Abstract:
A hand-operated assembly that supplies secondary drive power and steering control to a secondary drive wheel of a wheel chair. The assembly comprises a handle that is controlled with one hand and a linkage rod that extends from the handle to an eccentric arm fitted to a one-way clutch assembly at a secondary drive wheel support axle. Reciprocating up-down, pivoting movements of the handle over a range Y′ in the Y axis directs a linkage rod to rotate an eccentric arm fitted to a one-way clutch and a drive axle of a small diameter, secondary drive wheel. Independent 360° rotation of the handle about a second, horizontal or Z axis steers the secondary drive wheel. A portion Y′ of the range of handle motion directs a flange at the linkage arm to engage a brake piece that contacts the secondary drive wheel. Large diameter, hand driven, primary drive wheels are separately available to the user for effecting normal chair conveyance.

Description:
BACKGROUND OF THE INVENTION 
   The present invention relates to wheelchairs and, in particular, to a wheelchair having a drive and steering linkage whereby a wheelchair bound user with a single hand and small hand movement can drive a small diameter idler wheel, independent of large diameter hand drive wheels, to rotate the idler wheel and steer the chair. 
   A wide variety of wheelchairs exist for conveying geriatric and non-ambulatory individuals. Most chairs provide for a pair of relatively large diameter wheels that contain concentric hand rails. The rails can be grasped, rotated and/or manipulated by the user to drive and direct the chair. Most chairs also provide a pair of smaller diameter idler or non-driven wheels that typically support the front end of the chair. The idler wheels stabilize the chair and distribute the weight of the user. The idler wheels are mounted to rotate in associated support columns and follow motions directed by the larger diameter drive wheels 
   A variety of after-market and integrated assemblies have also been developed to provide drive power to the drive wheels of a wheel chair. Many assemblies actively drive the chair with the aid of a battery power source and associated drive linkage. 
   Many ratchet and lever arm accessories also exist in the art that apply drive power to the large diameter drive wheels without having to grip the hand rings. For example, U.S. Pat. No. 5,232,236 and published applications 2002/0043781; 2005/0269797; 2005/0275190; and 2006/0261571 disclose some of these assemblies. Some assemblies provide for foot and hand crank operation. U.S. Pat. Nos. 5,297,810; 5,873,589; 6,196,565; 
   A variety of hand manipulated lever arm assemblies have also been developed for wheel chairs that include drive linkages that cooperate with the large diameter wheel drive axles. To and fro movement of one or more included lever arms mounted to pivot at the chair direct associated linkages (e.g. chain, belt and rod) coupled to supporting axles to drive the large diameter wheels. Some of these assemblies can be found at U.S. Pat. Nos. 4,641,847; 4,762,332; 5,007,655; 5,020,815; 5,236,398; 5,322,312; 5,499,833; 6,325,398; 6,715,7890; 6,746,034; and 6,820,885. An arm rest that pivots side to side and cooperates with an eccentric coupled link rod is disclosed at U.S. Pat. No. 5,509,673. 
   A hand crank assembly that rotates about one axis to supply drive power to a depending chain and independently rotates about a second axis to provide steering to a large diameter drive wheel is shown at US published application 2006/0131832. A pivoting lever arm assembly and chain linkage that cooperates with a large diameter drive wheel and separately provides a rotating steering hand hold that cooperates with a small diameter idler wheel is shown at U.S. Pat. No. 6,916,032. 
   In contrast to the foregoing, the present invention provides a multi-axial hand-operated lever arm that pivots with limited hand movement in one axis (i.e. Y axis) to couple drive power via a rigid drive arm to a one-way clutch and small diameter drive wheel. Reciprocating vertical movement of the hand arm particularly supplies drive power to an eccentric arm fitted to the one-way clutch and a drive axle of a small diameter, secondary drive wheel. The hand arm independently rotates 360° about a horizontal or Z axis within a support column to steer the associated secondary drive wheel. Large diameter, primary drive wheels with hand rings are separately available to the user for normal conveyance. 
   SUMMARY OF THE INVENTION 
   It is a primary object of the invention to provide a hand-operated assembly to supply drive power and steer a drive wheel of a wheelchair. 
   It is further object of the invention to provide a hand-operated, multi-axis linkage operated by a single hand with limited movement to supply drive power and steer a secondary drive wheel of a wheelchair. 
   It is further object of the invention to provide a hand-operated lever arm that pivots in the Y axis at a support column fitted to a wheel chair and manipulates a drive rod coupled to an eccentric arm fitted to a one-way clutch at a drive axle and supported drive wheel. 
   It is further object of the invention to provide a pivoting hand arm that independently rotates 360° at a support column in the Z axis to steer a drive wheel driven by a drive rod and eccentric arm fitted to a one-way clutch at a drive axle. 
   It is further object of the invention to provide a modular support column having drive and steering linkages that couple to an idler support wheel of a wheel chair. 
   It is further object of the invention to provide a modular accessory drive and steering assembly for a secondary drive wheel of a wheelchair. 
   It is further object of the invention to provide a drive and steering assembly that cooperates with an associated brake for a secondary drive wheel of a wheelchair. 
   The foregoing objects, advantages and distinctions of the invention are obtained in a presently preferred assembly shown at attached figures. The assembly permits a wheelchair bound individual to selectively apply drive power with a single hand via a column mounted, pivoting lever arm or handle to a secondary drive wheel secured to the column. A linkage rod is directed from the lever arm to an eccentric arm fitted to a one-way clutch assembly secured to a wheel support axle at the secondary drive wheel. Limited, pivoting motions at the handle rotate and drive the axle and secondary drive wheel. 
   Steering is obtained upon rotating the lever arm and linkage rod within the column and thereby the drive wheel. That is, the lever arm is independently mounted to rotate 360° within the column about the Z axis to turn and steer the secondary drive wheel. Relatively short strokes of the handle lever arm in the Y axis over a range of motion Y′ are translated into controlled movements of the secondary drive wheel. A longer stroke motion of the lever arm over a range of motion Y″ induces a flange at the linkage rod to engage a brake pad mounted to pivot at the column and engage the secondary drive wheel. 
   Still other objects, advantages, distinctions, constructions and combinations of individual features of the invention will become more apparent from the following description with respect to the appended drawings. Similar components and assemblies are referred to in the various drawings with similar alphanumeric reference characters. The description to each combination should therefore not be literally construed in limitation of the invention. Rather, the invention should be interpreted within the broad scope of the further appended claims. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Several figures and photographs are provided which disclose presently preferred constructions of the invention and comprise the following: 
       FIG. 1  is a perspective drawing of a wheel chair fitted with the hand operated lever arm and associated secondary drive wheel assembly of the invention. 
       FIG. 2  is a partial cutaway view to the lever arm, support column and drive linkage. 
       FIG. 3  is a perspective drawing showing a keyed, ratchet and pawl one-way clutch assembly that mounts to a driven axle. 
       FIG. 4  is a perspective drawing showing a roller, one-way clutch bearing assembly that mounts to a driven axle. 
       FIG. 5  is a perspective drawing showing a wheel chair with a detachable idler wheel and a drive/steering assembly and associated secondary drive wheel. 
       FIG. 6  is a perspective drawing showing a wheel chair with a pair of detachable drive/steering assemblies and associated secondary drive wheels. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Referring to  FIGS. 1 , a perspective view is shown to a wheelchair assembly  2  of the invention. The wheelchair  2  is generally constructed in conventional fashion but is fitted with a novel, hand-operated drive/steering assembly  4  that cooperates with a secondary drive wheel  6 . The assembly  4  is operable with limited movements from a single hand and is described in greater detail below with additional attention to  FIGS. 2 through 6 . 
   Depending upon the manufacturer and chair application, the chair  2  can be constructed to a variety of forms and with a variety of wheel configurations. The depicted chair  2  however is representative of the most typical chair design used by hospitals, nursing homes etc. It is to be appreciated therefore that the assembly  4  can be adapted to a variety of chair constructions with differing seat, back rest and primary drive wheel configurations. 
   The chair  2  provides right and left primary drive wheels  8  or relatively large diameter (e.g. 24 to 36 inches). Hand rings  10  are fitted to the drive wheels  8  to provide a mechanism for a physically able occupant to control movements of the wheels  8  to direct the chair  2 . Handles  12  are provided for an attendant to push and manipulate the chair  2 . A hammock or sling-type seat  14  and backrest  16  are stretched between frame members of a support framework  18 . Pairs of armrests  20  and footrests  22  are fitted to the framework  18 . The footrests  22  and/or support arms  24  can be constructed to pivot to facilitate ingress and egress from the chair or may be deleted such as with sport type chairs. 
   Fitted to the forward end of the framework  18  is a typical idler wheel assembly  30 . The assembly  30  provides a secondary, chair support wheel  32  (e.g. 5-8 inches in diameter) that depends from a yoke  34 . The yoke  34  is supported to rotate on bearing surfaces fitted to a column piece  36 . Most wheelchairs include two idler wheel assemblies  30  that are permanently constructed with the chair to distribute the load of the occupant and stabilize the front of the chair  2  during a user&#39;s ingress and egress. The idler wheels passively follow motion directed by the primary drive wheels  8 . 
   The wheel chair  2  has been improved to include at least one hand-operated drive/steering assembly  4  and secondary drive wheel  6  in combination with an idler wheel assembly  30 . The secondary drive wheel  6  of the assembly  4  is of a comparable size to the idler wheel  32 . The assembly  4  enables a user having some hand strength in at least one hand to manipulate and steer the chair  2 , even if unable to direct the primary drive wheels  8 . 
   The idler wheel  32  and drive wheels  8  follow motions directed by the secondary drive wheel  6  and hand operations performed at a hand controlled, handle or lever arm  40 . The assembly  4  finds particular application for geriatric and infirmed individuals, who can now manipulate the chair  2  within activity spaces that don&#39;t require long distance movement (e.g. eating areas, social areas, reading areas or outdoor rest areas) without requiring an attendant. The assembly  4  can be fitted to a chair  2  with appropriate fasteners as an after-market improvement. 
   Turning attention to  FIGS. 2 through 4 ,  FIG. 2  depicts a perspective view of the drive/steering assembly  4  in partial cutaway.  FIGS. 3 and 4  depict alternative constructions of one way, over-running clutch assemblies  42  and  44  that can be secured to a driven axle  46  supporting the secondary drive wheel  6  and coupled to the lever arm  40 . The assembly  4  can be permanently mounted to the chair  2  such as by welding. Alternatively,  FIGS. 5 and 6  depict modular after-market assemblies  4  that can be fastened to a chair to obtain the benefits of the invention and enhance the utility of a chair  2 . Depending upon the chair  2 , minor modifications may have to be performed to adapt the drive/steering assembly  4 . 
   The assembly  4  generally comprises the handle or lever arm  40  which is mounted to rotate about a support column  48  that is coupled to a yoke  50  that supports the driven axle  46  and the secondary drive wheel  6 . A rigid linkage rod  54  extends between the lever arm  40  and a one-way, over-running clutch  44  that is keyed or coupled to the driven axle  46 , reference  FIG. 4 . Either of the clutch assemblies  42  or  44  of  FIGS. 3 and 4  can be adapted to the assembly  4 . 
   The clutch assembly  42  is secured to the axle  46  with a key (not shown) at mating keyways  60  let into the clutch  42 . The inner roller bearing portion  56  of clutch assembly  44  is press fit onto the axle  46 . A variety of alternative clutch assemblies and fastenings can be used to facilitate the coupling of the handle  40  and linkage rod  54  to the axle  46  and/or wheel  6 . 
   The linkage rod  54  is fastened to an offset end of a lobe or eccentric  62  or  64  that project from the clutch assemblies  44  and  42 . The radial offset of the fastening point of the linkage rod  54  to the lobes  62  and  64  from the axle  46  serves as an eccentric or lever arm which defines the effective stroke length of the lever arm  40 . Presently, the lobes  62  and  64  projects approximately 1 to 2 inches and which translates to a range of travel distance at the secondary drive wheel  6  of approximately 2 to 4 inches over the equivalent range of motion Y′ at the lever arm  40 . The actual range of chair movement can be varied as desired by varying the fulcrum or pivot point  82  of the lever arm  40  and/or the length of the lobes  62  and  64  and displacement of the linkage rod  54  from the axle  46  or with other associated gearing etc. 
   Returning attention to the lever arm  40 , the arm  40  is secured to a head piece  70  mounted to the column  48 . The head piece  70  is supported on a bearing  72  and the lever arm  40  thus can be rotated 360° about the Z axis. The lever arm  40  mounts to the head piece  70  at a pivot yoke  74  at a pivot pin  76 . The lever arm  40  extends approximately 5 to 6 inches and includes a rotating hand knob  78  to facilitate reciprocating vertical and rotational horizontal movements of the lever arm  40 . 
   The linkage rod  54  is secured to a pivot bracket  80  formed with and that depends from an inner surface of the arm  40  and a pivot pin  82  that defines the fulcrum point of the lever arm  40 . Over the range of arm motion Y′, the rod  54  rises and falls within the column  48  to rotate an associated lobe  62  or  64  and associated outer clutch assembly  44  or  42  to advance the axle  46  in a preferred clockwise or counterclockwise direction. Counter rotation of the axle  46  is prevented such as by the cogs  84  and pawl  86  at the clutch assembly  42 . Roller bearings  85  that move along arcuate, ramped or tapered surfaces at depressions  87  of the clutch assembly  44  grip and release the axle  46  and similarly limit movement of the axle  46  to be unidirectional. 
   With the operation of the hand lever  40  within the range of motion Y′, the secondary drive wheel  6  incrementally moves the chair  2  as desired by the occupant. Upon elevating the arm  40  into the Y″ range of motion, a flange  91  that projects from the linkage rod  54  engages and rotates a brake member  92  into engagement with the secondary drive wheel  6 . Upon engaging the wheel  6 , a frictional surface of the brake member  92  slows rotation of the wheel  6 . The brake member  92  is normally biased to prevent physical contact with the wheel  6 . A retainer mechanism may be included that cooperates with the latch arm  4  to secure the arm  40  in an elevated condition within the Y″ range of motion to lock movement of the chair  2 , once situated by the occupant. The mounting location of the lever arm  40  may also be re-located as desired with or without modification of the linkage rod  54 . 
   Although the drive/steering assembly  4  is shown as being permanently mounted to the chair  2 ,  FIGS. 5 and 6  depict alternative arrangements wherein representative wheel chairs  100  are shown without any idler support wheels  32 . Combinations of one or two modular drive/steering assemblies  102  and/or a modular idler wheel assembly  104  are shown that can be coupled to improve the support of the chairs  102 . The depicted chairs exemplify the modularity of the drive/steering assemblies  4  and  102  to improve the functionality of a wheelchair during initial construction or as an after-market modification and improvement. 
   The drive/steering assembly  102  and idler assemblies  104  are substantially identical to the assemblies  4  and  30  with the exception of including representative, detachable fasteners  106  and  108 . The fasteners  106  provide mating clamp collars  110  and  112  that cooperate with threaded fasteners  114 . The collars  110  and  112  detachably secure the assembly  102  to an upper end of a frame piece  120  at the chair  100 . 
   The fasteners  108  provide an extension plate  116  and an upright pin  118 . The pin  118  mounts to a lower end of the frame piece  120 . Collectively the fasteners  106  and  108  effectively secure the assemblies  102  and  104  to the wheel chairs  100  yet permit adjustments to facilitate proper alignment. Other types of interconnected, detachable fasteners  106  and  108  can be adapted to obtain a desired retention of the drive/steering assemblies  102  and idler assembly  104  to a chair. 
   The chair  100  at  FIG. 5  when fitted with the assemblies  102  and  104  as an after-market modification is essentially identical to the chair  2 . The chair  100  of  FIG. 6  in contrast includes a pair of independently mounted drive/steering assemblies  102 . The operator necessarily must coordinate and synchronize steering and drive hand movements to assure a desired travel. By operating the arms  40  in an alternating treadle fashion, the range of chair movement however is expanded. 
   While the invention is shown and described with respect to a presently preferred wheelchair drive/steering assembly and several considered improvements, modifications and/or alternatives thereto, still other assemblies and arrangements may be suggested to those skilled in the art. It is also to be appreciated that the singular features of the drive/steering assembly of the invention can be arranged in different combinations and adapted to different chairs. For example, the drive steering assembly can be modified to provide for movement of the handle  40  along only one axis and combined with a chair to selectively steer or drive the wheel  6 . The foregoing description should therefore be construed to include all those embodiments within the spirit and scope of the following claims.