Bonded guide tube and bellow assembly for air spring

Abstract

An air spring includes a bellow at least partially delimiting at least one working chamber that is constructed and arranged to be filled with compressed air. A guide tube surrounds at least a portion of the bellow. A bonding agent solely fixes a portion of the bellow to the guide tube. A piston is associated with the bellow. The bellow is constructed and arranged to roll with respect to an outer surface of the piston and an inner surface of the guide tube.

Claims

1. A method of securing a portion of a bellow to a metal guide tube of an air spring, the method comprising the steps of: placing the bellow, in an unformed state, in an outer mold form along with the guide tube, providing a bonding agent on a portion of an inner surface of the guide tube at a location where the bellow is to be fixed to the guide tube, the bonding agent being separate from material of the bellow, pressing the bellow against the outer mold to form the bellow and pressing the bellow against a portion of the guide tube so that the bonding agent contacts the guide tube and a portion of a peripheral surface of the bellow, curing the bellow and bonding agent, and after the curing step, removing the outer mold form, with the bonding agent fixing the formed bellow directly to the guide tube.

2. The method of claim 1, wherein the pressing step includes using an inflatable portion of a mold member to engage and press the bellow.

3. The method of claim 1, wherein step of providing the bonding agent includes providing an adhesive as the bonding agent.

4. The method of claim 1, wherein step of providing the bonding agent includes providing an epoxy as the bonding agent.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention will be better understood from the following detailed description of the preferred embodiments thereof, taken in conjunction with the accompanying drawings, wherein like reference numerals refer to like parts, in which:

(2) FIG. 1 is a view of a conventional air spring having a guide tube crimped to a support ring, thereby fixing a rolling bellow to the guide tube.

(3) FIG. 2 is a view of an air spring having the rolling bellow bonded directly onto the guide tube in accordance with an embodiment.

(4) FIG. 3 is a view of the rolling bellow and guide tube in an outer mold form in accordance with an embodiment.

(5) FIG. 4 is a view of the rolling bellow of FIG. 3 now shown pressed against the outer mold, with the guide tube acting as an outer mold during a curing process and with the rolling bellow bonded to the guide tube in accordance with an embodiment.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

(6) With reference to FIG. 2, a portion of an air spring is shown, generally indicated at 10, for a motor vehicle. The air spring 10 can be of the type disclosed in U.S. Pat. No. 8,474,798, the content of which is hereby incorporated by reference into this specification. Thus, the air spring 10 has at least one working chamber 12 filled with compressed air, which is at least partially delimited by an elastomer rolling bellow 14 that forms a rolled fold 14a. When the vehicle experiences spring compression and spring extension, the rolling bellow 14 rolls both on a rotationally symmetrical outer surface 15 of a roll-off piston 16 and on an inner surface 17 of a preferably metal guide tube 18. Thus, the guide tube 18 surrounds a portion of the rolling bellow 14. At its ends 20, 22, the rolling bellow 14 is fastened to the connecting parts by clamping rings 24, 26. The air spring 10 has a centrally arranged hydraulic damper structure, generally indicated at 27, including a piston rod 28 preferably connected via an air spring cover (not shown) to the bodywork. The piston rod 28 is connected to a damper cylinder 30 that is connected, via a connecting flange (not shown) to a wheel support of the chassis in the conventional manner. The conventional cardanic fold 33 of the bellow 14 is adjacent to an end 34 of the guide tube 18.

(7) Instead of crimping the guide tube 18 to a support ring to fix the rolling bellow 14, the bellow 14 is fixed directly to the guide tube 18 solely by a bonding agent 36, generally adjacent to the cardanic fold 33. The bonding agent 36 can be any suitable agent such as adhesive, epoxy, rubber cement, etc. The bonding area is shown at A in FIG. 2. With the embodiment, advantageously, the support tube 32 of FIG. 1 is no longer required, nor is a crimping step. Conventionally, the bellow 14 is molded in a manufacturing step. Thus, the embodiment makes use of this molding step to bond the bellow 14 to the guide tube 18 as explained below.

(8) With reference to FIG. 3, the unformed bellow 14 is placed in a conventional outer mold form 38 along with the guide tube 18. The bonding agent 36 is provided on a portion of an inner surface 40 of the guide tube 18 at a location where the bellow 14 is to be fixed to the guide tube 18. As shown in FIG. 4, the bellow 14 is pressed by an inflatable portion 41 of a mold member 42 against the outer mold form 38 in the conventional manner to from the bellow and, in accordance with an embodiment, the bellow 14 is also pressed against a portion of the guide tube 18 so that the bonding agent 36 contacts the guide tube 18 and a portion of a peripheral surface 44 of the bellow 14. The bellow and bonding agent 36 is then cured, with the guide tube 18 acting as an outer mold during the curing process. Once cured, the outer mold form 38 is removed, with the bonding agent 36 fixing the formed bellow 14 directly to the guide tube 18.

(9) Thus, the use of the bonding agent 36 during the bellow molding process eliminates the need for the conventional support ring and crimping process, thereby reducing parts and cost and also reducing a cumbersome manufacturing process of an air spring.

(10) The foregoing preferred embodiments have been shown and described for the purposes of illustrating the structural and functional principles of the present invention, as well as illustrating the methods of employing the preferred embodiments and are subject to change without departing from such principles. Therefore, this invention includes all modifications encompassed within the scope of the following claims.