DE4032609C1 - Vehicle shock-absorber piston and ring - uses broad plastics ring engaging grooves on support on piston - Google Patents

Abstract

The piston and ring is fitted in a damper and joined to a piston rod so as to divide the cylinder into two spaces. The plastics piston ring is on a support and extends axially over several times the thickness of the ring well. The ring (3) should be permanently fixed to its support (8) which in turn is positively joined to the piston (2) and is sealed relative a piston step on at least one endface. USE/ADVANTAGE - Motor vehicles, shock absorbers etc. Ring fixed to support can be machined separate from piston prior to final fitting using standard parts.

Description

The invention relates to a piston with a Piston ring for a hydraulic or pneumatic Unit, especially for a vibration damper, the one provided with a damping device Piston is connected to a piston rod and one Cylinder divided into two work spaces and that of Plastic existing piston ring on a supporting body is arranged and has an axial extension that is a multiple of the ring wall thickness.

Pistons for vibration dampers are known (e.g. DE-PS 08 68 393, Fig. 3), in which the one Damping device provided pistons a piston ring having. The piston ring is on a support body, arranged with radial play to the piston. However, to Lateral forces with as little play as possible through the piston rod intercepting is a radial game between the Support body and the piston undesirable. Such a thing Game also leads to leaks and knock sound.

Furthermore, aggregates are known (e.g. DE-GM 73 30 737), in which the piston has a piston ring groove is provided, the axial extension of the piston  ring corresponds. The piston is in this groove wrapped a foil. The increased tolerance is disadvantageous construction, because the tolerances of the groove, the cylinder total inside diameter and film thickness.

In addition, attachments of a piston ring are on a piston known (e.g. DE-OS 30 08 708), in which the piston ring ge at least one radially inward has directed projection and the piston for engagement this projection with a corresponding recess is provided. The assembly of the piston ring on the Piston is done in such a way that the previously put the piston ring in the form of a snap connection the forehead with a smaller inner diameter engage the sides of the piston. Here too is an ent speaking tolerance build-up between the individual buildings share to consider.

The object of the invention is a piston for one Vibration damper to create, in which the manufacture the piston ring can be done independently of the piston, so that on the one hand the assembly of both parts only after a mechanical processing and subsequent con trolls and that on the other hand the use of Unit and / or standard parts is possible.

To solve this problem, the invention provides see that the piston ring with the support body and is inextricably linked, the support body form is connected to the piston and at least at least an end face opposite a shoulder of the piston is sealed.

The advantage here is that the piston is mechanical can be finished, so that according to checking the perfect components with the piston ring can be provided. Regardless of that onto a support body by means of heat shrinking or a structure connection a plastic sliding film apply and calibrate to the closest tolerance. Here  through tightest tolerances between piston ring and Cylinder tube can be achieved so that a piston ring Similar sealing occurs, whereby by mounting the Support body on the actual piston body components can be used according to a modular principle.

According to another essential characteristic is between Piston and piston rod pre-fixed a fixed support head see. The support body can be advantageous profiled from its side facing the piston ring form.

In a further embodiment, at least one end protrudes area of the piston ring the piston so axially that a sealing lip is formed. By appropriate The internal pressure of the damping means is radial Pressure of the piston ring on the cylinder wall.

According to another essential feature, that the inner surface of the end portion of the piston ring runs beveled and through an axial clamping element is applied. By chamfering the endbe rich and introducing an axial clamping element the sloping surface is created according to the principle of inclined plane a radially outward pressure, so that a corresponding surface pressure of the piston ring can be achieved compared to the inner cylinder tube.

Preferred embodiments are according to the invention shown in the drawings.

It shows:

Fig. 1 shows a vibration damper with a damping piston in section,

FIG. 2 to FIG. 4, three different variants of a piston support body and aufgeschrumpftem piston ring in cross-section,

Fig. 5 to Fig. 6 held a piston with a piston ring by a positive connection.

The vibration damper 1 shown in Fig. 1 has a piston 2, which is fixed to the piston rod 4 and the cylinder 6 into an upper working chamber 5 and a lower working chamber 7 shares. The piston 2 is provided with a piston ring 3 for perfect sealing and guidance relative to the cylinder 6 .

In FIG. 2, the cylinder 6 and the piston 2 is shown in section a detail, wherein the cup-shaped support body is fixed axially between the piston 2 and the piston rod 4 and 8 is provided with the piston ring 3. The piston ring 3 is shrunk on the support body 8 .

In FIGS. 3 and 4 as a supporting body 8 zylin drischer ring is provided, which is visible to the piston ring 3 is fixed ver and the corresponding axially retaining elements 16. In these embodiments, too, the piston ring is applied to the support body 8 by means of heat shrinking, so that it is a piston base body which is provided with a corresponding piston ring 3 after finished mechanical processing.

FIGS. 5 and 6 show a piston ring 3, which in each case relative to the end face 17 of the piston is fixed by the bent end 10 of the piston ring 3 via a fixing member 9. The angled end 10 of the piston ring 3 is axially clamped by the fastening element 9 . This type of fastening can therefore only be carried out after mechanical machining of the piston.

Reference symbol list

1 - vibration damper
2 - piston
3 - piston ring
4 - piston rod
5 - upper work area
6 - cylinder
7 - lower work area
8 - support body
9 - fastener
10 - angled end of the piston ring
11 -ring approach
12 - groove
13 - beveled surface
14 - sealing lip
16 - holding element
17 - face

Claims (5)

1. Piston with a piston ring for a hydraulic or pneumatic unit, in particular for a vibration damper, the piston provided with a damping device being connected to a piston rod and dividing a cylinder into two working spaces and that the plastic piston ring being on a supporting body is arranged and has an axial extent which is a multiple of the ring wall thickness, characterized in that the piston ring ( 3 ) with the support body ( 8 ) is firmly and non-detachably, the support body ( 8 ) positively connected to the piston ( 2 ) and is sealed on at least one end face against a set of pistons ( 2 ). 2. Piston according to claim 1, characterized in that a support head is provided as the supporting body ( 8 ) between the piston ( 2 ) and piston rod ( 4 ). 3. Piston according to claim 1, characterized in that the supporting body ( 8 ) is profiled on its side facing the piston ring ( 3 ). 4. Piston according to claim 1, characterized in that at least one end region of the piston ring ( 3 ) projects axially beyond the piston ( 2 ) such that a sealing lip ( 14 ) is formed. 5. Piston according to claim 4, characterized in that the inner surface of the end region of the piston ring ( 3 ) is chamfered and is acted upon by an axial clamping element.