JPH05213169A - Hydraulic control device of brake - Google Patents

Abstract

PURPOSE:To stabilize control characteristics and keep safer braking concerning a hydraulic control device of a brake to control hydraulic pressure of a rear wheel brake, so as to prevent lock of rear wheels earlier than that of front wheels at the time of braking for an automobile. CONSTITUTION:A hydraulic control mechanism provided with a plunger 16 in which hydraulic pressure works and a diaphragm 24 on which vacuum pressure and control pressure act are provided, in a brake hydraulic control device 1 which is provided between a master cylinder 2 and a wheel braking unit and controls hydraulic pressure on rear wheels by sensing deceleration of a car. It is so constituted that the control pressure to act on the diaphragm 24 is enclosed when it reaches the preset deceleration and the hydraulic pressure is controlled in reducing pressure by action of the enclosed control pressure.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brake fluid pressure control device for controlling a rear wheel brake fluid pressure in order to prevent a rear wheel from locking before a front wheel when a vehicle is braked.

[0002]

2. Description of the Related Art Generally, as a brake fluid pressure control device for a rear wheel to prevent the rear wheel from locking before the front wheel when the vehicle is braked, the vehicle is a predetermined one as disclosed in Japanese Patent Publication No. 61-11824. After detecting that the vehicle has reached the deceleration, a method is used in which the increase in the rear wheel hydraulic pressure is suppressed below the increase in the front wheel hydraulic pressure.

In this system, the brake fluid pressure from the master cylinder is applied to the control piston to increase the spring load that presses the fluid pressure control plunger, and when the predetermined deceleration is reached, the inertial body (steel ball) Close the liquid flow path to the control piston to stop the spring load from rising. The control plunger has an A surface on which the hydraulic pressure from the master cylinder acts and a B surface on which a rear wheel hydraulic pressure on a smaller area acts. Initially, the master cylinder side and the rear wheel side communicate with each other.
The same pressure acts on both sides of A and B, and the thrust generated in the plunger due to the area difference between both sides of A and B opposes the spring load. Therefore, before the ball closes the liquid flow path, the master cylinder pressure of The plunger does not move due to the increase in spring load accompanying the rise, and the master cylinder side and the rear wheel side communicate with each other as described above.

However, as described above, when the predetermined deceleration is reached, the liquid flow path is closed and the spring load stops increasing. Therefore, the plunger moves against the spring load due to the subsequent increase in hydraulic pressure on the master cylinder side. , The communication between the master cylinder side and the rear wheel side is cut off by closing the poppet valve,
After that, the increase in the master cylinder hydraulic pressure and the increase in the rear wheel side hydraulic pressure have a relationship of the area ratios of the A and B surfaces.

That is, the hydraulic pressure acting on the rear wheels is controlled to be lower than the master cylinder hydraulic pressure acting on the front wheels, and the rear wheels are prevented from locking earlier than the front wheels. You can prevent skidding.

[0006]

However, in such a conventional brake fluid pressure control device, there is a ball in the brake fluid that senses the vehicle deceleration and closes the fluid flow path. There is a problem that the operation speed is likely to be unstable, such that the movement speed of the ball is different due to the change of, and the fluid flow force exerts a different influence on the operation of the ball due to the speed of depression of the brake pedal.

The present invention has been made in view of such conventional problems, and an object thereof is to stabilize the control characteristics and to secure safer braking.

[0008]

In order to achieve the above object, the present invention is provided between a master cylinder and a wheel brake unit, and senses the deceleration of the vehicle to control the hydraulic pressure of the rear wheels. In a brake fluid pressure control device, a fluid pressure control mechanism having a plunger on which fluid pressure acts, and a diaphragm on which vacuum pressure and control pressure act, are provided, and control that acts on the diaphragm when a predetermined deceleration is reached. The pressure is contained, and the hydraulic pressure is controlled to be reduced by the action of the contained control pressure.

Further, the present invention is provided with an inertial body for closing the communication hole in order to contain the control pressure when a predetermined deceleration is reached.

[0010]

In the present invention, when the predetermined deceleration is reached,
The inertial body closes the communication hole to contain the control pressure acting on the diaphragm, and causes the contained control pressure to act on the hydraulic pressure control mechanism having the plunger. This sets the split point. When the hydraulic pressure from the master cylinder exceeds the split point, the hydraulic pressure control mechanism reduces the hydraulic pressure supplied to the rear wheel brake unit with a predetermined reducing ratio in accordance with the increase in hydraulic pressure. Prevent rear wheel lock.

As described above, since the communication hole is closed by the inertial body and the control pressure is made to act on the hydraulic pressure control mechanism, it is possible to solve the problem that the control characteristic is influenced by the ambient temperature. Can be stabilized.
As a result, safer braking can be ensured.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 4 are views showing an embodiment of the present invention.
The present embodiment is suitable for a brake system having a general vacuum booster. In FIG. 1, a brake fluid pressure control device 1 according to an embodiment is provided between a master cylinder 2 and a wheel brake unit, and is installed so as to be inclined with respect to a vehicle as shown (the front side of the vehicle is raised. ing).

When the driver operates the brake pedal 3,
The vacuum differential pressure acts on the diaphragm 5 of the vacuum booster (power booster) 4 to boost and press the master cylinder 2. The inside of the vacuum booster 4 is defined by a diaphragm 5 into a pressurizing chamber 6 and a negative pressure chamber 7, and a return spring 8 for returning the diaphragm 5 is interposed in the negative pressure chamber 7. Reference numeral 9 is a valve that operates by operating the brake pedal 3 and introduces the atmosphere into the pressurizing chamber 6.

The negative pressure chamber 7 is connected to a vacuum source via a negative pressure passage 10, and the check valve 1 is provided in the middle of the negative pressure passage 10.
1 is interposed. A vacuum pipe 12 is connected to the negative pressure chamber 7 and the vacuum source via a negative pressure path 10. The master cylinder 2 is connected to the brake fluid pressure control device 1 via a fluid pressure pipe 13 and supplies a fluid pressure (brake fluid pressure) to a fluid inlet 14A formed in a valve housing 14 of the brake fluid pressure control device 1.

A valve hole 15 communicating with the liquid inlet 14A is formed in the valve housing 14, and a plunger 16 is slidably accommodated in the valve hole 15. A poppet valve 17 is incorporated in the internal flow path of the plunger 16, and a valve seat 18 is fixed to the plunger 16 on the outlet side of the internal flow path. These constitute a hydraulic pressure control mechanism for controlling the hydraulic pressure supplied to the rear wheel brake unit.

Hydraulic pressure is supplied to the internal flow path of the plunger 16 from the master cylinder 2 through the hydraulic pipe 13.
It is guided from the liquid outlet 19 to the rear wheel brake unit through the internal flow path. That is, as shown in the figure, the poppet valve 17 is pressed by the valve spring 20, but initially the plunger 16 is pressed against the bottom of the valve hole 15 with a force stronger than the pressing force, so the poppet valve 17 is opened. Speaks.

In the opening 21 of the valve housing 13,
A cover 22 is provided, and an end portion of the cover 22 is overlapped with the cover 22 on the valve housing 13 so that the bolt 2
Negative pressure chamber 25 by diaphragm 24 fixed by 3
And the control pressure chamber 26 are respectively defined. Negative pressure chamber 25
Is communicated with the negative pressure chamber 7 of the vacuum booster 4 and the vacuum source via the negative pressure port 29, the vacuum pipe 12, and the negative pressure path 10.

The diaphragm 24 has plates 27 and 28.
The boss portion 30 is fixed via the boss portion 30, and the boss portion 30 is in contact with the plunger 16. A valve opening spring 31 is provided in the control pressure chamber 26. A ball housing 33 is fixed to the cover 22 with a bolt 34 via a rubber member 32, and an atmospheric chamber 36 for accommodating the ball 35 is formed in the ball housing 33. A vent pipe 37 is provided so as to project into the atmosphere chamber 36, and one end of the vent pipe 37 is inserted and fixed in the boss portion 30 through the control pressure chamber 26. Cover 2
A communication hole 38 is formed in the rubber member 32 and the rubber member 32, and the atmosphere chamber 36 and the control pressure chamber 26 communicate with each other through the communication hole 38. When the brake is not operated, the vacuum source (vacuum pressure (negative pressure) in the negative pressure chamber 7 acts on the atmosphere chamber 36 through the ventilation hole 39 and the ventilation pipe 37 formed in the boss portion 30,
Further, it acts on the control pressure chamber 26 via the communication hole 38.

Atmosphere inlet 40 is provided in ball housing 33.
And an air introduction valve 41 is provided at the air introduction port 40 via a valve spring 42. When the ventilation pipe 37 presses the atmosphere introducing valve 41 by the diaphragm 24, the atmosphere introducing valve 41 opens to introduce the atmosphere into the atmosphere chamber 36. The ball 35, which is an inertial body (steel material), is rotatably accommodated in the atmosphere chamber 36, and when the brake reaches a predetermined deceleration, the ball 39 closes the communication hole 38, and the ball 39 and the control pressure are controlled. The communication with the chamber 26 is cut off.

The plunger 16 and the valve housing 13 are sealed by an oil seal 43 and an O-ring 44. Next, the operation will be described. When the brake is not operated, the negative pressure chamber 25 of the valve housing 13 has the negative pressure port 2
9, the vacuum pipe 12, the negative pressure passage 10, and the check valve 11 communicate with the vacuum source, and the boss portion 3
A vacuum pressure (negative pressure) acts on the atmosphere chamber 36 and the control pressure chamber 26 via the ventilation hole 39 of 0 and the ventilation pipe 37.
Further, since the brake fluid pressure does not act on the plunger 16, the diaphragm 24 does not operate.

When the driver depresses the brake pedal 3, the brake fluid pressure is generated as described above, and the fluid pressure is sent to the wheel brake unit for the front wheels and also to the valve hole 15 of the brake fluid pressure control device 1. .. The hydraulic pressure sent to the brake hydraulic pressure control device 1 passes through the plunger 16 and is sent to the wheel brake unit of the rear wheel.

The hydraulic pressure acting on the plunger 16 is obtained by subtracting the A surface (area corresponding to the outer diameter of the O ring 44) and the B surface (area corresponding to the inner diameter of the seal ring 43 from the A surface) of the plunger 16. Area) and pushes down the plunger 16 to the lower right due to the area difference between the two surfaces. The pushing force of the plunger 16 due to hydraulic pressure is the valve opening spring 31.
Plunger 16 and diaphragm 2
When 4 moves to the lower right and the vent pipe 37 contacts the atmosphere introducing valve 41, the communication between the negative pressure chamber 25 and the control pressure chamber 26 is blocked, and when moving further to the lower right, the atmosphere introducing valve 41 opens (Fig. (See 2) Atmosphere is introduced into the atmosphere chamber 36, and is also introduced into the control pressure chamber 26 through the communication hole 38.

When the atmosphere is introduced into the control pressure chamber 26, a thrust force that pushes back the plunger 16 is generated in the diaphragm 24, and the diaphragm 24 moves when the thrust force and the liquid pressure pushing the plunger 16 to the lower right are balanced. It returns to the neutral position and the atmosphere introduction valve 41 is closed. That is, the ball 35
As long as the communication hole 38 does not close, the atmosphere introduction valve 41 is arranged so that the fluid pressure acting on the plunger 16 and the thrust acting on the diaphragm 24 are always balanced.
6. The pressure in the control pressure chamber 26 is adjusted, and the hydraulic pressure from the master cylinder 2 is sent to the wheel brake unit for the rear wheels.

In reality, when the brake fluid pressure rises by depressing the brake pedal 3, the brake works and deceleration occurs. Then, when the predetermined deceleration is reached, the ball 35 rolls due to inertia to block the communication hole 38. Therefore, between the two chambers 25 and 26 acting on the diaphragm 24.
Since the increase in the differential pressure between them stops, the increase in the thrust acting on the diaphragm 24 also stops. When the hydraulic pressure further rises, the plunger 16 overcomes the thrust acting on the diaphragm 24 and the tension of the valve opening spring 31 and moves to the lower right side, and the poppet valve 17 is closed. The hydraulic pressure sent to the master cylinder 2
The fluid pressure is independent of the discharge pressure from.

Here, since the communication hole 38 is closed and the thrust force acting on the diaphragm 24 becomes constant, the plunger 1
Due to the balance of the forces acting on 6, the poppet valve 17 is repeatedly opened and closed to exhibit the hydraulic characteristics as shown in FIG. In this way, the increase in the hydraulic pressure delivered to the rear wheel brake unit gradually increases with respect to the increase in the discharge pressure from the master cylinder 2 at the ratio of the area ratio of the A surface to the B surface, so that the rear wheel is moved ahead of the front wheel. You can prevent the wheels from locking.

That is, thereafter, by repeatedly opening and closing the poppet valve 17 by the reciprocating movement of the plunger 16 according to the increase of the hydraulic pressure, the hydraulic pressure is reduced at a predetermined reducing ratio, and the rear wheel lock immediately before the braking is stopped. Therefore, the braking stability of the vehicle can be secured. In addition, in FIG.
Indicates a split point at which the predetermined deceleration has been reached in full loading, and B indicates a split point at which the predetermined deceleration has been reached in light loading.

Thus, when the predetermined deceleration is reached, the control pressure acting on the diaphragm 24 is contained,
Since the contained control pressure is made to act on the plunger 16 having the poppet valve 17 built therein, it is possible to prevent the control characteristic from changing due to the ambient temperature, and it is possible to secure safer braking. In the present embodiment, the example in which the poppet valve 17 is provided in the plunger 16 is shown, but a so-called lip seal type in which a seal ring acting as a valve is provided instead of the O ring 44 on the outer periphery of the plunger 16. It goes without saying that the same applies in the case of.

FIG. 4 shows the relationship of strokes until the poppet valve 17 is closed. The stroke A of the poppet valve 17> the stroke B of the ventilation pipe 37.

[0029]

As described above, according to the present invention,
The problem that the control characteristics are influenced by the ambient temperature can be solved, stable brake fluid pressure control can be performed, and safety can be improved.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of the present invention.

FIG. 2 is a diagram showing an open state of an air introduction valve.

FIG. 3 is a graph showing the relationship between master cylinder discharge pressure and rear wheel brake pressure.

FIG. 4 is a diagram showing a relationship of strokes until the valve is closed.

[Explanation of symbols]

 1: Brake fluid pressure control device 2: Master cylinder 3: Brake pedal 4: Vacuum booster 5: Diaphragm 6: Pressurization chamber 7: Negative pressure chamber 8: Return spring 9: Valve 10: Negative pressure passage 11: Check valve 12: Vacuum pipe 13: Hydraulic pipe 14: Valve housing 14A: Liquid inlet 15: Valve hole 16: Plunger 17: Poppet valve 18: Valve seat 19: Liquid outlet 20: Valve spring 21: Opening 22: Cover 23: Bolt 24 : Diaphragm 25: Negative pressure chamber 26: Control pressure chamber 27, 28: Plate 29: Negative pressure port 30: Boss portion 31: Valve opening spring 32: Rubber member 33: Ball housing 34: Bolt 35: Ball 36: Atmosphere chamber 37 : Ventilation pipe 38: Communication hole 39: Ventilation hole 40: Atmosphere introduction port 41: Atmosphere introduction valve 42: Valve spring 43: Oil seal 44: O-ring

Claims (2)

[Claims] 1. A brake fluid pressure control device provided between a master cylinder and a wheel brake unit, which senses a deceleration of a vehicle to control fluid pressure of rear wheels, having a plunger on which fluid pressure acts. Hydraulic control mechanism,
A diaphragm on which a vacuum pressure and a control pressure act is provided, the control pressure acting on the diaphragm is confined when a predetermined deceleration is reached, and the hydraulic pressure is controlled to be reduced by the action of the confined control pressure. A characteristic brake fluid pressure control device. 2. The brake fluid pressure control device according to claim 1, further comprising an inertia body for closing the communication hole in order to contain the control pressure when a predetermined deceleration is reached.