Patent Publication Number: US-6907945-B2

Title: Wheel chair

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a wheel chair, and more particularly to a wheel chair capable of easily ascending or descending obstacles or stairs, and enabling a user to always have a stable posture. 
   2. Description of the Related Art 
   Generally, patients or handicapped persons who do not behave by the force of his/her will utilize a wheel chair to move or travel. Such wheelchairs include a wheel frame having a seating part allowing a user to keep a seating posture. The wheel frame is provided with a rear wheel of a relatively large diameter. The rear wheel may be manually driven by a hand of the user or automatically driven by a separate actuator. In addition, the wheel frame is provided at a front thereof with a front wheel for stably maintaining the wheel frame. 
   With the structure of the conventional wheelchair as described above, the wheels are only rotated by an axle or driving shaft. Accordingly, the wheel chair may move on a level ground or easily go over the obstacle of a restricted height, without difficulty. During moving on the sands or marshy ground, or going over a high obstacle (in particular, the stairs), there is a problem in that the wheel idles or does not go over the obstacle. 
   In case of moving on a slope, since the user leans corresponding to the inclination of the slope, the user may not maintain the stable seating posture. 
   In case of the automatic-type wheel chair utilizing the actuator or motor, when the wheel chair is manually driven in case it is out of order, since the user rotates the rear wheel by holding it, thereby requiring excessive power. 
   In addition, in case of reinforcing or improving the function of the wheel chair, since the number of components is increased, the cost is expensive and the weight is increased. 
   SUMMERY OF THE INVENTION 
   Therefore, an object of the present invention is to solve the problems involved in the prior art, and to provide a wheel chair capable of easily ascending or descending obstacles or stairs. 
   Another object of the present invention is to provide a wheel chair capable of enabling a user to always have a stable posture when moving on a slope. 
   A further object of the present invention is to a wheel chair capable of enabling a user to easily manually drive it when power supply is interrupted. 
   A still object of the present invention is to a lightweight wheel chair having a simplified construction. 
   In order to accomplished the above mentioned objects, the present invention provides a wheel chair capable of going over an obstacle or ascending or descending a stair, the wheelchair comprising: a wheel frame having a seat on which a user sits; an actuator coupled to the wheel frame for supplying driving force; a power generating unit having a main shaft coupled to the actuator; a first transmission having a sun gear fixed to the main shaft, a plurality of planet gears meshed with the sun gear and rotating or revolving in accordance with applied load, a ring gear meshed with the respective planet gears, and carriers coupled to the respective planet gears and rotated by the planet gears; a second transmission having a driving shaft meshed with the ring gear of the first transmission, a key frame rotatably installed on the driving shaft, coupled to the carrier, and serving as a role of a center shaft during a step operation, and a casing fixed to the key frame; a plurality of front wheels each coupled to the driving shaft of the second transmission and fixed to rotating shafts each rotatably fixed to the casing; a follower drivingly coupled to the driving shaft and the key frame and having a follower shaft to which the wheel frame is fixed; and a rear wheel fixed to an end of the follower shaft of the follower. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above objects, other features and advantages of the present invention will become more apparent by describing the preferred embodiment thereof with reference to the accompanying drawings, in which: 
       FIG. 1  is a schematic view for illustrating of a half section of the entire driving unit of a wheel chair according to one preferred embodiment of the present invention. 
       FIG. 2  is a cross sectional view of the front-wheel driving section shown in FIG.  1 . 
       FIG. 3  is a cross sectional view of the rear-wheel driving section shown in FIG.  1 . 
       FIG. 4  is a partially cross sectional view of an upper portion of a real-wheel manually driving unit according to one embodiment of the present invention. 
       FIG. 5  is a cross sectional view of gears and latches of one rear-wheel manually driving unit. 
       FIG. 6  is a cross sectional view of gears and latches of another rear-wheel manually driving unit. 
       FIG. 7  is a side view of an upper portion of the real-wheel manually driving unit shown in FIG.  6 . 
       FIG. 8  is a schematic view of a seat according to one preferred embodiment of the present invention. 
       FIG. 9  is a view for the varying seat shown in FIG.  8 . 
       FIG. 10  is a side view of auxiliary driving means for a front wheel. 
       FIG. 11  is a side view of the state in which the auxiliary wheel shown in  FIG. 10  is developed. 
       FIG. 12  is a front view of the auxiliary wheel shown in FIG.  11 . 
       FIG. 13  is a front view of the entire front-wheel frame. 
       FIG. 14  is a side view for showing the entire construction of wheel chair according to the present invention. 
       FIG. 15  is a schematic view for illustrating of a half section of the entire driving unit of a wheel chair according to another preferred embodiment of the present invention. 
       FIG. 16  is a partially enlarged sectional view of a front-wheel driving section of the driving unit of the wheel chair shown in FIG.  15 . 
       FIG. 17  is a schematic view for illustrating of a half section of the entire driving unit of a wheel chair according to a still preferred embodiment of the present invention. 
       FIG. 18  is a partially enlarged sectional view of a front-wheel driving section of the driving unit of the wheel chair shown in FIG.  17 . 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Reference will now be made in detail to first and second preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. For the clarity, a half section of the driving unit is shown in detail. In addition, a term related to a direction hereinafter is one determined when viewing at front from the drawings, and the scope of the present invention is not limited thereto. 
   Referring to  FIGS. 1  to  2  and  10 , a wheel chair of the present invention includes a wheel frame  12  having a seat  10  on which a user sits. The wheel frame  12  is provided with an actuator  14 , such as a combustion engine or an electric motor, for supplying a driving power. 
   As shown in  FIG. 2 , the actuator  14  is coupled to a power generating unit  16  for driving the wheel chair. The power generating unit  16  includes a main shaft  18  such as an axle, and preferably, the main shaft  18  is provided at an end thereof with a pulley  20  connected to the actuator  14  through a connecting member such as a belt or chain. 
   The main shaft  18  includes a first transmission  22  for transmitting the driving force in accordance with the drive of the main shaft. Preferably, the first transmission  22  includes sun and planet gears. Specifically, the first transmission includes a sun gear  24  fixed to the main shaft  18 , a plurality of planet gears  26  meshed with the sun gear  24 , and another sun gear, i.e., a ring gear  28 , meshed with the respective planet gears  26 . The plurality of planet gears  26  rotates on its axis according to the rotation of the sun gear  24 , or revolves according to the load. Preferably, the ring gear  28  is formed with teeth on inner and outer peripheries thereof. 
   The first transmission  22  is provided with a carrier  30  accommodating the main shaft  18  therein, with the carrier being no contact with the main shaft  18 . The carrier includes a plurality of supporting shafts  32  which are coupled to each other via bearings to idle the planet gears  26 . In particular, the carrier is provided with at an end thereof with a pulley  34 . 
   Also, the first transmission  22  is provided with a second transmission  36 . The second transmission  36  includes a driving gear  36  meshed with the teeth formed on the outer periphery of the ring gear  28  of the first transmission  22 . The driving gear  38  is provided with a driving shaft  40  penetrating and fixed to a center thereof. The driving shaft  40  has at one end thereof a pulley  44  coupled to a rear wheel described hereinafter via a belt  42 , and at the other end thereof two sprockets  46  and  48 . The driving shaft  40  is rotatably inserted in a cylindrical key frame  50  serving as a role of a center shaft during a step operation, with a bearing interposed between them. Also, the key frame  50  includes two pulleys, i.e., a first pulley  52  and a second pulley  54 . The first pulley  52  is coupled to the pulley  34  provided at the end of the carrier  30  via a belt  56 , while the second pulley  54  is coupled to an axle of the rear wheel described hereinafter via a belt  58 . The key frame  50  of the second transmission  36  is provided with a casing  60  for providing a sufficient space. 
   A first front wheel  64  is rotatably installed in the casing  60  by a rotating shaft  62 . The rotating shaft  62  has a sprocket  66  which is coupled to the sprocket  46  provided at the end of the driving shaft  40  via a chain  68 . 
   A second front wheel  72  is rotatably installed in the casing  60  by a rotating shaft  70 . The rotating shaft  70  has a sprocket  74  which is coupled to the sprocket  48  provided at the end of the driving shaft  40  via a chain  76 . 
   Also, a third front wheel  73  is rotatably installed in the casing  60  by a rotating shaft  73 . The rotating shaft  71  has a sprocket (not shown) which is coupled to a sprocket  49  provided at the end of the driving shaft  40  via a chain. 
   With the structure as described above, a rotating direction of the driving shaft  40  is transferred to the rotating shaft without changing the rotation direction, so that the respective front wheels  64 ,  72  and  73  may be rotated in the same direction. Although the embodiment having three front wheels is described, two or four front wheels which are operated in the same manner as the case of three front wheels as described above may be provided. 
   The power generating unit  16  for driving the front wheels  64 ,  72  and  73  includes a follower  78  for driving the rear wheel. The follower  78  includes a follower shaft  82  rotatably fixed to a bracket  80  supporting the wheel frame. The follower shaft  82  is provided at one end thereof with a follower pulley  84  coupled to the pulley  44  of the driving shaft  40  via a main shaft belt  42 . Preferably, the follower pulley  84  is constructed to be loaded upon the forward drive only. To this end, the follower pulley  84  may have an advance clutch bearing  86 . 
   The follower shaft  82  is provided at other end thereof with another follower pulley  88  coupled to the pulley  54  of the key frame  50  via a key belt  58 . Preferably, the follower pulley  88  is constructed to be loaded upon the forward drive only. To this end, the follower pulley  88  may have an advance clutch bearing  90 . In particular, the key belt  58  may be supported by a tension pulley  92  mounted on the wheel frame  12 , so that it can be manually manipulated by the user to release the load upon the reverse. 
   The follower shaft  82  of the follower  78  is provided at an end thereof with a rear wheel  94  of a large diameter actually governing the drive of the wheelchair. The rear wheel  94  is provided at inner periphery with a brake lining  96  for braking the rear wheel. 
   Alternatively, the follower  78  may be provided with a manually driving unit  97  for manually driving the rear wheel at impossible transmission or emergency situation. The manually driving unit  97  includes two gears fixed to the follower shaft  82  interposed between the brackets  80 . Specifically, a first gear  98  is used for the advance of the rear wheel, while a second gear  100  is used for the reverse of the rear wheel. An end of a lever  102  operable by a hand of the user is installed on the follower shaft  82  between the first and second gears  98  and  100 . A guide  104  is fixed in a proper position of the lever  102 , and a supporter  106  is fixed on an upper portion of the guide  104 . 
   In particular, the guide  104  has on one side thereof a first latch  108  reciprocately movable up and down and meshed with a first gear  98  to forwardly rotate the first gear. The first latch  108  is urged against the support  106  by a spring  110 . The first latch  108  is coupled to a first handle  114  through a first coupling member  112 . Similarly, the guide  104  has on the one side thereof a second latch  1116  reciprocately movable up and down and meshed with a second gear  100  to forwardly rotate the second gear. The second latch  116  is urged against the support  106  by a spring  118 . The second latch  116  is coupled to a second handle  122  through a second coupling member  120 . 
   In addition, the lever  102  is provided on an upper portion thereof with a pivoting piece  124 . The first handle  114  is secured to one end of the pivoting piece  124 , and the second handle  122  is secured to the other end thereof, so that the respective handles is moved up and down in opposed direction. 
   As shown in  FIG. 5 , the respective gears has tooth grooves formed in a n opposed direction to each other, thereby easily rotating the gears. Specifically, the first gear  98  is formed with a tooth groove  98   a  with a vertical front and an acute rear, while the second gear is formed with a tooth groove  100   a  with an acute front and a vertical rear. In addition, the first latch  108  and the second latch  116  preferably have a shape corresponding to the respective tooth grooves  98   a  and  100   a  formed at the first and second gears  98  and  100 . 
   Alternatively, a manually driving unit  84 ′ includes, as shown in  FIGS. 6 and 7 , first and second horizontal latches  108 ′ and  116 ′. A first handle  114 ′ and a second handle  122 ′ each coupled by a coupling member are installed in a cross manner to each other on a lever  102 ′, which is different from the manually driving unit shown in  FIGS. 4 and 5 . Other components  110 ′,  112 ′,  106 ′,  118 ′,  120 ′ and so forth are similar to those shown in  FIGS. 4 and 5 , and thus the detailed description thereof will be omitted for its clarity. 
   As shown in  FIG. 8 , a seat  10  provided at the wheel frame  12  of the wheelchair according to the present invention is adapted to have a stable posture, since a seating angle is automatically changed in accordance with an inclination of the wheel chair and a user&#39;s intension. Specifically, the seat  10  includes a base  126  provided on the upper portion of the wheel body, a front member  130  rotatably coupled to a front of the base  126  by a hinge  128 , a rear member  134  rotatably coupled to a rear of the base  126  by a hinge  132 , a seating member  140  having one end foldably fixed to an upper portion of the front member  130  by a hinge  136  and the other end foldably fixed to an upper portion of the rear member  134  by a hinge  138 , and a seat back  142  having one side fixed to a rear of the seating member  140 . With the construction, as shown in  FIG. 9 , when the wheel chair on which the seat  10  is mounted moves on a level ground, ascends or descends a slope, since a center of gravity of the user always is toward the center of the base  126 , the user may keep his/her seating posture stably. The user may adjust the seating angle of the seat by optionally regulating the inclination of the respective members by use of the hinge or hinges. 
   As shown in  FIGS. 10 and 11 , the wheel chair of the present invention includes an auxiliary driving unit  144  for manually driving the wheel chair at the interruption of the power supply or emergency situation. The auxiliary driving unit  144  includes a supporting member  148  rotatably fixed to the wheel frame  12  by a hinge  146 , and an auxiliary wheel  150  rotatably fixed to the supporting member  148 . A lever  152  is hingedly installed to the auxiliary driving unit  144  for rotating the supporting member  148  so as to that the auxiliary wheel  150  is contact with the ground. Preferably, the lever  152  is provided with a handle  154  extending to the side of the wheel frame so that the user may easily control the lever  152 . 
   Preferably, the wheel frame  12  of the wheel chair according to the present invention consists of a front-wheel frame  156  and a rear-wheel frame  158 , as shown in  FIGS. 10  to  13 . In particular, the front-wheel frame  156  is preferably coupled to the rear-wheel frame  158  by a joint  160 . The rear-wheel frame  156  is jointed to the rear-wheel frame  158 , so that the front-wheel frame  156  may be swiveled left and right relative to the rear-wheel frame  158 . Therefore, when the wheel chair moves on an irregular or curved pavement, the wheel frame may be stably maintained. 
   Alternatively, as shown in  FIGS. 15 and 16 , according to the wheel chair of another preferred embodiment of the present invention, in order to directly transfer the power, which is supplied from the actuator  14  to the main shaft  18 , to the follower shaft  82  of the follower  78 , the pulley  20  of the main shaft  18  is directly coupled to the follower pulley  84  of the follower pulley  84 . In this case, the pulley  44  provided at the end of the driving shaft  40  will be eliminated or omitted, while it may be rotatably mounted on an outer body or housing. 
   As shown in  FIGS. 17 and 18 , according to a wheel chair of another preferred embodiment of the present invention, the entire construction of the wheel chair will be simplified, as well as the driving unit of the wheelchair. In addition, a part of the components described above will be eliminated to reduce its weight. As another preferred embodiment shown in  FIGS. 15 and 16 , since the pulley  20  of the main shaft  18  is directly coupled to the follower pulley  84  of the follower shaft  82  to directly transfer the power, the second pulley  54  of the key frame  50 , the belt  58 , the tension pulley  92 , and the follower pulley  88  of the follower  78  will be eliminated, as well as the pulley of the driving shaft  40 . Therefore, the driving unit will be simplified, and the light wheel chair will be achieved. 
   The operation of the wheel chair according to the present invention will be described in detail with reference to  FIGS. 1  to  14 . 
   In case that the wheel chair including the driving unit of the present invention moves on the level ground or a lower obstacle, the actuator  14  such as a motor is actuated to generate the power, and the main shaft  18  is rotated by the generated power through the main pulley  20 . The sun gear  24  mounted on the main shaft is rotated in a counterclockwise, and the plurality of planet gear  26  meshed with the sun gear  24  are rotated themselves in a clockwise. Accordingly, the ring gear  28  is rotated in the clockwise. If the ring gear  28  is rotated, the driving gear  38  of the second transmission  36  meshed with the ring gear  28  is rotated, and simultaneously the driving shaft  40  is rotated. If the driving shaft  40  is rotated, the rotating force is transferred to the respective rotating shafts  62 ,  70  and  71  through the sprocket  46 ;  48 ;  49 , the chain  68 ;  76  and the sprocket  66 ;  74 , to drive the wheels  64 ,  72  and  73  for advancing the wheel chair. In addition, if the pulley  44  of the driving shaft is rotated by the rotation of the driving shaft  40 , the follower pulley  84  coupled to the pulley  44  via the main belt  42  is rotated to rotate the rear wheel. 
   In case that the wheelchair ascends or descends the stairs or the steep slope in a step mode, the pulley  34  of the carrier  30  and the pulley  52  of the key frame  50  are rotated by the belt  56  to rotate the key frame  50 . Accordingly, the casing  60  is rotated, so that the step drive may be achieved by going one front wheel over another front wheel. At that time, since the pulley  54  of the key frame  50  is coupled to the follower pulley  88  of the follower shaft  82  via the belt  58 , the rear wheel  94  may be driven, so that the entire wheel chair may be stably and easily driven. The respective follower pulleys  84  and  88  has the clutch bearing  86 ;  90  for applying the load at the forward rotation, thereby stably driving the rear wheel  94 . 
   The driving mode described above is disclosed in Korean Patent Application No. 10-0053982 entitled “Driving apparatus” filed Nov. 30, 1999 and assigned to the applicant of the present invention, the teachings of which are hereby incorporated by reference. 
   If the actuator  14  is counter-rotated to reverse the wheel chair, the operation as described above happens in reverse order to the above mentioned-process, thereby reversing the wheel chair and adversely processing the step drive. At that time, preferably, the tension pulley  92  is manually released from the belt  58  to release the load applied to the belt  58 , so that it facilitates the reverse of the wheel chair. 
   In case that during the drive the transmission is interrupted or the rear wheel has to be manually driven, the user utilizes the manually driving unit  97 . Specifically, when the user advances the rear wheel, in state the second handle  122  is pulled to insert the end of the first latch  108  into the tooth groove  98   a  of the first gear  98 , if the lever  102  is pulled, the follower shaft  82  is rotated together with the first gear  98  in the front direction, thereby manually advancing the wheel chair. By the contrary, when the rear wheel manually reserves the wheel chair, in state the first handle  114  is pulled to insert the end of the second latch  116  into the tooth groove  100   a  of the second gear  100 , if the lever  102  is pushed, the follower shaft  82  is rotated together with the second gear  100  in the rear direction, thereby manually reversing the wheel chair. Although the manually driving mode is described with reference to  FIGS. 4 and 5 , the manual drive may be achieved by use of the manually driving unit having the construction shown in  FIGS. 6 and 7 . 
   The seat  10  of the wheelchair according to the present invention may maintain the constantly stable posture by automatically changing the seating angle depending upon the inclination of the pavement. In particular, the seat  10  according to the present invention is preferably formed in an inverted-trapezoidal shape so that the user can have the best stable posture, as shown in FIG.  8 . In case the wheel chair ascends the slope or stairs in the advance direction, the respective components are maintained at a proper angle by the hinges  128 ,  132 ,  136  and  138  each connecting the base  126 , the front member  130 , the rear member  134  and the seating member  140 , so that the user may maintain his/her posture stably. For example, the shape of the maximally adjusted seat when ascending forwardly is shown in a solid line in FIG.  9 . On contrary, the shape of the maximally adjusted seat when descending forwardly is shown in a dotted line in FIG.  9 . Of course, in case of reversing, the shape of the seat has a shape contrary to that as described above. In any cases, since the center of gravity of the user is toward the center of the base  126 , the user can maintain his/her seating posture stably. 
   The wheel chair of the present invention may be temporarily driven by use of the auxiliary driving unit at the interruption of the power supply or emergency situation. Specifically, if the handle  154  is pulled to rotate the lever  152  at the emergency stop of the wheel chair, the supporting member  148  is developed, and the auxiliary wheel  150  is contact with the ground. Simultaneously, the respective front wheels are slightly spaced apart from the ground. At that state, the user may drive the wheel chair by driving the rear wheel with his/her hands or the manually driving unit. 
   The wheel frame  12  of the present invention includes the front-wheel frame  156  and the rear-wheel frame  158  which are coupled by the joint. When the wheel chair moves on the irregular or curved pavement, the front-wheel frame  156  may be swiveled left and right relative to the rear-wheel frame  158 , as shown in  FIG. 13 , so that the stable posture of the wheel frame may be always maintained. 
   As shown in  FIGS. 15  to  18 , in case the pulley  20  of the main shaft  18  is directly coupled to the follower pulley  84  of the follower shaft  82 , the power supplied to the main shaft  18  from the actuator  14  is directly transferred to the follower shaft  82  of the follower  78  without passing through a separate transmission, thereby simultaneously driving the front and rear wheels. In particular, in case the main shaft  18  and the follower shaft  82  are directly coupled to each other, the wheel chair may smoothly rotate in 360 degrees. 
   Therefore, the wheelchair may effectively and stably transfer the user, regardless of the traveling topography. 
   While the present invention has been described and illustrated herein with reference to the preferred embodiments thereof, it will be apparent to those skilled in the art that various modifications and variations can be made therein without departing from the spirit and scope of the invention. Thus, it is intended that the present invention covers the modifications and variations of this invention that come within the scope of the appended claims and their equivalents. 
   As apparent from the above description, the wheel chair according to the present invention, it may ascend or descend the slope or stairs, as well as moving on the level ground, thereby improving the reliability. 
   The seating angle of the seat may be changed dependent upon the inclination or topography, thereby improving the reliability and convenience of the user. 
   In addition, the rear wheel may be manually driven at the interruption of the power supply, the wheel chair may be traveled by use of the auxiliary wheels in state the front wheel is spaced apart from the ground, and the front-wheel frame may be swiveled left and right relative to the rear-wheel frame, thereby facilitating the steering and drive of the wheel chair. 
   Furthermore, since the main shaft of the power generating unit and the follower shaft of the follower are directly coupled to each other, the additional components will be eliminated, while the wheelchair will be driven without losing the driving force. The wheel chair may be smoothly rotated in a stop state, and the simplified construction allows the weight to be decreased.