JPH0764253B2 - Brake fluid pressure adjustment valve - Google Patents

Description

TECHNICAL FIELD The present invention relates to a brake fluid pressure adjusting valve provided in a brake device of an automobile or the like.

(Prior Art) When a vehicle is braked, an inertial force acts on the vehicle body, so that the center of gravity moves to the front and more load is applied to the front wheels than to the rear wheels. Therefore, if the same braking force is applied to the front wheels and the rear wheels, the rear wheels may be braked first and the lock may occur. Therefore, there is one in which a brake fluid pressure adjusting valve is provided in the brake system on the rear wheel side to prevent the rear wheel from locking by controlling the fluid pressure supplied to the wheel cylinder of the rear wheel.

Conventionally, as this brake fluid pressure adjusting valve, for example, Japanese Patent Laid-Open No.
There was one disclosed in Japanese Patent Laid-Open No. 59-102649.

As shown in FIG. 7, this is a housing 5 including a main cylinder connecting portion 1 and an inlet chamber 2 connected to the main cylinder connecting portion 1, a wheel cylinder connecting portion 3 and an outlet chamber 4 connected to the wheel cylinder connecting portion 3, respectively. A piston 7 provided between the inlet chamber 2 and the outlet chamber 3 and having a passage 6 communicating these two chambers, and between the inlet chamber 2 and the outlet chamber 4 when the deceleration force of the vehicle exceeds a certain value. A valve member 8 that is moved to a closed position that obstructs communication, and a wheel cylinder connecting portion 3 that is provided in the outlet chamber 4 and is open when the hydraulic pressure from a master cylinder (not shown) is small, and sudden braking is performed. In operation, the throttle member 9 is configured to move to a position where the wheel cylinder connecting portion 3 is partially covered by the flowing brake fluid.

With this configuration, when the hydraulic pressure from the master cylinder is small, the brake fluid flows from the main cylinder connecting portion 1 into the inlet chamber 2 at an appropriate speed, and then flows into the outlet chamber 4 through the passage 6 of the piston 7. . Since the brake fluid at this time is not so fast, only a weak impact is given to the throttle member 9, and the throttle member 9 does not move so as to cover the wheel cylinder connecting portion 3.

When the vehicle reaches a certain deceleration, the valve member 8 moves to block the passage 6 of the piston 7 and the communication between the inlet chamber 2 and the outlet chamber 4 is cut off. Then, when the pressure in the inlet chamber 2 rises, the piston 6 is released according to the difference in the pressure receiving area of the piston 6.
Moves forward and the brake fluid in the outlet chamber 4 flows to the wheel cylinder. When the pressure in the inlet chamber 2 further increases, the piston 7 advances to a position where it does not contact the valve member 8, the passage 6 is opened, and the brake fluid flows into the outlet chamber 4 again.

At this time, or suddenly, the brake pedal (not shown)
When the brake pedal is strongly depressed, the brake fluid flows into the outlet chamber 4 from the passage 6 at an extremely high speed, but since the throttle member 9 moves so as to close the wheel cylinder connecting portion 3, the protrusion of the throttle member 9 The brake fluid only flows from the gap created by the portion 9a, and the pressure in the wheel cylinder is prevented from rising rapidly.

In this way, the optimum hydraulic pressure adjustment of the rear wheel brake is performed.

(Problems to be Solved by the Invention) However, the conventional hydraulic pressure regulating valve described above has the following problems.

Before the operation, the throttle member 9 is arranged in the outlet chamber 4 in a tilted state, so that the brake fluid suddenly flows into the outlet chamber 4 from the passage 6 of the piston 7, and the throttle member 9 blocks the wheel cylinder connecting portion 3. When moving,
With the throttle member 9, the brake fluid on the front side of the throttle member 9 is pushed into the wheel cylinder, or the brake fluid flows in before the wheel cylinder connecting portion 3 is closed, so that the pressure of the wheel cylinder is increased. There was fear.

Furthermore, since the piston moves due to the difference in pressure receiving area between the inlet chamber 2 side and the outlet chamber 4 side, even if the brake pedal is released, it gradually returns in response to the decrease in hydraulic pressure. Therefore, when the brake pedal is depressed immediately after the release, the gap between the valve member 8 and the piston 7 varies, the control timing of the hydraulic pressure is not constant, and the performance becomes unstable.

The present invention has been made in view of the above problems, and an object thereof is to reliably prevent a sudden pressure increase from being transmitted to a wheel cylinder and to adjust the brake fluid pressure with stable performance. To provide a valve.

(Means for Solving Problems) As means for solving the above problems and achieving the object, a wheel cylinder connecting portion is formed at a front end portion of a housing and a master cylinder connecting portion is formed at a rear end portion of the housing. A piston provided to be slidable in the housing defines an outlet chamber communicating with the wheel cylinder connecting portion and an inlet chamber communicating with the master cylinder connecting portion, and the inlet chamber of the piston is defined. The side has a small diameter and the outlet chamber side has a large diameter, and a communication hole that communicates the inlet chamber and the outlet chamber is formed in the piston, and the communication hole is closed in the inlet chamber according to the deceleration of the vehicle. In a brake fluid pressure adjusting valve provided with a valve member movable to a position, a disc member made of a thin plate is provided in the outlet chamber, and a spring member is interposed between the disc member and the large diameter portion of the piston. Put on,
The disc member is biased toward the front end portion of the housing, the piston is biased toward the inlet chamber side, and a liquid passage is formed between the disc member and the front end portion of the housing.

(Operation) With this configuration, even if the brake fluid suddenly flows into the outlet chamber from the communication hole of the piston and the pressure in the outlet chamber rises rapidly, the disc member is attached to the rear end side of the housing by the spring member. Since the disk member partially closes the wheel cylinder connecting portion because it is biased, the hydraulic pressure is transmitted to the wheel cylinder only by the liquid passage formed between the disk member and the front end portion of the housing. for that reason,
No large pressure is transmitted to the wheel cylinder. Also, even if the pressure is extremely large, since the disk member is made of a thin plate, the outer peripheral part bends to the front end side and narrows the liquid path due to the pressure, so that the pressure of the wheel cylinder is surely increased. Can be prevented.

Also, when the brake pedal is released, the piston is pressed toward the inlet chamber side by the spring member and surely returns to the initial position, so that stable performance is exhibited even if the brake pedal is immediately depressed.

(Example) Next, the Example of this invention is described based on drawing.

First, referring to FIGS. 1 and 2, the brake fluid pressure adjusting valve of the present invention is shown.
The configuration of 10 will be described. A cap 13 having a master cylinder connecting portion 12 is screwed and attached to a rear end side opening of a cylindrical housing 11 having a closed front end portion. A wheel cylinder connecting portion 14 is formed on the front end portion 11a of the housing 11.

The inside of the housing 11 is a stepped bore 11b,
The bore 11b has a small diameter on the front side and a large diameter on the rear side.
A guide member 15 is fitted in the bore 11b, and the guide member 15 is positioned by the step portion 11c of the housing 11 and the front end surface 13a of the cap 13.

A bore 15a on which the small diameter portion 16a of the piston 16 slides is formed in the front portion of the guide member 15. The piston 16 has a large diameter portion 16b on the front side, and the large diameter portion 16b is brought into sliding contact with the bore 11b of the housing 11. The interior of the housing 11 is defined by the piston 16 into a rear inlet chamber 17 and a front outlet chamber 18, the inlet chamber 17 being a master cylinder connecting portion 12 and the outlet chamber 18 being a wheel cylinder connecting portion 14. They are in communication with each other. Further, the piston 16 is provided with a communication hole 19 which communicates the inlet chamber 17 and the outlet chamber 18, and a seal member 20 is attached to the inlet hole 17 side of the communication hole 19. Reference numeral 21 is an O-ring for maintaining liquid tightness.

A spherical valve member 22 is provided in the inlet chamber 17 so as to be movable back and forth, and a plate member 23 for restricting a return position of the valve member 22 is provided between the valve member 22 and the cap 13. ing. Further, the valve member 22 can be seated on the seal member 20 of the piston 16 and block the communication hole 19 of the piston 16 when moving forward. Further, when the piston 16 moves forward to the maximum, the valve member 22 comes into contact with the shoulder portion 15b of the guide member 15 and cannot move further, and is separated from the piston 16 to open the communication hole 19. Will be done.

Next, the disk member 24 and the coil spring 25, which is a spring member, which are essential parts of the present invention, will be described.

A disk member 24 made of a thin plate is provided in the outlet chamber 18, and a coil spring 25 is interposed between the counterbore portion 16c formed on the front end surface of the piston 16 and the disk member 24. As a result, the disc member 24 is urged toward the front end portion 11a of the housing 11 and the piston 16 is urged toward the inlet chamber 17 side.

Further, as shown in FIGS. 2 (a) and 2 (b), the disk member 24 has a plurality of protrusions 24a arranged on the surface thereof, so that the housing 1
A gap is formed between the front end portion 11a of 1 and this gap serves as a liquid path 26. Therefore, only through this liquid path 26 the outlet chamber
18 and the wheel cylinder connecting portion 14 are communicated with each other. In addition, without providing the protrusion 24a on the disk member 24 side, the housing 1
The liquid passage 26 may be formed by providing a protrusion on the front end portion 11a side of 1.

The operation of the above configuration will be described with reference to FIGS. 3 to 6.

First, the brake fluid pressure adjusting valve 10 having the above-described configuration is attached to a vehicle with the rear side lowered by θ °. Therefore, as shown in FIG.
Is in contact with the plate member 23 at the rear of the.

Here, when a brake pedal (not shown) is depressed and hydraulic pressure is supplied from a master cylinder (not shown), the valve member 22 does not move until a certain deceleration is reached. A certain clearance is secured between the hydraulic pressure and the inlet chamber 17, the communication hole 19 of the piston 16, the outlet chamber 18, the liquid passage 26 between the disc member 24 and the rear end 11a, and the wheel. It is sent to a wheel cylinder (not shown) through the cylinder connecting portion 14. The braking force of the front wheels and the rear wheels in this state increases in proportion to the master cylinder hydraulic pressure.

The characteristics at this time are A ₁ (when empty) or A ₂ (when loaded) shown in the performance diagram of FIG. Incidentally, characteristic curves, the master cylinder pressure on the horizontal axis P _M (front-wheel brake fluid pressure P _F) is Yes taken, the vertical axis Yes taken is rear wheel brake fluid pressure P _R, reference numeral I ₁ is unladen I ₂ shows the ideal distribution curve at the time of loading, and I ₂ shows the ideal distribution curve at the time of loading.

Next, when the master cylinder hydraulic pressure increases and the vehicle deceleration increases, as shown in FIG.
Due to inertia, it rolls to the piston 16 side, sits on the seal member 20, and closes the communication hole 19. Therefore, hydraulic pressure is not supplied to the wheel cylinder, and the wheel cylinder is kept at a constant hydraulic pressure. Further, even if hydraulic pressure is supplied from the master cylinder and the pressure in the inlet chamber 17 rises, the piston 16 does not move to a certain value due to the difference in the pressure receiving area of the piston 16 and the biasing force of the coil spring 25. That is, the area of the large diameter side of the piston 16 is A, and the area of the smaller diameter side and B, hydraulically P _a wheel cylinder side, when the master cylinder hydraulic pressure and P _b, A> is for a B , P _a × A + W = P _b × B, the piston 16 will not move unless P _b rises. Note that W is the urging force of the coil spring 25.

The characteristic at this time is B ₁ (when empty) or B ₂ (when loaded) shown in the performance diagram of FIG.

Thus, in this state, the braking force of the rear wheels does not increase even if the braking force of the front wheels increases.

Next, the master cylinder hydraulic pressure rises and the inlet chamber 17
The pressure of the inner rises and P _b satisfies the above equation, the piston 16 is advanced. Along with this movement, the brake fluid in the outlet chamber 18 flows to the wheel cylinder, increasing the fluid pressure in the wheel cylinder. From the pressure relationship above formula in this _{case, P a = B / A ×} Pb-W / A , and the fluid pressure of the wheel cylinder rises at a rate of increase of the B / A of the hydraulic pressure of the master cylinder. The characteristic at this time is C shown in the performance diagram of FIG. 6, and is the same when the vehicle is empty and when it is loaded.

In this way, the brake fluid pressure adjusting valve can supply an appropriate fluid pressure to the wheel cylinders, so that a stable braking force can be obtained.

Here, when the master cylinder hydraulic pressure sharply rises due to sudden braking or the like, the brake fluid flows from the inlet chamber 17 through the communication hole 19 into the outlet chamber 18, causing the hydraulic pressure in the outlet chamber 18 to rise sharply. Since the wheel cylinder connecting portion 14 is closed by the disk member 24, the hydraulic pressure is supplied to the wheel cylinder only from the hydraulic passage 26, and the hydraulic pressure in the wheel cylinder does not suddenly rise. Further, even in the case of a very large pressure increase, the outer circumference of the disk member 24 bends and the liquid passage 26 is further narrowed, so that the liquid pressure increase of the wheel cylinder can be reliably prevented.

When the brake is released, the coil spring 25
As a result, the piston 16 returns to the initial position, so that the performance will not become unstable even if the brake operation is continued.

(Effects of the Invention) As described in detail above, in the brake fluid pressure regulating valve according to the present invention, even if the fluid pressure in the outlet chamber rises sharply, the disc member ensures reliable transmission to the wheel cylinders of the rear wheels. Therefore, it is possible to prevent the rear wheels from locking, and further, when the brake is released, the spring member returns the piston to the initial position, so that stable braking performance can be obtained.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view of a brake fluid pressure regulating valve which is an embodiment of the present invention, and FIGS. 2 (a) and 2 (b) show a disc member of the brake fluid pressure regulating valve shown in FIG. 2 (a) is a front view thereof, FIG. 2 (b) is a sectional view taken along line II-II of FIG. 2 (a), FIG. 3, FIG. 4 and FIG. 6 is a longitudinal sectional view showing an operating state of the brake fluid pressure adjusting valve shown in FIG. 6, and FIG. 6 is a relationship between the master cylinder fluid pressure and the rear wheel brake fluid pressure when the brake fluid pressure adjusting valve shown in FIG. 1 is activated. FIG. 7 is a vertical sectional view of a conventional brake fluid pressure adjusting valve. 11 …… Housing 12 …… Master cylinder connection 14 …… Wheel cylinder connection 16 …… Piston 17 …… Inlet chamber 18 …… Outlet chamber 19 …… Communication hole 22 …… Valve member 24 …… Disk member 25 …… Coil spring (spring member)

Claims (1)

[Claims] 1. A wheel cylinder connecting portion is formed at a front end portion of a housing, a master cylinder connecting portion is formed at a rear end portion of the housing, and the wheel cylinder connecting portion is formed by a piston slidably provided in the housing. And an inlet chamber communicating with the master cylinder connecting portion, the inlet chamber side of the piston having a small diameter and the outlet chamber side having a large diameter, and the piston having the inlet chamber A brake fluid pressure adjusting valve, comprising: a communication hole that communicates with an outlet chamber; and a valve member that is movable in the inlet chamber to a position that closes the communication hole according to the deceleration of the vehicle. , A thin disk member is provided, and a spring member is interposed between the disk member and the large diameter portion of the piston to urge the disk member toward the front end side of the housing, and A brake fluid pressure adjusting valve characterized in that a fluid passage is formed between the disc member and the front end portion of the housing while urging toward the inlet chamber.