JP6235351B2 - Braking device for vehicle - Google Patents

Description

  The present invention relates to a vehicle braking device that controls a friction braking force applied to a vehicle.

  As an example of a vehicle braking device that controls a friction braking force applied to a vehicle, for example, a vehicle braking device described in Patent Document 1 is known. In this vehicle braking device, in a state where the input piston and the output piston are separated from each other, the servo pressure generated by the pressure accumulator (accumulator) and the linear valve is applied to the output piston to drive the output piston, It has a master cylinder device that generates a master pressure.

JP 2012-16984 A

  By the way, at the time of brake fading, a desired friction braking force cannot be obtained unless the brake fluid fed from the master cylinder device to the wheel cylinder is increased as compared with the case of non-fading. However, Patent Document 1 does not disclose any control during brake fading.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a vehicle braking device that can ensure a desired friction braking force during a brake fade.

The invention according to claim 1 is a vehicular braking device that supplies brake fluid to a wheel cylinder of a friction brake device provided on a wheel of a vehicle, and generates a friction braking force on the wheel by the friction brake device. A master cylinder connected to the wheel cylinder; and a slidably disposed in the master cylinder, driven by hydraulic pressure in a servo chamber partitioned by the master cylinder, and supplied to the wheel cylinder An output piston that changes the volume of the master chamber filled with the brake fluid, and a space that is slidable behind the output piston in the master cylinder and is filled with the brake fluid between the output piston and the output piston. An input piston that is linked to the operation of the brake operation member, and a flow path that is connected to the separation chamber; A separation chamber valve that opens the separation chamber by a valve and closes the separation chamber by a valve; a servo pressure generator that generates servo pressure in the servo chamber; and whether the friction brake device is in a fade state fade state determination section determines, when said said friction braking device by fading state determination unit is determined to be the a fade state, closes the separation chamber by said separation chamber valve, the fade state determination When the friction brake device is determined to be in a non-fade state by the part, the separation chamber valve control unit that opens the separation chamber by the separation chamber valve and the fade state determination unit determine As the friction brake device transitions from the non-fade state to the fade state, the servo pressure generator generates the servo chamber. Wherein the hydraulic and the output piston performs a precharge processing is increased by a predetermined precharge pressure is the pressure for advancing a predetermined distance relative to the input piston, and is determined by the fade condition determination unit When the state of the friction brake device transitions from the fade state to the non-fade state, the servo pressure generating unit executes a precharge end process for reducing the hydraulic pressure in the servo chamber by the precharge pressure. A precharge control unit, a reaction force chamber forming unit that forms a reaction force chamber that generates a hydraulic pressure as an operation reaction force that opposes the force acting on the brake operation member, the reaction force chamber, and the brake fluid And a reaction force chamber valve that opens and closes a flow path between the reservoir and the reservoir, and the fade state determination unit causes the friction brake device to be in the fade state. The reaction force chamber valve is opened, and the reaction force chamber valve is opened when the fade state determination unit determines that the friction brake device is in a non-fade state. A reaction force chamber valve control section for closing the valve, and a flow path on the opposite side to the separation chamber of the separation chamber valve is connected to a flow path on the reaction force chamber side of the reaction force chamber valve, The separation chamber valve control unit has closed the reaction force chamber valve by the reaction force chamber valve control unit when the fade state determination unit determines that the friction brake device is in a non-fade state. Later, the separation chamber valve is opened .

  Thus, when it is determined that the friction brake device is in a fade state, the separation chamber is closed by the separation chamber valve. As a result, the separation chamber becomes liquid-tight, and the brake fluid in the separation chamber becomes a rigid body. Therefore, the output piston moves by the stroke amount of the input piston interlocked with the brake operation member, and the volume of the master chamber is the amount corresponding to the stroke amount. Change. In this manner, in the fade state of the friction brake device, the brake fluid is removed from the master chamber by the amount corresponding to the operation amount of the brake operation member by preventing the input piston from moving relative to the output piston. The desired friction braking force can be ensured by feeding the cylinder.

  When it is determined that the friction brake device is in a fade state, precharge control for generating a precharge pressure in the servo chamber is executed, and the output piston moves forward relative to the input piston. As a result, when the friction brake device is in a fade state (hereinafter referred to as “fade of the friction brake device”), more brake fluid than the brake fluid supplied from the master chamber to the wheel cylinder when the precharge control is not executed. Can be supplied from the master cylinder to the wheel cylinder, and a larger friction braking force can be generated in the friction brake device.

In addition, precharge end processing is executed in which the hydraulic pressure in the servo chamber is reduced by the precharge pressure as the friction brake device changes from the fade state to the non-fade state. Thereby, when the friction brake device is in a non-fade state, generation of excessive braking force due to the hydraulic pressure in the servo chamber being increased by the precharge pressure is prevented.
Further, the sliding of the input piston is prevented from being caused by the opening of the separation chamber valve before the reaction force chamber valve is closed and the separation chamber is opened. The movement of the interlocking brake operation member is prevented. For this reason, generation | occurrence | production of the driver | operator's uncomfortable feeling accompanying the movement of a brake operation member is prevented.
According to a second aspect of the present invention, there is provided a vehicular braking device that supplies brake fluid to a wheel cylinder of a friction brake device provided on a vehicle wheel, and generates a friction braking force on the wheel by the friction brake device. A master cylinder connected to the wheel cylinder; and a slidably disposed in the master cylinder, driven by hydraulic pressure in a servo chamber partitioned by the master cylinder, and supplied to the wheel cylinder An output piston that changes the volume of the master chamber filled with the brake fluid, and a space that is slidable behind the output piston in the master cylinder and is filled with the brake fluid between the output piston and the output piston. An input piston that is linked to the operation of the brake operation member, and a flow path that is connected to the separation chamber; A separation chamber valve that opens the separation chamber by a valve and closes the separation chamber by a valve; a servo pressure generator that generates servo pressure in the servo chamber; and whether the friction brake device is in a fade state When the friction brake device is determined to be in a fade state by the fade state determination unit and the fade state determination unit, the separation chamber valve closes the separation chamber, and the fade state determination unit When it is determined that the friction brake device is in a non-fade state, the separation chamber valve control unit that opens the separation chamber by the separation chamber valve and the friction that is determined by the fade state determination unit As the brake device transitions from the non-fade state to the fade state, the servo pressure generator causes the servo chamber to The friction brake is subjected to a precharge process for increasing a pressure by a predetermined precharge pressure that is a pressure for advancing the output piston by a predetermined distance with respect to the input piston, and is determined by the fade state determination unit Precharge for executing a precharge end process for reducing the hydraulic pressure in the servo chamber by the precharge pressure by the servo pressure generator when the state of the apparatus transitions from the fade state to the non-fade state. A control unit, a reaction force chamber forming portion that forms a reaction force chamber that generates a hydraulic pressure as an operation reaction force that opposes the force acting on the brake operation member, and the reaction force chamber and the brake fluid are accommodated The friction brake device is in the fade state by the reaction force chamber valve that opens and closes the flow path between the reservoir and the reservoir and the fade state determination unit. Is determined to open the reaction force chamber, and when the fade state determination unit determines that the friction brake device is in a non-fade state, the reaction force chamber valve is closed. A reaction chamber valve control unit that controls the valve, and a flow path on the opposite side to the separation chamber of the separation chamber valve is connected to a flow path on the reaction force chamber side of the reaction force chamber valve, and the separation chamber The valve control unit starts the valve closing of the reaction force chamber valve by the reaction force chamber valve control unit when it is determined by the fade state determination unit that the friction brake device is in a non-fade state. After the time corresponding to the operation state of the brake operation member has elapsed, the opening of the separation chamber valve is started.
According to this, when the separation chamber valve is closed, the separation chamber and the reaction force chamber are not in communication with each other. Therefore, the faster the operation speed of the brake operation member, the more the driver feels that the brake operation member is operating. I feel heavy. The faster the operating speed of the brake operating member, the shorter the time it takes for the separation chamber valve to open after the reaction chamber valve starts to be closed. The feeling time is shorter and the uncomfortable feeling that the driver learns is alleviated.

According to a third aspect of the present invention, in the first or second aspect of the invention, the precharge control unit gradually decreases the hydraulic pressure in the servo chamber in the precharge end process. As a result, in the precharge end process, a sudden decrease in braking force due to a rapid decrease in hydraulic pressure in the servo chamber, that is, a rapid decrease in vehicle deceleration is alleviated. For this reason, the uncomfortable feeling felt by the driver due to the decrease in the deceleration of the vehicle is alleviated.

According to a fourth aspect of the present invention, in the first to third aspects of the present invention, the amount of decrease in the hydraulic pressure in the servo chamber per unit time in the precharge end processing is less than the vehicle speed or deceleration. A reduction amount setting unit that sets the amount to be as small as possible, and the precharge control unit is configured to reduce the amount per unit time set by the reduction amount setting unit in the precharge end process. Reduce fluid pressure.

  The lower the vehicle speed and deceleration, the more uncomfortable the driver feels due to the decrease in vehicle deceleration in the precharge end process. As described above, the decrease amount per unit time of the hydraulic pressure in the servo chamber in the precharge end process is set to a smaller amount as the vehicle speed and deceleration are lower, and the decrease in vehicle deceleration is reduced. The driver feels uncomfortable.

According to a fifth aspect of the present invention, in the first to fourth aspects of the present invention, the separation chamber valve control unit determines that the friction brake device is in a non-fade state by the fade state determination unit. When the separation chamber valve is opened, the opening degree of the separation chamber valve is gradually increased.

  As a result, the separation chamber valve is suddenly opened and the operation feeling of the brake operation member felt by the driver due to the sudden communication between the separation chamber and the reaction force chamber is prevented, and the driver feels uncomfortable. Is reduced.

It is a schematic diagram showing one embodiment of a hybrid vehicle on which the vehicle braking device of the present embodiment is mounted. It is a fragmentary sectional view showing the composition of the brake device for vehicles of this embodiment. It is sectional drawing which shows the structure of the regulator of this embodiment. It is a flowchart of the fade mode control process which is a control program executed by the brake ECU shown in FIG. It is a graph showing the relationship between elapsed time, the state of a separation chamber valve, the state of a reaction force chamber valve, a precharge execution request, a precharge end processing request, and a precharge pressure. It is a graph showing the relationship between the movement amount of an input piston and servo pressure. It is a graph showing the relationship between pedal effort and master pressure. It is the mapping data showing the relationship between the depression speed of a brake pedal, and a separation chamber valve opening start time. It is the mapping data showing the relationship between the depression speed of a brake pedal, and the electric current increase gradient supplied to a separation chamber valve. It is a figure showing the valve closing timing of a reaction force chamber valve, and the valve opening of a separation chamber valve. It is the mapping data showing the relationship between a vehicle speed and a precharge pressure reduction gradient. It is the mapping data showing the relationship between deceleration and precharge decompression gradient. 6 is a graph showing a relationship between a brake fluid supply amount and a wheel cylinder pressure when there is no precharge control and when there is precharge control.

(Description of hybrid vehicle)
Hereinafter, embodiments of the present invention will be described with reference to the drawings. As shown in FIG. 1, a hybrid vehicle (hereinafter simply referred to as a vehicle) on which the friction brake unit B (vehicle braking device) of the present embodiment is mounted drives drive wheels such as left and right front wheels Wfl, Wfr. It is a vehicle to let you. The vehicle includes an engine 501 and a motor 502. The driving force of the engine 501 is transmitted to the driving wheels via the power split mechanism 503 and the power transmission mechanism 504, and the driving force of the motor 502 is transmitted to the driving wheels via the power transmission mechanism 504. It has become so.

  The vehicle includes an inverter 506. The inverter 506 converts voltage between the motor 502 and the generator 505 and a battery 507 serving as a DC power source. The engine ECU 8 adjusts the rotation speed of the engine 501 based on a command from the hybrid ECU 9. The hybrid ECU 9 controls the motor 502 and the generator 505 through the inverter 506. The hybrid ECU 9 is connected to a battery 507 and monitors the charging state, charging current, and the like of the battery 507.

  The regenerative braking device A is composed of the above-described generator 505, inverter 506, and battery 507. The regenerative braking device A generates regenerative braking force by the generator 505 on the left and right front wheels Wfl and Wfr based on a “target regenerative braking force” described later. In the embodiment shown in FIG. 1, the motor 502 and the generator 505 are separate bodies, but a motor generator in which the motor and the generator are integrated may be used.

  In the vicinity of each wheel Wfl, Wfr, Wrl, Wrr, there are brake pads DRfl, DRfr, DRrl, DRrr that rotate integrally with each wheel Wfl, Wfr, Wrl, Wrr, and brake pads DRfl, DRfr, DRrr, DRrr. Friction brake devices Bfl, Bfr, Brl, and Brr that generate a friction braking force by pressing (not shown) are provided. The friction brake devices Bfl, Bfr, Brl, Brr include wheel cylinders WCfl that press the brake pads against the brake discs DRfl, DRfr, DRrl, DRrr by a master pressure generated by a master cylinder device 1 (shown in FIG. 2) described later. , WCfr, WCrl, WCrr are provided.

  The vehicle is provided with an accelerator pedal 20 and an accelerator sensor 73. The accelerator sensor 73 detects an operation amount of the accelerator pedal 20 (hereinafter abbreviated as “accelerator operation amount”), and outputs a detection signal to the hybrid ECU 9. The hybrid ECU 9 calculates “required driving force” based on the “accelerator operation amount” detected by the accelerator sensor 73.

(Description of braking device for vehicle)
As shown in FIG. 2, the friction brake unit B (vehicle braking device) of the present embodiment mainly includes a master cylinder device 1, a reaction force generator 2, a separation chamber valve 22, and a reaction force chamber valve 3. The servo pressure generator 4, the pressure regulator 53, the brake ECU 6, and various sensors 72 to 75 that can communicate with the brake ECU 6.

  Further, the friction brake unit B includes wheel speed sensors Sfl, Sfr, Srl, Srr as shown in FIG. Wheel speed sensors Sfl, Sfr, Srl, Srr are provided in the vicinity of each wheel Wfl, Wfr, Wrl, Wrr, and brake a pulse signal having a frequency according to the rotation of each wheel Wfl, Wfr, Wrl, Wrr. It outputs to ECU6 and hybrid ECU9.

(Description of master cylinder device)
As shown in FIG. 2, the master cylinder device 1 is connected to the wheel cylinders WCfl, WCfr, WCrl, and WCrr via pipes 52 and 51 and a pressure adjusting device 53. The master cylinder device 1 supplies brake fluid to the pressure adjusting device 53 and supplies it to the wheel cylinders WCfl, WCfr, WCrl, WCrr, and mainly includes the main cylinder 11, the cover cylinder 12, and the input piston 13. And a first output piston 14 and a second output piston 15.

  The main cylinder 11 is a bottomed substantially cylindrical cylinder having an opening at one end and a bottom surface at the other end. Hereinafter, the master cylinder device 1 will be described assuming that the opening side of the main cylinder 11 is the rear side and the bottom surface side (closed side) of the main cylinder 11 is the front side. The main cylinder 11 has an intermediate wall 111 for separating the opening side (rear side) and the bottom surface side (front side) of the main cylinder 11 inside. In other words, an intermediate wall 111 protruding in the axial direction over the entire circumference in the axial direction is formed in the axial direction intermediate portion of the inner peripheral surface of the main cylinder 11. The inner peripheral surface of the intermediate wall 111 is a through hole 111a that penetrates in the axial direction (front-rear direction).

  Further, inside the main cylinder 11, there are a small-diameter portion 112 (front) and a small-diameter portion 113 (rear) having a smaller inner diameter in front of the intermediate wall 111. That is, the small diameter portions 112 and 113 protrude from a part of the entire circumference of the inner peripheral surface of the main cylinder 11 in the axial direction. Inside the main cylinder 11, both output pistons 14 and 15, which will be described later, are arranged so as to be slidable in the axial direction. Note that ports and the like that allow communication between the inside and the outside will be described later.

  The cover cylinder 12 has a substantially cylindrical cylinder portion 121 and a cup-shaped cover portion 122. The cylinder part 121 is disposed on the rear end side of the main cylinder 11 and is coaxially fitted to the opening of the main cylinder 11. The inner diameter of the front part 121a of the cylinder part 121 is larger than the inner diameter of the rear part 121b. Further, the inner diameter of the front part 121a is larger than the inner diameter of the through hole 111a of the intermediate wall 111.

  The cover portion 122 is assembled to the rear end portion of the main cylinder 11 and the outer peripheral surface of the cylinder portion 121 so as to close the opening of the main cylinder 11 and the rear end side opening of the cylinder portion 121. A through hole 122 a is formed in the bottom wall of the cover portion 122. The cover portion 122 is made of an elastic member that can expand and contract in the axial direction, and the bottom wall is urged rearward.

  The input piston 13 is a piston that slides in the cover cylinder 12 in conjunction with the operation of the brake pedal 10. The input piston 13 is disposed behind the projecting portion 142 of the first output piston 14 to be described later and spaced from the projecting portion 142 so as to be slidable in the axial direction in the cover cylinder 12. The input piston 13 is a bottomed substantially cylindrical piston having a bottom surface at the front and an opening at the rear. The bottom wall 131 constituting the bottom surface of the input piston 13 has a larger diameter than other portions of the input piston 13. The input piston 13 is disposed so that the bottom wall 131 is positioned at the rear end in the front portion 121 a of the cylinder portion 121. The input piston 13 is slidable in the axial direction and liquid-tightly disposed in the rear portion 121b of the cylinder portion 121.

  Inside the input piston 13, the operation rod 10a of the brake pedal 10 is inserted forward from the rear end of the input piston 13, and the operation rod 10a and the input piston 13 are formed by a pivot 10b formed at the tip (front end) of the operation rod 10a. Are connected. The operation rod 10 a protrudes to the outside through the opening of the input piston 13 and the through hole 122 a of the cover portion 122, and is connected to the brake pedal 10. The operating rod 10a moves in conjunction with the operation of the brake pedal 10, and moves forward while squeezing the cover 122 in the axial direction when the brake pedal 10 is depressed. In this way, the brake pedal 10 transmits the operation force (stepping force) from the driver applied to the brake pedal 10 to the input piston 13. As the operating rod 10a advances, the input piston 13 also advances.

  The first output piston 14 is disposed in the main cylinder 11 in front of the input piston 13 so as to be slidable in the axial direction. Specifically, the first output piston 14 includes a first pressurizing piston portion 141 and a protruding portion 142. The first pressurizing piston portion 141 is coaxially disposed in the main cylinder 11 on the front side of the intermediate wall 111. The first pressurizing piston portion 141 is formed in a substantially bottomed cylindrical shape having an opening in the front and a servo pressure receiving portion 141a in the rear. That is, the first pressurizing piston part 141 is configured by a servo pressure receiving part 141a and a peripheral wall part 141b.

  The servo pressure receiving portion 141a is slidable in the axial direction and liquid-tightly disposed in the main cylinder 11 in front of the intermediate wall 111. In other words, the servo pressure receiving portion 141a is formed on the outer peripheral surface of the first pressurizing piston portion 141 so as to protrude on the outer peripheral side over the entire circumference in the circumferential direction. The servo pressure receiving portion 141a faces the front end surface of the intermediate wall 111. The peripheral wall portion 141b is formed in a cylindrical shape having a smaller diameter than the servo pressure receiving portion 141a, and extends coaxially forward from the front end surface of the servo pressure receiving portion 141a. The front portion of the peripheral wall portion 141b is slidably and liquid-tightly arranged in the small diameter portion 112 in the axial direction. A rear portion of the peripheral wall portion 141 b is separated from the inner peripheral surface of the main cylinder 11.

  The protruding portion 142 is a columnar portion protruding rearward from the center of the rear end surface of the first pressure piston portion 141. The protruding portion 142 has a smaller diameter than the first pressure piston portion 141. The protrusion 142 penetrates the through hole 111a of the intermediate wall 111 and is arranged to be slidable in the axial direction. The outer peripheral surface of the protrusion 142 and the inner peripheral surface of the through hole 111a are liquid-tight by a seal member attached to the through hole 111a and in contact with the outer peripheral surface of the protrusion 142 over the entire periphery. A rear portion of the protruding portion 142 protrudes into the cylinder portion 121 from the through hole 111a to the rear. A rear portion of the protruding portion 142 is separated from the inner peripheral surface of the cylinder portion 121. The rear end surface of the protrusion 142 is separated from the bottom wall 131 of the input piston 13 by a predetermined distance. The first output piston 14 is urged rearward by an urging member 143 made of a spring or the like.

  Here, the brake fluid is filled by the servo pressure receiving portion 141a rear end surface of the first pressurizing piston portion 141, the intermediate wall 111 front end surface, the inner peripheral surface of the main cylinder 11 on the front side of the intermediate wall 111, and the outer peripheral surface of the protrusion 142. The servo chamber 1A is partitioned. In addition, the “separation chamber 1 </ b> B” filled with the brake fluid is defined by the rear end surface of the intermediate wall 111, the outer surface of the input piston 13, the inner peripheral surface of the front portion 121 a of the cylinder portion 121, and the outer surface of the protrusion 142. Further, the “reaction force pressure chamber 1 </ b> C” is defined by the rear end surface of the small-diameter portion 112 (including the seal member 91), the outer peripheral surface of the peripheral wall portion 141 b, the front end surface of the servo pressure receiving portion 141 a, the peripheral wall portion 141 b, and the inner peripheral surface of the main cylinder 11. Has been.

  The second output piston 15 is coaxially disposed in front of the first output piston 14 in the main cylinder 11. The second output piston 15 is formed in a substantially bottomed cylindrical shape having an opening at the front and a bottom wall (second pressure piston portion 151) at the rear. That is, the second output piston 15 includes a cylindrical second pressure piston portion 151 and a peripheral wall portion 152 that protrudes forward from the second pressure piston portion 151. The second pressurizing piston portion 151 is disposed between the small diameter portions 112 and 113 in front of the first output piston 14. A rear portion of the second output piston 15 including the second pressurizing piston portion 151 is separated from the inner peripheral surface of the main cylinder 11. The peripheral wall portion 152 has a cylindrical shape and extends coaxially forward from the outer edge of the second pressure piston portion 151. The peripheral wall portion 152 is slidably and liquid-tightly arranged in the small diameter portion 113 in the axial direction. The second output piston 15 is urged rearward by an urging member 153 made of a spring or the like.

  Here, the outer surface of the second output piston 15, the front end surface of the first output piston 14, the inner surface of the first output piston 14, the front end surface of the small diameter portion 112 (including the seal member 92), the rear end surface of the small diameter portion 113 (the seal member 93). And the inner peripheral surface of the main cylinder 11 between the small-diameter portions 112 and 113 (in front of the intermediate wall 111) defines a “first master chamber 1D” filled with brake fluid. Further, the brake fluid is caused by the inner bottom surface 111 d of the main cylinder 11, the front end surface of the second output piston 15, the inner surface of the second output piston 15, the front end surface of the small diameter portion 113 (including the seal member 94), and the inner peripheral surface of the main cylinder 11. The filled “second master room 1E” is partitioned.

  The first output piston 14 is driven by the hydraulic pressure in the servo chamber 1A to change the volume of the “first master chamber 1D”. Further, the second output piston 15 is driven by the hydraulic pressure in the “first master chamber 1D” (the hydraulic pressure in the servo chamber 1A) to change the volume of the “second master chamber 1E”.

  The master cylinder device 1 is formed with ports 11a to 11i that communicate between the inside and the outside. The port 11 a is formed behind the intermediate wall 111 in the main cylinder 11. The port 11b is formed at the same position in the axial direction as the port 11a so as to face the port 11a. The port 11 a and the port 11 b communicate with each other via a space between the inner peripheral surface of the main cylinder 11 and the outer peripheral surface of the cylinder part 121. The port 11a is connected to the pipe 161. The port 11b is connected to the reservoir 171. That is, the port 11a communicates with the reservoir 171.

  Further, the port 11 b communicates with the separation chamber 1 </ b> B through a passage 18 formed in the cylinder portion 121 and the input piston 13. The passage 18 is divided when the input piston 13 moves forward. That is, when the input piston 13 moves forward, the separation chamber 1B and the reservoir 171 are separated.

  The port 11c is formed in front of the port 11a and connects the separation chamber 1B and the pipe 162. The port 11d is formed in front of the port 11c and connects the servo chamber 1A and the pipe 163. The port 11e is formed in front of the port 11d and communicates the reaction force pressure chamber 1C and the pipe 164.

  The port 11f is formed between the seal members 91 and 92 of the small-diameter portion 112, and communicates the reservoir 172 and the inside of the main cylinder 11. The port 11 f communicates with the first master chamber 1 </ b> D via a passage 144 formed in the first output piston 14. The passage 144 is formed slightly behind the seal member 92 so that the port 11f and the first master chamber 1D are separated when the first output piston 14 advances.

  The port 11g is formed in front of the port 11f and communicates the first master chamber 1D and the pipe 51. The port 11 h is formed between the seal members 93 and 94 of the small diameter portion 113 and communicates the reservoir 173 and the inside of the main cylinder 11. The port 11h communicates with the second master chamber 1E via a passage 154 formed in the second output piston 15. The passage 154 is formed slightly behind the seal member 94 so that the port 11h and the second master chamber 1E are separated when the second output piston 15 moves forward. The port 11i is formed in front of the port 11h and communicates the second master chamber 1E and the pipe 52.

  In the master cylinder device 1, a seal member (black circle portion in the drawing) such as an O-ring is appropriately disposed. The seal members 91 and 92 are disposed in the small diameter portion 112 and are in liquid-tight contact with the outer peripheral surface of the first output piston 14. Similarly, the seal members 93 and 94 are disposed in the small-diameter portion 113 and are in liquid-tight contact with the outer peripheral surface of the second output piston 15. A seal member is also disposed between the input piston 13 and the cylinder part 121.

  The stroke sensor 72 is a sensor that is disposed in the vicinity of the brake pedal 10 and detects an operation amount (depression amount) of the brake pedal 10 and transmits a detection result to the brake ECU 6. Since the brake pedal 10 is connected to the rear end of the input piston 13, the stroke sensor 72 detects the amount of movement (position in the axial direction) of the input piston 13 in the axial direction as a result.

(Reaction force generator 2)
The reaction force generator 2 includes a stroke simulator 21. The stroke simulator 21 generates a reaction force against the pedal force acting on the brake pedal 10 by generating a reaction force pressure in the separation chamber 1B and the reaction force pressure chamber 1C according to the operation of the brake pedal 10, and normally This device reproduces the operational feeling (feeling of pedaling force) of the brake device. In general, the stroke simulator 21 is configured such that a piston 212 is slidably fitted to a cylinder 211 and a reaction force chamber 214 is formed on the front side of the piston 212 urged forward by a compression spring 213. Yes. The stroke simulator 21 is connected to the reaction force pressure chamber 1C via the pipe 164 and the port 11e, and is connected to the separation chamber valve 22 and the reaction force chamber valve 3 via the pipe 164.

(Separation chamber valve 22)
The separation chamber valve 22 is a normally closed electromagnetic valve, and its opening / closing and opening degree are controlled by the brake ECU 6. The separation chamber valve 22 is connected to the pipe 164 and the pipe 162, and connects / disconnects both pipes 162, 164. The separation chamber valve 22 is a valve for connecting / disconnecting the separation chamber 1B and the reaction force pressure chamber 1C. In other words, the separation chamber valve 22 opens or closes the pipes 162 and 164 connecting the separation chamber 1B and the stroke simulator 21, opens the separation chamber 1B by opening the valve, and closes the separation chamber 1B by closing the valve. It is.

  The pressure sensor 73 is a sensor that mainly detects the fluid pressure (reaction force pressure) of the separation chamber 1 </ b> B and the reaction force pressure chamber 1 </ b> C, and is connected to the pipe 164. The pressure sensor 73 detects the fluid pressure in the separation chamber 1B and the reaction force pressure chamber 1C when the separation chamber valve 22 is in the open state, and the fluid pressure in the reaction force pressure chamber 1C when the separation chamber valve 22 is in the closed state. To detect.

(Reaction force chamber valve 3)
The reaction force chamber valve 3 is a normally open type electromagnetic valve, and opening and closing of the reaction chamber valve 3 is controlled by the brake ECU 6. The reaction force chamber valve 3 is connected to the pipe 164 and the pipe 161 and connects / disconnects both pipes 161 and 164. The reaction force chamber valve 3 is a valve that opens or closes the flow path between the separation chamber 1 </ b> B and the reaction force pressure chamber 1 </ b> C and the reservoir 171.

(Control of separation chamber valve 22 and reaction force chamber valve 3)
Here, control of the reaction force chamber valve 3 and the separation chamber valve 22 by the brake ECU 6 during the brake operation will be described. When the brake pedal 10 is depressed, the input piston 13 moves forward, the passage 18 is divided, and the reservoir 171 and the separation chamber 1B are shut off. In the “linear mode” to be described later, the reaction force chamber valve 3 is in a closed state and the separation chamber valve 22 is in an open state. Since the reaction force chamber valve 3 is closed, the reaction force pressure chamber 1C and the reservoir 171 are shut off. Since the separation chamber valve 22 is in the open state, the separation chamber 1B and the reaction force pressure chamber 1C communicate with each other. That is, when the input piston 13 moves forward and the reaction force chamber valve 3 is closed, the separation chamber 1B and the reaction force pressure chamber 1C are disconnected from the reservoir 171. In response to the movement of the first output piston 14, the same amount of liquid flows into and out of the reaction force pressure chamber 1 </ b> C from the separation chamber 1 </ b> B by the protrusion 142. Then, the stroke simulator 21 generates reaction force pressure corresponding to the stroke amount in the separation chamber 1B and the reaction force pressure chamber 1C. That is, the stroke simulator 21 applies a reaction force pressure corresponding to the stroke amount of the input piston 13 (the operation amount of the brake pedal 10) to the brake pedal 10 connected to the input piston 13.

  The area of the tip surface of the protrusion 142 is the same as the area of the surface where the servo pressure receiving portion 141a faces the reaction force pressure chamber 1C. For this reason, when the reaction force chamber valve 3 is closed and the separation chamber valve 22 is open, the internal pressures of the separation chamber 1B and the reaction force pressure chamber 1C are the same. Is the same as the force acting on the front surface of the projecting portion 142 and the force acting on the surface of the reaction force pressure chamber 1C facing the reaction force pressure chamber 1C. Even if the internal pressure of 1B and reaction force pressure chamber 1C becomes high, the first output piston 14 does not move. Moreover, since the area of the front end surface of the protrusion 142 and the area of the surface where the servo pressure receiving portion 141a faces the reaction force pressure chamber 1C are the same, even if the first output piston 14 moves, the stroke simulator 21 Since the amount of fluid fluid that flows into the inside does not change, the reaction force pressure in the separation chamber 1B does not change, and the reaction force transmitted to the brake pedal 10 does not change.

(Servo pressure generator 4)
The servo pressure generator 4 mainly includes a pressure reducing valve 41, a pressure increasing valve 42, a pressure supply unit 43, and a regulator 44. The pressure reducing valve 41 is a normally open electromagnetic valve, and the fluid pressure in the flow path downstream of the pressure reducing valve 41 is controlled by the brake ECU 6 controlling the opening area of the flow path. One side of the pressure reducing valve 41 is connected to the pipe 161 via the pipe 411, and the other side of the pressure reducing valve 41 is connected to the pipe 413. That is, one of the pressure reducing valves 41 communicates with the reservoir 171 through the pipes 411 and 161 and the ports 11a and 11b. The pressure increasing valve 42 is a normally closed electromagnetic valve, and the fluid pressure in the flow path downstream of the pressure increasing valve 42 is controlled by the brake ECU 6 controlling the opening area of the flow path. One of the pressure increasing valves 42 is connected to the pipe 421, and the other of the pressure increasing valves 42 is connected to the pipe 422.

  The pressure supply unit 43 is means for providing high-pressure brake fluid to the regulator 44 based on an instruction from the brake ECU 6. The pressure supply unit 43 mainly includes an accumulator 431, a hydraulic pump 432, a motor 433, and a reservoir 434.

  The accumulator 431 accumulates the hydraulic pressure generated by the hydraulic pump 432. The accumulator 431 is connected to the regulator 44, the pressure sensor 75, and the hydraulic pump 432 by a pipe 431a. The hydraulic pump 432 is connected to the motor 433 and the reservoir 434. The hydraulic pump 432 supplies the brake fluid accumulated in the reservoir 434 to the accumulator 431 when the motor 433 is driven. The pressure sensor 75 detects the pressure of the accumulator 431, and the value is a value that correlates with the consumption amount of brake fluid accumulated in the accumulator 431. Other examples of the brake fluid consumption correlation value include a servo pressure that is increased by using the brake fluid of the accumulator 431, or a reaction force pressure that increases as the servo pressure increases.

  When the pressure sensor 75 detects that the accumulator pressure has dropped below a predetermined value, the motor 433 is driven based on the control signal from the brake ECU 6, and the hydraulic pump 432 supplies brake fluid to the accumulator 431. Pressure energy is supplied to the accumulator 431.

  As shown in FIG. 3, the regulator 44 is obtained by adding a sub-piston 446 mainly to a general regulator. That is, the regulator 44 mainly includes a cylinder 441, a ball valve 442, an urging portion 443, a valve seat portion 444, a control piston 445, and a sub piston 446.

  The cylinder 441 includes a substantially bottomed cylindrical cylinder case 441a having a bottom surface on one side (right side in the drawing) and a lid member 441b that closes an opening (left side in the drawing) of the cylinder case 441a. In the drawing, the lid member (441b) is formed in a U-shaped cross section. However, in this embodiment, the lid member 441b is formed in a columnar shape, and a portion blocking the opening of the cylinder case 441a is the lid member 441b. Will be described. The cylinder case 441a is formed with a plurality of ports 4a to 4h for communicating the inside and the outside.

  The port 4a is connected to the pipe 431a. The port 4b is connected to the pipe 422. The port 4c is connected to the pipe 163. The port 4d is connected to the pipe 161 via the pipe 411. The port 4 e is connected to a pipe 424 that leads to the pipe 422 through a relief valve 423. The port 4f is connected to the pipe 413. The port 4g is connected to the pipe 421. The port 4 h is connected to a pipe 511 branched from the pipe 51.

  The ball valve 442 is a valve having a ball shape at the tip, and is arranged on the bottom surface side of the cylinder case 441a (hereinafter also referred to as the cylinder bottom surface side) inside the cylinder 441 so as to be slidable in the longitudinal direction of the cylinder case 441a. It is installed. The urging portion 443 is a spring member that urges the ball valve 442 toward the opening side of the cylinder case 441a (hereinafter also referred to as the cylinder opening side), and is installed on the bottom surface of the cylinder case 441a. The valve seat portion 444 is a wall member provided on the inner peripheral surface of the cylinder case 441a, and partitions the cylinder opening side and the cylinder bottom surface side. A through passage 444 a is formed in the center of the valve seat portion 444 to communicate the partitioned cylinder opening side and cylinder bottom side. A valve seat surface 444b, which is a frustoconical surface with which the ball valve 442 abuts, is formed in the opening on the cylinder bottom surface side of the through passage 444a. The ball valve 442 urged against the valve seat surface 444b comes into contact with the ball valve 442 so that the through passage 444a is closed.

  A space defined by the ball valve 442, the urging portion 443, the valve seat portion 444, and the inner peripheral surface of the cylinder case 441a on the cylinder bottom surface side is defined as a first chamber 4A. The first chamber 4A is filled with brake fluid, connected to the pipe 431a via the port 4a, and connected to the pipe 422 via the port 4b.

  The control piston 445 includes a substantially columnar main body 445a and a substantially cylindrical protrusion 445b having a smaller diameter than the main body 445a. In the cylinder 441, the main body 445a is disposed on the cylinder opening side of the valve seat 444 so as to be slidable in the axial direction in a coaxial and liquid-tight manner. The main body 445a is biased toward the cylinder opening by a biasing member (not shown). A passage 445c extending in the circumferential direction (vertical direction in the drawing) having both ends opened to the peripheral surface of the main body 445a is formed at the approximate center of the main body 445a in the cylinder axis direction. A part of the inner peripheral surface of the cylinder 441 corresponding to the position of the opening of the passage 445c is formed with a port 4d, is recessed in a concave shape, and forms a third chamber 4C with the main body 445a.

  The protruding portion 445b protrudes from the center of the cylinder bottom end surface of the main body portion 445a toward the cylinder bottom surface. The diameter of the protruding portion 445 b is smaller than the through passage 444 a of the valve seat portion 444. The protruding portion 445b is disposed on the same axis as the through passage 444a. The tip of the protrusion 445b is spaced from the ball valve 442 toward the cylinder opening by a predetermined distance. The protruding portion 445b is formed with a passage 445d that extends in the cylinder axial direction and opens at the center of the cylinder bottom end surface of the protruding portion 445b. The passage 445d extends into the main body 445a and is connected to the passage 445c.

  A space defined by the cylinder bottom end surface of the main body 445a, the outer surface of the protruding portion 445b, the inner peripheral surface of the cylinder 441, the valve seat 444, and the ball valve 442 is defined as a second chamber 4B. The second chamber 4B communicates with the ports 4d and 4e via the passages 445c and 445d and the third chamber 4C.

  The sub-piston 446 includes a sub main body 446a, a first protrusion 446b, and a second protrusion 446c. The sub main body 446a is formed in a substantially cylindrical shape. In the cylinder 441, the sub main body portion 446a is disposed on the cylinder opening side of the main body portion 445a so as to be slidable coaxially and liquid-tightly in the axial direction.

  The first projecting portion 446b has a substantially cylindrical shape with a smaller diameter than the sub main body portion 446a, and projects from the center of the end surface of the sub main body portion 446a on the cylinder bottom surface side. The first protrusion 446b is in contact with the cylinder opening side end surface of the main body 445a. The 2nd protrusion part 446c is the same shape as the 1st protrusion part 446b, and protrudes from the end surface center by the side of the cylinder opening of the sub main-body part 446a. The second protrusion 446c is in contact with the lid member 441b.

  A space defined by the end surface on the cylinder bottom surface side of the sub main body portion 446a, the outer surface of the first projecting portion 446b, the end surface on the cylinder opening side of the control piston 445, and the inner peripheral surface of the cylinder 441 is defined as a pressure control chamber 4D. The pressure control chamber 4D communicates with the pressure reducing valve 41 via the port 4f and the pipe 413, and communicates with the pressure increasing valve 42 via the port 4g and the pipe 421.

  On the other hand, a space defined by the end surface of the sub main body 446a on the cylinder opening side, the outer surface of the second protrusion 446c, the lid member 441b, and the inner peripheral surface of the cylinder 441 is defined as a fourth chamber 4E. The fourth chamber 4E communicates with the port 11g via the port 4h and the pipes 511 and 51. Each chamber 4A-4E is filled with brake fluid. As shown in FIG. 2, the pressure sensor 74 is a sensor for detecting the hydraulic pressure (servo pressure) in the servo chamber 1 </ b> A, and is connected to the pipe 163.

(Brake piping)
Wheel cylinders WCfl, WCfr, WCrl, and WCrr are communicated with the first master chamber 1D and the second master chamber 1E that generate the master cylinder pressure via pipes 51 and 52 and a pressure adjusting device 53, respectively. Specifically, a well-known ABS (Antilock Break System) 53 is connected to the port 11g of the first master chamber 1D and the port 11i of the second master chamber 1E via pipes 51 and 52, respectively. The pressure regulator 53 is connected to wheel cylinders WCfl, WCfr, WCrl, WCrr for operating the friction brake devices Bfl, Bfr, Brl, Brr for braking the wheels Wfl, Wfr, Wrl, Wrr.

  Here, the configuration of one of the four wheels (5FR) of the pressure regulating device 53 will be described, and the other configurations are the same, and the description thereof will be omitted. The pressure adjusting device 53 includes a holding valve 531, a pressure reducing valve 532, a reservoir 533, a pump 534, and a motor 535. The holding valve 531 is a normally-open electromagnetic valve, and opening / closing thereof is controlled by the brake ECU 6. One of the holding valves 531 is connected to the pipe 52 and the other is connected to the wheel cylinder WCfr and the pressure reducing valve 532. That is, the holding valve 531 is an input valve of the pressure regulator 53.

  The pressure reducing valve 532 is a normally closed electromagnetic valve, and opening / closing thereof is controlled by the brake ECU 6. One of the pressure reducing valves 532 is connected to the wheel cylinder WCfr and the holding valve 531, and the other is connected to the reservoir 533. When the pressure reducing valve 532 is opened, the wheel cylinder WCfr and the reservoir 533 communicate with each other.

  The reservoir 533 stores brake fluid and is connected to the pipe 52 via a pressure reducing valve 532 and a pump 534. The pump 534 is arranged so that the suction port is connected to the reservoir 533 and the discharge port is connected to the pipe 52 via the check valve z. Here, the check valve z allows the flow from the pump 534 to the pipe 52 (second master chamber 1E) and restricts the flow in the reverse direction. The pump 534 is driven by the operation of a motor 535 according to a command from the brake ECU 6. In the ABS control decompression mode, the pump 534 sucks the brake fluid in the wheel cylinder WCfr or the brake fluid stored in the reservoir 533 and returns it to the second master chamber 1E. Note that a damper (not shown) is disposed upstream of the pump 534 in order to relieve pulsation of the brake fluid discharged from the pump 534.

  In the pressure regulating device 53 configured as described above, the brake ECU 6 controls the opening / closing of the solenoid valves 531 and 532 based on the master cylinder pressure, the state of the wheel speed, and the longitudinal acceleration, and controls the motor 535 as necessary. The ABS control (anti-lock brake control) and the skid prevention control for adjusting the brake hydraulic pressure applied to the wheel cylinder WCfr, that is, the braking force applied to the wheel Wfr, are executed. The pressure adjusting device 53 adjusts the amount and timing of the brake fluid supplied from the master cylinder device 1 based on an instruction from the brake ECU 6 (that is, adjusts the master pressure) to adjust the wheel cylinders WCfl, WCfr, It is a device that supplies WCrl and WCrr.

  In the “linear mode” to be described later, the hydraulic pressure sent from the accumulator 431 of the servo pressure generating device 4 is controlled by the pressure increasing valve 42 and the pressure reducing valve 41 to generate the servo pressure in the servo chamber 1A. 14 and the second output piston 15 move forward to pressurize the first master chamber 1D and the second master chamber 1E. The hydraulic pressure in the first master chamber 1D and the second master chamber 1E is supplied as master cylinder pressure from the ports 11g and 11i to the wheel cylinders WCfl, WCfr, WCrl and WCrr via the pipes 51 and 52 and the pressure regulator 53, A hydraulic braking force is applied to the wheels Wfl, Wfr, Wrl, Wrr.

(Brake ECU 6)
The brake ECU 6 is an electronic control unit and includes a microcomputer (not shown). The microcomputer includes an input / output interface, a CPU, a RAM, a ROM, a nonvolatile memory, and the like connected to each other via a bus. “Storage” is provided. The CPU executes a program corresponding to the flowchart shown in FIG. The RAM temporarily stores variables necessary for execution of the program, and the “storage unit” stores the program.

  The brake ECU 6 communicates with various sensors 72 to 75 and controls the electromagnetic valves 22, 3, 41, 42, 531, 532, motors 433, 535, and the like. The brake ECU 6 is connected to the hybrid ECU 9 (shown in FIG. 1) so as to communicate with each other, and performs cooperative control (regenerative cooperative control) of the regenerative brake device A and the friction brake unit B. The brake ECU 6 switches between the “linear mode” and the “fade mode”.

  As will be described later in detail, the “linear mode” is normal brake control, and the pressure reducing valve 41 and the pressure increasing valve are opened in the state where the separation chamber valve 22 is opened and the reaction force chamber valve 3 is closed. 42 is a mode for controlling the “servo pressure” of the servo chamber 1A by controlling 42. In this “linear mode”, the brake ECU 6 calculates the “required braking force” of the driver from the amount of operation of the brake pedal 10 (the amount of movement of the input piston 13) detected by the stroke sensor 72. Then, the brake ECU 6 calculates a “target regenerative braking force” from the “request braking force” of the driver, and outputs the “target regenerative braking force” to the hybrid ECU 9. The hybrid ECU 9 calculates an “executed regenerative braking force” based on the “target regenerative braking force”, and outputs the “executed regenerative braking force” to the brake ECU 6. The brake ECU 6 calculates the “target friction braking force” by subtracting the “execution regenerative braking force” from the “request braking force”. Then, the brake ECU 6 controls the “servo pressure” of the servo chamber 1A by controlling the pressure reducing valve 41 and the pressure increasing valve 42 based on the calculated “target friction braking force”, so that the friction in the friction brake unit B is controlled. Control is performed so that the braking force becomes the “target friction braking force”.

  In the “fade mode”, as will be described in detail later, when the fade condition is satisfied and the friction brake devices Bfl, Bfr, Brl, Brr are in a fade state or a state where the brake is likely to fade, the separation chamber valve 22 and the reaction force The chamber valve 3 is deenergized, the separation chamber 1B is liquid-tight, and the operating force of the brake pedal 10 by the driver is directly applied to the first output piston 14 via the brake fluid in the separation chamber 1B. Mode.

(Linear mode)
When the brake pedal 10 is not depressed, the state as described above, that is, the state where the ball valve 442 blocks the through passage 444a of the valve seat portion 444 is obtained. Further, the pressure reducing valve 41 is in an open state, and the pressure increasing valve 42 is in a closed state. That is, the first chamber 4A and the second chamber 4B are isolated.

  The second chamber 4B communicates with the servo chamber 1A via the pipe 163 and is maintained at the same fluid pressure. The second chamber 4B communicates with the third chamber 4C through passages 445c and 445d of the control piston 445. Therefore, the second chamber 4B and the third chamber 4C communicate with the reservoir 171 through the pipes 414 and 161. One of the pressure control chambers 4 </ b> D is closed by the pressure increasing valve 42, and the other is communicated with the reservoir 171 through the pressure reducing valve 41. The pressure control chamber 4D and the second chamber 4B are kept at the same fluid pressure. The fourth chamber 4E communicates with the first master chamber 1D via the pipes 511 and 51 and is maintained at the same fluid pressure.

  From this state, when the brake pedal 10 is depressed, after a predetermined regeneration period, the brake ECU 6 increases the pressure reducing valve 41 and the increase valve 41 so that the “target friction braking force” is generated based on the information from the stroke sensor 72. The pressure valve 42 is controlled. That is, the brake ECU 6 controls the pressure reducing valve 41 in the closing direction and the pressure increasing valve 42 in the opening direction.

  When the pressure increasing valve 42 is opened, the accumulator 431 and the pressure control chamber 4D communicate with each other. By closing the pressure reducing valve 41, the pressure control chamber 4D and the reservoir 171 are shut off. The hydraulic pressure (pilot pressure) in the pressure control chamber 4 </ b> D can be increased by the high-pressure brake fluid supplied from the accumulator 431. When the hydraulic pressure in the pressure control chamber 4D increases, the control piston 445 slides toward the cylinder bottom side. When the tip of the protrusion 445 b of the control piston 445 comes into contact with the ball valve 442, the passage 445 d is closed by the ball valve 442. As a result, the second chamber 4B is blocked from the reservoir 171.

  Further, when the control piston 445 slides toward the cylinder bottom surface side, the ball valve 442 moves by being pushed toward the cylinder bottom surface side by the protruding portion 445b and is separated from the valve seat surface 444b. As a result, the second chamber 4B communicates with the first chamber 4A via the through passage 444a of the valve seat portion 444. Since the high pressure brake fluid is supplied from the accumulator 431 to the first chamber 4A, the fluid pressure in the second chamber 4B increases due to the communication. When the force corresponding to the second chamber 4B acting on the control piston 445 becomes larger than the force corresponding to the pilot pressure acting on the control piston 445 as a result of the increase in the hydraulic pressure in the second chamber 4B, the control piston 445 The second chamber 4B is blocked from the first chamber 4A by sliding toward the opening side. By such an operation, the hydraulic pressure in the second chamber 4B becomes a hydraulic pressure corresponding to the pilot pressure. The brake ECU 6 controls the pressure reducing valve 41 and the pressure increasing valve 42 such that the pilot pressure in the pressure control chamber 4D increases as the “target friction braking force” increases. That is, as the “target friction braking force” increases, the pilot pressure increases and the servo pressure also increases.

  As the pressure in the second chamber 4B increases, the hydraulic pressure in the servo chamber 1A communicating therewith also increases. As the hydraulic pressure in the servo chamber 1A increases, the first output piston 14 moves forward, and the hydraulic pressure in the first master chamber 1D increases. And the 2nd output piston 15 also advances, and the hydraulic pressure of the 2nd master chamber 1E rises. As the hydraulic pressure in the first master chamber 1D increases, high-pressure brake fluid is supplied to the pressure adjusting device 53 and the fourth chamber 4E described later. Although the hydraulic pressure in the fourth chamber 4E rises, the sub-piston 446 does not move because the hydraulic pressure in the pressure control chamber 4D similarly rises. Thus, high-pressure (master cylinder pressure) brake fluid is supplied to the wheel cylinders WCfl, WCfr, WCrl, WCrr, and the friction brake devices Bfl, Bfr, Brl, Brr are operated to brake the vehicle. The force for moving the first output piston 14 forward in the “linear mode” corresponds to a force corresponding to the servo pressure.

  When releasing the brake operation, on the contrary, the pressure reducing valve 41 is opened, the pressure increasing valve 42 is closed, and the reservoir 171 communicates with the pressure control chamber 4D. As a result, the control piston 445 moves backward and returns to the state before the brake pedal 10 is depressed.

(Fade mode)
In the “fade mode”, the separation chamber valve 22 and the reaction force chamber valve 3 are not energized (controlled), the separation chamber valve 22 is closed, the reaction force chamber valve 3 is open, and the brake pedal 10 is Even after being stepped on, the non-energized state (uncontrolled state) is maintained. This will be described in detail below.

(Fade mode control processing)
The “fade mode control process” will be described below using the flowchart shown in FIG. When the vehicle is ready to start and the brake ECU 6 is activated, the program proceeds to S11.

  In S11, the brake ECU 6 determines whether at least one of the friction brake devices Bfl, Bfr, Brl, and Brr is in a fade state and the fade condition is satisfied. In the present embodiment, the fade state includes not only the state in which at least one of the friction brake devices Bfl, Bfr, Brl, and Brr is actually fading, but also a state that is likely to fade.

  Various methods can be used as a method for determining whether or not the fade condition is satisfied. For example, as disclosed in Japanese Patent Application Laid-Open No. 2009-190475, the brake ECU 6 determines the frictional force generated between the brake discs DRfl, DRfr, DRrl, DRrr and the brake pads and the brake discs DRfl, DRfr, DRrl, DRrr. The work amount is calculated from the rotation amount, and the pad temperature is estimated from the work amount and the brake pad cooling model. Based on the estimated pad temperature, for example, when the pad temperature is equal to or higher than a predetermined value, it is determined that the fade condition of the friction brake devices Bfl, Bfr, Brl, and Brr is satisfied. Note that the rotation amounts of the brake discs DRfl, DRfr, DRrl, DRrr are detected by wheel speed sensors Sfl, Sfr, Srl, Srr.

  Alternatively, as disclosed in JP-A-2002-193090, the vehicle deceleration calculated from the wheel speeds detected by the wheel speed sensors Sfl, Sfr, Srl, Srr and the brake pedal 10 detected by the brake pedal sensor The fade conditions of the friction brake devices Bfl, Bfr, Brl, and Brr may be determined based on the operation force and the operation amount. If the brake ECU 6 determines that at least one of the friction brake devices Bfl, Bfr, Brl, and Brr is in a fade state and the fade condition is satisfied (S11: YES), the program proceeds to S12, and the fade condition is If it is determined that it has not been established (S11: NO), the “precharge end processing request” (shown in FIG. 5) is turned ON, and the program proceeds to S50.

  In S12, when the brake ECU 6 determines that the vehicle speed V is equal to or higher than a specified speed (for example, 5 km / h) and the accelerator pedal 20 is not depressed (S12: YES), the program proceeds to S13. When it is determined that the vehicle speed V is lower than the specified speed, or when it is determined that the accelerator pedal 20 is depressed (S12: ON), the “precharge end processing request” (shown in FIG. 5) is set to ON. The program proceeds to S50. The brake ECU 6 calculates the vehicle speed V based on detection signals from the wheel speed sensors Sfl, Sfr, Srl, Srr, and acquires the opening information of the accelerator pedal 20 from the hybrid ECU 9.

  In S13, when the brake ECU 6 determines that the “precharge control” described later has been completed (S13: YES), the program proceeds to S31 and determines that the “precharge control” has not been completed. In this case (S13: NO), the “precharge execution request” (shown in FIG. 5) is turned ON, and the program proceeds to S21.

  In S21, the brake ECU 6 executes “precharge control” for controlling the pressure reducing valve 41 and the pressure increasing valve 42 so that “precharge pressure” is generated in the servo chamber 1A. That is, the brake ECU 6 controls the pressure reducing valve 41 in the closing direction and the pressure increasing valve 42 in the opening direction. When the “precharge pressure” is generated in the servo chamber 1A ((1) in FIG. 6), the first output piston 14 and the second output piston 15 move forward by a predetermined distance with respect to the input piston 13, and the brake fluid is discharged. It is supplied from the master chambers 1D and 1E to the wheel cylinders WCfl, WCfr, WCrl and WCrr.

  The purpose of performing the “precharge control” is that when the friction brake devices Bfl, Bfr, Brl, and Brr are in a fade state, the first output piston 14 and the second output piston 15 are connected to the input piston 13 in advance. This is because the brake fluid is moved forward to supply brake fluid to the wheel cylinders WCfl, WCfr, WCrl, WCrr, and a larger friction braking force is generated in the friction brake devices Bfl, Bfr, Brl, Brr. Here, the “precharge pressure” is obtained by operating the brake pedal 10 within a range where the required friction braking force is allowed when the friction brake devices Bfl, Bfr, Brl, Brr are in a fade state. Is set to The brake ECU 6 stores the generated “precharge pressure”.

  By this “precharge control”, no friction braking force is generated in the friction brake devices Bfl, Bfr, Brl, Brr. Alternatively, even if a friction braking force is generated, the friction braking force is minimal. When S21 ends, the program returns to S11.

  In S31, when the brake ECU 6 determines that the separation chamber valve 22 is closed and the reaction force chamber valve 3 is opened (S31: YES), the program proceeds to S41 and the separation chamber valve 22 is operated. Is determined to be open, or when it is determined that the reaction force chamber valve 3 is closed (S31: NO), the program proceeds to S32.

  In S32, the brake ECU 6 closes the separation chamber valve 22, and advances the program to S33. If the brake ECU 6 determines in S33 that the predetermined time has elapsed (S33: YES), the program proceeds to S34, and if it is determined that the predetermined time has not elapsed (S33: NO), Repeat the process.

In S34, the brake ECU 6 opens the reaction chamber valve 3 and advances the program to S35.
In S35, the brake ECU 6 changes the control mode of the friction brake unit B to “fade mode” and returns the program to S11.

  In S41, when the brake ECU 6 determines that the servo pressure in the servo chamber 1A is below the predetermined limit value shown in FIG. 6 based on the detection signal from the pressure sensor 74 (S141: YES), the program If it is determined that the servo pressure in the servo chamber 1A exceeds the predetermined limit value shown in FIG. 6 (S41: NO), the program proceeds to S43.

  In S41, the brake ECU 6 performs “servo pressure linear control”. Specifically, as described above in the “linear control”, the brake ECU 6 controls the pressure reducing valve 41 and the pressure increasing valve 42 based on a detection signal from the stroke sensor 72 when the brake pedal 10 is depressed. . That is, as shown in FIG. 6, the brake ECU 6 increases the pressure increasing valve 42 so that the pilot pressure increases as the movement amount of the input piston 13 (the operation amount of the brake pedal 10) detected by the stroke sensor 72 increases. Then, the servo pressure is controlled by controlling the pressure reducing valve 41.

  In “servo pressure linear control”, since the separation chamber valve 22 is closed and the separation chamber 1B is in a liquid-tight state, the first output piston 14 is connected to the first output piston 14 via the brake fluid in the separation chamber 1B. An operating force acting on the input piston 13 by the driver also acts. Accordingly, in addition to the servo pressure, the operating force acting on the input piston 13 also acts on the first output piston 14. Due to the servo pressure and the operating force acting on the first output piston 14, the first output piston 14 moves forward, and the hydraulic pressure in the first master chamber 1D increases. And the 2nd output piston 15 also advances, and the hydraulic pressure of the 2nd master chamber 1E rises. As a result, high-pressure (master cylinder pressure) brake fluid is supplied from the first master chamber 1D and the second master chamber 1E to the wheel cylinders WCfl, WCfr, WCrl, WCrr via the pressure regulator 53, and the friction brake devices Bfl, A friction braking force is applied to the vehicle by Bfr, Brl, and Brr.

  Note that as the hydraulic pressure in the first master chamber 1D increases, high-pressure brake fluid is supplied to the pressure regulator 53 and the fourth chamber 4E, which will be described later. And although the hydraulic pressure of the 4th chamber 4E rises, since the hydraulic pressure of the pressure control chamber 4D is also rising similarly, the sub piston 446 does not move. When S41 ends, the program returns to S11.

  In S43, the brake ECU 6 executes “servo pressure limiting control”. Specifically, as shown in FIG. 6, the brake ECU 6 determines that the pressure reducing valve 41 and the pressure increasing valve prevent the servo pressure from exceeding the limit value regardless of the operation amount of the brake pedal 10 detected by the stroke sensor 72. 42 is controlled to control the pilot pressure. Thus, in the “servo pressure limit control”, the increase in the servo pressure with respect to the increase in the operation amount of the brake pedal 10 is limited. In the present embodiment, in the “servo pressure limiting control”, the pressure reducing valve 41 and the pressure increasing valve 42 are closed.

  In the “servo pressure limit control”, since the separation chamber valve 22 is closed and the separation chamber 1B is in a liquid-tight state, the first output piston 14 acts on the input piston 13 in addition to the servo pressure. The operating force to act also acts. However, the servo pressure acting on the first output piston 14 is limited. As the first output piston 14 advances, the first output piston 14 advances due to the servo pressure and the operating force acting on the first output piston 14, and the hydraulic pressures in the first master chamber 1D and the second master chamber 1E are increased. To rise. Then, the hydraulic pressure in the fourth chamber 4E also increases due to the increase in the hydraulic pressure in the first master chamber 1D. As a result, high-pressure (master cylinder pressure) brake fluid is supplied from the first master chamber 1D and the second master chamber 1E to the wheel cylinders WCfl, WCfr, WCrl, WCrr via the pressure regulator 53, and the friction brake devices Bfl, A friction braking force is applied to the vehicle by Bfr, Brl, and Brr.

  Note that as the hydraulic pressure in the first master chamber 1D increases, high-pressure brake fluid is supplied to the pressure regulator 53 and the fourth chamber 4E, which will be described later. Then, although the hydraulic pressure in the fourth chamber 4E increases, the sub-piston 446 does not move when the hydraulic pressure in the fourth chamber 4E does not exceed the hydraulic pressure in the pressure control chamber 4D. On the other hand, when the hydraulic pressure in the fourth chamber 4E exceeds the hydraulic pressure in the pressure control chamber 4D, the sub piston 446 slides toward the cylinder bottom surface. At the same time, the control piston 445 is pushed by the first protrusion 446b and slides toward the cylinder bottom surface. As a result, the protruding portion 445b contacts the ball valve 442, and the ball valve 442 is pushed toward the cylinder bottom surface and moves. That is, the first chamber 4A and the second chamber 4B communicate with each other, the servo chamber 1A and the reservoir 171 are shut off, high-pressure brake fluid from the accumulator 431 is supplied to the servo chamber 1A, and the servo pressure acting on the servo chamber 1A increases. As a result, the master pressure also increases. When S43 ends, the program returns to S11.

  In this way, in the “fade mode”, first, the master pressure is increased by “servo pressure linear control” ((1) in FIG. 7), and then “servo pressure limit control” is started to limit the servo The master pressure gradually increases due to the pressure and the operating force ((2) in FIG. 7). When the hydraulic pressure in the fourth chamber 4E exceeds the hydraulic pressure in the pressure control chamber 4D as the master pressure increases ((3) in FIG. 7), the control piston 445 moves further to the cylinder bottom side, and the servo pressure The servo pressure acting on the servo chamber 1A is increased by the generator 4, and the master pressure is increased accordingly ((4) in FIG. 7). Even if the master pressure exceeds the maximum pressure that can be generated by the servo pressure generator 4 (accumulator 431) ((6) in FIG. 7), the separation chamber 1B is liquid-tight in the “fade mode”. Therefore, the operating force of the driver input to the input piston 13 is directly transmitted to the output pistons 14 and 15 by the brake fluid in the separation chamber 1B, and the master pressure is generated exceeding the maximum pressure. ((5) in FIG. 7).

In S50, the brake ECU 6 changes the control mode of the friction brake unit B to the “linear mode”, and advances the program to S51.
In S51, the brake ECU 6 closes the reaction force chamber valve 3 (T3 in FIG. 5). When S51 ends, the program proceeds to S52.

  In S <b> 52, the brake ECU 6 calculates the “separation chamber valve opening start time” by referring to the mapping data shown in FIG. 8 based on the depression speed of the brake pedal 10 detected by the stroke sensor 72. The mapping data shown in FIG. 8 is set so that the “reaction chamber valve closing start time” becomes shorter as the depression speed of the brake pedal 10 becomes faster. Next, when the brake ECU 6 determines that the “separation chamber valve opening start time” has elapsed since the reaction chamber valve 3 started to close (S52: YES), the program proceeds to S53. If it is determined that the “separation chamber valve opening start time” has not elapsed since the reaction force chamber valve 3 started to close (S52: NO), the processing of S52 is repeated.

  In S53, the brake ECU 6 starts opening the separation chamber valve 22. The separation chamber valve 22 is controlled so that the opening speed of the separation chamber valve 22 increases as the depression speed of the brake pedal 10 increases. Specifically, the brake ECU 6 calculates the depression speed of the brake pedal 10 based on the operation amount of the brake pedal 10 detected by the stroke sensor 72, and based on the depression speed of the brake pedal 10, FIG. With reference to the mapping data shown, the current increase gradient supplied to the separation chamber valve 22 is calculated. And brake ECU6 supplies an electric current to the separation chamber valve 22 so that it may become the said current increase gradient. The mapping data shown in FIG. 9 is set so that the current increase gradient supplied to the separation chamber valve 22 increases as the depression speed of the brake pedal 10 increases. As shown in FIG. 10, depending on the “separation chamber valve opening start time”, the opening of the separation chamber valve 22 may be started in a state where the reaction chamber valve 3 is not completely closed. is there. When S53 ends, the program proceeds to S54.

  If the brake ECU 6 determines in S54 that the separation chamber valve 22 has been opened (S54: YES), the program proceeds to S55, and if it is determined that the separation chamber valve 22 has not opened (S54: (S54: NO), the process of S54 is repeated.

  In S55, the brake ECU 6 executes a “precharge end process” for starting to reduce the hydraulic pressure corresponding to the “precharge pressure” acting on the servo chamber 1A stored in S21 (T5 in FIG. 5). First, the brake ECU 6 calculates a “precharge pressure reduction gradient” based on the vehicle speed V with reference to the mapping data shown in FIG. 11A. The mapping data shown in FIG. 11A is set so that the “precharge pressure depressurization gradient” increases as the vehicle speed V increases, and when the specified speed A is reached, the “precharge pressure depressurization gradient” becomes constant. It is set to be.

  The brake ECU 6 calculates the deceleration of the vehicle based on the vehicle speed V, and calculates the “precharge pressure reduction gradient” with reference to the mapping data shown in FIG. 11B based on the deceleration. The mapping data shown in FIG. 11B is set so that the “precharge pressure depressurization gradient” increases as the deceleration increases. When the specified deceleration B is reached, the “precharge pressure depressurization gradient” becomes constant. It is set to be.

  The brake ECU 6 selects a “precharge pressure depressurization gradient” calculated by the vehicle speed V and a “precharge pressure depressurization gradient” calculated by the deceleration. Next, the brake ECU 6 determines that the hydraulic pressure corresponding to the “precharge pressure” (stored in S21) acting on the servo chamber 1A is gradually reduced by the selected “precharge pressure reduction gradient”. The pressure reducing valve 41 is controlled ((1) in FIG. 5). When S55 ends, the program returns to S11.

  When the servo pressure calculated by the stroke sensor 72 in the linear control is equal to or less than the limit value shown in FIG. 6, as described above, the hydraulic pressure in the servo chamber 1A is equal to the “precharge pressure” in S55. The pressure is reduced ((2) in FIG. 6). On the other hand, when the servo pressure calculated by the stroke sensor 72 in the linear control exceeds the limit value shown in FIG. 6, in S50 to S55, the hydraulic pressure in the servo chamber 1A is changed to the stroke sensor in the linear control. The servo pressure calculated by 72 is increased ((3) in FIG. 6).

(Description of the effect of this embodiment)
As is apparent from the above description, when it is determined that the friction brake devices Bfl, Bfr, Brl, Brr are in a fade state, the separation chamber valve 22 closes the separation chamber 1B. As a result, the separation chamber 1B becomes liquid-tight, and the brake fluid in the separation chamber 1B becomes a rigid body. Therefore, the first output piston 14 moves by the stroke amount of the input piston 13 interlocked with the brake pedal 10 (brake operation member). The volumes of the master chambers 1D and 1E change by the stroke amount. In this way, in the faded state of the friction brake devices Bfl, Bfr, Brl, Brr, the input piston 13 is prevented from moving relative to the first output piston 14, thereby reducing the operation amount of the brake pedal 10. The brake fluid can be sent out from the master chambers 1D and 1E to the wheel cylinders WCfl, WCfr, WCrl, and WCrr by a corresponding amount to ensure a desired friction braking force.

  That is, when the brake ECU 6 (fade state determination unit) determines that any one of the friction brake devices Bfl, Bfr, Brl, and Brr is in a fade state (determined as YES in S11 of FIG. 4), the brake ECU 6 Then, the separation chamber valve 22 is closed (S32) and changed to the “fade mode” (S35). As a result, the separation chamber 1B becomes liquid-tight, and the operating force of the driver input to the input piston 13 is directly transmitted to the output pistons 14 and 15 by the brake fluid in the separation chamber 1B. As shown in 5), compared to the “linear mode”, a desired master pressure can be generated regardless of the maximum hydraulic pressure generated by the accumulator 431 (pressure accumulator). For this reason, at the time of brake fade, a master pressure for obtaining a desired friction braking force can be applied to the wheel cylinders WCfl, WCfr, WCrl, WCrr, and a desired friction braking force can be obtained at the time of brake fade.

  When the brake ECU 6 (precharge control unit) determines that any of the friction brake devices Bfl, Bfr, Brl, and Brr is in a fade state (determined as YES in S11 of FIG. 4), in S21, The servo pressure generator 4 executes “precharge control” for generating “precharge pressure” in the servo chamber 1A. As a result, the output pistons 15 and 14 move forward, and the brake fluid is supplied from the master chambers 1E and 1D to the wheel cylinders WCfl, WCfr, WCrl, and WCrr ((1) in FIG. 12).

  As a result, when any of the friction brake devices Bfl, Bfr, Brl, and Brr is in a fade state, when the “precharge control” is not executed, the master chambers 1E and 1D are transferred to the wheel cylinders WCfl, WCfr, WCrl, and WCrr. More brake fluid than the supplied brake fluid can be supplied from the master cylinder device 1 to the wheel cylinders WCfl, WCfr, WCrl, WCrr. For this reason, the maximum value of the hydraulic pressure (wheel cylinder pressure) acting on the wheel cylinders WCfl, WCfr, WCrl, WCrr is increased as compared with the case where the “precharge control” is not executed ((2) in FIG. 12). In the friction brake devices Bfl, Bfr, Brl, Brr, a larger friction braking force can be generated.

  Further, since brake fluid is supplied from the master chambers 1E and 1D to the wheel cylinders WCfl, WCfr, WCrl, and WCrr in advance, the friction control in the friction brake devices Bfl, Bfr, Brl, and Brr when the brake pedal 10 is stepped on is performed. Power generation is quicker.

  Further, “precharge” is performed so that the friction braking force required when the friction brake devices Bfl, Bfr, Brl, and Brr are in a fade state can be obtained by an operation within a range where the operation of the brake pedal 10 is allowed. Since the pressure is set, the braking force required when the friction brake devices Bfl, Bfr, Brl, Brr are in a faded state is ensured by the operation within the range in which the operation of the brake pedal 10 is allowed. Can be generated.

  Also, the brake ECU 6 (precharge control unit) determines that the hydraulic pressure in the servo chamber 1A is “precharged” as the state of the friction brake devices Bfl, Bfr, Brl, Brr transitions from the fade state to the non-fade state. The “precharge end process” (S55 in FIG. 4) that is decreased by the “pressure” is executed ((1) in FIG. 5). As a result, when the friction brake devices Bfl, Bfr, Brl, and Brr are in a non-fade state, generation of excessive braking force due to the hydraulic pressure in the servo chamber 1A being increased by the “precharge pressure” is prevented. Is done.

  Further, the brake ECU 6 gradually decreases the hydraulic pressure in the servo chamber 1A by controlling the pressure increasing valve 42 and the pressure reducing valve 41 in the “precharge end process” (S55 in FIG. 4) ((1) in FIG. 5). ). Thereby, in the “precharge end process”, a sudden decrease in braking force due to a rapid decrease in the hydraulic pressure in the servo chamber 1A, that is, a sudden decrease in vehicle deceleration is alleviated. For this reason, the uncomfortable feeling felt by the driver due to the decrease in the deceleration of the vehicle is alleviated.

  The lower the vehicle speed and deceleration, the more uncomfortable the driver feels due to the decrease in vehicle deceleration in the “precharge end process”. As described above, the brake ECU 6 (decrease amount setting unit) refers to the mapping data shown in FIG. 11A based on the vehicle speed V in the “precharge end process” of S55 of FIG. With reference to the mapping data shown in FIG. 11B, the “precharge pressure reduction gradient” is set. For this reason, the amount of decrease in the hydraulic pressure in the servo chamber 1A per unit time is set to a smaller amount as the vehicle speed and deceleration are lower, and the decrease in vehicle deceleration is reduced. Is alleviated.

  Further, in the processing of S51 to S53 in FIG. 4, the brake ECU 6 performs the separation chamber after the “separation chamber valve opening start time” has elapsed from the start of the reaction chamber valve 3 closing, as shown in FIG. The valve 22 starts to open. Thereby, after the reaction force chamber valve 3 is closed or the reaction force chamber valve 3 is almost closed, the opening of the separation chamber valve 22 is started. For this reason, the separation chamber valve 22 is opened and the separation chamber 1B is opened in the state where the reaction force chamber valve 3 is opened or the reaction force chamber valve 3 is almost open. Thus, the forward sliding of the input piston 13 is prevented, and the forward movement of the tread surface of the brake pedal 10 in conjunction with the sliding of the input piston 13 is prevented. For this reason, generation | occurrence | production of the uncomfortable feeling of the driver | operator who puts his foot on the brake pedal 10 tread surface is prevented.

  When the separation chamber valve 22 is closed, the separation chamber 1B and the reaction force chamber 214 of the stroke simulator 21 are not in communication with each other, and the separation chamber 1B is in a liquid-tight state. The faster the driver is, the heavier the driver feels. Therefore, the brake ECU 6 starts opening the separation chamber valve 22 after the reaction chamber valve 3 starts closing as the depression speed of the brake pedal 10 increases in the processing of S51 to S53 in FIG. The “separation chamber valve opening start time” (shown in FIG. 10), which is the time, is shortened. Thereby, the time when the driver feels that the feeling of operation of the brake pedal 10 is heavy becomes shorter, and the uncomfortable feeling that the driver learns is alleviated.

  Further, the brake ECU 6 gradually increases the opening degree of the separation chamber valve 22 when opening the separation chamber valve 22 in S53 of FIG. Thus, the separation chamber valve 22 is suddenly opened, and the separation chamber 1B is suddenly communicated with the reaction force chamber 214 of the stroke simulator 21 to prevent a sudden decrease in the operation feeling of the brake pedal 10 felt by the driver. Thus, the driver feels uncomfortable.

  Further, the brake ECU 6 increases the current increase gradient supplied to the separation chamber valve 22 as the depression speed of the brake pedal 10 is increased in S53 of FIG. As a result, as the depression speed of the brake pedal 10 increases, the time until the separation chamber valve 22 is fully opened is shortened. Thereby, the time when the driver feels that the feeling of operation of the brake pedal 10 is heavy becomes shorter, and the uncomfortable feeling that the driver learns is alleviated.

  It should be noted that as the speed of the vehicle decreases, the driver can easily feel a sense of discomfort associated with the deceleration of the vehicle due to the execution of the “precharge control”. In the present embodiment, even if the fade condition is satisfied (determined as YES in S11 of FIG. 4), if the vehicle speed V is lower than the specified speed (determined as NO in S12), the “precharge control” is performed. Because it is not executed, the driver does not feel strongly discomfort. Further, when the vehicle is traveling at a speed lower than the specified speed, the braking force necessary for decelerating or stopping the vehicle is not large, and therefore “precharge control” is not required.

  When the accelerator pedal 20 is depressed and the vehicle is accelerating, when the “precharge control” is executed, the brake pad is applied to the brake disc DRfl, by the input of the “precharge pressure” to the servo chamber 1A. The friction brake devices Bfl, Bfr, Brl, Brr are heated by being pressed against DRfr, DRrl, DRrr, and the fade state of the friction brake devices Bfl, Bfr, Brl, Brr may be further deteriorated. In this embodiment, even if the fade condition is satisfied (determined as YES in S11 of FIG. 4), if the accelerator pedal 20 is depressed (determined as NO in S12), the “precharge control” is performed. When the “precharge control” is already executed without being executed, the “precharge end process” is executed in S55, so that the temperature increase of the friction brake devices Bfl, Bfr, Brl, Brr is prevented. .

  Further, when it is determined that any of the friction brake devices Bfl, Bfr, Brl, and Brr is in a fade state (YES in S11 of FIG. 4), the operation amount of the brake pedal 10 (brake operation member) is set. A corresponding servo pressure is generated in the servo chamber 1A. Thus, in the fade state of any one of the friction brake devices Bfl, Bfr, Brl, Brr, in addition to the driver's operating force, a force corresponding to the servo pressure is applied to the output pistons 14, 15, that is, By assisting the driver's operating force with a force corresponding to the servo pressure, a larger friction braking force can be ensured. That is, as shown in (1) of FIG. 7, the master pressure can be generated quickly in the initial state where the driver has started stepping on the brake pedal 10, and the generation of friction braking force can be prevented from being delayed. it can. Further, as shown in (1) and (2) of FIG. 7, since the servo pressure acts on the output pistons 14 and 15 at the initial stage of generation of the friction braking force, only the operating force of the driver is output pistons 14 and 15. It is possible to generate a larger friction braking force as compared with the case of acting on.

  When the brake ECU 6 (fade mode control unit) determines that the servo pressure has exceeded the limit value (shown in FIG. 6) (determined as YES in S43 of FIG. 4), the brake ECU 6 (fade mode control unit) Limit the pressure rise. Thereby, in the “fade mode”, the separation chamber 1B is closed, and the rigidity of the brake pedal 10 is reduced due to the generation of servo pressure corresponding to the operation amount of the brake pedal 10 in the servo chamber 1A. Can be suppressed. That is, if the increase of the servo pressure is not restricted in the “fade mode”, the stroke amount of the brake pedal 10 detected by the stroke sensor 72 increases when the brake pedal 10 is depressed by the driver. As a result, the servo pressure generated in the servo chamber 1A increases. As a result, the amount of operation of the brake pedal 10 increases unless the operating force (stepping force) corresponding to the brake pedal 10 is reduced by the driver. Then, since the servo pressure further increases, the operation amount of the brake pedal 10 further increases unless the pedal effort is reduced by the driver. In this way, unless the pedaling force is reduced by the driver, it is conceivable that the amount of operation of the brake pedal 10 increases (the rigidity of the operation of the brake pedal 10 decreases). On the other hand, in this embodiment, since the increase in the servo pressure is limited, it is possible to suppress a decrease in the rigidity feeling of the brake pedal 10.

  In addition, the separation chamber valve 22 is opened, and the “precharge end process” is executed in a state where the separation chamber 1B is not liquid-tight. Thereby, the vibration caused by the decrease in the servo pressure in the servo chamber 1A is not transmitted to the brake pedal 10 in accordance with the “precharge end process”. For this reason, the driver who puts his foot on the brake pedal does not feel uncomfortable.

(Another embodiment)
In the embodiment described above, in the process of S43 shown in FIG. 4, as shown by the solid line in FIG. 6, the brake ECU 6 detects the amount of movement of the input piston 13 detected by the stroke sensor 72 (movement of the brake pedal 10). Regardless of the amount, the pilot pressure is controlled by controlling the pressure reducing valve 41 and the pressure increasing valve 42 so that the servo pressure does not exceed the limit value. However, the present invention is not limited to this, and as shown by the dotted line in FIG. 6, the brake ECU 6 exceeds the limit value, but compared with the “servo pressure linear control”, the servo pressure with respect to the increase in the movement amount of the input piston 13 There is no problem even if control for limiting the increase amount is performed. In the case of this embodiment, the above-described decrease in rigidity of the brake pedal 10 can be suppressed, and a larger servo pressure can be applied to the servo chamber 1A, thereby generating a larger friction braking force. Can do.

  In the embodiment described above, the stroke sensor 72 that is a brake operation amount detection unit is a sensor that detects the stroke amount of the brake pedal 10. However, the brake operation amount detection unit may be a sensor that detects the stroke amount of the input piston 13 and the operation force (stepping force) with respect to the brake pedal 10. Further, in the present invention, the first output piston 14 moves by the stroke amount corresponding to the operation amount of the brake pedal 10 in order to close the separation chamber 1B in the “fade mode”. The fluid pressure (reaction force pressure) in the reaction force pressure chamber 1 </ b> C becomes a fluid pressure corresponding to the stroke position of the first output piston 14. Therefore, the reaction force pressure becomes a hydraulic pressure corresponding to the operation amount of the brake pedal 10. Therefore, the brake operation amount detection unit may be the pressure sensor 73.

  In the embodiment described above, the separation chamber valve 22 is a linear valve whose opening degree increases as the supplied current increases. However, the separation chamber valve 22 may be a non-linear electromagnetic valve that opens immediately when current is supplied.

  In the embodiment described above, the brake operation member that transmits the operation force of the driver to the input piston 13 is the brake pedal 10. However, the brake operation member is not limited to the brake pedal 10 and may be, for example, a brake lever or a brake handle. It goes without saying that the technical idea of the present invention can be applied even if the vehicle braking device (friction brake unit B) of the present embodiment is applied to a motorcycle or other vehicles.

1: Master cylinder device 10: Brake pedal (brake operation member)
11: Main cylinder (master cylinder)
12: Cover cylinder (master cylinder)
13: Input piston 14: First output piston 15: Second output piston 1A: Servo chamber, 1B: Separation chamber, 1C: Reaction force pressure chamber 1D: First master chamber, 1E: Second master chamber 2: Reaction force generation Device, 3: reaction force chamber valve 4: servo pressure generator (servo pressure generator)
21: Stroke simulator (reaction force chamber forming unit), 214: Reaction force chamber 22: Separation chamber valve 41: Pressure reducing valve, 42: Pressure increasing valve, 431: Accumulator 6: Brake ECU (fade state determination unit, separation chamber valve control unit) , Reaction force chamber valve control unit, reduction amount setting unit)
72: Stroke sensor (brake operation amount detector)
73, 74, 75: Pressure sensor A: Regenerative brake device, B: Friction brake unit Bfl, Bfr, Brl, Brr: Friction brake device WCfl, WCfr, WCrl, WCrr: Wheel cylinder Wfl, Wfr, Wrl, Wrr: Wheel

Claims (5)

A brake device for a vehicle that supplies brake fluid to a wheel cylinder of a friction brake device provided on a wheel of a vehicle, and generates a friction braking force on the wheel by the friction brake device,
A master cylinder connected to the wheel cylinder;
The volume of the master chamber filled with the brake fluid supplied to the wheel cylinder is changed by being slidably disposed in the master cylinder and driven by the hydraulic pressure in the servo chamber partitioned by the master cylinder. An output piston;
An input piston that is slidably rearward of the output piston in the master cylinder, divides a separation chamber filled with the brake fluid between the output piston and interlocks with an operation of a brake operation member; ,
A separation chamber valve provided in a flow path connected to the separation chamber, opening the separation chamber by opening the valve, and closing the separation chamber by closing the valve;
A servo pressure generator for generating servo pressure in the servo chamber;
A fade state determination unit for determining whether or not the friction brake device is in a fade state;
Wherein when the friction brake device by fading state determination unit is determined to be the fade state, by the separation chamber valve closes the separation chamber, the friction brake device is non-fading by the fade condition determination unit A separation chamber valve control unit that opens the separation chamber by the separation chamber valve;
As the friction brake device determined by the fade state determination unit transitions from the non-fade state to the fade state, the servo pressure generation unit changes the hydraulic pressure in the servo chamber, and the output piston changes to the output piston. A precharge process for increasing a predetermined precharge pressure, which is a pressure to advance the input piston by a predetermined distance, is executed, and the state of the friction brake device determined by the fade state determination unit is changed from the fade state. A precharge control unit that executes a precharge end process for reducing the hydraulic pressure in the servo chamber by the precharge pressure by the servo pressure generation unit in accordance with the transition to the non-fade state;
A reaction force chamber forming portion forming a reaction force chamber in which a hydraulic pressure is generated as an operation reaction force opposed to a force acting on the brake operation member;
A reaction force chamber valve for opening and closing a flow path between the reaction force chamber and a reservoir in which the brake fluid is stored;
When it is determined that the friction brake device is in the fade state by the fade state determination unit, the reaction force chamber valve is opened, and the friction brake device is in the non-fade state by the fade state determination unit. A reaction force chamber valve control unit for closing the reaction force chamber valve when it is determined that
The flow path on the opposite side of the separation chamber valve to the separation chamber is connected to the reaction force chamber side flow path of the reaction force chamber valve,
The separation chamber valve control unit closes the reaction force chamber valve by the reaction force chamber valve control unit when it is determined by the fade state determination unit that the friction brake device is in the non-fade state. After being done, the brake device for vehicles which opens the said separation chamber valve . A brake device for a vehicle that supplies brake fluid to a wheel cylinder of a friction brake device provided on a wheel of a vehicle, and generates a friction braking force on the wheel by the friction brake device,
A master cylinder connected to the wheel cylinder;
The volume of the master chamber filled with the brake fluid supplied to the wheel cylinder is changed by being slidably disposed in the master cylinder and driven by the hydraulic pressure in the servo chamber partitioned by the master cylinder. An output piston;
An input piston that is slidably rearward of the output piston in the master cylinder, divides a separation chamber filled with the brake fluid between the output piston and interlocks with an operation of a brake operation member; ,
A separation chamber valve provided in a flow path connected to the separation chamber, opening the separation chamber by opening the valve, and closing the separation chamber by closing the valve;
A servo pressure generator for generating servo pressure in the servo chamber;
A fade state determination unit for determining whether or not the friction brake device is in a fade state;
When the fade state determination unit determines that the friction brake device is in a fade state, the separation chamber valve closes the separation chamber, and the fade state determination unit causes the friction brake device to be in a non-fade state. A separation chamber valve control unit that opens the separation chamber by the separation chamber valve;
As the friction brake device determined by the fade state determination unit transitions from the non-fade state to the fade state, the servo pressure generation unit changes the hydraulic pressure in the servo chamber, and the output piston changes to the output piston. A precharge process for increasing a predetermined precharge pressure, which is a pressure to advance the input piston by a predetermined distance, is executed, and the state of the friction brake device determined by the fade state determination unit is changed from the fade state. A precharge control unit that executes a precharge end process for reducing the hydraulic pressure in the servo chamber by the precharge pressure by the servo pressure generation unit in accordance with the transition to the non-fade state;
A reaction force chamber forming portion forming a reaction force chamber in which a hydraulic pressure is generated as an operation reaction force opposed to a force acting on the brake operation member;
A reaction force chamber valve for opening and closing a flow path between the reaction force chamber and a reservoir in which the brake fluid is stored;
When the fade state determination unit determines that the friction brake device is in the fade state, the reaction force chamber is opened, and the fade state determination unit causes the friction brake device to be in the non-fade state. A reaction force chamber valve control section for closing the reaction force chamber valve when it is determined that there is,
The flow path on the opposite side of the separation chamber valve to the separation chamber is connected to the reaction force chamber side flow path of the reaction force chamber valve,
The separation chamber valve control unit closes the reaction force chamber valve by the reaction force chamber valve control unit when it is determined by the fade state determination unit that the friction brake device is in the non-fade state. A vehicular braking device that starts the opening of the separation chamber valve after elapse of a time corresponding to the operation state of the brake operation member since the start of the operation. The precharge control unit, said at completion of precharge process, the vehicle braking system according to claim 1 or claim 2 gradually decreasing the hydraulic pressure of the servo chamber. A reduction amount setting unit that sets a reduction amount per unit time of the hydraulic pressure in the servo chamber in the precharge end processing to a smaller amount as the vehicle speed or deceleration decreases,
The precharge control unit, in the pre-charge ending processing, a decrease amount per unit time which is set by the decrease amount setting unit, of claims 1 to 3 for reducing the hydraulic pressure in the servo chamber The brake device for vehicles as described in any one . The separation chamber valve control unit, upon to open the said separation chamber valve when said said friction braking device by the fade condition determining unit wherein a non-fade state is determined, the opening degree of the separation chamber valve The vehicle braking device according to any one of claims 1 to 4 , wherein the vehicle speed is gradually increased.

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