JPS6210864B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a relay valve used in an air brake circuit.

Conventional relay valves reduce the passage area that communicates the output pressure chamber and reaction force chamber formed between the valve disc and output pressure port, and increase the volume of the reaction force chamber to improve the responsiveness of braking action. It was increasing. In other words, when compressed air is continuously supplied from the relay valve to the brake actuator, a large pressure difference occurs between the output pressure port of the relay valve and the brake actuator (for example, when the output pressure port of the relay valve (If the pressure is the same as that of the brake actuator, it is almost atmospheric pressure). The larger this differential pressure is, the faster the pressure rise rate of the brake actuator is. Therefore, in order to increase the brake actuator pressure to the brake instruction pressure in a short time, the pressure at the output pressure port of the relay valve must be instantaneously higher than the desired brake actuator pressure (approximately the air tank pressure). It is desirable that the pressure at the output pressure port of the relay valve also drop to the command pressure when the brake actuator pressure reaches the brake command pressure (solid line A in Figure 1). , see dashed line a). In order for the relay valve to perform such an action, the area of the passage connecting the output pressure chamber and the reaction force chamber is made small, and the pressure chamber should be prevented from being affected by it. However, when the passage area is reduced in this way, the volume of the reaction chamber is reduced by the operation of the pressure-sensitive piston, and the pressure inside the reaction chamber is reduced between the operation of the pressure-sensitive piston and the operation of the valve disk. increases significantly. Therefore, in order to prevent this, the volume of the reaction force chamber must be made sufficiently large.

For these reasons, in conventional relay valves, the diameter of the passage connecting the output chamber and the reaction chamber is 2 mm, whereas the volume of the reaction chamber is about 50 to 100 c.c.

In view of these problems, an object of the present invention is to sufficiently increase the area of the passage communicating the output pressure chamber and the reaction force chamber between the start of the pressure sensitive piston's operation and the time before the start of the valve disk's operation. To provide a relay valve which has a large capacity and is narrowed after the valve disk is operated, thereby reducing the volume of the reaction force chamber without impairing responsiveness, and which is free from the risk of clogging the passage. be.

The present invention will be described below with reference to embodiments shown in the drawings. The relay valve according to the present invention has a supply pressure port 1, an output pressure port 2, an indicated pressure port 3, and an exhaust port 4 formed in the housing 5, and further includes a supply pressure port 1, an output pressure port 2, and an exhaust port 4.
A valve disk 6 is disposed in connection with the indicated pressure port 3, and a pressure sensitive piston 7 is disposed in connection with the indicated pressure port 3. The valve disc 6 is biased upward by a spring 8, and its valve seat 9 abuts against a valve seat 10 formed in the housing 5, closing between the supply pressure port 1 and the output pressure port 2. Output pressure port 2 via exhaust hole 11 penetrated through the center
is communicated with the exhaust port 4. The pressure sensitive piston 7 has an indicated pressure chamber 12 communicating with the indicated pressure port 3 on its upper surface, a reaction force chamber 13 on its lower surface, and an extension member 14 protruding from the center of its lower surface.
The exhaust hole 11 of the valve disc 6 is located at the lower end of the member.
A valve seat 15 is formed for closing the valve. This pressure-sensitive piston 7 is urged upward by a spring 16 mounted in a reaction force chamber 13, and under normal conditions maintains its valve seat 15 at an appropriate distance α from the valve seat 9 of the valve disk 6. There is.

In such a relay valve, the present invention crosses the sliding surface between the reaction force sensitive piston 7 and the housing 5 of the relay valve to form a passage 18 that communicates the output pressure port 2 and the reaction force chamber 13 with each other. However, the passage 18 on the sliding surface is gradually closed by the sliding surface of the housing 5 as the pressure sensitive piston 7 descends.

In the embodiment shown in FIG. 2, the passage 18 is provided through the extension member 14 of the pressure-sensitive piston 7, and the opening 19 on the side of the reaction force chamber 13 is opened in response to the actuation of the pressure-sensitive piston 7 to form a guiding annular shape for the piston. It is narrowed down by a wall 20. This passage 18 is maintained in the most constricted state while the lower end valve seat 15 of the pressure-sensitive piston 7 contacts the valve disc 6 and further presses down the valve disc, as shown in FIGS. 3 and 4.
As shown in the figure, a groove 21 is formed in the upper part of the opening 19 on the side of the reaction force chamber 13.

The relay valve according to the present invention operates as follows.
By operating a brake valve (not shown), compressed air corresponding to the amount of pedal depression is supplied to the command pressure chamber 12 via the command pressure port 3 of the relay valve.
The compressed air supplied to the indication pressure chamber 12 acts on the upper surface of the pressure-sensitive piston 7, causing the piston to be moved by the spring 16.
Press down against the When the pressure sensitive piston 7 descends, its lower end valve portion 15 comes into contact with the valve seat 9 of the valve disk 6, the exhaust hole 11 is closed by the lower end valve seat 15 of the pressure sensitive piston 7, and the output pressure port 2 ( The output pressure chamber 17) and the exhaust port 4 are closed. During this time, the passage 18 communicating the reaction force chamber 13 and the output pressure chamber 17 is gradually narrowed as shown in FIG. When the pressure-sensitive piston 7 further descends, the valve disk 6 is pressed down by the valve seat 15 of the piston, and its valve seat 9 is pushed down into the housing 5.
The supply pressure port 1 and the output pressure port 2 are communicated with each other by being separated from the valve seat 10 of the valve seat 10 . When supply pressure port 1 and output pressure port 2 communicate with each other in this way, the air reservoir (not shown) that was supplied to supply pressure port 1
Compressed air is delivered to the output pressure chamber 17 and further delivered to the brake actuator (not shown) via the output pressure port 2. During this time, the passage 18 communicating the reaction force chamber 13 and the output pressure chamber 17 is maintained in its most constricted state (see FIG. 4). In this way, the relay valve according to the present invention obtains the pressure characteristics shown by the solid line A and the broken line a shown in FIG.

FIG. 5 shows another embodiment of the relay valve according to the present invention, in which the extension member 14 of the pressure-sensitive piston 7 is guided through a passage 18 that communicates the reaction force chamber 13 and the output pressure chamber 17. The passage 18 is narrowed by the extension member 14, and the passage 18 is finally closed to separate the reaction force chamber 13 and the output pressure chamber 17 only by the orifice passage 18'. I'm trying to communicate.

As is clear from the above explanation, the passage 18 communicating the reaction force chamber 13 and the output pressure chamber 17
, sufficient ventilation is ensured between the reaction force chamber 13 and the output pressure chamber 17 until the lower end valve seat 15 of the pressure sensitive piston 7 comes into contact with the valve seat 9 of the valve disk 6, and the valve disk 6 is activated. While compressed air is being fed to the output pressure chamber 17, the passage 18 may be throttled to prevent the influence of the pressure increase in the output pressure chamber 17 from affecting the reaction force chamber 13, and is limited to the embodiment. Various embodiments may be adopted within the scope of the claims.

As described above, the relay valve according to the present invention can obtain ideal output characteristics regardless of the volume of the reaction force chamber, and therefore can provide a compact relay valve with excellent responsiveness.

[Brief explanation of the drawing]

Figure 1 shows the pressure characteristics when the passage connecting the reaction force chamber and the output pressure chamber in a conventional relay valve is narrowed and widened, and the solid line A shows the output when the passage is narrowed. The broken line a shows the brake pressure characteristics, the solid line B shows the output pressure characteristics when the passage is made thicker, and the broken line b shows the brake pressure characteristics. FIG. 2 is a longitudinal cross-sectional view of a relay valve according to the present invention, FIGS. 3 and 4 are cross-sectional views of main parts showing the passageway in its operating state, and FIG. 5 is a main part showing another embodiment. FIG. 1... Supply pressure port, 2... Output pressure port, 3
...Indication pressure port, 4...Exhaust port, 6...Valve disk, 7...Pressure sensitive piston, 11
... Exhaust hole, 13 ... Reaction force chamber, 17 ... Output pressure chamber, 18 ... Passage.

Claims (1)

[Claims] 1 In the normal state, the supply pressure port and the output pressure port are closed, and the output pressure port and the exhaust hole are in communication, and in the operating state, the output pressure port and the exhaust hole are closed, and the supply pressure port and the output a valve disk communicating with the pressure port;
A pressure-sensitive piston, which has an indicated pressure chamber formed on its upper surface and a reaction force chamber formed on its lower surface, and which descends in response to indicated pressure from compressed air fed to said indicated pressure chamber to operate said valve disk. In the relay valve, a passage is formed that crosses the sliding surface of the pressure sensitive piston and the housing of the relay valve to communicate the output pressure port and the reaction force chamber with each other, and The relay valve is characterized in that the passageway in the surface is gradually closed by the outer circumferential surface of the pressure-sensitive piston or the sliding surface of the housing as the pressure-sensitive piston descends.