US2945486A - Sealing and valving means for use in air guns - Google Patents

Description

C. N. WEBBY July 19, 1960 SEALING AND VALVTNG MEANS FOR USE IN AIR GUNS 2 Sheets-Sheet 1 Filed Sept. 16, 1957 INVENTOR CLIVE NELSON WEBBY ATTOR N EYS c. N. WEBBY 2,945,486

July 19, 1960 SEALING AND VALVING MEANS FOR USE IN AIR GUNS 2 Sheets-Sheet 2 Filed Sept. 16, 1957 INVENTOR CLIVE NELSON WEBBY ATTORNEYS WW/W SEALING AND VALVIN G MEANS FOR USE IN AIR GUNS Clive Nelson Webby, Riverlea, Taranaki, New Zealand Filed Sept. 16, 1957, Ser. No. 684,243 Claims priority, application New Zealand Sept. 19, 1956 '5 Claims. (Cl. 12'4-'11) This invention relates to sealing and valving means for use in air guns, and refers more particularly to an air gun including a storage chamber for gas under pressure and also including means for valving the gas under pressure to a barrel for expelling a shot therefrom.

An object of this invention is to provide an improved sealing and valving means for use in an air gun whereby an increased safety margin in the use of an air gun is attained, and hold-ups brought about by dust and grit are largely avoided, and wherein the said means is easily assembled and readily removed as may be required.

Another object of this invention is to provide an improved sealing and valving means for an air gun which permits the escape of air trapped between said means and. theinner wall of the storage chamber of the air gun to provide an improved seal between said sealing and valving means and said storage chamber wall.

A further object of this invention is to provide an improved sealing and valving means for use in an air gun wherein the known difiiculty associated with heavy valve actuating springs used therein is avoided, and to render the improved sealing and valving means suitable for use in conjunction with light springs and with gas under high pressure.

A still further object is to provide an improved sealing and valving means for use in an air gun in which there is a sealing means which is arranged so that its wear is reduced to a minimum during the operation of the air Another object of this invention is to provide an improved sealing and valving means for use in an air gun in which there is an initial light seal and such construction permits the use of a light spring in the operationof a releasing means and a seal is maintained over the escape line along the releasing means.

According to this invention, the improved sealing and valving means for use in an air gun is accommodated in a storage chamber and in an inner end of the chamber, and a resilient cup is spring pressed to form an initial light seal and a releasing means is movable inan end of the storage chamber to break a seal and to valve gas from the storage chamber to a barrel while permitting entrapped gas between the cup and the inner surface of the chamber to escape to atmosphere and to ensure the cup forms a seal on the inner surface of the chamber as required during the operation of the air gun.

The invention will now be described with reference to the accompanying drawings in which: a

Figure 1 is a general view of the air gun,

Figure 2 is a partly broken elevation on an enlarged scale showing the valving and sealing means in the fully efiective sealed position,

Figure 3 is a view similar to Figure 2 showing the valving and sealing means in the unsealed position,

Figure 4 is an elevation of the sealing cup,

Figure 5 is an end view of Figure 4, and

ing the attachment to the rear and forward members.

States Patent 0.

1 2,945,486 Patented July 19, 1960 In the form of the invention operable with gas under a pressure in the vicinity of 1500 lbs. per square inch, there is provided in an air gun generally indicated at 1, Figure l, a cylindrical casing 1a, a storage chamber 2 for gas under pressure with a sealing .and valving means in the casing-1a, more particularly in an inner end of the storage chamber 2 (see Figures 2 and 3) whereby gas under pressure is supplied or valved to a barrel 3*arranged in parallelism with the cylindrical casing 1a on movement of a releasing piston 4 as required to expel a shot 5 from the-barrel 3.

As shown in Figures 2 and 3 the sealing and valving means has a removable body 7 which is cylindrical in form and is held in a corresponding cylindrical inner end of the storage chamber 2 in the casing 1a by removable pins 8 inserted through the wall of the casing 1a and engaging in the removable body 7 whereby the body 7 can be removed from the casing 1a when the removable pins 8 are withdrawn.

Referring to Figures 2 and 3 the removable body '7 has a bore 9 and a passage 10 from the bore 9 leads to a port 11 in the Wall of the chamber 2 and to a corresponding port 12 in the wall of the barrel 3 so that gas under pressure, permitted to enter the bore 9 of the body 7, is led to the barrel 3 to expel a shot 5 from the latter during the operation or firing of the gun 1. The bore 9 of i to assist in sealing the body 7 in the end of-the storage chamber 2 in the cylindrical casing 1a when the gun is discharged. I

'I'he bore 9 ofthe body 7 has a releasable piston 4 operable inwards, that is, away from the storage chamber 2, and along the bore 9 whereby gas under pressure is valved to the bore 9, then to the annular indentation or groove 13 and to and through the passageltl and to the barrel 3 of the gun 1 during the operation of, the gun 1; or the releasable piston '4 is operable outwards, that is towards the storage chamber 2 and along the bore 9 to close the passage 10 and to close the outer end of the bore .9 of the removable body 7 to seal ofi the gas under pressure in the storage chamber 2.

The releasable piston 4 has a head 4a which in a desired form has a coned or domed formation which in its inner position forms a seal with conical surface 7a of body 7 and projects beyond the inner end of the removable body 7 (see Figure 2), but at all times the greatest circumferential or peripheral edge of the piston 4 is Within the inner end of the body 7. By such arrangement of parts a resilient cup 15 placed over the inner end of the body 7 seals off the inner end of, the body 7 and the piston 4 in its sealed position as shown in Figure 2. Y

Further, as shown in Figure 2, the resilient cup is accommodated in the storage chamber 2, and the cup 15 is spring pressed towards the inner end of the body 7 and on to the head 4a of the releasable piston 4 in the latters initially sealed position. The cup 15 comprises a body portion with a base 16 (see Figure 4) abutting against the inner end of the removable body 7 and on the piston 4 in the body 7, an axial orifice 17 through the body portion, and the orifice 1'7 merging'into a. bell mouth 18 with lips 19 (see Figures 4 and 5) adjacent the inner surface of the storage chamber 2, and there is an annular groove 20 in the outer surface of the body portion. The orifice17 of the resilient cup 15 is of a smaller diameter than the bore 9 of the releasable piston 4, and in a sense the cup 15 is movable and floating in the storage chamber 2. The resilient cup 15 may be made of a rubber composition which may be reinforced or progressively hardened from the lips 19 to the base 16.

The orifice 17 of the resilient and centrally situated cup 15 has aninnerprojection or shoulder 21 (See Figure 4) extending in from the body portion and such inner projection or shoulder 21 may be arranged to engage the end of a compression spring 22 which may be situated between such inner projection or shoulder 21 and the opposed end of the storage chamber 2. But in the preferred form of the invention as shown in Figures 2 and 3, the resilient cup 15 has a venturi 24 situated centrally therein and such venturi 24 is formed to .sit on theinner shoulder 21 of the resilient cup '15 with a narrow end 25 of the venturi 24 directed towards a recess 4b in the head 4a of the releasing piston 4. In this, form ofthe invention the venturi 24 is formed with an inner shoulder or step 24a which receives an end of the compression spring 22 in the storage chamber 2 The venturi 24 may be vulcanized to the cup 15 when the gun is operated under high pressures of gas.

Preferably the narrow end 25 of the venturi 24 terminates with its orifice in the recess 4b so that gas under pressure is directed to the bore 9 of the body 7 and along the passage 10 of the body 7 when the releasing piston 4 is withdrawn to uncover the passage 10, and the gas under pressure is directed in a stream which has the minimum detrimental effect on the base 16 of the resilient cup 15.

Also withdrawing the releasing piston 4 to uncover the passage 10 to the barrel 3, with the venturi 24 directed towards the annular groove 13 .and the passage 10 in the body 7, ensures the release of gas with velocity and high pressure to the barrel 3 for expelling a shot 5 from the barrel 3.

By such arrangement, the resilient cup 15 is spring loaded and influenced and urged towards the inner end of the releasable piston 4, and also further urged by mount,- ing gas pressure against the inner end of the removable body 7, and in so doing the cup 15 expands in effecting sealing between the cup 15 and the casing 141, and then the cup 15 when relieved of gas under pressure contracts in effecting unsealing and in so doing may be deemed to be floating.

The gas under pressure in the storage chamber 2 exerts a pressure on the bell mouth 18 of the resilient cnp 15, and the lips 19 of the bell mouth 18 are forced on to the inner surface of the storage chamber 2, thereby maintaining a thrust against the wall of the storage chamber 2. The maintenance of such thrust of the bell mouth 18 and lips 19 of the resilient cup 15 against the wall of the storage chamber 2, is assisted by the annular groove 20 in the outer surface of the body portion of the resilient cup 15 having communication to atmosphere through a hole 23 in the wall of the storage cham her 2. By such arrangement of the annular groove 20 on the outer surface of the body portion of the cup 15, and the hole 23 in the wall of the storage/chamber 2, gas between the surfaces of theresilient cup 15 and the storage chamber 2 can escape to atmosphere, and the cup 15 is assured of being maintained against the inner wall of the storage chamber 2, and forming a seal thereon, more particularly as the storage chamber 2 is relieved of gas under pressure. a

Thus, by this invention, a storage chamber 2 in the cylindrical casing 1a of an air gun 1 is provided with a sealing and valving means wherein a releasable piston 4 in a removable body 7 is reciprocal in a bore 9, so that the head 4a of the releasable piston 4 is moved away from a resilient cup 15 on the bore 9 thereof, to uncover and .to valve gas under pressure from the storage chamber 2 through the bell mouth 18 of the resilient cup 15, through the orifice 17 of the resilient cup.15, and into the bore 9 and annular groove 13 in the removable body expelling a shot 5 from the barrel 3; and at the same time, the gas under pressure in the storage chamber 2 thrusts the lips 19 of the bell mouth 18 on to the wall of the storage chamber 2 to effect and maintain a seal between the outer wall of the cup 15 and the inner wall of the storage chamber 2, for which purpose an annular groove 20 in the body of the resilient cup 15 is open to atmosphere through the wall of the storage chamber 2.

Then on a forward reciprocation of the releasable piston 4 in the removable body 7, the piston head 4a closes over the annular groove 13 in the removable body 7, and the piston head 4a abutts against surface 7a of member 7 and projects forwardly into the orifice 17 of the resilient cup 15 to form a double seal. Then in a buildup of pressure in chamber 2 the surface of the base 16 of the resilient cup 15 is urged by its spring 22 and the gas under pressure in the storage chamber 2 to form a seal on the inner face or surface of the removable body 7 and over .the junction of the bore 9 of the removable body 7 with the releasable piston 4, to form a seal over part of the head 4a of the releasable piston 4 and the inner face or surface of the removale body 7, but in so doing, the forward projection of the head 4a of the releasable piston 4 does not have its greatest circumference or periphery projecting beyond the inner face or surface of the removable body 7, but rather the greatest circumference or peripheral surface of the releasable piston 4 is within the bore 9 of the removable body'7 whereby a portion of surface 4a engages surface 7a.to provide the double seal, and at the same time to ensure that .the resilient cup 15, particularly the base 16 thereof, is not subjected to more than ordinary wear and tear during the operation of the sealing and valving means.

By such arrangement the gas under pressure trapped between the resilient cup 15 and the walls of chamber 2 tends to escape through the hole 23 to atmosphere through V the wall of the storage chamber 2 beyond the resilient 7, and through. the passage 10 of the removable body 7 cup 15 during build-up of pressure in chamber 2, and this arrangement for the escape of gas from between the cup 15 and the wall of chamber 2, provides a more efficient seal between theresilient cup 15 and the walls of chamher 2 during the expulsion of a shot 5 from the barrel 3 since no high pressure gas will exist between the chamber contacting walls of resilient cup 15 and the walls of chamber 2 at this time.

In a form of the invention operable with gas under pressures'in the vicinity of 3,000 to 4,500 lbs. per square inch, the releasing means includes a releasing piston 4 which has a recessed inner end or head 4a, and the surface 7a of the member 7 makes an initial seal on the domed or sloping inner surface of the end or head 4a of the releasing piston 4 as the piston 4 is moved forward into the position shown in Figure 2. Also by such arrangement an initial seal is formed by the sloping surface of the inner end of the head 4:: of the releasing piston 4 as the piston 4 is moved in against the spring 22 to bear upon and move the resilient cup 15 away from the inner end of the body 7; and as the gas under pressure is increased in the storage chamber 2, slidable cup 15 is moved toward 7 and a more effective seal is made between the resilient cup 15 and the wall of the cylindrical casing 1a and also between the resilient cup 15 and the end of the body 7 and the inner end or head of the releasing piston 4. Hence such effective seal is made as the resilient cup 15 is forced towards the body 7 and the cup 15 is forced over and on to the escape lines of gas under pressure between the surface of the releasing piston 4 and the central bore 9 of the body 7; and also sealing the junction between the wall of the storage chamber 2 and the adjacent end of the removable body 7.

The trip link'mechanism as shown in Figures 2, 3 and 6 has a trigger 26 pivotally attached to the cylindrical ing 14 s ihe ai gen 1 nd e gge 26 i p in loaded and influence-d preferably forwardly by a light cocking spring 27. An arcuate slot 28 is provided in a trip link 29 pivotally connected to trigger 26 and a pin 30 arranged for engagement in and with the slot 28 is fixed in a bifurcated lower portion of a composite bell crank lever 31 which is pivoted in a slot 32 of a rear member 33 and the bell crank lever 31 has another pin 34 pivoted to a forward bifurcated link 35 which is also pivoted in a slot 36 of a forward member 37. (See Figures 2, 3 and 6).

By such arrangement, operation of the trigger 26 overcomes an initial pressure as the trip link 29 moves rearwardly with its slot 28 moving along the pin 30 against the influence of the cocking spring 27, and the further operation of the trigger 26 with the pin 30 in the front end of the slot 28 pivots the bell crank lever 31 about its pivot pin 38 downwardly from the slot 32 in its slotted rear member 33 and by its pin 34 pivots the composite link 35 about its pin 39 downwardly from its slot 36 in the forward member 37 to draw the forward member 37 away from the releasable piston 4 to unseal the cup and to permit gas under pressure to pass to the barrel 3 to fire the air gun 1. The arcuate slot 28 allows the pin 30 of the bell crank lever 31 to run freely in opening the valve during the firing of the air gun 1.

In this arrangement, the link 29, bell crank lever 31 and link 35 are not subjected to the influence or tension of the spring 27 but during the operation of the gun, the influence or tension of the spring 27 is taken by an operators finger on the trigger 26.

The reverse movement influenced by the spring 27 pivots the bell crank lever 31 and link 35 to a position where their pivot points 38, 34 and 39 are in alignment and kept from pivoting further up and out of alignment by a stop 31a, and at the same time the forward member 37 is moved forward to push the releasable piston 4 to its initial sealing position with the cup 15 and surface 7a as shown in Figure 2.

The rear end of the casing 1a has an internal screw thread to take a screw threaded plug 40 which maintains the link mechanism in the rear end of the casing 1a, and the plug 40 has a recess to receive an extension or projection 33a of the rear member 33 which is held by a pin 41 so that the link mechanism is adjustably held by the plug 40 which can be turned on its screw threads to take up or allow for wear in the link mechanism as well as maintaining the link mechanism in the rear of the casing 1a.

What I do claim and desire to obtain by Letters Patent of the United States of America is:

1. In an air gun, a cylindrical casing a portion of which is enclosed to form a storage chamber for gas under pressure, a gas discharge passage in communication with said storage chamber having side walls converging toward said storage chamber, a resilient cup slidably positioned within said storage chamber including a bottom adjacent one end of said gas discharge passage and side walls in contact with the walls of said storage chamber, an axial orifice through said bottom of said cup in line with and of slightly less diameter than said passage, a releasable piston positioned within said casing including an end having surfaces converging axially outwardly thereof, said end projecting into said storage chamber through said passage, said converging end surfaces of said piston contacting said converging walls of said passage to form a first seal to prevent the escape of gas from said chamber through said passage and resilient means within said storage chamber for biasing said cup into contact with said end of said piston within said chamber around the periphcry of said orifice to form a second seal to prevent the escape of gas through said passage.

2. The structure as set forth in claim 1 wherein the side walls of said resilient cup are progressively harder toward the bottom of said cup whereby the portions of the side walls of said cup further away from the bottom thereof form a positive seal with the walls of said chamber before the harder portions thereof on an increase of pressure within said chamber to provide a progressively larger and more effective seal between said resilient cup and said chamber walls as pressure is increased within said chamber.

3. The structure as set forth in claim 2 including an annular groove around the outer circumference of said resilient cup adjacent the bottom thereof and a gas escape port extending through said casing in registration with said groove to provide escape means for gas trapped between the bottom and adjacent side walls of said cup and (the walls of said casing on an increase of pressure within said chamber due to said progressively larger and more effective seal between said resilient cup and said chamber walls.

4. The structure as set forth in claim 1 wherein said releasable piston is operable by trip-link mechanism comprising a trigger pivotally attached to the casing of the gun, a light cocking spring attached to the trigger for biasing the trigger into a cocked position, a trip-link pivotally secured to said trigger at one end and having an arcuate slot in the other end, a bell crank lever including a bifurcated lower portion, a pin mounted across said bifurcated lower portion and passing through said slot in said trip-link, a rear member positioned in the rear end of said casing and having a slot therein in which said bell crank lever is pivotally secured, a forward member positioned in said casing in axial spaced relation to said rear member and in contact with said releasable piston having a slot therein, a forward bifurcated link pivotally mounted in said slot in said forward member, said forward bifurcated link and said bell crank lever being pivotally connected, whereby pivoting of the trigger in opposition to said cocking spring moves the trip-link rearwardly with its arcuate slot moving along said pin across the bifurcated lower portion of the bell crank lever and further pivoting of the trigger after said pin has reached the forward end of said arcuate slot pivots the bell crank lever downwardly from the slot in the rear member causing similar downward pivoting of said forward bifurcated link and therefore movement of said forward member away from said releasable piston to allow rearward movement of said piston due to gas under pressure within said chamber to unseal the resilient cup and permit escape of gas under pressure in said pressure chamber through said passage, said pin across the bifurcated portion of said bell crank lever running freely along said arcuate slot during rearward movement of said piston.

5. The structure as set forth in claim 4 including an adjustable plug in the rear end of said casing in contact with said rear member operable to adjust the position of said rear member longitudinally of said casing to compensate for wear of said trip-link mechanism.

References Cited in the file of this patent UNITED STATES PATENTS 504,820 Thacher et a1. Sept. 12, 1893 843,573 Blomen et al Feb. 12, 1907 1,292,665 Udesen Jan. 28, 1919 2,273,678 Webby Feb. 17, 1942 2,299,073 Beasley Oct. 20, 1942

Images