Patent Application
20050127611
1. Field of the Invention
The invention pertains to a piston ring, especially for a piston in a vibration damper, including a lateral wall with a lateral surface facing the piston, a pair of retaining segments extending radially inward from the lateral surface and having respective retaining surfaces which rest against the top and bottom of the piston, and a pair of sealing lips which extend radially outward from the lateral wall for engaging a cylindrical wall of the damper.
2. Description of the Related Art
A piston ring which covers a lateral surface of a flat piston is known from US 2003/0062687. In the axial direction, the piston ring is secured by support elements with retaining surfaces, which rest on the top and bottom surfaces of the piston. Within a groove in the piston ring, a tensioning ring is provided, which is intended to pretension the piston ring radially outward against the wall of the cylinder of the vibration damper. The groove is formed by the sidewalls of webs, which extend radially inward. In this design, the problem is that the locking ring can slide out of the groove during the axial movements of the piston, which can be very rapid at times. Although it is advisable for the groove to be as deep as possible, it is difficult if not impossible to remove a piston ring with a very deep groove from the mold after the injection-molding process.
FIG. 3 of U.S. Pat. No. 5,615,756 also shows a piston ring for a flat piston, where, starting from the support segments, a comparatively massive sealing lip extends toward the inside wall. Relatively high pretensioning forces against the cylinder wall can be achieved with a massive sealing lip without the need for a tensioning ring. The presence of such a large amount of material, however, leads to distortion when the piston ring cools down after injection molding, so that the shape of the sealing lip does not always have the desired precision.
The task of the present invention is to obtain a piston seal with a large amount of pretension against the cylinder wall.
Accomplished according to the invention in that the sealing lip is designed with a reinforcing profile radially on the inside, the web of which is perpendicular to the support segments.
The advantage of the reinforcing profile is that the wall thickness of the web does not represent a large concentration of material. In addition, it is easy to remove perpendicular webs from the mold.
Thus, for example, the sealing lip and the reinforcing profile can form a U-shaped cross section.
In another advantageous embodiment, the reinforcing profile is formed by a ring-shaped web. The sealing lip and the ring-shaped reinforcing profile are concentric and provide sufficient pretension against the cylinder wall. To simplify the design of the mold, the ring-shaped web begins directly above the support segment.
An especially high degree of dimensional rigidity can be obtained especially by providing transverse webs between the ring-shaped web and the sealing lip.
In a variant, the reinforcing profile is located axially between the support segment and the sealing lip and extends toward the surface against which the seal is to be formed. This design principle makes it possible to provide the sealing lip with very high rigidity, and at the same time the piston ring can be removed easily from the mold.
It is provided that the reinforcing profile is formed by a box profile, which is open radially toward the outside.
Other objects and features of the present invention will become apparent from the following detailed description considered in conjunction with the accompanying drawings. It is to be understood, however, that the drawings are designed solely for purposes of illustration and not as a definition of the limits of the invention, for which reference should be made to the appended claims. It should be further understood that the drawings are not necessarily drawn to scale and that, unless otherwise indicated, they are merely intended to conceptually illustrate the structures and procedures described herein.
The single-tube vibration damper 1 consists essentially of a pressure tube 3, in which a piston 5, mounted on a piston rod 7, is installed with freedom of axial movement. At the exit end of the piston rod 7, a piston rod guide 9 closes off a working space 11, which is filled with damping medium. This working space is separated by a separating piston 13 from a gas space 15, which has a bottom part 17 with an eye 19 at the end.
When the piston rod moves, damping medium is displaced through the damping valves 21 in the piston 5, the valves being formed by valve disks 23. A piston ring 25, which covers a circumferential surface of the piston 5, prevents the medium from flowing laterally around the piston.
It is common to all the variants according to
Thus, while there have shown and described and pointed out fundamental novel features of the invention as applied to a preferred embodiment thereof, it will be, understood that various omissions and substitutions and changes in the form and details of the devices illustrated, and in their operation, may be made by those skilled in the art without departing from the spirit of the invention. For example, it is expressly intended that all combinations of those elements and/or method steps which perform substantially the same function in substantially the same way to achieve the same results are within the scope of the invention. Moreover, it should be recognized that structures and/or elements and/or method steps shown and/or described in connection with any disclosed form or embodiment of the invention may be incorporated in any other disclosed or described or suggested form or embodiment as a general matter of design choice. It is the intention, therefore, to be limited only as indicated by the scope of the claims appended hereto.
| Number | Date | Country | Kind |
|---|---|---|---|
| 103 57 561.8 | Dec 2003 | DE | national |
