EP3351228B1

EP3351228B1 - Modular wheel assembly for a wheelchair

Info

Publication number: EP3351228B1
Application number: EP17205230.0A
Authority: EP
Inventors: David Davies
Original assignee: Sunrise Medical GmbH and Co KG
Current assignee: Sunrise Medical GmbH and Co KG
Priority date: 2016-12-14
Filing date: 2017-12-04
Publication date: 2019-09-11
Anticipated expiration: 2037-12-04
Also published as: EP3351228A1; DE102016124424A1

Description

The present invention relates to a wheelchair comprising two modular wheel assemblies.
Power wheelchairs or motorized wheelchairs, power chairs, or electric wheelchairs, are traditionally equipped with an energy source, such as batteries, to power the wheelchair. Many different styles of power chair drive systems exist, among them four-wheeled power chairs that have a front wheel drive or a rear wheel drive.
Converting a power chair from front wheel drive to rear wheel drive is usually done by rotating the seat around relative to the power chair base to create either a front wheel driven power chair, or a rear wheel driven power chair. For example, US 6,290,011 B1 describes a front wheel/rear wheel drive convertible wheelchair, where a seat assembly is adapted to be reversed in direction relative to a seat support. Here, the user either faces forward with the drive wheels at the front or at the rear. To reverse this, the seat is rotated 180° an then re-fixed.
However, converting a wheelchair from front wheel drive to rear wheel drive by rotating the seat has several disadvantages. As for example, the center of gravity is never optimized for each of both cases, since the relationship between the user and seat mass to wheel position remains similar between front wheel drive and rear wheel drive. This 'compromise' results in reduced stability and drive traction.
Also, where the seat has powered options such as recline, tilt and lift, the obvious location for the wiring connections between the seating and powerbase would be near the rear of the seat. This is where the actuators are generally located and where the tilt 'hinge' point is. Therefore, rotation of the seat through 180° requires the re-routing of the connecting wires. In one configuration of the seat, this requires the wires to run across the top of the batteries from the rear of the seat to the front of the base. Therefore, different wires of different lengths are required when converting between front wheel drive and rear wheel drive.
A modular power drive wheelchair according to US 5,156,226 is provided for rapid assembly and/or disassembly of relatively compact modular components. The wheelchair comprises a base module including a base frame and related support wheels, wherein the base frame is adapted for facilitated mounting or dismounting of a seat module. A battery module including at least one storage battery is provided for relatively easy slide fit mounting onto the base frame at a position below the seat module. A controller module is also provided for mounting onto the base module and functions during wheelchair operation to control battery powered operation of one or more drive motors coupled to the wheelchair wheels. The various modules are designed for rapid disassembly to permit easy transporting of the wheelchair, for example, within the trunk of a standard automobile. Moreover, the base and seat modules are designed for relatively easy size adjustment to accommodate changing size requirements, for example, of a growing child.
US 2015/0175227 A1 describes a modular mobile vehicle with an adjustable wheelbase, which has a ready-made vehicle body, at least one wheelbase actuator and a seat module mounted on the ready-made vehicle body. The ready-made vehicle body has at least one motor, at least one rear wheel, two horizontally mounted guiding tubes, a front wheel frame slidably mounted around the two guiding tubes, and at least one front wheel. The at least one wheelbase actuator is mounted on the ready-made vehicle body, is located between the two guiding tubes, and is extendably connected with the front wheel frame. The seat module is mounted on the ready-made vehicle body and has a seat body detachably mounted on the ready-made vehicle body
A transportable power wheelchair is disclosed in EP 1 522 293 A2 which employs a variety of detachable modules to facilitate transportation and storage. The wheelchair may be readily disassembled/reassembled by a single individual without assistance and/or the need for special tools. The wheelchair includes a power supply unit, a pair of primary drive wheels, and a drive train subassembly mounting and independently driving each at least one of the drive wheels. First and second main frame subassemblies preferably have mounted thereon one of the drive train subassemblies. The power supply unit is also detachably mounted therebetween. At least one cross member assembly connects the main frame subassemblies. The cross member assembly, in combination with the main frame subassemblies, define the main frame assembly. A seat is also detachably mounted to the main frame assembly by means of the cross members.
A powered wheelchair for disabled persons is provided with US 6,290,011 B1 that has a frame that has a first end and a second end. A seat support is coupled to the frame between the first and second ends. A pair of swivel wheels is coupled to the frame proximate the first end and a pair of motor driven wheels is connected to the frame proximate the second end. A motor is coupled to each of the driven wheels. The motors are adapted to allow a change in the rotational direction of the driven wheel to which it is coupled, wherein the rotational direction of the motors may be changed when the wheelchair is converted from a rear wheel drive wheelchair to a front wheel drive wheelchair. At least one battery is coupled to the motors, the battery providing power to the motors. An electronic controller is coupled to the motors and the battery. The controller has a user interface that is used to direct the speed and direction of the wheelchair. A seat assembly is reversibly coupled to the seat support and extends upwardly above the frame. The seat assembly has an extension member coupled thereto that is adapted to be reversed in direction relative to the seat support. The seat assembly further includes a seat base having a front edge. The seat base may thus be located so that the front edge is located generally over the swivel wheels to provide a rear wheel drive wheelchair and may be reversed so that the front edge is located generally over the driven wheels to provide a front wheel drive wheelchair. The rotational direction of the driven wheels may be reversed so that a forward command from the controller results in a different rotation when the wheelchair is in a rear wheel drive configuration as compared to a forward command when the wheelchair is in a front wheel drive configuration.
There is need for an improved wheelchair that overcome the above mentioned disadvantages.
This need is achieved according to the invention by a wheelchair of claim 1.
Preferred wheelchairs of the invention are described in claims 2 to 11.
The invention is based on the surprising finding that by keeping the orientation of the seat to power chair base constant, the wiring connections between the seat and the power chair base remains also constant. Advantageously, the wiring looms are always the same whether the chair is configured front wheel drive or rear wheel drive. Therefore, only one design of looms needs to be utilized. Also, the location of the seat height adjustment posts and seat interface remains constant to the battery box as well as the location of the controller within the battery box, and the location of the rear lights relative to the battery box. Hence, the design of the chair can be simplified. Also, since the arrangement of the key components is always the same, training and documentation as regards spares and maintenance is simplified. This also reduces the amount of spare parts needed for the design.
In a further advantage, the frame member comprises at least one first connection member and a second connection member for connecting the modular wheel assembly to a connection point on the base of the wheelchair. Here, the first connection member can be arranged on the frame member so that the drive wheels are positioned towards the centre of the power chair base, and the second connection member can be arranged on the frame member so that the drive wheels are positioned away from the power chair base.
This allows to compensate for different relationships between the drive wheels and the base structure of the wheelchair so that the centre of gravity can be optimized for front wheel drive and rear wheel drive. In particular, when rear wheel drive is chosen, it is important for good traction between the drive wheels and the ground that the rear wheels are located in a forward direction, i.e. towards the wheelchair centre. If the wheels are located towards the rear of the structure, i.e. towards the battery box, then the traction will be limited. The seat location on the rear wheel drive wheelchair base will be towards the front of the base to accommodate the footrests protruding down from the seat structure in front of the base structure. Because the seat has to be located in a forward location, i.e. due to physical space then the centre of gravity will be between the centre of the wheelchair structure and a little forward of this. Whereas, when forward wheel drive is chosen, traction is rarely an issue as the center of gravity position is always towards the front, i.e. to accommodate the footrest as described above, near to where the drive wheels are located. However, forward wheel drive wheelchairs suffer from stability issues, because the center of gravity is near to the front of the chair there is a tendency for the chairs to tip forward when stopping quickly or going down slopes.
Therefore, by using the first and second connection members for connecting the modular wheel assembly to the connection point on the power chair base improves 'tipping' stability.
Also, by using modular wheel assemblies, the modular wheel assemblies can be located onto the power chair base in both a front wheel drive and rear wheel drive configuration by swapping the two modular wheel assemblies from the left hand side to the right hand side of the power chair base and vice versa.
Further, by providing the modular wheel assemblies in a first configuration, and in a second configuration allows to achieve a small lateral width between the castor wheel when used in a front wheel drive configuration, which provides a more stable driving performance, and a larger lateral width between the castor wheels when used in a rear wheel drive configuration which provides more space to accommodate the castor wheels and footrest.
Further advantages and features of the invention are presented in the following description in which a preferred embodiment of the invention is shown by the help of the enclosed figures, in which

Figures 1a, 1b: are perspective views of a wheelchair according to embodiments of the invention configured in a front wheel drive mode and in a rear wheel drive mode;
Figure 2: is a side view of a modular wheel assembly of a wheelchair according to one embodiment of the invention;
Figures 3a, 3b: are top views of a wheelchair according to embodiments of the invention configured in a front wheel drive mode and in a rear wheel drive mode; and
Figures 4a, 4b: are side views of a wheelchair according to embodiments of the invention configured in a front wheel drive mode and in a rear wheel drive mode, and having foot supports installed.

Figures 1a, 1b show perspective views of a wheelchair 1, 1' according to embodiments of the invention configured in a front wheel drive mode and in a rear wheel drive mode.
As shown in figure 1a, the wheelchair 1 comprises two modular wheel assemblies 3, 3', where one of the modular wheel assemblies 3, 3' is connected to each side of the wheelchair 1 at a modular power chair base 5. The modular wheel assemblies 3, 3' comprise a frame member 7, 7' comprising a castor wheel 9, 9' and a drive wheel 11, 11' each. In the shown example, the modular wheel assemblies 3, 3' also comprise a castor arm 13, 13' with a castor fork 15, 15' each for supporting the respective castor wheel 9, 9'. Also, as it can be seen from figure 1a, the wheelchair 1, 1' comprises a motor mount arm 17, 17' that carries a motor 19, 19' and the drive wheel 11, 11'.
The wheelchair 1, 1 ' shown in figures 1a, 1b comprises a seat 21 mounted on top of the modular power chair base 5.
Modular wheel assemblies 3, 3' according to a first configuration and of a second configuration are mounted on the modular power chair base 5. In the first configuration, the drive wheel 11 is arranged offset to a first side of the frame member 7 out of alignment of a centerline of the frame member 7 so that the drive wheel 11 sticks out to the side of the wheelchair 1. In the second configuration the drive wheel 11' sticks out to the opposite side of the wheelchair 1 as it can be best seen from figure 1b. However, the skilled person would know that the invention could be also carried out when two identical wheels assemblies are installed on both sides of the modular power chair base, where the drive wheels are essentially arranged in alignment with the centerline of the frame member.
As it can be seen from figure 1a, the wheelchair 1 has the larger drive wheels 11, 11' at the front. In this mode, the centre of gravity is more forward of the centre of the modular power chair base 5, i.e. near the drive wheels 11, 11' to ensure traction between the tires and ground. When such a wheelchair 1 is driven on an uneven surface or at higher speeds, the wheelchair 1 tends to 'fish tail'. This is an unintended motion of the rear of the wheelchair 1 oscillating left/right. Small directional corrections at the drive wheels 11, 11' or changes in direction caused by the road surface are exaggerated at the rear extremity of the wheelchair 1. Also often associated with this is castor flutter; castor flutter is the rapid and uncontrolled oscillation of the castor wheels 9, 9'. This is initiated by the 'fish tailing' and caused by the relatively low downward load on the castor wheels 9, 9', i.e. due to the forward centre of gravity, and relatively heavy mass of the castor wheels 9, 9'. This phenomenon gets worse at higher speeds. Therefore, small lateral dimensions between the castor wheels 9, 9' provides a better (more stable) driving performance.
Figure 1b essentially shows the arrangement of figure 1a, however, the the two modular wheel assemblies 3, 3' are swapped on the sides of the of the modular power chair base 5. Thus, the wheelchair 1' is adapted to be converted from a front wheel drive mode to a rear wheel drive mode (and vice versa) by swapping the two modular wheel assemblies 3, 3' on the sides of the of the modular power chair base 5. In the rear wheel drive mode configuration that is shown in figure 1b, the larger drive wheels 11, 11' are at the rear. Therefore the castor wheels 9, 9' and their support are located at the front of the wheelchair 1', in the same area where the footrests (not shown in figures 1a, 1b) could be located .
Figure 2 shows a side view of a modular wheel assembly 3 for a wheelchair according to one embodiment of the invention. The shown modular wheel assembly could be one of the modular wheel assemblies 3 shown in figures 1a, 1b.
As it can be seen from the figure, the modular wheel assembly 3 comprises a first connection member 23a, and a second connection member 23b. The position of the second connection member 23b is offset from the position of the first connection member 23a. For example, the connection members 23a, 23b could be offset in the same horizontal plane by a distance ranging from 20mm to 100mm, preferably offset by a distance of 20mm. Both connection members 23a, 23b are suitable to be connected to the connection point on the modular power chair base 5 of the wheelchair. However, depending on whether a front wheel drive mode or a rear wheel drive mode is desired by the user, only one of the connection members 23a, 23b is connected to the connection point. Therefore, the first connection member 23a is arranged on the frame member 7 so that the drive wheel 11 is positioned away from the center of the modular power chair base 5 when the modular wheel assembly 3 is connected to the connection point on the modular power chair base 5 of the wheelchair by the first connection member 23a, and the second connecting 23b member is arranged on the frame member 7 so that the drive wheel 11 is positioned towards the centre of the modular power chair base 5 when the modular wheel assembly 3 is connected to the connection point on the modular power chair base 5 of the wheelchair by the second connection member 23b.
Therefore, in the shown embodiment, a connection of the first connection member 23a to the connection point on the modular power chair base 5 corresponds to a front wheel drive mode of the wheelchair, and a connection of the second connection member 23b to the connection point corresponds to a rear wheel drive mode of the wheelchair. However, in another embodiment, which is not shown in the figures, there could be alternatively, i.e. to achieve the same effect, two connection points arranged on each side of the modular power base 5 that connect to one connection member on the modular power chair base.
Figures 3a, 3b are top views of a wheelchair 1, 1' according to embodiments of the invention configured in a front wheel drive mode and in a rear wheel drive mode. The shown wheelchairs 1, 1' and modular wheel assemblies 3, 3' could be the wheelchairs and modular wheel assemblies that are shown in the previous figures. Figure 3a shows the wheelchair 1 in a front wheel drive mode as also shown in figure 1a, and figure 3b shows the wheelchair 1' in a rear wheel drive mode as also shown in figure 1b. Both figures 3a, 3b show that the castor arms 13, 13' could be also spaced, e.g. bend, to a side of the frame members 7, 7' to carry the respective castor wheel 9, 9' out of alignment of the centerline of the respective frame member 7, 7'.
Advantageously, by having the castor arms 13, 13' shaped as shown in figures 3a, 3b allows to achieve small lateral dimensions between the castor wheels 11, 11' when the wheelchair 1 is configured in the front wheel drive mode to provide a better, i.e. more stable, driving performance. On the other hand, when the modular wheel assemblies 3, 3' are swapped around on the modular power base of the wheelchair 1' as shown in figure 3b, i.e. the wheelchair 1' is configured in the rear wheel drive mode, larger lateral dimensions between the castor wheels 11, 11' provides more space to accommodate the castors and footrests (not shown in figures 3a, 3b).
Figures 4a, 4b are side views of a wheelchair 1, 1' according to embodiments of the invention configured in a front wheel drive mode and in a rear wheel drive mode, and having a foot support 25 installed.
Wheelchairs normally provide a leg/foot support, these come in two general formats: Individual footrests - one left, one right of the centreline. These can be fixed or swing away to aid user access. They come in various leg angles and can be electrical operated.
Centre Mount footrest - one single device located on the wheelchair centerline (not shown in figures 4a, 4b).
As it can be seen from the figures, the foot supports 25 are located on the front edge of the wheelchair seat 21, the clinical aim is to provide a 90° knee angle, i.e. the angle between the thigh and lower leg. To minimize the overall length of the wheelchair 1,1', i.e. to minimize the turning circle, and to provide a stable chair, i.e. one that does not tip forward, the seat front edge and the drive wheels usual coincide. Therefore the usual footrest used on front wheel drive wheelchairs 1 are Centre mount version as these avoid collisions with the drive wheels. However, the design according to the invention allows to use one common foot support 25 that can be used for both modes.

Reference sign list

1, 1': wheel chair
3, 3': modular wheel assembly
5: modular power chair base
7, 7': frame member
9,9': castor wheel
11, 11': drive wheel
13, 13': castor arm
15, 15': castor fork
17, 17': motor mount arm
19, 19': motor
21: seat
23a, 23b: first and second connection member
25: foot support

Claims

A wheelchair (1, 1'), comprising:
at least one modular power chair base (5) comprising at least one connection point on each side of the modular power chair base (5) for connecting at least one modular wheel assembly (3, 3') to each side of the modular power chair base (5); and

at least two modular wheel assemblies, each comprising:
a frame member (7, 7'),

at least one castor wheel (9, 9') attached to the frame member (7, 7'),

at least one drive wheel (11, 11') attached to the frame member (7, 7'), and

at least one castor arm (13, 13') adapted to carry the castor wheel (9, 9'),

wherein
• the frame member (7, 7') comprises at least one first connection member (23a) for connecting the modular wheel assembly (3, 3') to a connection point on the modular power chair base (5) of the wheelchair (1, 1'),

• in a first configuration, the drive wheel (11, 11') is arranged offset to a first side of the frame member (7, 7') out of alignment of a centerline of the frame member (7, 7'),

• in a second configuration, the drive wheel (11, 11') is arranged offset to the second side of the frame member (7, 7') out of alignment of the centerline of the frame member (7, 7'), and

• the second side is opposite to the first side,

wherein one modular wheel assembly (3, 3') is connected to each side of the modular power chair base (5), and

the two modular wheel assemblies comprise one modular wheel assembly (3, 3') of the first configuration, and one modular wheel assembly (3, 3') of the second configuration, and

the wheelchair (1, 1') is adapted to be converted between the front wheel drive mode configuration and the rear wheel drive mode configuration by swapping the two modular wheel assemblies on the sides of the modular power chair base (5).
The wheelchair (1, 1') according to claim 1, characterized in that
each castor arm (13, 13') comprises at least one castor fork (15, 15') for supporting the castor wheel (9, 9').
The wheelchair (1, 1') according to claim 1 or 2, characterized in that
in the first configuration, the castor arm (13, 13') is spaced to the second side to carry the castor wheel (9, 9') out of alignment of the centerline of the frame member (7, 7'), and
in the second configuration, the castor arm (13, 13') is spaced to the first side to carry the castor wheel (9, 9') out of alignment of the centerline of the frame member (7, 7').
The wheelchair (1, 1') according to one of the preceding claims, characterized in that each frame member (7, 7') comprises at least one second connection member (23b) for connecting the modular wheel assembly (3, 3') to the connection point on the modular power chair base (5) of the wheelchair (1, 1').
The wheelchair (1, 1') according to claim 4, characterized in that
the position of the second connection member (23b) is offset essentially in the same horizontal plane from the position of the first connection member (23a), preferably offset by a distance ranging from 20mm to 100mm, preferably offset by a distance of 40mm, and wherein a connection of the first connection member (23a) to the connection point corresponds to a front wheel drive mode configuration of the wheelchair (1, 1'), and a connection of the second connection member (23b) to the connection point corresponds to a rear wheel drive mode configuration of the wheelchair (1, 1').
The wheelchair (1, 1') according to claims 4 or 5, characterized in that
the first connection member (23a) is arranged on the frame member (7, 7') so that the drive wheel (11, 11') is positioned away from the center of the modular power chair base (5) when the modular wheel assembly (3, 3') is connected to the connection point on the modular power chair base (5) of the wheelchair (1, 1'), and wherein
the second connection member (23b) is arranged on the frame member (7, 7') so that the drive wheels (11, 11') are positioned towards the centre of the modular power chair base (5) when the modular wheel assembly (3, 3') is connected to the connection point on the modular power chair base (5) of the wheelchair (1, 1').
The wheelchair (1, 1') according to one of the preceding claims, characterized in that
each modular wheel assembly (3, 3') comprises at least one suspension member, wherein the frame member (7, 7') is adapted to support the suspension member.
The wheelchair (1, 1') according to one of the preceding claims, characterized in that
each modular wheel assembly (3, 3') comprises at least one motor mount arm (17, 17') adapted to carry at least one motor (19, 19') and the drive wheel (11, 11').
The wheelchair (1, 1') according to one of the preceding claims characterized in that
the wheelchair (1, 1') comprises a seat (21) mounted on top of the modular power chair base (5), preferably the seat (21) is rigidly fixed to the modular power chair base (5).
The wheelchair (1, 1') according to one of preceding claims, characterized in that
the wheelchair (1, 1') comprises at least one leg support and/or at least one foot support (25).
The wheelchair (1, 1') according to one of preceding claims, characterized in that
the modular power chair base (5) comprises at least one further connection point on each side of the modular power chair base (5) for connecting the first connection member (23a) or the second connection member (23b) of the modular wheel assemblies (3, 3') to each side of the modular power chair base (5).