GB2388574A

GB2388574A - A height adjustable wheelchair

Info

Publication number: GB2388574A
Application number: GB0211083A
Authority: GB
Inventors: Stewart Mark Scott
Original assignee: Individual
Current assignee: Individual
Priority date: 2002-05-15
Filing date: 2002-05-15
Publication date: 2003-11-19
Also published as: GB0211083D0

Abstract

The present invention is intended to provide a wheelchair that has a seat height that is adjustable from a standard position to a height at which the users eye level can be the same as that of most standing persons. A gas strut (15, figure 6) is provided to enable the seat to be raised or lowered with the user seated. A main frame 5 is connected to a chassis frame 1 by a front hinge 4 and rear link arm assemblies 19. This allows the main frame to be folded flat (figure 8) to aid storage and transportation. Two independent hand wheels 8 drive the rear wheels 2 via two drive belts 10,11. The hand wheels are connected to the seat 7, and therefore as the seat position is altered the hand wheels remain with the seat thus allowing the wheelchair to be propelled by the user when the seat is in any position. Alternatives to the gas strut and belt drives are discussed.

Description

t HEIGHT ADJSTABLE WHEELCHAIR

This invention relates to a height adjustable, foldable, self-propelled wheelchair.

Non-electric self-propelled wheelchairs consist of a fixed height seat mounted in a frame fitted with wheels. The wheelchair has large diameter rear wheels so that the user can reach the wheels with their hands and propel themselves.

This type of wheelchair with a fixed height seat has the following disadvantages: 1. The wheelchair user has difficulty in accessing items at a high level. Examples include accessing items in a kitchen or library.

2. The wheelchair user has difficulty in participating in conversations where others are standing.

3. The wheelchair user cannot see objects at a level designed for standing persons.

An example is in a museum.

4. The wheelchair user may not be able to converse faith people behind high counters. Examples include an airport check-in desk or bank.

In addition, the user propels the chair by grabbing either the rear wheels or a secondary rail fitted close the rear wheel lyres. The disadvantage is that the users hands and sleeves can get very dirty when the wheelchair is used outdoors.

Electrical powered wheelchairs that have a height adjustable mechanism are expensive, very heavy and the batteries require frequent recharging. Their large size and substantial weight make them very difficult to transport in an ordinary car.

This invention is a self-propelled wheelchair with a seat that the user can adjust in height from a low position, suitable for working at a desk, to a high position. The high position is such that the user is at the same eye level as a standing person. A gas strut is used to raise and lower the seat while the user is still seated. The wheelchair is foldable so it can be placed into a car boot for transportation. A propelling mechanism is provided so that the user can drive the wheelchair with the seat in any position. With this drive mechanism, the user does not directly contact the road wheels and so the user and his or her clothes remain clean.

A specific embodiment of the invention will now be described by way of an example with reference to the accompanying drawings in which Figure 1/8 shows in perspective the complete wheelchair assembly.

Figure 2/8 shows in perspective the wheelchair chassis assembly.

Figure 3/8 shows in perspective the chassis with the drive belt mechanism Figure 4/8 shows a side elevation of the wheelchair with the seat in its highest position Figure 5/8 show a side elevation of the wheelchair with the seat in its lowest position Figure 6/8 show in perspective a rear view of the seat frame, seat and gas strut.

Figure 7/8 show in perspective a front view of the seat, seat frame, main frame and armrest. Figure 8/8 shows a side elevation of the wheelchair in its folded position.

Referring to figure 1/8, the wheelchair comprises of a chassis frame 1 fitted with castors 3 and rear wheels 2, a main frame 5 in which a seat frame 6 can move, a seat 7, a had operated belt drive mechanism comprising of hand-wheel 8, drive belts 10 & 1 1 and front hinge frame 4 and rear link assemblies 19 that allow the wheelchair to be folded.

The chassis shown in figure 2/8 consists of a chassis frame I fitted with two castors 3 at the front and two rear wheels 2.

In figure 3/8 only the drive mechanism and chassis assembly are shown. The user propels the wheelchair by rotating two hand-wheels 8. The handwheel drives a hand-wheel drive belt I O. this drives an idler 9. The idler 9 then drives a rear wheel drive belt 11 that Drives a pulley fitted to the rear wheels 2. The drive mechanisms are independent of each other so that the wheelchair can be driven forward, backward or rotated.

Figure 4/8 shows a side elevation with the seat 7, shown in its highest position.

The hand-wheels are mounted on two arm rest assemblies 13, these maintain the distance between the hand-wheel centre and the main frame 5 pivot. The armrests ] 3 are also connected to the seat 7, via an arm rest link 18. As the seat height is adjusted, the arm rests 13 moves with the seat 7. The user can therefore operate the hand-wheels with the seat at any height.

Figure 5/8 shows a side elevation with the seat 7, shown in its lowest position.

This shows how the armrest 13 has rotated about the main frame 5 pivot and maintained the hand-wheel 8 within reach of the user.

Figure 6/8 shows the seat assembly. The seat 7 is hinged and connected to the seat frame 6. This allows the seat to be folded flat. A seat stay 12 holds the seat horizontally. The seat frame 6 is fitted with a series of rollers 16 that locate in the main frame.

These allow the seat frame to move vertically. A sprung loaded locking bolt 17 is used to retain the seat in any position. The user withdraws the locking bolt by pushing down the release arm 14. The release arm pulls the central cable of the release cable 25 Mat pulls the locking bolt back.

The locking bolts engage into a series of holes within the main frame S as shown in figure 7/8. With the locking bolt disengaged the seat is free to move up and down the main frame 5.

The gas strut I S shown in figure 6/8 provides a vertical force upwards on the seat frame and reacts against the base of the main frame. The gas strut is matched to suit the user weight.

For a 70Kg weight user a 65Kg gas strut is used. With the user sitting on the seat 7, if the locking bolt 17 is disengaged the seat will lower under the net down force of 5Kg. The user can raise the seat position by pushing down with 1 OKg on the release arms. lOKg of the users weight is then taken off the seat and transferred by the release arms to the main frame. The weight on the seat is now 60Kg and with a thrust up of 65Kg from the gas strut the seat will then rise. When the correct position is obtained the release arms are released and the locking bolts 17 engage into the nearest locking hole.

Figure 8/8 shows the wheelchair fully folded. The folding is accomplished by disengaging a locking mechanism (not shown). The main frame S then rotates along with the front hinge 4 and rear link assemblies 19 and folds flat. The seat then folds flat by hinging about the connection between the seat and seat frame.

The hand-wheels 8 and arm rest 13 also fold down by hinging about the main frame 5 pivot.

Claims

1 A wheelchair comprising of a wheeled chassis, a seat frame, a seat, a seat height adjustment mechanism, folding arms and hand operated belt drive mechanism. The chassis consists of a chassis frame fitted with two front castor wheels and two rear driving wheels. The seat slides within the seat frame and is fitted with a gas strut that provides an elevating force on the seat. The seat frame is connected to the chassis by arms that allow the frame to fold flat. The hand operated belt drive mechanism comprises of hand wheels connected to the chassis rear driving wheels via a belt drive. The hand wheels are connected to the seat and move with the seat.

2 A height adjustable wheelchair as claimed in claim 1 with the drive mechanism comprising a chain drive instead of a belt drive.

3 A height adjustable wheelchair as claimed in claim 1 with the drive mechanism comprising of a rigid drive shaft via gearboxes instead of a drive belt.

4 A height adjustable wheelchair as claimed in claim 1 with the drive mechanism comprising of a flexible drive coupling instead of a drive belt.

5 A height adjustable wheelchair as claimed in any proceeding claim with the height adjustment performed by a rack and pinion drive instead of a gas strut.

6 A height adjustable wheelchair as claimed in any proceeding claim with the height adjustment performed by a leadscrew instead of a gas strut.

7 A height adjustable wheelchair as clauned in any proceeding claim with the height adjustment performed by springs instead of a gas strut.

8 A height adjustable wheelchair substantially as described herein with reference to figures 1 -8.