Abstract:
A suspension system for a vehicle includes a support structure of a wheel having a forward rolling axis. The suspension system includes a first link rotatably secured at an inner end to the vehicle and in communication with the support structure of wheel at an outer end. The suspension system includes a second link rotatably secured at an inner end to the vehicle and in communication with the support structure of the wheel at an outer end. The system also includes a shock absorber having a first end in communication with one of the first link or the second link and a second end rotatably secured to the vehicle. The shock absorber is compressible to allow the support structure of the wheel to absorb impact forces imparted thereto during travel. The shock absorber is located along a longitudinal axis of the vehicle.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]    The present invention claims priority from U.S. Provisional Application Serial No. 60/298,723, entitled “4-Bar Linkage Suspension For A Vehicle With Longitudinal Orientation,” filed Jun. 15, 2001. 
     
    
     
       TECHNICAL FIELD  
         [0002]    The present invention relates generally to suspension systems for use with a vehicle wheel. More specifically, the present invention relates to a four bar linkage suspension system for a vehicle wheel that can be used in a variety of all terrain and high speed applications.  
         BACKGROUND OF THE INVENTION  
         [0003]    Suspension systems for vehicle wheels have been developed for a variety of different configurations. These suspension systems are incorporated into a variety of different vehicles, including automobile, motorcycles and the like. Current suspension systems are typically configured such that they are located inwardly from the vehicle wheel and along the wheel&#39;s axis. Because these suspension systems are located inwardly from 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.  
           [0004]    Other known suspension systems, such as utilized on some motorcycles allow the wheel to move up and down as an impact force is imparted to the wheel. This upward and downward movement of the vehicle wheel has no rearward component and the suspension does not provide a stationary suspension base allowing steering of the wheel relative to the suspension and no dolly wheel capability.  
           [0005]    As is also known, 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 decreasing wheel radius.  
           [0006]    Shock absorbing dolly wheel suspensions have been developed to reduce the transmission of impact forces from the ground engaging wheels to the suspension and to the load or equipment supported thereby. Many of these dolly wheel suspension systems utilize a variety of springs attached to different support members to minimize the transmission of impact forces on the dolly wheels to the vehicles. While these dolly wheel suspension systems provide satisfactory performance, that are generally utilized in a trailing fashion on the vehicle. As such, these systems do not provide a forward extending unit and, in particular, if they were placed forwardly of the vehicle, they would require space ahead of the wheel, thereby increasing the vehicle packaging size. And, if these systems were reversed to be forwardly extending as defined, they would not generate an up and back motion of the wheel, which would be most advantageous for a dolly wheel suspension.  
           [0007]    There are also dolly wheel systems that use a short spring or elastomeric compression component to dampen impact loads. However, these systems are relatively limited in suspension travel and are restricted in achieving the travel dampening characteristics that are generally accomplished with a shock absorber.  
           [0008]    It would thus be advantageous to provide a wheel suspension system that is forwardly extending without being ahead of the wheel while providing an up and back motion, which is advantageous to the ride performance of the vehicle. It would similarly be advantageous to provide a suspension system for a dolly wheel that requires significantly less space without sacrificing performance.  
         SUMMARY OF THE INVENTION  
         [0009]    It is therefore an object of the present invention to provide a suspension system for a vehicle wheel that will effectively absorb the shocks incident to travel of the vehicle over irregular road surfaces.  
           [0010]    It is another object of the present invention to provide a suspension system for a vehicle wheel in which the dolly wheel is mounted for generally up and down movements as it encounters irregularities in road surface and 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.  
           [0011]    It is yet another object of the present invention to provide a suspension system for a vehicle wheel that can be packaged in a compact area within a vehicle.  
           [0012]    It is a further object of the present invention to provide a suspension system for a vehicle wheel that includes the full shock absorption and spring action that is currently present in existing automotive vehicles.  
           [0013]    It is still a further object of the present invention to provide a suspension system for a vehicle wheel that allows the vehicle wheel to move upwardly and rearwardly when subjected to an impact force on the ground.  
           [0014]    It is still another object of the present invention to provide a suspension system that is located rearwardly of the vehicle wheel axis with respect to the direction of travel of the vehicle.  
           [0015]    It is yet a further object of the present invention to provide a suspension system that provides the above advantages and/or objects for a dolly wheel&#39;s free rotational orientation or a fixed/steering configuration.  
           [0016]    It is yet another object of the present invention to provide a suspension system that utilizes at least one pivoting linkage with orientation fore and aft resulting in an upwardly and rearwardly path of the wheel and suspension system for absorption of impact  
           [0017]    In accordance with the above and the other objects of the present invention, a suspension system for a vehicle is provided. The suspension system includes a vehicle wheel having a forward rolling orientation defined by the direction of travel. The system includes a first link that is pivotally secured at an inner end to the vehicle. The first link is in communication with the vehicle wheel support at an outer end. The system also includes a second link that is rotatably secured at in inner end to the vehicle. The second link is in communication with the vehicle wheel at an outer end. The system also includes a shock absorber having a first end in communication with either the first link or the second link. The shock absorber has a second end pivotally secured to the vehicle. The shock absorber is compressible to allow the vehicle wheel to absorb impact forces imparted thereto by the four bar linkage controlling the transmitting motion of the wheel while the shock absorber absorbs the load. The shock absorber is located along a forward axis of the vehicle.  
           [0018]    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 DRAWING  
       [0019]    [0019]FIG. 1 is a side view of a vehicle partially broken away illustrating a vehicle wheel suspension system in accordance with a preferred embodiment of the present invention;  
         [0020]    [0020]FIG. 2 is a top view of a vehicle illustrating a vehicle wheel suspension system in accordance with a preferred embodiment of the present invention;  
         [0021]    [0021]FIG. 3 is a schematic side view illustrating the operation of a vehicle wheel suspension system in accordance with a preferred embodiment of the present invention;  
         [0022]    [0022]FIG. 4 is a perspective view of the dolly wheel suspension system of FIG. 3;  
         [0023]    [0023]FIG. 5 is a schematic side view illustrating the operation of a vehicle wheel suspension system in accordance with another preferred embodiment of the present invention;  
         [0024]    [0024]FIG. 6 is a top view of a vehicle employing a vehicle wheel suspension system in accordance with another preferred embodiment of the present invention; and  
         [0025]    [0025]FIG. 7 is a perspective view of a vehicle wheel suspension system in accordance with another preferred embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0026]    Referring now to FIGS. 1 and 2, which illustrates a vehicle  10  utilizing a wheel suspension system  12  in accordance with a preferred embodiment of the present invention. As will be understood, the wheel suspension system  12  is preferably intended for use with a dolly wheel that provides, what are termed in the art, zero turn capabilities. Alternatively, the system may have a fixed steering configuration, but with the ability for the wheel to turn freely forward and below the suspension system. Additionally, the disclosed suspension system is preferably incorporated into a vehicle, such as an automotive vehicle or a mobility vehicle. As shown, when incorporated into a vehicle  10 , the suspension system  12  is preferably included on each of the front wheels  14 . However, it will be understood that the disclosed suspension system can also be utilized on the rear wheels of a vehicle. Moreover, the preferred vehicle  10  has an open front  16 .  
         [0027]    Referring now to FIGS. 3 and 5, which illustrate a preferred embodiment of the present invention. As shown, the wheel suspension system  12  is preferably packaged into a narrow longitudinal space that is in line with a vehicle wheel  14 . The wheel suspension system  12  illustrated in FIGS. 3 and 5, is preferably utilized with a dolly wheel  14 . The suspension system also includes a dolly wheel spindle assembly  18 , a first linkage unit  20 , a second linkage unit  22 , and a shock absorber  24 .  
         [0028]    The dolly wheel spindle assembly  18  includes an upwardly extending pin portion  26 , a top portion  28 , and downwardly extending support portions  30 . The pin portion  26  is received within a bearing housing  32  that allows the pin portion  26  to rotate within the bearing housing  32 . The bearing housing  32  is pivotally secured to a first end  34  of the first linkage unit  20  and to a first end  36  of the second linkage unit  22 . The pin portion  26  is fixedly secured or integrally formed with the top portion  28 , which extends over top of the wheel  14 . The downwardly extending support portions  30  are intended to engage the wheel  14  by an axle or pin, which passes through the center of the wheel  14 . By this configuration, movement of the dolly wheel spindle assembly  18  effectuates movement of the dolly wheel  14 . Moreover, the dolly wheel spindle assembly is thus free to spin about a dolly wheel spindle axis  38  to respond to the direction of travel of a vehicle.  
         [0029]    The first linkage unit  20  has a second end  40 , which is pivotally secured to a frame portion  42  of the vehicle  10 . The second linkage unit  22  has a second end  44 , which is pivotally secured to the frame portion  42  of the vehicle  10 . The first linkage unit  20  and the second linkage unit  22  together form a four bar linkage system. In this orientation, that first linkage unit  20  and the second linkage unit  22  are preferably oriented in a generally horizontal direction, with respect to the ground and the direction of travel of the vehicle  10 . The four-bar linkage suspension system is preferably oriented in line with the vehicle wheel  14 , i.e., behind the vehicle wheel  14  with respect to the direction of travel. This is contrary to normal suspension orientations where the components of the suspension are oriented generally in line with the axis of the wheel, i.e., inwardly from the vehicle wheel and generally in line with its centerline.  
         [0030]    The shock absorber  24  is preferably a spring shock and includes a spring  46 . The shock absorber  24  has an outer end  48  that is pivotally secured to first linkage unit  20  and an inner end  50  that is pivotally secured to the frame portion  42  of the vehicle. The shock absorber  24  is preferably set for operating load and acts in compression. As will be understood, the shock absorber  24  thus urges the first linkage unit  20  and thus the dolly wheel spindle assembly  18  downwardly such that the dolly wheel  14  engages the ground.  
         [0031]    In accordance with the disclosed invention, the linkage members  20 ,  22  and their general axis of movement are located behind the wheel  14  in the normal direction of travel. The linkages  20 ,  22  are constructed with suspension movement to allow clearance for wheel movement. To effectuate clearance, the first linkage unit  20  preferably has a curved configuration to minimize interference with the wheel  14 , when the wheel  14  is pivoted, as shown in FIG. 3.  
         [0032]    As shown in the figures, the suspension system  12  is preferably oriented in line with the wheel  14  with its components accommodated within the width of the wheel  14  and the support linkages  20 ,  22 . The orientation of the support linkages  20 ,  22  and their lengths is intended to provide “up and back” motion of the wheel  14  to better absorb forward impact, bumps, or obstructions. The system also provides free rotation of the wheel and spindle, with clearance for the wheel to be used in a “dolly wheel” configuration. This “up and back” motion is shown best in FIG. 3.  
         [0033]    In operation, when the wheel  14  is subjected to a force, such as through a bump or rock, the wheel  14  moves as defined by the connection of the first ends  34 ,  36  of the first and second linkages  20 ,  22  and the connection of their second ends  40 ,  42  such that the linkages  20 ,  22  move upward and by the result of the 4 bar linkage, allow the wheel  14  to move backward. At the same time, the shock absorber  24  compresses and pivots about its inner end  48  and its outer end  50 . The wheel is thus positioned as indicated by reference number  14 ′ and the linkages are generally indicated by reference numbers  20 ′,  22 ′.  
         [0034]    Referring now to FIGS. 5 through 7, which illustrate another embodiment of a suspension system  12  in accordance with the present invention. The wheel suspension system  12  in this embodiment is also preferably packaged into a narrow longitudinal space that is in line with the vehicle wheel  14 . The wheel suspension system  12  in this embodiment is also preferably utilized with a dolly wheel  14 . However, as will be understood it can be utilized in connection with a variety of other wheels. The suspension system  12  includes a dolly wheel spindle assembly  18 , a first linkage unit  20 , a second linkage unit  22 , and a shock absorber  24 .  
         [0035]    The dolly wheel spindle assembly  18  is secured at an upper end  60  to a wheel carrier portion  62  and at a lower end  64  to the wheel  14 . The wheel carrier portion  62  is pivotally secured to the frame portion  42 . The first end  34  of the first linkage  20  is pivotally secured to the wheel carrier portion  62 . The first end  36  of the second linkage  22  is pivotally secured to the wheel carrier portion  62 . The second end  40  of the first linkage  20  is pivotally secured to the frame portion  42 . The second end  44  of the second linkage  22  is pivotally secured to the frame portion  42 .  
         [0036]    The first linkage unit  20  and the second linkage unit  22  together form a four bar linkage system. In this orientation, the first linkage unit  20  and the second linkage unit  22  are preferably oriented in a generally vertical and direction, with respect to the ground and the direction of travel of the vehicle  10 . The four-bar linkage suspension system is preferably oriented in line with the vehicle wheel  14 , i.e., behind the vehicle wheel  14  with respect to the direction of travel. The shock absorber  24  is connected at its outer end  50  to the wheel carrier frame  62  and at its inner end  52  to the vehicle frame  42 .  
         [0037]    In operation, when the wheel  14  is subjected to an impact force, such as through a bump or rock, the wheel  14  moves as defined by the connection of the first ends  34 ,  36  of the first and second linkages  20 ,  22  and the connection of their second ends  40 ,  42  such that the linkages  20 ,  22  move as a result of the 4-bar linkage to allow the wheel  14  to move backward and upward. At the same time, the shock absorber  24  compresses and pivots about its upper end  48  and its lower end  50 .  
         [0038]    The preferred vehicle configuration provides for an open area  16  between the wheels  14  such that the area can be used for entry and exit of the vehicle or as a lifting area for other devices. This also allows good suspension travel in a small package and the geometry allows a high component of rear motion of the tire for better fore-aft shock absorption.  
         [0039]    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.