JPH07277165A - Load responsive type brake fluid pressure control device - Google Patents

Abstract

PURPOSE:To prevent the operation error of the fail safe structure even in the case where the fluctuation of hydraulic pressure such as ABS is input to a pressure chamber communicated with a pipeline of a front brake system by arranging a fixed throttle check valve in a branch pipeline communicated with the pipeline. CONSTITUTION:An input passage 8 and an output passage 9 of a proportioning valve A, which is interposed in a rear brake system, are communicated by a bypass passage 17. A piston 15 is energized by the pressure led from a pipeline of a front brake system into a pressure chamber 21 through a branch pipeline so that a bypass passage 17 is closed by a seal member 18. On the other hand, when dissipation of the pressure is generated in the front brake system, the bypass pipeline 17 is opened, and the pressure from a master cylinder is transmitted to a rear wheel cylinder, bypassing the proportional valve A. In this device, a fixed throttle check valve 34 is arranged on the way of the branch pipeline.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a load-responsive braking hydraulic pressure control device, and more particularly to a load-responsive braking hydraulic pressure control device having a structure for releasing hydraulic control on the rear wheel cylinder side when the front brake system is defective. The present invention relates to a control device.

[0002]

2. Description of the Related Art Conventionally, a brake system of an automobile has been provided with a load-responsive braking hydraulic pressure control device for reducing an output hydraulic pressure of a master cylinder at a predetermined rate in accordance with a loaded load. The control device is arranged in the middle of the hydraulic passage from the brake master cylinder to the rear wheel cylinder. Therefore, the hydraulic control device applies a braking force equal to that on the front wheel cylinder side to the rear wheel cylinder side at the time of low braking force at the initial stage of control, and when the braking force becomes equal to or more than a predetermined value, the hydraulic pressure control device causes the braking force to be higher than that on the front wheel cylinder side. A small braking force is applied to the rear wheel cylinder side to prevent the rear wheel from being locked and to obtain stable braking. Also, in vehicles such as trucks, the amount of braking force that causes rear wheel locking varies depending on the size of the loading load.Therefore, when the loading load is high, the hydraulic pressure at which the braking force on the rear wheel cylinder side begins to decrease Is large and small when it is small.

Further, in such a braking system,
When the front brake system fails, in order to obtain reliable braking only with the normal rear brake system, the bypass passage is opened and the pressure from the master cylinder is transmitted directly to the rear wheel cylinder, bypassing the proportioning valve. Some are equipped with a bypass mechanism.

More specifically, as shown in FIG. 9, the hydraulic control device has a housing 1 fixed to the vehicle body side, and a base end of a load detection lever 3 is fixed to one end of the housing 1. The detection lever 3 is connected to the vertically movable stem 2, and the tip of the detection lever 3 has a tension spring 4
Is connected to an axle side bracket (not shown) via. Inside the housing 1, there are a large diameter portion 5a and a small diameter portion 5b.
Is formed, and a slidable plunger 6 constituting a proportioning valve A is housed in the first cylinder 5. The large diameter portion 5a of the first cylinder 5 is connected to the master cylinder via a conduit not shown, and the small diameter portion 5b is connected to the rear wheel cylinder via a conduit not shown.

A bypass mechanism B is provided below the small diameter portion 5b.
The second cylinder 7 that forms the second cylinder 7 is formed.
The cylinder 7 is formed coaxially with the first cylinder 5. The large diameter portion 7a of the second cylinder 7 and the large diameter portion 5a of the first cylinder 5 are communicated with each other by the input passage 8, and the small diameter portion 7b of the second cylinder 7 and the small diameter portion 5b of the first cylinder 5 output. The passages 9 communicate with each other.
The output passage 9 includes a valve seat hole 10 formed in the housing 1 between the cylinders 5 and 7, and a small hole 13 formed in the holder 11 and the valve seat 12 housed in the small diameter portion 5b of the second cylinder. And is opened and closed by a ball valve 16 held by a piston 15 via a spring 14.

Further, a bypass passage 17 for connecting the input passage 8 and the output passage 9 of the proportioning valve A is formed between the outer peripheral surface of the holder 11 and the inner peripheral wall surface of the small diameter portion 7b of the second cylinder. The bypass passage 17 is closed by a seal member 18 which is a closing valve. Therefore, the seal member 18 is fitted to the outer peripheral portion of the holder 11 located on the valve seat hole 10 side,
During the hydraulic control of proportioning valve A, the small diameter part 7
It is formed in such a shape that it comes into pressure contact with the inner wall surface of b.

Therefore, the one end portion 6a of the plunger 6 is
Is inserted in the output passage 9 and is pushed down by the urging force of the compression spring 19, so that the ball valve 16 is normally kept in the spring 1
The output passage 9 is opened by pushing down against the urging force of 4. The other end 6b of the plunger 6 is in contact with the stem 2 attached to the base end of the load detection lever 3 and is pushed down by the force of the tension spring 4. Also, the first
A small pressure receiving surface 20a and a large pressure receiving surface 20b are formed on the outer peripheral surface of the plunger 6 facing the large diameter portion 5a and the small diameter portion 5b of the cylinder 5, and when the brake hydraulic pressure is supplied to the large diameter portion 5a, It is adapted to be pressed upward by the small pressure receiving surface 20a. After that, the small pressure receiving surface 20a and the large pressure receiving surface 2
Proportioning valve A due to the difference in pressure receiving area of 0b
Is controlled.

On the other hand, the piston 15 is the second cylinder 7
Is fitted and inserted in the large-diameter portion 7a, and the pressure chamber 21 is defined in the second cylinder 7 by the piston 15. The pressure chamber 21 is connected to a branch pipe line (not shown) via a passage 22 formed in the housing 1. The branch line is
It is branched from a pipe line of a front brake system (not shown), and pressure is introduced into the pressure chamber 21 from the pipe line of the front brake system via the branch pipe line. Then, the piston 15 is biased by the spring 23 arranged in the pressure chamber 21 and the pressure introduced into the pressure chamber 21 through the passage 22, and in the normal state, the seal member 18 is moved to the second cylinder 7. The bypass passage 17 is closed by being pressed against the inner wall surface.

When the pressure in the pressure chamber 21 drops or disappears due to a defect in the front brake system, the pressure of the rear brake system acts on the piston 15 through the input passage 8, and the piston 15 operates. It is moved to the pressure chamber 21 side. Accordingly, the holder 1 integrated with the piston 15
1, the valve seat 12 and the seal member 18 also descend in the same direction, the bypass passage 17 is opened, and the pressure in the rear brake system is transmitted to the output passage 9 directly through the bypass passage 17. Therefore, the pressure of the rear brake system is directly transmitted to the rear wheel cylinder (not shown) via the input passage 8 and the output passage 9 without passing through the proportioning valve A.

[0010]

However, in the above-described conventional load-responsive braking hydraulic pressure control device, an ABS (antilock brake system) not shown is operated during braking, that is, during control of the proportioning valve A.
When the hydraulic pressure fluctuation (pulsation) from the modulator is input to the pressure chamber 21 via the branch pipe and the passage 22, the control pressure of the modulator causes the pressure Pin of the second cylinder 7 to be higher than the pressure Pc of the pressure chamber 21. Large and the pressure chamber 21
Since the pressure fluctuation of the holder 11 becomes large as shown in FIG. 10, the pressure difference between Pin and Pc causes the holder 11 integrated with the piston 15 to
The seal member 18 and the like are lowered to open the bypass passage 17 and become the output pressure Pout, which is guided to the rear wheel cylinder (not shown) via the output passage 9 and is not controlled as the proportioning valve A. It will be judged as a failure of. At a pressure Pc below the chain line shown in FIG. 10, it means that the bypass passage 17 is opened, the hydraulic pressure control of the proportioning valve A is not performed, and it is determined that the front brake system is defective.

As a result, as shown in part D of FIG. 11, the bypass mechanism B (fail safe structure) malfunctions,
This impairs the proportioning valve characteristics,
Even in the normal state, the braking force equal to that on the front wheel cylinder side is applied to the rear wheel cylinder side.
Further, the seal member 18 that closes the bypass passage 17 may frequently come into contact with the inner wall surface of the second cylinder 7 as the piston 10 moves up and down, and may be damaged, resulting in poor durability. In addition, such a problem is
Not only the pulsation from the BS modulator, but also the pulsation due to other causes such as sudden depression of the brake.

The present invention has been made in view of such an actual situation, and an object thereof is to provide a structure for releasing the hydraulic control on the rear wheel cylinder side when the front brake system is defective, in which a hydraulic pressure fluctuation such as ABS is caused. Is sometimes input to the pressure chamber that communicates with the pipeline of the front brake system,
An object of the present invention is to provide a load-responsive braking hydraulic pressure control device capable of preventing malfunction of a fail-safe structure.

[0013]

In order to solve the above-mentioned problems of the prior art, in the present invention, a proportioning valve is provided in a rear brake system between a master cylinder and a rear wheel cylinder, and the proportioning valve is provided. The input passage and the output passage of the steering valve are connected by a bypass passage, and pressure is introduced from the front brake system passage to the pressure chamber via the branch passage, and the piston is urged by the pressure to bypass the bypass passage. When a pressure loss occurs in the front brake system, a bypass valve is opened to transmit the pressure from the master cylinder to the rear wheel cylinder by bypassing the proportioning valve. In the load-responsive braking hydraulic pressure control device, the It is arranged with throttle non-return valve.

[0014]

In the load-responsive braking hydraulic pressure control device according to the present invention, the input passage and the output passage of the proportioning valve interposed in the rear brake system are connected by the bypass passage, and the pipe of the front brake system is branched. The pressure is introduced into the pressure chamber through the passage, the bypass passage is closed by the closing valve, and the hydraulic control on the rear wheel cylinder side is released when the front brake system is defective. Since a check valve with a fixed throttle is installed in the middle of the valve, even if hydraulic pressure fluctuations such as ABS are input to the pressure chamber via a branch pipe, the check valve with a fixed throttle exists. Thus, the input pressure and the pressure in the pressure chamber become substantially equal to each other, and the pressure fluctuation in the pressure chamber becomes small, so that the proportioning valve is normally controlled.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below based on the illustrated embodiments.

FIGS. 1 to 8 show an embodiment of a load-responsive braking hydraulic pressure control device according to the present invention. The same members as those in the conventional example shown in FIG. . As shown in FIG. 1, the load-responsive braking hydraulic pressure control system of the present embodiment is arranged such that the proportioning valve A is interposed in the rear brake system between the brake master cylinder 24 and the rear wheel cylinder 25. , Master cylinder 2
Reference numeral 4 is connected to a brake pedal 27 via a rod 26. Further, the output port of the master cylinder 24 is the conduit 2
8 is connected to the inlet 8a of the input passage 8 formed in the large-diameter portion 5a of the first cylinder 5 via 8 and is connected to the front wheel cylinder 30 side via the front brake system pipe 29. An ABS modulator (brake hydraulic pressure regulator) 31 is provided in the middle of these pipelines 28, 29.
Is provided. Further, the small diameter portion 5 of the first cylinder 5
The outlet 9a of the output passage 9 formed in b is connected to the rear wheel cylinder 25 side via a pipe 32 of the rear brake system.

Further, the modulator 31 and the pressure chamber 21 of the housing 1 are connected to each other via a branch pipe line 33 branched from a pipe line 29 of the front brake system, and the branch pipe line 33 is connected to the pipe line 33. One end of the passage 22 forming a part of the above is communicated with the opening 22a. Moreover, the other end opening 22b of the passage 22 communicates with the pressure chamber 21. Therefore, the pressure (control pressure) from the modulator 31 is introduced into the pressure chamber 21 through the pipe line 29, the branch pipe line 33, and the passage 22 of the front brake system.

On the other hand, a check valve 34 with a fixed throttle is housed in the pressure chamber 21 of the housing 1. As shown in FIGS. 3 and 4, the check valve 34 includes a valve body portion 36 having an orifice 35 and a passage 22 through the valve body portion 36.
It is composed of a ring-shaped spring portion 37 that urges toward the side, and the valve body portion 36 and the spring portion 37 are integrally formed using a synthetic resin material.

The valve body portion 36 is formed into a truncated cone shape in section which is tapered toward the passage 22 side, the tip end portion is inserted into the passage 22 and the outer peripheral surface is the other end opening portion 22b of the passage 22. Is provided so as to be in contact with the peripheral edge of the. Further, the spring portion 37 is formed in a ring shape tilted in a direction orthogonal to the piston 15, and an intermediate portion thereof is formed in a bent different shape to increase the biasing force, and the passage 22
The portion on the opposite side is arranged in contact with the inner peripheral wall surface of the pressure chamber 21. Therefore, the piston 15 and the spring 23 in the pressure chamber 21 are connected to the spring portion 37 of the check valve 34.
It is designed to be inserted through the inside.

However, in the check valve 34, the valve body portion 36 has the spring portion 3 by the pressure from the modulator 31.
It moves to the pressure chamber 21 side against the urging force of 7, and the other end opening 22b of the passage 22 is opened. Therefore, the pressure from the modulator 31 flows into the pressure chamber 21 through the other end opening 22b of the passage 22 and the orifice 35 as shown by the arrow in FIG. On the other hand, in the check valve 34, when the pressure on the passage 22 side is reduced, the valve body portion 36 is pressed against the passage 22 side by the urging force of the spring portion 37 and the other end opening 22b is closed. ing. Therefore, the pressure in the pressure chamber 21 is set to the orifice 3 of the valve body 36 as shown by the arrow in FIG.
It is configured so that it gradually flows out to the passage 22 side through only 5 and is throttled, so that it does not drop sharply.

In the proportioning valve A of the load-responsive braking hydraulic system according to this embodiment, the master cylinder 24 is used.
When the pressure from is input to the large diameter portion 5a of the first cylinder 5 via the modulator 31 and the conduit 28, this pressure is introduced to the large diameter portion 7a of the second cylinder 7 through the input passage 8, It is sent to the rear wheel cylinder 25 via the output passage 9, the small diameter portion 5b of the first cylinder 5 and the pipe 32. The master cylinder 24 is attached to the large diameter portion 5a of the first cylinder 5.
When the pressure from is input, the plunger 6 is first pressed upward by the small pressure receiving surface 20a. After that, the small pressure receiving surface 20a urges the plunger 6 upward. However, since the urging force of the compression spring 19 cannot be overcome while the pressure is small, the plunger 6 does not operate and the master cylinder 24 does not operate. The pressure is directly transmitted to the rear wheel cylinder 25 via the input passage 8, the large diameter portion 7a of the second cylinder 7 and the output passage 9. When the pressure of the large diameter portions 5a, 7a of the first and second cylinders 5, 7 is increased,
The plunger 6 is operated by overcoming the urging force of the compression spring 19, and the ball valve 16 is urged by the spring 14 to operate the valve seat 1.
The output passage 9 is closed by abutting against 2. After that, the ball valve 16 and the valve seat 12 are repeatedly separated and contacted as the pressure in the large diameter portions 5a and 7a of the first and second cylinders 5 and 7 increases, and the proportioning valve A is controlled. Therefore, the pressure reduced at a constant rate is transmitted to the rear wheel cylinder 25. During this time, the pressure from the master cylinder 24 is constantly supplied also into the pressure chamber 21 through the modulator 31, the branch pipe line 33, the passage 22 and the check valve 34 with a fixed throttle.
The pressure is equal to the pressure in the large diameter portion 7a of the cylinder 7, and therefore the bypass mechanism B does not operate.

Further, a defect occurs in the front brake system,
When the pressure in the pressure chamber 21 drops or disappears, the bypass mechanism B operates. That is, the pressure of the rear brake system is applied to the piston 15, the pipe 28, the large diameter portion 5 a of the first cylinder 5, the input passage 8 and the large diameter portion 7 a of the second cylinder 7.
Therefore, the piston 15 moves to the pressure chamber 21 side. Along with this, the holder 11, the valve seat 12, and the seal member 18 which are integrated with the piston 15 also descend in the same direction, the bypass passage 17 is opened, and the pressure of the rear brake system is directly output through the bypass passage 17 to the output passage 9
Transmitted to. Therefore, the pressure input from the rear brake system to the large-diameter portion 5a of the first cylinder 5 does not pass through the proportioning valve A and remains as it is in the input passage 8
And is transmitted to the rear wheel cylinder 25 via the output passage 9.

Further, in the load-responsive braking hydraulic device of this embodiment, during the brake operation in which the proportioning valve A is controlled, the hydraulic pressure fluctuation from the modulator 31 is input to the passage 22 via the branch pipe passage 33. However, when the fluctuation of the hydraulic pressure is high, the valve body portion 36 of the check valve 34 with the fixed throttle is provided.
Is pushed to the pressure chamber 21 side by the pressure from the modulator 31 to open the other end opening 22b of the passage 22, and the pressure from the modulator 31 is the other end opening 22b and the orifice 35 as shown by the arrow in FIG. Through the pressure chamber 21
The pressure in the pressure chamber 21 rises as shown in FIG. When the hydraulic pressure fluctuation is low, the valve body 36 of the check valve 34 with the fixed throttle closes the other end opening 22b of the passage 22, and the pressure in the pressure chamber 21 passes through the orifice 35 to the passage 22 side. However, as shown in FIG. 7, it takes a long time without dropping sharply as shown in FIG. 7, and during that time, the hydraulic pressure fluctuation becomes high again and the pressure in the pressure chamber 21 rises. To do. Therefore, the pressure in the large-diameter portion 7a of the second cylinder 7 and the pressure in the pressure chamber 21 become substantially equal regardless of whether the hydraulic pressure fluctuation from the modulator 31 is high or low, and it is determined that the front brake system has failed. By this, the bypass passage 17 is opened, and the hydraulic pressure of the proportioning valve A is not controlled to a pressure below the chain line in FIG. 7 where it is not controlled. Therefore, the malfunction of the bypass mechanism B is distinguished from the failure of the front brake system. Does not occur, and the proportioning valve A is normally controlled as shown in FIG.

In the load-responsive braking hydraulic system of this embodiment,
Since the check valve 34 with a fixed throttle is housed and arranged in the pressure chamber 21 of the housing 1, the structure does not become complicated,
Conventional load-responsive braking hydraulic systems can be utilized. Moreover, in the check valve 34 of this embodiment, since the valve body portion 36 and the spring portion 37 that form the check valve 34 are integrally molded using a synthetic resin material, there is no risk of increasing the cost of parts.

The embodiment of the present invention has been described above.
The present invention is not limited to the embodiments described above, and various modifications and changes can be made based on the technical idea of the present invention.

For example, in the check valve 34 with a fixed throttle in the above-described embodiment, the valve body portion 36 and the spring portion 37 are integrally molded using a synthetic resin material, but the valve body portion 36 and the spring portion 37 are formed. And may be formed separately. Further, the check valve 34 uses a plate-shaped body for the valve body 36, and
7 is composed of a compression spring, and the orifice 3
Even if the plate-shaped body provided with 5 is urged toward the passage 22 by the compression spring, the same effect is obtained. Further, in the above-described embodiment, the check valve 34 is housed and arranged in the pressure chamber 21 formed in the housing 1, but it may be arranged in the middle of the branch pipe line 33.

[0027]

As described above, in the load-responsive braking hydraulic pressure control device according to the present invention, the proportioning valve is interposed in the rear brake system between the master cylinder and the rear wheel cylinder, and the proportioning valve The input passage and the output passage are connected by a bypass passage, and pressure is introduced from the front brake system passage to the pressure chamber via the branch passage, and the piston is urged by the pressure to close the bypass passage. With a shut-off valve
When the pressure loss occurs in the front brake system, the bypass passage is opened to transmit the pressure from the master cylinder to the proportioning valve and to the rear wheel cylinder. A check valve with a fixed throttle is arranged in the middle of the branch line. Therefore, according to the load-responsive braking hydraulic pressure control device of the present invention, even if the hydraulic pressure fluctuation of the ABS modulator or the like is input to the pressure chamber via the branch pipe line, the check valve with the fixed throttle can be operated. Since the hydraulic pressure fluctuation in the pressure chamber can be reduced by the throttling action, the failure of the front brake system and the erroneous operation of the bypass mechanism can be prevented, and normal proportioning valve control can be performed and the bypass passage There is no risk of damaging the stop valve, and durability can be improved.

[Brief description of drawings]

FIG. 1 is a conceptual diagram showing a brake system of an automobile.

FIG. 2 is a vertical cross-sectional view showing a load-responsive braking hydraulic pressure control device according to an embodiment of the present invention.

FIG. 3 is a cross-sectional view taken along the line CC in FIG.

FIG. 4 is a perspective view showing a check valve with a fixed throttle arranged in the load-responsive braking hydraulic pressure control device.

FIG. 5 is a cross-sectional view showing a state in which pressure on the passage side is introduced into the pressure chamber via the check valve with a fixed throttle.

FIG. 6 is a cross-sectional view showing a state in which the pressure in the pressure chamber is discharged to the passage side through the orifice of the check valve with a fixed throttle.

FIG. 7 is an explanatory diagram showing a relationship between pressure and time in a pressure chamber provided in the load-responsive braking hydraulic pressure control device.

FIG. 8 is an explanatory diagram showing characteristics of the load-responsive braking hydraulic pressure control device.

FIG. 9 is a vertical cross-sectional view showing a conventional load-responsive braking hydraulic pressure control device.

FIG. 10 is an explanatory diagram showing a relationship between pressure and time of a pressure chamber provided in a conventional load-responsive braking hydraulic pressure control device.

FIG. 11 is an explanatory diagram showing characteristics of a conventional load-responsive braking hydraulic pressure control device.

[Explanation of symbols]

 1 Housing 5 First Cylinder 5a Large Diameter 5b Small Diameter 6 Plunger 7 Second Cylinder 7a Large Diameter 7b Small Diameter 8 Input Passage 8a Inlet 9 Output Passage 9a Outlet 10 Valve Seat Hole 11 Holder 12 Valve Seat 13 Small Hole 14 Spring 15 Piston 16 Ball Valve 17 Bypass Passage 18 Sealing Member 19 Compression Spring 21 Pressure Chamber 22 Passage 23 Spring 24 Brake Master Cylinder 25 Rear Wheel Cylinder 26 Rod 27 Brake Pedal 28, 29, 32 Pipeline 30 Front Wheel Cylinder 31 Modulator 33 Branch Pipe Line 34 Check valve with fixed throttle 35 Orifice 36 Valve body 37 Spring portion A Proportioning valve B Bypass mechanism

Claims (3)

[Claims] 1. A proportioning valve is interposed in a rear brake system between a master cylinder and a rear wheel cylinder, and an input passage and an output passage of the proportioning valve are connected by a bypass passage and a front brake system is connected. When a pressure is introduced from the pipeline to the pressure chamber via the branch pipeline, a closing valve for biasing the piston by the pressure to close the bypass passage is provided, and when pressure disappears in the front brake system, In a load-responsive braking hydraulic pressure control device in which a bypass passage is opened to transmit the pressure from the master cylinder to the rear wheel cylinder by bypassing the proportioning valve, a fixed throttle is provided in the middle of the branch pipe line. A load-responsive braking hydraulic pressure control device characterized in that a check valve is provided. 2. The check valve with a fixed throttle is housed in the pressure chamber, the valve body having an orifice provided at an opening of a passage that connects the pressure chamber and the branch pipe line, The load-responsive braking hydraulic pressure control device according to claim 1, wherein the valve body portion is configured by a spring portion that biases the valve body portion toward the passage side. 3. A check valve with a fixed throttle, which is housed in the pressure chamber, and provided with an orifice provided at an opening of a passage that connects the pressure chamber and the branch pipe line, and a valve body portion, 2. A ring-shaped spring portion for urging the valve body portion toward the passage, and the valve body portion and the spring portion are integrally molded using a synthetic resin material. The load-responsive braking hydraulic pressure control device described.