WHEELCHAIR

Abstract: A wheelchair comprises a base frame section (1) with a longitudinal rod (3, 4) carrying at its ends a front wheel (5) and a back wheel (6), respectively, and a seat frame section (2) for supporting a seat and a back rest. Each back wheel (6) is mounted in a wheel carrier (9) pivotably connected with the corresponding longitudinal rod (3, 4), wherein a spring means (15) is provided between the wheel carrier (9) and the longitudinal rod (3, 4), said spring means (15) extending substantially parallel with the longitudinal rod (3, 4). Each spring means (15) is preferably located below the corresponding longitudinal rod (3, 4). In this manner the wheelchair described is provided with an elastic back wheel suspension, wherein a compact construction is obtained by the location of the spring means.

Description: Wheelchair The invention relates to a wheelchair, comprising a base frame section with a longitudinal rod carrying at its ends a front wheel and a back wheel, respectively, and a seat frame section for supporting a seat and a back rest. Such a wheelchair is described in Dutch patent application 9100789. The invention aims to provide a wheelchair of this type providing the user more comfort and which is also suitable for mounting an electrical drive. To this end the wheelchair according to the invention is characterized in that each back wheel is mounted in a wheel carrier pivotably connected with the corresponding longitudinal rod, wherein a spring means is provided between the wheel carrier and the longitudinal rod, said spring means extending substantially parallel with the longitudinal rod. In this manner a wheelchair is obtained which is provided with an elastic back wheel suspension, wherein a compact construction is obtained by the location of the spring means. An electrical drive is simply possible if an electric motor is mounted in each wheel carrier, the shaft of said motor carrying the back wheel. The invention will be further explained by reference to the drawings in which an embodiment is very schematically shown. Fig. 1 is a section of a part of an embodiment of the wheelchair according to the invention. Fig. 2 shows a detail of Fig. 1 at a larger scale. Fig. 3 is a section according to the plane III-III of Fig. 1. Referring to the drawings there is schematically shown a wheelchair mainly made in the same manner as the wheelchair according to NL-A-9100789 and reference is made to this document for a detailed description of the construction of this wheelchair. The wheelchair comprises a base frame section 1 and a seat frame section 2 for supporting a seat not shown and a back rest neither shown. The base frame section 1 is provided at both sides with a longitudinal rod 3 and 4, respectively, consisting of an oval tube. Each longitudinal rod carries at its front end a castor wheel 5 and at its rear end a back wheel 6. The back wheel 6 is mounted on the shaf 7 of an electric motor 8 not further shown and known per se. The electric motor 8 is mounted in a wheel carrier 9 pivotably connected with the corresponding longitudinal rod 3, 4 by means of a U-shaped brace 10. To this end the legs of the U-shaped brace 10 are mounted on a shaft 11 rotatably received in a bush 12 mounted on the longitudinal rod 3, 4 and in the longitudinal rod 3, 4 itself. The U-shaped brace 10 is fastened on the shaft 11 by a lock bolt 13 which engages for example in a circumferential groove of the shaft 11 not shown. Both shafts 11 are coupled with each other by a cylindrical bush 14, the ends of the shafts 11 directed towards each other being fittingly received in said bush 14. In this manner the wheel carriers 9 on the one hand can pivot with respect to the base frame section 1 independently of each other, whereas on the other hand a rigid construction of the base frame section 1 is guaranteed. Each wheel carrier 9 is coupled with the base frame section 1 by means of a spring means 15. This spring means 15 is located below the corresponding longitudinal rod 3 , 4 and extends substantially parallel with this longitudinal rod 3, 4. Thereby a very compact construction is obtained. As shown in Fig. 2 in more detail, the spring means 15 comprises a bush 16 and a pulling rod 17, wherein the bush 16 is rotatably connected with a support 19 of the corresponding longitudinal rod 3, 4 by a pin 18, whereas the pulling rod 17 is rotatably connected with the corresponding wheel carrier 9. A head 20 of the pulling rod 17 is slidably mounted in the bush 16, wherein a plurality of diaphragm springs 22 is provided between this head 20 and an end wall 21 of the bush 16. An adjusting nut 24 is provided on a screw thread part 23 of the pulling rod 17, wherein a sleeve 25 is enclosed between the adjusting nut 24 and the end wall 21 of the bush 16. By means of the adjusting nut 24 the rest position of the spring means 15 and thereby the spring bias can be adjusted. Each wheel carrier 9 is provided with an arm 26 pivotably connected with the same and carrying a safety wheel 27 at its end directed away from the base frame section 1. In the rest position shown in Fig. 1 said safety wheel 27 lies at an adjustable distance from the surface 28 supporting the wheels 5, 6. The arm 26 is coupled with the base frame section 1 by a coupling rod 29. In the embodiment shown the coupling rod 29 is rotatably connected with a support 30 of the arm 26 and a support 31 attached to the bush 16. The length of this coupling rod is adjustable for adjusting the distance between the safety wheel 27 and the surface 28. If during use of the wheelchair described a back wheel pivots upwardly, the safety wheel 27 will pivot downwardly. Thereby it is obtained that in particular during riding on an oblique surface tilting backwards of the wheelchair is prevented in that the safety wheels 27 will then contact the oblique surface and thereby increase the wheel- base. Although in the embodiment described the back wheels 6 are driven by electric motors 8, it is of course also possible to apply the construction described in a wheelchair without electrical drive. In that case each back wheel 6 is connected with an adapted wheel carrier 9 by a shaft. The invention is not restricted to the above described embodiment which can be varied in a number of ways within the scope of the claims.

Claims: CLAIMS 1. Wheelchair, comprising a base frame section with a longitudinal rod carrying at its ends a front wheel and a back wheel, respectively, and a seat frame section for supporting a seat and a back rest, characterized in that each back wheel is mounted in a wheel carrier pivotably connected with the corresponding longitudinal rod, wherein a spring means is provided between the wheel carrier and the longitudinal rod, said spring means extending substantially parallel with the longitudinal rod. 2. Wheelchair according to claim 1, characterized in that each spring means is located below the corresponding longitudinal rod. 3. Wheelchair according to claim 1 or 2 , characterized in that each spring means has an adjustable spring bias. 4. Wheelchair according to anyone of the preceding claims, characterized in that each spring means comprises a bush and a pulling rod with a head slidable in the bush, wherein a plurality of diaphragm springs are provided between an end wall and the head. 5. Wheelchair according to claim 4, characterized in that the pulling rod has a screw thread part wherein the length projecting out of the bush is adjustable by means of a nut rotatably mounted on the screw thread part. 6. Wheelchair according to anyone of the preceding claims, characterized in that each wheel carrier comprises a U-shaped brace, the legs of which are mounted on a shaft, said shaft being rotatably mounted in the corresponding longitudinal rod. 7. Wheelchair according to claim 6, characterized in that each longitudinal rod comprises a bush for receiving the corresponding shaft. 8. Wheelchair according to claim 6 or 7, characterized in that both shafts are coupled with each other by a cylindrical bush. 9. Wheelchair according to anyone of the preceding claims, characterized in that each wheel carrier comprises an arm pivotably connected with the same and directed away from the base frame section and carrying a safety wheel at its free end, said safety wheel being located at an adjustable distance from the surface supporting the wheelchair, wherein the arm is connected with the base frame section by a coupling rod. 10. Wheelchair according to claim 9, characterized in that the coupling rod has an adjustable length. 11. Wheelchair according to anyone of the preceding claims, characterized in that an electric motor is mounted in each wheel carrier, the shaft of said motor carrying the back wheel.

Inventors: SCHEULDERMAN PETRUS JOHANNES, SCHEULDERMAN, PETRUS, JOHANNES
Applicants: SCHEULDERMAN PETRUS JOHANNES, SEENUS NL BV R VAN, RICHARD VAN SEENUS NEDERLAND B.V., SCHEULDERMAN, PETRUS, JOHANNES
Application year: 1993
Main classification: A61G5
IPC codes: A61G5