MECHANICAL WHEELCHAIR DRIVE AND WHEELCHAIR HAVING SUCH A MECHANICAL WHEELCHAIR

Abstract

The invention relates to a mechanical wheelchair drive, comprising a rotatably mounted lever, a handle fastened to the lever, and a force transfer unit for transferring rotational motion of the lever to a wheelchair wheel, wherein the lever has a variable length and is guided along a closed guide of a guide plate, said guide deviating from the circular form, such that the length of the lever changes during the rotational motion.

Claims

1. Mechanical wheelchair drive comprising a rotatably mounted lever, a handle fastened to the lever and a force transfer unit for transferring a rotational motion of the lever to a wheelchair wheel, wherein the lever has a variable length and can be guided along a closed guide of a guide plate, which guide deviates from the circular form, so that a length variation of the lever takes place during the rotational motion.

2. The mechanical wheelchair drive according to claim 1, wherein the lever has a lever part mounted rotatably at a fastening point of the guide plate and an extendable lever part configured to be guided along the guide.

3. The mechanical wheelchair drive according to claim 1, wherein a horizontal adjusting device is provided for the adjustable fastening of the guide plate and the lever along a horizontal.

4. The mechanical wheelchair drive according to claim 3, wherein a vertical adjusting device is provided for the adjustable fastening of the guide plate and the lever along a vertical.

5. The mechanical wheelchair drive according to claim 4, wherein the adjusting device comprises a rail with fastening holes and a carriage with a fixing pin, which carriage can slide along the rail, wherein the fixing pin can be introduced into the fastening holes for fixing the carriage and wherein the guide plate and the lever are connected indirectly or directly to the carriage.

6. The mechanical wheelchair drive according to claim 1, wherein the force transfer unit is formed by a belt drive.

7. The mechanical wheelchair drive according to claim 6, wherein a belt is provided and configured to receive the rotational motion of the lever via a first roller and configured to deliver it to a second roller for transfer of the rotational motion to a wheelchair wheel.

8. The mechanical wheelchair drive according to claim 7, wherein deflecting rollers are provided so that the belt can be guided along an outer side of the wheelchair drive.

9. The mechanical wheelchair drive according to claim 1, wherein the force transfer unit comprises a freewheeling mechanism configured to transfer the rotational motion of the lever in only one direction of rotation.

10. The mechanical wheelchair drive according to claim 1, wherein an actuating lever for a braking device of the wheelchair drive is provided on the handle.

11. The mechanical wheelchair drive according to claim 1, wherein at least one fastening device is provided for fastening the mechanical wheelchair drive on a wheelchair.

12. The mechanical wheelchair drive according to claim 1, wherein the guide corresponds to a droplet-shaped closed curve having a wide end curve region and a narrow end curve region, wherein the end curve regions each have an vertex point and the narrow end curve region of the closed curve in a mounted state of the wheelchair drive points in a direction towards a backrest of a wheelchair.

13. The mechanical wheelchair drive according to claim 12, wherein in the mounted state of the wheelchair drive a longitudinal axis running between the vertex points of the wide end curve region and the narrow end curve region is inclined by at least 5° or by at least 10° or by 15° but no more than 30° with respect to the horizontal.

14. The mechanical wheelchair drive according to claim 13, wherein the curve can be described by the following mathematical equations: $X_1=A\cos \left(\theta \right)$ $Y_1=B\sin \left(\theta \right){\sin }^n\left(0.5*\theta \right)$ $\left(\begin{array}{c}X\\ Y\end{array}\right)=\left(\begin{array}{cc}\cos \left(\beta \right)& -\sin \left(\beta \right)\\ \sin \left(\beta \right)& \cos \left(\beta \right)\end{array}\right)\left(\begin{array}{c}{X}_1\\ Y_1\end{array}\right)$ wherein θ corresponds to an angle, the coordinates X and Y describe the course of the guide in a Cartesian coordinate system, the parameter β is specified between −20° and 30°, the parameters A and B are specified between 0.01 m and 0.25 m and the parameter n is specified between 0.2 and 0.9.

15. A wheelchair having a seat surface, a backrest and at least two wheelchair wheels, wherein a mechanical wheelchair drive is provided, which is connected to at least one wheelchair wheel, the mechanical wheelchair drive comprising a rotatably mounted lever, a handle fastened to the lever and a force transfer unit for transferring a rotational motion of the lever to a wheelchair wheel, wherein the lever has a variable length and can be guided along a closed guide of a guide plate, which guide deviates from the circular form, so that a length variation of the lever takes place during the rotational motion.

16. The wheelchair according to claim 15, wherein two wheelchair wheels are provided on the wheelchair which are each connected to a wheelchair drive.

17. The mechanical wheelchair drive according to claim 3, wherein the adjusting device comprises a rail with fastening holes and a carriage with a fixing pin, which carriage can slide along the rail, wherein the fixing pin can be introduced into the fastening holes for fixing the carriage and wherein the guide plate and the lever are connected indirectly or directly to the carriage.

18. The mechanical wheelchair drive according to claim 7, wherein the first roller is a first toothed belt wheel and the second roller is a second toothed belt wheel.

19. The mechanical wheelchair drive according to claim 11, wherein the fastening device is configured for fastening the mechanical wheelchair drive on an armrest holder of a wheelchair.

20. The mechanical wheelchair drive according to claim 13, wherein the longitudinal axis is inclined with the wide end curve region of the droplet-shaped closed curve downwards.

Description

[0031] The invention is explained further hereinafter with reference to preferred embodiments. In the figures:

[0032] FIG. 1 shows a wheelchair drive according to the invention in an oblique view;

[0033] FIG. 2 shows a guide plate together with guide and a variable-length lever in side view;

[0034] FIG. 3 shows a particularly preferred embodiment of a curve by means of which the guide can be described;

[0035] FIG. 4 shows a wheelchair with a wheelchair drive according to the invention; and

[0036] FIG. 5 shows a wheelchair with a wheelchair drive according to the invention in exploded view.

[0037] FIG. 1 shows a mechanical wheelchair drive 1 for a wheelchair 2 in a preferred embodiment. The wheelchair drive 1 comprises a lever 3 with a variable length which consists of a rotatably mounted lever part 4 and an extendable lever part 5 to which in turn a preferably rotatable handle 6 is fastened. The rotational motion of the lever 3 can be transferred to a wheelchair wheel 34 (not shown) by means of a force transfer unit 7. In order to brake the wheelchair, the handle 6 can have an actuating lever 40 for a braking device 41 of the wheelchair wheel 34 (cf. FIG. 4). The actuating lever 40 can in this case be connected to the braking device 41 via a cable pull (not shown).

[0038] In order to accomplish a length variation of the lever 3 during the rotational motion, the rotatably mounted lever part 4 is mounted rotatably at a fastening point 10 of a guide plate 9 and the extendable lever part 5 is guided in a guide 8 of the guide plate 9, which guide 8 is closed in itself. Preferably the guide 8 is formed by a slot guide 11 in which a guide pin 12 fastened to the extendable lever part 5 slides. Alternatively the guide 8 can also be configured as a guide rail which is closed in itself, along which a guide carriage or hook fastened to the extendable lever part 5 slides. The guide pin 12, the guide carriage or the guide hook can be mounted by additional bearing means for better guidance.

[0039] In order to be able to adapt the wheelchair drive 1 to the respective user, preferably a horizontal adjusting device 13 and a vertical adjusting device 14 are provided. By means of the horizontal adjusting device 13, the guide plate 9 and the lever 3 can be fastened at various positions along a horizontal, i.e. in the usage state substantially in the direction of travel of the wheelchair. By means of the vertical adjusting device 14 the guide plate 9 and the lever 3 can be fastened at various positions along a vertical, i.e. in the usage state substantially at right angles to a ground surface. In the embodiment shown the adjusting devices 13, 14 each have rails 15 with fastening holes 16 and carriages 17 with fastening pins 18. In addition, the rail 15 of the vertical adjusting device 14 is connected to the carriage 17 of the horizontal adjusting device 13. In order to adapt the guide plate 9 and the lever 3 to the body size of a person, only the fastening pins 18 need to be removed from the fastening holes 16 and the carriages 17 are displaced along the rails 15 to a suitable position. The fastening pins 18 are then inserted again through the through-holes of the carriage 17 provided for this purpose and into the fastening holes 16 in order to fix the carriage 17.

[0040] Furthermore, as can be deduced from FIG. 1 the force transfer unit 7 is formed by a belt drive 19, whereby a belt 20, preferably a toothed belt, transfers the rotational motion of the lever 3 from a first roller (not visible), in particular a toothed belt wheel, to a second roller 22, also in particular a toothed belt wheel. For this purpose the first roller is connected in a rotation preventive manner to the lever 3. As can be seen in particular from FIG. 4, the second roller 22 is preferably connected via a belt drive 23 with a tensioning device 24 to a wheelchair wheel 34. The second roller 22 can, however, also be connected directly to the wheel chair wheel 34. In order to transmit the rotational motion, as in the exemplary embodiment shown, the second roller 22 can be connected in a rotation preventive manner to a transmission roller 39 which has a different diameter and connects the belt 20 in a transmitting manner to the belt drive 23 or the wheelchair wheel 34. In this case, the belt drive 23 or the wheelchair wheel 34, respectively, is in contact with the transmission roller 39.

[0041] In order that the wheelchair drive 1 can be designed as compactly as possible, the belt 20 can be guided over deflecting rollers 26 which, in the embodiment shown are fastened to the carriages 17 and the rails 15 so that the belt 20 can be substantially guided along the outer side of the wheelchair drive 1, in particular along the rails 15.

[0042] In order to be able to mount the wheelchair drive 1 on a wheelchair 2 (cf. FIG. 4), at least one fastening device 27 can be provided, in particular for fastening to an armrest holder 28 of the wheelchair 2. The fastening device 27, for example, has a mounting rod for insertion into the armrest holder 28.

[0043] As can be seen from FIG. 2, the guide 8 of the guide plate 9 is closed in itself and deviates from a circular form. The guide pin fastened to the extendable lever part 5 slides in the guide 8 and thus brings about the change in length during the rotational motion. As a result of the curve shape deviating from the circular form, the joints of the driving person and protected and at the same time the power transferred from the muscles to the wheelchair wheel 34 is increased. In addition, the muscles involved in the rotational motion are more uniformly loaded and enable a continuous, i.e. jerk-free progressive movement.

[0044] FIG. 3 shows a closed curve C in a Cartesian coordinate system which corresponds to the course of the guide 8 in a particularly preferred embodiment. The fastening point 10 of the lever 3 would be positioned at the origin of the coordinate system. The depicted curve C can in this case be substantially described by the following equations:

[00002]$X_1=A\cos \left(\theta \right)$$Y_1=B\sin \left(\theta \right){\sin }^n\left(0.5*\theta \right)$$\left(\begin{array}{c}X\\ Y\end{array}\right)=\left(\begin{array}{cc}\cos \left(\beta \right)& -\sin \left(\beta \right)\\ \sin \left(\beta \right)& \cos \left(\beta \right)\end{array}\right)\left(\begin{array}{c}{X}_1\\ Y_1\end{array}\right)$

[0045] wherein θ as running coordinate corresponds to an angle between 0 and 2*pi or 0° and 360°. The coordinates X and Y describe the course of the guide 8 in the Cartesian coordinate system. In the diagram shown the parameter β was selected as 15.95°, the parameter A was selected as 0.151 m, the parameter B was selected as 0.152 m and the parameter n was selected as 0.7. The course of the curve which corresponds to the dotted line can be flattened towards the continuous line to avoid discontinuities and for better guidance of the lever 3.

[0046] The depicted curve C has a substantially droplet-shaped profile and has a wide 29 and a narrow end curve region 30. The end curve regions 29, 30 each have an vertex point 31 which are connected to one another by a longitudinal axis 32. The longitudinal axis is inclined by an angle θ of preferably 15° in the mathematically positive direction so that the wide end curve region 29 is inclined downwards. In the mounted state of the wheelchair drive 1, the narrow end curve region 30 of the closed curve C preferably points in the direction of a backrest 33 of the wheelchair 2 (cf. FIG. 4). As a result, a particularly joint-protecting rotational motion is obtained.

[0047] FIG. 4 shows two wheelchair drives 1 each in combination with respectively one wheelchair wheel 34 of a wheelchair 2. The wheelchair 2 can, as is known from the prior art, have a seat surface 35, a backrest 33 and two footrests 36. By using two wheelchair drives 1, each wheelchair wheel 34 can be driven individually by means of respectively one wheelchair drive 1. As can be seen in FIG. 4, each of the two wheelchair drives 1 is connected to the wheelchair 2 in each case via the fastening devices 27. The rotational motion of a lever 3 is transmitted via a belt 20, a first roller and a second roller 22 to a wheelchair wheel 34. For this purpose respectively one wheelchair wheel 34 can be connected via a belt drive 23 with tensioning device 24 to the second roller 22. However, it is also feasible that the second roller is connected directly to a wheelchair wheel 34. A transmission with the aid of a transmission roller 39 connected to the second roller 22 is also possible.

[0048] FIG. 5 shows the wheelchair 2 with a wheelchair drive 1 again in exploded view. A second belt 37 of the belt drive 23 together with tensioning device 24 can be seen in the figure.