JPH01262241A - Antilock control actuator for vehicle - Google Patents

Abstract

PURPOSE:To make it possible to efficiently operate air bleeding in a main passage and a return passage by providing a limiting means for maintaining a spool at a position except for a spool flow adjusting position in a flow control selector valve provided at the branch point of the main passage and the return passage. CONSTITUTION:In the case that air bleeding for a main passage from a master cylinder to a wheel brake is conducted, a stopper rod 30 is pushed in from the outside of a housing 14 of a flow control selector valve 100 provided at the branch point of a return passage to be abutted to a spool 16. Then, the connection of a large passage from a inlet port 11 to an outlet port 13 is obtained so that the air bleeding can be efficiently conducted. In the case that air bleeding for a return passage side is conducted, the spool 16 is maintained at a position except for a flow adjusting position by the operation of the stopper rod 30 so that a metering phenomenon does not occur and the air bleeding for the return passage can be efficiently conducted. Thus, the air bleeding opera tion for the main passage and the return passage can be efficiently conducted in a short time.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] This invention relates to an actuator for anti-lock control of wheel brakes of a vehicle.

[Prior Art] A typical anti-lock device is shown in FIG. 11. In the illustrated device, an electromagnetic intake valve 4 is provided in a main flow path 3 extending from a master cylinder 1 to a wheel brake 2. This electromagnetic suction valve 4 is a two-point/two-position switching valve, and is normally placed in the first position shown.

In this state, the electromagnetic suction valve 4 is in an open state.

On the other hand, when electric power is supplied to the electromagnetic suction valve 4, it is switched to the second position and becomes a closed state.

A circulation passage 5 branching from a branch point 8 of the main passage 3 joins the main passage 3 at a junction located between the master cylinder 1 and the electromagnetic intake valve 4. This circulation path 5 is provided with an electromagnetic discharge valve 7 and a circulation pump 6. Solenoid discharge valve 7
is a two-point, two-position switching valve, and the first valve shown in the figure is normally
has been brought to this position. In that position, the electromagnetic discharge valve 7 is in a closed state. On the other hand, when power is supplied to the electromagnetic discharge valve 7, it is switched to the second position and becomes open.

Reflux pump 6 pumps fluid toward confluence 9 .

In recent years, anti-lock devices have become popular, and the scope of their installation has expanded to include small cars. Along with this, it has become necessary to apply the brakes to vehicles having small brakes that consume less fluid. Furthermore, there is an urgent need to reduce costs.

In the device shown in FIG. 11, when the anti-lock control is not activated, both the electromagnetic intake valve 4 and the electromagnetic exhaust valve 7 are in the non-power state as shown. In this case, hydraulic pressure from the master cylinder 1 acts on the wheel brakes 2.

During pressure reduction during anti-lock control, both the electromagnetic intake valve 4 and the electromagnetic exhaust valve 7 are supplied with power. When maintaining the hydraulic pressure for the wheel brakes 2, only the electromagnetic intake valve 4 is supplied with power. When the pressure is increased during anti-lock control, both the electromagnetic intake valve 4 and the electromagnetic exhaust valve 7 are in a non-power state.

In order to maintain the amount of pressure increase in the pressure increase process of anti-lock control at an appropriate value, the method described below is adopted within the shell. The first method is to insert an orifice into the main flow path 3 to adjust the flow rate of the main flow path. In the second method, when repressurizing the wheel brake 2 following a pressure reduction process in which both the electromagnetic intake valve 4 and the electromagnetic discharge valve 7 are in a power supply state, a pressurization state in which both the electromagnetic valves 4 and 7 are in a non-power supply state is adopted. This is a method of increasing the brake pressure in a stepwise manner by combining this and a holding state in which only the electromagnetic intake valve 4 is supplied with power, thereby achieving a moderate amount of pressure increase on average.

In the case of brakes that consume a small amount of fluid, such as those used in small cars, it is necessary to keep the flow rate low in order to maintain the same amount of pressure increase. Therefore, when adopting the first method, it is necessary to make the orifice in the main flow path 3 smaller. Furthermore, when the second method is employed, it is necessary to shorten the time of the boosting portion in the stepwise boosting process.

However, when the orifice in the main flow path is made small, the flow rate is restricted even when the pressure is increased when the anti-lock control is not activated, resulting in a delay in increasing the pressure during emergency braking, for example. It is also conceivable that foreign matter in the brake piping system may block the orifice, leading to a no-brake condition.

Further, even if an attempt is made to shorten the time of the pressure increasing part in the stepwise pressure increasing process, there is a limit in terms of the responsiveness of the solenoid valves 4 and 7.

In order to solve the above-mentioned problems, anti-lock control actuators as shown in FIGS. 12 and 13 have been proposed. In these figures the 11th
Elements labeled with the same numbers as those used in the figures indicate the same or equivalent elements. Therefore, specific explanations about them will be omitted.

In the apparatus shown in FIGS. 12 and 13, a flow control switching valve 10 is provided at the branch point 8 of the main flow path 3 instead of the electromagnetic suction valve 4 described above. The flow rate control switching valve 10 operates to selectively open and close a flow path from the master cylinder 1 to the wheel brakes 2.

Specifically, the flow rate control switching valve 10 includes a housing 14, a spool 16, and a return spring 17. The housing 14 includes an inlet port 11 facing the master cylinder 1 side, a first outlet port 13 facing the wheel brake 2 side, and a second outlet port 12 facing the exhaust valve 7 side. A storage space is formed inside the housing 14, and a fixing member 15 and a spring support member 24 are fixedly attached within this space. The fixed member 15 is
Ports 11a and llb communicating with the inlet port 11, and a port 13a communicating with the first outlet port 13;
and a port 12a communicating with the second outlet port 12. Furthermore, a communication path 2 is provided on the inner circumference of the fixing member 15.
3 is formed.

The spool 16 is arranged within the storage space of the housing 14 so as to be slidable in the axial direction. The spool 16 defines a fluid passageway including orifices 21 and 22 therein. The spool 16 also has a bow 18, 20 communicating with the internal fluid passageway and a groove 19 on its outer periphery, as shown.

The return spring 17 is arranged such that one end thereof contacts the spool 16 and the other end or spring receiver contacts the member 24. This return spring 17 urges the spool 16 in one direction, that is, to the left in the figure.

The state shown in FIG. 12 is a state in which anti-lock control is not performed, that is, the anti-lock control is inactive. The state shown in FIG. 13 corresponds to the pressure reduction process of anti-lock control.

The shapes and mutual positional relationships of the elements constituting the flow rate control switching valve 10 are selected so as to achieve the operations described below.

When the anti-lock control is not activated as shown in FIG. 12, the spool 16 is brought to the non-activated position by the urging force of the return spring 17. In this state,
A large flow path is formed between the inlet port 11 and the first outlet port 13, which includes ports 11a, 11b, port 18, groove 19, and port 13a. This large flow path can pass a large flow of fluid.

Next, assume that the discharge valve 7 is opened during pressure reduction during anti-lock control. Then, a fluid flow is formed from the main flow path 3, passing through the orifices 21, 22 and heading toward the return flow path 5. Correspondingly, a pressure difference is created before and after the orifice 21 and before and after the orifice 22. Due to this differential pressure, the spool 16 slides to the right in the figure against the biasing force of the return spring 17, thereby closing the aforementioned large flow path. This state is the state shown in FIG.

In the state shown in FIG. 13, the port 11a of the fixing member 15
Communication between the port 18 of the spool 16 and the port llb of the fixing member 15 is cut off, and the communication between the port llb of the fixing member 15 and the groove 19 of the spool 16 is cut off.
Communication with the government has also been cut off.

On the other hand, a reduced pressure flow path is formed from the first outlet port 13 to the second outlet port 12. This reduced pressure flow path is constituted by the port 13a of the fixed member 15, the groove 19 of the spool 16, the communication path 23 of the fixed member 15, the port 20 of the spool 16, and the orifice 22. In this way, the fluid acting on the wheel brake 2 is discharged to the circulation path 5 via the pressure reduction path.

Assume that from the state shown in FIG. 13, the discharge valve 7 is brought into a non-power-supplied state and a transition is made to the pressure increasing process of anti-lock control. In this case, since the discharge valve 7 is in the closed state, the flow of the fluid in the aforementioned pressure reduction channel is stopped. Then, a small flow path from the main flow path 3 toward the wheel brake 2 is formed. This small flow path includes the port 18 of the spool 16, the orifice 21,
Port 20, communication path 23 of fixing member 15, spool 16
and the port 13a of the fixing member 15. A pressure difference is generated before and after the orifice 21.

The spool 16 due to the differential pressure generated before and after the orifice 21
If the biasing force of Close the small channels.

On the other hand, the spool 16 due to the differential pressure before and after the orifice 21
If the biasing force against the return spring 17 is smaller than the biasing force of the return spring 17, the spool 16 returns to the flow adjustment position and the port 11a of the fixed member 15 and the spool 16
and the port 18 of the computer. As a result, the main flow path 3
A small flow path is formed again from the wheel brake 2 to the wheel brake 2.

In this way, the amount of liquid passing through the small channel is reduced by the return spring 1
It is controlled by the differential pressure across the orifice 21 determined by the biasing force of 7 and the effective area of the spool 16. Such control is generally referred to as "metalling."

The devices shown in Figures 12 and 13 avoid pressure increase delays by ensuring a large flow path during normal braking, and by ensuring a small flow path through which a minute amount of liquid passes during anti-lock pressure increase. Appropriate gradual pressure increase is achieved. Moreover, since the electromagnetic suction valve 4 shown in FIG. 11 is not required, the cost can be reduced. In addition, an electronic control circuit for driving the electromagnetic intake valve 4 is not required, and the present invention can meet the need for cost reduction for use in small vehicles.

[Problems to be Solved by the Invention] However, the following problems also occur in the above-mentioned device.

First of all, when air is removed from the reflux channel 5, a liquid flow passes through the orifices 21 and 22. Therefore, the metaling phenomenon described above occurs between the tip edge 16a of the spool 16 and the port 12a of the fixing member 15. As a result, only the fluid passes through the second outlet port 12 at a flow rate based on the differential pressure determined by the biasing force of the return spring 17. As described above, when air is removed from the circulation path 5, the air removal efficiency is very poor, and therefore it takes a long time.

Second, a similar problem occurs when air is removed from the main flow path, for example when air is removed from the wheel brakes 2. That is, if air remains between the second outlet port 12 and the discharge valve 7, a liquid flow passing through the orifices 21 and 22 will occur, causing the spool 16 to move and move the air between the inlet port 11 and the first outlet port. 13 will be blocked. In that case, it becomes impossible to bleed air.

Therefore, it is an object of the present invention to
It is an object of the present invention to provide an actuator for anti-lock control of a vehicle that can efficiently bleed air from a circulation passage and a main passage in a device as shown in the figure.

[Means for Solving the Problems] A vehicle anti-lock control actuator, which is a premise of the present invention, includes a main flow path, a circulation path, a circulation pump, a discharge valve, and a flow rate control switching valve. The main flow path extends from the master cylinder to the wheel brakes. The circulation path is provided so as to branch from the main flow path and join the main flow path closer to the master cylinder than the branch point. The reflux pump is provided in the reflux path and sends the fluid toward the confluence point. The discharge valve is provided between the branch point and the return flow path, and selectively opens and closes the flow path. The flow control switching valve is provided at the branch point and selectively opens and closes the flow path from the master cylinder to the wheel brakes.

The flow rate control switching valve includes a housing, a spool, and a return spring. The housing has an artificial port facing the master cylinder side, a first outlet port facing the wheel brake side, and a second outlet port facing the exhaust valve side, and also forms a storage space inside. The spool is disposed within the storage space of the housing so as to be slidable in the axial direction thereof, and forms a fluid passageway including an orifice therein. A return spring biases the spool in one direction.

The shapes and mutual positional relationships of the elements constituting the flow rate control switching valve are selected so as to achieve the operations described below.

That is, when the anti-lock control is not activated, the spool is brought to the deactivated position by the biasing force of the return spring, thereby creating a large flow that allows a large amount of fluid to pass between the inlet port and the first outlet port. form a road.

When the discharge valve is opened during pressure reduction during anti-lock control, a fluid flow is formed from the main flow path, through the orifice, and toward the return flow path. Correspondingly, a pressure difference is created across the orifice, and this pressure difference causes the spool to slide against the biasing force of the return spring, thereby closing the large flow path. At the same time, by forming a depressurizing flow path from the first outlet port to the second outlet port, fluid acting on the wheel brakes is discharged to the circulation path.

When the discharge valve is closed and the flow of fluid in the pressure reduction channel is stopped during pressure increase during anti-lock control, a small channel is formed that passes from the main channel through the orifice to the wheel brake. Correspondingly, a pressure differential develops across the orifice. If the biasing force against the spool due to this differential pressure exceeds the biasing force of the return spring, the spool moves beyond the flow rate adjustment position and closes the small flow path. On the other hand, if the biasing force against the spool due to the differential pressure is less than the biasing force of the return spring, the spool returns to the flow rate adjustment position and brings the small flow path into communication. In this way, the amount of liquid passing through the small channel is 1. It is controlled by the differential pressure across the orifice determined by the biasing force of the return spring and the effective area of the spool.

In the anti-lock control actuator for a vehicle as described above, the present invention provides a flow control switching valve further comprising a restricting means that abuts the spool and holds the spool at a position other than the flow rate adjustment position. It is characterized by

[Operation] In the present invention, the restricting means contacts the spool and holds the spool at a position other than the flow rate adjustment position.

Therefore, when air is removed from the circulation path or the main flow path, the metaling phenomenon described above does not occur.

In the device shown in FIGS. 12 and 13, when air is removed from the circulation path, the flow rate of the fluid is only as high as when a differential pressure determined by the biasing force of the return spring and the cross-sectional area of the spool acts on the orifice. However, in this invention, there is a large pressure difference between the pressure upstream of the orifice, that is, the pressure at the inlet port and the pressure at the second outlet port, and the amount of liquid passing through the small channel is large. Become.

In addition, with this invention, even when air is removed from the main flow path, the spool can be held in a position that ensures communication between the large flow paths, so the large flow path is not closed and air is removed efficiently. can be done.

[Embodiments] Various embodiments of the present invention are shown in FIGS. 1 to 10. Each of these embodiments is illustrated in FIGS. 12 and 13.
The difference from the device shown in the figure is that the flow rate control switching valve further includes a limiting means that abuts the spool 16 and holds the spool 16 in a position other than the flow rate adjustment position.

In other respects, there is no difference between each of the embodiments described below and the apparatus shown in FIGS. 12 and 13. Therefore, in FIGS. 1 to 10, the same or corresponding elements as shown in FIGS. 12 and 13 are given the same numbers. In addition, only the structure and operation related to the limiting means will be explained below.

1 and 2 are sectional views showing essential parts of a first embodiment of the invention.

The illustrated flow control switching valve 100 has a housing 14 and a stopper rod 3 extending through a spring bearing member 24.
0. This stopper rod 30 is provided so as to be movable in the axial direction of the spool 16, and is supported by a spring 31.
is always urged in a direction away from the spool 16. The stopper rod 30 has one end connected to the housing 1.
The housing 14 is located within the storage space of the housing 14 so that it can come into contact with the spool 16, and the other end protrudes outside the housing 14.

FIG. 1 shows a normal brake state, that is, a state in which anti-lock control is not activated. In this state, the stopper rod 30 is pushed against the spool 16 by the biasing force of the spring 31.
It is kept in a position where it does not come into contact with the

FIG. 2 shows a state in which air is removed from the main flow path. In this case, one end of the stopper rod 30 is brought into contact with the spool 16 by manually pushing the stopper rod 30 from outside the housing 14 . As a result, the spool 16 remains fixed in the state shown in FIG.
The communication of the large flow path leading up to the point is ensured. If the state shown in FIG. 2 is maintained until the shallow air operation is completed, air can be removed efficiently and in a short time.

Even when venting air from the circulation path side, if the spool 16 is held at a position other than the flow rate adjustment position by operating the stopper rod 30, the metal ring phenomenon will not occur and the air from the circulation channel can be efficiently vented. be able to.

3 and 4 are cross-sectional views showing a flow rate control switching valve 101 according to a second embodiment of the present invention.

In this embodiment, the pushing member 32, the spring bearing member 24, and the return spring 17 are used as a limiting means for holding the spool 16 at a position other than the flow rate adjustment position. The push member 32 has one end or the spring receiver is the member 24.
The other end protrudes to the outside of the housing 14. Both the pushing member 32 and the spring bearing member 24 are
It is provided so as to be movable in the axial direction of the spool 16.

In the normal braking state shown in FIG. 3, the spring bearing member 24 and the pushing member 32 are
7 is maintained in a position away from the spool 16.

To bleed air, the push member 32 is pushed in from the outside of the housing 14.

Then, as shown in FIG. 4, the pushing member 32 and the spring receiver both move in the direction in which the member 24 approaches the spool 16, compressing the return spring 17. As a result, the biasing force of the return spring 17 against the spool 16 increases, and the spool 16 is held fixed at a position where the large flow path formed between the inlet port 11 and the first outlet port 13 is brought into communication.

5 and 6 are cross-sectional views showing a flow rate control switching valve 102 according to a third embodiment of the present invention.

In this embodiment, the stopper rod 33 is used as the limiting means.
and spring 34 are used. Stopper rod 33
is provided so as to be movable in a direction perpendicular to the axial direction of the spool 16, and one end thereof extends through the fixed member 15 and faces the hydraulic pressure chamber where the spool 16 is present. , the other end protrudes to the outside of the housing 14. The spring 34 biases the stopper rod 33 in one direction.

In the normal braking state shown in FIG.
It is kept in a position where it does not come into contact with 6.

To bleed air, the stopper rod 33 is pushed in from the outside of the housing 14. Then, as shown in FIG. 6, one end of the stopper rod 33 projects onto the inner surface of the fixing member 15. Therefore, spool 1
If the spool 6 moves slowly to the right from the illustrated state, the tip of the spool 16 will come into contact with the stopper rod 33, and no further movement will be possible.

7 and 8 are cross-sectional views showing a flow rate control switching valve 103 according to a fourth embodiment of the present invention.

In this embodiment, the stopper rod 35 is used as the limiting means.
is used. This fourth embodiment is structurally similar to the third embodiment described above, except that the stopper rod 35
It is different in that it does not use a spring to return the

Specifically, the stopper rod 35 has a piston portion 35a, and the housing 14 corresponds to the piston portion 35a.
A cylinder portion 140 is formed in which the piston portion 35a is slidably received.

A seal member 35b is attached to the piston portion 35a of the stopper rod 35 to maintain liquid-tightness and airtightness. The cylinder portion 140 of the housing 14 has two chambers 140a and 140b that are separated by a seal member 35b. One chamber 140a is
The spool 16 communicates with the existing hydraulic chamber, and the other chamber 140b is at atmospheric pressure.

For example, assume that the actuator manufacturer performs an air bleeding operation in advance and delivers the actuator to the user in that state. When the manufacturer performs the air bleeding operation, by pushing the stopper rod 35 from the outside,
One end of the stopper rod 35 is made to protrude onto the inner surface of the fixing member 15. This state is the state shown in FIG. Then, the main flow path and the circulation path are brought into a vacuum state. Then, the piston wood 35 is energized by atmospheric pressure and moves to the eighth position.
It is fixed and maintained in the state shown in the figure. The device is delivered to the user in this state, and the flow path is filled with working fluid at the user's end. When the liquid pressure acting on the piston portion 35a of the stopper rod 35 exceeds atmospheric pressure, the piston rod 35
is retracted to the non-operating position shown in FIG.

With the above configuration, the stopper rod 35 automatically returns to the non-operating position when pressurizing for the first time after air bleeding is completed, so there is no possibility of forgetting to return the stopper rod 35 to the non-operating position. It cannot occur.

Although not shown, as a fifth embodiment, the chamber 14 of the cylinder portion 140 shown in the above-mentioned fourth embodiment
A spring may be placed within 0b.

This spring biases the stopper rod 35 into its operative position. In such a configuration, the hydraulic pressure acting on the piston portion 35a of the stopper rod 35 is
When the biasing force of the spring becomes larger, the stopper rod 35 retreats to the non-operating position.

9 and 10 are cross-sectional views showing a flow rate control switching valve 104 according to a sixth embodiment of the present invention.

In this embodiment, a recess 37 formed on the outer surface of the spool 16 and a stopper rod 36 capable of engaging with the recess 37 are used as the limiting means. The stopper rod 36 is provided so as to be movable in a direction perpendicular to the axial direction of the spool 16, and has one end facing the hydraulic pressure chamber in which the spool 16 is present, and the other end protruding to the outside of the housing 14. . Stopper rod 36
has a piston portion, similar to the fourth embodiment described using FIGS. 7 and 8. One end of this piston portion faces the hydraulic pressure chamber in which the spool 36 is present, and the other end faces atmospheric pressure.

When the manufacturer performs an air bleeding operation, the stopper rod 36 is pushed in from the outside of the housing 14, so that the tip of the stopper rod 36 and the recess 37 of the spool 16 are engaged. With this engagement, spool 1
The position of 6 is fixed, and the air bleeding operation can be performed efficiently. On the user side, for example, the main flow path and the circulation path are brought into a vacuum state. Then, the stopper rod 36 is urged by the atmospheric pressure acting on its piston portion, and maintains the engaged state shown in FIG. 9. It is delivered to the user in that state. When the user fills the working fluid and pressurizes the brake, the hydraulic pressure acting on the piston portion of the stopper rod 36 becomes greater than atmospheric pressure, and as a result, the stopper rod 36 becomes inoperative as shown in FIG. Return to position.

[Effects of the Invention] As described above, in this invention, the flow rate control switching valve is provided with the restricting means that abuts the spool and holds the spool at a position other than the flow rate adjustment position. Air removal from the circulation path can be carried out efficiently and in a short time.

[Brief explanation of the drawing]

FIGS. 1 and 2 are cross-sectional views showing essential parts of an embodiment of the present invention, with FIG. 1 showing the normal usage state and FIG. 2 showing the state when performing an air bleeding operation. There is. 3 and 4 are sectional views showing essential parts of other embodiments of the present invention, with FIG. 3 showing the normal usage state and FIG. 4 showing the state when performing the air bleeding operation. It shows. 5 and 6 are cross-sectional views showing still other embodiments of the present invention, with FIG. 5 showing the normal usage state and FIG. 6 showing the state when performing the air bleeding operation. There is. 7 and 8 are sectional views showing essential parts of still another embodiment of the present invention, with FIG. 7 showing the normal usage state and FIG. 8 showing the state when performing the air bleeding operation. It shows. 9 and 10 are sectional views showing essential parts of still another embodiment of the present invention, with FIG. 9 showing the state when performing an air bleeding operation, and FIG. 10 showing the normal use state. It shows. FIG. 11 is a hydraulic circuit diagram of a conventional anti-lock device. 12 and 13 are diagrams showing a conventional device that is an improved version of the device shown in FIG. 11. FIG. 12 shows a normal brake operation state, and FIG. 13 shows a reduced pressure state for anti-lock control. It shows. In the figure, 1 is the master cylinder, 2 is the wheel brake,
3 is a main flow path, 5 is a circulation path, 6 is a circulation pump, 7 is an electromagnetic discharge valve, 10, 100, 101, 102, 103, 104
1 is a flow control switching valve; 11 is an inlet port; 12 is a second outlet port; 13 is a first outlet port; 14 is a housing;
6 is the spool, 17 is the return spring, 21.22
is an orifice, 30 is a stopper rod, 31 is a spring, 3
2 is a push member, 33 is a stopper rod, 34 is a spring, 3
5 is a stopper rod, 36 is a stopper rod, and 37 is a recess. Note that in each figure, the same numbers indicate the same or corresponding parts. Figure 1 Figure 2 Figure 3 Figure 4 Figure 11 Figure 13

Claims (1)

[Scope of Claims] A main flow path extending from a master cylinder to a wheel brake; a circulation path branching from the main flow path and merging with the main flow path closer to the master cylinder than the branch point; a reflux pump that is provided in the reflux path and sends fluid toward the merging point; a discharge valve that is provided between the branch point and the reflux pump that selectively opens and closes the flow path; a flow rate control switching valve that selectively opens and closes a flow path from the master cylinder to the wheel brake; the flow rate control switching valve includes: an inlet port facing the master cylinder side, and an inlet port facing the wheel brake side. a housing having a first outlet port and a second outlet port facing the discharge valve side and forming a storage space therein; , a spool forming a fluid passage including an orifice therein, and a return spring biasing the spool in one direction, and each element constituting the flow rate control switching valve is as follows. , i.e. when the anti-lock control is inactive, the spool is brought to the inactive position by the biasing force of the return spring, thereby connecting the inlet port and the first
A large flow path through which a large flow of fluid passes is formed between the main flow path and the outlet port, and when the discharge valve is opened during depressurization during anti-lock control, the fluid flows from the main flow path through the orifice. A fluid flow toward the circulation path is formed, and a pressure difference is generated before and after the orifice. Due to this pressure difference, the spool slides against the biasing force of the return spring, and flows through the large flow path. and at the same time, by forming a depressurizing flow path from the first outlet port to the second outlet port, the fluid acting on the wheel brake is discharged to the circulation path, and at the time of pressure increase for anti-lock control. When the discharge valve is brought into a closed state and the flow of fluid in the pressure reduction channel is stopped,
A small flow path is formed from the main flow path through the orifice toward the wheel brake, and a pressure difference is generated before and after the orifice, and the urging force against the spool due to this pressure difference causes the return spring to be biased. If the force exceeds the force, the spool moves beyond the flow rate adjustment position and closes the small flow path, and if the biasing force against the spool due to the differential pressure is less than the biasing force of the return spring. , the spool returns to the flow rate adjustment position to bring the small channel into communication, and as a result, the amount of liquid passing through the small channel is determined by the biasing force of the return spring and the effective area of the spool. In the actuator for anti-lock control of a vehicle, the shape and mutual positional relationship of the actuator are selected so as to achieve an operation controlled by a pressure difference before and after the orifice, the flow control switching valve further comprising: An actuator for anti-lock control of a vehicle, comprising a limiting means that abuts the spool and holds the spool at a position other than the flow rate adjustment position.