WO1998023911A1

WO1998023911A1 - Gas supply regulator for an air gun

Info

Publication number: WO1998023911A1
Application number: PCT/GB1997/003256
Authority: WO
Inventors: John Bowkett; Simon Jeremy Gilbert
Original assignee: Bsa Guns (Uk) Limited
Priority date: 1996-11-27
Filing date: 1997-11-27
Publication date: 1998-06-04
Also published as: GB2324138B; GB9815523D0; GB9624602D0; GB2324139B; GB9815521D0; DE19781542T1; DE19781545T1; DE19781544T1; GB9815519D0; GB2324139A; GB2324138A; GB2324137B; WO1998023909A1; WO1998023910A1; GB2324137A

Abstract

A charging valve for the pressure regulator of a pneumatic-type air gun comprises a closure element (50) in the form of a steel ball which is arranged to become accommodated within an elastomeric O-ring (48) to close the valve. The ball is of slightly greater diameter than the internal diameter of the O-ring, whereby a seal is created between the ball and an interior external surface of the O-ring at its inner circumference. A piston-operated plunger (60) in a gas outlet passage (44) pushes the ball through the O-ring in order to open the valve, the ball being received into a bore (56) of a bushing (54) which contains a retaining spring (58) to limit movement of the ball away from the O-ring.

Description

GAS SUPPLY REGULATOR FOR AN AIR GUN

Air guns of pneumatic type are known which are arranged to take a supply of pressurised gas, for operation of the gun, from a pressurised gas bottle.

In order that successive shots from the gun may be fired by means of measured doses of gas at uniform pressure, rather than at successively lower pressures as the pressure in the supply bottle drops, it is known to provide a pressure regulator within the gun which serves automatically to measure out uniform doses of gas, regardless of the bottle pressure.

Such regulators occasionally malfunction in operation, particularly for example from dirt impeding the proper operation of valving, and ordinarily the consequence of this is that for proper attention the gun must be returned to the manufacturer or a servicing agent for repair. This necessarily means that there is some delay before the gun can be returned to the owner in working condition.

It is one of the objects of this invention to provide a pressure regulator of improved reliability for an air gun.

In one of its aspects the invention provides a regulator device for an air gun, the device comprising a charging valve whereby gas can be admitted to a dosing chamber of the device from a pressurised gas supply and a discharge valve whereby a charge of gas in the dosing chamber can be released from the chamber for operation of the gun, the charging valve comprising a closure element which in order to close the valve is arranged to become introduced within a seating formed by an interior external surface at the inner circumference of an annular sealing element of elastomeric material, the closure element being of slightly greater diameter than the inner circumference of the sealing element so as to enter the sealing element with some compression of the sealing element whereby a seal is created between the closure element and the sealing element at its inner circumference.

The sealing element may, conveniently, comprise an O-ring which forms the seating. The closure element may be in the form of a ball of slightly larger diameter than the internal diameter of the O-ring, and may be of steel or any other suitable material.

The position of the closure element relative to the seating may be under the control of an operating stem which projects generally axially through the annular sealing element to engage the closure element, the closure element being held displaced axially from the seating in an advanced position of the stem.

The sealing element may be held in a ring-retaining chamber formed at the bottom of a well by a tubular bushing introduced into the well, the closure element being freely accommodated within a bore in the bushing when the valve is fully open. A retaining spring may be provided within the bore to limit movement of the closure element away from the sealing element.

There now follows a description, to be read with reference to the accompanying drawings, of a regulator device which illustrates the invention by way of example.

In the accompanying drawings: Figure 1 is an axial cross-section through a regulator unit for an air gun;

Figure 2 shows a similar charging valve that that shown in the regulator in Figure 1 but on a larger scale and with the valve closed.

A regulator unit for fitment in an air gun comprises a tubular body 10 which is divided into supply and dosing chambers 12 and 14, respectively, by means of a first valve block 16. Two O-ring seals 15, 17 seal around the block between the block and the body.

An inlet end 18 of the body 10, leading into the supply chamber 12, is open for the supply of gas at high pressure from a gas bottle or other pressurised reservoir. A charging valve 20 is arranged within the valve block 16 to control the passage of gas from the supply chamber 12, the gas passing through the valve block and into the dosing chamber 14.

An outlet end 22 of the regulator body 10 is closed off by a second valve block 24. An O-ring seal 26 seals around the block between the block and the body. A discharge valve 28 of the regulator is arranged within the second valve block to control the release of gas from the dosing chamber 14, the gas passing through the valve block to a discharge port 30 for operation of the gun.

The regulator operates automatically to maintain a gas pressure of around 1000 p.s.i. (6.895 xlO³ kPa) in the dosing chamber 14 between operations of the gun, there so being a uniform charge of compressed gas available for every shot fired. This is achieved by means of a regulating piston 32 which is housed to move within a cylinder 34 positioned within the dosing chamber 14 between the two valve blocks 16,24. The piston 32 is urged by means of a driving spring 36 towards an open end 38 of the cylinder positioned within the first valve block 16, the piston so being urged axially towards the charging valve 20. O-rings 40 seal between the piston 32 and the cylinder wall. An operating mandrel 42 of the charging valve is housed in an axial through-passage 44 of the valve block and abuts an end face 33 of the piston 32, being movable axially in the passage (as permitted by the piston) for operation of the charging valve, as hereinafter described. In Figure 1 the arrangement is shown with the piston fully displaced by the spring 36, abutting an end face 46 of the valve block around an entry to the passage 44, and the mandrel correspondingly fully advanced towards the charging valve to maintain the valve fully open.

The charging valve 20 comprises an annular valve seating formed by an interior external surface at the inner circumference of an O-ring 48 of an elastomeric material, and a closure element formed by a steel ball 50. The ball is of slightly greater diameter than the internal diameter of the O-ring so that a good seal is formed between the ball and the ring upon the ball being pressed firmly into the ring (Figure 2) to compress the material of the ring at its inner circumference. The ring surrounds an entry of the through-passage 44 into the bottom of a well 52 formed in the valve block 16, the well opening into the supply chamber 12. A tubular bushing 54 lines the well, being slightly shorter than the well in depth in order to define a ring-retaining chamber at the bottom of the well. The ball 50 is freely accommodated (when the valve is open) within a central bore 56 of the bushing in which there is a retaining spring 58 to limit possible movement of the ball through the bushing away from the sealing ring. When the valve is fully open, an operating stem 60 of the operating mandrel 42 projects axially through the O-ring 48 (from the through- passage 44) to hold the ball 50 displaced from the O-ring and into the bushing 54.

Surrounding the entry to the well 52, an externally-threaded cup 62 is screwed into an internally-threaded portion of the regulator body 10, so covering the bushing 54 and the entry to the well 52. As an integral part projecting axially from the base of the cup, a fixed stump 64 projects, within the supply chamber 12, axially away from the charging valve 20 and towards the inlet end 18 of the regulator body. The stump is provided for the purposes of displacing (and so opening) a sealing valve (not shown) of a gas bottle when the bottle is affixed to the regulator for use.

No seal is created between the screw-threaded cup 62 and the regulator body 10. On the contrary, the interengaged screw threads provide a throttling passageway enabling gas to flow in a controlled manner through the supply chamber 12 and into the tubular bushing 54 within the well 52 of the valve block 16. With the charging valve 20 held open, the gas passes through the O-ring seating 48 and into the through- passage 44, there being a clearance around the mandrel 42 which permits the gas to pass. Clearances between the regulating cylinder 34 and the valve housing 16 permit the gas to pass into the dosing chamber 14.

So long as the discharge valve 28 is maintained closed, the pressure in the dosing chamber can be built up. Upon a predetermined pressure being attained, depression of the regulating piston commences, the pressure at which this occurs being determined by the strength of the piston-supporting spring 36. As the piston so becomes moved inwardly of the cylinder 34, in the direction away from the charging valve 20, the valve-operating mandrel 42 is correspondingly permitted to become moved in the direction away from the valve until, finally, the valve ball 50 becomes seated within the sealing O-ring 48 (Figure 2) and air flow between the supply and dosing chambers becomes stopped. At this stage the pressure in the dosing chamber 14 is 1000 p.s.i. (6.895 x 10³ kPa) , whereas the pressure in the supply chamber 12 may be in excess of 3000 p.s.i. (20.69 x 10³ kPa) . The regulator is now charged and ready for the gun to be fired.

The discharge valve 28 comprises a closure element in the form of a cylindrical body 66 of a hard plastics material which presents a circular edge seal against a frusto-conical seating surface 68 within the second valve block 24. The cylindrical body extends axially of a broad entry portion 70 of a passageway which passes through the block, the convergent seating surface 68 connecting the entry portion 70 with a narrower intermediate portion 72. The discharge port 30 is in communication with the intermediate portion.

The closure body 66 is urged against the seating 68 by means of a return spring 74 acting between the body and an adjacent end face of the regulating cylinder 34, being located on a nose 73 projecting axially from the cylinder end.

A push rod 76, for operation of the discharge valve, extends from the closure body 66 and through the valve body 24 to provide a projecting portion 78 outside the body. An inner end portion 80 of the push rod is secured within a recess in the closure body; the rod extends from there through the intermediate portion 72 of the valve body passageway, through a constriction 82 formed by the body, and through an outer portion 84. The outer portion 84 of the passageway accommodates a tubular bush 86, an O-ring 88 being seated between the end of the bush and the constriction 82 in order to form a seal between the push rod 76 and the valve body at that point.

The push rod is a loose fit within the bush 86 and passes through the constriction 82 with some clearance. Consequently the push rod is not held closely except by the O-ring seal 88 adjacent to the constriction 82, and accordingly the push rod can pivot slightly, at the O-ring, in planes perpendicular to the O-ring. In this manner, the closure body 66 on the inner end portion 80 of the push rod is free to move radially to a small degree for self-centring against the conical seating surface 68.

In operation of the gun, the projecting end portion 78 of the push rod is depressed by an actuating element of a trigger mechanism (not shown) to displace the valve closure body 66 from the seating surface 68, so causing the compressed gas within the dosing chamber 14 to be released to the discharge port 30.

Immediately after firing the gun, release of the push rod 76 permits the discharge valve to close under the action of residual pressure and the return spring 74. Upon the depressurisation of the dosing chamber the regulating piston 32 advances under the action of the driving spring 36 to advance the mandrel 42 and open the charging valve 20, and accordingly the chamber becomes replenished from the supply chamber 12.

Claims

1. A regulator device for an air gun, the device comprising a charging valve whereby gas can be admitted to a dosing chamber of the device from a pressurised gas supply and a discharge valve whereby a charge of gas in the dosing chamber can be released from the chamber for operation of the gun, the charging valve comprising a closure element which in order to close the valve is arranged to become introduced within a seating formed by an interior external surface at the inner circumference of an annular sealing element of elastomeric material, the closure element being of slightly greater diameter than the inner circumference of the sealing element so as to enter the sealing element with some compression of the sealing element whereby a seal is created between the closure element and the sealing element at its inner circumference.

2. A regulator device according to claim 1 in which the sealing element is an O-ring.

3. A regulator device according to clam 1 in which the closure element is in the form of a ball.

4. A regulator device according to any one of claims 1 to 3 in which the position of the closure element relative to the seating is under the control of an operating stem which projects generally axially through the sealing element to engage the closure element, the closure element being held displaced axially from the seating in an advanced position of the stem.

5. A regulator device according to any one of claims 1 to 4 in which the sealing element is retained in the bottom of a well by means of a tubular bushing, the closure element being freely accommodated within a bore of the bushing when the valve is fully open.

6. A regulator device according to claim 5 in which a retaining spring is arranged to limit the possible movement of the closure element in the direction away from the sealing element.

7. In a regulator device for an air gun, a charging valve substantially as hereinbefore described with reference to the accompanying drawings.

8. An air gun comprising a regulator device according to any one of claims 1 to 7.