Shock absorber arrangement for a vehicle suspension and use of a lubricant for same

Abstract

A shock absorber arrangement for a vehicle suspension contains a shock absorber having a damper cap and a piston rod, and a supplementary spring which is arranged on the piston rod opposite the shock absorber and has an outer surface facing the damper cap and an inner surface facing the piston rod, and is configured for damping the movement of the shock absorber in the direction of the piston rod on contact with the damper cap. The outer surface and/or the inner surface is at least partially coated with a lubricant.

Claims

1-15. (canceled)

16. A shock absorber arrangement for a vehicle suspension, comprising: a shock absorber which has a damper cap having an end face and has a piston rod, and a supplementary spring which is arranged on the piston rod opposite the shock absorber and has an outer surface facing the damper cap and an inner surface facing the piston rod, and is configured for damping movement of the shock absorber in the direction of the piston rod on contact with the damper cap, wherein the outer surface of the supplementary spring comes into contact with the end face of the damper cap, and the supplementary spring performs an evasive movement if the shock absorber continues to move, resulting in a relative movement of the outer surface along the end face, wherein the supplementary spring expands in an inward and outward direction transverse to the piston rod on compression of the supplementary spring, whereupon the inner surface comes into contact with the piston rod, and wherein the outer surface facing the damper cap and/or the inner surface facing the piston rod is at least partially coated with a lubricant.

17. The shock absorber arrangement according to claim 16, wherein the shock absorber comprises a damper fluid and the lubricant is different from the damper fluid.

18. The shock absorber arrangement according to claim 16, wherein the lubricant is a friction-reducing material.

19. The shock absorber arrangement according to claim 16, wherein the lubricant comprises one or more pulverulent organic and/or inorganic materials.

20. The shock absorber arrangement according to claim 19, wherein the lubricant comprises a silicate.

21. The shock absorber arrangement according to claim 19, wherein the lubricant comprises graphite.

22. The shock absorber arrangement according to claim 6, wherein the lubricant comprises a medium- or high-viscosity fluid.

23. The shock absorber arrangement according to claim 22, wherein the fluid has a kinematic viscosity of 270 mm.sup.2/s or more at 40° C.

24. The shock absorber arrangement according to claim 22, wherein the fluid comprises a resin.

25. The shock absorber arrangement according to claim 16, wherein hie lubricant comprises a water- and/or oil-repellent material.

26. The shock absorber arrangement according to claim 16, wherein the lubricant comprises pulverulent and fluidic constituents.

27. A method of reducing noise coming from a shock absorber arrangement of a vehicle suspension, comprising: applying a lubricant to the shock absorber arrangement according to claim 16 to reduce noise.

28. The method according to claim 27 wherein the lubricant is a friction-reducing material; and/or wherein the lubricant comprises one or more pulverulent materials, and/or comprises a silicate, and/or comprises graphite.

29. The method according to claim 28, wherein the lubricant comprises a medium- or high-viscosity fluid; and/or wherein the lubricant comprises a resin.

30. The method according to claim 27, wherein the lubricant is a combination of solid and fluidic constituents.

31. The shock absorber arrangement according to claim 20, wherein the silicate is a sheet silicate.

32. The shock absorber arrangement according to claim 20, wherein the silicate is selected from the group consisting of talc, muscovite, phlogopite, apophyllite, and carletonite.

33. The shock absorber arrangement according to claim 23, wherein the fluid has a kinematic viscosity of 2000 mm.sup.2/s or more at 40° C. and a kinematic viscosity of 270 mm.sup.2/s or more at 100° C.

34. The shock absorber arrangement according to claim 23, wherein the fluid has a kinematic viscosity of 16000 mm.sup.2/s or more at 40° C. and a kinematic viscosity of 2000 mm.sup.2/s or more at 100° C.

35. The shock absorber arrangement according to claim 24, wherein the resin is a polyalkylene glycol.

Description

[0075] The invention will be illustrated below with reference to the accompanying figures with the aid of a preferred working example. The figures show

[0076] FIG. 1a, b a shock absorber arrangement according to a preferred working example in different operating states,

[0077] FIG. 2a detailed depiction of the shock absorber arrangement of FIG. 1a, b, and

[0078] FIG. 3a-c further detailed depictions of the shock absorber arrangement according to FIGS. 1a, b and 2. in different operating states.

[0079] FIG. 1 shows a shock absorber arrangement 1. The shock absorber arrangement 1 comprises a shock absorber 3 having a damper cap 7 and a piston rod 5 which extends through the damper cap 7.

[0080] Opposite the damper cap 7, a supplementary spring 9 is arranged along the piston rod 5. The supplementary spring 9 is accommodated by a base 11.

[0081] The supplementary spring 9 has an outer surface 13 which faces an outer surface 15 of the damper cap 7.

[0082] During operation of the shock absorber arrangement 1, a state as shown in FIG. 1B can arise as a result of the movement of the damper. In this state, the outer surface 13 of the supplementary spring 9 is in contact with the end face 15 of the damper cap. If the shock absorber 3 continues to move, the supplementary spring 9 performs an evasive movement, as a result of which a relative movement of the outer surface 13 along the end face 15 occurs.

[0083] The working principle according to the invention, which then comes to bear, is explained in more detail in FIGS. 2 and 3a-c.

[0084] In FIG. 2, the supplementary spring 9 is firstly depicted in the partially sectioned state. The supplementary spring 9 is not compressed in the state shown in FIG. 2.

[0085] On the outer surface 13, the supplementary spring 9 is at least partially coated with a lubricant 17, which is particularly preferably a friction-reducing material such as talcum powder or another material of the above-described preferred embodiments. The lubricant 17 is, in the working example shown, additionally applied by way of example at least partially along an inner surface 21 of the supplementary spring 9, with the inner surface 21 facing the piston rod 5. A gap 19 is present between the inner surface 21 and the piston rod 5.

[0086] When compression of the supplementary spring occurs as indicated by way of example in FIG. 1b, the supplementary spring 9 expands in the radial direction, i.e. transverse to the piston rod 5, in an outward direction and an inward direction. The inner surface 21 then comes into contact with the piston rod 5. Here too, the lubricant 17 brings about the advantages according to the invention. Although the noise-reducing effect is not as pronounced as in the case of application of the lubricant 17 to the outer surface 13, it is nevertheless present and advantageous according to the invention.

[0087] The working example of FIG. 2 should be considered to be illustrative in so far as the exclusive coating of the inner surface 21 (at least partially) and also the exclusive coating of only the outer surface 13 (at least partially) are to be considered as separately encompassed preferred embodiments.

[0088] FIG. 3a-c show the behavior of the lubricant 17 in different operating states. In the interests of a simple depiction, only the coating on the outer surface 13 is shown here. The concept could, however, be carried over analogously to the behavior of a coated inner surface 21 relative to the piston rod 5 (cf. FIG. 2).

[0089] In FIG. 3a, a state in which the supplementary spring 9 has been coated with lubricant 17 on the outer surface 13 but has not yet come into contact with the damper cap 7 is firstly shown. Damper fluid 23 has collected on the end face 15 of the damper cap 7 as a result of operation of the shock absorber. If, proceeding from FIG. 3a, the supplementary spring 9 is brought into contact with the damper cap 7, the outer surface 13 takes up some of the damper fluid 23. Both damper fluid 23 and lubricant 17 which preferably but not necessarily partially or completely binds the damper fluid 23 if the lubricant comprises or consists of a pulverulent material are then present on the outer surface 13.

[0090] Due to the additional presence of the lubricant 17, an undesirable stick-slip effect is reliably decreased during continued operation.

[0091] FIG. 3c shows the state after prolonged operation or the state in the case of only very sparing wetting of the outer surface 13 with lubricant 17. The amount of damper fluid 23 and of lubricant 17 on the outer surface 13 is overall very much smaller than in the state shown in FIG. 3b. A significant noise reduction is nevertheless still achieved in the case of such an arrangement relative to a state in which damper fluid 23 but no additional lubricant 17 of a different nature than the damper fluid 23 is present on the outer surface 13.

[0092] It is a particular advantage of the invention that it can also be implemented retrospectively with little expense in existing damper systems. Since a partial and/or very thin coating of the supplementary spring 9 with the lubricant 17 suffices for reliable noise reduction, any envisaged maintenance intervals for renewing the coating can be made correspondingly long.

[0093] In a preferred embodiment, which envisages a pulverulent material as lubricant, the amount of the lubricant applied is in the region of 1 kg/m.sup.2 or less, preferably in the region of 250 g/m.sup.2 or less, particularly preferably in the range from 1 g/m.sup.2 to 150 g/m.sup.2.

[0094] In a further preferred embodiment, in which a polyalkylene glycol is used as lubricant, the amount of lubricant applied is preferably in the region of less than 500 g/m.sup.2, preferably in the region of 100 g/m.sup.2 or below, particularly preferably in the range from 0.1 g/m.sup.2 to 40 g/m.sup.2.

[0095] It has been found to be sufficient for many practical cases for, for example when using talcum powder as lubricant 17, an amount of only about 100 g/m.sup.2 of talcum powder to be used, based on the surface area of a shaped polyurethane body. When using polyalkylene glycols, it has even been found that the desired effects are obtained even at amounts of about 15 g/m.sup.2.