Abstract:
A wheelchair has actuation plates provided in juxtaposition with the seat to descend when a user sits on the seat to lower the seat with the user&#39;s weight and to ascend when the user rises from the seat to permit the seat to return with removal of the weight. A brake is mounted on the axle shafts to brake the axle shafts and energized constantly in a non-braking direction. Levers are coupled directly or indirectly to the brake to move according to descending motions of the actuation plates to put the brake in a non-braking state and to move according to ascending motions of the actuation plates to put the brake in a braking state. Biasing devices for evacuating legs that extend from the seat and/or steps that are mounted onto the legs.

Description:
BACKGROUND OF THE INVENTION 
   The present invention relates to a wheelchair. 
   DESCRIPTION OF THE RELATED ART 
   With conventional wheelchairs, there is a need of manually braking a wheelchair when a user goes away from the wheelchair. Therefore, in the case where a user goes away from a wheelchair failing to apply braking, there is a possibility that the wheelchair begins to move the moment the user puts a hand or hands on the wheelchair trying to move the user&#39;s body weight to the wheelchair again. 
   Conventionally, the following wheelchair is known as solving such problem. The wheelchair comprises a metallic sheet stopper, which is cut to afford meshing with a spoke of a rear wheel. A detector is mounted below a central portion of a seat to actuate the stopper. When a user rises from the wheelchair, the seat having sunk due to weight ascends and the detector detects such ascent. Based on the detecting action, the cut in the stopper meshes with the spoke of the rear wheel and the rear wheel is made stationary to apply braking. Also, when the user sits and the user&#39;s body weight is applied on the seat to lower the seat, a signal from the detector causes the stopper to separate from the spoke of the rear wheel to release braking. 
   With the wheelchair with an automatic brake according to the prior art, however, when a user rises from the wheelchair and the stopper is not positioned in opposition to a spoke, rear wheels will rotate until a next spoke comes to a position of the stopper. That is, “idle time” is generated in the meantime and the wheelchair freely runs to become unstable. Also, since the stopper meshes with a spoke of the rear wheels to apply braking, large forces concentrate on a spoke made of a thin metallic bar. Therefore, there is involved a problem that spokes are liable to break in repeated use. 
   Also, steps are mounted on all wheelchairs and get in the way forwardly of a course to obstruct beginning of walking when a user gets off a wheelchair to begin walking, so that it is necessary to remove steps to positions not to obstruct a user&#39;s course before the user begins walking. With conventional wheelchairs, a user must bend forward exceedingly to spring up the steps with hands, or with feet. 
   In addition, although not related to the gist of the invention, for example, JP-A-5-103815 and JP-A-7-232646 are enumerated to disclose a brake device for wheelchairs. 
   SUMMARY OF THE INVENTION 
   It is an object of the invention to provide a wheelchair with an automatic brake, in which braking is applied the moment a user rises, and which is excellent in safety. 
   To achieve the above object, the present invention provides a wheelchair. The wheelchair includes a seat, a pair of rear wheels fixed to axle shafts arranged below the seat and arranged outside both sides of the seat, a grasping portion arranged rearwardly of the seat to be grasped and operated by a helper, at least one front wheel arranged forwardly of the axle shafts. Actuation plates provided in juxtaposition with the seat to descend when a user sits on the seat to lower the seat with the weight and to ascend when the user rises from the seat to permit the seat to return with removal of the weight. Brake means mounted on the axle shafts to brake the axle shafts and energized constantly in a non-braking direction. Levers coupled directly or indirectly to the brake means to move according to descending motions of the actuation plates to act on the brake means to put the brake means in a non-braking state and to move according to ascending motions of the actuation plates to act on the brake means to put the brake means in a braking state. The user sits on the seat, the user&#39;s body weight causes the seat to descend and the actuation plates to move downward and positional movements of the actuation plates cause the levers to move to release braking on the axle shafts by the brake means, and when the user having sat on the seat rises, the actuation plates having been pushed down by the user&#39;s body weight move upward and positional movements of the actuation plates cause the levers to move to permit the brake means to brake the axle shafts. 
   A further aspect of the present invention is a wheelchair including a seat, a pair of rear wheels fixed to axle shafts arranged below the seat and arranged outside both sides of the seat, a grasping portion arranged rearwardly of the seat to be grasped and operated by a helper, at least one front wheel arranged forwardly of the axle shafts, legs extended forward and downward from the seat, steps mounted on the legs. Actuation plates provided in juxtaposition with the seat to descend when a user sits on the seat to lower the seat with the weight and to ascend when the user rises from the seat to permit the seat to return with removal of the weight. Brake means mounted on the axle shafts to brake the axle shafts and energized constantly in a non-braking direction. Levers coupled directly or indirectly to the brake means to move according to descending motions of the actuation plates to act on the brake means to put the brake means in a non-braking state and to move according to ascending motions of the actuation plates to act on the brake means to put the brake means in a braking state. The legs being turnably supported horizontally in base positions and biased in one directions of turning by second bias means. Position holding means for holding the legs in positions. The steps are used, against the bias of the second bias means and released from a holding state as the actuation plates move upward, and wherein when the user sits on the seat, the user&#39;s body weight causes the seat to descend and the actuation plates to move downward and positional movements of the actuation plates cause the levers to move to release braking on the axle shafts by the brake means, and when the user having sat on the seat rises, the actuation plates having been pushed down by the user&#39;s body weight move upward and positional movements of the actuation plates cause the levers to move to permit the brake means to brake the axle shafts and the holding state by the position holding means is released to cause the bias of the second bias means to evacuate the legs. 
   A further aspect of the present invention is a wheelchair including a seat, a pair of rear wheels fixed to axle shafts arranged below the seat and arranged outside both sides of the seat, a grasping portion arranged rearwardly of the seat to be grasped and operated by a helper, at least one front wheel arranged forwardly of the axle shafts, legs extended forward and downward from the seat, steps mounted on the legs. Actuation plates provided in juxtaposition with the seat to descend when a user sits on the seat to lower the seat with the weight and to ascend when the user rises from the seat to permit the seat to return with removal of the weight. Brake means mounted on the axle shafts to brake the axle shafts and energized constantly in a non-braking direction. Levers coupled directly or indirectly to the brake means to move according to descending motions of the actuation plates to act on the brake means to put the brake means in a non-braking state and to move according to ascending motions of the actuation plates to act on the brake means to put the brake means in a braking state, the steps being turnably supported in base positions and biased in one directions of turning by third bias means. Position holding means for holding the steps in positions. The steps are used, against the bias of the third bias means and released from a holding state as the actuation plates move upward, and wherein when the user sits on the seat, the user&#39;s body weight causes the seat to descend and the actuation plates to move downward against the first bias means and positional movements of the actuation plates cause the levers to move to release braking on the axle shafts by the brake means, and when the user having sat on the seat rises, the actuation plates having been pushed down by the user&#39;s body weight move upward by the first bias means and positional movements of the actuation plates cause the levers to move to permit the brake means to brake the axle shafts and the holding state by the position holding means is released to cause the bias of the third bias means to evacuate the steps. 
   Other aspects and advantages of the present invention will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a side view showing an embodiment of a wheelchair with an automatic brake according to the invention when a left side of a wheelchair body in a state, in which a user sits on a seat, is viewed from inside; 
       FIG. 2  is a perspective view showing an essential part of  FIG. 1  as viewed from obliquely downward and inside of a rear side; 
       FIG. 3  is a side view showing an embodiment of a wheelchair with an automatic brake according to the invention when a left side of a wheelchair body in a state, in which a user goes away from a seat, is viewed from inside; 
       FIG. 4  is a perspective view showing an essential part of  FIG. 3  as viewed from obliquely downward and inside of a rear side; 
       FIG. 5  is a perspective view showing an essential part of  FIG. 3  as viewed from forwardly downward and inside; 
       FIGS. 6A and 6B  show a control device of an automatic step opening mechanism housed in a horizontal strut of a step holding leg, or in a lower portion of the step holding leg,  FIG. 6A  being a cross sectional view showing a state, in which a stopper projects, and  FIG. 6B  being a cross sectional view showing a state, in which the stopper withdraws; 
       FIG. 7  is a side view showing a further embodiment of a wheelchair with an automatic brake according to the invention when a left side of a wheelchair body in a state, in which a user sits on a seat, is viewed from inside; 
       FIG. 8  is a side view showing a still further embodiment of a wheelchair with an automatic brake according to the invention when a left side of a wheelchair body in a state, in which a user goes away from a seat, is viewed from inside; 
       FIGS. 9A and 9B  show a still further embodiment of a wheelchair with an automatic brake according to the invention,  FIG. 9A  being a perspective view showing a left side of an essential part of a wheelchair body in a state, in which a user sits on a seat, as viewed from obliquely rearward and inside, and  FIG. 9B  being a schematic side view showing only related portions for the purpose of explaining the function of the embodiment; and 
       FIGS. 10A and 10B  show a state, in which a user goes away from a seat,  FIG. 10A  being a perspective view similar to  FIG. 9A , and  FIG. 10B  being a schematic side view similar to FIG.  9 B. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   First Embodiment 
   A first embodiment of the invention will be described with reference to  FIGS. 1  to  10 . The embodiment comprises the following four mechanisms. The first one is a brake mechanism used in the case where a user rises from a wheelchair and in the case where a user rides on the wheelchair, the second one is a brake actuating mechanism for a helper, the third one is a brake release mechanism during conveying an empty wheelchair, and the fourth one is an automatic opening mechanism for steps. 
   First, an explanation will be given to a constitution of the brake mechanism. As shown in  FIG. 1 , a frame of the wheelchair comprises main rear columns  1 A composed of a pair of left and right pipes extending vertically, a pair of left and right, main lower columns  1 B extending forward from lower ends of the main rear columns  1 A, a pair of left and right, first main front columns  1 C extending upward from forward ends of the main lower columns  1 B, a pair of left and right, main upper and horizontal columns  1 D fixed to intermediate portions of the main rear columns  1 A and extending forward therefrom, a pair of left and right, second main front columns  1 E extending downward from forward ends of the main upper and horizontal columns  1 D, a pair of left and right, first mount pipes  1 F, both ends of which are interposed between the main rear columns  1 A and the second main front columns  1 E and fixed to upper ends of front and rear, cross braces  40 , and a pair of left and right, second mount pipes  1 G, which are arranged below and in parallel to the first mount pipes  1 F, and one ends of which are fixed to the main rear columns  1 A and the other ends of which are fixed to the first and second main front columns  1 C,  1 E. 
   The front and rear, cross braces  40  are fixed at upper ends thereof to front or rear portions of the first mount pipes  1 F and at lower ends thereof to front or rear portions of the main lower columns  1 B on an opposite side, and intersect each other at central portions thereof to be turnably fixed to each other at the intersections, thus enabling folding of the wheelchair. 
   Upper ends of the main rear columns  1 A make rearwardly bent handles  2  held by a helper. A pair of left and right, rear wheels  3  are rotatably mounted to the main rear columns  1 A, and a pair of left and right, front wheels  4  are rotatably mounted to lower portions of the first main front columns  1 C. Mounted to the pair of left and right, first mount pipes  1 F is a seat  5  having elasticity and capable of moving downward with an underside thereof bending. In addition, depiction of spokes of the rear wheels  3  and the front wheels  4  is omitted in  FIGS. 1 and 3 . 
   As shown in  FIGS. 1 and 2 , mounted on left and right axle shafts  10  of the rear wheels  3  are axle-shaft clamping type brake means  11 . Fixed to brake actuating portions of the brake means  11  are ends of brake levers  12 . Used as the brake means  11  are, for example, “SERVO BRAKES”, “BAND BRAKES” (both being JIS. NO. 6415) manufactured by Karasawa Seisakusho Kabushiki-kaisha, which are used for axle shaft brakes for bicycles, and so on. 
   Fixed to the pair of left and right, second mount pipes  1 G are upper ends of first mount plates  13  each extending below the brake levers  12  and toward the main rear columns  1 A. Lower end of the first mount plates  13 , respectively, are fixed to the pair of left and right, main lower columns  1 B. Fixed to upper portions of the pair of left and right, first mount plates  13 , respectively, are second mount plates  14 , to which one ends of actuation plates  16  are mounted through hinges  15  to be able to swing vertically. Here, the actuation plates  16  are arranged in a manner to contact with an underside of a portion amounting to about ¼ of a rear portion of the seat  5 . 
   Upper ends of dampers  20  composed of a gas damper, an air damper, an oil damper, or the like to serve as first bias means are pivotally mounted to the actuation plates  16 , and lower ends of the dampers  20  are pivotally mounted to support plates  21  fixed to lower portions of the first mount plates  13 . Extension forces of the dampers  20  push up the actuation plates  16  to bring the same into contact with the underside of the seat  5 . Lower ends of lengths of wire  22  for actuation of braking are fixed to the brake levers  12 , and upper ends of the lengths of wire  22  are mounted to the actuation plates  16  through small windows  13   a  provided on the first mount plates  13 . 
   As shown in  FIGS. 1 and 2 , the lengths of wire  22  loosen in a state, in which the dampers  20  are not extended and the actuation plates  16  swing downward, that is, a user of the wheelchair sits on the seat  5 , and the brake levers  12  swing downward owing to restoring forces of bias means housed in the brake means  11 , so that braking of the axle shafts  10  is released. As shown in  FIGS. 3 and 4 , in a state, in which the dampers  20  are extended and the actuation plates  16  swing upward, that is, a user of the wheelchair rises from the wheelchair, the lengths of wire  22  are pulled upward and the brake levers  12  are pulled upward, so that the axle shafts  10  are braked against restoring forces of bias means housed in the brake means  11 . 
   Subsequently, an explanation will be given to an action of the brake mechanism.  FIGS. 1 and 2  show a state, in which a user of the wheelchair sits on the seat  5  and body weight is applied on a corresponding portion of the seat  5  to the actuation plates  16 , so that the seat  5  is pushed down at the corresponding portion to push down the actuation plates  16  against extension forces of the dampers  20 . Also, the actuation plates  16  are pushed down whereby the lengths of wire  22  with upper ends thereof fixed to the actuation plates  16  loosen and the upward pulling forces of the lengths of wire  22  acting on the brake levers  12  disappear, so that biasing forces of bias means housed in the brake means  11  are restored to swing the brake levers  12  downward and braking of the axle shafts  10  is released (put in a non-braked state). 
   In contrast, when a user rises from a state, in which the user sits on the seat  5 , that is, a state shown in  FIGS. 1 and 2 , weight produced by body weight applied on the seat  5  disappears, so that pressure on the dampers  20  is released and so the dampers  20  are extended to push up the actuation plates  16  as shown in  FIGS. 3 and 4 . When the lengths of wire  22  with upper ends thereof fixed to the actuation plates  16  are thereby pulled upward, the brake levers  12 , to which lower ends of lengths of wire  22  are joined, are pulled up whereby restoring forces of the bias means housed in the brake means  11  to release braking are applied on the brake levers  12  and so the axle shafts  10  are braked (put in a braked state). 
   In this manner, since braking is applied the moment a user rises, and there is no play, the wheelchair remains stable and safe. Also, since the axle-shaft clamping type brake means  11 , of which durability and safety are warranted on the basis of results of use in many years, are adopted to clamp and brake the axle shafts  10 , they are excellent in durability and safety. 
   Incidentally, there is in many cases the possibility that when a user by one self rides on a wheelchair, the user first puts a hand or hands on the seat  5  trying to support a body, and so risk of fall is highly possible since the user&#39;s posture is not stable in the case where forces produced when the user puts a hand or hands on the seat  5  release braking to permit the wheelchair to move. Accordingly, in order to avoid such risk, the actuation plates  16  in the first embodiment are arranged in a manner to contact with an underside of a portion amounting to about ¼ of a rear portion of the seat  5 . More specifically, body weight of the user is applied on that portion amounting to about ¼ of the rear portion of the seat  5 , which is disposed at the back of the seat to be adequately distant from that portion, on which the user possibly puts a hand or hands, and braking is released after the user&#39;s posture becomes adequately stable, which warrants safety. 
   In addition, while the first embodiment uses the dampers  20  as tension applying means for pushing up the actuation plates  16 , springs or the like may be used to bias the actuation plates  16 . Also, while the actuation plates  16  are pivotally on the first mount plates  13 , they may be provided on the first mount plates  13  to be vertically movable. 
   Subsequently, an explanation will be given to the brake actuating mechanism. As shown in  FIGS. 1 and 3 , handle levers  30 , respectively, are mounted on the pair of left and right handles  2 . Lengths of brake wire  31  are coupled at upper ends thereof to the handle levers  30 , and at lower ends thereof to the brake levers  12  as shown in  FIGS. 1  to  5 . Hereupon, in the case where there is a need of braking when a user rides on the wheelchair and a helper pushes the wheelchair, the lengths of brake wire  31  are pulled upward upon grasping of the handle levers  30  and so the brake levers  12  coupled to the lengths of brake wire  31  are pulled up to apply braking. 
   In addition, although not shown, it goes without saying that when there is a need of braking by a user who sits on the wheelchair, a conventional manual brake mounted on the wheelchair is used as it is. 
   Subsequently, an explanation will be given to a constitution of the brake release mechanism when an empty wheelchair is to be conveyed. As described, when a user goes away from the wheelchair to make the same empty, braking is automatically applied to come to a state shown in FIG.  4 . Accordingly, there is a need of releasing braking when an empty wheelchair is to be conveyed. As shown in  FIG. 5 , both ends of a release lever  41  are pivotally mounted to a portion substantially intermediate between an intersection  40   a  of the rear cross braces  40  among the two pairs of front and rear cross braces  40 , which connect between the first mount pipes  1 F and the main lower columns  1 B on a side opposed to the first mount pipes  1 F, and upper ends of the cross braces  40  and to the main rear column  1 A disposed on the same side as that of the portion. 
   An upper end of a length of release wire  42  is fixed to the release lever  41  and a lower end of the length of release wire  42  is fixed to the brake lever  12  from below through wire through of the support plate  21  and holes  13   b  formed on bent portion the first mount plate  13 . A location  12   a , in which the length of release wire  42  is fixed to the brake lever  12 , is positioned much distant from a pivot of the brake lever  12  relative to a location  12   b , in which the lengths of brake actuating wire  22  are fixed to the brake lever  12 , such that a larger force than brake actuating forces with the wheelchair being empty acts on the brake lever  12  in a release direction as shown in FIG.  5 . 
   Subsequently, an explanation will be given to an action of the brake release mechanism when an empty wheelchair is to be conveyed. Generally, wheelchairs can be folded by causing a pair of left and right, rear wheels  3  and a pair of left and right, front wheels  4  to approach in an overlapping manner. More specifically, by lifting a longitudinal center line of the seat  5  in a manner to make the center line upwardly convex when an empty wheelchair is to be conveyed, it is possible to cause the pair of left and right, first mount pipes  1 F, to which both left and right, outer edges of the seat  5  are fixed, to approach each other. Hereupon, when the pair of left and right, first mount pipes  1 F are caused to approach each other in a manner described above, the pair of left and right, second mount pipes  1 G, the pair of left and right, main lower columns  1 B, the pair of left and right, rear wheels  3 , and the pair of left and right, front wheels  4  are caused interlocking therewith to approach each other, and further the front cross braces  40  and the rear cross braces  40  are caused interlocking therewith to approach each other. Therefore, a fixed end of the release lever  41  on a side of the cross brace  40 , the release lever being arranged between the cross brace  40  and the main rear column  1 A, is lifted upward about an axis of turning on a fixed end of the release lever on a side of the main rear column  1 A. Then, the length of release wire  42  is simultaneously pulled upward, and a force, which the length of release wire  42  applies on the brake lever  12  from below, exceeds the brake actuating forces in association with points of action on the brake lever  12  and directions of forces, so that braking is released to enable conveying an empty wheelchair. 
   Finally, an explanation will be given to a constitution of the first embodiment of the automatic opening mechanism for legs, which hold steps, with reference to  FIGS. 1 ,  3 , and  6 . Struts  51  fixed to upper portions of legs  50  are pivotally fitted and inserted into upper ends of the first main front columns  1 C. Torsion springs  52  mounted on the first main front columns  1 C bias the struts  51  to open the same outside as viewed from a front of the wheelchair. The struts  51  may be reversely biased so that the left and right legs  50  are closed inside to be folded to overlap each other. Formed on lower ends of the legs  50  are supports  50 A to extend substantially horizontally and forward. Provided on intermediate portions of the legs  50  are horizontal struts  50 B to extend toward the first main front columns  1 C. Ends of the horizontal struts  50 B are pivotally mounted on the first main front columns  1 C. Strut supports  60  are fixed below the horizontal struts  50 B. 
   The strut supports  60  house therein structures as shown in FIG.  6 . The strut supports  60  comprise top-opened casings  61 , in which top-opened spring supports  62  are fixed. Bushes  63  are fixed in upper areas of the spring supports  62 . Stoppers  64  arranged through the spring supports  62  are slidably inserted into the bushes  63 . Springs  65  are arranged between the spring supports  62  and flanges  64   a  of the stoppers  64  to bias the stoppers  64  so that tip ends of the stoppers  64  project from the bushes  63 . Fixed to inner ends of the stoppers  64  are wire fixing members  66 . Fixed to the wire fixing members  66  are lower ends of lengths of wire  68  for opening of steps. The lengths of wire  68  are surrounded by wire guides  67 . Upper ends of the lengths of wire  68  are fixed through the damper support plates  21  to the actuation plates  16 . 
   Recesses  50   a  are provided in those positions on undersides of the horizontal struts  50 B, which correspond to the stoppers  64 . 
   Subsequently, an explanation will be given to an action of the automatic opening mechanism for legs. As described with respect to an action of the automatic brake mechanism, the brake levers  12  swing downward to release braking in a state, in which a user sits on the seat  5  of the wheelchair as shown in  FIGS. 1 and 2 . At the same time when the lengths of wire  22  for actuation of braking, connected to the brake levers  12  loosen, the lengths of wire  68  for opening of steps also loosen, so that the springs  65  in the casings  61  for the stopper bias and project the stoppers  64 , as shown in  FIG. 6A , to engage the same with the recesses  50   a  in the horizontal struts  50 B so that the legs  50  are not opened by the bias of the torsion springs  52  when the legs  50  are set in positions for use. 
   In contrast, when a user rises from a state of sitting on the seat  5  as shown in  FIGS. 1 and 2 , extension forces of the dampers  20  pull the lengths of wire  22  upward and the brake levers  12  coupled to the lengths of wire  22  are pulled up to apply braking, as described with respect to the action of the brake mechanism. Since the lengths of wire  68  coupled at upper ends thereof to the actuation plates  16  are also pulled in the same as the lengths of wire  22 , the stoppers  64  of the strut supports  60  withdraw, as shown in  FIG. 6B , to be released from engagement with the recesses  50   a  in the horizontal struts  50 B. 
   Thereby, control on the bias of the torsion springs  52  is released, so that the bias of the torsion springs  52  opens steps  53  left and right together with the pair of left and right legs  50  and so no obstacle is constituted when a user of the wheelchair begins walking. Setting of the legs  50  to positions for use is effected such that when the legs  50  are manually turned to positions for use after a user goes away from the wheelchair, the stoppers  64  are projected to engage with the recesses  50   a  to thereby fix the legs in a forwardly directed, neutral state, which corresponds to positions for use when a user rides on the wheelchair. 
   Conventionally, the steps  53  must be removed to positions constituting no hindrance to walking with hands or feet before a user rises and begins walking. In the first embodiment, accidents are prevented, in which a paralytic user or a user who cannot bend forward to reach hands to the steps  53  stumbles and falls, since the steps  53  are moved to positions constituting no hindrance to beginning of walking before a user rises and begins walking. 
   Second Embodiment 
     FIGS. 7 and 8  show a second embodiment of the automatic opening mechanism for steps. In addition, in the second embodiment, members being the same as, or corresponding to those in  FIGS. 1  to  6  are denoted by the same reference numerals, and an explanation therefor is omitted. In the present embodiment, legs  50  are fixed to first main front columns  1 C. Tip ends of lower portions of the legs  50  constitute supports  50 A, and steps  53  are rotatably born by the supports  50 A. The steps  53  turn to assume two positions including a horizontal position and a vertical position. Springs  70  are mounted on the supports  50 A to bias the steps  53  to vertical position at all times. Also, formed in base positions of the supports  50 A are stoppers  64  having the same function as that of the stoppers  64  in the control device for the leg opening mechanism in the first embodiment. Provided on the steps  53  are recesses  53   a , with which the stoppers  64  engage. Like the first embodiment, lengths of wire  68  for opening of steps are fixed at lower ends thereof to wire fixing members  66  in the casings  61  for the stoppers and at upper ends thereof through support plates  21  to actuation plates  16 . 
   Accordingly, with the embodiment, the stoppers  64  at lower portions of the step holding legs project to engage with the recesses  53   a  in the same manner as the case in  FIG. 1 , in a state, in which a user sits on a seat  5  of the wheelchair as shown in FIG.  7 . Therefore, the steps  53  are held in positions (horizontal) for use notwithstanding the bias of springs  70 . Also, when a user rises from a state shown in  FIG. 7 , the stoppers  64  withdraw and separate from the recesses  53   a  on the steps  53 , and so the steps  53  are put in a vertical position from a horizontal position as shown in  FIG. 8  by the bias of the springs  70  not to constitute an obstacle when a user of the wheelchair begins walking. Such arrangement produces the same effect as that in the first embodiment. 
   Third Embodiment 
     FIGS. 9 and 10  show a third embodiment of the automatic opening mechanism for steps. 
   Fixed to a first mount plate  13  is a crank support arm  80  extending toward an actuation plate  16 , and swingably born by the crank support arm  80  is a bent portion of a L-shaped crank  81  having a short arm  81   a  and a long arm  81   b . An end of the short arm  81   a  of the crank  81  is pivotally coupled to the actuation plate  16 , and an upper end of a length of wire  82  for opening of a step is fixed to an end of the long arm  81   b  of the crank  81 . The length of wire  82  for opening of a step extends through a second mount pipe  1 G and passes guide rollers  83 ,  84 ,  85 , which are rotatably provided on the second mount pipe  1 G and a leg  50 , and a lower end of the length of wire is fixed to a step actuation arm  54 , which is united with the step  53 , from below. 
   Subsequently, an explanation will be given to an action. When a user sits on a wheelchair, the user&#39;s body weight lowers a seat  5  as shown in  FIG. 9 , and the actuation plate  16  is correspondingly pushed down. Thereby, the crank  81  is caused to swing about a support shaft of the crank support arm  80  in a clockwise direction as viewed in  FIG. 9A , so that the end of the short arm  81   a  lowers and the end of the long arm  81   b  rises. When the end of the long arm  81   b  rises, the length of wire  82  for opening of a step, an upper end of which is coupled to the end of the long arm, is pulled up to go round the step actuation arm  54  from beneath, thus acting as a force to pull down the step actuation arm. Thereby, the step  53  having been put in a vertical position is turned inside 90 degrees to come to a horizontal position to be set in a position for use. 
   Meanwhile, when a user of the wheelchair rises, the seat  5  ascends and the actuation plate  16  is pushed upward by the force of a damper  20  as shown in  FIG. 10 , the crank  81  is caused to swing about the support shaft of the crank support arm  80  in a counterclockwise direction, so that the end of the short arm  81   a  rises and the end of the long arm  81   b  lowers. Thereby, since the length of wire  82  for opening of a step loosens to release a pulling force acting on the step actuation arm  54 , the restoring force of the springs  70  housed in the step  53  shifts the step  53  from the horizontal position to the vertical position, so that the step is positioned not to prevent a user of the wheelchair from rising and then beginning walking. 
   In this manner, according to the third embodiment, when a user sits on a wheelchair, the step  53  automatically comes to a horizontal position to be set in a position for use, and when a user rises, the step automatically comes to a vertical position to be set in a position not to obstruct walking, so that a more excellent effect than that in the first embodiment is produced. 
   An explanation will be given below to other modifications. 
   In the above embodiments, the brake levers  12  are connected directly to the brake means  11  but may be connected to the brake means through a length of wire. 
   The first bias means adopts the dampers  20  but may adopt other means. 
   The second bias means adopts the coil springs  52  and the third bias means adopts the coil springs  70  but may adopt other bias means than coil springs. 
   The actuation plates  16  are not necessarily disposed on the back side of the seat  5 . 
   The present examples and embodiments are to be considered as illustrative and not restrictive, and the invention is not to be limited to the details given herein, but may be modified within the scope and equivalence of the appended claims.