JP2019084920A - Vehicular braking device - Google Patents

Abstract

To provide a vehicular braking device capable of compatibly suppressing overshooting and also suppressing an operation sound of a liquid pressure supply device.SOLUTION: The present invention is directed to a vehicular braking device so constituted that a servo pressure generation device 4 has hysteresis varying in drive pressure for a predetermined period from the point of time of transition from pressure increase control or pressure reduction control to holding control, and the vehicle braking device comprises: liquid pressure supply parts 57, 90, and 97 which supply a brake liquid to a liquid pressure passage A connecting master chambers 1D, 1E and wheel cylinders 541 to 544; and a target setting part 62 which executes target setting processing to set target master pressure so that target master pressure is smaller than target wheel pressure when the wheel pressure is maintained or reduced than when the wheel pressure is increased.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a braking device for a vehicle.

  Among the vehicle braking devices, there is one in which an actuator (pressure mechanism) capable of pressurizing the wheel cylinder is disposed between the master cylinder and the wheel cylinder. The actuator can pressurize the fluid pressure (wheel pressure) of the wheel cylinder by driving the pump and controlling the differential pressure control valve. The configuration of the actuator is described, for example, in JP-A-2016-52809.

JP, 2016-52809, A

  The fluid pressure control by the actuator has higher linearity (responsiveness) than the fluid pressure control by, for example, a hydraulic booster including a regulator because there is no control dead zone. Therefore, the vehicle braking device may be configured to generate a hydraulic braking force on the basis of pressurization by the actuator. Also, in a vehicle equipped with a regenerative braking device, hydraulic control by an actuator is often used.

  However, since the control of hydraulic pressure by the actuator (particularly pressure control) is accompanied by the drive of the pump, the operation of the motor for driving the pump is required. Therefore, at the time of hydraulic pressure control by the actuator, the operation noise of the motor is generated, and there is a problem in terms of quietness. Thus, the operation of the hydraulic pressure supply device for supplying the hydraulic pressure to the hydraulic pressure path is accompanied by the generation of the operation noise. The inventor of the present invention has a braking device for a vehicle provided with a pressurizing mechanism (upstream pressurizing mechanism) capable of pressurizing and controlling hydraulic pressure (master pressure) of a master cylinder, in addition to an actuator (downstream pressurizing mechanism). Research and development, but the above problems also occur in this configuration.

  In addition, as the upstream side pressurizing mechanism, a hydraulic booster provided with a regulator is adopted from the viewpoint of output and durability. However, the regulator has a hysteresis in which the control hydraulic pressure fluctuates for a predetermined period from the time when the pressure increase control or the pressure decrease control is shifted to the hold control, so that overshoot or undershoot may occur. For example, the influence of the overshoot on the wheel pressure may not be eliminated even by the fluid pressure adjustment with the differential pressure control valve depending on the situation.

  The present invention has been made in view of such circumstances, and it is an object of the present invention to provide a vehicle brake device capable of achieving both suppression of overshoot and suppression of operation noise of a hydraulic pressure supply device. Do.

  The vehicle braking system according to the present invention generates a drive pressure in a drive chamber for generating a drive pressure for driving a piston, and a master cylinder having a master chamber for generating a master pressure by driving the piston, and the drive pressure in the drive chamber. Pressure increase control for increasing the drive pressure based on a target master pressure that is a target value of the master pressure by control of a drive pressure supply unit and the drive pressure supply unit, holding control for holding the drive pressure, or A first control unit that executes pressure reduction control that reduces the drive pressure, a hydraulic pressure supply unit that supplies a brake fluid to a hydraulic pressure passage that connects the master chamber and the wheel cylinder, and A holding valve for holding the fluid pressure of the wheel cylinder, a pressure reducing valve for reducing the fluid pressure of the wheel cylinder held by the holding valve, the master pressure or the target master pressure The hydraulic pressure supply unit, the holding valve, and the pressure reducing valve are controlled so that the hydraulic pressure of the wheel cylinder becomes the target wheel pressure based on the target wheel pressure which is the target value of the hydraulic pressure of the wheel cylinder. A second control unit, and the drive pressure supply unit is configured to have a hysteresis in which the drive pressure fluctuates for a predetermined period from the time when the pressure increase control or the pressure decrease control shifts to the hold control. In the vehicle braking device, when the fluid pressure of the wheel cylinder is held or reduced, the target master pressure is greater than the target wheel pressure as compared to the case where the fluid pressure of the wheel cylinder is increased. A target setting unit is provided which executes target setting processing for setting the target master pressure so as to be smaller.

  According to the present invention, when the hydraulic pressure (wheel pressure) of the wheel cylinder is held or reduced by the target setting process, the target master pressure is relatively smaller than when the wheel pressure is increased. When the demand for the wheel pressure shifts from the pressure increase to the hold, the target master pressure decreases, and the wheel pressure is held by the hold valve, and the pressure reduction control is executed by the drive pressure supply unit. Thereby, the overshoot can be suppressed more reliably while maintaining the wheel pressure. Further, by suppressing the overshoot more reliably, the wheel pressure can be increased by the master pressure increase main body (that is, the drive pressure supply unit main body). That is, the hydraulic pressure braking force can be generated without driving the hydraulic pressure supply unit or by reducing the drive amount of the hydraulic pressure supply unit. According to the present invention, it is possible to achieve both suppression of overshoot and suppression of operation noise of the fluid pressure supply unit (fluid pressure supply device).

It is a block diagram of the braking device for vehicles of this embodiment. It is a sectional view of a regulator of this embodiment. It is a block diagram of the actuator of this embodiment. It is a time chart for explaining goal setting processing of this embodiment.

  Hereinafter, an embodiment of the present invention will be described based on the drawings. Each figure used for explanation is a conceptual diagram, and the shape of each part may not necessarily be exact. As shown in FIG. 1, the vehicle braking device BF includes a master cylinder 1, a reaction force generator 2, a first control valve 22, a second control valve 23, and a servo pressure generator (“drive pressure supply unit , The actuator 5, the wheel cylinders 541 to 544, the various sensors 71 to 77, the upstream ECU (corresponding to the "first control unit") 6, and the downstream ECU (the "second Control unit 6A). Further, in the present embodiment, in order to explain the hybrid vehicle as an example, the vehicle braking device BF is provided with a regenerative braking device 8. The regenerative braking device 8 is provided for the front wheel Wf, and includes a hybrid ECU 81, a generator 82, an inverter 83, and a battery 84. The details of the regenerative braking device 8 are omitted because they are known.

  The master cylinder 1 is a part that supplies the brake fluid to the actuator 5 according to the amount of operation of the brake pedal (brake operation member) 10, and the main cylinder 11, the cover cylinder 12, the input piston 13, the first master piston 14, and A second master piston 15 is provided. The brake pedal 10 may be any brake operating means that allows the driver to brake.

  The main cylinder 11 is a bottomed, substantially cylindrical housing that is closed at the front and opens at the rear. An inner wall portion 111 that protrudes in an inward flange shape is provided on the inner peripheral side of the main cylinder 11 so as to be closer to the rear. The center of the inner wall portion 111 is a through hole 111 a penetrating in the front-rear direction. Further, on the front side of the inner wall portion 111 inside the main cylinder 11, small diameter portions 112 (rear) and 113 (front) whose inner diameters are slightly smaller are provided. That is, the small diameter portions 112 and 113 protrude in an annular shape inwardly from the inner peripheral surface of the main cylinder 11. Inside the main cylinder 11, a first master piston 14 is disposed slidably in the small diameter portion 112 so as to be movable in the axial direction. Similarly, the second master piston 15 is disposed slidably in the small diameter portion 113 so as to be movable in the axial direction.

  The cover cylinder 12 includes a substantially cylindrical cylinder portion 121, a bellows cylindrical boot 122, and a cup-shaped compression spring 123. The cylinder portion 121 is disposed on the rear end side of the main cylinder 11 and coaxially fitted in an opening on the rear side of the main cylinder 11. The inner diameter of the front portion 121 a of the cylinder portion 121 is larger than the inner diameter of the through hole 111 a of the inner wall portion 111. Further, the inner diameter of the rear portion 121b of the cylinder portion 121 is smaller than the inner diameter of the front portion 121a.

  The dustproof boot 122 has a bellows-like cylindrical shape and can be expanded and contracted in the front-rear direction, and is assembled so as to contact the rear end side opening of the cylinder portion 121 on the front side thereof. A through hole 122 a is formed at the rear center of the boot 122. The compression spring 123 is a coil-like biasing member disposed around the boot 122, and the front side is in contact with the rear end of the main cylinder 11, and the rear side is compressed so as to approach the through hole 122a of the boot 122. It is diameter. The rear end of the boot 122 and the rear end of the compression spring 123 are coupled to the operating rod 10a. The compression spring 123 biases the operating rod 10 a rearward.

  The input piston 13 is a piston that slides in the cover cylinder 12 in response to the operation of the brake pedal 10. The input piston 13 is a bottomed substantially cylindrical piston having a bottom in the front and an opening in the rear. The bottom wall 131 constituting the bottom surface of the input piston 13 is larger in diameter than the other portions of the input piston 13. The input piston 13 is axially slidably and fluidly disposed in the rear portion 121 b of the cylinder portion 121, and the bottom wall 131 enters the inner peripheral side of the front portion 121 a of the cylinder portion 121.

  Inside the input piston 13, an operation rod 10 a interlocking with the brake pedal 10 is disposed. The pivot 10b at the tip of the operating rod 10a can push the input piston 13 forward. The rear end of the operating rod 10 a protrudes to the outside through the opening on the rear side of the input piston 13 and the through hole 122 a of the boot 122 and is connected to the brake pedal 10. When the brake pedal 10 is depressed, the operating rod 10a advances while pressing the boot 122 and the compression spring 123 in the axial direction. As the operation rod 10a advances, the input piston 13 also advances in conjunction with it.

  The first master piston 14 is disposed slidably on the inner wall portion 111 of the main cylinder 11 in the axial direction. The pressure cylinder part 141, the flange part 142, and the protrusion part 143 are integrally formed in the 1st master piston 14 in order from the front side. The pressure cylinder portion 141 is formed in a substantially cylindrical shape with a bottom at the front and has an opening, has a gap with the inner circumferential surface of the main cylinder 11, and is in sliding contact with the small diameter portion 112. A biasing member 144 in the form of a coil spring is disposed between the second master piston 15 and the internal space of the pressure cylinder portion 141. The first master piston 14 is biased rearward by the biasing member 144. In other words, the first master piston 14 is biased by the biasing member 144 toward the set initial position.

  The flange portion 142 has a diameter larger than that of the pressure cylinder portion 141 and is in sliding contact with the inner peripheral surface of the main cylinder 11. The projecting portion 143 has a diameter smaller than that of the flange portion 142 and is disposed so as to slide in a fluid-tight manner in the through hole 111 a of the inner wall portion 111. The rear end of the protruding portion 143 passes through the through hole 111 a and protrudes into the internal space of the cylinder portion 121, and is separated from the inner circumferential surface of the cylinder portion 121. The rear end surface of the projecting portion 143 is separated from the bottom wall 131 of the input piston 13, and the separation distance is variable.

  Here, a “first master chamber 1D” is defined by the inner circumferential surface of the main cylinder 11, the front side of the pressure cylinder portion 141 of the first master piston 14, and the rear side of the second master piston 15. Further, the rear chamber behind the first master chamber 1D is defined by the inner peripheral surface (inner peripheral portion) of the main cylinder 11, the small diameter portion 112, the front surface of the inner wall portion 111, and the outer peripheral surface of the first master piston 14. ing. The front end portion and the rear end portion of the flange portion 142 of the first master piston 14 divide the rear chamber back and forth, the “second hydraulic pressure chamber 1C” is partitioned on the front side, and the “servo chamber (drive 1) corresponding to a room is divided. The volume of the second hydraulic pressure chamber 1C decreases as the first master piston 14 advances, and the volume increases as the first master piston 14 retreats. Further, the inner peripheral portion of the main cylinder 11, the rear surface of the inner wall portion 111, the inner peripheral surface (inner peripheral portion) of the front portion 121a of the cylinder portion 121, the projecting portion 143 (rear end portion) of the first master piston 14, and the input The “first fluid pressure chamber 1 </ b> B” is defined by the front end portion of the piston 13.

  The second master piston 15 is disposed on the front side of the first master piston 14 in the main cylinder 11 so as to be axially movable and in sliding contact with the small diameter portion 113. The second master piston 15 is integrally formed with a cylindrical pressure cylinder 151 having an opening at the front, and a bottom wall 152 closing the rear side of the pressure cylinder 151. The bottom wall 152 supports the biasing member 144 between itself and the first master piston 14. A biasing member 153 in the form of a coil spring is disposed in the internal space of the pressure cylinder 151 and between the closed inner bottom surface 111 d of the main cylinder 11. The second master piston 15 is biased rearward by the biasing member 153. In other words, the second master piston 15 is biased by the biasing member 153 toward the set initial position. A “second master chamber 1E” is defined by the inner peripheral surface of the main cylinder 11, the inner bottom surface 111d, and the second master piston 15.

  The master cylinder 1 is formed with ports 11 a to 11 i that communicate the inside with the outside. The port 11 a is formed rearward of the inner wall portion 111 of the main cylinder 11. The port 11 b is formed at the same position in the axial direction as the port 11 a, facing the port 11 a. The port 11 a and the port 11 b communicate with each other through an annular space between the inner peripheral surface of the main cylinder 11 and the outer peripheral surface of the cylinder portion 121. The port 11 a and the port 11 b are connected to the pipe 161 and connected to the reservoir 171 (low pressure source).

  The port 11 b is in communication with the first fluid pressure chamber 1 B by a passage 18 formed in the cylinder portion 121 and the input piston 13. The passage 18 is shut off when the input piston 13 advances, whereby the first hydraulic pressure chamber 1B and the reservoir 171 are shut off. The port 11c is formed rearward of the inner wall portion 111 and forward of the port 11a, and communicates the first fluid pressure chamber 1B with the pipe 162. The port 11d is formed forward of the port 11c, and communicates the servo chamber 1A with the pipe 163. The port 11e is formed forward of the port 11d, and communicates the second hydraulic pressure chamber 1C with the pipe 164.

  The port 11 f is formed between the seal members G 1 and G 2 of the small diameter portion 112, and communicates the reservoir 172 with the inside of the main cylinder 11. The port 11 f is in communication with the first master chamber 1 D via a passage 145 formed in the first master piston 14. The passage 145 is formed at a position where the port 11 f and the first master chamber 1 D are shut off when the first master piston 14 advances. The port 11g is formed in front of the port 11f, and communicates the first master chamber 1D with the conduit 31.

  The port 11 h is formed between the seal members G 3 and G 4 of the small diameter portion 113, and communicates the reservoir 173 with the inside of the main cylinder 11. The port 11 h is in communication with the second master chamber 1 E via a passage 154 formed in the pressure cylinder 151 of the second master piston 15. The passage 154 is formed at a position where the port 11 h and the second master chamber 1 E are shut off when the second master piston 15 advances. The port 11i is formed in front of the port 11h, and communicates the second master chamber 1E with the conduit 32.

  Further, in the master cylinder 1, a seal member such as an O-ring is appropriately disposed. The seal members G1 and G2 are disposed at the small diameter portion 112, and are in fluid-tight contact with the outer peripheral surface of the first master piston. Similarly, the seal members G3 and G4 are disposed at the small diameter portion 113, and abut on the outer peripheral surface of the second master piston 15 in a fluid tight manner. Also, seal members G5 and G6 are disposed between the input piston 13 and the cylinder portion 121.

  The stroke sensor 71 is a sensor that detects an operation amount (stroke) at which the brake pedal 10 is operated by the driver, and transmits a detection signal to the upstream ECU 6 and the downstream ECU 6A. The brake stop switch 72 is a switch that detects the presence or absence of the operation of the brake pedal 10 by the driver as a binary signal, and transmits a detection signal to the upstream ECU 6.

  The reaction force generating device 2 is a device that generates a reaction force that opposes the operating force when the brake pedal 10 is operated, and is mainly configured of the stroke simulator 21. In response to the operation of the brake pedal 10, the stroke simulator 21 generates a reaction fluid pressure in the first fluid pressure chamber 1B and the second fluid pressure chamber 1C. The stroke simulator 21 is configured by slidably fitting a piston 212 to a cylinder 211. The piston 212 is biased rearward by a compression spring 213, and a reaction fluid pressure chamber 214 is formed on the rear side of the piston 212. The reaction force fluid pressure chamber 214 is connected to the second fluid pressure chamber 1C via the pipe 164 and the port 11e, and the reaction force fluid pressure chamber 214 is connected via the pipe 164 to the first control valve 22 and the second control. It is connected to the valve 23.

  The first control valve 22 is an electromagnetic valve that is closed in a non-energized state, and is controlled by the upstream ECU 6 to open and close. The first control valve 22 is connected between the pipe 164 and the pipe 162. Here, the pipe 164 communicates with the second fluid pressure chamber 1C via the port 11e, and the pipe 162 communicates with the first fluid pressure chamber 1B via the port 11c. When the first control valve 22 is opened, the first fluid pressure chamber 1B is opened, and when the first control valve 22 is closed, the first fluid pressure chamber 1B is closed. Therefore, the pipe 164 and the pipe 162 are provided to communicate the first fluid pressure chamber 1B with the second fluid pressure chamber 1C.

  The first control valve 22 is closed in a non-energized state without being energized, and at this time, the first fluid pressure chamber 1B and the second fluid pressure chamber 1C are shut off. As a result, the first fluid pressure chamber 1B is sealed and there is no place to go for the brake fluid, and the input piston 13 and the first master piston 14 are interlocked while maintaining a fixed separation distance. Further, the first control valve 22 is open in the energized state, and at this time, the first fluid pressure chamber 1B and the second fluid pressure chamber 1C are communicated with each other. As a result, the volume change of the first fluid pressure chamber 1B and the second fluid pressure chamber 1C accompanying the advancing and retracting of the first master piston 14 is absorbed by the movement of the brake fluid.

  The pressure sensor 73 is a sensor that detects the reaction fluid pressure in the second fluid pressure chamber 1C and the first fluid pressure chamber 1B, and is connected to the pipe 164. The pressure sensor 73 detects the pressure in the second hydraulic pressure chamber 1C when the first control valve 22 is closed, and communicates with the first hydraulic pressure chamber 1B when the first control valve 22 is open. Pressure will also be detected. The pressure sensor 73 transmits a detection signal to the upstream ECU 6.

  The second control valve 23 is an electromagnetic valve that opens in a non-energized state, and the upstream side ECU 6 controls the opening and closing of the second control valve 23. The second control valve 23 is connected between the pipe 164 and the pipe 161. Here, the pipe 164 communicates with the second fluid pressure chamber 1C via the port 11e, and the pipe 161 communicates with the reservoir 171 via the port 11a. Therefore, the second control valve 23 communicates between the second hydraulic pressure chamber 1C and the reservoir 171 in a non-energized state to generate a reaction liquid pressure, but shuts off in a energized state to generate a reaction liquid pressure. Let

  The servo pressure generator 4 is a so-called hydraulic booster (booster), and 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 solenoid valve (normally open valve) that opens in a non-energized state, and the flow rate (or pressure) is controlled by the upstream ECU 6. One end of the pressure reducing valve 41 is connected to the pipe 161 via the pipe 411, and the other end of the pressure reducing valve 41 is connected to the pipe 413. That is, one end of the pressure reducing valve 41 communicates with the reservoir 171 via the pipes 411 and 161 and the ports 11a and 11b. By closing the pressure reducing valve 41, the brake fluid is prevented from flowing out from the first pilot chamber 4D described later. The reservoir 171 and the reservoir 434 are in communication although not shown. The reservoir 171 and the reservoir 434 may be the same reservoir.

  The pressure increasing valve 42 is a normally closed electromagnetic valve (normally closed valve) closed in a non-energized state, and the flow rate (or pressure) is controlled by the upstream ECU 6. One end of the pressure increase valve 42 is connected to the pipe 421, and the other end of the pressure increase valve 42 is connected to the pipe 422. The pressure supply unit 43 is a part that mainly supplies high-pressure brake fluid to the regulator 44. The pressure supply unit 43 includes an accumulator 431, a hydraulic pump 432, a motor 433, and a reservoir 434.

  The accumulator 431 is a tank for accumulating high pressure brake fluid. The accumulator 431 is connected to the regulator 44 and the hydraulic pump 432 by a pipe 431 a. The hydraulic pump 432 is driven by the motor 433 and pumps the brake fluid stored in the reservoir 434 to the accumulator 431. The pressure sensor 75 provided in the pipe 431 a detects an accumulator hydraulic pressure of the accumulator 431 and transmits a detection signal to the upstream ECU 6. The accumulator fluid pressure correlates to the accumulated amount of brake fluid accumulated in the accumulator 431.

  When the pressure sensor 75 detects that the accumulator fluid pressure has dropped below the predetermined on pressure, the motor 433 is driven based on the command from the upstream ECU 6. As a result, the hydraulic pump 432 pumps brake fluid to the accumulator 431 to recover the accumulator hydraulic pressure to a predetermined value or more. Further, when it is detected by the pressure sensor 75 that the accumulator fluid pressure has dropped below the predetermined off pressure, the motor 433 is stopped based on the command from the upstream side ECU 6. That is, the on-pressure and the off-pressure of the motor 433 (accumulator 431) are set in the upstream side ECU 6, and the upstream side ECU 6 controls the accumulator fluid pressure based on the detection value of the pressure sensor 75.

  As shown in FIG. 2, the regulator 44 includes a cylinder 441, a ball valve 442, a biasing portion 443, a valve seat portion 444, a control piston 445, and a sub piston 446. The cylinder 441 is configured of a substantially bottomed cylindrical cylinder case 441a having a bottom surface on one side (right side in the drawing), and a lid member 441b closing an opening (left side in the drawing) of the cylinder case 441a. The cylinder case 441a is formed with a plurality of ports 4a to 4h for communicating the inside with the outside. The lid member 441b is also formed in a substantially bottomed cylindrical shape, and each port is formed at each portion opposed to the plurality of ports 4a to 4h of the cylindrical portion.

  The port 4a is connected to the pipe 431a. The port 4 b is connected to the pipe 422. The port 4 c is connected to the pipe 163. The piping 163 connects the servo chamber 1A and the port 4c. The port 4 d is connected to the reservoir 434 via a pipe 414. The port 4 e is connected to the pipe 424 and is further connected to the pipe 422 via the relief valve 423. The port 4 f is connected to the pipe 413. The port 4 g is connected to the pipe 421. The port 4 h is connected to a conduit 311 branched from the conduit 31.

  The ball valve 442 is a ball-type valve, and is disposed on the bottom surface side (hereinafter also referred to as the cylinder bottom surface side) of the cylinder case 441a inside the cylinder 441. The biasing portion 443 is a spring member for biasing the ball valve 442 to the opening side (hereinafter also referred to as a cylinder opening side) of the cylinder case 441a, 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 divides the cylinder opening side from the cylinder bottom side. At the center of the valve seat portion 444, a through passage 444a is formed, which communicates the divided cylinder opening side and the cylinder bottom side. The valve seat portion 444 holds the ball valve 442 from the cylinder opening side such that the biased ball valve 442 blocks the through passage 444a. A valve seat surface 444b on which the ball valve 442 is removably seated (contacted) is formed at the opening on the cylinder bottom side of the through passage 444a.

  A space defined by the ball valve 442, the biasing portion 443, the valve seat portion 444, and the inner peripheral surface of the cylinder case 441a on the cylinder bottom side is referred to as a "first chamber 4A". The first chamber 4A is filled with the 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 cylindrical main body 445 a and a substantially cylindrical protrusion 445 b smaller in diameter than the main body 445 a. The main body 445 a is coaxially and fluid-tightly and axially slidably disposed on the cylinder opening side of the valve seat 444 in the cylinder 441. The main body 445a is biased toward the cylinder opening by a biasing member (not shown). A passage 445c extending in the radial direction (vertical direction in the drawing) whose both ends are open at the circumferential surface of the main body portion 445a is formed substantially in the center of the main body portion 445a in the cylinder axial direction. The inner peripheral surface of a portion of the cylinder 441 corresponding to the opening position of the passage 445c is recessed in a concave shape while the port 4d is formed. This recessed space is referred to as "third chamber 4C".

  The protrusion 445 b protrudes from the center of the end surface on the cylinder bottom surface side of the main body 445 a toward the cylinder bottom surface. The diameter of the protrusion 445 b is smaller than the through passage 444 a of the valve seat 444. The protrusion 445 b is disposed coaxially with the through passage 444 a. The tip of the projecting portion 445 b is spaced apart from the ball valve 442 by a predetermined distance toward the cylinder opening. The projecting portion 445 b is formed with a passage 445 d extending in the cylinder axial direction that is opened at the center of the end surface of the projecting portion 445 b on the cylinder bottom side. 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 peripheral surface of the protrusion 445b, the inner peripheral surface of the cylinder 441, the valve seat 444, and the ball valve 442 is referred to as a "second chamber 4B". The second chamber 4B is in communication with the ports 4d and 4e via the passages 445d and 445c and the third chamber 4C in a state where the projecting portion 445b and the ball valve 442 are not in contact with each other.

  The sub piston 446 is composed of a sub main body 446 a, a first protrusion 446 b, and a second protrusion 446 c. The sub main body portion 446a is formed in a substantially cylindrical shape. The sub main body portion 446 a is coaxially, fluid tight, and axially slidably disposed on the cylinder opening side of the main body portion 445 a in the cylinder 441. Further, a damper mechanism may be provided at an end of the sub piston 446 on the cylinder bottom side.

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

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

  On the other hand, a space defined by the end face on the cylinder opening side of the sub main body portion 446a, the outer peripheral surface of the second projecting portion 446c, the lid member 441b, and the inner peripheral surface of the cylinder 441 is referred to as "second pilot chamber 4E". The second pilot chamber 4E communicates with the port 11g via the port 4h and the conduits 311 and 31. Each of the chambers 4A to 4E is filled with the brake fluid. The pressure sensor 74 is a sensor that detects a servo pressure (corresponding to a “drive pressure”) supplied to the servo chamber 1A, and is connected to the pipe 163. The pressure sensor 74 transmits a detection signal to the upstream ECU 6.

Thus, the regulator 44 has a control piston 445 driven by the difference between the force corresponding to the pressure in the first pilot chamber 4D (also referred to as "pilot pressure") and the force corresponding to the servo pressure. When the volume of the first pilot chamber 4D changes with the movement of 445, and the flow rate of the liquid flowing into and out of the first pilot chamber 4D increases, the force corresponding to the pilot pressure and the force corresponding to the servo pressure are balanced. The moving amount of the control piston 445 based on the position of the control piston 445 in the equilibrium state is increased, and the flow rate of the liquid flowing into and out of the servo chamber 1A is increased. That is, the regulator 44 is configured such that the liquid having a flow rate corresponding to the differential pressure between the pilot pressure and the servo pressure flows into and out of the servo chamber 1A.
As the flow rate of the liquid flowing from the accumulator 431 into the first pilot chamber 4D increases, the regulator 44 enlarges the first pilot chamber 4D and the flow rate of the liquid flowing from the accumulator 431 into the servo chamber 1A increases. As the flow rate of the liquid flowing out from the pilot chamber 4D to the reservoir 171 increases, the first pilot chamber 4D is reduced and the flow rate of the liquid flowing out from the servo chamber 1A to the reservoir 171 is increased. The regulator 44 having such a configuration has a hysteresis in which the servo pressure (pilot pressure) fluctuates for a predetermined period even after shifting from pressure increase control or pressure decrease control to hold control. The predetermined period is a period (period corresponding to the state) that fluctuates according to the gradient of the servo pressure (pilot pressure).
The amount of hysteresis is a change amount of the servo pressure which is still changed even if the pressure increase control or the pressure decrease control of the servo pressure is ended (even if it is shifted to the holding control). The holding control is control for closing the pressure reducing valve 41 and the pressure increasing valve 42. Hysteresis is, for example, pressure increase control, that is, holding control from a state where the control piston 445 pushes the ball valve 442 to bring the first chamber 4A and the second chamber 4B into communication (the control piston 445 is at the pressure increase position), That is, when the pressure reducing valve 41 and the pressure increasing valve 42 are closed and the first pilot chamber 4D is switched to the closed state, the control piston 445 retracts from the pressure increasing position to shut off the first chamber 4A and the second chamber 4B. Until it does, it arises because a pressure increase state continues. As the gradient of the servo pressure, ie, the gradient of the pilot pressure, increases, the control piston 445 advances, and the time to reverse after switching to the holding control becomes longer, and the hysteresis amount becomes larger. Conversely, the smaller the gradient of the servo pressure, the smaller the amount of hysteresis.
Further, a dead zone for the target servo pressure is set in the upstream ECU 6. The dead zone is set to the positive side and the negative side with respect to the target servo pressure. The upstream ECU 6 switches the brake control to the holding control when the actual servo pressure becomes a value within the range of the dead zone. That is, when performing the brake control, the upstream ECU 6 recognizes that the actual servo pressure substantially reaches the target servo pressure when it falls within the range of the dead zone (the dead zone region). By setting such a dead zone, hunting of fluid pressure control can be suppressed more than when setting the target servo pressure at one point.

  The actuator 5 is disposed between the first master chamber 1D and the second master chamber 1E in which a master cylinder pressure (hereinafter referred to as a master pressure) is generated, and the wheel cylinders 541 to 544. The actuator 5 and the first master chamber 1D are connected by a pipe line 31, and the actuator 5 and the second master chamber 1E are connected by a pipe line 32. The actuator 5 is a device that adjusts the fluid pressure (wheel pressure) of the wheel cylinders 541 to 544 in accordance with an instruction from the downstream ECU 6A. The actuator 5 executes pressurization control, pressure reduction control, and holding control to further pressurize the brake fluid from the master pressure according to a command from the downstream side ECU 6A. The actuator 5 combines these controls based on the command of the downstream side ECU 6A to execute anti-skid control (ABS control) or anti-slip control (ESC control).

  Specifically, as shown in FIG. 3, the actuator 5 includes a hydraulic circuit 5A and a motor 90. The hydraulic circuit 5A includes a first piping system 50a and a second piping system 50b. The first piping system 50a is a system that controls the hydraulic pressure (wheel pressure) applied to the rear wheels Wrl, Wrr. The second piping system 50b is a system that controls the hydraulic pressure (wheel pressure) applied to the front wheels Wfl and Wfr. Further, for each wheel W, a wheel speed sensor 76 is installed. In the present embodiment, front and rear piping is employed.

  The first piping system 50a includes a main pipe A, a differential pressure control valve 51, pressure increasing valves 52, 53, pressure reducing lines B, pressure reducing valves 54, 55, a pressure control reservoir 56, a reflux line C, and the like. , An auxiliary conduit D, an orifice portion 58, and a damper portion 59. In the description, the term "line" can be replaced with, for example, a hydraulic line, a flow path, an oil path, a passage, or a pipe.

  The main pipeline A is a pipeline connecting the pipeline 32 and the wheel cylinders 541 and 542. The differential pressure control valve 51 is an electromagnetic valve which is provided in the main conduit A and controls the main conduit A to a communication state and a differential pressure state. The differential pressure state is a state in which the flow path is restricted by the valve, and can also be referred to as a throttle state. The differential pressure control valve 51 is a differential pressure between the hydraulic pressure on the master cylinder 1 side and the hydraulic pressure on the wheel cylinders 541 and 542 centering on its own according to the control current based on the instruction of the downstream side ECU 6A (hereinafter referred to as “ Control the first differential pressure). In other words, the differential pressure control valve 51 is configured to be capable of controlling the differential pressure between the hydraulic pressure of the portion on the master cylinder 1 side of the main conduit A and the hydraulic pressure of the portion on the wheel cylinders 541 and 542 of the main conduit A. There is.

  The differential pressure control valve 51 is a normally open type that is in the communication state in the non-energized state. As the control current applied to the differential pressure control valve 51 increases, the first differential pressure increases. When the differential pressure control valve 51 is controlled to a differential pressure state and the pump 57 is driven, the fluid pressure on the wheel cylinders 541 and 542 becomes larger than the fluid pressure on the master cylinder 1 side according to the control current . A check valve 51 a is provided for the differential pressure control valve 51. The main pipeline A branches into two pipelines A1 and A2 at a branch point X on the downstream side of the differential pressure control valve 51 so as to correspond to the wheel cylinders 541 and 542.

  The pressure-increasing valves 52 and 53 are electromagnetic valves that open and close according to an instruction from the downstream side ECU 6A, and are normally open type electromagnetic valves that are opened (communicated state) in the non-energized state. The pressure intensifying valve 52 is disposed in the line A1, and the pressure intensifying valve 53 is disposed in the line A2. The pressure increase valves 52 and 53 are opened in the non-energized state at the time of pressure increase control and communicated with the wheel cylinders 541 to 544 and the branch point X, and are energized at the time of holding control and pressure reduction control to be in the closed state. And branch point X are cut off.

  The pressure reducing line B connects between the pressure increasing valve 52 and the wheel cylinders 541 and 542 in the line A1 and the pressure control reservoir 56, and adjusts pressure between the pressure increasing valve 53 and the wheel cylinders 541 and 542 in the line A2. It is a conduit connecting the pressure reservoir 56. The pressure reducing valves 54 and 55 are solenoid valves that open and close according to an instruction of the downstream side ECU 6A, and are normally closed type solenoid valves that are closed (cut off) in a non-energized state. The pressure reducing valve 54 is disposed in the pressure reducing channel B on the wheel cylinders 541 and 542 side. The pressure reducing valve 55 is disposed in the pressure reducing channel B on the wheel cylinders 541 and 542 side. The pressure reducing valves 54 and 55 are energized mainly at the time of pressure reducing control to be in an open state, and allow the wheel cylinders 541 and 542 to communicate with the pressure regulating reservoir 56 via the pressure reducing pipeline B. The pressure control reservoir 56 is a reservoir having a cylinder, a piston, and a biasing member.

  The reflux line C is a line connecting the pressure reducing line B (or pressure regulating reservoir 56) and the differential pressure control valve 51 and the pressure increasing valves 52 and 53 in the main line A (here, the branch point X). is there. The pump 57 is provided in the reflux line C so that the discharge port is disposed at the branch point X side and the suction port is disposed at the pressure control reservoir 56 side. The pump 57 is a gear-type electric pump (gear pump) driven by the motor 90. The pump 57 causes the brake fluid to flow from the pressure control reservoir 56 to the master cylinder 1 side or the wheel cylinders 541 and 542 side via the reflux line C. Further, the pump 57 pumps the brake fluid in the wheel cylinders 541 and 542 back to the master cylinder 1 via the pressure reducing valves 54 and 55 in an open state, for example, in anti-skid control. As described above, the pump 57 is disposed between the master cylinder 1 and the wheel cylinders 541 and 542, and can discharge the brake fluid in the wheel cylinders 541 and 542 to the outside of the wheel cylinders 541 and 542.

  The pump 57 is configured to repeat a discharge process of discharging the brake fluid and a suction process of sucking the brake fluid. That is, when the pump 57 is driven by the motor 90, the discharge process and the suction process are alternately repeated. In the discharge process, the brake fluid sucked from the pressure control reservoir 56 in the suction process is supplied to the branch point X. The motor 90 is energized and driven through a relay (not shown) according to an instruction of the downstream side ECU 6A. The pump 57 and the motor 90 can be collectively referred to as an electric pump.

  The orifice portion 58 is a throttle-shaped portion (so-called orifice) provided at a portion of the reflux line C between the pump 57 and the branch point X. The damper portion 59 is a damper (damper mechanism) connected to a portion of the return flow line C between the pump 57 and the orifice portion 58. The damper portion 59 absorbs and discharges the brake fluid in accordance with the pulsation of the brake fluid in the return conduit C. The orifice portion 58 and the damper portion 59 can be said to be a pulsation reducing mechanism that reduces (attenuates, absorbs) pulsation.

  The auxiliary pipe line D is a pipe line connecting the pressure control hole 56 a of the pressure control reservoir 56 and the upstream side (or the master cylinder 1) of the main pipe line A with respect to the differential pressure control valve 51. The pressure control reservoir 56 is configured such that the valve hole 56b is closed as the inflow of the brake fluid to the pressure control hole 56a increases due to the increase in the stroke. A reservoir chamber 56c is formed on the side of the conduits B and C of the valve hole 56b.

  When the pump 57 is driven, the brake fluid in the pressure control reservoir 56 or the master cylinder 1 is transferred to the portion between the differential pressure control valve 51 and the pressure increasing valves 52, 53 in the main conduit A via the reflux conduit C (branch point X Is discharged. Then, the wheel pressure is increased in accordance with the control states of the differential pressure control valve 51 and the pressure increasing valves 52, 53. As described above, in the actuator 5, pressurization control is executed by driving the pump 57 and controlling various valves. That is, the actuator 5 is configured to be able to press the wheel pressure. In the portion between the differential pressure control valve 51 of the main conduit A and the master cylinder 1, a pressure sensor 77 for detecting the fluid pressure (master pressure) of the portion is installed. The pressure sensor 77 transmits the detection result to the upstream ECU 6 and the downstream ECU 6A.

  The second piping system 50b has a configuration similar to that of the first piping system 50a, and is a system that adjusts the hydraulic pressure of the wheel cylinders 543 and 544 of the front wheels Wfl and Wfr. The second pipe system 50b corresponds to the main pipe A and connects the pipe 31 and the wheel cylinders 543 and 544, the differential pressure control valve 91 corresponding to the differential pressure control valve 51, and the pressure increasing valve 52. Pressure increasing valves 92 and 93 corresponding to the pressure control valve 53, pressure reducing conduits Bb corresponding to the pressure reducing flow passage B, pressure reducing valves 94 and 95 corresponding to the pressure reducing valves 54 and 55, pressure regulating reservoir 96 corresponding to the pressure regulating reservoir 56 , A reflux pipe Cb corresponding to the reflux pipe C, a pump 97 corresponding to the pump 57, an auxiliary pipe Db corresponding to the auxiliary pipe D, an orifice portion 58a corresponding to the orifice portion 58, and a damper portion And a damper portion 59a corresponding to 59. About the detailed composition of the 2nd piping system 50b, since explanation of the 1st piping system 50a can be referred to, explanation is omitted. Moreover, in the following description, the description of each part of the actuator 5 uses the code | symbol of 1st piping system 50a, and abbreviate | omits the code | symbol of 2nd piping system 50b.

  The adjustment of the wheel pressure by the actuator 5 may be, for example, pressure increase control for providing the master pressure as it is to the wheel cylinders 541 to 544, holding control for sealing the wheel cylinders 541 to 544, and adjustment of the brake fluid in the wheel cylinders 541 to 544. This is done by executing pressure reduction control to flow out to the pressure reservoir 56 or pressurization control to press the wheel pressure by the throttling by the differential pressure control valve 51 and the drive of the pump 57. Details will be described later.

  The upstream ECU 6 and the downstream ECU 6A are an electronic control unit (ECU) including a CPU, a memory, and the like. The upstream ECU 6 is an ECU that executes control on the servo pressure generator 4 based on a target wheel pressure (or target deceleration) that is a target value of the wheel pressure. The upstream ECU 6 executes pressure increase control (pressurization control), pressure reduction control, or holding control with respect to the servo pressure generator 4 based on the target wheel pressure. In the pressure increase control, the pressure increase valve 42 is opened, and the pressure reduction valve 41 is closed. In the pressure reducing control, the pressure increasing valve 42 is closed, and the pressure reducing valve 41 is opened. In the holding control, the pressure increasing valve 42 and the pressure reducing valve 41 are closed.

  Various sensors 71 to 77 are connected to the upstream ECU 6. The upstream ECU 6 obtains stroke information, master pressure information, reaction force hydraulic pressure information, servo pressure information, wheel speed information, and the like from these sensors. The sensor and the upstream ECU 6 are connected by a communication line (CAN) not shown. Further, the upstream ECU 6 acquires information (during antiskid control, etc.) regarding the control state of the actuator 5 from the downstream ECU 6A.

  The downstream ECU 6A is an ECU that executes control on the actuator 5 based on a target wheel pressure (or target deceleration) which is a target value of the wheel pressure. The downstream ECU 6A executes pressure increase control, pressure decrease control, hold control, or pressure control on the actuator 5 as described above based on the target wheel pressure.

  Here, each control state by the downstream side ECU 6A will be described taking control of the wheel cylinder 541 as an example. In pressure increase control, the pressure increase valve 52 (and the differential pressure control valve 51) is opened, and the pressure reduction valve 54 is closed. Become. The flow of the brake fluid from the upstream to the downstream is permitted by the check valve 51a installed in parallel with the differential pressure control valve 51, and the reverse is prohibited. Therefore, when the fluid pressure on the upstream side is higher than the fluid pressure on the downstream side, the brake fluid is supplied downstream via the check valve 51a without control to the differential pressure control valve 51. In the pressure reduction control, the pressure increasing valve 52 is closed, and the pressure reducing valve 54 is opened. In the holding control, the pressure increasing valve 52 and the pressure reducing valve 54 are closed. The holding control can also be performed by closing the pressure reducing valve 54 and closing (throttling) the differential pressure control valve 51 without closing the pressure increasing valve 52. Further, in the holding control, control is also performed to maintain the differential pressure while leaking the brake fluid from the differential pressure control valve 51 to the upstream side while driving the motor 90 and the pump 57 from the viewpoint of pressure response. That is, the differential pressure control valve 51 and / or the pressure increasing valve 52 correspond to a "holding valve" that holds the wheel pressure. In the pressurization control, the differential pressure control valve 51 is in the differential pressure state (throttling state), the pressure increasing valve 52 is opened, the pressure reducing valve 54 is closed, and the motor 90 and the pump 57 are driven. The motor 90 and the pump 57 correspond to a "hydraulic pressure supply portion" which supplies the brake fluid to a hydraulic pressure passage connecting the master chamber and the wheel cylinder. That is, the hydraulic pressure supply unit includes the pump 57 that discharges the brake fluid to the main conduit A, and the motor 90 that drives the pump 57. Further, the pressure reducing valve 54 can be said to be a valve that reduces the wheel pressure held by the holding valves 51 and 52.

  Various sensors such as a stroke sensor 71, pressure sensors 73 and 77, and a wheel speed sensor 76 are connected to the downstream ECU 6A. The downstream ECU 6A acquires stroke information, master pressure information, reaction force hydraulic pressure information, wheel speed information, and the like from these sensors. The various sensors and the downstream ECU 6A are connected by a communication line (not shown). The downstream ECU 6A executes anti-slip control and anti-skid control on the actuator 5 according to the situation and the request.

  The upstream ECU 6 sets the target deceleration based on the stroke information, and transmits the target deceleration information to the downstream ECU 6A via the communication line. The target master pressure and the target wheel pressure are determined based on the target deceleration. The upstream ECU 6 and the downstream ECU 6A control the hydraulic pressure of the brake fluid so that the wheel pressure approaches the target wheel pressure (deceleration approaches the target deceleration) by cooperative control. The upstream ECU 6 calculates the target deceleration based on the stroke to calculate the target master pressure, and the downstream ECU 6A calculates the target wheel pressure based on the target deceleration, and the detected master pressure (or target master pressure) and the target The pressure amount (control amount) is set based on the wheel pressure. The downstream ECU 6A transmits the control state (during anti-skid control, etc.) to the upstream ECU 6.

  Further, both ECUs 6 and 6A execute regenerative coordinated control with the hybrid ECU 81. In this case, for example, from the start of the brake operation to a predetermined situation, the target deceleration is achieved by the regenerative braking force by the regenerative braking device 8 and the pressurization of the wheel pressure by the actuator 5 (hydraulic braking force). Then, after the predetermined situation, the target deceleration is achieved mainly based on the regenerative braking force and the master pressure increase by the servo pressure generator 4, and near the end of the brake operation, the hydraulic braking force (pressure by the actuator 5) So-called substitution control to switch to) is executed.

  As described above, the vehicle braking device BF has a servo cylinder 1A that generates a servo pressure for driving the master pistons 14 and 15, and a master cylinder having master chambers 1D and 1E that generates a master pressure by driving the master pistons 14 and 15. 1 and servo pressure generating device 4 for generating servo pressure in servo chamber 1A, and pressure increase control for increasing servo pressure with respect to servo pressure generating device 4 based on target master pressure which is a target value of master, servo It is disposed in the main pipeline A that connects the master chamber 1D, 1E and the wheel cylinders 541 to 544 with the upstream ECU 6 that holds the holding control to hold the pressure or the pressure reduction control to reduce the servo pressure. The differential pressure control valve 51 and / or the fluid pressure which can be controlled on the side of 544 to be higher than the fluid pressure on the side of the master chamber 1D, 1E by the differential pressure control A pressure increasing valve 52 for holding the wheel pressure, a pump 57 for discharging the brake fluid to a portion of the main conduit A between the differential pressure control valve 51 and the wheel cylinders 541 to 544, a motor 90 for driving the pump 57; Based on the pressure reducing valves 54 and 55 disposed between the wheel cylinders 541 to 544 and the pressure control reservoir 56, and based on the master pressure or the target master pressure and the target wheel pressure, the wheel pressure becomes the target wheel pressure, A differential pressure control valve 51, a motor 90, and a downstream ECU 6A that controls the pressure reducing valves 54 and 55 are provided.

(Target setting process)
Here, the target setting process of the present embodiment will be described. In the present embodiment, the target setting process is performed when the vehicle speed is equal to or less than a predetermined speed. That is, the target setting process is performed when the regenerative braking force is equal to or less than a predetermined value. The upstream ECU 6 includes an upstream control unit 61 and a target setting unit 62 as functions. As described above, the upstream control unit 61 is configured to execute pressure increase control, hold control, or pressure decrease control for the servo pressure generator 4 based on the target master pressure.

  The target setting unit 62 sets the target master pressure so that the target master pressure is smaller than the target wheel pressure when holding or reducing the wheel pressure as compared to when the wheel pressure is increased. Execute "Process". When the wheel setting pressure is increased, the target setting unit 62 sets the target master pressure so that the target master pressure follows the target wheel pressure as a target setting process. In summary, the target setting unit 62 sets the target master pressure to the target wheel pressure or less, and when holding or reducing the wheel pressure, compared with the case where the wheel pressure is increased, the target master pressure and the target wheel pressure A target setting process is performed to set the target master pressure and the target wheel pressure so as to increase the difference. The decrease range of the target master pressure at this time is set from the width of one of the dead zones (the width from the target value to the upper limit of the dead zone) to the target master pressure (that is, the target master pressure is set to 0). Ru. The target setting unit 62 according to the present embodiment sets the target master pressure and the target wheel pressure to the same value when the wheel pressure is increased in the target setting process. Then, when the target setting process is executed, the downstream ECU 6A stops (does not drive) the motor 90.

  Thus, when the target setting process is executed, the target master pressure is set to follow the target wheel pressure at the time of pressure increase, and is set to a value smaller than the target wheel pressure at the time of holding or pressure reduction. The target setting unit 62 according to the present embodiment newly sets the target master pressure using the target wheel pressure set by the downstream ECU 6A as it is because the target wheel pressure is determined by the target deceleration and the presence or absence of regeneration coordination. In addition, the target setting unit 62 of the present embodiment is configured to execute the target setting process when the brake operation is performed at low speed traveling, that is, when the regenerative braking force is not output or is small. The vehicle speed can be acquired from the wheel speed sensor 76 or the like, and the generated or generated regenerative braking force can be acquired from the hybrid ECU 81.

  Here, an example of the target setting process will be described with reference to FIG. In this description, the brake operation at low speed traveling where the regenerative braking force is zero is taken as an example. When the braking operation is started, the target deceleration increases. At this time, the target setting unit 62 sets the target wheel pressure corresponding to the target deceleration, sets the target master pressure to the same value, and gives priority to the pressure increase in the servo pressure generator 4. That is, as shown in FIG. 4 (lower side), both ECUs 6 and 6A attempt to achieve the target deceleration only by the master pressure increase (pressurization by the servo pressure generator 4). The upstream ECU 6 executes pressure increase control on the servo pressure generator 4 based on the target master pressure (corresponding to the target servo pressure) set by the target setting unit 62. Since the difference between the target master pressure and the target wheel pressure is zero, the downstream side ECU 6A does not have a shortage of hydraulic pressure (or recognizes that the servo pressure generator 4 has priority), and applies pressure to the actuator 5 The control is not executed, and the normal pressure increase control state (the pressure increase valves 52, 53 are in the open state and the pressure decrease valves 54, 55 are in the close state) is maintained. That is, the motor 90 and the pump 57 are not driven, and the wheel pressure is increased only by the servo pressure generator 4.

  Then, when the stroke (the amount of brake operation) becomes constant, the calculated target deceleration becomes constant. The target setting unit 62 makes the target wheel pressure constant in order to hold the wheel pressure, and sets the target master pressure smaller than the target wheel pressure by a predetermined pressure so that the master pressure is controlled to the reduced side. As a result, the upstream ECU 6 executes pressure reduction control on the servo pressure generator 4, and the downstream ECU 6 A executes holding control on the actuator 5. That is, the upstream side ECU 6 opens the pressure reducing valve 41 and closes the pressure increasing valve 42, and the downstream side ECU 6A maintains the closing of the pressure reducing valves 54, 55 and the opening of the pressure increasing valves 52, 53. The differential pressure control valve 51 is brought into a differential pressure state (throttling state). Since the master pressure (servo pressure) gradually decreases, the downstream ECU 6A controls the differential pressure state of the differential pressure control valve 51 in the direction (valve closing side) in accordance with the fluctuation. This control reduces the master pressure but keeps the wheel pressure constant.

  Then, when the actual master (the detection value of the pressure sensor 77) enters the dead zone for the target master pressure due to the pressure reduction, the upstream ECU 6 executes the holding control. Note that this is the same as the control performed by the actual servo pressure (the detected value of the pressure sensor 73) and the target servo pressure. On the other hand, in order to hold the wheel pressure, the downstream side ECU 6A maintains the above-mentioned holding control, and makes the command pressure (control current) to the differential pressure control valve 51 constant according to the holding of the master pressure. The differential pressure control valve 51 is controlled to, for example, a closed state.

  Then, when the stroke decreases, the target deceleration decreases, and the target setting unit 62 maintains the difference between the target wheel pressure and the target master pressure, and adjusts the target wheel pressure and the target master pressure according to the decrease in the target deceleration. Make The upstream ECU 6 executes the pressure reduction control by the decrease of the target master pressure, and the master pressure decreases. When the master pressure decreases, the wheel pressure also decreases due to the action of the differential pressure control valve 51 controlled to a constant differential pressure state. Then, the target master pressure becomes 0 (atmospheric pressure) earlier than the target wheel pressure while the target deceleration decreases. After the target master pressure becomes 0, the downstream ECU 6A controls the differential pressure control valve 51 to the valve-opening side according to the decrease of the target deceleration (that is, reduce the control current to reduce the differential pressure), Reduce the wheel pressure. The downstream ECU 6A mainly controls the differential pressure control valve 51 without driving the motor 90 in the fluid pressure control that has undergone the target setting process.

  On the other hand, when the target setting process is not performed in the same situation, as shown in FIG. 4 (upper side), when the brake operation is started, the pressure control by the actuator 5 is first performed according to the increase of the target deceleration. Is executed. That is, the downstream ECU 6A drives the motor 90 and the pump 57. Then, when the target deceleration becomes equal to or more than a predetermined value, pressure increase control by the servo pressure generator 4 is started to assist the output from the viewpoint of durability. Along with this, the command pressure to the differential pressure control valve 51 also becomes constant. Then, after the stroke becomes constant and the target wheel pressure becomes constant (after transition to the holding control), the downstream ECU 6A continues the driving of the motor 90 and the pump 57, and the differential pressure state by the differential pressure control valve 51 While the brake fluid is leaked from the differential pressure control valve 51 to the upstream side, and the wheel pressure is kept constant.

  Then, when the target deceleration decreases, while the brake fluid is leaking as described above, the pressure reducing valves 54 and 55 are opened to reduce the wheel pressure. As described above, in the control in which the target setting process is not performed, the target deceleration is achieved by pressurizing only the actuator 5 at the start of pressure increase, and after the target master pressure is set (target master pressure> 0), the target wheel The pressure is controlled to be greater than the target master pressure by a predetermined pressure. In the conventional control, application of the hydraulic braking force is started from pressurization by the actuator 5 regardless of the magnitude of the regenerative braking force, and the motor 90 and the pump 57 continue to be driven.

  According to the present embodiment, when the wheel pressure is held or reduced by the target setting process, the target master pressure is relatively smaller than when the wheel pressure is increased. When the demand for the wheel pressure shifts from pressure increase to hold, the target master pressure decreases, so the wheel pressure is held by the differential pressure control valve 51 or the pressure increase valve 52, and the servo pressure generator 4 performs pressure reduction control. To be executed. Thereby, the overshoot can be suppressed more reliably while maintaining the wheel pressure. Further, by suppressing the overshoot more reliably, the wheel pressure can be increased by the master pressure increase main body (that is, the servo pressure generator 4 main body). That is, the hydraulic braking force can be generated without driving the motor 90 or reducing the driving amount of the motor 90. According to the present embodiment, both suppression of the overshoot and suppression of the operation noise of the motor 90 can be achieved.

  In the present embodiment, when the wheel pressure is increased, the target master pressure is set to follow the target wheel pressure (to be the same value). Power can be generated. Further, the downstream side ECU 6A does not need to drive the motor 90 during one brake operation (without increasing the pressure) performed at low speed traveling. Thereby, in the brake operation at the time of low speed traveling, the operation noise of the motor 90 is not generated, and the quietness is improved. Further, since the target setting process is performed when the regenerative braking force is equal to or less than the predetermined value, the influence on the regenerative coordinated control that generates separate hydraulic braking forces on the front wheel Wf and the rear wheel Wr is suppressed.

<Other modifications>
The present invention is not limited to the above embodiment. For example, as the target setting process, as the target setting process, the target master pressure when holding or reducing the wheel pressure becomes smaller relative to the target wheel pressure as the vehicle speed decreases (the target master pressure and the target wheel pressure And the target master pressure and the target wheel pressure may be set. For example, when the vehicle speed is extremely low (the vehicle speed is equal to or less than the second predetermined speed, and the predetermined speed> the second predetermined speed), the target master pressure is set to 0 when the request for the wheel pressure shifts from pressure increase to holding You may do it. Once the wheel pressure is increased by the master pressure, the wheel pressure can be held by the differential pressure control valve 51 or the pressure increase valve 52, so the master pressure may be set to zero. This makes it possible to suppress overshoot more reliably. In the case of extremely low speed, even if there is an increase in stepping, it can be dealt with only by pressurization by the actuator 5. The effect of the hysteresis is more pronounced as the hydraulic braking force (wheel pressure) is smaller. Therefore, as described above, by changing the reduction range in accordance with the vehicle speed (for example, setting a plurality of reduction ranges), it is possible to take measures against hysteresis depending on the situation. The determination time of the vehicle speed may be at the start of the braking operation, at the switching of control, or at every predetermined time.

  Further, the upstream ECU 6 and the downstream ECU 6A may be realized by one ECU. Further, the target setting unit 62 may be provided in the downstream ECU 6A or in a new ECU. Further, the configuration of the regulator 44 may be a configuration using a spool. Further, the target setting process of the present embodiment can also be said to be a specific target setting process performed in a specific situation such as when the vehicle speed is equal to or less than a predetermined speed (when the regenerative braking force is equal to or less than a predetermined value). The target setting process can also be applied to a vehicle without the regenerative braking device 8. In addition, when the wheel pressure is increased, the target master pressure may be smaller than the target wheel pressure, but the motor 90 is driven accordingly, and the improvement in quietness is smaller than in the case of following. Also, the target setting process may be executed without restriction by the vehicle speed. The target setting unit 62 may set the target master pressure and the target wheel pressure.

DESCRIPTION OF SYMBOLS 1 ... Master cylinder, 1A ... Servo chamber (drive chamber), 1D ... 1st master chamber (master chamber), 1E ... 2nd master chamber (master chamber), 14 ... 1st master piston (piston), 15 ... 2nd Master piston (piston), 4 ... Servo pressure generator (drive pressure supply unit), 5 ... Actuator, 51, 91 ... Differential pressure control valve (holding valve), 52, 53, 92, 93 ... Pressure increasing valve (holding valve) , 54, 55, 94, 95 ... pressure reducing valve, 541-544 ... wheel cylinder, 57, 97 ... pump (liquid pressure supply unit), 6 ... upstream ECU (first control unit), 62 ... target setting unit, 6A ... downstream side ECU (second control unit), 8 ... regenerative braking device, 90 ... motor (hydraulic pressure supply unit), BF ... braking device for vehicle.

Claims (4)

A driving chamber generating a driving pressure for driving a piston, and a master cylinder having a master chamber generating a master pressure by driving the piston;
A drive pressure supply unit that generates the drive pressure in the drive chamber;
Pressure increase control for increasing the drive pressure, holding control for holding the drive pressure, or reducing the drive pressure is performed based on a target master pressure that is a target value of the master pressure, by controlling the drive pressure supply unit. A first control unit that executes pressure reduction control;
A hydraulic pressure supply unit for supplying a brake fluid to a hydraulic pressure passage connecting the master chamber and the wheel cylinder;
A holding valve disposed in the hydraulic pressure passage for holding the hydraulic pressure of the wheel cylinder;
A pressure reducing valve for reducing the hydraulic pressure of the wheel cylinder held by the holding valve;
The fluid pressure supply unit such that the fluid pressure of the wheel cylinder becomes the target wheel pressure based on the master pressure or the target master pressure and a target wheel pressure that is a target value of the fluid pressure of the wheel cylinder. A second control unit that controls the holding valve and the pressure reducing valve;
And the driving pressure supply unit is configured to have a hysteresis in which the driving pressure fluctuates for a predetermined period from when the pressure increasing control or the pressure reducing control shifts to the holding control, ,
When holding or reducing the hydraulic pressure of the wheel cylinder, the target master pressure is set so that the target master pressure becomes smaller than the target wheel pressure as compared to the case where the hydraulic pressure of the wheel cylinder is increased. A vehicle braking device comprising a target setting unit that executes a target setting process of setting   The target setting unit sets the target master pressure such that the target master pressure in the case of holding or reducing the hydraulic pressure of the wheel cylinder becomes smaller relative to the target wheel pressure as the vehicle speed decreases as the target setting process. The vehicle braking device according to claim 1, wherein the pressure is set. It has a regenerative braking system that generates regenerative braking force on the wheels,
The vehicle braking device according to claim 1, wherein the target setting unit executes the target setting process when the regenerative braking force is equal to or less than a predetermined value. The fluid pressure supply unit includes a pump that discharges the brake fluid to the fluid pressure passage, and a motor that drives the pump.
The target setting unit sets the target master pressure so that the target master pressure follows the target wheel pressure as the target setting process when the fluid pressure of the wheel cylinder is increased.
The vehicle braking device according to any one of claims 1 to 3, wherein the second control unit stops the motor when the target setting process is performed.

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