EP0619868A1

EP0619868A1 - Piston cushioning in a gun using a liquid propellant charge.

Info

Publication number: EP0619868A1
Application number: EP93924658A
Authority: EP
Inventors: Michel Begneu
Original assignee: Giat Industries SA
Current assignee: Giat Industries SA
Priority date: 1992-11-02
Filing date: 1993-10-29
Publication date: 1994-10-19
Anticipated expiration: 2013-10-29
Also published as: NO942503D0; FR2697624A1; WO1994010522A1; EP0619868B1; NO942503L; US5533434A; FR2697624B1; DE69308536D1

Abstract

Système d'alimentation d'un dispositif, tel que la chambre (5) de combustion du tube (1) d'une arme à propulseur liquide, comprenant un vérin hydraulique constitué d'un piston (15) et d'un cylindre (9) déterminant avec le piston une chambre (16) à volume variable reliée à la chambre (5) de combustion par une canalisation de sortie (21), et des moyens amortisseurs (40) constitués d'une carotte (41) qui fait saillie à l'intérieur de la chambre (16), et d'une cavité (42) formée dans le piston (15) pour amortir le mouvement du piston (15) en fin de course par un effet de laminage du fluide hydraulique. Des moyens de réglage (45) permettent de régler la longueur de la carotte (41) en saillie à l'intérieur de la chambre (16) en fonction du volume de celle-ci.System for supplying a device, such as the combustion chamber (5) of the tube (1) of a liquid propellant weapon, comprising a hydraulic cylinder consisting of a piston (15) and a cylinder (9 ) determining with the piston a chamber (16) of variable volume connected to the combustion chamber (5) by an outlet pipe (21), and damping means (40) consisting of a core (41) which protrudes at inside the chamber (16), and a cavity (42) formed in the piston (15) to damp the movement of the piston (15) at the end of the stroke by a rolling effect of the hydraulic fluid. Adjustment means (45) make it possible to adjust the length of the sprue (41) projecting inside the chamber (16) as a function of the volume of the latter.

Description

DAMPING OF THE PISTON OF A LIQUID PROPULSIVE LOAD CANNON.

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.

In general, 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 and expensive.

The object of the invention is to design a supply system of the aforementioned type and in which the means for damping the piston at the end of the stroke are designed to take account of operating conditions which may have to be modified, these modifications n 'not involving the replacement of the cylinder and / or damping means, the latter being designed for variable speeds reached by the piston at the end of the stroke.

To this end, the invention provides a supply system of the aforementioned type and which is characterized in that the speed of the piston at the end of the stroke being variable and determined by the initial axial length of the chamber of the aforementioned jack, the means d damping of the piston at the end of the stroke comprises a rod carried by a bottom of the cylinder and protruding inside said chamber, and a cavity of corresponding shape and size, formed on the piston and intended to receive the rod at the end stroke of the piston to brake and dampen the movement of the latter by a hydraulic rolling effect, means being further provided for adjusting the length of the rod projecting into said chamber as a function of the speed reached by the piston at the end of race.

According to another characteristic of the invention, the bottom of the cylinder of the jack in the direction of which the piston moves, is axially movable to adjust the initial volume of the chamber, and in that the means for adjusting the length of the rod of the damping means projecting inside said chamber, also ensure the adjustment of the position of the bottom of the aforementioned cylinder. 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.

As a variant, 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. So a power system according to

1 invention can be easily adapted to operating conditions which may vary from one application to another, without requiring complex equipment and delicate 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.

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 thereof, and by a plug which seals the other end of the channel 8. A multiplier piston 15 pressure is slidably mounted inside the cylinder 9. A chamber 16 of variable volume is delimited between the piston 15 and the bottom 10 of the cylinder 9. A second chamber 17, of 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 protrudes inside the second chamber 17 and on which the piston 15 is supported when the chamber 16 contains the quantity of propellant necessary for firing the projectile 2. A e inlet pipe 20 makes the second chamber 17 of the cylinder 9 communicate 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, to dampen and brake 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 displacement of the core 41 inside the chamber 16 to adjust its protruding length in the 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 does not reach its end-of-travel position, to maintain combustion as long as the projectile 2 is inside the 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 (FIG. 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 decrease in the volume of the chamber

16 results in a protruding length of the core 41 inside the chamber 16 which changes 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

1. 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 chamber variable volume 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 of the movement of the piston at the end of the stroke, characterized in that the speed of the piston (15) at the end of the stroke being variable and determined by the initial axial length of the chamber

(16) mentioned above, the damping means (40) of the piston at the end of the stroke comprise a rod or core (41) carried by a cylinder bottom (10) and projecting inside said chamber (16), and a cavity (42) of corresponding shape and dimension, formed on the piston (15) and intended to receive the core (41) at the end of the stroke of the piston (15) to brake and dampen the movement of the latter by a hydraulic rolling effect, means (45) being furthermore provided for adjusting the length of the core (41) projecting into said chamber (16) as a function of the speed reached by the piston (15) at the end of the stroke .

2. Supply system according to claim 1, in which the cylinder bottom (10) in the direction of which the piston (15) moves is axially movable to adjust the volume of the chamber (16), and in that the means adjusting (45) the length of the core (41) projecting inside said chamber (16) also ensure the adjustment of the axial position of said cylinder bottom (10).

3. Feeding system according to the Claim 2, characterized in that the above-mentioned adjustment means (45) simultaneously move the core (41) and the cylinder bottom (10) so that the length of the core (41) projects the interior of the chamber (16) increases as the volume of the chamber (16) increases.

4. Supply system according to claim 3, characterized in that the aforementioned adjustment means (45) ensure the displacement of the core (41) and of the cylinder bottom (10) in the same direction, but over lengths of different displacement.

5. Supply system according to claim 2, characterized in that the cylinder bottom (10) consists of a tubular element (10a) screwed into the body (6) of the jack, in that the core (41) of the damping means (40) is screwed inside said tubular element, the threads necessary for screwing the core (41) being tighter than those necessary for screwing the bottom of the cylinder (10), means (50) immobilizing in rotation said core (41), and in that the adjustment means (45) comprise a device for controlling the rotation of the cylinder bottom (10).

6. Supply system according to claim 5, characterized in that the rotation control device comprises a sleeve (46) housed in the tubular element (10a), forming the bottom of the cylinder (10), and driven in rotation by a pinion (46a), a key (47) movable in a groove (48) to link in rotation the sleeve (46) and the bottom of the cylinder (10).

7. Feeding system according to claim 6, characterized in that the means (50) for immobilizing in rotation the core (41) consist of a fixed tube (50) of rectangular section housed in _the sleeve E (46), and wherein ^t are slidably mounted a rod (56) integral complementary section of the core ^(41).