WO2010084071A1

WO2010084071A1 - Piston having piston rings and support rings

Info

Publication number: WO2010084071A1
Application number: PCT/EP2010/050380
Authority: WO
Inventors: Christian Hold
Original assignee: Hoerbiger Kompressortechnik Holding Gmbh
Priority date: 2009-01-22
Filing date: 2010-01-14
Publication date: 2010-07-29
Also published as: AT507055B1; AT507055A1; CN102292577A

Abstract

In a conventional piston, sufficient backlash must be provided between the piston and cylinder in order to prevent the piston from running against the cylinder upon advanced wear of the support ring due to the resulting transverse movement of the piston. Large backlash can lead to an undesired extrusion of the piston ring in the gap between the piston and the cylinder, however. In order to solve these conflicting requirements, according to the invention a support ring (12) is arranged in a peripheral groove (20) provided on the piston body (15), wherein the axial width of the peripheral groove (20) is larger than the axial width of the support ring (12), a piston ring (11), which is supported axially on a support ring (12), is arranged between two neighboring support rings (12), wherein the distance between two neighboring support rings (12) is larger than the width of the piston ring (11) in between, and the support ring (12) is arranged radially spaced apart from the piston body (15) radially inside.

Description

Piston with piston rings and support rings

The subject invention relates to a piston having a piston body and a number of piston rings and support rings, which are arranged on the piston body.

In a conventionally constructed piston 1 (as shown in Fig. 1), e.g. For a piston compressor, the piston rings 2 are received in a rigid L-shaped disc 3, wherein the piston rings 2 are supported on the radial limbs of the L-shaped discs 3. The L-shaped disks 3 are here arranged and fixed directly on a piston rod 6. The piston 1 is guided in the cylinder 5 by a support ring 4, whereby a tarnishing of the piston 1 to the cylinder 5 is prevented. However, as the wear ring wear increases, the mobility of the piston 1 increases transversely to the stroke movement (indicated by a double arrow). In such a piston 1, it is therefore necessary that the play between piston 1 (or the L-shaped discs 3) and cylinder 5 is as large as possible in order to achieve a maximum Tragringverschleiß can. Due to this necessity, however, a large clearance necessarily arises between the piston 1 and the cylinder 5, whereby, however, the piston rings 2, which are usually made of a plastic, such as e.g. PTFE, are able to extrude into this gap between L-shaped discs 3 and cylinder 5. However, this play should therefore be as small as possible, so that the piston rings 2 (especially at high pressures) do not extrude into the gap. In order to meet these contradictory requirements with such a known piston 1, an additional backup ring can be arranged in the piston ring groove, but this increases the length of the piston.

The piston according to EP 541 482 A1 solves this problem by means of adjustable, slotted piston rings. The piston rings are arranged for this purpose in an L-shaped chamber ring and radially inwardly spaced from the boundary surface of the chamber ring, wherein the piston rings are clamped by adjacent chamber rings. In the resulting annular space of the working pressure is passed, whereby the piston rings are pressed against the tread of the cylinder. An end face of the piston ring, as well as the radial leg of the L-shaped chamber ring, chamfered, wherein in the starting position, the two parallel inclined surface are spaced from each other. With increasing wear of the piston rings, the two inclined surfaces approach visibly until they lie against each other, whereby the wear limit is reached. An axial mobility of the piston is prevented by the fact that the piston is guided by the piston rings in the cylinder. The play between piston and cylinder, and consequently the risk of extrusion, but can be reduced because it is prevented by the adjustable piston rings that the piston starts against the cylinder. But such a piston is due to the inclined surfaces and the necessary supply of the gas pressure in the annulus manufacturing technology consuming. In addition, due to the necessary axial clamping of the piston rings by adjacent chamber rings a Doppelpassungsproblem, which also leads to manufacturing difficulties. In addition, this can lead to the piston rings being pressed against the cylinder with different pressure forces, which in turn can lead to undesired different wear rates of the piston rings.

It is therefore an object of the subject invention to provide a piston that solves the two contradictory requirements, great play between the piston and cylinder on the one hand and low extrusion of the piston ring on the other hand and is simple and compact.

This object is achieved in that a support ring is arranged in a provided on the piston body circumferential groove, wherein the axial width of the circumferential groove is greater than the axial width of the support ring that between two adjacent support rings each have a piston ring is arranged, the axially a support ring is supported, wherein the distance between two adjacent support rings is greater than the width of the intermediate piston ring and that the support ring radially inwardly radially spaced from the piston body is arranged. By this arrangement it is achieved that a support ring is not moved during a movement of the piston transversely to the lifting movement with the piston, but only moves the piston body relative to the support ring. A support ring is therefore not pressed by the piston movement against the running surface of the cylinder, whereby the radial clearance between the support ring and tread can be significantly reduced. Furthermore, this results in an enormous space savings in the necessary length of the piston, since the support ring combines the function of a support and the function of the conventional piston ring groove in itself. In a conventional piston built an L-shaped chamber disc and an additional backup ring in the Kolbenringnut would be necessary, whereby a wider piston ring groove would have to be performed.

In a particularly preferred embodiment, a number of chamber rings is arranged, wherein in a chamber ring, a circumferential groove is provided, in which a support ring is arranged and the support ring radially inwardly radially spaced from the bottom of the circumferential groove is arranged. This can be realized very easily a built piston, since the chamber rings can be easily pushed with the support rings and piston rings on a piston part.

To guide the piston in the cylinder at least one support ring is advantageously provided on the piston body. A particularly advantageous and simple structural arrangement results when the piston body is arranged on a piston center part, wherein at one axial end of the piston a piston end part can be provided which fixes the chamber rings of the piston body on the piston center part.

In order not to have to seal the dynamic pressure component to the piston rings, a first uncut ring may be disposed on the compression chamber side axial end of the piston on the piston body and a gap may be provided between this first uncut ring and a next ring, the gap with the space in front of the first uncut ring is connected. The first uncut ring serves to seal the dynamic working pressure component.

In order not to interfere with the axial mobility of the piston through the first uncut ring, the uncut ring may be disposed in a circumferential groove bounded at one axial end by a support ring, the width of the circumferential groove being greater than the width of the uncut ring , The support ring may be arranged in a circumferential groove of the piston body, wherein the width of the circumferential groove is greater than the width of the respective support ring. Thus, an axial clamping of the uncut rings or the support rings is prevented. Furthermore, the uncut ring and the support ring may be radially inwardly spaced from the bottom of the circumferential groove to allow relative movement of the piston body with respect to the rings.

The subject invention is described below with reference to the schematic, exemplary, non-limiting and advantageous embodiments facing Figures 1 to 7. It shows

1 shows a piston according to the prior art, FIG. 2 shows a piston according to the invention, FIG. 3 shows a detail of a piston according to the invention,

Fig. 4 shows a further embodiment of a piston according to the invention and Fig. 5 to 7 embodiments of the rings used in the piston.

An advantageous embodiment of a piston according to the invention will be described below with reference to Figures 2 and 3. The piston 1 consists of a piston body 15, which is formed by a number of axially adjacent chamber rings 10. The piston body 15 and the chamber rings 10 are here arranged on a piston center part 14 and are fixed thereon with a piston end part 13. For this purpose, the piston end part 13 can be screwed onto the piston middle part 14, for example. However, a chamber ring can also be designed as part of the piston end part 13 or piston center part 14. At the piston end part 13 and the piston center part 14 is here in each case a support ring 4 is arranged to guide the piston 1 in the cylinder 5. The stroke of the piston 1 and the length of the piston 1 set the axial end distance between the piston 1 and cylinder end. The axial end of the piston 1 may be tuned for a valve to minimize the dead space.

Depending on the design of the machine in which the piston 1 is used, the free axial end of the piston end part 13 can be connected to either a connecting rod or a piston rod 17 (as indicated in FIG. 2). In the case of a piston rod 17, the piston 1 need not be firmly connected to the piston rod 17, but may rest only loosely on the piston rod 17, since the pressure acting in the compression chamber 16 ensures that the piston 1 remains in contact with the piston rod 17 and is moved with it.

On the piston body 15, a number of piston rings 11 is arranged. The piston rings 1 1 can basically be designed arbitrarily. Preferably, adjusting piston rings 11 are used which, as wear, e.g. be pressed by the acting pressure, always radially outward against the cylinder 5. One possible embodiment of such piston rings 11 may be e.g. AT 505 549 B are taken.

In a chamber ring 10, a circumferential groove 20 is provided, in which a support ring 12 is arranged. In the example shown, the circumferential groove 20 is disposed at one axial end of the chamber ring 10 and is bounded axially by the adjacent chamber ring 10. In such an embodiment, an uncut support ring 12 can be easily assembled during assembly of the piston 1. In the case of cut or slotted support rings, the circumferential groove 20 may also be spaced from the axial ends of the chamber ring 10. In such an embodiment, however, can be dispensed with the chamber rings 10, since the circumferential grooves 20 then directly into the piston body 15, e.g. in the Kolbenmitteilteil 14, may be incorporated. The width of the circumferential groove 20 is slightly larger than the width of the support ring 12, so that the support ring 12 is arranged in the circumferential groove 20 with an axial clearance and is not clamped axially and especially the piston body 15 remains freely movable relative to the support ring 12 , The free relative mobility of the piston body 15 counteract only due to the upcoming pressures resulting frictional forces between the support ring 12 and circumferential groove 20. During a movement of the piston 1 transversely to the stroke direction thus only the piston body 15 is moved, the support rings 12 are not moved thereby. Thus, the support rings 12 are at worst with their own very low weight on the cylinder wall. However, no forces are transmitted from the piston body 15 to the support rings 12.

On the remaining part of the chamber ring 10, a piston ring 1 1 is arranged in each case. In order for a respective support ring 12 is disposed between two adjacent piston rings 11,

-A- wherein the width of a piston ring 11 is slightly smaller than the resulting distance between two support rings 12 so that the piston ring 11 between the two adjacent support rings 12 is not clamped and the radial mobility of the piston body 15 is not disturbed. In operation, a piston ring 11 will abut axially by the acting pressures or by the stroke of the piston on a support ring 12 and the adjacent piston ring 11 axially spaced from this support ring 12 and axially abut the next support ring 12, etc. The piston rings 11 are supported axially only on the support rings 12 from which are in turn axially supported exclusively in the circumferential grooves 20

The piston 1 shown in Fig. 2 is a single-acting piston. For a double-acting piston could be provided for all piston rings 11 on both sides in each case a support ring 12, so here also between Kolbenendteil 13 and adjacent piston ring 1 1, so that all piston rings 1 1 in both compression strokes to avoid extrusion to a Supporting ring 12 can support.

During a movement of the piston 1 transversely to the lifting movement, the piston body 15 can therefore move through the radial clearance X between the support ring 12 and the base of the circumferential groove 20 in the radial direction relative to the support ring 12, without the support ring 12 is moved. A support ring 12 can therefore be installed with very little play Y between the cylinder 5 and the outer peripheral surface of the support ring 12, since there is no danger that the support ring 12 is pressed by such a transverse movement to the cylinder 5 with increased force. With an inventive arrangement, the game Y can be reduced to 0.1 mm without problems. A natural limit of the game Y represents the thermal expansion of the support ring 12, which of course must not cause the support ring 12 is clamped radially in the cylinder 5. Due to the possible slight play Y, however, extrusion of the piston ring 11 into the gap between the support ring 12 and the cylinder 5 can also be practically prevented. The piston rings 11 may also be arranged radially spaced from the piston body 15, e.g. when using piston rings according to the AT 505 549 B, so that between the piston rings 11 and the piston body 15 also creates a radial clearance, which is larger with increasing piston ring wear. In the resulting annular space here is the acting pressure, which presses the piston ring 1 1 outwardly against the cylinder 5. A possible transverse movement of the piston body 15 does not affect the piston rings 1 1 therefore.

In a further advantageous embodiment of a piston 1 according to the invention, as shown in Fig. 4, an uncut ring 21 is arranged on the compression chamber side in front of the piston rings 1 1, to seal the dynamic pressure component of the working pressure. Since this should take place in a defined manner, a radial groove 26 can be incorporated into the associated support ring 24 and a gap 25 can be provided behind it, so that the dynamic Working pressure does not blow through to the rear. Through the radial groove 26, the remaining working pressure is passed into the intermediate space 25. Axially afterwards can still be provided a support ring 4, another uncut ring 27 and the piston rings 1 1 for sealing the static pressure component. However, such a ring configuration can also be used with any other piston.

The first uncut ring 21 can be arranged in a circumferential groove 28 of a first chamber ring 23, which abuts axially on a second chamber ring 22, in which the second uncut ring 27 is arranged in a further circumferential groove 28. The second uncut ring 27 can also be omitted. Both uncut rings 21, 27 are in turn spaced radially from the base of the associated circumferential groove 28 and the width of the circumferential groove 28 is each wider than the width of the respective uncut ring 21, 27 to allow unimpeded transverse movement of the piston body 15. Both uncut rings 21, 27 are axially on a support ring 24, 12, which in turn are each arranged in a circumferential groove 20 in the chamber rings 22, 23 and are again arranged radially spaced from the bottom of the circumferential groove. The support rings 24, 12 are in turn incorporated in their circumferential grooves 20 with an axial clearance, so that they are not clamped axially. The same applies to the uncut rings 21, 27. In the second chamber ring 22 at the axial end facing the first chamber ring 23 is a recess, e.g. in the form of a twist, provided, which forms the gap 25. A support ring 4 is arranged here in front of the second uncut ring 27 in the second chamber ring 22. However, the support ring 4 can also be arranged in the first chamber ring 23. The remaining configuration of the piston 1 corresponds to the piston 1 described with reference to FIGS. 2 and 3.

Possible embodiments of rings used are shown in Figures 5 to 7. In the uncut ring 21, 27 pressure equalization holes 30 may be provided. The uncut ring 21, 27 may advantageously be made of PRFE, since PTFE rings can adjust some wear. Furthermore, a radial groove 31 may be provided on the support ring 24 of the first uncut ring 21 at an axial end face in order to guide the working pressure in both strokes safely into the intermediate space 25. During the compression stroke, this groove 31 can flow through no working medium, because the uncut ring 21 seals at the other end face. This groove 31 serves to allow the suction stroke, the compressed working fluid in the chamber 25 back into the compression chamber to not press the uncut ring 21 against the cylinder 5 during the suction stroke. The uncut ring 21 is therefore not pressure-loaded. This arrangement can also be adjusted so that the second uncut ring 27 also seals a portion of the dynamic pressure. It is therefore not absolutely essential that the first unscheduled tene ring 21 seals the full dynamic pressure. The second uncut ring 27 can also seal the static pressure, since no radial groove is milled into the following support ring.

A shown in Fig. 6 support ring 4 may be executed cut and may have on the radially outer peripheral surface axially continuous grooves to direct the pressure acting on the piston rings 11. The embodiment of a piston ring 11 illustrated in FIG. 7 corresponds to the description of AT 505 549 B. However, any other embodiment of a piston ring 11 is also conceivable.

Claims

claims

1. Piston having a piston body (15) and a number of piston rings (11) and support rings (12) which are arranged on the piston body (15), characterized in that a support ring (12) provided in a on the piston body (15) Circumferential groove (20) is arranged, wherein the axial width of the circumferential groove (20) is greater than the axial width of the support ring (12), that between two adjacent support rings (12) each have a piston ring (1 1) is arranged axially is supported on a support ring (12), wherein the distance between two adjacent support rings (12) is greater than the width of the piston ring lying therebetween (11) and that the support ring (12) radially inwardly radially spaced from the piston body (15) is.

2. Piston according to claim 1, characterized in that on the piston body (15) a number of chamber rings (10) is arranged and in a chamber ring (10) has a circumferential groove (20) is provided, in which a support ring (12) is arranged and the support ring (12) is radially inwardly radially spaced from the bottom of the circumferential groove (20).

3. Piston according to claim 1 or 2, characterized in that on the piston body (15) at least one support ring (4) is provided.

4. Piston according to one of claims 1 to 3, characterized in that the piston body (15) is arranged on a piston center part (14).

5. Piston according to claim 4, characterized in that at one axial end of the piston (1) a Kolbenendteil (13) is provided which fixes the chamber rings (10) of the piston body (15) on the piston center part (14).

6. Piston according to one of claims 1 to 5, characterized in that at the compression space side axial end of the piston (1) on the piston body (15) a first uncut cut ring (21) is arranged and between this first uncut ring (21 ) and a next ring of the piston (1), a gap (25) is provided, wherein the intermediate space (25) is connected to the space in front of the first uncut ring (21).

7. Piston according to claim 6, characterized in that the uncut ring (21, 27) in a circumferential groove (28) of the piston body (15) is arranged, which at an axia- len end of a support ring (24, 12) is limited wherein the width of the circumferential groove (28) is greater than the width of the respective uncut ring (21, 27).

8. Piston according to claim 7, characterized in that the uncut ring (21, 27) radially inwardly radially spaced from the bottom of the circumferential groove (28) is arranged.

9. Piston according to one of claims 6 to 8, characterized in that the support ring (24, 12) in a circumferential groove (20) of the piston body (15) is arranged, wherein the width of the circumferential groove (20) is greater than the width of the respective support ring (24, 12)

10. Piston according to claim 9, characterized in that the support ring (12) radially inwardly radially spaced from the bottom of the circumferential groove (20) is arranged.

1 piston according to one of claims 6 to 10, characterized in that the next ring is a support ring (4), a second uncut ring (27) or a piston ring (11).