WHEEL CHAIR

Abstract: A wheel chair comprises a chassis (2) and, arranged thereat, small front and rear wheels (4 and 5 respectively) and big wheels (6) for displacement of the wheel chair by manual power from a person sitting therein. The wheel chair is convertible between a first operational state, in which it rests on the ground solely by means of the front and rear small wheels (4 and 5 respectively) and a second operational state, in which it rests on the ground by means of, on one hand, either the small front and rear wheels and, on the other hand, the big wheels (6). Furthermore, the wheel chair (1) comprises a device (10) operable to act between the chassis (2) and ground (9) to lift the chassis to provide an operational state converting position, in which the wheel chair (1) rests on the ground by means of the lifting device, which is adapted, in this position, to counteract relative movement between the wheel chair and the ground, and the small front and/or rear wheels while lifting at least one of them and at least one of the big wheels out of contact with the ground.

Description: 93/02648 Wheel chair FIELD OF INVENTION AND PRIOR ART The present invention is related to a wheel chair according to the precharacterizing part of the enclosed claim l. The convertibility of such wheel chairs involves the notion that the chair in the first operational state, in which it rests on the ground solely by means of the small front and rear wheels, should be displaced forwardly by a person sitting therein obtaining contact with the ground by means of his feet and pushing the chair forwardly, or rearwardly if desired. In the second operational state, in which the wheel chair rests on the ground by means of, on one hand, either the small front or rear wheels and, on the other hand, the big wheels, the chair is suited for propulsion by the person sitting therein causing the big wheels to rotate with his hands, either by gripping the wheels directly or rims connected thereto. The two operational states are, accordingly, suitable for such persons bound to wheel chairs, who have considerable strength in their legs and arms respectively. By means of the convertibility obtained, one and the same chair may, at different times, be used by persons having different physiological abilities, but it is also possible that one and the same person may want to change between the two ways of displacing the wheel chair. By the US patent 4 098 521 a wheel chair is known, which has the big wheels removably arranged at its chassis, the conversion from the first to the second operational state occurring by manual lifting of the wheel chair resting on the small front and rear wheels so that it still rests on the rotatable front wheels during application of the big wheels to the chassis, whereafter the rear small wheels hang in the air, since the big wheels extend further downwardly relative to the chassis than the small rear wheels. The conversion from the second to the first operational state occurs in a reverse manner. The conversions between different operational states are relatively difficult to achieve, since, first of all, the wheel chair tends to roll away and at least move during the work, and, secondly, it is laborious to lift the chair at the same time as the big wheels are put in place or removed, in particular if a person would sit in the chair at the same time, which in the practice becomes impossible. An alternative possibility would be to overturn the wheel chair sidewardly to put a big wheel in place and remove it respectively one at a time. A wheel chair of the kind mentioned by way of introduction is previously known by GB 2 113 160. In this wheel chair the small rear wheels are vertically movable so that they, by pressing these small wheels downwardly, can be caused to take over the support function from the big wheels. The problem with the wheel chair rolling away on conversion occurs also here and it is necessary to lift the rear end of the wheel chair to press down the small wheels below the big ones. It would appear to be practically impossible to obtain conversion with a person sitting in a chair, at least conversion from the second to the first operational state. The US patent 4 457528 describes a wheel chair, the big wheels of which are removable from the chassis in order to make the wheel chair rest only on the small wheels thereafter. The same problems that have been mentioned above in connection with the second US patent arise on conversion. In addition to the prior wheel chairs of the kind in question and mentioned hereinabove, a few wheel chairs of a related kind may be mentioned: The US patent 3 216 738 describes a wheel chair comprising a wheel chair unit having big and small wheels and a frame supporting the wheels. This unit may be removed from the wheel chair so that the wheel chair is transformed into a chair instead. Thus, there exists no real first operational state, but instead the wheel chair then operates as an ordinary chair. The exchange between the two states occurs in a position, in which the wheel chair is not held steadily in place, since it rests on its wheels, and the conversion is entirely impossible to execute for a person sitting in the wheel chair. The Swedish publication for public inspection No. 78118536-6 describes a wheel chair comprising different fittings for receiving wheels having different diameter. In this way the rear small wheels may be removed and instead big wheels be applied, one having, in this connection, to deal with all the problems mentioned hereinabove in connection with the US patent 4 098 521. Finally, it is to be mentioned that the German patent DE 32 30 179 describes a wheel chair which does not have the possibility to exchange operational state but which comprises a lifting device for lifting the wheel chair in its entirety between different levels to overcome level differences. With the exception that some of the wheels in certain situations is brought out of contact with the ground, this wheel chair has nothing in common with the wheel chairs according to the nature defined by way of introduction. SUMMARY OF THE INVENTION The object of the present invention is to provide a wheel chair according to the precharacterizing part of the enclosed claim O 93/02648 4 1, the problems mentioned hereinabove on conversion between the different operational states and impairing the prior art wheel chairs of this nature having been considerably reduced. This object is obtained in accordance with the invention by providing a wheel chair in accordance with the enclosed claim 1. By providing, in accordance with the invention, a lifting device and by means of the operational state converting posi¬ tion achieved thereby, it becomes, accordingly, possible to change between the two operational states in a very simple manner. Since the lifting device is adapted to counteract relative movement between the wheel chair and the ground and the wheel chair, with exception of the lifting device in the converting position, rests on the ground only by means of the small front and/or rear wheels while lifting at least one of them and at least one of the big wheels out of contact with the ground, the wheel chair stays safely in place during execution of the manipulations which are necessary for conversion. Furthermore, it becomes entirely possible, by designing the lifting device in an appropriate manner, to carry out conver¬ sion also with a person sitting in the wheel chair. Since at least one of the big wheels is not in contact with the ground in the operational state converting position achievable by means of the wheel chair in accordance with the invention no great forces are needed to modify the relative position between the small wheels and this big wheel vertically or alternatively remove or apply some of the wheels. According to a preferred embodiment of the invention, the chassis of the wheel chair comprises attachments for releasable rotatable reception of the big wheels and the big wheels are adapted to be moved to and removed from the attachments, and, accordingly, the wheel chair in the elevated operational state converting position for conversion to the second and first respectively operational state. In such a wheel chair the big O ς wheels may be attached or removed in a simple manner after readily having obtained the operational state conversion position by operating the lifting device since the big wheels hang above the ground and thereafter the lifting device may be operated to lower the wheel chair until the big wheels and the other small wheels respectively get in contact with the ground. According to another embodiment of the invention, said attach¬ ments and big wheels comprise co-operating members enabling quick-locking of the wheels to the attachments so that attach¬ ing and removing of these wheels may occur with some minor rapid manipulations. Further advantages and preferable features of the invention will appear from the following description and the rest of the dependent claims. BRIEF DESCRIPTION OF THE DRAWINGS A preferred embodiment of the invention cited as an example will follow hereunder with reference to the enclosed drawings, in which: Fig 1 is a diagrammatical perspective view obliquely from behind of a wheel chair according to a preferred embodiment of the invention; Fig 2 is a side view of the wheel chair according to Fig 1 in a second operational state; Fig 3 is a side view of the wheel chair according to Fig 1 in a first operational state; Fig 4 is a side view illustrating the wheel chair according to Fig 1 in an operational state converting position; Fig 5 is a partially cut view through the hub of a big wheel of a wheel chair according to Fig 1 and a part of an attachment therefor; and Fig 6 is a view corresponding to Fig 5 and illustrating a position in which the wheel axle of the big wheel may be removed from the attachment. DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION A wheel chair 1 according to a preferred embodiment of the invention is diagrammatically illustrated in Fig 1, said wheel chair comprising a chair 3 supported by a chassis or frame 2 and adapted to receive a person using the wheel chair sitting therein, and wheels for supporting the wheel chair on the ground in the form of two small front wheels 4, two small rear wheels 5 and two big wheels 6. These wheels are adapted rota- table about substantially horizontal axes, the front and rear small wheels also being held by holders 7, which are rotatably arranged at the chassis 2 about substantially vertical axes. This means that the small wheels may be adjusted into different directions relative to the chassis and the rest of the wheel chair in order to enable steering of the wheel chair. The position of the wheel chair on a ground when the big wheels 6 are attached to the wheel chair is illustrated in Fig 2. In this position the wheel chair will rest on the ground by means of the front small wheels 4 and the big wheels 6, whereas the rear small wheels will hover above the ground. In this opera¬ tional state it is intended that the wheel chair should be propelled by the person sitting in the wheel chair putting the big wheels 6 in rotation, either by gripping these wheels or the rims 8 associated thereto. In this operational state the rear small wheels 5 act as a safety against rearward tipping of the wheel chair. The spokes provided between the hubs of the big wheels and their wheel rims have been omitted in the Figures for gaining better clarity. 93/02648 7 The wheel chair is illustrated in a second operational state in Fig 3, in which it is without the removed big wheels 6 and rests on the ground 9 by means of the front and rear small wheels 4 and 5 respectively. In this state it is intended that the chair should be displaced by a person sitting therein moving his feet in contact with the ground and pushing himself forwardly by means of leg power. It is also conceivable that one desires to be relieved of the big wheels since they could be hindering and/or the wheel chair becomes more easy to steer on small areas, such as in a flat. It follows from the above that the big wheels 6 are removably rotatably arranged at the chassis 2 so that they can be at¬ tached to or removed therefrom for changing the wheel chair between the two operational states illustrated in Figs 2 and 3. This arrangement of the big wheels at the chassis will be explained later with reference to, in particular. Figs 5 and 6. Furthermore, a lifting device 10 is arranged at the chassis 2 of the wheel chair and adapted to act between the chassis 2 and the ground 9 to elevate the chassis parts adjacent to the lifting device relative to the ground. The lifting device consists in the embodiment illustrated of a cylinder 11 recei¬ ving a rigid rod 12 having a lower foot 13, said rod being displaceable in the cylinder and acting as a distance element. The lifting device is connected to a power source not illus¬ trated, such as for example a source for supplying hydraulic or pneumatic power or electric energy for, as an example, screwing the rod 12 out of and into the cylinder 11. The lifting device is operable, preferably by the person sitting in the chair, by means of an operating member not illustrated. Although in the Figures a lifting assembly formed by said cylinder 11 and rod 12 has been shown at one side of the wheel chair it is intended that a similar assembly should be provided at the opposite side of the wheel chair. However, as an alternative the lifting device could comprise only a single such assembly arranged under the middle of the wheel chair on the cross beam 15, which is included in the chassis 2 and connects the two longitudinal beams 14 thereof. This lifting assembly would then be capable of lifting, simultaneously, the rear small wheels and the big wheels on both sides of the wheel chair. When two lifting assemblies are arranged, one at each side of the wheel chair on each of the longitudinal beams, it would be possible to operate one lifting assembly of the lifting device at a time, and it is this mode of operation which is intended to be covered by means of the claim definition "whereas at least one of the small wheels and at least one of the big wheels are lifted out of contact with the ground". However, this definition also com¬ prises the case where the wheel chair, as in Fig 3, does not comprise any big wheel, but the lifting device has lifted the chassis relative to the ground so much that if it was assumed that the big wheels would be attached to the chassis in this position, at least one of them would be out of contact with the ground. The operation of the lifting device will now be explained. When the operational state of the wheel chair is to be changed from the position according to Figs 2 or 3, the lifting device is operated so that the rod 12 is displaced downwardly into contact with the ground 9 and thereafter the extreme end 13 of the rod is displaced further vertically away from the chassis while lifting the same relative to the ground. The lifting device may then be arranged to displace the distance element rod 12, in relation to the position achieved on ground contact by means of the foot 13 in the condition according to Fig 2, further about 15 mm vertically relative to the cylinder 11 so that a big wheel 6 attached to the chassis clearly gets out of contact with the ground or, in the operational state according to Fig 3, such a big wheel may be attached to the wheel chair while being free from the ground. In the operational state converting position obtained according to Fig 4 the big wheels may, accordingly, be attached to or removed from the wheel chair whereas the wheel chair is held in a stable position due to the friction of the foot 13 against the ground without having to lift or roll over the wheel chair manually in order to be able to take care of wheel exchange. In the position according to Fig 4 the rear small wheels 5 simultaneously act as a protection against rearward tipping. The arrangement of the big wheels on the wheel chair will now be explained with reference, primarily, to Figs 5 and 6. An attachment 16 is secured to the chassis for each of the big wheels 6. The attachment 16 is adapted to releasably and rotatably receive the big wheels by presenting a through passage 17, which is provided by a sleeve 19, which is inserted into a hole 18 of the attachment 16 and provided with an external thread, said sleeve being retained to the attachment 16 by means of nuts 20 engaging with the sleeve and located on either sides of the attachment. The extreme end of the wheel axle 21 of the big wheel is introduσible into the passage 17. The hub 23 of the wheel is, furthermore, in a conventional manner rotatable about the wheel axle 21 by means of bearings 22. A rubber ring 24 is provided about the wheel axle and adapted to abut against a shoulder 25 formed between the part of the wheel axle introduced into the sleeve 19 and the rest of the wheel axle, said rest having a larger diameter than said end. The end of the sleeve 19 pointing opposite to the direc¬ tion of introduction of the wheel axle is pointed to obtain some axial resiliency of the wheel axle in the sleeve. The wheel axle 21 is hollow and comprises a passage 27 recei¬ ving a substantially cylindrical core part 26. The passage 27 comprises a step 28 with a diameter increase in the end oppo¬ site to the end adapted for introduction into the sleeve 19. The extreme end of the core part which is remote from the sleeve 19 presents a diameter increase 29, which begins from a second step 30, a compression spring 30 being adapted to act between said second step 30 and the step 28, said compression spring being wound about the core part 26. The compression spring 31 tends to press the core part 29 out of the wheel axle in the direction of the arrow A. This, however, is counteracted by two balls 32, which are adapted to abut against 93/02648 10 circumferential surfaces 33 of the core part, said surfaces diverging in the direction of introduction of the wheel axle into the sleeve 19. Furthermore, the wheel axle 21 comprises, in the area of the balls 32, recesses, out of which the balls 32 are adapted to protrude in the position according to Fig 5. This has the result that the spring 31 strives to press out the core part 26 out of the wheel axle, whereby the balls 32 are pressed against and get fastened to the periphery of the sleeve 19 and in this way retains the wheel axle and the wheel to the attachment 16. However, the wheel may rapidly be removed from the attachment 16 by manually pressing the end of the core part 26 into the wheel axle in the direction of the axle B while storing poten¬ tial energy in the compression spring 31, whereby the balls 32 will be able to move along the circumferential surfaces 33 of the core part in a converging direction and, accordingly, inwardly in the recesses of the wheel axle, so that thereafter the wheel axle may be retracted from the sleeve 19 with main¬ tained compression of the spring 31. In order to attach the big wheel to the attachment, it is only necessary to grip the wheel about its hub and, preferably with the thumb, press the end 29 into the wheel axle so that the balls 32 will lie in their positions most closely to the axis of the core part, whereupon the wheel axle in this state is pushed into the sleeve 19 of the attachment 16 in the direction of arrow B. When the posi¬ tion according to Fig 6 has been achieved, the pressure on the end 29 of the core part is released and the compression spring 31 displaces the core part relative to the wheel axle while displacing the balls 32 along the circumferential surfaces 33 to the position illustrated in Fig 5, with the result that the wheel is held in place. Thanks to the quick-locking device just described in combina¬ tion with the lifting device according to the invention the operational state of the wheel chair according to the invention may be exchanged rapidly and easily. The invention is of course not only restricted to the prefer¬ able embodiments described hereinabove, but numerous possibi¬ lities for modifications thereof are obvious to a man skilled in the art without having to depart from the basic concept of the invention. As an example, it would be possible to arrange the big wheels so that they remain on the wheel chair also in the first opera¬ tional state either by making the rear small wheels movable downwardly against the ground or the big wheels elevatable relative to the chassis when the position according to Fig 4 has been achieved. The lifting device could be located at another place on the chassis than the one illustrated on the drawings and it could also be designed in an arbitrary manner as long as it fulfils the function aimed at. In this connection the lifting device could comprise a pivot arm pivotably connected to the chassis and being actuatable by means of line control device so as to be brought to pivot relative to the chassis and enter into contact with the ground and lift the chassis relative thereto with its free end. The two attachments for the big wheels could be connected to each other by means of a cross bar so that they, together with this cross bar, form a U-shaped configuration. The wheels could be more in number than illustrated in the Figures but the front or rear small wheels could also occur in the singular. The design of the chassis and the chair itself illustrated in the drawings is given purely for the sake of illustration, and these parts of the wheel chair may be varied within wide limits depending upon various requirements.

Claims: Claims 1. A wheel chair comprising a chassis (2) and front and rear small wheels (4 and 5 respectively) and big wheels (6) arranged at the chassis to enable displacement of the wheel chair by means of manual power from a person sitting therein, the wheel chair being convertible between a first operational state, in • which it rests on the ground solely by means of the front and rear small wheels (4 and 5 respectively), and a second opera¬ tional state, in which it rests on the ground by means of, on one hand, either the front or rear small wheels and, on the other hand, the big wheels (6), characterized in that it comprises a device (10) operable to act between the chassis and the ground to lift the chassis so as to provide an operational state converting position, in which the wheel chair (1) rests on the ground by means of the lifting device, which is adapted, in this position, to counteract relative movement between the wheel chair and the ground, and the front and/or rear small wheels whereas at least one of them and at least one of the big wheels are lifted out of contact with the ground. 2. A wheel chair according to claim 1, characterized in that the lifting device is adapted to lift the chassis (2) to an operational state converting position, in which the wheel chair rests on the ground by means of, on one hand, either the small front (4) or rear (5) wheels and, on the other hand, the lifting device (10). 3. A wheel chair according to claim 1 or 2, characterized in that the lifting device (10) is adapted to lift, in order to achieve the operational state converting position, the chassis (2) while maintaining the contact between the ground and the small wheels, by means of which the wheel chair is resting in its second operational state. 4. A wheel chair according to any of claims 1-3, characterized in that the lifting device (10) comprises a rigid distance 93/02648 13 element (12) connected to the chassis and movable into a position, in which one (13) of its ends, namely the extreme one, is located against the ground and at a larger vertical distance from the adjacent chassis parts than the vertical distance between the latter and the ground in any of the two operational states. 5. A wheel chair according to claim 4, characterized in that the distance element is a pivoting arm pivotably connected to the chassis and that a tensile force transmitting element is connected to the pivoting arm and adapted to pivot the pivoting arm relative to the chassis by means of actuation from an operating member while changing the vertical distance of the extreme end of the distance element to the chassis. 6. A wheel chair according to any of claims 1-5, characterized in that it comprises an operating member to enable a person sitting in the wheel chair to operate the lifting device in order to bring the wheel chair to the operational state conver¬ ting position and carry out the conversion with said person in the wheel chair. 7. A wheel chair according to any of claims 1-6, characterized in that the small front wheels (4) are adapted to rest on the ground in the second operational state and that the big wheels (6) are provided, as viewed in the driving direction, between the small front and rear wheels (4 and 5 respectively). 8. A wheel chair according to claim 7, characterized in that the lifting device (10) is arranged at the chassis (2) between the small rear wheels (5) and the big wheels (6). 9. A wheel chair according to any of claims 1-8, characterized in that the chassis comprises attachments (16) for releasable and rotatable reception of the big wheels (6) and that the big wheels are adapted to be moved to and removed from the attach¬ ments and, accordingly, the wheel chair in the elevated O 93/02648 operational state converting position for conversion to the second and first respectively operational state. 10. A wheel chair according to claim 9, characterized in that each attachment (16) comprises a substantially horizontally directed passage (17) adapted to receive the wheel axle (21) of a big wheel (6), that a spring member (31) is adapted to actuate a locking member (32) to lock the wheel axle introduced into the passage within said passage, and that the locking member is adapted to interrupt this locking operation on manual actuation of the spring member (31) and enable withdrawal of the wheel axle (21) from the passage (17) of the attachment to remove the big wheel (6) from the wheel chair. 11. A wheel chair according to claim 10, characterized in that the wheel axle (21) of the big wheel is hollow, that a core part (26) is displaceably received within the wheel axle, that the core part comprises surfaces (33) diverging from a center axis thereof in a direction towards one end of the core part, that one or more elements (32) are arranged displaceable along these surfaces, that the wheel axle (21) is adapted to be moved so far in the passage (17) that these elements are moved through and out of the passage again, that the spring member (31) is adapted to act between the wheel axle (21) and the core part (26) to exert the latter in a direction opposite to the direction of introduction of the wheel axle to a position, in which the elements (32) have been displaced along said surfaces (33) and abut against portions of the attachment which surround the passage or a part connected thereto and prevent further relative displacement between the core part and wheel axle, and that the core part (26) is displaceable, by means of appli¬ cation of external forces involving compression of the spring means (31), relative to the wheel axle in said direction of introduction while displacing the elements (33) along the surfaces (33) away from the end of the core part towards the center axis of the core part so as to release the wheel axle for withdrawal from the passage.

Inventors: EKMAN JAN, EKMAN, JAN +DI
Applicants: ERIKSSON ANN MARI & LM, VITACTIV AB, ERIKSSON, ANN-MARI +LM
Application year: 1992
Main classification: A61G5
IPC codes: A61G5