US3599530A

US3599530A - Automatic replenisher for the hydro-pneumatic recoil systems of large caliber guns

Info

Publication number: US3599530A
Application number: US878121A
Authority: US
Inventors: Robert E Seamands; Elmer J Henning
Original assignee: United States Department of the Army
Current assignee: United States Department of the Army
Priority date: 1969-11-19
Filing date: 1969-11-19
Publication date: 1971-08-17
Anticipated expiration: 1988-08-17

Abstract

In order to maintain a uniform starting point for the reciprocable piston in a hydropneumatic recuperator of the type utilized in the recoil systems of large caliber guns, a reservoir is jointly connected to each of the gas and oil chambers in the recuperator and is provided with a floating piston arranged to separate the oil and the gas into individual areas and maintain an equilibrium position therebetween arranged to return the recuperator piston against a fixed stop at the end of each firing cycle regardless of any change in the volume of the oil.

Description

United States Patent Inventors Robert E. Seamands Moline, 111.; Elmer J. Ilenning, Bettendorf, Iowa Appl. No. 878,121 Filed Nov. 19, 1969 Patented Aug. 17,1971 Assignee The United States of America as represented by the Secretary of the Army AUTOMATIC REPLENISI-IER FOR THE HYDRO- PNEUMA'IIC RECOIL SYSTEMS 0F LARGE CALIBER GUNS [56] References Cited UNITED STATES PATENTS 3,410,174 11/1968 l-lahn 89/43 Primary Examiner-Benjamin A. Borchelt Assistant Examiner-Stephen C. Bentley Attorneys-Harry M. Saragovitz, Edward J. Kelly, Herbert Berl and Albert E. Arnold, .l r.

ABSTRACT: In order to maintain a uniform starting point for the reciprocable piston in a hydropneumatic recuperator of the type utilized in the recoil systems of large caliber guns, a reservoir is jointly connected to each of the gas and oil chambers in the recuperator and is provided with a floating piston 4 Gamma Drawing Flgs' arranged to separate the oil and the gas into individual areas US. Cl 89/43 R and maintain an equilibrium position therebetween arranged Int. Cl. F41f 19/02 to return the recuperator piston against a fixed stop at the end Field of Search 89/42 R, 42 of each firing cycle regardless of any change in the volume of A, 42 B, 43 R, 43 A, 44 the oil.

I 34 717/4 on. I l g g 5 36 4 0 g 0| L G A 5 g E 54 64 s \l 11:! 72 F E 42 58 6O 62 52 48 5s 5 s; 5 E l 1 l\ J AUTOMATIC REPLENISHER FOR THE HYDRO- PNEUMATIC RECOIL SYSTEMS OF LARGE CALIBER GUNS BACKGROUND OF THE INVENTION The present invention relates to hydropneumatic recoil systems for artillery weapons and is more particularly directed to means for insuring relative uniformity to each return of the recoiling parts to battery position despite any change in the volume of the hydraulic oil in the recoil system.

In current recoil systems for artillery weapons of relatively large caliber, the flow of the hydraulic oil from the recoil cylinder to the recuperator during the recoil phase of the firing cycle is customarily utilized to actuate a floating piston in the recuperator for compressing a quantity of nitrogen gas therein to furnish the motive power for the subsequent return of the recoiling parts to battery position. The required oil flow is, in turn, achieved by the displacement of a piston head slidably seated in the recoil cylinder with a stem extending exteriorly thereof into fixed engagement with the recoiling parts. In order to ensure substantially equal trunnion forces from one firing cycle to the next, the floating piston in the recuperator must be returned to essentially the same starting point at the conclusion of each firing cycle. Such require'ment'can be simply achieved by the provision of a fixed stop within the interior of the recuperator in the counterrecoil path of the floating piston. However, since the heat generated in the recoil system during the relatively sustained firing frequently required in modern warfare generally produces an unpredictable increase in the volume of the hydraulic oil therein, considerable difficulty has been encountered in maintaining the desired uniformity in the starting point of the floating piston.

It has been suggested, therefore, that a spring-operated member be slidably interposed between the head of the floating piston and the nitrogen gas to accommodate the expanded volume of the hydraulic oil without disturbing the required abutment between the piston head and the fixed stop in the recuperator. However, this expedient has not proven satisfactory inasmuch as the expansion of the oil frequently reaches such proportions that the slidable member carries the spring entirely out of contact with the piston head thereby eliminating the restraint necessary to maintain the latter against the fixed stop. While the bias of the spring could be increased sufficiently to cope with the anticipated change in the volume of the oil, the resulting increase in the size and weight thereof would be prohibitive.

' Accordingly, it is an object of this invention to provide a hydropneumatic recoil mechanism in which the hydraulic oil is automatically maintained at a relatively constant pressure despite any leakage or heat expansion thereof.

A further object of this invention is to provide a replenisher unit for the aforesaid recoil mechanism which will operate to return the floating piston in the recuperator to the same starting position at the end of each firing cycle regardless of changes in the volume of the oil therein.

Still another object of the present invention lies in the provision of a replenisher unit as aforesaid which will automatically compensate for any loss or gain in the volume of the oil without the need for a mechanical spring.

SUMMARY OF THE INVENTION It has been found that these objects can best be attained by adding a replenisher unit to the recuperator in the form of a cylindrical reservoir in respective communication with both the oil and gas portions thereof and providing a slidable piston in the reservoir to separate the oil from the gas. The gas side of the reservoir piston is formed with a rod extending outwardly through the corresponding end of the cylinder to serve as an indicator for any change in the volume of the oil in the entire recoil mechanism. The resulting reduction in the reservoir piston area exposed for contact by the nitrogen gas results in a differential pressure which, under static conditions, will permit the reservoir piston to compensate for changes in the volume of the oil while the initial higher pressure of the gas continues to maintain the recuperator piston against the fixed stop. Thus, in the event of an increase in the volume of the oil, the corresponding increase in the pressure thereof will actuate the reservoir piston to a new equilibrium position without changing the position of the recuperator piston. Such is also the case in the event of any decrease in oil inasmuch as the compressed nitrogen gas will displace the reservoir piston until equilibrium is again attained. The oil passage between the recuperator and the reservoir is restricted to such extent that oil will not flow therethrough during the actuation of the recoiling parts.

BRIEF DESCRIPTION OF THE DRAWINGS The exact nature of the invention as well as other objects and advantages thereof will be readily apparent from consideration of the following specification relating to the annexed drawings wherein:

FIG. 1 is a schematic sectional representation of a hydropneumatic recoil unit for a gun of large caliber, such unit being secured to the underside of the stationary cradle in which the carrier for the gun tube is slidably mounted and shown in the battery position thereof;

FIG. 2 is a view similar to that of FIG. 1 but showing the relationship of the parts during the initial portion of the recoil cycle; and

FIG. 3 is a fragmentary schematic sectional representation showing the recuperator piston at the conclusion of a firing cycle and the different positions of the reservoir piston at such point, the latter being shown in full in the position required to compensate for an increase in the volume of the oil and shown in phantom in the position required to compensate for a decrease in the volume of oil.

DESCRIPTION OF A PREFERRED EMBODIMENT Referring more particularly to the drawings wherein similar reference characters have been employed to designate corresponding parts throughout, there is shown a large caliber gun tube 12 to which a suitable carrier 14 is fixedly secured as by rings or loops 16. Carrier 14 is, in turn, slidably mounted in a longitudinal track 18 within the interior of a stationary cradle 20. Fixedly mounted to cradle 20 is a recoil unit 22 which, for simplicity of explanation, is here schematically illustrated and consequently does not show the actual size and relative position of the various components thereof. However, it should be understood that the forward and rearward ends of recoil unit 22 are oriented in the same respective directions as the muzzle and breech ends of gun tube 12.

Recoil unit 22 includes a recoil cylinder 24 suitably fastened to cradle 20 and a piston 26 slidably disposed in cylinder 24. Piston 26 is provided with a rod 28 which extends through the rearward end wall of cylinder 24 into fixed engagement with a depending portion 30 of carrier 1 4 he portion of cylinder 24 through which rod 28 passes is utilized to house a quantity of hydraulic fluid, such as recoil oil, ad piston 26 is therefore provided with a suitable seal 32 arranged for slidable contact with the interior wall surface of cylinder 24. The forward end v il of cylinder 24 is provided with an opening or outlet 3. therethrough to permit exhaustion of the air therefrom during the counterrecoil stroke of piston 26.

A recuperator 36 preferably formed with a cylindrical housing 38 is connected to recoil cylinder 24 to form an oil passage 40 therebetween in the vicinity of the rear end wall thereof.

' Within housing 38 and in spaced relation to the interior wall increasing depth. The rear end of tubular member 42 is spaced forwardly of the corresponding end wall of housing 38 to open into the vicinity of oil passage 40. A barrier wall 48 with a central hole 50 therethrough is formed within housing 38 in spaced relation to the front end of flange portion 44 to form an accumulation chamber 52 for the oil flowing through tubular member 42. Forwardly of wall 48, the interior wall surface of housing 38 is provided with oppositely disposed lugs or stops 54 which serve to establish the starting point for the reciprocating travel of a piston 56 provided with a longitudinally extending control rod 58 slidably engageable in tubular member 42.

A plurality of throttling slots 60 of progressively increasing depth are circumferentially spaced about the exterior periphery of control rod 58 and extend from the rear end thereof to a length which will terminate slightly forwardly of barrier wall 48 when the rear end of piston 56 is in abutment with stops 54. Forwardly of the head of piston 56, housing 38 is filled with nitrogen gas which is arranged to be compressed by piston 56 during the forward stroke thereof in order to pro vide the motive power required to return the recoiling parts of the gun to the battery position thereof. A check valve 62 is contained in flange portion 44 to permit oil to flow into accumulation chamber 52 during the forward movement of piston 56 and yet operate to block any flow therethrough during the return movement of piston 56.

Suitable ducts

64 and 66 extending from opposite end portion of recuperator 36 provide for the coextensive connection thereto of a generally cylindrical replenisher 68. Duct 64 is formed with a restricted opening 70 therein which effectively prevents any surging of the oil therethrough during the movement of control rod 58 and yet, once such rod comes to a halt, permits oil to flow between recuperator 36 and replenisher 68 in the event of any change in the volume of the oil. Duct 66, on the other hand, is of sufficient diameter to permit ready passage of the nitrogen gas therethrough in either direction responsive to the movement of piston 72 slidably seated in replenisher 68 in sealing engagement with the interior wall surfaces thereof. Piston 72 is also provided with a forwardly extending rod 74 projecting out through the front end wall of replenisher 68 and provided with spaced indicia 76 arranged to indicate the quantity of oil within the entire system. One of the indicia is specifically located and marked, as at 78, so as to be positioned slightly beyond the forward end wall of replenisher 68 in the absence of any increase or decrease in the volume of the oil. The differential area formed by the opposite faces of replenisher piston 72 is such that the pressure of the gas thereon is at all times slightly greater than the pressure of the oil.

During the recoil movement of gun tube carrier 14 in cradle 20, piston 26 is pulled along therewith to force oil from recoil cylinder 24 into recuperator 36. The force thus applied against the rear end of control rod 58 displaces piston 56 out of contact with stops 54. As control rod 58 moves forwardly, throttling slots 60 therein and throttling grooves 46 in the tubular member 42 are both exposed for the passage of oil therethrough. At the same time, the flow of oil into recuperator 36 opens check valve 62 to increase the quantity which will pass through accumulation chamber 52 and act against the rear face of the head on piston 56 to continue the forward movement thereof. Piston 56 continues forwardly until the recoil forces produced by the firing of the gun are absorbed by the combination of the frictional forces opposing such travel, the pressure drop in throttling grooves 46, and the increasing compression of the nitrogen gas. As the gas is thus compressed, piston 72 in replenisher 68 remains virtually stationary since it is isolated from transient conditions in the pressure ofthe oil by restricted opening 70 in duct 64.

During the counterrecoil or return travel of control rod 58, the compressed nitrogen gas in recuperator 36 actuates piston 56 to force oil back into recoil cylinder 24 and thereby operate piston 26 to return carrier 14 to the battery position in cradle 20. As oil begins to flow rearwardly through accumulation chamber 52, check valve 62 is closed to limit the flow of oil to the space between control rod 58 and tubular member 42. Since throttling grooves 46 and slots 60 decrease in depth in a rearward direction, the resulting resistance to the rearward travel of control rod 58 prevents excessive impact of carrier 14 against the mating portion of cradle 20. In the event the oil in the system expands due to the heat engendered therein by any relatively sustained firing operation of the gun and thereby prevents control rod piston 56 from reaching stops 54 once the recoiling parts have attained battery position, the resulting imbalance of the forces on replenisher piston 72 will automatically adjust the latter to permit the excess oil in the recuperator 36 to flow therefrom into replenisher 68 through restricted opening 70. Thus, recuperator piston 56 will return to its starting position in contact with stops 54. In the event any leakage of the oil or any substantial drop in the temperature thereof produces a decrease in volume which will permit control rod piston 56 to reach stops 54 before the recoiling parts attain battery position, the imbalance of the forces on replenisher piston 72 will automatically move the latter rearwardly, as best indicated in FIG. 3, to force additional oil through restricted opening 70 into recuperator 36 to restore the volume originally contained therein and in recoil cylinder 24.

Thus, there is here provided improved means for compensating for any loss or gain in the volume of the oil in a combined recoil and recuperator system in order to ensure the return of the recuperator piston to the same starting position for each firing cycle. The use of a floating piston in an added replenisher separately connected to each of the oil and gas portions of the recuperator is a simple yet positive expedient for maintaining the required equilibrium between the oil and gas pressures at the beginning of each firing cycle.

We wish it to be understood that we do not desire to be limited to the exact details of construction shown and described, for obvious modifications will occur to a person skilled in the art.

We claim:

1. In a large caliber gun having a hydropneumatic recoil mechanism including a recuperator unit with a reciprocating piston responsive to the recoil fiow of oil thereagainst for compressing a quantity of nitrogen gas to provide the motive power for returning the recoiling parts of the gun to battery position, means for returning the recuperator piston to the same starting position at the end of each firing cycle comprising,

a replenisher connected to each end of the recuperator, and

a piston slidably seated in said replenisher between the oil and the gas therein to maintain an equilibrium position responsive to changes in the quantity of oil within the entire recoil mechanism.

2. The invention defined in claim 1 wherein said replenisher piston is contoured to produce a differential pressure thereon responsive to changes in the volume of the oil in the recoil mechanism.

3. The invention defined in claim 1 wherein said replenisher piston comprises a head and a rod extending from one s de of said head through the nitrogen gas to project outwardly of said replenisher whereby the area exposed to the oil is larger th; the area exposed to the gas to provide a differential pressure thereagainst for normally urging said piston to compensate for changes in the volume of oil.

4. The invention defined in claim 1 wherein the conn ction between the recuperator and said replenisher includes a restricted passage for preventing the flow of oil therebetween during the reciprocation of the recoiling parts without affecting the required equalization of the pressure between the oil in the recuperator and the oil in said replenisher following the termination of the counterrecoil movement of the recoiling parts.

Claims

1. In a large caliber gun having a hydropneumatic recoil mechanism including a recuperator unit with a reciprocating piston responsive to the recoil flow of oil thereagainst for compressing a quantity of nitrogen gas to provide the motive power for returning the recoiling parts of the gun to battery position, means for returning the recuperator piston to the same starting position at the end of each firing cycle comprising, a replenisher connected to each end of the recuperator, and a piston slidably seated in said replenisher between the oil and the gas therein to maintain an equilibrium position responsive to changes in the quantity of oil within the entire recoil mechanism.

3. The invention defined in claim 1 wherein said replenisher piston comprises a head and a rod extending from one side of said head through the nitrogen gas to project outwardly of said replenisher whereby the area exposed to the oil is larger than the area exposed to the gas to provide a differential pressure thereagainst for normally urging said piston to compensate for changes in the volume of oil.

4. The invention defined in claim 1 wherein the connection between the recuperator and said replenisher includes a restricted passage for preventing the flow of oil therebetween during the reciprocation of the recoiling parts without affecting the required equalization of the pressure between the oil in the recuperator and the oil in said replenisher following the termination of the counterrecoil movement of the recoiling parts.