JPH02114048A - Flow control valve for anti-lock - Google Patents

Abstract

PURPOSE:To ensure safety even when a spring is broken, by furnishing a spare communication path to put an inlet and an outlet in communication with each other when a spool gets over the repressurization position and moves to the position where a variable orifice is fully closed. CONSTITUTION:In a flow control valve 3 for anti-lock, a solenoid valve 5 is opened at the time of anti-lock decompression to allow the working liquid in a decompression chamber 36 to be exhausted from an exhaust hole 31c to a reserver 63, and thereby a spool 32 moves down according to the differential pressure between the two ends to put a minor flow path blocking part 32c in opened condition, that should form an exhaust path passing paths 31b, 32a, 31e, 31c, and thus the working liquid of a wheel brake is exhausted to the reserver 63 to attain decompression. Therein a spare communication hole 32e is formed in the spool 32 between the mentioned minor path blocking part 32c and a metalling edge 32d. When the spool 32 has come to the overstroke position, spare communication path passing through paths 31a, 35, 33, 36, 32e, 31e, and 32a is formed to preclude generation of a trouble of non-braking.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a flow control valve used in a vehicle anti-lock brake system.

[Conventional technology]

Vehicle anti-lock devices are becoming popular, and costs are being reduced.
Application to small cars is an urgent need. One solution to this problem is, for example, hydraulic pressure control using two solenoid valves per wheel, as shown in Japanese Patent Publication No. 49-283071! [Instead of l, GB uses one solenoid valve per wheel and controls with two control modes: pressure reduction and slow pressure increase.
8512610.

This is as shown in Fig.
This is a version in which the electromagnetic valve for controlling pressure increase in Publication No. 1 is replaced with a flow control valve 3. This flow rate control valve 3 is provided inside a housing 31 having three boats: an inlet 31a communicating with the master cylinder 2, an outlet 31b communicating with the wheel brakes 4, and an outlet 31c communicating with the electromagnetic valve 5. The spool 32 that switches the communication state between
The other ends of the spools 32 face the decompression chamber 36, and are housed in a slidable manner under pressure from a spring 34. When the anti-lock is not activated, the spool 32 remains at the original position shown in the figure and is opened from the inlet 31a. A large flow path is formed that passes through the outer circumferential groove 32i of the spool 32 and reaches the outlet 31b. Also,
The flow path between the outlet 31b and the discharge port 31c is the small wave passage closing part 3
It is cut off at 2C.

On the other hand, during anti-lock pressure reduction, when the solenoid valve 5 is energized and opened, the pressure reduction chamber 3 flows from the discharge port 31C to the reservoir 63.
As a result of the hydraulic fluid 6 being discharged, a pressure difference is generated between both ends of the spool 32, and the spool 32 moves, resulting in the state shown in FIG. 5A. Then,
First, the large flow path is closed by the large flow path closing portion 32b of the spool 32, and the spool 32 further moves to the state shown in FIG.
b, a discharge passage connecting the groove 32a, the passage 31e, and the discharge port 31c is formed, and the hydraulic fluid of the wheel brake 4 is discharged to the reservoir 63 via the electromagnetic valve 5 and is depressurized. Then, this working fluid is sucked and pressurized by a pump 61 driven by a motor 62, and returned between the master cylinder 2 and the inlet 31a.

Furthermore, when the solenoid valve 5 is demagnetized when repressurizing the anti-lock, the spool 32 moves between the edge 32d and the passage 3 in the state shown in FIG. 5B.
A metal ringing action is performed with the inner peripheral end of 1f, and the inlet 31a,
Passage 31d, fixed orifice 33, decompression chamber 36, passage 3
A small flow path connecting the 1f1 passage 31e, the outer circumferential groove 32a, and the outlet 31b is formed to slowly increase the pressure of the wheel brake 4. When the differential pressure between the inlet 31a and the outlet 31b becomes small (when the spool returns to its original position, it becomes the state shown in FIG. 5).

In the case of this method, only one solenoid valve is required per wheel, which is advantageous in terms of cost, and the flow rate when repressurizing the antilock in the state shown in FIG.
The metering edge 3 is adjusted so that the flow rate is such that the differential pressure determined by the biasing force of
Since the opening degree of the passage between 2d and the passage 31f (hereinafter referred to as variable orifice) is adjusted, it remains constant regardless of the differential pressure between the inlet 31a and the outlet 31b, and the differential pressure before and after the orifice can be reduced. Therefore, it is possible to secure a small flow rate with a relatively large orifice diameter, and it is easy to apply to small cars with small brakes with small consumption II.

[Problem to be solved by the invention]

The above flow control valve or a similar flow control valve is
Due to a problem such as the spring 34 breaking, the spool 32 may break at the metering edge 32d as shown in FIG. 5C.
When the variable orifice section is overstroked to a fully closed position, communication between the inlet 31a and the outlet 31b is cut off.

In this case, the brake fluid flowing from the inlet 31a to the outlet 31b only leaks from the minute clearance between the spool and the casing, and the pressure increase/decrease condition of the wheel brake becomes very poor. It is thought that it is extremely rare for the spool to stop in such a position, but since there is a concern about such trouble, it is necessary to consider countermeasures regarding this problem in vehicle brakes where safety is the top priority. There is.

The present invention aims to provide a flow control valve that meets these demands.

[Means to solve the problem]

In order to eliminate the above-mentioned problems, the present invention includes a housing having a small number of inlets and outlets (both have two boats), and a housing that is slidably provided within the housing, and which is configured to change the relative position between the fixed orifice and the housing. It has a spool having a variable orifice that can change the flow path area, and a spring that biases this spool in one direction, and when the anti-lock is not activated, the spool is in a non-activated position. A large flow path connecting the inlet and the outlet is communicated, and when repressurizing the anti-lock, the spool moves to the repressurizing position and the inlet, variable orifice, fixed orifice, and outlet form a serial flow path. The flow rate of this flow path is a constant fL when a constant pressure difference determined by the effective pressure receiving area of the spool and the biasing force of the spring acts on the front and rear of the fixed orifice, regardless of the pressure difference between the inlet and the outlet. In an anti-lock flow control valve configured such that the flow path area of the variable orifice is required to meet a certain amount, the spool has moved beyond the repressurization position to a position where the variable orifice is fully closed. Sometimes, a spare communication path is provided to communicate between the inlet and the outlet.

The preliminary communication path may be provided on either the spool or the housing. When the preliminary communication path is provided on the housing, when the spool moves beyond the normal operation stroke, it moves along with the preliminary communication path and connects the preliminary communication path. Although it is necessary to provide a valve element that opens the communication path by urging it in the valve closing direction, this is not necessary if it is provided on the spool.

(Operation) When the spool moves to the overstroke position, the inlet and outlet of the casing are connected via the preliminary communication path.Therefore, even if the spool stops at that position and cannot return to its original position, the wheel brake pressure The step-up/down pressure a capability is ensured,
Normal operation of the vehicle will not be affected.

Further, when the spool operates normally, the preliminary communication path is not connected to the entrance, so that anti-lock control is not adversely affected.

〔Example〕

*FIG. 1 - First Embodiment The flow rate control valve 103 of this first embodiment is the control valve of FIG. 5 to which the technology of the present invention is added.

That is, a preliminary communication hole 32e is provided that penetrates the spool 3'2 in the radial direction between the small passage closing portion 32c and the metering edge 32d. This preliminary communication hole 32e is
When the spool 32 is in the position of FIG. 1A, the passage 31
However, at this time, the small channel closing portion 32C cuts off the communication between the passage 31e and the spool outer peripheral groove 32a, and when the spool 32 is in the position shown in FIG. 1B, the preliminary communication hole 32e itself is connected to the housing 31. Both entrances and exits do not function as communication routes.

However, as shown in FIG. 1C, when the spool 32 reaches the overstroke position, its function is activated and the inlet 32
a. A preliminary communication path passing through the input chamber 35, fixed orifice 33, decompression chamber 36, preliminary communication hole 32e, passages 31f, 31e, and spool outer circumferential groove 32a is secured, and no-brake troubles due to movement of the spool 32 to the relevant position are avoided. is prevented.

Fig. 2 - Second Embodiment The control valve 203 of this second embodiment has the features of the present invention added to the control valve that creates a large flow path via the flow path in the spool when the anti-lock is not activated. This is what I did. This control valve 203 is mounted on the boat 37a in the housing 31 from the viewpoint of workability.
.about.37c. The spool 32 also has an input chamber 35 and a boat 37 in the non-operating position.
A boat P5 is connected to the port 31a via a boat P5, a port P5 is connected to the outlet 31b via a boat 37b, and an outlet 31b is connected to a vacuum chamber 36 via a boat 37C during anti-lock depressurization. A boat P is provided for communication.

The solenoid valve 5 is also integrated into the housing 31 to open and close the discharge path between the decompression chamber 36 and the discharge port 31C.

This control valve is in the state shown when not braking, and the inlet 31
a1 boat 3? a, boat PI, input room 35, boat P
! , a large flow path leading to the outlet 31b via the boat 37b is secured.

When the electromagnetic valve 5 is energized and opened during anti-lock pressure reduction, the hydraulic fluid in the pressure reduction chamber 36 is discharged from the outlet 31C. Then, the input chamber 35 with the fixed orifice 33 as a boundary
A pressure difference is generated between the spool 32 and the decompression chamber 36, and the spool 32 moves downward, and the large flow path is blocked by the large flow path closing portion 32b at the position shown in FIG. 2A. When the spool 32 further moves downward and the small passage closing portion 32C opens, the outlet 31b
, the port 37C1, the boat Ps, and the decompression flow path leading to the discharge port 31c via the decompression chamber 36 are communicated with each other, and the hydraulic pressure of the wheel brakes is reduced. Further, when the solenoid valve 5 is demagnetized and closed by the anti-lock repressurization command, the flow toward the discharge port 31c is stopped, and the state shown in FIG.
7a, variable orifice composed of this boat and metering edge 32d, boat Pl, input chamber 35, fixed orifice 33, decompression chamber 36, boat P1, boat 3? A small flow path leading to the outlet 31b via the outlet 31b is secured.

The opening force of the variable orifice is automatically adjusted so that the flow rate of this small flow path is always constant regardless of the differential pressure between the inlet 31a and the outlet 31b. As in the case of FIG. If the spool 32 moves to the overstroke position, a no-brake problem will occur.

Therefore, the control valve 203 of the second embodiment is provided with a preliminary communication passage 31g that directly connects the inlet 31a and the outlet 31b to the housing 31, and a valve means 38 that opens and closes this communication passage. Valve means 3
Reference numeral 8 denotes a valve body 38a whose valve head faces the valve chamber in the middle of the preliminary communication path, and a spring 38 that biases this valve body in the valve-closing direction.
It consists of b. Further, the valve body 38a has a stroke L such that the lower end side is connected to the upper end of the spool 17 (the end on the input chamber 35 side).
The stroke L and the metering edge 32d of the boat 3 of the sleeve 37 are mounted in a state that allows relative movement in the axial direction of the sleeve 37. The relationship between a and the closing stroke Lt is set to ≧L2.

Note that the relationship between the stroke L1 of the large channel closing portion 32b closing the boat 37b and the above-mentioned L20 is Lt>L.

It is.

By doing this, when the spool 32 moves to the side of the decompression chamber 36 with a larger stroke, for example, the second
When the valve body 38a is moved L4 to the position shown in Fig. C, the valve body 38a is pulled by the spool 32 to open the preliminary communication passage 31g, through which the master cylinder pressure flows to the outlet 31b.

Further, when the spool 32 moves within the range of L3, the valve body 38a is kept in the closed position, so the original function of the control valve is not impaired.

*Figure 3 - Third embodiment, Figure 4 - Fourth embodiment The control valve 303 of this third embodiment and the control valve 403 of the fourth embodiment are both provided with a preliminary communication path on the spool 32. The passage is opened naturally by overstroke displacement of the spool.

That is, in the case of FIG. 3, the radial hole provided in the spool 32 is used as the preliminary communication path 32f, while in the case of FIG. The space created between the ocean surface and the input chamber 35 at one end is defined as a preliminary communication path 32g, and these communication paths 32f, 3
2g to the boat 37a at the overstroke position where the spool 32 moves more than L2, and the inlet 31a
, the boat 37a, the preliminary communication path 32r (or 32g), the fixed orifice 33, the decompression chamber 36, and the boat P1.37C to guide the master cylinder pressure to the outlet 31b.

The preliminary communication path 32g shown in Fig. 4 can be made by digging a groove around the spool's outer circumference, but in any case, with the structure shown in Figs. 3 and 4, only slight additional work is required on the spool. This has the advantage of avoiding complication of the structure of the control valve. Other effects of the third and fourth embodiments are as follows:
Since this is the same as in the embodiment, further explanation will be omitted.

Note that the fixed orifice 33 of the control valve in FIGS. 2 to 4
is formed on the shim plate 39 and pressed against the inner step of the spool 32 by the force of the spring 34, and when the differential pressure between the high pressure input chamber 35 and the low pressure decompression chamber 36 increases abnormally, the spring 34 is activated. It can be compressed and moved to the decompression chamber side. Although this is not an essential requirement of the present application, if it is done in this way, when the fixed orifice 33 is blocked by a foreign object and the liquid flow from the input chamber 35 to the decompression chamber 36 is cut off, an abnormal pressure difference will occur. The shim plate 39 moves to the decompression chamber side 36, and there is a gap of 35.3 mm between the outer diameter surface of the shim plate and the large diameter hole 32h of the spool 32.
Since a bypass path between 6 and 6 is created, the reliability of the control valve is further increased.

〔effect〕

As described above, the flow control valve of the present invention is provided with a spare communication path that connects the inlet of the housing to the outlet when the spool moves to the overstroke position. Even if the brake fluid remains stopped at the overstroke position, the flow of brake fluid to the wheel brakes is guaranteed, which will impede normal operation of the vehicle.
There is no deterioration in the original function of the valve, and it is suitable for vehicle brakes.
This has the effect of sufficiently increasing reliability regarding the fail-safe system.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing an example of the flow control valve of the present invention in a used state, and FIG. 1A, FIG. 1B, and FIG.
, 5B, and 5C are explanatory diagrams of the spool position; FIG. 2 is a sectional view of the second embodiment;
rM, Figure 2C shows the movement status of the spool, Figures 5A and 5
3 is a sectional view of the third embodiment, FIG. 4 is a sectional view of the fourth embodiment, FIG. 5 is a sectional view of the conventional example, and 5A is a sectional view corresponding to the positions of FIGS. Figures 5B and 5B are explanatory diagrams of the operation of the control valve in Figure 5 when the anti-lock is activated, and Figure 5C is a diagram showing the overstroke position of the spool. 1... Brake pedal, 2... Master cylinder, 4... Wheel brake, 5... Solenoid valve,
6... Pressure source, 103.203.303.403... Flow rate control valve, 31... Housing, 31a...
Entrance, 31b...Exit, 32...
Spool, 32b... Large channel closing part, 32C... Small channel closing part, 32d... Metering edge, 32e...
...Preliminary communication hole, 31g, 32f, 32g...Preliminary communication path, 33
...Fixed orifice, 34 ... Spring, 35 ... Input chamber, 36 ... Decompression chamber, 37 ... Sleeve, 38 ... ...Valve means, 39...
・Shim board.

Claims (3)

[Claims] (1) A housing having at least two ports, an inlet and an outlet, and a variable orifice that is slidably provided within the housing and whose flow path area can be changed by changing the relative position between the fixed orifice and the housing. and a spring that biases this spool in one direction, and when the anti-lock is not activated, the spool is in the inactive position and communicates a large flow path connecting the inlet and the outlet. However, when repressurizing the anti-lock, the spool moves to the repressurizing position and the inlet, variable orifice, fixed orifice, and outlet form a series flow path, and the flow rate of this flow path is equal to that of the inlet. The flow path area of the variable orifice is set so that a constant flow rate is obtained when a constant pressure difference determined by the effective pressure-receiving area of the spool and the biasing force of the spring acts across the fixed orifice, regardless of the pressure difference at the outlet. In the anti-lock flow control valve configured as required, when the spool moves beyond the repressurizing position to a position where the variable orifice is fully closed, a reserve is provided that communicates between the inlet and the outlet. An anti-lock flow control valve characterized by having a communication path. (2) Claim (1) in which the preliminary communication path is provided on the spool.
The anti-lock flow control valve described. (3) The preliminary communication path is provided in the casing, and when the spool moves beyond the normal operation stroke, a valve body that moves along with the spool and opens the preliminary communication path is biased in the valve closing direction. The anti-lock flow control valve according to claim (1), wherein the anti-lock flow control valve is provided with: