GB2239695A - A round of ammunition - Google Patents

Abstract

A round of ammunition for use in a liquid propellant gun comprises a projectile 25 interconnected by means of a frangible threaded tube 27 with a stub case 28 which has a percussion primer 29 and a booster charge 3a. The stub case 28 has a plurality of gas vents 31 for the charge 30, which is ignited by the primer 29 via a bore 33. The projectile 25 has a rotating band 26 with an aftwardly-outwardly projecting deflectible annular lip seal 26a. At a predetermined gas pressure in the combustion chamber 120 of the gun, the tube 27 will break and the projectile be free to ride forwardly into the gun barrel 8. <IMAGE>

Description

A ROUND OF AMMUNITION This invention relates to rounds of ammunition for liquid propellant guns of the type utilizing a differential piston to provide continued or regenerative injection of propellant into the combustion chamber.

Reference is made to U.K. patent application No. 40263/78, which discloses a liquid propellant gun system having an annual differential piston journaled for telescopic movement with respect to an annular control valve and to the chamber of the firing bore.

Reference is also made to U.K. patent application No.

8122574, which discloses, in ari annular piston, annular control valve, liquid propellant gun, a check valve to permit liquid propellant under relatively low pressure to flow from the supply system into the combustion chamber and to preclude the pulse of pressure generated in the combustion chamber from feeding back to the supply system.

Reference should be made to these earlier applications for structure not shown in this disclosure.

An object of this invention is to simplify the injection mechanism for an annular piston, annular control valve gun system.

A feature of this invention is the provision of a flexible lip on the projectile used in conjunction with the dual angle injection mechanism to positively eliminate backflow of propellant through the injection mechanism during the ignition phase of the gun cycle.

Reference is directed to co-pending application No. 8616562 frorn which this application was divided.

These and other features and advantages of the invention will be apparent from the following description of the invention taken in conjunction with the accompanying drawing in which: FIG. 1 is a view in elevation, in longitudinal crosssection, of a gun system embodying this invention. The upper half of the view shows the assembly during the filling with liquid propellant, while the lower half shows the assembly after filllng and during firing.

DESCRIPTION OF THE INVENTION The gun system Includes a gun barrel assembly 8 which Is fixed within a housing 10. The barrel assembly has a rifled firing bore 20, a projectile receiving chamber 22 havtng an intermediate forctng cone 23 and a cylindrical surface 24. A round of ammunition comprising a projectile 25 with a firing band 26 having an aftwardly-outwardly projecting deflectible lip 26a which Is fixed by a frangible threaded tube 27 to a stub case 28 which has a percussion primer 29 and a booster charge 30.The round Is chambered, locked and extracted by a conventional bolt 32, or, in a large caliber gun, a breech block. The booster has a plurality of gas vents 31 for the booster charge, which Is ignited by the prImer 29 vta a bore 33.

The barrel assembly and the housing 10 define a substantially hollow cylindrical cavity 34 in which are telescopically disposed a substantially hollow cylindrical valve 36 and a substantially hollow cylindrical piston 38.

The valve 36 includes a forward annular portlon 40 having an tnner wall surface 42 provIdIng an annular gap or passageway 44 adJacent the outer wall surface 46 of the barrel. The annular portIon 40 Is Integral with an tntermediate tubular portion 52 having an tnner wall surface 54 providing an annular cavity 56 adjacent the outer wall surface 46, and an outer wall surface 5S providing an annular cavity 60 adjacent the inner wail surface 50 of the houstng.

The intermediate portion 52 Is integral with an aft annular portion 62 having an inner wall surface 6 journaled on the outer wall surface 6c of the barrel and substantially sealed thereto, a transverse aft surface 68, a transverse forward surface 70, an inner annular cavity 72, a plurality of longitudinal bores or passageways 74 extending between the surfaces 68 and 70, and a ring seal 76 disposed In an annular groove In the outer wall surface 58. A plurality of longitudinal bores 77 provide passageways between the cavity 56 and the cavity 72 when the valve 36 is aft of its forerd- most position.Two rods 78 have their aft ends respectively fled to the forward annular portion 40, and pass through bores in the housing. The rods are each biased aftwardly by a respective helical c:mpression spring 210 captured between a cross pin on the rod and a plug in the housing. Each rod may have a respectIve seel as shown in SN 840,074, and has a detent mechanism to preclude aftward movement of the valve beyond that shown in the upper part of FIG. 1.

The piston 38 tncludes a forward annular portion 90 having an inner wall surface 92 journaled on the surface 58 of the valve and an outer wall surface 94 spaced from the surface 50 of the housing. The annular portion 90 is Integral with an intermediate tubular portion 96 having an inner surface 92 bearlng agalnst the ring seal 76 In the valve, and an outer surface 100 bearding against a pair of ring seals 102a and 102b respectively disposed In a pair of annular grooves in the inner surface 104 of the houstng.The intermediate port Ion 96 ts integral with an aft annular portion 106 having mounted thereon a ring seal 108, which may be a discrete seal as shown or simply a tight clearance, which is biased to journal on and seal against the aftmost portion 66a of the outer surface 66 of the barrel. It will be seen that the effectIve cross-sectional area of the forward surface 114 of the aft annular portion 106 is less than the effective cross-sectional area of the aft surface 112, providing the piston sleeve 38 with a differential piston action.

The barrel 8, the valve 36 and the piston 38, dependtng on their mutual positioning, may be considered to define a liquid propellant fill cavity 56, a valve cavity 72, a pumping cavity 118, and a combustion cavity 120. The barrel 8 has a first plurality of bores 126 disposed tn an annular row and angled aftwardly from the surface 66 tn the pumping chamber 118 to the surface 24 tn the projectile chamber 22.

The barrel 8 has a second plurality of bores 128 disposed in an annular row and angled forwardly from the surface 66 In the pumping chamber 118 to bore 20. The bores 126 and 128 are herein shown at an angle of 45 .

A supply means 151 for supplying liquid propellant under pressure is coupled to a cam controlled valve 152 which Is coupled to an inlet in the housing which leads to an annular passageway 154 in the housing, from which a plurality of radial bores 156 lead to and through the forward portion of the surface 50. A radial bore 158 leads through and from the surface 50 aft of the annulus 90 of the piston 38 to a vent.

Two rods 170 and 172 have their aft ends respectively fixed to the forward annular portion 90 of the piston 38, and pass through bores with seals in the housing. The forward ends of the rods respectively terminate In an enlargement. A drum cam, such as Is shown In U.S. Patent No. 3,763,739, issued Oct. 9, 1973, to D. P. Taste, has a helical control track tn which rides a cam follower which has an arm which terminates in a rod follower. The rods are free to move forwardly free of the follower, but are controlled tn their movement aftwardly by the cam track via the followers.The cam track Is also able to pull the rods forwardly vta the followers, all as shown in ########### The barrel 8 has an enlarged portlon 200 with an outer surface 201 which rides on and serves to seal against the Inner surface 54 of the valve 36. A pluraltty of substantially longitudinal bores 77 are disposed in an annular row through the enlargement to serve as passageways from the fill annular cavity 56 to the valve cavtty 72. The plurality of longitudinal bores 74 serve as passageways from the valve cavity 72 to the pumping cavtty i18.

A belleville washer 206 is seated In the valve cavity 72 on the barrel adjacent the bores 77 and retatned by a retaining ring 208. The washer is normally conical tn shape and permits the flow of liquid propellant from the fill cavity 56, through the passageways 77, around the washer 206, through the valve cavity 72, and through the passageways 74 into the pumping cavity 118. Prlor to firing, the differen- tidal valve 36 is held in the position shown In the upper portion of FIG. 1 by meens of external compression springs 210 coupled to the rods 78, so that the surface 66 of the valve head 62 closes both rows of bores 126 and 128 and precludes the flow of liquid propellant from the pumping cavity 118 into these bores. At the beginning of firing, the liquid pressure tn the pumping cavity 118 will rise and be communi- cated to the valve cavity 72.This increase tn pressure on the aft face of the belleville washer 206 over the pressure on the forward face of washer will force the washer flat against its inherent sprtng force to close the passageways 77, to thereby isolate the ftll cavity 56 and tts anterior system from the ballistic fluid pressures generated during the firing.During firing, because the forward fece 70 of the head of the valve 36 has less transverse area than the aft face 68, the differential pressure generated thereby will progressively force the valve 36 forward, against the bias of the springs 210, to progressively reduce the volume of the valve cavity 72 to substantially zero and to progressively uncover the aftwardly directed bores 126 and the forwardly directed bore 128.

In the embodiment here shown1 firing Is tnttlated by a mechanical firing pin In the gun bolt 32 Impacting the primer 29 to generate and pass hot gas under high pressure through the passageway 33 to the booster charge 30, which in turn generateg hot gas under pressure which Is passed through the vents 31 Into the combustion cavity 120. This gas under pressure will act on the aft face 112 of the head 106 of the piston 38 to force the piston forwardly, Increasing the pressure In the pumping cavity 118 on the aft face 68 of the head 62 of the valve 36, and tn the valve cavity 72. The belleville washer 206 closes the passageways 77 and the valve 36 commences to move forwardly.As the valve 36 moves forwardly tt uncovers the bores 126 which pass liquid propellant Into the annular cavlty defined by the projectile, the surface 24, the forcing cone 23 and the lip 26a of the firing band 26. The lip seals the annular cavity, blocking back pressure developed in the combustion cavtty 120 from entering this annular cavity and the upstream liquid propellant supply system. As the pressure Increases in the pumping cavity 118, the lip 26a ts deflected to pass liquid propellant aftwardly of the projectile Into the combustion cavity 120.Because the forward face 114 of the piston head has less transverse area than the aft face 112, the differen tlal pressure generated will force the piston forwardly continuing the flow of liquid propellant through the bores 126.At a predetermined gas pressure tn the combustion chamber 120, e.g., 5,000 psi, the frangible tube 27 will break and the projectile wlll be free to ride forwardly into the gun barrel bore to uncover the bores 128. Slnce the valve head 62 has already uncovered these bores, liquid propellant Is now free to pass from the pumping cavity 118 through these bores forwardly Into the gun barrel bore to provide a spray of liquid propellant into the gun barrel which then burns due to contact with hot combustion gasses.

Throughout the injection phase, chamber gas flow is provided by the aft angled holes and bore gas flow ts provided by the forward angled holes.

The dual angle feature of this Injector dispurses the separate Injection streams and avoids the accumulatlon of an unstable quantity of unburned propellants.

In the event of a misfire, both the differential valve 36 and the belleville washer valve wtll remain in their Initial, open dIspositions, to permit the liquid propellant in the pumping cavity 118 to be returned to the supply system 151 by the process of moving the differential piston forwardly via the rods 170 and 172.

Claims (2)

1. A round of ammunition comprising: a cartridge case, a projectile, a rupturable element interconnecting said case and said projectile, and a deformable seal disposed around and fixed to said projectile.

2. A round of ammunition substantially as hereinbefore described with reference to and as illustrated in the drawing.

2. A round of ammunition according to claim 4 wherein: said projectile has a firing band, and said seal is a deflectible lip projecting from said firing band.

3. A round of ammunition substantially as hereinbefore described with reference to and as illustrated in the drawings.

Amendments to the claims have been filed as follows 1. A round of ammunition comprising: a cartridge case, a projectile, a frangible element interconnecting said case and said projectile, and an annular rotating band, fixed to and around said projectile, having a deflectable annular lip projecting from said band, all spaced forward of said cartridge case.