Counter recoil mechanism, preferably for an artillery weapon
BACKGROUND OF THE INVENTION 
     The invention relates to a pneuamtic or hydro-pneumatic counter recoil mechanism for an artillery weapon. 
     Such mechanisms generally operate by means of an hydraulic fluid (oil) arrangement, that operates hydro-pneumatically. The counter recoil recuperator of the state of the art is not capable to adjust the counter recoil force automatically to the prevailing elevation of the gun barrel. Therefore, frequently the counter recoil force is too large with a low gun barrel elevation and/or also with small charges, so that the automatic breech block function is inhibited as a result of an insufficient recoil path. 
     SUMMARY OF THE INVENTION 
     It is an object of the invention to construct a counter recoil mechanism of the afore-described type wherein the counter recoil force automatically adjusts itself in the artillery weapon to the prevailing gun barrel elevation. With reduced gun barrel elevation and small charges the counter recoil force is automatically reduced. Thereby the recoil path is enlarged so that the automatic breech mechanism remains open for a sufficient period of time. At high gun elevations, on the other hand, the counter recoil force is not reduced. Additionally, there is avoided that the recoil velocity of the gun barrel reaches inadmissibly high values, for example for ejecting the primer or for effecting the loading function which is coupled to the recoil movement. 
     Thus the invention provides for an automatic adjusting arrangement for a counter recoil mechanism for a gun barrel, which adjusts the volume of the chamber containing the gas or the hydraulic medium in such a way that, at reduced gun elevation, the counter recoil force becomes smaller and thereby permits an increased recoil path and effects not such a large recoil velocity. With small charges a sufficiently long recoil path is attained, which reduces the counter recoil force which acts here as a main braking force. The stream brake force in the hydraulic recoil brake accepts, with the reduced recoil velocities produced by the small charges, only a reduced portion of the recoil brake work. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     With these and other objects in view, which will become apparent in the following detailed description, the present invention, which is shown by example only, will be clearly understood in connection with the accompanying drawing, in which: 
     FIGS. 1 and 2 respectively illustrate schematically partially in vertical cross-section and partially in side-elevational view a first and second embodiment of a control mechanism with a control guide, respectively a slider, arranged at a pneumatic recuperator; and 
     FIGS. 3 and 4 illustrate partially in vertical crosssection and partially schematically in side-elevational view two further embodiments of the control guide having mechanically, respectively electrically actuated valve seats forming part of a hydro-pneumatic recuperator. 
    
    
     DETAILED DESCRIPTION 
     FIG. 1 illustrates a known pneumatic recuperator having a cylinder 16 which is mounted on the cradle frame 22 of the gun and which has in its interior a reciprocally mounted piston 17 connected to a piston rod 18 mounted in a conventional manner in the cylinder 16 by means of the usual sealing rings. This piston rod 18 is connected at its rear end by means of fastening nut 21 to a bottom member 32, which is operatively connected to the gun barrel (not illustrated). When a shot is fired in the direction towards the left in FIG. 1 the bottom member 32 travels jointly with the gun barrel backwards towards the right and causes thereby, via the piston rod 18 and piston 17, a compression of the gas in the pressure chamber 15 of the cylinder 16. Between the cradle frame 22 and the bottom member 32 a shock absorbing ring 23 is disposed to absorb excessive shock forces. 
     The adjusting arrangement in accordance with the invention consists of a cylinder 20, the pressure chamber 11 of which is in communication with the pressure chamber 15 of the recuperator via a conduit 15a. There is slidably mounted within the cylinder 20 a displacement piston 1 having a hollow smooth piston rod 3 which slidably guides the piston 1 in the cylinder 20. The conventional sealing rings are also provided in the cylinder 20. The hollow piston rod 3 has a pressure medium inlet opening 8 and a pressure medium outlet opening 7. Furthermore, a communication opening 3a is provided for communicating the inner chamber 6 of the cylinder 20, which is disposed behind the piston 1, either with the chamber 9 or with the conduit 10 in the inner hollow space 10 of the hollow piston rod 3. A control piston rod 2 is slidably mounted in the hollow piston rod 3, which with a control surface 2a, disposed between the control edges 4 and 5, covers more or less the opening 3a in the hollow piston rod 3. The control piston 2 furthermore includes the inner conduit 10 and the chambers 9. The free end of the control piston is formed as a roller 13 which is guidingly mounted in a curved guide groove 12 at the fixed gun carriage mount. The curved guide groove 12 is disposed in such a way that by swinging the gun cradle frame 22 and thereby also the recuperator about the trunnion 19 of the fixed gun carriage mount away from the horizontal firing position illustrated in FIG. 1 the control piston 2 is pushed into the hollow piston rod 3. Thereby the annular chamber 9 which is in communication with the inlet opening 8, is placed in communication via the opening 3a with the inner chamber 6 of the cylinder 20. The pressure medium than causes the displacement piston 1 to move towards the right, whereby the volume of gas in the pressure chamber 11 is made smaller (i.e. is compressed) and thereby the recoil force is increased. When the gun barrel is again swung back, then the control piston 2 is pulled towards the left by the piston rod 2a. Thereby the inner chamber 6 is joined via the opening 3a with the inner conduit 10 and thereby is also placed in communication with the pressure medium outlet opening 7. Thereby the control piston 1 can be pushed by the pneumatic medium disposed in the pressure chamber 15 via the conduit 15a and the pressure chamber 11, which then increases in size, toward the left, whereby the recoil force is reduced. 
     In the embodiment of FIG. 2 the piston rod 2b of the control piston 2 is pivotally connected via a link 24 onto that portion of the gun whose elevation is not adjustable. Consequently, a relative adjustment between the piston rod 3 and the cylinder 1 occurs during a change in elevation of the gun barrel. 
     In the pneumatic recuperator of FIGS. 3 and 4 the inner chamber of the cylinder 20 is divided by means of a simple piston and piston rod 18a into the pressure chamber 15 and the pressure chamber 6 at the rear side of the piston 1a. The gas which is present in the chamber 6, can, for example, be nitrogen. 
     The pressure chamber 11 is joined by way of a conduit 31a and a communication inlet conduit 31 with the housing of a control valve 27a (FIG. 3), respectively 27b (FIG. 4). In the bores of the housing there are disposed two valves 42b, 43b which, via piston rods 40a, 43b are joined to the pistons 40b, 41. The valve heads of the valves 42b, 43b are held in their operative position on the valve seats in the housing by means of coil springs 44b, 45b. In the embodiment of FIG. 3 there is disposed a further cylinder chamber between the bores for the pistons 40b, 41, which piston chamber receives a piston 46 having a piston rod 46a. This piston is biased by means of a coil spring 38 abutting against its operative end, whereas at its other end it supports via a valve pivot support 36 the swingable double valve lever 26. One end of the double valve lever 26 is pivotally joined by means of a pin and slot connection 26a to the leg 24a of a balance lever 24, which is in turn pivotally joined at its other end by an other pin and slot connection 24b with a piston rod 33a of a piston 33 slidably disposed in a further piston chamber 34 of the housing 27a, which piston is spring-loaded by means of a coil spring 35. A control lever 25 is pivotally connected in the middle region of the balance lever 24 to the latter. A support arm 37 is fixedly secured to the housing 27a and pivotally supports the control lever 25, which control lever has at its other end a roller 13 which is slidable within a curved guide groove 12 forming part of the trunnion 19. There is disposed at the housing a pressure medium inlet opening 28 and a pressure medium outlet opening 29 as well as communication channels 47, 47a, 47b which communicate individual cylinder chambers to each other as shown in FIG. 3. The valve arrangement operates as follows: The valve as illustrated in FIG. 3 is in the switched off position, in which it is maintained by means of the spring 38. The valve is brought into its operative position, which means in a position in which the inlet opening 28 is pressurized, whereby the piston 46 is pressure biased at its rear side via the communication channel 47, so that the double valve lever 26 lifts off the valve head 42 from its seat in the housing 27a. Thereby an open communication is established between the pressure chamber 11 via the communication opening 31 past the valve head 42 towards the pressure medium outlet opening 29. If now the gun barrel is swung about the trunnion axis of the trunnion then also the control lever 25 is swung a predetermined angle (due to the special configuration of the groove 12) and via this lever by means of the balance lever 24 the double valve lever 26 is swung in such a way that with its free end it pushes down on the piston 41 and thereby lifts off the valve head 43 from its seat in the housing. The valve head 42 is then again pushed by means of the pressure spring 44 onto its seat. Now the pressure medium inlet opening 28 is in communication via the open valve head 43 with the pressure chamber 11. The return guiding of the valve double lever 26 into its starting position is effected by the pressure piston 33b, which is biased by the pressure coil spring 35b, via the balance lever 24, in view of the fact that the piston 33 is in communication via the communication channel 47b with the pressure medium inlet opening 31. By means of the communication channel 47a the adjusting of the piston 46 is made possible since the communication channel 47a permits the streaming of the pressure medium behind the piston towards the outlet opening 29. 
     For purposes of actuating electrically the control valve 27b, in accordance with FIG. 4, which is constructed in similar fashion as the valve in accordance with FIG. 3, the valve double lever 26 is replaced by the electromagnets 50 and 51 which are controlled by the operational amplifier 54 and the guide groove 12 and roller 13 are replaced by an elevation emitter 53 which senses the elevation of the gun barrel and emits electric pulse signals accordingly. The return guidance into the starting position results by means of the pressure measuring emitter 52, the pressure valves of which are compared in the operational amplifier 54 with the pressure values of a corresponding pressure scale, which corresponds to the prevailing gun elevation which is reported by the elevation emitter. 
     Although the invention is described and illustrated with reference to a plurality of embodiments thereof, it is to be expressly understood that it is in no way limited to the disclosure of such preferred embodiments but is capable of numerous modifications within the scope of the appended claims.