JP2618672B2 - Brake fluid pressure booster - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a brake fluid pressure increasing device for reducing a pedaling force of a vehicle brake.

(Prior Art) Many modern vehicles are equipped with a booster for the purpose of reducing the pedal effort applied by a driver.

The conventional booster is integrated with the master cylinder and assists the working plunger inside this master cylinder with the engine negative pressure or the hydraulic pressure from a separate hydraulic pressure source, and is proportional to the pedal depression force. Power to the wheel cylinder. As a hydraulic brake device equipped with such a booster, there is, for example, one disclosed in Japanese Patent Application Laid-Open No. 62-1449547.

(Problems to be solved by the invention) However, in the conventional booster described above,
Since it is designed to be integrally attached to the master cylinder, there is a disadvantage that the total length of the master cylinder is inevitably increased.

In general, the master cylinder must be provided in front of the side of the driver's seat because it needs to be linked with the brake pedal in the vehicle compartment. However, since the suspension is located in this part,
Care had to be taken to avoid interference with this. This has become increasingly difficult due to the tendency of the suspension occupied area to expand with the recent sophistication of suspensions, and a solution is currently desired.

SUMMARY OF THE INVENTION It is an object of the present invention to reduce the size of a master cylinder without lowering the boosting effect on a brake device, and to increase the degree of freedom in layout in front of a driver's seat in a vehicle.

(Means for Solving the Problems) The present invention provides, as means for solving the above-mentioned problems, a first cylinder portion 3 connected to a master cylinder 2 in a casing 1 and a pipe connected to a wheel cylinder 4. A second cylinder portion 5 to be connected is provided. From the first cylinder portion 3 to the second cylinder portion 5, the pressure receiving area on the first cylinder portion 3 side is larger than the pressure receiving area on the second cylinder portion 5 side. A stepped piston 6 is formed inside the stepped piston 6, and a communication hole 7 is formed in the stepped piston 6 to communicate the first cylinder part 3 side and the second cylinder part 5 side.
Spring 8 in order to bias the
And when the stepped piston 6 moves in the direction of the second cylinder 5 by a predetermined amount, the valve 9 that closes the communication hole 7 is elastically supported. Connect the liquid supply source 10 by piping, and
A check valve 12 for closing the passage 11 from the high-pressure liquid supply source 10 is provided in the passage 11 on the side of the second cylinder unit 3.
The valve 9 and the check valve 12 are linked to each other.

(Operation) With such a configuration, when the brake fluid is first sent from the master cylinder 2 to the first cylinder portion 3, the brake fluid passes through the communication hole 7 of the stepped piston 6 retracted by the spring 8. Then, it passes through the second cylinder section 5 and is sent to the wheel cylinder 4. Wheel cylinder 4
When the hydraulic pressure on the side increases, the stepped piston 6 moves forward against the force of the spring 8 due to the difference in the pressure receiving area, and the communication hole 7 is closed by the valve 6. When the stepped piston 6 further advances in this state, the hydraulic pressure from the second cylinder portion 5 to the wheel cylinder 4 starts to increase, and at the same time, the check valve 12 linked with the valve 9 opens,
The brake fluid from the high-pressure fluid supply source 10 flows into the second cylinder unit 5. The brake fluid continues to be supplied until the stepped piston 6 is pushed back by a predetermined amount, where the force of the first cylinder 3 and the force of the second cylinder 5 are balanced, and the check valve 12 is closed. When the hydraulic pressure on the master cylinder 2 side is further increased, the forward and backward movement of the stepped piston 6 and the supply of the brake fluid from the high-pressure fluid supply source 10 are repeated, and the hydraulic pressure on the wheel cylinder 4 side is reduced by the number on the master cylinder 2 side. Doubled. When a large boosting effect is desired, the pressure receiving area of the stepped piston 6 on the first cylinder portion 3 side is increased, and the area ratio to the pressure receiving area on the second cylinder portion 5 side is set large. It is good. In this case, the flow rate of the brake fluid from the master cylinder 2 must be increased in order to obtain a predetermined stroke of the main body stepped piston 6, but the action of increasing the flow rate of the brake fluid from the high-pressure fluid supply source 10 works. Since the stroke of the stepped piston 6 is almost unnecessary, the boosting action is enhanced without increasing the flow rate from the master cylinder 2.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

The hydraulic brake shown in FIG. 2 employs two-system cross piping, and two sets of pressure boosters according to the present invention are connected in parallel to the master cylinder 2, and each pressure booster is arranged diagonally. It is connected to a certain front wheel and rear wheel wheel cylinder 4 by piping. Each pressure intensifier is connected to a high pressure liquid supply circuit as a high pressure liquid supply source 10. In the high-pressure liquid supply circuit, a connection portion for the pressure-intensifying device and a pressure switch 15 are provided in a passage connecting the pump 13 and the accumulator 14, and the pressure switch 15 is linked to a motor 16 for driving the pump 13. I have. As a result, when the pressure in the circuit decreases, the motor 16 operates and the hydraulic pressure generated by the pump 13 is stored in the accumulator 14, and the pressure decrease is compensated.

In FIG. 1, reference numeral 1 denotes a casing of a pressure booster according to the present invention. The casing 1 includes a first cylinder portion 3 connected to a master cylinder 2 by piping and a first cylinder portion connected to a wheel cylinder 4 by piping. And a stepped piston having a larger pressure receiving area on the first cylinder part 3 side than on the second cylinder part 5 side from the first cylinder part 3 to the second cylinder part 5. 6 is slidably mounted. Also, at a position substantially intermediate between the first cylinder portion 3 and the second cylinder portion 5 of the casing 1,
A relief hole 17 communicating with the atmosphere is formed, and a communication hole 7 communicating the first cylinder portion 3 and the second cylinder portion 5 is formed in the stepped piston 6, and a valve is provided at an end thereof. seat
18 are provided. A spring 8 for urging the stepped piston 6 in the direction of the first cylinder portion 3 is provided in the second cylinder portion 5.

A valve 9 is provided inside the second cylinder portion 5 so as to face a valve seat 18 of the stepped piston 6, and the valve 9 is urged in the direction of the first cylinder portion 3 by a spring 19. The moving end is regulated by the holder 20. When the stepped piston 6 is at the retracted end as shown in FIG.
The valve 9 comes into contact with the valve seat 18 as the stepped piston 6 moves forward by opening the communication hole 7 away from the valve seat 18. A rod portion 21 is integrally formed at an end of the valve 9 opposite to the stepped piston 6. Further, a pressure chamber 22 is provided in the casing 1 so as to be adjacent to the above-described second cylinder portion 5. The high-pressure chamber 22 communicates with the high-pressure liquid supply source 10 and the second cylinder unit 5 through the passage 23 and the passage 11, respectively.
The opening and closing of the passage 23 and the passage 12 are appropriately performed by the 12.

In the above configuration, when the brake pedal is depressed and the brake fluid is pumped from the master cylinder 2, the brake fluid is supplied to the second cylinder portion 5 and the wheel cylinder 4 through the communication hole 7 of the stepped piston 6. When the pressure of the wheel cylinder 4 gradually increases in this way, the stepped piston 6 starts to move forward (moves in the direction of the second cylinder portion 5), and the valve seat 18 and the valve 9 come into contact with each other and the communication hole is formed. 7 becomes blocked. Stepped piston 6 at this time
Movement is based on the difference in pressure receiving area of the first cylinder portion 3 side and the pressure receiving area of the second cylinder portion 5, the pressure receiving area A and the hydraulic pressure P _W in the second cylinder portion 5 of the force F _O valence plus the spring 8 to the product is, the process proceeds to equal to the product of the pressure receiving area a a hydraulic P _M in the first cylinder portion 3, the second cylinder portion 5 Along with this Hydraulic pressure is increased.

At this time, if indicated a relationship between balanced by the formula, and _{P M · A = P W ·} a + F O ...... (1).

When the stepped piston 6 advances in this way, the valve seat 18
At the same time, the valve 9 itself moves, and the check valve is
Press 12. As a result, the check valve 12 is opened, the brake fluid flows into the second cylinder portion 5 from the high-pressure chamber 22, and when the pressure in the high-pressure chamber 22 decreases, the check valve 24 is opened and the high-pressure liquid is supplied from the high-pressure liquid supply source 10 to the high-pressure chamber 22. Brake fluid is replenished. Then, such operations of the check valve 12 and the check valve 24 are repeated until a predetermined amount of the brake fluid is supplied to the second cylinder portion 5. When the brake fluid is supplied to the second cylinder part 5, the hydraulic pressure of the second cylinder part 5 and the wheel cylinder 4 gradually increases, and the stepped piston 6 is pushed back. And stepped piston 6
Is pushed back a predetermined amount, the check valve 12
11 is closed, and the force balance before and after the stepped piston 6 is temporarily maintained. In this state, when the depression force of the brake pedal is further applied and the hydraulic pressure of the master cylinder 2 is increased, the balance between the front and rear forces of the stepped piston 6 is again lost, and the front and rear movement of the stepped piston 6 and the check valves 12 and 24 The opening / closing operation is repeated to increase the hydraulic pressure of the second cylinder portion 5 and the wheel cylinder 4.

Such fluid pressure P _M in the master cylinder 2 and the is converted into hydraulic pressure P _W of several times higher wheel cylinder 4. Increasing slope of the fluid pressure P _W is as shown in Figure 3 for fluid pressure P _W, first only the P _M and P _W of depression of the brake pedal is increased at the same rate, from the equation (1) then were the It increases with the ratio of A / a obtained.

When the pressure of the master cylinder 2 is weakened, the stepped piston 6 retreats due to the pressure difference between the second cylinder part 5 and the first cylinder part 3, and the brake fluid passes through the communication hole 7 and passes through the master cylinder. It is sent to the cylinder 2.

In the above-described embodiment, the high-pressure liquid supply source 10 is maintained at a constant pressure by using the accumulator 14 and the pressure valve 15. However, as shown in FIG. The switch 25 is linked to the motor 16 and the relief valve 26
Can be attached to keep the pressure of the high-pressure liquid supply source 10 constant.

(Effects of the Invention) As described in detail above, according to the present invention, instead of assisting the stroke of the operating plunger of the master cylinder, the brake fluid is supplied by a device external to the master cylinder connected by piping. By increasing and increasing the pressure, the brake device can be operated with a sufficiently large boosting action without increasing the size of the master cylinder itself. As a result, the degree of freedom in the layout of the vehicle in front of the driver's seat is increased. Is extended.

Furthermore, since the flow rate of the brake fluid at the same pressure as the brake fluid increased by the stepped piston can be increased in the second cylinder portion, the supply amount of the brake fluid from the master cylinder can be reduced. As a result, an effect is obtained that the stroke of the brake pedal can be reduced.

Further, in the case of the present invention, even when the supply of hydraulic pressure from the full high-pressure liquid supply source cannot be obtained, a high brake hydraulic pressure can be generated only by increasing the amount of depression of the brake pedal.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a main part of an embodiment of the present invention, FIG. 2 is a schematic diagram showing a hydraulic pipe according to an embodiment of the present invention, and FIG. FIG. 4 is a diagram showing the relationship between the hydraulic pressure of a master cylinder and the hydraulic pressure of a wheel cylinder when a pressure device is used, and FIG. 4 is a schematic diagram showing a hydraulic pipe of another embodiment. DESCRIPTION OF SYMBOLS 1 ... Casing, 2 ... Master cylinder, 3 ... First cylinder part, 4 ... Wheel cylinder, 5 ... Second cylinder part, 6 ... Stepped piston, 7 ... Communication hole, 8 ... ... Spring, 9 ... Valve, 10 ... High-pressure liquid supply source, 11 ... Path, 12 ... Check valve,

Claims (1)

(57) [Claims] A first cylinder portion connected to a master cylinder by piping and a second cylinder portion connected to a wheel cylinder by piping are provided in a casing, and a second cylinder portion is connected from the first cylinder portion to the second cylinder portion. A stepped piston whose pressure receiving area on the first cylinder portion side is larger than the pressure receiving area on the second cylinder portion side is provided, and the stepped piston has the first cylinder portion side and the second cylinder portion side. And a spring is provided to urge the stepped piston in the direction of the first cylinder, and when the stepped piston moves in the direction of the second cylinder by a predetermined amount. Elastically supporting the valve closing the communication hole,
Further, the second cylinder section is connected to a high-pressure liquid supply source by piping, and a check valve that closes the passage from the high-pressure liquid supply side is provided in a passage on the high-pressure liquid supply side, and a check valve in the second cylinder section is provided. A brake fluid pressure increasing device wherein a valve and said check valve are linked.