connected by an S system side first pipeline 40S, and an S system side gate-in valve 42S is provided on the S system side first pipeline 40S. Yes. The S system side gate-in valve 42S is a normally closed solenoid valve, and operates (opens and closes) in response to a command signal output from the brake controller 8.

  Further, on the S system side first pipeline 40S, an S system side first check valve 44S is provided between the S system side gate-in valve 42S and the S system side pump 36S. The S system side first check valve 44S is a valve that allows the flow of brake fluid in the direction from the S system side gate-in valve 42S to the S system side pump 36S. Moreover, it is a valve which prohibits the flow of the brake fluid in the direction from the S system side pump 36S toward the S system side gate-in valve 42S.

The discharge side of the S system side pump 36S and the wheel cylinder 1FR and the wheel cylinder 1RL are connected by the S system side second pipeline 46S.
The S system side second pipeline 46S branches into an S system side first branch path 48FR connected to the wheel cylinder 1FR and an S system side first branch path 48RL connected to the wheel cylinder 1RL.

The S system side solenoid-in valve 50FR is provided in the S system side first branch path 48FR. The S system side solenoid-in valve 50FR is a normally open solenoid valve corresponding to the wheel cylinder 1FR, and operates (opens and closes) in response to a command signal output from the brake controller 8.
Further, the S system side first branch path 48FR is provided with an S system side first bypass pipe 52FR that bypasses the S system side solenoid-in valve 50FR. The S system side first detour conduit 52FR is provided with an S system side first detour check valve 54FR.

  The S system side first bypass check valve 54FR is a valve that allows the flow of brake fluid in the direction from the wheel cylinder 1FR toward the S system side pump 36S. The S system side first detour check valve 54FR is a valve that prohibits the flow of brake fluid in the direction from the S system side pump 36S toward the wheel cylinder 1FR.

  The S system side solenoid-in valve 50RL is provided in the S system side first branch path 48RL. The S system side solenoid-in valve 50RL is a normally open solenoid valve corresponding to the wheel cylinder 1RL, and operates (opens and closes) in response to a command signal output from the brake controller 8.

  In addition, the S system side first branch path 48RL is provided with an S system side first bypass pipe 52RL that bypasses the S system side solenoid-in valve 50RL. The S system side first bypass check valve 54RL is provided in the S system side first bypass pipe 52RL.

  The S system side first detour check valve 54RL is a valve that allows the flow of brake fluid in the direction from the wheel cylinder 1RL toward the S system side pump 36S. The S system side first detour check valve 54RL is a valve that prohibits the flow of brake fluid in the direction from the S system side pump 36S toward the wheel cylinder 1RL.

  Further, on the S system side second pipeline 46S, between the discharge side of the S system side pump 36S and the portion branched into the S system side first branch 48FR and the S system side first branch 48RL, the S A system-side second check valve 56S is provided. The S system side second check valve 56S is a valve that allows the flow of brake fluid in the direction from the S system side pump 36S toward the S system side solenoid in valve 50FR and the S system side solenoid in valve 50RL. The S system side second check valve 56S is a valve that prohibits the flow of brake fluid in the direction from the S system side solenoid in valve 50FR and the S system side solenoid in valve 50RL toward the S system side pump 36S.

  Further, the master cylinder 4 and the S system side second pipeline 46S are connected by an S system side third pipeline 58S. The S system side second pipeline 46S and the S system side third pipeline 58S merge between the S system side pump 36S, the S system side solenoid in valve 50FR, and the S system side solenoid in valve 50RL.

  On the S system side third pipeline 58S, an S system side gate-out valve 60S is provided. The S system side gate-out valve 60S is a normally-open electromagnetic valve, and operates (opens and closes) in response to a command signal output from the brake controller 8.

  The S system side third pipeline 58S is provided with an S system side second bypass pipeline 62S that bypasses the S system side gate-out valve 60S, and the S system side second bypass pipeline 62S includes an S A system-side second bypass check valve 64S is provided.

  The S system side second bypass check valve 64S is a valve that allows the flow of brake fluid in a direction from the master cylinder 4 toward the S system side solenoid in valve 50FR and the S system side solenoid in valve 50RL. The S system side second bypass check valve 64S is a valve that prohibits the flow of brake fluid in the direction from the S system side solenoid in valve 50FR and the S system side solenoid in valve 50RL toward the master cylinder 4.

Further, on the S system side first pipeline 40S, the S system side fourth pipeline 66S is branched between the S system side gate-in valve 42S and the S system side first check valve 44S.
One end of the S system side fourth pipeline 66S is connected to the S system side first pipeline 40S, and the other end of the S system side fourth pipeline 66S is provided with an S system side reservoir 68S. The S system-side reservoir 68S is a tank that stores and discharges brake fluid that moves in the P system pipe line.

  An S system side third check valve 70S is provided between the S system side reservoir 68S and the S system side pump 36S. The S system side third check valve 70S is a valve that allows the flow of brake fluid in the direction from the S system side reservoir 68S to the S system side pump 36S. The S system side third check valve 70S is a valve that prohibits the flow of brake fluid in the direction from the S system side pump 36S toward the S system side reservoir 68S.

  The wheel cylinder 1FR, the wheel cylinder 1RL, and the S system side fourth pipeline 66S are connected by the S system side fifth pipeline 72S. The S system side fourth pipeline 66S and the S system side fifth pipeline 72S merge between the S system side third check valve 70S and the S system side reservoir 68S.

  The S system side fifth pipeline 72S branches into an S system side second branch path 74FR that communicates with the wheel cylinder 1FR and an S system side second branch path 74RL that communicates with the wheel cylinder 1RL.

The S system side second branch path 74FR is provided with an S system side solenoid out valve 76FR. The S system side solenoid out valve 76FR is a normally closed electromagnetic valve corresponding to the wheel cylinder 1FR, and operates (opens and closes) in response to a command signal output from the brake controller 8.
The S system side second branch path 74RL is provided with an S system side solenoid out valve 76RL. The S system side solenoid out valve 76RL is a normally closed electromagnetic valve corresponding to the wheel cylinder 1RL, and operates (opens and closes) in response to a command signal output from the brake controller 8.

  An S system side master cylinder pressure sensor 78S is provided in an oil passage (pipe) between the master cylinder 4 and the S system side gate-in valve 42S and the S system side gate out valve 60S.

The S system side master cylinder pressure sensor 78S detects the hydraulic pressure of the brake fluid supplied from the master cylinder 4 to the S system, and outputs an information signal including the detected hydraulic pressure to the brake controller 8.
(Detailed configuration of brake controller)
Hereinafter, a detailed configuration of the brake controller 8 will be described with reference to FIGS. 1 and 2 and FIG. 3.

FIG. 3 is a diagram showing a detailed configuration of the brake controller 8.
As shown in FIG. 3, the brake controller 8 includes a brake operation amount detection unit 80, a brake operation speed detection unit 82, a brake assist operation determination unit 84, and a control start determination unit 86. In addition, the brake controller 8 includes a control end determination unit 88, a pressure reduction amount setting unit 90, a braking force control amount calculation unit 92, and a brake assist control unit 94.

  The brake operation amount detector 80 is a hydraulic pressure supplied from the master cylinder 4 to the P system and the S system based on the input of information signals output from the P system side master cylinder pressure sensor 78P and the S system side master cylinder pressure sensor 78S. Is detected.

  Here, the hydraulic pressure (master cylinder pressure) supplied from the master cylinder 4 to the P system and the S system is correlated with the amount of operation of the brake pedal 2 by the driver. That is, when the amount of operation of the brake pedal 2 by the driver increases, the master cylinder pressure also increases.

  Therefore, the master cylinder pressure is a pressure corresponding to the amount of operation of the brake pedal 2 by the driver. Therefore, the brake operation amount detection unit 80 detects the operation amount of the brake pedal 2 by the driver by detecting the master cylinder pressure.

  The brake operation speed detection unit 82 detects the master cylinder pressure in the same manner as the brake operation amount detection unit 80, and further calculates the amount of change per unit time of the detected master cylinder pressure. Accordingly, the brake operation speed detection unit 82 detects the operation speed of the brake pedal 2 by the driver.

  Here, in this embodiment, the operation speed of the brake pedal 2 by the driver detected by the brake operation speed detection unit 82 is returned in the return direction (the direction in which the depressed brake pedal 2 is returned to the non-operating position). The operation speed.

  The brake assist operation determination unit 84 determines whether or not the above-described brake assist control is performed by determining whether or not a brake assist operation flag is established. Here, the brake assist operation flag is a flag that is satisfied under the condition that the brake assist control is performed.

When the brake assist operation determining unit 84 determines that the brake assist control is not performed, the control start determining unit 86 determines that the operation amount of the brake pedal 2 by the driver detected by the brake operation amount detecting unit 80 is in advance. It is determined whether or not the set control start threshold value is exceeded.
Here, the control start threshold is an amount of operation (depression amount) of the brake pedal 2 by the driver that can be determined that the driver is willing to decelerate the traveling vehicle V. This is the calculated value.

The control end determination unit 88 determines whether or not the operation amount of the brake pedal 2 by the driver detected by the brake operation amount detection unit 80 is less than a preset operation amount threshold value.
Here, the operation amount threshold is an operation amount of the brake pedal 2 by the driver, which is considered that the driver intends to stop the operation of the brake pedal 2, and is a value used when the brake assist control being executed is terminated. It is.

  Specifically, the operation amount threshold value is a hydraulic pressure corresponding to the operation amount of the brake pedal 2. This is an operation amount that allows the driver to determine that he / she is willing to return the position of the brake pedal 2 to the non-operating position by weakening the depression force applied to the brake pedal 2 that has been depressed. It is a value obtained in advance by an experiment or the like according to the configuration, the performance of the brake device, or the like.

  The decompression amount setting unit 90 sets the decompression amount used when ending the brake assist control being performed according to the operation speed of the brake pedal 2 in the return direction. In this setting, when the brake assist operation determination unit 84 determines that the brake assist control is performed, the operation amount of the brake pedal 2 by the driver detected by the brake operation amount detection unit 80 is set in advance. This is performed when the operation amount threshold is less than the threshold value.

  Here, the amount of pressure reduction used when ending the brake assist control being executed is the brake assist control being executed in order to decrease the control amount of the hydraulic pressure in the brake assist control being executed toward “0”. Is a value to be subtracted from the control amount of the hydraulic pressure at.

  Specifically, the fluid pressure increased when the fluid pressure supplied to each wheel cylinder 1 in the previous brake assist control is decreased per unit time toward “0” at a preset reduction speed. Is the degree of decrease in the amount of pressure increase. Here, the degree of decrease in the pressure increase amount with respect to the increased hydraulic pressure is, for example, a decrease in which the pressure increase amount is decreased (reduced) with respect to the hydraulic pressure supplied to each wheel cylinder 1 in the previous brake assist control. Amount (pressure reduction amount).

Note that the hydraulic pressure control amount in the brake assist control being performed is a value calculated by the braking force control amount calculation unit 92, and will be described later.
Specifically, when setting the amount of pressure reduction used when ending the brake assist control being performed, the pressure reduction amount setting unit 90 first returns the brake pedal 2 return direction detected by the brake operation speed detection unit 82. Refer to the operation speed to. Then, it is determined whether or not the driver's operation speed in the return direction of the brake pedal 2 detected by the brake operation speed detector 82 is equal to or higher than a preset operation speed threshold.

  Here, the operation speed threshold is an operation speed in the return direction of the brake pedal 2 by the driver such that the hydraulic pressure remains in each wheel cylinder 1 in a state in which the driver completely returns the brake pedal 2. This is a speed at which it can be determined whether or not the operation of the brake pedal 2 by the driver is a rapid return operation (an operation to weaken the pedal force applied to the depressed brake pedal 2 and return the position of the brake pedal 2). It is a value obtained in advance by experiments or the like.

The state in which the driver has completely returned the brake pedal 2 is a state in which the driver has operated the brake pedal 2 in the return direction to return the position of the brake pedal 2 to the non-operating position.
That is, the case where the operation speed detected by the brake operation speed detection unit 82 is equal to or greater than the operation speed threshold is a rapid return operation by the driver, and the amount of operation of the brake pedal 2 by the driver is This is a case where the amount of operation rapidly decreases to a non-operation amount.

  Then, when the operation speed of the brake pedal 2 is less than a preset operation speed threshold, the decompression amount setting unit 90 sets the decompression amount used when ending the brake assist control being performed as the second decompression amount. Set. Here, the second pressure reduction amount is such that the driver of the vehicle V who is operating the brake pedal 2 does not feel a loss of deceleration or a feeling of drag with respect to the operation speed in the return direction of the brake pedal 2. It is a value, and is a value obtained in advance by experiments or the like.

On the other hand, when the operation speed of the brake pedal 2 is equal to or higher than a preset operation speed threshold, the pressure reduction amount setting unit 90 uses a pressure reduction amount (a pressure reduction amount per unit time) used when ending the brake assist control being performed. ) Is set to a first reduced pressure amount that is larger than the second reduced pressure amount.
Therefore, when the operation speed of the brake pedal 2 is equal to or higher than the operation speed threshold, the decompression amount setting unit 90 ends the brake assist control being performed more than when the operation speed of the brake pedal 2 is less than the operation speed threshold. Increase the amount of vacuum used.

  The braking force control amount calculation unit 92 refers to the determination result by the brake assist operation determination unit 84 and calculates the control amount of the hydraulic pressure supplied from the hydraulic unit 6 to each wheel cylinder 1. Here, the control amount of the hydraulic pressure supplied from the hydraulic unit 6 to each wheel cylinder 1 is the increase amount of the hydraulic pressure when the master cylinder pressure is increased in the brake assist control.

  Further, the braking force control amount calculation unit 92 calculates the drive amount of the brake assist motor 38 and the operation (open / close) state of each valve (42, 50, 60, 76) according to the calculated control amount. Then, a command signal including the calculated drive amount and operation state is output to the brake assist motor 38 and each valve (42, 50, 60, 76) every control cycle.

  That is, the braking force control amount calculation unit 92 calculates the command signal and changes the flow rate of the brake fluid flowing through the plurality of pipelines (40, 46, 48, 58, 66, 72, 74) of the hydraulic unit 6. Let

  Specifically, the control amount of the hydraulic pressure supplied to each wheel cylinder 1 (hereinafter also simply referred to as a control amount) is calculated by multiplying the operation amount of the brake pedal 2 by the driver by a correction coefficient. In this calculation, when the brake assist operation determination unit 84 determines that the brake assist operation flag is not established, the operation amount of the brake pedal 2 by the driver detected by the brake operation amount detection unit 80 is controlled. Perform when the threshold is exceeded. Here, the correction coefficient to be multiplied by the operation amount of the brake pedal 2 is a value obtained by time integration for each unit time (in this embodiment, for each control cycle) with a gain α for each unit time. This is a value for setting the hydraulic pressure supplied to the cylinder 1 to the target hydraulic pressure. Specifically, the relationship among the control amounts of the master cylinder pressure, wheel cylinder pressure and hydraulic pressure is as follows.

Wheel cylinder pressure = master cylinder pressure + hydraulic pressure control amount = master cylinder pressure + (brake pedal operation amount x correction factor)
= Master cylinder pressure + (Brake pedal operation amount x α · t1) (1)

  However, t1 is the elapsed time from the start of control amount calculation, and a predetermined time (for example, 5 seconds) set in advance is set as the maximum value. The master cylinder pressure in the above equation (1) is the master cylinder pressure at the start of calculation of the hydraulic pressure control amount.

  On the other hand, the control amount of the hydraulic pressure supplied to each wheel cylinder 1 is calculated so that the control amount of the hydraulic pressure in the brake assist control being performed decreases toward “0”. This calculation is based on the amount of operation of the brake pedal 2 by the driver detected by the brake operation amount detection unit 80 when the brake assist operation determination unit 84 determines that the brake assist operation flag is established. Performed when the value is less than the threshold. In this case, the pressure reduction amount β (first pressure reduction amount or second pressure reduction amount) set by the pressure reduction amount setting unit 90 is supplied to each wheel cylinder 1 from the hydraulic pressure control amount [previous value] in the previous brake assist control. Subtraction is performed until the control amount of the hydraulic pressure is “0”. That is, with respect to the hydraulic pressure supplied to each wheel cylinder 1 in the previous brake assist control, the pressure increase amount is decreased, and the control amount of the hydraulic pressure in the previous brake assist control is decreased toward “0”. . That is, the control amount of the hydraulic pressure is controlled as follows.

  Control amount of hydraulic pressure = Control amount of hydraulic pressure at start of decrease-β · t2 (2)

However, t2 is the elapsed time from the start of decrease in the hydraulic pressure control amount. Note that the minimum value of the hydraulic pressure control amount is zero.
Here, when decreasing the pressure increase amount with respect to the hydraulic pressure supplied to each wheel cylinder 1 in the previous brake assist control, the pressure increase amount is set according to the pressure decrease amount set by the pressure decrease amount setting unit 90. Change the degree of reduction (amount of reduction per unit time).

  Specifically, the reduced pressure amount β per unit time is set to a first reduced pressure amount that is larger than the second reduced pressure amount. As a result, the rate of decrease for decreasing the amount of pressure increase is increased with respect to the hydraulic pressure supplied to each wheel cylinder 1 in the previous brake assist control.

  The brake assist control unit 94 determines whether to perform the above-described brake assist control according to the determination result by the brake assist operation determination unit 84 and the hydraulic pressure control amount calculated by the braking force control amount calculation unit 92. . Here, the state in which the brake assist control is performed includes a state in which the brake assist control being performed is continued.

  Specifically, when the brake assist operation determination unit 84 determines that the brake assist operation flag is not established, the brake assist operation flag is established so that brake assist control is performed. Even if the brake assist operation determination unit 84 determines that the brake assist operation flag is established, the control end determination unit 88 described above has the operation amount of the brake pedal 2 equal to or greater than the operation amount threshold value. Is determined, the brake assist operation flag is established.

  On the other hand, when the brake assist operation determination unit 84 determines that the brake assist operation flag is established, it is determined whether or not the hydraulic pressure control amount calculated by the braking force control amount calculation unit 92 is “0”. To do.

  When the hydraulic pressure control amount calculated by the braking force control amount calculation unit 92 is “0”, the brake assist operation flag is deleted so that the brake assist control being performed is completed. On the other hand, when the hydraulic pressure control amount calculated by the braking force control amount calculation unit 92 is not “0”, the brake force control amount calculation unit 92 calculates the brake assist operation flag while maintaining the state where the brake assist operation flag is established. The brake assist control using the control amount of the hydraulic pressure is continued.

(Processing performed by the brake controller 8)
Hereinafter, the processing performed by the brake controller 8 will be described in detail with reference to FIGS. 1 to 3 and FIG. 4.
FIG. 4 is a flowchart showing processing performed by the brake controller 8.
The flowchart shown in FIG. 4 starts from a state in which the driver of the vehicle V operates (depresses) the brake pedal 2 to brake and decelerate the vehicle V in the vehicle V that is traveling (forward traveling) (FIG. 4). “START” shown in FIG. When the flowchart shown in FIG. 4 is started, the process performed by the brake controller 8 proceeds to the process of step S100.

  In step S100, the brake operation amount detector 80 detects the master cylinder pressure and detects the operation amount of the brake pedal 2 by the driver. Here, the detection of the master cylinder pressure by the brake operation amount detection unit 80 is performed every predetermined sampling time, for example, every 10 [msec]. In step S100, when the operation amount of the brake pedal 2 is detected, the process performed by the brake controller 8 proceeds to step S102.

  In step S102, the brake operation speed detection unit 82 calculates the amount of change per unit time of the master cylinder pressure, and detects the operation speed in the return direction of the brake pedal 2 by the driver. Here, the calculation of the change amount per unit time of the master cylinder pressure by the brake operation speed detection unit 82 is performed in association with the detection of the master cylinder pressure by the brake operation amount detection unit 80, for example. When the operation speed in the return direction of the brake pedal 2 is detected in step S102, the process performed by the brake controller 8 proceeds to step S104.

In step S104, the brake assist operation determination unit 84 determines whether or not a brake assist operation flag is established ("brake assist operation flag = 0?" Shown in step S104). Thereby, in step S104, it is determined whether brake assist control is being implemented.
If it is determined in step S104 that the brake assist operation flag has not been established ("Yes" shown in the figure), the processing performed by the brake controller 8 proceeds to step S106.

On the other hand, if it is determined in step S104 that the brake assist operation flag is established ("No" shown in the figure), the processing performed by the brake controller 8 proceeds to step S108.
In step S106, the control start determination unit 86 determines whether or not the operation amount detected by the brake operation amount detection unit 80 is equal to or greater than the control start threshold value.

If it is determined in step S106 that the operation amount detected by the brake operation amount detection unit 80 is equal to or greater than the control start threshold ("Yes" shown in the figure), the processing performed by the brake controller 8 proceeds to step S110.
On the other hand, when it is determined in step S106 that the operation amount detected by the brake operation amount detection unit 80 is less than the control start threshold value ("No" shown in the figure), the processing performed by the brake controller 8 is completed (in FIG. 4). "END").

In step S108, the control end determination unit 88 determines whether or not the operation amount detected by the brake operation amount detection unit 80 is less than a preset operation amount threshold value.
If it is determined in step S108 that the operation amount detected by the brake operation amount detector 80 is equal to or greater than the operation amount threshold ("No" shown in the figure), the processing performed by the brake controller 8 proceeds to step S110.

  On the other hand, if it is determined in step S108 that the operation amount detected by the brake operation amount detection unit 80 is less than the operation amount threshold ("Yes" shown in the figure), the processing performed by the brake controller 8 proceeds to step S114. .

  In step S110, the braking force control amount calculation unit 92 calculates the control amount of the hydraulic pressure supplied to each wheel cylinder 1 (“control amount = operation amount × correction coefficient” shown in step S110). Thus, in step S110, the hydraulic pressure obtained by increasing the master cylinder pressure is transmitted to each wheel cylinder 1, and a braking force larger than the braking force corresponding to the amount of operation of the brake pedal 2 by the driver is applied to each wheel W. To grant. When a command signal is output to the brake assist motor 38 and each valve (42, 50, 60, 76) in step S110, the process performed by the brake controller 8 proceeds to step S112.

  In step S112, the brake assist control unit 94 establishes a brake assist operation flag ("brake assist operation flag = 1" shown in step S112) so as to perform brake assist control. In step S112, when the brake assist operation flag is established, the processing performed by the brake controller 8 ends (“END” in FIG. 4).

In step S114, the decompression amount setting unit 90 determines whether or not the operation speed detected by the brake operation speed detection unit 82 is equal to or greater than a preset operation speed threshold.
In step S114, when it is determined that the operation speed of the brake pedal 2 by the driver is equal to or higher than a preset operation speed threshold ("Yes" shown in the figure), the processing performed by the brake controller 8 proceeds to step S116.

On the other hand, if it is determined in step S114 that the operation speed of the brake pedal 2 by the driver is less than the preset operation speed threshold ("No" shown in the figure), the processing performed by the brake controller 8 proceeds to step S118. To do.
In step S116, the decompression amount setting unit 90 sets the decompression amount to the first decompression amount. In step S116, when the pressure reduction amount is set to the first pressure reduction amount, the process performed by the brake controller 8 proceeds to step S120.

  In step S118, the decompression amount setting unit 90 sets the decompression amount to a second decompression amount that is smaller than the first decompression amount. If the pressure reduction amount is set to the second pressure reduction amount in step S118, the processing performed by the brake controller 8 proceeds to step S120. Here, the second decompression amount is a value at which the driver of the vehicle V who is operating the brake pedal 2 does not feel any deceleration or dragging with respect to the operation speed in the return direction of the brake pedal 2. It is. Further, the first reduced pressure amount is a value larger than the second reduced pressure amount.

  In step S120, the braking force control amount calculation unit 92 calculates the control amount of the hydraulic pressure supplied to each wheel cylinder 1 (“control amount = (control amount [previous value] −reduction amount, 0) shown in step S120”). Here, when calculating the control amount of the hydraulic pressure supplied to each wheel cylinder 1, the first pressure reduction set in step S116 is used as the pressure reduction amount to be subtracted from the control amount of the hydraulic pressure in the previous brake assist control. Or the second reduced pressure set in step S118.

  Then, the braking force control amount calculation unit 92 outputs a command signal including the calculated drive amount and opening / closing state to the brake assist motor 38 and each valve (42, 50, 60, 76) for each control cycle. In step S120, when a command signal is output to the brake assist motor 38 and each valve (42, 50, 60, 76), the processing performed by the brake controller 8 proceeds to step S122.

In step S122, the brake assist control unit 94 determines whether or not the control amount of the hydraulic pressure supplied to each wheel cylinder 1 calculated by the braking force control amount calculation unit 92 is “0”.
If it is determined in step S122 that the control amount of the hydraulic pressure supplied to each wheel cylinder 1 is “0” (“Yes” shown in the figure), the processing performed by the brake controller 8 proceeds to step S124. Here, the state where the control amount of the hydraulic pressure supplied to each wheel cylinder 1 is “0” means the state where the control amount calculated toward “0” calculated in step S120 has reached “0”. It is.

  On the other hand, if it is determined in step S122 that the control amount of the hydraulic pressure supplied to each wheel cylinder 1 is not “0” (“No” shown in the figure), the processing performed by the brake controller 8 is completed (in FIG. 4). "END"). Here, the state where the control amount of the hydraulic pressure supplied to each wheel cylinder 1 is not “0” means that the control amount that decreases toward “0” calculated in step S120 has reached “0”. It is in a state of decreasing. Thereby, in step S122, the brake assist control using the hydraulic pressure control amount calculated by the braking force control amount calculation unit 92 is continued.

  In step S124, the brake assist control unit 94 deletes the brake assist operation flag (“brake assist operation flag = 0” shown in step S124) so that the brake assist control being executed is completed. In step S124, when the brake assist operation flag is deleted, the processing performed by the brake controller 8 ends (“END” in FIG. 4).

(Operation)
Next, referring to FIGS. 1 to 4, using FIGS. 5 and 6, an example of processing performed by the braking force control device of the present embodiment and the operation of the vehicle V accompanying the processing performed by the braking force control device. An example will be described.

FIG. 5 is a flowchart showing processing performed by the braking force control apparatus.
The flowchart shown in FIG. 5 starts from a state in which the vehicle V is traveling (forward traveling) and the brake assist control is not performed (“START” shown in FIG. 5). When the flowchart shown in FIG. 5 is started, the process performed by the braking force control apparatus proceeds to the process of step S200.

In step S200, the brake sensor 24 or the brake operation amount detector 80 detects the operation of the brake pedal 2 by the driver ("brake pedal ON" shown in step S200). In step S200, when the operation of the brake pedal 2 by the driver is detected, the processing performed by the braking force control device proceeds to step S202.
In step S202, the brake operation amount detector 80 detects the operation amount of the brake pedal 2 by the driver (see step S100). In step S202, when the operation amount of the brake pedal 2 is detected, the processing performed by the braking force control device proceeds to step S204.

  In step S204, the above-described brake assist control is started (see “brake assist start” shown in step S204) (see steps S104, S106, S110, and S112).

  Here, when the braking force control device performs a process of starting the brake assist control, the braking force control amount calculation unit 92 calculates the control amount of the hydraulic pressure supplied to each wheel cylinder 1. Then, the braking force control amount calculation unit 92 outputs a command signal calculated according to the calculated control amount to the brake assist motor 38 and each valve (42, 50, 60, 76) for each control cycle (step). (See S114).

The P-system side gate-in valve 42P and the S-system side gate-in valve 42S that have received the command signal are opened, and the P-system side gate-out valve 60P and the S-system side gate-out valve 60S are closed.
Also, the brake assist motor 38 that has received the input of the command signal drives the P system side pump 36P and the S system side pump 36S. The P system side pump 36P and the S system side pump 36S suck the brake fluid stored in the master cylinder 4.

  Thereby, the hydraulic pressure increased to a hydraulic pressure higher than the master cylinder pressure is supplied to the wheel cylinder 1FL, the wheel cylinder 1RR, the wheel cylinder 1FR, and the wheel cylinder 1RL.

  As described above, when the braking force control device performs the process of starting the brake assist control, in the vehicle V, a braking force larger than the braking force corresponding to the amount of operation of the brake pedal 2 by the driver is applied to each wheel W. It will be. In addition to the gate-in valve 42 and the gate-out valve 60S, the valves (50, 76) that receive input of command signals control the degree of pressure increase (pressure increase, pressure reduction or Operation).

If the process which starts brake assist control is performed in step S204, the process which a braking force control apparatus performs will transfer to step S206.
In step S206, the control end determination unit 88 determines whether or not the driver intends to end the braking of the vehicle V ("braking end?" Shown in step S206) (see step S108). That is, in step S206, it is determined whether or not the driver intends to stop the operation of the brake pedal 2 and the operation of the brake pedal 2 by the driver intends to return the position of the brake pedal 2 to the non-operating position. judge.

If it is determined in step S206 that the driver has an intention to end braking of the vehicle V ("Yes" shown in the figure), the processing performed by the braking force control device proceeds to step S208.
Here, when the driver intends to end the braking of the vehicle V, the amount of operation of the brake pedal 2 by the driver decreases to the amount of operation when the driver is not operated, and the hydraulic pressure of each wheel cylinder 1 becomes the hydraulic pressure. It flows into the master cylinder 4 via the unit 6. Specifically, brake fluid flows from each wheel cylinder 1 to the master cylinder 4 via the hydraulic unit 6. As a result, the master cylinder pressure is reduced as compared with a state where the driver is depressing the brake pedal 2.

On the other hand, if it is determined in step S206 that the driver does not intend to end the braking of the vehicle V ("No" shown in the figure), the processing performed by the braking force control device proceeds to step S204.
In step S208, a process of ending the brake assist control being performed ("control end process" shown in step S208) is performed (see steps S114 to S124).

  When the braking force control device performs the process of ending the brake assist control, the decompression amount setting unit 90 determines whether or not the operation speed detected by the brake operation speed detection unit 82 is equal to or greater than the operation speed threshold (see step S114). )

  Here, when the operation speed detected by the brake operation speed detection unit 82 is equal to or higher than the operation speed threshold, the operation amount of the brake pedal 2 by the driver is rapidly reduced to the operation amount at the time of non-operation. For this reason, the master cylinder pressure rapidly decreases from the state where the driver depresses the brake pedal 2. When the amount of operation of the brake pedal 2 by the driver reaches the amount of operation when not operated, the master cylinder 4 communicates with the reserve tank 28 via the first series passage 26. As a result, the brake fluid in the master cylinder 4 flows into the reserve tank 28 via the first series passage 26.

  When the operation speed detected by the brake operation speed detection unit 82 is equal to or greater than the operation speed threshold, the pressure reduction amount setting unit 90 sets the pressure reduction amount to the first pressure reduction amount (see step S114). Further, the braking force control amount calculation unit 92 calculates the control amount of the hydraulic pressure supplied to each wheel cylinder 1 (see step S120).

  Specifically, in the brake assist control, the first pressure reduction amount set by the pressure reduction amount setting unit 90 is used so that the control amount of the hydraulic pressure supplied to each wheel cylinder 1 decreases toward “0”. Thus, the control amount of the hydraulic pressure supplied to each wheel cylinder 1 is calculated. Then, the braking force control amount calculation unit 92 outputs a command signal calculated according to the calculated control amount to the brake assist motor 38 and each valve (42, 50, 60, 76) for each control cycle (step). (See S120).

  Here, as described above, the first decompression amount indicates that the driver of the vehicle V operating the brake pedal 2 feels that the deceleration is lost or dragged with respect to the operation speed in the return direction of the brake pedal 2. It is a value larger than the second reduced pressure amount which is a value that does not feel.

  Therefore, when the pressure reduction amount is set to the first pressure reduction amount, as shown in FIG. 6, the hydraulic pressure of each wheel cylinder 1 is higher at a higher speed than when the pressure reduction amount is set to the second pressure reduction amount. The amount of control decreases toward “0”. That is, the braking force control amount calculation unit 92, when the amount of operation of the brake pedal 2 by the driver rapidly decreases to the amount of operation at the time of non-operation, than when to gently decrease to the amount of operation at the time of non-operation. Increase the decrease rate of the pressure increase of the fluid pressure increased in the brake assist control.

  This is because, when the pressure reduction amount is set to the first pressure reduction amount, from each wheel cylinder 1 to the master cylinder 4 via the hydraulic unit 6 than when the pressure reduction amount is set to the second pressure reduction amount. This is done by increasing the flow rate of the flowing brake fluid.

  FIG. 6 shows the master cylinder pressure, the hydraulic pressure of each wheel cylinder 1, the amount of operation of the brake pedal 2 by the driver, and the operating speed of the driver in the return direction of the brake pedal 2 in the process of ending the brake assist control. It is a figure which shows the relationship between and elapsed time. In FIG. 6, the master cylinder pressure is indicated as “M / C pressure”, and the hydraulic pressure of each wheel cylinder 1 is indicated as “W / C pressure”. Similarly, in FIG. 6, the operation amount of the brake pedal 2 by the driver is indicated as “operation amount”, and the operation speed in the return direction of the brake pedal 2 by the driver is indicated as “operation speed”.

Further, in FIG. 6, when the pressure reduction amount is set to the first pressure reduction amount, the inclination indicating the change in the hydraulic pressure of each wheel cylinder 1 is indicated by a straight line (solid line) with the sign “R1”. Yes. Similarly, in FIG. 6, when the pressure reduction amount is set to the second pressure reduction amount, the inclination indicating the change in the hydraulic pressure of each wheel cylinder 1 is indicated by a straight line (broken line) with the sign “R2”. ing.
Receiving the command signal from the braking force control amount calculation unit 92, the brake assist motor 38 stops the P system side pump 36P and the S system side pump 36S that are being driven to stop the suction of the brake fluid.

In addition, the P-system side gate-in valve 42P and the S-system side gate-in valve 42S that have received the input of the command signal are closed.
Therefore, the brake fluid sucked by the P system side pump 36P and the S system side pump 36S moves (returns) to the master cylinder 4 again.

  As a result, the hydraulic pressures of the wheel cylinder 1FL, the wheel cylinder 1RR, the wheel cylinder 1FR, and the wheel cylinder 1RL, which are increased to a hydraulic pressure higher than the master cylinder pressure in step S204, also decrease in the same manner as the master cylinder pressure.

  Here, as shown in FIG. 6, when the pressure reduction amount is set to the first pressure reduction amount, the slope R1 indicating the change in the hydraulic pressure of each wheel cylinder 1 is the second pressure reduction amount. The slope is larger than the slope R2 indicating the change when the amount is set.

  For this reason, when the pressure reduction amount is set to the first pressure reduction amount, the flow rate of the brake fluid flowing from the wheel cylinder 1 to the master cylinder 4 becomes larger than when the pressure reduction amount is set to the second pressure reduction amount. Thereby, when the pressure reduction amount is set to the first pressure reduction amount, the difference in hydraulic pressure between the wheel cylinder 1 and the master cylinder 4 is reduced faster than when the pressure reduction amount is set to the second pressure reduction amount. .

Then, the hydraulic pressure between the wheel cylinder 1 and the master cylinder 4 at the time when the amount of operation of the brake pedal 2 by the driver reaches the amount of non-operation (state of “hydraulic pressure 0” shown in FIG. 6). The difference in can be reduced.
Therefore, when the amount of operation of the brake pedal 2 by the driver decreases rapidly and the pressure reduction amount is set to the first pressure reduction amount, the first operation amount when the operation amount of the brake pedal 2 reaches the amount of operation when not operated is first. The flow rate of the brake fluid flowing through the communication passage 26 decreases, and the generation of sound due to the brake fluid flowing through the first series passage 26 is suppressed. For this reason, when the amount of operation of the brake pedal 2 by the driver is rapidly reduced, it is possible to reduce a sense of discomfort given to the driver. This is because the generation of sound due to the brake fluid decreases rapidly when the operation amount of the brake pedal 2 is rapidly reduced to the operation amount when the brake pedal 2 is not operated, and the master cylinder 4 and the reserve tank 28 communicate with each other. This is because the pressure is higher than the hydraulic pressure of the master cylinder 4.

On the other hand, as shown in FIG. 6, when the reduced pressure amount is set to the second reduced pressure amount, the time elapses compared to the case where the reduced pressure amount is set to the first reduced pressure amount. However, the difference in hydraulic pressure between the wheel cylinder 1 and the master cylinder 4 is larger than when the pressure reduction amount is set to the first pressure reduction amount.
And the pressure reduction amount is also set to the first pressure reduction amount for the difference in hydraulic pressure between the wheel cylinder 1 and the master cylinder 4 when the operation amount of the brake pedal 2 by the driver reaches the operation amount at the time of non-operation. It becomes larger than the case.

  As described above, when the pressure reduction amount is set to the second pressure reduction amount, the slope R2 indicating the change in the hydraulic pressure of each wheel cylinder 1 sets the pressure reduction amount to the first pressure reduction amount. This is because the slope R1 is smaller than the slope R1 indicating the change in the hydraulic pressure.

  Therefore, when the amount of operation of the brake pedal 2 by the driver reaches the amount of operation when not operated, a relatively large hydraulic pressure difference occurs between the hydraulic pressures of the wheel cylinder 1 and the master cylinder 4. Then, after the amount of operation of the brake pedal 2 by the driver reaches the amount of operation at the time of non-operation, the hydraulic pressure of the wheel cylinder 1 becomes “0”. In FIG. 6, the time difference between the time when the hydraulic pressure of the wheel cylinder 1 becomes “0” in the case of the inclination R1 and the time when the hydraulic pressure of the wheel cylinder 1 becomes “0” in the case of the inclination R2. This is indicated by the symbol “TD”.

In step S208, when the process for terminating the brake assist control being performed is performed, the process performed by the braking force control apparatus is terminated (“END” in FIG. 5).
As described above, the braking force control method implemented by the operation of the braking force control device of the present embodiment is such that when the operation amount of the brake pedal 2 decreases from the operation amount threshold value to less than the operation amount threshold value, the master cylinder pressure This is a method of reducing the amount of increase in the hydraulic pressure increased to the above hydraulic pressure. In addition to this, when the operating speed in the return direction of the brake pedal 2 is equal to or higher than the operating speed threshold, the hydraulic pressure increased to the hydraulic pressure higher than the master cylinder pressure than when the operating speed is lower than the operating speed threshold. This is a method of increasing the decrease rate of the pressure increase amount.

As described above, the P-system side master cylinder pressure sensor 78P, the S-system side master cylinder pressure sensor 78S, and the brake operation amount detection unit 80 correspond to the brake operation amount detection means.
Similarly, the P-system side master cylinder pressure sensor 78P, the S-system side master cylinder pressure sensor 78S, and the brake operation speed detection unit 82 correspond to brake operation speed detection means.
The control start determination unit 86, the control end determination unit 88, the pressure reduction amount setting unit 90, and the braking force control amount calculation unit 92 correspond to hydraulic pressure control means.

Further, the plurality of pipelines (40, 46, 48, 58, 66, 72, 74) included in the hydraulic unit 6 correspond to the second communication path.
Similarly, the braking force control amount calculation unit 92, the brake assist motor 38 and the valves (42, 50, 60, 76) included in the hydraulic unit 6 correspond to flow rate varying means.

(Effects of the first embodiment)
(1) When the operation amount detected by the brake operation amount detection unit decreases from a preset operation amount threshold value or more to less than the operation amount threshold value, the fluid pressure control means increases the fluid pressure to a fluid pressure equal to or higher than the master cylinder pressure. Reduce the amount of pressure increase.

Further, when the operation speed detected by the brake operation speed detection means is equal to or higher than the preset operation speed threshold, the hydraulic pressure control means is more than the case where the operation speed detected by the brake operation speed detection means is less than the operation speed threshold. Increase the decrease rate of the pressure increase by increasing the fluid pressure.
For this reason, when the operating amount of the brake pedal by the driver decreases rapidly, if the operating speed in the return direction of the brake pedal is high, the decreasing speed that decreases the hydraulic pressure increase amount can be increased. Become.

As a result, it is possible to reduce the hydraulic pressure difference between the wheel cylinder and the master cylinder when the amount of operation of the brake pedal is rapidly reduced.
As a result, the amount of brake fluid flowing through the first series passage when the amount of operation of the brake pedal 2 reaches the non-operation amount is reduced, and the generation of sound by the brake fluid flowing through the first series passage is suppressed. In addition, it is possible to reduce the uncomfortable feeling given to the driver.

(2) The hydraulic pressure control means includes a flow rate variable means for changing the flow rate of the brake fluid flowing through the second communication path. Then, when the operation speed detected by the brake operation speed detection means is equal to or higher than the preset operation speed threshold, the flow rate variable means is more Increase the flow rate of the brake fluid flowing through the double passage.

  For this reason, when the operating amount of the brake pedal by the driver decreases rapidly and the operating speed in the return direction of the brake pedal is high, the flow rate of the brake fluid flowing through the second communication path is increased, and the hydraulic pressure is reduced. It is possible to increase the decrease rate of the pressure increase amount.

  As a result, it is possible to increase the flow rate of brake fluid flowing from the wheel cylinder to the master cylinder when the amount of brake pedal operation decreases rapidly, thereby reducing the hydraulic pressure difference between the wheel cylinder and the master cylinder. Become. Thereby, it becomes possible to reduce the flow volume of the brake fluid flowing through the first series passage when the operation amount of the brake pedal 2 reaches the operation amount at the time of non-operation.

(3) In the braking force control method according to the present embodiment, when the operation amount of the brake pedal decreases from the preset operation amount threshold value to less than the operation amount threshold value, the fluid pressure increased to the fluid pressure greater than the master cylinder pressure. Reduce the amount of pressure increase.

Further, in the braking force control method of the present embodiment, when the operation speed in the return direction of the brake pedal is equal to or higher than the preset operation speed threshold, the hydraulic pressure increased as compared with the case where the operation speed is less than the operation speed threshold. Increase the decrease rate of the pressure increase.
For this reason, when the operating amount of the brake pedal by the driver decreases rapidly, if the operating speed in the return direction of the brake pedal is high, the decreasing speed that decreases the hydraulic pressure increase amount can be increased. Become.

As a result, it is possible to reduce the hydraulic pressure difference between the wheel cylinder and the master cylinder when the amount of operation of the brake pedal is rapidly reduced.
Thereby, the flow rate of the brake fluid flowing through the first series passage is reduced, and the generation of sound by the brake fluid flowing through the first series passage when the operation amount of the brake pedal 2 reaches the operation amount at the time of non-operation is suppressed. In addition, it is possible to reduce the uncomfortable feeling given to the driver.

(Modification)
(1) In the braking force control apparatus according to the present embodiment, the hydraulic pressure control means includes a flow rate varying means for changing the flow rate of the brake fluid flowing through the second communication path, but is not limited thereto. That is, for example, between the master cylinder 4 and each wheel cylinder 1, a bypass oil passage that is different from the second communication passage and through which the brake fluid can move is provided. When the operation speed detected by the brake operation speed detection means is less than the preset operation speed threshold, the brake fluid is circulated only through the second communication path, while the operation speed detected by the brake operation speed detection means is the operation speed. When it is equal to or greater than the threshold, the flow rate of the brake fluid may be changed by causing the brake fluid to flow through both the second communication passage and the bypass oil passage.

(2) In the braking force control apparatus of the present embodiment, the master cylinder pressure is detected by the P-system side master cylinder pressure sensor 78P and the S-system side master cylinder pressure sensor 78S, and the amount of operation of the brake pedal 2 by the driver is determined. Although it detected, it is not limited to this. That is, for example, a stroke sensor that directly detects the stroke (operation amount) of the brake pedal 2 may be provided to detect the operation amount of the brake pedal 2 by the driver. Similarly, the operation speed of the brake pedal 2 by the driver may be detected using the stroke of the brake pedal 2.

(Second embodiment)
Next, a second embodiment of the present invention (hereinafter referred to as the present embodiment) will be described with reference to the drawings.

(Constitution)
First, the configuration of the present embodiment will be described with reference to FIGS. 1 to 3.
The configuration of this embodiment is the same as that of the first embodiment described above, except for the configuration of the decompression amount setting unit 90. Since the configuration other than the decompression amount setting unit 90 is the same as that of the first embodiment described above, detailed description thereof is omitted.
The decompression amount setting unit 90 stores in advance a map indicating the relationship between the operation speed in the return direction of the brake pedal 2 and the decompression amount. The map stored in the decompression amount setting unit 90 will be described later.

In addition, when the brake assist operation determination unit 84 determines that the brake assist control is being performed, the decompression amount setting unit 90 is the same as that in the first embodiment, depending on the operation speed in the return direction of the brake pedal 2. A similar amount of pressure reduction is set.
Specifically, it is determined whether or not the operation speed of the driver in the return direction of the brake pedal 2 detected by the brake operation speed detection unit 82 exceeds a preset increase correction threshold.

Here, the increase correction threshold value is a value corresponding to the second reduced pressure amount in the first embodiment described above, and is a value obtained in advance by an experiment or the like. The increase correction threshold value is set in a map stored in the decompression amount setting unit 90.
That is, when the operation speed detected by the brake operation speed detection unit 82 exceeds the increase correction threshold, the operation of the brake pedal 2 by the driver is a rapid return operation, and the amount of operation of the brake pedal 2 by the driver However, this is a case where the amount of operation rapidly decreases to the amount of operation when no operation is performed.

  When the operation speed of the driver in the return direction of the brake pedal 2 detected by the brake operation speed detection unit 82 exceeds the increase correction threshold, the pressure reduction amount setting unit 90 has a high operation speed of the brake pedal 2. The decompression amount is set to a higher value. Thereby, the higher the operation speed of the brake pedal 2 is, the larger the degree of decrease in the degree of increase in the hydraulic pressure increased to a higher hydraulic pressure than the master cylinder pressure.

(Processing performed by the brake controller 8)
Hereinafter, the process performed by the brake controller 8 will be described in detail with reference to FIGS. 1 to 4 and FIG. 7.

FIG. 7 is a flowchart showing processing performed by the brake controller 8.
The flowchart shown in FIG. 7 starts from a state in which the driver of the vehicle V operates (depresses) the brake pedal 2 to brake and decelerate the vehicle V in the vehicle V that is traveling (forward traveling) (FIG. 7). “START” shown in FIG. When the flowchart shown in FIG. 7 is started, the process performed by the brake controller 8 proceeds to the process of step S300.

The processing in step S300 (“operation amount detection” shown in step S300) is the same as the processing in step S100 described above, and thus the description thereof is omitted. When the process of step S300 is performed, the process performed by the brake controller 8 proceeds to step S302.
The processing in step S302 ("operation speed detection" shown in step S302) is the same as the processing in step S102 described above, and thus the description thereof is omitted. When the process of step S302 is performed, the process performed by the brake controller 8 proceeds to step S304.

  Since the process of step S304 ("brake assist operation flag = 0?" Shown in step S304) is the same as the process of step S104 described above, the description thereof is omitted. When the process of step S304 is performed, the process performed by the brake controller 8 proceeds to step S306 or step S308.

  The processing in step S306 (“operation amount ≧ control start threshold?” Shown in step S306) is the same as the processing in step S106 described above, and thus the description thereof is omitted. When the process of step S306 is performed, the process performed by the brake controller 8 proceeds to step S310 if "Yes" shown in the figure, and ends if "No" shown in the figure (" END ").

  The processing in step S308 (“operation amount <operation amount threshold?” Shown in step S308) is the same as the processing in step S108 described above, and a description thereof will be omitted. When the process of step S308 is performed, the process performed by the brake controller 8 proceeds to step S310 if "No" shown in the figure, and moves to step S314 if "Yes" shown in the figure.

  The processing in step S310 (“control amount = operation amount × correction coefficient” shown in step S310) is the same as the processing in step S110 described above, and a description thereof will be omitted. When the process of step S310 is performed, the process performed by the brake controller 8 proceeds to step S312.

  The processing in step S312 (“brake assist operation flag = 1” shown in step S312) is the same as the processing in step S112 described above, and thus the description thereof is omitted. When the process of step S312 is performed, the process performed by the brake controller 8 ends ("END" shown in FIG. 7).

  In step S314, the decompression amount setting unit 90 determines whether or not the operation speed detected by the brake operation speed detection unit 82 exceeds a preset increase correction threshold. In the map shown in step S314, the increase correction threshold value is indicated by a broken line.

  When the operation speed detected by the brake operation speed detection unit 82 exceeds the preset increase correction threshold, the pressure is reduced based on the relationship between the operation speed of the brake pedal 2 and the pressure reduction amount in the map shown in step S314. Set the amount. That is, in step S314, when the operation speed in the return direction of the brake pedal 2 by the driver detected by the brake operation speed detection unit 82 exceeds the increase correction threshold, the higher the operation speed of the brake pedal 2, Set the decompression amount to a large value. As a result, in step S314, as the operating speed of the brake pedal 2 is higher, the decreasing speed of the hydraulic pressure increased to a higher hydraulic pressure than the master cylinder pressure is increased.

When the operation speed detected by the brake operation speed detection unit 82 is less than the increase correction threshold, the amount of pressure reduction is set to a smaller value than when the operation speed is greater than or equal to the increase correction threshold. In this case, the pressure reduction amount is set to the same value as the second pressure reduction amount in the first embodiment described above, for example.
When the pressure reduction amount is set in step S314, the process performed by the brake controller 8 proceeds to step S316.

  The processing in step S316 (“control amount = (control amount [previous value] −depressurization amount, 0)” shown in step S316) is the same as the processing in step S120 described above, and a description thereof will be omitted. When the process of step S316 is performed, the process performed by the brake controller 8 proceeds to step S318.

  The processing in step S318 (“control amount = 0?” Shown in step S318) is the same as the processing in step S122 described above, and thus the description thereof is omitted. When the processing of step S318 is performed, the processing performed by the brake controller 8 proceeds to step S320 if "Yes" shown in the figure, and ends if "No" shown in the figure ("shown in FIG. 7" END ").

Since the process of step S320 ("brake assist operation flag = 0" shown in step S320) is the same as the process of step S124 described above, the description thereof is omitted. When the process of step S320 is performed, the process performed by the brake controller 8 ends ("END" shown in FIG. 7).
Other configurations are the same as those of the first embodiment described above.

(Operation)
Next, an example of processing performed by the braking force control device of the present embodiment and an example of operation of the vehicle V accompanying processing performed by the braking force control device will be described with reference to FIGS. In the following description, since the same processing as that of the first embodiment described above is performed except for the processing for ending the brake assist control being performed, the processing of the different parts and the operation of the vehicle V accompanying this processing are described. To do.

When the braking force control device performs the process of ending the brake assist control (see step S208), the operation amount detected by the control end determination unit 88 by the brake operation amount detection unit 80 is less than the preset operation amount threshold value. Whether or not (see step S308).
When the operation amount detected by the brake operation amount detection unit 80 is less than the operation amount threshold set by the pressure reduction amount setting unit 90, the operation speed detected by the brake operation speed detection unit 82 in the pressure reduction amount setting unit 90 increases. It is determined whether or not the correction threshold is exceeded (see step S314).

Here, when the operation speed detected by the brake operation speed detection unit 82 exceeds the increase correction threshold, the pressure reduction amount setting unit 90 sets the pressure reduction amount to a higher value as the operation speed of the brake pedal 2 is higher ( (See step S314).
When the pressure reduction amount setting unit 90 sets the pressure reduction amount, the braking force control amount calculation unit 92 calculates the control amount of the hydraulic pressure supplied to each wheel cylinder 1 using the set pressure reduction amount. At this time, as in the first embodiment described above, in the brake assist control, the control amount of the hydraulic pressure supplied to each wheel cylinder 1 is supplied to each wheel cylinder 1 so as to decrease toward “0”. Calculate the control amount of the hydraulic pressure. Then, the braking force control amount calculation unit 92 outputs a command signal calculated according to the calculated control amount to the brake assist motor 38 and each valve (42, 50, 60, 76) for each control cycle (step). (See S316).

Here, the decompression amount set by the decompression amount setting unit 90 is a value exceeding the above-described second decompression amount, and becomes a larger value as the operation speed of the brake pedal 2 is higher. Thus, the higher the operation speed of the brake pedal 2 is, the larger the decrease speed at which the hydraulic pressure increase amount is decreased.
For this reason, the pressure reduction amount is set to an appropriate value in accordance with the operation speed of the brake pedal 2 in the return direction by the driver, and the brake fluid flowing from each wheel cylinder 1 to the master cylinder 4 as time elapses. It becomes possible to change the flow rate.

  This makes it possible to change the braking force applied to the wheels W during braking of the vehicle V in accordance with the amount of operation of the brake pedal 2, and to change the behavior of the vehicle V during braking to the amount of operation of the brake pedal 2. It becomes possible to make it behave according to.

  As described above, the higher the operation speed detected by the brake operation speed detection unit 82, the larger the decrease speed when the control amount of the hydraulic pressure of each wheel cylinder 1 is decreased toward “0”. That is, when the amount of operation of the brake pedal 2 by the driver rapidly decreases to the amount of operation at the time of non-operation, the braking force control amount calculation unit 92 has a high operation speed in the return direction of the brake pedal 2 by the driver. As the pressure increases, the decrease rate of the pressure increase is increased.

  Therefore, as in the first embodiment described above, when the amount of operation of the brake pedal 2 by the driver is rapidly reduced, the difference in hydraulic pressure between the wheel cylinder 1 and the master cylinder 4 is reduced. For this reason, when the operation amount of the brake pedal 2 becomes the operation amount at the time of non-operation, the flow rate of the brake fluid flowing through the first series passage 26 decreases, and the sound of the brake fluid flowing through the first series passage 26 is reduced. Occurrence is suppressed.

  Further, when the amount of operation of the brake pedal 2 by the driver is rapidly reduced, the decrease speed for decreasing the pressure increase amount is increased as the operation speed in the return direction of the brake pedal 2 is higher. For this reason, it becomes possible to change the decreasing speed of the pressure increasing amount according to the operating speed of the brake pedal 2 in the return direction by the driver, and the behavior of the vehicle V during braking is changed to the operating amount of the brake pedal 2. It becomes possible to make the behavior according to.

  As described above, the decompression amount setting unit 90 corresponds to the decrease speed correction unit.

(Effect of the second embodiment)
(1) The decrease speed correction means increases the decrease speed of the pressure increase amount of the hydraulic pressure increased to a higher hydraulic pressure than the master cylinder pressure as the operation speed detected by the brake operation speed detection means is higher.
For this reason, according to the operation speed of the brake pedal in the return direction by the driver, it is possible to set the pressure reduction amount to an appropriate value and change the decrease rate of the hydraulic pressure increase amount.

  As a result, when the operation amount of the brake pedal rapidly decreases, the generation of sound by the brake fluid flowing through the first series passage is suppressed when the operation amount of the brake pedal 2 becomes the operation amount at the time of non-operation. It becomes possible.

  In addition, the braking force applied to the wheels during braking of the vehicle can be changed according to the operating speed of the brake pedal, and the behavior of the vehicle during braking depends on the operating speed of the brake pedal. It becomes possible. This makes it possible to reduce the uncomfortable feeling given to the driver when the amount of operation of the brake pedal rapidly decreases.

(2) When the operation speed detected by the brake operation speed detection means exceeds the preset increase correction threshold, the decrease speed correction means is higher than the master cylinder pressure as the operation speed detected by the brake operation speed detection means is higher. Increase the decrease rate of the pressure increase of the fluid pressure increased to the fluid pressure.

For this reason, it becomes possible to suppress the erroneous detection with respect to the operation speed in the return direction of the brake pedal by the driver.
As a result, when the operation amount of the brake pedal rapidly decreases, the generation of sound by the brake fluid flowing through the first series passage when the operation amount of the brake pedal 2 becomes the operation amount when not operating is reduced. In addition, it is possible to accurately control the behavior of the vehicle during braking.

(Modification)
(1) In the braking force control apparatus of the present embodiment, the decrease speed correction means increases the decrease speed of the pressure increase amount when the operation speed detected by the brake operation speed detection means exceeds a preset increase correction threshold. However, the present invention is not limited to this. In other words, the lower the operation speed detected by the brake operation speed detection means, the higher the operation speed detected by the brake operation speed detection means without referring to the determination result of whether or not the operation speed detected by the brake operation speed detection means exceeds the increase correction threshold. The decrease rate of the pressure increase amount may be increased.

1 wheel cylinder (wheel cylinder 1FL, wheel cylinder 1FR, wheel cylinder 1RL, wheel cylinder 1RR)
2 Brake pedal 4 Master cylinder 6 Hydraulic unit 8 Brake controller 22 Brake booster 24 Brake sensor 26 First series passage 28 Reserve tank 36 Pump 38 Brake assist motor 42 Gate-in valve 50 Solenoid-in valve 60 Gate-out valve 68 Reservoir 76 Solenoid Out valve 78 Master cylinder pressure sensor (P system side master cylinder pressure sensor 78P, S system side master cylinder pressure sensor 78S)
80 Brake operation amount detection unit 82 Brake operation speed detection unit 84 Brake assist operation determination unit 86 Control start determination unit 88 Control end determination unit 90 Depressurization amount setting unit 92 Braking force control amount calculation unit 94 Brake assist control unit V Vehicle W Wheel ( (Left front wheel WFL, Right front wheel WFR, Left rear wheel WRL, Right rear wheel WRR)

Claims (5)

A master cylinder that communicates with the reserve tank via the first series passage when the brake pedal is not operated, and that generates a master cylinder pressure corresponding to the operation amount of the brake pedal;
A wheel cylinder that communicates with the master cylinder via a second communication path and that applies a braking force to the wheel by hydraulic pressure;
Hydraulic pressure control means for increasing the hydraulic pressure of the wheel cylinder to a hydraulic pressure equal to or higher than the master cylinder pressure;
Brake operation amount detection means for detecting the operation amount of the brake pedal;
A brake operation speed detecting means for detecting an operation speed in the return direction of the brake pedal,
When the operation amount detected by the brake operation amount detection unit decreases from a preset operation amount threshold value to less than the operation amount threshold value, the fluid pressure control unit decreases the increase amount of the fluid pressure, and When the operation speed detected by the brake operation speed detection means is greater than or equal to a preset operation speed threshold, the pressure increase amount is greater than when the operation speed detected by the brake operation speed detection means is less than the operation speed threshold. A braking force control device characterized by increasing the decreasing speed of the brake. The hydraulic pressure control means includes flow rate variable means for changing the flow rate of the brake fluid flowing through the second communication path,
When the operation speed detected by the brake operation speed detection means is greater than or equal to a preset operation speed threshold, the flow rate varying means is when the operation speed detected by the brake operation speed detection means is less than the operation speed threshold. The braking force control device according to claim 1, wherein the flow rate is increased to increase the decrease rate.   3. The braking force control apparatus according to claim 1, further comprising a decrease speed correction unit that increases the decrease speed as the operation speed detected by the brake operation speed detection unit increases. 4.   4. The decrease speed correction means increases the decrease speed as the operation speed increases when the operation speed detected by the brake operation speed detection means exceeds a preset increase correction threshold. The braking force control device described in 1. When the brake pedal is not operated, the hydraulic pressure of the master cylinder that communicates with the reserve tank via the first series passage and the wheel cylinder that imparts braking force to the wheel and communicates with the reserve tank is applied to the brake pedal. According to the operation amount, the pressure is increased to a hydraulic pressure higher than the master cylinder pressure generated in the master cylinder,
When the operation amount of the brake pedal decreases from a predetermined operation amount threshold value or more to less than the operation amount threshold value, the hydraulic pressure increase amount is decreased and the operation speed in the return direction of the brake pedal is set in advance. A braking force control method, wherein when the operation speed is equal to or greater than an operation speed threshold, the decrease speed of the pressure increase amount is made larger than when the operation speed is less than the operation speed threshold.

Images