WO2001089441A2 - Wheelchair - Google Patents

Abstract

Wheelchair comprising a base which is provided with a plurality of wheels which come into contact with the ground, at least some of which wheels form part of a caster assembly. The caster assembly comprises a wheel carrier, which holds a wheel which can rotate about a horizontal wheel axle, and a pivotable body, which is connected on the one hand to the wheel carrier and on the other hand to the base. The pivotable body can pivot about a substantially vertical pivot axis with respect to the base. The wheel carrier is connected, in such a manner that it can tilt about a substantially horizontal tilting axis which lies at a distance from the wheel axle, to the pivotable body. Elastic restoring means are arranged between the wheel carrier and the pivotable body, in such a manner that the wheel carrier can execute a tilting movement counter to a restoring force which is generated by the elastic restoring means. An adapter element, which is mounted on the base, on the one hand, and on the chair unit, on the other hand, is arranged between the base and the chair unit.

Description

Wheelchair

A first aspect of the present invention relates to a wheelchair according to the preamble of claim 1.

In a generally known design, a wheelchair of this type has front wheels for advancing and steering the wheelchair, which front wheels are each coupled to a dedicated electric drive motor. At the back, in a known design, there are one or more caster assemblies. These caster assemblies may be able to rotate freely or may be steered by a steering mechanism. In another known design, the one or more caster assemblies are situated at the front of the wheelchair.

The drawback of known wheelchairs with caster assemblies is that the ride of the wheelchairs is unsatisfactory. For example, the person sitting in the wheelchair experiences unpleasant bumps when travelling over obstacles, for example over a doorstep of a building. Furthermore, the known wheelchairs have the drawback that, particularly at relatively high speeds, the handling is unstable.

The object of the first aspect of the invention is to provide a wheelchair which does not have this drawback.

The first aspect of the present invention provides a wheelchair according to the preamble of claim 1 which is characterized in that the wheel carrier is connected, in such a manner that it can tilt about a substantially horizontal tilting axis which lies at a distance from the wheel axle, to the pivotable body, and in that elastic restoring means are arranged between the wheel carrier and the pivotable body, in such a manner that the wheel carrier can execute a tilting movement counter to a restoring force which is generated by the elastic restoring means .

The first aspect of the invention therefore provides for the wheel carrier of the caster to be able to execute an elastic tilting movement, under the influence of an external load, with respect to the base. Therefore, for example when travelling over a doorstep, the wheel in question will move backwards slightly, as seen in the direction of travel, and also upwards slightly. This elastic displacement feature increases the comfort of the person in the wheelchair. The action of this caster assembly is also advantageous when travelling at high speed.

Preferably, preloading means are provided for setting a preloading in the elastic restoring means, in such a manner that the wheel carrier can only execute a tilting movement once the preloading has been overcome .

In an embodiment which is deemed advantageous in practice, this preloading can be set in such a manner that, when the person who is to travel in the wheelchair sits on the wheelchair, there is no or scarcely any tilting movement of the wheel carrier. In this case, the tiltability is only used to absorb the loads which are caused by causes other than the weight of the person. This prevents the position and/or height of the seat changing when the person is in the process of sitting down in the wheelchair or getting out of the wheelchair.

A second aspect of the present invention relates to a wheelchair according to the preamble of claim 10.

In a generally known design, a wheelchair of this type has relatively large rear wheels for advancing and steering the wheelchair, which rear wheels are each coupled to a dedicated electric drive motor. In a known design, two caster assemblies are provided at the front. These caster assemblies may be able to rotate freely. In another known design, the one or more caster assemblies are situated at the rear of the wheelchair.

The first drawback of known wheelchairs is that the ride of the wheelchairs is unsatisfactory. In this case, the short distance between the front and rear wheels in combination with the relatively high weight of the wheelchair itself and the person sitting in it plays a role. Wheelchairs are known in which features are provided which enable the chair unit to be fitted in a plurality of different axial positions, as seen in the longitudinal direction of the wheelchair. As a result, it is possible, by arranging the chair at a suitable location, for the centre of gravity of the person sitting in the chair unit to be positioned at a location which is favourable for the ride of the wheelchair.

However, the known wheelchairs are of complex design, which makes it difficult to produce large numbers and makes the wheelchairs undesirably expensive.

According to a second aspect, the invention aims to provide measures which achieve the adjustment feature described above in a simple manner, preferably for a relatively low cost price.

According to its second aspect, the invention provides a wheelchair according to claim 10.

By arranging an adapter element between the base and the chair unit, it becomes possible to make a standard base and to adjust the adapter element to the appropriate chair unit. This structure is highly advantageous in particular if the base also incorporates the electric drive means and a battery container for fitting one or more batteries.

Advantageous embodiments of the adapter element are described in claims 11-18 and the description which follows.

A third aspect of the invention relates to the fact that there is a demand for numerous different wheelchairs, which forces wheelchair manufacturers to produce all kinds of different models. As described in the introduction, there are, for example, wheelchairs with relatively large wheels driven by electric motors at the front and casters at the rear, but also wheelchairs with a reversed arrangement of these wheels. In this context, the terms front and rear sides of the wheelchair are defined by the sitting position of the wheelchair passenger. The third aspect of the invention aims to allow efficient production of different wheelchair models. For this purpose, the third aspect of the invention provides a wheelchair according to claim 19. By using the adapter element, it is possible, on the basis of a standard base, to expediently produce wheelchairs with the chair unit in two oppositely directed orientations with respect to the said base.

Naturally, the various aspects of the invention can be incorporated in various combinations in a single wheelchair. In particular, both the first and the second aspect contribute to improving the ride of the wheelchair and the comfort of the passenger.

The various aspects will be explained in the following description with reference to the drawing, in which: Ficr. 1 shows a diagrammatic perspective view of a preferred embodiment of the caster assembly and a part of a carrier arm for the caster assembly of the wheelchair according to the invention,

Fig. 2 diagrammatically depicts an exploded view of the caster assembly shown in Figure 1,

Fig. 3 diagrammatically depicts a perspective view of an example of a base of the wheelchair according to the invention, and Fig. 4 diagrammatically depicts a perspective view of an adapter element which can be mounted on the base shown in Figure 3.

In Figures 1 and 2, identical components are denoted by identical reference numerals.

Figure 1 shows a caster assembly 1 and a part of a wheelchair base 2 on which the caster assembly 1 is mounted. The caster assembly 1 and the wheelchair base 2 form part of a wheelchair (not shown in further detail) .

The caster assembly 1 comprises a wheel carrier 3, which holds a wheel 5 which can rotate about a horizontal wheel axle . The wheel carrier 3 is in this case a fork with two limbs 6, 7 and a transverse web 8 between them, which connects the limbs 6, 7 to one another at the top. The wheel axle 4 lies at a distance from the transverse web 8.

The caster assembly 1 also comprises a pivotable body 10 which is connected on the one hand to the wheel carrier 3 and on the other hand to the base 2. It can be seen from Figure 2 that a journal 11, which fits into a bearing bush 12 of the base 2, where it can be locked in a suitable way in such a manner that the pivotable body 10 can pivot about a substantially vertical pivot axis with respect to the base 2, is attached to the pivotable body 10. By way of example, a lock nut is screwed onto the journal 11.

The pivotable body 10 is disposed between the limbs 6, 7 of the fork 3.

At a distance from the holes in the fork 3 for accommodating the wheel axle 4, opposite holes 13 are provided in the limbs of the fork 3, in such a manner that the centre axis 14 through these holes 13 is parallel to the wheel axle 4. In the pivotable body 10, threaded holes 15 are arranged on the sides lying alongside the limbs 6, 7, in such a manner that in each case one threaded bolt 17 can be fitted through a hole 13 in the fork 3 and can be fixed in the associated threaded hole 15.

In the mounted position, the journal 11 fits with play through an opening 18 in the transverse web 8 of the fork 3.

The procedure described above leads to the wheel carrier 3 being connected, in such a manner that it can tilt about a substantially horizontal tilting axis 14 which lies at a distance from the wheel axle 4, to the pivotable body 10.

Furthermore, a downwardly directed pin 20, around which a spring 21 is positioned, is attached to the transverse web 8 of the fork 3. The pin 20 fits with play through an associated opening 22 in the pivotable body 20. The spring 21 is supported against the transverse web 8 and the pivotable body 10. A preload- setting member 23 is provided on that part of the pin 20 which projects below the pivotable body 10, for the purpose of setting the preloading of the spring 20. By way of example, the setting member 23 is a self-locking nut. The spring 21 is disposed between the transverse web of the fork 3 and the pivotable body 10, at a location which lies at a distance from the journal 11, as seen in a direction which is opposite to the distance between the centre axis of the journal 11 and the wheel axle 4. In other words, the spring 21 is disposed in front of the journal 11, as seen in the direction of travel.

The spring 21 in this case forms elastic restoring means which are arranged between the wheel carrier 3 and the pivotable body 10, in such a manner that the wheel carrier can execute a tilting movement about the axis 14 counter to a restoring force which is generated by the elastic restoring means.

Obviously, the dimensions of the opening 18 in the transverse web 8 are such that this tilting movement of the fork 3 is possible.

By setting a preloading in the elastic restoring means, in this case the spring 21, it is possible to ensure that the wheel carrier can only execute a tilting movement once the preloading has been overcome.

The preloading can preferably be set in such a manner that, when the person who is to travel in the wheelchair sits down on the wheelchair, there is no or scarcely any tilting movement of the wheel carrier 3.

In Figure 3, reference numeral 101 denotes a wheelchair base. The base 101 in this case comprises a transverse bar 102 with longitudinal bars 103, 104 attached fixedly thereto. These bars 102, 103, 104, together with a rear bar 105, form a basework to which a battery container 105 is attached. The walls of the battery container 105 may be provided with openings or may be virtually completely open. On each side of the base 102 there is a rigid carrier arm 107, 108, which are each attached to the transverse bar 102 in such a manner that they can pivot about a horizontal pivot axis .

At its front end, each carrier arm 107, 108 bears a caster assembly 109, 110, and at its rear end each carrier arm 107, 108 bears a relatively large rear wheel 111, 112. Although this is not shown, an electric drive motor is provided for each rear wheel 111, 112, which motors are supplied from the batteries positioned in the battery container 105.

The drawing does not show that the wheelchair is provided with a chair unit, which comprises at least a seat and a backrest, which chair unit is mounted on the base 101.

According to the second aspect of the invention, the chair unit is not mounted directly on the base 101, but rather an adapter element 120 is provided between the base 101 and the chair unit, which element is mounted, on the one hand, on the base 101 and, on the other hand, on the chair unit. The adapter element 120 is designed in such a manner that it is possible to mount the chair unit in a plurality of different axial positions, as seen in the longitudinal direction of the wheelchair.

The adapter element 120 is substantially in the form of an inverted U, with two walls 121, 122 which point downwards and are attached to the base 101, and a transverse web 123, on which the chair unit is mounted.

The adapter element 120 is preferably produced from sheet steel.

A plurality of sets of holes 124 are provided above one another, spaced apart, in the walls 121, 122. Furthermore, corresponding, optionally threaded bolt holes 125 are present in the base 101, in particular in the longitudinal bars 103, 104. In this way, the adapter element 120 can be mounted on the base 101 in a plurality of vertical positions (Y direction) . The transverse web 123 is provided with a plurality of sets of holes 126 for attaching the chair unit, which sets of holes 126 lie at a distance from one another in the axial direction (X direction) . Bolts or the like can be fitted through these holes 126 in order to attach the chair unit to the adapter element 120, a plurality of axial positions of the chair unit with respect to the adapter element, and therefore also with respect to the base 101, being possible. The transverse web 123 of the U-shaped adapter element 120 extends above the batteries.

As indicated by the arrow Z in Figure 4, the adapter element 120 is also designed so that it - together with the chair unit mounted thereon - can, as desired, be positioned in a forwards orientation or a backwards orientation on the base 101, so that the same base 101 can be used to create wheelchairs with different directions of travel. In this way, it is possible to provide the larger wheels 111, 112 at the front of the wheelchair.

Claims

1. Wheelchair comprising a base which is provided with a plurality of wheels which come into contact with the ground, at least some of which wheels form part of a caster assembly, which caster assembly comprises a wheel carrier (3), which holds a wheel (5) which can rotate about a horizontal wheel axle (4), and a pivotable body (10) , which is connected on the one hand to the wheel carrier and on the other hand to the base (2), which pivotable body can pivot about a substantially vertical pivot axis with respect to the base, characterized in that the wheel carrier is connected, in such a manner that it can tilt about a substantially horizontal tilting axis (14) which lies at a distance from the wheel axle, to the pivotable body, and in that elastic restoring means (21) are arranged between the wheel carrier and the pivotable body (10), in such a manner that the wheel carrier can execute a tilting movement counter to a restoring force which is generated by the elastic restoring means .

2. Wheelchair according to claim 1, in which preloading means (23) are provided for setting a preloading in the elastic restoring means, in such a manner that the wheel carrier can only execute a tilting movement once the preloading has been overcome.

3. Wheelchair according to claim 1 or 2, in which the wheel carrier is a fork (3) with two limbs (6, 7) and a transverse web (8) between them, the wheel axle being provided at a distance from the transverse web and the pivotable body being disposed substantially between the limbs of the fork.

4. Wheelchair according to claim 3, in which the pivot axis (11) fits with play through an opening in the transverse web (8) of the fork (3) and is fixed to the pivotable body, the dimensions of the opening (18) in the transverse web being such that a tilting movement of the fork is possible.

5. Wheelchair according to claim 4, in which the centre axes of the tilting axis and the pivot axis intersect one another.

6. Wheelchair according to claim 1, in which the elastic means (21) are arranged between the transverse web of the fork and the pivotable body, at a location which lies at a distance from the pivot axis, as seen in a direction which is opposite to the distance between the centre axis of the pivot axis and the wheel axle.

7. Wheelchair according to claim 6, in which the elastic means (21) are formed by a spring.

8. Wheelchair according to claim 7, in which a pin (20) is attached to the transverse web of the fork, around which pin the spring is placed and which pin fits with play through an associated opening in the pivotable body, and in which the spring is supported against the transverse web and the pivotable body, a preload-setting member (23) being provided on the pin, for example on a part of the pin which projects below the pivotable body, for the purpose of setting the preloading of the spring.

9. Wheelchair according to claim 2, in which the preloading can be adjusted in such a manner that, when the person who is to travel in the wheelchair sits down on the wheelchair, there is no or scarcely any tilting movement of the wheel carrier.

10. Wheelchair comprising:

- a base (101) which is provided with a plurality of wheels (109, 110, 111, 112) which come into contact with the ground,

- a chair unit which comprises at least a seat and a backrest, which chair unit is mounted on the base, the wheelchair comprising features which enable the chair unit to be fitted in a plurality of different axial positions, as seen in the longitudinal direction of the wheelchair, characterized in that an adapter element (120), which is mounted on the base, on - li ¬

the one hand, and on the chair unit, on the other hand, is arranged between the base (101) and the chair unit.

11. Wheelchair according to claim 10, in which the adapter element is provided with a plurality of attachment formations for the chair unit, which lie at a distance from one another in the axial direction.

12. Wheelchair according to claim 11, in which the attachment formations are holes through which attachment bolts or pins extend in order to attach the chair unit to the adapter element .

13. Wheelchair according to one or more of the preceding claims 10-12, in which the adapter element can be attached to the base in a plurality of vertical positions.

14. Wheelchair according to claim 13, in which the adapter element is provided with a plurality of attachment formations which lie at a distance from one another in the vertical direction.

15. Wheelchair according to one or more of the preceding claims 10-14, in which the adapter element is of single-part design.

16. Wheelchair according to one or more of the preceding claims 10-15, in which the adapter element is substantially in the form of an inverted U, with two walls, which point downwards and are attached to the base, and a transverse web, on which the chair unit is mounted.

17. Wheelchair according to claim 16, which is provided with electric drive means and with one or more batteries, and in which the base has a battery container wherein the one or more batteries are positioned, and in which the transverse web of the U-shaped adapter element extends above the battery or batteries .

18. Wheelchair according to one or more of the preceding claims 10-17, in which the adapter element with the chair unit mounted on it or the chair unit is designed to be positioned, as desired, in a forwards orientation or a backwards orientation on the base, so that the same base can be used to create wheelchairs with different directions of travel.

19. Wheelchair comprising:

- a base which is provided with a plurality of wheels which come into contact with the ground,

- a chair unit which comprises at least a seat and a backrest, which chair unit is mounted on the base, the wheelchair comprising features which enable the chair unit to be fitted in a plurality of different axial positions, as seen in the longitudinal direction of the wheelchair, characterized in that an adapter element (120), which is mounted on the base, on the one hand, and on the chair unit, on the other hand, is arranged between the base (101) and the chair unit, and in that the adapter element with the chair unit mounted on it or the chair unit is designed to be positioned, as desired, in a forwards orientation or a backwards orientation on the base, so that the same base can be used to create wheelchairs with different directions of travel.