Indoor/outdoor wheelchair frame

Abstract

C-shaped frames comprise the left and right sides of a wheelchair the main left and right wheels being rotatably mounted to the base portions of the frames and left and right castor wheels being mounted only to the left and right free ends of the lower arms of the frames so that the upper arms are cantilevered from the base above the lower arms. The seat and back structure of the chair is supported by the upper arms. As a consequence of the C-shaped configuration of the frames the castor wheels are independently resiliently supported for up and down movement relative to the seat resulting in a cushioned ride for a person sitting in the wheelchair when the chair is used out of doors over uneven terrain.

Description

This invention relates generally to wheelchairs and more particularly to the basic frame structure of a wheelchair designed to support the seat and back for both indoor and outdoor use.

BACKGROUND OF THE INVENTION

Conventional wheelchairs normally include left and right closed frame structures connected by diagonally extending crossed tubes arranged to scissor together if the chair is of the folding type. Generally, the left and right closed frames include extending back uprights for supporting the chair back and forward upright extending tubes supporting the front the seat, the rear and forward uprights being integrally connected between the horizontal upper and lower arms to form the closed left and right frame structures. Left and right large main wheels are rotatably mounted to the rear portion of the closed frames and left and right forward castor wheels are mounted at the lower front portions of these frames.

The foregoing construction works satisfactorily for wheelchairs when used indoors wherein floor areas are level and the chair itself is propelled at a relatively low speed. On the other hand, these types of chairs do not work satisfactorily outdoors wherein the terrain is often uneven. While some relative motion between the left and right closed frames themselves is permitted through coupling of the crossed diagonal tubes, this flexibility is limited and in the event the wheel-chair is used out of doors and over terrain wherein small gullies or mounds are traversed, one of the four wheels can actually lose contact with the ground. Moreover, riding the wheelchair over uneven terrain of this type is at best uncomfortable and at worst can be dangerous oftentimes resulting in toppling over of the wheelchair.

Known types of wheel suspension systems such as used in outdoor vehicles could, of course, be incorporated in a wheelchair. However, such suspension systems become expensive and complicated particularly with respect to proper support of the castor wheels themselves.

BRIEF DESCRIPTION OF THE PRESENT INVENTION

With the foregoing in mind, the present invention contemplates a novel frame configuration for a wheelchair which provides resilient suspension for the castor wheels of the chair in such a manner that it can be used both indoors and outdoors without the disadvantages presently inherent in known wheelchairs, all without requiring complicated and expensive suspension systems for the wheels.

More particularly, the wheelchair includes left and right generally C-shaped frames in spaced parallel, side-by-side relationship, the free ends of the upper and lower arms of the C-shaped frames extending forwardly. Left and right main wheels are rotatably mounted to the left and right rear base portions of the C-shaped frames respectively and these rear base portions are held in horizontally spaced relationship by an horizontal transversely extending rear member connecting the base portions together.

Left and right castor wheels in turn are rotatably mounted at the forward ends of the left and right lower arms of the C-shaped frames respectively and these forward portions of the frames are maintained in horizontally spaced relationship by an horizontal transversely extending forward cross member. The wheelchair seat and back are supported solely by the upper left and right arms of the frames such that the seat and back are effectively cantilevered from the rear base portions of the C-shaped frames.

With the foregoing arrangement, each castor wheel is substantially independently resiliently supported for up and down movement relative to the seat, the C-shaped configuration of the frames providing the ability of the forward portions of the lower arms to flex upwardly towards and downwardly away from the upper arms so that a cushioned ride for a person sitting in the seat results when the wheelchair is used outdoors over uneven terrain.

BRIEF DESCRIPTION OF THE DRAWINGS

A better understanding of this invention will be had by referring to the accompanying drawings in which:

FIG. 1 is a perspective view of the basic supporting frame structure of the wheelchair showing a seat and back frame in exploded relationship above the base frame;

FIG. 2 is a fragmentary cross section taken in the direction of the arrows 2--2 of FIG. 1 illustrating a detail of one of the frame members;

FIG. 3 is a cross section of a portion of a coupling means on the frame of FIG. 1 for coupling the seat and back frame structure to the base frame;

FIG. 4 is a cross section of the wheelchair in assembled relationship taken in the direction of the arrows 4--4 of FIG. 1; and,

FIG. 5 is a front elevational view of the wheelchair looking in the direction of the arrows 5--5 of FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to the central portion of FIG. 1 the indoor/outdoor wheelchair includes left and right generally C-shaped frames 10 and 11 in spaced parallel, side-by-side relationship the free ends of the upper and lower arms of the C-shaped frames extending forwardly. Thus, the C-shaped frame 10 includes an upper arm 12 and a lower arm 13 having their rear ends connecting together to form a rear base 14. Similarly, the right frame 11 includes an upper arm 15 and lower arm 16 connecting together at their rear to form a rear base portion 17.

As shown, left and right main wheels 18 and 19 are mounted respectively to the left and right rear base portions 14 and 17. An horizontal transversely extending rear member 20 connects the base portions 14 and 17 together. This rear member 20 not only holds the rear portions of the C-shaped frames in a constant horizontal spacing relative to each other, but also serves as a frame support for an electric drive motor and associated batteries in the event the wheelchair is to be of the powered type.

Left and right front castor wheels 21 and 22, in turn, are mounted at the forward ends of the left and right lower arms 13 and 16 as at 23 and 24. An horizontal transversely extending forward cross member 25 connects these forward portions 23 and 24 of the lower arms together. This cross member will maintain the horizontal spacing between the forward portions of the lower arms of the C frames constant.

From the foregoing description thus far, it will be evident that the left and right upper arms 12 and 15 of the C-shaped frames are essentially cantilevered from the base portions 14 and 17. Each of the C-shaped frame members may additionally include a shock absorber connected between the upper and lower arms such as indicated at 26 connecting between the arms 12 and 13 of the C-shaped frame 10 and at 27 connected between the upper and lower arms 15 and 16 of the C-shaped frame 11. In the preferred construction, and as indicated in the drawings, the C-shaped frames are each formed from an integral tube bent into a C-shape, the rear horizontal member 20 and the forward cross member 25 also comprising tubular structures.

Shown in exploded view above the C-shaped frames is a seat means designated generally by the arrow 28. This seat means includes a chair frame comprised of left and right horizontal tubular members 29 and 30 and forward cross tubular member 31 defining a seat area, the spacing between the horizontal members 29 and 30 being such that they will respectively overlie and be supported by the upper arms 12 and 15 of the C-shaped frame when the chair frame is assembled thereon.

As shown, the chair frame includes removable arm rests 32 and 33 and a back portion 34. Preferably, the chair frame is designed to be removably coupled to the upper arms of the C-shaped frame and towards this end, there are provided cooperating coupling means on the forward portion of the upper arms 12 and 15 of the C-shaped frames and the front of the chair frame.

In the particular embodiment illustrated, the cooperating coupling means on the C-shaped frames includes a transverse open-ended tube 35 mounted on the front portions of the upper arms 12 and 15. This transverse tube 35 incorporates first and second shorter tubes 36 and 37 received in the opposite open ends and biased apart at their inner central portions as by a spring 38. The forward end of the chair frame in turn includes first and second cylindrical receiving sockets 39 and 40 facing each other and dimensioned to receive the protruding ends of the shorter tubes 36 abd 37 so that the chair frame is effectively coupled to the C-shaped frames for swinging movement about a front transverse horizontal axis coinciding with the axis of the transverse tube 35.

It will be noted that the more rearward top surfaces of the upper arms 12 and 15 of the C-shaped frames include integrally formed cradles 41 and 42 for engagement with the underside of the horizontal tubes 29 and 30 of the chair frames when the same is positioned on top of the C-shaped frames. Preferably, the horizontal tubes 29 and 30 of the chair frame include downwardly extending spring type tabs 43 and 44 which snap over the sides of the upper arms 12 and 15 when the chair is assembled to hold the rear portion of the chair frame to the upper arms of the C-shaped frames.

With the foregoing arrangement, it will be evident that the chair frame may readily be removed from the C-shaped frames by simply first lifting the rear portion of the chair frame to swing it about the forward coupling tube 35, this action releasing the resilient tabs 43 and 44. The protruding ends of the shorter tubes 36 and 37 are then retracted from the cylindrical sockets 39 and 40 so that the entire chair frame can simply be then lifted away from the C-shaped frames. A desirable feature of the foregoing arrangement is the fact that the chair frame can readily be swung about the front coupling axis defined by the transverse tube 35 without actually removing the chair frame in order to expose for servicing equipment under the seat such as the electric motor power drive or batteries if such are used.

As described heretofore, each of the C-shaped frames preferably comprises a bent integral tubular member. It is desirable that the flexing or resilient movement of the castor wheels occur towards the rear base portions of the C-shaped frame and that the forward lower arm portions supporting the castor wheels be relatively rigid to provide adequate support. Thus in the embodiment described, each of the forward end portions of the lower arms of the C-shaped frames, such as 23 and 24, are reinforced.

Referring specifically to FIG. 2, this reinforcement takes the form of an inner tube 47 positioned within the end portion of the lower arm of the C-shaped frame adjacent to the mounting point of the castor. A similar internal reinforcing tube is provided for the other lower arm portion 24 associated with the castor 22 of FIG. 1. Essentially, these reinforcing means render the forward portions of the lower arms supporting the castors more rigid than the remaining portions so that the associated castor is firmly supported.

FIG. 3 illustrates in greater detail the cooperating coupling means secured to the front portions of the C frames. Thus, there is shown in FIG. 3 the transverse tube 35 with the first and second shorter tubes 36 and 37 received in the opposite ends thereof. In order to prevent the central spring 38 from biasing the shorter tubes 36 and 37 completely out the ends of the transverse tube 35, a stop means is provided to limit such telescoping movement. This stop means takes the form of slots 48 and 49 through which small knobs 50 and 51 respectively connected to the inner ends of the shorter tubes 36 and 37 extend. With this arrangement, the outward telescoping movement of the tubes 36 and 37 is limited by engagement of the respective knobs 50 and 51 with the right and left ends of the slots 48 and 49 respectively. On the other hand, the slots are of sufficient longitudinal extent that by manually moving the knobs 50 and 51 towards each other as indicated by the arrows, the protruding ends of the shorter tubes 36 and 37 will be retracted thereby releasing the cylindrical sockets 39 and 40 on the front of the chair frame as described in FIG. 1.

Referring now to FIGS. 4 and 5, the manner in which the improved frame arrangement of the present wheelchair provides for a cushioned ride when used out of doors will be evident. In FIGS. 4 and 5, corresponding components already described in FIG. 1 are designated by the same numerals.

Referring first to FIG. 4, the relative positions of the chair frame and the C-shaped frames when the chair frame is assembled will be evident. Thus, the horizontal tube 30 of the chair frame rests in the cradle 42 on the upper arm 15 of the C-shaped frame 11, the resilient tab 44 engaging about the upper arm 15 as shown. The forward cylindrical receiving socket on the chair frame is at substantially the same level as the cradle 42 so that the chair frame is held in substantially parallel relationship to the upper arms of the C-shaped frames.

When the wheelchair is used out of doors and is moving along uneven terrain such as might result from a hump in the ground as indicated by the dashed lines at 52, the C-shape configuration permits up and down movement of the castor wheels such as the wheel 22 engaging the hump relative to the upper arms of the C-shaped frame and seat to thus accommodate the hump and result in a cushioned ride for a patient in the chair. This action is indicated by the phantom linies for the castor wheel 22 as indicated at 22'. Thus, in travelling over a small curb or sill, both front castor wheels can move up and down in a resilient manner to provide a cushioning effect.

In addition to the foregoing, the mounting by the C-shaped frames is such that the forward castor wheels can move up and down independently of each other to a certain extent notwithstanding that there is provided the cross bar 25. Thus referring specifically to FIG. 5, should there be a hump of uneven terrain such as indicated at 53 which is engaged by only one of the castor wheels such as the castor wheel 22, this wheel can raise upwardly in a resilient manner independently of the other castor wheel 21 while the seat for the chair remains substantially level. The function of the cross member 25, of course, is to maintain substantially constant the horizontal spacing between the castor wheels but the presence of this member will not interfere appreciably with the independent up and down movement resulting from the C-shaped frame configuration. Proper damping of the resilient configuration can be controlled by the provision of the shock absorbers 26 and 27 so that there results an overall smooth and comfortable ride without requiring an unduly complicated suspension system for the wheels.

From the foregoing description, it will thus be evident that the present invention has provided a greatly improved wheelchair suitable for both indoor and outdoor use. While the particular frame structure described together with the cooperating removable seat is best adapted for use with a power operated wheelchair wherein the electric motor and batteries as described would be supported by the rear member 20, the basic principles of the C-shaped configuration could be used for manually operated wheelchairs to thus provide the versatility for a large number of types of wheelchairs for both indoor and outdoor use.

Claims

What is claimed is:

1. An indoor/outdoor wheelchair including in combination:

a. left and right generally C-shaped frames in spaced parallel, side-by-side relationship the free ends of the upper and lower arms of the C-shaped frames extending forwardly;

b. left and right main wheels rotatably mounted to the left and right rear base portions of the C-shaped frames respectively;

c. an horizontally transversely extending rear member connecting said base portions together;

d. left and right castor wheels rotatably mounted at the forward ends of the left and right lower arms of the C-shaped frames respectively;

e. an horizontally transversely extending forward cross member forward portions of said lower arms together;

f. a seat means including a chair frame defining seat and back areas supported by the upper left and right arms of said frames such that the seat means is effectively cantilevered from the rear base portions of the C-shaped frames; and

g. coupling means including a transverse open-ended tube mounted on the front portion of the upper arms of said C-shaped frames, first and second shorter tubes disposed in axial alignment within said transverse tube, spring means in the central portion of said transverse tube biasing the first and second shorter tubes apart so that their outer ends protrude from the open ends of said transverse tube, stop means limiting the outward extent of said shorter tubes, and first and second cylindrical receiving sockets at the forward end of said chair frame facing each other and dimensioned to receive the protruding ends of the first and second shorter tubes respectively so that said chair frame is coupled to the C-shaped frames for swinging movement about a transverse horizontal axis whereby said chair frame may be completely decoupled from the C-shape frames by retracting said shorter tubes against the bias of said spring means to release said receiving sockets, and whereby a horizontal spacing between the front castor wheels is substantially maintained by said forward cross member while each castor wheel is substantially independently resiliently supported for up and down movement relative to said seat means as a consequence of the C-shaped configuration of the frames providing the ability of the forward portions of the lower arms to flex upwardly towards and downwardly away from the upper arms so that a cushioned ride for a person sitting in said seat means results when the wheelchair is used outdoors over uneven terrain.

2. The subject matter of claim 1, in which each of said left and right C-shaped frames comprises an integral tube bent into the C-shape, the lower forward end portion of the tube incorporating a reinforcing means to render it more rigid than the remaining portion so that the associated castor is firmly supported.

3. The subject matter of claim 1, in which said seat means includes a chair frame defining seat and back areas; and cooperating coupling means at the forward end of the chair frame seat area and the forward ends of said upper arms of the C-shaped frame for coupling the chair frame to the C-shaped frames.

4. The subject matter of claim 1, in which each C-shaped frame includes a shock absorber connected between its upper and lower arms.