Check valve for a compressor

Abstract

 A compressed gas is introduced from a compressor into an inlet 2aa of a check valve 1 and discharged through an outlet 3a from the check valve 1. A ball valve 5 is disposed on a valve receiver 6 between the inlet 2aa and the outlet 3a in the check valve 1. The ball valve 5 is more strongly pressed onto the valve receiver 6 in an upstream side than in a down-stream side to prevent back flow of the gas.

Description

BACKGROUND OF THE INVENTION

[0001] The present invention relates to a check valve for a compressor and particularly to a check valve connected to an outlet of a compressor to prevent back flow of a compressed gas.

[0002] JP6-83975U discloses that a check valve for a compressor comprises a tubular casing having an inlet connected to an outlet of the compressor and an outlet for discharging compressed gas; a ball valve in the tubular casing to open a flow path for the inlet by moving away from a valve-seating surface in the tubular casing and to shut the flow path for the inlet by contacting the valve-seating surface; and a valve receiver in the tubular casing to control opening between the ball valve and the valve-seating surface when the ball valve moves away from the valve-seating surface.

[0003] However, in the check valve, the ball valve is provided in the tubular casing freely. Thus, compressed gas which flows from the inlet to the outlet with operation of the compressor makes the ball valve vibrated, which results in contact with the valve receiver and its surroundings to generate chattering sound.

SUMMARY OF THE INVENTION

[0004] In view of the disadvantage in the prior art, it is an object of the invention to provide a check valve for a compressor to prevent a ball valve from vibrating in a tubular casing even if vibration is generated owing to compressed gas flow in the tubular casing.

[0005] According to the present invention, there is provided a check valve for a compressor, comprising a tubular casing that comprises an inlet connected to an outlet of a compressor and an outlet for discharging a compressed gas introduced from the inlet, a ball valve which moves away from a valve-seating surface of the tubular casing to allow the compressed gas to flow from the inlet to the outlet or which contacts the valve-seating surface to prevent the compressed gas from flowing back from the outlet to the inlet, and a valve receiver limiting opening between the ball valve and the valve-seating surface, characterized by comprising different-pressure creating means making pressure acting onto a downstream-side outer circumferential surface of the ball valve lower than what acts onto an upstream-side outer circumferential surface of the ball valve to press the ball valve onto a seat of the valve receiver.

BRIEF DESCRIPTION OF THE DRAWINGS

[0006] 

Fig. 1 is a partially-sectioned exploded perspective view of the first embodiment of a check valve according to the present invention.

Fig. 2 is a vertical sectional view of the assembled check valve in Fig. 1.

Fig. 3 is partially-sectioned exploded perspective view of the second embodiment of a check valve according to the present invention.

Fig. 4 is a vertical sectional view of the assembled check valve in Fig. 3.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0007] Figs. 1 and 2 show the first embodiment of the present invention. A check valve 1 comprises a tubular casing 4 comprising an upper tubular entrance casing 2 having an inlet 2a connected to an outlet of a compressor (not shown) via a conduit, and a lower tubular exit casing 3 having an outlet 3a connected to a compressed air storage tank via a conduit; a ball valve 5 disposed freely in the tubular casing 4; and a circular valve receiver 6 provided between the upper and lower casings 2 and 3.

[0008] At the lower end, the upper casing 2 has a flange 2b which contacts a flange 3b at the upper end of the lower casing 3. The flanges 2b and 3b are coupled to each other with a plurality of screws 7. An O-ring 8 is held between the flanges 2b and 3b to provide air tightness between the casings 2 and 3.

[0009] In the vicinity of an introducing portion 2a of the upper casing 2, a tapered valve-seating surface 2c is formed. If compressed air flows back from a discharge portion 3a to the introducing portion 2a, the ball valve 5 will fit in the valve-seating surface 2c to shut a flow path to the introducing portion 2a, preventing air from flowing back.

[0010] At the center of a seat 6a of the valve receiver 6, a through hole 6b is formed. The through hole 6b allows the intake path 2a to communicate with the discharge path 3a. The ball valve 5 is disposed on the seat 6a to shut the through hole 6b.

[0011] A plurality of throttle paths 6c are formed around the through hole 6b of the seat 6a of the valve receiver 6. When compressed air flows from the intake path 2a to the discharge path 3a over the ball valve 5, the throttle paths 6c allows the compressed air to be throttled so that pressure in the discharge path 3a becomes lower than that in the intake path 2a. In the first embodiment, the through hole 6b and the throttle paths 6c constitute different-pressure creating means.

[0012] When compressed air is introduced into the intake path 2a by the compressor, the ball valve 5 is put on the seat 6a of the valve receiver 6 to close the through hole 6b. Compressed air flows from the intake path 2a to the discharge path 3a over the ball valve 5 and through the throttle paths 6c.

[0013] When compressed air flows through the throttle paths 6c, it is choked to increase flow speed to make pressure in a downstream side lower than that in an upstream side. Accordingly, lower pressure directly acts onto a downstream outer circumferential surface or a lower half of the ball valve 5 through the through hole 6b than what acts onto an upstream outer circumferential surface or an upper half of the ball valve 5 in Fig. 2.

[0014] Thus, the ball valve 5 is sucked into the through hole 6b of the seat 6a of the valve receiver 6 to press the seat 6a. Even if vibration occurs with flowing of compressed gas in the tubular casing 4, the ball valve 5 is sucked onto the seat 6a and held thereon, so that chattering will be prevented. The through hole 6b is formed in the middle of the seat 6a of the valve receiver 6 and the throttle paths 6c are formed around the through hole 6b through the seat 6a, so that the ball valve 5a can be surely disposed in the middle of the seat 5a.

[0015] Figs. 3 and 4 show the second embodiment of the present invention. The second embodiment is different only in a valve receiver from the first embodiment, and the same numerals are allotted to the same members as those in the first embodiment. Only differences will be described with different numerals.

[0016] A valve receiver 10 comprises a seat 10a which a ball valve 5 can contact; a cylindrical portion 10b which projects toward an upstream side or an inlet 2aa and has an inner circumferential surface slightly larger than a diameter of the ball valve 5 to receive the ball valve 5; and a plurality of gas-flow through holes 10c to allow compressed gas to flow from the inlet 2aa to an outlet 3a.

[0017] A throttle path 11 is formed between the inner circumferential surface of the cylindrical portion 10b and the outer circumferential surface of the ball valve 5 in the cylindrical portion 10b. Compressed air flows through the throttle path 11 from the intake path 2a to a discharge path 3a to make pressure acting onto the downstream-side outer circumferential surface lower than what acts onto the upstream-side outer circumferential surface of the ball valve 5. In the second embodiment, the cylindrical portion 10b and the throttle path 11 constitute different-pressure acting means.

[0018] Compressed air introduced through the intake path 2a passes through the throttle path 11 between the ball valve 5 and the inner circumferential surface of the cylindrical portion 10b of the valve receiver 10, and flows through the gas-flowing through holes 10c to the discharge path 3a. Thus, compressed air is throttled through the throttle path 11 to make pressure acting onto the downstream-side outer circumferential surface lower than what acts onto the upstream-side outer circumferential surface. The ball valve 5 is pressed onto the seat 10a of the valve receiver 10 and held thereon. Even if vibration occurs owing to compressed gas flow, the ball valve 5 will be still held on the seat 6a of the valve receiver 6, so that chattering cannot sound. A plurality of gas-flowing through holes 10c are formed on the outer circumference of the seat 10a, the ball valve 10a is held surely in the middle of the seat 10a.

[0019] In the embodiment, the middle of the seat 10a of the valve receiver 10 is flat, but a recess may be formed on the seat 10a to fit in the outer surface the ball valve 5.

Claims

1. A check valve for a compressor, comprising a tubular casing (4) that comprises an inlet (2a) connected to an outlet of a compressor and an outlet (3a) for discharging a compressed gas introduced from the inlet (2a), a ball valve (5) which moves away from a valve-seating surface (2c) of the tubular casing (4) to allow the compressed gas to flow from the inlet (2a) to the outlet (3a) or which contacts the valve-seating surface (2c) to prevent the compressed gas from flowing back from the outlet (3a) to the inlet (2a), and a valve receiver (6,10) limiting opening between the ball valve (5) and the valve-seating surface (2c), characterized by comprising:

different-pressure creating means making pressure acting onto a downstream-side outer circumferential surface of the ball valve (5) lower than what acts onto an upstream-side outer circumferential surface of the ball valve to press the ball valve (5) onto a seat (6a,10a) of the valve receiver (6,10).

2. A check valve as claimed in claim 1 wherein the different-pressure creating means comprises a through hole (6b) in the middle of the seat (6a) to allow the through hole (6b) to receive the ball valve (5); and a throttle hole (6c) through the seat (6a) around the through hole (6b).

3. A check valve as claimed in claim 1 wherein the different-pressure creating means comprises a cylindrical portion (10b) projecting from the seat (10a) toward the inlet (2a) and having an inner circumferential surface slightly larger than a diameter of the ball valve (5); and a throttle path (11) between the inner circumferential surface of the cylindrical portion (10b) and the ball valve (5).

Drawing