JPH021167Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an improvement of a proportioning valve used in a vehicle brake system.

Conventionally, a proportioning valve that controls the hydraulic pressure transmitted to the rear wheel brake side of the vehicle from a predetermined hydraulic pressure value to a corner point, or a proportioning valve that controls the hydraulic pressure value at the corner point, has been used.
There are also known types that include an inertial valve mechanism that changes according to the load state of the vehicle, and double piping types that have two independent braking systems for the vehicle.

As one of the basic configurations of such a proportioning valve, for example, as shown in FIG. It is divided as a control liquid chamber, and this compartment is used as an input liquid chamber a ₁
An annular sheet member 4 is provided to divide the input and output liquid chambers a _{1 and c} 2 into output liquid chambers a 1 and c ₂ by making contact with and separating from the sheet member 4.
Some are equipped with a control piston 5 that opens and closes communication between them. The control piston 5 normally separates its valve body portion 5a from the seat member ₄ to open communication between the input and output fluid chambers a1 and _a2 , and the transmitted fluid pressure increases to a predetermined fluid pressure value. In this case, the control piston 5 is configured as follows in order to operate so as to close the communication between the input and output liquid chambers a ₁ and a ₂ by bringing the valve body portion 5 a into contact with the seat member 4. There is.

That is, by making a difference in the area of hydraulic pressure acting on the control piston 5 from each of the input and output liquid chambers a ₁ and a ₂ , a moving force based on the hydraulic pressure is applied to the control piston 5 as the hydraulic pressure increases. For this purpose, the valve body of the control piston 5 is The end portion opposite to the head portion 5a is inserted outside the liquid chamber through a cylinder hole 3a formed in the middle cylinder member 3 having a partition wall structure, and a control spring 6 is inserted in order to apply the bias spring force described above to the cylinder hole 3a.
This means that they are engaged.

Such engagement of the spring is usually performed via a spring holder 7 as shown in this example. Also, the cylinder hole 3a of the middle cylinder member 3
In order to prevent liquid leakage from the insertion and sliding portion of the control piston 5, the input liquid chamber of the middle cylinder member 3 is
A piston cup 8 is usually disposed as a seat member at the inner end portion on the _a1 side.

In FIG. 1, 9 is a locking ring for fixing the middle cylinder member 3, 10 is a hold spring for keeping the middle cylinder member 3 and seat member 4 fixed, and 13 is a fluid leakage from between the fitting surfaces. O-ring as a sealing member to prevent
18 is an input port that connects the input fluid chamber a(1) and the master cylinder, and 18 is an output port that connects the output fluid chamber _a2 to the rear wheel brake device.

In the proportioning valve configured as described above, normally the control piston 5 separates its valve body portion 5a from the seat member 4 due to the bias spring force of the control spring 6, and when the hydraulic pressure increases, the control piston 5 resists this spring force. The control piston 5 moves to bring the valve body 5a into contact with the seat member 4, and thereafter, by repeatedly bringing the valve body 5a into contact with and separating from the seat member 4, the output liquid chamber is depressurized and raised relative to the input liquid pressure. This is something that has been known for some time.

Now, when a proportioning valve with the above configuration is produced in large quantities on an industrial scale, the actual breakpoint value during breakpoint pressure reduction control may vary slightly from product to product. It was hot. Although this can be addressed by improving the machining accuracy of component parts, it is difficult in practice to strictly control component tolerances.

Therefore, the inventor of the present invention has conducted various studies regarding this problem, and has obtained good results in eliminating the dispersion of actual break points between products by using the configuration of the present invention.

That is, considering the cause of the variation in the actual break point, this is because in the configuration shown in FIG. 1, the control piston 5 is first guided by the cylinder hole 3a of the middle cylinder member 3; If the coaxiality between the control piston 5 and the piston cup fitted on the outer periphery of the control piston 5 is lost, the sliding resistance of the control piston will change due to twisting, etc., and this will cause the actual break point value to change. The point is that it has an impact. This problem of coaxiality may also occur between the control spring 6 and the control piston 5, and in this case as well, the influence of a change in sliding resistance due to the inclination of the control piston 5 may occur.

In view of these points, it is an object of the present invention to provide a proportioning valve in which the sealing member itself that prevents liquid leakage from the control liquid chamber directly serves as a sliding guide for the control piston 5. It is.

The characteristic of the proportioning valve of the present invention, which was developed to achieve this purpose, is that the control piston is brought into contact with and separated from the seat that divides the interior of the cylinder into input and output liquid chambers. Communication between the output liquid chambers is opened and closed to control the liquid pressure in the output liquid chamber to be reduced at a corner point relative to the liquid pressure in the input liquid chamber, and one axial end of the control piston on the output liquid chamber side is connected to the partition wall of the cylinder. In the proportioning valve, the annular outer circumferential surface of the partition wall is inserted into the outside of the output liquid chamber and engaged with the corner spring to set the corner fluid pressure value of the corner point pressure reduction control. an annular elastic seal member that snaps onto the inner circumferential surface of the cylinder and whose annular inner circumferential surface snaps onto the outer circumferential surface of the one axial end of the control piston in a fluid-tight manner; and both ends of the elastic seal member in the cylinder axial direction. The elastic seal member has a sandwich structure with a pair of back-ups that are compressively engaged with the inner circumferential surface of the cylinder and loosely fit against the outer circumferential surface of the one axial end of the control piston, and the elastic seal member The annular cross section has two impact surfaces spaced apart from each other in the axial direction with respect to each of the outer circumferential surfaces of the one end in the axial direction, and has an approximately H-shaped cross section (a so-called H-shaped seal).

An embodiment of the present invention will be described below with reference to FIG. 2. Since this embodiment is the same as that shown in FIG. 1 except for the structural parts through which the control piston is inserted and supported, there are common parts. is indicated by adding 100 to the code, and its explanation is omitted.

The feature of this example is that instead of the middle cylinder member 3 in FIG.
20 is fitted on the inner circumferential surface of the cylinder of the cylinder body 1 on its outer circumferential surface, and fitted on the outer circumference of the control piston 5 on the other inner circumferential surface.
The back ups are engaged with both end surfaces of the mold seal 120 in a pair, and these are connected to the locking ring 1.
09 and the hold spring 110. Since the backup does not serve as a sliding guide for the control piston 105, it has a loose fitting structure with a slight clearance between its inner peripheral surface and the outer peripheral surface of the control piston 105.

The operation and function of the proportioning valve as a whole with such a configuration is no different from that of conventional ones, but the H-shaped seal 120 can form a liquid leakage seal in two places on its inner and outer peripheral surfaces, and Since this H-shaped seal 120 itself serves as a sliding guide for the control piston 105, there is no effect of variations in sliding resistance due to misalignment between the seat member and the control piston 105 as in the conventional case.
It was experimentally confirmed that the effect of reducing the variation in actual breaking points can be obtained.

Further, the sealing performance of the H-shaped seal 120 is sufficiently ensured by the back-up sandwich structure, and its practical benefits are extremely large.

[Brief explanation of drawings]

FIG. 1 is a partial sectional view showing the structure of a conventional proportioning valve, and FIG. 2 is a sectional view showing an embodiment of the present invention. 1,101... Cylinder body, 3... Middle cylinder member, 3a... Cylinder hole, 4,104...
Seat member, 5... Control piston, 105... Valve body portion, 6, 106... Control spring, 7, 10
7... Spring holder, 8... Piston cup, 9,109... Locking ring, 10,110...
...Hold spring, 13,14...O-ring, 16,116...Input port, 17,117
...output port, 18,118...output port,
120...H-type seal,...backup.

Claims (1)

[Scope of utility model registration request] The control piston engages and separates the seat that divides the inside of the cylinder into an input liquid chamber and an output liquid chamber to open and close communication between the input liquid chamber and the output liquid chamber, thereby inputting the liquid pressure in the output liquid chamber. The liquid pressure in the liquid chamber is controlled to be reduced at a turning point, and one axial end of the control piston on the output liquid chamber side is inserted through the partition wall of the cylinder to the outside of the output liquid chamber and engaged with the turning point spring. , in the proportioning valve in which the corner point liquid pressure value of the corner point pressure reduction control is set, the partition wall is
an annular elastic seal member whose annular outer circumferential surface elastically contacts the inner circumferential surface of the cylinder and whose annular inner circumferential surface elastically contacts the outer circumferential surface of the one axial end of the control piston in a fluid-tight manner; It has a sandwich structure with a pair of back-ups that are press-fitted to both axial end surfaces of the cylinder and are loosely fitted to the outer circumferential surface of the one axial end of the control piston, and the elastic seal member is arranged inside the cylinder. A proportioning valve characterized in that the annular cross section has a generally H-shaped shape and has two impact surfaces spaced apart in the axial direction relative to the peripheral surface and the outer peripheral surface of the one axial end of the control piston.