JPS58191661A - Brake liquid pressure control valve - Google Patents

Abstract

PURPOSE:To eliminate the over-shooting of liquid pressure by a structure wherein grooves with the radial direction and with the direction of a generating line are provided on a back-up member to support an annular sealing member in order to uniformize the liquid pressure applied to the sealing member at the release of braking. CONSTITUTION:A valve body part 8, to which the sealing member contacts, and a large diametral head part 7 are formed at a control piston 6. The sealing member 4 is located in a valve body by the back-up member 3. In spite of the flow of the brake liquid from a wheel cylinder as indicated with the arrow, the liquid pressure is uniformly applied to the sealing member 4 due to the radial grooves 9 and the grooves 10 with the direction of a generating line provided on the back-up member 3, resulting in eliminating the over-shooting of the liquid pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a hydraulic pressure control valve for a vehicle brake system, and more particularly, to an improvement in a brake hydraulic pressure control valve that controls the rear wheel brake hydraulic pressure of a vehicle to be reduced compared to the front wheel side. .

In general, the brake fluid pressure control valve in this building is a valve installed in the brake fluid pressure system from the mask cylinder to the rear wheel brake system, and normally (during initial braking), it directly transmits fluid pressure, but as the fluid pressure increases It is known to be equipped with a function to reduce the transmission fluid pressure in order to reduce the rear wheel braking force and prevent the occurrence of wheel lock as the
A typical example of this is so-called groportioning, which reduces the increase in rear wheel brake fluid pressure relative to the front wheel brake fluid pressure (corresponding to mask cylinder fluid pressure) from a certain corner value (makes the rate of increase gentle). Valve is known.

The basic structure of this provisioning valve is that an annular seal member disposed in the valve cylinder divides the inside of the cylinder into input and output liquid chambers, and the shaft hole of this seal member is inserted through the annular seal member. A control piston is provided that is movable in the axial direction, and this control piston is normally biased toward the output liquid chamber by a spring force, but when hydraulic pressure is applied, it moves toward the input liquid chamber against the spring force. cooperates with the sealing member to cut off the communication between the input and output liquid chambers to generate a break point value, and after this, the communication between the input and output liquid chambers is increased according to the increase in the liquid pressure in the input liquid chamber. The system is designed to gradually increase the hydraulic pressure on the output liquid chamber side by repeating shutoff, and this output liquid chamber side is communicated with the rear wheel brake device.

In addition to the provisioning valve with this basic configuration, there are also the necessary controls tJh for vehicles to which this valve is applied.
Various modified hydraulic pressure control valves have also been proposed in which the spring force acting on the control piston is made variable or the hydraulic pressure bending point occurs in two stages in order to meet the above-mentioned requirements.

By the way, in the above hydraulic pressure control valve, the output liquid chamber 1
Looking at the fluid pressure increase characteristics of μm1, there are cases where the fluid pressure becomes high near the corner point when moving to the pressure reduction control stage, resulting in a so-called overshoot phenomenon.Strictly speaking, this is due to brake control This indicates the above unfavorable tendency.

The inventor of the present invention has investigated this hydraulic pressure overshoot in detail, and found that one of the causes of it is that the position of the seal member shifts and collapses due to the pressure fluid flowing back from the output fluid chamber to the input fluid chamber when the brake is released. etc. occurs, and the next pressurization (
It was inferred that the reason was that the way the seal member and the piston contacted each other during braking was different from the previous time.

To explain this based on the drawings, FIGS. 1 and 2 show a part of a hydraulic control valve to which the present invention is applied, in which 1 is a valve body, 2 is a cylinder, and 3 is a hydraulic control valve. Reference numeral 4 indicates a cylindrical backup amplifier member, and 4 indicates an annular sealing member disposed so as to contact and engage with one end surface of the bank-up member 3. The reference numeral 4 designates an annular sealing member arranged so as to contact and engage with one end surface of the backup member 3. It is pressed and positioned. Further, a circumferential lip portion 5 is formed on the outer periphery of the seal member 4 so as to engage and come into contact with the circumferential surface of the cylinder 20.

The inside of the cylinder 2 is divided by this seal member 3 into an input liquid chamber a communicating with the mask cylinder side and an output liquid chamber a communicating with the rear wheel brake device side.

Reference numeral 6 denotes a control piston that is inserted through the shaft hole of the seal member 4 and is movable in the axial direction. A valve body portion 8 at the rear edge portion is provided, and this valve body portion 8
are opposed to each other so as to be able to abut against the end surface of the seal member 4.

Assuming that the diameter of the large-diameter head part is O and the diameter of the small-diameter shaft part is A as shown in the figure, this control piston 6 has a direction from the input liquid chamber a to the output liquid chamber with an area of At At (Fig. right direction)
The area of the output liquid chamber A is subjected to hydraulic pressure in the input liquid chamber a direction (to the left in the figure), and a spring (not shown) causes the output liquid chamber to move in the direction (to the left in the figure). (in the right direction) to receive a predetermined spring force.

In other words, with this configuration, the control piston 6 is normally pressed to the limit of deflection on the side of the output liquid chamber by a spring force, and the valve body part 8 is separated from the seal member 4, thereby closing the gap between the input and output liquid chambers a and b. If communication is maintained, and the hydraulic pressure in the axial direction becomes unbalanced due to a rise in hydraulic pressure, the control piston/6 resists the spring force.
moves toward the input liquid chamber a, and when the valve body portion 8 abuts the seal member 8, communication between the input and output liquid chambers a and b is cut off.

After this, the liquid pressure in the output liquid chamber is tanθ=A+-At/A
It rises with a slope of t.

The liquid pressure increase characteristic line shown by the solid line in FIG. 3 depicts the ideal increase in the case described above.

By the way, as mentioned above, overshoot, which is a problem with ideal rise, is based on the change in hydraulic pressure when the brake is released, and this will be explained next.

Assuming that FIG. 1 shows the hydraulic pressure operation state in the state of FIG. 3 (b) in which a predetermined brake is applied, when the brake is released here, the hydraulic pressure on the input fluid chamber a side drops rapidly. Along with this, the hydraulic pressure on the output liquid chamber side is in a high state, so this also acts on the seal member 4, pushing and bending the seal part that contacts the valve body part 8, the outer peripheral lip 5, etc. The pressure liquid will escape to the input liquid chamber a side. FIG. 2 shows this state.

Therefore, ideally, the output fluid pressure would follow the same characteristics as when it rose and would drop to zero pressure, but in reality, the bending stiffness of the sealing member and other factors will affect the situation, resulting in a state where the pressure difference is only △P (
The hydraulic pressure will drop at the point (indicated by the dark line) in the figure. The fact that such pressing and bending of the seal member occurs non-uniformly in the circumferential direction is the cause of the above-mentioned positional displacement and collapse of the seal member.

In view of these circumstances, the present invention is designed to eliminate the above-mentioned problems by equalizing the hydraulic pressure acting on the seal member 4 in the circumferential direction when the brake is released. The gist of the present invention is as follows: A cylindrical backup member that is fitted and arranged at a predetermined position in a cylinder; An annular seal member that partitions the input and output liquid chambers, and an annular seal member that is provided so as to be movable in the axial direction by passing through the shaft hole of the annular seal member, and that comes into contact with the seal member to interrupt communication between the input and output liquid chambers. a control piston having a valve body formed therein, the control piston moving toward the input liquid chamber when the hydraulic pressure in the output liquid chamber reaches a predetermined value, and causing the valve body to abut against the seal. In the hydraulic pressure control valve, the backup member includes at least one of a plurality of radial grooves or protrusions formed on the one end surface, or a generatrix groove on the outer circumferential surface, which are formed in a large number spaced apart in the circumferential direction. It is located in the brake fluid pressure control valve which is a percentage indicator.

A hydraulic pressure control valve having such a configuration has the effect of significantly reducing the occurrence of so-called overshoot during braking.

To explain the embodiment of the present invention using the drawings, the fourth
Figures (a), (b), and e) all show different configuration examples of backup members used to realize the present invention, and their basic shapes are similar to those in Figures 1 and 2 above.
As applied to the hydraulic control valve shown in Fig. 1,
It has the same shape as the one in FIG. That is, it has a cylindrical shape as a whole, and has a slightly larger diameter at one end surface that engages in contact with the seal member 4, and a smaller diameter at the other end surface that engages with the cylinder side wall of the valve body.

(a) In the case shown in the figure, a plurality of radial grooves (which may also be protrusions) 9 are spaced apart in the circumferential direction on one end surface.
．． 9... are formed at approximately equal intervals, and in the figure (b), a plurality of generatrix direction grooves 10, 10... are formed at a distance in the circumferential direction on the large diameter outer circumferential surface following one end surface portion. are formed at approximately equal intervals, and the one shown in the figure (/) has both of the two types of grooves 9 and 10.

When using any of the backup members 3', 3'', and 3#' as described above, the characteristic line of rise and fall on the side of the output liquid chamber appears almost the same as in the conventional case, but the next brake It was observed that the appearance of overshoot at time was significantly reduced.

It is understood that this is because the presence of the grooves 9 or 10 makes the pressure applied to the sealing member uniform in the circumferential direction.

It should be noted that the grooves 9 (or protrusions) or 10 are formed at equal intervals in the circumferential direction, and it is thought that the grooves will be more uniform if there are more grooves, but in practice, the entire circumference shown in the diagram is divided into eight equal parts. Good results were obtained with only a small amount of water.

As described above, the present invention has a relatively simple structure and has extremely good effects, and its usefulness has been enormous.

[Brief explanation of the drawing]

Figures 1 and 2 are cross-sectional views showing a part of the hydraulic control valve to which the present invention is applied. Figure 1 shows the state when braking, and Figure 2 shows the state when the brake is released. Figures 4 (a), (b), and 4 are diagrams showing the rise and fall characteristics of rear wheel brake fluid pressure.
(C) shows examples of backup members used in the hydraulic control valve of the present invention. 1... Valve body 2... Cylinder 3.3'
, 3'', 3'''... Backup member 4... Seal member 5... Outer lip 6... Control piston
7... Large diameter head 8... Valve body part 9...
Groove 10... Groove. (11) Figure 2

Claims (1)

[Claims] A cylindrical backup member is fitted and arranged at a predetermined position in the cylinder, and the backup member is arranged so as to come into contact with one end of the backup member and the circumferential surface of the cylinder to divide the inside of the cylinder into input and output liquid chambers. An annular seal member and a valve body portion that is movable in the axial direction through the shaft hole of the annular seal member and abuts against the seal member to interrupt communication between the input and output liquid chambers. and a control piston, the control piston moves toward the input fluid chamber to bring the valve body portion into contact with the seal when the fluid pressure in the output fluid chamber reaches a predetermined value. A brake fluid pressure control valve characterized in that the member includes at least one of a plurality of radial grooves or protrusions formed on the one end surface and a generatrix direction groove on the outer circumferential surface, which are formed in large numbers spaced apart in the circumferential direction.