WO2023052656A1

WO2023052656A1 - High pressure compressor system for compressed air or gas rifles or pistols

Info

Publication number: WO2023052656A1
Application number: PCT/ES2021/070711
Authority: WO
Inventors: Julián Arnedo Vera; Antonio Fidel NÚÑEZ MORALES
Original assignee: Gamo Outdoor, S.L.
Priority date: 2021-09-30
Filing date: 2021-09-30
Publication date: 2023-04-06

Abstract

High pressure compressor system for compressed air or gas rifles or pistols, comprising a motor (1) that rotates a shaft (2); characterized in that: — the shaft (2) is connected to at least one crankshaft (32) having at least two crankpins (7, 8), a first crankpin (7) and a second crankpin (8), attached to respective connecting rods (3, 4) that are offset relative to one another, namely - a first connecting rod (3) connected to the first crankpin (7), which is attached to a first pin (9) connected to a first piston (11) which defines a first conduit (17) inside same, ending at a first sleeve (28) defining a first housing (27) connected to a first valve (15), and - a second connecting rod (4) connected to the second crankpin (8), which is attached to a second pin (10), in turn connected to: • a second piston (12), and • a second sleeve (13), said second sleeve (13) surrounding the first piston (11), and at least partially surrounding the second piston (12) and both crankpins (7, 8), said second sleeve (13) being connected to the first sleeve (28) and comprising through-holes (5, 6) for the fluid to pass into the second sleeve (13); and — it comprises at least one guide tube (14, 19) that surrounds the second sleeve (13) and, at least partially, the second piston (12), and a second valve (16) that defines a fluid inlet into the second sleeve (13).

Description

HIGH PRESSURE COMPRESSOR SYSTEM FOR COMPRESSED AIR OR GAS RIFLES OR GUNS.

DESCRIPTION

High-pressure compressor system for compressed air or gas carbines or pistols, of the type that comprises a motor that rotates a shaft characterized in that: said shaft is connected to at least one crankshaft with at least two crankpins, a first crankpin and a second crankpin, respectively linked each one to connecting rods, out of phase with each other: a first connecting rod connected to the first crankpin, which is joined to a first pin connected to a first piston that defines a first conduit inside it and which ends in a first sleeve that defines a first housing connected to a first valve, a second connecting rod connected to the second crank pin, which is joined to a second pin connected to: a second piston, and a second sleeve, said second sleeve surrounding the first piston, the at least partially to the second piston and to the two pins, that said second jacket is connected to the first jacket, and that it includes openings for the passage of the fluid inside the second jacket, and because it comprises at least one guide tube that surrounds the second jacket and at least partially the second piston, and a second valve that defines a fluid inlet inside the second jacket; that when the shaft rotates by action of the motor in a first phase: it moves the second pin that drags the second connecting rod in a direction towards the axis and said second connecting rod moves the second piston in a direction towards the axis, opening the second valve allowing the entrance of fluid inside the second sleeve and, the second piston drags the second sleeve in the same direction of advance as the second connecting rod, and moves the first pin that drags the first connecting rod in a direction towards the axis and said first connecting rod moves the first piston in a direction towards the axis defining a second housing between the second jacket and the first piston, likewise making the fluid from the second jacket pass through the first conduit to the second housing, and dragging said second jacket to the first jacket, compressing the first housing that pushes the fluid towards the first valve through which the pressurized fluid exits; and when the shaft continues to rotate due to the action of the motor in a second phase: it moves the second pin that drives the second connecting rod in the opposite direction to the axis and said second connecting rod moves the second piston in the opposite direction to the axis, closing the second valve preventing the gas inlet inside the second sleeve and the second piston drags the second sleeve in the same direction of advance as the second connecting rod, and moves the first pin that drags the first connecting rod in the opposite direction to the axis and said first connecting rod moves the first piston in the opposite direction to the axis, reducing the volume of the second housing and compressing the fluid inside it, also making the fluid pass from the second housing to the first housing, leaving the fluid pre-charged to exit through the first valve when it turns again the shaft by motor action.

BACKGROUND OF THE INVENTION

In the state of the art, different systems are known that comprise compressors to drive pellets in carbines or sports pistols, also known as compressed air or gas.

Thus, the German Patent DE4212623 "DRUCKLUFTWAFFE", from 1992, in the name of ANSCHUETZ GMBH JG, which refers to a compressed air rifle that has an electric motor that works by means of a battery with a compressor, belongs to the state of the art. gears and electronic circuitry supported by an in-line casing under the barrel. The air rifle has a continuous or reciprocating compressor, driven by an electric motor, to provide the compressed air for the propulsion of the pellet. Between the motor and the compressor there is a gear. The motor is a DC motor and is powered by a battery. The motor, compressor, gears, battery, and control electronics are all in-line and mounted in a housing below the cylinder. The battery is held in a quick change adapter. There is a pressure sensor that shuts off the engine when the pressure is reached. required propulsion pressure. The motor is started by a trip contact with a delay circuit. ADVANTAGE - Simple low loss design.

The French Patent FR2681674 "DISPOSITIF DE REARMEMENT ET ARME A AIR COMPRIME AINSII EQUIPE", of the year 1991, in the name of Mr. Pierre DORVAL, which refers to a pneumatic piston that can move to compress air in a pneumatic chamber until it is released, is also known. action on the trigger allows air to pass into an area of the barrel behind a projectile. A battery-powered electric motor is driven by a reduction gear, with a hydraulic pump housed in an oil reservoir. The pump discharges into a hydraulic chamber through a distributor. The hydraulic chamber is separated from the pneumatic chamber by the piston. The distributor can be moved between a chamber filling position, a position to keep oil in the chamber, and a position to return oil to the reservoir. Its application is in compressed air pistols used for sporting purposes.

BRIEF DESCRIPTION OF THE INVENTION

The present invention falls within the field of air or gas firing mechanisms.

The closest document is the German Patent DE4212623.

It is known to connect a pressure cartridge to the airgun, particularly in the case of airsoft guns, which provides compressed air for a predetermined number of shots, where the clamping lever is eliminated.

However, the balance of the weapon depends on the fill level of the pressure cartridge. Therefore, said German invention solves the problem by motorizing the continuously operating pump, that is, a rotary compressor or a pulsating compressor with its drive motor being integrated into the weapon for the first time. This results in low mechanical losses and a particularly simple structure.

On the other hand, it has the drawback that if a high-pressure compressed air source is required (for example, between 60 and 120 bar), with a low flow rate per second and low weight, the compressors currently on the market They do not adapt to the requirements and add a lot of weight to the rifle or air or gas pistol. In addition, there is also the added effect that there are a lot of vibrations at the time of the shot, which results in the reliability of the shot.

The present invention solves the aforementioned problem by means of a compressor system that includes a double compression stage, which makes it reach the required pressures, with a mechanism that is both statically and dynamically balanced, which minimizes vibrations at the time of firing. , being all of it of a reduced size ideal for its installation in a carbine or pistol, also reducing the weight and being therefore suitable for its integration in a compressed air or gas weapon.

An object of the present invention is a high-pressure compressor system for compressed air or gas carbines or pistols, of the type that comprises a motor that rotates a shaft characterized in that: said shaft is connected to at least one crankshaft with at least two crankpins, a first crankpin and a second crankpin, each connected respectively to connecting rods, out of phase with each other: a first connecting rod connected to the first crankpin, which is connected to a first pin connected to a first piston defining a first conduit inside and ending in a first sleeve that defines a first housing connected to a first valve, a second connecting rod connected to the second crankpin, which is joined to a second pin connected to: a second piston, and a second sleeve, wrapping said second sleeve to the first piston, at least partially to the second piston already the two crank pins, that said second jacket is connected to the first jacket, and that it includes openings for the passage of the fluid into the second jacket, and that it comprises at least one guide tube that surrounds the second jacket and at least partially the second piston, and a second valve that defines a fluid inlet inside the second jacket; that when the shaft rotates by action of the motor in a first phase: it moves the second pin that drags the second connecting rod in a direction towards the axis and said second connecting rod moves the second piston in a direction towards the axis, opening the second valve allowing the entrance of fluid inside the second sleeve and, the second piston drags the second sleeve in the same direction of advance as the second connecting rod, and moves the first pin that drags the first connecting rod in a direction towards the axis and said first connecting rod moves the first piston in a direction towards the axis defining a second housing between the second jacket and the first piston, likewise making the fluid from the second jacket pass through the first conduit to the second housing, and dragging said second jacket to the first jacket, compressing the first housing that pushes the fluid towards the first valve through which the pressurized fluid exits; and when the shaft continues to rotate due to the action of the motor in a second phase: it moves the second pin that drives the second connecting rod in the opposite direction to the axis and said second connecting rod moves the second piston in the opposite direction to the axis, closing the second valve preventing the gas inlet inside the second sleeve and the second piston drags the second sleeve in the same direction of advance as the second connecting rod, and moves the first pin that drags the first connecting rod in the opposite direction to the axis and said first connecting rod moves the first piston in the opposite direction to the axis, reducing the volume of the second housing and compressing the fluid inside it, also making the fluid pass from the second housing to the first housing, leaving the fluid pre-charged to exit through the first valve when it turns again the shaft by motor action.

BRIEF DESCRIPTION OF THE DRAWINGS In order to facilitate the explanation, six sheets of drawings are attached to this report in which a practical case of realization has been represented, which is cited by way of example, not limiting the scope of the present invention:

- Figure 1 is a general view of the object of the invention with the first valve facing the first piston,

- Figure 2 is a view of a longitudinal section along the line ll-ll of Figure 1,

- Figure 3 is a cross-sectional view along the line lll-lll of Figure 1,

- Figure 4 is a cross-sectional view along the line ll-ll of Figure 1, assuming that the valve was located above the axis,

- Figure 5 is a cross-sectional view along the line ll-lll of Figure 1, in its first movement, assuming that the valve was located above the axis, and

- Figure 6 is a cross-sectional view along the line ll-lll of Figure 1, in its second movement, assuming that the valve is located above the axis.

CONCRETE PERFORMANCE OF THE PRESENT INVENTION

Thus, in figure 1 an engine 1, a base 21, a cylinder head 23 and a guide tube 14 are illustrated.

Figure 2 represents the engine 1 with its shaft 2, a crankshaft 32, a first connecting rod 3, a second connecting rod 4, a first crank pin 7, a second crank pin 8, a first pin 9, a second pin 10, a first piston 11, a second piston 12, a first sleeve 28, a second sleeve 13, an intermediate support 31, some through holes 5, 6, guide tubes 14, 19, a first valve 15, a second valve 16, a first conduit 17, a second conduit 18, the bench 21, a receptacle 22, the cylinder head 23, a first reed valve 25, a second reed valve 26, a first housing 27, a passage 29 and a fixed piston 30.

Figure 3 shows the first connecting rod 3, the second connecting rod 4, the first pin 7, the second pin 8, the first pin 9, the second pin 10, the first piston 11, the second piston 12, the second sleeve 13 , the intermediate support 31, the guide tubes 14, 19, the first valve 15, the second valve 16, the first conduit 17, the bench 21, the receptacle 22, the cylinder head 23, the first sleeve 28, the first reed valve 25, the second reed valve 26, the first housing 27, the passage 29 and the fixed piston 30.

Figure 4 shows the engine 1 with its axis 2, the crankshaft 32, the first connecting rod 3, the second connecting rod 4, the first pin 7, the second pin 8, the first pin 9, the second pin 10, the the first piston 11, the second piston 12, the second sleeve 13, the intermediate support 31, the through holes 5,6, the guide tubes 14,19, the first valve 15, the second valve 16, the first conduit 17, the second conduit 18, a second housing 20, the base 21, a deposit 24, the receptacle 22, the first jacket 28, the first housing 27, the passage 29 and the fixed piston 30.

Figure 5 shows the axis 2, the first connecting rod 3, the second connecting rod 4, the first pin 7, the second pin 8, the first pin 9, the second pin 10, the first piston 11, the second piston 12 , the second jacket 13, the intermediate support 31, the guide tubes 14, 19, the first valve 15, the first conduit 17, the second housing 20, the bench 21 and the receptacle

22, the first sleeve 28, the first housing 27, the passage 29 and the fixed piston 30.

Finally, figure 6 shows axis 2, the first connecting rod 3, the second connecting rod 4, the first pin 7, the second pin 8, the first pin 9, the second pin 10, the first piston 11, the second piston 12, the second jacket 13, intermediate support 31, guide tubes 14, 19, the first valve 15, the first duct 17, the second housing 20, the base plate 21 and the receptacle 22, the first jacket 28, the passage 29 and the fixed piston 30.

Thus, the high-pressure compressor system of the present invention includes a motor 1 that rotates a shaft 2 and this rotates the crankshaft 32, which includes crankpins 7,8 and connecting rods 3,4.

Said axis 2 is connected to crankpins 7, 8, which are each linked to a respective connecting rod 3, 4, said connecting rods (first connecting rod 3 and second connecting rod 4) being out of phase with each other, that is, there is a delay until the second connecting rod 4 is in the same position as the first connecting rod 3.

The first connecting rod 3 is attached to a first pin 9 and said first pin 9 is connected to a first piston 11 that defines a first conduit 17 inside, for the passage of fluid and that ends in a first sleeve 28 that configures a first housing 27 which in turn connects with the first valve 15.

The second connecting rod 4 is attached to a second pin 10 and said second pin 10 is connected in turn with two elements: with a second piston 12, and with a second sleeve 13, which surrounds said second sleeve 13 to the first piston 11, to the less partially to the second piston 12 and to the pin 7; and it is also connected to the first jacket 28, also comprising through holes 5, 6 for the passage of fluid into the second jacket 13.

It also comprises at least one guide tube 14, 19 that surrounds the second jacket 13 and, at least partially, the second piston 12.

It also comprises a second valve 16 that defines the fluid inlet inside the second jacket 13. Thus, when the axis 2 rotates due to the action of the engine 1 in a first phase, two actions are produced in the crankshaft 32:

On the one hand, axis 2 moves the second pin 7 that drives the second connecting rod 4 in the direction towards axis 2 and said second connecting rod 4 moves the second piston 12 in the direction towards axis 2, opening the second valve 16 allowing the entry of fluid inside the guide tube 19 and the second piston 12 drags the second sleeve 13 in the same direction of advance as the second connecting rod 4.

On the other hand, axis 2 moves the first pin 7 that drives the first connecting rod 3 in the direction towards axis 2 and said first connecting rod 3 moves the first piston 11 in the direction towards axis 2 defining between the second sleeve 13 and the first piston 11 a second housing 20 for the fluid, likewise passing the fluid from the second jacket 13 through the first conduit 17 to the second housing 20.

In addition, said second jacket 13 drags the first jacket 28, compressing the first housing 27 that pushes the fluid towards the first valve 15 through which the pressurized fluid comes out.

And, when axis 2 continues to rotate due to the action of motor 1 in a second phase, two actions are produced:

On the one hand, axis 2 moves the second pin 8 that drives the second connecting rod 4 in the opposite direction to axis 2 and said second connecting rod 4 moves the second piston 12 in the opposite direction to axis 2, closing the second valve 16 preventing the gas inlet inside the second sleeve 13 and the second piston 12 drags the second sleeve 13 in the same direction of advance as the second connecting rod 4. On the other hand, axis 2 moves the first pin 7 that drives the first connecting rod 3 in the opposite direction to axis 2 and said first connecting rod 3 moves the first piston 11 in the opposite direction to axis 2, reducing the volume of the second housing 20 and compressing the fluid inside, also making the fluid pass from the second housing 20 to the first housing 27, leaving, then, the pre-charged fluid to exit through the first valve 15 when the shaft 2 rotates again by action of the motor 1.

The first crankpin 7 is linked to the first connecting rod 3 and the second crankpin 8 to the second connecting rod 4. In addition, the second sleeve 13 envelops the crankpins 7,8 at least partially. When the aforementioned axis 2 rotates by action of the motor 1 in a first phase: on the one hand, it moves the second pin 8 that drags the second connecting rod 4 in the direction of axis 2 and on the other hand it moves the first pin 7 that drags to the first connecting rod 3 in the direction towards axis 2.

In this way, when axis 2 continues to rotate due to the action of motor 1 in a second phase: it moves the second crankpin 8 that drives the second connecting rod 4 in the opposite direction to axis 2, and moves the first crankpin 7 that drives the first connecting rod 3 in the opposite direction to axis 2.

As previously noted the connecting rods 3,4 are out of phase with each other. The inventors have studied that the effects are very significant if the phase difference is between 170-190°, more specifically, very optimal results have been found if the connecting rods 3,4 are approximately 180° phased with each other.

The possibility of configuring a receptacle 22 that stores the fluid coming from the second valve 16, in this way the fluid supply is faster, has also been provided for the possibility of configuring inside the second jacket 13, partially enveloping the crankpins 7, 8. and followed. Optionally, the system can comprise a frame 21 that surrounds at least partially the guide tube 14, 19, the motor 1, the axis 2, and the second jacket 13.

There is the possibility that the second piston 12 defines a second conduit 18 inside it and that it ends in the second valve 16 (figure 2), connecting the fluid from the second valve 16 with the inside of the second jacket 13.

It could also be arranged, optionally, for the second valve 16 to be a ball valve for its simplicity, as shown in figures 2 and 3, even though this does not exclude the use of other valves that can be found. most pertinent according to the pistol or carbine.

Constructively, the second valve 16 can be arranged as indicated in figures 1 to 3, that is, after the second connecting rod 4 or that it is located above the second sleeve 13, figures 4 to 6.

Optionally, it can be configured that the first jacket 25 and the second jacket 13 form a single piece or that the first jacket 25 is joined to the second jacket 13 by an intermediate support 31 that includes the passage 29, as shown in the figures 2 to 6.

This last possibility of joining the first jacket 25 with the second jacket 13 by an intermediate support 31 would require that the first housing 27 be connected to the second housing 20 through a passage 29 through which the fluid passes from one housing to the other and the first reed valve 25.

It could also comprise a second reed valve 26, at the outlet of the first conduit 17, connected to the first piston 11, and facing the passage 29, in such a way that said second reed valve moves with the first piston 11. Said reed valves 25,26 allow the fluid to go in one direction, from the second housing 20 to the first housing 27, but prevents the opposite direction, that is, said reed valves 25,26 do not allow the transfer of fluid from the first housing 27 to the second housing 20 or into the first conduit 17.

Also, optionally, constructively it can be arranged that the first valve 15 forms part of a fixed piston 30.

There is also the possibility that the fixed piston 30 is connected to the guide tube 14, since said guide tube 14 is immobile with respect to the axis 2.

In this embodiment, the option of two 7.8 crankpins will be given as an example, although, as explained above, it could be done with more than two crankpins.

Two possible embodiments are indicated below, a first with the fluid inlet through the second valve 16 as indicated in figures 1 to 3, where the second valve 16 is in the same plane as the crankpins 7, 8, or a second one with the fluid inlet through the second valve 16 that is located above the crank pins 7, 8 (figures 4 to 6).

The operation is essentially the same, what varies is the interaction of the second piston 16, since in the case of figures 1 to 3 it is necessary to have a second conduit 18 made in the second piston 16 for the passage of the fluid inside. of the second sleeve 13, and on the contrary, in the case of figures 4 to 6, said second piston 16 does not need to have any second conduit 18, since the fluid does not enter the second sleeve 13 through that area, but rather it does it for the upper part of the second shirt 13. The fluid, for example, atmospheric air or CO2, enters through the second valve 16 in the tank 24, which is formed by the tube 19 and the piston 12.

When the second piston 12 advances away from the axis 2, dragging the second sleeve 13, towards the cylinder head 23, the first piston 11 advances away from the axis 2, in the opposite direction to the second piston 12, in the direction of the first valve 15, compressing the fluid that leaves through the second conduit 18 and is discharged in the receptacle 22.

This creates a pressure, higher than atmospheric, inside the compressor body that improves the filling of the second housing 20 when the second piston 11 moves away from the axis 2.

When the first piston 11 moves away from the axis 2 and the second sleeve 13, in the opposite direction by the action of the second piston 12 to which it is connected, the fluid compressed in the second housing 20 is compressed again and is discharged in the first housing. 27.

When the movement of the first piston 11 and the second piston 12 with the second sleeve 13 is reversed again by the action of the pins 7, 8, the fluid stored in the first housing 27 is compressed again and exits through the first valve. 15 to later serve for the shot of the pellet.

The present invention describes a new high-pressure compressor system for compressed air or gas rifles or pistols. The examples mentioned here are not limiting of the present invention, therefore it may have different applications and/or adaptations, all of them within the scope of the following claims.

Claims

1.- High-pressure compressor system for compressed air or gas rifles or pistols, of the type that comprises a motor (1) that rotates a shaft (2) characterized in that:

- Said shaft (2) is connected to at least one crankshaft (32) with at least two crankpins (7, 8), a first crankpin (7) and a second crankpin (8), each connected respectively to connecting rods (3,4), out of phase with each other:

- A first connecting rod (3) connected to the first crankpin (7), which is attached to a first pin (9) connected to a first piston (11) that defines a first conduit (17) inside it and that ends in a first jacket (28) defining a first housing (27) connected to a first valve (15),

- a second connecting rod (4) connected to the second crank pin (8), which is joined to a second pin (10) connected to:

■ a second piston (12), and

■ a second jacket (13), wrapping said second jacket (13) to the first piston (11), at least partially to the second piston (12) and to the two pins (7,8), which is connected to said second jacket (13) to the first jacket (28), and comprising some openings (5,6) for the fluid inside the second jacket (13),

- and because it comprises at least one guide tube (14, 19) that surrounds the second jacket (13) and at least partially the second piston (12), and a second valve (16) that defines a fluid inlet inside the the second shirt (13); that when the shaft (2) rotates by action of the motor (1) in a first phase:

- moves the second pin (8) that drives the second connecting rod (4) in the direction towards the axis (2) and said second connecting rod (4) moves the second piston (12) in a direction towards the axis (2), opening the second valve (16) allowing the entry of fluid inside the second sleeve (13) and, the second piston (12) drags the second sleeve (13) in the same direction of advance as the second connecting rod (4), and

- moves the first crank pin (7) that drives the first connecting rod (3) in the direction towards the axis (2) and said first connecting rod (3) moves the first piston (11) in the direction towards the axis (2) defining between the second jacket (13) and the first piston (11) a second housing (20), likewise making the fluid from the second jacket (13) pass through the first conduit (17) to the second housing (20), and dragging said second jacket (13) to the first jacket (28), compressing the first housing (27) that pushes the fluid towards the first valve (15) through which the pressurized fluid exits; and when the shaft (2) continues to rotate due to the action of the motor (1) in a second phase:

- moves the second pin (8) that drives the second connecting rod (4) in the opposite direction to the axis (2) and said second connecting rod (4) moves the second piston (12) in the opposite direction to the axis (2), closing the second valve (16) preventing the entry of gas inside the second sleeve (13) and, the second piston (12) drags the second sleeve (13) in the same direction of advance as the second connecting rod (4), and

- displaces the first pin (7) that drives the first connecting rod (3) in the opposite direction to the axis (2) and said first connecting rod (3) moves the first piston (11) in the opposite direction to the axis (2) reducing the volume of the second housing (20) and compressing the fluid inside, also making the fluid pass from the second housing (20) towards the first housing (27), leaving the fluid pre-charged to exit through the first valve (15) when it turns again the shaft (2) by action of the motor (1).

2. System according to claim 1, characterized in that the connecting rods (3,4) are out of phase with each other between 170-190°. 16

3. System according to claim 2, characterized in that the connecting rods (3,4) are 180° out of phase with each other.

4. System, according to claim 1, characterized in that inside the second jacket (13), partially enveloping the crankshafts, a receptacle (22) is configured that stores the fluid from the second valve (16). .

5. System according to claim 1, characterized in that it comprises a bench (21) that envelops at least partially:

- to the guide tube (14, 19),

- to the engine (1),

- to the axis (2), and

- to the second shirt (13).

6. System according to claim 5, characterized in that the second piston (12) defines a second conduit (18) inside it and which ends in the second valve (16).

7. System according to claim 6, characterized in that the second valve (16) is a ball valve.

8. System according to claim 7, characterized in that the second valve (16) is located above the second sleeve (13).

9. System according to claim 1 7, characterized in that the first sleeve (28) and the second sleeve (13) form a single piece.

10. System according to claim 1, characterized in that the first housing (27) is connected to the second housing (20) by a passage (29) through which the fluid passes from one housing to another. 17

11. System according to claim 10, characterized in that the first sleeve (25) is attached to the second sleeve (13) by an intermediate support (31) comprising the passage (29) and the first reed valve ( 25).

12.- System according to claim 11, characterized in that it comprises a second reed valve (26) at the outlet of the first conduit (17), attached to the first piston (11) and facing the passage (29) moving said second reed valve (26) with said first piston (11).

13. System according to claim 1, characterized in that the first valve (15) is part of a fixed piston (30).

14. System according to claim 13, characterized in that the fixed piston (30) is connected to the guide tube (14).