GB2289245A

GB2289245A - Foldable electric wheelchair with centrally located power control unit

Info

Publication number: GB2289245A
Application number: GB9409452A
Authority: GB
Inventors: John Michael Singleton
Original assignee: Spastics Society
Current assignee: Spastics Society
Priority date: 1994-05-12
Filing date: 1994-05-12
Publication date: 1995-11-15
Also published as: GB9409452D0

Abstract

A foldable electric wheelchair has two driving wheels 13 mounted on opposed side frame assemblies 10 for driving engagement with an associated electric motor 14. The power control unit 33 for the motors 14 is located centrally between the side frame assemblies 10 in both the in-use and the folded configurations to protect the control unit 33 from side impact damage and to reduce the length of the electrical cables 35. The control unit 33 may be supported in a frame 34 which is supported on the pivots (28a), 28b of the cross braces struts (27a), 27b of the folding frame. <IMAGE>

Description

FOLDABLE ELECTRIC WHEELCHAIR This invention relates to foldable electric wheelchairs. This invention has particular application to foldable electric wheelchairs of the kind having two opposed side frame assemblies each mounting a front castor wheel and a rear wheel with an electric motor for driving engagement with the rear wheel, the two side frame assemblies having a flexible seat panel extending between them with a foldable strut assembly extending below the seat panel and pivotally connected to each side frame assembly so that the wheelchair can be extended in a "use" position in which the side frame assemblies are spaced apart with the seat panel extended whilst the wheelchair can be folded to a "compact" position in which the two side frame assemblies are brought close together by folding of the strut assembly with the seat panel collapsing between the side frame assemblies.

Such foldable electric wheelchairs of the kind defined may include various optional other fittings such as foot-rests, side panels, arm-rests, and a flexible back panel extending between rear upright members at the rear of each side frame assembly. However, these features and options are not within the scope of this invention.

As is known, the power for the electric motors is supplied by batteries which have to be mounted on the wheelchair, and commonly there are two batteries which are carried under the seat panel. However, these batteries have to be removed if the wheelchair is to be folded, and various special arrangements for mounting and supporting the batteries have to be provided.

As is also known, in order to control the power to the motors to effect the controlled driving of the wheelchair, each of the batteries has to be connected to a power control unit, and this unit is also connected to the joystick or like manual control for operation by the user.

It is an object of this invention to provide a special construction of such foldable electric wheelchair of the kind defined that provides important practical advantages over the existing types, particularly having regard to electrical efficiency and safety of the power control unit.

According to this invention, we provide a foldable electric wheelchair of the kind defined and wherein the power control unit is supported on the foldable strut assembly beneath the seat panel and is located substantially centrally between the opposed side frame assemblies.

By this special arrangement, the power control unit is supported between the two side frame assemblies and when the wheelchair is in the "use" position, the batteries are on either side thereof whilst, when the wheelchair is in the "compact" folded position, the power control unit remains in place protected from each side by the side frame assemblies that are closely adjacent thereto.

In the simplest arrangement, the foldable strut assembly includes a main cross brace having two struts which are pivotally connected together for relative folding movement about the pivot, with the upper and lower end portions of each strut being connected to and pivotally supported on respective opposed side frame assemblies.

In this arrangement, the power control unit is supported on the main cross brace on or closely adjacent to the pivot connecting the two struts.

Preferably, the foldable strut assembly includes the main cross brace and a secondary cross brace also having two struts which are pivotally connected together for relative folding movement about the pivot, with the upper and lower end portion of each strut being connected to and pivotally supported on respective side frame assemblies, and the main and secondary cross braces are at positions longitudinally spaced apart relative to the front and rear of the wheelchair.

With this preferred arrangement, the main cross brace is forward of the secondary cross brace and is substantially stronger than the secondary cross brace so that the main cross brace provides the main load bearing support to carry the majority of the weight and loads arising in service when a user is seated in the wheelchair.

The secondary cross brace is preferably spaced longitudinally from the main cross brace towards the rear of the wheelchair with the distance being sufficient for the batteries to be received between the cross braces.

Conveniently, the power control unit is also supported on the secondary cross brace on or closely adjacent to the pivot connecting the two struts of the secondary cross brace so that it extends between the two cross braces.

The folding movement of each of the cross braces is like a simple scissors movement, and the longitudinal spacing between each pair of cross braces can be arranged so that the power control unit is supported on and between the cross-braces and there is no interference on relative folding movement of the foldable strut assembly.

Conveniently, the power control unit is mounted in a support frame that extends between and is connected to each pair of cross braces at or closely adjacent to the respective pivot centre of the links of each pair.

The support frame provides a sturdy partial enclosure within which the power control unit is mounted so that it is firmly held in place whether the wheelchair be in the extended "use" position or in the "compact" folded position.

The mounting of the power control unit and support by the foldable strut assembly provides important advantages over previous arrangements in which the power control unit is mounted on one of the side frames, usually beside or near to an arm-rest, with the remote controller being connected thereto or mounted directly on the unit. With such known arrangements, the power control unit is vulnerable to side impact damage whether the wheelchair be in the extended "use" position or in the folded "compact" position. As the power control unit is a critical component for the operation of the wheelchair, such vulnerability is undesirable because damage or interference to the power control unit will render the wheelchair totally inoperable.

Furthermore, in the previous arrangements with a side mounted power control unit, various electrical cables have to be provided to connect the unit both to the batteries underneath the seat panel as well as the manual controller, e.g. a joystick or like control, and to the respective electric motors. The length of such electrical cables can be long, and because of their length, the electrical efficiency of the system is adversely effected in relation to length. By the invention with the special positioning and mounting of the power control unit, the length of electrical cables is most significantly reduced and electrical efficiency can be maximised.

Preferably, each of the two electric batteries is enclosed in a housing which is arranged to engage and be supported on a respective side frame member with a quick release device so that the user or attendant can remove the batteries prior to folding movement of the wheelchair and to replace the batteries in position when extending the wheelchair from the compact position.

Furthermore, releasable connectors for the electric cables may be provided on such battery housing and there can be safety circuits incorporated within each battery housing for safeguarding the battery against over-heating or other risks.

By providing the power control unit in the central under-slung position on and between the pair of cross braces, it is possible to use the same construction and assembly for an electric wheelchair which has either, a remote controller mounted to the front of the wheelchair for operation by the user, or, a controller mounted on the rear of the wheelchair by or as part of a rear handle for attendant operation.

Other features of and advantages achieved by this invention will be referred to later herein with reference to an exemplary embodiment of the invented foldable electric wheelchair.

An exemplary embodiment of a foldable electric wheelchair according to this invention will now be described with reference to the accompanying drawings wherein: FIGURE 1 is a side view of the wheelchair in the extended "use" position and with various parts of the wheelchair being omitted and others shown in dashed lines for clarity; FIGURE 2 is a rear view of the wheelchair as shown in Figure 1 showing the battery housings and other parts in dashed lines for clarity; and FIGURE 3 is a rear view of the wheelchair as shown in Figure 2 but shown in the folded "compact" position with the battery housings removed and other parts being shown in dashed lines for clarity.

With reference to the drawings, the wheelchair comprises two similar side frame assemblies 10 which are generally of known type. Briefly, each side frame assembly 10 includes a main frame 11 to the front of which is mounted a castor wheel 12 and to the rear of which is mounted a driving wheel 13 for driving engagement with an electric motor 14. A suitable arrangement for engaging and disengaging drive from each wheel may be provided. To the front of the wheelchair and also supported from each main frame 11 are foldable foot-rests 15.

Each main frame 11 also supports a side panel frame 16 releasably connected by suitable connections (not shown). The frame 16 may be closed by a modesty panel (not shown). The side panel frame 16 includes a socket tube 17 and an arm-rest 18 is adjustably mounted on the frame 16 by a dependent spigot portion 19 engaging in the socket tube 17. In this embodiment, a remote controller 20 with joystick is mounted on one of the arm-rests. A seat panel 21 of flexible material extends between seat tubes 22 of the two opposed side frame assemblies 10.

In this embodiment, each side frame assembly 10 includes a rear upright member 23 having a handle 24 for use by an attendant (if required).

Extending between the upright members 23 is a rear back panel 25 of flexible material. The upright members 23 may be removable by a quick release device and in some versions of the wheelchair, such upright members may be shorter or omitted depending on the requirements of the user.

The side frame assemblies 10 are connected together by a foldable strut assembly. The strut assembly comprises a main cross brace 26a and a secondary cross brace 26b which is spaced longitudinally from the main cross brace 26a. The main cross brace 26a comprises two similar substantial struts 27a which are pivotally connected together at their centres by a pivot 28a. The upper ends of each strut 27a are supported and connected to respective seat tubes 22 by short links (not shown) connected to a respective top tube 29 of the main frame 11. The lower ends of each strut 27a are pivotally supported on a respective bottom tube 30 of the main frame 11.

The secondary cross brace 26b also comprises two similar struts 27b but these are of lighter section than those of the main cross brace 26a as the secondary cross brace is not required to support the same loading as arises when the wheelchair is in use from the weight of the user seated on the seat panel. The two struts 27b are also pivotally connected together at their centres by a pivot 28b. The upper ends of each strut 27b are each pivotally connected and supported at the respective ends of the seat tube 22 whilst the lower ends 27b are pivotally supported on a respective bottom tube 30 of the main frame 11.

The pivots 28a and 28b are aligned with each other and are spaced apart longitudinally underlying the seat panel 21.

Each of the two batteries (not shown) are enclosed in a housing 31 (shown in dashed lines in Figures 1 and 2). Each housing 31 may include cradle (not shown) and each housing 31 engages the bottom tube 30 of the main frame 11 and is located thereon. The battery/housing assemblies are mounted so as to extend between the two spaced apart cross braces 26.

Each of the battery/housing assemblies can be removed and/or inserted laterally by operation of a quick release device, such as a detent catch or the like (not shown).

A power control unit 33 is a substantially rectangular box enclosing all of the control circuitry for operation of the wheelchair. The unit 33 has an upper terminal block 32 including a charger socket. The unit 33 is supported in a frame 34 which has one U-shaped strap extending around the lower sides of the unit 33 with opposed channel shaped parts extending transversely thereto engaging opposed end walls of the unit 33. The power control unit is mounted so that it extends in the fore-aft position between the adjacent batteryihousing assemblies.

The frame 34 with the power control unit 33 extends between the spaced apart cross braces and is connected at its opposed ends to the adjacent one of the cross braces 26a and 26b at or adjacent to the respective pivots 28a, 28b. The power control unit 33 is arranged so that it is supported to remain in the central position between the cross braces 26a and 26b whether these be in the extended position as shown in Figure 2 or when folded as shown in Figure 3.

The power control unit 33 has electrical cables 35 connecting it via the terminal block 32 to each of the respective batteries and other electrical cables 36 connected to the respective motors 14. In addition, there is a further cable 37 connected to the remote controller 20. The battery connection cables 35 include releasable connectors (not shown) for disconnecting same from the control unit when the batterylhousing assemblies are removed.

As will now be appreciated, by this construction and special arrangement, the power control unit 33 remains in the same position irrespective of whether the foldable strut assembly is extended or folded.

When the wheelchair is in the "compact" position as shown in Figure 3, the control unit is confined between the respective side frames 10 and these provide protection against damage for the unit.

By mounting the power control unit 33 beneath the seat panel 21 and between the batteries, stability of the wheelchair is increased as there is no uneven distribution of mass and the control unit is substantially in line with the longitudinal direction of straight travel as well as assisting in maintaining a low centre of gravity. Even when the wheelchair is in the folded position, the mass of the control unit mounted centrally and between the respective side frame assemblies will maintain the central and low centre of gravity as will facilitate stable handling of the folded wheelchair.

In addition, the length of electrical cables between the power control unit 33 and the batteries is very short, and would be much longer if the control unit 33 was mounted in an upper position near to one of the armrests as has usually been done before. The shortness of such cables ensures electrical efficiency because resistance power loss caused by long cables is obviated.

Furthermore, if it is desired to have a remote controller mounted for attendant use at the rear of the wheelchair, this can be mounted on one of the rear upright members 22 without modifying the general arrangement of the control unit 33 and the cabling to and from the batteries and motors.

Although in the embodiment just described and as shown, there are two cross braces comprising the foldable strut assembly, in certain arrangements the secondary cross brace may be omitted with the power control support unit only being supported from one end by the main cross brace.

The same arrangement for mounting the power control unit 33 can be utilised for wheelchairs of different sizes as the size differences are commonly just accommodated by different seat and back panels and different lengths of links of the foldable strut assembly. This means that economies in material and manufacturing can be achieved.

The invention is not limited to the particular style of wheelchair as depicted in the embodiment as shown and described.

The control unit may be of varying sizes depending upon the application and power requirements, and the supporting frame for the power unit may take different forms such as a basket or cradle, and in some cases the connection could be by mountings provided integrally in the unit casing.

The invention can be applied to special forms of wheelchairs used for sporting or like activities in which lightweight and minimum side frames are used or even omitted. The wheelchair could have removable cushions supported on the seat and/or rear panels, and special customised supports or different foot-rests or leg supports can be provided.

Other features of foldable electric wheelchairs of the general kind first-mentioned herein will be known to those skilled in this field, and the advantages of this invention will be appreciated by the reference herein to the exemplary embodiment which is not a restrictive limitation on the scope of this invention.

Claims

Claims:

1. A foldable electric wheelchair of the kind defined wherein the power control unit is supported on the foldable strut assembly beneath the seat panel and is located substantially centrally between the opposed side frame assemblies.

2. A wheelchair according to Claim 1 wherein the batteries are supported on the opposed side frame assemblies on either side of the power control unit.

3. A wheelchair according to Claim 1 or Claim 2 wherein the foldable strut assembly includes a main cross brace having two struts which are pivotally connected together for relative folding movement about the pivot, with the upper and lower end portions of each strut being connected to and pivotally supported on respective opposed side frame assemblies.

4. A wheelchair according to Claim 3 wherein the power control unit is supported on the main cross brace on or closely adjacent to the pivot connecting the two struts.

5. A wheelchair according to Claim 3 or Claim 4 wherein the foldable strut assembly further includes a secondary cross brace having two struts which are pivotally connected together for relative folding movement about the pivot, with the upper and lower end portion of each strut being connected to and pivotally supported on respective side frame assemblies, and the main and secondary cross braces are at positions longitudinally spaced apart relative to the front and rear of the wheelchair.

6. A wheelchair according to Claim 5 wherein the main cross brace is forward of the secondary cross brace and is substantially stronger than the secondary cross brace so that the main cross brace provides the main load bearing support to carry the majority of the weight and loads arising in service when a user is seated in the wheelchair.

7. A wheelchair according to Claim 5 or Claim 6 wherein the secondary cross brace is spaced longitudinally from the main cross brace towards the rear of the wheelchair with the distance being sufficient for the batteries to be received between the cross braces.

8. A wheelchair according to any one of Claims 5 to 7 wherein the power control unit is supported on the secondary cross brace on or closely adjacent to the pivot connecting the two struts of the secondary cross brace so that it extends between the two cross braces.

9. A wheelchair according to any one of Claims 5 to 8 wherein the folding movement of each of the cross braces is like a simple scissors movement, and the longitudinal spacing between each pair of cross braces can be arranged so that the power control unit is supported on and between the cross-braces and there is no interference on relative folding movement of the foldable strut assembly.

10. A wheelchair according to any one of Claims 5 to 9 wherein the power control unit is mounted in a support frame that extends between and is connected to each pair of cross braces at or closely adjacent to the respective pivot centre of the links of each pair.

11. A wheelchair according to any one of the preceding Claims wherein each of the two electric batteries is enclosed in a housing which is arranged to engage and be supported on a respective side frame member with a quick release device so that the user or attendant can remove the batteries prior to folding movement of the wheelchair and to replace the batteries in position when extending the wheelchair from the compact position.

12. A wheelchair according to any one of the preceding Claims wherein each battery housing has releasable connectors for electric cables connecting the battery to the power control unit.

13. A wheelchair according to any one of the preceding Claims wherein a remote controller Is mounted to the front of the wheelchair for operation by the user andlor a remote controller is mounted on the rear of the wheelchair by or as part of a rear handle for operation by an attendant.

14. A foldable electric wheelchair comprising two opposed side frame assemblies each mounting a wheel having a battery operated electric motor for driving engagement with the wheel, a foldable strut assembly extending between and connected to each side frame assembly so that the wheelchair can be folded from a "use" position in which the side frame assemblies are spaced apart to a "compact* position in which the side frame assemblies are brought close together, and a power control unit located substantially centrally between the opposed side frame assemblies in the "use" position for controlling operation of the motors in response to actuation of a remote controller arranged for operation by a user seated on the wheelchair andior by an attendant.

15. A foldable electric wheelchair substantially as hereinbefore described with reference to the accompanying drawings.