JPS6341779B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hydraulic pressure control device for a vehicle brake system.

It has long been known that the front and rear wheel braking force when braking a vehicle needs to be reduced by a predetermined ratio on the rear wheels compared to the front wheels due to the difference in the load pressing the wheels against the road surface. Various hydraulic control devices such as proportioning valves are provided for this purpose.

However, the proportioning valve
The control piston faces the output liquid chamber with different pressure receiving areas, and the control spring applies a spring force to the control piston in one direction (input liquid chamber side), while balancing the liquid pressure at a constant rate. This system slowly increases the rear wheel brake fluid pressure at a turning point, and since the only control elements are the fluid pressure and a constant spring force, the ideal brake force distribution ratio between the front and rear wheels changes as the vehicle's load carrying capacity changes. There was a problem that there could be a large deviation from the actual value.

Therefore, various devices have been devised to vary the control characteristics of the hydraulic pressure control device according to changes in the loading condition of the vehicle, and the present invention is one of these, which provides a method for controlling braking based on changes in the loading condition of the vehicle. The spring force of the control spring of the proportioning valve can be varied by taking advantage of changes in the brake fluid pressure required to obtain a constant deceleration, and the variable range can be varied depending on the characteristics of the vehicle. This makes it relatively easy to select.

That is, the present invention has a control piston which has a small hydraulic pressure receiving area in the input liquid chamber and a large hydraulic pressure receiving area in the output liquid chamber, and is biased by a spring force Fx in the direction of the output liquid chamber. The proportioning actuating mechanism controls the output hydraulic pressure to gradually increase at a turning point by moving against the spring force caused by the input hydraulic pressure, and the proportioning mechanism controls the output hydraulic pressure to gradually increase at a turning point by moving against the spring force.
A G-valve mechanism that blocks communication between a flow path connecting one of the output liquid chambers and the adjustment liquid chamber, and a control piston that applies the spring force of a control spring biased at one end to the control piston that engages the other end by a seesaw action. a spring force biasing mechanism having a link that transmits a spring force Fx, one end of which faces the adjustment fluid chamber, and the other end of which is engaged with the hold spring and the control spring. A load-responsive hydraulic pressure control for double piping in a vehicle brake system, characterized in that a piston is configured to move against these springs by hydraulic action to variably increase the spring force biasing the link of the control spring. It is a device.

The present invention will be described below based on embodiments shown in the drawings.

In the figure, 1 is a proportioning actuation mechanism that controls the brake fluid system of A and B systems in conjunction.
2 is a G valve mechanism; 3 is a spring force biasing mechanism that applies the spring force of a control spring to the control piston of the proportioning actuating mechanism through a booster; the value of the spring force is determined by the value of the G valve mechanism; It is provided to increase in proportion to the hydraulic pressure value held in the regulating liquid chamber at the time of operation.

These mechanisms will be explained in sequence below.

Proportioning operation mechanism A stepped cylinder 5 formed in the valve body 4,
Integrated cylindrical fail-safe pistons 6 and 6' are slidably fitted to 5', and the following first control piston 8 is inserted and slidably fitted into the middle cylinder 7 inside the shaft cylinder, thereby controlling the inside of the valve chamber. It is divided into A and B2 liquid systems. The interior of the system A, which is divided into two systems, includes an output liquid chamber _a2 where the tip head of the first control piston 8 faces, and an input liquid chamber _a1 through which the shaft is inserted.
The output hydraulic pressure pa 2 is divided by a valve seat 10 assembled inside the cylinder of the fail-safe piston 6, and the output hydraulic pressure pa ₂ Enter hydraulic pressure pa ₁
It is provided so that the bending point slowly rises.
11 is a hold spring for the valve seat 10;
12 is a stopper that also serves as a spring seat and restricts the degree of freedom of axial movement of the first control piston 8 relative to the fail-safe pistons 6, 6' to a constant length _l2 , 13 is a sealing member, and 14 is an input liquid chamber a. Input port connecting ₁ and A-system master cylinder, 15
is an output port that connects the output fluid chamber _a2 and the A-system rear wheel brake system.

Note that when the first control piston 8 is stationary, the spring force Fx is applied via the second control piston 16 described below.
is biased toward the tip side as shown in the figure,
When hydraulic pressure is applied, the output hydraulic pressure _is
The valve body 9 is configured to move a certain length l ₁ (<l ₂ ) so as to come into contact with the valve seat 10 to control the hydraulic pressure in the balance between pa ₂ and the B system output hydraulic pressure pb ₂ described below. There is.

The other compartment of system B, which is divided into two systems, is an output liquid chamber where the tip head of the second control piston 16 faces.
b ₂ and an input liquid chamber b ₁ into which the shaft portion is inserted, by a valve seat 18, and a valve body portion 17 formed on the second control piston 16 and the valve seat 1.
8 in cooperation with each other, the output hydraulic pressure pb ₂ is made to slowly rise at a turning point with respect to the input hydraulic pressure pb ₁ . still,
The rear end of the second control piston 16 is fitted and slid into a small-diameter medium cylinder 20 (cross-sectional area A ₂ is A ₂ <A ₁ ) of a cylindrical plug 19 fixedly assembled in the valve chamber. In addition, the spring force Fx of the control spring is biased toward the tip side through a link 39 described below, and the front end has a degree of freedom of movement relative to the first control piston 8 with a fixed length in the axial direction. l ₃ (l ₄ <
l ₃ < l ₁ + l ₄ ), and the sealing cross-sectional area of the valve body portion 17 is the first
Seal cross-sectional area of the valve body 9 of the control piston 8 A ₁
It is set the same as.

Also, the valve seat 18 is connected to the hold spring 2.
The valve body part 1 of the second control piston 16 is pressed against the end of the fail-safe piston 6' via the back-up 22 by the spring force of the second control piston 16 in the stationary state.
It is constructed to have a gap of 7 and _l4 . Furthermore, the retraction limit l ₅ of the second control piston 16
(>l ₄ ) is regulated by the stepped portion of the plug 19.

24 is a piston cup, 25 is a seal ring,
26 is a stopper, 27 is an input port that connects input liquid chamber _b1 to the B system master cylinder, and 28 is an output liquid chamber.
This is an output port that connects _b2 to the B-series rear wheel brake system.

G Valve Mechanism The G valve of this example is similar to the known one, and is guided by a guide surface 29 that forms an elevation angle θ with respect to the forward direction of the vehicle, so that the ball 30 moves inertially when a constant deceleration occurs during vehicle braking. The ball 30 comes into contact with the valve seat 31, and the contact between the ball 30 and the valve seat 31 operates to close the flow path 31a. This flow path 31a
is provided to connect between the A system output liquid chamber _a1 and the adjustment liquid chamber C of the spring force biasing mechanism.

Spring force biasing mechanism The spring force biasing mechanism of this example includes a cylinder 33, and a piston that is slidably fitted to the cylinder 33, one end facing the adjustment liquid chamber C, and a spring seat 35 assembled to the other end. 34, a hold spring 36 stretched between the spring seat 35 and the valve body 4, and a control spring 37 engaged with the lower end of the link 39 via the spring seat 35 and the spring seat 38. The upper end of the link 39 engages with the rear end of the second control piston 16, and the seesaw movement of the link 39 about the fulcrum 40 transfers the spring force of the control spring 37 to the link 3.
It is configured to amplify the force at a boost ratio based on the length ratio of the fulcrum of 9 and the point of load application and transmit it to the second control piston 16.

According to such a configuration, the spring force Fx transmitted to the second control piston 16 via the link 39
increases as the control spring 37 is deflected by the movement of the piston 34, and the amount of increase is determined by the relationship between the hydraulic pressure on the piston 34 and the spring force of the hold spring 36.

To describe the operation of the hydraulic pressure control device configured as described above, at the initial stage of braking, the input hydraulic pressure pa ₁ ,
pb ₁ is transmitted as it is to the rear wheel brake device via the output liquid chambers a ₂ and b ₂ , and at this time, the hydraulic pressure to the first and second control pistons 8, 16 is the same as that for the first control piston 8. is balanced in both axial directions, and for the second control piston 16, the hydraulic pressure toward the rear end (to the right in the figure) that acts on the cross-sectional area _A2 of the small-diameter medium cylinder 20 increases. Therefore, when Pc=Fx/A ₂ is achieved due to the balance with the spring force Fx applied through the link 39 toward the front end, the second control piston 16 moves to the right in the figure and moves toward the valve body. 17 comes into contact with the valve seat 18,
Close the communication between input and output liquid chambers b ₁ and b ₂ , then tanθ=
The output liquid pb ₂ is input to the input liquid pressure pb ₁ at the ratio of A ₁ −A ₂ /A ₁ .
The increase will be gradual.

The first control piston 8 also controls the B system output hydraulic pressure.
In conjunction with the corner point slow increase control of pb ₂ , the output hydraulic pressure pa ₂ is controlled to be corner point slowly increase with respect to the input hydraulic pressure pa ₁ .

In the above relationship, the feature of this example is that the spring force Fx applied to the second control piston 16 increases in proportion to the fluid pressure value Pc held in the adjustment fluid chamber C by the operation of the G valve mechanism 2. It lies in being done.
In other words, the corner value Pc of output hydraulic pressure control is proportional to the value of the spring force Fx, but the value of this spring force Fx depends on the hold hydraulic pressure Ph in the adjustment liquid chamber, so in this example, Fx = F ₀
+kPh (F ₀ is the initial spring force), and the brake fluid pressure required for the G valve mechanism 2 to obtain a constant deceleration that closes the flow path 31a during vehicle braking is proportional to the load capacity of the vehicle. , the spring force acting on the second control piston 16 as the load increases.
This is because Fx will also be increased. Moreover, according to such a configuration, it is possible to vary the rate of change of the spring force Fx in response to various changing states of the ideal brake distribution curve, which are not constant depending on the vehicle type.
This can be easily done by changing the value of k in the previous equation Fx = F ₀ = kPh, and this k is the value of the piston 34.
This can be determined by selecting the diameter of the hold spring 36, the spring constant of the hold spring 36, the boost ratio of the link 39, etc.

In addition, in the proportioning actuation mechanism 1 in this example, when the A system fails, the degree of freedom of movement of the second control piston 16 relative to the first control piston 8 is l ₃ <
Since l ₁ + l ₄ , hydraulic control is canceled and B
In the event of a system failure, the second control piston 16 and the fail-safe pistons 6, 6' move to the right in the figure while maintaining the relationship shown, and the second control piston 16
The hydraulic pressure control is canceled because it is locked by the stepped part of the plug 19 through the brake, and if one of the A and B systems eventually fails, the normal system rear wheel brake fluid pressure will always be the same pressure as the input hydraulic pressure. This structure compensates for the lack of braking force in the entire vehicle.

As described above, the hydraulic pressure control device for a vehicle brake system according to the present invention adjusts the spring force that determines the corner value in the hydraulic pressure control of the proportioning actuating mechanism in proportion to the load capacity of the vehicle. In addition, the design can be changed very easily by changing the diameter of the piston 34, the spring force of the hold spring 36, etc., so it can be used to suit the characteristics of a variety of vehicles. This has the effect of expanding the scope of application.
In addition, the spring force of the control spring is amplified based on the lever ratio of the link that seesaws and is applied to the control piston, which has the effect of downsizing the device and simplifying the design of the control spring, and the practical benefits are extremely large. It is what it is.

It should be noted that although the above embodiment has been described for a double piping system, it is clear that it can be similarly applied to a single system system.

[Brief explanation of the drawing]

The drawing is a longitudinal sectional view showing a hydraulic pressure control device for a vehicle brake system, which is an embodiment of the present invention. 1...Proportioning operation mechanism, 2...G
Valve mechanism, 3... Spring force biasing mechanism, 4... Valve body, 5, 5'... Stage cylinder, 6, 6'...
Fail-safe piston, 7...Medium cylinder, 8
...First control piston, 9... Valve body portion, 10...
...Valve seat, 11...Hold spring,
12... Stopper, 13... Seal member, 14...
...Input port, 15...Output port, 16...Second control piston, 17...Valve body, 18...Valve seat, 19...Plug, 20...Small diameter medium cylinder, 21...Hold spring, 22...
Backup, 23... Locking ring, 24... Piston cup, 25... Seal ring, 26...
Stopper, 27... Input port, 28... Output port, 29... Guide surface, 30... Ball, 31
... Valve seat, 32 ... Channel, 33 ... Cylinder, 3
4...Piston, 35...Spring seat, 36...
...Hold spring, 37...Control spring, 38...Spring seat, 39...Link.

Claims (1)

[Claims] 1. It has a control piston that has a small hydraulic pressure receiving area in the input liquid chamber and a large hydraulic pressure receiving area in the output liquid chamber, and is biased by a spring force Fx in the direction of the output liquid chamber, and the spring force due to the hydraulic pressure action of this control piston A proportioning actuating mechanism controls the output hydraulic pressure to slowly increase at a turning point with respect to the input hydraulic pressure by moving against the input hydraulic pressure, and a proportioning mechanism that closes the flow path by generating a constant deceleration when the vehicle is braked to control one of the input and output liquid chambers. and a G valve mechanism that blocks communication between the flow path connecting the control liquid chamber and the adjustment liquid chamber, and transmits the spring force of the control spring biased at one end as spring force Fx to the control piston engaged at the other end by seesaw action. a spring force biasing mechanism having one end facing the adjustment liquid chamber, and a hold spring at the other end and a piston engaged with the control spring, the spring force biasing mechanism having a link that faces the adjustment liquid chamber, and a hold spring at the other end and a piston engaged with the control spring. A load-responsive hydraulic pressure control device for dual piping in a vehicle brake system, characterized in that the control spring moves against these springs to variably increase the spring force biasing the link of the control spring.