Abstract:
A wheel suspension system for a vehicle includes a vehicle wheel having a wheel rim and a tire secured to the wheel rim. The wheel is secured to a frame portion of the vehicle by a spindle assembly. The spindle assembly includes a wheel carrier arm pivotally secured thereto at a pivot point, such that the wheel and the wheel carrier arm rotate together about an axis of rotation defined by pivot point. The wheel carrier arm is in communication with a shock absorption device. The shock absorption device is located within a space defined by the wheel, such that the shock absorption spring device is hidden when the vehicle wheel is viewed from a side direction. The shock absorption spring device compresses upon an impact force contacting the vehicle wheel. In the most compact form, the wheel carrier arm and the shock absorbing spring device is packaged within the wheel rim volume such that both are hidden when the vehicle wheel is viewed from a front direction.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present invention claims priority from U.S. Provisional Application Serial No. 60/298,724, entitled “Dolly Wheel Assembly With An Integrated Suspension,” filed Jun. 15, 2001. 
    
    
     TECHNICAL FIELD 
     The present invention relates generally to a wheel assembly with an integrated suspension for use in a variety of all terrain and high speed applications with the integrated suspension being configured to allow the wheel assembly to move upwardly and rearwardly in response to an impact force. More specifically, the present invention relates to dolly wheels for use with a vehicle that provides maneuverability resulting in what is termed zero turn capability. The present invention also offers advantages when related to vehicle wheels, including both fixed position and steered. 
     BACKGROUND OF THE INVENTION 
     Dolly wheels are commonly used on vehicles or other devices which operate at low speeds (0-10 m.p.h.) as well as on industrial trucks and dollies and other equipment where it is advantageous to have zero turn capabilities. The wheels on such dolly wheel suspensions are subjected to relatively high impact forces when they engage an obstruction. These impact forces typically increase as a function of increasing speed and weight or load and operation in rough surface engagement conditions. 
     Shock absorbing dolly wheel suspensions, which help reduce the transmission of impact forces from the ground engaging wheels to the vehicle load, or load supported thereby, currently exit. Many of these shock absorbing dolly wheel suspension systems utilize a variety of springs attached to different support members to minimize the effect of impact forces that are encountered by the dolly wheels on the vehicles. While these dolly wheel suspension systems provide satisfactory performance, they normally require a relatively large devoted envelope within which to locate the suspension within the vehicle. This large devoted envelope requires structuring the vehicle to accommodate the larger suspension, which thus increases the overall cost of the vehicle. There are also dolly wheel systems that use a short spring or elastomeric compression component to dampen impact loads. However, while compact in size, these systems are relatively limited in suspension travel and travel dampening characteristics that are generally accomplished with a shock absorber utilized within a larger system. 
     Further, suspension systems for vehicle wheels of the non-dolly wheel type have been developed with a variety of different configurations. These suspension systems are incorporated into a variety of different vehicles, including automobile, motorcycle and the like. Current suspension systems are typically configured such that they are located inwardly of the vehicle wheel and their components move generally along the axis of the wheel. Because these suspension systems are located inwardly of the vehicle wheel, they require a relatively large amount of space. These suspension systems provide satisfactory performance. However, the amount of space required to accommodate the suspension system is disadvantageous for many uses. 
     It would thus be advantageous to provide a dolly wheel suspension system that provides significant travel, and requires significantly less space without sacrificing performance. It would also be advantageous to provide a suspension system for a fixed location wheel or a wheel of steering capability that requires significantly less space without sacrificing performance. 
     SUMMARY OF THE INVENTION 
     It is therefore an object of the present invention to provide a wheel suspension system for a vehicle that will effectively absorb the shocks incident to travel of the vehicle over irregular road surfaces. 
     It is another object of the present invention to provide a dolly wheel suspension system in which the dolly wheel is mounted for generally up and down movements as it encounters irregularities in road surface and is arranged with a spring and shock absorber to yieldably resist upward movement of the wheel and to absorb road shocks resulting in the minimum upward component of movement of the vehicle itself. 
     It is yet another object of the present invention to provide a wheel suspension system that can be packaged in a much smaller area within a vehicle than prior suspension systems. 
     It is a related object of the present invention to provide a wheel suspension system that can be utilized with dolly wheels having zero turn capabilities. 
     It is still a further object of the present invention to provide a dolly wheel suspension system that includes the full shock absorption and spring action that is currently present in existing automotive vehicles. 
     It is still another object of the present invention to provide a suspension system for a fixed location wheel, a controlled steered wheel of a vehicle, or an unrestrained dolly wheel that is fully integrated within the rim of the wheel. 
     In accordance with the above and the other objects of the present invention, a wheel suspension system is provided. In the case of a dolly wheel, the suspension system includes a dolly wheel, a wheel carrier arm, and a dolly wheel spindle rotationally secured to a frame element of the vehicle. The dolly wheel spindle has a generally vertical axis of rotation and the wheel carrier arm and the dolly wheel rotate about the axis of rotation. The wheel carrier arm is rotatably secured to the dolly wheel spindle and acts as a swing arm for the dolly wheel. The wheel carrier arm has a first end that is pivotally secured to the dolly wheel spindle and extends downwardly from the pivot point defined by the connection of the wheel carrier arm to the dolly wheel spindle. The wheel carrier arm has a method for rotatably mounting the dolly wheel being generally located in its mid body. The wheel carrier arm has a second end that is remote from the first end with the second end being secured to a first end of a shock absorber. The wheel carrier arm is moveable about the pivot point thereby compressing or extending the shock absorber. The shock absorber incorporates a spring and is rotatably secured at a second end to an extending arm of the dolly wheel spindle. The dolly wheel has an outer periphery and the shock absorber is located within an area defined by the outer periphery of the dolly wheel to minimize the space needed for the suspension system. 
     Other objects and features of the present invention will become apparent when viewed in light of the detailed description of the preferred embodiment when taken in conjunction with the attached drawings and appended claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an exploded view of a wheel suspension system in accordance with a preferred embodiment of the present invention; 
     FIG. 2 is a schematic side view of a dolly wheel suspension system in accordance with a preferred embodiment of the present invention; 
     FIG. 3 is a schematic side view of the dolly wheel suspension system of FIG. 2 illustrating the operation of the suspension system when the wheel is subjected to an impact force in accordance with a preferred embodiment of the present invention; 
     FIG. 4 is a schematic side view of a dolly wheel suspension system in accordance with another preferred embodiment of the present invention; 
     FIG. 5 is a schematic side view of the dolly wheel suspension system of FIG. 4 illustrating the operation of the suspension system when the wheel is subjected to an impact force in accordance with a preferred embodiment of the present invention; 
     FIG. 6 is cross-sectional front view of the dolly wheel suspension system of FIG. 4 in accordance with a preferred embodiment of the present invention; 
     FIG. 7 is a cross-sectional front view of a standard steer wheel suspension system utilizing the general suspension components as shown in FIGS. 4 and 5 in accordance with a preferred embodiment of the present invention; and 
     FIG. 8 is a schematic front view of a standard wheel suspension system utilizing the general suspension components of FIG.  2  and FIG. 3 in accordance with a preferred embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to FIGS. 1 to  3 , which illustrate a wheel suspension system  10  in accordance with a preferred embodiment of the present invention. As will be understood, the wheel suspension system  10  is preferably intended for use with a dolly wheel that provides, what are termed in the art, zero turn capabilities. However, it will be understood that the disclosed wheel suspension system can be utilized with other types of wheels, including wheels that are fixed and have controlled steering capabilities. Additionally, the disclosed suspension system is preferably incorporated into a vehicle, such as an automotive vehicle, a trailed vehicle, or a mobility vehicle. The dolly wheel suspension system  10  includes a dolly wheel  12 , a dolly wheel spindle assembly  14 , a wheel carrier arm  16 , and a shock absorber  18 . 
     The dolly wheel  12  includes a wheel rim  20  having an outer periphery  22 . A tire  24  is disposed around the outer periphery  22  of the wheel rim  20  and is secured to the wheel rim  20 . The tire  24  has an outer periphery  26 , which is intended to engage the ground. The wheel rim  20  has a wheel hub  28  secured thereto, as would be clearly understood by one of skill in the art. The tire  24  is preferably configured for off road capability. 
     The dolly wheel spindle assembly  14  includes an upwardly extending pin portion  30  which is secured to a top portion  32 , which extends over top of the tire  24 . The pin portion  30  is secured to a support portion  34  (FIG. 2) of a vehicle. The pin portion  30  of the dolly wheel spindle assembly  14  is secured through at least one bearing  36  to the support portion  34 . The dolly wheel spindle assembly  14  is thus free to spin about a dolly wheel spindle axis  38  to respond to the direction of travel of a vehicle. 
     The dolly wheel spindle assembly  14  preferably carries all of the suspension components in the direction of travel of the wheel and of the end of the vehicle, as generally indicated by the arrow  40 . The wheel carrier arm  16  is pivotally connected to the top portion  32  of the dolly wheel spindle assembly  14  by a pin  42  to define a pivot point  43  thereat. The pivot point  43  allows the wheel carrier arm  16  to pivot with respect to the dolly wheel spindle assembly  14 , as required. The wheel carrier arm  16  is secured to the shock absorber  18 , which carries a spring  46  to maintain the wheel carrier arm  16  in a secure and load carrying position with respect to the dolly wheel spindle assembly  14 . The wheel carrier arm  16  is also secured to the wheel hub  28  by a bearing shaft  44 . 
     The wheel carrier arm  16  preferably has a bend  45  formed therein to allow a portion of the wheel carrier arm  16  and the shock absorber  18  to fit inside the wheel rim  20 . In this configuration, inside means that at least a portion of the wheel carrier arm  16  as well a portion of the shock absorber  18  are located within the wheel rim  20  when the dolly wheel  12  is viewed from the front. In other words, the bend  45  locates a portion of the wheel carrier arm  16  and the shock absorber  18  inside the outermost side portion of the tire  24  or in the volume defined by the wheel rim. The dolly wheel spindle assembly  14  also includes an extending portion  47  that is also preferably constructed to function as a mud scraper within the wheel rim  20 . 
     The shock absorber  18  is preferably a spring shock and includes the spring  46 . The shock absorber  18  is preferably set for operating load and acts in compression. As will be understood, the shock absorber  18  thus urges the wheel carrier arm  16  downwardly and forwardly such that the dolly wheel  12  engages the ground. The shock absorber  18  is secured to the wheel carrier arm  16  and to the dolly wheel spindle assembly  14  by a plurality of securing bolts  48 . The shock absorber  18  has a first end  50  that is secured to the wheel carrier arm  16  and a second end  52  that is secured to a flange portion  35 . The flange portion  35  extends downwardly from the top portion  32  of the dolly wheel spindle assembly  14 . The first end  50  of the shock absorber  18  is preferably pivotally secured to the wheel carrier arm  16 . Similarly, the second end  52  of the shock absorber  18  is preferably pivotally secured to the dolly wheel spindle assembly  14 . 
     As shown, the suspension system  10  is preferably provided such that the shock absorber  18  is located within the outer periphery  26  of the tire  24 . More preferably, the shock absorber  18  is located within the outer periphery  22  of the wheel rim  20 . Additionally, at least a portion of the wheel carrier arm  16  is located within the outer periphery  22  of the wheel rim  20 . Preferably, a substantial portion of the wheel carrier arm  16  is located within the outer periphery  22  of the wheel rim. The dolly wheel  12  and the wheel rim  20  are preferably of a sufficient diameter to accommodate the suspension needed by the vehicle. 
     It will be understood that it is also possible to locate the wheel carrier arm  16  either within the outer periphery  22  of the wheel rim  20  or outside the outer periphery  26  of the tire  24 , depending on packaging needs. Moreover, the pivot point  43  for the wheel carrier arm  16  can be positioned outside the outer periphery  26  of the tire  24  and the wheel rim  20  for more linear path of the dolly wheel  12  and thus a greater length of suspension travel. 
     In the embodiment shown in FIGS. 1 through 3, a substantial portion of the wheel carrier arm  16  is located within the periphery of the wheel rim  20 . Moreover, the suspension system  10  is located below the dolly wheel spindle axis  38 . The suspension operates equally in all directions of vehicle motion with the turning of the dolly wheel  12  to the direction of travel. This is because the dolly wheel  12  spins toward its direction of travel, thereby taking the suspension system  10  with it in that direction of travel. It will be understood that when utilized on a vehicle, a pair of dolly wheels will preferably be utilized. The operation of each dolly wheel and its associated suspension is preferably the same and thus the description of the structure and operation of one will apply equally to the operation of the other. 
     Referring now to FIG. 3, which illustrates the operation of the suspension system  10  in accordance with the present invention. As shown, when the tire  24  contacts a bump or rock  60  in the road or ground, a force can impact the tire  24 , which results in upward and rearward motion, as generally indicated by arrow  70 , in such a manner as to absorb forward motion impact. This upward and rearward motion is shown in FIG.  3 . In order to effectuate this motion, the wheel carrier arm  16  rotates about the pivot point  43  and the shock absorber  18  compresses against the force of the spring  46 . Moreover, because the shock absorber  18  is pivotal about its first end  50  and its second end  52 , it can rotate during compression to accommodate for the length of travel of the wheel carrier arm  16 . 
     Referring now to FIGS. 4 through 6, which illustrate another embodiment of the suspension system  10  in accordance with the present invention. In the embodiment shown in FIG. 4, the dolly wheel spindle assembly  14  and the wheel carrier arm  16  are configured differently than the embodiment shown in FIGS. 2 to  3 . As shown in FIG. 4, the flange portion  35  of the dolly wheel spindle assembly  14  extends further downwardly than in the embodiment of FIGS. 2 and 3 such that its axis pin  43 , rotatably securing the wheel carrier arm  16  is located within the outer periphery  26  of the tire  24 . With this configuration, the pivot point determined by axis pin  43  is located within the outer periphery  22  of the wheel rim  20 . Moreover, the first end  52  of the shock absorber  18  is pivotally secured to an extension portion  62  that is integrally formed with the dolly wheel spindle assembly  14 . 
     FIG. 5 illustrates the operation of the suspension system  10  of FIG.  4 . The operation of the suspension system  10  is substantially the same as in the embodiment described above in connection with FIGS. 1 through 3. Specifically, when the tire  24  contacts a bump or rock  60  in the road or ground, a force can impact the tire  24 , which results in upward and rearward motion in such a manner as to absorb forward motion impact. In order to effectuate this motion, the wheel carrier arm  16  rotates about the pivot point  43  and the shock absorber  18  compresses against the force of the spring  46 . Moreover, because the shock absorber  18  is pivotal about its first end  50  and its second end  52 , it can rotate during a compression to accommodate the travel of the wheel carrier arm  16 . 
     FIG. 6 illustrates the wheel carrier arm  16  and the shock absorber  18  being located within an area or volume defined by the wheel rim  20 . Thus, as shown, in the front view, the shock absorber  18  and the wheel carrier arm  16  are located within the area defined by the wheel rim  20 . Similarly, the wheel carrier arm  16 , the axis pin  43 , and the shock absorber  18  are located within the outer periphery  22  of the wheel rim  20  when viewed from the side view. 
     FIGS. 7 and 8 illustrate alternative embodiments of the preferred suspension system  10  for use with a standard steering system. As shown, a tire  80  is secured to a vehicle frame  82 . The vehicle frame  82  includes a tie rod  84  extending therefrom to effectuate standard steering. The vehicle frame  82  includes a vehicle king ping  84  secured thereto. The king pin  85  includes a generally vertical axis of rotation  86 . The king pin  85  is in communication with an assembly  88  of the vehicle frame  82  for securing a wheel carrier  90 . The wheel carrier  90  has a wheel carrier arm  92  pivotally secured thereto on axis  101 . A shock absorber  94  and associated spring  96  is disposed between one end  98  of the wheel carrier arm  92  and an upper end  100  of the wheel carrier  90 . The wheel carrier arm  92  is secured to a wheel hub  102  on an axis  103 , as will be understood by one of skill in the art. The operation of the suspension system  10  for the standard steering, as illustrated in FIGS. 7 and 8, is the same as described above in connection with dolly wheel steering. 
     In the embodiment shown in FIG. 7, the wheel carrier arm  92  and the shock absorber  94  are located entirely within the area or volume defined by the wheel rim  104 . Thus, as shown, in the front view, the shock absorber  94  and the wheel carrier arm  92  are located within the area defined by the wheel rim  104 . Similarly, the wheel carrier arm  92 , the axis pin  101 , and the shock absorber  94  are located within the outer periphery  108  of the wheel rim  104  when viewed from the side view. In the embodiment shown in FIG. 8, the wheel carrier arm  92  and the shock absorber  94  are located entirely outside the tire  80  and the wheel rim  104  in the front view. However, the wheel carrier arm  92  and the shock absorber  94  are located inside the outer periphery  110  of the tire  80  when viewed from the side view. 
     In accordance with the above, the suspension system  10  has maximum ability in all directions of the vehicle steer condition. Further, the angle of the king pin axis  86  does not change with movement of the suspension system  10 . The disclosed suspension system  10  provides a compact, cost effective design and in particular is an excellent, well-packaged suspension for a mobility vehicle. It will be appreciated that a free acting dolly wheel  12 , as shown in FIGS. 1 through 6, with this suspension system  10  could also be controlled to effectuate fully controlled steering with the use of the suspension system described herein. Alternatively, the disclosed suspension system  10  could be used with a standard wheel, as disclosed in FIGS. 7 and 8, rather than a dolly wheel. 
     While a preferred embodiment of the present invention has been described so as to enable one skilled in the art to practice the present invention, it is to be understood that variations and modifications may be employed without departing from the purview and intent of the present invention, as defined in the following claims. Accordingly, the preceding description is intended to be exemplary and should not be used to limit the scope of the invention. The scope of the invention should be determined only by reference to the following claims.