JP2811159B2 - Air over hydraulic booster - Google Patents

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 a vehicle such as a truck or a bus and having a brake control function such as anti-skid control or traction control.

[0002]

BACKGROUND OF THE INVENTION Generally, an air-over-hydraulic booster includes a pneumatic operating section that operates by pneumatic pressure from a brake valve, and a hydraulic cylinder that generates brake hydraulic pressure. One pneumatic operating portion has a pneumatic piston that forms a pressure chamber and a non-pressure chamber in its housing. The other hydraulic cylinder has a hydraulic piston that can be linked with the pneumatic piston. The air overhydraulic booster converts air pressure into liquid pressure. That is, when the compressed air is supplied to the pressure chamber, the pneumatic piston slides toward the non-pressure chamber in accordance with the supply of the compressed air, and the hydraulic piston slides accordingly to generate brake hydraulic pressure. As means for adding a brake control function to such an air-over-hydraulic booster, there is a means for controlling the pressure at the pneumatic stage or a means for controlling the pressure at the hydraulic stage.
Among them, the means for controlling the air pressure requires relatively light equipment, and is preferable from the viewpoint of mountability and the like. An aspect of the present invention relates to an air overhydraulic booster that performs brake control by controlling the air pressure.

As means for controlling the air pressure, for example,
As disclosed in Japanese Patent Laid-Open Publication No. Hei 3-167061, there is a device having a pressure control valve device for holding compressed air supplied to a pressure chamber or discharging the compressed air to the atmosphere. The pressure control valve device includes two valves therein, a shutoff valve and an exhaust valve. The shutoff valve communicates the brake valve with the pressure chamber when in the open position, and keeps the air pressure in the pressure chamber constant by being switched to the closed position. When the exhaust valve is switched to the valve-open position, the exhaust valve communicates with the pressure chamber and releases the air pressure in the pressure chamber. Opening / holding / relaxing of the brake fluid pressure is repeated by opening and closing these valves to perform appropriate brake control. The above-mentioned publication discloses a technique for integrating a pressure control valve device with a housing of a pneumatic operating portion. According to this technique, the transmission loss of the compressed air pressure due to the long pipe is eliminated, and the brake control based on the switching of the pressure control valve device is performed (hereinafter, simply referred to as “brake control”).
This is based on the switching of the pressure control valve device.) In this case, the pneumatic piston can be slid swiftly in response to the fluctuation of the pneumatic pressure in the pressure chamber, thereby improving the responsiveness.

[0004]

Generally, a pneumatic piston has an axial length shorter than its diameter in order to effectively convert pneumatic pressure into hydraulic pressure. Further, the pneumatic piston is provided with a sealing member on the outer periphery thereof for blocking the pressure chamber from the non-pressure chamber, and the pneumatic piston resiliently contacts the inner periphery of the housing with the sealing member. It is designed to be guided and supported through the horn. For this reason, when the pneumatic piston slides in response to the fluctuation of the air pressure in the pressure chamber, the pneumatic piston easily falls down with respect to the housing. The resistance increases. In that respect, in particular, during the brake control, the air pressure fluctuation in the pressure chamber is repeated in a short cycle, so that the falling of the pneumatic piston is a factor that hinders the agile sliding of the piston itself. . Further, as described above, in the case where the pressure control valve device is integrated with the pneumatic operation section, the pneumatic pressure in the pressure chamber fluctuates sharply during the brake control because the transmission loss of the compressed air is eliminated. As a result, the pneumatic piston is more likely to fall down. This is because the steep air pressure fluctuation in the pressure chamber exerts the acting force to move the pneumatic piston more agilely, but gives the uneven or uneven acting force that causes the pneumatic piston to fall down. It is because. Therefore, if the pressure control valve device is simply integrated into the pneumatic actuator, the pneumatic piston will fall down, and the pneumatic piston cannot slide smoothly and more agilely during brake control. Even if it tries to improve the performance, a sufficient effect cannot be expected.

[0005] On the other hand, the above-mentioned tilting of the pneumatic piston causes the joint between the pneumatic piston and the hydraulic piston to have a structure in which the two parts do not support each other (for example, Japanese Utility Model Publication No. 4-11895). In the publications of US Pat. According to such a structure, the pneumatic piston cannot be guided sufficiently. The guiding of the pneumatic piston can be carried out indirectly by supporting itself with the hydraulic piston and guiding the hydraulic piston. However, if they are structured so that they can be separated from each other without guiding and supporting each other, at the time of assembling, each of the pneumatic operating section and the hydraulic cylinder section are individually assembled, and the two are assembled together. Just fit them. Therefore, simplification of the assembling work can be achieved, which is preferable.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above, and an object of the present invention is to prevent a pneumatic piston from falling down during sliding and to guide the pneumatic piston effectively so that compressed air is supplied to a pressure chamber. It is an object of the present invention to provide a technology that enables a pneumatic piston to slide smoothly in response to supply and discharge of brake fluid, and that can appropriately control brake fluid pressure.

[0007]

As a means for solving the above-mentioned problems, the present invention provides a low-pressure piston which extends in the sliding direction on the outer periphery of the pneumatic piston and always slides on the inner periphery of the housing of the pneumatic operating portion. A frictional guide is provided. According to the configuration provided with the guide portion, even if the air pressure in the pressure chamber fluctuates in a short cycle based on the switching to the pressure control valve device during the brake control, the pneumatic piston is prevented from falling over the housing by the guide portion. In addition, the sliding is guided while the sliding resistance is suppressed as small as possible. Therefore, the pneumatic piston slides smoothly and swiftly according to the pneumatic fluctuation in the pressure chamber. This is the same even when the responsiveness is enhanced by integration with the pressure control valve device. Even in that case, the pneumatic piston can slide smoothly without falling down.

The guide portion is similarly located adjacent to a sealing member provided on the outer periphery of the pneumatic piston, but the positional relationship between the two is that the guide portion is located closer to the non-pressure chamber. Is preferred. According to such a structure, in particular, when the pneumatic piston slides from a state of being completely urged toward the pressure chamber, the pneumatic piston at this time can be guided more effectively. The pneumatic piston urged toward the pressure chamber mainly includes a contact portion between the pressure chamber side end of the pneumatic piston and the inner wall of the housing and a contact portion between a guide portion on the outer periphery thereof and the inner periphery of the housing. Supported. By arranging the contact portions of these two parts further apart, the pneumatic piston in that state can be more sufficiently supported, and the pneumatic piston that slides from that state can be more effectively guided. .

[0009]

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

The pneumatic operating section 10 has a slidable pneumatic piston 17 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 / discharging the compressed air from / V and a non-pressure chamber 12 at the other end are formed. The pressure receiving portion 17b has a U-shaped cross section opened to the non-pressure chamber 12 side, and includes a sealing member 13 on its outer periphery for blocking the pressure chamber 11 from the non-pressure chamber 12. The non-pressure chamber 12 has a return spring 18 for urging the pneumatic piston 17 toward the pressure chamber 11, and the pressure receiving portion 17 b also has a function of receiving the return spring 18. On the wall surface of the housing 19 on the pressure chamber 11 side,
An air inlet 16 is provided. Compressed air from the brake valve is introduced into the pressure chamber 11 through the air inlet 16. With the introduction, the pneumatic piston 17 slides toward the non-pressure chamber 12 against the urging force of the return spring 18. The other end of the non-pressure chamber 12 of the housing 19 is provided with an overstroke sensor 50 for detecting a sliding limit of the pneumatic piston 17.

The hydraulic cylinder section 20 is located on the non-pressure chamber 12 side of the pneumatic operation section 10. Hydraulic cylinder section 20
Has a hydraulic piston 27 therein. The hydraulic piston 27 is connected to the pneumatic piston 17 so as to be interlocked therewith.
When the compressed air is supplied to the pressure chamber 11, the pneumatic piston 17 slides accordingly, and the hydraulic piston 2
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 section 10 and the hydraulic cylinder section 20 in FIG. FIG. 2 is an enlarged view of a section 2-2 of the pressure control valve device 30 shown in FIG. The pressure control valve device 30 includes a brake valve B
/ V and the pneumatic actuator 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 section 10, and an exhaust port 34 communicating with the atmosphere are formed. Have. In particular, the control valve outlet 36 and the pressure chamber 11 (air inlet 16)
Are connected via a communication pipe 66.

Inside the pressure control valve device 30, there are two valves, a shutoff valve 37 for controlling pneumatic pressure and an exhaust valve 38. These valves are both 2-port, 2-position solenoid valves. The shutoff valve 37 is located in a passage connecting the control valve inlet 35 (brake valve B / V side) and the control valve outlet 36 (pressure chamber 11 side), and opens or closes the valve to communicate or shut off the passage. The other exhaust valve 38 is connected to the control valve outlet 36.
It is located in a passage connecting the (pressure chamber 11 side) and the exhaust port 34 (atmosphere side), and opens or closes a valve to open or close the passage. In addition, in addition to the anti-skid control function as well as the traction control function,
On 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 that disconnects the control valve inlet 35 from the brake valve B / V and communicates with the air tank ( (Not shown).

When the pressure control valve device 30 is not operated, the shut-off valve 3
Numeral 7 indicates that the valve element 37a is separated from the valve seat 37b by the force of the spring 37s due to the coil degaussing and is in the valve-open position, and the other exhaust valve 38 has the valve element 38a caused by the coil 38a It is seated on the valve seat 38b and is in the valve closed position. Therefore, the pressure control valve device 30 is provided with the brake valve B / V-
The pressure chambers 11 are in communication. Under these conditions, compressed air from the brake valve B / V is supplied to the pressure chamber 11.
Supply / discharge, and brake operation-release by a normal driver's operation is performed. When the external electromagnetic control unit ECU determines that the wheels have a tendency to lock via a wheel speed sensor provided for the wheels, the pressure control valve device 30 operates. First, when the electromagnetic control unit ECU issues a brake holding signal, the shutoff valve 37 is switched to the valve closing position (the valve body 37a is seated on the valve seat 37b by the coil demagnetization) based on the signal, and the pressure chamber 11 is moved to the brake valve. B / V
Shield from At this time, the exhaust valve 38 is at the valve closing position.
Under these conditions, the air pressure in the pressure chamber 11 is kept constant, and the brake fluid pressure in the hydraulic cylinder 20 is kept constant accordingly. Next, the electromagnetic control unit ECU
Generates a brake release signal, the exhaust valve 38 is switched to the open position (the valve body 38a is separated from the valve seat 38b by coil degaussing) based on the signal, and communication between the pressure chamber 11 and the exhaust port 34 is established. I do. At this time, the shutoff valve 37 is at the valve closing position. Under such a state, the compressed air in the pressure chamber 11 is exhausted to the atmosphere through the exhaust valve 38 and the exhaust port 34, and the brake hydraulic pressure of the hydraulic cylinder 20 is accordingly relaxed. Further, these valves are switched by the control of the electromagnetic control unit ECU based on the state of the wheels. The pressure control valve device 30 performs appropriate brake control by repeating the filling, holding, and release of the brake fluid pressure in accordance with such switching.

The pressure control valve device 30 is integrated with the housing 19 of the pneumatic actuator 10. By integrating, the transmission loss due to the long piping is eliminated, and the pneumatic piston 17 against the pneumatic fluctuation of the pressure chamber 11 during the brake control.
And the response of the brake fluid pressure control can be enhanced. Therefore, the casing 39 of the pressure control valve device 30 includes a mounting portion 31 for integration thereof. The mounting portion 31 is formed integrally with the lid 19 a that closes the end of the housing 19. The housing 19 has an opening at the end of the non-pressure chamber 12 side, and the lid 19a closes the opening. Such a mounting portion 31 includes a communication passage 33 that communicates the non-pressure chamber 12 and the inside of the exhaust port 34.
As a result, the air flows through the exhaust port 34 as the pneumatic piston 17 slides, so that freezing due to snow or the like can be prevented.

The connecting portion between the pneumatic piston 17 and the hydraulic piston 27 is formed by fitting the convex portion 15 on the pneumatic piston 17 side and the concave portion 25 on the hydraulic piston 27 side. The protrusion 15 is located at the other end of the rod 17a. The recess 25 is located at one end of the hydraulic piston 27. Such a coupling portion is a simple one in which the projections 15 and the depressions 25 abut each other, and is not a coupling in which they support each other. Thus, the assembling work is simplified.

Now, the pressure receiving portion 17b of the pneumatic piston 17
Is provided with a guide portion 14 having low friction on its outer periphery. The guide part 14 is provided on the inner periphery 1 of the housing 19 of the pneumatic operating part 10.
The pneumatic piston 17 is guided by constantly sliding on 9c. The guide portion 14 is made of a low-friction resin material (for example, Teflon or the like), and has a ring shape.
Such a guide portion 14 is mounted in a groove portion 17c extending around the outer circumference of the pressure receiving portion 17b. The guide part 14 has its annular part cut off, and when it is installed in the groove 17c, the cut part is expanded and installed.

The guide portion 14 is adjacent to the sealing member 13 located on the outer periphery of the same pressure receiving portion 17b. Regarding the positional relationship between the two, the guide portion 14 is located closer to the non-pressure chamber 12 side. In the normal brake release state, the pneumatic piston 17 is in a position where it is completely urged toward the pressure chamber 11 by the action of the return spring 18. At this time, the pressure receiving section 17
The plurality of projections 17d provided on the b contact the inner end wall 19e of the housing 19, and the pneumatic piston 17 is positioned. When compressed air is supplied to the pressure chamber 11 in this state,
The pneumatic piston 17 is momentarily urged toward the non-pressure chamber 12 side. At this time, the guide portion 14 is located closer to the non-pressure chamber 12, that is, the protrusion 17d and the guide portion 1
4 is located farther away, the pneumatic piston 17 can be guided and supported more effectively. When the pneumatic piston 17 slides inside the housing 19, the guide section 14 guides the pneumatic piston 17. By extending the guide portion 14 in the sliding direction, the guiding effect can be further improved. Further, since the guide portion 14 is made of a low-friction material, the sliding resistance of the pneumatic piston 17 with respect to the housing 19 can be reduced even if the guide length of the pneumatic piston 17 is increased. The fact that the sliding resistance is small depends on the change in air pressure of the pressure chamber 11.
This is effective in quickly moving the pneumatic piston 17.

It is to be noted that the guide portion 14 may be, for example, a rotatable ball material or a roller material. However, in consideration of, for example, damage to the inner circumference 19c of the housing 19, it is preferable that the housing 19 be formed of an annular resin material that is in surface contact with the inner circumference 19c and does not damage the partner.

[0020]

According to the present invention, the pneumatic piston is provided with a low-friction guide portion which is always in sliding contact with the inner periphery of the housing, so that the sliding pneumatic piston is more effectively guided, and the It is possible to effectively prevent the pressure piston from falling down. Further, even when the responsiveness of the pneumatic piston is improved by integrating the pneumatic operating section and the pressure control valve device, the pneumatic piston does not fall. Therefore,
The pneumatic piston can slide smoothly, and the brake hydraulic pressure can be controlled properly.

[Brief description of the drawings]

FIG. 1 is a sectional view of an air over hydraulic booster 100 according to an embodiment of the present invention.

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

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Pneumatic operation part 11 Pressure chamber 12 Non-pressure chamber 13 Sealing member 14 Guide part 17 Pneumatic piston 17a Rod part 19 Housing 20 Hydraulic cylinder part 27 Hydraulic piston 30 Pressure control valve device 100 Air over hydraulic booster

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B60T 13/40

Claims (4)

(57) [Claims] 1. A pneumatic piston is slidably disposed in a housing, a sealing member in contact with the inner periphery of the housing is mounted on the outer periphery of the pneumatic piston, and compressed air is supplied to one end of the pneumatic piston. Forming a pressure chamber to be exhausted, a pneumatic operating portion having a non-pressure chamber connected to the atmosphere at the other end of the pneumatic piston, and a hydraulic piston capable of interlocking with the pneumatic piston, When the hydraulic piston is pressed in response to the introduction of the compressed air into the pressure chamber, a hydraulic cylinder section that generates brake hydraulic pressure, and an air pressure introduced into the pressure chamber based on an external command. A pressure control valve device for holding or discharging to the atmosphere, wherein the pressure control valve device is integrated with the housing of the pneumatic operating section. An air-over-hydraulic booster provided with a low-friction guide portion extending in the movement direction and constantly sliding on the inner periphery of the housing. 2. The air overhydraulic booster according to claim 1, wherein said guide portion is formed of an annular member made of a low friction resin material and mounted on an outer periphery of said pneumatic piston. 3. The pneumatic piston according to claim 1, wherein the guide portion and the sealing member are adjacent to an outer periphery of the pneumatic piston, and the guide portion is located closer to the non-pressure chamber. Air over hydraulic booster. 4. A rod portion extending from the pneumatic piston toward the hydraulic piston is provided so as not to be guided and supported on the hydraulic piston side portion and to be detachable from the hydraulic piston. The air-over-hydraulic booster according to claim 1, wherein: