US2945487A

US2945487A - Air guns

Info

Publication number: US2945487A
Application number: US684242A
Authority: US
Inventors: Webby Clive Nelson
Original assignee: Individual
Current assignee: Individual
Priority date: 1956-09-19
Filing date: 1957-09-16
Publication date: 1960-07-19
Anticipated expiration: 1977-07-19

Description

July 19, 1960 C. N. WEBBY AIR GUNS 2 Sheets-Sheet 1 Filed Sept. 16, 1957 INVENTOR OLIVE NELSON WEBBY BY mwa/za .ATTORN EYS C. N. WEBBY July 19, 1960 AIR GUNS Filed Sept. 16, 1957 2 Sheets-Sheet 2 hom o OE

INVENTOR CLIVE NELSON WEBBY B M W ATTORNEYS United States Patent AIR GUNS Clive Nelson Webby, Riverlea, Taranaki, New Zealand Filed Sept. 16, 1957, Ser. No. 684,242

Claims priority,-application New Zealand Sept. 19, 1956 Claims. (Cl. 12'4 -1s This invention relates to air guns and more particularly the invention has reference to air guns which are operated by agas under pressure.

Prior to this invention, it has been known to-operate air guns for the expelling of a shot from a barrel, by means incorporated in the gun for compressing a spring which on release of the spring engages or is cushioned by gas to move a shot and to expel the latter through the barrel of the gun.

Further, it has been known in air guns to provide hingeable means for operating a pump for pressing gas into storage, and to provide means for the release of gas under pressure to expel a shot through the barrel of the gun.

Further also, it-has been known, in air guns, to provide a cartridge of compressed gas and to release part of the stored gas to expel a shot through the barrel of the gun.

It is an object of this present invention to provide improvementsin an air gun including means for creating and for storing gas under pressure, said air gun including means for release of such gas or part thereof to expel a shot through a barrel of a gun.

The object of this present invention is to provide an improved means for pumping gas under pressure into a storage chamber, such pumping means being easily operated, convenient to the user or operator in holding the gun, and moreover a pumping means which requires little effort to gain the desired storage of gas for moving a shot through the barrel of the gun and expelling the shot therefrom, on release of some of the compressed gas or all of the compressed gas from the storage chamber for this purpose. A stillfurther object of -this.inventi0n is to provide an improved means for the compressing ofgas or for the storing of gas in an, air gun, such means being not only simple to operate, but also durable in operation in that pumping is effected without the contacting and consequent wearing of the metal moving parts of a pump with other .metal parts of a pump so that grit and other extraneous between such parts is. reduced to a minimum.

A further object of this invention is to provide in an air gun a construction which overcomesknowndifliculties associated with aligning or self, centering a piston rod ina cylindrical-casing when 0 ringsand the like are used on a rod of smalldiameter as in previous constructions; in this invention, a. resiliency in an inner piston head enables an inner endof the piston rod to align or self centre in the casing. 7

According to this invention, the improvements to an air gun comprises a cylindrical; casing, which is closed at its outer endand open at its inner end, andwhich is situated. alongside and parallelingthe barrel of the gun and held in associationtherewith, a storage chamber for gas. under pressure arranged. at the open inner end of the cylindrical casing, a piston rod reciprocal in the cylin- H drical casing, which isarranged to provide. a low pressure chamber in its outer portion, the piston rod having an ice outer piston head whereby reciprocation of the piston rod draws'gas into the low pressure chamber and further reciprocation of the piston rod forces the gas past a low pressure non-return valve and along the interior of the piston rod to an inner piston head on the inner end of the piston rod, and such inner piston head is made of a durable flexible material with an inner high pressure check valve therein, and the inner piston head has a formed end which is slidably engaged on a valve head of a nonreturn valve of the storage chamber, so that gas is'led through the inner piston head past its inner high pressure check valve and then past an inner non-return valve into the storage chamber.

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

Figure l is a general view of the air gun,

Figure 2 is an enlarged sectional view (partly broken) of the outer end of the cylindrical casing with the piston rod near the inner end of its stroke, and p Figure 3 is a continuation of Figure 2 showing the inner end of the cylindrical casing, while Figure 4 is a view similar to Figure 2 showing the piston rod near the outer end of its stroke, and

Figure 5 is a continuation of Figure 4,

Figure 6 is 'a front view (further enlarged) of an O-ring, and

Figure 7 is a sectional view of Figure 6,

Figure 8 is an enlarged front view pressure check valve, While Figure 9 is a sectional view of Figure '8,

Figure 10 is a view (on a smaller scale), of'the complete piston rod,

Figure 11 is an enlarged front view of another form of high pressure check valve, while v Figure 12 is a sectional view of Figure-11', and

Figure-13 is an enlarged sectional view of the inner piston head and high pressure check valve.

In this invention, an air gun generally indicated at 1 has a cylindrical casing 1a which is provided with a longitudinal slot 2 through which a hand .piece 3 is arranged to reciprocate along the exterior of the cylindrical casing 1a and the hand piece 3 has a protuberance 4 passing through-the slot land the protuberance 4 engages in asmall slot 5 near the central part 6 of the piston rod 7 within the casing 1a so that on moving the hand piece 3 reciprocally out and back along the cylindrical casing: in, the piston rod 7 is moved within the interior of the cylindrical casing 1a (see Figures 1,2 and 3).

As shown in Figure 2, the cylindrical casing is pro,- vided with an outer plug 8 which can be removed for placing the piston rod 7 in the cylindrical casing 1a and then the plug 8 is screwed on again to seal' the outer end of the casing 1a. Situated in the casing 1a and adjacent the outer plug 8 is a buffer pad 9 which is formed with an end having an interior taper 9a, and a relief or bleed hole 10 is made through the buffer pad 9.

In Figures 2 and 3, the piston rod 7 is illustrated near the inner end of its stroke and the piston rod' 7 according to this invention (see Figures 2' and 3) is elongated and arranged with a central small bore 11 for the passage of gas therethrough. On the outer end of the piston rod 7, near the outer plug -8 and facing the buffer pad 9, is an outer piston head 12 formed on the outer-end of the piston rod. 7, and such outer piston head 12 ist-apered to fit into the interior, tapered end 9aof the buffer pad 9. A low pressure chamber 13 is formed between such outer end of the casing in with its buffer pad9 and the outer tapered head 12 of the piston rod 7. A low pressure non-return valve 14 is situated within the entrance of the:bore 1 1 of the piston rod 7 and, the valve 14 is retained within the outer taperedport'ion of the piston head: 12 by.;a tapered screw threaded plug 14a (see Figures 2 and 4) of one form of high The outer face 17 of the O-ring 16 i.e.

tions or studs on and projecting out from such outer face 17, so that gas can be drawn into the low pressure chamber 13 round and past the O-ring 16 whereas, gas from the low pressure chamber 13 can not in reverse, pass the O-ring 16 as the latter seals against the interior of the casing 1a and by its unbroken other face of the O-ring 16 against the inner part of the annular groove 15 (see Figures 6 and 7). Thus outward reciprocation of the piston rod 7 and its outer head 12 confines gas in the low pressure chamber 13 and the gas is forced past the low pressure non-return valve 14 in the entrance of the bore 11 of the piston rod 7; and gas passes along the bore 11 towards the storage chamber as shown more particularly in Figure 4.

Further in from its annular groove 15, the piston rod 7 has a sleeve 19 preferably of a rubber composition formed with longitudinal ridges 20 which run along and bear upon, the interior of the casing 1a, and the ridges 20 permit gas 'to pass lengthwise along the sleeve 19 to the outer tapered head of the piston 12 and to the low pressure chamber 13 (see Figures 2 and 4).

As shown in Figures 2, 3, 4 and 5, behind and further in from the outer tapered piston head 12 and back in from the sleeve 19, the piston rod 7 is decreased in diameter and is bound round with an exteriorly and helically arranged oiling wick 21 such oiling wick 21 extending from the outer tapered piston head 12 to the central part 6 of the piston rod 7.

The central part 6 of the piston rod 7 is enlarged in diameter and is formed with a small slot made longitudinally of the piston rod 7, and such small slot 5 is ar ranged and situated to provide for engagement of the protuberance 4 on the hand piece 3 whereby the piston rod 7 can be reciprocated in the casing 1a. For this latter purpose the casing 1a is provided in its central portion with the corresponding but longer longitudinal slot 2 to permit the protuberance 4 to project through and reciprocate along the longer longitudinal slot 2 (see Figures 2, 3, 4, 5 and As illustrated in Figures 3 and 5, commencing from the enlarged central part 6 of the piston rod 7 and continuing to the inner end of the piston rod 7, this inner part 24 of the piston rod 7 is decreased in diameter again and bound *round exteriorly and helically with a further oiling wick 25 which has a smaller diameter than the first-mentioned oiling wick 21. Such further oiling wick 25 is arranged to strengthen and to guide the inner part 24 of the piston valve 27 of a storage chamber 28 is arranged to operate against the inner end of such reduced inner portion 1b. beyond the reduced inner portion 1b, the cylindrical casmg 1a extends with its normal bore towards, and terminating near, the inner end of a barrel (not shown) of i the gun 1, that is the casing 1a continues beyond the nonreturn valve 27 to provide a passage from and alongside the non-return valve 27 to the storage chamber 28 (see Figures 3 and 5).

As shown in Figures 3 and 5, the inner end of the piston rod 7 is formed to receive and to hold an inner piston head 31 which is an essential part of this invention.

As shown in Figures 3 and 5, and more particularly in Figure 13, in order to receive and to hold the inner piston head 31 on the inner end portion 7b of the piston rod 7, such inner end portion 7b has its exterior surface formed with an annular groove 32, and the inner piston head 31 has a skirt 33 which is a firm push fit over the inner end portion 7b, and the skirt 33 is stretchable over said inner end portion 7b until an interiorly raised portion 34 of the skirt 33 fits into and holds in the annular groove 32, to ensure the gripping of the skirt 33 on the inner end portion 7b of the piston rod 7, so as to prevent loss of low ressure gas andto prevent buckling and distortion of the skirt 33 by frictional contact.

The inner piston head 31 is made of a rubber composition and one which is of a material which do% not deteriorate in the presence of oil, and which does not seize on the interior wall of the cylindrical casing 1a, and the rubber composition may be reinforced or progressively hardened from a bell mouth 35 to the skirt 33.

The outer end of the skirt 33 of the inner piston head 31 is flared in the form of a bell mouth as an oil scraper ring to restore oil.

The inner piston head 31 has a tapered hole 36 which tapers and splays towards the non-return valve 27 of the storage chamber 28, so that the inner piston head 31 is provided with flexible lips. The inner piston head 31 has a denser body portion than the flexible lips of the inner piston head 31, and the flexible lips can be flexed under the pressure of gas being pumped to seal off an escape line for the compressed gas (see Figure 13).

The outer end of the inner piston head 31 situated about the inner end portion 7b of the piston rod 7 is in the form of a skirt 33 or annular wall which serves as a guide on the reduced portion 1b of the cylindrical casing 1a to prevent whipping of the inner reduced portion 24 of the piston rod 7 as well as for holding the inner piston head 31 on the inner end 7b of the piston rod 7 by engaging in the annular groove 32 in the inner end of the piston rod 7b as outlined above, and as illustrated in Figures 3, 5 and 13.

As shown in Figures 3, 5 and 13, behind the denser body portion of the inner piston head 31 there is provided a high pressure valve chamber 37, and the high pressure valve chamber 37 is open to a passage 38 through the denser body portion leading to the tapered hole 36. Such high pressure valve chamber 37 in one form as illustrated is made between the surface of the denser body portion and the inner end 7b of the piston rod 7; and the inner end 7b of the piston rod 7 is hollowed or cut out concentrically of the bore 11 of the piston rod 7 so that the high pressure valve chamber 37 is a recess in the inner end 7b of the piston rod 7.

The arrangement of the piston rod 7 is such that the inner end of the bore 11 of the piston rod 7 terminates in the high pressure valve chamber 37 (see Figures 3, 5 and 13).

A check valve 39 suitable for gas under pressure is situated in the high pressure valve chamber 37 and such check valve 39 has a concave end 40 which fits over the inner end 7b of the bore 11 of the piston rod 7, which terminates in the high pressure valve chamber 37, and the concave end 40 of the check valve 39 forms a seal around the piston rod bore 11 as required during the operation of the device (see Figures 3, 5 and 13).

In this invention and as illustrated in Figures 3, 5, 8, 9, 10, ll, 12 and 13, the check valve 39 is castellated or otherwise formed at its other end 41, and such castellated end 41 bears against the denser body portion of the inner piston head 31, and over the passage 38 which leads to the tapered hole 36 of the inner piston head 31. The check valve 39 is in the storm of a solid cylinder and in one form the Walls 42 of the valve 39 are tapered towards the castellated end 41 (Figures 8 and 9) whilst in another form the walls 42 are provided with flats 43 (Figures 11 and 12). By this arrangement gas being pumped entersthe high pressure valve chamber 37 and the concave end 40 gives afeather cutoff to the inner end of the bore 11 of the piston rod 7 and the gas passes around the exterior of the check valve by the tapered walls 42 or by the flats 43 to and through the passage 38 through the denser body portion of the inner piston head 31 to the tapered hole 36, during the operation of the device.

Such tapered bore of the inner piston head 31 therefore assumes the construction of a bell mouth 35 whereby gas being compressed forces the bell mouth 35 outwards against the bore of the reduced inner portion 111 of the cylindrical casing 1a to form an initial seal against the back pressure of the compressed .gas as it is compressed in the storage chamber 23. The outer surface of the bell mouth 35 of the inner-piston head 31 is a slip fit in the reduced inner portion 1b of the cylindrical casing 1a and such outer surface forms an initial seal in the casing 1a. At the same time the gas under pressure from the storage chamber 28 expands the body portion of the inner piston head 31 outwards about the tapered hole 36 and more particularly about the high pressure valve chamber 37 to ensure that the inner piston head 31 fits the reduced inner portion 1b of the cylindrical casing 1a and bars the escape of gas under pressure from the high pressure valve chamber 37 which is the normal escape route for gas being compressedinto the high pressure valve chamber 37, so that the gas under pressure is forced into the storage chamber 28. Due to the resilience of the connection between the skirt 33 and the denser body portion having the bell mouth 35, the said denser body portion enables the inner end 7b of the piston rod 7 to be selfaligning in the reduced inner portion 1b of the cylindrical casing 1a during reciprocation of the piston rod 7. (See Figures 3, 5 and 13.)

The tapered portion of the inner piston head 31 is arranged to fit over a male part of the valve head 44 of the non-return valve 27 of the storage chamber 28. This valve head 44 has a bevelled sealing surface 45 making a seal on the complementary bevelled sealing surface made in the reduced inner end portion 1b of the cylindrical casing 1a and the valve head 44 has an annular groove 46 alongside the bevelled sealing surface 45 so that a sealing ring 47, which is accommodated and held in the anular groove 46, bears against the flat inner end of the reduced portion 1b of the cylindrical casing 1a to make a seal to ensure that gas under pressure from the storage chamber 28 will not return to the inner piston head 31. Thus gas under pressure passing through the passage 38 in the inner piston head 31 presses on the male part of the valve head 44 of the non-return valve 27 ofthe storage chamber 28, until the valve head 44 is forced off its seat and the gas is forced past the sealing ring 47 which does not permit the gas to return from the storage chamber 28 to the passage 38 in the inner piston head 31. The valve head 44 may be cut away or recessed or provided with an annular checked out portion alongside the annular groove 46 whereby gas under pressure is received and is also permitted to pass inwards to the storage chamber 28 for gas under pressure behind the valve head 44.

At the inner end of the cylindrical casing 1a behind the storage chamber 28 there is provided a releasing means (not shown) operated by a trigger 48 of the gun I and such release gear is arranged to operate a releasable piston (not shown) which permits the gas under pressure to escape into the barrel of the gun I for the purpose of propelling or expelling a shot from the gun I on firing the latter.

Hence in carrying out this invention and preparatory to firing or expelling a shot from a gun 1, gas under pressure is built up in the low pressure chamber 13, transferred to the high pressure chamber 37 and stored in the storage chamber 28. Such build up of gas under pressure is effected by sliding the hand-grip 3 reciprocally along the cylindrical casing 1a of the gun I, the cylindrical casing 1a surrounding the piston rod 7, so that the piston rod, 7 is reciprocated between the 'low pressure chamber 12 in the forward or outer end of the cylindrical casing 1a and the high pressure valve chamber. 37 formed in the inner end at the cylindrical casing 1a of the gun I as the piston rod 7 is reciprocated in the cylindrical casing 1a. 1

As shown in Figures 1, 3, 4 and 10, by drawing the hand grip 3 towards the inner end, gas is drawnin past the hand grip 3 and by the outside of the piston rod '7 and past the sleeve 19 of the outer end 12 of the piston rod 7, then past the ro-ring 16 and past the tapered head on the outer end 12 of the piston rod 7 so that the/gas is drawn into the low pressure chamber 13 in the forward end of the cylindrical casing 1a.

On reciprocating the piston rod'7 outwardly again to its forward position with the taperedouter end of the outer piston head 12 engaged in the tapered interior 9a of the buffer pad 9, gas is forced past the non-return valve 14 in the'outer end 12 of the piston rod 7, so that gas under pressure passes along the longitudinal central bore 11 of the piston rod 7 to the inner piston head 31 on the'inner end of the piston rod 7, and the gas passes by the check valve 39 in the high pressure valve chamber 37 in the inner piston head 31 and through the tapered end of the inner piston head 31 pastthe nonreturn valve 27 to the storage chamber 28in the inner end of the cylindrical casing 1a. i

Onagain reciprocating the piston rod 7 inwardly the check valve 39 in the high pressure valve chamber 37 in the inner piston head 31 is forced back around the inner end of the :bore' 11 of the piston rod 7.to seal off the said bore 11, and the inner piston head 31 advancesiwith its'tapered hole 36 towards the male'part of the valve head 44 of the non-return valve 27 ofthe storage chamber 28 and in so doing, gas is forced past the non-return valve 27 and into the storage chamber 28, where on successive reciprocations of the piston rod 7 in the cylindrical casing 1a gas is built up under pressure in the storage chamber 28 for use as required in firing or expelling a shot from the gun 1.

What 1 do claim and desire to obtain by Letters Patent of the United States of America, is:

1. In an air gun including a gun barrel, apparatus for compressing and storing air comprising an elongated cylindrical casing situated alongside of and parallel to and fixed to the gun barrel, said casing having a closed outer end and an open inner end, a storage chamber for gas under pressure positioned in communication with said open end of said casing, a one-way valve within said storage chamber and'adjacent the open end of said casing,

a hollow piston rod positioned within said casing for axial reciprocation therein, said piston rod having an outer piston head adjacent said outer end of said casing and an inner piston head adjacent said inner end of said casing and also having a central section of enlarged diameter, means associated with each said piston head to provide a seal'between said casing and each piston head, a longitudinal slot centrally located in said casing, a hand piece secured through said slot to said enlarged central section and operable on reciprocation thereof longitudinally of said casing to reciprocate said piston rod within said casing, air intake means associated with said outer piston head operable to allow air to enter into said casing between the outer end thereof and said outer piston head on rearward movement of said piston rod, and to prevent the reverse flow of air through said air intake means on forward movement of said piston rod, a low pressure one-way valve positioned in said outer piston head operable to allow air to pass from the space between the outer end of said casing and said outer piston head into the interior of said hollow piston rod on forward movement of said piston rod and to prevent passage of gas in the opposite direction through said low pressure one-way valve on rearward movement of said piston rod, a high pressure one-way valve positioned in said inner piston head operable to allow gas to pass from the interior of said hollow piston rod into the space between said inner piston head and said storage chamber on forward movement of said piston rod and to prevent gas from passing in the opposite direction into the interior of said piston rod on rearward movement of said piston rod, said one-way valve within said storage chamber being operable to allow gas to pass from the space between said inner piston head and said storage chamber into said storage chamber on rearward movement of said piston rod and to prevent escape of gas from said storage chamber on forward movement of said piston rod.

2. The structure as claimed in claim 1 wherein said gas intake means comprises a sleeve mounted on said outer piston head having longitudinal ridges on the exterior surface thereof bearing on the interior of the cylindrical casing and forming passages therewith to permit gas to pass therealong, an annular groove in the outer piston head forward of said sleeve, and a low pressure O-ring loosely fit within said groove and having checked out portions on the forward side thereof extending radially thereacross.

3. The structure as claimed in claim 1 wherein said piston rod is of reduced diameter between said outer piston head and said central section and between said inner piston head and said central section and including oily wicks wound around on the reduced diameter portions of said piston rod to provide lubrication and reinforcement for said piston rod.

4. The structure as claimed in claim 1 wherein said inner piston head is formed of resilient material and includes an outer end in the shape of a cylindrical skirt adapted to fit snugly over the inner end of said piston rod, said skirt and piston rod being mechanically connected in assembly, the inner end of said inner piston head having a tapered bore flaring radially outwardly toward the one-way valve within said storage chamber, said inner piston head having an inner end portion less dense than the body portion thereof whereby a seal is formed between said inner end portion and the walls of said casing on inward movement of said piston rod which seal is due to radial outward flexing of said tapered 'bore as pressure is built up in the casing between said inner piston head and said storage chamber.

5. The structure as claimed in claim 1 wherein said inner piston head has an axial passage therethrough and said high pressure non-return valve comprises an axial References Cited in the file of this patent UNITED STATES PATENTS 2,293,957 Wells Aug. 25, 1942 2,299,073 Beasley Oct. 20, 1942 2,725,869 Barber Dec. 6, 1955 FOREIGN PATENTS 614,740 Great Britain Dec. 22, 1948 1,122,368 France May 22, 1956