JPH08310369A - Fluid pressure controller - Google Patents

Abstract

PURPOSE: To efficiently perform working fluid suction, which is carried out by means of a hydraulic pump, inside a fluid chamber of a reservoir. CONSTITUTION: In a reservoir 11, a piston 17 is slidably inserted into a cylindrical bottomed internal hole 16 bored in a cylinder 15, and a fluid chamber 18 is formed of the internal hole 16 and the piston 17. The inner circumferential face of the internal hole 16 is provided with a large diameter part, 16a, a slanting diameter part 16b, and a small diameter part, 16c in the axial direction of the inside hole 16 in this order from the fluid chamber 18 side. On the outer circumferential face of the piston 17, a circumferential groove 17a is formed in the circumference direction of the piston 17 at the predetermined distance from the fluid chamber 18, and in the inside of the circumferential groove 17a, a seal member 19 made of an elastic body is arranged so as to be brought into contact with the internal hole 16 and the piston 17 outer circumferential face. The first port 12 in the fluid chamber 18 is connected to a hydraulic pump 10, and working fluid inside the fluid chamber 18 is sucked by means of the hydraulic pump 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic control device for controlling hydraulic pressure.

[0002]

2. Description of the Related Art Conventionally, a vehicle such as an automobile is equipped with a brake device as one of hydraulic pressure control devices, and an example thereof is a brake hydraulic pressure control device disclosed in Japanese Utility Model Laid-Open No. 2-49667. be able to.

In the brake fluid pressure control device disclosed in Japanese Utility Model Laid-Open No. 2-49667, when hydraulic fluid is discharged from a wheel cylinder of a brake that suppresses wheel rotation into a fluid chamber of a reservoir, the brake fluid pressure control device is arranged in the cylinder of the reservoir. The piston is pushed by the hydraulic fluid and slides in the inner hole of the cylinder in the direction in which the volume of the liquid chamber increases. Further, a hydraulic pump is connected to the liquid chamber, and when the hydraulic pump operates, the working fluid in the liquid chamber is sucked by the suction force of the hydraulic pump, and at the same time, the piston keeps the volume of the liquid chamber in the inner hole. It is designed to slide in a decreasing direction.

An O-ring is provided between the inner hole of the cylinder and the outer peripheral surface of the piston, and the liquid chamber is sealed so that the working liquid does not leak from the liquid chamber. The piston is pushed by the hydraulic fluid discharged from the wheel cylinder, reaches the position where it cannot slide in the direction in which the volume of the liquid chamber increases in the inner hole of the cylinder, and the hydraulic fluid is further discharged from the wheel cylinder. And the liquid pressure in the liquid chamber rises sharply. Even if the fluid pressure in the fluid chamber suddenly rises to a high pressure, the hydraulic fluid does not leak from the fluid chamber. The pressure generated by being pressed against the hole and the outer peripheral surface of the piston) is increased.

[0005]

However, in the brake fluid pressure control device as described above, the seal pressure by the O-ring is constant. Even when high pressure does not act on the liquid chamber and a high sealing pressure is unnecessary, the sealing pressure is high. When the seal pressure of the O-ring is increased, the sliding resistance between the piston and the cylinder increases.
Therefore, in the brake fluid pressure control device as described above, the sliding resistance between the piston and the cylinder remains large even when high pressure does not act on the fluid chamber and a high sealing pressure is unnecessary. As a result, the efficiency of sucking the working fluid into the fluid chamber is low.

According to the present invention, by changing the seal pressure at the piston position, when high pressure does not act on the liquid chamber and a high seal pressure is unnecessary, the sliding resistance between the piston and the cylinder is reduced to reduce the liquid pressure. An object of the present invention is to efficiently suck the working fluid into the liquid chamber by the pressure pump.

[0007]

In order to solve the above problems, the present invention provides a piston, a cylinder having an inner hole into which the piston is slidably inserted, and an inner hole of the cylinder and the piston. It is fixed to one of the liquid chamber formed between the inner hole of the cylinder and the outer peripheral surface of the piston, and is pressed against the inner hole of the cylinder and the outer peripheral surface of the piston to seal the liquid chamber. In a hydraulic control device comprising a reservoir formed of a seal member, a hydraulic fluid supply means for supplying hydraulic fluid to the fluid chamber, and a hydraulic pump for sucking the hydraulic fluid in the fluid chamber, the piston is the cylinder. The pressure contact force of the seal member in at least a part of a region slidable in the inner hole of the cylinder in the direction of increasing the volume of the liquid chamber, the piston increases the volume of the liquid chamber in the inner hole of the cylinder. You Is characterized in further comprising a sealing pressure varying means to be smaller than the pressing force of the sealing member of the sliding impossible positioned in the direction.

[0008]

According to the fluid pressure control device having the above construction, when the working fluid is supplied from the working fluid supply means to the fluid chamber of the reservoir, the piston is pushed by the working fluid, and the volume of the fluid chamber is reduced within the inner hole of the cylinder. Sliding in an increasing direction. When the working fluid is still supplied and the piston reaches the position where it cannot slide in the cylinder bore in the direction of increasing the volume of the liquid chamber, the seal pressure varying means strongly presses the seal member against the piston and the cylinder. Further, in at least a part of the region where the piston can slide in the cylinder inner hole in the direction of increasing the volume of the liquid chamber (the region where high pressure does not act on the liquid chamber), the seal pressure varying means causes the seal member to move to the piston and the cylinder. The pressure contact force of pressure contact is reduced. Therefore, in at least part of the case where the piston slides in the cylinder inner hole in the direction in which the volume of the liquid chamber decreases due to the suction of the hydraulic fluid by the hydraulic pump, the pressure contact force with which the seal member is pressed against the piston and the cylinder is small. To be done.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the hydraulic pressure control device of the present invention is applied to a brake hydraulic pressure control device for suppressing the rotation of the wheels of a vehicle will be described below. FIG. 1 is a hydraulic circuit diagram in which the hydraulic pressure control device according to the first embodiment of the present invention is applied to a brake hydraulic pressure control device. Although the master cylinder 1 shown in FIG. 1 has two discharge ports, the same discussion can be made in both systems, so only the first system will be described in FIG. 1, and description of the other systems will be omitted.

In FIG. 1, the master cylinder 1 is connected via a switching valve 2 and a switching valve 3 to a left rear wheel wheel cylinder 7 provided in a brake of a left rear wheel, which is a driving wheel, and is switched. It is connected via a valve 2 and a switching valve 4 to a right rear wheel wheel cylinder 8 provided in a brake of a right rear wheel which is a driving wheel.

The conduit between the switching valve 3 and the left rear wheel wheel cylinder 7 is connected to the first port 12 of the reservoir 11 via the switching valve 5, and the switching valve 4 and the right rear wheel wheel cylinder 8 are connected. The line between the reservoir 1 and the reservoir 1 is connected via the switching valve 6.
1 is connected to the first port 12. Further, the first port 12 of the reservoir 11 is connected to the suction port of the hydraulic pump 10, and the discharge port of the hydraulic pump 10 is connected to the conduit between the switching valve 2 and the switching valve 3 and the switching valve 4. In addition to being connected, it is connected via a relief valve 9 to a conduit between the master cylinder 1 and the switching valve 2. The relief valve 9 blocks the flow of hydraulic fluid from the master cylinder 1 toward the hydraulic pump 10, but allows the flow in the opposite direction at a set pressure or higher. The relief valve 9 has a valve element 9a and a valve seat 9b, and the valve element 9a is always biased by a spring 9c as a biasing means so as to be seated on the valve seat 9b. Therefore, the relief valve 9 is normally closed, and the hydraulic pressure in the pipeline of the relief valve 9 on the hydraulic pump 10 side is determined by the spring 9c rather than the hydraulic pressure of the pipeline on the master cylinder 1 side of the relief valve 9. The hydraulic fluid flows from the hydraulic pump 10 side of the relief valve 9 to the master cylinder 1 side when the valve element 9a is separated from the valve seat 9b by becoming larger than the set pressure.

An inflow control valve 14 is provided in the second port 13 of the reservoir 11, and the second port 13 is connected to the conduit between the master cylinder 1 and the switching valve 2 via the inflow control valve 14. Has been done.

In the reservoir 11, a piston 17 is slidably inserted into a cylindrical inner hole 16 having a bottom formed in a cylinder 15, and the first port 12 and the second port 13 are the cylinders. 15 is formed in the bottom wall 15a. A liquid chamber 18 is formed by the inner hole 16 and the piston 17. The liquid chamber 18 is communicated with the first port 12 and the second port 13, and the working liquid is stored in the liquid chamber 18. The inner diameter of the inner hole 16 is such that the cylinder 1 extends in the axial direction of the inner hole 16.
5 has a large diameter portion 16a having a large diameter on the side of the bottom wall 15a and a small diameter portion 16c having a small diameter on the side opposite to the side of the bottom wall 15a of the cylinder 15, and has a large diameter portion 16a and a small diameter portion 16c. And a slanted portion 16b whose diameter is slanted in the axial direction of the inner hole 16 are formed, and the inner diameter of the slanted portion 16b on the bottom wall 15a side of the cylinder 15 is the same as that of the large diameter portion 16a. The inner diameter of the cylinder 15 on the side opposite to the bottom wall 15a side has a small diameter portion 16
It is the same as c. A circumferential groove 17a is formed on the outer circumferential surface of the piston 17 in the circumferential direction of the piston 17, and an annular seal member (O-ring) 19 made of an elastic body (rubber) is provided in the circumferential groove 17a. It is fixed. The seal member 19 is sized so as to come into pressure contact with the inner hole 16 and the outer peripheral surface of the piston 17, and seals the liquid chamber 18 so that the hydraulic fluid does not leak from the liquid chamber 18.

When the volume of the liquid chamber 18 increases from the inoperative position shown in the drawing, the piston 17 moves from the inoperative position shown in the increasing direction (downward in FIG. 1) to the volume not shown in the drawing. When the piston 17 decreases from the operating position, the piston 17 slides in the volume decreasing direction (upward in FIG. 1) from the non-operating position shown. Liquid chamber 1 of piston 17
A spring 20 as an urging means is engaged on the side opposite to 8 via a retainer 21, and the other end of the spring 20 is fixed to a lid 30 provided in the cylinder 15 so as to close the inner hole 16. The spring force of the spring 20 is the piston 1
7 is added. Retainer 2
1 is provided with a flange portion, and the flange portion comes into contact with a stepped portion 16d provided on the small diameter portion 16c of the inner hole 16 to restrict the approach limit of the cylinder 15 to the bottom wall 15a. . Moreover, the retainer 21 is loosely fitted to the piston 17, so that the piston 17
When the retainer 21 slides in the direction of decreasing the volume of the original position liquid chamber 18 when the volume of the liquid chamber 18 decreases from the inoperative position shown in the drawing, the pin 22 engages with the valve element 14a, and the piston 22 17 moves the valve element 14a in a direction away from the valve seat 14b via the pin 22. As a result, the valve element 14a is separated from the valve seat 14b, and the working fluid in the master cylinder 1 is allowed to flow into the liquid chamber 18 in an inflow permitted state.

The switching valves 2, 3, 4, 5, 6 and the hydraulic pump 10 described above are connected to a controller (not shown), and the controller is mainly composed of a computer. Various programs for executing anti-lock brake control and traction control control are stored in the ROM of the computer, and the CPU is RAM
Anti-lock brake control and traction control control are executed by executing various programs while using the. The anti-lock brake control prevents the wheels from locking when the vehicle is braked, and the traction control control prevents the drive wheels from idling when the vehicle is driven.

In the normal braking state, the controller is
Switching valve 2 is demagnetized (open state), switching valve 3 is demagnetized (open state), switching valve 4 is demagnetized (open state), switching valve 5
Is demagnetized (closed), switching valve 6 is demagnetized (closed)
The master cylinder 1 allows the hydraulic pressure of the left rear wheel wheel cylinder 7 and the right rear wheel wheel cylinder 8 to be increased or decreased. In addition, a reverse valve is provided in parallel with the switching valve 2, and the reverse valve is operated from the master cylinder 1 by performing a brake operation when the switching valve 2 is closed when the traction control control is activated. The liquid is allowed to flow to the wheel cylinders 7 and 8 through the reverse valve. Further, the reversing valves are also provided in parallel to the switching valves 3 and 4, and these reversing valves are operated when the antilock brake control is activated.
Also, when the switching valve 4 is closed, the drive wheels are prevented from idling when the vehicle is driven.

In the normal braking state, the controller is
Switching valve 2 is demagnetized (open state), switching valve 3 is demagnetized (open state), switching valve 4 is demagnetized (open state), switching valve 5
Is demagnetized (closed), switching valve 6 is demagnetized (closed)
The master cylinder 1 allows the hydraulic pressure of the left rear wheel wheel cylinder 7 and the right rear wheel wheel cylinder 8 to be increased or decreased. In addition, a reverse valve is provided in parallel with the switching valve 2, and the reverse valve is operated from the master cylinder 1 by performing a brake operation when the switching valve 2 is closed when the traction control control is activated. The liquid is allowed to flow to the wheel cylinders 7 and 8 through the reverse valve. Further, the reversing valves are also provided in parallel to the switching valves 3 and 4, and these reversing valves are operated when the antilock brake control is activated.
When the brake operation is loosened and the hydraulic pressure of the master cylinder 1 is reduced when the switching valve 4 is closed, the hydraulic fluid from the wheel cylinders 7 and 8 passes through these reverse valves to switch the switching valve 2 It is intended to flow to the side.

In the first embodiment configured as described above, during normal brake operation (state shown in FIG. 1), pressure is applied from the master cylinder 1 to the left rear wheel wheel cylinder 7 through the switching valve 2 and the switching valve 3. The liquid is supplied and the pressurized liquid is supplied from the master cylinder 1 to the right rear wheel wheel cylinder 8 through the switching valve 2 and the switching valve 4, and the wheels are braked.
At this time, the switching valves 5 and 6 are closed,
No pressure liquid is discharged from the left rear wheel wheel cylinder 7 and the right rear wheel wheel cylinder 8 to the reservoir 11. Therefore, since the piston 17 in the reservoir 11 is in the non-actuated position, the valve element 14a of the inflow control valve 14 is seated on the valve seat 14b, and the inflow control valve 14 is closed. The supply of pressurized liquid from the master cylinder 1 to the reservoir 11 is blocked. Further, since the hydraulic pump 10 is stopped and the hydraulic pressure in the hydraulic pump 10 side pipeline of the relief valve 9 and the hydraulic pressure in the master cylinder 1 side pipeline are the same, the relief valve 9 valve The child 9a is seated on the valve seat 9b, and the relief valve 9 is closed.

When the antilock brake is operated, the hydraulic pump 10 starts to operate at the same time as the operation starts, and
The controller excites the switching valves 3 and 4 to stop the supply of hydraulic fluid from the master cylinder 1 and the hydraulic pump 10 to the left rear wheel cylinder 7 and the right rear wheel cylinder 8. Also, the switching valve 5
The switching valve 6 is excited, and the pressure liquid is discharged from the left rear wheel wheel cylinder 7 and the right rear wheel wheel cylinder 8 to the liquid chamber 18 of the reservoir 11 (a reduced pressure state). Therefore, the hydraulic pressure in each wheel cylinder 7, 8 is reduced, and the locked state of the wheels is released. When the wheel lock state is released by such an operation, the switching valve 5 and the switching valve 6 are demagnetized by the controller, and the pressure liquid from the left rear wheel wheel cylinder 7 and the right rear wheel wheel cylinder 8 is stored in the liquid chamber of the reservoir 11. It is prevented from being discharged to 18 (holding state). Also,
The controller demagnetizes the switching valves 3 and 4,
The hydraulic fluid from the master cylinder 1 and the hydraulic fluid sucked and discharged from the reservoir 11 by the hydraulic pump 10 are supplied to the wheel cylinders 7 and 8 through the switching valves 3 and 4, respectively, and the fluid in the wheel cylinders 7 and 8 is then supplied. The pressure is increased (pressurized state). When the anti-lock brake is operated, the switching valves 3, 4, 5 and 6 are appropriately excited or demagnetized according to the locked / unlocked state of the wheels so that the left rear wheel wheel cylinder 7 and the right rear wheel wheel cylinder 8 can be operated. Since the hydraulic pressure in each is independently increased or decreased and the hydraulic pressure in the hydraulic valve 10 side of the relief valve 9 and the hydraulic pressure in the master cylinder 1 side hydraulic line are the same, the relief valve 9 is closed. When the antilock brake is activated, the switching valve 2 remains in the demagnetized state (open state). When the brake operation is loosened and the hydraulic pressure in the master cylinder 1 drops, the hydraulic fluid in the wheel cylinders 7 and 8 passes through the check valves provided in parallel with the switching valves 3 and 4 to the master cylinder 1. It is supposed to be returned.

The controller also causes the switching valve 2 to be in an excited state (closed state), the switching valve 3 and the switching valve 3 when the left and right rear wheels, which are driving wheels, tend to idle when the vehicle is driven (starting or accelerating). Traction control control is started with the switching valve 4 in the demagnetized state (open state) and the switching valves 5 and 6 in the demagnetized state (closed state). When the traction control control is started, the hydraulic pump 10 starts operating and sucks the hydraulic fluid from the liquid chamber 18 of the reservoir 11. The hydraulic fluid sucked from the liquid chamber 18 is discharged by the hydraulic pump 10,
It is supplied to the left rear wheel wheel cylinder 7 and the right rear wheel wheel cylinder 8 through the switching valve 3 and the switching valve 4, and suppresses idling of the left and right rear wheels. It should be noted that when the controller increases the hydraulic pressure in the left rear wheel wheel cylinder 7 and the right rear wheel wheel cylinder 8 and the hydraulic pressure is above a certain level, idling of the left and right rear wheels is being suppressed, and the switching valve 3 Also, the switching valve 4 is set in the excited state (closed state), and the switching valves 5 and 6 are set in the demagnetized state (closed state) to maintain the hydraulic pressure in each wheel cylinder 7, 8. Further, when it is determined that the idling is suppressed, the left rear wheel wheel cylinder 7 and the right rear wheel wheel are set by setting the switching valves 3 and 4 in the excited state (closed state) and the switching valves 5 and 6 in the excited state (open state). The hydraulic pressure in the cylinder 8 is reduced. At this time, all the switching valves 2, 3 and 4 are closed, so that the hydraulic pressure discharged from the hydraulic pump 10 causes the hydraulic pressure in the pipeline of the relief valve 9 on the hydraulic pump 10 side to change to the master cylinder. When the pressure becomes higher than the hydraulic pressure in the pipeline on the first side by a preset pressure or more, the valve element 9a of the relief valve 9 separates from the valve seat 9b, and the hydraulic pressure discharged from the hydraulic pump 10 becomes the hydraulic pressure in the relief valve 9. Flows from the pump 10 side to the master cylinder 1 side.

The inflow control valve 14 is in the inflow blocking state immediately before the traction control control is started, but if the traction control control is started and the hydraulic pump 10 is operated, the hydraulic pump 10 operates in the liquid chamber 18. Liquid is inhaled. As a result, the liquid pressure in the liquid chamber 18 becomes a negative pressure, and the piston 17 slides in the inner hole 16 in the direction of decreasing the volume of the liquid chamber 18 (upward in FIG. 1) from the inoperative position shown in FIG. , The pin 22 separates the valve element 14a from the valve seat 14b. As a result, the inflow control valve 14 shifts to the inflow permitted state. Therefore, when the working fluid in the liquid chamber 18 is insufficient, the working fluid is replenished from the master cylinder 1.

In the first embodiment, when the hydraulic fluid is discharged from the left rear wheel wheel cylinder 7 and the right rear wheel wheel cylinder 8 into the liquid chamber 18 during the operation of the anti-lock brake, the hydraulic pressure in the liquid chamber 18 is reduced. As a result, the piston 17 is pushed up by the hydraulic fluid and slides from the non-operating position shown in FIG. 1 in the direction of increasing the volume of the liquid chamber 18 (downward in FIG. 1). Piston 17
When slides in the inner hole 16 in the direction of increasing the volume of the liquid chamber 18,
Sealing member 1 fixed to the circumferential groove 17a of the piston 17
9 also slides together with the piston 17 while being pressed against the inner peripheral surface of the inner hole 16. First, the seal member 19 slides while making sliding contact with the large diameter portion 16a. Further, when the piston 17 slides in the inner hole 16 in the direction of increasing the volume of the liquid chamber 18, the seal member 19 slides while slidingly contacting the inclined portion 16b and the small diameter portion 16c. That is, as the piston 17 slides in the inner hole 16 in the direction of increasing the volume of the liquid chamber 18, the seal member 19 is pressed against the outer peripheral surface of the piston 17 and the inner peripheral surface of the inner hole 16 and elastically deforms. Is increased, the elastic deformation amount is maximized when the seal member 19 is in sliding contact with the small diameter portion 16c, and the pressure contact force between the seal member 19 and the inner hole 16 is maximized.
The force with which the seal member 19 presses the outer peripheral surface of the piston 17 and the inner peripheral surface of the inner hole 16 (hereinafter, this force is referred to as seal pressure) becomes maximum.

When the working fluid is continuously discharged from the left rear wheel wheel cylinder 7 and the right rear wheel wheel cylinder 8 into the liquid chamber 18, the piston 17 slides in the inner hole 16 in the direction of increasing the volume of the liquid chamber 18. When the retainer 21 contacts the lid 30, the piston 17 cannot slide in the direction of increasing the volume of the liquid chamber 18. When the piston 17 reaches a position where the piston 17 cannot slide in the direction of increasing the volume of the liquid chamber 18, the seal member 19 is in pressure contact with the small diameter portion 16c, and therefore the wheel cylinders 7 and 8 are further moved into the liquid chamber 18. Even if the working fluid is discharged and the hydraulic pressure in the fluid chamber 18 suddenly rises and a high pressure is applied, the sealing pressure of the seal member 19 is high, so that the sealing performance of the fluid chamber 18 is ensured. Liquid does not leak from the liquid chamber.

When the piston 17 is in a position where it cannot slide in the inner hole 16 in the direction of increasing the volume of the liquid chamber 18, the liquid chamber 18 is introduced from the left rear wheel wheel cylinder 7 and the right rear wheel wheel cylinder 8. When the discharge of the hydraulic fluid from the hydraulic pump 10 is stopped, the hydraulic fluid is continuously sucked from the hydraulic chamber 18 by the hydraulic pump 10 and the spring force of the spring 20 causes the piston 17 to move to the inner hole 16
The inside slides in the direction of decreasing the volume of the liquid chamber 18. Seal member 1
When 9 is in sliding contact with the small diameter portion 16c, the sealing member 19
The sliding resistance between the inner hole 16 and the inner hole 16 is large. At this time, since the compression amount of the spring 20 is large, the spring force of the spring 20 is large, which causes the piston 17 to slide relatively. It's easy to do.

In the first embodiment, when the traction control control starts to be started, the hydraulic pump 10
Since the working fluid in the liquid chamber 18 is sucked by the liquid chamber 18,
A negative pressure is generated inside the piston 17, and the piston 17 moves from the non-actuated position shown in FIG.
Slide in (upward). When the piston 17 slides in the inner hole 16 in the direction of decreasing the volume of the liquid chamber 18, the pin 22 engages with the valve 14a, the valve 14a separates from the valve seat 14b, and the inflow control valve 14 flows in. Allowed state. At this time, the seal member 19 also slides together with the piston 17, but since the seal member 19 is in sliding contact with the large diameter portion 16a of the inner hole 16, the seal pressure of the seal member 19 is low. Therefore, the sliding resistance between the seal member 19 and the inner hole 16 is small. That is, when the high pressure does not act in the liquid chamber 18 and the sealing pressure of the seal member 19 does not need to be increased, the sliding resistance between the seal member 19 and the inner hole 16 is reduced, so that the piston Since 17 is easily slid, the hydraulic fluid is efficiently sucked into the fluid chamber 18 by the hydraulic pump 10.

When the traction control control is stopped, the suction of the hydraulic fluid in the liquid chamber 18 by the hydraulic pump 10 is stopped and the piston 17 is pushed by the spring 14c, so that the piston 17 moves inside the inner hole 16 of the liquid chamber 18. Sliding in the direction of increasing volume. Then, when the piston 17 returns to the inoperative position, the valve element 14a is seated on the valve seat 14b, and the inflow control valve 14 is in the inflow blocking state. When the traction control control is stopped and the piston 17 slides in the inner hole 16 in the direction of increasing the volume of the liquid chamber 18, the seal member 1
Since the sliding resistance between the inner hole 16 and the inner hole 16 is small, the piston 17 can slide easily.

In the first embodiment, the inner hole 16, the large diameter portion 16a, the inclined diameter portion 16b and the small diameter portion 16c of the cylinder 15 correspond to the seal pressure varying means. The left rear wheel wheel cylinder 7 and the right rear wheel wheel cylinder 8 correspond to hydraulic fluid supply means.

A second embodiment of the present invention will be described with reference to FIG. FIG. 2 is a sectional view of the reservoir of the hydraulic control system according to the second embodiment of the present invention. In the second embodiment, the structure other than the reservoir is the same as that of the first embodiment, and the description thereof is omitted here. Further, the same components as those of the first embodiment are designated by the same reference numerals, and detailed description thereof will be omitted.

A piston 27 is slidably inserted in a cylindrical inner hole 26 having a bottom and formed in the cylinder 15. The outer diameter of the piston 27 is a large diameter portion 27a that is large on the bottom wall 15a side of the cylinder 15 in the axial direction of the inner hole 26,
The cylinder 15 has a small diameter portion 27c having a small diameter on the side opposite to the bottom wall 15a side, and an inclined portion having a diameter inclined in the axial direction of the inner hole 26 between the large diameter portion 27a and the small diameter portion 27c. 27b
And the bottom wall 15a of the cylinder 15 of the inclined portion 27b is formed.
The outer diameter of the side is the same as that of the large diameter portion 27a, and the outer diameter of the inclined portion 27b on the side opposite to the bottom wall 15a side of the cylinder 15 is the same as that of the small diameter portion 27c. A circumferential groove 26a is formed on the inner circumferential surface of the inner hole 26 in the circumferential direction of the inner hole 26, and an annular seal member (O-ring) made of an elastic body (rubber) is formed in the circumferential groove 26a. ) 29 is fixed. The seal member 29 is sized so as to come into pressure contact with the inner hole 26 and the outer peripheral surface of the piston 27, and when the piston 27 is in the non-actuated position shown in FIG. 2, the seal member 29 has the small diameter portion 27 c of the piston 27. Is in pressure contact with. Also, the inner hole 2
6 is formed with a stepped portion 26d, and the flange portion of the retainer 21 is in contact with the stepped portion 26d when the piston 27 is in the non-actuated position shown in FIG.

In the second embodiment, when the hydraulic fluid is discharged from the left rear wheel wheel cylinder 7 and the right rear wheel wheel cylinder 8 into the liquid chamber 18 during the operation of the antilock brake, the hydraulic pressure in the liquid chamber 18 is reduced. The piston 27 is pushed up by the hydraulic fluid, and slides in the direction in which the volume of the fluid chamber 18 increases from the non-actuated position shown in FIG. With the sliding of the piston 27, the seal member 29 has a small diameter portion 27c, an inclined portion 27b, and a large diameter portion 2
When the retainer 21 comes into contact with the lid 30 by pressure contact with 7a,
The piston 27 cannot slide in the direction of increasing the volume of the liquid chamber 18. When the piston 27 reaches a position where the piston 27 cannot slide in the direction of increasing the volume of the liquid chamber 18, the seal member 29 is in pressure contact with the large diameter portion 27a. Hydraulic fluid is discharged to the liquid chamber 18
Since the sealing pressure of the seal member 29 is high even if the hydraulic pressure in the inside suddenly rises to a high pressure, the sealing property of the liquid chamber 18 is ensured and the hydraulic fluid does not leak from the liquid chamber.

When the piston 27 is in a position where it cannot slide in the direction of increasing the volume of the liquid chamber 18, the hydraulic fluid is discharged from the left rear wheel wheel cylinder 7 and the right rear wheel wheel cylinder 8 into the liquid chamber 18. When stopped, the hydraulic pump 10 continuously sucks the hydraulic fluid from the inside of the liquid chamber 18 and the spring force of the spring 20 causes the piston 27 to move inside the inner hole 26.
Sliding in the direction of decreasing the volume. The seal member 29 has the large diameter portion 2
The sliding resistance between the seal member 29 and the inner hole 26 is large when it is in sliding contact with 7a, but at this time, since the compression amount of the spring 20 is large, the spring force of the spring 20 becomes large. Therefore, the piston 27 is relatively easy to slide.

In the second embodiment, when the traction control control starts to be started, the hydraulic pump 10
Since the working fluid in the liquid chamber 18 is sucked by the liquid chamber 18,
A negative pressure is generated inside, and the piston 27 slides in the inner hole 26 in the direction of decreasing the volume of the liquid chamber 18 from the non-actuated position shown in FIG. At this time, since the seal member 29 is in pressure contact with the small diameter portion 27c of the piston 27, the seal pressure of the seal member 29 is low, and the sliding resistance between the seal member 29 and the outer peripheral surface of the piston 27 is small. ing. That is, the liquid chamber 1
In the case where the high pressure does not act on the inside of 8 and the seal pressure of the seal member 29 does not need to be increased, the sliding resistance between the seal member 29 and the outer peripheral surface of the piston 27 is reduced,
The piston 27 is easy to slide, and the hydraulic pump 10
Thus, the suction of the hydraulic fluid in the liquid chamber 18 is efficiently performed.

In the second embodiment, the piston 27, the large diameter portion 27a, the inclined diameter portion 27b and the small diameter portion 27c correspond to the seal pressure varying means. The left rear wheel wheel cylinder 7 and the right rear wheel wheel cylinder 8 correspond to hydraulic fluid supply means.

In the above embodiment, when the piston slides in the inner hole in the direction of increasing the volume of the liquid chamber 18 by the spring 14c of the inflow control valve 14 when the traction control control is stopped, the sliding resistance of the seal member is The smaller size makes the piston easier to slide. Therefore, the spring force of the spring 14c can be reduced, and the inflow control valve 14 can be downsized.

Further, in the above embodiment, when the spring force of the spring 20 is large and does not act on the piston, the sliding resistance of the seal member is small, so that the piston is easy to slide and the hydraulic pressure is high. The hydraulic fluid can be sucked into the hydraulic chamber by the hydraulic pump without increasing the suction force of the pump. Therefore, a large negative pressure is generated in the liquid chamber due to the large suction force of the hydraulic pump, and it is possible to prevent vaporization of air, water, etc. contained in the hydraulic fluid.

In the above embodiment, the piston slides in the inner hole from the non-actuated position in the direction of decreasing the volume of the liquid chamber for traction control control, that is, in the region where the liquid chamber is substantially at atmospheric pressure. , It is necessary to suck the hydraulic fluid in the fluid chamber of the reservoir with a hydraulic pump, but in such an area, since the sealing pressure of the seal member is low, the suction efficiency of the hydraulic pump is good and traction is high. There is also an effect that control is performed with good response.

In the above embodiment, the annular seal member made of an elastic body was an O-ring made of rubber, but the seal member is not limited to this, and may be a resin, for example. It may be a D ring. Any annular member made of a material having elasticity may be used.

Further, in the above embodiment, the seal pressure of the seal member may be increased immediately after the piston starts sliding from the inoperative position in the inner hole in the direction of increasing the volume of the liquid chamber. Since the hydraulic pressure discharged from the wheel cylinder is relatively higher than the atmospheric pressure, the sealing pressure remains low even when the piston starts sliding from the inoperative position in the inner hole in the direction of increasing the volume of the liquid chamber. Then, the hydraulic fluid in the liquid chamber may leak. However, at the same time when the piston starts sliding from the inoperative position in the inner hole in the direction of increasing the volume of the liquid chamber,
By increasing the sealing pressure of the sealing member, it is possible to reliably prevent leakage of the hydraulic fluid in the liquid chamber.

Further, in the above embodiment, when the piston is in the non-actuated position, the volume of the liquid chamber is secured to some extent and the traction control control can be dealt with. However, the piston is in the non-actuated position. In this case, it is also applicable to a brake fluid pressure control device in which the volume of the fluid chamber becomes zero (that is, a brake fluid pressure control device capable of only antilock brake control).

In the above embodiment, the hydraulic pressure control device of the present invention is applied to the brake hydraulic pressure control device. However, the hydraulic pressure control device of the present invention is not limited to the brake hydraulic pressure control device. Applicable.

[0041]

According to the present invention, when the piston is in a position where it cannot slide in the cylinder bore in the direction of increasing the volume of the liquid chamber, the seal pressure varying means increases the pressure contact force of the seal member. . Therefore, more hydraulic fluid is supplied,
Even if the liquid pressure in the liquid chamber suddenly rises to a high pressure, the sealing property is ensured, and the hydraulic fluid does not leak from the liquid chamber. Further, in at least part of the case where the piston slides in the cylinder inner hole in the direction in which the volume of the liquid chamber decreases due to the suction of hydraulic fluid by the hydraulic pump, the pressure contact force with which the seal member is pressed against the piston and the cylinder is small. Therefore, the sliding resistance of the piston is reduced, and the efficiency of sucking the working fluid into the fluid chamber by the fluid pressure pump is improved.

[Brief description of drawings]

FIG. 1 is a hydraulic circuit diagram in which a hydraulic pressure control device according to a first embodiment of the present invention is applied to a brake hydraulic pressure control device.

FIG. 2 is a sectional view of a reservoir of a hydraulic control system according to a second embodiment of the present invention.

[Explanation of symbols]

1 ... master cylinder 7 ... left rear wheel wheel cylinder (working fluid supply means) 8 ... right rear wheel wheel cylinder (working fluid supply means) 10 ... hydraulic pressure Pump 11 ... Reservoir 15 ... Cylinder 16 ... Inner hole (sealing pressure varying means) 16a ... Large diameter portion (sealing pressure varying means) 16b ... Part (seal pressure varying means) 16c ... Small diameter part (sealing pressure varying means) 17 ... Piston 18 ... Liquid chamber 19 ... Seal member

Claims (1)

[Claims] 1. A piston, a cylinder having an inner hole into which the piston is slidably inserted, a liquid chamber formed between the inner hole of the cylinder and the piston, and an inner hole of the cylinder. A reservoir, which is fixed to either one of the outer peripheral surface of the piston, is in pressure contact with the inner hole of the cylinder and the outer peripheral surface of the piston, and includes a seal member that seals the liquid chamber, and a hydraulic fluid in the liquid chamber. A hydraulic pressure control device comprising a hydraulic fluid supply means for supplying the hydraulic fluid and a hydraulic pump for sucking the hydraulic fluid in the fluid chamber, wherein the piston moves in the inner hole of the cylinder in a direction in which the volume of the fluid chamber increases. The pressure contact force of the seal member in at least a part of the slidable region is set so that the piston cannot slide in the inner hole of the cylinder in the direction in which the volume of the liquid chamber increases. Pressure welding A fluid pressure control device comprising a seal pressure varying means for making the force smaller than the force.