WHEELCHAIR

Abstract

 A wheelchair comprises a frame (10) with a seat (15) and a rolling chassis (A1,A2) on which the frame supports in suspended manner. The chassis comprises a wheel suspension assembly (A1,A2) on both sides, each with a bearing arm (25) from which a driven wheel (20) extends and at least one support wheel arm (35,45) with a support wheel (30,40). The bearing arm (25) is connected to the frame for pivoting about a first pivot axis (S1) and the support wheel arm (45) is pivotable about a second pivot axis (S2). The support wheel arm (45) of the other wheel suspension assembly (A2). The bridge (50) is connected in a hinge (S) between the two support wheel arms (45) to the frame (10) for pivoting about a longitudinal axis (L), while the pivoting support wheel arms (45) are coupled via spring and/or damper means (D) to the likewise pivoting bearing arms (25).

Description

[0001] The present invention relates to a wheelchair comprising a frame with a seat and a rolling chassis, wherein the chassis comprises a wheel suspension assembly on opposite sides of the frame, each with a bearing arm for a driven wheel and a support wheel arm for a support wheel, wherein the bearing arm is connected to the frame for pivoting about a first pivot axis lying substantially transversely of a longitudinal direction and the support wheel arm is pivotable about a second pivot axis relative to the frame, and wherein the bearing arm and the support wheel arm are provided with spring and/or damper means for thereby suspending and/or damping a pivoting movement of the bearing arm. The invention relates particularly here to a mid-wheel drive wheelchair.

[0002] A mid-wheel drive wheelchair of the type described in the preamble is known from European patent application EP 2.716.268. The wheelchair described therein comprises a rolling chassis having a set of driven wheels centrally which extend from a suspension assembly on respectively the right and left-hand side of the seat. Both driven wheels are mounted here on a bearing arm which is connected pivotally about a first pivot axis to the frame on a front side. On a rear side of each bearing arm a support wheel arm is connected pivotally about a second pivot axis to the bearing arm. Extending herefrom on a rear side of the seat is a rear support wheel which is suspended by spring and/or damper means. These spring and/or damper means also provide for a suspension of the frame with the seat thereon. The known wheelchair moreover has a set of independently pivoting and suspended front support wheels on a front side of the seat. These are each provided individually with separate spring and/or damper means mounted between the respective support wheel arm and the frame.

[0003] Although a chassis with a total of five or six wheels is thus provided which, according to said patent application, is able to maintain continuous contact with the ground surface irrespective of a variation therein, the known construction nevertheless has the drawback that the two driven wheels are not equally loaded here under all conditions, whereby slippage can occur.

[0004] The present invention has for its object, among others, to provide a wheelchair which provides a more reliable weight distribution over the driven wheels.

[0005] In order to achieve the stated object a wheelchair of the type referred to in the preamble has the feature according to the invention that the support wheel arm is coupled via a bridge to the corresponding support wheel arm of the opposite wheel suspension assembly, that the bridge between the two support wheel arms is connected to the frame for pivoting about a pivot axis lying substantially along the longitudinal direction and that the support wheel arm is coupled via the spring and/or damper means to the bearing arm. The bridge here particularly comprises a rigid body or a substantially rigid assembly of substantially rigid bodies.

[0006] The connection of the bridge to the frame provides a pressure point which is thus directly transferred by the bridge suspended pivotally relative thereto to both support wheel arms connected thereto. These two support wheel arms in turn distribute the load at least to a great extent equally over the two bearing arms with the driven wheels thereon. Both wheels thus always maintain at least substantially the same grip on the ground surface. The spring and/or damper means between the bearing arm and the support wheel arm on each of the two sides of the chassis serve primarily for a suspension and comfort of the frame with the seat thereon, but moreover urge the support wheel arms with the support wheels thereon downward in order to maintain an effective contact with the ground surface.

[0007] Although the construction according to the invention is in principle already suitable for a wheelchair with a single set of support wheels, it is preferred to equip the wheelchair with support wheels at both the front and the rear. A preferred embodiment of the wheelchair according to the invention has for this purpose the feature that the wheel suspension assembly comprises a front support wheel arm, from which a front support wheel extends, as well as a rear support wheel arm from which a rear support wheel extends, and that at least the rear support wheel arm is coupled via the bridge to the rear support wheel arm of the opposite wheel suspension assembly.

[0008] The front support wheels are located at a front side of the wheelchair, while the rear support wheels are mounted on a rear side as seen from the position of the user seated on the wheelchair and in a normal direction of travel. Use can be made here of optionally independently pivoting support wheel arms at the front and/or at the rear. In a further preferred embodiment the wheelchair according to the invention is however characterized in that the front support wheel arm of each of the wheel suspension assemblies is connected rigidly to the bearing arm, and in particular is formed integrally therewith, and that the front support wheel arm and the bearing arm extend on either side of the first pivot axis. Such a rigid connection between the front support wheel arm and the bearing arm not only provides for simplicity of construction, but also for strength and travel stability. This latter is particularly important in the case of strong acceleration and deceleration of the wheelchair.

[0009] A further preferred embodiment of the wheelchair according to the invention has the feature that the front support wheel arm is otherwise freely pivotable about the first pivot axis relative to the frame. The front support wheel arm is thus completely free to pivot about the first pivot axis together with the bearing arm and thereby maintain a good contact between the front support wheel and a ground surface in order to be able to thus accommodate to unevenness in the ground surface. In particular no further spring and/or damper means are provided here between the front support wheel arm and the frame as in the known wheelchair, as this would otherwise impede such a free pivoting of the front support wheel arm relative to the frame.

[0010] Although the bridge of the suspension assembly can per se be connected rigidly to the respective support wheel arm, a preferred embodiment of the wheelchair according to the invention has the feature that the support wheel arm is connected to the bridge for pivoting about a pivot axis lying substantially along the bridge. The support wheels here retain complete freedom to follow a ground surface irrespective of a position of the bridge about its own pivot axis. This imparts stability to the wheelchair which is thus prevented from tipping over, wherein the bridge connection moreover imparts a uniform distribution of forces.

[0011] For the purpose of a satisfactory manoeuvrability of the wheelchair, a further preferred embodiment of the wheelchair according to the invention has the feature that the support wheel comprises a swivel wheel which can swivel freely around a substantially vertically oriented swivel axis. The driven wheels are normally responsible for steering with the wheelchair. A particular embodiment of the wheelchair according to the invention has for this purpose the feature that the drive means comprise a separate motor for each driven wheel, and more particularly that the bearing arm bears the motor. Through mutually differing driving of the two wheels, the one for instance more quickly than the other or even in opposite direction, it is possible to take a bend or even rotate the wheelchair about its own axis. The swivelling support wheels here provide the wheelchair with an unimpeded manoeuvrability.

[0012] The spring and/or damper means can be of diverse nature per se. An air suspension or screw suspension can thus be applied therefor, optionally in combination with damper means. Particularly good results have however been obtained with a particular embodiment of the wheelchair which is characterized according to the invention in that the spring and/or damper means are formed by a rubber body. Here this is preferably a block element of optionally natural rubber in optionally hollow form. The spring and/or damper means can thus not only be of a simple and inexpensive design, they can also thus remain relatively compact, and thereby fit readily inside the space of a relatively compact construction of the wheel suspension assembly of the wheelchair according to the invention.

[0013] In order to enhance a natural feel for the rider and a predictable travel behaviour, a further preferred embodiment of the wheelchair according to the invention has the feature that a rotation axis of the driven wheel is located under the seat. Because the axis of the driven wheels thus extends under the seat and steering normally takes place therewith, steering of the wheelchair thus takes place about a vertical axis at the position of the user. This makes a significant contribution toward a natural feel and the ergonomics of the seat.

[0014] In respect of driving of the wheelchair a further preferred embodiment according to the invention has the feature that the drive means comprise an electric motor powered by at least one rechargeable battery, wherein the frame comprises the at least one battery. The at least one rechargeable battery is thus situated in or on the frame and the at least one battery contributes toward the total suspended mass of the seat. This will usually be a relatively heavy battery pack which will thus contribute to considerable extent toward a travel comfort of the seat.

[0015] The invention will be further elucidated hereinbelow on the basis of an exemplary embodiment and an accompanying drawing. In the drawing:

Figure 1

shows a side view of an exemplary embodiment of the wheelchair according to the invention;

Figure 2

shows a rear view of the wheelchair of figure 1; and

Figure 3

shows a top view of the wheelchair of figure 1.

[0016] It should otherwise be noted that the figures are purely schematic and not always drawn to (the same) scale. Some dimensions in particular may be exaggerated to greater or lesser extent for the sake of clarity. Corresponding parts are designated in the figures with the same reference numeral.

[0017] The wheelchair of figure 1 comprises a frame 10 having thereon a seat 15 on which a user can sit. The wheelchair is mobile due to a rolling chassis on which frame 10 supports in suspended manner. The chassis comprises here an identical wheel suspension assembly A1,A2 on both sides of the frame which will be described in further detail hereinbelow. The shown wheelchair is a mid-wheel drive wheelchair with a set of driven wheels 20 on respectively the left and right-hand side of the seat between a set of front support wheels 30 and a set of rear support wheels 40.

[0018] For driving of the wheelchair both driven wheels 20 have a separate electric motor, which is not further shown but which is assumed sufficiently known to a skilled person. Power supply to the electric motors is provided by a rechargeable battery pack, which is likewise not further shown but assumed sufficiently known to a person with ordinary skill in the art, and which is accommodated under seat 15 in frame 10 and thereby contributes toward the total suspended mass of the seat. Located within reach or otherwise manipulable from seat 15 is a control (not further shown) with which the drive of wheels 20 forward and/or rearward can be activated and with which it is possible for the user to steer.

[0019] The wheel suspension assemblies A1,A2 each comprise a bearing arm 25 connected at a proximal end for pivoting about a first pivot axis S1 to frame 10. At a distance from pivot axis S1 the bearing arm 25 bears a driven wheel 20 which is rotatable about a horizontal wheel axis W. The electric motor is also usually mounted on or at this bearing arm 20 together with a transmission which provides for autonomous driving of the respective wheel 20. Suspension assembly A1,A2 comprises on a rear side of the seat a rear support wheel arm 45 from which a rear support wheel 40 extends. The rear support wheels are embodied here as swivel wheels which can swivel freely about an individual swivel axis Z. For this purpose the rear support wheel arm 45 comprises at a distal end an axle bushing 47 with bearing for receiving therein a shaft of a wheel fork 43 of the respective swivel wheel 40.

[0020] According to the invention the support wheel arms 45 of both wheel suspension assemblies A1,A2 are mutually connected by means of a bridge 50. Bridge 50 is connected in a hinge S to frame 10 for pivoting about a longitudinal axis L lying in a direction of travel. The two support wheel arms 45 are in turn connected to bridge 50 for pivoting about a second pivot axis S2 directed along bridge 50, and are thereby free to pivot about a substantially vertical plane relative to bridge 50, and thereby relative to the frame. At a proximal end the support wheel arm 45 is suspended from bearing arm 25 via spring and/or damper means D. Spring means D here comprise a rubber body, but can optionally also comprise a screw spring or air spring, optionally in combination with a damper.

[0021] Spring means D are mounted between bearing arm 25 and rear support wheel arm 45, which are in turn free to pivot around respectively the first pivot axis S1 and the second pivot axis S2 relative to frame 10. Rubber body D here not only provides for a suspension and comfort of the frame, but moreover transmits a pressure from bearing arm 25 to rear support wheel arm 45. This imparts a downward pressure to the respective rear support wheel arm 45 for a good contact of the rear support wheel 40 mounted thereon with the ground surface.

[0022] Bridge 50 can be formed in one part and for this purpose be shaped or cast in a desired form, or be assembled from parts welded or otherwise rigidly connected to each other. In both cases the bridge provides a rigid connection between rear support wheel arms 45 on the right and left-hand side, whereby they are mutually coupled. The pivoting suspension S3 at the outer end nevertheless provides for independent support on the ground surface, whereby an optimal ground contact is enhanced irrespective of a possible unevenness of the ground surface.

[0023] Suspension assembly A1,A2 comprises on a front side of the seat a front support wheel arm 35 from which a front support wheel 30 extends. Front support wheel 30 are likewise embodied as swivel wheels and can swivel freely about an individual swivel axis Z. For this purpose the respective front support wheel arm 35 comprises at a distal end an axle bushing 37 with bearing for receiving therein a shaft of a wheel fork 33 of the respective front support wheel 30. Each of the front support wheel arms 35 is rigidly connected to bearing arm 25 of the respective wheel suspension assembly A1,A2 and connected together therewith to frame 10 for pivoting about the first pivot axis S1. The front support wheel arms 35 are not coupled to frame 10, and particularly not connected thereto via further spring and/or damper means, and are thus unimpeded in their swivelling relative to the frame.

[0024] The invention thus provides an exceptionally stable and durable chassis for a driven wheelchair, in particular a mid-wheel drive wheelchair as shown. Although the invention has been further elucidated here on the basis of only a single exemplary embodiment, it will be apparent that the invention is by no means limited thereto. On the contrary, many variations and embodiments are still possible within the scope of the invention for a person with ordinary skill in the art. Use is thus made in the described example of steel parts for the different structural parts, in particular the bearing arms and wheel arms, although a lightweight metal such as aluminium, titanium or magnesium, or a carbon fibre-reinforced composite material can also be used instead while still retaining strength. Instead of being embodied with two sets of support wheels, the seat can optionally also be embodied with a single set of support wheels on the rear side or front side, and use can optionally be made on the front and/or rear side of a single support wheel arm on which a single or double support wheel is mounted. The wheelchair can if desired be further equipped with diverse comfort-increasing modifications of the frame, such as for instance armrests, an optionally electrical adjustment of the seat and/or a seat massage device.

Claims

1. Wheelchair, comprising a frame with a seat and a rolling chassis, wherein the chassis comprises a wheel suspension assembly on opposite sides of the frame, each with a bearing arm for a driven wheel and a support wheel arm for a support wheel, wherein the bearing arm is connected to the frame for pivoting about a first pivot axis lying substantially transversely of a longitudinal direction and the support wheel arm is pivotable about a second pivot axis relative to the frame, and wherein the bearing arm and the support wheel arm are provided with spring and/or damper means for thereby suspending and/or damping a pivoting movement of the bearing arm, characterized in that the support wheel arm is coupled via a bridge to the corresponding support wheel arm of the opposite wheel suspension assembly, that the bridge between the two support wheel arms is connected to the frame for pivoting about a pivot axis lying substantially along the longitudinal direction and that the support wheel arm is coupled via the spring and/or damper means to the bearing arm.

2. Wheelchair as claimed in claim 1, characterized in that the wheel suspension assembly comprises a front support wheel arm with a front support wheel as well as a rear support wheel arm with a rear support wheel, and that at least the rear support wheel arm is coupled via the bridge to the rear support wheel arm of the opposite wheel suspension assembly.

3. Wheelchair as claimed in claim 2, characterized in that the front support wheel arm of each of the wheel suspension assemblies is connected rigidly to the bearing arm, and in particular is formed integrally therewith, and that the front support wheel arm and the bearing arm extend on either side of the first pivot axis.

4. Wheelchair as claimed in claim 3, characterized in that the front support wheel arm is freely pivotable about the first pivot axis relative to the frame.

5. Wheelchair as claimed in one or more of the foregoing claims, characterized in that the support wheel arm is connected to the bridge for pivoting about a pivot axis lying substantially along the bridge.

6. Wheelchair as claimed in one or more of the foregoing claims, characterized in that the support wheel comprises a swivel wheel which can swivel freely around a substantially vertically oriented swivel axis.

7. Wheelchair as claimed in one or more of the foregoing claims, characterized in that the drive means comprise a separate motor for each driven wheel.

8. Wheelchair as claimed in claim 7, characterized in that the bearing arm bears the motor.

9. Wheelchair as claimed in one or more of the foregoing claims, characterized in that the spring and/or damper means are formed by a rubber body.

10. Wheelchair as claimed in one or more of the foregoing claims, characterized in that a wheel axis of the driven wheel is located under the seat.

11. Wheelchair as claimed in one or more of the foregoing claims, characterized in that the drive means comprise an electric motor powered by at least one rechargeable battery, wherein the frame comprises the at least one battery.

Drawing