Auxiliary drive device for a wheelchair

1. An auxiliary drive device for a wheelchair, comprising:

at least one electrically driven drive wheel;

a handle adapted to carry the auxiliary drive device; and

a coupling mechanism for coupling the auxiliary drive device to a wheelchair;

wherein

each of the at least one electrically driven drive wheels is supported at a steering shaft and freely pivotable with respect to the auxiliary drive device so that, when mounted to the wheelchair, the at least one electrically driven drive wheel aligns itself in a self-acting manner in a direction defined by manual action induced into the wheelchair; and

wherein the steering shaft of each of the at least one electrically driven drive wheels is arranged such that, when the auxiliary drive device is coupled to a wheelchair ready to be operated, a castor is provided for each of the at least one electrically driven drive wheels so that each of the at least one electrically driven drive wheels is self-adjusting with respect to the wheelchair to which it is coupled allowing driving straight.

2. The auxiliary drive device according to claim 1 , wherein, when the auxiliary drive device is coupled to a wheelchair ready to be operated, the steering shaft is basically vertical with respect to the driving surface on which the wheelchair stands and with which the electrically driven drive wheel is in contact, wherein a deviation from the vertical position is not more than 5°.

3. The auxiliary drive device according to claim 1 , wherein, when the auxiliary drive device is coupled to a wheelchair ready to be operated, an imaginary line through the axis of rotation of the drive wheel and the axial center of the steering shaft is inclined with respect to the center axis of the steering shaft in a range between 20° to 30°, wherein deviation from this range is not more than 5°.

4. The auxiliary drive device according to claim 1 , wherein, when the auxiliary drive device is coupled to a wheelchair ready to be operated, the castor is 60 mm and deviation from this value is not more than 20 mm.

5. The auxiliary drive device according to claim 1 , wherein the angular range within which the electrically driven drive wheel can be freely rotated is at least 360°.

6. The auxiliary drive device according to claim 5 , further comprising a stop gliding element-guiding element fixedly connected to the steering shaft which has a crescent-shaped elongated hole in which a stop gliding element is movably guided, wherein, when the steering shaft is rotated in a first direction, the stop gliding element abuts against a first side of a fixedly arranged stop element, wherein the stop gliding element in this position rests against a first end of said elongated hole, and upon rotation of the steering shaft in a direction opposite to the first direction of rotation, the stop gliding element gets in contact with a second side of the stop element, wherein in this position the stop gliding element rests against a second end of the elongated hole.

7. The auxiliary drive device according to claim 1 , wherein the drive functions of the electrically driven drive wheel can be controlled via an operating satellite which can be attached to a wheelchair wherein the operating satellite has a push control knob for controlling specifically ON and OFF functions and a rotational control ring for initiating drive and selection of the driving speed.

8. The auxiliary drive device according to claim 1 , further comprising at least one sensor is provided by which driving of a curve can be detected and an electronic control unit for controlling functions of the auxiliary drive device is adapted to influence the driving speed depending on a curve radius.

9. The auxiliary drive device according to claim 1 , wherein the coupling mechanism for coupling the auxiliary drive device to the wheelchair has a spring biased locking element which allows coupling to the wheelchair in a positive-locking manner and release thereof via a handle.

10. The auxiliary drive device according to claim 9 , wherein the locking element is formed such that in a locking position the locking element rests in a spring biased manner against an element to be held in a positive-locking manner for effecting the coupling and the element to be held in a form-locking manner for effecting the coupling comprises a cylindrical coupling pin.

11. The auxiliary drive device according to claim 1 , wherein, when the auxiliary drive device is coupled to a wheelchair ready to be operated, the steering shaft is basically vertical with respect to the driving surface on which the wheelchair stands and with which the electrically driven drive wheel is in contact, wherein a deviation from the vertical position is not more than 3°.

12. The auxiliary drive device according to claim 1 , wherein, when the auxiliary drive device is coupled to a wheelchair ready to be operated, an imaginary line through the axis of rotation of the drive wheel and the axial center of the steering shaft is inclined with respect to the center axis of the steering shaft in a range between 20° to 30°, wherein deviation from this range is not more than 3°.

13. The auxiliary drive device according to claim 1 , wherein, when the auxiliary drive device is coupled to a wheelchair ready to be operated, the castor is 60 mm and deviation from this value is not more than 10 mm.

14. The auxiliary drive device according to claim 1 , wherein the angular range within which the electrically driven drive wheel can be freely rotated is ≥380°.