Attaching a damper cap to a damper tube

Abstract

Attachment of a damper cap (1) to a damper tube (2) of an air suspension strut, wherein the damper tube (2) comprises an end face (3) and a circumferential surface (4) oriented perpendicular to it, wherein the damper cap (1) comprises an end part (5) and a leg (6) oriented perpendicular to it, wherein the leg (6) is hollow cylindrical, wherein the damper cap (1) rests on the end face (3) of the damper tube (2) by means of the end part (5) and the leg (6) at least partially surrounds the circumferential surface (4) of the damper tube (2), characterized in that a recess (11) is provided on the inside of the damper cap (1) along the leg (6), wherein the leg (6) comprises an inclined surface (9) directed towards the circumferential surface (4), wherein a slidable fastening means (7) is provided within the recess (11).the first surface (10) rests against the inclined surface (9) of the leg (6) and the second surface against the outer surface (4) of the damper tube (2), wherein the fastening means (7) is moved against the leg (6) and along the outer surface (4) by means of a force-generating means (8) such that the damper cap (1) is fastened to the damper tube (2).

Description

[0001] The invention relates to a fastening of a damper cap to a damper tube of an air spring strut according to the preamble of claim 1 and to an air spring strut with such a damper cap according to claim 5.

[0002] An air suspension strut, such as that known from US 2015 / 0 202 938 A1, is installed between the vehicle chassis or a wheel carrier and the vehicle body. The air suspension strut typically comprises an air spring and a shock absorber. The air spring cushions the wheel, while the shock absorber dampens the vibrations of the wheel or the vehicle body.

[0003] The air spring essentially consists of an air spring cover, a rolling piston, and a rolling bellows clamped between them in an airtight manner, defining a pressurized working chamber. The rolling bellows is enclosed by a sleeve-shaped outer guide and rolls along the concentric rolling piston during compression, forming a rolling fold. The air spring strut is connected to the vehicle body via the air spring cover using appropriate fasteners.

[0004] The shock absorber located within the air spring is connected to the wheel carrier on one side and, on the other, its piston rod, which can be inserted into the damper tube, is mounted in the air spring cover via a damper bearing. When the vehicle wheel compresses against the vehicle body, the air spring, together with the outer guide, pivots relative to the rolling piston.

[0005] The rolling piston is typically mounted vertically and / or suspended from the shock absorber's damper tube. A lower support ring and a damper cap are used for this purpose. The damper cap is typically pressed onto the damper tube to prevent twisting or pulling off and to securely connect the damper cap to the damper tube.

[0006] In the case of a hanging rolling piston, as is known, for example, from DE 10 2012 220 204 A1, an additional elastomer element can be provided between the damper cap and the damper tube in order to provide additional acoustic decoupling.

[0007] The disadvantage is that with different air spring strut designs, the press fit reaches its limits if the tolerance range is not tight enough. In particular, the inclusion of an elastomer element requires the damper cap to be individually adapted depending on the air spring strut design.

[0008] From JP 2003 - 194 126 A a fastening of a damper cap to a damper tube is known, wherein the damper cap is connected to a damper tube by means of crimping with a fastening means.

[0009] The object of the invention is to provide a damper cap for the damper tube of an air spring strut and an air spring strut with a damper cap which can be attached to a damper tube in a tolerance-compensating and at the same time firmly.

[0010] The problem underlying the invention is solved with the features of the independent patent claims.

[0011] According to the invention, a fastening of a damper cap to a damper tube of an air spring strut is provided, wherein the damper tube comprises an end face and a lateral surface oriented perpendicular thereto, wherein the damper cap comprises an end part and a leg oriented perpendicular thereto, wherein the leg is formed as a hollow cylinder, wherein the damper cap rests on the end face of the damper tube by means of the end part and the leg at least partially surrounds the lateral surface of the damper tube, wherein a recess is provided along the leg on the inside of the damper cap, wherein the leg comprises an inclined surface directed towards the lateral surface, wherein a displaceable fastening means is provided within the recess, which rests with a first surface on the inclined surface of the leg and with a second surface on the lateral surface of the damper tube,wherein the fastening means is displaced against the leg and along the lateral surface by means of a force-generating means in such a way that the fastening of the damper cap to the damper tube takes place.

[0012] The specially designed beveled surfaces of the leg and the fastening means, which are in surface contact, in conjunction with the force-generating means, create a special fastening mechanism that prevents the damper cap from being pulled off the damper tube. The damper cap adapts to wide tolerance ranges and can be used to compensate for tolerances. This means that the same damper cap can be used with damper tubes of different diameters without the damper cap having to be adjusted in its dimensions. This provides a damper cap for different air spring struts based on the modular principle. At the same time, the movable fastening means allows the damper cap to first be pushed onto the damper tube and then moved axially by the force-generating means, creating the fastening.

[0013] Preferably, the fastening means is a wedge, wherein the wedge has a wedge surface as its first surface, which rests against the inclined surface of the damper cap. The wedge shape is particularly well suited for securing the damper cap to the damper tube to prevent it from being pulled out. According to a preferred embodiment, the force-generating means is a spring provided within the recess, which bears on one side against a contact surface of the recess and on the other side against the fastening means or wedge. The spring is a particularly suitable means for generating a force that displaces the wedge. At the same time, the compressed spring allows the damper cap to be pushed onto the damper tube. For example, a coil spring or a compression spring with bent and ground end coils is used.

[0014] According to a further preferred embodiment, the fastening means or wedge is coated or covered with an elastomeric material. Such a coating, preferably made of rubber, increases the contact force and prevents loosening.

[0015] It is used to attach a damper cap to an air spring strut for a motor vehicle.

[0016] Further preferred embodiments of the invention emerge from the subclaims and the following description of an embodiment with reference to the figure.

[0017] It shows Fig. 1 in detail an embodiment of a fastening of a damper cap to a damper tube.

[0018] Fig.1 shows a section of an air spring strut with an exemplary damper cap 1 on a damper tube 2. Damper tube 2 comprises an end face 3 and a circumferentially oriented outer surface 4. Damper cap 1 is pushed onto damper tube 2 and rests on end face 3. Damper cap 1 has an end part 5 and a leg 6 oriented perpendicularly thereto, which is hollow-cylindrical in the circumferential direction. The underside of the end part 5 rests on the end face 3 of the damper tube 2, with leg 6 surrounding the outer surface 4 at least in the upper region of the damper tube 2 and being spatially spaced from it.

[0019] The “top / bottom” orientation used is determined by the regular installation position of an air spring strut, in which the air spring cover is connected to the body and the shock absorber is connected to the wheel carrier of a vehicle.

[0020] On the inside, the damper cap forms a recess 11, which is essentially delimited by or formed by leg 6. On the one hand, recess 11 extends above into end part 5, and on the other hand, recess 11 extends below the end face 3 laterally along the lateral surface 4 on leg 6. The lower part of recess 11 is delimited by an inclined surface 9 of leg 6. This is achieved by an inclined surface 9, which extends downwards and towards the lateral surface 4.

[0021] Within recess 11, a fastening means in the form of a wedge 7 is provided. Wedge 7 has a wedge surface 10 and rests against the outer surface 4 of the damper tube 2 with an axial surface opposite the wedge surface 10. Wedge surface 10, in turn, rests against the inclined surface 9 of the leg 6. Wedge 7 itself is designed such that it does not completely fill the recess 11 and is arranged to be movable and displaceable within it.

[0022] By means of a force-generating means in the form of a mechanical spring 8 within the recess 11, it is possible to displace wedge 7 with its tapered wedge surface 10 along the inclined inclined surface 9 such that wedge 7 is pressed between leg 6 and outer surface 4. For this purpose, spring 8 rests on the one hand against wedge 7 and on the other hand against an inner contact surface of the damper cap 1 in the recess 11.

[0023] The specially designed, surface-to-surface contacting inclined surfaces of wedge 7 and leg 6, in conjunction with the spring 8 acting on wedge 7, create a unique fastening mechanism for damper cap 1 to damper tube 2, preventing damper cap 1 from being pulled off damper tube 2. At the same time, a damper cap 1 is created that can be manufactured with generous tolerance compensation, allowing it to be installed more universally on various air spring struts. As a clamped spring 8, this allows damper cap 1 with wedge 7 to first be pushed onto damper tube 2, and then, due to its spring force, wedge 7 is pushed against the inclined surface 9 of leg 6, thereby securing damper cap 1.

[0024] Damper cap 1 is preferably provided from a steel, whereby wedge 7 can be selected from any metal with a high strength.

[0025] Preferably, wedge 7 can be coated or covered with an elastomer, such as rubber. This increases the friction between wedge surface 10 and inclined surface 9, which should better prevent the wedge 7 from coming loose. List of reference symbols 1 damper cap 2 damper tube 3 Frontal surface 4 Shell surface 5 Front part 6 legs 7 Fasteners 8 spring 9 Inclined surface 10 Wedge surface 11 Recess

Claims

[1] Fastening of a damper cap (1) to a damper tube (2) of an air spring strut, wherein the damper tube (2) comprises an end face (3) and a lateral surface (4) oriented perpendicularly thereto, wherein the damper cap (1) comprises an end part (5) and a leg (6) oriented perpendicularly thereto, wherein the leg (6) is formed as a hollow cylinder, wherein the damper cap (1) rests on the end face (3) of the damper tube (2) by means of the end part (5) and the leg (6) at least partially surrounds the lateral surface (4) of the damper tube (2), characterized bythat a recess (11) is provided on the inside of the damper cap (1) along the leg (6), wherein the leg (6) comprises an inclined surface (9) directed towards the outer surface (4), wherein a displaceable fastening means (7) is provided within the recess (11), which rests with a first surface (10) on the inclined surface (9) of the leg (6) and with a second surface on the outer surface (4) of the damper tube (2), wherein the fastening means (7) is displaced by means of a force-generating means (8) against the leg (6) and along the outer surface (4) in such a way that the fastening of the damper cap (1) to the damper tube (2) takes place. [2] Fastening according to claim 1, characterized by that the fastening means is a wedge (7), wherein the wedge (7) comprises as a first surface a wedge surface (10) which bears against the inclined surface (9) of the leg (6). [3] Fastening according to claim 1 or 2, characterized bythat the force-generating means (8) is a spring (8) which is provided within the recess (11), wherein the spring (8) bears on the one hand against a contact surface of the recess (11) and on the other hand against the fastening means (7). [4] Fastening according to one of claims 1 to 3, characterized by that the fastening means (7) is coated with an elastomeric material. [5] Air spring strut with a damper cap attachment according to one of claims 1 to 4.

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