Abstract:
An air spring and shock absorber unit for use in vehicle suspension systems or cab suspension systems comprising a shock absorber mounted within an air spring. The lower end of the air spring bellows is attached to the air spring piston in such a manner which enables the lower end of the bellows to be disconnected from the air spring piston without damaging the crimp ring which connects the bellows to the piston.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   This invention relates to an air spring and shock absorber assembly for use in suspension systems and more particularly to an air spring and shock absorber assembly for use in vehicle suspension systems. Even more particularly, the invention relates to an air spring and shock absorber assembly wherein the lower end of the air spring bellows may be disconnected from the air spring piston without removing, i.e., destroying, the lower crimp ring or clamping ring, thereby enabling a substitute air spring piston to be installed in the assembly so that the characteristics of the assembly may be changed. 
   2. Description of the Related Art 
   Many different types of air spring and shock absorber assemblies have been previously provided for use in suspension systems such as vehicle suspension or cab suspension systems. For example, see U.S. Pat. Nos. 5,649,692; 6,443,436; and 6,715,744. Each of the assemblies of the above-identified patents includes a shock absorber and an air spring which includes an air spring bellows and an air spring piston. If it is desired to change the characteristics of the air spring and shock absorber assemblies of the prior art, the same may be achieved by replacing the air spring piston with a substitute piston which has different characteristics. 
   In U.S. Pat. No. 5,649,692, one end of the air spring bellows 21 is attached to the air spring piston (turret tube) 23 by means of a clamping ring 22b. If it is necessary to disconnect the bellows 21 from the piston 23, to enable a substitute piston to be utilized in the assembly, the clamping ring 22b must be cut or severed to accomplish the disconnection. Subsequent reinstallation of a substitute piston 23 requires that a new clamping ring be used which involves labor and material cost issues. 
   In U.S. Pat. No. 6,643,436, one end of the air spring bellows 72 is attached to the air spring piston 76 by a clamping ring 78. The assembly of U.S. Pat. No. 6,643,436 suffers the same disadvantages as set forth with respect to U.S. Pat. No. 5,649,692 discussed hereinabove. In U.S. Pat. No. 6,715,744, one end of the air spring bellows 26 is secured to the air spring piston by an unnumbered clamping or crimp ring. The assembly of U.S. Pat. No. 6,715,744 likewise faces the same disadvantages as addressed above with respect to the assembly of U.S. Pat. No. 5,649,692. 
   Another consideration in air spring and shock absorber assemblies of the prior art is that there is a pre-loading on the shock absorber end mounts which causes vibration transmission therethrough. In most assemblies of the prior art, the lifting force of the air spring is being transmitted through the shock absorber end mounts which pre-loads them with a very high force and makes noise and vibration transmission much more prevalent. 
   SUMMARY OF THE INVENTION 
   An air spring and shock absorber assembly for use in a suspension system such as a vehicle suspension systems or a cab suspension system is disclosed and comprises a shock absorber and an air spring. The shock absorber includes a body having upper and lower ends and an exterior surface with the body having at least one projection extending outwardly therefrom above its lower end. A base end mount is provided on the lower end of the body and a rod end mount is provided on the upper end of the piston rod which extends upwardly from the body. Damping means is provided in the body for yieldably resisting movement of the piston rod with respect to the body. 
   The air spring includes an end cap which is positioned above and which is operably secured to the rod end mount of the shock absorber. The air spring includes a flexible bellows having upper and lower ends with the upper end of the bellows being sealably secured to the end cap. The air spring also includes an air spring piston which has upper and lower ends with the piston having a central bore extending therethrough between its upper and lower ends. The piston also has a reduced diameter portion at its upper end. The shock absorber body is received by the central bore in the piston with at least one projection on the shock absorber body engaging the lower end of the piston to prevent downward movement of the air spring piston with respect to the shock absorber body. 
   At least one O-ring seal is provided in the central bore of the piston which is in sealing engagement with the exterior surface of the body of the shock absorber. The piston also has an air passageway extending thereinto which is in communication with the central bore thereof above the O-ring seal with the air passageway being in communication with a source of pressurized air. A resilient O-ring, having inner and outer surfaces, is positioned on the reduced diameter portion of the piston. The lower end of the bellows embraces the resilient O-ring and a lower crimp ring secures the lower end of the bellows to the resilient O-ring. 
   The resilient O-ring permits the resilient O-ring, the lower end of the bellows and the lower crimp ring to be selectively disconnected, as a unit, from the air spring piston to permit the piston to be replaced by a substitute piston and to reinstall the resilient O-ring, lower end of the bellows and the lower crimp ring, as a unit, onto the substitute piston. 
   The rod end mount at the upper end of the piston rod is configured in such a way that when the assembly is static, there is no pre-load on the rod end mount. 
   It is therefore a principal object of the invention to provide an improved air spring and shock absorber assembly. 
   Still another object of the invention is to provide an air spring and shock absorber assembly including a novel means for connecting the lower end of the air spring bellows to the upper end of the air spring piston so that the piston may be removed from the assembly and substituting a different piston without destroying the lower crimp ring which connects the bellows to the piston. 
   Still another object of the invention is to provide an air spring and shock absorber assembly wherein the rod end mount is configured in such a way that when the component is static, there is no pre-load on the rod end mount. 
   It is a further object of the invention to provide an air spring and shock absorber assembly which permits the air spring piston to be easily exchanged for a piston with a different profile yielding a different spring rate. 
   These and other objects will be apparent to those skilled in the art. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view of the air spring and shock absorber assembly of this invention; 
       FIG. 2  is a sectional view of the assembly of this invention; 
       FIG. 3  is an exploded perspective view of the assembly of this invention; and 
       FIG. 4  is a partial sectional view illustrating the manner in which the air spring bellows, O-ring and crimp ring are removable, as a unit, from the air spring piston. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   The numeral  10  refers to the air spring and shock absorber assembly of this invention which is designed for air-suspended vehicles or for vehicle cab suspensions. One end of the assembly is operably secured to the vehicle frame with the other end thereof operably secured to the vehicle axle or control arm associated therewith if the assembly is used in a vehicle suspension system. If the assembly is used in a vehicle cab suspension, one end of the assembly will be secured to the vehicle cab and the other end will be secured to the frame of the vehicle. 
   Assembly  10  includes a conventional shock absorber  12  having a body  14  which has a base end mount  16  provided at the lower or base end thereof. Mount  16  includes a conventional rubber or resilient bushing  18  having a metal sleeve  20  positioned thereon. The outer surface of body  14  has a plurality of radially spaced-apart protrusions or projections  22  extending outwardly therefrom above the base end thereof. Rod  24  slidably extends from the upper end of body  14  and has a rod end mount  26  provided on the upper end thereof. Mount  26  includes a conventional rubber or resilient bushing  28  mounted thereon having a metal sleeve  29  positioned therein. Shock absorber  12  includes conventional damping means contained within body  14  to yieldably urge rod  24  upwardly from body  14  and to yieldably resist the downward movement of rod  24  into body  14 . 
   Clevis  30  is mounted on rod end mount  26  and includes a top plate  32  having ears or clevis elements  34  and  36  extending downwardly therefrom. Bolt or pin  38  extends through the ears  34 ,  36  and sleeve  29  to connect the clevis  30  to the rod end mount  26 . Plate  32  as a central opening  40  formed therein which receives the threaded shank  42  of bolt  44  extending therethrough. As seen, the head  46  of bolt  44  is positioned below plate  32 . 
   The numeral  48  refers to the air spring portion of assembly  10  which includes a piston  50  and a flexible bellows  52 . Piston  50  includes an upper end  54 , lower end  56 , an outer bellows roll-out surface  58  and a central bore  60  extending between the upper and lower ends of the piston. The upper outer surface of piston  50  is provided with a reduced diameter portion  62  defined by shoulder  64  at the lower end thereof. Air passageway  66  extends upwardly and downwardly through piston  50  to central bore  60 . Piston  50  has an annular recess or groove  68  formed therein at the lower end of bore  60  which is adapted to receive a metal O-ring  70  therein. Piston  50  is also provided with a pair of vertically spaced, annular grooves or recesses  72  and  74  formed therein above recess  68  which are adapted to receive resilient O-ring seals  76  and  78  therein, respectively. 
   As seen, shock absorber  12  is inserted upwardly through bore  60  of piston  50  until the projections  22  on body  14  engage the metal O-ring  70  which limits further upward movement of shock absorber  12  with respect to piston  50 . The O-ring seals  76  and  78  sealably engage the exterior surface of body  14  of shock absorber  12  to prevent the passage of air thereby. 
   The numeral  80  refers to a metal or plastic end cap which includes a disc-shaped upper end  82  having an annular skirt  84  extending downwardly therefrom inwardly of the periphery of upper end  82 . The outer surface of skirt  84  is preferably provided with a recessed portion  86  above the lower end thereof which has protruding ridges. The upper end of bellows  52  is positioned in recessed portion  86  and is secured to skirt  84  of end cap  80  by a conventional crimp ring  88 . 
   A resilient O-ring  90  is mounted on reduced diameter portion  62  of piston  50  and has its lower end  92  in engagement with shoulder  64  of reduced diameter portion  62 . The outer surface of O-ring  90  has an annular recessed portion  94  formed therein which preferably has annular ridges projecting therefrom. The lower end of bellows  52  is received by recessed portion  94  of O-ring  90  and is secured to O-ring  90  by a conventional crimp ring  96 . 
   Bolt  44  extends upwardly through opening  98  in end cap  80  to secure the clevis  30  to end cap  80 . Bolt  44  is also designed to secure the end cap  80  and the assembly  10  to the vehicle frame or cab. The base end mount  16  will be operably secured to the vehicle axle or a control arm operably connected thereto or to the frame of the vehicle. 
   When it is desired to change the piston  50  in the assembly  10  to change the characteristics of the assembly  10 , the end cap  80  and the base end mount  16  will normally be disconnected from the vehicle. The lower end of bellows  52  and the resilient O-ring  90  and crimp ring  96  are then pulled off the reduced diameter portion  62  of piston  50  together, which is made possible by the resilient O-ring  90  and which is accomplished without removing or cutting the crimp ring  96 . A new piston, having the desired characteristics is then substituted for the removed piston. The O-ring  90  having the lower end of the bellows  52  maintained thereon by the crimp ring  96  is then slipped onto the reduced diameter portion  62  of the new piston  50 . The assembly  10  is then secured to the vehicle as previously described. Although it has been described and preferred that the O-ring  90  stays with the bellows  52  and the crimp ring  96  during the disconnection of the piston  50  from the bellows  52 , it is possible that the bellows  52  and the crimp ring  96  may be removed from the piston without removing the O-ring  90  from the piston  50 . 
   Thus it can be seen that the invention accomplishes at least all of its stated objectives.