Cylinder degassing unit and working cylinder

Abstract

The present invention relates to a cylinder degassing unit, comprising a base body, an inner discharge part, an annular chamber and an outer discharge part, the base body being designed to be placed in a positionally fixed manner on the working cylinder in the wall perforations of the cylinder residual air space and having a concave contour forming the annular chamber, the inner discharge part having an inner discharge channel and an inner elastomeric annular body, the inner discharge channel being arranged in the base body, connecting the cylinder residual air space to the annular chamber and having an inner inlet in the cylinder residual air space and an intermediate outlet (2.4) in the annular chamber, the inner elastomeric annular body being The present invention relates to a cylinder degassing unit, comprising: an outer discharge part having an outer discharge channel and an outer elastomeric annular body, the outer discharge channel being arranged in the base body, connecting the annular chamber to the outside atmosphere, having an intermediate inlet in the cylinder residual air space and an external outlet in the annular chamber, the outer elastomeric annular body being designed to cover the external outlet, being preloaded and forming a second pressure barrier in the outlet direction and a second sealing surface in the inlet direction.

Description

[Technical Field]

[0001] The present invention relates to a cylinder degassing unit for venting an actuation cylinder, and to an actuation cylinder equipped with such a cylinder degassing unit. [Background technology]

[0002] In particular, for single-acting lift or pull cylinders, i.e., actuating cylinders that are hydraulically actuated in only one direction and can return to their starting position under load or controlled by spring force, dissolved gases and moisture can enter the empty working chamber through the piston seal under the high pressure of the hydraulic medium. This is further exacerbated by the negative pressure created in the empty working chamber during the return stroke of the piston as it undergoes a volume change due to the piston's stroke.

[0003] Therefore, it is necessary to re-ventilate the empty working chamber during operation. Degassing is performed to remove such gases and to control the pressure ratio in the empty working chamber. In the state of the art, for example, air exchange boreholes are provided for this purpose, connecting the empty working chamber with the ambient atmosphere.

[0004] In order to prevent the outside atmosphere and the contaminants contained therein from entering the empty working chamber of the cylinder during the alternating movement of the piston, such air exchange boreholes are provided with, for example, state-of-the-art functional elements.

[0005] The state of the art describes various solutions to this problem. For example, pure filter elements made of porous materials or valves with one-sided self-locking function are known. They allow the trapped gas to escape, while also preventing the backflow of the external atmosphere and the dust contained in it.

[0006] A technically well-designed solution is described in DE202011102288U1. The gas exchange barrier described there defines a check valve with an integrated filter element and is designed as a module, making it easy to install. A drawback of the existing solution is its particularly complex design. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] German Registered Utility Model No. 202011102288 Summary of the Invention [Problem to be solved by the invention]

[0008] The object of the present invention is to provide a cylinder degassing unit that is structurally simple, cost-effective, and particularly reliable in degassing the cylinder residual working chamber of a working cylinder, and that can be adapted to different parameters. A further object is to provide a working cylinder equipped with such a cylinder degassing unit. [Means for solving the problem]

[0009] With regard to the cylinder degassing unit, the problem is solved by the features set forth in claim 1, and with regard to the working cylinder, the problem is solved by the features set forth in claim 9. Preferred embodiments can be taken from the associated dependent claims.

[0010] According to the present invention, the basic components of a cylinder degassing unit are a base body, an inner discharge portion, an annular chamber, and an outer discharge portion.

[0011] The cylinder degassing unit is designed as a compact modular component. It is typically used to vent or degas the piston chamber of a lift or pull cylinder.

[0012] According to the invention, the cylinder degassing unit is based on the fact that there exists a cylinder residual air space in the working cylinder that is not pressurized by the hydraulic medium, the volume of which changes as a result of the stroke movement of the piston of the working cylinder, and the working cylinder is provided with a wall perforation that provides a connection between the cylinder residual air space and the outside atmosphere, which is led through the cylinder degassing unit.

[0013] The substrate is used in a positionally fixed arrangement on a hydraulic actuation cylinder (hereinafter also referred to as an actuation cylinder). When the present invention is used as intended, the substrate is disposed at least partially within a wall perforation of the actuation cylinder.

[0014] The base body has a concave contour, which preferably forms an annular chamber in the design of a circumferential annular gap or a circumferential annular groove. The concave contour is preferably designed as a tapered diameter of the base body and, together with the inner jacket of the wall perforation, forms a circumferential cavity providing the annular chamber.

[0015] The volume of the annular chamber controls the volume of air that can be stored and the volumetric flow rate that can be released. Additionally, the annular chamber takes over the function of a pressure chamber.

[0016] According to the present invention, the inner exhaust portion includes an inner exhaust channel and an inner elastomeric annular body.

[0017] The inner discharge channel is arranged in the base body and can be provided as a borehole, in particular. The inner discharge channel connects the cylinder residual air space with the annular chamber. At one end of the inner discharge channel there is an inner inlet for this purpose located in the cylinder residual air space. The intermediate outlet of the annular chamber is located at the other end of the inner discharge channel.

[0018] An inner elastomeric annulus covers the intermediate outlet and is preloaded, the inner elastomeric annulus being designed to form a first pressure barrier in the outlet direction and a second sealing surface in the inlet direction.

[0019] The outer exhaust portion is constructed similarly to the inner exhaust portion, also disposed within the substrate, and having an outer exhaust channel and an outer elastomeric annular body.

[0020] The outer discharge channel connects the annular chamber to the outside atmosphere. To this end, the preferably inclined outer discharge channel has an intermediate inlet at one end into the cylinder's residual air space and an outer outlet to the outside atmosphere at its opposite end. The outer elastomeric annular body covers the outer outlet. Like the inner elastomeric annular body, the outer elastomeric annular body is preloaded and designed to form a second pressure barrier in the outlet direction and a first sealing surface in the inlet direction. Once the second pressure barrier is overcome, the discharged medium exits into the low-pressure region of the atmosphere.

[0021] For the purposes of the present invention, the discharge direction is understood to be the direction from the inside to the outside, i.e. from the cylinder residual air space towards the outside atmosphere. The discharge direction represents the possible path along which the discharge medium may leave the cylinder residual air space towards the outside atmosphere.

[0022] The inlet direction is understood to be the direction opposite to the outlet direction.

[0023] The order of designation of the pressure barriers follows the discharge direction, and the order of designation of the sealing faces follows the inlet direction.

[0024] The discharged medium may in particular be a gaseous medium such as air or gas which is released from the hydraulic medium as a result of the pressure difference, or it may be a hydraulic medium which may enter the cylinder residual air space in small amounts as a result of the piston movement peeling off the inner jacket of the working cylinder, or it may enter as a leakage flow, or it may also be condensate. In the following, the discharged medium may also be referred to as gas or air.

[0025] Depending on the operating conditions, the sealing surfaces allow for division into a high-pressure range in the cylinder residual air space and the inner discharge channel, a medium-pressure range in the annular chamber and outer discharge channel from downstream of the inner elastomeric annulus to the outer annulus, and a low-pressure range in the external atmosphere.

[0026] The hardness of the material, the preload after attachment to the substrate, and the wall thickness of each elastomeric annular body, as well as the cross-sectional opening area of ​​the intermediate or outer outlet, determine the pressure required for the evacuation medium to flow out.

[0027] When a predetermined pressure is reached in the inner discharge channel, the inner elastomeric annulus expands, allowing the discharge medium to escape into the annular chamber. Due to the closing force provided by the preload, a predetermined pressure also remains in the residual air space of the cylinder after the discharge.

[0028] The same applies to the outer outlet. When a minimum pressure is reached, the outer elastomeric annulus expands, unblocking the outer outlet. Gas can escape from the intermediate chamber to the atmosphere through the outer exhaust channel and the outer outlet. The preload on the outer elastomeric annulus defines the residual pressure value that closes the outer outlet. In this way, a defined pressure can be maintained within the annular chamber, also referred to herein as the intermediate pressure range.

[0029] In accordance with the present invention, the air distribution module is further designed to have a full exhaust operational state, a partial exhaust operational state, and a closed operational state.

[0030] In a fully discharged operating state, a positive pressure exists in the residual air space of the cylinder relative to the external atmosphere. This positive pressure overcomes the first and second pressure barriers and leads from the residual air space of the cylinder through the inner discharge section, the annular chamber, and the outer discharge section to the outlet for the discharge medium to the external atmosphere. In this case, the above-mentioned different pressure conditions are provided: high pressure in the residual air space of the cylinder, medium pressure in the annular chamber, and low pressure in the external atmosphere.

[0031] In the partial discharge operating state, a positive pressure exists in the cylinder residual air space compared to the annular chamber. This positive pressure overcomes the first pressure barrier, and the medium escapes from the cylinder residual air space through the inner discharge section into the annular chamber. However, in the partial discharge operating state, the pressure difference is not large enough to also overcome the second pressure barrier. The first sealing surface remains closed.

[0032] In the closed operating state, neither the first nor the second pressure barrier can be overcome. The inner discharge section seals the cylinder residual air space from the annular chamber, and the outer discharge section seals the annular chamber from the outside atmosphere.

[0033] With the cylinder degassing unit according to the invention, a surprisingly simple design solution has been found which offers several particular advantages.

[0034] Both the valve effect and the pressure control are realized in a functionally integrated manner by particularly simple and robust means.

[0035] Advantageously, two barrier-forming elastomer annuli provide a two-stage exhaust path: first from the cylinder residual air space to the annular chamber, and then from there to the atmosphere. This design implements an airlock function, meaning that the cylinder residual air space is not directly connected to the cylinder's surroundings. This enhances the protection of the cylinder residual air space from the harmful effects of the atmospheric environment. Dust particles, harmful gases, or aerosols are blocked in two stages and cannot enter the cylinder and potentially damage it.

[0036] Advantageously, the annular chamber is already shielded from contamination by the outer discharge part, so that the inner elastomeric annular body in particular is particularly protected and its function is not impaired even under problematic conditions of the external atmosphere.

[0037] Another advantage is the defined residual pressure in the annular chamber that is made possible by the invention. Particularly advantageously, several advantageous effects can be achieved by the residual pressure during functional integration.

[0038] On the one hand, the residual pressure is an advantageous stage in the pressure cascade, providing an intermediate pressure level between the maximum possible pressure in the cylinder residual air space and the mere atmospheric pressure of the outside atmosphere. The total pressure difference is therefore advantageously divided into two stages.

[0039] On the other hand, even if the cylinder residual air space is at a negative pressure compared to the outside atmosphere, there is a positive pressure between the annular chamber and the outside atmosphere, which has the advantageous effect of preventing outside air from entering the annular chamber.

[0040] By applying residual pressure to the inner piston ring (looking towards the inlet), the residual pressure assists the sealing effect of the inner piston ring under closed operating conditions.

[0041] This allows the volume of the cylinder residual air space to increase during the piston stroke, without risking the intrusion of external air and contaminant particles, thereby providing negative pressure to the cylinder residual air space, thus assisting the piston's working movement and improving energy efficiency.

[0042] Another advantage is that the outgoing air during rapid piston movement goes through at least two pressure stages, resulting in reduced noise pollution. The discharge flow is buffered by an annular chamber, which avoids the loud hissing noise typical of conventional cylinders that discharge directly from the positive pressure range to the negative pressure range.

[0043] Another advantage is the simplicity of the design: the base body can easily be provided as a machined part. The elastomeric annulus can be designed as a simple hose section or rubber ring. This design has the advantage of being particularly robust. Furthermore, the annulus can be easily replaced and renewed as needed. Advantageously, the base body can be arranged in the wall perforation so that it protrudes axially outward together with the outer discharge part, so that the outer elastomeric annulus, which may be subject to high stresses due to environmental influences, can be replaced without removing the cylinder degassing unit from the wall perforation and preferably even without using tools.

[0044] Furthermore, by selecting the preload of the elastomeric annulus, the desired pressure in the cylinder residual air space and in the annular chamber can be specified for a particular application, while using the same substrate with the same dimensions of the exhaust channel and outlet. Further adaptation is possible by changing the cross section of the outlet.

[0045] In a first advantageous further development of the cylinder degassing unit according to the preceding claim, the base body has a cylindrical basic shape and is accommodated in a wall perforation formed as a hollow cylindrical borehole in the wall of the cylinder residual air space.

[0046] Advantageously, the base body can be designed with an external thread that engages with a corresponding internal thread in the wall drilling of the actuating cylinder, however, other connections are also possible, such as for example a press fit.

[0047] According to a further advantageous embodiment, the inner and outer elastomeric annular bodies are identical in structure.

[0048] This further development allows for further simplification and optimization of the design. Nevertheless, it is still possible to provide different pressure differentials by the inner elastomeric annulus at the intermediate outlet as a first pressure barrier and by the outer elastomeric annulus at the outer outlet as a second pressure barrier, for example by selecting different cross-sectional areas of the respective outlets of the discharge channels or different diameters of the bearing seats of the elastomeric annulus.

[0049] In another advantageous further development of the cylinder degassing unit, the annular chamber is formed by a concave contour of the base body and an inner jacket of the wall perforations.

[0050] The concave profile of the base body can be produced in a cost-effective and simple manner, preferably by lathing the material. However, it is also possible to mill non-radially symmetrical concave profiles. The geometric design of the concave profile of the base body, together with the substantially cylindrical inner jacket, defines the shape and volume of the annular chamber. In this way, the pressure conditions and flow behavior can be influenced in a targeted manner.

[0051] In another advantageous further development of the cylinder degassing unit, the annular chamber in the closed operating state is designed to be at a positive pressure relative to the outside atmosphere.

[0052] The positive pressure creates an airlock function within the annular chamber. The intrusion of dust or other contaminated air is prevented by the permanently present positive pressure. The positive pressure within the annular chamber is maintained throughout the piston's stroke, at all possible piston positions, and at all possible pressure conditions in the cylinder residual air space. The positive pressure within the annular chamber prevents external atmosphere and contaminants from entering the annular chamber and assists the sealing effect of the inner elastomeric annulus in its function as a second sealing surface.

[0053] Another advantageous development of the cylinder degassing unit has an inner O-ring which is designed for sealing contact with the wall perforation and forms a sealing surface between the cylinder residual air space and the annular chamber.

[0054] This further development shows how to further simplify the structural design and improve the effectiveness of the pressure control and valve functions.

[0055] Another advantageous development of the cylinder degassing unit has an outer O-ring which is designed to come into sealing contact with the wall perforation and forms a sealing surface between the annular chamber and the outside atmosphere.

[0056] Again, as with the inner O-ring, this further simplifies the structural design and improves the effectiveness of the pressure control and valve functions.

[0057] Another advantageous further development of the cylinder degassing unit according to the preceding claims has a further inner discharge part and a further annular chamber functionally arranged in series with the inner discharge part and the annular chamber.

[0058] A further development is based on the further special advantage that the multi-stage design can be further extended with a third or further stage.

[0059] For applications with different piston travel speeds and applied pressure ranges, further pressure stages can be connected in series within the cylinder degassing unit, thereby controlling and further improving damping, noise generation and outflow gas behavior. Also, the pressure difference achieved between the individual pressure stages is advantageously reduced, while maintaining the same total pressure difference between the cylinder residual air space and the outside atmosphere.

[0060] A further aspect of the invention relates to an actuation cylinder having a cylinder residual air space with associated wall perforations that provide a passageway.

[0061] The working cylinder according to the invention also comprises a cylinder degassing unit according to the invention arranged in the wall perforation, which is designed according to any one of claims 1 to 8.

[0062] Advantageously, the actuating cylinder according to the present invention is designed as a single-acting hydraulic actuating cylinder that is actuated by a fluid in only one direction. An empty working chamber bounded by a piston with a piston seal forms the cylinder residual air space. The empty working chamber is, for example, a piston chamber in the case of a pull cylinder or a piston rod chamber in the case of a pressure cylinder. Furthermore, the actuating cylinder is designed in a manner known per se.

[0063] The invention is explained in more detail by way of an exemplary embodiment with the aid of the following figures: FIG. [Brief explanation of the drawings]

[0064] [Figure 1] Schematic cross-sectional view of an actuating cylinder. [Figure 2] Schematic cross-sectional view of a cylinder degassing unit. DETAILED DESCRIPTION OF THE INVENTION

[0065] The same reference numerals in various figures refer to the same structures or components. Reference numerals are also used in the description even if they are not shown in the relevant figures.

[0066] FIG. 1 shows a schematic cross-sectional view of an exemplary embodiment of an actuation cylinder 8 fitted with a cylinder degassing unit 7 .

[0067] In this exemplary embodiment, the actuating cylinder 8 is a hydraulically pulled cylinder. There is a lateral pressurized medium connection in the cylinder wall, through which pressurized medium can be applied to the piston rod chamber. In this way, pressure is applied to the annular surface of the piston facing the guide closure, causing the piston with its associated piston rod to perform an inward stroke movement. The cylinder residual air space is not pressurized and remains empty. The volume of the cylinder residual air space 5 changes as a result of the stroke movement.

[0068] In an exemplary embodiment, the cylinder degassing unit 7 is arranged in connection with the cylinder residual air space 5 in the wide section of the wall perforation 5.1, which is designed as a borehole and assigned to the cylinder residual air space 5, forming a uniform pressure chamber together with the cylinder residual air space 5. This configuration allows the cylinder degassing unit 7 to evacuate the cylinder residual air space 5 during the retraction movement of the piston. Further details of the cylinder degassing unit 7 are shown in Figure 2 below.

[0069] FIG. 2 shows a schematic cross-sectional view of the cylinder degassing unit 7.

[0070] It consists of a base body 1, an inner discharge part 2 and an outer discharge part 4. Furthermore, an annular chamber 3 is formed by a concave contour 1.1 of the base body 1.

[0071] When installed as intended, the inner discharge section 2 is placed in a wall perforation 5.1 of the working cylinder, designed as a borehole, and is pressure-connected to the cylinder residual air space 5 by its inner discharge channel 2.1. The inner discharge channel 2.1 begins at the inner inlet 2.3 of the borehole's cylinder residual air space 5 and leads to an intermediate outlet 2.4, which then leads to the annular chamber 3. The intermediate outlet 2.4 is covered by an inner elastomeric annular body 2.2, which in the exemplary embodiment is designed as a stretched rubber or plastic ring with a flat cross section. In the exemplary embodiment, the seal and pressure separation between the cylinder residual air space 5 and the annular chamber 3 are provided by an inner O-ring 9.

[0072] The outer discharge part 4 is similarly designed and consists of an outer discharge channel 4.1 and an outer elastomeric annulus 4.2. The outer discharge channel 4.1, designed as a borehole, penetrates the base body 1. The outer discharge channel 4.1 has a pressure connection with an intermediate inlet 4.3 to the annular chamber 3 and ends in the discharge direction at an outer outlet 4.4 of the outer elastomeric annulus 4.2, which therefore leads to the outside atmosphere 6, which is not part of the device according to the invention.

[0073] During the active stroke of the pull cylinder of the exemplary embodiment, hydraulic pressure medium is introduced into the piston rod chamber, moving the piston towards the piston bottom. The volume of the piston chamber decreases, and the pressure of the discharge medium accumulated there increases. In this case, the piston chamber becomes the cylinder residual air space 5.

[0074] When a positive pressure exists in the cylinder residual air space 5 and is high enough to overcome the preload of the elastomeric annulus 2.2, the escaping gas flows via the inner inlet 2.3 into the inner escaping channel 2.1, through it to the intermediate outlet 2.4 and from there through the inner elastomeric annulus into the annular chamber 3. In the exemplary embodiment, the annular chamber 3 is a circumferential cavity formed by the concave contour 1.1 of the base body 1 and the wall of the borehole, here indicated schematically by a vertical dashed line.

[0075] The intermediate outlet 2.4 is closed by the inner elastomeric annulus 2.2, which opens only when a certain pressure is applied. Air enters the medium-pressure region of the annular chamber 3 from the positive pressure region in the cylinder residual air space 5 of the working cylinder. This pressure difference causes the annular chamber 3 to fill with the discharge medium.

[0076] The gas then flows into the outer exhaust section 4. The gas enters the outer exhaust channel 4.1 via the intermediate inlet 4.3. The outer outlet 4.4 is closed by the outer elastomeric annular body 4.2, which also opens once the gas reaches a certain pressure, allowing the gas to flow into the external atmosphere, i.e., the negative pressure region.

[0077] During the passive piston stroke in the extension direction, the volume in the piston chamber increases again, causing a decrease in pressure. Both elastomeric annular bodies 2.2, 4.2 contact and close the associated outlets 2.4, 4.4, respectively, thus forming the first and second sealing surfaces. Even if the pressure in the cylinder residual air space 5 becomes lower than the external atmosphere 6, a relative positive pressure remains in the annular chamber 3 compared to the external atmosphere 6 due to the closure of the intermediate outlet 2.4 by the inner elastomeric annular body 2.2 (as a second sealing level) and the preload of the outer elastomeric annular body 4.2 at the outer outlet as a second pressure barrier. This relative positive pressure reliably prevents the intrusion of external air. This is the closing operating state.

[0078] The circles around the numbers 5, 3 and 6 indicate the different pressure zones. Furthermore, the horizontal dashed lines indicate the boundaries of the different pressure zones in a schematic manner. [Explanation of symbols]

[0079] 1 Base 1.1 Concave contour 2 Inner discharge part 2.1 Inner discharge channel 2.2 Inner elastomeric annulus 2.3 Inside entrance 2.4 Intermediate exit 3 Circular Chamber 4 External discharge part 4.1 Outer Discharge Channel 4.2 Outer elastomeric annulus 4.3 Intermediate Entrance 4.4 External exit 5 Cylinder residual air space 5.1 Wall perforation 6. External atmosphere 7 Cylinder degassing unit 8 working cylinders 9 Inner O-ring

Claims

1. A cylinder degassing unit (7), The device comprises a base (1), an inner discharge portion (2), an annular chamber (3), and an outer discharge portion (4), The base body (1) is designed to be placed in a fixed position on the working cylinder (8) in a wall perforation (5.1) of the cylinder residual air space (5) and has a concave contour (1.1) forming the annular chamber (3), The inner discharge part (2) has an inner discharge channel (2.1) and an inner elastomeric annular body (2.2), the inner discharge channel (2.1) is arranged in the base body (1), connects the cylinder residual air space (5) to the annular chamber (3), has an inner inlet (2.3) in the cylinder residual air space (5) and an intermediate outlet (2.4) in the annular chamber (3), the inner elastomeric annular body (2.2) covers the intermediate outlet (2.4), is prestressed and is designed to form a first pressure barrier in the discharge direction and a second sealing surface in the inlet direction; The outer discharge part (4) has an outer discharge channel (4.1) and an outer elastomeric annular body (4.2), the outer exhaust channel (4.1) is arranged in the base (1), connects the annular chamber (3) to the external atmosphere (6), has an intermediate inlet (4.3) in the annular chamber (3) and has an outer outlet (4.4) leading to the external atmosphere (6); the outer elastomeric annular body (4.2) covers the outer outlet (4.4), is prestressed and is designed to form a second pressure barrier in the outlet direction and a first sealing surface in the inlet direction; The cylinder degassing unit (7) is designed to have a full discharge operating state, a partial discharge operating state, and a closed operating state; In the fully discharged operating state, a positive pressure exists in the cylinder residual air space (5) relative to the external atmosphere (6), thereby overcoming the first pressure barrier and the second pressure barrier and providing a medium outlet from the cylinder residual air space (5) via the inner discharge portion (2), the annular chamber (3) and the outer discharge portion (4) into the external atmosphere (6); In the partial discharge operating state, a positive pressure exists in the cylinder residual air space (5) relative to the annular chamber (3), which overcomes the first pressure barrier and provides a medium outlet from the cylinder residual air space (5) into the annular chamber (3) via the inner discharge part (2), In the closed operating state, neither the first nor the second pressure barrier is overcome, and the inner discharge part (2) seals the cylinder residual air space (5) against the annular chamber (3), and the outer discharge part (4) seals the annular chamber (3) against the external atmosphere (6).

2. 2. An in-cylinder degassing unit (7) according to claim 1, characterized in that the base body (1) has a cylindrical basic shape and is designed to be accommodated in a wall perforation formed as a hollow cylindrical borehole into the cylinder residual air space (5).

3. 3. A cylinder degassing unit (7) according to claim 1 or 2, characterized in that the inner elastomeric annular body (2.2) and the outer elastomeric annular body (4.2) are identical in structure.

4. A cylinder degassing unit (7) according to any one of claims 1 to 3, characterized in that the annular chamber (3) is formed by the concave contour (1.1) of the base body (1) and the inner jacket of the wall perforations.

5. A cylinder degassing unit (7) according to any one of claims 1 to 4, characterized in that the annular chamber (3) in the closed operating state is designed to be at a positive pressure relative to the external atmosphere (6).

6. 6. A cylinder degassing unit (7) according to any one of claims 1 to 5, characterized in that it comprises an inner O-ring (9) designed to be in sealing contact with the wall perforation (5.1) and forming a sealing surface between the cylinder residual air space (5) and the annular chamber (3).

7. A cylinder degassing unit (7) according to any one of claims 1 to 6, characterized in that it has an outer O-ring designed to be in sealing contact with the wall perforation (5.1) and forming a sealing surface between the annular chamber (3) and the external atmosphere (6).

8. A cylinder degassing unit (7) according to any one of claims 1 to 7, characterized in that it has another inner discharge section and another annular chamber functionally arranged in series with the inner discharge section (2) and the annular chamber (3).

9. A cylinder with residual air space (5) and wall perforations (5.1), A working cylinder (8) comprising a cylinder degassing unit (7) arranged in said wall perforation (5.1), said cylinder degassing unit (7) being designed according to any of claims 1 to 8.

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