JPH02114049A - Flow control valve for anti-lock - Google Patents

Abstract

PURPOSE:To prevent generation of a trouble of non-braking resulting from fast attachment of a spool by furnishing a normally open bypass connecting inlet and outlet of a flow control valve for anti-lock, and blocking the bypass when a certain specified value is exceeded by the sensed value of differential pressure between before and after a fixed orifice. CONSTITUTION:In a flow control valve 103 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 the flow control valve 103 is equipped within its casing 31 with a differential pressure valve 15 and a bypass 11 parallel with a major flow path provided at the inlet and outlet 31a, 31b via a peripheral groove 32a. Downward motion of piston 15a when a certain specified value is exceeded by the differential pressure between before and after a fixed orifice 33 will block the bypass 11.

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 to use one solenoid valve per wheel for pressure reduction and gradual pressure increase, instead of the hydraulic pressure control using two solenoid valves per wheel as shown in Japanese Patent Publication No. 49-283071. The GB851 control method uses two control modes.
2610.

As shown in Figure 5, this is
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. The flow rate control valve 3 is installed inside a housing 31 having three ports: 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 solenoid valve 5. A spool 32 is biased by a spring 34 and is housed in a slidable manner, and when the anti-lock is not activated, the spool 32 remains at the original position shown in the figure and is inserted into the outer peripheral groove of the spool 32 from the inlet 31a. A large flow path is formed that reaches the outlet 31b via the outlet 32a.

Furthermore, when the anti-lock pressure is reduced, when the magnetic valve 5 is energized and opened, the hydraulic fluid is discharged from the discharge port 31c to the reservoir 63, and as a result, the spool 32 moves due to a differential pressure generated at both ends. It will be in the state shown in the figure. 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. 32
A discharge path is formed that connects the passage 31e, the passage 31e, and the discharge port 31C, and the hydraulic fluid for the wheel brakes 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.
1" performs a metal ringing action with the inner peripheral end of the inlet 31a1.
A small flow path is formed that connects the passage 31d, the fixed orifice 33, the decompression chamber 36, the passage 31f, the passage 31e1, the outer circumferential groove 32a, and the outlet 31b, and gradually increases the pressure of the wheel brake 4.

When the differential pressure between the inlet 31a and the outlet 31b decreases, the spool returns to its original position, resulting in 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 4 is applied before and after the fixed orifice 33.
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 fixed orifice is adjusted. Since it can be made small, 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 that consume a small amount of fluid.

[Problem to be solved by the invention]

In the flow control valve having the spool, as described above, when the anti-lock pressure is reduced, the spool 32 first moves to the position shown in FIG. 5A, and the inlet 31a and the outlet 31b
After that, move further and open the depressurization flow path connecting the outlet 31b and the discharge port 31C at the position shown in Fig. 5B. Also, when repressurizing the anti-lock, the fixed orifice 3
Open a small channel via 3. Therefore, when the spool 32 is in the intermediate position between FIGS. 5A and 5B, the inlet 31
The large flow path between a and the outlet 31b is closed by the large flow path closing part 32b, and the small flow path is closed by the small flow path closing part 32C, so that in the unlikely event that the spool 32 is If it becomes stuck in this position, there is a problem in that the master cylinder 2 becomes unable to apply pressure to the wheel brake.

This problem does not only occur with the illustrated control valve;
In other words, this is a common problem with all types of control valves that temporarily cut off communication between the inlet and outlet when the spool moves between the original position where the large flow path is opened and the repressurized position where the small flow path is opened. It is.

This invention was made with the aim of solving such problems.

[Means to solve the problem]

In order to achieve the above object, the flow control valve B of the present invention includes a housing having at least two ports, an inlet communicating with the master cylinder and an outlet communicating with the wheel brake, and the valve is slidably inserted into the housing. a spool, which is capable of switching the communication state between two ports, and has a fixed orifice and a variable orifice whose flow path area can be changed by changing the corresponding position with respect to the casing; the spool is in a non-operating position and forms a large flow path connecting the inlet and outlet when the anti-lock is not activated, and when the anti-lock is re-pressurized, the spool is biased against the spring. The main channel is moved from the non-operating position against the biasing force of the main channel to first close the large channel with the large channel closing section, and then further moved until the small channel closing section is in the open position and the inlet is closed. A small channel is formed between the outlets, communicating via the fixed orifice and the variable orifice, and the flow rate of this channel is independent of the pressure difference between the inlet and the outlet, and the effective pressure receiving area of the spool and the biasing force of the spring are formed. In the anti-lock flow control valve, the flow path area of the variable orifice is adjusted so that a constant flow rate is obtained by applying a constant pressure difference between the front and rear of the fixed orifice. A differential pressure detection means for detecting a fluid pressure difference and a normally open bypass passage connecting the inlet and the outlet are provided, and the bypass passage is closed when the differential pressure detected by the differential pressure detection means exceeds a predetermined value. This is what I did.

Note that the differential pressure detection means may be a hydraulic piston that receives the pressures before and after the fixed orifice in opposite directions, and this hydraulic piston may be provided with a valve portion for opening and closing the bypass path, if necessary. may be provided. Further, a sleeve for housing the spool may be provided between the housing and the spool so as to be slidable in the axial direction, and this sleeve may serve as the differential pressure detection means.

(Function) In the case of a flow control valve having such a configuration, when the spool moves from the non-operating position under normal conditions, a pressure difference is generated before and after the fixed orifice that overcomes the force of the spool biasing spring. If the differential pressure is detected by the differential pressure detection means and the bypass path is closed when the differential pressure is lower than the differential pressure at which the spool starts moving, there will be no effect on anti-lock pressure reduction and slow pressure increase repressurization.

On the other hand, if the spool is stuck at a position where both the large flow path and the small wave path are closed, the small flow path is closed and no liquid volume passes through the fixed orifice, so a pressure difference is generated before and after the orifice. Therefore, the bypass path remains open, and the hydraulic pressure passing through this bypass path can prevent troubles due to no braking.

Note that the bypass path remains open even when the anti-lock is not activated, but at this time, the inlet and outlet communicate through a large flow path, so the braking pressure only passes through the path with less resistance. No problem will occur even if the bypass path is opened.

〔Example〕

Embodiments of the present invention are shown in FIGS. 1 to 4.

The flow rate control valve 103 of the first embodiment shown in FIG. 1 is the control valve shown in FIG. This is the same as FIG. 5 in that the hydraulic pressure control system is shown only for one of the four wheels of the automobile. Therefore, the same parts will be denoted by the same reference numerals, and only the characteristic parts of the present invention will be described below. Note that 1, which is not explained in FIG. 5, is the brake pedal, 6 is the pump 61, and the motor e, ? , reservoir 6
PI is the braking pressure from the master cylinder.

As shown in the figure, a bypass passage 1) and a differential pressure valve 15 are provided in the housing 31 of the flow rate control valve 103, which are parallel to the large flow passage created between the inlet 31a and the outlet 31b via the outer circumferential groove 32a. be.

The differential pressure valve 15 has a hydraulic pressure responsive piston 15a as a differential pressure detection means which receives the hydraulic pressure introduced from the inlet 31a at the upper end and the hydraulic pressure introduced from the decompression chamber 36 at the lower end, and urges this piston upward. It consists of a spring 15b. The piston 15a that crosses the bypass passage 1) has a communication passage 15c for the bypass passage, and when the piston 15a moves downward due to the pressure difference before and after the fixed orifice 33 and the passage 15C moves to the closing point, the bypass passage 1) is shut off. be done. Furthermore, when the differential pressure across the fixed orifice 33 becomes smaller than the biasing force of the spring 15b, the piston 15a returns to the position shown in the figure and the bypass passage is reopened. Therefore, even if the spool 32 is stuck in the position where both the large passage closing part 32b and the small passage closing part 32c shown in FIG. 5A are closed, the solenoid valve 5 is closed when the anti-lock is not activated, Since there is no liquid flow passing through the orifice 33, no differential pressure is generated before and after the fixed orifice 33, the piston 15a does not move, and the bypass path is in a communicating state. Note that when the anti-lock pressure is reduced, the solenoid valve 5 is opened, a liquid flow is generated passing through the fixed orifice 33 toward the discharge port 31c, the piston 15a moves, and the bypass passage 1
) is closed, but when the spool is stuck in the above position, the small flow passage closing portion 32c remains closed, so the wheel brake 4
The hydraulic pressure does not drop, so the software can detect the abnormality. Then, when the solenoid valve 5 is closed by the repressurization command, the liquid flow through the fixed orifice 33 disappears.
Since the differential pressure between the front and rear disappears, the state immediately returns to the state when the anti-lock is not activated.

Next, in a second embodiment shown in FIG. 2, features of the present invention are added to a control valve that creates a large flow path via a flow path in the spool when the anti-lock is not activated. This control valve 203 is provided with a port 37a in the housing 31 from the viewpoint of workability.
~3? Including a sleeve 37 having a C. The spool 32 also has an input chamber 35 connected to a port 37 in the non-operating position.
a port P+ that communicates with the inlet 31a via port 31a, a port P that communicates the input chamber 35 with the outlet 31b via port 37b, and a port that communicates the outlet 31b with the decompression chamber 36 via port 37c during anti-lock depressurization. P, is provided.

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
A, port 37a, port P l s A large flow path leading to the outlet 31b via the input chamber 35, port Pz, and port 37b is secured.

When the solenoid 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 37C, the port P1, and the depressurization 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. Furthermore, 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 inlet 31a, port 3 is in the state shown in FIG.
7a, a small flow path leading to the outlet 31b via the variable orifice composed of this port and the metering edge 32d, the port Pl, the input chamber 35, the fixed orifice 33, the decompression chamber 36, the port P1, and the port 37C is secured. Ru.

Then, the opening degree 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 the prior art shown in FIG. 5, the flow rate becomes the flow rate when a differential pressure determined by the biasing force of the spring 34 and the effective cross-sectional area of the spool 32 acts before and after the orifice 33, and is kept constant. However, this control valve is also bo) P,,P, is port 3? b, 37
The spool 32 is at a position where it is simultaneously blocked by the sleeve wall between C.
If it gets stuck, problems with no braking will occur.

Therefore, the control valve 203 of the second embodiment is provided with a bypass passage 12 leading from the inlet 31a to the wheel brake side and a differential pressure valve 16. 31a, and the port position of the large flow path is set so that the large flow path closing portion 32b closes the port 37b to detect the pressure difference between the input chamber 35 and the decompression chamber 36. The differential pressure valve 16 operates by comparing the pressure difference between the hydraulic pressure from the input chamber 35 and the pressure reducing chamber 3.
It consists of a piston 16a for detecting a differential pressure that receives hydraulic pressure from 6 in opposite directions, a spring 16b that urges the piston upward, and a valve means 16d that has a separation spring 16C for the valve body. , the control valve of this second embodiment, which is almost the same as the first embodiment and will not be explained here, also has the following:
When the spool 32 is fixed at the position shown in FIG. 2A, the differential pressure valve 16 is in the state shown in FIG. 2 when the anti-lock is not activated, and the bypass passage 12 is opened, as in the first embodiment.

The flow control valve shown in FIG. 3 also differs from the one shown in FIG. 2 in the structure and installation position of the differential pressure valve 17, but there is no major difference in basic operation.
A bypass passage 13 provided between the air and the air is opened and closed by a differential pressure valve 17. The differential pressure valve 17 includes a piston 17a that receives the pressure of the decompression chamber 36 and the master cylinder pressure in opposite directions, and a spring 17 that urges this piston to receive the pressure of the pressurizing source.
b, and furthermore, piston 1? A valve means 17d is provided between the case 17C and the master cylinder pressure to detect the differential pressure between the master cylinder pressure and the pressure reducing chamber 36, and operates on the same principle as the differential pressure valve shown in FIG. 2 to open and close the bypass passage 13. do.

The control valve 403 in Fig. 4 is considered as a countermeasure in case the spool 32 becomes stuck at a position where the inlet 31a and the input chamber 35 are cut off, the ports Ps and 37c are communicated, and the decompression chamber 36 and the outlet 31b are connected. It is something that was given. In this control valve, a bypass passage 14 is provided between an outlet 31b and an input chamber 35.

Further, the sleeve 37 is made axially movable by a stroke L smaller than the stroke L at which the port 37a is closed to the metering edge 32d, and is biased upward by the spring 18b. A check valve 18d that opens when pushed by an operating shaft at the end of the sleeve is provided, and the differential pressure valve 18 is constructed from the above elements to simplify the overall structure.

When the pressure difference between the input chamber 35 and the pressure reduction chamber 36 is zero or small, this control valve uses a spring force to close the sleeve 3 for detecting the pressure difference.
7 is held in the position shown, and the bypass path 14 is opened. Therefore, the hydraulic pressure flowing from the passage 14 to the decompression chamber 36 via the fixed orifice 33 can move to the outlet 31b through the ports Ps and 3Tc, and can also return from the outlet side through the opposite path. .

In addition, when the decompression chamber 36 is opened with the spool 32 (not fixed), the sleeve 37 moves downward due to the differential pressure between the two chambers 35 and 36, and the differential pressure valve 18 opens the bypass passage 14.
is closed, so anti-lock control is not affected. The control valve shown in FIG. 4 can also directly guide the braking pressure that has passed through the check valve 18d to the outlet 31b. In this case, the control valve shown in FIG.
,,P3 is 3? Spool 32 at a position between b and 3Tc
Even if the wheel brakes become stuck, it is possible to raise and lower the pressure of the wheel brakes.

In the embodiments shown in FIG. 2 and later, the fixed orifice 33 is formed in the shim plate 38 and pressed against the inner step of the spool 32 by the force of the spring 34, thereby creating a high-pressure input chamber 35 and a low-pressure decompression chamber 36. When the differential pressure between them increases abnormally, the spring 34 can be compressed and moved toward the decompression chamber. Although this is not an essential configuration, if the fixed orifice 33 is blocked by foreign matter, the input chamber 35
When the liquid flow from the spool to the decompression chamber 36 is cut off, the shim plate 38 moves toward the decompression chamber due to the abnormal pressure difference, and a 35 Since a bypass path is created between .36 and 35.36, this configuration can be said to be extremely effective for the control valve of the present invention, which generates a liquid flow between 35 and 36 to eliminate the differential pressure in the compartment.

〔effect〕

As described above, the flow control valve of the present invention uses the differential pressure detection means to open the bypass passage parallel to the large flow passage when the differential pressure before and after the fixed orifice is below a certain value, and when the differential pressure exceeds a certain value. Since the bypass passage is closed when the anti-lock is activated, the master cylinder pressure can be applied to the wheel brake when the spool becomes stuck at a position where both the large flow passage and the small flow passage are closed, without causing any functional deterioration during anti-lock operation. This has the effect of eliminating the trouble of no-brake caused by the spool sticking and improving the reliability of the wheel brake.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing an example of the flow control valve of the present invention in a used state, Fig. 2 is a sectional view of a second embodiment, Fig. 2A,
Fig. 2B is a diagram showing the scale position during anti-lock operation in the second embodiment, Fig. 3 is a sectional view of the third embodiment, Fig. 4 is a sectional view of the fourth embodiment, and Fig. 5 is the conventional example. A cross-sectional view of
5A and 5B are explanatory views of the operation of the control valve of FIG. 5 during anti-lock operation. 1... Brake pedal, 2... Master cylinder, 4... Wheel brake, 5...
... Solenoid valve, 6 ... Pressure source, 103.203.303.403 ... Flow rate control valve, 1). 12.13.14...Bypass road,
15.16.17.18...Differential pressure valve, 31...
...Housing, 32...Spool,
32b...Large channel closing part, 32c...Small channel closing part, 32d...Metering edge, 33...
・Fixed orifice,

Claims (4)

[Claims] (1) A housing having at least two ports, an inlet that communicates with the master cylinder and an outlet that communicates with the wheel brake, and is slidably inserted into the housing and can switch the communication state between the two ports, It is equipped with a spool having a fixed orifice and a variable orifice whose flow path area can be changed by changing the corresponding position with respect to the housing, and a spring that biases this spool in one direction, and when the anti-lock is not activated. When the spool is in a non-operating position, it forms a large flow path connecting the inlet and the outlet, and when the anti-lock is re-pressurized, the spool moves from the non-operating position against the biasing force of the spring and first The large flow path is closed by the large flow path closing portion, and then the small flow path is further moved until the small flow path closure portion is in the open position, and the small flow path is connected between the inlet and the outlet via the fixed orifice and the variable orifice. When a flow path is formed, and the flow rate of this flow path is independent of the pressure difference between the inlet and the outlet, and 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. The anti-lock flow control valve is configured such that the flow path area of the variable orifice is adjusted to provide a constant flow rate, comprising: differential pressure detection means for detecting a fluid pressure difference before and after the fixed orifice; 1. A flow control valve for an anti-lock system, comprising: a normally open bypass path connecting said pressure difference detection means; and said bypass path is closed when the differential pressure detected by said pressure difference detection means exceeds a predetermined value. (2) The anti-lock flow control valve according to claim (1), wherein the differential pressure detection means is a hydraulic pressure responsive piston that receives pressures before and after the fixed orifice in opposite directions. (3) The anti-lock flow control valve according to claim (2), wherein the hydraulic pressure responsive piston is provided with a valve portion for opening and closing a bypass passage. (4) The anti-lock flow control valve according to claim (1), wherein a sleeve for housing the spool is provided between the housing and the spool so as to be slidable in the axial direction, and the sleeve serves as the differential pressure detection means.