GB2211269A

GB2211269A - A shock absorber unit

Info

Publication number: GB2211269A
Application number: GB8822573A
Authority: GB
Inventors: Guenther Handke
Original assignee: Fichtel and Sachs AG
Current assignee: ZF Friedrichshafen AG
Priority date: 1987-10-16
Filing date: 1988-09-26
Publication date: 1989-06-28
Anticipated expiration: 2008-09-26
Also published as: DE3735058A1; GB2211269B; GB8822573D0

Description

Title: A shock absorber unit.

This invention relates to a shock absorber unit for a motor vehicle comprising a container having an axis and two ends, at least one cavity within said container, shock absorbing means within said at least one cavity, a piston rod extending inwards and outwards of said at least one cavity through a first-one of said two ends, fastening means on an external end portion of said piston rod member for fastening said piston rod member to the body of said motor vehicle, said fastening means comprising a support cap with a support face adapted to support an elastic body to be interposed between said support cap and said body, and a protection tube fastened to said external end portion of said piston rod member, surrounding said container and extending towards a second one of said two ends over at least part of the axial length of said container, said protection tube being fastened to said external end portion of said piston rod member by a carrier cap fastened to said external end portion of said piston rod member on the side of said support cap remote from said support face.

In known shock absorber units the carrier caps are 2 made of metal. These meal-shaped carrier caps are expensive in manufacturing.

It is an ob-'ect of the present invention to provide a J shock absorber unit of the type as defined above which canbe manufactured in a more economic way.

According to the present invention the carrier cap can be made of synthetic plastic material.

It has been found that a carrier cap made of synthetic plastic material is fully sufficient if the support cap is shaped such that the elastic body, which is generally made of a caoutchouc-like material, is prevented from contact with the carrier cap.

Also the protection tube may be made of synthetic plastic material.

The carrier cap can be connected with the protection tube by connecting means such as snap-connecting means. It is, however, also possible to make the carrier cap integral with the protection tube.

The positioning and fixation of the carrier cap and the support cap on the piston rod member can be made as follows: The external end portion of said piston rod member has a first substantially axially directed shoulder face and a second substantially axially directed shoulder face; the first shoulder face is nearer to said at least one cavity and the second shoulder face is more remote from said at least one cavity. A first centering face has a larger diameter and extends in axial direction between said first shoulder face and said second shoulder face; a second centering face extends in axial direction above said second shoulder face axially away from said first shoulder face. The carrier cap has a radially inwardly directed fastening flange engaging said first shoulder face and said first centering face, and said support tube has a radially inwardly directed fastening flange engaging said second shoulder face and said second centering face.

If it is desired to improve the fixation of the carrier cap on the piston rod member, the carrier cap may have an axially extending sleeve portion engagingly surrounding an axially extending section of said external end portion of said piston rod member. This axially extending sleeve portion and this axially extending section may be substantially cylindrical.

In order to safely prevent contact of said cacutchouc 4 block and said carrier cap, said support cap may extend radially outwards beyond said carrier cap and said protection tube.

In order to provide positive engagement between said caoutchouc block and said support cap, the support cap may have a radially inwardly directed fastening flange engaging said external end portion of said piston rod member, a frusto-conical side wall adjoining said fastening flange and extending with increasing diameter from said fastening flange towards said second end of said container and a radially outer substantially axially directed support shoulder. This support shoulder may have a radially outer edge portion directed towards said second end of said container or extending axially away from said second end of said container.

The carrier cap may have a fastening section adjacent to the piston rod member, a frusto-conical side wall adjoining said fastening section and extending with increasing diameter axially towards said second end of said container, and a transition section adjoining said frusto-conical section and said protection tube.

In order to prevent a contact of the support cap and the carrier cap, the support cap may have axial distance from the carrier cap at least adjacent to the radially outer diameters of said support cap and said carrier cap.

The carrier cap may be manufactured with a very thin wall. The functions of the two caps are separated. The support cap must be only adapted to the elastic body, e. g. caoutchouc body, whereas the carrier cap must be adapted only to the fixation of the protection tube. The support cap can be manufactured in different forms so that it may be adapted to different vehicle types.

The invention will be explained in greater detail hereinafter with reference to embodiments shown in the accompanying drawings, in'which:

Figure 1 shows a longitudinal section through a first embodiment of the invention; Figure 2 shows a longitudinal section through a second embodiment of the invention and Figure 3 shows a longitudinal section through a third embodiment of the invention.

In Figure 1 the shock absorber unit comprises a container tube 11 and a piston rod member 12 extending inwardly and outwardly of the container tube through the upper end thereof. The piston rod member carries the damping devices (not shown). The piston rod 12 is provided with.

6 a threaded fastening pin 13 at the upper end of its external end portion. The shock absorber unit may be fastened via said threaded pin 13 of the external end portion and through caoutchouc block to a vehicle body such as to permit certain pivotability of the shock absorber unit with respect to the vehicle body. A protection tube 15 surrounds the container tube 11. This protection tube 15 is fixed to the external end portion of the piston rod 12 by a carrier cap 16.

The carrier cap 16 has a cylindrical sleeve portion 16a surrounding a cylindrical section 12a of the piston rod 12. A radially inwardly directed flange 16b of the carrier cap 16 engages an axially directed shoulder face 12b of the piston rod member 12a and a centering face 12c of the piston rod member 12a. A conical side wall 16c of the carrier cap 16 extends downwards and radially outwards as seen in Fig. 1. A cylindrical connection sleeve 16d of the carrier cap 16c adjoins the frusto-conical section 16c. This connection sleeve 16d is in snapping engagement with an upper end portion 15a of the protection tube 15 through a radially inwardly directed snapping flange 15b of the protection tube 15. In addition, one can provide as seen on the left-hand side of Figure 1 a shoulder 15c at the transition between the lower portion of the protection tube 15 and the upper end portion 15a of the protection tube, so that the cylindrical connection 7 sleeve 16d is axially engaged between the shoulder face 15c and the snapping flange 15b. The carrier cap 16 engages the cylindrical section 12a, the shoulder face 12b and the centering face 12c witha press-fit.

A support cap 18 is located above the carrier cap 16. The support cap 18 is press-fitted on a further shoulder face 12d and a further centering face 12e by a radially inwardly directed fastening flange 18a. The support cap 18 has a frusto-conical side wall 18b with a support face 18c. At the lower end of the frusto-conical side wall 18 there is provided a support shoulder 18d with an axially extending edge portion 18e. A caoutchouk block (not shown) is supported by the support cap 18, namely on the support face 18c and the support shoulder 18d. The edge portion 18e prevents contact of the caoutchouc block even under maximum load with the protection tube 15.

Between the support cap 18 and the carrier cap 18 there exists a gap 24 so that even on certain movements of the protection tube 15 no contact between the support cap 18 and the carrier cap 16 exists. The protection tube 15 and the carrier cap 16 are preferably made as synthetic plastic moldings manufactured by the well known blow-molding technique. They can be made, however. in accordance with the equally well known in3ection molding technique. The support tube 18 is preferably of metal.

8 In the embodiment of Figure 2 the carrier cap is molded integrally with the protection tube 15. In all other respects the embodiment of Figure 2 is identical with the embodiment of Figure 1.

In the embodiment of Figure 3 the support shoulder 18d is provided with an upwardly extending edge portion 118e such as to define a gutter 23 so that the caoutchouc block cannot escape and cannot contact the protection tube 15. In all other respects the embodiment of Figure 3 is identical with the embodiment of Figure 1.

While specific embodiments of the invention have been shown and described in detail to illustrate the application of the inventive principles, it will be understood that the invention may be embodied otherwise without departing from such principles.

The reference numerals in the claims are only used for facilitating the understanding and are by no means restrictive.

R 9

Claims

CLAIMS:

1. A shock absorber unit for a motor vehicle comprising a container (11) having an axis an two ends, at least one cavity within said container (11), shock absorbing means within said at least one cavity, a piston rod (12) extending inwards and outwards of said at least one cavity through a first one of said two ends, fastening means (13, 18) on an external end portion of said piston rod member (12) for fastening said piston rod member to the body of said motor vehicle, said fastening means comprising a support cap (18) with a support face (18c) adapted to support an elastic body to be interposed between said support cap (18) and said vehicle body, and a protection tube (15) fastened to said external end portion of said piston rod member (12), surrounding said container (11) and extending towards a second one of said two ends over at least part of the axial length of said container (11), said protection tube (15) being fastened to said external end portion of said piston rod member (12) by a carrier cap (16)fastened to said external end portion of said piston rod member (12) on the side of said support cap (18) remote from said support face (18c), said carrier cap (16) being made of synthetic plastic material.

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2. A shock absorber unit as set forth in claim 1, said protection tube (15) being made of synthetic plastic material.

3. A shock absorber unit as set forth in claims 1 or 2, said carrier cap (16) being connected with said protection tube (15) by connecting means (16d, 15a, 15b,.15c)

4. A shock absorber unit as set forth in claim 3, said connecting means (16d, 15a, 15b, 15c) being snapconnecting means.

5. A shock absorber unit as set forth in claims 1 or 2, said carrier cap (16) being integral with said protection tube (15).

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6. A shock absorber unit as set forth in one of claims 1 to 5, said external end portion of said piston rod member (12) having a first substantially axially directed shoulder face (12b) and a second substantially axially directed shoulder face (12d), said first shoulder face (12b) being nearer to said at least one cavity and said second shoulder face (12d) being more remote from said at least one cavity, a first centering face (12c) having a larger diameter p extending in axial direction between said first shoulder face (12b) and said second shoulder face (12d), a second centering face (12e) extending in axial direction above said second shoulder face (12d) axially away from said first shoulder face (12b), said carrier cap (16) having a radially inwardly directed fastening flange (16b) engaging said first shoulder face (12b) and said first centering face (12c), and said support cap (18) having a radially inwardly directed fastening flange (18a) engaging said second shoulder face (12d) and said second centering face (12e).

7. A shock absorber unit as set forth in one of claims 1 to 6, said carrier cap ' (16) having an axially extending sleeve portion (16a) engagingly surrounding an axially extending section (12a) of said external end portion of said piston rod member (12).

8. A shock absorber unit as set forth in claim 7, said axially extending sleeve portion (16a) and said axially extending section (12a) being substantially cylindrical.

9. A shock absorber unit as set forth in one of claims 1 to 8, said support cap (18) extending radially outwards beyond said carrier cap (16) and said protection tube (15)- 12

10. A shock absorber unit as set forth in one of claims 1 to 9, said support cap (18) having a radially inwardly directed fastening flange (18a) engaging said external end portion of said piston rod member (12), a frusto-conical side wall (16c) adjoining said fastening flange (18a) and extending with increasing diameter from said fastening flange (18a) towards said second end of said container (11) and a radially outer substantially axially directed support shoulder (18d).

11. A shock absorber unit as set forth in claim 10, said support shoulder (18d) having a radially outer edge portion (18e) directed towards said second end of said container (11).

12. A shock absorber unit as set forth in claim 10, said support shoulder (18d) having a radially outer edge portion (118e) extending axially away from said second end of said container (11).

13. A shock absorber uflit as set forth in one of claims 1 to 12, said carrier cap (16) having a fastening section (16a, 16b) adjacent to said piston rod member (12), a frusto-conical side wall (16c) adjoining said fastening section (16a, 16b) and extending with increasing diameter axially towards said second end of said container (11), and a transition section (16d) adjoining said frustoconical section (16c) and said protection tube (15).

14. A shock absorber unit as set forth in one of claims 1 to 13, said support cap (18) having axial distance from said carrier cap (16) at least adjacent to the radially outer diameters of said support cap (18) and said carrier cap (16).

Published 1989atThe Patent Office. State House, 86171 Holborn, London WC1R 4TP. Further copies maybe obtained from The Patent Office. Sales Branch, St Mary Cray, Orpington, Kent BR5 3RD. Printed by Multiplex techniques ltd, St Mary Cray, Kent, Con. 1187