JPH08164839A - Method and apparatus for preventing exhaust port from freezing in air overhydraulic booster - Google Patents

Abstract

PURPOSE: To prevent an exhaust port portion of a pressure control value device from being blocked caused by freezing or the like in an air overhydraulic booster. CONSTITUTION: An exhaust port 300 is provided which affords communication between the exhaust side of a pressure controlling valve device 30, a no-pressure chamber 12 of a pneumatic operation section 10 and the atmosphere in common. Thus, a pneumatic piston 17 moves every time a usual brake is applied and released so that air frequently flows in the portion of the exhaust port 300 as the volume of the no-pressure chamber 12 is changed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air-over-hydraulic booster used in a brake system for vehicles such as trucks and buses and having a brake control function such as anti-skid control or traction control.

[0002]

BACKGROUND OF THE INVENTION Air over hydraulic boosters generally include a pneumatic actuator and a hydraulic cylinder. The pneumatic actuator has a pneumatic piston that forms a pressure chamber and a non-pressure chamber inside its housing. The hydraulic cylinder portion has a hydraulic piston that is operably connected to the pneumatic piston.
The air-over-hydraulic booster converts the air pressure from the brake valve into hydraulic pressure and uses the hydraulic pressure as brake pressure. That is, when compressed air from the brake valve is supplied into the pressure chamber, the pneumatic piston slides toward the non-pressure chamber side, and the hydraulic piston slides accordingly to generate brake hydraulic pressure. As a means for adding a brake control function to such an air over hydraulic booster, a means for controlling the pressure at the pneumatic stage, or
There is a means for controlling the pressure at the hydraulic pressure stage. Of them
The means for controlling the pressure at the pneumatic pressure stage requires a comparatively light equipment, and is preferable from the point of view of attachment and the like. The present invention
The target is an air-over-hydraulic booster that performs brake control by such air pressure control.

As an air-over-hydraulic booster to which a brake control function by pneumatic pressure control is added, there is, for example, one provided with a pressure control valve device for holding or discharging the air pressure supplied to the pressure chamber of the pneumatic operating portion to the atmosphere.
(For example, disclosed in Japanese Patent Laid-Open No. 3-167061 or Japanese Utility Model Publication No. 6-29137.) Two valves, a shutoff valve and an exhaust valve, are provided inside the pressure control valve device. The shutoff valve is located in a passage that connects the brake valve and the pressure chamber, and opens or closes the valve to connect or shut off the passage. The other exhaust valve is located in a passage that connects the pressure chamber and an exhaust port that communicates with the atmosphere, and opens or closes the passage to open or close the passage.

In the normal brake operation-release state, the shutoff valve is in the open position and the other exhaust valve is in the closed position. That is, the brake valve and the pressure chamber of the pneumatic operating portion are in communication with each other. The pressure control valve device operates to perform brake control. When a brake holding signal is issued from the outside, the shutoff valve switches to the closed position based on the signal. Then, the air pressure in the pressure chamber is kept constant, and accordingly, the brake fluid pressure is kept constant. When a brake slack signal is issued from the outside, the exhaust valve is switched to the open position based on the signal, and the pressure chamber of the pneumatic operating unit and the exhaust port of the pressure control valve device are communicated with each other. At this time, the shutoff valve is in the closed position. Then, the compressed air supplied to the pressure chamber is released to the atmosphere through the exhaust valve and the exhaust port.
Along with this, the pneumatic piston slides toward the pressure chamber, and the brake fluid pressure is accordingly relaxed. The above publications
A technique for integrating such a pressure control valve device with the housing of the pneumatic actuator has been clarified. By integrating them, it is possible to reduce the installation space for them and to improve the mountability and maintainability.

[0005]

The brake control by switching the valves is not so frequently performed. Because, for example, normal normal brake operation-
This is because the pressure control valve device is activated and the brake control is performed only when the wheels tend to lock or the wheels tend to idle during the release. For this reason, the frequency of air flowing through the exhaust port of the pressure control valve device is low. Therefore, for example, when using an air-over-haodrolic booster including such a pressure control valve device in a snowy area, snow or ice that the vehicle rolls up adheres to cover the opening of the exhaust port and blocks the exhaust port. It may happen. Further, when the exhaust port is provided with a check valve for preventing foreign matter from entering from the outside, the check valve may lose its valve function due to freezing or the like, and may block the exhaust port. The blockage of the exhaust port hinders the discharge of the compressed air in the pressure chamber to the atmosphere when the brake is loosened during the brake control. Therefore, proper brake control cannot be performed.

[0006]

SUMMARY OF THE INVENTION In consideration of the above problems, the present invention effectively prevents an exhaust port of a pressure control valve device from being blocked by freezing or the like in an air overhydric booster equipped with the pressure control valve device. It is an object of the present invention to provide a technique capable of surely performing proper brake control.

[0007]

By the way, in a general air-over-hydraulic booster, an exhaust port is also provided in the pneumatic operating portion. The exhaust port communicates the pressureless chamber with the atmosphere. Then, the atmosphere is allowed to flow in and out of the pressureless chamber whose volume changes according to the sliding of the pneumatic piston, so that unnecessary pressure that prevents the sliding of the pneumatic piston is generated in the pressureless chamber. To prevent. This exhaust port
Air passes through each time the normal brake operation-release (every time the pneumatic piston slides). Normal braking-release is often done. Therefore, the air passes through the exhaust port frequently. From the empirical fact, the exhaust port provided for this non-pressure chamber is unlikely to be blocked due to freezing or the like due to such frequent air flow.

The present invention focuses on these points. In the present invention, the air that frequently flows according to the change in volume of the pressureless chamber is used to prevent the exhaust port of the pressure control valve device from freezing. That is, a method is employed in which the air flowing between the pressureless chamber and the atmosphere according to the change in volume of the pressureless chamber is brought into contact with the exhaust port of the pressure control valve device. The frequency of the air is extremely higher than the frequency of the air (compressed air) from the pressure chamber during brake control passing through the exhaust port. By bringing such frequently flowing air into contact with the exhaust port of the air pressure control valve device, it is possible to prevent the exhaust port from being blocked by snow, freezing, or the like. By preventing the exhaust port from being blocked, the air pressure of the pressure chamber can be reliably discharged from the exhaust port to the atmosphere, and proper brake control can be reliably performed.

In order to bring such frequently flowing air into contact with the exhaust port of the pressure control valve device more effectively, the air is configured to flow through the exhaust port. For example, an exhaust port is provided that connects both the exhaust side of the pressure control valve device and the non-pressure chamber of the pneumatic operating unit to the atmosphere in common. Air flows between the pressureless chamber and the atmosphere through the exhaust port according to the change in volume of the pressureless chamber. Since the air flows frequently, the exhaust port is less likely to be blocked by snow, freezing, or the like. When the brake is released during brake control, the compressed air supplied to the pressure chamber is discharged to the atmosphere through the exhaust port in which such blockage is unlikely to occur. Therefore, compressed air can be reliably discharged, and proper brake control can be reliably performed.

Here, the pressure control valve device is integrated with the pneumatic operating portion. By this integration, the installation space of the entire device can be reduced. Further, by this integration, the exhaust port of the pressure control valve device and the non-pressure chamber of the pneumatic operating portion can be arranged closer to each other. That is, since the pressure control valve device for preventing the blockage of the exhaust port and the non-pressure chamber of the pneumatic operating part for preventing the blockage are arranged in the vicinity of each other, the facility for preventing the blockage is complicated. I won't.

[0011]

1 is a sectional view of an air-over hydraulic booster 100 according to an embodiment of the present invention. The air-over-hydraulic booster 100 operates by receiving compressed air from the brake valve B / V and operating.
0, a hydraulic cylinder portion 20 that generates a brake hydraulic pressure to the brake actuator W / C, and a pressure control valve device 30 that controls the air pressure to the pneumatic actuator 10 based on a command from the outside.

The pneumatic operating portion 10 has a pneumatic piston 17 which is slidable in a housing 19 thereof. The pneumatic piston 17 includes a rod portion 17a extending in the sliding direction and a pressure receiving portion 17b located at one end of the rod portion 17a.
The pneumatic piston 17 has a brake valve B at one end thereof.
A pressure chamber 11 for supplying / exhausting compressed air from / V and a non-pressure chamber 12 on the other end side are formed. An air inlet 16 is provided on the wall surface of the housing 19 on the pressure chamber 11 side. Air from the brake valve is the air inlet 1
A pneumatic piston 17 introduced into the pressure chamber 11 through 6 and receiving the air pressure thereof returns a return spring 1 arranged in the non-pressure chamber 12.
It slides toward the non-pressure chamber 12 side against the biasing force of 8. Pressureless chamber 1
At the other end of 2, an overstroke sensor 50 for detecting the sliding limit of the pneumatic piston 17 is provided.

The hydraulic cylinder portion 20 is located on the pressureless chamber 12 side of the pneumatic operating portion 10. Hydraulic cylinder section 20
Has a hydraulic piston 27 therein. The hydraulic piston 27 is operably connected to the pneumatic piston 17.
When the compressed air is supplied to the pressure chamber 11, the pneumatic piston 17 slides in response to the compressed air, and the hydraulic piston 2 receives it.
7 slides. The hydraulic piston 27 generates a brake hydraulic pressure to the brake actuator W / C while reducing the volume of the hydraulic chamber 21.

The pressure control valve device 30 is located above the pneumatic operating portion 10 and the hydraulic cylinder portion 20 in FIG. FIG. 2 is an enlarged view of a cross section 2-2 of the pressure control valve device 30 shown in FIG. The pressure control valve device 30 is a brake valve B.
/ V and the pneumatic working unit 10. Then, a control valve inlet 35 connected to the brake valve B / V, a control valve outlet 36 connected to the pressure chamber 11 (air inlet 16) of the pneumatic operating unit 10, and an exhaust port 300 communicating with the atmosphere are provided. Have. In particular, the control valve outlet 36 and the pressure chamber 11 (air inlet 1
6) is connected via a communication line 66.

The pressure control valve device 30 has a shutoff valve 37 and an exhaust valve 38 for controlling the air pressure inside. Both of these valves are 2-port-2 position solenoid valves. The shutoff valve 37 is the control valve inlet 35 (brake valve B / V
Side) and the control valve outlet 36 (pressure chamber 11 side) are connected to each other, and the passage is opened or closed by opening or closing the valve. The other exhaust valve 38 is located in a passage that connects the control valve outlet 36 (pressure chamber 11 side) and the exhaust outlet 300 (atmosphere side), and opens or closes the valve to connect or disconnect the passage. In addition, not only the anti-skid control function but also the traction control function is added to the brake valve B / V side of the pressure control valve device 30 based on a command from the electronic control unit ECU during traction control. A switching valve device (not shown) for disconnecting 35 from the brake valve B / V and communicating with the air tank will be provided.

When the pressure control valve device 30 is not in operation, the shutoff valve 3
In No. 7, the valve body 37a is separated from the valve seat 37b by the force of the spring 37s due to the demagnetization of the coil, and is in the valve opening position. Further, the other exhaust valve 38 is in the valve closed position because the valve body 38a is seated on the valve seat 38b by the force of the spring 38s due to the coil demagnetization. Therefore, the pressure control valve device 30 has the brake valve B / V-
The pressure chambers 11 are in communication with each other. Under these conditions, the compressed air from the brake valve B / V is transferred to the pressure chamber 11
By supplying / discharging to / from, the brake operation / release is performed by a normal driver's operation. When the external electronic control unit ECU determines that the wheel tends to lock through the wheel speed sensor provided for the wheel, the pressure control valve device 30 operates. First, the electronic control unit section E
The CU issues a brake hold signal. Based on the signal, the shutoff valve 37 is switched to the closed position (the valve body 37a is seated on the valve seat 37b by the coil excitation), and the pressure chamber 11 is shut off from the brake valve B / V. At this time, the exhaust valve 38 is in the closed position. Under these conditions, the air pressure in the pressure chamber 11 is kept constant. Accordingly, the brake hydraulic pressure of the hydraulic cylinder unit 20 is kept constant. Subsequently, the electronic control unit unit ECU issues a brake slack signal. Based on the signal, the exhaust valve 38 is switched to the open position (the valve body 38a is separated from the valve seat 38b by the coil excitation), and the pressure chamber 11 and the exhaust port 300 are communicated with each other. At this time, the shutoff valve 37
Is in the closed position. Under these conditions, the compressed air in the pressure chamber 11 is discharged to the atmosphere through the exhaust valve 38 and the exhaust port 300, and the brake hydraulic pressure in the hydraulic cylinder portion 20 is correspondingly relaxed. Further, those valves are switched by the control of the electronic control unit ECU based on the state of the wheels. In response to the switching, the pressure-holding-releasing of the brake fluid pressure is repeated, and the pressure control valve device 30 performs appropriate brake control.

The pressure control valve device 30 is integrated with the housing 19 of the pneumatic actuator 10. Therefore, the casing 39 of the pressure control valve device 30 includes a mounting portion 31 for integrating the casing 39. The mounting portion 31 is integrally formed with the lid 19a that closes the end of the housing 19 so as to expand to the outside of the housing 19. The housing 19 has an opening at the end of the pressureless chamber 12 side, and the lid 19a closes the opening.

Now, the mounting portion 31 is provided with the exhaust port 300 which is one of the points of the present invention. Exhaust port 3
00 commonly connects the non-pressure chamber 12 of the pneumatic operating unit 10 and the exhaust side (exhaust valve 38) of the pressure control valve device 30 to the atmosphere. For this reason, the mounting portion 31 has the passage 312 that connects the exhaust port 300 and the pressureless chamber 12, and
A passage 338 that connects the exhaust port 300 and the exhaust valve 38 is provided. Exhaust port 300 for mounting part 31
Further, by providing the two passages 312 and 338 communicating therewith, it is possible to reduce the labor of the work at the time of molding the parts and reduce the number of parts of the entire apparatus.

FIG. 3 is a sectional view showing an embodiment of the exhaust port 300 in particular. Inside the exhaust port 300 shown in FIG. 3, a baffle member 360 is located near the opening, and two check valves, a first check valve 370 and a second check valve 380, are located further inward. Is located. The baffle material 360 blocks intrusion of relatively large foreign matter (dust, stones, etc.) from the atmosphere side to the inner side. In addition, the first check valve 370 located inside thereof
Prevents the inflow of air from the atmosphere side to the inward side.
The other second check valve 380 allows only the suction of air from the atmosphere side to the inward side.

The baffle material 360 is provided so as to cover the opening of the exhaust port 300. The baffle material 360 has a plurality of through holes 361 arranged in the circumferential direction, and an umbrella-shaped portion 362 extending inwardly of the through holes 361 so as to cover the through holes 361. First check valve 370 and second check valve 380
The valve holes 371 and 381 are provided on one plate member 378 whose outer peripheral side is inclined downward with respect to the central portion. The valve hole 371 of the first check valve 370 is formed by a plurality of holes arranged in the circumferential direction near the outer periphery of the plate member 378.
On the other hand, there is a rubber plate-shaped valve body 372 which is seated from the atmosphere side. The valve hole 381 of the second check valve 380 is formed of a plurality of holes arranged in the circumferential direction near the center of the plate member 378 on the inner peripheral side of the valve hole 371, and a rubber seated on the inner side of the valve hole 381. There is a plate-shaped valve body 382. Each valve body 3
71 and 381 are supported by retainers 373 and 383. The retainers 373 and 383 limit the opening amount of each valve.

The exhaust port 300 shown in FIG.
Assuming that the air over hydraulic booster 100 is installed at the installation position (the mounting portion 33 of the pressure control valve device 30) shown in FIG. When the pressure control valve device 30 is not operated, the compressed air is supplied to the pressure chamber 11 so that the pneumatic piston 17 slides toward the non-pressure chamber 12 in the normal brake operation state. Along with this, the volume of the pressureless chamber 12 decreases. As the volume of the baffle member 3 is decreased, the air in the pressureless chamber 12 opens the first check valve 370 through the passage 312.
The gas is discharged from the exhaust port 300 to the atmosphere through the holes 60.
In the brake released state thereafter, the compressed air supplied into the pressure chamber 11 is exhausted from the brake valve B / V side, and the pneumatic piston 17 slides toward the pressure chamber 11 side by the urging force of the return spring 18. Along with this, the volume of the pressureless chamber 12 increases. As the volume increases, the atmosphere flows into the pressureless chamber 12 through the passage 312 and the exhaust port 300 while opening the second check valve 380. Thus, in the normal brake operation-release state, air is exhausted through the exhaust port 300 each time the brake operation-release is performed, that is, each time the pneumatic piston 17 slides to both the non-pressure chamber 12 side and the pressure chamber 11 side. It is something that passes through.

When the pressure control valve device 30 is actuated and the exhaust valve 38 is switched to the open position based on the brake slack signal, the compressed air in the pressure chamber 11 is responsive to the switching and the communication line 66 and the exhaust gas are exhausted. It reaches the exhaust side of the pressure control valve device 30 through the valve 38. At this time, the pneumatic piston 17 slides from the non-pressure chamber 12 side to the pressure chamber 11 side. The compressed air that has reached the exhaust side is discharged from the exhaust port 300 to the atmosphere through the through hole 361 of the baffle material 360 while opening the first check valve 370 through the passage 338. At the same time, a part of the compressed air also flows into the pressureless chamber 12 through the passage 312. Generally, the compressed air supplied to the pressure chamber 11 is air dried by an air dryer provided in the brake system. Therefore, when such dry air flows into the pressureless chamber 12, it is possible to remove moisture from the chamber.

Regarding the positional relationship between the first check valve 370 and the second check valve 380, the first check valve 370 of the two is located on the lower side. By doing so, even if water enters the inside through these check valves, the water remains below, so when the air is discharged to the atmosphere, such water and air will be used for the first check. Valve 370
Can be discharged through.

The exhaust port 300 shown in FIG. 1 is different from the one provided with a two-way check valve shown in FIG.
This is a structure in which one of the two-way check valves is not provided. Therefore, the exhaust port 300 shown in FIG. 1 is provided only during normal brake operation, that is, when the pneumatic piston 17 slides toward the non-pressure chamber 12 side.
Air flows between the pressureless chamber 12 and the atmosphere through the exhaust port 300. However, the pneumatic piston 1
If the sliding amount of 7 is large (that is, the amount of volume change of the pressureless chamber is large), the second check valve is required in order to enable normal brake release quickly. Here, the second check valve may be provided at a different position from the exhaust port 300, for example, a communication port for communicating the pressureless chamber 12 with the atmosphere may be prepared, and the second check valve may be provided at the communication port. .

Regarding the installation position of the exhaust port 300,
Instead of the mounting portion 31 of the pressure control valve 30, the pneumatic operating portion 10
The housing 19 may be located on the pressureless chamber 12 side.
That is, the housing 19 is provided with another exhaust port for communicating the pressureless chamber 12 with the atmosphere, and the pressure control valve device 30 is provided.
A passage is provided which connects the exhaust side and the pressureless chamber 12. Of course, a check valve or the like can be provided there. Further, a filter may be provided in place of the check valves in consideration of the intrusion of foreign matter from the atmosphere. Of course, by providing the check valve and the filter twice, it is possible to more reliably prevent foreign matter from entering.

[0026]

According to the present invention, the exhaust side of the pressure control valve device and the non-pressure chamber of the pneumatic operating portion are provided with an exhaust port which communicates with the atmosphere in common. Air passes through the exhaust port according to the volume change of the pressureless chamber due to the sliding of the pneumatic piston each time the normal brake operation is released. Therefore, the frequency of air flow to the exhaust port increases, and the exhaust port can be prevented from being blocked due to freezing or the like. Therefore, the compressed air that has passed through the exhaust port from the pressure control valve device can be reliably exhausted, and proper brake control by the pressure control valve device can be reliably performed.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an air overidroid booster 100 that is an embodiment of the present invention.

2 is a sectional view taken along line 2-2 shown in FIG.

FIG. 3 is a sectional view showing an embodiment of an exhaust port 300 portion.

[Explanation of symbols]

 100 Air Over Hydraulic Booster 10 Pneumatic Actuator 11 Pressure Chamber 12 Non-Pressure Chamber 17 Pneumatic Piston 19 Housing 19a Lid 20 Hydraulic Cylinder 27 Hydraulic Piston 30 Pressure Control Valve Device 31 Attachment 37 Shutoff Valve 38 Exhaust Valve 39 Casing 300 Exhaust port 370 First check valve 380 Second check valve

Claims (9)

[Claims] 1. Compressed air from a brake valve is introduced into a pressure chamber inside a housing, and the introduced compressed air causes
A pneumatic piston that divides the pressure chamber and a non-pressure chamber inside the housing is slid toward the non-pressure chamber side, and is connected so as to interlock with the pneumatic piston as the pneumatic piston slides. The brake fluid pressure is generated by the hydraulic piston, and based on the switching of the pressure control valve device that receives a command from the outside, by connecting the pressure chamber and the exhaust port communicating with the atmosphere, In an air-over-hydraulic booster, in which compressed air introduced into a pressure chamber is exhausted to the atmosphere through the exhaust port, and the pneumatic piston is slid toward the pressure chamber side to loosen the brake fluid pressure accordingly. In the method of preventing freezing of the exhaust port, the pneumatic piston is slid toward at least one of the pressure chamber side and the non-pressure chamber side in response to the pneumatic piston sliding. Chamber and using air flowing between the air, freezing prevention method of the exhaust port in the air-over hydraulic booster which is adapted to contact the air to the exhaust port. 2. The method for preventing freezing of an exhaust port in an air-over-hydraulic booster according to claim 1, wherein the air flowing between the non-pressure chamber and the atmosphere flows through the exhaust port. 3. A pneumatic piston is slidably arranged in a housing to form a pressure chamber into and from which compressed air is supplied and exhausted at one end side of the pneumatic piston, and an atmosphere is provided at the other end side of the pneumatic piston. And a pneumatic piston capable of interlocking with the pneumatic piston, the hydraulic piston being pressed in response to the supply of compressed air to the pressure chamber. By so doing, a hydraulic cylinder unit for generating a brake hydraulic pressure and a pressure control valve device for holding or discharging the air pressure introduced into the pressure chamber to the atmosphere based on a command from the outside are provided. In an air-over-hydraulic booster that is integrated adjacent to the air pressure actuating portion, an exhaust port is provided that connects both the pressureless chamber and the exhaust side of the pressure control valve device to the atmosphere in common. Air over Hydraulic booster. 4. When the pneumatic piston slides to at least one of the pressure chamber side and the non-pressure chamber side, air is passed between the non-pressure chamber and the atmosphere through the exhaust port. The air over hydraulic booster according to claim 3, wherein the fluid flows. 5. The casing of the pressure control valve device is provided with a mounting portion for integration with the housing, and the mounting portion is expanded to the outside of the housing on a wall surface that closes the end portion of the housing. 5. The exhaust port is formed by integrally forming the exhaust port.
Air over hydraulic booster as described. 6. The housing has an opening at an end on the pressureless chamber side in the axial direction of the pneumatic piston body, and a wall surface for closing the end of the housing is attached to the opening. The air-over hydraulic booster according to claim 5, which is a cover body. 7. The air-over-hydraulic booster according to claim 3, wherein the exhaust port is provided with a check valve for blocking the inflow of air from the atmosphere side to the inward side. 8. A second air passage between the pressureless chamber and the atmosphere, which allows only suction of air from the atmosphere into the pressureless chamber in response to movement of the pneumatic piston toward the pressure chamber. 8. The air over hydraulic booster according to claim 7, wherein a check valve is provided. 9. The air-overhydro according to claim 8, wherein the exhaust port is also used as an air suction port from the atmosphere into the non-pressure chamber, and the exhaust port is provided with the second check valve. Rick Booster.