Abstract:
An articulating vehicle ( 10 ) includes a front axle ( 21 ) operatively connected to a front frame ( 40 ) and a rear axle ( 21 ) is operatively connected to the rear frame ( 30 ). A torsional joint ( 50 ) has an inner shaft member ( 51 ) operatively connected one of the frames and an outer hollow member ( 52 ) operatively connected to the other of the frames. An elastomeric material ( 53 ) is positioned between the inner member ( 51 ) and outer member ( 52 ). The elastic material ( 53 ) connects the inner and outer members, whereby the frames may rotate relative to each other along the longitudinal axis as the elastomeric member ( 53 ) is compressed and resiliently resists rotation between the frames ( 30  and  40 ). A torsional energy absorption suspension is provided for one of the wheels. The suspension includes a torsional joint ( 50 ), a single A-frame member ( 94 ). A lever arm ( 95 ) may also be utilized to vary the preload on the torsional joint ( 50 ).

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to a suspension for a vehicle, and more particularly to a utility vehicle which utilizes a torsional energy-absorbing member and also may utilize a torsional joint to make the vehicle articulating. 
     2. Description of the Prior Art 
     Utility vehicles for use in agricultural, lawn and golf course maintenance fields typically travel directly upon the turf surface being maintained. Such vehicles must often support a substantial weight on a frame. Inherent in such applications is the need to travel over uneven terrain, freshly watered grass or recently planted soil. Obstacles such as shrubbery, sand traps and trees are also often encountered. 
     Utility vehicles of this type are often used to apply fertilizer, pesticides or other surface treatment to turf being maintained. In order to prevent damage to the turf and to promote safety while turning in off-road environents, maximum speed of many utility vehicles is limited to approximately 15-25 miles per hour. Unfortunately, this encourages the tendency to drive at maximum speed under most conditions, including going over and around obstacles. 
     It is preferable that scuffing of the turf or soil does not occur while the vehicle is in motion. Despite the terrain, it would be advantageous to keep all four wheels on the ground. This would help maintain the traction of the vehicle, increase the vehicle&#39;s stability and maintain constant ground pressure. Simply suspending the wheels from the axle does not provide sufficient latitude as the terrain is often more uneven than the suspension system is able to compensate for. Further, the suspension systems are quite complex and there are a number of parts that may wear as the vehicle is continually used. 
     Another important consideration when designing a utility vehicle is the ride and comfort of the driver and passenger. Typically, past utility vehicles have had the cab of the utility vehicle connected to the rear frame in such a manner that movement of the rear wheels is transferred to the cab in which the operator sits. 
     The present invention addresses these problems and provides for a utility vehicle with a torsional suspension system which is less complex and requires less maintenance. Further, the vehicle may articulate along its longitudinal axis and also provides for a utility vehicle which separates the motion of the rear wheels from the passenger cab. 
     SUMMARY OF THE INVENTION 
     The present invention is a torsional energy suspension for a utility vehicle having a wheel. The suspension includes a torsional energy absorption member having an inner shaft member, an outer hollow member an elastomeric material operatively connecting the inner and outer members. An A-frame has a first end operatively connected to a wheel and a second wheel operatively connected to one of the members, the other of the members operatively connected to the frame. A lever arm has a first end connected to the other of the members and a second end adapted to be connected to the frame. The second end of the lever arm is adapted to be secured in a plurality of positions on the frame, wherein a varying preload may be created by simply securing the lever arm to a different position. 
     The invention is also a torsional energy absorption suspension for a utility vehicle having a frame, wheel and longitudinal axis. The suspension includes a torsional energy absorption member having an inner shaft, an outer hollow member and an elastomeric material operatively connecting the inner and outer members. The absorption member has a longitudinal axis which extends generally from the front of the vehicle to the rear of the vehicle. An A-frame has a first end operatively connected to a wheel and a second end operatively connected to one of the members, the other of the members operatively connected to the frame. The A-frame consisting essentially of a single member. 
     The invention is also a utility vehicle having a longitudinal axis. A front axle is operatively connected to the front frame and a rear axle is operatively connected to a rear frame. A torsional energy absorption member has an inner shaft member, an outer hollow member, and an elastomeric material operatively connecting the inner and outer members. An A-frame has a first end operatively connected to a wheel and a second end operatively connected to one of the members, the other of the members operatively connected to a frame. A lever arm has a first end operatively connected to the other of the members and a second end adapted to be connected to the frame. The second end of the lever arm is adapted to be secured in one of a plurality of positions on the frame, wherein a varying preload may be created by simply securing the lever arm to a different position. In a preferred embodiment, the vehicle also includes a torsional joint having an inner shaft member operatively connected to one of the frames and an outer hollow member operatively connected to the other of the frames. An elastomeric material is positioned between the inner and outer members of the torsional joint. The elastomeric material operatively connects the inner and outer members, whereby the frames may rotate relative to each other along the longitudinal axis as the elastomeric member is compressed and resiliently resists rotation between the frames. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of the utility vehicle of the present invention; 
     FIG. 2 is a perspective view of the rear of the vehicle of FIG. 1 with the payload platform removed; 
     FIG. 3 is a front-end view of the vehicle of FIG. 1 showing the rear axle having its right side lowered; 
     FIG. 4 is a front elevational view of the vehicle shown in FIG. 1 on level ground; 
     FIG. 5 is a front elevational view of the vehicle shown in FIG. 1 with the rear axle having its left end lowered; 
     FIG. 6 is a perspective view shown generally from the front left of the frame of the vehicle of FIG. 1; 
     FIG. 7 is a perspective view of the frame of the vehicle shown in FIG. 1 shown generally from the left rear; 
     FIG. 8 is an enlarged perspective view shown generally from above of the suspension member of the vehicle shown in FIG. 1; 
     FIG. 9 is an enlarged perspective view of the suspension shown in FIG. 8, shown generally from in front; 
     FIG. 10 is an enlarged cross-sectional view of the torsional joint used in the vehicle shown in FIG. 1; 
     FIG. 11 is a perspective view of the torsional joint used in the vehicle shown in FIG. 1; 
     FIG. 12 is a perspective view of the suspension member used in the vehicle shown in FIG. 1; 
     FIG. 13 is an enlarged cross-sectional view of the torsional suspension member shown in FIG. 11; and 
     FIG. 14 is a top plan view of the torsional joint used in the vehicle shown in FIG.  1 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to the drawings, wherein like reference numerals represent like parts throughout the several views, there is generally shown at  10  a utility vehicle. The vehicle  10  includes a cargo bed or payload platform  11 . The payload platform  11  is operatively connected to a rear frame  30 , which will be described more filly hereafter. The payload platform  11  may be secured to the rear frame  30  by suitable means such as bolts and nuts, welding or other means well known in the art. Preferably the platform is hinged to allow for dumping. An operator platform  12  is operatively connected to a front frame  40 , which will be more fully described hereinafter. The operator platform  12  is suitably connected by bolts and nuts, welding or other means well known in the art to the front frame  40 . Positioned on and carried by the operator platform  12  is a passenger seat  13  and operator seat  14 . A front hood and fender assembly  15  is also operatively carried by the front frame  40 . A prime mover, such as an internal combustion engine  16  is mounted to the rear frame  30  and drives, in this case, rear wheels  17 . The front wheels  18  could also be driven, and the present invention is applicable for use in conjunction with either the rear wheels or the front wheels, regardless of whether the vehicle is front-wheel, rear-wheel or all-wheel drive. Steering of the vehicles controlled by conventional manipulation of a steering wheel  19  which is connected to a steering column  20 . 
     The rear frame  30  is preferably a single-piece weldment having left side  30   a,  rear section  30   b,  right side  30   c  and front member  30   d.  The left side  30   a  has an aperture  30   e  formed therein through which a muffler (not shown) is positioned. The axle  21  is operatively connected to the frame  30  by mounting member  31  which is welded to the axle  21  at one end and secured to the right side  30   c  by suitable means such as bolts and nuts  32 . A similar mounting member (not shown) is utilized to secure the axle  21  to the left side  30   a.  As previously described, the payload platform  11  is operatively connected to the top of the frame  30 . As shown in FIG. 1, the payload platform  11  includes a generally planar bed with three vertical sides. However, any suitable platform may be utilized. As previously stated, the platform is preferably hinged to provide for dumping. 
     The front frame  40  includes a longitudinal beam  45  which has a back frame member  43  welded thereto. The back frame member  43  is generally perpendicular to the longitudinal beam  45 . Welded to the top of the longitudinal beam  45  is a floor board  41 . 
     Referring to FIGS. 6,  7  and  11 , there is shown a torsional joint, generally designated at  50 . The torsional joint  50  connects the rear frame  30  to the front frame  40  along the center longitudinal axis of the vehicle  10 . The torsional joint  50  includes an inner shaft member  51  and an outer hollow member  52 . An elastomeric material  53  is positioned between the inner member  51  and outer member  52 . The elastomeric material  53  operatively connects the inner member  51  to the outer member  52 . As shown in FIG. 10, there are four elastomeric members  53 . However, it is understood that the elastomeric members  53  may also take other configurations, such as completely surrounding the inner member  51 . Such torsional members are known in the art, such as those described in U.S. Pat. No. 3,545,737. As will be described more fully hereafter, the inner shaft member  51  has a generally rectangular cross-section throughout its midsection, where it is in contact with the elastomeric material  53 . At its ends are formed a first cylindrical shaft  51   a  and a second cylindrical shaft  51   b.  Plastic bearings (not shown) may be positioned between the shafts  51   a  and  51   b  and the outer member  52  to keep the inner shaft  51  concentric with the outer member  52 . The shafts  51   a  and  51   b  are rigidly secured to the midsection of the inner shaft  51  and preferably are integral one-piece portion of the shaft member  51 . The cylindrical ends  51   a  and  51   b  are utilized to more easily mount the torsional joint  50 . As shown in FIG. 10, the inner shaft member  51  and outer hollow shaft member  52  have a generally rectangular cross-section and preferably a square cross-section. 
     The joint  50  is operatively connected to the front frame by a yoke  55  at one end and a support structure  60  at its other end. The yoke  55  includes a right side plate  55   a  and a left side plate  55   b.  A plate  55   c  is welded between the two side plates  55   a  and  55   b.  The yoke  55  is welded to the beam  45 . Four bolt openings are formed in the back plate  55   c.  Also, the plate  55   c  at its top end has an opening which is sized slightly larger than the outer hollow member  52 . A mounting plate  56  has four bolt openings formed therein. The bolt openings are in alignment with the bolt openings formed in the back plate  55   c.  A central aperture is formed in the mounting plate  56  and the shaft  51   b  is welded in the aperture. The plate  56  is mounted to the back plate  55   c  through the bolt holes by bolts and nuts (not shown). The support structure  60  includes a right plate  61  and a left plate  62 . Both plates have two holes formed therein which are in alignment with two holes formed in the front member  30   d  of the rear frame for attachment by bolts and nuts (not shown). First and second arms  63  and  64  extend from the plates  61  and  62  at one end and are secured at the other ends, to the outer hollow member  52 . A back member  65  extends between the plates  61  and  62  and has a central section which is connected to the end of the outer hollow member  52 . The central section of the back member  65  has an opening through which the shaft  51   a  extends. The opening is large enough so that there is no interference between the back member  65  and the rotational movement of the shaft  51   a.  The outer hollow member  52  and support structure  60  are preferably formed as a single casting. Alternately, the components may be connected by suitable means such as welding. The back plates  61  and  62  are secured by bolts and nuts (not shown) to the front member  30   d.  This connects the outer hollow member  52  to the rear frame while the inner shaft member  51  is connected to the front frame. Additional support for the inner shaft member  51  is provided by a plate  69  which extends upward from the back of the rear member  43  and is welded thereto. The plate has an aperture which is sized and positioned to accept the shaft  51   a.    
     In viewing FIG. 14, it can be seen that the shaft  51   a  has a reduced diameter at its end. This is useful in nesting the shaft  51   a  in the frame. The reduction in diameter is what is supported by the plate  69 . Further, a bore  51   c  is formed in the shaft  51 . The bore  51   c  is sized to accept a bolt which extends through the plate  69  and further secures the shaft  51   a  to the front frame. The bosses  68  are formed in the outer hollow member  52  for possible additional use of providing guides for electrical wires and the like. 
     While the present invention has been described with respect to the outer hollow member  52  being connected to the rear frame and the inner shaft member  51  connected to the front frame, it is understood that one skilled in the art could reverse this so that the outer hollow member was connected to the front frame and the inner shaft member  51  connected to the rear frame. 
     Connected to the front portion of the beam  45  is a housing, generally designated at  70 . The housing includes a rear member  71  connected to an inclined top member  72  which is in turn connected to a front member  73 . The rear member  71  has two apertures  71   a  for mounting a torsional suspension member  90 , which will be described in more detail hereafter. Two arcuate slots  71   b  are also formed at the bottom of the rear member  71  and are positioned proximate each side of the beam  45 . The front member  73  also has two apertures  73   a  for mounting the torsional suspension member  90 . 
     The utility vehicle  10  includes a suitable steering mechanism, such as the one shown in FIGS. 8 and 9. However, it is understood that other suitable mechanisms may be utilized. The steering of the utility vehicle  10  is provided by a steering gear  79  which has an input shaft  79   a  which is operatively connected to the steering column  20  by means well known in the art. The steering gear  79  is operatively connected to a pitman arm  74  which is in turn connected to a tie rod  75 . The other end of the tie rod  75  is connected to a steering arm  76  which is connected to a king pin  77   a.  The king pin  77   a  has a king pin pivot  77 . A spindle  80  is operatively connected to the king pin  77   a.  The spindle  80  is operatively connected to a stub axle  78  on which a front wheel  18  is mounted. A similar arrangement is provided for the right front wheel  18 . 
     Two torsional suspension members  90  are provided for suspension of the front wheels  18 . Only the left torsional suspension member  90  will be described in detail, as the other suspension member is similar. As seen in FIGS. 12 and 13, the torsional suspension member includes an inner shaft member  91  and an outer hollow member  92 . An elastomeric material  93  is positioned between the inner member  91  and the outer member  92 . The elastomeric material  93  operatively connects the inner member  91  to the outer member  92 . As shown in FIG. 13, there are four elastomeric members  93 . However, it is understood that the elastomeric members  93  may also take other configurations, such as completely surrounding the inner member  91 . As can be seen, the torsional suspension member  90  is based on the same principle as the torsional joint  50 . As shown in FIG. 13, the inner shaft member  91  and the outer hollow shaft member  92  have generally rectangular cross-sections and preferably have a square cross-section. Both ends of the inner shaft member  91  have a bore  91   a  which is tapped and threaded. 
     An A-frame member  94  connects the torsion suspension member  90  to the king pin pivot  77 . The A-frame member  94  is a single member and includes a top member  94   a,  side member  94   b  and side member  94   c,  preferably formed as a single unitary piece, as a casting or by welding or other suitable methods. The A-frame member has one end welded to the outer hollow member  92  and the other end welded to the king pin pivot  77 . The A-frame member  94  is a single member to provide for an A-frame connection between the suspension member  90  and the king pin pivot  77 . 
     A lever arm  95  has a first end  95   a  and a second end  95   b.  An opening  95   c  is formed in the first end  95   a.  A rectangular opening  95   d  is formed in the second end  95   b.  The opening  95   d  is substantially hidden in FIG.  12  and only a corner of the opening is seen. However, the opening  95   d  is sized to be fitted over the end of the inner shaft  91 . The opening  95   d  may be welded to the inner shaft member  91  or it may have a tight fit when slipped over the shaft member  91 . An extension arm  96  has a first end welded to the side  94   c  and has a second end in which a notch  96   a  is formed, or as shown in FIG. 12 may be formed as an integral part of the A-frame  94 . The notch  96   a  is formed between protrusions  96   b  and  96   c.  The extension arm  96  is welded to the outer hollow member  92 . Another opening is formed in the front member  73  and a pin  97  is inserted therethrough. The opening is positioned so that the pin  97  is positioned in the notch  96   a.    
     The torsional suspension element  90  is connected to the housing  70 , and therefore the front frame, by two bolts (not shown) at each end of the inner shaft member  91 . The bolts are inserted through the housing  70  and into the threaded openings  91   a.  The torsion suspension member is at a downward angle of about 15 degrees from the longitudinal axis of the vehicle  10 . The 15 degrees is to allow for the proper steering geometry so that the steering may follow Ackerman&#39;s steering geometry. The first end  95   a  of the lever arm is also secured to the housing by means of a nut and bolt (not shown) which extends through the slot  71   b  and opening  95   c.  The amount of preloading of the suspension element  90  is adjustable by the position that the lever arm is secured in the arcuate slot  71   b.  The arcuate slot has the same radius as that of the pivoting lever arm. In adjusting the amount of loading on the suspension member  90 , the bolts are loosened in the bores  91   a  of the inner shaft member  91  and the lever arm is secured in the desired rotational position by securing the bolt through slot  71   b  and opening  95   c.  Then the bolts are secured in position in the bores  91   a  of the inner shaft member  91  to secure the torsion suspension member  90  to the frame. While the slot  71   b  is shown as an arcuate slot, it is also envisioned that the slot may instead comprise a plurality of openings in an arcuate path. The openings or the slot may be calibrated with a numerical reference to indicate the amount of loading put on the suspension member  90 . Therefore, if for example, a 400-pound plow is attached to the front end of the vehicle  10 , the lever arm  95  could be rotated to the correct marking to compensate for the 400-pound load. 
     As can be seen, it is the inner shaft member  91  which is secured to the frame via the housing  70 . The outer hollow member  92  is operatively connected to the A-frame and therefore the tire  18 . Any movement of the tire  18  in a vertical position causes the A-frame member  94  to move up or down. This translates to a rotational movement of the outer hollow member  92 , which movement is resisted by the elastomeric material  93 . Further, the extension arm  96  with its notch  96   a,  in combination with the pin  97  prevent extreme movements of the tire in an up and down direction. As previously indicated, as the tire moves up and down, the outer wall  92  rotates either clockwise or counter-clockwise, depending upon the direction of the travel of the tire. The pin  97  is positioned in the notch  96   a.  The pin  97  will contact the protrusion  96   b  as the arm  96  rotates if the tire  18  moves upward too far. Similarly, if the tire  18  moves downward, the pin  97  would contact the protrusion  96   c  as the arm  96  rotates and limits movement in the downward direction. 
     While the inner member  91  is connected to the frame, it is appreciated by those skilled in the art that this could be reversed and the outer member  92  could be connected to the frame and the inner member  91  operatively connected to the king pin pivot  77  and therefore the tire  18 . 
     The longitudinal axis of the suspension member  90  extends generally from the front to the rear of the vehicle  10 . However, as previously discussed, it is at a slightly downward angle of approximately 15 degrees. The vertical plane which encompasses the longitudinal axis of the suspension member  90  is parallel to the vertical plane which would include the longitudinal axis of the vehicle  10 . 
     In viewing FIGS. 3 through 5, the advantages of the torsional joint  50  are easily seen. FIG. 3 is a front view of the vehicle  10  as the right rear tire moves downward. The torsional joint  50  allows the rear frame  30  to rotate relative to the front frame  40  without the front frame  40  rotating. Therefore, the cab in which the operator sits is not subjected to the drastic movements of the rear frame  30 . 
     FIG. 4 shows the utility vehicle  10  on level ground. FIG. 5 shows the reverse of FIG.  3 . That is, FIG. 5 shows when the left rear tire goes downward and again the cab in which the operator sits is isolated from the movement of the rear frame  30 . The cab is isolated from the heavy payload that may be carried by the rear frame. 
     This torsional joint  50  allows for better ground following by the wheels of the vehicle  10 . All four wheels are kept on the ground in more instances which helps traction and stability. Further, the joint  50  works very well because it is a non-mechanical joint and there are no washers or spacers to wear. Because the elastic material is used for the resistance to rotation, there is nothing to adjust or loosen up as the joint  50  ages. 
     The suspension member  90  also provides for a simple suspension. The A-frame  94  is a single piece and there is not the need for an additional shock absorber or equivalent, as is required with the prior art. Typically, a spring or a shock is utilized with the prior art vehicles or a suspension system. When a spring or shock is utilized, it is necessary that the frame of the vehicle extend further upward so that the shock or spring may be secured at a point above the wheel. With the present invention, the frame does not have to extend up above the wheel to provide a place of attachment as the single simple A-frame member  94  is planar and is substantially the same height as the king pin pivot  77 . 
     The above specification, examples and data provide a complete description of the manufacture and use of the composition of the invention. Since many embodiments of the invention can be made without departing from the spirit and scope of the invention, the invention resides in the claims hereinafter appended.