GB2479178A

GB2479178A - Auxiliary frame detachably mounted to a wheelchair backrest to provide anchorage points for occupant and vehicle restraints

Info

Publication number: GB2479178A
Application number: GB201005441A
Authority: GB
Inventors: Daniel Steedman
Original assignee: Individual
Current assignee: Individual
Priority date: 2010-03-31
Filing date: 2010-03-31
Publication date: 2011-10-05
Also published as: GB201005441D0

Abstract

An auxiliary frame is provided that can be detachably mounted to the backrest frame 43 of a wheelchair to reinforce the wheelchair structure and provide anchorage points for both vehicle mounted tie-down restraints and occupant straps that are used to secure an occupant within the wheelchair when the wheelchair is mounted within a vehicle. The detachable frame has an upper section that provides anchorage points for the buckles 40 an occupant restraint harness and also anchorage points for a first set of rear wheelchair restraint straps 35,36 which are looped around the frame. A lower section of the frame provides further anchorage points 45 for upper body harness and a lap belt, as well as anchorage points [63, Fig. 6] for hooks 33,34 of a second set of wheelchair restraint straps 31,32. The upper part of the frame is coupled to the wheelchair frame 43 by channels [56, Fig. 6] mounted on the end of telescopic frame sections [54,55, Fig. 6]. The lower part of the frame has clamps [66, Fig. 6] or slots [65, Fig. 6] to allow fitting to the lower part of the wheelchair. The upper and lower parts of the frame are coupled to one another in a telescopic manner to allow height adjustment. Further tie-down straps 47 may be used to tether the front of the wheelchair. The frame prevents collapse of the wheelchair frame in the event of a vehicle collision.

Description

Improvements in Wheelchairs

Description

Introduction.

The invention related to the transportation of a wheelchair while occupied by the user. There are established principles involved in transportation of wheelchairs which are effectively embodied in the International Standard ISO 10542 This Standard relates to the testing of wheelchairs in a crash scenario, using separate Wheelchair Restraints arid Occupant Restraints. The invention provides an alternative method for use where these established principles cannot be applied, while resistant to the same level of forces applied in the ISO 10542 test.

Outlining the Established Principles.

A simplified illustration of the principles embodied in 15010542 is shown in Fig 1. The Wheelchair is secured to the vehicle floor using webbing based restraints fitted to standard floor tracking systems (6&7). The Tie down points on the wheelchair (5) are designated by the wheelchair manufacturer based on the testing they have carried out based on ISO 7176 part 19, which is identical in principle to the ISO 10542 test. The Occupant Restraint has a Lap Belt (3) and a Shoulder Belt (2). The Lower end of the shoulder belt and both ends of the lap belt are secured either to the Wheelchair Restraint (4) or to an independent track mounted anchorage. The upper end of the Shoulder Belt is secured to the Vehicle Wall (1) to produce a similar effect to the shoulder element of a car seat belt for a passenger in a car seat. The critical points for the occupant are points (1) and (6). Fig 3 shows us how the forces are loaded onto the restraint system when the 20G forward force is applied. The positioning of the lap belt is (Improvements in Wheelchairs Page 2) critical to prevent the occupant from sliding out underneath it. The force exerted by the Occupant in the 20G impact is suspended between points 1 (or 15) and point 6 (or 19). The front Wheelchair Restraint (7) prevents the front of the wheelchair from lifting up after the impact.

Current Situations where the Established Principles cannot be applied.

For the Established Principles to be effective the vehicle has to be fitted with a means of anchoring the Shoulder part of the Occupant Restraint. It is well known in the Wheelchair Industry that many of the larger community vehicles do not have this provision, and it these situations the wheelchair is transported with the Shoulder part of the Occupant Restraint passing over the occupant's shoulder and returning to the floor as shown in Fig 2. This method has the following flaws: 1) On smaller people, and particularly children, the shoulder strap does not grip on the shoulder -mainly due to the fact that the webbing width is often wider then their shoulder. This slips down, and therefore offers no protection in an impact.

2) Some wheelchairs have extended backrests, and postural buggies have continuous loop handles, both denying the access required for the Shoulder Part of the Occupant Restraint to be applied.

3) Even where Shoulder Anchorage is available, the Shoulder part of the Occupant Restraint sometimes passes across the occupant's face.

Improvements in Wheelchairs When in use this system appears to have the same benefits as the methods used in the Established Principles. Point 13 corresponds with Point 6, Figi, and so on as compared. The Fundamental difference is where the Shoulder Strap (8) returns to the Vehicle Floor.

To appreciate how this affects the wheelchair and then, ultimately, the occupant, we have to consider the forces illustrated in Fig 4. The main force (20) is a 20G force in the ISO 10542 test, and is in the forward direction. The resisting forces (22,23,23) are transposed into a radial force (21) with point (25) as its centre. Now we look at Fig 5 to see that this force (26) causes the backrest of the wheelchair to fail, and in practice it also causes the main frame of the wheelchair to collapse. The occupant then has no protection and will sustain severe injuries, maybe leaving the wheelchair altogether becoming a danger to other passengers in the vehicle.

This system has been tested to the ISO 10542 level of testing, but used a surrogate wheelchair which is designed not to fail on impact in order to ensure that the restraints are being tested fairly. The Surrogate Wheelchair has a backrest construction that would be resistant to the forces applied -but it weighs 85 kg, and is very difficult to push around. Testing of this Restraint arrangement with Standard Wheelchairs, where the Shoulder part of the Occupant Restraint returns to the floor, have demonstrated the failure of the wheelchair. It is accepted that this system is not a safe system for travelling, but the method continues until an alternative becomes available.

The other area where the Established Principles are not able to be applied is the use of Specialist Postural Seating in Wheelchairs, in particular Bespoke Moulded Seats. These seating methods tend to provide a cocoon for the occupant to accommodate skeletal deformities, with the moulded profile fitting around the side of the occupant, preventing the usual Lap Belt path over the pelvis of the occupant.

Summary of the Invention

When considering the need to create a Restraint Method that is completely floor mounted by means of the use of Webbing Restraints, it is clear that the critical area of concern is the structure of the wheelchair. We are stating that every wheelchair to use this device should have been tested in accordance with ISO 7176 part 19 (Wheelchair Crash Test) and as such will be proven to have frame integrity in the lower section of the structure as indicated in Fig 8. This illustration shows the proven area of the wheelchair structure (69) secured to the floor using proven means and to proven attachment points (67&68). The backrest is shown as having no support, which is the real situation for a webbing based floor mounted restraint system as we have seen earlier.

The Invention of the Wheelchair Occupant Restraint Frame provides the support to the structure of the wheelchair and integrates the known strong points of the wheelchair to enable the application of a floor mounted webbing restraint system without risk of collapse to the wheelchair structure. This system removes the need for additional structures either permanently or temporarily installed into a vehicle, allowing a simple embarking procedure for the wheelchair into the vehicle.

Improvements in Wheelchairs To understand how the Wheelchair Occupant Restraint Frame provides the relevant support to the wheelchair backrest, we refer to Fig 9. We have seen in Fig 4 how the forces are transferred to a rotational force with the centre of rotation at the rear floor mounting point. Fig 5 showed how this affects the structure of the backrest. In Fig 9 we are showing that it is possible to create a triangle of strength. For a triangular structure to work, each side needs to be maintained in a straight line. The tensile force acting on the Upper Tether Strap (70) will maintain this side of the triangle in a straight line.

Likewise, the tensile forces (71) on the Rear Wheelchair Restraint will maintain this second side of the triangle. It remains then for the Wheelchair Occupant Restraint frame to maintain the third side of the triangle, which is subject to the force from above (73) as a result of the forward movement which is resisted at the base of the backrest by the structure of the wheelchair base (72), causing a substantial compression force on the Wheelchair Occupant Restraint Frame. The Wheelchair Occupant Restraint Frame is designed to withstand this compression force, thus maintaining the integrity of the structure of the wheelchair.

Application of the invention Having established the principles whereby the invention fulfils its function, we now look at how it actually fits to the wheelchair (which may be any wheelchair that has been crash tested to 1507177 part 19): The Occupant Restraint Frame (Figure 6) is attached to the backrest frame of a wheelchair as shown in Fig 7. Drawings Fig 6 and Fig 7 should be viewed together to ensure the details are clear. The channels (Fig 6: 56&57) on the Upper Telescopic Sections (Fig 6: 54&55) are fitted around the wheelchair backrest tubular framework (Fig 7: 43) and secured in place to the Upper Frame (Fig 7: 48) by the securing screws (Fig 6: 51&52). This attachment secures the backrest to the Occupant Restraint Frame at the top of the wheelchair. The Lower Telescopic sections are secured to the base of the wheelchair backrest at the point where the wheelchair tiedowns are applied. The attachment (Fig 7: 44) either uses the channel clamp (Fig 6: 66) to secure on the tubular seat frame or is bolted to the wheelchair frame through the slots (Fig 6: 65). The method of attachment selected relates to the Wheelchair Manufacturer's recommendations for the rear tie down point. On some wheelchairs the Rear Wheelchair Restraints are fitted around the tubular framework, in which case the clamp method is used. Other wheelchairs have a bracket bolted onto the framework, in which case the bracket can be removed and the bolt fitted through the slots (Fig 6: 65). The Telescopic sections (Fig 6: 61&62) are then secured to the lower frame (Fig 6: 58) by means of securing screws (Fig 6: 59,60). This ensures a compact fitting to the wheelchair frame. To accommodate the varying heights of wheelchairs, the Upper Frame (Fig 6: 48) and Lower Frame (Fig 6: 58) can be extended apart telescopically and the position secured by securing screws on the Upper Frame (Fig 6: 49&50). A headrest (Fig 7: 42) is fitted to the Headrest Attachment point (Fig 6: 53) and secured with securing screws. The headrest protects the Occupant of the wheelchair from Whiplash injuries in the event of a rear impact in the vehicle. The Occupant Restraint Frame can then be used to secure the wheelchair and Occupant into a vehicle.

Improvements in Wheelchairs The Occupant is secured to the wheelchair frame using an upper body harness secured at each shoulder (Fig 7: 40) with a buckle which is secured to the Occupant Restraint Frame (Fig 7: 39). The lower section of the Upper Body Harness and the Lap Belt are secured to the Occupant Restraint Frame Slot (Fig 7: 45) on either side of the wheelchair. The Rear Wheelchair Restraints (Fig 7: 31&32) attach to the Occupant Restraint Frame through the aperture in the Lower bracket (Fig 7: 63) using hooks (Fig 7: 33&34) or similar attachment. A Pair of Front Wheelchair Tie Downs (Fig 7: 47) are attached -one either side of the wheelchair -at the Wheelchair Manufacturer's recommended attachment point for the wheelchair (Fig 7: 46). The Upper Section of the Occupant Restraint is secured to the floor by means of Tethers (Fig 7: 35&36) which are secured to the Rear Wheelchair Restraint Housings (Fig 7: 29&30) by buckles or similar attachments or, alternatively, secured independently to the vehicle floor. Each Tether Strap is passed around the Upper Frame and secured back to itself using a tongue and buckle conection (Fig 7: 37&38). The Tethers are tensioned by hand to ensure that they are taking the load as soon as it is applied.

Summary of Drawings:

Fig 1: Illustration of the elements of the recognised Wheelchair Securing Method in accordance with ISO 10542.

Fig 2: Illustration of the alternative method used when there is no Shoulder Anchorage point available.

Fig 3: Illustration of the Forces applied in a simulated Crash Scenario when using the recognised Wheelchair Securing Method in accordance with ISO 10542.

Fig 4: Illustration of the Forces applied where the Shoulder Anchorage point is not present.

Fig 5: Illustration of the results of the Forces applied in Fig 4 when a standard wheelchair is tested.

Fig 6: Illustration of the Invention -Occupant Restraint Frame Fig 7: Illustration of the Invention fitted to a Wheelchair, with Wheelchair Restraints Fitted.

Fig 8: Illustration showing the base of the wheelchair which has been proved to withstand the forces involved in the 15010542 test.

Fig 9: Illustration of how the Invention resists the forces acting on the backrest and preventing frame failure.