Wheelchair and one-piece molded braking support wheel therefor

A molded braking and support wheel assembly for a multi-wheeled wheelchair for a handicapped person. The wheel assembly includes a braking support wheel molded as a single unit of plastic or plastic-like material having concentric components including a tire receiving rim, a wheel bearing and brake assembly receiving hub, and spaced wheel spokes substantially radially extending between the hub and rim. A ring or band-shaped metal brake drum is also molded as a unit into the hub, the brake drum having a generally cylindrical inner braking friction surface and plastic-interlocking outer surface features which permanently interlock with the plastic material when the braking support wheel is mold formed. The plastic-interlocking outer features are molded with the hub into a single unit with the support wheel to secure the brake drum from relative movement in the hub. The brake drum defines a generally cylindrical cavity for operatively receiving the brake assembly. The hub includes a wheel bearing cavity coaxial with said brake drum for receiving spaced wheel bearings positioned therein.

Not applicable

Not applicable

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates generally to wheelchairs for the handicapped, and more particularly to a one-piece molded wheel support wheel formed as a unit for supporting and braking the wheelchair.

2. Description of Related Art

Manually propelled wheelchairs having two smaller castered front wheels and two larger rear wheels are well known. These assistive devices are utilized by users which are physically impaired individuals unable to walk or who find walking difficult and are typically propelled by the user. Such wheelchairs require periodic immobilization and stabilization thereof as determined by the user or attendant and are therefore equipped with a hand-actuated brake assembly (typically one per each braking support wheel) attached to a frame member of the wheelchair frame assembly adjacent the wheelchair seat allowing the user or attendant to selectively move a hand operated lever of the brake assembly to engage or disengage a friction braking member in the form of a bar or plate which presses against the outer periphery of each corresponding tire of the braking support wheels of the wheelchair.

However, due to wheel wear, moisture, dirt, oil and other wheel periphery surface modifying debris or contaminants, the limited pressure exerted by the friction member thereagainst will vary greatly and thus correspondingly affect the degree of braking friction for immobilization of the wheelchair. Should the frictional force between the outer periphery of the rear wheel and the friction member be compromised and reduced, unexpected movement of the wheelchair may be experienced.

A more efficient brake mechanism has been incorporated into battery powered motorized three-wheeled scooters which provide motorized personal transportation for a seated user. These motorized scooters typically include spaced apart coaxially mounted rear wheels, one or both of which serve as a driving wheel connected to the battery powered motor mounted on the scooter carriage and a steerable front wheel which includes a wheel housing supporting a single front wheel and a brake mechanism having a tightenable brake band and drum arrangement. However the steerable front wheel of such power scooters is typically supported between spaced downwardly extending ears or plates of the wheel housing such that the entire wheel and brake mechanism are held on an elongated mounting shaft connected between the lower ears of the wheel housing itself.

The present invention replaces the conventional support wheel and corresponding wheel perimeter brake engaging members with a one-piece molded braking and support wheel which includes a molded-in brake drum wheel operably receiving a brake assembly. Substantially greater consistent braking and immobilization are achieved by providing a brake and support wheel mold formed more efficiently as a unit of wheelchairs and which is substantially less impervious to conditions of tire wear, moisture, dirt, oil and other debris which would typically collect on the outer perimeter surface of the wheel tire.

BRIEF SUMMARY OF THE INVENTION

This invention is directed to a molded braking and support wheel assembly for a multi-wheeled wheelchair for a handicapped person. The wheel assembly includes a braking support wheel molded as a single unit of plastic or plastic-like material and having a tire receiving rim, a wheel bearing and brake assembly receiving hub, and spaced wheel spokes substantially radially extending between the hub and rim. A ring-shaped metal brake drum is molded as a unit into the hub, the brake drum having a plastic-interlocking outer surface and a generally cylindrical inner braking friction surface. The plastic-interlocking outer surface is molded into said hub as a single unit with the support wheel to secure the brake drum from relative movement in the hub. The brake drum defines a generally cylindrical cavity for operatively receiving a brake assembly, the hub including a wheel bearing cavity coaxial with said brake drum for receiving a wheel bearing positioned therein.

It is therefore an object of this invention to provide a wheelchair for an ambulatory-impaired user which includes a substantially more reliable brake mechanism for selective immobilization of the wheelchair.

Still another object of this invention is to provide an improved wheel brake mechanism for wheelchairs which is uniquely incorporated into a new one-piece molded brake and support wheel having a molded-in rigid metal brake drum which is ready to receive the brake assembly.

Yet another object of this invention is to reduce the amount of rear wheel tire tread wear caused by current brake lever engagement thereagainst to brake a wheelchair.

Still another object of this invention is to provided more consistent braking function of the brake assemblies of a wheelchair along with substantially less brake wear and significantly less adjustment thereof.

In accordance with these and other objects which will become apparent hereinafter, the instant invention will now be described with reference to the accompanying drawings.

LIST OF COMPONENTS

12—braking support wheel assembly

14—braking support wheel

24—brake shoe support aperture

32—brake support plate

36—brake shoe actuator surface

38—brake shoe support shaft

40—motion transfer arm

56—adjuster support flange

60—wheelchair frame assembly

64—upright frame member

66—lower frame member

72—brake support shaft

90—brake drum support hub

92—wheel spoke web

100—main support tube

102—main support shaft bore

106—outer tool access cavity

116—inner wheel bearing cavity

118—outer wheel bearing cavity

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings, a partially exploded view of one embodiment of a wheelchair of the present shown generally at numeral10inFIG. 1. This embodiment10includes a larger rear braking and support wheel assembly shown generally at numeral12forming the larger-in-diameter spaced rear wheels14of this wheelchair assembly10and conventional front casters62supporting the front portion of the frame assembly60. The frame assembly60includes spaced upright frame members64and spaced horizontal frame members66as shown.

The hub16of each molded one-piece braking support wheel14operably receives a brake assembly30which, for the purpose of clarity, is shown installed into the brake drum18, the brake drum18being permanently molded into the hub16as a unit with the braking support wheel14as will be described herebelow. A brake actuator assembly68is clampingly engaged onto the spaced horizontal frame members66in a conventional manner. A flexible brake cable70interconnects the brake actuator assembly68and the brake mechanism30as will be described more fully herebelow. The molded braking support wheel14includes an outer tire-receiving rim28which supportively receives a tire T in a conventional manner.

Referring now toFIG. 2, an alternate embodiment of the wheelchair frame assembly60′ is there shown at10′. The wheelchair frame assembly60′ includes spaced horizontal frame members66′ upright frame members64′ having rearwardly, upwardly extending portions thereof which receive hand grips48and brake actuator levers50. The brake actuator levers50are operably connected by flexible brake cable70′ to the brake assembly30. Each smaller braking support wheel assembly12′ includes a smaller-in-diameter braking support wheel14′ supporting a tire T′ of a generally smaller diameter than that shown inFIG. 1. The hub configuration16′ includes a molded-in brake drum18supporting the brake assembly30as previously described.

InFIG. 3, details of the brake actuator assembly68include an elongated brake support shaft and clamp74which serves to clampingly engage the brake actuator assembly68to the upper horizontal seat frame member66shown inFIG. 1. Brake links76and78pivotally connected together as shown respond to pivotal movement of the brake handle80in the direction of the arrows to actuate the brake cable70.

InFIGS. 4 and 5, the opposite end of cable70is attached to an adjuster support flange56of the support arm44of a brake support plate32of the brake assembly30. A threaded adjuster46receives the end of the outer sleeve of the brake cable70, while the core wire58extends to be clampingly engaged by a core wire clamp82to adjacent the distal end of a pivotally movable motion transfer arm40. The brake assembly30further includes a debris flange54mounted against the inner surface of the brake support plate32. The opposing brake friction shoes34are mounted against the debris flange54in pivotal position about a brake shoe support shaft38through a common aligned pivotal aperture24in a proximal opposingly positioned end of each brake friction shoe34.

The motion transfer arm40is operably engaged with a brake cam42which rotates consonant with pivotal movement of the motion transfer arm40as effected by in and out movement of the core wire58in the direction of the arrow. This brake cam42includes opposing flats which are held biasingly by a wire spring (not shown) against brake shoe actuator surfaces36of the opposing spaced ends of each of the brake friction shoes34. Thus, as the brake cam42is rotated, the brake shoes34are pivotally spread apart to act against the inner cylindrical drum friction surface20of the brake drum18. Referring additionally toFIG. 6, a hexagonal brake plate anti-rotation aperture52is operably engaged with a mating surface of either an upright frame member64or a hexagonal surface formed onto a wheel mounting shaft (not shown) to resist the rotational torque exerted against the brake support plate32during braking operation.

Referring now toFIGS. 7,8and9, a most important aspect of the invention is there shown. InFIGS. 7 and 8, the injection-molded plastic or plastic-like braking support wheel14″ is formed as a unit of injection-molded plastic or plastic-like materials. This braking support wheel14″, as does the braking support wheels14and14′ which is identical except with respect to outside diameter of the rim28,28′ and28″, includes radially extending evenly spaced wheel spokes84which tie the hub16″ and rim28″ together structurally. Lightening wheel spoke webs92form lightening apertures shown to both enhance strength while maintaining a low total weight of the braking support wheel14″.

Molded into and as a part of the hub16″ is the rigid metal brake drum or band18formed typically of steel for strength and wear resistance. However, other metallic materials are equally suitable for this purpose. The brake drum18includes annular grooved plastic-interlocking outer surface22of sufficient width so that the plastic material fully engages into this grooved outer surface22during the mold-forming of the braking support wheel14″. This grooved outer surface22insures that there is no movement between the brake drum18and the hub16″ during operation of the wheelchair, including the braking thereof as previously described.

The hub16″ includes concentrically and coaxially formed inner and outer wheel bearing cavities116and118which, as seen inFIG. 9, forcibly receive the inner and outer wheel bearings96and98, respectively. These wheel bearings96and98are press fit and held spaced apart for added strength by an inwardly extending molded bearing spacer88forming the bearing gap86. The hub16″ also includes an assembly clearance or access cavity106so that a conventional socket wrench may be utilized to install and remove the wheel support shaft S by its head H (shown inFIG. 10in phantom).

To add strength to the hub16″, hub ribs26are provided which are evenly spaced and radially extending and which substantially stiffen the entire hub16″ while maintaining a minimum weight of molded plastic material to accomplish the necessary task of supporting the inner and outer wheel bearings96and98and brake drum18as previously described.

Referring particularly toFIG. 9, details of the brake mechanism30are there shown in section view positioned within the brake drum18with the brake friction shoes34bearing against the drum friction surface20to effect braking as previously described. An elongated main support tube100having an elongated longitudinal main support shaft bore102is positioned centrally within the brake assembly30with an enlarged end portion104forming a brake plate spacer between the inner bearing96against end surface120and support tube shoulder108against the brake support plate32. With the wheel mounting shaft S slidably engaged through the inner bores of bearings86and86and the main support shaft bore102, securement of this arrangement into a suitable aperture or receiver formed through the upright frame member64(shown in phantom), of frame assembly60is effected.

Still referring toFIG. 9, an alternate means for preventing rotation of the brake support plate32′ is in the form of anti-rotation tabs112and114formed integrally with the brake support plate32′. These tabs112and114are angled and spaced apart so as to engage against the outer surface of the upright frame member64as shown. Preferably, two spaced upper and lower anti-rotation tab sets112and114are provided so that a set of four such tabs, two on either side of frame member64, provide positive anti-rotation alignment of the brake support plate32and the entire brake assembly30.

Referring lastly toFIG. 10, an alternate embodiment of the brake drum18′ is there shown. Molded into the hub16′ of the braking support wheel (not shown for simplicity) during the plastic injection mold forming thereof. This brake drum18′ includes the cylindrical drum friction surface20′ which operably engages against the outer surfaces of the brake friction shoes34as previously described. However, the outer surface of the brake drum18′ includes spaced apart transverse hub engaging grooves94which are better suited for resisting the torsional forces generated during braking operation of the wheelchair assembly. In this hub embodiment16″, the bearing gap86and brake drum support hub90are similar to those previously described inFIGS. 7,8and10.

While the instant invention has been shown and described herein in what are conceived to be the most practical and preferred embodiments, it is recognized that departures may be made therefrom within the scope of the invention, which is therefore not to be limited to the details disclosed herein, but is to be afforded the full scope of the claims so s to embrace any and all equivalent apparatus and articles.