A WHEEL CHAIR WITH A DRIVING UNIT, AND A DRIVING UNIT FOR WHEEL CHAIRS

Abstract: There is a clear distinction between hand driven, simple wheel chairs and much higher developed motor driven wheel chairs. The invention provides for a compromise, where a wheel chair of a simple design is or can be provided with a special driving unit (30), which as a self-contained unit, may serve to drive the wheel chair by having one or more driving wheels (32) located between the main wheels (26) of the chair in direct driving engagement with the ground. The driving unit can be secured in such a manner that the driving wheel or wheels (32) may move up and down relative to the main wheels (26), such that a driving engagement can be maintained during driving along a non-planar ground surface. The unit is well suited for mounting on both new and existing wheel chairs. When the driving wheel or wheels (32) are placed accurately midways between the ground engaging portions of the main wheels there will be no problems with respect to lateral dragging of the driving wheels in response to changes of the driving direction.

Description: A wheel chair with a driving unit, and a driving unit for wheel chairs. The present invention relates to a wheel chair for walk hampered persons and particularly a wheel chair with a driving unit, and a driving unit for such a wheel chair. It becomes more and more usual that wheel chairs are built as selfpropelled units, in which the whole structure is designed for that purpose, e.g. by a direct motor drive on the wheel shafts. However, there exist - and is still made - many wheel chairs which are only adapted for manual propulsion, either by the wheels being driven by the user, who grips a peripheral portion of the wheels, or by an attendant pushing the wheel chair. It would be desirable add some motor power to the wheel driving even in these chairs, but prior attempts of adding a preferably releasable motor drive have failed. On this background it is the purpose of the inven¬ tion to provide a wheel chair having a well suited auxiliary driving system. While the prior proposals have generally aimed at adding a driving momentum on the wheels, mostly by af¬ fecting the wheel periphery by a rotating driving rol¬ ler, the invention provides for a much more suitable auxiliary drive by completing the chassis of the chair with a motor driven, ground supported driving wheel, with this wheel mounted so as to be able to carry out movements up and down relative to the chair wheels, so that it can follow irregularities on the ground surface, and with the wheel located in such a manner that in its ground engaging position it will not impede a free turn- ability of the wheel chair. The latter condition is easily fulfilable by the extra driving wheel being located with ground contact at the same transverse ground contact axis as defined by the chair wheels. Such an extra driving wheel may well have a dia¬ meter which is much smaller than that of the chair wheels, and for that reason practically all designs of wheel chairs will provide sufficient space for the mounting of the extra wheel underneath the chair, be¬ tween the chair wheels, such that the extra wheel will not effectively take up additional space. The desired separate, vertical ovability of the driving wheel is easily achievable by mounting the driv¬ ing unit in a manner such that the wheel carrying part thereof is tiltable in a vertical plane about a trans¬ verse chassis axis of the wheel chair, horizontally spaced from the axis of the driving wheel. Normally the driving unit will comprise not only the driving wheel, but also a driving motor and a battery for driving the motor, and these parts will represent a noticeable weight, which will force the driving wheel downwardly, when the entire unit is pivotably connected with the chassis of the chair at a certain distance from the point of gravity of the unit. It has been found possible to design a standard fitting that will enable a driving unit according to the invention to be mounted on almost all known designs of wheel chairs, and the units, therefore, can be manu¬ factured at relatively low costs as a standard product for existing wheel chairs. It is also usable, of course, as a driving unit in new wheel chairs. It will be desirable that the unit can be pas- sivated so as to be out of engagement with the ground or floor, but this is easily achievable, e.g. by means of a pedal operated device for tilting the unit upwardly. In the following the invention is explained in more detail with reference to the drawing, which is a par¬ tially cut, perspective view of a chassis of a driving chair according to the invention. The chassis shown is in a conventional manner de¬ signed with a pair of opposed, longitudinal side members 2 , each belonging to an upright side frame structure having a foremost vertical pipe 4 for receiving a lower castor 6, upper longitudinal side members 8 and 10, which hold, inter alia, a forwardly and downwardly pro¬ jecting pipe 12 for holding a foot support member 14, and rear upright pipes 16 and 18, of which the pipe 18 carries a post 20 for a rearwardly projecting driving handle 22. These two side structures are mutually con¬ nected by a lower cross connection comprising a seat carrying structure 24 between the side members 2. In the embodiment shown the carrying wheels 26 of the wheel chair are mounted on bracket plates 28, which project rearwardly from the upright rear pipe 16. The wheel chair can be driven manually by an at¬ tendant holding the driving handles 22. According to the invention such a chair may be completed by mounting underneath the cross structure 24 a driving unit consisting of a chassis having underlying driving wheels 32 and an upper electric motor 34 driven from a battery in a box 36. This chassis has a forwardly projecting rod 38, the front end of which is rigidly connected with with a transverse pipe 40 continuing at both ends in respective telescopic members 42 that are securable to the pipe by means of clamp handles 44. At their outer ends the telescopic members 42 rotatably secured to mounting members 48 that are fixed to the side members 2 by means of clamps 48. The entire unit 30 may thus pivot freely up and down about the traverse constituted by the parts 40 and 42, i.e. the wheels 32 may rest against the ground also where the latter is out of level with the areas of en¬ gagement between the ground and the wheels 26. The related level difference will not go very high, and since e.g. by lifting the chair up into a car it will be unsuitable if the unit 30 pivots down vertically, the pivotability thereof is caused to be limited with the use of suitable stop means or - as shown - with the use of carrier chains 50 interposed between the rear end of the unit and holding fittings 52 at the rearmost portion of the horizontal pipes 8. From the unit 30 a cable 56 extends up to a handle lever 56 on one of the driving handles 22. This con¬ nection, mechanical or electrical, serves to enable a control of the motor 34 by means of the handle lever 56 by on/off operation or by a more graduated actuation of the motor for driving the wheels 32. A battery charger 58 will belong to the equipment. It will be desirable that the unit 30 can be raised from its driving engagement with the ground for making it freely manually drivable, and this can be achieved in a simple manner by the rear end of the unit being con¬ nected with a pivot lever cooperating with one of the lower side members 2 and having at its rear end a pedal 60, which is thus operable to cause the rear end of the unit to pivot upwardly into an upper position in which it is releasably locked, in a manner not shown. The pivot point of the said lever may be identical with the suspension point for the lower end of the chain 50, whereby the mounting of the pivot lever will be par¬ ticularly simple. The reestablishing of ground contact for the driving wheels 32 can be obtainable merely by a lifting of the pedal member 60. The driving wheel or wheels 32 should be located midway between the chair wheels 26, while in the longi¬ tudinal direction they should be located in a position such that they engage the ground on the same transverse line as defined by the points of ground engagement of the chair wheels 26, this line being designated 62 in the drawing. Admittedly the drawing is wrong on this point, as the wheels 32 are shown located noticeably in front of this line. If that was the case the result would be that by every turning of the driving wheel chair the wheel or wheels 32 would have to be dragged laterally over the ground, this being avoided when this or these wheels engage the ground on the line 62. The discussed driving unit 30 may be produced as a standard product, which will be well suited for mounting on the major part of the already existing wheel chairs, as the required adaptation will mostly be a question of adapting the length of the telescopic member 40,42. The disclosed driving unit will also be highly well suitable for installation in new wheel chairs that are beforehand desired to be motor driven, as hereby a cheap series produced driving unit 30 can be used in con¬ nection with even a conventional chair design.

Claims: C L A I M S : 1. A wheel chair having a driving unit, charac¬ terized in that the driving unit is mounted as a sepa¬ rately wheel supported unit placed in a low position between the main wheels of the chair, comprising a motor and one or more ground supported motor driven driving wheels, which are kept in ground contact in being limited displaceable in the vertical direction relative to the main wheels, the driving wheel or wheels being ground engaging near the line of connection between the ground contact points of the main wheels. 2. A wheel chair according to claim 1, in which the motor and the driving wheel or wheels, preferably to¬ gether with an associated battery box, are mounted on a rigid carrier chassis, which, from the area between the main wheels, extends forwardly to a mounting area, in which the front end of the carrier chassis is connected with the chassis of the wheel chair pivotally about a transverse, horizontal axis. 3. A wheel chair according to claim 1, in which the driving unit is connected with the chassis of the wheel chair in a manner such that the driving wheel or wheels are substantially non-displaceable in the horizontal transverse direction and placed substantially exactly on the said connection line. 4. A wheel chair according to claim 1, charac¬ terized in that the chair is provided with means oper¬ able to cause the driving wheel or wheels to be lifted free of the ground and to arrest them in such lifted position. 5. A driving unit for a wheel chair according to claim 1, comprising a motor and driving wheel or wheels, characterized in that the wheel or wheels are adapted for a direct driving engagement with the ground and that a wheel and motor carrying chassis is provided with mounting means for fixation to a wheel chair chassis in a manner such that the unit will be mountable in a posi¬ tion, in which the driving wheel or wheels are located in a low position between the main wheels of the wheel chair. 6. A driving unit according to claim 5, in which the chassis of the unit, preferably also carrying a battery box and a motor control unit, at its end oppo¬ site to its wheel accommodating end is provided with a telescopic arm system extending laterally to both sides and having outer mounting fittings, relative to which the chassis is pivotal about an axis coinciding with the telescopic arm system.

Inventors: RAUN KNUD, RAUN, KNUD
Applicants: RAUN KNUD, RAUN, KNUD
Application year: 1991
Main classification: A61G7
IPC codes: A61G5