Abstract:
An air spring module is constructed and arranged to be removably mounted between a damper and a vehicular body. The module includes a bored contact piston which is slip fitted over a reciprocable piston rod of the damper. A retaining ring releasably locks the contact piston to the damper, and O-ring seals provide a seal between the contact piston and the damper. An air sleeve is secured at its lower end to the contact piston and is secured at its upper end to a canister. A bearing assembly and mount rotationally and removably secures the canister to the body.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to vehicle suspension and, in particular, is concerned with an air spring module for use with a damper. 
     2. Description of the Related Art 
     Automotive suspension struts, such as used in MacPherson-type suspensions, are commonly constructed with either coil springs or air springs mounted coaxially about the strut. A particular problem is encountered by front suspension struts which are mounted to the front steerable wheels. When the wheels are steered, the spring undergoes a twisting movement as the strut body rotates with the wheel. Such twisting undesirably changes the characteristics of the coil spring. To solve the torsional twist of coil springs, a bearing assembly is placed between the vehicle body and a mounted piston rod of the strut to allow the strut to rotate relative to the body. 
     Air springs also are mounted about suspension struts alone or in combination with coil springs. 
     It is desirable when incorporating an air suspension spring on a MacPherson strut assembly to allow for replacement of the MacPherson strut without removal or disassembly of the air spring. In order to do this, the air spring should be detachable with respect to the strut body and the vehicle body. 
     SUMMARY OF THE INVENTION 
     The present invention includes an air spring module mounted about a suspension damper. The module includes means for removably securing the air spring to the damper body and a bearing and mounting assembly for permitting the rotation of the air spring with respect to the vehicle body as the damper body rotates during steering. The module can be used with a sealed damper. 
     In a preferred embodiment, an air spring module is constructed and arranged to be removably mounted between a damper and a vehicular body. The module includes a bored contact piston which is slip fitted over a reciprocable piston rod of the damper. A retaining ring releasably locks the contact piston to the damper, and 0-ring seals provide a seal between the contact piston and the damper. An air sleeve is secured at its lower end to the contact piston and is secured at its upper end to a canister. A bearing assembly and mount rotationally and removably secures the canister to the body. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a longitudinal sectional view of an air spring module according to the present invention mounted at its upper end to a vehicle body and removably secured to a damper at its lower end. 
     FIG. 2 is an enlarged view of a portion of the assembly illustrated in the circle of FIG. 1. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     An air spring module indicated generally at 10 is illustrated in FIG. 1. As described below, the module 10 is removably mounted on a damper 100. The damper 100 includes an outer reservoir tube 102 closed at its upper end by a seal cover 104. An upstanding neck 106 of the seal cover 104 receives a reciprocable piston rod 108 extending from the damper 100. The lower end (not illustrated) of the damper 100 is mounted to a wheel assembly (not illustrated) in a conventional manner. 
     The module 10 includes a profiled contact piston 12 which is generally cylindrical and has an increased diameter at its lower portion. The piston 12 includes a stepped bore having a large diameter portion 14 and a small diameter portion 16. The reservoir tube 102 is received in the large diameter portion 14 and the neck 106 and piston rod 108 fit in the small diameter portion 16. A retaining sleeve 18 is press fitted into the small diameter portion 16 and includes an annular stop 20 which engages the end surface of the neck 106. A cup 22 is retained to the sleeve 18 by a crimped flange 24 and secures an elastomeric compression bumper 26 coaxially mounted about the piston rod 108. 
     An elastomeric air sleeve 28 is attached to the outer circumference of the contact piston 12 by a clamp or retainer 30. A rolling lobe 32 is formed in a portion of the sleeve 28 which travels along the contact piston 12 in a well-known manner. The upper portion of the sleeve 28 is secured to a partially-cylindrical canister 34 by a clamp or retainer 36. The canister 34 is welded to a lower bearing retainer 38. An elastomerically-isolated bearing assembly 40 is provided between the lower bearing retainer 38 and an upper bearing retainer 42. An elastomeric mount 44 includes a cylindrical sleeve 46 which is fitted over a stepped portion 110 of the piston rod 108. A metallic ring 48 is provided about the mount 44 and welded to the lower bearing retainer 38 to secure the mount 44. A lower rate washer 50 is secured to the sleeve 46 at a lower surface of the mount 44. A plate 52 is connected to the lower bearing retainer 38 by a retainer ring 54 received in a groove in the outer circumference of a neck portion 56 of the lower bearing retainer 38. The plate 52 includes a plurality of downwardly projecting preloaded rubber pads 58. The pads 58 rest on a plurality of thrust washers 60, preferably formed from low friction materials such as polytetrafluoroethylene. The thrust washers are concentrically mounted about the neck 56 of the lower bearing retainer 38 and are held in place by a support 62 secured to the upper bearing retainer 42. 
     The module 10 described above can be mounted on any type of damper, including hydraulic and pneumatic dampers. To assemble the module 10 in a vehicle, the contact piston 12 is fitted over the piston rod 108 and reservoir tube 102 via the stepped bore. A pair of O-ring seals 64, 66 are provided in a first circumferential groove 112 in the neck 106 of the seal cover 104 to provide a seal between the sleeve 18 and the neck 106. A retainer ring 68 is mounted in a second circumferential groove 114 of the neck 106 and is initially compressed as the sleeve 18 is slid over the neck 106. A complementary groove 70 is provided in an inner surface of the sleeve 18 so that the retainer ring 68 springs outwardly and fits snugly into the groove 70 when the contact piston 12 is in its proper position. This construction provides a quick and removable connection between the lower end of the module 10 and the damper 100. 
     A fastener 72 removably mounts the contact piston 12 to a support plate 116 welded to an outer surface of the reservoir tube 102. The damper 100 and air spring module 10 are then inserted upwardly through an opening 118 in a vehicle body 120. Fasteners 122, 124 are inserted through openings in the body 120 and threaded into complementary nuts 74, 76 welded to a lower surface of the upper bearing retainer 42. In this manner, the upper end of the air spring module 10 is removably connected to the body 120. A conduit assembly 126 and a washer 128 are secured to the upper end of the piston rod 108 by a nut 130. The conduit assembly 126 is in fluid communication with a compressor (not illustrated) to operate the air spring module 10 as desired. The compressor can include valving to control the flow of fluid into and out of the conduit assembly 126. 
     An axial bore 132 is provided in the piston rod 108 beginning at its upper end to a point below the lower rate washer 50. A plurality of radial bores 134 are provided at the lower end of the axial bore 132 to provide a fluid flow path from the conduit assembly 126 to an air chamber 78 formed by the air sleeve 28. During use, a control system (not illustrated) can add air to the air chamber 78 through the axial and radial bores 132, 134 as desired. The module 10 is effectively sealed from the damper 100. 
     As the damper 100 is turned at its lower end from a steering input, the contact piston 12 and attached air sleeve 28 and lower bearing retainer 38 rotate with the damper 100. The bearing assembly 40 permits relative rotation of the lower bearing retainer 38 with respect to the upper bearing retainer 42 and the vehicle body 120. The preloaded rubber pads 58 provide isolation and support against the thrust washers 60 for the module 10 as the lower bearing retainer 38 rotates. 
     It will be appreciated that the air spring module 10 can be used with any type of damper, including shock absorbers and struts. The module 10 is easily removed from the damper 100 by removing the fastener 72 and forcing the contact piston 12 upwardly away from the reservoir tube 102. At this point, the retainer ring 68 is compressed into the groove 114 until the sleeve 18 clears the neck 106 of the seal cover 104. Removing fasteners 122, 124 from the body 120 frees the upper end of the air module 10. Therefore, if a damper 100 becomes defective, it will be necessary only to replace the damper 100, and the air spring module 10 can be retained. On the other hand, if the air spring module 10 is damaged, e.g., if the air sleeve 28 becomes punctured, the damper 100 can be easily removed, permitting the air spring module 10 to be replaced. 
     Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention.