DE3812574A1 - Piston with a piston ring - Google Patents

Abstract

Piston with a piston ring for a vibration damper, the piston, which is provided with a damping device, being attached to a piston rod and dividing the cylinder into two working spaces, the piston having a raised outer surface in the central region and being designed with undercut-free end regions. The piston ring, which is composed of plastic, is shrunk onto the undercut-free piston by means of a heat treatment and, in the process, simultaneously calibrated in its outside diameter to the final size.

Description

The invention relates to a piston with a Piston ring for a hydraulic, hydropneumatic or pneumatic unit, especially for a pig tion damper, the one with a damping device provided piston is attached to a piston rod and divided a cylinder into two work spaces, and that the piston in the middle area on its outer surface is raised and undercut-free and that the plastic piston ring an axial Er stretching that is a multiple of the ring wall thickness is.

It is known for such units (e.g. DE-GM 73 30 737) to ver the piston with a piston ring groove see that the axial extension of the piston ring ent speaks. The piston with a film is in this groove flipped. The increased tolerance build-up is disadvantageous because the tolerances of the groove, the inside of the cylinder add knife and film thickness. In addition, one appropriate mechanical processing of the piston not agile.

In addition, attachments of a piston ring are on a piston known (DE-OS 30 08 708), in which the Piston ring at least one radially inward Has projection and the piston to engage this Provide projection with a corresponding recess  is. The piston ring is mounted on the piston in such a way that the previously completed piston ring in the form of a snap connection in the smaller one End face of the piston snaps. Here too is a corresponding tolerance build-up between the individual components.

The object of the invention is a piston for one Vibration damper with a simple and cost cheap piston ring to provide for the takeover of Management and sealing tasks not only slippery, but also has a high degree of dimensional accuracy, and moreover avoids mechanical machining of the piston.

To solve this problem, the invention provides see that the piston ring by means of a heat treatment shrunk onto the piston and at the same time the Outside diameter is calibrated to the final dimension.

The advantage here is that the piston than conventional Sintering piston is provided on the in a warm up shrink-wrapped a Teflon slide film and is calibrated to the closest tolerance at the same time. By the finished sinterable flask becomes a achieved significant cost savings because the mechanical Machining the piston ring or the foil groove or Contouring can be omitted. By achieving narrowest gaps between piston and cylinder tube there is thus a piston ring-like seal, whereby simple assembly of the finished piston is possible.

According to another essential feature, that a fixation over the end portions of the piston ring the piston ring in the area of the raised outer surface undercut-free surface of the piston ring. The raised outer surface and / or are advantageous the undercut-free surface of the piston is cylindrical educated. It is advantageous in this training that the outer jacket of the piston without a backstitch is adjustable and the piston ring prevents loosening axial forces on the end edges of the cylindrical he anchored the outer surface of the piston.  

In an embodiment of the invention it is provided that at least one end portion of the piston ring such The piston protrudes axially that a sealing lip is formed. Here, the warm process is advantageous shrinking an additional protrusion of the piston ringes used and as an additional sealing lip for Ab seal of the piston against the cylinder.

According to another cheap embodiment between the end portion of the piston ring and the piston a recess open to the work space is formed. This recess can be used for printing dependent pressure of the piston ring on the cylinder take advantage of the inner wall.

Preferred embodiments are in the drawing shown schematically.

It shows:

Fig. 1 cut a section of a vibration damper GE Fig. 2 shows a piston with shrunk piston ring in section . Fig. 3 shows a piston in section as a single part.

The vibration damper 1 shown in Fig. 1 has a piston 2, which is attached to a piston rod 4 and the cylinder 5 divides 8 and a lower working chamber 7 into an upper working chamber. The piston 2 is provided with a piston ring 3 for proper sealing and guidance with respect to the cylinder 5 .

In Fig. 2, the piston 2 is shown ge cut as a single part, the outer surface of the piston 2 having a raised outer surface 10 and behind cut-free surfaces 11 in the end regions 8 and 9 of the piston 2 . The piston 2 is provided as a conventional sintered piston, but the outer jacket has undercut-free surfaces 11 . On this outer surface, the piston ring 3 is shrunk in the form of a Teflon sliding film in a heat shrink fit and simultaneously calibrated to the closest tolerance. The piston ring 3 is anchored against loosening under axial forces on the transition areas between the raised outer surface 10 and the undercut-free surface 11 .

During the application of the piston ring 3 , an additional sealing lip 12 can be produced by an additional protrusion of the Teflon film. A pressure-dependent pressing of the piston ring 3 against the inner wall of the cylinder 5 is possible through a recess 13 that is open toward the working space 7 .

A piston 2 is shown in FIG. 3, the outer casing consisting of a raised outer surface 10 and undercut-free surfaces 11 in the end regions 8 and 9 .

Reference symbol list

1 = vibration damper
2 = piston
3 = piston ring
4 = piston rod
5 = cylinder
6 = work space
7 = work space
8 = end area
9 = end area
10 = raised outer surface
11 = undercut-free area
12 = sealing lip
13 = recess

Claims (5)

1. Piston with a piston ring for a hydraulic, hydropneumatic or pneumatic unit, in particular for a vibration damper, the piston provided with a damping device being fastened to a piston rod and dividing a cylinder into two working spaces and that the piston in the central area on its outer surface is raised and free of undercuts and that the plastic piston ring has an axial extension that is a multiple of the ring wall thickness, characterized in that the piston ring ( 3 ) is shrunk onto the piston ( 2 ) by means of heat treatment and at the same time the Outside diameter is calibrated to the final dimension. That takes place 2. Piston according to claim 1, characterized in that on the end portions (8, 9) of the piston ring (3) a fixing of the piston ring (3) in the region of the raised outer surface (10) to the undercut-free surface of the piston ring (3). 3. Piston according to claim 1, characterized in that the raised outer surface ( 10 ) and / or the rear cut-free surface ( 11 ) of the piston ( 2 ) are cylindrical. 4. Piston according to claim 1, characterized in that at least one end region ( 8 , 9 ) of the piston ring ( 3 ) axially projects beyond the piston ( 2 ) such that a sealing lip ( 12 ) is formed. 5. Piston according to claim 4, characterized in that between the end region ( 9 ) of the piston ring ( 3 ) and the piston ( 2 ) an open towards the working space recess ( 13 ) is formed.