Electrical wheelchair with an electrical seat-rotating device

1. An electrical wheelchair comprising:

a chair body including a frame and a driving wheel unit disposed rotatably on said frame;

a seat member disposed above said frame and including a rotation-controlling switch and a wheel-controlling switch that are disposed on said seat member, said seat member being disposed at a frontward position relative to said frame;

a motor unit disposed on said frame and connected electrically to said rotation-controlling switch and said wheel-controlling switch, said wheel-controlling switch being operable to rotate said driving wheel unit relative to said frame in a predetermined direction when said seat member is disposed at said frontward position, said motor unit including a driving motor that is provided with a motor shaft;

a worm unit including a horizontal worm rod that is journalled on said frame and that is rotated by said motor shaft of said motor unit;

a vertical rotating shaft journalled on said frame and having an upper end connected fixedly to said seat member;

a worm wheel engaging said worm rod and sleeved fixedly on said rotating shaft so as to transfer rotation of said worm rod to said rotating shaft, thereby permitting 360° rotation of said rotating shaft and said seat member relative to said frame, said rotation-controlling switch being operable to start and stop rotation of said motor shaft relative to said frame; and

a control unit including a sensing unit that senses 180° rotation of said rotating shaft so as to reverse rotational direction of said driving wheel unit so that said driving wheel unit can rotate relative to said frame in a direction opposite to said predetermined direction under automatic control, and a stop unit that stops rotation of said rotating shaft relative to said frame when said seat member rotates from said frontward position by 360°, after which rotational direction of said rotating shaft is reversed under automatic control when said rotation-controlling switch is actuated once again, said control unit sensing rotation of said rotating shaft so as to stop rotation of said driving wheel unit.

2. The electrical wheelchair as claimed in claim 1 , wherein said worm rod is provided with a spur gear sleeved fixedly thereon, said motor shaft being provided with a spur gear sleeved fixedly thereon, said electrical wheelchair further including an endless timing belt that has a toothed inner surface and that is trained on said gears of said worm rod and said rotating shaft so as to transfer rotation of said motor shaft to said worm rod.

3. The electrical wheelchair as claimed in claim 1 , wherein said sensing unit of said control unit includes a movable sensor attached to said rotating shaft, and a fixed sensor disposed fixedly on said frame, said movable sensor being brought into alignment with said fixed sensor so as to reverse the rotational direction of said driving wheel unit when said seat member rotates from said frontward position by 180°.

4. The electrical wheelchair as claimed in claim 3 , wherein said stop unit of said control unit includes a radial projecting rod welded to and extending radially and outwardly from said rotating shaft, and a stop element fixed on said frame, said radial projecting rod contacting said stop element so as to prevent further rotation of said rotating shaft relative to said frame when said seat member rotates from said frontward position by 360°, contact between said radial projecting rod and said stop element causing the rotational direction of said rotating shaft to be reversed when said rotation-controlling switch is actuated once again to rotate said rotating shaft relative to said frame.