JPH0885446A - Brake pressure control valve - Google Patents

Abstract

PURPOSE: To provide a brake pressure control valve capable of guaranteeing the brake of a compressed air feed system when a slope start auxiliary device is operated even if the compressed air feed system on the upstream side of the brake pressure control valve fails. CONSTITUTION: A signal pressure chamber 27 and an output pressure chamber 26 are communicated with each other via a passage, and the passage is blocked by a valve element 34 excited by a spring 35. When the pressure of the output pressure chamber 26 becomes a prescribed value or below against the pressure of the signal pressure chamber 27, the valve element 34 is operated by the differential pressure to open the passage.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brake pressure control valve used in a hill start assist device.

[0002]

2. Description of the Related Art In large vehicles such as trucks and trailers, a brake valve is attached to a brake pedal. In such a brake operating device, by depressing the brake pedal, compressed air in the air tank is supplied to the brake actuator via the brake valve, and the hydraulic pressure generated by the brake actuator is applied to the wheel cylinder, whereby The brake is working. Then, when the brake pedal is released, the brake is released.

In the above-mentioned conventional brake operating device, when temporarily stopping on a slope or the like, it is necessary to operate such as pulling a side brake, and when starting on an uphill road, the side brake is applied. It required very skilled operation such as operating the accelerator and clutch while releasing. For this reason, the driving operation is complicated, and there is a risk that the engine stalls or the vehicle retreats when starting on an uphill road.

Therefore, the applicant first provided a brake operating device which solved the above-mentioned problems (Japanese Patent Publication No. 6-45334).
(See the official gazette).

In this brake operating device, as shown in FIG. 4, when the brake pedal 1a is depressed, the brake valve 1 enters the supply mode, and the compressed air in the air tank 2a passes through the brake valve 1 and the conduit 6a. Fluid pressure operation check valve) 10 is supplied to the input port 10a,
It is supplied to the brake actuator 3 from the output port 10b via the output pressure chamber 11 of the brake pressure control valve 10 shown in FIG. Then, the brake actuator 3 is operated and the working fluid is supplied to the wheel cylinder 4 via the pipe 6c. Further, when the brake pedal 1a is released, the brake valve 1 enters the exhaust mode, and the compressed air in the brake actuator 3 passes through the pipe line 6b, the brake pressure control valve 10, and the pipe line 6a, and then the brake valve 1 is released.
Is discharged to the outside through the exhaust port 1b. Therefore, the brake is released. Such operation is no different from that of the conventional brake operating device.

In this brake operating device, if the brake pedal 1a is continuously depressed while the vehicle is stopped, this state is detected by a controller (not shown), and the solenoid valve 5 is actuated after a lapse of a predetermined time (for example, 1 second). Then, the compressed air in the air tank 2b is introduced into the signal pressure chamber 12 of the brake pressure control valve 10 shown in FIG. The compressed air causes the valve body 1 in the brake pressure control valve 10 to move.
The piston 14 with 3 is energized. As a result, the piston 14 is moved by the pressure of the signal pressure chamber 12 against the biasing force of the spring 15 as shown in FIG. Then, the piston 14 contacts the step portion 10c and is stopped there. In this state, the valve body 13 contacts the valve seat 10d, and the input port 10a is closed by the valve body 13. Therefore, the compressed air inside the brake actuator 3 is retained as it is, and the brake operating state is maintained.

Therefore, even if the vehicle is temporarily stopped on a slope or the like and the brake pedal 1a is released, the vehicle does not start to move naturally, and the trouble of pulling the side brakes one by one is eliminated. When the brake pedal 1a is strongly depressed again in the stopped state shown in FIG. 6, only the valve body 13 is moved by the pressure in the input port 10a to open the input port 10a, and the brake actuator 3 is replenished with compressed air. To be done. Therefore, a desired braking force according to the degree of inclination of a slope or the like can be easily obtained. Further, the pressure of the output pressure chamber 11 is balanced with the pressure of the signal pressure chamber 12 and is maintained at a relatively low pressure (for example, 1/3 to 1/4 of the maximum brake pressure), so that the brake operation is performed for a long time. Even in the state, unreasonable pressure does not act on the conduits 6b, 6c and the like, and the durability thereof can be improved.

Next, when the vehicle is ready to start by operating the accelerator, clutch, etc., the controller senses this and demagnetizes the solenoid valve 5. Then, the compressed air in the signal pressure chamber 12 is discharged to the outside from the exhaust port (not shown), and the piston 14 is returned to its original state by the urging force of the spring 15. At this time, if the brake pedal 1a is released, the compressed air in the brake actuator 3 is exhausted to the outside from the exhaust port 1b of the brake valve 1, the brake is released, and the vehicle can start. Therefore, particularly when starting on an uphill road, it is not necessary to perform a skilled operation such as operating an accelerator or a clutch while loosening a side brake as in the conventional case, and a smooth start is possible without causing a stall or a vehicle retreat.

[0009]

By the way, in the above-mentioned brake operating device, one compressed air supply system upstream of the brake pressure control valve 10, that is, compressed air supply from the air tank 2a to the brake pressure control valve 10 is supplied. When one of the systems fails, compressed air is no longer supplied to the brake actuator 3 of that system, so the braking action of the system cannot be obtained. Therefore, even if the slope starting assist device is operated in that state, the braking force acts only on one system, and there is a risk that the braking force will be insufficient and the vehicle cannot be stopped on the slope.

Therefore, an object of the present invention is to provide a brake pressure control valve which can ensure the braking action of the system even if the compressed air supply system upstream from the brake pressure control valve fails.

[0011]

According to the brake pressure control valve of the present invention, an input port connected to the brake valve, an output port connected to the brake actuator, and a switching valve are selectively connected to the air tank or the atmosphere. A valve housing having a signal pressure port and a valve seat at the open end of the input port, and a first valve body at the tip, and a signal pressure communicating with the signal pressure port in the valve housing. And an output pressure chamber communicating with the output port and urged by a first spring in a direction to reduce the signal pressure chamber, and actuated by the pressure of the air tank supplied to the signal pressure chamber. In the brake pressure control valve including the main piston that constitutes the opening / closing valve by bringing the first valve body and the valve seat into contact with each other, in the signal pressure chamber and the output pressure chamber via the passage. Communicate At the same time, the passage is closed by the second valve body urged by the second spring, and when the pressure in the output pressure chamber becomes less than or equal to a predetermined value with respect to the pressure in the signal pressure chamber, the differential pressure To activate the second valve body,
The passage is open.

[0012]

In the brake operating device employing the brake pressure control valve of the present invention, when the slope start assist device is operated in a state where one compressed air supply system upstream of the brake pressure control valve is defective. Then, the compressed air in the signal pressure chamber is replenished to the brake actuator of the defective system. Therefore, the braking force of the defective system can be secured, and the vehicle can be reliably stopped on a slope or the like.

[0013]

1 shows an embodiment of a brake pressure control valve employed in a brake operating device according to the present invention, and FIGS. 2 and 3 show its operating state.

Housing 21 of brake pressure control valve 20
Is composed of end housing blocks 21a, 21a and a central housing block 21b. An input port 22 and an output port 23 are formed in the end housing block 21a, and a signal pressure port 24 is formed in the central housing block 21b. Are formed. A main piston 25 is arranged in the housing 21, and the piston 25 defines an output pressure chamber 26 and a signal pressure chamber 27. The input port 22 and the output port 23 are open to the output pressure chamber 26.

The main piston 25 is biased by a spring 28 provided in the output pressure chamber 26 in a direction to reduce the signal pressure chamber 27. Further, the main piston 25 is formed with a hole 25a opening at its front end. Further, the main piston 25 has a chamber 25b at the rear end portion.

An auxiliary piston 29 is fitted in the hole 25a of the main piston 25. This auxiliary piston 29 has a hole 29a in a direction perpendicular to its axis.
Is installed throughout. The auxiliary piston 29 has a hole 2
The pin 30 loosely fitted in the 9a is provided with the hole 2 of the main piston 25.
It is held by the main piston 25 by engaging with 5c. The auxiliary piston 29 has a hole 29 that connects the rear end surface of the piston 29 and the hole 29a.
b. The hole 25a is replaced by the holes 29b, 29.
It is connected to the output pressure chamber 26 via a and 25c.
The auxiliary piston 29 has a valve body 31 (first valve body of the invention) at the tip. And this auxiliary piston 2
9 is urged toward the input port 22 by a spring 32 (first spring of the present invention) provided in the hole 25a.

A tubular retainer 33 is fitted to the main piston 25 to prevent the pin 30 from falling out of the hole 25c of the main piston 25.

The chamber 25b of the main piston 25 is
Inlet port 25d (opening to the signal pressure chamber of the present invention)
To the signal pressure chamber 27, and to the hole 25a via the outlet port 25e.

A valve element 34 (second valve element of the present invention) is housed in the chamber 25b, and the valve element 34 is biased by a spring 35 (second spring of the present invention).
The inlet port 25d is closed.

An electromagnetic switching valve 40 is attached to the brake pressure control valve 20. In this electromagnetic valve 40, valve chambers 42 and 43 are formed below a plunger 41, and these valve chambers 42 and 43 are connected to each other by a passage 44. Valve bodies 45 and 46 are arranged in the valve chambers 42 and 43, respectively, and these valve bodies 45 and 46 are connected to each other by a rod 47a. Furthermore, the valve body 4
5, 46 are connected to the plunger 41 via a rod 47b. Then, when the plunger 41 moves up and down, the pair of valve seats 4 formed at both upper and lower ends of the passage 44.
The valve bodies 45 and 46 are configured to come into contact with and separate from the valve bodies 8 and 49, respectively. The valve bodies 45 and 46 are urged upward by a spring 50 in FIG.

In such a brake pressure control valve 20, the intermediate portion of the passage 44 is communicated with the signal pressure chamber 27 of the brake pressure control valve 20 via the signal pressure port 24. The valve chamber 42 is communicated with the atmosphere via a passage 51.

Then, similarly to the case shown in FIG. 4, the input port 22 of the brake pressure control valve 20 is connected via the pipe line 6a.
The output port 23 is connected to the output port 1c of the brake valve 1.
Is connected to the input port 3a of the brake actuator 3 via the conduit 6b. Further, the valve chamber 4 of the solenoid valve 40
3 is connected to the air tank 2b via a pipe line 6d.

The brake pressure control valve 20 is constructed as described above, the solenoid 54 of the solenoid valve 40 is demagnetized when the vehicle is running, and the pair of valve bodies 45 and 46 are springs 50 as shown in FIG. It has been pushed upwards. Therefore, the upper valve body 45 is separated from the valve seat 48 and abuts on the valve seat 49 of the lower valve body 46. Therefore, the compressed air is not introduced into the signal pressure chamber 27 of the brake pressure control valve 20, and the main piston 25 does not return to the return spring 28.
Is held in the position shown in FIG. 1, and the brake pressure control valve 2
The 0 input port 22 is open.

When the brake pedal 1a of the brake valve 1 is depressed in this state, the brake valve 1 enters the supply mode, and compressed air is supplied to the input port 22 of the brake pressure control valve 20 via the brake valve 1. This compressed air is discharged from the output port 23 through the output pressure chamber 26, is supplied to the brake actuator 3, and operates the brake actuator 3. Then, the brake actuator 3 generates a working fluid corresponding to the pressure of the compressed air, and the wheel cylinder 4 is operated by the pressure of the fluid. Further, when the brake pedal 1a is released, the brake valve 1 enters the exhaust mode, and the compressed air in the brake actuator 3 is discharged to the outside from the exhaust port 1b of the brake valve 1 via the brake pressure control valve 20. Therefore, the hydraulic pressure acting on the wheel cylinder 4 disappears and the brake is released.

Next, when the brake pedal 1a is continuously depressed while the vehicle is stopped, this state is detected by the controller, and the solenoid 54 of the solenoid valve 40 is excited after a lapse of a predetermined time (for example, 1 second). When the solenoid 54 is excited, the plunger 41 moves downward as shown in FIG. 2 against the biasing force of the spring 50, the valve element 45 contacts the upper valve seat 48, and the valve element 46 moves downward. It is separated from the side valve seat 49. Therefore, compressed air is introduced into the signal pressure chamber 27 of the brake pressure control valve 20 via the signal pressure port 24. As a result, the main piston 25 is moved by the pressure of the signal pressure chamber 27 against the biasing force of the spring 28 as shown in FIG. The main piston 25 abuts against the stepped portion 21c of the valve housing 21 and is stopped there. In this state, the valve body 3 of the auxiliary piston 29
1 contacts the valve seat 36 and closes the input port 22. Therefore, the compressed air inside the brake actuator 3 is retained as it is, and the wheel cylinder 4 continues the brake operation. Therefore, even if the vehicle is temporarily stopped on a slope or the like and the brake pedal 1a is released, the vehicle does not start to move naturally, and there is no need to bother pulling the side brakes.

When the brake pedal 1a is strongly depressed again in the stopped state shown in FIG. 2, the pressure in the input port 22 causes the auxiliary piston 29 to move against the urging force of the spring 32, so that the valve body 31 moves. The brake actuator 3 is separated from the valve seat 36 and the compressed air is replenished. Therefore, a desired braking force according to the degree of inclination of a slope or the like can be easily obtained. When the pressure in the output pressure chamber 26 is equal to or higher than the predetermined pressure, the main piston 25 moves against the pressure in the signal pressure chamber 27, and the valve element 31 separates from the valve seat 36. Therefore, when the brake pedal 1a is released, the output pressure chamber 26
Is discharged from the exhaust port 1b of the brake valve 1,
When the pressure in the output pressure chamber 26 reaches a predetermined pressure, the main piston 25 is moved and the input port 22 is closed. for that reason,
The pressure in the output pressure chamber 26 is balanced with the pressure in the signal pressure chamber 27 and is relatively low (for example, 1/3 to 1 of the maximum brake pressure).
/ 4), even if the brake is operated for a long period of time, the pipe line 6b or the like is not subjected to an excessive pressure and the durability thereof can be improved.

Next, when the vehicle is ready to start by operating the accelerator, clutch or the like, the controller senses this and the solenoid 54 of the solenoid valve 40 is demagnetized. When the solenoid 54 is demagnetized, the valve bodies 45 and 46 are locked by the spring 5
The urging force of 0 causes the valve body 45 to move away from the valve seat 48 and the valve body 46 to move toward the valve seat 4 as shown in FIG.
Contact 9 Therefore, the compressed air in the signal pressure chamber 27 of the brake pressure control valve 20 is discharged to the outside through the signal pressure port 24, the passage 44, the valve chamber 42, and the passage 51. Along with that, the main piston 25 returns to the original position by the urging force of the spring 28. Then, the compressed air in the brake actuator 3 is discharged to the outside from the exhaust port 1b of the brake valve 1, the brake is released, and the vehicle can start. Therefore, particularly when starting on an uphill road, it is not necessary to perform a skilled operation such as operating an accelerator or a clutch while loosening a side brake as in the conventional case, and a smooth start is possible without causing a stall or a vehicle retreat.

In the brake operating device shown in FIG. 4,
When the slope start assist device is operated in the state where the compressed air supply system on the upstream side of the brake pressure control valve 20 is defective, that is, when the electromagnetic switching valve 40 is operated, it is shown in FIG. As described above, the main piston 25 is actuated by the compressed air supplied to the signal pressure chamber 27, the valve body 31 contacts the valve seat 36, and the compressed air supply system upstream of the brake pressure control valve 20 is shut off. At the same time, the valve body 34 is operated against the biasing force of the spring 35 by the pressure of the compressed air in the signal pressure chamber 27. Therefore, the compressed air in the signal pressure chamber 27 is converted into the chamber 25b and the holes 25a, 29b, 29a, 25.
is supplied to the output pressure chamber 26 via c, and the output port 2
3, it is supplied to the brake actuator 3 via the conduit 6b. As a result, the wheel cylinder 4 on the defective side can also be operated. Then, when the pressure in the output pressure chamber 26 reaches a predetermined pressure, the valve body 34 closes the inlet port 25d by the urging force of the spring 35.

When the operation of the slope start assisting device is released, the compressed air in the signal pressure chamber 27 is discharged to the outside, so that the main piston 25 is restored. Therefore, the compressed air acting on the brake actuator 3 also passes through the output pressure chamber 26 and the input port 22 and the brake valve 1
Is discharged from the outside.

In short, in the brake pressure control valve 20, when the pressure of the output pressure chamber 26 is lower than the predetermined pressure when the compressed air is supplied to the signal pressure chamber 27 (the state of FIG. 2), that is, When the difference between the pressure P1 of the signal pressure chamber 27 and the pressure P2 of the output pressure chamber 26 is larger than the set load F of the spring 35, the valve element 34 is opened, and the compressed air in the output pressure chamber 27 enters the output pressure chamber 26. Supplied. On the other hand, in the brake pressure control valve 20, when the output pressure chamber 26 reaches a predetermined pressure P3 or more in the state of FIG. 2 in order to protect the pipe line 6b, the main piston 25 is returned by that pressure, and Therefore, it has a function of opening the input port 22. Therefore, in the brake pressure control valve 20, the relationship between the pressures is set to P1>
The pressure acting area on the output pressure chamber side 26 of the main piston 25, the pressure acting area on the signal pressure chamber 27 side, the set load of the springs 28, 35, etc. are determined so that P3 ≧ P2.

[0031]

As described above, in the brake pressure control valve according to the present invention, when one of the upstream systems of the brake pressure control valve fails, the slope starting assist device is operated, Compressed air in the signal pressure chamber is replenished to the defective brake actuator in the system. Therefore, it is possible to secure the braking action on the side of the system where the defect has occurred when the hill start assist device is operating, so that the vehicle can be reliably stopped on a hill or the like.

[Brief description of drawings]

FIG. 1 is a sectional view showing a brake pressure control valve used in a brake operating device according to the present invention and showing a non-actuated state of the brake pressure control valve.

FIG. 2 is an enlarged cross-sectional view of an essential part of the operating state of the brake pressure control valve shown in FIG.

FIG. 3 is an enlarged cross-sectional view of an essential part of the operating state of the brake pressure control valve shown in FIG.

FIG. 4 is a piping diagram conceptually showing a brake operating device.

FIG. 5 is a sectional view showing a conventional brake pressure control valve and showing a non-operating state of the brake pressure control valve.

FIG. 6 is an enlarged cross-sectional view of an essential part showing an operating state of the brake pressure control valve shown in FIG.

[Explanation of symbols]

 1 Brake valve 2a, 2b Air tank 3 Brake actuator 5 Solenoid valve 6a, 6b, 6d Pipe line 20 Brake pressure control valve 21 Valve housing 21a, 21b Housing block 21c Step 22 Input port 23 Output port 24 Signal pressure port 25 Main piston 25a Hole 25b Chamber 25c Hole 25d Inlet port 25e Outlet port 26 Output pressure chamber 27 Signal pressure chamber 28 Spring 29 Auxiliary piston 29a, 29b Hole 31 Valve body (first valve body) 32 Spring (first spring) 33 Retainer 34 Valve Body (second valve body) 35 Spring (second valve body) 36 Valve seat 40 Electromagnetic switching valve

Claims (3)

[Claims] 1. An input port connected to a brake valve, and an output port connected to a brake actuator.
A valve housing having a signal pressure port selectively connected to an air tank or the atmosphere through a switching valve and having a valve seat at the opening end of the input port; and (b) a first valve body at the tip. The valve housing is defined by a signal pressure chamber communicating with the signal pressure port and an output pressure chamber communicating with the output port, and is provided in a direction to reduce the signal pressure chamber by the first spring. A brake pressure control valve that is energized and operated by the pressure of the air tank that is supplied to the signal pressure chamber, and that includes a main piston that forms an opening / closing valve by bringing the first valve body and the valve seat into contact with each other. In (c), the signal pressure chamber and the output pressure chamber are communicated with each other through a passage, and the passage is closed by a second valve body urged by a second spring. The pressure is relative to the pressure in the signal pressure chamber When it is fixed below, in differential pressure by actuating said second valve body, a brake pressure control valve being characterized in that so as to open the passage. 2. A step portion is formed on the valve housing,
The stepped portion restricts a certain amount of movement of the main piston, and a hole is formed in the tip surface of the main piston, and the auxiliary piston is inserted into the hole so that the auxiliary piston can be retracted. The first valve element at the tip of the valve, and the third spring is provided in the hole between the auxiliary piston and the main piston, and the hole communicates with the output pressure chamber. And opening the hole in the signal pressure chamber, further accommodating the second valve body and the second spring in the hole, and biasing the second valve body by the second spring. The brake pressure control valve according to claim 1, wherein the opening is closed. 3. The brake pressure control valve according to claim 2, wherein a passage is formed in the auxiliary piston so that the hole communicates with the output pressure chamber.