JPH05254410A - Brake liquid pressure control device - Google Patents

Abstract

PURPOSE:To provide sufficient braking force and stabilize the control characteristic by obtaining the high sealing pressure in response to the load of a vehicle in a brake liquid pressure control device controlling the rear wheel brake liquid pressure. CONSTITUTION:A brake liquid pressure control device is provided with a liquid pressure control mechanism 23 having a plunger 19 applied with the liquid pressure, an A chamber 26 and a B chamber 27 partitioned by a main diaphragm 25 pressing the plunger 19, and an inertial body closing a cutoff valve 42 cutting off the introduction of the gas pressure proportional to the step-on force of a brake pedal 4 or the discharge pressure of a master cylinder 2 when the inertial force exceeds the force of a sensor spring 41 and the sensor diaphragm 28 by the deceleration of a vehicle.

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) Since the liquid flow path to the control piston is closed to contain the control pressure, the spring load stops increasing. In other words, the amount of brake fluid pressure required to reach a certain deceleration is determined by the load on the vehicle, so the greater the vehicle load, the greater the control pressure that can be contained. Therefore, the spring load also stops increasing with a large tension. become.

The control plunger has an A surface on which hydraulic pressure from the master cylinder acts and a B surface on which a smaller area of rear wheel hydraulic pressure acts. Initially, the master cylinder side and the rear wheel side communicate with each other. And the same pressure acts on both A and B,
Since the thrust force generated in the plunger due to the area difference between the two surfaces A and B opposes the spring load, the spring load increases as the master cylinder discharge pressure increases before the ball (inertia) closes the liquid flow path. Therefore, the plunger does not move, 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, so that the plunger cylinder moves against the spring tension due to the subsequent increase in master cylinder discharge pressure. , The communication between the master cylinder side and the rear wheel side is blocked by the action of the lip seal,
After that, the increase in the master cylinder discharge pressure and the increase in the rear wheel 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 discharge pressure acting on the front wheels, so that the rear wheels are prevented from being locked before the front wheels, and the rear wheels are early locked to prevent the vehicle from being locked. You can prevent skidding. The hydraulic pressure control characteristic is expressed in a graph as shown in FIG. 4, and it can be seen that as the vehicle load increases, the rear wheel hydraulic pressure becomes higher, and then the hydraulic pressure is controlled to be lower than the master cylinder discharge pressure.

That is, since the load of the vehicle is detected to control the rear wheel hydraulic pressure, it is generally called a load sensing valve.

[0008]

However, in such a conventional brake fluid pressure control device, a system for detecting the fact that a constant deceleration has been reached and closing the fluid flow path is used. It was difficult to obtain a large difference in the containment pressure depending on the magnitude of the load. Also, because the ball, which is an inertial body, moves in the brake fluid and closes the shutoff valve, it is easily affected by temperature and fluid flow, and the containment pressure itself has an error with respect to deceleration and load. There is also a problem that it is easy to get out, and there is a problem that it is difficult to obtain the containment pressure for controlling the rear wheel hydraulic pressure characteristics required by the vehicle.

That is, when the load on the vehicle is large, the rear wheel hydraulic pressure cannot be sufficiently controlled even if the rear wheel hydraulic pressure is controlled to a high value within a range where the rear wheel is not locked first. As a result, the load on the front wheel brakes increases, which causes a problem that the braking force becomes insufficient due to overheating of the front wheel brakes when the brakes are continuously used.

The present invention has been made in view of such conventional problems, and a sufficient braking force can be obtained and a control can be performed by obtaining a high containment pressure according to the load of the vehicle. An object of the present invention is to obtain a brake fluid pressure control device that can stabilize the characteristics.

[0011]

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 the brake fluid pressure control device, a fluid pressure control mechanism having a plunger on which fluid pressure acts, a chamber A and a chamber B defined by a main diaphragm that presses the plunger, and a chamber C defined by a sensor diaphragm.
When the inertial force exceeds the force of the sensor spring and the sensor diaphragm provided between the main chamber and the main chamber due to the deceleration of the vehicle, the force of the brake pedal or the master cylinder The inertial body that closes the shutoff valve that shuts off the introduction of the gas pressure proportional to the discharge pressure into the chamber A is provided.

Further, according to the present invention, a correction spring for correcting the thrust of the sensor diaphragm is provided between the sensor diaphragm and the inertial body. Further, according to the present invention, the main diaphragm and the sensor diaphragm are provided with a check valve that allows the gas to flow from the B chamber and the C chamber to the A chamber and shuts off the reverse.

[0013]

In the present invention, the vehicle is braked by the increase in the brake fluid pressure discharged to the front wheels and the rear wheels, the deceleration occurs, and the inertial force also acts on the inertial body. When the increase in deceleration exceeds the increase in introduced gas pressure and overcomes the force of the sensor diaphragm and the sensor spring, the inertial body moves toward the front of the vehicle and the shutoff valve closes. In this way, the pressure contained in the chamber A is applied to 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 at a predetermined reducing ratio in accordance with the increase in the hydraulic pressure, and controls it. Prevents rear wheel lock immediately before stopping. In the present invention, the deceleration when the inertial body closes the shutoff valve is substantially changed by the sensor diaphragm, so that a large difference in the containment pressure between the light load and the constant load can be obtained.

Therefore, the rear wheel hydraulic pressure can be controlled to a sufficiently high value in accordance with the change in the load such as the load amount.
Since it is possible to effectively use the rear wheel brakes while preventing the rear wheels from being locked early, it is possible to prevent the braking force from being reduced due to overheating of the front wheel brakes. Further, since the thrust of the sensor diaphragm is corrected by using the correction spring, the hydraulic pressure characteristic according to the change of the load can be obtained.

Further, since the shutoff valve is closed by the movement of the inertial body and the gas pressure is confined in the chamber A, the problem that the control characteristics are influenced by the ambient temperature can be solved and the control characteristics can be stabilized. You can As a result, safer braking can be ensured.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 3 are views showing an embodiment of the present invention.
It should be noted that this embodiment is applied to a brake system having a general vacuum booster. In FIG.
The brake fluid pressure control device 1 according to the embodiment is provided between the master cylinder 2 and the wheel brake unit (rear wheel brake unit) 3.

When the driver operates the brake pedal 4,
A vacuum differential pressure acts on the diaphragm 6 of the booster (vacuum booster) 5 to boost and press the master cylinder 2. The hydraulic pressure discharged from the master cylinder 2 is supplied to the front wheel brake unit and to the rear wheel brake unit 3 via the brake hydraulic pressure control device 1, respectively.

From the booster 5, the diaphragm 6
By taking out the vacuum pressure acting on, the gas pressure proportional to the master cylinder discharge pressure and the pedal effort can be obtained. That is, the diaphragm 6 of the booster 5
Both sides are a negative pressure chamber 7 and a pressurizing chamber 8, both of which are held at a negative pressure obtained from a vacuum source such as an engine intake pipe when not operating, but when the pedal 4 is depressed, the vacuum control valve 9 As a result, the atmosphere is introduced into the pressurizing chamber 8 and a differential pressure between the diaphragm 6 and the negative pressure chamber 7 acts, and at the same time, a force proportional to the differential pressure is transmitted to the pedal 4 by the reaction force mechanism 10.
Therefore, the vacuum pressure acting on the diaphragm 6 becomes a value proportional to the master cylinder discharge pressure and the pedal effort.

A return spring 11 for returning the diaphragm 6 is interposed in the negative pressure chamber 7, and the negative pressure chamber 7 is connected to a vacuum source via a negative pressure passage 12 and the negative pressure passage 1
A check valve 13 is provided in the middle of 2. A vacuum pipe 14 is connected to the pressurizing chamber 5. The master cylinder 2 is connected to the brake fluid pressure control device 1 via a fluid pressure pipe 15 to provide fluid pressure (brake fluid pressure).
Is supplied to the fluid inlet 17 formed in the valve housing 16 of the brake fluid pressure control device 1.

A valve hole 18 communicating with the liquid inlet 17 is formed in the valve housing 16, and a plunger 19 is slidably accommodated in the valve hole 18. A valve spring 20 is interposed between the valve housing 16 and the plunger 19 and simply pushes the plunger 19 to the left. Further, between the valve housing 16 and the plunger 19, a lip seal 21 that opens and closes the internal flow path by the movement of the plunger 19 is provided. 22
Is a cup seal for sealing the brake fluid. With these components, a hydraulic pressure control mechanism 23 for controlling the hydraulic pressure supplied to the rear wheel brake unit 3 is reduced.

A cover 24 constituting a case is fixed to the valve housing 16, and inside the cover 24, a main diaphragm 25 defines an A chamber 26 and a B chamber 27, and a sensor diaphragm 28 defines a C chamber 29. Is made. A boss portion 32 is fixed to the main diaphragm 25 via plates 30 and 31.
Presses a lever 33 fixed to the end of the plunger 19. The end of the lever 33 is fixed to the cover 24 by a pin 34.

Reference numeral 35 denotes a weight (inertial body) which is swingably supported in the A chamber 26 by a pin 36 via a holding member 37. The weight 35 is connected to the sensor diaphragm 28 via a correction spring 38. A sensor spring 41 is provided between the weight 35 and the main diaphragm 25 via a pin 39 and a retainer 40. That is, the weight 35 presses the tension of the sensor spring 41 toward the rear of the vehicle by the force of the sensor diaphragm 28, and opens the shutoff valve 42. The shut-off valve 42 is the introduction part 4 of the vacuum pipe 14 connected to the pressurizing chamber 8.
It is provided in the inside of 3 through the check spring 44, and receives tension in the closing direction by the check spring 44, but is normally opened by being pressed by the weight 35. Therefore, the atmospheric pressure V1 of the pressurizing chamber 8 or the atmospheric pressure V0 of the same pressure as the atmospheric pressure V0 of the negative pressure chamber 7 is introduced into the A chamber 26.

Check valves 45 and 46 are provided on the main diaphragm 25 and the sensor diaphragm 28, respectively, so that gas can flow out from the B chamber 27 and the C chamber 29 to the A chamber 26, but the opposite is blocked. .. When the vehicle is braked, deceleration occurs, and the inertia force also acts on the weight 35 to overcome the forces of the sensor diaphragm 28 and the sensor spring 41, the weight 35 swings forward of the vehicle and the shutoff valve 42 opens the check spring. It is designed to be closed by the tension of 44.

Next, the operation will be described. When not in operation, the air pressure V1 of the pressurizing chamber 8 of the booster 5 is the same as that of the negative pressure chamber 7 as described above, and the pressurizing chamber 8 and the vacuum pipe 1 are
The A chamber 26, the B chamber 27, and the C chamber 29, which are communicated with each other through 4, are at the same atmospheric pressure as V0. That is, the same atmospheric pressure V0 as the negative pressure chamber 7 is applied from the vacuum pipe 14 to the weight 35.
Is introduced into the A chamber 26 via the shut-off valve 42 opened by the above, and is introduced into the B chamber 27 and the C chamber 29 via the check valves 45 and 46.

When the brake pedal 4 is stepped on, the pressurizing chamber 8 becomes an atmospheric pressure V1 proportional to the brake fluid pressure as described above.
V1 is introduced into chamber 26. However, B room 27 and C room 2
9 and 9, the check valves 45 and 46 act to maintain the atmospheric pressure V0 without increasing the atmospheric pressure. Therefore, a differential pressure between V1 and V0 acts on the sensor diaphragm 28, and the weight 35 is pulled rearward of the vehicle together with the sensor spring 41 via the correction spring 38.

On the other hand, the differential pressure between V1 and V0 similarly acts on the main diaphragm 25, and presses the plunger 19 via the lever 33. The plunger 19 pushes the main diaphragm 25 and the valve spring 20.
Since the lip seal 21 is in the communicating state by being pressed to the left side by the pressing force of, the discharge pressure of the master cylinder 2 is directly discharged to the rear wheel brake unit 3 as the rear wheel hydraulic pressure.

The vehicle is braked by the increase in the brake fluid pressure discharged to the front wheels and the rear wheels, deceleration occurs, and the inertia force acts on the weight 35 as well to oppose the force of the sensor diaphragm 28 and the sensor spring 41. When the increase in deceleration exceeds the increase in V1 to overcome the force of the sensor diaphragm 28 and the sensor spring 41, the weight 3
5 moves to the front (left side) of the vehicle, and the shutoff valve 42 is closed by the tension of the check spring 44.

Therefore, the atmospheric pressure in the chamber A 26 is separated from V1 to V2 and stops rising. Therefore, the force of the main diaphragm 25 pushing the plunger 19 also stops increasing, and the increase in hydraulic pressure overcomes them, and the plunger 19 moves to the right. Then, the lip seal 21 closes and the discharge pressure P2 to the rear wheel is After separating from the discharge pressure P1 of the master cylinder 2, the pressure rises a little lower than the rise of P1.

Here, the weight 25 overcomes the forces of the sensor diaphragm 28 and the sensor spring 41,
The relationship between V1 (= P1) and (deceleration-V1) when moving to the left is as shown in FIG. 2 (a). That is, in the conventional method, as shown in FIG. 2B, only the deceleration is detected and the shutoff valve is closed at a constant deceleration, so that the light loading and the constant loading of the containment pressure acting on the control piston are performed. However, in the embodiment, since the deceleration when the weight 35 moves is substantially changed by the sensor diaphragm 28, the difference between the light loading of the containment pressure (V2) and the constant loading is obtained. Can be taken large.

That is, as shown in FIG. 2B, in the prior art, the difference between the light loading and the constant loading was obtained only by the amount indicated by B, whereas in the present embodiment, the difference between FIG. As shown in a), the difference between the light loading and the constant loading is obtained by A. Therefore, the rear wheel hydraulic pressure P2 can be controlled to a sufficiently high value in accordance with changes in the load such as the load, so that the rear wheel brake can be effectively used while preventing the rear wheel from being locked early. It is possible to prevent a decrease in braking force due to the above.

Further, as described above, the force proportional to V1 is subtracted from the deceleration to obtain the sensor spring 4
The feature is to detect the point that overcomes 1. However, if the "simple force proportional to V1" is simply subtracted, there will be a change in load during partial load (intermediate load between light load and constant load). Since the change in the hydraulic pressure characteristic may not correspond subtly in some cases, the correction spring 38 acts to correct it.

That is, it is necessary to change the value subtracted from the deceleration as shown in FIG. That is, paying attention to the fact that the effective area of the sensor diaphragm 28 changes depending on the position of the sensor diaphragm 28,
Is set to decrease the effective area of the sensor diaphragm 28 by reducing the correction spring 38 and moving the sensor diaphragm 28 to the right side.

That is, as shown by C in FIG. 3, the sensor diaphragm 2 is made to approach a constant value when V1 becomes large as compared with the case where it is simply proportional to V1 (D).
The thrust force of No. 8 is set by using the correction spring 38. As a result, in the case of partial load, fluid pressure characteristics corresponding to changes in load can be obtained. Further, since the shutoff valve 42 is closed by using the weight 35 so that the atmospheric pressure V2 is confined in the chamber A 26, the problem that the control characteristic is influenced by the ambient temperature can be solved, and the control characteristic is stabilized. can do. As a result, safer braking can be ensured.

In this way, the brake fluid pressure characteristics of the rear wheels required by the vehicle can be obtained. Although the weight 35 is arranged in the A chamber 26 in this embodiment, it may be arranged in a place other than the A chamber 26, and the sensor spring 41 may be arranged between the case and the weight 35.

Further, in the present embodiment, an example in which a vacuum type booster is used is explained, but the point is that the gas pressure proportional to the discharge pressure of the master cylinder 2 or the brake pedal depression force,
Since it is to detect the point at which the shutoff valve 42 is closed in combination with deceleration, it can be applied to a brake system using compressed air.

[0037]

As described above, according to the present invention, since the rear wheel hydraulic pressure can be controlled to a sufficiently high value in accordance with the change in the load, it is possible to prevent the rear wheel from being locked early.
It is possible to effectively utilize the rear wheel brakes and prevent a reduction in braking force due to overheating of the front wheel brakes.

Further, due to the action of the correction spring, it is possible to obtain the hydraulic characteristic corresponding to the change of the load. Also,
The control characteristics can be stabilized, and safer braking can be secured.

[Brief description of drawings]

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

FIG. 2 is an explanatory view of the operation of a conventional example and the present invention.

FIG. 3 is a graph showing the relationship between gas pressure and sensor diaphragm thrust.

FIG. 4 is a graph showing the relationship between master cylinder discharge pressure and rear wheel hydraulic pressure.

[Explanation of symbols]

 1: Brake hydraulic pressure control device 2: Master cylinder 3: Rear wheel brake unit 4: Pedal 5: Booster device (vacuum booster) 6: Diaphragm 7: Negative pressure chamber 8: Pressurization chamber 9: Vacuum control valve 10: Anti Force mechanism 11: Return spring 12: Negative pressure line 13: Check valve 14: Vacuum pipe 15: Hydraulic pipe 16: Valve housing 17: Liquid inlet 18: Valve hole 19: Plunger 20: Valve spring 21: Lip seal 22: Cup seal 23: Fluid pressure control mechanism 24: Cover 25: Main diaphragm 26: A chamber 27: B chamber 28: Sensor diaphragm 29: C chamber 30, 31: Plate 32: Boss part 33: Lever 34: Pin 35: Weight ( Inertia) 36: Pin 37: Holding member 38: Correction spring 39: Pin 40: retainer 41: sensor spring 42: shutoff valve 43: introduction part 44: check spring 45, 46: check valve

Claims (3)

[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,
Chambers A and B defined by a main diaphragm that presses the plunger, a chamber C defined by a sensor diaphragm, and an inertial force that is swingably provided on the case due to the deceleration of the vehicle. An inertial body that closes the shutoff valve that shuts off the introduction of gas pressure proportional to the pedaling force of the brake pedal or the discharge pressure of the master cylinder into the chamber A when the force of the sensor spring provided between the main diaphragm and the sensor diaphragm is exceeded. A brake fluid pressure control device characterized by being provided. 2. The brake fluid pressure control device according to claim 1, further comprising a correction spring provided between the sensor diaphragm and the inertial body for correcting thrust of the sensor diaphragm. 3. The main diaphragm and the sensor diaphragm are provided with a check valve for allowing the outflow of gas from the chamber B and the chamber C to the chamber A and blocking the reverse thereof. And 2 brake fluid pressure control device.