WO1991018577A1

WO1991018577A1 - Powered wheelchairs and wheels for them

Info

Publication number: WO1991018577A1
Application number: PCT/GB1991/000910
Authority: WO
Inventors: Keith Richard Bound
Original assignee: Keith Richard Bound
Priority date: 1990-06-06
Filing date: 1991-06-06
Publication date: 1991-12-12
Also published as: GB2244684A; AU7953891A; GB9012646D0

Abstract

A wheelchair (1) has four wheel units (3) each of which includes an electric drive motor (17) and transmission gears (15, 16, 18) housed within a hollow egg-shaped wheel (12), a steering motor (25), and mounting means (14, 25') adapted to secure the wheel unit (31) to the body (21) of the wheelchair. Thus each wheel (12) has its own drive motor (17) and steering motor (25) and is independently operable. Various modes of operation of the wheelchair are disclosed.

Description

Powered Wheelchairs And Wheels For Them

This invention relates to powered wheelchairs and wheels for them. The wheels may also be applied to other powered vehicles.

Battery powered electric wheelchairs normally comprise a rigid frame having a seat and four wheels. It is known to motorise the rear or front pair of wheels whilst leaving the other two wheels freely rotatable. However, unless the wheelchairs are driven over smooth, flat surfaces they can become unstable and dangerous for the occupant. With only two wheels propelling the vehicle it can lose power if one of its motorised wheels is off the ground. The occupant can also lose control if he is crossing a slope because the weight of the chair and its occupant tends to turn the two rotatable (unpowered) wheels in the direction of the slope, which causes the chair to be defected from the desired direction. Furthermore, most wheelchair designs do not go to any length to insure that the centre of gravity of the wheelchair plus occupant is low.

I am aware of published British Patent specification Number GB 2 188 889 which shows a wheelchair having four wheel drive. The wheelchair is steered by rotating wheels on the same axis at different speeds. Only a pair of wheels is steered in this specification.

I am also aware of European Patent Specification

Number 0 160 631 which shows a four wheel drive wheelchair, again having steering provided by differential speeds of rotation of wheels on the same axis. I am further aware of British Patent

Specification GB 2 184 987 which discloses a wheelchair having four wheel drive and provided with a single steering motor which is connected via couplings to each of the wheels so as to steer them.

A problem associated with using differential wheel speed to steer a wheelchair is that it places a great strain on the motor and battery of the wheelchair and tends to wear both the wheels themselves and the surface over which the wheelchair is travelling.

The aim of the present invention is to provide a new powered wheelchair, and/or to provide a new wheel unit suitable for incorporation in such a vehicle.

According to a first aspect the invention consists in a powered wheelchair having a body which carries a seat; an electronic controller; a control input station under the control of the user providing signals to the electronic controller; and a plurality of wheel units attached to the body, characterised in that each wheel unit comprises a wheel, its own drive motor, and transmission means for transmitting drive from the motor to the wheel, and also its own steering motor, the arrangement being such that each wheel is independently driven and steered by its own drive and steering motors, the electronic controller providing appropriate control signals to the motors to cause the wheelchair to respond appropriately to the signals from the control input station.

The provision of a separate steering motor for each wheel unit reduces the complexity of the mechanical steering components of the wheelchair significantly and allows each wheel to be moved independently of the others. This gives the wheelchair greater manoeuvrability.

Preferably each wheel unit comprises mounting means adapted to mount the wheel unit to the body of the wheelchair, a wheel, a drive motor operatively coupled to the wheel by transmission means adapted to transmit drive from the motor to the wheel, and is- characterised in that the drive motor is housed in the wheel itself.

Preferably the transmission means is also housed in the wheel itself.

This enables the wheel units to be particularly compact. A manufacturer can also simply buy four wheel units, bolt them to the wheelchair body, and connect up their electronics appropriately.

Preferably the drive motor and transmission means are fixed relative to the mounting unit and the wheel rotates round them.

Preferably the wheel has housing or shell means which forms a housing around the drive means and transmission means. The wheel may be hollow and the drive and transmission means may be provided inside the hollow of the wheel. The wheel may be ovate and have an oval diametral cross section. Alternatively the wheel may be generally spherical, or spherical or ovate with flattened portions.

Preferably the wheel unit includes a steering motor adapted to steer the wheel through 360 . Alternatively it may be sufficient for each wheel to be steerable through a lesser angle of, say, 180° or 270°.

The transmission means may be gears, and preferably comprises a worm gear connected to the drive motor and co-operating with a larger wheel drive gear.

The _^wheel unit preferably includes brake means, which may be operated automatically when the user places the control input station in a neutral condition.

According to a second aspect of the invention I provide a wheel unit comprising mounting means adapted to mount the wheel unit to a wheelchair or other vehicle, a wheel, and a drive motor operatively coupled to the wheel by transmission means adapted to transmit drive from the motor to the wheel, characterised in that the drive motor is housed in the wheel itself.

Preferably the transmission means is housed in the wheel itself.

Further preferable features of the wheel unit will be apparent from the foregoing statements of invention and from the specific description which follows.

I also provide a vehicle incorporating such a wheel unit..

The invention will now be described by way of example only with reference to the accompanying drawings of which:-

Figures 1 and 2 show perspective views of a wheelchair in accordance with the invention; Figure 3 shows a schematic side view of a wheel unit in accordance with a second aspect of the invention;

Figure 4 shows a schematic cross section on line IV-IV of Figure 3;

Figure 5 shows another sectional view of the wheel unit;

Figure 6 shows a schematic plan view of the wheelchair;

Figure 7 shows a schematic side view of two wheel units and suspension means of the wheelchair;

Figure 8 illustrates a joystick of the wheelchair;

Figure 9 illustrates a control panel of the wheelchair;

Figure 10 illustrates a flow chart for the operation of the wheelchair; and

Figures 11 - 22 illustrate the movement of the wheelchair when the control joystick is in various positions.

A wheelchair 1 is shown in Figures 1 to 9 and comprises a body 2 having a seat 2a and arms 2b. The wheelchair has four wheel units 3 connected to the body, and a control panel 4.

The control panel 4 comprises a joystick 5, an on/off power button 6, a speed selector button 7 capable of selecting between a slow speed of about 2 miles per hour and a fast speed of about 4 miles per hour, a "crab" button 8 (the function of which will be described later) , a front wheel only drive button 9, a rear wheel only drive button 10, and an LCD display 11. The joystick 5 has an upper portion 5a projecting above the control panel which is manipulated by the user to send signals to a microprocessor which controls the operation of the wheel units 3. The lower part of the joystick 5 comprises an electrical sensor unit 5b which sends signals indicative of the position of the manually operable part of the joystick to the microprocessor. It will be appreciated that other control input means may be provided instead of those described, for example voice control or head operated controls.

Each wheel unit 3 comprises a wheel 12 rotatably mounted on an axle 13 which is part of a wheel unit mounting column 14 connected at its upper end to the body 2 of the wheelchair (via suspension strip 26 - described later) . A wheel drive gear 15 is rotatably mounted on the axle 13 and is drivable connected to a worm gear 16 of an electric motor 17 by an intermediate gear 18. The wheel drive gear 15, worm gear 16 and intermediate gear 18 are enclosed in a gear casing 19, which is irrotationally mounted on the axle 13. Electrical control wires 14' lead through the column 14 to the motor 17. The wheel 12 comprises a wheel shell or housing 20 which is of hollow ovate form of generally circular cross section in some vertical planes and generally oval cross section in diametrical, and horizontal, planes. The wheel shell 20 has a central aperture 20a through which the axle 13 extends. A bearing 20a is provided at the aperture. The wheel shell 20 has a central hollow space 20b in which the electric motor 17 and gear casing 19 are provided. Thus the wheel surrounds the drive motor and transmission gears. The drive gear 15 is releasably connected to a wheel plate 20c which is in turn releasably connected to the main body of the shell 20.

Figure 6 illustrates the wheelchair schematically and shows the forward direction F, and front left and right wheels 21 and 22 and rear left and right wheels 23 and 24. As illustrated in Figure 7, and Figure 4, the upper end of the wheel unit mounting column 14 has a steering motor 25 and associated transmission means. The wheel units 3 (including the steering motor 25) are mounted on a metal plate 26 which is attached to the body of the wheelchair at attachment point 27.- The body of the wheelchair is preferably rotationally moulded in plastics material. The plate 26 provides suspension between the wheel units and the body of the wheelchair.

Each wheel unit 3 is a self-contained unit having a drive motor 17 and transmission gears 15, 16,18 inside the wheel, a column 14, and a steering motor 25. The unit can simply be fixed to the body 2 and its electronic control wires connected. There are no mechanical couplings to interconnect other than that attaching the entire unit 3 to the body.

When the wheelchair is first switched on the microprocessor M monitors, and indicates on the LCD display 11 whether there is a mechanical or electrical fault in the vehicle. The user can select between a slow or fast speed using button 7, four wheel drive

(where no button is pressed) , front wheel drive only when button 9 is pressed, and rear wheel drive only when button 10 is pressed. The user can also select a side-ways "crab" movement feature using button 7. The microprocessor M monitors and displays on the liquid crystal display 11 the current operational mode of the vehicle, the speed selected, and whether there is any mechanical or electrical fault.

The various ways in which the wheelchair can manoeuvre are shown in Figures 11 to 22. Figure 11 shows the movement of the vehicle when the joystick 5 is in its north position. The vehicle moves straight forwards, with all of the wheels 22-24 aligned parallel with the forward direction (referenced as F) . Similarly, when the joystick is in its south position the vehicle moves straight backwards as shown in Figure 12.

When no other button is pressed and the joystick is moved to the east position, as represented in Figure 13, each of the four wheels 21 to 24 are controlled by microprocessor M to extend at 45 to the forward direction F so that the wheels lie generally on tangents to a circle of rotation 28. When the wheels rotate in the appropriate direction (again controlled by the microprocessor) the vehicle rotates in a clockwise direction about its central axis 29 as shown in Figure 13. The microprocessor causes all of the wheels to rotate equally.

When the joystick 5 is moved to its west position shown in Figure 14 the wheels move to the same angular position as that shown in Figure 13, but rotate in the opposite direction so that the vehicle rotates about its central vertical axis 29 in an anti-clockwise position represented by circle 30. When the joystick 5 is placed in its north-east position by the user the wheels 21 and 23 take up positions inclined at 45 to the forward direction F, tangetial to a circle of rotation 31, and the wheels 22 and 24 take up positions inclined at right angles to the forward direction F. The wheels 21 and 23 are then rotated thorugh a relatively large angle whilst the wheels 22 and 24 are moved angularly only a relatively, small amount. The wheels 22 and 24 may even be caused to rotate in opposite directions by a small amount. The desired end result is that the wheelchair swings around a vertical axis 32 which is displaced from the centre of the wheelchair. The wheelchair swings around in a clockwise direction.

When the joystick 5 is placed in its south-east position the wheels rotate in the opposite direction and the wheelchair swings about the axis 32 in the opposite, anticlockwise, direction.

When the joystick 5 is placed in its south-west position the wheels 22 and 24 take up positions inclined at 45° to the forward direction and the wheels 21 and 23 are inclined at right angles to the forward direction. When the wheels 22 and 24 rotate the wheels 21 and 23 move angularly by a smaller amount in a similar manner to that discussed with reference to Figure 15. The wheelchair swings about a vertical axis 33 displaced from the central vertical axis 29 of the wheelchair by a similar amount, but in the opposite direction, to the vertical axis 32.

Figure 18 shows the arrangement when the joystick is in its northwest position. The wheels take up the same positions as when the joystick is in its south-est position but they rotate in the opposite direction. Figures 19 and 20 schematically illustrate front and rear wheel drive operation of the wheelchair when buttons 9 and 10 are pressed respectively.

Figure 21 illustrates the operation of the wheelchair when the "crab" button 8 is pressed and the joystick 5 then.moved moved to its west position. The wheels 21 to 24 all take up attitudes in which they are turned by their respective steering motors 25 to positions at right angles to the forward direction F. When the wheels are rotated the wheelchair then moves in a straight line directly sideways as shown by the arrow SI.

Figure 22 shows the arrangement when the crab button 8 is pressed and the control joystick 5 is placed in its east position. The wheels move to the same right angled position as that shown in Figure 21, but rotate in the opposite direction so that the wheelchair moves bodily to its side in direction shown by arrow S2.

It will be appreciated that in the various modes of movement the wheels are controlled individually to rotate by just the appropriate amount to arrive at the desired wheel positions. Thus some wheels may rotate more than others.

Figure 10 illustrates the operation of the wheelchair in the form of a flow chart. When button 6 is pressed to switch the power on, represented by a box 40 of Figure 10, the microprocessor M checks to see whether power is reaching the drive motor 17 and the steering motor 25 of each wheel unit 3. This is represented by box 41 of the flow chart. If the microprocessor detects that one of the motors is not receiving power it checks to see whether the batteries need recharging, shown at box 42, and if this is not the problem it then checks to see whether there is any mechanical or electrical failure, box 43, and then makes an appropriate display on the LCD 11.

Provided that the microprocessor M detects that power is indeed reaching the drive and steering motors, an operational signal is indicated on the LCD display 11 and the user selects the appropriate driving mode by pressing one of the buttons on the display panel 4. This is represented by box 44 of the flow chart. Having selected the appropriate drive mode the user then selects the drive speed, box 45, and then selects the appropriate movement of the wheelchair by using the joystick control 5 and moving it to a selected one of eight possible drive positions, box 46. The vehicle the moves under the control of the user. When the vehicle has reached its desired position the user releases the joystick 5 which is sprung so as to return to its neutral position in the centre of its possible drive positions, box 47, and this cuts the power to the drive and steer motors. When the joystick is in its neutral position a solenoid brake incorporated in each wheel unit is activated and prevents rotation of the wheel. There may be a slight delay in the operation of the solenoid brake in order for the wheel to come to rest before it operates. Alternatively the wheel may be positively braked once the joystick is moved to its neutral position. Once the user is a position in which he wishes to stay for some time he can switch off the power of the wheelchair in order to save energy. It will be appreciated that the invention also consists in a wheel unit 3, and in a vehicle incorporating such a wheel unit.

Claims

1. A powered wheelchair (1) comprising a body (2) which carries a seat (2a) ; an electronic controller (M) ; a control input station (4) under the control of the user providing signals to the electronic controller (M) ; and a plurality of wheel units (3) attached to the body (2) , characterised in that each wheel unit (3) comprises a wheel (12) , its own drive motor (17), and transmission means (15,16,18) for transmitting drive from the motor (17) to the wheel (12) , and also its own steering motor (25) , the arrangement being such that each wheel (12) is independently driven and steered by its own drive and steering motors, the electronic controller (M) providing appropriate control signals to the motors (17 and 25) to cause the wheelchair (1) to respond appropriately to the signals from the control input station (4) .

2. A wheelchair according to claim 1 characterised in that each wheel unit (3) comprises mounting means (25') adapted to mount the wheel unit (3) to the body of the wheelchair, a wheel (12) , a drive motor (17) operatively coupled to the wheel by transmission means (15,16,18) adapted to transmit drive from the motor to the wheel, and is characterised in that the drive motor (17) is housed in the wheel (12) itself.

3. A wheelchair according to claim 2 characterised in that the transmission means (15,16,18) are also housed in the wheel (12) itself.

4. A wheelchair according to any preceding claim characterised in that the drive motor (17) and transmission means (15,16,18) are fixed relative to the mounting means (25') and the wheel (12) rotates round them.

5. A wheelchair according to claim 4 characterised in that the wheel (12) has housing or shell means (20) which forms a housing around the drive means and transmission means.

6. A wheelchair according to claim 5 characterised in that the wheel is hollow and the drive and transmission means are provided inside the hollow space of the wheel.

7. A wheelchair according to any preceding claim characterised in that the wheel (12) has a generally oval cross section.

8. A wheelchair according to any preceding claim, characterised in that each wheel unit (3) includes a steering motor (25) adapted to steer the wheel.

9. A wheelchair according to any preceding claim, characterised in that the transmission means (15,16,18) comprises gears.

10. A wheel unit comprising mounting means (14,25) adapted to mount the wheel unit to a wheelchair or other vehicle, a wheel (12) , and a drive motor (17) operatively. coupled to the wheel (12) by transmission means (15,16,18) adapted to transmit drive from the motor (12) , characterised in that the drive motor (17) is housed in the wheel itself.

11. A wheel unit according to claim 10 characterised in that the transmission means (15,16,18) is also housed in the wheel itself.

12. A wheel unit according to claim 10 or claim.11 characterised in that the wheel (12) is hollow and the drive motor (17) and transmission means (15,16,18) are provided in the hollow space of the wheel, the wheel rotating around them.