JPH1016743A - Wheel brake fluid pressure control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable a pressure increasing gradient during re-increasing of a rear wheel brake fluid pressure to be equal to a pressure increasing during re-increasing of a front wheel brake hydraulic pressure and further to enable a size of a major component element of a first piston pump to be equal to a size of a major component element of a second piston pump. SOLUTION: A pump efficiency of a piston pump 30 is made lower than a pump efficiency of a piston pump 24 by a method whereon a volume of a pump chamber 303 of the piston pump 30 for use in flowing brake liquid in a reservoir 28 into rear wheel brakes 18, 19 is made to be larger than a volume of a pump chamber 243 of a piston pump 24 for use in flowing brake fluid in a reservoir 21 into front wheel brakes 15, 16 and then a discharging volume of the piston pump 30 is made to be lower than a discharging volume of the piston pump 24.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wheel brake hydraulic pressure control device for preventing a wheel from locking when a vehicle equipped with a hydraulic brake device is braked.

[0002]

2. Description of the Related Art Various types of wheel brake fluid pressure control devices of this type are known. However, such a device is provided in a first communication passage for communicating a first pressure generating chamber of a master cylinder with a front wheel brake. The front wheel brake is cut off from the first pressure generating chamber of the master cylinder by the first control valve installed and communicates with the first reservoir, so that the brake fluid in the front wheel brake flows out to the first reservoir and the front wheel brake fluid is released. While reducing the pressure, the front wheel brake is cut off from the first pressure generating chamber and the first reservoir of the master cylinder by the first control valve, and the brake fluid in the first reservoir flows into the front wheel brake by the first piston pump. This causes the front wheel brake fluid pressure to be increased again, so that the pressure in the second communication passage connecting the second pressure generation chamber of the master cylinder and the rear wheel brake is increased. The rear wheel brake is shut off from the second pressure generating chamber of the master cylinder by the second control valve disposed and communicates with the second reservoir, so that the brake fluid in the rear wheel brake flows out to the second reservoir and the rear wheel brake fluid is released. The pressure is reduced, the rear wheel brake is cut off from the second pressure generating chamber and the second reservoir of the master cylinder by the second control valve, and the brake fluid in the second reservoir flows into the rear wheel brake by the second piston pump. There is known a wheel brake fluid pressure control device which is configured to re-increase the rear wheel brake fluid pressure by causing the first piston pump and the second piston pump to be driven by a single drive shaft. For example, Japanese Patent Application Laid-Open
No. 25833.

In the wheel brake fluid pressure control apparatus described in Japanese Patent Application Laid-Open No. 60-25833, when the second piston pump is set to the same size as the first piston pump, the rear wheel brake is controlled from the second control valve. When the pressure increase of the hydraulic circuit from the first control valve to the front wheel brake is smaller than that of the hydraulic circuit from the first control valve to the front wheel brake. The diameter of the piston of the second piston pump is set to be smaller than the diameter of the piston of the first piston pump in consideration of the fact that the gradient becomes too large and the rear wheel is likely to relock.

[0004]

However, the wheel brake fluid pressure control device described in Japanese Patent Application Laid-Open No. 60-25833 discloses the size of the main components of the first piston pump and the size of the main components of the second piston pump. The difference in size is disadvantageous in terms of cost and manufacturing control as compared with the case where the size of the main components of the first piston pump and the size of the main components of the second piston pump are the same.

The invention of this application makes it possible to make the pressure increase gradient when the rear wheel brake fluid pressure is increased again equal to the pressure increase gradient when the front wheel brake fluid pressure is increased again.
It is an object of the present invention to provide a wheel brake fluid pressure control device in which the size of the main components of the first piston pump and the size of the main components of the second piston pump can be made the same.

[0006]

According to a first aspect of the present invention, there is provided a wheel brake fluid pressure control device for communicating a first pressure generating chamber of a master cylinder with a front wheel brake. The front wheel brake is cut off from the first pressure generating chamber of the master cylinder by the first control valve installed in the middle of the communication passage and communicates with the first reservoir, so that the brake fluid in the front wheel brake flows out to the first reservoir. The front wheel brake fluid pressure is reduced by the first control valve, the front wheel brake is cut off from the first pressure generating chamber and the first reservoir of the master cylinder by the first control valve, and the brake fluid in the first reservoir is forwarded by the first piston pump. The front wheel brake fluid pressure is increased again by flowing into the wheel brake, and the second pressure generating chamber of the master cylinder communicates with the rear wheel brake. The rear wheel brake is disconnected from the second pressure generation chamber of the master cylinder by the second control valve provided in the middle of the communication passage and communicates with the second reservoir, so that the brake fluid in the rear wheel brake flows out to the second reservoir. To reduce the rear wheel brake fluid pressure, to disconnect the rear wheel brake from the second pressure generating chamber and the second reservoir of the master cylinder by the second control valve, and to release the brake fluid in the second reservoir by the second piston pump. Wheel brake fluid pressure configured to re-intensify rear wheel brake fluid pressure by flowing into the wheel brake and configured to drive the first piston pump and the second piston pump by a single drive shaft In the control device, the volume of the second piston pump is set to be larger than the volume of the pump chamber of the first piston pump.

In the wheel brake fluid pressure control device having such a structure, since the brake fluid is actually compressible, the pump efficiency of the second piston pump becomes lower than that of the first piston pump, and the The discharge amount of the second piston pump when driving the first piston pump and the second piston pump depending on the shaft is smaller than the discharge amount of the first piston pump. Therefore, even when the diameter of the piston of the first piston pump and the diameter of the piston of the second piston pump are set to be the same, the amount of brake fluid flowing into the rear wheel brake by the operation of the second piston pump is increased by the operation of the first piston pump. It becomes smaller than the amount of brake fluid flowing into the front wheel brake. The decrease amount of the discharge amount of the second piston pump with respect to the discharge amount of the first piston pump is changed by changing the increase amount of the volume of the pump chamber of the second piston pump with respect to the volume of the pump chamber of the first piston pump. Therefore, the ratio of the discharge amount of the second piston pump to the discharge amount of the first piston pump can be changed from the second control valve to the rear wheel with respect to the amount of fluid consumed during pressure increase in the hydraulic circuit from the first control valve to the front wheel brake. By setting it equal to the ratio of the amount of fluid consumed when increasing pressure in the hydraulic circuit up to the brake, the pressure increase gradient when re-increasing the rear wheel brake fluid pressure is increased when the front wheel brake fluid pressure is re-increased. It can be equivalent to a pressure gradient.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the invention according to the present application will be described below with reference to the drawings.

FIG. 1 is a diagram schematically showing a hydraulic brake device for an automobile. In FIG. 1, a brake pedal 11 is connected to a tandem master cylinder 13 via a booster 12, and the brake operation force applied to the brake pedal 11 is doubled by the booster 12 and input to the tandem master cylinder 13. One of the two pressure generating chambers of the tandem master cylinder 13 is connected to the communication passage 1.
4 communicates with the front left wheel brake 15 and the front right wheel brake 16, and the other pressure chamber of the two pressure generating chambers of the tandem master cylinder 13 communicates with the rear left wheel brake 18 and the rear right wheel brake 19 through the communication passage 17. Communicated.

A normally-open solenoid valve 20 for selectively closing the communication passage 14 for anti-lock control of the hydraulic pressure of the wheel brakes 15 and 16, and a wheel brake 15,
A normally closed solenoid valve 2 for selectively communicating a portion between the solenoid valve 16 and the solenoid valve 20 and a discharge path 22 communicating with the first reservoir 21.
3 and the brake fluid flowing into the first reservoir 21 from the communication passage 14 through the solenoid valve 23 and the discharge passage 22.
A first piston pump 24 that flows into a portion between the wheel brakes 15 and 16 and the solenoid valve 20, and a check valve 25 for returning brake fluid that is connected to the communication passage 14 in parallel with the solenoid valve 20.
Is provided. The solenoid valves 20, 23 constitute a first control valve.

The first piston pump 24 includes a cylinder 24
1, a piston 242 disposed in a cylinder 241 in a liquid-tight and slidable manner, and a cylinder 241 and a piston 242.
, An inlet valve 244, an outlet valve 245, and a drive shaft 246 having an eccentric portion. The pump chamber 243 is connected to the first through the inlet valve 244.
It is connected to the reservoir 21 and to the communication passage 14 via the outlet valve 245. The drive shaft 246 is an electric motor 26
Driven by

A normally open solenoid valve 27 for selectively closing the communication passage 17 for anti-lock control of the hydraulic pressure of the wheel brakes 18 and 19, and a wheel brake 18 and
A normally closed solenoid valve 3 for selectively communicating a portion between the solenoid valve 19 and the solenoid valve 27 and a discharge path 29 communicating with the second reservoir 28.
0, the brake fluid flowing from the communication passage 17 through the solenoid valve 27 and the discharge passage 29 into the second reservoir 28
A first piston pump 31 that flows into a portion between the wheel brakes 18 and 19 and the solenoid valve 27, and a check valve 32 for returning brake fluid that is connected to the communication passage 17 in parallel with the solenoid valve 27.
Is provided. The solenoid valves 27 and 31 constitute a second control valve.

The second piston pump 30 includes a cylinder 30
1, a piston 302 disposed in a cylinder 301 in a liquid-tight and slidable manner, and a cylinder 301 and a piston 302
, An inlet valve 304, an outlet valve 305, and a drive shaft 246. The pump chamber 243 is connected to the second reservoir 28 via an inlet valve 244 and has an outlet. It is connected to the communication passage 17 via the valve 245.

The piston 24 of the first piston pump 24
2. The inlet valve 244 and the outlet valve 245 have the same size as the piston 302, the inlet valve 304 and the outlet valve 305 of the second piston pump 30, respectively.

The cylinder 301 of the second piston pump 30
Is longer than the cylinder 241 of the first piston pump 24, so that the volume of the pump chamber 303 of the second piston pump 30 is
Greater than 3 volumes.

When the brake pedal 11 is operated and the hydraulic pressure is applied from the master cylinder 13 to the wheel brakes 15, 16, 18, 19, the front wheel brake 1
The hydraulic pressures of 5 and 16 are maintained by turning on (closing) the solenoid valve 20, and while the solenoid valve 20 is kept on, the solenoid valve 2
By turning on (opening) the front wheel brake 3, the front wheel brake 15,
The brake fluid in the tank 16 flows into the first reservoir 21 to be reduced in pressure. After the pressure is reduced, the solenoid valve 23 is turned off while the solenoid valve 20 is kept on, and the first piston pump 24 is driven by the electric motor 26 to drive the first reservoir. When the brake fluid in the cylinder 21 flows into the front wheel brakes 15 and 16, the pressure is increased again. When the solenoid valve 20 is turned off during the pressure increase, the pressure is increased suddenly. Similarly, the hydraulic pressure of the rear wheel brakes 18, 19 is maintained by turning on (closing) the solenoid valve 27, and the solenoid valve 2
By turning on (opening) the solenoid valve 31 while maintaining the ON state of the brake valve 7, the brake fluid in the rear wheel brakes 18 and 19 flows out to the second reservoir 28 to reduce the pressure. While the solenoid valve 31 is turned off and the second piston pump 30 is driven by the electric motor 26 to release the brake fluid in the second reservoir 28 to the rear wheel brakes 18 and 19.
When the pressure rises again, the solenoid valve 2
If the switch 7 is turned off, the pressure will increase rapidly again.

The electric motor 26 keeps driving both piston pumps from the start to the end of the anti-lock control. Therefore, after the start of the anti-lock control, the hydraulic pressure of the front wheel brakes 15, 16 is controlled by the solenoid valves 20, 23. On,
The pressure is reduced and increased again by turning off the rear wheel brake 18,
The hydraulic pressure of 19 is reduced and increased again by turning on and off the solenoid valves 27 and 31.

The pressure increasing gradient when the hydraulic pressure of the front wheel brakes 15, 16 is being re-intensified is equal to the pressure increasing gradient when the hydraulic pressure of the rear wheel brakes 18, 19 is being re-intensified. Is desirable.

When the hydraulic pressure of the front wheel brakes 15, 16 is being re-intensified, the pressure increase gradient is equal to the pressure-consuming consumption amount Q of the hydraulic circuit from the solenoid valves 20, 23 to the front wheel brakes 15, 16.
1 and the amount of brake fluid (discharge rate of the first piston pump 24) flowing into the front wheel brakes 15, 16 from the first reservoir 21 by the operation of the first piston pump 24. Similarly, when the hydraulic pressure of the rear wheel brakes 18 and 19 is being re-intensified, the pressure increase gradient is equal to the pressure-consuming consumption liquid amount Q2 of the hydraulic circuit from the solenoid valves 27 and 31 to the rear wheel brakes 18 and 19. It is determined by the amount of brake fluid (discharge amount of the second piston pump 30) flowing from the second reservoir 28 to the rear wheel brakes 18 and 19 by the operation of the second piston pump 30. The second with respect to the discharge amount of the first piston pump 24
Change the ratio of the discharge amount of the piston pump 30 to the amount of liquid consumed during pressure increase Q
By setting it equal to the ratio of the pressure-increasing liquid consumption Q2 to 1, the pressure-increasing gradient when the hydraulic pressure of the front wheel brakes 15, 16 is re-intensified and the hydraulic pressure of the rear wheel brakes 18, 19 are reduced. The pressure increase gradient when the pressure is increased again becomes equal.

Since the amount of liquid consumed during pressure increase is generally larger in the front wheel brake than in the rear wheel brake, the discharge amount of the second piston pump 30 must be smaller than the discharge amount of the first piston pump 24. is there. The diameter of the piston 242 of the first piston pump 24 and the piston 302 of the second piston pump 30 is Ap, the brake fluid compression coefficient is k, and the stroke of the piston 242 of the first piston pump 24 and the piston 302 of the second piston pump 30 is S. , The volume of the pump chamber 243 of the first piston pump 24 is Vf,
Assuming that the volume of the pump chamber 303 of the piston pump 30 is Vr, the discharge amount Qf of the first piston pump 24 is Qf = A
p × S−k × Vf, and the second piston pump 3
A discharge amount Qr of 0 is represented by Qr = Ap × S−k × Vr. From this equation, for example, Vr = Vf + (Ap ÷ 2 × k
× S), the discharge amount Q of the second piston pump 30
r becomes a half of the discharge amount Qf of the first piston pump 24.

Therefore, for example, when the ratio of the increased pressure consumption liquid amount Q2 to the increased pressure consumption liquid amount Q1 is 2: 1, V
If r = Vf + (Ap の 2 × k × S) and the ratio of the discharge amount Qr of the second piston pump 30 to the discharge amount Qf of the first piston pump 24 is set to 2: 1, the front wheel brake 15 , 16 pressure increase gradient and rear wheel brake 1
The re-pressure increase gradient of 8, 19 becomes equivalent.

The pump chamber 3 of the second piston pump 30
03 to the pump chamber 243 of the first piston pump 24.
Is not limited to the configuration in which the cylinder 301 of the second piston pump 30 is longer than the cylinder 241 of the first piston pump 24. And so on.

[0023]

The wheel brake hydraulic pressure control device according to the invention of this application makes the pressure increase gradient when the rear wheel brake hydraulic pressure is re-intensified equal to the pressure increase gradient when the front wheel brake hydraulic pressure is re-intensified. In addition, the size of the main components of the first piston pump and the size of the main components of the second piston pump can be made the same, which is advantageous in terms of cost and manufacturing control.

[Brief description of the drawings]

FIG. 1 is a diagram showing an embodiment of the invention of this application.

[Explanation of symbols]

 13 Master cylinder 14 Communication path 15, 16 Front wheel brake 17 Communication path 18, 19 Rear wheel brake 20, 23 Electromagnetic constituting first control valve Valve 21 first reservoir 24 first piston pump 243 pump chamber of first piston pump 27, 31 electromagnetic valve constituting first control valve 28 second reservoir 30 ... 2nd piston pump 303 ... Pump chamber of 2nd piston pump

Claims (3)

[Claims] The front wheel brake is connected to the first cylinder of the master cylinder by a first control valve installed in a first communication passage communicating between the first pressure generating chamber of the master cylinder and the front wheel brake.
By shutting off the pressure generation chamber and communicating with the first reservoir, the brake fluid in the front wheel brake flows out to the first reservoir to reduce the front wheel brake fluid pressure,
The front wheel brake is shut off from the first pressure generating chamber and the first reservoir of the master cylinder by the first control valve and the brake fluid in the first reservoir flows into the front wheel brake by the first piston pump. The hydraulic pressure is increased again, and the rear wheel brake is moved to the second pressure generation chamber of the master cylinder by a second control valve installed in a second communication passage communicating the second pressure generation chamber of the master cylinder with the rear wheel brake. The brake fluid in the rear wheel brake is discharged to the second reservoir to reduce the rear wheel brake fluid pressure by communicating with the second reservoir by disconnecting the rear wheel brake from the master cylinder by the second control valve. (2) Isolate from the pressure generating chamber and the second reservoir, and release the brake fluid in the second reservoir by the second piston pump into the rear wheel brake. The wheel brake fluid pressure control device is configured to re-increase the rear wheel brake fluid pressure by flowing in, and configured to drive the first piston pump and the second piston pump by a single drive shaft. A wheel brake fluid pressure control device, wherein the volume of the second piston pump is set larger than the volume of the pump chamber of the first piston pump. 2. The wheel brake hydraulic pressure control device according to claim 1, wherein the diameter of the piston of the first piston pump and the diameter of the piston of the second piston pump are set to be the same. Hydraulic pressure control device. 3. The wheel brake fluid pressure control device according to claim 1, wherein the amount of brake fluid flowing into the front wheel brake by the operation of the first piston pump is changed from the pump chamber of the second piston pump to the rear wheel. The ratio of the amount of brake fluid that flows into the brake to the amount of fluid consumed during pressure increase of the hydraulic circuit from the second control valve to the rear wheel brake relative to the amount of fluid consumed during pressure increase of the hydraulic circuit from the first control valve to the front wheel brake A wheel brake fluid pressure control device characterized in that it is set to have the same amount ratio.