Packing Ring with Inclined Relief Opening

Abstract

In order to provide a packing ring (14) that is constructed as simply and compactly as possible, allows a longer service life, and can be flexibly adapted to various conditions of use, the present invention envisages that at least one ring segment (14a) is provided with at least one relief opening (25), which extends from the radially inner inner circumferential surface (18) of the ring segment (14a) to the radially outer outer circumferential surface (23) and / or to the second axial ring end (RE2) of the ring segment (14a), and at least one portion of the at least one relief opening (25) that contacts the radially inner inner circumferential surface (18) of the ring segment (14a) is inclined or curved towards the first axial ring end (RE1).

Description

Technical Field

[0001] The present invention relates to a packing ring having at least three ring segments each having a first segment end and a second segment end in the circumferential direction, wherein a first tangential contact surface of the first segment end of one ring segment abuts against a second tangential contact surface of the second segment end of the ring segment following the one ring segment in the circumferential direction, whereby a radial seal of the packing ring is formed, and a first axial contact surface of the first segment end of one ring segment facing the first axial ring end of the packing ring abuts against a second axial contact surface of the second segment end of the ring segment following the one ring segment in the circumferential direction facing the second axial ring end of the packing ring, whereby an axial seal of the packing ring is formed. Furthermore, the present invention relates to a sealing device for sealing a reciprocating oscillating piston rod, comprising a casing in which a plurality of packing rings arranged continuously in the axial direction are provided inside, and a compressor casing, and a piston compressor comprising at least one cylinder casing arranged in contact with the compressor casing and in which a piston reciprocates and oscillates inside.

[0002] Crosshead configurations, especially double-acting piston compressors, require sealing the crank-side compression chamber within the cylinder, which is dominated by a (high) cylinder pressure that varies over time, along the oscillating piston rod. This sealing is generally performed against a (low) pressure corresponding substantially to the ambient pressure that prevails within the crankcase. The sealing member used for such sealing is called a packing ring and is arranged within a so-called pressure packing. In this case, the sealing member can follow to some extent the lateral movement of the piston rod without losing its sealing action. In order to improve the service life and reliability of the pressure packing, generally a plurality of such packing rings as described above are connected in series in the axial direction within the pressure packing. Such pressure packings or seals are well known in various configurations from the prior art, for example, from British Patent Publication No. 928749, U.S. Patent No. 1008655, or European Patent Application Publication No. 2056003.

[0003] Based on the relative movement between the piston rod and the packing ring, the packing ring is affected to some extent by wear on the contact surface with respect to the piston rod. This ring wear requires a ring shape that is usually cut, which enables automatic continuous adjustment of the ring when material is removed at the contact surface between the ring and the piston rod. For this purpose, rings cut in the radial and tangential directions are generally used, and these rings are used in pairs in the packing chambers of the pressure packing, thereby covering the resulting butting gaps with each other to compensate for wear. Such a combination of radially / tangentially cut rings is a single-acting seal that seals only in the direction of the crosshead, while in the re-expansion stage on the crank side of the piston compressor, there is no risk of higher pressure being trapped within the packing, which is ensured by the radial cut. In the case of a cut ring shape, as is well known, a coil expander generally wound around the outer peripheral surface is used, and the coil expander presses the packing ring against the piston rod even in the non-pressurized state.

[0004] Particularly at relatively high pressures, in conventional units, significant extrusion of the packing ring into the gap formed between the piston rod and the packing casing or the chamber disk can also occur. To avoid this extrusion as much as possible, as disclosed in U.S. Patent No. 3,305,241, an additional metallic support ring that does not planar-contact the piston rod can be used between the low-pressure side of the ring and the chamber disk.

[0005] In a composite of a packing ring cut in the radial direction and a packing ring cut in the tangential direction, the sealing against the piston rod is substantially performed only by the packing ring cut in the tangential direction. Each ring segment of the packing ring cut in the tangential direction can slide relative to each other during wear based on the cut guided in the tangential direction, and thus can maintain the sealing effect. The packing ring cut in the radial direction is substantially used only to seal the wear gap of the packing ring in the tangential direction in the axial and radial directions. The packing ring in the radial direction wears until each ring segment abuts against each other in the circumferential direction. Therefore, the wear of the packing ring cut in the radial direction is different from the wear of the packing ring cut in the tangential direction. In order to prevent the packing ring cut in the tangential direction and the packing ring cut in the radial direction from rotating relative to each other, thereby causing the wear gap of the packing ring cut in the tangential direction to no longer be covered and the sealing effect to be lost, anti-rotation means must be provided between the rings. Such anti-rotation means are generally formed as pins, and the pins are inserted into recesses arranged corresponding to the packing ring cut in the radial direction and the packing ring cut in the tangential direction. Therefore, in the aforementioned European Patent Application Publication No. 2056003, it has already been proposed to provide a single packing ring cut in both the radial and tangential directions instead of a composite packing ring composed of a packing ring cut in the radial direction and a packing ring cut in the tangential direction. Thereby, the axial structural length of the pressure packing and thus the entire seal can be shortened.

[0006] As the compression pressure of the compressor increases, the load applied to the packing ring and thus the wear of the packing ring also increase. A well-known method for reducing the load applied to the segmented packing ring is to provide pressure compensation means, as shown, for example, in the aforementioned European Patent Application Publication No. 2056003. In this case, the relatively high applied pressure is intentionally brought closer to the dynamic sealing surface (between the packing ring and the piston ring in the radial direction) through one or more circumferentially extending pressure compensation grooves, and on the side opposite to the pressure in the axial direction (the crankcase side). Thereby, the surface pressure at the dynamic sealing surface decreases, the frictional force decreases, and the service life increases. However, the drawback in this case is that the principle of this pressure compensation can only be enhanced to a certain extent. This is because, based on the pressure compensation grooves, the remaining wall thickness remaining in the axial direction of the packing ring is no longer sufficiently stable, and there is a risk of deformation and thus leakage when pressure is applied. Another drawback of the highly pressure-compensated packing ring is that the ring is radially crimped to the piston rod with only a very small residual force. Since the piston rod is generally affected by a certain degree of lateral movement in addition to the translational oscillatory movement, the frictional force at the axial contact surface of the packing ring may prevent or at least delay the radial movement of the ring, thereby causing the ring to lift off from the piston rod and resulting in leakage.

[0007] The packing ring with three ring segments disclosed in U.S. Patent No. 1999094 is provided with inclined holes connecting grooves extending circumferentially on the inner peripheral surface to recesses on the axial end faces. This ring is not cut in the tangential direction. U.S. Patent No. 1828178 discloses an oil scraping ring composed of three parts and cut in the tangential direction, rather than a sealing packing ring. On the inner peripheral surface, circumferential grooves connected to the axial end faces via a plurality of openings are arranged. Through the openings, the oil scraped from the piston rod is led to the outside. Korean Registered Patent Publication No. 101898141 discloses a packing ring composed of four parts and having axial and tangential seals. Each ring segment is provided with a central relief hole.

[0008] Therefore, an object of the present invention is to provide a packing ring and a sealing device that eliminate the drawbacks of the prior art. In particular, it is desirable that the packing ring be configured as simply and compactly as possible, enable a longer service life, and be flexibly adaptable to various operating conditions.

[0009] This object is solved according to the present invention in that at least one relief opening is provided in at least one ring segment, the relief opening extending from the inner peripheral surface located radially inside the ring segment to the outer peripheral surface located radially outside and / or to the second axial ring end of the ring segment, wherein at least one part of the at least one relief opening in contact with the inner peripheral surface located radially inside the ring segment of the ring segment is inclined or curved towards the first axial ring end. Thereby, a packing ring is achieved that enables pressure compensation between the high pressure applied to the outer peripheral surface and the second axial ring end during operation of the compressor in the assembled state and the relatively low pressure applied to the first axial ring end, wherein the pressure compensation can be adapted, in particular increased, to the radial wear of the packing ring.

[0010] Preferably, the first relief opening end that opens to the inner peripheral surface located radially inside the ring segment of at least one relief opening is separated from the first axial ring end by a relief opening axial distance of 4% to 40%, preferably 4% to 20% of the axial ring width of the ring segment. Thereby, the pressure compensation portion can be brought as close as possible to the low-pressure side in the axial direction without unacceptably weakening the packing ring.

[0011] Preferably, at least one relief opening has a circumferential relief opening length that is 2% to 100% of the axial ring width of the packing ring, preferably 2% to 50% of the axial ring width, particularly at most 25% at least at the relief opening end. Thereby, for example, a groove-shaped recess extending over a relatively small range in the circumferential direction can be provided on the inner peripheral surface.

[0012] Preferably, at least two relief openings are provided in at least one ring segment. In this case, each relief opening has a first relief opening end that opens to the inner peripheral surface located radially inside the ring segment. In this case, the first relief opening ends of two relief openings arranged side by side in the circumferential direction are separated from each other by a relief opening circumferential distance z that is preferably 1 mm to 15 mm. With this advantageous configuration, the pressure compensation can be distributed as uniformly as possible in the circumferential direction.

[0013] When at least one relief opening is provided and the first relief opening end that opens to the inner peripheral surface located radially inside the ring segment of the relief opening is separated from the second relief opening end that opens to the outer peripheral surface located radially outside the ring segment of the relief opening in the circumferential direction, for example, a relief hole that extends obliquely from the inner peripheral surface located inside to the outer peripheral surface located outside may be provided in the region of the first segment end on the inner peripheral surface located inside.

[0014] Advantageously, at least one relief opening has an axial relief opening width which is 2 to 30%, preferably 2 to 20%, of the axial ring width of the packing ring, at least at the relief opening end. Preferably, the relief opening has a straight extension and a constant circular cross-section with a relief opening diameter which is 2 to 30%, preferably 2 to 20%, of the axial ring width of the packing ring. Thereby, the relief opening can be easily manufactured, for example, by punching or milling, and in this case, it has been found that multiple dimensions are advantageous in order to achieve pressure compensation as good as possible.

[0015] At least one axial groove is provided on at least one ring segment, preferably on the outer peripheral surface located radially outside each ring segment, and the axial groove extends from the first axial ring end to the second axial ring end. Thereby, the rigidity of the structure of the ring segment and thus of the packing ring can be improved.

[0016] Preferably, at least one wear opening is provided in at least one ring segment, extending from the outer peripheral surface located radially outside the ring segment and / or from the second axial ring end towards the inner peripheral surface located radially inside the ring segment. In this case, the radially inner wear opening end facing the inner peripheral surface is spaced apart by a distance of at most 40% of the radial ring height extending between the outer peripheral surface located radially outside the ring segment and the inner peripheral surface located radially inside the ring segment, in the radial direction of the ring segment, from the inner peripheral surface located radially inside the ring segment. In this case, the wear opening end is located between the first axial ring end and the second axial ring end and is spaced apart from the first axial ring end and the second axial ring end. Thereby, from a predetermined wear state in which the wear opening is exposed on the inner peripheral surface located radially inside the packing ring, the pressure compensation is significantly increased and the crimping pressure is reduced.

[0017] It is advantageous if at least one end facing the inner circumferential surface located radially inward of at least one wear opening is inclined towards the first axial ring end. Thereby, as in the case of the inclined relief opening, from the time when the wear opening is exposed on the inner circumferential surface located radially inward of the packing ring, the pressure compensation characteristics can be adapted to, and in particular increased with respect to, the wear progressing in the radial direction of the packing ring.

[0018] Preferably, at least one wear opening has a straight extension and a circular cross-section with a wear opening diameter that is 2% to 60%, preferably 2% to 40%, of the axial ring width of the packing ring. Thereby, the wear opening can be easily manufactured, for example, by drilling or milling, and it has been found that multiple dimensions are advantageous in order to achieve the best possible pressure compensation in this case.

[0019] If the defining part of at least one wear opening facing the first axial ring end is axially spaced from the first axial ring end by a wear opening axial distance of 2% to 20%, preferably 2% to 15%, of the axial ring width, the pressure compensation can be improved without unacceptably reducing the stability of the packing ring.

[0020] In another advantageous configuration, at least one compensation recess is provided in at least one ring segment, extending from the outer circumferential surface located radially outward of the ring segment towards the inner circumferential surface located radially inward of the ring segment and extending from the first axial ring end towards the second axial ring end. In this case, preferably at least one compensation recess is provided for each ring segment. Thereby, the axial crimping pressure against the wall is reduced and thus the radial friction is reduced, whereby the packing ring can better follow the lateral movement of the piston rod.

[0021] It is further advantageous if at least one mating recess is provided on the inner circumferential surface located radially inside at least one ring segment, the mating recess extending in the axial direction of the ring segment from a second axially ring end to a first axially ring end and in the radial direction of the ring segment from the inner circumferential surface located radially inside the ring segment to the outer circumferential surface located radially outside the ring segment. In this case, the mating recess has a radial mating recess depth of at most 3% of the ring height. Thereby, on the inner circumferential surface located radially inside the packing ring and not included in the mating recess, an increase in surface pressure can be caused during the high-speed operation stage of the compressor, which is advantageous for reducing leakage during high-speed operation, particularly in a packing ring with significantly pressure compensation.

[0022] The above problem is further solved by a sealing device provided with at least one packing ring according to the present invention, and a piston compressor provided with at least one packing ring according to the present invention in a compressor casing.

[0023] Hereinafter, the present invention will be described in more detail with reference to FIGS. 1 to 8d, which exemplarily, schematically and non - limitatively show advantageous configurations of the present invention.

Brief Description of the Drawings

[0024]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

[0025] FIG. 1 shows a sealing device 1 (pressure packing) well-known in the prior art for a reciprocating oscillating piston rod 2 of a piston compressor (not shown) having, for example, a well-known crosshead. The piston rod 2 performs a substantially reciprocating oscillating motion as indicated by the double arrow. The reciprocating motion results from a well-known crosshead configuration of a piston machine used particularly in large-sized and relatively slow-speed operating piston machines such as gas compressors or large diesel engines. In this case, the lateral force of the connecting rod is supported by a so-called crosshead joint supported and arranged in the crankcase. The piston attached to the crosshead by the piston rod thereby only performs a substantially reciprocating motion. Since the concept of the crosshead is basically well-known, it will not be described in more detail here. However, here, a pure reciprocating motion means that the piston rod 2 may be slightly moved laterally.

[0026] When the sealing device 1 is incorporated in a piston compressor, the first axial seal end AE1 is arranged so as to face a piston (not shown) of the piston compressor arranged in the cylinder in the axial direction. The second axial seal end AE2 located on the opposite side of the sealing device 1 faces the crankcase of the piston compressor. Thus, the sealing device 1 has a high pressure P at the first seal end AE1 (in the cylinder) Hat a relatively low pressure with respect to this, which may correspond substantially to the ambient pressure or be slightly higher, the pressure P at the second seal end AE2 (in the crankcase) N is used to seal against. Obtaining the best possible sealing action is important in order to ensure that the amount of compressed medium flowing out of the cylinder into the crankcase and possibly from there to the surroundings is minimal. In particular, in the case of a gas compressor, for example, where natural gas is compressed, this is extremely important in order to avoid the formation of a combustible mixture consisting of gas and air, which may in some cases cause a flame or explosion, outside the compressor. Furthermore, for safety reasons, to prevent people in the vicinity of the compressor from being endangered, the best possible seal is required. Additionally, in order to increase the supply rate and thus the efficiency of the compressor, the best possible seal is advantageous.

[0027] The sealing device 1 generally has a substantially cylindrical casing 3, which may be assembled, for example, from a predetermined number i of casing segments 3i (also called chamber disks) arranged continuously in the axial direction. In the illustrated example, the sealing device 1 has a plurality of chambers 4 facing the piston rod 2, and these chambers 4 are formed here by recesses provided in the casing segments 3i. One or more packing rings 7a - 7c of different embodiments are respectively arranged in each chamber 4. For example, as described at the beginning, a packing ring cut in the radial direction, a packing ring cut in the tangential direction, or a composite packing ring 7b cut in the radial / tangential direction as shown in the figure are combined. In order to prevent the packing rings 7a - c from being extruded, one support ring 8 made of, for example, a suitable metal may be provided following the packing rings 7a - c in the axial direction. The illustrated sealing device 1 has, for example, three different types of packing rings 7. In this case, as the first packing ring 7a next to the cylinder, a so-called pressure cutoff ring or "pressure breaker" used to reduce the gas flow rate is provided. Two packing rings 7b are respectively arranged in the chamber 4b next to the packing ring 7a in the direction of the crankcase. The packing ring 7b is a conventional composite packing ring cut in the radial / tangential direction here. A plurality of packing rings 7c following these in the axial direction are respectively arranged in the chamber 4c and are isolated from the chamber 4b or the packing ring 7b arranged in the chamber 4b by the buffer chamber 4e in the illustrated example. The packing ring 7c forms a seal barrier as described, for example, in European Patent No. 2376819 or European Patent No. 2855982 in the illustrated embodiment. For this purpose, a pressurized seal medium, for example, seal oil, is supplied into the chamber 4c via the supply line 9. The seal medium may be led out via the outflow line 10 for circulation.An oil pressure is applied to each packing ring 7c from the radially outer side and the axial direction by a sealing medium. Due to this oil pressure, each packing ring 7c is pressed against the piston rod 2 and pushed apart from each other in the axial direction, whereby a seal can be formed or improved. On the other hand, the packing ring 7b is held by the piston rod 2 by a coil expander 11 disposed on the circumferential surface and is pressed against the piston rod 2 by a differential pressure during operation. However, the seal by the seal barrier using the packing ring 7c is only shown for the sake of completeness and is not important for the present invention.

[0028] At the second axial seal end AE2 of the sealing device 1, two scraping rings 13 are arranged following the packing ring 7c. These scraping rings 13 are provided for scraping and collecting the sealing medium adhering to the piston rod 2. The scraping ring 13 scrapes the sealing medium and guides it radially outward into the chamber 4d. This sealing medium is led out from the chamber 4d through the collecting pipeline 12, then filtered, for example, and collected in a reservoir tank and supplied to the packing ring 7b again.

[0029] The sealing device 1 shown in FIG. 1 is of course exemplary, and may have any different configuration in which the packing rings 7a to 7c and / or the scraping rings 13 are arranged differently. For example, the casing segment 3i forming the chamber 4c for the seal by the seal barrier and the buffer chamber 4e may be completely omitted, and only the casing segment 3i provided with the chamber 4b for the packing ring 7b and one or more chambers 4d for the scraping ring 13 may be provided in the sealing device 1. In the present invention, at least one packing ring 14 configured based on the present invention, which will be described below, is arranged in the sealing device 1.

[0030] The packing ring 14 according to the present invention, which will be described below with reference to FIGS. 2 to 8d, is related to the packing ring 7b shown in FIG. 1, for example. Of course, it is understood that the illustrated sealing device 1 is merely an example for explaining the application of the packing ring 14 according to the present invention. The sealing device 1 may of course have to some extent a dry-operating type packing ring 7a (pressure cut-off ring), a packing ring 7b, a packing ring 7c pressed by a sealing medium, a scraping ring 13, and also, for example, only one or a plurality of dry-operating type packing rings 7b, and in this case, at least one packing ring 14 according to the present invention is provided.

[0031] FIG. 2 shows a packing ring 14 according to one advantageous configuration of the present invention. The packing ring 14 has a substantially cylindrical central opening 15, and in the assembled state, a reciprocating oscillating type piston rod 2 (see FIG. 1) of, for example, a piston compressor extends through this central opening 15. The diameter of the cylindrical opening 15, that is, the inner diameter Di of the packing ring 14 (see FIG. 3a), substantially corresponds to the diameter of the piston rod 2, or, as will be described in more detail, conforms to the diameter of the piston rod 2 even if it wears during operation. The packing ring 14 has at least three ring segments 14a each having a first segment end SE1 in the circumferential direction and a second segment end SE2 in the circumferential direction. The three ring segments 14a are preferably identically formed and are assembled adjacent to each other in the circumferential direction to form the packing ring 14. Dividing the packing ring 14 into a plurality of ring segments 14a has the advantage that the packing ring 14 can be easily attached to the piston rod 2 and the wear of the packing ring 14 occurring during the operation of the compressor can be compensated better. In particular, in order to arrange the packing ring 14 around the piston rod 2, it is not necessary to remove the piston rod 2.

[0032] At a first segment end SE1 of the ring segment 14a, a first tangential contact surface 19a and a first axial contact surface 16 are provided (see also Fig. 3b). In this case, the first axial contact surface 16 faces a first axial ring end RE1. Both the first tangential contact surface 19a and the first axial contact surface 16 are preferably defined by a first wear limiting surface 22. In the illustrated example, the first tangential contact surface 19a and the first axial contact surface 16 are in immediate contact with each other and are preferably arranged perpendicular to each other. In the simplest case, at the first segment end SE1, a first axial segment recess may be provided that extends axially, partially from the first axial ring end RE1 of the packing ring 14, towards a second axial ring end RE2 located on the opposite side in the axial direction (see also Fig. 3b). Thus, the defining surface of the first axial segment recess forms the first tangential contact surface 19a and the first axial contact surface 16, and further forms a first wear limiting surface 22, the function of which will be explained in more detail below.

[0033] A second tangential contact surface 19b is provided at the second segment end SE2 of the ring segment 14a. The second tangential contact surface 19b abuts against the first tangential contact surface 19a of the first segment end SE1 of the ring segment 14a that follows it in the circumferential direction. Thereby, a radial seal of the packing ring 14 can be formed. Further, a second axial contact surface 17 is provided at the second segment end SE2 of the ring segment 14a (see also FIGS. 4a and 4b). The second axial contact surface 17 abuts against the first axial contact surface 16 of the first segment end SE1 of the ring segment 14a that is in contact with it in the circumferential direction. Thereby, an axial seal of the packing ring 14 can be formed. The second tangential contact surface 19b and the second axial contact surface 17 preferably abut against each other and are advantageously arranged perpendicular to each other. In the simplest case, as shown in the figure, at the second segment end SE2 of the ring segment 14a, a second axial segment recess may be provided that extends axially from the second axial ring end RE2 of the packing ring 14 partially toward the first axial ring end RE1 located on the opposite side in the axial direction (see also FIG. 4b). In this case, the axial defining portion of the second axial segment recess forms the second axial contact surface 17, and the circumferential defining portion forms the second end face 29. However, the second axial segment recess does not form the second tangential contact surface 19b, and the second tangential contact surface 19b is formed, for example, by the ring segment 14a being cut in the tangential direction outward in the radial direction at the second segment end SE2. However, it should be noted here that the term tangential direction related to the first and second tangential contact surfaces 19a, 19b does not necessarily mean the tangential direction in the strict mathematical sense. That is, the extending portions of the tangential contact surfaces 19a, 19b do not necessarily need to form a tangent to a curved portion such as the inner diameter Di or the outer diameter Da. Therefore, the first and second segment recesses can be manufactured, for example, by an appropriate milling machine or cut out in an injection molding method.

[0034] In the assembled state, the first axial ring end RE1 of the packing ring 14 faces the crankcase where a low pressure P (which corresponds to or may be slightly higher than the peripheral pressure) prevails inside, while the second axial ring end RE2 faces the cylinder where a relatively higher pressure P prevails inside. For this purpose, the terms high-pressure side and low-pressure side are also used hereinafter. It should be noted here that when a plurality of packing rings 14 are arranged continuously in the axial direction in the sealing device 1, the pressure decreases from the high pressure P on the cylinder side to the relatively lower pressure P on the crankcase side, which is lower in terms of the device, across the entire sealing device 1. That is, the packing ring 14 that first contacts the cylinder in the axial direction is exposed to a higher pressure than the packing ring 14 following towards the crankcase. That is, the pressure states in the respective packing rings 14 of the sealing device 1 are usually different from each other. N is arranged in the compressor so as to face the crankcase where the internal pressure is dominated by the low pressure P, while the second axial ring end RE2 faces the cylinder where the relatively higher pressure P prevails inside. H In this regard, the terms high-pressure side and low-pressure side are also used hereinafter. It should be noted here that when a plurality of packing rings 14 are arranged continuously in the axial direction in the sealing device 1, the pressure decreases from the high pressure P on the cylinder side to the relatively lower pressure P on the crankcase side, which is lower in terms of the device, across the entire sealing device 1. That is, the packing ring 14 that first contacts the cylinder in the axial direction is exposed to a higher pressure than the packing ring 14 following towards the crankcase. That is, the pressure states in the respective packing rings 14 of the sealing device 1 are usually different from each other. H from the relatively higher pressure P on the cylinder side to the relatively lower pressure P on the crankcase side, which is lower in terms of the device, across the entire sealing device 1. That is, the packing ring 14 that first contacts the cylinder in the axial direction is exposed to a higher pressure than the packing ring 14 following towards the crankcase. That is, the pressure states in the respective packing rings 14 of the sealing device 1 are usually different from each other. N In the case where the packing ring 14 has not yet worn in the new assembled state, in the illustrated example, the first and second wear-limiting surfaces 21, 22 of adjacent ring segments 14a facing each other in the circumferential direction are spaced apart from each other by the wear distance a. In this case, nevertheless, the tangential contact surfaces 19a and 19b and the axial contact surfaces 16 and 17 are in contact with each other, thereby enabling the formation of a seal in the radial and axial directions of the packing ring 14. The wear distance a serves to compensate for the wear that the packing ring 14 is affected by on the inner peripheral surface 18 on the radially inner side during continuous operation. A circumferential groove 20 extending around the entire packing ring 14 in the circumferential direction may be provided on the outer peripheral surface 23 on the radially outer side of the packing ring 14. The circumferential groove 20 is provided to accommodate a coil expander 11 (not shown), and the coil expander 11 radially compresses the packing ring 14 and holds it on the piston rod 2 in the assembled state, as described with reference to FIG. 1.

[0035] In the case where the packing ring 14 has not yet worn in the new assembled state, in the illustrated example, the first and second wear-limiting surfaces 21, 22 of adjacent ring segments 14a facing each other in the circumferential direction are spaced apart from each other by the wear distance a. In this case, nevertheless, the tangential contact surfaces 19a and 19b and the axial contact surfaces 16 and 17 are in contact with each other, thereby enabling the formation of a seal in the radial and axial directions of the packing ring 14. The wear distance a serves to compensate for the wear that the packing ring 14 is affected by on the inner peripheral surface 18 on the radially inner side during continuous operation. A circumferential groove 20 extending around the entire packing ring 14 in the circumferential direction may be provided on the outer peripheral surface 23 on the radially outer side of the packing ring 14. The circumferential groove 20 is provided to accommodate a coil expander 11 (not shown), and the coil expander 11 radially compresses the packing ring 14 and holds it on the piston rod 2 in the assembled state, as described with reference to FIG. 1.

[0036] When wear occurs on the inner peripheral surface 18, the coil expander 11 is subjected to the high pressure P on the cylinder side H In combination with, as suggested by the arrows at the segment ends SE1, SE2 in Fig. 3a, the tangential contact surfaces 19a, 19b of the ring segment 14a facing each other come into contact and slide, so that the packing ring 14 is automatically adjusted radially. Due to wear, the wear distance a decreases until it reaches the maximum wear adjustment. When the maximum wear adjustment is reached, the wear distance becomes zero (a = 0), and the second wear limiting surface 21 provided at the end of the second segment end SE2 of the ring segment 14a in the circumferential direction comes into contact with the first wear limiting surface 22 of the first segment end SE1 of the ring segment 14a in contact in the circumferential direction.

[0037] According to the present invention, at least one relief opening 25 is provided in at least one ring segment 14a, but preferably in all ring segments 14a. The relief opening 25 extends from the inner peripheral surface 18 located radially inside to the outer peripheral surface 23 located radially outside of each ring segment 14a of the packing ring 14 and / or to the second axial ring end RE2 of each ring segment 14a of the packing ring 14. In this case, at least one portion of at least one relief opening 25 in contact with the inner peripheral surface 18 located radially inside of the ring segment 14a is inclined or curved towards the first axial ring end RE1. Preferably, two or more relief openings 25 are provided for each ring segment 14a. For example, as shown in Fig. 2, three relief openings 25 are provided for each ring segment 14a. That is, the relief opening 25 is a continuous cutout connecting the inner peripheral surface 18 located inside to the outer peripheral surface 23 located radially outside and / or the second axial ring end RE2. That is, the relief opening 25 does not open into a circumferential groove extending in the circumferential direction on the inner peripheral surface 18 as in the prior art, but opens directly into the inner peripheral surface 18 located inside.

[0038] The relief opening 25 is basically used to intentionally influence the pressure state between the high-pressure side (second axial ring end RE2) of the packing ring 14 facing the cylinder and the low-pressure side (first axial ring end RE1) of the packing ring 14 facing the crankcase during the operation of the compressor, as will be explained in more detail below with reference to FIGS. 5a and 5b. Based on the feature of the present invention that at least one part of the relief opening 25 in contact with the inner peripheral surface 18 located radially inside the ring segment 14a is inclined towards the first axial ring end RE1, as will be explained in more detail below, the pressure compensation can additionally be adapted to the radial wear of the packing ring 14.

[0039] The relief openings 25 each have a first relief opening end portion 25a, and the first relief opening end portion 25a opens to the inner peripheral surface 18 located radially inside each ring segment 14a of the packing ring 14. The relief opening end portions 25a of two adjacent relief openings 25 that open to the inner peripheral surface 18 located radially inside are arranged to be separated from each other by a relief opening circumferential distance z in the circumferential direction. That is, the relief opening end portions 25a are not connected to each other on the inner peripheral surface 18 located radially inside. Therefore, the inner peripheral surface 18 of the ring segment 14a extends between two adjacent relief opening end portions 25a in the circumferential direction. The relief opening circumferential distance z is preferably 1 mm to 15 mm, particularly preferably 1 to 10 mm, for example 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 mm, according to the size of the ring segment 14a. Also, distances located between these, such as 1.5 mm, 2.5 mm, 3.5 mm, 4.5 mm, 5.5 mm, etc. are of course possible. In this case, the relief opening circumferential distance z does not indicate the measurement from the center of one relief opening end portion 25a to the center of the other relief opening end portion 25a, but rather indicates the circumferential distance between the defining portions of each relief opening end portion 25a, or in other words, the length of the inner peripheral surface 18 in the circumferential direction between adjacent relief opening end portions 25a. However, in this case, the relief opening circumferential distance z between the relief opening end portions 25a of each relief opening 25 of one ring segment 14a does not necessarily have to be the same.

[0040] The relief opening end 25a is preferably arranged at a distance x in the axial direction of the relief opening from the first axial ring end RE1. The relief opening axial distance x is preferably 4% to 40%, advantageously 4 to 30%, particularly preferably 4 to 20%, very particularly preferably 4 to 15%, especially at most 10% of the axial ring width RB, as shown in detail in the cross-section D-D of FIGS. 2 and 6. Thus, between the relief opening end 25a and the first axial ring end RE1 in the axial direction, the inner peripheral surface 18 of the ring segment 14a extends. Similarly, the relief opening axial distance x is not measured from the center of the relief opening end 25a, but is also measured from the defining part of the relief opening end 25a, or in other words, is measured as the length of the inner peripheral surface 18 in the axial direction between the relief opening end 25a and the first axial ring end RE1. However, in this case, the relief opening axial distance x of each relief opening 25 of one ring segment 14a does not necessarily have to be the same. In this case, the axial ring width RB extends between the first axial ring end RE1 and the second axial ring end RE2. The details of the configuration of the relief opening 25 will be described in more detail below with reference to FIG. 6. As is apparent from FIG. 2, the axial relief opening width of the relief opening 25 is smaller than the ring width RB, at least at the relief opening end 25a. In the case of the relief opening 25 having a circular cross-section (at least at the relief opening end 25a), the axial relief opening width corresponds to the diameter. The axial relief opening width of the relief opening end 25a is preferably 2% to 30%, preferably 2 to 25%, particularly preferably at most 20%, especially at most 15% of the ring width RB. Generally, the relief opening end 25a is not located at the center between both axial ring ends RE1, RE2 of the packing ring 14, but is located closer to the first axial ring end RE1 than to the second axial ring end RE2. The first axial ring end RE1 faces the low-pressure side in the assembled state.

[0041] In addition to at least one inclined relief opening 25, each figure is provided with another feature shown in particular in FIGS. 2 to 4b, in particular a relief opening 25 that extends completely straight, one or more wear openings 27. The circumferential groove 20 or the axial groove 24 is optional and will be described below. Thus, the configuration of the packing ring 14 shown in FIG. 2 shows one advantageous configuration with a plurality of features independent of each other. In the present invention, it is considered sufficient if at least one inclined relief opening 25 is provided in at least one ring segment 14a.

[0042] In order to improve the structural rigidity of the packing ring 14, at least one axial groove 24 may be provided on at least one ring segment 14a, preferably on the outer peripheral surface 23 of each ring segment 14a. The axial groove 24 extends axially continuously from the first axial ring end RE1 (optionally interrupted by the circumferential groove 20) to the second axial ring end. Preferably, however, a plurality of axial grooves 24 are provided for each ring segment 14a. For example, as shown in the figure, three axial grooves 24 are provided for each ring segment 14a. In the illustrated example, the relief openings 25 open into the axial grooves 24 on the outer peripheral surface 23. However, of course, this is not essential, and the relief openings 25 may open into the outer peripheral surface 23 (or the circumferential groove 20) of the packing ring 14 adjacent to the axial groove 24 in the circumferential direction.

[0043] The relief openings 25 of the illustrated embodiment are each formed in the form of an inclined cylindrical hole. This is because these relief openings 25 can be manufactured particularly easily in a cutting manner and are inclined overall towards the first axial ring end RE1. However, of course, a non-circular cross-section and / or a non-linear extension of the one or more relief openings 25 may also be envisaged. However, this will increase the manufacturing effort for the relief openings 25. What is important for the present invention, however, is only that at least one part of at least one relief opening 25 that contacts the inner circumferential surface 18 located radially inside the ring segment 14a is inclined towards the first axial ring end RE1. Therefore, this does not necessarily result in a completely straight and inclined extension of the relief opening 25. Basically, it is considered sufficient if a specific part of the relief opening 25 starting from the inner circumferential surface 18 is formed inclined. The part following this part may be formed, for example, straight, i.e., parallel to the axial ring ends RE1, RE2, and / or may extend to the second axial ring end RE2. This is because high pressure P H is also applied there.

[0044] However, the relief opening 25 preferably has a completely straight extension, whereby the relief opening 25 can be manufactured as easily as possible, for example, by means of a cylindrical drill or milling cutter. However, of course, other manufacturing methods are also conceivable. For example, the relief opening 25 can be manufactured directly by an injection molding method and can be incorporated into the ring segment 14a during the injection molding method, especially without the need to drill later. It is also conceivable to manufacture the packing ring 14 using an additive manufacturing method such as 3D printing. In this case too, the relief opening 25 can be taken into account directly during manufacturing.

[0045] However, how the relief opening 25 is manufactured is not important for the present invention. What is important is that the peripheral conditions of the relief opening 25 required with respect to the inclination towards the first axial ring end RE1 are met. In the simplest configuration, the relief opening 25 may extend, for example, as shown in the cross-section D-D in FIG. 6. In this case, not only the part of at least one relief opening 25 that contacts the inner peripheral surface 18 located radially inside the packing ring 14 is inclined towards the first axial ring end RE1, but as also suggested by the example shown in FIG. 2, the entire relief opening 25 is inclined by the first relief opening angle ε. Details regarding this will be described in more detail below with reference to FIG. 6. Based on the inclination of the relief opening 25 according to the present invention, it is possible to intentionally influence the pressure state in the packing ring 14 over the service life of the packing ring 14. In particular, the pressure compensation of the packing ring 14 can be adapted to radial wear. In the simplest case, the corresponding relief opening 25 is formed as a cylindrical hole, and in this case, the axis of the hole is inclined towards the first axial ring end RE1. Thereby, the second relief opening end 25b opening to the outer peripheral surface 23 located radially outside is closer to the first axial ring end RE1 than the first relief opening end 25a opening to the inner peripheral surface 18 located radially inside the relief opening 25. Based on the inclined extension, when the ring segment 14a wears radially, the first relief opening end 25a "moves" substantially towards the first axial ring end RE1, whereby the pressure compensation of the packing ring 14 is increased according to the wear. This is because the high pressure P H on the inner peripheral surface 18 is brought closer to the first axial ring end RE1 in the axial direction. That is, substantially, the greater the wear of the ring segment 14a, the greater the pressure compensation. Thereby, during operation, the radial pressure contact force of the packing ring 14 against the piston rod 2 is reduced, and the service life of the packing ring 14 is improved.

[0046] In order to better disperse the pressure circumferentially on the inner circumferential surface 18 located radially inward, one or more relief openings 25 may end in the form of a milling cut / groove extending, for example, over a relatively small range circumferentially on the inner circumferential surface 18 located radially inward. In this case, the first relief opening end 25a no longer has, preferably, a circular cross-section (between the milling cut / groove and the outer outer circumferential surface 23 and / or the second axial ring end RE2 in the radial direction) of the remaining relief openings 25, and may be formed by a milling cut / groove of a corresponding shape. In this case, the circumferential relief opening circumferential distance z and the axial relief opening axial distance x in the axial direction are measured axially and circumferentially from each defining part of the milling cut / groove. Instead of the milling cut / groove, for example, a kind of slot may be provided. Generally, the relief opening 25 has, at least at its relief opening end 25a, a circumferential relief opening length that is preferably 2 to 100% of the axial ring width RB of the packing ring 14, preferably 2 to 50% of the axial ring width RB, in particular at most 25%. Generally important is that each relief opening end 25a is not connected to each other on the inner circumferential surface 18 located radially inward via a circumferential groove provided for pressure compensation during operation. That is, the circumferential groove forms, together with a particularly small relief opening axial distance x, a narrow side surface made of ring material at the first axial ring end RE1. This side surface is considered to be excited during operation, which may lead to non-uniform wear and undesirable leakiness.

[0047] In addition to at least one relief opening 25 which is at least partially inclined according to the invention, one or more relief openings 25 which of course do not have an inclination towards the first axial ring end RE1 may be provided. Such a relief opening 25 is shown, for example, in the cross-section A-A shown in FIG. 6 and extends substantially parallel to both axial ring ends RE1, RE2. Thus, the pressure compensation is kept substantially constant, i.e., (unlike the inclined relief opening 25) it does not change according to the radial wear of the packing ring 14. Details regarding this will be explained in more detail based on FIG. 6.

[0048] In another advantageous configuration of the invention, at least one wear opening 27 is additionally provided in at least one ring segment 14a of the packing ring 14, preferably in each ring segment 14a. The wear opening 27 extends from the outer peripheral surface 23 located radially outside the packing ring 14 and / or from the second axial ring end RE2 over a part of the ring height RH towards the inner peripheral surface 18 located radially inside the packing ring 14. However, in the non-worn state of the ring segment 14a, it does not extend up to the inner peripheral surface 18 of the ring segment 14a. In the case of a hole, the wear opening 27 is formed, for example, as a blind hole starting from the outer peripheral surface 23 towards the inner peripheral surface 18. Of course, the wear opening 27 formed as a hole may also be drilled towards the inner peripheral surface 18, additionally or alternatively, starting from the second axial ring end RE2. What is important for the wear opening 27 is that the wear opening end 27a (see FIG. 6) of at least one wear opening 27, which faces the inner peripheral surface 18 most widely in the radial direction (regardless of its configuration), is spaced from the inner peripheral surface 18 located radially inside the ring segment 14a by a distance of at most 40%, preferably at most 30%, particularly preferably at most 20% of the ring height RH in the radial direction of the ring segment 14a. In this case, the ring height RH extends between the outer peripheral surface 23 located outside the packing ring 14 and the inner peripheral surface 18 located radially inside, that is, substantially corresponds to half of the difference between the inner diameter Di and the outer diameter Da of the packing ring 14, as shown in FIG. 4a. What is important is that the wear opening end 27a is located between the first axial ring end RE1 and the second axial ring end RE2 and is spaced from the first axial ring end RE1 and the second axial ring end RE2. That is, since the wear opening end 27a is surrounded by the ring material both axially and circumferentially, it is only exposed when worn correspondingly in the radial direction.

[0049] However, preferably, as shown in FIGS. 2 to 4, a plurality of wear openings 27 are provided over the entire circumference of one ring segment 14a, and particularly preferably, at least two wear openings 27 are provided for each ring segment 14a. In the illustrated example, the wear opening 27 starts from the outer peripheral surface 23 or the outer peripheral groove 20 disposed here on the outer peripheral surface 23, and extends in the radial direction of the packing ring 14 (parallel to the axial ring ends RE1, RE2) toward the inner peripheral surface 18 without reaching the inner peripheral surface 18, and is formed as a cylindrical hole.

[0050] When the wear opening 27 is drilled, the wear opening 27 may have a conical bottom corresponding to the drill used, as shown in the figure. When the wear opening 27 is, for example, milled by milling, the wear opening 27 generally has a substantially flat bottom. However, of course, other manufacturing means such as injection molding or additive manufacturing are also conceivable.

[0051] The length and diameter of the wear opening 27 are substantially determined by the desired pressure compensation characteristics of the packing ring 14. In this case, the length or the extension length is set in the radial direction such that the wear opening end 27a of the wear opening 27 is separated from the inner peripheral surface 18 by up to 40% of the radial ring height RH of the packing ring 14. In the example shown in FIGS. 2 to 4, the wear opening 27 is disposed at the center in the axial direction between both ring ends RE1, RE2. However, the wear opening 27 may also be disposed closer to one of the ring ends RE1, RE2, and preferably, it is separated by a wear opening axial distance y of 2% to 20%, preferably 2 to 15%, particularly at most 10% of the ring width RB from the first axial ring end RE1. The specific axial arrangement is substantially determined by the desired pressure compensation to be achieved by the packing ring 14.

[0052] At least one wear opening 27, or preferably a plurality of wear openings 27, of one ring segment 14a is set such that, from a specific wear state of the packing ring 14, a radially inner wear opening end 27a facing the inner peripheral surface 18 (see FIGS. 2 and particularly FIG. 6) is exposed. Thereby, the wear opening 27 will extend throughout from the outer peripheral surface 23 to the inner peripheral surface 18 starting from this wear state. Thus, starting from this wear state, the wear opening 27 acts in the same manner as the relief opening 25 (not shown). In particular in this case, during operation of the compressor, the wear opening 27 increases the pressure compensation between the inner peripheral surface 18 and the outer peripheral surface 23 of the packing ring 14, whereby, for example, undesired premature crushing of the packing ring 14 can be avoided.

[0053] However, since a high pressure P is also applied to the second axial ring end RE2, the wear opening 27 may extend towards the inner peripheral surface 18 starting from the second axial ring end RE2, similar to the relief opening 25 (suggested by the dashed line in the cross-section B - B shown in FIG. 6, for example). H

[0054] For example, the wear opening 27 can be dimensioned such that from the worn state in which the wear opening 27 is exposed on the inner peripheral surface 18, substantially complete pressure compensation is performed between the inner peripheral surface 18 and the outer peripheral surface 23. Thereby, although the packing ring 14 will surely partially lose its sealing action, instead, the risk of breakage can be reduced, particularly avoided. In this case, complete pressure compensation means that for each radial force acting on the outer peripheral surface 23 and the inner peripheral surface 18 based on pressure, they are substantially completely balanced, so that in the radial direction, substantially no longer, the force generated by the differential pressure acts on the packing ring 14. That is, substantially, the packing ring 14 spontaneously becomes inoperative from a specific worn state. For this purpose, preferably, one or more other packing rings 14 of the sealing device 1 that may have less wear are assumed to still substantially normally exert their sealing action. Therefore, it is not necessary to immediately replace the inoperative packing ring 14, which may lead to the stop of the compressor. For example, it is considered that the set maintenance interval from a predetermined leakage amount that can be detected by measurement technology can be more easily observed.

[0055] Similar to the case of the relief opening 25 according to the present invention, it may be advantageous if at least one end of at least one wear opening 27 facing the inner peripheral surface 18 located radially inside is inclined by a wear opening angle φ toward the first axial ring end RE1, as will be described in more detail below with reference to FIG. 6, for example. Therefore, also in this case, the pressure compensation characteristics can be adapted through wear. Preferably, the wear openings 27 are each arranged in the circumferential direction between two relief openings 25, particularly preferably at the center between two relief openings 25.

[0056] In Fig. 3a, the packing ring 14 shown in Fig. 2 is illustrated in a view looking vertically down from above at the first axial ring end RE1 or preferably the flat first ring end face facing the low-pressure side in the assembled state. In Fig. 3b, one individual ring segment 14a of the packing ring 14 shown in Fig. 3a is shown. In Fig. 3b, the shape of the first axial segment recess disposed at the first segment end SE1 of the ring segment 14a so as to form the first tangential contact surface 19a and the first axial contact surface 16 can be recognized. As described above, since the first axial segment recess extends axially partially from the first axial ring end RE1 toward the second axial ring end RE2 located on the opposite side, the second segment end SE2 of the ring segment 14a that follows the first axial segment recess in the circumferential direction can engage with the first axial segment recess. That is, the adjacent ring segments 14a partially overlap in the circumferential direction, whereby the first tangential contact surface 19a of the first segment end SE1 of the ring segment 14a abuts against the second tangential contact surface 19b of the second segment end SE2 of the adjacent ring segment 14a, and a radial seal of the packing ring 14 can be formed. Similarly, the first axial contact surface 16 formed by each first axial segment recess of the first segment end SE1 of the ring segment 14a also abuts against the second axial contact surface 17 formed by each second axial segment recess of the second segment end SE2, and an axial seal of the packing ring 14 can be formed. The first axial segment recess and the second axial segment recess are arranged at the segment ends SE1, SE2 located on opposite sides of one ring segment 14a in the circumferential direction and at the axial ring ends RE1, RE2 located opposite to each other.

[0057] In this case, the segment ends SE1, SE2 cooperate such that in the circumferential direction, the tangential contact surfaces 19a, 19b face each other and can slide in contact with each other. As a result, the second wear limiting surface 21 of the second segment end SE2 of one ring segment 14a abuts against the first wear limiting surface 22 of the first axial segment recess of the first segment end SE1 of the adjacent ring segment 14a, which is arranged with a wear distance a (see FIGS. 2 and 3a), until the wear adjustment of the packing ring 14 becomes possible during operation. At the second segment end SE2 of the ring segment 14a, preferably at the transition between the second tangential contact surface 19b and the second wear limiting surface 21, an outer radius R2 with a specific radius is provided, whereby the wear adjustment or in particular the sliding contact of the respective tangential contact surfaces 19a, 19b can be promoted. For this purpose, advantageously, as shown in FIGS. 3b and 4b, an inner radius R1 is also provided between the first tangential contact surface 19a and the first wear limiting surface 22 at the first segment end SE1 as well.

[0058] The wear opening 27 is here formed as a blind hole with a conical bottom and extends from the outer peripheral surface 23, here the bottom of the circumferential groove 20, radially towards the inner peripheral surface 18 over a part of the ring height RH. In this case, the wear opening end 27a of each wear opening 27 is spaced from the inner peripheral surface 18 located radially inside by a distance of up to 40% of the radial ring height RH of the packing ring 14 in the radial direction of the ring segment 14a. In the illustrated packing ring 14, three inclined relief openings 25 and two wear openings 27 are provided for each ring segment 14a. The wear openings 27 are here arranged in the circumferential direction at the center between each relief opening 25. The wear openings 27 extend here in the radial direction of the packing ring 14 (parallel to the axial ring ends RE1, RE2), and the relief openings 25 are formed inclined according to the invention, i.e. inclined towards the first axial ring end RE1, whereby the pressure compensation can be increased according to wear. However, it is of course understood that this configuration is only exemplary, and the exact structural configuration, as well as the number and orientation of the relief openings 25 and / or wear openings 27, are of course left to the person skilled in the art and depend on the desired field of use of the packing ring 14 and the effect to be achieved, in particular the pressure compensation to be achieved. What is important for the present invention is that at least one relief opening 25 is provided in at least one ring segment 14a, in which case at least one part of the relief opening 25 in contact with the inner peripheral surface 18 located radially inside the ring segment 14a is inclined towards the first axial ring end RE1.

[0059] Figures 4a and 4b show a plan view of the second axial ring end RE2, in the assembled state, facing the high-pressure side of the compressor, of the packing ring 14 or of the individual ring segments 14a of the packing ring 14. In particular in FIG. 4b, a second axial segment recess provided at the second segment end SE2 of the ring segment 14a so as to form the second axial contact surface 17 can be seen. The second tangential contact surface 19b is provided radially outward at the second segment end SE2. The second axial segment recess extends axially from the second axial ring end RE2, in particular from the preferably flat second ring end face 28 provided thereon, towards the first axial ring end RE1, in particular the first flat ring end face. Furthermore, the second axial segment recess forms the second end face 29 of the second segment end SE2, which is spaced by a segment distance b from the first end face 30 of the first segment end SE1 of the adjacent ring segment 14a, as shown in FIG. 4a, next to the second axial contact surface 17. By the cooperation of the adjacent segment ends SE1, SE2, a radially complete through and axially defined radial recess 31 is produced in the packing ring 14, the width of the radial recess 31 corresponding to the segment distance b. As the wear of the packing ring 14 continues, the segment distance b, like the wear distance a (see FIGS. 2 and 3a), decreases until the wear distance a becomes zero (in this case, b > a). If the values are equal in the (new) non-worn state of the packing ring 14 (a = b), as wear progresses, the wear distance a becomes zero earlier than the segment distance b for kinematic reasons in the example shown. This depends substantially on the specific structural configuration, in particular the arrangement of the tangential contact surfaces 19a, 19b. However, alternatively, the end faces 29, 30 may be used as wear limit parts (in this case, a > b).

[0060] However, the tangential contact surfaces 19a, 19b may also extend continuously, for example, from the outer peripheral surface 23 to the inner peripheral surface 18. As a result, wear adjustment is no longer substantially restricted by the wear distance a as shown hitherto. Therefore, the first axial segment recess provided at the first segment end SE1 no longer has the first wear limiting surface 22, and the second segment end SE2 also no longer has the second wear limiting surface 221. In this case, the limitation of wear adjustment can be achieved, for example, by the radial recess 31 provided at the second axial ring end RE2, and the width of the radial recess 31 corresponds to the segment distance b as shown based on FIG. 4a.

[0061] Of course, in order to obtain the optimally applicable results as much as possible, the material and surface properties of the packing ring 14 may be changed. In one advantageous configuration, the packing ring 14 is made of a tribologically optimized suitable material, for example, a polytetrafluoroethylene (PTFE) composite material. The manufacturing may be carried out, for example, by cutting-type manufacturing, injection molding, or by an additive method such as 3D printing.

[0062] FIG. 5a schematically shows, based on a longitudinal cross-section, the pressure state in a conventional packing ring 7b (see FIG. 1) during operation of a compressor. In contrast, FIG. 5b shows the pressure state in a packing ring 14 according to the present invention. The packing ring 14 is preferably arranged, for example as shown in FIG. 1, in a sealing device 1 (not shown) arranged in the crankcase of a compressor, for example, to seal the piston rod 2. The packing rings 7b, 14 are arranged such that each first axial ring end RE1 faces the low-pressure side (crankcase side), and each second axial ring end RE2 faces the high-pressure side (cylinder side). The packing rings 7b, 14 are arranged such that each first axial ring end RE1 abuts against the casing segment 3i of the sealing device 1, thereby forming a radial seal between the first axial ring end RE1 and the casing segment 3i. This seal corresponds substantially to a static seal. This is because there is no or only very little relative movement between the first axial ring end RE1 of the packing ring 14 and the casing segment 3i.

[0063] In this case, at the first axial ring end RE1, a high pressure P is applied to the outer peripheral surface 23 located radially outward, while a relatively low pressure P is applied to the inner peripheral surface 18 located radially inward. H The high pressure P decreases to a lower pressure P in the radial direction, and in this case, the pressure characteristic line transitions non-linearly in the illustrated example. A high pressure P is applied to the second axial ring end RE2, and the high pressure P is substantially constant over the radial ring height RH between the outer peripheral surface 23 located radially outward and the inner peripheral surface 18 located radially inward. It should be noted here that the pressure in the sealing device 1 is from the high pressure P in the cylinder in the axial direction to the low pressure P in the crankcase. N H N H H H N ​​​​​​It gradually decreases step by step through each of the packing rings 14 in the number provided at that time. That is, the pressure states in the respective packing rings 14 of the sealing device 1 are naturally different from each other. Therefore, the high pressure P applied to the first packing ring 14 facing the cylinder H does not correspond to the high pressure P H applied to the subsequent packing rings 14 and the like. That is, the high pressure P H and the low pressure P N in this specification relate to each one packing ring 14 respectively. The low pressure P N in one packing ring 14 substantially corresponds to the high pressure P H of the packing rings 14 and the like continuing in the axial direction (towards the crankcase) respectively.

[0064] Similarly, the high pressure P H is applied to the outer peripheral surface 23 located radially outside. In this case, this pressure is substantially constant over the axial ring width RB of the packing ring 14 between the second axial ring end RE2 and the first axial ring end RE1. During operation, on the inner peripheral surface 18 located radially inside and in contact with the reciprocating oscillating piston rod 2, the high pressure P H at the second axial ring end RE2 (cylinder side) and the relatively low pressure P N at the first axial ring end RE1 (crankcase side) perform sealing. In this case, it is a dynamic seal based on the relative movement between the (position-fixed) packing ring 14 and the reciprocating oscillating piston rod 2. As suggested in FIG. 5a, a substantially linear pressure characteristic line is generated along the inner peripheral surface 18 located radially inside. In this case, the pressure decreases from the high pressure P H (at the second axial ring end RE2) to the low pressure P N (at the first axial ring end RE1). Basically, the pressure drop in the axial direction on the inner peripheral surface 18 is also non-linear based on the compressibility of the gaseous medium, but in a specific case (for example, at a high absolute pressure, the high pressure P H and the low pressure P NWhen the differential pressure between them is small), as shown in the figure, the pressure characteristic line can be easily approximated to a linear function for simplicity. That is, in the example shown in Fig. 5a, the packing ring 7b is pressed more strongly in the radial direction by the piston rod 2 based on a larger radial differential pressure compared to the packing ring 14 according to the present invention, which is disadvantageous because this will lead to greater wear. Additionally, the packing ring 7b shown in Fig. 5a is pressed more strongly against the piston rod 2 in the region of the first axial ring end RE1 than at the second axial ring end RE2 based on a larger radial differential pressure. This non-uniform pressure distribution may additionally result in non-uniform wear in some cases, which is also disadvantageous.

[0065] Fig. 5b shows a cross-section of the packing ring 14 according to the present invention. In this case, this cross-sectional view is formed here as a cylindrical hole and extends into the region of the relief opening 25 inclined towards the first axial ring end RE1 of the packing ring 14. As described, at least one relief opening 25 is provided for each ring segment 14a. Preferably, as shown in Fig. 2, a plurality of, for example, three relief openings 25 are provided for each ring segment 14a, whereby the pressure characteristic line in the circumferential direction can be made as uniform as possible. The pressure characteristic lines at each axial ring end RE1, RE2 and on the outer peripheral surface 23 located radially outside are substantially the same as those of the conventional packing ring 7b shown in Fig. 5a. In this case, the pressure characteristic line on the dynamic seal surface along the inner peripheral surface 18 located radially inside between the piston rod 2 and the packing ring 14 is intentionally affected by at least one relief opening 25 for each ring segment 14a.

[0066] As is apparent from Fig. 5b, the pressure compensation is between the outer peripheral surface 23 (high pressure P H ) located radially outside and the inner peripheral surface 18 (low pressure P N) is carried out between them. That is, the pressure between the second axial ring end RE2 (cylinder side) and the defining portion of the first relief opening end 25a of the relief opening 25 facing the first axial ring end RE1 is substantially constant. From the defining portion of the first relief opening end 25a of the relief opening facing the first axial ring end RE1 and the first axial ring end RE1, the pressure is the high pressure P H to a relatively low pressure P N with respect to this. In this case, the pressure characteristic line is substantially linear as already described with reference to FIG. 5a.

[0067] Different from the packing ring 7b shown in FIG. 5a, in the packing ring 14 shown in FIG. 5b, substantially complete pressure compensation is carried out axially in the region between the second axial ring end RE2 and the defining portion of the first relief opening end 25a of the relief opening 25 facing the first axial ring end RE1. The differential pressure ΔP between the pressure characteristic line shown in FIG. 5a and the pressure characteristic line shown in FIG. 5b is written in parallel lines in FIG. 5b. What results from this is that the packing ring 14 is supported over a longer region axially than the conventional packing ring 7b based on radial pressure compensation, and barely in the region between the defining portion of the first relief opening end 25a facing the first axial ring end RE1 and the first axial ring end RE1, it is pressed more strongly against the piston rod 2 based on the radial differential pressure.

[0068] The maximum pressure compensation is substantially limited in practice by the circumferential distance z between each relief opening 25, the axial relief opening distance x of the relief opening end 25a from the first axial ring end RE1, and the material properties of the packing ring 14. The structural configuration preferably ensures a sufficiently high strength of the packing ring 14 in the given material, so that, as far as possible, no deformation and thus no associated leakage occur in the region between the first relief opening end 25a and the first axial ring end RE1 of the packing ring 14. The circumferential distance z between each relief opening 25 in the circumferential direction and the axial relief opening distance x between each relief opening 25 and the first axial ring end RE1 in the axial direction are selected such that this is the case.

[0069] To ensure this, the circumferential distance z between the relief openings is preferably at least 1 mm (~15 mm), the axial relief opening distance x is preferably 4% - 40% of the axial ring width RB, the relief opening length (at least at the relief opening end 25a) of the relief opening 25 is preferably 2% - 100% of the ring width RB, and the axial relief opening width (at least at the relief opening end 25a) of the relief opening 25 is preferably 2% - 30% of the axial ring width RB. In this case, the axial relief opening width of the relief opening end 25a and the axial relief opening distance x are adjusted to each other such that the condition is satisfied that each relief opening end 25a is eccentrically located between the respective axial ring ends RE1, RE2, i.e., is located closer to the first axial ring end RE1 than to the second axial ring end RE2. If the circumferential distance z between the relief openings is extremely small, the ring is extremely weakened, which may lead to undesirable deformation and more leakage. On the other hand, if the circumferential distance z between the relief openings is extremely large, there is a high pressure P between each relief opening 25a Hmay not be fully formed in some cases. This leads to an unfavorable pressure distribution in the circumferential direction and thus insufficient pressure compensation, which may also result in higher frictional forces and, consequently, greater ring wear. Of course, it is understood that the size, shape, and arrangement of the relief opening 25 shown in FIG. 5b are merely exemplary, and the specific structural configuration is directed towards the field of use of the packing ring 14 and remains entrusted to those skilled in the art. Based on the inclination according to the invention of the relief opening 25 (in at least one part of the relief opening 25 that contacts the inner circumferential surface 18 located radially inside the ring segment 14a), the pressure compensation is adapted to the radial wear of the packing ring 14 that occurs during the operation of the piston compressor. Due to the radial wear, the inner circumferential surface 18 "moves" substantially towards the outer circumferential surface 23. This also leads to the fact that, based on the inclination of the relief opening 25, the first relief opening end 25a of the relief opening 25 also "moves" axially towards the first axial ring end RE1 in response to the wear. As a result, the relief opening axial distance x decreases and, consequently, the pressure compensation of the packing ring 14 increases. This is because the high pressure P on the inner circumferential surface 18 H is brought closer to the first axial ring end RE1.

[0070] FIG. 6 illustrates various possibilities of the arrangement of the relief opening 25 and the wear opening 27 based on a plurality of longitudinal cross-sections A-A to D-D of the packing ring 14. The relief opening 25 shown in cross-section A-A extends in the radial direction of the packing ring 14, that is, substantially parallel to both axial ring ends RE1, RE2. The relief opening 25 has a circular cross-section and is spaced from the first axial ring end RE1 by a relief opening axial distance x measured from the defining portion of the first relief opening end 25a of the relief opening 25 facing the first axial ring end RE1. The relief opening axial distance x is adjusted according to the field of use of the packing ring 14, particularly to the desired pressure characteristic line on the inner peripheral surface 18 located radially inside the packing ring, as shown in the example of the inclined relief opening 25 based on FIG. 5b. The relief opening axial distance x is preferably 4% to 40%, advantageously 4 to 30%, particularly preferably 4 to 20%, most particularly preferably 4 to 15%, especially at most 10% of the axial ring width RB of the packing ring 14. As already explained, it is desirable that the relief opening axial distance x does not fall below a predetermined minimum distance in order to ensure a sufficiently high strength of the packing ring 14, and in this case the minimum distance is 4% of the axial ring width RB. That is, when the relief opening 25 is formed as a radially continuous hole as shown, it is preferably provided mainly in the half facing the low-pressure side of the packing ring 14. Additionally, with respect to at least one relief opening 25 inclined towards the first axial ring end RE1 according to the present invention, one or more relief openings 25 that are not inclined towards the first axial ring end RE1 in this way may be provided.

[0071] When the relief opening 25 is formed as a cylindrical hole, the relief opening diameter d EThe axial ring width RB of the packing ring 14 is preferably 2 to 30%, preferably 2 to 25%, particularly preferably 2 to 20%, and particularly at most 15%. However, the relief opening 25 may also have a non-circular, preferably constant cross-section, for example an elliptical cross-section or a cross-section in the form of a slot. In this case, the said dimension applies to the axial relief opening width of the relief opening 25.

[0072] Regardless of the cross-sectional shape and extent of the relief opening 25, generally speaking, it is applicable that the first relief opening end 25a of the relief opening 25 is eccentrically arranged on the radially inner peripheral surface 18. That is, the first relief opening end 25a of the relief opening 25 is located closer to the first axial ring end RE1 than the second axial ring end RE2 in the axial direction. Thus, the axial relief opening width of the relief opening 25 at the first relief opening end 25a, for example the diameter in the case of a circular cross-section, depends on the relief opening axial distance x. That is, the greater the relief opening axial distance x from the first ring end RE1, the smaller the maximum axial relief opening width, whereby it is ensured that the relief opening end 25a is located closer to the first axial ring end RE1 than the second axial ring end RE2 in the axial direction.

[0073] As already described and as shown in FIG. 2, based on the present invention, at least one relief opening 25 is provided in at least one ring segment 14a, which (at least partially) inclines towards the first axial ring end RE1 as illustrated in cross-section D-D of FIG. 6. Here, the relief opening 25 has a circular cross-section similar to cross-section A-A, provided that the relief opening 25 is arranged to be inclined by a relief opening angle ε with respect to the radial direction in the axial direction, whereby, based on the present invention, pressure compensation can be adapted to radial wear. Thus, the second relief opening end 25b on the radially outer side of the relief opening is located closer to the first axial ring end RE1 than the first relief opening end 25a on the radially inner side. In the illustrated example, the relief opening angle ε is measured between the first axial ring end RE1 and the axis of the relief opening 25 formed as a cylindrical hole. The relief opening axial distance x is measured, as already described, from the defining part of the first relief opening end 25a facing the first axial ring end RE1 on the inner circumferential surface 18 located on the radially inner side. The value of the relief opening axial distance x is, of course, related to the new state of the packing ring 14 without wear. However, the relief opening 25 may additionally have an extension offset in the radial direction when viewed in plan view (FIGS. 3 and 4) with respect to the (at least partial) inclination towards the first axial ring end RE1 (e.g., the longitudinal cross-section D-D shown in FIG. 6), that is, it may be inclined as will be further described in more detail below based on FIG. 8b.

[0074] By arranging at least one relief opening 25 to be inclined, the pressure compensation can be varied according to the wear of the packing ring 14. This is because the axial position of the relief opening end 25a on the radially inner side changes according to the wear. In the illustrated example, when radial wear v of the packing ring 14 occurs, the relief opening end 25a moves towards the first axial ring end RE1. That is, the relief opening axial distance x when radial wear v occurs vis smaller than the relief opening axial distance x in the new state of the packing ring 14. The value x of the relief opening axial distance v Of course, it depends on the relief opening angle ε. Thereby, the pressure compensation becomes larger in the axial direction according to the wear state of the packing ring 14. In this case, the degree of pressure compensation can be selected according to the magnitude of the relief opening angle ε.

[0075] However, the relief opening 25 does not necessarily need to be formed with an overall inclination over its entire length. Basically, it is sufficient that only the portion of the relief opening 25 in contact with the inner peripheral surface 18 is inclined toward the first axial ring end RE1. The remaining portion of the relief opening 25 facing the outer peripheral surface 23 may extend parallel to each ring end RE1, RE2, as suggested by the dashed line in cross-section D-D. Therefore, the pressure compensation of the partially inclined relief opening 25 depends on wear until wear v is achieved and the inclined portion of the relief opening 25 substantially completely disappears (the first relief opening end 25a moves toward the first ring end RE1).

[0076] When the wear progresses further, the pressure compensation is kept substantially constant based on the straight portion (illustrated by the dashed line) of the relief opening 25. This is because the first relief opening end 25a does not move further toward the first ring end RE1. In this case, the length of the inclined portion of the relief opening 25 in the radial direction of the packing ring 14 is preferably 0 to 60%, particularly preferably 40% of the ring height RH. Of course, the entire relief opening 25 or the portion of the relief opening 25 in contact with the inner peripheral surface 18 may have an overall or partial curved extension instead of a straight extension. In this case, the relief opening 25 or the portion of the relief opening 25 in contact with the inner peripheral surface 18 may be curved toward the first axial ring end RE1, whereby the first relief opening end 25a will move toward the first ring end RE1 according to wear.

[0077] In another advantageous configuration of the invention, in addition to at least one relief opening 25 inclined according to the invention as described above, as described above with reference to FIG. 2, one or more wear openings 27 may be provided in at least one ring segment 14a of the packing ring 14. In the cross-section B-B shown in FIG. 6, a wear opening 27 in the form of a cylindrical hole having a conical bottom and a wear opening diameter d v is shown. The wear opening 27 extends here in the radial direction of the packing ring 14, i.e., parallel to the first and second axial ring ends RE1, RE2 in the example shown. However, unlike the relief opening 25, the wear opening 27 starts from the outer peripheral surface 23 located on the outer side in the radial direction of the packing ring 14 and extends only over a part of the ring height RH towards the inner peripheral surface 18 located on the inner side in the radial direction and does not reach the inner peripheral surface 18 (in the new state without wear). That is, the wear opening 27 connects the outer peripheral surface 23 located on the outer side in the radial direction of the packing ring 14 to the inner peripheral surface 18 located on the inner side in the radial direction only from a predetermined radial wear v of the packing ring. Therefore, the wear opening 27 contributes to pressure compensation only from the wear state v and, in this case, performs substantially the same function as the relief opening 25.

[0078] At least one wear opening 27 is spaced apart from the first axial ring end RE1 by a wear opening axial distance y, where the wear opening axial distance y is measured from the point on the wear opening 27 that is located closest to the inner circumferential surface 18 in the radial direction. This is because this point is first exposed by wear. That is, the wear opening 27 is not connected to the first axial ring end RE1, but is only connected to the outer circumferential surface 23 located radially outside and / or the second axial ring end RE2. Thus, generally, the radially inner wear opening end 27a facing the inner circumferential surface 18 is located between the first axial ring end RE1 and the second axial ring end RE2. Thus, the wear opening end 27a is surrounded by the material of the packing ring 14 when viewed in the axial and circumferential directions. In the illustrated example (section B - B), the wear opening 27 is formed as a hole having a conical bottom, and thus the wear opening axial distance y is measured to the tip of the wear opening end 27a. The wear opening axial distance y may be the same size as the relief opening axial distance x, but may be different, for example, as suggested in FIG. 6. Preferably, the wear opening axial distance y is 2 to 20%, particularly preferably 2 to 15%, and especially at most 10% of the axial ring width RB of the packing ring 14.

[0079] The radial extent of the wear opening 27 starting from the outer circumferential surface 23 on the outer side in the radial direction, here the wear opening depth t of a cylindrical hole v is such that the wear opening end 27a is spaced apart from the inner circumferential surface 18 in the radial direction by a distance that is at most 40% of the radial ring height RH, and is preferably selected according to the expected wear v of the packing ring 14. For example, the time until a specific wear v of a specific packing ring material is achieved can be detected in a test taking into account the surface roughness of the piston rod 2 under specific operating conditions. From this, for example, it is possible to estimate how long the compressor can operate (for example, the number of operating hours) until the wear v is achieved. In this case, the wear opening depth t of the wear opening 27 vThe wear opening 27 can be set to connect the outer peripheral surface 23 in the radial outer direction to the inner peripheral surface 18 in the radial inner direction from a predetermined number of operating hours, and from this point on, it can be set to enable an increase in pressure compensation.

[0080] However, also similar to at least one relief opening 25 inclined according to the present invention, at least one wear opening 27 inclined towards the first axial ring end RE1 may be provided in the packing ring 14 at at least one end facing the inner peripheral surface 18 located in the radial inner direction. Preferably, however, not only the end of the wear opening 27 (as suggested by the dashed line in cross-section C-C) is inclined, but the entire wear opening 27 is inclined. In particular, at least one wear opening 27 may be formed as a cylindrical hole extending obliquely from the outer peripheral surface 23 located in the radial outer direction towards the inner peripheral surface 18 located in the radial inner direction, as shown in cross-section C-C in FIG. 6. The wear opening 27 is here inclined by a wear opening angle φ with respect to the first axial ring end RE1. Thereby, similar to the straight configuration (cross-section B-B), an increase in pressure compensation is performed from wear v. Additionally, in the case of the inclined aspect shown in cross-section C-C, as already explained based on the relief opening 25 (cross-section D-D) inclined towards the first axial ring end RE1 according to the present invention, the pressure compensation automatically increases from wear v in response to further progressing wear. In the case of the inclined hole, the wear opening depth t v does not correspond to the hole depth, but rather corresponds to the maximum extent in the radial direction of the wear opening 27 starting from the outer peripheral surface 23 located in the radial outer direction, as shown in cross-section C-C.

[0081] The wear opening diameter d of the wear opening 27 v (in the case of a circular cross-section) may, for example, correspond to the relief opening diameter d E or the relief opening diameter d EIt may be different. Similarly, the wear opening angle φ between the wear opening 27 and the first axial ring end RE1 may correspond to the relief opening angle ε or may be different from the relief opening angle ε. This also depends on the surrounding conditions under which the packing ring 14 is used and the desired characteristics regarding the pressure compensation to be achieved.

[0082] However, the relief opening 25 and / or the wear opening 27 do not necessarily have to open to the outer peripheral surface 23 located radially outside the packing ring 14. For example, as suggested by the dashed lines in cross-section A-A for the relief opening 25 and in cross-section B-B for the wear opening, it is conceivable that the relief opening 25 and / or the wear opening 27 extend additionally or alternatively within the second axial ring end RE2. The high pressure P on the cylinder side H is also applied to the second axial ring end RE2, so the effect of pressure compensation can also be achieved by the relief opening 25 connecting the inner peripheral surface 18 located radially inside to the second axial ring end RE2 or by the wear opening 27 connecting the inner peripheral surface 18 to the second axial ring end RE2 from a predetermined wear v. However, based on easier manufacturing, it is advantageous if the relief opening 25 and / or the wear opening 27 are arranged starting from the outer peripheral surface 23 located radially outside the packing ring 14, particularly in the form of a cylindrical hole, up to or towards the inner peripheral surface 18 located radially inside.

[0083] In another advantageous configuration of the packing ring 14, as shown respectively based on one ring segment 14a in FIGS. 7a to 7d, at least one compensation recess 32 may be provided in the packing ring 14. The at least one compensation recess 32 extends from the outer peripheral surface 23 located radially outside the packing ring 14 over a part of the ring height RH towards the inner peripheral surface 18 located radially inside the packing ring 14 and over a part of the ring width RB from the first axial ring end RE1 towards the second axial ring end RE2. The compensation recess 32 serves substantially to reduce the frictional force in the contact surface between the axial compressive force during the operation of the compressor and thus between the first axial ring end RE1 and the casing segment 3i of the sealing device 1 (schematically shown in the cross-section E-E of FIG. 7a).

[0084] Particularly in the case of a packing ring 14 with significantly pressure compensation (for example, a large number of relief openings 25, a smaller circumferential distance z of the relief openings, a smaller axial distance x of the relief openings), due to the large pressure compensation, it may occur that during operation, the packing ring 14 is pressed against the piston rod 2 only by a relatively small resultant force in the radial direction (for example, see FIG. 5b). In the case of the lateral movement of the piston rod 2 that may occur during operation, the packing ring 14 without the compensation recess 32 may be able to follow only insufficiently based on the friction in the contact surface between the first axial ring end RE1 and the casing segment 3i, which may cause the packing ring 14 to be lifted radially from the piston rod 2 and thus lead to undesirable leakage. The compensation recess 32 reduces the frictional force acting against the lateral movement of the packing ring 14, so that the packing ring 14 can follow the movement of the piston rod 2 better in the radial direction. The compensation recess 32 may be formed in various ways, as will be described in detail below based on FIGS. 7a to 7d. In this case, on the left side, each ring segment 14a is shown in a plan view, and on the right side, cross-sectional views corresponding to each cross-section line are shown respectively.

[0085] In FIG. 7a, the compensation recess 32 has a width bA It is processed and formed in the shape of an elongated groove. As can be seen from the left figure, it has a first compensation recess end 32a and a second compensation recess end 32b that is spaced from the first compensation recess end 32a by a predetermined angle in the circumferential direction. The maximum radial extension length h of the compensation recess 32, which is clear in cross-section E-E A is preferably 60% of the radial ring height RH. Thereby, in order to achieve a radial seal, it is ensured that a sufficiently large static seal surface in contact with the contact surface in the casing segment 3i is provided at the first axial ring end RE1. The maximum radial extension length h of the compensation recess 32 in the radial direction A is applied regardless of the structural configuration of the compensation recess 32. The maximum compensation recess depth t of the compensation recess 32 in the axial direction of the packing ring 14 A is 1 to 40% of the ring width RB of the packing ring 14, preferably 0.5 mm, and this also applies regardless of the structural configuration of the compensation recess 32 (Figs. 7a to 7d).

[0086] The configuration shown in Fig. 7b has a plurality of separate compensation recesses 32 arranged at intervals in the circumferential direction as shown in the left plan view. Thereby, the compensation recesses 32 arranged to be located on the outer side (at the segment ends SE1, SE2) in the circumferential direction may be dimensioned separately from, for example, the compensation recesses 32 located therebetween, whereby the pressing force can be changed in the circumferential direction. The cross-section F-F shown on the right also shows the radial extension length h A as well as the compensation recess depth t A are shown.

[0087] The configuration of the compensation recess 32 shown in Fig. 7c substantially corresponds to the configuration shown in Fig. 7a. However, as is clear from the left side plan view, the compensation recess 32 has a plurality of additional compensation recess openings 32c in the region located between the first compensation recess end 32a and the second compensation recess end 32b in the circumferential direction. These compensation recess openings 32c are different in that they connect the compensation recess 32 to the outer peripheral surface 23 located radially outward in the radial direction. In the cross-section G-G shown on the right side, the radial extension length h A as well as the compensation recess depth t A are also shown.

[0088] Fig. 7d shows another configuration of the compensation recess 32. In this case, as shown in the left side plan view, the compensation recess 32 is connected to the outer peripheral surface 23 of the packing ring in the radial direction over the entire circumferential extension length thereof. As a result, a relatively large contact surface on which the high pressure P H on the cylinder side can act is generated in the casing segment 3i, whereby the axial pressing force of the packing ring 14 on the casing segment 3i can be significantly reduced as compared with the embodiments shown in Figs. 7a to 7c. In the cross-section H-H shown on the right side, the radial extension length h A as well as the compensation recess depth t A of the corresponding compensation recess 32 are also shown.

[0089] However, of course, each of the illustrated embodiments is merely exemplary and shows non-limitingly possible structural configurations of the compensation recess 32. Of course, those skilled in the art can also provide a compensation recess 32 with a different configuration.

[0090] Figures 8a to 8d illustrate another advantageous configuration of one of the packing rings 14 according to the present invention, based on one ring segment 14a. As already fully explained, the packing ring 14 is provided with at least one relief opening 25, and in this case, at least one portion of the relief opening 25 that contacts the inner peripheral surface 18 located radially inside the ring segment 14a is inclined toward the first axial ring end RE1. In FIG. 8, for each ring segment 14a, four relief openings 25 are arranged at a circumferential distance z of the relief openings from each other. However, the circumferential distance z of the relief openings does not have to be the same for all the relief openings 25 (as shown in the figure), and may be different, for example.

[0091] On the inner peripheral surface 18 located radially inside at least one ring segment 14a of the packing ring 14, at least one butting recess 33 is provided based on another advantageous configuration of the present invention. The at least one butting recess 33 extends from the second axial ring end RE2 over a part of the ring width RB in the axial direction of the ring segment 14a toward the first axial ring end RE1. In the radial direction of the ring segment 14a, the butting recess 33 extends from the inner peripheral surface 18 located radially inside the ring segment 14a over a very small part of the ring height RH toward the outer peripheral surface 23 located radially outside the ring segment 14a. In the circumferential direction, the butting recess 33 is arranged at an interval from each segment end SE1, SE2. FIG. 8d shows an isometric view of the ring segment 14a, where the butting recess 33 can be clearly seen. In the illustrated example, only one butting recess 33 is provided in the ring segment 14a. Of course, a plurality of butting recesses 33 smaller than the illustrated butting recess 33 may be provided in the ring segment 14a, arranged at intervals from each other in the circumferential direction.

[0092] The arrangement of the butting recess 33 is applied in particular to the packing ring 14 which is significantly pressure-compensated (for example, a large number of relief openings 25, a smaller circumferential distance z of the relief openings, and a smaller axial distance x of the relief openings). In the case of such a packing ring 14, when the compressor starts from a stopped state to high-speed operation, there is a risk of an increase in leakage. This is because the radial crimping pressure pressing the packing ring 14 against the piston rod 2 may be insufficient in some cases to compensate for manufacturing errors due to manufacturing or bulges that may occur in the packing ring 14 and / or the piston rod 2. By arranging at least one butting recess 33, the packing ring 14 will abut against the piston rod 2 at a relatively small butting surface 34 compared to the entire inner circumferential surface 18 located radially inward at the start of the high-speed operation stage. Thereby, the surface pressure based on pressure is increased at the butting surface 34 at the start of the high-speed operation stage, which results in an improved sealing effect and thus less leakage. In this context, the high-speed operation stage means not only the first start-up of the piston compressor but also all start-ups from a stopped state (as long as at least the butting surface 34 exists). Preferably, at least one butting recess 33 is dimensioned such that the remaining butting surface 34 of one ring segment 14a is 25% - 75%, preferably 60%, of the inner circumferential surface 18 of the ring segment 14a. When a plurality of butting recesses 33 are arranged in the ring segment 14a, the area ratio relates to the sum of the individual areas of the butting recesses 33 with respect to the inner circumferential surface 18 of the ring segment 14a.

[0093] In FIG. 8a, one ring segment 14a of the packing ring 14 is shown in a view looking at the inner circumferential surface 18 located radially inward from the vertical direction. During operation of the piston compressor, the high pressure P on the cylinder side H Starting from the second axial ring end RE2 to which the high pressure P is applied, the butting recess 33 extends over a part of the ring width RB towards the first axial ring end RE1, and at the first axial ring end RE1, during operation, the high pressure P H against which the relatively low pressure P Nis dominant. The butt joint recess width b in the axial direction of the packing ring 14 AL is preferably 30% to 90%, particularly 65% of the axial ring width RB in order to exhibit a sufficiently high effect during high-speed operation of the compressor. Further, in FIG. 8a, the first relief opening end 25a of the relief opening 25, which are separated from each other by a relief opening circumferential distance z in the circumferential direction (measured from the defined portions facing each other of the relief opening end 25a), is observed.

[0094] FIG. 8b shows a plan view of the first axial ring end RE1 of the ring segment 14a. FIG. 8c shows a longitudinal section of the ring segment 14a in the region of one relief opening 25 based on the section line J-J shown in FIG. 8b. In FIG. 8c, a very small radial butt joint recess depth t compared to the radial ring height RH AL is observed, and the butt joint recess depth t AL varies within the range of 1% to a maximum of 3% of the radial ring height RH, particularly preferably by 2%. This very small butt joint recess depth t ALBased on this, during normal operation of the compressor, the characteristics of the packing ring 14 are basically unchanged, and the butting characteristics are improved as described by the butting characteristics. Therefore, the butting recess 33 is not a circumferential groove in the conventional sense that connects the relief openings 25 to each other and thus contributes little or negligibly to pressure compensation during operation of the compressor. When the butting surface 34 wears, the packing ring 14 behaves like a ring without the butting recess 33. That is, within the framework of the present invention, the fact that the relief opening end 25a of the relief opening 25 opens directly into the inner peripheral surface 18 located radially inward means that it also opens into the butting recess 33. That is, the pressure state shown based on FIG. 5b substantially also applies to the packing ring 14 provided with the butting recess 33. When a plurality of butting recesses 33 are provided in one packing ring 14, for example, when one butting recess 33 is provided for each ring segment 14a (as shown in the figure) or when a plurality of butting recesses 33 are provided for each ring segment 14a, these butting recesses 33 may be formed differently from each other. For example, the butting recesses 33 may have different radial butting recess depths t AL and / or different shapes and / or different butting recess widths b in the axial direction AL It may have. However, in particular, the peripheral conditions regarding the remaining butting surface 34 are the same. Due to manufacturing, the butting recess 33 may optionally have a specific radius on the edge, for example, based on the geometry of the cutting tool used, such as a milling cutter.

[0095] Again, in Fig. 8b, relief openings 25 in various forms as well as wear openings 27 (not visible) are shown by dashed lines. The relief opening 25-1 disposed at the second segment end SE2 of the ring segment 14a is different here from the remaining three relief openings 25-2. As is apparent in Fig. 8c, the relief opening 25-2 is formed as a cylindrical through-hole, extending in the radial direction of the packing ring 14 or here the ring segment 14a, and inclined towards the first axial ring end RE1. That is, the relief opening 25-2 has a specific relief opening angle ε>0 in order to adapt the pressure compensation to the radial wear of the packing ring 14 according to the present invention. However, of course, only one relief opening 25-2 may be formed in an inclined manner, and the other relief openings 25-2 may extend parallel to the first and second ring ends RE1, RE2, for example, as is apparent in the cross-section A-A shown in Fig. 6.

[0096] The relief opening 25-1 disposed at the second segment end SE2 of the ring segment 14a extends in a direction different from the radial direction of the ring segment 14a here. Different from the relief opening 25-2 inclined axially by the first relief opening angle ε, the relief opening 25-1 is arranged to be displaced by the second relief opening angle ω from the radial direction in the plane of the figure. That is, substantially, the second relief opening end 25-1b opening to the outer peripheral surface 23 located on the outer side in the radial direction of the packing ring 14 is separated from the first relief opening end 25-1a opening to the inner peripheral surface 18 located on the inner side in the circumferential direction as shown in Fig. 8b.

[0097] The distance between the relief opening ends 25-1a and 25-1b is obtained from ω×Da, where ω is the relief opening angle and Da is the outer diameter of the packing ring 14. Based on this inclined arrangement of the relief opening 25-1, pressure compensation is also possible for the portion of the inner circumferential surface 18 located inside and near the second segment end SE2. Such pressure compensation cannot be achieved or is only difficult to achieve by one relief opening 25 extending radially (in the plane of the drawing shown in Fig. 8b) similar to the relief opening 25-2, due to the overlap of the segment ends SE2 and SE1 of the two adjacent ring segments 14a. However, of course, it is also conceivable that one or more relief openings 25, which are displaced by only the first relief opening angle ε and displaced by the second relief opening angle ω from the radial direction, are provided in one packing ring 14 or one ring segment 14a. That is, the first relief opening end 25a may be separated from the second relief opening end 25b both in the axial direction and in the circumferential direction.

[0098] The two wear openings 27 extend radially here in the ring segment 14a. As is clear from Fig. 8b, the two wear openings 27 having different depths t v1 >t v2 extend from the outer circumferential surface 23 located radially outside the packing ring 14 towards the inner circumferential surface 18 located radially inside. For wear v = RH - t v1 in the case, first, the wear opening 27 having the depth t v1 is exposed, and when the wear progresses to v = RH - t v2 , the wear opening 27 having the depth t v2 is exposed. Thereby, a substantially two-stage increase in pressure compensation is achieved. Of course, more or fewer wear openings 27 and / or relief openings 25 may be provided. One or more wear openings 27 may have various depths t vAlternatively or additionally, it may be arranged to be inclined by a first wear opening angle φ with respect to the radial direction of the packing ring 14 (see cross-section C-C shown in FIG. 6) and / or similar to the second relief opening angle ω as shown in FIG. 8b, it may be arranged to be inclined by a second wear opening angle λ (not shown).

[0099] Of course, in order to achieve the desired results, especially the desired pressure compensation of the packing ring 14, the illustrated embodiments of the present invention may be arbitrarily combined according to the application. Preferably, at least one packing ring 14 according to the present invention, particularly preferably a plurality of packing rings 14 according to the present invention, are arranged continuously in the axial direction within the sealing device 1 of the piston compressor shown in FIG. 1.

[0100] Finally, it should be pointed out again that the illustrated and described features of each embodiment shown in FIGS. 1 to 8d are considered to be independent of each other and may of course be used alone or in any combination. The packing ring 14 does not necessarily have to have a relief opening 25 and a wear opening as shown in FIG. 2, for example. In the simplest case, the packing ring 14 according to the present invention may have at least one relief opening 25 of any shape extending from the inner circumferential surface 18 to the outer circumferential surface 23 of the ring segment 14a and / or to the second axial ring end RE2, in which case at least one portion of at least one relief opening 25 in contact with the inner circumferential surface 18 located radially inside the ring segment 14a is inclined towards the first axial ring end RE1. Optionally, one or more relief openings 25 that are not inclined towards the first axial ring end RE1 may be provided and / or one or more wear openings 27 may be provided, and one or more of these wear openings 27 may also be inclined. Further optionally, one or more compensation recesses 32 and / or butting recesses 33 and / or axial grooves 24 and / or circumferential grooves 20 may be provided in the packing ring 14.

Claims

1. A packing ring (14) for sealing a reciprocating oscillating piston rod (2) having at least three ring segments (14a) each having a first segment end (SE1) and a second segment end (SE2) in the circumferential direction, wherein a first tangential contact surface (19a) of the first segment end (SE1) of one ring segment (14a) abuts against a second tangential contact surface (19b) of the second segment end (SE2) of the ring segment (14a) following in the circumferential direction of the ring segment (14a), thereby forming a radial seal of the packing ring (14), and a first axial contact surface (16) of the first segment end (SE1) of one ring segment (14a) facing the first axial ring end (RE1) of the packing ring (14) abuts against a second axial contact surface (17) of the second segment end (SE2) of the ring segment (14a) following in the circumferential direction of the ring segment (14a) facing the second axial ring end (RE2) of the packing ring (14), thereby forming an axial seal of the packing ring (14). In the packing ring (14), at least one relief opening (25) is provided in at least one ring segment (14a), the relief opening (25) extends from an inner circumferential surface (18) located radially inside the ring segment (14a) to an outer circumferential surface (23) located radially outside, and / or the relief opening (25) extends from the inner circumferential surface (18) located radially inside the ring segment (14a) to the second axial ring end (RE2) of the ring segment (14a), and at least one portion of at least one of the relief openings (25) in contact with the inner circumferential surface (18) located radially inside the ring segment (14a) is inclined or curved toward the first axial ring end (RE1), and the inner circumferential surface (18) is a surface that abuts against the piston rod (2). The packing ring (14) is characterized in that.

2. The first relief opening end (25a) of at least one of the relief openings (25) that opens to the inner peripheral surface (18) located radially inside the ring segment (14a) is separated from the first axial ring end (RE1) by a relief opening axial distance (x) of 4% to 40% of the axial ring width (RB) of the ring segment (14a). The packing ring (14) according to claim 1.

3. The first relief opening end (25a) of at least one of the relief openings (25) that opens to the inner peripheral surface (18) located radially inside the ring segment (14a) is separated from the first axial ring end (RE1) by a relief opening axial distance (x) of 4 to 20% of the axial ring width (RB) of the ring segment (14a). The packing ring (14) according to claim 1.

4. At least one of the relief openings (25) has a circumferential relief opening length that is 2 to 100% of the axial ring width (RB) of the packing ring (14) at least at the relief opening end (25a). The packing ring (14) according to any one of claims 1 to 3.

5. At least one of the relief openings (25) has a circumferential relief opening length that is 2 to 50% of the axial ring width (RB) of the packing ring (14) at least at the relief opening end (25a). The packing ring (14) according to any one of claims 1 to 3.

6. At least one of the relief openings (25) has a circumferential relief opening length that is at most 25% of the axial ring width (RB) of the packing ring (14) at least at the relief opening end (25a). The packing ring (14) according to claim 5.

7. At least two of the relief openings (25) are provided in at least one of the ring segments (14a), and each of these relief openings (25) has a first relief opening end (25a) that opens to the inner circumferential surface (18) located radially inside the ring segment (14a). The first relief opening ends (25a) of two of the relief openings (25) arranged side by side in the circumferential direction are spaced apart from each other by a relief opening circumferential distance (z). The packing ring (14) according to any one of claims 1 to 6.

8. The relief opening circumferential distance (z) is from 1 mm to 15 mm. The packing ring (14) according to claim 7.

9. At least one relief opening (25) is provided, and the first relief opening end (25a) of the relief opening (25) that opens to the inner circumferential surface (18) located radially inside the ring segment (14a) is spaced apart in the circumferential direction from the second relief opening end (25b) of the relief opening (25) that opens to the outer circumferential surface (23) located radially outside the ring segment (14a). The packing ring (14) according to any one of claims 1 to 8.

10. At least one of the relief openings (25) has an axial relief opening width that is 2 to 30% of the axial ring width (RB) of the packing ring (14) at least at the relief opening end (25a). The packing ring (14) according to any one of claims 1 to 9.

11. At least one of the relief openings (25) has an axial relief opening width that is 2 to 20% of the axial ring width (RB) of the packing ring (14) at least at the relief opening end (25a). The packing ring (14) according to any one of claims 1 to 9.

12. At least one of the relief openings (25) has a straight extension and a relief opening diameter (d) that is 2 to 30% of the axial ring width (RB) of the packing ring (14). Ｅ The packing ring (14) according to claim 10 or 11, having a constant circular cross-section with).

13. At least one of the relief openings (25) has a straight extension and a relief opening diameter (d) that is 2 to 20% of the axial ring width (RB) of the packing ring (14). Ｅ The packing ring (14) according to claim 10 or 11, having a constant circular cross-section with).

14. At least one axial groove (24) is provided on the outer peripheral surface (23) located radially outside at least one ring segment (14a), and the axial groove (24) extends from the first axial ring end (RE1) to the second axial ring end (RE2). The packing ring (14) according to any one of claims 1 to 13.

15. At least one axial groove (24) is provided on the outer peripheral surface (23) located radially outside each ring segment (14a), and the axial groove (24) extends from the first axial ring end (RE1) to the second axial ring end (RE2). The packing ring (14) according to any one of claims 1 to 13.

16. At least one wear opening (27) is provided in at least one ring segment (14a), and the wear opening (27) extends from the outer peripheral surface (23) located radially outside the ring segment (14a) towards the inner peripheral surface (18) located radially inside the ring segment (14a), and / or the wear opening (27) extends from the second axial ring end (RE2) of the ring segment (14a) in the direction of the inner peripheral surface (18) located radially inside the ring segment (14a). The radially inner wear opening end (27a) of at least one such wear opening (27) facing the inner peripheral surface (18) is separated by a distance of at most 40% of the radial ring height (RH) extending radially between the outer peripheral surface (23) located outside the ring segment (14a) and the inner peripheral surface (18) located radially inside the ring segment (14a) in the radial direction of the ring segment (14a) from the inner peripheral surface (18) located radially inside the ring segment (14a). The wear opening end (27a) is located between the first axial ring end (RE1) and the second axial ring end (RE2) and is separated from the first axial ring end (RE1) and the second axial ring end (RE2). The packing ring (14) according to any one of claims 1 to 15.

17. At least one end of at least one said wear opening (27) facing the inner peripheral surface (18) located radially inside is inclined towards the first axial ring end (RE1). The packing ring (14) according to claim 16.

18. At least one said wear opening (27) has a straight extension and a constant circular cross-section with a wear opening diameter (d ｖ ) that is 2 to 60% of the axial ring width (RB) of the packing ring (14). The packing ring (14) according to claim 16 or 17.

19. At least one of the wear openings (27) has a straight extension portion and a constant circular cross-section with a wear opening diameter (d ｖ ) that is 2 to 40% of the axial ring width (RB) of the packing ring (14). The packing ring (14) according to claim 16 or 17. **Claim 20** At least one of the wear openings (27) is axially spaced from the first axial ring end (RE1) by a wear opening axial distance (y) that is 2% to 20% of the axial ring width (RB). The packing ring (14) according to any one of claims 16 to 19. **Claim 21** At least one of the wear openings (27) is axially spaced from the first axial ring end (RE1) by a wear opening axial distance (y) that is 2 to 15% of the axial ring width (RB). The packing ring (14) according to any one of claims 16 to 19. **Claim 22** At least one compensation recess (32) is provided in at least one of the ring segments (14a), extending from the outer peripheral surface (23) located radially outside the ring segment (14a) towards the inner peripheral surface (18) located radially inside the ring segment (14a) and extending from the first axial ring end (RE1) towards the second axial ring end (RE2). The packing ring (14) according to any one of claims 1 to 21. **Claim 23** At least one compensation recess (32) is provided in each ring segment (14a), extending from the outer peripheral surface (23) located radially outside the ring segment (14a) towards the inner peripheral surface (18) located radially inside the ring segment (14a) and extending from the first axial ring end (RE1) towards the second axial ring end (RE2). The packing ring (14) according to any one of claims 1 to 21. **Claim 24** On the inner circumferential surface (18) located radially inside at least one of the ring segments (14a), there is provided at least one butt joint recess (33) extending in the axial direction of the ring segment (14a) from the second axial ring end portion (RE2) toward the first axial ring end portion (RE1) and extending in the radial direction of the ring segment (14a) from the inner circumferential surface (18) located radially inside the ring segment (14a) toward the outer circumferential surface (23) located radially outside the ring segment (14a). As a result, a relatively smaller butt joint surface (34) is formed with respect to the entire inner circumferential surface (18) located radially inside. The butt joint recess (33) has a radial butt joint recess depth (t ＡＬ ) that is up to 3% of the radial ring height (RH) extending between the outer circumferential surface (23) located outside the ring segment (14a) and the inner circumferential surface (18) located radially inside. The first relief opening end portion (25a) of at least one of the relief openings (25) opens into the butt joint recess (33) until the butt joint surface (34) wears, and after the butt joint surface (34) wears, it opens into the inner circumferential surface (18) located radially inside. The packing ring (14) according to any one of claims 1 to 23.

25. At least one of the relief openings (25) opens directly into the inner circumferential surface (18). The packing ring (14) according to any one of claims 1 to 24.

26. A sealing device (1) for sealing a reciprocating and oscillating piston rod (2) provided with a casing (3) having a plurality of packing rings (7) arranged continuously in the axial direction inside. The sealing device (1) is provided with at least one packing ring (14) according to any one of claims 1 to 25.

27. A piston compressor comprising a compressor casing, at least one cylinder casing disposed in contact with the compressor casing and having a piston disposed therein and reciprocatingly oscillating therein, the piston being connected to a crankshaft disposed in the compressor casing via a piston rod, and at least one packing ring (14) disposed in the compressor casing for sealing the piston rod according to any one of claims 1 to 25.

28. The piston compressor according to claim 27, wherein a sealing device (1) having a casing (3) is provided in the compressor casing, a plurality of packing rings (7) arranged continuously in the axial direction are provided in the casing (3), and at least one packing ring (14) according to any one of claims 1 to 25 is provided.

29. A method for sealing a reciprocating oscillating piston rod of a piston compressor having at least one packing ring (14) with a cylindrical central opening (15) through which the piston rod extends, wherein the packing ring (14) has at least three ring segments (14a) each having a first segment end (SE1) and a second segment end (SE2) in the circumferential direction, and a first tangential contact surface (19a) of the first segment end (SE1) of one ring segment (14a) abuts against a second tangential contact surface (19b) of the second segment end (SE2) of the ring segment (14a) following the ring segment (14a) in the circumferential direction, thereby forming a radial seal, and a first axial contact surface (16) of the first segment end (SE1) of one ring segment (14a) facing the first axial ring end (RE1) of the packing ring (14) abuts against a second axial contact surface (17) of the second segment end (SE2) of the ring segment (14a) following the ring segment (14a) in the circumferential direction facing the second axial ring end (RE2) of the packing ring (14), thereby forming an axial seal, and the packing ring (14) is arranged in the piston compressor such that the first axial ring end (RE1) faces the crankcase of the piston compressor, in the method, At least one relief opening (25) extending from an inner circumferential surface (18) located radially inward to an outer circumferential surface (23) located radially outward provided in at least one of the ring segments (14a) and / or from the inner circumferential surface (18) located radially inward of the ring segment (14a) to the second axial ring end (RE2) of the ring segment (14a), wherein a first relief opening end (25a) opening to the inner circumferential surface (18) located radially inward of at least one of the relief openings (25) is formed such that at least one portion of at least one of the relief openings (25) in contact with the inner circumferential surface (18) located radially inward of the ring segment (14a) is inclined or curved toward the first axial ring end (RE1), thereby moving toward the first axial ring end (RE1) in response to radial wear of the ring segment (14a). Claim 30 On the inner circumferential surface (18) located radially inward of at least one of the ring segments (14a), at least one butting recess (33) having a radial butting recess depth (t ＡＬ ) of up to 3% of the ring height (RH) is provided, and the butting recess (33) extends in the axial direction of the ring segment (14a) from the second axial ring end (RE2) toward the first axial ring end (RE1) and extends in the radial direction of the ring segment (14a) from the inner circumferential surface (18) located radially inward of the ring segment (14a) toward the outer circumferential surface (23) located radially outward of the ring segment (14a), whereby a relatively smaller butting surface (34) is formed relative to the entire inner circumferential surface (18) located radially inward, so that the surface pressure based on the pressure of the packing ring (14) is increased at the start of the high-speed operation stage of the piston compressor, and the first relief opening end (25a) of at least one of the relief openings (25) opens to the butting recess (33) until the butting surface (34) wears, and after the butting surface (34) wears, it opens to the inner circumferential surface (18) located radially inward. The method according to claim 29.

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