JP5245778B2 - Electric brake booster, vehicle with electric brake booster, and electric brake booster - Google Patents

Description

  The present invention relates to an electric brake booster that applies a brake assist force, a vehicle with an electric brake booster, and an electric brake booster method.

As this type of technology, the technology described in Patent Document 1 is disclosed. In this publication, a booster piston is stroked by an electric motor in accordance with the stroke of the input piston.
JP 2007-112426 A

  In the above prior art, when the ABS operates, if the brake pedal position does not change when circulating the discharged brake fluid to the master cylinder, the actuator (electric motor) holds the position of the booster piston. As a result, the hydraulic pressure of the actuator increases, and the actuator consumes more current than necessary.

  The present invention has been made paying attention to the above problems, and the object of the present invention is to discharge the brake fluid of the wheel cylinder and to recirculate the discharged brake fluid to the master cylinder. It is to provide an electric brake booster that can suppress consumption.

In order to achieve the above object, in the present invention, when the hydraulic pressure control means is not performing pressure reduction control, the actuator is driven based on the stroke amount of the brake pedal, and when pressure reduction control is being performed, The hydraulic pressure of the master cylinder where the wheel is locked is calculated based on the road surface friction coefficient, and the actuator is driven based on the hydraulic pressure of the master cylinder so that the hydraulic pressure of the master cylinder can be increased to the calculated hydraulic pressure. I tried to make it.

  Therefore, when the brake fluid of the wheel cylinder is circulated to the master cylinder, the hydraulic pressure of the master cylinder is not increased more than necessary, and current consumption in the actuator can be suppressed.

  Hereinafter, the best mode for realizing the electric brake booster of the present invention will be described based on the first embodiment.

[Example 1]
A configuration of the electric brake booster 20 according to the first embodiment will be described.

[Brake system configuration]
FIG. 1 shows a vehicle 80 having the electric brake booster 20 of the first embodiment. The vehicle 80 includes an electric brake booster 20 that applies to the master cylinder M / C the force amplified with respect to the brake pedal depression force by the driver, and a hydraulic pressure that controls the hydraulic pressure supplied to each wheel cylinder W / C. The control unit 19 includes a wheel speed sensor 71 that detects the wheel speeds of the wheels 21FL, 21FR, 21RL, and 21RR, and a control unit 70 that controls the electric brake booster 20 and the hydraulic pressure control unit 19.

  The control unit 70 controls the electric motor 41 (see FIG. 3) of the electric brake booster 20 and the solenoid valves 1, 2, 3, 4 (see FIG. 2) of the hydraulic pressure control unit 19. The control unit 70 also includes wheel information from the wheel speed sensor 71, stroke information of the brake pedal BP from the brake stroke sensor 43 (see FIG. 3) of the electric brake booster 20, and electric motor 41 from the resolver 44 (see FIG. 3). Rotation position information, drive current information of the electric motor 41 from the current sensor 45 (see FIG. 3), and a master cylinder M / C fluid from a master cylinder pressure sensor (see FIG. 2) of the fluid pressure control unit 19 described later. Pressure information is input, and a command signal is output to each device based on the information.

[Configuration of hydraulic pressure control unit]
FIG. 2 is a diagram showing the configuration of the hydraulic pressure control unit 19. The brake system of the first embodiment has a piping structure called X piping, which is composed of two systems, a P system and an S system. P system has left front wheel cylinder W / C (FL) and right rear wheel cylinder W / C (RR), S system has right front wheel cylinder W / C (FR), rear left It has a wheel cylinder W / C (RL). Further, the pump mechanism P is provided as a brake fluid pressure source different from the master cylinder M / C. The pump mechanism P includes a pump PP and a pump PS provided in the P system and the S system, and the pump PP and the pump PS. Has an electric motor M for driving.

  Between the master cylinder M / C and the suction side of the pump mechanism P, there are oil passages 10P, 10S. Each oil passage 10 has gate-in valves 1P, 1S which are normally closed solenoid valves. ing. Check valves 5P and 5S are provided between the gate-in valve 1 and the pump mechanism P. Each check valve 5 allows the flow of brake fluid in the direction from the gate-in valve 1 to the pump mechanism P, and in the opposite direction. The flow of is prohibited. A master cylinder pressure sensor 18 that detects the hydraulic pressure of the master cylinder M / C is provided in the oil passage 10S.

  Oil paths 12P and 12S are provided between the master cylinder M / C and each wheel cylinder W / C, and each oil path 12 has gate-out valves 2P and 2S which are normally open solenoid valves. The oil passages 17P and 17S that bypass each gate-out valve 2 are provided. Each oil passage 17 has check valves 8P and 8S. Each check valve 8 allows the flow of brake fluid in the direction from the master cylinder M / C side to the wheel cylinder W / C, and the flow in the opposite direction. Ban.

  Further, each oil passage 12 has a pressure-increasing / holding valve 3FL, 3RR, 3FR, which is a normally open solenoid valve corresponding to each wheel cylinder W / C, on the wheel cylinder W / C side from the gate-out valve 2. 3RL. Further, each oil passage 12 has oil passages 16FL, 16RR, 16FR, and 16RL that bypass each pressure increasing / holding valve 3. This oil passage 16 has check valves 9FL, 9RR, 9FR, 9RL, and each check valve 9 allows the flow of brake fluid in the direction from the wheel cylinder W / C to the pump mechanism P, and in the opposite direction. Prohibit flow.

  Oil paths 11P and 11S are provided between the discharge side of the pump mechanism P and the oil path 12, and the oil path 11 and the oil path 12 are between the gate-out valve 2 and the pressure increasing / holding valve 3. Have joined. Each oil passage 11 has check valves 6P and 6S between the junction with the oil passage 12 and the pump mechanism P. Each check valve 6 is directed from the pump mechanism P to the pressure increasing / holding valve 3. Allow the flow of brake fluid in the direction and prohibit the flow in the opposite direction.

  Reservoirs 15P and 15S are provided on the suction side of the pump mechanism P, and oil passages 14P and 14S are provided between the reservoir 15 and the pump mechanism P. Further, check valves 7P and 7S are provided between the reservoir 15 and the pump mechanism P. Each check valve 7 allows the flow of brake fluid in the direction from the reservoir 15 to the pump mechanism P, and flows in the opposite direction. Is prohibited.

  Oil passages 13 </ b> P and 13 </ b> S are provided between the wheel cylinder W / C and the oil passage 14, and the oil passage 13 and the oil passage 14 merge between the check valve 7 and the reservoir 15. Each oil passage 13 has pressure reducing valves 4FL, 4RR, 4FR, 4RL which are normally closed solenoid valves.

[Configuration of electric brake booster]
FIG. 3 is a partial cross-sectional view of the electric brake booster 20.
The electric brake booster 20 includes a master cylinder M / C, a main piston 30 that is operated by a brake operation force input to the brake pedal BP by a driver, and a booster piston 50 that is operated by a thrust generating mechanism 40. .

  The thrust generating mechanism 40 includes an electric motor 41, a screw shaft 42 that transmits the thrust of the electric motor 41 to the booster piston 50, and a brake stroke sensor 43 that detects the stroke amount of the brake pedal BP.

  The electric motor 41 is a hollow DC brushless motor, and includes a stator 41a fixed to the inner wall of the housing 60 and a rotor 41b having a ball screw groove 41c on the inner peripheral side. A resolver 44 is provided to detect the rotational position of the electric motor 41.

  On the outer peripheral side of the screw shaft 42, a ball 42b that meshes with the ball screw groove 41c of the rotor 41b is rotatably held. When the electric motor 41 is driven, the rotational force of the rotor 41b is transmitted as axial thrust to the screw shaft 42 via the ball 42b. The screw shaft 42 has a hollow portion 42a, and the large-diameter portion 30b of the main piston 30 is accommodated in the hollow portion 42a. The large-diameter portion 30b of the main piston 30 is connected to the brake pedal BP by the push rod 31, and the main piston 30 advances and retreats according to the stroke of the brake pedal BP.

  The electric motor 41 side end portion of the booster piston 50 is in contact with the screw shaft 42, and the booster piston 50 moves as the screw shaft 42 moves. The booster piston 50 has a hollow portion 50a, and the small diameter portion 30a of the main piston 30 is accommodated in the hollow portion 50a. The small diameter portion 30 a of the main piston 30 has a seal member 30 c that slides with the inner peripheral surface of the hollow portion 50 a of the booster piston 50.

  The master cylinder M / C has a bottomed cylinder body 61. In the cylinder body 61, a main piston 30 and a booster piston 50 as primary pistons, and a secondary piston 51 that forms a pair with the booster piston 50 are accommodated so as to be slidable with respect to the inner wall of the cylinder body 61. The booster piston 50 and the secondary piston 51 have seal members 50b and 51a that slide on the inner peripheral surface of the cylinder body 61, respectively.

  The main piston 30, the booster piston 50, and the secondary piston 51 divide the cylinder body 61 into two primary hydraulic chambers 61a and a secondary hydraulic chamber 61b. Between the booster piston 50 and the secondary piston 51, and between the secondary piston 51 and the bottom surface of the cylinder body 61, springs 62a and 62b are provided, and the secondary piston 51 is located between the end surface of the booster piston 50 and the bottom surface of the cylinder body 61. It is energized to be located near the center.

  As the main piston 30, booster piston 50 and secondary piston 51 move, the brake fluid contained in the primary hydraulic chamber 61a and the secondary hydraulic chamber 61b is transferred to each wheel cylinder W / C via the brake hydraulic circuit. Moving.

  The small-diameter portion 30a of the main piston 30 is smaller in diameter than the inner circumference of the hollow portion 50a of the booster piston 50, and the large-diameter portion 30b is larger in diameter than the inner circumference of the booster piston 50. The diameter is smaller than the diameter of the inner periphery of the shaft 42.

  In a state where the brake is not operated, the end surface 30d on the master cylinder M / C side of the large diameter portion 30b of the main piston 30 and the end surface 50c on the brake pedal BP side of the booster piston 50 are positioned apart from each other in the axial direction. ing. Thereby, at the time of an automatic brake operation, only the booster piston 50 moves and the main piston 30 and the brake pedal BP are prevented from moving.

[ABS control]
The brake system of the first embodiment is equipped with ABS, and the control unit 70 performs ABS control. An outline of the ABS control performed in the first embodiment will be described.

(1) Normal brake / pressure increase control When a brake operation is performed by the driver, the brake fluid pressure is increased to the wheel cylinder W / C by the master cylinder M / C, and the brake of each wheel 21 is operated.

(2) Depressurization control When the brake slip is applied, if the wheel slip rate exceeds a predetermined value (the range in which the road surface friction coefficient μ decreases) and the tendency of the wheels to lock increases, the pressure increase / hold valve 3 is closed and the pressure reduction valve 4 is opened Then, the brake fluid pressure of the wheel cylinder W / C is discharged to the reservoir 15, and the brake is released to reduce the slip ratio of the wheel.
The brake fluid discharged to the reservoir 15 is circulated to the master cylinder M / C by the pump P.

(3) Holding control When the wheel slip ratio is within a predetermined range (the road surface friction coefficient μ is close to the maximum value) during brake operation, both the pressure increasing / holding valve 3 and the pressure reducing valve 4 are closed. Then, the brake fluid pressure on the wheel cylinder W / C side is maintained.

  As described above, high braking performance can be obtained without locking the wheel by mainly switching the normal brake control / pressure increase control, pressure reduction control, and holding control according to the wheel slip ratio.

[Brake boost control]
In the control unit 70 of the first embodiment, the electric motor 41 is controlled so that the booster piston 50 moves forward and backward according to the stroke amount of the brake pedal BP of the electric brake booster 20. That is, the booster piston 50 moves forward and backward integrally with the main piston 30 mechanically connected to the brake pedal BP.

[Brake boost control during decompression]
FIG. 4 is a flowchart showing a flow of brake boost control processing performed in the control unit 70.

In step S1, it is determined whether or not decompression control is performed in the ABS. If decompression control is being performed, the process proceeds to step S2, and if decompression control is not being performed, the process proceeds to step S8.
In step S2, information on the master cylinder pressure Pmc is input from the master cylinder pressure sensor 18, and the process proceeds to step S3.

  In step S3, a road surface friction coefficient μ is calculated, and the process proceeds to step S4. The road surface friction coefficient μ can be obtained from the wheel slip ratio S. FIG. 5 is a graph showing the relationship between the wheel slip ratio S and the road surface friction coefficient μ. As shown in FIG. 5, if the wheel slip ratio S is known, the road surface friction coefficient μ can be obtained. Here, the wheel slip ratio can be obtained as follows. Each wheel speed information is input from a wheel speed sensor 71 provided on each wheel 21. Of each wheel speed information, the wheel speed of the driven wheel is set as the vehicle body speed. A value obtained by dividing each wheel speed by the vehicle body speed is a wheel slip ratio of each wheel.

In step S4, the simultaneous lock hydraulic pressure Plock of the master cylinder M / C that locks both the front wheels (wheels 21FL, 21FR) and the rear wheels (wheels 21RL, 21RR) is calculated, and the process proceeds to step S5.
Fig. 6 shows the relationship between the hydraulic pressure of the front wheel cylinders W / C (FL) and W / C (FR) and the hydraulic pressure of the rear wheel cylinders W / C (RL) and W / C (RR). It is a graph. The thin solid line shows the ideal relationship between the hydraulic pressure of the front wheel cylinders W / C (FL) and W / C (FR) and the hydraulic pressure of the rear wheel cylinders W / C (RL) and W / C (RR). Value. The thick solid line shows the hydraulic pressure of the front wheel cylinders W / C (FL) and W / C (FR) and the rear wheel wheel cylinders W / C (RL) and W / C (RR) of the brake system of the first embodiment. The relationship with hydraulic pressure is shown. The alternate long and short dash line indicates the hydraulic pressure of the wheel cylinder W / C at which the front wheel and the rear wheel are locked when the road surface friction coefficient μ is μ0. The two-dotted line indicates the hydraulic pressure of the wheel cylinder W / C where the front wheel is locked, and the dotted line indicates the hydraulic pressure of the wheel cylinder W / C where the rear wheel is locked.

  As shown in FIG. 6, the hydraulic pressures of the front wheel cylinders W / C (FL) and W / C (FR) and the rear wheel cylinders W / C (RL) and W / C (RR) When the relationship is at point A2, the front wheel and the rear wheel are locked together. The hydraulic pressure of the wheel cylinder W / C at this time is converted into the hydraulic pressure of the master cylinder M / C, and this is set as the simultaneous lock hydraulic pressure Plock.

In step S5, it is determined whether or not the master cylinder pressure Pmc input in step S2 is larger than the simultaneous lock hydraulic pressure Plock. If the master cylinder pressure Pmc is larger than the simultaneous lock hydraulic pressure Plock, the process proceeds to step S6. When it is smaller, the process proceeds to step S7.
In step S6, the hydraulic pressure control of the electric motor 41 is performed so as to maintain the master cylinder pressure Pmc detected in step S2, and the process ends.

In step S7, the pressure can be increased until the master cylinder pressure Pmc reaches the simultaneous lock hydraulic pressure Plock calculated in step S4. When the master cylinder pressure Pmc is increased to the simultaneous lock hydraulic pressure Plock, the simultaneous lock hydraulic pressure Plock is maintained. Thus, the electric motor 41 is controlled to end the process.
In step S8, the position of the electric motor 41 is controlled and the process is terminated. In this position control, the electric motor 41 is controlled so that the booster piston 50 advances and retracts integrally with the main piston 30.

[Brake boost control during decompression]
As described above, in the stroke control, the electric motor 41 is controlled so that the booster piston 50 advances and retracts integrally with the main piston 30. Further, in the ABS control, when the wheel slip ratio becomes high and the tendency of the wheel to lock becomes strong, the brake fluid of the wheel cylinder W / C of the wheel 21 that has become strong in the lock tendency is discharged, and the discharged brake fluid is used as the master cylinder M / C. To recirculate. Therefore, when the driver maintains the stroke amount of the brake pedal BP when circulating the brake fluid to the master cylinder M / C, the master cylinder pressure Pmc increases due to the circulating brake fluid pressure. Therefore, the master cylinder pressure Pmc is increased in spite of trying to reduce the pressure with the wheel cylinder W / C, and the power consumption becomes larger than necessary for the electric motor 41 to maintain the position of the booster piston 50. was there.

  Therefore, in the first embodiment, the control unit 70 performs stroke control for controlling the electric motor 41 in accordance with the stroke amount of the brake pedal BP, and at the time of ABS pressure reduction control by the hydraulic pressure control unit 19, the hydraulic pressure of the master cylinder M / C. Accordingly, the hydraulic pressure control for controlling the electric motor 41 is performed.

  In the stroke control of the electric motor 41, since the electric motor 41 is controlled according to the stroke amount of the brake pedal BP, the control according to the driver's intention to decelerate can be performed. However, during ABS pressure reduction control, even if the master cylinder pressure Pmc is increased in accordance with an increase in the stroke amount of the brake pedal BP, the braking force of the wheels does not increase. Therefore, during ABS pressure reduction control, fluid pressure control is performed so as not to unnecessarily increase the master cylinder pressure Pmc, and the power consumption of the electric motor 41 can be suppressed.

  Here, the driver does not decelerate the vehicle only by the stroke amount of the brake pedal BP, but decelerates the vehicle by a stepping force corresponding to the reaction force of the brake pedal BP. For this reason, it is conceivable that the electric motor 41 is hydraulically controlled even when the ABS pressure reduction control is not performed. However, since the rise of the master cylinder pressure Pmc is delayed with respect to the stroke of the brake pedal BP, the control system of the electric motor 41 is deteriorated immediately after the brake pedal BP starts the stroke. In the first embodiment, by switching between stroke control and hydraulic pressure control of the electric motor 41, power consumption of the electric motor 41 can be suppressed while avoiding deterioration of the control system of the electric motor 41.

  In addition, even if ABS depressurization control is activated only on wheels with a high locking tendency due to higher locking tendency of other wheels, there is still room to increase the braking force on other wheels (in normal vehicles, the front wheels are the rear wheels). Since the tendency to lock earlier becomes higher, even if ABS pressure reduction control is activated on the front wheels, it becomes possible to increase the braking force on the rear wheels by increasing the brake fluid pressure on the rear wheels, and the vehicle deceleration Can be increased).

  Therefore, in the first embodiment, the control unit 70 calculates the simultaneous lock hydraulic pressure Plock at which all the wheels are locked based on the road surface friction coefficient μ, and when performing the hydraulic pressure control, the control unit 70 calculates the master cylinder pressure Pmc as the simultaneous lock hydraulic pressure Plock. Until then, the electric motor 41 is controlled so that the voltage can be boosted.

  FIG. 7 is a time chart when the master cylinder pressure Pmc is lower than the simultaneous lock hydraulic pressure Plock when the ABS pressure reduction control is started. 7A shows the driver's required deceleration (stroke amount of the brake pedal BP), FIG. 7B shows the vehicle body deceleration, FIG. 7C shows the power consumption of the electric motor 41, and FIG. The brake pedal depression force, FIG. 7 (f) shows the operation / non-operation of the ABS control. A solid line is a time chart when the electric motor 41 is hydraulically controlled when the ABS pressure reduction control of the first embodiment is started, and a dotted line is a time when the position of the electric motor 41 is controlled even after the ABS pressure reduction control is started. It is a time chart.

  At time t0, the driver starts stepping on the brake pedal, and the master cylinder pressure Pmc increases. As the master cylinder pressure Pmc increases, the vehicle body deceleration increases, and the power consumption of the electric motor 41 and the brake pedal depression force increase.

  At time t1, ABS control is started for a certain wheel. At this time, the master cylinder pressure Pmc is P1 (in FIG. 6, the hydraulic pressure of the front wheel cylinders W / C (FL), W / C (FR) and the rear wheel wheel cylinders W / C (RL), W / C (RR) is the master cylinder pressure when the relationship with the hydraulic pressure is point A1. Since the hydraulic pressure P1 is lower than the simultaneous lock hydraulic pressure Plock, the master cylinder pressure Pmc can be increased to the simultaneous lock hydraulic pressure Plock.

  Thereafter, the master cylinder pressure Pmc increases due to the increase in the stroke amount of the brake pedal BP and the return of the brake fluid to the master cylinder M / C by the ABS pressure reduction control. As the master cylinder pressure Pmc increases, the vehicle body deceleration increases, and the power consumption of the electric motor 41 and the brake pedal depression force increase.

  At time t2, the master cylinder pressure Pmc becomes the simultaneous lock hydraulic pressure Plock. After the master cylinder pressure Pmc becomes the simultaneous lock hydraulic pressure Plock, the master cylinder pressure Pmc is held at the simultaneous lock hydraulic pressure Plock even if the stroke amount of the brake pedal BP increases. Even after time t2, the stroke amount of the brake pedal BP is increased and the brake fluid is recirculated to the master cylinder M / C by the ABS pressure reduction control, but the power consumption and the brake pedal depression force of the electric motor 41 are not increased.

  At time t3, the stroke amount of the brake pedal BP decreases and the master cylinder pressure Pmc decreases. As the master cylinder pressure Pmc decreases, the vehicle body deceleration decreases, and the power consumption of the electric motor 41 and the brake pedal depression force decrease.

  At time t4, the ABS control for all the wheels is completed, and the control unit 70 controls the position of the electric motor 41 according to the stroke amount of the brake pedal BP.

  As shown from time t1 to time t2 in FIG. 7, the vehicle body deceleration is increased to increase the master cylinder pressure Pmc until the simultaneous lock hydraulic pressure Plock is reached even after the ABS pressure reduction control is started. be able to.

  If the master cylinder pressure Pmc is higher than the simultaneous lock hydraulic pressure Plock at the start of ABS pressure reduction control, the vehicle body deceleration does not increase even if the master cylinder pressure Pmc is increased further.

  Therefore, in the first embodiment, the control unit 70 stores the master cylinder pressure Pmc when the hydraulic pressure control unit 19 starts to discharge brake fluid from all wheels, and stores the master cylinder pressure Pmc when performing hydraulic pressure control. The electric motor 41 is controlled so as to maintain the hydraulic pressure.

  FIG. 8 is a time chart when the master cylinder pressure Pmc is higher than the simultaneous lock hydraulic pressure Plock when the ABS pressure reduction control is started. 8A shows the driver's required deceleration (stroke amount of the brake pedal BP), FIG. 8B shows the vehicle body deceleration, FIG. 8C shows the power consumption of the electric motor 41, and FIG. Brake pedal depression force, FIG. 8 (f) shows the operation / non-operation of the ABS control. A solid line is a time chart when the electric motor 41 is hydraulically controlled when the ABS pressure reduction control of the first embodiment is started, and a dotted line is a time when the position of the electric motor 41 is controlled even after the ABS pressure reduction control is started. It is a time chart.

  At time t10, the driver starts stepping on the brake pedal, and the master cylinder pressure Pmc increases. As the master cylinder pressure Pmc increases, the vehicle body deceleration increases, and the power consumption of the electric motor 41 and the brake pedal depression force increase.

  At time t11, ABS control is started for all wheels. The master cylinder pressure Pmc at this time is P3 (in FIG. 6, the hydraulic pressures of the front wheel cylinders W / C (FL), W / C (FR) and the rear wheel cylinders W / C (RL), W / C (RR) is the master cylinder pressure when the relationship with the hydraulic pressure is point A3.

  Thereafter, even if the stroke amount of the brake pedal BP increases, the master cylinder pressure Pmc is maintained at the hydraulic pressure P3. Even after time t12, the stroke amount of the brake pedal BP is increased and the brake fluid is recirculated to the master cylinder M / C by the ABS pressure reduction control, but the power consumption and the brake pedal depression force of the electric motor 41 are not increased.

  At time t12, the stroke amount of the brake pedal BP decreases, and the master cylinder pressure Pmc decreases. As the master cylinder pressure Pmc decreases, the vehicle body deceleration decreases, and the power consumption of the electric motor 41 and the brake pedal depression force decrease.

  At time t13, the ABS control for all the wheels is completed, and the control unit 70 controls the position of the electric motor 41 according to the stroke amount of the brake pedal BP.

  As shown from time t11 to time t12 in FIG. 8, the power consumption of the electric motor 41 can be suppressed while maintaining the vehicle body deceleration.

[Effect of Example 1]
Next, effects of Example 1 are listed below.

(1) The main piston 30 that moves forward and backward by input from the brake pedal BP, the booster piston 50 that can be displaced relative to the main piston 30, the electric motor 41 that moves the booster piston 50 back and forth, the main piston 30 and / or Alternatively, the master cylinder M / C that generates hydraulic pressure by the movement of the booster piston 50, the brake stroke sensor 43 that detects the stroke amount of the brake pedal BP, the master cylinder pressure sensor 18 that detects the master cylinder pressure Pmc, and the master cylinder It is provided between the M / C and the wheel cylinder W / C, and when the lock tendency of each wheel is detected, the brake fluid of the wheel cylinder W / C of the wheel 21 which is in a lock tendency is discharged, and the discharged brake fluid is discharged. The hydraulic pressure control unit 19 circulating to the master cylinder M / C and the stroke amount of the brake pedal BP Next, the position control for controlling the electric motor 41 is performed, and the hydraulic pressure control for controlling the electric motor 41 according to the hydraulic pressure of the master cylinder M / C when the hydraulic pressure control unit 19 is operated (at the time of ABS pressure reduction control). And a control unit 70 for performing the above.
Therefore, when the hydraulic pressure control unit 19 is operated, the hydraulic pressure control is performed so that the master cylinder pressure Pmc is not increased unnecessarily, and the power consumption of the electric motor 41 can be suppressed.

  (2) The control unit 70 calculates the master cylinder pressure Pmc (simultaneous lock hydraulic pressure Plock) at which all the wheels are locked based on the road surface friction coefficient μ, and when performing the hydraulic pressure control, The pressure can be increased to the simultaneous lock hydraulic pressure Plock.

  Even after the ABS pressure reduction control is started, the vehicle body deceleration can be increased to increase the master cylinder pressure Pmc until the simultaneous lock hydraulic pressure Plock is reached.

  (3) The control unit 70 stores the master cylinder pressure when the hydraulic pressure control unit 19 starts discharging brake fluid from all the wheels, and when performing the hydraulic pressure control, the master cylinder pressure storing the master cylinder pressure Pmc. Thus, the electric motor 41 is controlled so as to be maintained.

  Therefore, the power consumption of the electric motor 41 can be suppressed while maintaining the vehicle body deceleration.

(4) In the vehicle 80, the main piston 30 that moves forward and backward by input from the brake pedal BP, the booster piston 50 that can be displaced relative to the main piston 30, an electric motor 41 that moves the booster piston 50 forward and backward, Master cylinder M / C that generates hydraulic pressure by movement of piston 30 and / or booster piston 50, brake stroke sensor 43 that detects the stroke amount of brake pedal BP, and master cylinder pressure sensor 18 that detects master cylinder pressure Pmc. And between the master cylinder M / C and the wheel cylinder W / C, when the locking tendency of each wheel is detected, the brake fluid of the wheel cylinder W / C of the wheel 21 that has a locking tendency is discharged and discharged. Fluid pressure control unit 19 for circulating the brake fluid to the master cylinder M / C and the brake pedal B In addition to performing position control for controlling the electric motor 41 according to the stroke amount, the electric motor 41 is controlled according to the hydraulic pressure of the master cylinder M / C when the hydraulic pressure control unit 19 is operated (at the time of ABS pressure reduction control). And a control unit 70 for performing hydraulic pressure control.
Therefore, when the hydraulic pressure control unit 19 is operated, the hydraulic pressure control is performed so that the master cylinder pressure Pmc is not increased unnecessarily, and the power consumption of the electric motor 41 can be suppressed.

(5) The main piston 30 that moves forward and backward by input from the brake pedal BP, the booster piston 50 that can be displaced relative to the main piston 30, the electric motor 41 that moves the booster piston 50 back and forth, the main piston 30 and / or Alternatively, the master cylinder M / C that generates hydraulic pressure by the movement of the booster piston 50, the brake stroke sensor 43 that detects the stroke amount of the brake pedal BP, the master cylinder pressure sensor 18 that detects the master cylinder pressure Pmc, and the master cylinder It is provided between the M / C and the wheel cylinder W / C, and when the lock tendency of each wheel is detected, the brake fluid of the wheel cylinder W / C of the wheel 21 which is in a lock tendency is discharged, and the discharged brake fluid is discharged. And a hydraulic control unit 19 that circulates to the master cylinder M / C. With driving the electric motor 41 in accordance with the stroke of the Rekipedaru BP, during operation of the fluid pressure control unit 19 so as to drive the electric motor 41 in response to hydraulic pressure in the master cylinder M / C.
Therefore, when the hydraulic pressure control unit 19 is operated, the hydraulic pressure control is performed so that the master cylinder pressure Pmc is not increased unnecessarily, and the power consumption of the electric motor 41 can be suppressed.

[Other embodiments]
The best mode for carrying out the present invention has been described based on the first embodiment. However, the specific configuration of the present invention is not limited to the first embodiment and does not depart from the gist of the present invention. Any change in the design of the range is included in the present invention.

  In the first embodiment, the master cylinder pressure sensor 18 that detects the master cylinder pressure Pmc is provided. This configuration may be replaced by estimating the master cylinder pressure Pmc from the power consumption of the electric motor 41 without using the master cylinder pressure sensor 18.

  FIG. 9 is a graph showing the relationship between the master cylinder pressure Pmc and the power consumption of the electric motor 41. If the relationship shown in FIG. 9 is used, the master cylinder pressure Pmc can be estimated from the power consumption of the electric motor 41. The power consumption of the electric motor 41 can be calculated from the drive current information from the current sensor 45.

This effect is described below.
(6) The current sensor 45 that detects the drive current for detecting the drive current of the electric motor 41 is provided, and the hydraulic pressure of the master cylinder M / C is obtained using the power consumption calculated from the detected drive current.
Therefore, the master cylinder pressure sensor 18 can be omitted, and the configuration of the brake hydraulic pressure circuit can be simplified.

  The master cylinder pressure sensor 18 is the master cylinder pressure detecting means of the present invention, the electric motor 41 is the actuator of the present invention, the brake stroke sensor 43 is the stroke detecting means of the present invention, the current sensor 45 is the current detecting means, and the control unit 70. Corresponds to the actuator control means, lock hydraulic pressure calculation means and hydraulic pressure storage means of the present invention.

It is a figure which shows the vehicle carrying the brake booster of Example 1. FIG. FIG. 3 is a diagram illustrating a configuration of a hydraulic pressure control unit according to the first embodiment. It is a fragmentary sectional view of the electric brake booster of Example 1. 3 is a flowchart illustrating a flow of control processing of the control unit according to the first embodiment. It is a graph which shows the relationship between the wheel slip ratio of Example 1, and a road surface friction coefficient. It is a graph which shows the relationship between the wheel cylinder hydraulic pressure of the front wheel of Example 1, and the hydraulic pressure of the wheel cylinder of a rear wheel. 3 is a time chart illustrating the operation of the first embodiment. 3 is a time chart illustrating the operation of the first embodiment. It is a graph which shows the relationship between the master cylinder pressure of Example 1, and the power consumption of an electric motor.

Explanation of symbols

18 Master cylinder pressure sensor (master cylinder pressure detection means)
19 Hydraulic control unit 20 Electric brake booster 30 Main piston 41 Electric motor (actuator)
43 Brake stroke sensor (stroke detection means)
45 Current sensor (current detection means)
50 booster piston 70 control unit (actuator control means, lock hydraulic pressure calculation means, hydraulic pressure storage means)
BP Brake pedal
M / C master cylinder
W / C Wheel cylinder

Claims (4)

A main piston that moves forward and backward by input from the brake pedal;
A booster piston that is displaceable relative to the main piston;
An actuator for moving the booster piston back and forth;
A master cylinder that generates hydraulic pressure by movement of the main piston and / or the booster piston;
Stroke detecting means for detecting a stroke amount of the brake pedal;
Master cylinder pressure detecting means for detecting the hydraulic pressure of the master cylinder;
Provided between the master cylinder and the wheel cylinder, when the locking tendency of each wheel is detected, the brake fluid of the wheel cylinder of the wheel having a locking tendency is discharged, and the discharged brake fluid is circulated to the master cylinder. Hydraulic pressure control means for performing pressure reduction control ,
When the previous SL fluid pressure control means not performing pressure reduction control, performs position control for controlling the actuator based on the stroke amount of the brake pedal, when performing the decompression control, the liquid of the master cylinder Actuator control means for performing hydraulic pressure control for controlling the actuator based on pressure;
Provided ,
The actuator control means has a lock hydraulic pressure calculation means for calculating the hydraulic pressure of the master cylinder in which all wheels are locked based on a road surface friction coefficient, and when performing the hydraulic pressure control, the hydraulic pressure of the master cylinder The electric brake booster controls the actuator so that the pressure can be increased to the hydraulic pressure calculated by the lock hydraulic pressure calculating means . The brake booster according to claim 1,
The master cylinder pressure detecting means has a current detecting means for detecting a driving current for detecting a driving current of the actuator, and obtains a hydraulic pressure of the master cylinder using power consumption calculated from the detected driving current. Electric brake booster characterized. A main piston that moves forward and backward by input from the brake pedal;
A booster piston that is displaceable relative to the main piston;
An actuator for moving the booster piston back and forth;
A master cylinder that generates hydraulic pressure by operation of the main piston and / or the booster piston;
Stroke detecting means for detecting a stroke amount of the brake pedal;
Master cylinder pressure detecting means for detecting the hydraulic pressure of the master cylinder;
A depressurization that is provided between the master cylinder and the wheel cylinder and discharges the brake fluid of the wheel cylinder of the wheel that is locked when the lock state of each wheel is detected, and circulates the discharged brake fluid to the master cylinder. Hydraulic pressure control means for controlling,
When the hydraulic pressure control means is not performing the pressure reduction control, position control is performed to control the actuator based on the stroke amount of the brake pedal, and when the pressure reduction control is being performed, the hydraulic pressure of the master cylinder is controlled. Actuator control means for performing hydraulic pressure control for controlling the actuator based on
Provided,
The actuator control means has a lock hydraulic pressure calculation means for calculating the hydraulic pressure of the master cylinder in which all wheels are locked based on a road surface friction coefficient, and when performing the hydraulic pressure control, the hydraulic pressure of the master cylinder The vehicle with an electric brake booster controls the actuator so that the pressure can be increased to the hydraulic pressure calculated by the lock hydraulic pressure calculating means . A main piston that moves forward and backward by input from the brake pedal;
A booster piston that is displaceable relative to the main piston;
An actuator for moving the booster piston back and forth;
A master cylinder that generates hydraulic pressure by operation of the main piston and / or the booster piston;
Stroke detecting means for detecting a stroke amount of the brake pedal;
Master cylinder pressure detecting means for detecting the hydraulic pressure of the master cylinder;
Provided between the front SL master cylinder and the wheel cylinder, brake fluid and discharging of the wheel cylinders of the wheels were locked when it detects the locked state of each wheel, circulates the brake fluid discharged to the master cylinder Hydraulic pressure control means for performing pressure reduction control;
Have
When the hydraulic pressure control means is not performing the pressure reduction control, the actuator is driven based on the stroke amount of the brake pedal, and when the pressure reduction control is being performed, all the wheels are locked. The hydraulic pressure of the master cylinder is calculated based on a road surface friction coefficient, and the actuator is driven based on the hydraulic pressure of the master cylinder so that the hydraulic pressure of the master cylinder can be increased to the calculated hydraulic pressure. Electric brake boost method .

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