Description of Invention

This invention relates to electrically propelled vehicles, which each include a removable drive assembly.

The invention has been devised in relation to the type of vehicle whose purpose is to carry a person whose mobility is impaired. For example, the vehicle may be a wheelchair. Many such vehicles are adapted to be comparatively readily dismantled, and/or folded, collapsed, or otherwise converted, to a relatively compact configuration to enable them conveniently to be stored, or transported in another vehicle. Such dismantling or conversion may involve the removal of one or more drive assemblies from the remainder of the vehicle. Such a removable drive assembly may comprise an electric motor, reduction gear box, and a single wheel (two such drive assemblies being provided for the two driving wheels of a powered wheelchair) or possibly may comprise an axle assembly which includes an electric motor, reduction gear which may incorporate a differential gearing arrangement, and two drivable wheels at the ends of the axle assembly. In addition to the conversion of the vehicle to a compact, readily stored or transported, condition, the or each such drive assembly is a relatively heavy unit and its or their removal reduces the vehicle to units which are more readily handled and lifted.

In broad terms, the requirements for one or more removable such drive assemblies for a vehicle are that the removal and replacement thereof from the vehicle should be relatively easy to carry out for persons who may not be mechanically adept, and this should be consistent with a high level of safety in use. It is broadly one object of the present invention to meet such requirements.

The or each drive assembly of an electrically propelled vehicle according to the invention incorporates an electric motor, and this of course requires an electrical connection to be made to the motor. Such electrical connection should be capable of being broken when the drive assembly is to be removed, since it is usual for batteries for powering the vehicle and control gear

to be carried by the frame of the vehicle. For reasons of safety, it is desirable that the electrical connection should not be able to be established with the motor of the drive assembly until the drive assembly is properly connected to the frame of the vehicle.

With this more particular object in mind, according to one aspect of the invention we provide a vehicle including a frame, a drive assembly including an electric motor and at least one ground-engaging wheel; inter-engaging formations associated with the drive assembly and frame and providing a releasable connection therebetween; catch means for holding said formations in engagement, said catch means being movable between a retaining position in which it holds said formations in engagement and a releasing position in which it permits disengagement thereof; and releasable electrical connector means for establishing an electrical connection to the motor of the drive assembly; wherein the catch means permits the electrical connection to be established by the electrical connector means only when the catch means is in its retaining position.

Preferably when the electrical connector means is engaged it prevents the catch means from being moved to its releasing position.

According to another aspect of the invention, we provide a vehicle comprising a frame; a drive assembly including a motor and at least one ground- engaging wheel; and cooperating formations associated with the drive assembly and frame and providing a releasable connection of the drive assembly to the frame; wherein disengagement of said formations to permit removal of the drive assembly from the frame requires a downwards movement of the drive assembly relative to the frame having regard to the normal orientation of the vehicle in use.

By virtue of the provision of interengaging formations which for disengagement from one another, to remove the drive assembly from the frame, require downwards movement of the drive assembly relative to the frame, the weight of the frame of the vehicle and a person carried thereby assists in holding the drive assembly connected to the frame. There is therefore a high degree of

security of the connection of the drive assembly to the frame, against unintentional release of the drive assembly.

According to another aspect of the invention, we provide a vehicle comprising a frame; a drive assembly including a motor and at least one ground- engaging wheel; and inter-engaging formations associated with the drive assembly and frame and providing a releasable connection therebetween, and guide means for guiding the formations into correct engagement.

Preferably one of the inter-engaging formations comprises a socket formation, which has a tapered mouth for guiding a plug formation, constituting the other of the interengaging formations, into it.

The provision of formations of this configuration renders the connection of the drive assembly to the frame a comparatively straightforward operation, particularly to a person who may not have a high degree of mechanical aptitude. Preferably both the plug formation and rocket formation are of tapering configuration, to give a firm engagement therebetween without play or looseness.

Preferably two or all three aspects of the invention as above set forth are combined in a vehicle.

These and other aspects and advantages of the invention will now be described by way of example with reference to the accompanying drawings, of which:-

Figure 1 is a diagrammatic exploded perspective view of part of a vehicle according to the invention, showing the parts providing a releasable connection between the frame and drive assembly of the vehicle;

Figure 2 is a diagrammatic perspective view, from the opposite side to the view of Figure 1, of part of the vehicle;

Figure 3 is a vertical section through the assembly of Figure 1;

Figure 4 is a diagrammatic lateral view of part of the assembly.

In the drawings, part of the frame of a vehicle, such as a wheelchair, is indicated generally at 10, comprising generally vertically and horizontally extending tubular members 11, 12. A plate 13 is secured to the tubular members

11, 12 at the position where they join, being fastened by welding or by releasable fasteners such as bolts. A plate 14 is held to the plate 13, in spaced parallel relation thereto, by bolts extending through the two plates and through spacer elements 15, 16 therebetween. The spacer elements, which are made of a tough plastics material such as "Delrin" are oriented such that they converge towards one another as they extend upwardly, the spacer elements and plates 13, 14 defining a socket which as viewed in side view is of generally wedge-shaped configuration with its wide mouth at its lower end, facing downwardly. The spacer elements 15, 16 are each of generally U-shape in cross-section, defining grooves facing one another as indicated in part at 17 for the spacer element 15 and 17a for the element 16.

A drive assembly, indicated generally at 20, comprises a mounting plate 21 to which is bolted a unit comprising an electric motor 22 and worm drive reduction gear box 23, the latter having an output shaft 24 which carries a wheel 25 with tyre 26. A retainer assembly for holding the wheel on the shaft 24, and for transmitting torque from shaft to wheel, is indicated generally at 27.

Above the shaft 24, the mounting plate has a portion 28 which is of tapered configuration, having sides 29, 30 which converge towards one another as they extend upwardly. Between the sides 29, 30 there is a rectangular opening 31. The tapering of the sides 29, 30 matches that of the spacer elements 15, 16, so that upon entering of the portion 28 of the mounting plate 21 into the socket defined by plates 13, 14 and the spacers, a position is reached wherein the portion 28 of the plate 21 is engaged in the grooves of the spacers 15, 16 and firmly gripped thereby.

Catch means is provided for holding the drive assembly of the vehicle in engagement with the frame of the vehicle when the position above described has been reached. A catch element 32 is secured by bolts 32a _. to an element 36 which is pivoted about a pivot pin 33 held by flanges pressed out of the plate 13 and spring biased by a spring 34 to a position in which a nose portion 35 of the catch element extends through an opening in the plate 13 and is engageable with

the upper edge of the aperture 31 in the plate portion 28. When thus engaged it retains the drive assembly to the frame of the vehicle. To enable disconnection of the drive assembly, the catch element 32 must be pivoted with the element 36 in the clockwise direction, with respect to Figure 3, against the biasing force of the spring 34, and to enable this to be done the element 36 has an upper portion 37 which is accessible to the hand, to be pushed in the direction of arrow 38 for disengagement of the catch element as above described. The element 36 further has a downwardly extending blocking portion 39.

The bolts 32a _. holding the catch element 32 to the pivoted element 36 extend through elongated holes in the latter, so that the position of the catch element can be adjusted and set to be able to hold the plate portion 28 in a full and play-free engagement with the socket 13, 14, 15, 16. Such setting may be required during manufacture, to accommodate production tolerances, and may be altered if any wear should occur after long use.

For providing an electrical connection to the motor 22 from electrical wiring fixed to the frame of the vehicle, such wiring being connected to a suitable control mechanism and a battery or batteries which provide the power for the vehicle, an electrical socket 40 is fixed to the plate 13. The motor has electrical wires 41 extending therefrom terminating in a plug 42 engageable with the socket 40. The disposition of the socket 40 is such that the plug 42 is only able to be engaged therewith when the catch element 32 is so positioned such that the blocking portion 39 of the element 36 is clear of the socket 40. When the plug 42 is engaged with the socket 40, the presence of the plug, engageable by the blocking portion 39 of the element 36, prevents the element from being moved to disengage the catch element 32 from the plate portion 28.

Thus it is not possible to move the catch element 32 to its releasing position, to enable the drive assembly to be disengaged from the frame of the vehicle, until the plug 42 has been disengaged from the socket 40. During connection of the drive assembly to the vehicle, the blocking portion 39 prevents engagement of the plug 42 with the socket 40 until the drive assembly has been

correctly engaged with the frame of the vehicle and the catch assembly assumes the position shown in Figure 3.

The invention thus provides a vehicle such as, for example, a wheelchair, with a removable drive assembly which has several advantages in terms of safety and ease of use. The configuration of the interengaging formations of the frame of the vehicle and the drive assembly respectively as a downwardly opening socket (13, 14, 15, 16) and a plug element engageable therein (28) means that the weight of the frame of the vehicle and a person carried thereby tends to keep the drive assembly firmly in correct engagement with the vehicle in use. Such security is of course assisted by the catch element 32. The tapering configuration of the socket acts as a guide for guiding the drive assembly into correct engagement, rendering connection of the drive assembly to the frame an operation which is relatively easily carried out, particularly for a person who may not be mechanically adept or possibly even may be incapacitated. The tapering configuration of the socket and plug element also ensures that when they are engaged they do so in a positive manner without play or looseness, and the adjustability of the catch element ensures that it is operable to hold such an engagement whilst allowing for manufacturing tolerances and wear in use. The cooperation of the blocking portion 39 of the catch means with the plug and socket of the electrical connector for the motor of the drive assembly provides a further element of safety against establishment of the electrical connection if the drive assembly is not correctly fitted to the frame, and against removal of the drive assembly from the frame without electrical disconnection of the motor.

The features disclosed in the foregoing description, or the following claims, or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, as appropriate, may, separately or in any combination of such features, be utilised for realising the invention in diverse forms thereof.