Abstract:
A quadricycle includes a four-wheel suspension system that is structured to maintain contact between the ground and the wheels when traversing uneven terrain, as well as to permit a rider to lean into a curve in order to facilitate steering the vehicle. The suspension assemblies are relatively wide to resist rollover accidents. Shock absorbers within the suspension assemblies are angled from vertical to provide both a vertical force component and a horizontal force component in order to permit leaning into a curve while resisting excessive leaning. The quadricycle&#39;s drivetrain is structured to increase clearance between the ground and many drivetrain components. Smaller components of the spindle and wheel hub assembly are protected by larger components of the suspension assembly.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of U.S. provisional patent application Ser. No. 61/447,233, filed on Feb. 28, 2011, and entitled “Pedal-Powered Four Wheel Cycle.” 
     TECHNICAL FIELD 
     The present invention relates to pedal-powered vehicles. More specifically, a quadricycle having an independent suspension for each wheel is provided. 
     BACKGROUND INFORMATION 
     Pedal powered vehicles are well known. Although bicycles are the most common, unicycles, tricycles, and quadricycles have all been built in the past. Such vehicles are currently used for physical fitness, recreation, and transportation. 
     Concerns about both the price of gasoline, as well as the environment, are expected to result in increased interest in the use of pedal powered vehicles for transportation. Although presently available bicycles are safe and easy to ride on a relatively dry road, slippery conditions such as snow, ice, rain, mud, or gravel can greatly increase the likelihood of a fall. A fall that occurs in traffic could potentially have serious consequences. 
     A quadricycle would be much safer in slippery conditions than a bicycle. However, when traveling over uneven surfaces, a presently available quadricycle, which typically includes rigid axles, would be unable to maintain contact between all four wheels and the ground at all times. Accordingly, there is a need for a means of maintaining contact between all four wheels of a quadricycle and the ground at all times. 
     Furthermore, a bicycle has the advantage of steering not only by turning the handlebars, but also by leaning into a turn. Leaning into a turn resists the centrifugal forces which would otherwise tend to cause a vehicle to tip over during a turn. Unfortunately, presently available quadricycles do not provide any means of leaning into a turn. 
     U.S. Pat. No. 4,360,224 discloses a tricycle having two front wheels and a single rear wheel. The front wheels are connected to the frame through a double wishbone suspension having a pair of upper arms and a pair of lower arms connected by vertical links at their outer ends. The upper arms are pivotally connected to the frame. The lower arms are pivotally connected to a longitudinal shaft by a shock absorbing cushion. 
     U.S. Pat. No. 6,286,846 discloses a suspension system for isolating a load independently from two separate inputs such as a pair of wheels. The suspension is applicable to two wheeled vehicles, with the inputs being the front and rear wheels of a bicycle. 
     US 2002/0190494, filed by C. Cocco et al. and published on Dec. 19, 2002, discloses a tricycle having two front wheels and a single rear wheel. The suspension assembly disclosed therein utilizes essentially vertical shock absorbers, within a relatively narrow structure. 
     A suspension system for a quadricycle is disclosed within US 2007/0029751, filed by M. Marcacci and published on Feb. 8, 2007. This suspension system is designed specifically to avoid steering caused by the rolling of the vehicle, as stated in paragraph [0026], [0029], and [0039] of Marcacci. Conversely, the present inventor believes that utilizing the leaning of the vehicle to affect or assist with steering is advantageous. Furthermore, this suspension system utilizes essentially vertical shock absorbers. 
     Accordingly, there is a need for a pedal powered vehicle having a suspension system which will permit leaning into a turn while negotiating a curve, while at the same time resisting excessive leaning of the vehicle. 
     SUMMARY 
     The above need is met by a quadricycle having a suspension system. The suspension system includes a mount having a central portion pivotally secured to a lower portion of the vehicle&#39;s frame. The mount is permitted to pivot with respect to the frame in order to increase the flexibility of the suspension system. A lower arm is pivotally secured to one end of the mount. An upper arm is hingedly secured to and upper portion of the vehicle&#39;s frame. A spindle assembly is hingedly secured between the upper and lower arms. A shock absorber extends from either the lower arm or the upper arm to the frame. 
     Another example of a quadricycle has a suspension system with a mount having a central portion secured to a lower portion of the vehicle&#39;s frame. The mount is permitted to pivot with respect to the frame in order to increase the flexibility of the suspension system. A lower arm is pivotally secured to one end of the mount. An upper arm is hingedly secured to and upper portion of the vehicle&#39;s frame. A spindle assembly is hingedly secured between the upper and lower arms. A shock absorber extends from either the lower arm or the upper arm to the frame. 
     The shock absorber is angled with respect to vertical in order to provide force components in both the vertical and horizontal directions. 
     Yet another example of a quadricycle includes a suspension system having a mount having a central portion pivotally secured to a lower portion of the vehicle&#39;s frame. The mount is permitted to pivot with respect to the frame in order to increase the flexibility of the suspension system. A lower arm is pivotally secured to one end of the mount. An upper arm is hingedly secured to and upper portion of the vehicle&#39;s frame. A spindle assembly is hingedly secured between the upper and lower arms. A shock absorber extends from the lower arm to the frame. 
     These and other aspects of the invention will become more apparent through the following description and drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an isometric front, left side, and top view of a quadricycle. 
         FIG. 2  is a top plan view of the quadricycle of  FIG. 1 . 
         FIG. 3  is an isometric front, left side, and top view of a quadricycle having the wheels removed for clarity. 
         FIG. 4  is an isometric front, right side, and top exploded view of the right front suspension assembly of the quadricycle of  FIG. 1 . 
         FIG. 5  is an isometric front, left side, and top partially exploded view of a wheel hub assembly for a quadricycle of  FIG. 1 . 
         FIG. 6  is an isometric view of a spindle assembly of the quadricycle of  FIG. 1 . 
         FIG. 7  is an isometric front, left side, and top view of a drivetrain and left rear suspension assembly of the quadricycle of  FIG. 1 . 
         FIG. 8  is an isometric front, left side, and top view of a drivetrain of the quadricycle of  FIG. 3 . 
         FIG. 9  is an isometric front, left side, and top exploded view of a differential assembly for a drivetrain of  FIGS. 7-8 . 
         FIG. 10  is a front plan view of the right and the left front suspension assemblies of a quadricycle of  FIG. 1 , showing the positioning of the parts while traveling in a straight line. 
         FIG. 11  is a front plan view of the right and the left front suspension assemblies of a quadricycle of  FIG. 1 , showing the positioning of the parts while traveling around a curve to the right. 
         FIG. 12  is a left side, top, and rear isometric view of an alternative quadricycle. 
         FIG. 13  is a right side, top, and rear isometric view of yet another alternative quadricycle. 
         FIG. 14  is a front plan view of the right and the left front suspension assemblies of a quadricycle of  FIG. 1 , showing the positioning of the parts while traveling around a curve to the left. 
         FIG. 15  is a front plan view of the right front and the left front suspension assemblies of a quadricycle of  FIG. 1 , showing the positioning of the parts while traveling around a curve to the right. 
     
    
    
     Like reference characters denote like elements throughout the drawings. 
     DETAILED DESCRIPTION 
     Referring to  FIGS. 1-3 , a quadricycle  10  is shown. The quadricycle  10  includes a frame  1 . A seat  14  is secured to and upper portion of the frame  12  in a manner that may provide for height adjustment in a manner that is well known to those skilled in the art of pedal vehicles. A handlebar assembly  16  is pivotally secured within a forward portion  18  of the frame  12 . A left front suspension assembly  20  and right front suspension assembly  22  are hingedly secured to the forward portion  18  of the frame  12  in a manner that will be explained in greater detail below. Similarly, a left rear suspension assembly  24  and right rear suspension assembly  26  are hingedly secured to a rear portion  28  of the frame  12 , in a manner that will be explained in greater detail below. 
     Referring to  FIG. 4 , the individual components of the right front suspension assembly  22 , which is a mirror image of the left front suspension assembly  24 , are shown. This suspension assembly  22  includes a lower arm  30 . The illustrated example of the lower arm  30  is an A-arm  30  which is generally triangular when viewed from the front, having a forward inner corner  32  and rear inner corner  34 . Each of the inner corners  32 ,  34  include a hinge connector element  36 , which in the illustrated example is a ball joint rod end  36  having a threaded portion  38  that is structured to interface with a corresponding threaded portion of the inner corners  32 ,  34 . The ball joint rod end  36  further includes an aperture  38  that is structured to receive a pin  40 , which also passes through at least one corresponding aperture  42  defined within the mount  44 , which is secured to a lower portion of the forward portion  18  of the frame  12 . Some examples of the mount  44  may pivot with respect to the frame  12 , while other examples of the mount  44  are rigid with respect to the frame  12 . The threaded connection between the ball joint rod end  36  and corners  32 ,  34  permits some adjustment to the length of this portion of the A-arm  30 . 
     The upper portion  46  of the A-arm  30  includes a bracket  48  defining at least one aperture  50  therein. Similarly, the outer corner  52  of the A-arm  30  includes a similar bracket  54 , defining at least one aperture  56  therein. A base  88  and spindle  96 , described in more detail below, are secured within the bracket  54 . A bracket  57  defining aperture  61  therein is secured to the top of the spindle  96 . 
     A control arm  58  is structured to connect the bracket  57  and upper portion  59  of the forward portion  18  of the frame  12 . The illustrated example of the control arm  58  includes a pair of threadedly connected ball joint rod ends  60 ,  62 , each of which defines an aperture  64 ,  66 , respectively. The threaded connection between the control rod  58  and the ball joint rod ends  60 ,  62  permits some adjustments to the length of the assembly formed by these components, thereby permitting the tilt of a wheel  84  to be adjusted. The ball joint rod end  60  is connected to the bracket  57  by a pin  63  passing through the corresponding apertures  64 ,  61 . Similarly, the ball joint rod end  62  is connected by a pin  68  passing through the apertures  66  as well as at least one corresponding aperture  70  defined within a bracket  72  that is secured to the upper portion  59  of the forward frame portion  18 . The upper portion  59  includes a second bracket  74  defining an aperture  76 . A shock absorber  78  defines an aperture  80 ,  82  at each end. In the illustrated example, the shock absorber  78  is a gas shock, incorporating both a spring and an adjustable gas system. The shock absorber  78  is secured between the upper front frame portion  59  and upper A-arm portion  46  by a pin  84  passing through the corresponding apertures  76 ,  80 , as well as the pin  86  passing through the corresponding apertures  82 ,  50 . The shock absorber  78  serves to bias the A-arm  30  downward. The angle at which the shock absorber  78  is mounted is such that the shock absorber provides both vertical and horizontal force components, with a significant horizontal force component for resisting excessive lean of the quadricycle  10 . Some examples of the shock absorber  78  will be mounted at least about 15° from vertical, or in other examples at least about 30° from vertical. Other examples of the shock absorber  78  will be mounted at least about 45° from vertical. The illustrated examples do not exceed about 75° from vertical, or in other examples about 60° from vertical in order to provide a vertical force component. 
     A wheel  84  is rotatably secured to the right front suspension assembly  22  utilizing the wheel hub and spindle assembly  86  which is best illustrated in  FIGS. 5-6 . The assembly  86  includes a base  88  which is pivotally secured within the bracket  54 . Referring specifically to  FIG. 6 , the base  88  defines a central vertical hole  90 , and offset vertical hole  92 , and a horizontal hole  94  intersecting the holes  90  and  92 . The spindle  96  is secured on top of the base  88 . The spindle  96  includes a central threaded hole  98  and an offset threaded hole  100  defined within the bottom surface  102 . In the case of a front wheel hub assembly, a bolt  90  is inserted upward into the central holes  90 ,  98  to pivotally secure the spindle  96  with respect to the base  88 . In the case of a rear wheel, a second bolt is inserted upward through the offset holes  92 ,  100 , so that the bolts contained within the central holes  90 ,  98 , combined with the bolts secured within the offset holes  92 ,  100 , resist fitting of the spindle  96  with respect to the base  88 . In either case, a bolt  104  is secured within the horizontal hole  94  by the nut  106  and/or pin  108 . The bolt  104  not only secures the base  88  to the bracket  54 , but also acts as a barrier to resist loosening of the bolts within the holes  90 ,  92 . A bolt passing into the central hole  98  may further be secured by a pin  110 . 
     Referring back to  FIGS. 6-7 , the spindle  96  includes an axle receiving hole  112 , which in the illustrated example includes a bearing  114  therein. A spindle  96  utilized in conjunction with the front wheels also includes a rod  116  protruding from one side, which will be utilized in steering the quadricycle as explained in greater detail below. The illustrated example of the rod  116  includes an attachment flange  118  defining a hole  120  therein. A bracket  57  is secured to the top of the spindle  96 . Because the spindle assembly  86  is located above the A-arm  30 , these components are protected by the solid structure of the A-arm  30 . 
     Referring to  FIGS. 3 and 8 , the individual components of the left rear suspension assembly  24 , which is a mirror image of the right rear suspension assembly  26 , are shown. Some elements of the left rear suspension assembly  24  have been omitted from  FIG. 8  for clarity in illustrating the drivetrain, which is described below. The suspension assembly  24  includes a lower arm  126 . The illustrated example of the lower arm  126  is an A-arm  126  which is generally triangular when viewed from the front, having a forward inner corner  128  and rear inner corner  130 . Each of the inner corners  128 , 130  include a hinge connector element  132 , which in the illustrated example is a ball joint rod end  132  having a threaded portion  134  that is structured to interface with a corresponding threaded portion of the inner corners  128 ,  130 . The ball joint rod end  132  further includes an aperture  136  that is structured to receive a pin  138 , which also passes through at least one corresponding aperture  140  defined within the mount  142 , which is secured to a lower portion  144  of the rear portion  28  of the frame  12 . Some examples of the mount  142  may pivot with respect to the frame  12 , while other examples of the mount  142  are rigid with respect to the frame  12 . The threaded connection between the ball joint rod end  132  and corners  128 ,  132  permits some adjustment to the length of this portion of the A-arm  126 . 
     The upper portion  146  of the A-arm  126  includes a bracket  148  defining at least one aperture  150  therein. Similarly, the outer corner  152  of the A-arm  126  includes a similar bracket  154 , defining at least one aperture  156  therein. A base  88  and spindle  96  are secured within the bracket  154  in the same manner as described above, in a manner that resists pivoting of the spindle  96  with respect to the base  88 . A bracket  158  defining an aperture  160  therein is secured to the top of the spindle  96 . 
     A control arm  162  is structured to connect the bracket  158  and upper portion  164  of the rear portion  28  of the frame  12 . The illustrated example of the control arm  162  includes a pair of threadedly connected ball joint rod ends  166 ,  168  each of which defines an aperture  170 ,  171 , respectively. The threaded connection between the control rod  162  and the ball joint rod ends  166 ,  168  permits some adjustments to the length of the assembly formed by these components, thereby permitting the tilt of a wheel  84  to be adjusted. The ball joint rod end  166  is connected to the bracket  158  by a pin  172  passing through the corresponding apertures  160 ,  170 . Similarly, the ball joint rod end  168  is connected by a pin  174  passing through the aperture  171  as well as at least one corresponding aperture  176  defined within a bracket  178  that is secured to the upper portion  164  of the rear frame portion  28 . The upper rear portion  164  includes a second bracket  180  defining an aperture  182 . A shock absorber  184  defines an aperture  186 ,  188  at each end. In the illustrated example, the shock absorber  184  is a gas shock, incorporating both a spring and an adjustable gas system. The shock absorber  184  is secured between the upper rear frame portion  164  and upper A-arm portion  146  by a pin  190  passing through the corresponding apertures  186 ,  182 , as well as the pin  192  passing through the corresponding apertures  150 . The shock absorber  184  serves to bias the A-arm downward. Some examples of the shock absorber  184  will be mounted at least about 15° from vertical, or in other examples at least about 30° from vertical. Other examples of the shock absorber  184  will be mounted at least about 45° from vertical. The illustrated examples do not exceed about 75° from vertical, or in other examples about 60° from vertical in order to provide a vertical force component. 
     Referring back to  FIG. 7  as well as  FIG. 8 , a drivetrain  194  is shown. The drivetrain  194  begins with a conventional set of pedals  196  connected coaxially with at least one sprocket  198 . The sprocket  198  is connected by a chain  200  to a second sprocket  202  that is rotatably mounted in an upper portion  204  of the middle of the frame  12 . The second sprocket  202  is mounted coaxially with a third sprocket  206  that may have the same or a different diameter. The third sprocket  206  is connected by a chain  208  to a cassette  210  formed from a group of coaxially mounted sprockets in conjunction with a gear shifting mechanism located in the upper rear portion  164  of the frame  12 . Gear shifting mechanisms are well known to those skilled in the art of pedal powered vehicles. The cassette  210  is coaxially connected to a right side initial drive sprocket  212  and a left side initial drive sprocket  214 .  FIG. 7  illustrates the left side of the drive mechanism, which is a mirror image of the right side of the drive mechanism. A chain  216  connects the left side initial drive sprocket  214  to a fifth sprocket  218  that is rotatably mounted in the rear lower portion  144  of the frame  12 . 
     Sprocket  218  is connected to one end of a first drive shaft portion  220 . The other end of the first drive shaft portion  220  includes a universal joint  222 , to which a second drive shaft portion to  224  is connected. The second drive shaft portion  224  terminates near the spindle  96 , where it is connected by another universal joint to a third drive shaft portion  226 . The third drive shaft portion  226  passes through the bearing  114  within the spindle  96 , terminating in a one-way ratcheting mechanism  228 . A hub assembly  230  is connected to the ratcheting mechanism  228 . The one-way ratcheting mechanism  228  permits the hub assembly  230  and wheel  84  thereon to be driven by the third drive shaft portion  226  when the pedals  196  are operated, and also allows the wheel  84  to spin freely while coasting. 
     The drivetrain  229  of  FIG. 8  is very similar to the drivetrain  194 , differing primarily in that the right/left sprockets  212 ,  214  and associated chains are replaced with a single upper sprocket  231 , chain  233 , and lower sprocket  235 . 
     The steering mechanism is best illustrated in  FIG. 3  and. For each of the front suspension assemblies  20 ,  22 , the flange  118  of the rod  116  of the spindle  96  is operatively connected to a rod  232 , the opposite end of which is operatively connected to the handlebar assembly  16 . Turning the handlebars causes the rods  232  to rotate the spindles and  96  in the appropriate direction. The handlebar assembly  16  may further include gear shifting levers in a manner well known to those skilled in the art. 
       FIGS. 10-11  illustrate the working of the suspension system.  FIG. 10  depicts the components of the suspension system as the quadricycle  10  is traveling in a straight line. During linear travel, both the right and left A-arms are generally horizontal, with both the right and left shock absorbers being essentially the same length. As the quadricycle  10  negotiates a right-hand curve, shown in  FIG. 11 , the rider may lean to the right to aid in negotiating the curve. This leaning causes the right side suspension assembly to pivot upward, and the left side suspension assembly to pivot downward. This leaning also causes the wheels  84  to lean, so that the quadricycle is riding at least partially on the side edges of the wheels, thereby causing the natural rotation of the wheels to aid in negotiating the right side turn. This leaning further positions the quadricycle and rider in a more stable position with respect to the centrifugal forces generated by negotiating the curve. 
       FIGS. 14-15  illustrate negotiating a curve utilizing in embodiment of the quadricycle  10  having mounts  44 ,  142  that are pivotally mounted to the frame. In each of  FIGS. 14-15 , the mounts  44 ,  142  have remained substantially horizontal even though the frame  12  is leaning to one side in order to lean into a curve. Depending on the terrain, the mounts  44 ,  142  may remain substantially horizontal, or they may assume other orientations as best suits the movement of the quadricycle  10 . 
     The configuration of the drivetrain further assists the ability of the quadricycle  10  to negotiate curves and various terrain irregularities. By placing many of the components of the drivetrain relatively high on the frame, any danger of striking the ground with these components is reduced. Furthermore, the various universal joints connecting the drive shaft sections permit the drive shaft sections to move in a manner that delivers power to the wheels  84  while resisting any interference to the movement of the suspension assemblies. 
     A quadricycle  236  having a modified drivetrain  238  is illustrated in  FIG. 12 . The pedals  240  and associated sprocket  242  remain in a relatively standard position on the frame  244  relative to the seat  246 . A chain  248  extends forward from the sprocket  242  to a cassette  250 . The cassette  250  is coaxial with a sprocket  252 . A chain  254  carries the power from the sprocket  252  to a rear sprocket  256 . A driveshaft arrangement similar to that described above extends from the sprocket  256  to the wheels  84 . 
     A quadricycle  258  having a modified rear suspension assembly is illustrated in  FIG. 13 . The frame  260  of the quadricycle  258  includes a rear suspension assembly  262 . The rear suspension assembly includes an arm  264  pivotally secured to the frame to  60 , and extending rearward from the frame  260 . The illustrated example of the arm  264  as the general configuration of a two-pronged fork. A shock absorber  266  is connected between the arm  264  and an upper rear portion of the frame  268 . A drivetrain sprocket  270  is coaxially mounted on a solid driveshaft  272  that is rotatably secured at the rearward end of the arm  264 . 
     The quadricycle described above therefore provides a suspension system for maintaining contact between the wheels and the ground when negotiating uneven terrain, and to permit leaning into a turn when negotiating curves. The shock absorbers are angled from vertical to provide both vertical and horizontal force components to permit leaning into a curve while resisting excessive leaning. The width of the suspension assemblies resists rollovers, improving safety in snow, ice, wet roads, mud, and/or gravel. Drivetrain elements are elevated from the ground for better protection. Spindle elements are protected by larger suspension assembly components. 
     A variety of modifications to the above-described embodiments will be apparent to those skilled in the art from this disclosure. For example, any of the various hinge components could be reversed. Furthermore, a gear shifting cassette can be included at any point within a drivetrain. Thus, the invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof. The particular embodiments disclosed are meant to be illustrative only and not limiting as to the scope of the invention. The appended claims, rather than to the foregoing specification, should be referenced to indicate the scope of the invention.