Patent Publication Number: US-2003227118-A1

Title: Single point attachment dual path suspension mount

Description:
TECHNICAL FIELD OF THE INVENTION  
       [0001] This invention relates generally to a damper mount assembly, and relates more particularly to a single point attachment mount assembly for vehicle suspension dampers.  
       BACKGROUND OF THE INVENTION  
       [0002] The typical vehicle suspension includes a damper in the form of a strut or a shock that is mounted between the sprung (body), and unsprung (wheel assembly) masses of the vehicle to dampen spring oscillations. The lower end of the damper is connected to the wheel assembly in a suitable manner, and the upper end is connected to the body structure of the vehicle body, usually at a tower, by an upper damper mount assembly. With conventional upper mounts, a coil spring supports the weight of the vehicle and creates a force that is proportional to the relative velocity between the wheel of the vehicle and the body, transferring loads to the mount. In addition, a jounce bumper acts as a stop for compression directed movement of the damper transferring loads to the mount. Since the damper is connected to the body by the upper mount, the upper mount must support the total weight of the vehicle and provide acceptable isolation. Achieving these properties requires proper tuning of the mount. Tuning is complicated by the fact that relatively high spring and jounce bumper loads have to be accommodated through the mount.  
       [0003] Conventional upper mounts include at least one resilient element, normally a rubber cushion, to isolate and reduce the transmission of input forces to the body. An upper mount is generally required to be firm enough to support the weight of the body while simultaneously resilient enough for isolation purposes. For certain inputs, deflection of the upper mount is desirable while for other inputs it is preferable for the upper mount to resist deflection. Single path upper mounts are known, wherein the actuator or damper rod and a coil spring seat are fastened together and the load path is through a single rubber cushion. The single rubber cushion accommodates the forces generated by both the actuator or damper and the cooperating coil spring. The rubber cushion is preloaded by the vehicle&#39;s weight. Dual path mounts are also known, wherein the actuator or damper rod and the coil spring seat are not fastened together and wherein the load path is through separate rubber cushion assemblies. A first rubber cushion assembly engages the coil spring and supports the vehicle&#39;s weight, and a second rubber cushion assembly engages the actuator or damper rod and is not preloaded by vehicle weight.  
       [0004] The conventional upper mount assembly is attached to the tower by a plurality of fasteners that are distributed around the mount near its outer perimeter. It is also known to secure the mount to the tower by placing components of the mount on opposite sides of the tower and capturing them by a nut threaded to a piston rod tenon of the damper. U.S. Pat. No. 6,161,822, the disclosure of which is hereby incorporated by reference, shows a similar single point attachment mount.  
       SUMMARY OF THE INVENTION  
       [0005] The present invention is a mount assembly for connecting a damper rod to a motor vehicle tower. The mount assembly comprises a mount housing, a nut, and a resilient cushion. The mount housing has a vertical portion extending through an opening in the tower, and a flange disposed on one side of the tower. The nut is disposed on a side of the tower opposite the one side, and is engaged with the vertical portion of the mount housing. The resilient cushion is disposed within the vertical portion of the mount housing, the damper rod extending through the resilient cushion assembly. A spring engaged with the tower is adapted to transfer loads from the motor vehicle to the tower.  
       [0006] Accordingly, it is an object of the present invention to provide a mount assembly of the type described above that attaches to the tower at a single point.  
       [0007] Another object of the present invention is to provide a mount assembly of the type described above that accepts damper loads in shear.  
       [0008] Still another object of the present invention is to provide a mount assembly of the type described above that reduces product and assembly costs by the elimination of redundant fasteners as well as improved cycle time due to the reduction of repeated fastening actions on the assembly line.  
       [0009] Still another object of the present invention is to provide a mount assembly of the type described above that provides separate paths for vehicle loads and damper loads.  
       [0010] The foregoing and other features and advantages of the invention will become further apparent from the following detailed description of the presently preferred embodiments, read in conjunction with the accompanying drawings. The detailed description and drawings are merely illustrative of the invention rather than limiting, the scope of the invention being defined by the appended claims and equivalents thereof.  
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0011]FIG. 1 is a cross-sectional view of a suspension mount assembly according to the present invention attached to a damper and a tower of a motor vehicle; and  
     [0012]FIG. 2 is an exploded view of the suspension mount assembly. 
    
    
     DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS  
     [0013]FIGS. 1 and 2 show one embodiment  10  of an upper suspension mount assembly for connecting a damper rod  11  to a vehicle body tower  12 . In general, the mount assembly  10  is rigidly attached to the tower  12  at a single point, by trapping the tower between a flange  13  on mount housing  14  and a nut  15  engaged with external threads on a vertical portion  16  of the mount housing. In operation, the damper rod  11  is free to move relative to the tower  12 , but no relative movement is intended between the mount housing  14  and the tower. This preferred illustrated embodiment provides for two separate load paths through the mount assembly  10 . The loads created by the damper, and transmitted from the damper rod  11 , pass through a resilient cushion assembly  18  to the vehicle tower  12 . Other loads transmitted to the mount assembly  10 , such as those that might be transmitted by the vehicle through a spring  20 , pass through a spring seat  22  and a bearing  24  to the mount housing  14  and the vehicle tower  12 .  
     [0014] The tower  12  is normally an inverted cup-shaped element with an annular sidewall, and is formed as part of a vehicle body stamping in a well-known manner. In a preferred embodiment the tower  12  is round or circularly shaped, and the mount assembly  10  is correspondingly shaped for mating reception therein so that no specific initial angular orientation of the mount assembly relative to the tower is required for assembly. The mount assembly  10  can of course adopt alternate shapes, such as oval or oblong, that may present some advantages in specific applications such as allowing the mount to have performance differentials (tunability) in the different motion directions of the vehicle suspension.  
     [0015] A lower rate washer  26  is preferably formed of an acceptably rigid material such as metal, and includes a shoulder  28  around an opening  30 . The damper piston rod  11  abuts the shoulder  28 , and a tenon  32  of the rod extends through the opening  30 . A nut  34  is threadingly engaged with the upper portion of the tenon  32  to compress and capture the cushion assembly  18  between an upper rate washer  36  and the lower rate washer  26  and within the mount housing  14 . The cushion assembly  18  may optionally or additionally be bonded by well known processes to the support surfaces of those components.  
     [0016] The cushion assembly  18  is preferably formed of an elastomer that provides a selected level of damping between the damper rod  11  and the tower  12 . To facilitate proper fit and positioning of the cushion assembly  18  relative to the damper rod  11 , the upper rate washer  36  and the lower rate washer  26  may be provided with fingers  38  and  40 , respectively, that engage the cushion assembly. The shape of the cushion assembly  18  and its physical properties may be altered as necessary to enhance performance of the mount assembly  10  in a manner known in the art. Through this structure, the damper piston rod  11  moves relative to the tower  12  by means of deflection of the elastomeric cushion  18 .  
     [0017] Attachment is accomplished by means of a single point connection by virtue of the nut  15  being threaded onto external threads on the mount housing  14 . No other fasteners are required to attach the mount assembly  10  to the vehicle tower  12 . The nut  15  may also provide the optional feature of serving as a simple camber and caster adjustment mechanism in the associated vehicle suspension system.  
     [0018] Accordingly, an upper mount assembly is provided that is relatively easily attached to the tower of the motor vehicle, includes relatively few individual components, and exhibits tuning and packaging flexibility. Attachment to the vehicle tower is accomplished through a single point type connection system that advantageously expedites assembly of the associated vehicle suspension system. The upper mount is rigidly attached to the vehicle body by trapping the vehicle&#39;s tower between two rigid components of the mount while the damper rod tenon is free to move relative to the clamping members of the mount and relative to the tower, while preferably no relative movement occurs between the clamping members of the mount and the tower. Additionally, damper loads are accepted in shear, while a separate path is provided for the vehicle loads.  
     [0019] While the embodiment of the invention disclosed herein is presently considered to be preferred, various changes and modifications can be made without departing from the spirit and scope of the invention. The scope of the invention is indicated in the appended claims, and all changes that come within the meaning and range of equivalents are intended to be embraced therein.