DE9017933U1 - Piston with one piston ring - Google Patents

Description

PPL 5&bgr;4 GM -4- 21.05.1991

Piston with one piston ring

The invention relates to a piston with a piston ring for a hydraulic or pneumatic unit, in particular for a vibration damper, whereby the piston provided with a damping device is on a piston rod and divides a cylinder into two working spaces and the piston ring made of plastic has an axial extension which is several times the ring wall thickness.

In such units it is known (e.g. DE-GM 73 3O 737) to provide the piston with a piston ring groove, which corresponds to the axial extent of the piston ring. The piston is wrapped in this groove with a film. The disadvantage is the increased tolerance build-up, since the tolerances of the groove, the cylinder inner diameter and the film thickness add up.

In addition, fastenings of a piston ring on a piston are known (e.g. DE-OS 3O �Ogr;βgr; 7�Ogr;βgr;>), in which the piston ring has at least one radially inward-facing projection and the piston is provided with a corresponding recess for engagement with this projection. The piston ring is mounted on the piston in such a way that the previously finished

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PPL 584 GM -5- 21.O5.1991

The piston ring is snapped into the piston end faces with a smaller inner diameter in the form of a snap connection. Here, too, a corresponding tolerance build-up between the individual components must be taken into account.

The object of the invention is to create a piston for a vibration damper in which the piston ring can be manufactured independently of the piston, so that on the one hand the assembly of both parts only takes place after mechanical processing and subsequent inspection and that on the other hand the use of standard and/or unitary parts is possible.

To solve this problem, the invention provides that the piston ring is connected to a support body, wherein the support body is positively connected to the piston.

The advantage here is that the piston can be mechanically finished so that after appropriate inspection the flawless components can be fitted with the piston ring. Independently of this, a plastic sliding film can be applied to a support body by means of heat shrinking or a structural connection and calibrated to the tightest tolerance. This makes it possible to achieve the tightest tolerances between the piston ring and the cylinder tube, so that a seal similar to a piston ring is created, whereby by mounting the support body on the actual piston body, components can be used according to a modular principle.

According to another important feature, a cylindrical ring or a support pot fixed between the piston and the piston rod is provided as the support body. The support body can advantageously be profiled on the side facing the piston ring.

Alternatively, the task can be solved according to a second embodiment by the piston ring being

PPL 5&bgr;4 GM -6- 21.05.1991

a fastening element is connected to the piston in a form-fitting and/or friction-fitting manner.

The advantage of this embodiment is that the piston can be completely machined mechanically, so that after subsequent inspection the piston ring can be fitted and connected to the piston body in a form-fitting or force-fitting manner.

A favorable embodiment provides that a cylindrical ring is provided as a fastening element, which serves to fix an angled end of the piston ring relative to an annular projection of the piston.

A further force-locking connection can be achieved by providing a disk-shaped element as a fastening element, which fixes an angled end of the piston ring against a front side of the piston.

In an embodiment of the invention, it is provided that the piston ring has a groove on its inner surface running around the circumference, which engages in a corresponding projection of the piston.

The advantage here is that the piston ring can be designed as a rigid component, e.g. made of plastic, and the circumferential groove is designed as a snap connection together with a cylindrical projection.

In a further development of the two alternative solutions, at least one end area of the piston ring projects axially beyond the piston in such a way that a sealing lip is formed. The corresponding internal pressure of the damping means causes the piston ring to be pressed radially against the cylinder wall.

According to a further essential feature, it is provided that the inner surface of the end region of the piston ring

PPL 5&bgr;4 GM -7- 21-05.1991

bevelled and is loaded by an axial clamping element. By bevelling the end area and inserting an axial clamping element onto the bevelled surface, a radially outward-acting pressure is created according to the principle of the inclined plane, so that a corresponding surface pressure of the piston ring against the cylinder inner tube can be achieved.

Preferred embodiments of the invention are shown in the drawings.

It shows:

Figure 1 shows a vibration damper with a damping piston in section

Figure 2 to Figure 4 three different variants of a piston with support body and shrunk-on piston ring in section

Figure 5 to Figure 6 a piston with a piston ring held by a force-locking connection

Figure 7 shows another frictional connection of a piston ring to the piston

Figure 8 to Figure 9 a piston ring which is connected to the piston via a snap connection

Figure 10 to Figure 11 a piston ring with corresponding sealing lip

Figure 12 to Figure 13 Piston rings with bevelled end area.

The vibration damper 1 shown in Figure 1 has a piston 2 which is attached to the piston rod 4 and divides the cylinder 6 into an upper working chamber 5 and a lower working chamber 7. The piston 2 is

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PPL 5a4 GM -β- 21.05.1991

perfect sealing and guidance relative to the cylinder 6 with a piston ring 3.

In Figure 2, the cylinder 6 and the piston 2 are shown in section as a detail, with the tap-shaped support body β being axially fixed between the piston 2 and the piston rod 4 and being provided with the piston ring 3. The piston ring 3 is shrunk onto the support body 8.

In Figures 3 and 4, a cylindrical ring is provided as the support body 8, which is provided with the piston ring 3 and which is axially fixed accordingly via holding elements 16. In these embodiments too, the piston ring is applied to the support body 8 by means of a heat shrink, so that this is a piston base body which is provided with a corresponding piston ring 3 after mechanical processing has been completed.

Figures 5 and 6 show a piston ring 3, which is fixed via a fastening element 9 opposite the front face 17 of the piston by the angled end 10 of the piston ring 3. The angled end 10 of the piston ring 3 is clamped axially by the fastening element 9. This type of fastening can therefore only be carried out after the piston has been mechanically processed.

In Figure 7, a disk-shaped fastening element 9 is arranged in front of the piston 2, which fixes the piston ring 3 with its angled end IO in a force-fitting manner relative to the front side 17 of the piston 2.

Figures 8 and 9 each refer to a piston 2, the piston ring 3 of which is provided with a groove 12, whereby an annular projection 11 together with the groove 12 forms a snap connection. The annular projection 11 can be part of the fastening element 9.

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PPL 584 GM -9- 21.05.1991

At the same time, an axial and/or radial preload can be applied to the piston ring 3.

In Figures 10 and 11, the piston ring 3 is held relative to the piston 2 by the annular projection 11 and the groove 12 in the form of a snap connection, with the end of the piston ring 3 projecting beyond the piston 2 in such a way that a sealing lip 14 is formed. When the beveled surface 13 is subjected to damping means during operation, a radially acting force can be achieved on the sealing lip 14 for perfect sealing against the cylinder 6.

Figures 12 and 13 again show a piston 2 with a piston ring 3, the beveled surface 13 of which is axially loaded by the fastening element 9 in such a way that a radially directed force is generated via the beveled surface 13 and the fastening element 9 according to the principle of the inclined plane. This radially directed force in turn serves to perfectly seal the piston ring 3 against the cylinder 6.

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PPL 584 GM -&Igr;&Ogr;- 21.&Ogr;5.1991

Reference number

1 - Vibration damper

2 - Piston

3 - Piston ring

4 - Piston rod

5 - upper working area

6 - Cylinder

7 - lower working space &bgr; - supporting body

9 - Fastening element

10 - angled end of the piston ring

11 - ring-shaped attachment

12 - Groove

13 - bevelled surface

14 - Sealing lip

15 - Clamping element

16 - Holding element

17 - Front side

17 Q

Claims (10)

BÖGE Aktiengesellschaft 21 May 1991 Bogestraße 5O PPL 5&THgr;4 GM 520a Eitorf St/cr Protection claims 1. Piston with a piston ring for a hydraulic or pneumatic unit, in particular for a vibration damper, whereby the piston provided with a damping device is on a piston rod and divides a cylinder into two working spaces and the piston ring made of plastic has an axial extension which is a multiple of the ring wall thickness, characterized in that that the piston ring <3> is connected to a support body <8>, whereby the support body <8> is positively connected to the piston <2). 2. Piston according to claim 1,
characterized, that a cylindrical ring is provided as the supporting body <8>. 3. Piston according to claim 1,
characterized, that a support pot fixed between the piston <2> and the piston rod <4> is provided as the supporting body <8>. 90 1? 933. PPL 5&bgr;4 GM -2- 21.05.1991 4. Piston according to claim 1,
characterized., that the support body <8> is profiled on its side facing the piston ring (3). 5. Piston with a piston ring for a hydraulic or pneumatic unit, in particular for a vibration damper, whereby the piston provided with a damping device is on a piston rod and divides a cylinder into two working spaces and the piston ring made of plastic has an axial extension which is several times the ring wall thickness, characterized in that that the piston ring <3> is positively and/or non-positively connected to the piston <2> via a fastening element <9). 6. Piston according to claim 5,
characterized, that a cylindrical ring is provided as a fastening element <9>, which serves to fix an angled end <1O> of the piston ring <3> relative to an annular projection <11> of the piston <2>. 7. Piston according to claim 6,
characterized, that a disk-shaped element is provided as a fastening element <9>, which fixes an angled end (1O> of the piston ring <3) opposite a front side of the piston <2>. 8. Piston according to claim 6,
characterized, that the piston ring <3) has a groove <12> running around the circumference on its inner surface, which engages in a corresponding projection (13> of the piston <2>. 1?933. PPL 584 GM -3- 21.O5.1991 9. Piston according to claim 1 or claim 6, characterized in that at least one end region of the piston ring (3) projects axially beyond the piston <2> in such a way that a sealing lip <14> is formed. 10. Piston according to claim 9,
characterized, that the inner surface of the end region of the piston ring <3> is bevelled and is acted upon by an axial clamping element (15). in 17 &pgr;