EP0619868B1 - Piston cushioning in a gun using a liquid propellant charge - Google Patents

Abstract

A system for supplying a device, such as the combustion chamber (5) of the barrel (1) of weapon using a liquid propellant, including a hydraulic cylinder consisting of a piston (15) and a cylinder (9) defining therewith a variable-volume chamber (16) connected to the combustion chamber (5) via an outlet channel (21), and a cushioning assembly (40) consisting of a projection (41) extending into the chamber (16), and a recess (42) formed in the piston (15) for cushioning said piston (15) at the end of its stroke by throttling the hydraulic fluid. An assembly (45) is provided for adjusting the length of the projection (41) within the chamber (16) according to its volume.

Description

The present invention relates to a system for supplying a device with a volume of hydraulic liquid having a predetermined value varying according to the operating conditions, this system comprising a hydraulic cylinder consisting of a piston and of a cylinder determining with the piston a variable volume chamber connected to the device, means for supplying the chamber with pressurized liquid, means for controlling the displacement of the piston such as a pressurized fluid introduced into the cylinder on the side opposite to said chamber, and means for damping the movement of the piston at the end of the stroke.

Generally, in a supply system of the aforementioned type, damping means can be, for example, of the hydraulic rolling effect type or of the servo type.

For damping by hydraulic rolling effect, the bottom of the cylinder of the jack may include a cavity intended to receive a boss of corresponding shape provided on the piston. The jack equipped with such damping means is designed for specific operating conditions. In other words, the cylinder is chosen according to the supply conditions necessary for the operation of the device. If these conditions are modified, in particular the speed of the piston at the end of the stroke, it is then necessary to replace the cylinder with a cylinder whose characteristics are adapted to these new conditions, which can lead to often long assembly / disassembly operations. and tedious.

Damping by servo-control of the flow rate of the supply fluid to the actuator requires an apparatus comprising in particular pressure and positioning sensors, which deliver signals then processed by a computer to adjust the flow rate of the fluid as the displacement of the piston. A such equipment is complex, expensive and difficult to develop.

US Pat. No. 4,281,582 describes a system for supplying liquid propellant to a weapon in which the injection piston is mechanically attached and a second whose movements are controlled.

Patent EP-A-0 250 978, the description of which is taken from the preamble of independent claim 1, also describes a liquid propellant weapon comprising a hydraulic cylinder determining with a piston a variable volume chamber, means of supply of the chamber with liquid under pressure and means for damping the piston.

The object of the invention is to design a supply system in which the damping means of the piston at the end of the stroke are designed to take account of operating conditions which can be brought to be modified, these modifications not causing the replacement of the actuator and / or of the damping means, the latter being designed for variable speeds reached by the piston at the end of the stroke.

The invention therefore provides a system for supplying a device with a volume of hydraulic liquid having a predetermined value varying according to the operating conditions, this system comprising a hydraulic cylinder constituted by a piston and a cylinder determining with the piston a variable volume chamber connected to the device, means for supplying the chamber with pressurized liquid, means for controlling displacement of the piston, such as a pressurized fluid introduced into a cylinder on the side opposite to said chamber, and means for damping the movement of the piston at the end of the stroke, the speed of the piston at the end of the stroke being variable and determined by the initial axial length of the aforementioned chamber, the piston being braked and damped by a hydraulic rolling effect, characterized in that the damping means of the piston at the end of the stroke comprise a rod or core carried by a cylinder bottom and projecting inside said chamber, and a cavity of corresponding shape and size, formed on the piston and intended to receive the core at the end of the piston stroke, means being, moreover, provided for adjusting the length of the core projecting in said chamber as a function of the speed reached by the piston at the end of the stroke.

According to a characteristic of the invention, the bottom of the cylinder in the direction of which the piston moves is axially movable to adjust the volume of the chamber, and the means for adjusting the length of the carrot projecting inside said chamber also ensure the adjustment of the axial position of said cylinder bottom.

According to another characteristic of the invention, the aforementioned adjustment means ensure simultaneously the displacement of the rod of the damping means and the bottom of the cylinder, so that the rod of the damping means protrudes inside the chamber over a length which increases with the increase in the volume of bedroom.

According to one embodiment of the invention, the bottom of the cylinder is constituted by a cylindrical element screwed into the body of the jack, the rod of the damping means is screwed inside said tubular element with threads which are tighter that those used for screwing the cylindrical element into the cylinder body, means being provided for immobilizing said rod in rotation, and the aforementioned adjustment means comprise a device for controlling the rotation of the bottom of the cylinder.

Thus, according to this embodiment, the aforementioned adjustment means move the rod of the damping means and the bottom of the cylinder in the same direction, but over different displacement lengths, by a single control means.

Alternatively, the aforementioned adjustment means could be designed so as to move the rod of the damping means and the bottom of the cylinder in two opposite directions.

Thus, a supply system according to the invention can be easily adapted to operating conditions which may vary from one application to another, without requiring complex equipment which is difficult to adjust.

Such a supply system can for example be used in a liquid propellant weapon to inject under pressure a predetermined quantity of a propellant into the combustion chamber of the barrel of the weapon.

In such an application, the propellant is stored in a volume tank variable constituted by the chamber of the aforementioned hydraulic cylinder and in which a pressure multiplier piston moves which is driven by the pressure of the gases prevailing inside the combustion chamber, pressure which is then insufficient to cause the projectile to be ejected put in position in the barrel of the weapon. Given the acceleration which is imparted to the piston as a result of a rapid rise in pressure of the combustion gases, the speed reached by the piston at the end of the stroke is relatively high, and it is desirable to provide damping means to brake the movement of the piston at the end of the stroke.

In such a supply system, it is advantageously possible to provide a variable volume reservoir according to the desired firing conditions, but in this case a variation in the volume of the chamber will cause a variation in the speed reached by the piston at the end of race.

Thus, a supply system according to the invention is perfectly suited to take account of different firing conditions, such a possibility not being able to be obtained with a tank with fixed volume.

• la figure 1 est une vue en coupe schématique et partielle d'une arme à prolpulseur liquide équipée d'un système d'alimentation conforme à l'invention,
• la figure 2 est une vue en coupe schématique qui montre les détails d'un mode de réalisation du système d'alimentation conforme à l'invention, et
• la figure 3 est une vue en coupe partielle selon la ligne III-III de la figure 2.

Other advantages, characteristics and details of the invention will emerge from the explanatory description which follows, given with reference to the appended drawings, given solely by way of example, and in which:

• FIG. 1 is a schematic and partial sectional view of a liquid propellant weapon equipped with a supply system according to the invention,
• FIG. 2 is a schematic sectional view which shows the details of an embodiment of the supply system according to the invention, and
• Figure 3 is a partial sectional view along line III-III of Figure 2.

It is schematically represented in the Figure 1, a tube 1 of a medium or large caliber weapon with liquid propellant, with a projectile 2 stationed in the tube 1 at a forcing cone 3, in a manner known per se. The rear end of the tube 1 can be sealed in a sealed manner by a breech obturator 4. A combustion chamber 5 is delimited in the tube 1 between the projectile 2 and the breech obturator 4 in the closed position thereof. .

This liquid propellant weapon is equipped with an injection system according to the invention, for injecting under pressure into the chamber 5 a determined quantity of a propellant, such as a propellant in liquid or gelled form.

The injection system is housed in a body 6 attached around the tube 1 and fixed to the latter by means of a nut 7 for example. A longitudinal channel 8 is drilled in the body 6, parallel to the axis of the tube 1, and a cylinder 9 is defined between two bottoms 10 and 11 inside this channel 8. The two bottoms 10 and 11 are respectively constituted by a cylindrical element adjustable in axial position inside the channel 8 and which seals one end of it, and by a plug which seals the other end of channel 8.

A pressure multiplier piston 15 is slidably mounted inside the cylinder 9. A chamber 16 with variable volume is delimited between the piston 15 and the bottom 10 of the cylinder 9. A second chamber 17, with variable volume is delimited between the piston 15 and the other bottom 11 of the cylinder 9. An axial stop 18 integral with the bottom 11 projects inside the second chamber 17 and on which the piston 15 is supported when the chamber 16 contains the amount of propellant necessary for firing the projectile 2.

An inlet pipe 20 communicates the second chamber 17 of the cylinder 9 with the chamber 5 of combustion. This inlet pipe 20 is constituted by a radial channel pierced in the body 6 and the wall of the tube 1.

An outlet pipe 21 communicates the first chamber 16 of the cylinder 9 with the combustion chamber 5. This outlet pipe 21 is constituted by a second blind longitudinal channel 22 pierced in the body 6, parallel to the first channel 8, by connecting channels 23 which each open into the chamber 16 and into the second channel 21, and by a channel radial 24 which opens into the combustion chamber 5 and into the second channel 21.

A pressure-controlled valve 25 is mounted at the passage section between the two channels 22 and 24 of the outlet pipe 21. The valve 25 comprises a shutter 26 formed by a tubular element, one end face of which or front face is closed by a bottom wall 27 which is pierced with a central opening 28. The shutter 26 is slidably mounted, in a leaktight manner, in the second longitudinal channel 22, by being introduced into it by its face before so that its bottom wall 27 can come to bear on an annular seat 29 machined in the body 6 around the end of the second channel 22 which opens into the radial channel 24.

A piston 30, centered and mounted to slide in leaktight manner inside the shutter 26, is supported on the end of a rod 31 which extends a plug 32 which non-sealingly closes the open end of the second channel 22 which opens to the rear face of the body 6. A return spring 33 attached around the rod 31 urges the shutter 26 to bear on its seat 29, so as to close the passage section between the second channel 22 and the radial channel 24 of the outlet pipe 21.

It should be noted that a room 35 is delimited inside the shutter 26 between the bottom wall 27 and the piston 30, when the valve 25 is closed. This chamber 35 communicates with the channel 22 through the opening 28 of the bottom wall 27 of the shutter 26. Under these conditions, the return force of the spring 33 to keep the valve 25 closed should only be greater than the difference of the forces exerted by the propellant, contained in the channel 22 and in the chamber 35, on the two opposite faces of the bottom wall 27 of the shutter.

Damping means 40 are housed inside the cylinder 9 in the vicinity of the cylinder bottom 10, for damping and braking the movement of the piston 15 at the end of the stroke.

Referring to FIGS. 1 and 2, these damping means 40 comprise a rod or core 41 carried by the cylinder bottom 10 and which projects inside the chamber 16, and a cavity 42 of corresponding shape and size, formed on the piston 15 and intended to receive the core 41 at the end of the piston 15 stroke. Adjustment means 45 are provided for adjusting the length of the core 41 projecting inside the chamber 16 as a function of the speed reached by the piston 15 at the end of the stroke, means which will be described in detail with reference to the embodiment illustrated in FIG. 2.

The bottom of the cylinder 10 is constituted by a tubular element 10a which is screwed into the channel 8, the corresponding threads being referenced at 43. The core 41 is screwed inside the tubular element 10a, the corresponding threads being referenced at 44, these threads being tighter than the threads 43. A sleeve 46 is housed inside the tubular element 10a, and it extends over a length less than that of the latter. This sleeve 46 projects in part outside the channel 8, and it is integral with a pinion 46a driven in rotation by a crown 47, itself driven in rotation by a motor member not shown. The tubular element 10a is integral in rotation with the sleeve 46 by a key 47 which engages freely in a longitudinal groove 48 extending along the external wall of the sleeve 46. A tube 50 is mounted inside the sleeve 46 with one end which rotatably supports the pinion 46a and which is fixed to a plate 51 secured to the body 6 by screws 52 for example. Towards its other end, the tube 50 has an axial opening 55 of rectangular section and in which is slidably mounted a rod 56, of corresponding section, which is integral with the core 41.

Thus, the adjustment means 45 will ensure both the axial positioning of the cylinder bottom 10 to vary the volume of the chamber 16 of the cylinder 9, and the movement of the core 41 inside the chamber 16 to adjust its protruding length in chamber 16.

The bottom of the cylinder 10 has a reduction in diameter at its end by which the core 41 projects. This reduction in diameter makes it possible to accommodate at least one end-of-travel damping ring 60 on which a sleeve 61 forming a stop is supported and retained by a nut 62.

The chamber 16 of the cylinder 9 is supplied with propellant through a channel 63 which opens into the chamber 16. This channel 63 is connected to a reservoir (not shown) with the interposition of a non-return valve.

There will now be described the operation of the supply system described above.

Before firing the projectile 2 placed in the tube 1, the volume of the chamber 16 forming a reservoir is adjusted to store the quantity therein. total of propellant necessary for firing the projectile 2. This operation consists in adjusting the axial position of the cylinder bottom 10 by actuating the adjustment means 45 which also adjust the protruding length of the core 41 inside the room 16.

Once these adjustments have been made, the propellant is sent under low pressure to the chamber 16 through the intake channel 63. The propellant spreads into the chamber 16, as well as in the outlet pipe 21. The pressure of the propellant is sufficient to cause the piston 15 to recede in the direction of the support stop 18, but it is insufficient to cause the opening of the valve 25, the shutter 26 of which remains in contact with its seat 29 to prevent the propellant from moving towards the combustion chamber 5. A small quantity of propellant is then injected and then ignited directly in the combustion chamber 5. The combustion gases penetrate inside the second chamber 17 of the cylinder 9 through the inlet pipe 20. The pressure of these gases is insufficient to cause the projectile 2 to be ejected, but is sufficient to move the piston 15 to inside the cylinder 9. As it moves, the piston 15 compresses the propellant contained in the chamber 16 and the outlet pipe 21. As soon as this pressure has reached a value sufficient to open the valve 25, the agent propulsion under pressure is injected inside the combustion chamber 5. The pressure exerted on the piston 15 increases rapidly, so that the piston 15 reaches a relatively high speed at the end of the stroke. The damping means 40 then come into action, and braking of the piston 15 is obtained by a rolling effect of the propellant contained in the cavity 42 of the piston when the core 41 engages in this cavity 42. The residual energy from the piston 15 is then absorbed by the damping rings 60, when the piston 15 comes into contact with the sleeve 61. The gas pressure inside the combustion chamber 5 is then become sufficient to eject the projectile 2. In general, this ejection of the projectile 2 occurs before the piston 15 reaches its end-of-travel position, to maintain combustion as long as the projectile 2 is at inside of tube 1.

Suppose that one wants to modify the conditions of shooting of a new projectile 2 put in station in the tube 1 of the weapon, to obtain for example a reduction in the range of the shooting. This results in a reduction in the amount of propellant to be injected into the combustion chamber 5. It is therefore necessary to reduce the volume of the chamber 16 by moving the bottom of the cylinder 10 in the direction of the arrow F (Figure 2). For this, the adjustment means 45 are actuated, that is to say that the pinion 46a is rotated in the desired direction for a reduction in the volume of the chamber 16. The rotation of the sleeve 46 causes the rotation of the cylinder bottom 10 which, by the threads 43, moves axially along the arrow F inside the cylinder 9. Simultaneously, the core 41 via the threads 44 by which it is screwed into the cylinder bottom 10 and of the rod 56 which immobilizes it in rotation, moves axially in the same direction F inside the chamber 16 of the cylinder 9, but over a distance of displacement less than that of the bottom of the cylinder 10.

Thus, the reduction in the volume of the chamber 16 results in a protruding length of the core 41 inside the chamber 16 which goes from the value L to a lower value 1 (FIG. 2). Indeed, the volume of the chamber 16 decreasing, the speed of the piston 15 in limit switch will be lower, which requires a lesser hydraulic rolling effect to dampen and brake the piston 15. In other words, the core 41 will protrude into the cavity 42 of the piston 15 over a shorter length. Conversely, in the case of an increase in the volume of the chamber 16 with a higher end-of-travel speed of the piston 15, the core 41 will protrude inside the chamber 16 over a greater length.

In such a liquid propellant weapon, it is advantageously possible to provide several cylinders 8, each chamber 16 of which communicates with the outlet pipe 21 which conveys the propellant towards the combustion chamber 5.

Of course, the invention is in no way limited to the previous embodiment which has been given only by way of example. In particular, at least one variant can be designed at the level of the adjustment means 45 which can be designed so as to move the cylinder bottom and the core in two opposite directions, without excluding the possibility of two different adjustments, one of the 'other. Finally, the application of the invention is not limited to a system for supplying the combustion chamber of a liquid propellant weapon, but in any system whose operating conditions require the delivery of a volume of hydraulic fluid with a predetermined and variable value.

Claims (7)

1. A system to supply a device with a volume of hydraulic liquid having a predetermined value which varies according to the operating conditions, this system comprising a hydraulic jack formed of a piston (15) and a cylinder (9) which marks out with the piston (15) a variable volume chamber (16) connected to the device, means to supply the chamber (16) with pressurized liquid, means to control the movement of the piston (15), such as a pressurized fluid introduced into a cylinder (9) on the opposite side of said chamber, and means (40) to cushion the movement of the piston (15) at the end of its stroke, the speed of the piston at the end of its stroke being variable and being determined by the initial axial length of the afore-mentioned chamber (16), the piston being braked and cushioned by a hydraulic rolling effect, characterised in that the means (40) to cushion the piston (15) at the end of its stroke comprise a rod or sprue (41) carried by the bottom of a cylinder (10) and projecting inside said chamber (16), and a cavity (42) of a corresponding shape and size, formed on the piston (15) and intended to accommodate the sprue (41) at the end of the piston (15) stroke, means (45) being provided in addition to adjust the length of the sprue (41) which projects into said chamber (16) according to the speed reached by the piston at the end of its stroke.
2. A supply system according to Claim 1, characterised in that the cylinder bottom (10), in whose direction the piston (15) moves, is axially mobile so as to adjust the volume of the chamber (16), and in that the means (45) to adjust the length of the sprue which projects into said chamber (16) also ensure the adjustment of the axial position of said cylinder bottom (10).
3. A supply system according to Claim 2, characterised in that the afore-mentioned adjustment means (45) simultaneously ensure the movement of the sprue (41) and the cylinder bottom (10), so that the length of the sprue (41) projecting inside the chamber (16) increases when the volume of the chamber (16) increases.
4. A supply system according to Claim 3, characterised in that the afore-mentioned adjustment means (45) ensure the movement of the sprue (41) and the cylinder bottom (10) in the same direction, but for different lengths of movement.
5. A supply system according to Claim 2, characterised in that the cylinder bottom (10) is formed of a tubular element (10a) screwed into the body (6) of the jack, in that the sprue (41) of the cushioning means (40) is screwed inside said tubular element, the threading required to screw in the sprue (41) being tighter than those required to screw in the cylinder bottom (10), means (50) immobilizing said sprue (41) in rotation, and in that the adjustment means (45) comprise a control device to rotate the cylinder bottom (10).
6. A supply system according to Claim 5, characterised in that the rotation control device comprises a sleeve (46) housed in the tubular element (10a), forming the cylinder bottom (10), and driven in rotation by a pinion (46a), a retainer (47) able to move in a groove (48) to link the sleeve (46) and the cylinder bottom (10) in rotation.
7. A supply system according to Claim 6, characterised in that the means (50) to immobilize the sprue (41) in rotation are formed of a fixed tube (50) which has a rectangular section housed in the sleeve (46) and in which a rod (56) of a matching section and integral with the sprue (41) is mounted sliding.

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