Abstract:
A height adjustable seat suspension having first and second bases connected by a linkage assembly with an air spring and shock disposed between the bases. The shock dampens vertical movement of the bases and the air spring increases in air volume to raise the seat height of the suspension and decreases in air volume to lower the seat height of the suspension. A threaded rod is also included as part of the shock which is threadably engaged with a collar that is rotated by a drive source. The engagement between the threaded portions of the rod and collar axially repositions the rod with respect to said collar to change the effective length of, the shock.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    The present invention relates to seat suspensions and, more particularly, to a unique height adjustment mechanism that allows the height of a seat suspension to be adjusted while maintaining consistent shock dampening. The present invention uses a small output electric motor that operates a valve which, in turn, controls the air volume inside an air spring, thereby adjusting the height of the suspension.  
         SUMMARY OF THE INVENTION  
         [0002]    In one embodiment of the present invention, a shock absorber or dampener is provided which uses a drive to adjustably control the effective axial length of the shock in order to accommodate a plurality of seat heights. The length of the shock is adjusted by providing threads on a rod that forms part of the shock assembly which coact with threads associated with the drive source. The operation of the drive and subsequent coaction between the threads causes the rod to thread axially changing the effective length of the rod and the overall length of the shock.  
           [0003]    In another embodiment of the present invention, an actuator is further provided with the device. The actuator moves axially in conjunction with the rod and is used to adjust the height of a seat suspension. As the actuator moves axially, it operates a valve that controls air flow into and out of the air spring. The actuator causes air to flow into the spring to increase the seat height and exhausts air to decrease the seat height. 
       
    
    
     DESCRIPTION OF THE DRAWINGS  
       [0004]    These and other features, objects and advantages of the present invention will become apparent from the following description and drawings wherein like reference numerals represent like elements in several views, and in which:  
         [0005]    [0005]FIG. 1 is a side view of one embodiment of the present invention;  
         [0006]    [0006]FIG. 2 is an exploded perspective view of a shock absorber used with the embodiment shown in FIG. 1;  
         [0007]    [0007]FIG. 3 is cross-sectional view of the shock absorber shown in FIG. 2;  
         [0008]    [0008]FIG. 4 is a side view of the embodiment shown in FIG. 1 in multiple height adjustments;  
         [0009]    [0009]FIG. 5 is a side view of an alternate embodiment of the present invention using a scissors-type seat suspension shown in an extended position;  
         [0010]    [0010]FIG. 6 is a side view of the embodiment shown in FIG. 5 in a lowered position;  
         [0011]    [0011]FIG. 7 is a side view showing actuation of a valve stem of the present invention; and  
         [0012]    [0012]FIG. 8 is a side view showing the actuation of another valve stem of the present invention.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0013]    Set forth below is a description of what are currently believed to be the preferred embodiments or best examples of the invention claimed. Future and present alternatives and modifications to the preferred embodiments are contemplated. Any alternates or modifications having insubstantial changes in function, in purpose, in structure or in result are intended to be covered by the claims of this patent.  
         [0014]    As shown in FIG. 1, seat suspension  10  may consist of a parallelogram seat assembly  20 , the design of which is known to those of skill in the art. As shown, assembly  20  consists of a first support base  22  and opposingly located support base  24 . Bases  22  and  24  are connected by a linkage assembly consisting of two sets of arms  26  and  28  which, together, form the general parallelogram assembly  20 .  
         [0015]    The present invention may also work with other known seat suspensions as well. As shown in FIGS. 5 and 6, the present invention may also be used with a scissors-type seat suspension.  
         [0016]    Disposed between bases  22  and  24  is an air suspension spring  30 . Spring  30  is a bladder or bag, with the volume of air inside the spring setting the height of the seat suspension by controlling the distance between bases  22  and  24 . The air used to operate spring  30  is supplied from a compressor typically located remotely from the seat on the piece of equipment or vehicle. The design, construction, and use of spring  30  are also well known to those of ordinary skill in the art and a spring manufactured by Firestone may be used with the present invention.  
         [0017]    Attached to bases  22  and  24  is dampener  40  which functions as a shock absorber which restricts the vertical movement of bases  22  and  24 . In one embodiment, the dampener may be a fluid-based system such as a hydraulic dampener manufactured by Tenneco. Of course, other types of dampeners or shock absorbers may also be used with the present invention such as spring, air and other dampening systems known to those of skill in the art.  
         [0018]    Dampener  40  is affixed to base  22  by mount  42  and to base  24  by mount  44 . In general, dampening is achieved by the depression of plunger  46  which forces a fluid through a restrictive orifice located inside dampener  40 . A rubber bumper  45  is located on plunger  46  which acts as a shock absorber and stop.  
         [0019]    Mounted to dampener  40  is air supply control valve  50  which controls the air volume inside air spring  30 . As shown, value  50  may be mounted to dampener  40  by U-bolt  52 , bracket  53 , and fasteners  54 . Valve  50  is in communication with both air spring  30  and the air supply compressor located on the equipment or vehicle. Valve  50  has an exhaust port  56  which exhausts air from spring  30 ; an air supply port  57 , which supplies air to spring  30  via a hose (not shown); and an inlet port  58 , which is connected to the air supply through the use of a hose.  
         [0020]    Extending outwardly from valve  50  are two valve stems  60  and  62 , which control the volume of air in spring  30 . When valve stem  60  is depressed, air is added to spring  30  via port  57 . When valve stem  62  is extended, air is exhausted from spring  30  via port  56 . When valve stems  60  and  62  are in a neutral position, air is not added to or exhausted from spring  30 .  
         [0021]    The operation of valve  50  is controlled by actuator  66  which is connected to anti-rotator sleeve  70 . Disposed within sleeve  70  through aperture  72  is extension rod  80  which is affixed to or extends from plunger  46  and is also secured to sleeve  70  to further form part of the shock assembly. As is also shown in FIG. 3, extension rod  80 , bumper  45  and plunger  46  may be located within interior  74  of sleeve  70 . An elongated groove or track  76  is further located on sleeve  70  and is sized to slidingly receive boss  43  located on the outer housing of valve  40 .  
         [0022]    As shown in FIGS. 3 and 4, an electric motor  90  is used to adjust the effective length of shock  40  by controlling the length of rod  80 . As shown in FIGS. 1 and 4, motor  90  may be mounted to suspension  10  by fasteners  91 , block  103 , or by other fastening or mounting means known to those of skill in the art.  
         [0023]    To change or adjust the length of rod  80 , and consequently shock  40 , gear assembly  94  includes an elongated aperture  95  sized to receive rod  80  and a collar  96  which includes internal threads  97  which threadably engage threads  82  on rod  80 . Threads  97  may be formed directly on collar  96  or be part of an internal sleeve  99  which is secured to collar  96  by pin  113 . The coaction between threads  97  and  82  causes rod  80  to travel axially. FIG. 4 shows how the length of rod  80  is changed to accommodate various seat heights.  
         [0024]    In another embodiment, the seat suspension used may be a scissors-type seat suspension which is shown in FIGS. 5 and 6. The design, construction, and operation of this type of seat suspension are generally described in U.S. Pat. Nos. 4,856,763 and 5,580,027, which are incorporated herein by reference. As shown, seat suspension  200  includes a linkage assembly consisting of scissor arms  210  and  212  which are connected to opposingly located base sections  220  and  222 . The other components making up the height adjustment system are incorporated into suspension  200  in the manner described above. Again, as shown in FIGS. 5 and 6, the length of rod  80  is changed to accommodate various seat heights.  
         [0025]    In use, the present invention uses a small output drive such as an electrical motor  90  to change the length of the shock to accommodate a wide variety of seat heights. It has also been found that the small output drive source may also be used to control the height of the seat by controlling the amount of air either inputted to or exhausted from air spring  30 . For example, to accommodate a lower seat height, the effective length of rod  80 , as well as the overall length of shock  40 , must be decreased. To accomplish this, collar  96  is rotated in the appropriate direction which causes a portion of rod  80  to thread axially into aperture  95  of collar  96  by having collar  96  be threadably engaged with threads  82  on rod  80 . As rod  80  travels axially into collar  96 , sleeve  70  moves axially as well. In turn, actuator  66  moves axially toward base section  22  which moves actuator  66  out of a neutral position with respect to stems  60  and  62 . More specifically, stem  60  remains inactive since it must be depressed to add air to spring  30 . However, actuator  66  activates stem  62  by pulling it toward base  22  through the use of fastener  101 . This exhausts air from air spring  30  until, by movement of base section  22  downwardly, actuator  66  is returned to its neutral position which deactivates valve stem  62  and terminates the exhaustion of air from spring  30 .  
         [0026]    To raise the height of seat suspension  10 , motor  90  is activated and the rotation of internal threads  97  and the coaction with threads  82  cause the effective length of rod  80  to increase. As the effective length of the rod increases, sleeve  70  axially moves toward base  24  and so does actuator  66 . This, again, moves actuator  66  out of a neutral position, depressing valve stem  60  which causes air to flow into spring  30  thus increasing its volume and the height of the seat suspension. As air volume is added, actuator  66  moves back into a neutral position which terminates the operation. Valve stem  62  and fastener  101  are unaffected since they will have traveled through aperture  104  located on actuator  66  during this operation.  
         [0027]    Alternatively, threads  97  may remain fixed or anti-rotational, and rod  80  may be rotated by the drive source to provide the desired length adjustment.  
         [0028]    One advantage of the invention is that the effective length of the shock may be changed to accommodate changes in seat height. As described, this is accomplished by coacting threads  82  and  97  and the use of the small output drive  90 .  
         [0029]    Another advantage of the present invention is that changes in the length of shock  40  may also be used to operate air spring  30 . This allows spring  30  to perform most of the work of actually adjusting the height of the suspension.  
         [0030]    Consistent dampening is also maintained with the present invention. Once the adjustment is made to the length of rod  80  and shock  40 , the length of plunger  46 , while temporarily changed, will return to its optimal stroke at the center of the ride zone once a neutral position is re-obtained by the action of the air spring.  
         [0031]    In addition, the adjustment system also provides an ability to preset the seat height. By maintaining the proper spacial relationship between the length of rod  80  as it corresponds to a particular air volume and seat height, each time the air supply is activated, the suspension will return to the previously preset height once a neutral position is re-established.  
         [0032]    While the invention has been described with reference to the preferred embodiments thereof, it will be appreciated that numerous variations, modifications, and alternate embodiments are possible, and accordingly, all such variations, modifications, and alternate embodiments are to be regarded as being within the spirit and scope of the invention.