JP6996192B2 - Vehicle braking device - Google Patents

Description

The present invention relates to a vehicle braking device.

In a vehicle braking device, for example, an ABS (anti-lock braking system) or an actuator constituting an electronic stability control system is provided with a pump for discharging (returning) the brake fluid from the wheel cylinder to the master cylinder. For example, Japanese Patent Application Laid-Open No. 7-2235225 describes slip control of a vehicle including an ABS control hydraulic pump for anti-skid control, a TCS control hydraulic pump for brake traction control, and a motor for driving them. The device is described. According to this device, the increase in the load of the motor is suppressed by prohibiting the brake traction control depending on the execution status of the anti-skid control.

Japanese Unexamined Patent Publication No. 7-22535

In a vehicle braking device provided with such a pump, when the brake fluid is supplied from the master cylinder to the wheel cylinder, the hydraulic pressure of the brake fluid is applied to the pump due to its configuration, and a load is applied to the pump itself. If high pressure brake fluid is applied to the pump during pump operation, the load may lock the motor. Therefore, in the booster on the upstream side such as a hydraulic booster or an electric booster (for example, an electric cylinder), a mechanism for adjusting the force (for example, a booster valve and a pressure reducing valve for a hydraulic booster, a motor for an electric booster) is used. By controlling it, it is possible to limit the hydraulic pressure applied to the pump.

In such a vehicle braking device, the master piston is configured to be driven according to the operation of the brake operating member even if a failure such as an electric failure occurs in the adjusting mechanism of the booster. However, when a failure occurs in the adjusting mechanism, a hydraulic pressure corresponding to the brake operation is mechanically generated (without control), and it becomes difficult to reliably limit the hydraulic pressure applied to the pump. Therefore, in the event of the above failure, the drive of the pump must be prohibited in order to avoid locking the motor. It is desired that anti-skid control using a pump can be performed while avoiding the lock of the motor even in the above-mentioned failure state.

The present invention has been made in view of such circumstances, and even if a failure occurs in the adjustment mechanism of the drive amount of the piston, the pump can be operated while avoiding the lock of the motor. The purpose is to provide the device.

The vehicle braking device of the present invention has an adjusting mechanism for adjusting the driving amount of a piston sliding in the master cylinder, a piston driving unit that drives the piston to supply brake liquid to the wheel cylinder, and a brake operating member. The brake liquid in the wheel cylinder is arranged between the master cylinder and the wheel cylinder and the piston control unit that controls the adjustment mechanism so that the driving amount of the piston increases as the operation amount of the above increases. A pump that discharges to the outside of the wheel cylinder and is driven by a motor is provided, and the piston is driven by an operating force according to the operating amount of the brake operating member separately from the operation of the piston driving unit. In the vehicle braking device, the maximum output determining unit that determines the maximum value of the output hydraulic pressure of the master cylinder, and the brake operating member of the brake operating member under the condition that the brake liquid is discharged by the pump. When the operation amount becomes a predetermined value or more, a piston drive limiting unit that limits the driving amount of the piston to a specified value or less based on the maximum value of the output hydraulic pressure determined by the maximum output determining unit is provided.

According to the present invention, for example, even if the adjustment mechanism of the piston drive unit fails, if the operation amount of the brake operating member increases during pump operation, the piston drive limiting unit adjusts the maximum output determining unit to adjust the piston. The amount of drive is limited. In other words, in a situation where high pressure is generated, by limiting the maximum value of the output hydraulic pressure from the master cylinder separately from the control to the adjustment mechanism, even if the adjustment mechanism fails, the pump will have high pressure when the pump operates. Can be suppressed from being added. According to the present invention, even if a failure occurs in the adjusting mechanism, the pump can be operated while avoiding the lock of the motor.

It is a block diagram of the braking device for a vehicle of this embodiment. It is a block diagram of the regulator of this embodiment. It is a block diagram of the actuator of this embodiment. It is explanatory drawing which shows the change of the off pressure of this embodiment. It is a flowchart which shows the flow of the drive amount limit control of this embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. Each figure used for explanation is a conceptual diagram, and the shape of each part may not always 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 (“piston drive unit”). 4), actuators 5, wheel cylinders 541 to 544, various sensors 71 to 77, an upstream side ECU 6 and a downstream side ECU 8.

The master cylinder 1 is a portion that supplies the hydraulic fluid to the actuator 5 according to the operation amount of the brake pedal (corresponding to the "brake operating member") 10, and is a main cylinder 11, a cover cylinder 12, an input piston 13, and a first. It includes a master piston 14 and a second master piston 15. The brake pedal 10 may be any brake operating means that allows the driver to operate the 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 projecting in an inward flange shape is provided near the rear side of the inner peripheral side of the main cylinder 11. The center of the inner wall portion 111 is a through hole 111a penetrating in the front-rear direction. Further, small diameter portions 112 (rear) and 113 (front) having a slightly smaller inner diameter are provided in front of the inner wall portion 111 inside the main cylinder 11. That is, the small diameter portions 112 and 113 project inwardly annularly from the inner peripheral surface of the main cylinder 11. Inside the main cylinder 11, a first master piston 14 is disposed so as to be slidably contacted with the small diameter portion 112 and movable in the axial direction. Similarly, the second master piston 15 is disposed so as to be slidably contacted with the small diameter portion 113 and movable in the axial direction.

The cover cylinder 12 is composed of a substantially cylindrical cylinder portion 121, a bellows tubular boot 122, and a cup-shaped compression spring 123. The cylinder portion 121 is arranged on the rear end side of the main cylinder 11 and is coaxially fitted to the opening on the rear side of the main cylinder 11. The inner diameter of the front portion 121a of the cylinder portion 121 is larger than the inner diameter of the through hole 111a 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 cylinder shape and can be expanded and contracted in the front-rear direction, and is assembled so as to be in contact with the rear end side opening of the cylinder portion 121 on the front side thereof. A through hole 122a is formed in the center behind the boot 122. The compression spring 123 is a coil-shaped urging member arranged around the boot 122, and the front side thereof abuts on the rear end of the main cylinder 11 and the rear side is compressed so as to be close to the through hole 122a of the boot 122. It is diametered. 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 urges the operating rod 10a 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 surface in the front and an opening in the rear. The bottom wall 131 constituting the bottom surface of the input piston 13 has a larger diameter than other parts of the input piston 13. The input piston 13 is axially slidable and liquid-tightly arranged on the rear portion 121b of the cylinder portion 121, and the bottom wall 131 enters the inner peripheral side of the front portion 121a of the cylinder portion 121.

Inside the input piston 13, an operation rod 10a interlocked with the brake pedal 10 is arranged. 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 10a projects outward through the opening on the rear side of the input piston 13 and the through hole 122a of the boot 122, and is connected to the brake pedal 10. When the brake pedal 10 is depressed, the operation rod 10a advances while pushing 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 slidably disposed on the inner wall portion 111 of the main cylinder 11 in the axial direction. The first master piston 14 is formed by integrally forming a pressure cylinder portion 141, a flange portion 142, and a protruding portion 143 in order from the front side. The pressure cylinder portion 141 is formed in a substantially cylindrical shape with a bottom having an opening in the front, has a gap between the pressure cylinder portion 141 and the inner peripheral surface of the main cylinder 11, and is in sliding contact with the small diameter portion 112. In the internal space of the pressure cylinder portion 141, a coil spring-like urging member 144 is disposed between the pressure cylinder portion 141 and the second master piston 15. The first master piston 14 is urged rearward by the urging member 144. In other words, the first master piston 14 is urged by the urging member 144 toward the set initial position.

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

Here, the "first master chamber 1D" is partitioned by the inner peripheral 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 partitioned 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 and rear ends of the flange portion 142 of the first master piston 14 divide the rear chamber into front and rear, the "second hydraulic chamber 1C" is partitioned on the front side, and the "servo chamber 1A" is on the rear side. It is partitioned. The volume of the second hydraulic chamber 1C decreases as the first master piston 14 advances, and the volume increases as the first master piston 14 retracts. 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 protruding portion 143 (rear end portion) of the first master piston 14, and the input. The "first hydraulic chamber 1B" is partitioned by the front end portion of the piston 13.

The second master piston 15 is arranged on the front side of the first master piston 14 in the main cylinder 11 so as to be slidably in contact with the small diameter portion 113 and movable in the axial direction. The second master piston 15 is integrally formed with a tubular pressure cylinder portion 151 having an opening in the front and a bottom wall 152 that closes the rear side of the pressure cylinder portion 151. The bottom wall 152 supports an urging member 144 with the first master piston 14. In the internal space of the pressurizing cylinder portion 151, a coil spring-shaped urging member 153 is arranged between the main cylinder 11 and the closed inner bottom surface 111d. The second master piston 15 is urged rearward by the urging member 153. In other words, the second master piston 15 is urged by the urging member 153 toward the set initial position. The "second master chamber 1E" is partitioned 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 11a to 11i that communicate the inside and the outside. The port 11a is formed behind the inner wall portion 111 of the main cylinder 11. The port 11b is formed at a position similar to that of the port 11a in the axial direction so as to face the port 11a. The ports 11a and 11b communicate with each other via 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 11a and the port 11b are connected to the pipe 161 and to the reservoir 171 (low voltage source).

Further, the port 11b communicates with the first hydraulic chamber 1B 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, thereby shutting off the first hydraulic chamber 1B and the reservoir 171. The port 11c is formed behind the inner wall portion 111 and in front of the port 11a, and communicates the first hydraulic chamber 1B with the pipe 162. The port 11d is formed in front of the port 11c and communicates the servo chamber 1A and the pipe 163. The port 11e is formed in front of the port 11d and communicates the second hydraulic chamber 1C with the pipe 164.

The port 11f is formed between the sealing members G1 and G2 of the small diameter portion 112, and communicates the reservoir 172 with the inside of the main cylinder 11. The port 11f communicates with the first master chamber 1D via a passage 145 formed in the first master piston 14. The passage 145 is formed at a position where the port 11f and the first master chamber 1D are cut 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 pipeline 31.

The port 11h is formed between the sealing members G3 and G4 of the small diameter portion 113, and communicates the reservoir 173 with the inside of the main cylinder 11. The port 11h communicates with the second master chamber 1E via a passage 154 formed in the pressure cylinder portion 151 of the second master piston 15. The passage 154 is formed at a position where the port 11h and the second master chamber 1E are cut 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 pipeline 32.

Further, a sealing member such as an O-ring is appropriately arranged in the master cylinder 1. The seal members G1 and G2 are arranged in the small diameter portion 112 and are in liquid-tight contact with the outer peripheral surface of the first master piston 14. Similarly, the seal members G3 and G4 are arranged at the small diameter portion 113 and are in liquid-tight contact with the outer peripheral surface of the second master piston 15. Further, the seal members G5 and G6 are also arranged between the input piston 13 and the cylinder portion 121.

The stroke sensor 71 is a sensor that detects an operation amount (stroke) in which the brake pedal 10 is operated by the driver, and transmits a detection signal to the upstream side ECU 6 and the downstream side ECU 8. The brake stop switch 72 is a switch that detects the presence / absence of operation of the brake pedal 10 by the driver with a binary signal, and transmits the 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 composed of the stroke simulator 21. The stroke simulator 21 generates reaction force hydraulic pressure in the first hydraulic chamber 1B and the second hydraulic chamber 1C in response to the operation of the brake pedal 10. The stroke simulator 21 is configured by slidably fitting the piston 212 to the cylinder 211. The piston 212 is urged rearward by the compression spring 213, and a reaction force hydraulic chamber 214 is formed on the rear surface side of the piston 212. The reaction hydraulic pressure chamber 214 is connected to the second hydraulic pressure chamber 1C via the pipe 164 and the port 11e, and the reaction force hydraulic pressure chamber 214 is further connected to the first control valve 22 and the second control via the pipe 164. It is connected to the valve 23.

The first control valve 22 is a solenoid valve having a structure that closes in a non-energized state, and its opening and closing is controlled by the upstream ECU 6. The first control valve 22 is connected between the pipe 164 and the pipe 162. Here, the pipe 164 communicates with the second hydraulic pressure chamber 1C via the port 11e, and the pipe 162 communicates with the first hydraulic pressure chamber 1B via the port 11c. Further, when the first control valve 22 is opened, the first hydraulic pressure chamber 1B is opened, and when the first control valve 22 is closed, the first hydraulic pressure chamber 1B is closed. Therefore, the pipe 164 and the pipe 162 are provided so as to communicate the first hydraulic chamber 1B and the second hydraulic chamber 1C.

The first control valve 22 is closed in a non-energized state, and at this time, the first hydraulic chamber 1B and the second hydraulic chamber 1C are shut off. As a result, the first hydraulic chamber 1B is sealed and there is no place for the hydraulic fluid to go, and the input piston 13 and the first master piston 14 are interlocked with each other while maintaining a constant separation distance. Further, the first control valve 22 is open in the energized state, and at this time, the first hydraulic chamber 1B and the second hydraulic chamber 1C are communicated with each other. As a result, the volume change of the first hydraulic chamber 1B and the second hydraulic chamber 1C due to the advance / retreat of the first master piston 14 is absorbed by the movement of the hydraulic fluid.

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

The second control valve 23 is a solenoid valve having a structure that opens in a non-energized state, and its opening and closing is controlled by the upstream ECU 6. The second control valve 23 is connected between the pipe 164 and the pipe 161. Here, the pipe 164 communicates with the second hydraulic 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 chamber 1C and the reservoir 171 in a non-energized state and does not generate reaction force hydraulic pressure, but shuts off in the energized state to generate reaction force hydraulic pressure. Let me.

The servo pressure generator 4 is a so-called hydraulic booster (boost booster), and includes a pressure reducing valve 41, a pressure boosting valve 42, a pressure supply unit 43, and a regulator 44. The pressure reducing valve 41 is a normally open type 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 of the pressure reducing valves 41 is connected to the pipe 161 via the pipe 411, and the other of the pressure reducing valves 41 is connected to the pipe 413. That is, one of the pressure reducing valves 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 hydraulic fluid is prevented from flowing out from the first pilot chamber 4D, which will be described later. Although not shown, the reservoir 171 and the reservoir 434 communicate with each other. Reservoir 171 and reservoir 434 may be the same reservoir.

The pressure boosting valve 42 is a normally closed solenoid valve (normally closed valve) that closes in a non-energized state, and the flow rate (or pressure) is controlled by the upstream ECU 6. One of the booster valves 42 is connected to the pipe 421, and the other of the booster valves 42 is connected to the pipe 422. The pressure supply unit 43 is a portion that mainly supplies a high-pressure hydraulic fluid to the regulator 44. The pressure supply unit 43 includes an accumulator (corresponding to a “high pressure source”) 431, a hydraulic pump 432, a motor 433, and a reservoir 434.

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

When the pressure sensor 75 detects that the accumulator hydraulic pressure has dropped below a predetermined ON pressure, the motor 433 is driven based on a command from the upstream ECU 6. As a result, the hydraulic pump 432 pumps the hydraulic fluid to the accumulator 431 to restore the accumulator hydraulic pressure to a predetermined value or more. Further, when the pressure sensor 75 detects that the accumulator hydraulic pressure has dropped to a predetermined off pressure or lower, the motor 433 is stopped based on the command from the upstream ECU 6. That is, the on-pressure and off-pressure of the motor 433 (accumulator 431) are set in the upstream ECU 6, and the upstream ECU 6 controls the accumulator hydraulic 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, an urging portion 443, a valve seat portion 444, a control piston 445, and a sub-piston 446. The cylinder 441 is composed 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 that closes the 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 and the outside. The lid member 441b is also formed in a substantially bottomed cylindrical shape, and each port is formed in each portion of the tubular portion facing the plurality of ports 4a to 4h.

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

The ball valve 442 is a ball-shaped valve, and is arranged 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 urging portion 443 is a spring member that urges the ball valve 442 to the opening side (hereinafter, also referred to as the 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 separates the cylinder opening side and the cylinder bottom surface side. At the center of the valve seat portion 444, a gangway 444a is formed to communicate the divided cylinder opening side and the cylinder bottom surface side. The valve seat portion 444 holds the ball valve 442 from the cylinder opening side so that the urged ball valve 442 closes the through-passage 444a. A valve seat surface 444b on which the ball valve 442 can be detachably seated (contacted) is formed in the opening on the bottom surface side of the cylinder of the gangway 444a.

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

The control piston 445 includes a substantially cylindrical main body portion 445a and a substantially cylindrical protruding portion 445b having a diameter smaller than that of the main body portion 445a. The main body portion 445a is arranged coaxially and hydraulically on the cylinder opening side of the valve seat portion 444 in the cylinder 441 so as to be slidable in the axial direction. The main body portion 445a is urged toward the cylinder opening side by an urging member (not shown). At substantially the center of the main body portion 445a in the cylinder axial direction, a passage 445c having both ends opened in the peripheral surface of the main body portion 445a and extending in the radial direction (vertical direction in the drawing) is formed. A part of the inner peripheral surface of the cylinder 441 corresponding to the opening position of the passage 445c is formed with a port 4d and is recessed in a concave shape. This recessed space is referred to as "3rd room 4C".

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

The space partitioned by the cylinder bottom surface side end surface of the main body portion 445a, the outer peripheral surface of the protruding portion 445b, the inner peripheral surface of the cylinder 441, the valve seat portion 444, and the ball valve 442 is referred to as "second chamber 4B". The second chamber 4B communicates with the ports 4d and 4e via the passages 445d and 445c and the third chamber 4C in a state where the protrusion 445b and the ball valve 442 are not in contact with each other.

The sub-piston 446 includes a sub-main body portion 446a, a first protruding portion 446b, and a second protruding portion 446c. The sub-main body portion 446a is formed in a substantially columnar shape. The sub-main body portion 446a is arranged in the cylinder 441 on the cylinder opening side of the main body portion 445a in a coaxial and liquid-tight manner so as to be slidable in the axial direction. Further, a damper mechanism may be provided at the end of the sub-piston 446 on the bottom surface side of the cylinder.

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

The space partitioned by the end surface of the sub-main body portion 446a on the bottom surface side of the cylinder, the outer peripheral surface of the first protrusion 446b, the end surface of the control piston 445 on the cylinder opening side, and the inner peripheral surface of the cylinder 441 is defined as the "first pilot chamber 4D". And. The first pilot 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, the space partitioned by the end surface of the sub-main body portion 446a on the cylinder opening side, the outer peripheral surface of the second protruding portion 446c, the lid member 441b, and the inner peripheral surface of the cylinder 441 is referred to as a "second pilot chamber 4E". The second pilot chamber 4E communicates with the port 11g via the port 4h and the pipelines 311 and 31. Each chamber 4A to 4E is filled with a hydraulic fluid. The pressure sensor 74 is a sensor that detects the servo 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.

As described above, the regulator 44 has a control piston 445 driven by the difference between the force corresponding to the pressure (also referred to as “pilot pressure”) of the first pilot chamber 4D and the force corresponding to the servo pressure, and the control piston. When the volume of the first pilot chamber 4D changes with the movement of the 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 movement amount of the control piston 445 with respect to 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 so that a liquid having a flow rate corresponding to the differential pressure between the pilot pressure and the servo pressure flows in and out of the servo chamber 1A.

As described above, the pressure reducing valve 41 and the pressure increasing valve 42 constitute a mechanism for adjusting the servo pressure, that is, an adjusting mechanism 40 for adjusting the driving amount of the master pistons 14 and 15. The pressure boosting valve 42 can also be said to be a mechanism (adjustment mechanism 40 on the pressure boosting side) for adjusting the amount of increase in the drive amount of the master pistons 14 and 15. The pressure reducing valve 41 can be said to be a mechanism for adjusting the amount of decrease in the driving amount of the master pistons 14 and 15 (adjustment mechanism 40 on the pressure reducing side). The accumulator 431 is a device that generates (accumulates) the hydraulic pressure supplied to the adjusting mechanism 40, that is, the driving force of the master pistons 14 and 15. In summary, the servo pressure generator 4 has an adjusting mechanism 40 for adjusting the driving amount of the master pistons 14 and 15 sliding in the master cylinder 1, and an accumulator 431 for generating the driving force of the master pistons 14 and 15. , A device that drives the master pistons 14 and 15 to supply the brake liquid to the wheel cylinders 541 to 544.

The actuator 5 is arranged between the first master chamber 1D and the second master chamber 1E where the master cylinder pressure (hereinafter referred to as the master pressure) is generated, and the wheel cylinders 541 to 544. The actuator 5 and the first master chamber 1D are connected by a pipeline 31, and the actuator 5 and the second master chamber 1E are connected by a pipeline 32. The actuator 5 is a device that adjusts the hydraulic pressure (wheel pressure) of the wheel cylinders 541 to 544 in response to an instruction from the downstream ECU 8. The actuator 5 executes pressurization control, depressurization control, and holding control for further pressurizing the brake fluid from the master pressure in response to a command from the downstream ECU 8. The actuator 5 executes anti-skid control (ABS control), sideslip prevention control (ESC control), or the like by combining these controls based on the command of the downstream ECU 8.

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 and 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, a wheel speed sensor 76 is installed for each wheel W. In this embodiment, front and rear piping is adopted.

The first piping system 50a includes a main pipe line A, a differential pressure control valve 51, pressure boosting valves 52 and 53, a pressure reducing pipe line B, pressure reducing valves 54 and 55, a pressure regulating reservoir 56, and a recirculation pipe line C. , A pump 57, an auxiliary pipe D, an orifice portion 58, and a damper portion 59. In the description, the term "pipeline" can be replaced with, for example, a hydraulic line, a flow path, an oil passage, a passage, a pipe, or the like.

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 provided in the main pipeline A and controlling the main pipeline A in 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 be said to be a throttled state. The differential pressure control valve 51 has a differential pressure between the hydraulic pressure on the master cylinder 1 side and the hydraulic pressure on the wheel cylinders 541 and 542, centered on the control current, according to the control current based on the instruction from the downstream ECU 8. Also called "first differential pressure") is controlled. In other words, the differential pressure control valve 51 is configured to be able to control the differential pressure between the hydraulic pressure of the master cylinder 1 side portion of the main pipeline A and the hydraulic pressure of the wheel cylinders 541 and 542 side portions of the main pipeline A. There is.

The differential pressure control valve 51 is a normally open type that is in a communicating state in a non-energized state. The larger the control current applied to the differential pressure control valve 51, the larger the first differential pressure. When the differential pressure control valve 51 is controlled to the differential pressure state and the pump 57 is driven, the hydraulic pressure on the wheel cylinders 541 and 542 side becomes larger than the hydraulic pressure on the master cylinder 1 side according to the control current. .. A check valve 51a is installed on the differential pressure control valve 51. The main pipeline A is branched 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 booster valves 52 and 53 are solenoid valves that open and close according to the instructions of the downstream ECU 8, and are normally open type solenoid valves that are in an open state (communication state) in a non-energized state. The pressure booster valve 52 is arranged in the pipeline A1, and the pressure booster valve 53 is arranged in the pipeline A2. The pressure boosting valves 52 and 53 are opened in a non-energized state during pressure boost control to communicate with the wheel cylinders 541 to 544 and the branch point X, and are energized and closed during holding control and depressurization control. And the branch point X are blocked.

The pressure reducing line B connects between the pressure boosting valve 52 and the wheel cylinders 541 and 542 in the line A1 and the pressure adjusting reservoir 56, and adjusts between the pressure increasing valve 53 and the wheel cylinders 541 and 542 in the line A2. It is a pipeline connecting to the pressure reservoir 56. The pressure reducing valves 54 and 55 are solenoid valves that open and close according to the instructions of the downstream ECU 8, and are normally closed type solenoid valves that are closed (shut off) in a non-energized state. The pressure reducing valve 54 is arranged in the pressure reducing pipe line B on the wheel cylinders 541 and 542. The pressure reducing valve 55 is arranged in the pressure reducing pipe line B on the wheel cylinders 541 and 542. The pressure reducing valves 54 and 55 are mainly energized during depressurization control to be in an open state, and the wheel cylinders 541 and 542 and the pressure regulating reservoir 56 are communicated with each other via the pressure reducing pipe line B. The pressure regulating reservoir 56 is a reservoir having a cylinder, a piston, and an urging member.

The reflux pipe C is a pipe connecting the pressure reducing pipe B (or the pressure regulating reservoir 56) and the differential pressure control valve 51 and the pressure increasing valves 52 and 53 (here, the branch point X) in the main pipe A. be. The pump 57 is provided in the return pipe line C so that the discharge port is arranged on the branch point X side and the suction port is arranged on the pressure regulating reservoir 56 side. The pump 57 is a gear-type electric pump (gear pump) driven by a motor 90. The pump 57 causes the brake fluid to flow from the pressure regulating reservoir 56 to the master cylinder 1 side or the wheel cylinders 541 and 542 sides via the reflux pipe C. Further, for example, during anti-skid control, 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 the open state. In this way, the pump 57 is arranged 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 and repeatedly executed. In the discharge process, the brake fluid sucked from the pressure regulating reservoir 56 in the suction process is supplied to the branch point X. The motor 90 is energized and driven via a relay (not shown) according to the instruction of the downstream ECU 8. The pump 57 and the motor 90 can also be said to be electric pumps.

The orifice portion 58 is a throttle-shaped portion (so-called orifice) provided in a portion between the pump 57 of the return pipe C and the branch point X. The damper portion 59 is a damper (damper mechanism) connected to a portion of the return pipe C between the pump 57 and the orifice portion 58. The damper unit 59 absorbs and discharges the brake fluid according to the pulsation of the brake fluid in the return pipe line 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 pipeline D is a pipeline connecting the pressure regulating hole 56a of the pressure regulating reservoir 56 and the upstream side (or master cylinder 1) of the differential pressure control valve 51 in the main pipeline A. The pressure adjusting reservoir 56 is configured so that the valve hole 56b is closed as the inflow amount of the brake fluid into the pressure adjusting hole 56a increases due to the increase in the stroke. A reservoir chamber 56c is formed on the pipe lines B and C sides of the valve hole 56b.

By driving the pump 57, the brake fluid in the pressure regulating reservoir 56 or the master cylinder 1 is brought into the portion between the differential pressure control valve 51 and the pressure boosting valves 52 and 53 in the main pipe line A via the return pipe line C (branch point X). ). Then, the wheel pressure is pressurized according to the control state of the differential pressure control valve 51 and the pressure boosting valves 52 and 53. In this way, 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 pressurize the wheel pressure. A pressure sensor Y for detecting the hydraulic pressure (master pressure) of the portion is installed in a portion between the differential pressure control valve 51 and the master cylinder 1 in the main pipeline A. The pressure sensor Y transmits the detection result to the upstream side ECU 6 and the downstream side ECU 8.

The second piping system 50b has the same configuration as the first piping system 50a, and is a system for adjusting the hydraulic pressure of the wheel cylinders 543 and 544 of the front wheels Wfl and Wfr. The second piping system 50b includes a main pipeline Ab corresponding to the main pipeline A and connecting the pipeline 31 and the wheel cylinders 543 and 544, a differential pressure control valve 91 corresponding to the differential pressure control valve 51, and a pressure boosting valve 52. Pressure-increasing valves 92 and 93 corresponding to 53, pressure reducing pipes Bb corresponding to pressure reducing pipe B, pressure reducing valves 94 and 95 corresponding to pressure reducing valves 54 and 55, and pressure adjusting reservoir 96 corresponding to pressure adjusting reservoir 56. , The recirculation line Cb corresponding to the recirculation line C, the pump 97 corresponding to the pump 57, the auxiliary line Db corresponding to the auxiliary line D, the orifice part 58a corresponding to the orifice part 58, and the damper part. It is provided with a damper portion 59a corresponding to 59. As for the detailed configuration of the second piping system 50b, the description of the first piping system 50a can be referred to, and thus the description thereof will be omitted.

The wheel pressure adjustment by the actuator 5 is a pressure increase control that provides the master pressure to the wheel cylinders 541 to 544 as it is, a holding control that seals the wheel cylinders 541 to 544, and a pressure adjustment reservoir 56 for the fluid in the wheel cylinders 541 to 544. It is done by executing the depressurization control to flow out to the wheel, or the pressurization control to pressurize the wheel pressure by the throttle by the differential pressure control valve 51 and the drive of the pump 57.

The upstream side ECU 6 and the downstream side ECU 8 are electronic control units (ECUs) including a CPU, a memory, and the like. The upstream ECU 6 is an ECU that executes control to the servo pressure generator 4 based on the target wheel pressure (or target deceleration) which is the target value of the wheel pressure. The upstream ECU 6 executes pressurization control, depressurization control, or holding control for the servo pressure generator 4 based on the target wheel pressure. In the pressurization control, the pressure booster valve 42 is opened and the pressure reducing 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 boosting valve 42 and the pressure reducing valve 41 are closed.

Various sensors such as a stroke sensor 71, a pressure sensor Y, 25b, 26a, 15b5, and a wheel speed sensor 76 are connected to the upstream ECU 6. The upstream ECU 6 acquires 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 side ECU 6 acquires information (during anti-skid control, etc.) regarding the control status of the actuator 5 from the downstream side ECU 8.

The downstream side ECU 8 is an ECU that executes control to the actuator 5 based on a target wheel pressure (or a target deceleration) which is a target value of the wheel pressure. The downstream side ECU 8 executes pressure increase control, depressurization control, holding control, or pressurization control with respect to the actuator 5 based on the target wheel pressure.

Here, to briefly explain each control state by the downstream side ECU 8 by taking the control for the wheel cylinder 541 as an example, in the pressure increase control, the differential pressure control valve 51 and the pressure increase valve 52 are in the open state, and the pressure reducing valve 54 is in the closed state. Become. In the pressure reducing control, the pressure increasing valve 52 is closed and the pressure reducing valve 54 is opened. In the holding control, the pressure boosting valve 52 and the pressure reducing valve 54 are closed. In the pressurization control, the differential pressure control valve 51 is in the differential pressure state (throttle state), the pressure booster valve 52 is in the open state, the pressure reducing valve 54 is in the closed state, and the pump 57 is driven.

Various sensors such as a stroke sensor 71, a pressure sensor Y, 25b, and a wheel speed sensor 76 are connected to the downstream side ECU 8. The downstream ECU 8 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 8 are connected by a communication line (not shown). The downstream side ECU 8 executes skid prevention control and anti-skid control for the actuator 5 according to a situation and a request. In the present embodiment, the stroke sensor 71 and the upstream ECU 6 are connected by a communication line Z1, the stroke sensor 71 and the downstream ECU 8 are connected by a communication line Z2, and the downstream ECU 8 and the upstream ECU 6 are connected by a communication line Z3. It is connected. For other communication lines, the display in the figure is omitted.

Briefly explaining the cooperative control, the upstream side ECU 6 sets a target deceleration based on the stroke information, and transmits the target deceleration information (corresponding to "control information") to the downstream side ECU 8 via the communication line Z3. do. The target master pressure and the target wheel pressure are determined based on the target deceleration. The upstream side ECU 6 and the downstream side ECU 8 control the hydraulic pressure of the brake fluid so that the wheel pressure approaches the target wheel pressure (deceleration approaches the target deceleration) by coordinated control. The upstream ECU 6 calculates the target deceleration based on the stroke to calculate the target master pressure, and the downstream ECU 8 calculates the target wheel pressure based on the target deceleration and applies the pressure based on the detected master pressure and the target wheel pressure. Set the pressure amount (control amount). The downstream side ECU 8 transmits a control status (during anti-skid control, etc.) to the upstream side ECU 6. The operation of the actuator 5 is limited to a specific situation (for example, during anti-skid control or sideslip prevention control), and usually, the wheel pressure may be controlled by controlling the master pressure by the upstream ECU 6.

Here, the pressurization mode of the upstream pressurizing mechanism BF1 including the master cylinder 1 and the servo pressure generator 4 will be described. A plurality of (here, three) pressurizing modes are set in the upstream pressurizing mechanism BF1. The upstream side pressurizing mechanism BF1 is configured to have a linear mode, a regulator mode, and a static pressure mode (mode when the accumulator 431 fails) as a pressurizing mode. The linear mode is a normal mode, for example, during pressurization control, the booster valve 42 is opened as described above, the servo pressure is pressurized via the regulator 44, and the master pressure is pressurized.

The regulator mode is a mode mainly executed when the electric system fails, and the first control valve 22 is closed and the first hydraulic chamber 1B is closed due to the non-energized state, and the second control valve 23 is closed. Is a mode in which the valve is opened and the second hydraulic chamber 1C communicates with the reservoir 171. As a result, the invalid stroke disappears, the reaction force hydraulic pressure becomes atmospheric pressure, and the operation of the brake pedal 10 by the driver is easily transmitted to the master pistons 14 and 15. That is, it becomes easy to link the master pressure to the brake operation. Further, in the regulator mode, the brake fluid flows from the second master chamber 1E to the second pilot chamber 4E of the regulator 44 via the pipeline 31, 311 and the port 4h according to the brake operation. As a result, the sub-piston 446 is pressed to press the control piston 445, the ball valve 442 is disengaged, the high-pressure brake fluid of the accumulator 431 is provided to the servo chamber 1A, and the driver's operation is assisted to obtain the master pressure. Is pressurized.

Specifically, in the regulator mode, the booster valve 42 fails (for example, the valve itself fails, the power system fails, etc.), and the valve closed state is maintained despite the valve opening instruction of the upstream ECU 6. Moreover, it can be said that the accumulator 431 is a mode executed when it is in a normal state. When the upstream ECU 6 detects a failure of the booster valve 42 (for example, based on the difference between the target servo pressure and the actual servo pressure), the upstream ECU 6 switches the pressurization mode from the linear mode to the regulator mode.

The static pressure mode is a mode in which assistance is impossible, for example, when the accumulator 431 has failed, and the master pressure is pressurized only by the operation of the driver. The static pressure mode can also be said to be a regulator mode in which the accumulator 431 is not operating. It can be said that there are two pressurization modes of the upstream pressurizing mechanism BF1: a linear mode in a normal state and a collapse mode in which a regulator mode and a static pressure mode are combined. The pressurization mode can be switched by the upstream side ECU 6, and even if the upstream side ECU 6 itself fails, it can be mechanically (automatically) switched according to the state of the upstream side pressurizing mechanism BF1 depending on the type of each solenoid valve. .. As described above, the vehicle braking device BF is configured so that the master pistons 14 and 15 are driven according to the stroke of the brake pedal 10 even if the servo pressure generating device 4 does not operate. In other words, the vehicle braking device BF is configured so that the master pistons 14 and 15 are driven by an operating force according to the stroke of the brake pedal 10 separately from the operation of the servo pressure generating device 4.

(Drive amount limit control)
Here, the drive amount limiting control that limits the drive amount of the master pistons 14 and 15 in a specific situation will be described. The upstream ECU 6 has a piston control unit 61, a maximum output determination unit 62, and a piston drive limiting unit 63 as main functions. The piston control unit 61 is configured to control the adjusting mechanism 40 so that the drive amount of the master pistons 14 and 15 increases as the stroke of the brake pedal 10 (for example, the detection value of the stroke sensor 71) increases. That is, in the linear mode, the piston control unit 61 controls the pressure reducing valve 41 and the pressure increasing valve 42 according to the stroke, and executes pressure increasing control, holding control, or pressure reducing control with respect to the servo pressure (master pressure). It is a part.

The maximum output determination unit 62 is a portion that determines the maximum value of the output hydraulic pressure of the master cylinder 1 (that is, the maximum value of the master pressure). The maximum output determining unit 62 is configured to maintain the maximum value of the output hydraulic pressure of the master cylinder 1 that can be generated within a predetermined range without controlling the adjusting mechanism 40. The maximum value (upper limit) of the master pressure corresponds to the maximum value of the driving force that can be output by the servo pressure generator 4, that is, the upper limit value of the accumulator hydraulic pressure. That is, the maximum output determination unit 62 of the present embodiment maintains the hydraulic pressure of the accumulator 431 within a predetermined range (lower limit value to upper limit value). Specifically, the maximum output determination unit 62 stores the off pressure (upper limit value) and on pressure (lower limit value) of the motor 433, and when the accumulator hydraulic pressure (detection value of the pressure sensor 75) exceeds the off pressure, the motor 433 Is stopped, and when the accumulator hydraulic pressure falls below the on pressure, the motor 433 is driven. The off pressure is the value of the accumulator hydraulic pressure that turns off the motor 433, and the on pressure is the value of the accumulator hydraulic pressure that turns on the motor 433.

The piston drive limiting unit 63 has a stroke (operation amount) of the brake pedal 10 under the condition that the brake fluid is discharged from the wheel cylinders 541 to 544 by the pumps 57 and 97 (hereinafter, also referred to as “decompression discharge”). When the value exceeds a predetermined value, the drive amount of the master pistons 14 and 15 is limited to a specified value or less based on the maximum value of the master pressure determined by the maximum output determination unit 62. The piston drive limiting unit 63 limits the drive amount by adjusting the maximum output determining unit 62 (here, the maximum value of the master pressure). More specifically, as shown in FIG. 4, the piston drive limiting unit 63 is set by the maximum output determining unit 62 when the stroke becomes a predetermined value or more at the time of depressurized discharge of the pumps 57 and 97 (at the time point of t1 in FIG. 4). The drive amount limiting control for reducing the turned off pressure by a predetermined pressure is executed, and the drive amount of the master pistons 14 and 15 is limited to a specified value or less. Further, when the stroke becomes less than a predetermined value (at the time of t2 in FIG. 4) after the drive amount limit control is executed, the piston drive limit unit 63 releases the drive amount limit control, that is, the off pressure of the motor 433 is released. Return to the original value (initial value). The decompression discharge of the pumps 57 and 97 can be executed, for example, during anti-skid control (ABS control) or sideslip prevention control (ESC control).

The piston drive limiting unit 63 can determine whether or not the stroke of the brake pedal 10 is equal to or greater than a predetermined value, for example, based on the detection values of the stroke sensor 71 and / or the pressure sensor 74. The piston drive limiting unit 63 of the present embodiment determines whether or not the stroke is equal to or greater than a predetermined value based on the detection value (actual servo pressure) of the pressure sensor 74. That is, the piston drive limiting unit 63 determines whether or not the stroke is equal to or greater than a predetermined value based on whether or not the servo pressure is equal to or greater than a predetermined threshold value using the servo pressure as a determination element. If the servo pressure is equal to or greater than the threshold value, the piston drive limiting unit 63 determines that the stroke is equal to or greater than a predetermined value. The predetermined value of the stroke can be set, for example, based on the stroke value when the accumulator 431 and the servo chamber 1A communicate with each other by pushing the control piston 445 in the regulator mode.

The piston drive limiting unit 63 of the present embodiment is set to execute the drive amount limiting control only when the pressurizing mode is the regulator mode. For example, when a failure of the booster valve 42 is detected, the pressurization mode is switched from the linear mode to the regulator mode, and the drive amount limit control can be executed. That is, in the piston drive limiting unit 63 of the present embodiment, when the adjusting mechanism 40 on the boosting side is out of order (in the case of the regulator mode), the pumps 57 and 97 (at least one of them) perform decompression discharge. When the stroke exceeds a predetermined value, the drive amount limit control is executed.

The flow of the drive amount limit control of the present embodiment will be described with reference to FIG. The upstream side ECU 6 determines whether or not the current state is braking (braking operation) based on the detection value of the stroke sensor 71 (S101). When the current state is braking (S101: Yes), the upstream ECU 6 determines whether or not the pressurizing mode is the regulator mode, for example, from the current pressurizing mode setting or the state of each solenoid valve (S101: Yes). S102). When the pressurizing mode is the regulator mode (S102: Yes), the upstream ECU 6 determines whether or not the stroke is equal to or greater than a predetermined value by determining whether or not the servo pressure is equal to or greater than the threshold value (S102: Yes). S103). When the servo pressure is equal to or higher than the threshold value, that is, the stroke is equal to or higher than a predetermined value (S103: Yes), the upstream ECU 6 executes the drive amount limiting control and lowers the off pressure of the motor 433 by a predetermined pressure (S104).

On the other hand, when the current state is not braking (S101: No), the pressurizing mode is not the regulator mode (S102: No), or the servo pressure is less than the threshold value (S103: No), the upstream ECU 6 is the motor 433. The off pressure is set to the initial value (original value) (S105). In step S105, the upstream ECU 6 stops the drive amount limit control and returns the off pressure to the initial value if the drive amount limit control is being executed, and sets the off pressure to the initial value if the drive amount limit control is not executed. Keep it as it is. Note that steps S101 to S103 can be described as AND conditions in one step. Further, the upstream ECU 6 may set an execution permission flag for the drive amount limit control in advance when recognizing that the pressurization mode is the regulator mode.

In summary, the servo pressure generator 4 includes an accumulator 431 that generates a driving force by hydraulic pressure with respect to the master pistons 14 and 15, and an adjusting mechanism 40 that adjusts the hydraulic pressure supplied from the accumulator 431, and has a maximum. The output determination unit 62 maintains the hydraulic pressure of the accumulator 431 between a predetermined upper limit value and a predetermined lower limit value (within a predetermined range), and the piston drive limiting unit 63 is a maximum output determination unit 62 when a predetermined condition is satisfied. The set upper limit pressure is lowered to limit the drive amount of the master pistons 14 and 15 to the specified value or less.

According to the present embodiment, for example, even if the booster valve 42 fails, if the stroke of the brake pedal 10 becomes large while the pumps 57 and 97 are operating, the piston drive limiting unit 63 is set to the maximum output determining unit 62 and is turned off. By adjusting the pressure, the drive amount of the master pistons 14 and 15 is limited. That is, in a situation where high pressure is generated, by limiting the maximum value of the output hydraulic pressure from the master cylinder 1 separately from the control to the booster valve 42, even if the adjustment mechanism 40 fails, the pump 57, It is possible to suppress the application of high pressure to the pumps 57 and 97 when the 97 is operated. According to the present embodiment, even if the adjusting mechanism 40 fails, the pumps 57 and 97 can be operated while avoiding the lock of the motor 90.

When the driver executes a brake operation of a predetermined value or more in the regulator mode, the accumulator 431 and the servo chamber 1A are mechanically communicated with each other to assist the brake operation. When this braking operation is continued, the servo pressure rises, and as a maximum value, becomes a hydraulic pressure (high pressure) corresponding to the hydraulic pressure accumulated by the accumulator 431. That is, the driving amount of the master pistons 14 and 15 becomes large, and the master pressure becomes the hydraulic pressure (high pressure) equivalent to the servo pressure. In this state, when the pumps 57 and 97 execute decompression discharge by anti-skid control or the like, a high load is applied to the pumps 57 and 97. According to the present embodiment, in such a situation, by lowering the maximum value of the accumulator hydraulic pressure, the servo pressure (corresponding to the drive amount of the master pistons 14 and 15) and the master pressure are lowered regardless of the adjustment mechanism 40. Let me. As a result, the load on the pumps 57 and 97 can be reduced and the lock of the motor 90 can be suppressed. Therefore, anti-skid control and sideslip prevention control can be executed even in the regulator mode.

(Deformation mode)
The present invention is not limited to the above embodiment. For example, in the piston drive limiting unit 63, the larger the stroke of the brake pedal 10 under the condition that the brake fluid is discharged by the pumps 57 and 97, the more the specified value (the limit value of the drive amount of the master pistons 14 and 15). May be configured to be smaller. The piston drive limiting unit 63 may set the off pressure of the motor 433 to be smaller as the stroke is larger. The adjustment of the off pressure by the piston drive limiting unit 63 may be stepped (stepwise) or linear, but from the viewpoint of quick response, it is preferable to use the stepped shape as in the present embodiment.

Further, as the execution condition (AND condition) of the drive amount limit control, "the temperature of the motor 90 for driving the pumps 57 and 97 is equal to or higher than the predetermined temperature" and "the pumps 57 and 97" are further set for the above embodiment. At least one of "is driven for a predetermined time or longer" may be added. That is, the piston drive limiting unit 63 has a stroke of the predetermined value or more under the condition that the brake fluid is discharged by the pumps 57 and 97, and the temperature of the motor 90 for driving the pumps 57 and 97 is equal to or higher than the predetermined temperature. If this is the case, the drive amount of the master pistons 14 and 15 may be limited to a specified value or less. Further, the piston drive limiting unit 63 has a stroke of the predetermined value or more under the condition that the brake fluid is discharged by the pumps 57 and 97, and the temperature of the motor 90 for driving the pumps 57 and 97 is equal to or higher than the predetermined temperature. If this is the case, the drive amount of the master pistons 14 and 15 may be limited to a specified value or less. With such a configuration, the drive amount limiting control is executed only in the situation where the pumps 57 and 97 are loaded different from the master pressure, that is, the motor 90 is more likely to be locked, and the efficiency is higher. Control is possible. The temperature of the pumps 57 and 97 (motor 90) can be estimated from, for example, detection by a temperature sensor or a driving condition. The drive time of the pumps 57 and 97 can also be grasped by the time count.

Further, the piston drive limiting unit 63 is likely to continue discharging the brake fluid by the pumps 57 and 97 for a specified time or longer after limiting the drive amount of the master pistons 14 and 15 to a specified value or less (after lowering the off pressure). If the pressure is high, the limitation (changed off pressure) may be continued regardless of the stroke of the brake pedal 10. Whether or not it is highly probable that the reduced pressure discharge of the pumps 57 and 97 will be continued for a specified time or longer can be determined based on, for example, an estimated road surface friction coefficient (hereinafter referred to as road surface μ). When the road surface μ is low, the anti-skid control is likely to be executed, and the pumps 57 and 97 are likely to operate for a specified time or longer. Therefore, the piston drive limiting unit 63 may estimate the road surface μ and determine whether or not the probability is high based on the estimation result. The road surface μ can be estimated by a known method, and can be sent (estimated) by using, for example, a detection value of an acceleration sensor or a wheel speed sensor 76 that detects acceleration in the front-rear direction of the vehicle.

Further, the piston drive limiting unit 63 may execute the drive amount limiting control by lowering the rotation speed of the motor 433. By lowering the rotation speed of the motor 433, the accumulator hydraulic pressure can be lowered (substantially lowering the upper limit value). The piston drive limiting unit 63 may be set, for example, to reduce the rotation speed of the motor 433 to a predetermined rotation speed according to a specified value. Further, "Kickback has occurred in the pumps 57 and 97" may be added as an execution condition (AND condition) of the drive amount limit control. The presence or absence of kickback can be determined, for example, by fluctuations in the servo pressure.

Further, the drive amount limiting control may be executed in the linear mode. That is, "the pressurization mode is the regulator mode" may be deleted from the execution condition of the drive amount limit control, or "the pressurization mode may be the regulator mode or the linear mode". Even in the linear mode, the load on the pumps 57 and 97 can be reduced regardless of the adjustment mechanism 40.

Further, the present invention may be applied to an electric booster. In this case, for example, the electric cylinder corresponds to the servo pressure generator (4), and the motor for driving the electric cylinder corresponds to the adjustment mechanism (40). As the maximum output determination unit (62) and the piston drive limiting unit (63), for example, a flow path and a solenoid valve for allowing brake fluid to escape are newly provided near the outlet of the master cylinder, and a control unit for controlling the solenoid valve is provided. It can also be configured by arranging (ECU). For example, the upper limit pressure for opening the solenoid valve is set in the control unit (maximum output determination unit), and the control unit (piston drive limiting unit) lowers the upper limit pressure when executing the drive amount limiting control. It may be configured in.

Further, the pumps 57 and 97 may be electric pumps other than the gear pump, such as a piston pump. Further, the upstream side ECU 6 and the downstream side ECU 8 may be configured by one ECU. Further, the actuator 5 is not provided with solenoid valves (holding valves) 51, 91, etc., so that it cannot pressurize the wheel pressure by differential pressure control (for example, it cannot execute skid prevention control), and is an anti-skid. It may be an actuator capable of executing control. That is, the actuator 5 may be a so-called ABS actuator. Further, a pedal force sensor or the like may be used to detect the operation amount of the brake pedal 10.

1 ... Master cylinder, 10 ... Brake pedal (brake operating member), 14, 15 ... Master piston (piston), 4 ... Servo pressure generator (piston drive unit), 40 ... Adjustment mechanism, 431 ... Accumulator (high pressure source), 541 to 544 ... Wheel cylinder, 57, 97 ... Pump, 6 ... Upstream ECU, 61 ... Piston control unit, 62 ... Maximum output determination unit, 63 ... Piston drive limiting unit, BF ... Vehicle braking device.

Claims (6)

A piston drive unit that has an adjustment mechanism that adjusts the drive amount of the piston that slides in the master cylinder and drives the piston to supply the brake liquid to the wheel cylinder, and the larger the operation amount of the brake operating member, the more the piston A piston control unit that controls the adjustment mechanism so that the drive amount becomes large, and the brake liquid in the wheel cylinder are discharged to the outside of the wheel cylinder, which is arranged between the master cylinder and the wheel cylinder, and a motor. A vehicle braking device including a pump driven by the piston, and the piston is driven by an operating force according to an operating amount of the brake operating member separately from the operation of the piston driving unit. ,
The maximum output determination unit that determines the maximum value of the output hydraulic pressure of the master cylinder,
When the operating amount of the brake operating member becomes a predetermined value or more under the condition that the brake fluid is discharged by the pump, the output hydraulic pressure is determined based on the maximum value determined by the maximum output determining unit. A piston drive limiting unit that limits the driving amount of the piston to a specified value or less,
A braking device for vehicles equipped with. The vehicle braking device according to claim 1, wherein the piston drive limiting unit reduces the specified value as the amount of operation of the brake operating member is larger under the condition that the brake fluid is discharged by the pump. .. When the operating amount of the brake operating member is equal to or higher than a predetermined value and the temperature of the motor is equal to or higher than a predetermined temperature under the condition that the brake fluid is discharged by the pump, the piston drive limiting unit is used. The vehicle braking device according to claim 1 or 2, wherein the driving amount of the piston is limited to the specified value or less based on the maximum value of the output hydraulic pressure determined by the maximum output determining unit. When the operation amount of the brake operating member is equal to or more than a predetermined value and the pump is driven for a predetermined time or longer under the condition that the brake fluid is discharged by the pump, the piston drive limiting unit is used. The vehicle braking device according to any one of claims 1 to 3, wherein the driving amount of the piston is limited to the specified value or less based on the maximum value of the output hydraulic pressure determined by the maximum output determining unit. When it is highly probable that the discharge of the brake fluid by the pump will continue for a specified time or longer after limiting the driving amount of the piston to the specified value or less, the piston drive limiting unit depends on the operating amount of the brake operating member. The vehicle braking device according to any one of claims 1 to 4, wherein the limitation is continued. The piston driving unit includes a high-pressure source that generates a driving force by hydraulic pressure with respect to the piston, and the adjusting mechanism that adjusts the hydraulic pressure supplied from the high-pressure source.
The maximum output determination unit maintains the hydraulic pressure of the high pressure source between a predetermined upper limit value and a lower limit value.
The one according to any one of claims 1 to 5, wherein the piston drive limiting unit lowers the upper limit value set by the maximum output determining unit to limit the driving amount of the piston to the specified value or less. Braking device for vehicles.

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