Abstract:
A power wheelchair includes a pair of clutches, each coupled to a respective drive power source and a respective drive wheel, and a clutch control device that includes a pair of rod pivoting units, a control unit, and a flexible linking unit interconnecting the control unit and the rod pivoting units. The rod pivoting units are coupled to rotary control rods of the clutches, respectively. By operating the control unit, drive power transmission of the clutches can be controlled accordingly.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The invention relates to a power wheelchair, more particularly to a power wheelchair equipped with a clutch control device for controlling drive power transmission of a pair of clutches.  
         [0003]     2. Description of the Related Art  
         [0004]     As shown in  FIGS. 1 and 2 , a conventional power wheelchair  1  includes a pair of clutches  11 , each of which is mounted on a chair frame (not shown) and has a rotary control rod  111 , a pair of motors  12  respectively coupled and supplying drive power to the clutches  11 , a pair of drive wheels  13  respectively coupled to and driven by the clutches  11 , and a clutch control device  14  for controlling drive power transmission of the clutches  11 .  
         [0005]     The clutch control device  14  includes a pair of rod pivoting components  141 , each of which is coupled to the rotary control rod  111  of a respective one of the clutches  11 , an intermediate connecting rod  142  having opposite ends connected pivotally and respectively to the rod pivoting components  141 , a drive rod  143  connected pivotally to one of the rod pivoting components  141 , a link  145  connected pivotally to the drive rod  143  and further connected to the chair frame so as to be pivotable about a pivot axis  144 , and a handle  146  for controlling rotation of the link  145 .  
         [0006]     The handle  146  is operated when it is desired to enable or disable transmission of drive power by the clutches  11  from the motors  12  to the drive wheels  13 , i.e., when it is desired to switch the power wheelchair  1  from a power driving mode to a manual driving mode, and vice versa. In particular, when the handle  146  is operated, the link  145  rotates about the pivot axis  144 , and the drive rod  143  moves one of the rod pivoting components  141 . The other rod pivoting component  141  also moves at this time due to the connection with the intermediate connecting rod  142 .  
         [0007]     The following are some of the drawbacks of the aforesaid conventional power wheelchair  1 :  
         [0008]     1. The intermediate connecting rod  142  of the clutch control device  14  is a rigid component that interconnects the rod pivoting components  141  and that requires some space for movement when switching the power wheelchair  1  between the power driving and manual driving modes, thereby resulting in restrictions to the spatial design (i.e., disposition of other components) of the conventional power wheelchair  1 .  
         [0009]     2. The intermediate connecting rod  142  and the drive rod  143 , which are made of rigid metal material, result in a heavier total weight for the clutch control device  14 .  
       SUMMARY OF THE INVENTION  
       [0010]     Therefore, the object of the present invention is to provide a power wheelchair with a clutch control device that can overcome the aforesaid drawbacks associated with the prior art.  
         [0011]     Accordingly, a power wheelchair of the present invention comprises a chair frame, a pair of clutches, a pair of drive power sources, a pair of drive wheels, and a clutch control device.  
         [0012]     The chair frame includes a pair of spaced apart lateral frame parts.  
         [0013]     Each of the clutches is mounted on a respective one of the lateral frame parts of the chair frame, and includes a rotary control rod.  
         [0014]     Each of the drive power sources is coupled and supplies drive power to a respective one of the clutches.  
         [0015]     Each of the drive wheels is coupled to and is driven by a respective one of the clutches.  
         [0016]     The clutch control device includes a pair of rod pivoting units, a control unit, and a flexible linking unit.  
         [0017]     Each of the rod pivoting units has a rod coupling member and a restoring component. The rod coupling member is coupled to the rotary control rod of a respective one of the clutches, and is operable so as to rotate the rotary control rod of the respective one of the clutches between a first clutch position, in which the respective one of the clutches permits transmission of the drive power from the respective one of the drive power sources to the respective one of the drive wheels, and a second clutch position, in which the respective one of the clutches is inhibited from transmitting the drive power from the respective one of the drive power sources to the respective one of the drive wheels. The restoring component is coupled to the rod coupling member for accumulating a restoring force to restore the rotary control rod of the respective one of the clutches from the second clutch position to the first clutch position.  
         [0018]     The control unit is mounted on the chair frame, and is operable between first and second control states.  
         [0019]     The flexible linking unit interconnects the control unit and the rod coupling members of the rod pivoting units such that the rotary control rods of the clutches are disposed at the first clutch position when the control unit is at the first control state, and at the second clutch position when the control unit is at the second control state. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0020]     Other features and advantages of the present invention will become apparent in the following detailed description of the preferred embodiment with reference to the accompanying drawings, of which:  
         [0021]      FIG. 1  is a fragmentary perspective view of a conventional power wheelchair;  
         [0022]      FIG. 2  is a schematic top view of  FIG. 1 ;  
         [0023]      FIG. 3  is an assembled perspective view of the preferred embodiment of a power wheelchair according to the present invention;  
         [0024]      FIG. 4  is a schematic top view of the preferred embodiment;  
         [0025]      FIG. 5  is a fragmentary exploded perspective view to illustrate a rod pivoting unit of the preferred embodiment;  
         [0026]      FIG. 6  is a fragmentary exploded perspective view to illustrate a control unit of the preferred embodiment;  
         [0027]      FIG. 7  is a fragmentary schematic sectional view to illustrate a first control state of the control unit;  
         [0028]      FIG. 8  is a fragmentary schematic top view to illustrate the rod pivoting unit when the control unit is at the first control state;  
         [0029]      FIG. 9  is a fragmentary schematic sectional view to illustrate a second control state of the control unit; and  
         [0030]      FIG. 10  is a fragmentary schematic top view to illustrate the rod pivoting unit when the control unit is at the second control state. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0031]     Referring to  FIGS. 3 and 4 , the preferred embodiment of a power wheelchair according to the present invention is shown to include a chair frame  2 , a pair of clutches  3 , a pair of drive power sources  4 , a pair of drive wheels  5 , and a clutch control device  6 .  
         [0032]     The chair frame  2  includes a pair of spaced apart lateral frame parts  21 , each of which is provided with a respective mounting plate  22 . Since the feature of the present invention does not reside in the specific configuration of the chair frame  2 , further details of the same are omitted herein for the sake of brevity.  
         [0033]     Each of the clutches  3  is mounted under the mounting plate  22  of a respective one of the lateral frame parts  21  of the chair frame  2 , and includes a rotary control rod  31  that extends upwardly through the mounting plate  22 , as best shown in  FIG. 5 . Since the clutches  3  are commercially available products, further details concerning the structure and operation thereof are dispensed with herein.  
         [0034]     Each of the drive power sources  4  is coupled and supplies drive power to a respective one of the clutches  3 . In this embodiment, each of the drive power sources  4  includes a motor.  
         [0035]     Each of the drive wheels  5  is coupled to and driven by a respective one of the clutches  3 .  
         [0036]     The clutch control device  6  includes a pair of rod pivoting units  7 , a control unit  8 , a flexible linking unit  91 , and a pair of contact switches  92 .  
         [0037]     With further reference to  FIG. 5 , each of the rod pivoting units  7  has a rod coupling member  71  and a restoring component  73 . The rod coupling member  71  is coupled to the rotary control rod  31  of a respective one of the clutches  3 , and is operable so as to rotate the rotary control rod  31  of the respective one of the clutches  3  between a first clutch position, in which the respective one of the clutches  3  permits transmission of the drive power from the respective one of the drive power sources  4  to the respective one of the drive wheels  5 , and a second clutch position, in which the respective one of the clutches  3  is inhibited from transmitting the drive power from the respective one of the drive power sources  4  to the respective one of the drive wheels  5 . The restoring component  73  is coupled to the rod coupling member  71  for accumulating a restoring force to restore the rotary control rod  31  of the respective one of the clutches  3  from the second clutch position to the first clutch position.  
         [0038]     Each of the contact switches  92  is mounted on the mounting plate  22  of a respective one of the lateral frame parts  21 , and is disposed adjacent to and is triggered by the rod coupling member  71  of a respective one of the rod pivoting units  7  to generate a disable signal for a corresponding one of the drive power sources  4  when the rotary control rod  31  coupled to the rod coupling member  71  is moved to the second clutch position.  
         [0039]     In this embodiment, the rod coupling member  71  of each of the rod pivoting units  7  includes a sleeve part  711  that is disposed above the mounting plate  22  of a respective one of the lateral frame parts  21  and that is coupled co-rotatably to the rotary control rod  31  of the respective one of the clutches  3 , a fan-shaped guide part  712  connected to and extending horizontally and outwardly from the sleeve part  711  and further connected to the flexible linking unit  91 , and an actuator part  72  projecting outwardly from the sleeve part  711  and disposed to trigger the respective one of the contact switches  92  when the rotary control rod  31  coupled to the rod coupling member  71  is moved to the second clutch position. The guide part  712  is formed with a peripheral curved guide groove  713 .  
         [0040]     The restoring component  73  of each of the rod pivoting units  7  is in the form of a torsion spring in this embodiment, is sleeved on the sleeve part  711  of the rod coupling member  71 , and has an anchoring end  731  anchored to the mounting plate  22  on a respective one of the lateral frame parts  21 , and a restoring end  732  opposite to the anchoring end  731 . Each of the rod pivoting units  7  further includes an end cap  74  coupled to the restoring end  732  of the restoring component  73 , and a fastener  75  for fastening the end cap  74  to the sleeve part  711  of the rod coupling member  71  such that the restoring end  732  of the restoring component  73  is rotatable together with the end cap  74  and the rod coupling member  71  relative to the anchoring end  731 .  
         [0041]     Referring to  FIG. 6 , the control unit  8  is mounted on the chair frame  2 , and is operable between first and second control states. The control unit  8  includes a control base  81  mounted on the chair frame  2 , a control lever  82  connected to the flexible linking unit  91 , and a pivot axle  83  that mounts pivotally the control lever  82  to the control base  81  such that the control lever  82  is operable to dispose the control unit  8  at a selected one of the first and second control states (to be described in greater detail in the succeeding paragraphs).  
         [0042]     The control base  81  includes a pair of spaced apart pivot lugs  811  that are mounted fixedly on the chair frame  2 . Each of the pivot lugs  811  has a curved lever engaging edge  814  formed with a pair of first and second engaging grooves  812 ,  813  that are angularly spaced apart from each other relative to the pivot axle  83 . The first engaging grooves  812  of the pivot lugs  811  engage removably the control lever  82  when the control unit  8  is disposed at the first control state (see  FIG. 7 ). The second engaging grooves  813  of the pivot lugs  811  engage removably the control lever  82  when the control unit  8  is disposed at the second control state (see  FIG. 9 ).  
         [0043]     The control lever  82  includes a tube body  821  that has a tube wall  8211  with opposite first and second tube ends  8212 ,  8213 . The first tube end  8212  is mounted pivotally to the pivot lugs  811  by the pivot axle  83 . The tube wall  8211  is formed with a guide slot unit  823  along a length thereof. The control lever  82  further includes a fan-shaped guide body  822  connected to the first tube end  8212  and further connected to the flexible linking unit  91 , a pull rod  84  movably disposed in the tube body  821 , a locking pin  85  extending through the pull rod  84  and the guide slot unit  823  and movable along the guide slot unit  823 , a biasing member  86  for biasing the pull rod  84  toward the pivot axle  83  to enable the locking pin  85  to engage a selected pair of the first and second engaging grooves  812 ,  813  of the pivot lugs  811 , and a handle  87  that is disposed outwardly of the tube body  821  and proximate to the second tube end  8213 , that is connected to the pull rod  84 , and that is operable so as to pull the pull rod  84  against biasing action of the biasing member  86  for disengaging the locking pin  85  from the first and second engaging grooves  812 ,  813 . The guide body  822  preferably has a curved outer surface formed with a pair of spaced apart guide furrows  824 . In this embodiment, the biasing member  86  is a compression spring that is disposed in the tube body  821 .  
         [0044]     The flexible linking unit  91  interconnects the control unit  8  and the rod coupling members  71  of the rod pivoting units  7  such that the rotary control rods  31  of the clutches  3  are disposed at the first clutch position when the control unit  8  is at the first control state, and at the second clutch position when the control unit  8  is at the second control state. The flexible linking unit  91  includes a pair of flexible components  911  (see  FIGS. 3 and 4 ), each of which extends between the control unit  8  and the rod coupling member  71  of a respective one of the rod pivoting units  7 . Each flexible component  911  includes a front connecting member  912  (see  FIG. 6 ) mounted fixedly on the chair frame  2  adjacent to the guide body  822  of the control lever  82 , a rear connecting member  913  (see  FIG. 5 ) mounted fixedly on the mounting plate  22  of a respective one of the lateral frame parts  21  of the chair frame  2  adjacent to the guide part  712  of the rod coupling member  71  of the respective one of the rod pivoting units  7 , a sheath  914  (see  FIGS. 5 and 6 ) that interconnects the front and rear connecting members  912 ,  913 , a flexible steel wire  915  (see  FIGS. 5 and 6 ) movably extending through the sheath  914 , a front end block  916  (see  FIG. 6 ) fixed to the guide body  822  of the control lever  82  and connected to one end  918  of the steel wire  915 , and a rear end block  917  (see  FIG. 5 ) fixed to the guide part  712  of the rod coupling member  71  of the respective one of the rod pivoting units  7  and connected to the other end  919  of the steel wire  915 . The end  918  of the steel wire  915  is guided by one of the guide furrows  824  in the guide body  822  of the control lever  82 . The end  919  of the steel wire  915  is guided by the guide groove  713  in the guide part  712  of the rod coupling member  71  of the respective one of the rod pivoting units  7 .  
         [0045]     As shown in  FIGS. 7 and 8 , when the control unit  8  is at the first control state, the locking pin  85  of the control lever  82  engages the first engaging grooves  812  of the control base  81 , and the restoring components  73  bias the rod coupling members  71  of the rod pivoting units  7  such that the rotary control rods  31  of the clutches  3  are disposed at the first clutch position. The actuator parts  72  of the rod coupling members  71  do not trigger the contact switches  92  at this time, thereby enabling power driving of the power wheelchair.  
         [0046]     As shown in  FIGS. 9 and 10 , when the control unit  8  is operated to the second control state such that the locking pin  85  of the control lever  82  engages the second engaging grooves  813  of the control base  81 , the steel wires  915  pull the rod coupling members  71  of the rod pivoting units  7  to rotate against the biasing action of the restoring components  73 , thereby disposing the rotary control rods  31  of the clutches  3  at the second clutch position. At this time, the actuator parts  72  of the rod coupling members  71  trigger the contact switches  92  for disabling the drive power sources  4 , thereby enabling manual driving of the power wheelchair.  
         [0047]     Unlike the conventional power wheelchair, the clutch control device  6  utilizes the flexible linking unit  91  to interconnect the control unit  8  and the rod coupling members  71 . As a result, spatial design of the power wheelchair of this invention has greater flexibility, and the total weight of the clutch control device  6  is reduced considerably.  
         [0048]     While the present invention has been described in connection with what is considered the most practical and preferred embodiment, it is understood that this invention is not limited to the disclosed embodiment but is intended to cover various arrangements included within the spirit and scope of the broadest interpretation so as to encompass all such modifications and equivalent arrangements.