US2774281A - Injector pump for breech cooling of guns - Google Patents

Description

Dec. 18, 1956 G. A. HAwKlNs INJECTOR PUMP FOR BREECH COOLING oF GUNS 'Filed sept. 19. 1945 a- U ii 9,

United States Patent INJEcroR PUMP non BREECH coLiNC F GUNS eorge A. Hawkins, West Lafayette, Ind., assigner to Purdue University, Lafayette, Ind.

Application September 19, 1945, Serial No. 617,374 Y 2 Claims. (Cl. 89-1) The inven-tion relates to means for cooling machine guns by linjection of water or other liquids or fluid, and seeks to present a practicable pump device operable by lprior gun mechanism for supplying a liquid under pressure to a jet or other device at the gun chamber or bore.

lt is ajparticular purpose to present such a device adapted to supply charges of Water to the gun at the rapid intervals corresponding to the frequency of fire of current models of machine guns; which will also be of light weight, and small size, and adapted to be incorporated as a part of the gun without interfering with conventional use of the weapon.

Because of the delicate balance of forces in current models of machine guns, and the fact that any addition to the work required to be performed by the recoil operated mechanism is likely to result in the stoppage from causes that would not otherwise have such effect, it is an object of the invention to present a device which will require a minimum of work by the gun mechanism for itS operation. In this particular it is a purpose to cause the pump to function as part of the recoil mechanism, so that it will act as a resilient buffer to absorb some excess of momentum in the present recoiling parts of the gu-n and to convert a part thereof to counter recoil energy.

A further attainment in View is the perfection of details in the pump by which a minimum impedance o f a piston by liquid to be moved will be sulered, and a maximum of ener-gy in the piston applied to compression of liquid at an injector jet, without requiring complicated devices. i

Additional objects, advantages and lfeatures of invention reside in the construction, arrangement and cornbination of parts involved in the embodiment ofthe invention, as will be apparent or understood from the following description and accompanying drawings wherein:

Fig. l is a vertical longitudinal section of 4the rear end of a machine gun in which my invention is embodied,

Fig. 2 is a cross section on the line 2 2 of Fig. '1;

Fig. 3 is a cross section on the hne 3 3 of Fig. l;

Fig. 4 is a rear elevation of the bolt and striker plate;

Fig. 5 is a fragmentary longitudinal section of a modification of the pump.

Referring more particularly to the details in the draw-- between the grips as heretofore.

The back plate 13 has the usual buffer disc sleeve 15 in which elastic buffer `discs have heretofore been mounted supported rigidly at the rear or outer end of the sleeve, and bearing against a buffer plate set in thet f butV all the discs and thepbuer plate are axiallyrboredf.

Y 2,774,281 Patented Dec. 1s, 195s ,Q I ice s o 'as to receive freely slidable therethrough a piston rod 18 extending through the head 19 of a pump cylinder 2 0, the head being tenoiied and threaded to screw into the rear' interiorly threaded end of the sleeve 15 and against 4the discs as a figid support o'r seat therefor. The tenon 21 is bored at its :forward end to receive a packing and gland around the rod 1S, as at 22, the rod 18 being snugly slidable through a reduced bore in the head. A piston 23 4is fixed on the rod, reciprocable in the cylinder 20.

In the present instance the cylinder 20 is shown as a bored piece closed at its rear end by a plug 24. Set in the cylinder and confined between the plug 24 and piston there is a helical spring 25 serving to hold the piston yieldingly at the forward limit of its movement. The tension of the spring may be adjustable, if desired, by means of the plug 24. The piston may also be made adjustable on the rod to vary the length of the forwardly extended part of the latter, as will be understood.

The length of the cylinder bore greatly exceeds the length of Vthe required stroke of the piston, so as to accommodate a spring of adequate length.

The forward end of the rod 18 is in, and llongitudinally alined with, the path of the bolt 26 of the gun; and Va striker plate 27 yis mounted on the rear end of the bolt, to engage the end of the rod 1S, avoiding liabilityof deforming the material of the bolt and also serving to protect and retain the sear and sear side against loose movement on impact of the bolt with the rod 18. Thi-s plate 27 is held iin place by a dovetail bar 28 formed and fixed permanently to the back of the plate 27 and set slidably in a corresponding dovetail `groove formed across the extremity of the bolt. The bar 28 is of a length equal to the width of the bolt, and with lthe latter fits slidably between the side plates of the receiver. In consequence, no fastenings are required for the plate 27, and it may be vtaken off manually when the bolt is taken .out of the receiver by manually pressing the plate 27 toward either side until the bar 2S clears the groove across the end of the bolt.

The cylinder v20 of Figs. 2 and 3 is formed with an inlet port 30, or more, adjacent -the forward end of the piston when in initial position, and two or more ports 31 immediately to vthe rear of the piston when in said position. The cylinder has fitted and welded therearoundV a manifold ring 32, U-shaped in cross section, into which a supply pipe 33 is set, and a U-bend pipe 34 `also has one end set in the manifold and its other end set in the port 30, forming a by-pass between the cylinder spaces at .opposite ends of the piston during a limited part of its movement. In a modification of the pump in Fig. 5, four ports 30' and four ports 31 (three of each being shown) are formed in the cylinder, the two series in Ithe same relation ,to each other and to the piston as are the ports 30 and 31, and an interiorly channelled manifold ring 35 is provided on the cylinder, broad enough to extend over and form common communication between all of the ports 30 and 31'. The supply pipe 33is engaged in this manifold, but need for pipe 34 is eliminated, at the same time that a Ireduction of impedance of piston and bolt movements is attained, which will be understood.

At a distance -rearwardly of the ports 31 an outlet 36 is formed through the wall of the cylinder, from which a high pressure pipe 37 is extended forwardly alongside or under the receiver 11 and to the chamber of the gun, or to other location, so that liquid carried through the pipe may be discharged into the gun chamber, or bore; the last named details not being shown since they comprise no part of the invention claimed herein. It may be stated, however, that it has heretofore been proposed to inject water into the breech of a gun as a cooling expedient, and the use of :a jet requiring the water to be forced therethrough with a spraying eiect has been contemplated. Y

It may be seen that some extent of movement of the piston 23 from its initial position, shown in Fig. l, may occur before it passes beyond the ports 31. Maximum high pressure is not developed in the outlet r'port 36 until the piston does pass beyond these ports, which may be termed cut-off. In order to utilize this function to produce a very certain measurement and .instant high pressuredischarge vof liquid :at whatever nozzle there may be provided at the gun breech, I have` located in the pipe 37 a pressure regulating check valve 38, of suitable construction to permit passage of liquid to the gun after the piston 23ypasses beyond the ports 31.

vThe valve 38 may be constructed so as to'positively prevent return ilow ofthe liquid toward the pump, and also may ,be` :adjustablejor provided with a spring of strength suicient to prevent ow toward the gun cham- .ber until the pressure at the port v36 is higher than the hydrostatic head Ade veloped by inertia. of the water be- Y fore the piston in the early movement of the latter towardor to the rear sides of theports 31.

'Ihepump is so proportioned in relation to the movement of the r`d7718 by the bolt, that it may be adjusted to supply. inthe neighborhood of Vthree or more grams of water to the `gun on each operation of the piston in the caseof a .50 caliber machine gun of the type'indicated, and this'su'pply may be varied by substitutingpistons' and cylinders of different diameters, or by adjusting the piston on the rod18 by means of nuts 39 screwed on the rod before and behind the piston. The piston body between the nuts may be of conventional construction,

suitable. to the use disclosed. The cylinder is shown with a forward shoulder which serves as a stop for the piston and.. therefore adjustment of the piston longitu'dinally Von the rodV 18 with corresponding changes of position of the nuts, determines Athe extent to which the rod projects into the receiver 171 and the length of stroke of 'the piston. Parts of the supply pipe 33 and high pressure pipe '37 may be flexible conduit to facilitate remov-al and replacement of the back plate, and for other purposes. l v

I'na gun 'of' the kind indicated, the bolt by which my rod: 18 is operated has a weight in the neighborhood of five, pounds and -moves by recoil over a total distance of seven ahdfone-eighth inches, and assuming the diameter ofthe pump bore to `be l5 mm. the device is constructed `inthe present illustrated instance to utilize approximately lby'theboltfrnay have some impeding effect lon the bolt,

which may, be compensated for by adjustment ofthe oil buer device customarily present in the barrel recoil' device in the Vgun indicated, or other recoil device, and. ad-

justment vof `the plug 214lto cause rn'o'refeife'ctive recoil 4function 'ofuthecspring Y25. These adjustments maintain orihcreasethe rate of`re ofthe gun.

As the lrod" 18 is pushed rearwardly by the bolt, the piston rst displaceswater from the rearpart of the cylinderfthrfough fhefports 31, and forwardly through the pipe 34, intofthe Aextreme forwardpart ofthe cylinder, and against Athe forward side-of the piston 23'. At the same time the spring 25 Vis progressively compressed, with increasing` absorption; ofjinertiaof the-bolt. A-S

. recoil movement. While I have disclosed my invention in the best form the piston passes rearwardly of the ports 31, cut-off there prevents further -displacement of water through the ports 31, and a high resistance ,to further movement of the piston develops by the inertia of liquid in advance of the piston toward the rear in the cylinder and standing in the pipe 37 to the gun chamber. The momentum of the bolt is assisted in this work by the momentum of the liquid in motion through the bypass pipe 34 to the forward side of the piston, and aiding, as a liquid piston, in the rearward movement of the piston 23. When cutoi occurs at the ports 31, inow of water from the 'slipply 33 to the manifold ring will avoid dissipation of the liquid piston energy before it has been materially utilized against the piston 23.

The spring 25 is' preferably one capable of counteracting the inertia of the bolt, less that dissipated in operation of the piston upon the liquid, although the discs 16 may be permitted to perform some part of this function, the plate 27 engaging the buffer plate 17 'in the same manner as the bolt itself, has heretofore done.

It is my practice, in one manner of u'tlizationoffthe invention, to maintain the water supply at 33 under pres-V sure, so as to minimize to that extent impedance of thel piston after cut off 'at the ports 31, the pressure supply Y being formally indicated as a storage reservoir 40 from which the pipe `33 leads, an air chamber 41 being indicated; also a pump 42 having .an outlet 43 delivering to the'reservoir, andasupply duct 44 connected to its. intake. The pump is adapted to be otherwise mounted and connected to a recoiling member, and this is con templated. v

Ill this type of gun a separate recoil action is provided for the barrel.. operatively connected with the cartridge,l

v there. is an initialgreco'il interaction 'and coupling between thewbarrel unit and the bolt unit, including an accelerator device on the barrel: unit by which impetus may be added tothe movement of the bolt, and the recoil of 'the barrel unit is adjustable so that this increment of motion `in the boltmay be increased, to compensate for the energyrequired in operating the valve. There is acoupling ofrbol't and barrel also during a small part of their'nal counterin Vwhich I have constructed and used the same, it Will nevertheless be` understood that this is exemplary only,

and that improvement in design and proportions 'com` Arnen'surate with. requirement of use, strength of material,

. mentwith the claims hereunto appended.

I claim: p

1,v In, an injector pumpfor cooling a gun having a receiver body, a barrel, a reciprocating bolt and' a bolt buffer assembly,` comprising, Va pump cylinder,- closed-at vits`I rearward; end: and provided withl a reduced, axially bored,threaded forward head portion, said cylinder adapted to. be threadablyfsecurediin coaxial. relationv to the rearward end of said bolt Vbuffer assembly, a' piston jrocl connected at its forward end to said reciprocating Vbolt and extending axially'V and rearwardlythrough said boltbulfer'assembly, said" axial bore in headportionon said-pump cylinder 'and into the Vforward portionof 'saidY iipump cylinder, a piston secured on the rearward'zendofsaid-:piston rod and Vslidabley in said'Y pump cylinde'xg-a spring insaid pump cylinder normally biasing said pistonV Vinfarforw'ard direction, an annular channel? surrounding Y psaicljpurnpj; cylinder,V a1 rstl pipe connecting said iannularj channel with a source of liquid coolant, a series of radial ports in said cylinder wall communicating between vsaid annular channel and said pump cylinder, a second pipe communicating between said annular channel and the forward portion of said pump cylinder immediately forward of said piston when said piston is at its full forward position in said pump cylinder, a third pipe communicating between said pump cylinder at a point substantially rearward of said piston, when said piston is in said full forward position, and a barrel on said gun, said piston acting upon recoil to move in a rearward direction to force said liquid coolant into said barrel of said gun and a pressure regulating valve on said third pipe.

2. In an injector pump for cooling a gun having a receiver body, a barrel, a reciprocating bolt and a bolt buer assembly, comprising a pump cylinder axially secured at its forward end to said buter assembly, a vspringbiased piston slidably mounted within said cylinder and connected to said reciprocating bolt of sa'id gun, an inlet and an outlet port formed on said cylinder, said inlet port in communication with each other, a manifold mountedV on said cylinder connecting said inlet port W-ith said second port, and said piston being initially located between said irst and second ports.

l References Cited in the le of this patent UNITED STATES PATENTS 543,567 Browning July 30, 1895 1,073,452 White Sept. 16, 1913 1,216,460 Kilgore Feb. 20, 1917 1,401,667 Brown Dec. 27, 1921 2,376,321 Albertson May 22, 1945

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