Land vehicles – Wheeled – Extensible
Reexamination Certificate
1999-06-07
2001-01-16
Johnson, Brian L. (Department: 3618)
Land vehicles
Wheeled
Extensible
C280S253000, C280S242100, C280S246000, C280S639000
Reexamination Certificate
active
06173986
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to the fields of equipment for aiding the disabled and to medical equipment. More specifically the present invention relates to a wheel chair having a lever arm propulsion mechanism and a collapsible frame with spaced apart first and second wheels, the wheels being affixed to first and second wheel half-axles. The propulsion mechanism includes first and second clutches secured to corresponding first and second wheel half-axles. Each clutch has an outer clutch drum which engages and rotates an internal clutch core affixed to the given half-axle when rotated in one direction and disengages the core and spins freely about the core when rotated in the opposing direction. A lever arm is pivotally mounted to the frame and is affixed to a lever arm axle fitted to a drive cable pulley, and a drive chain or cable is engagingly wrapped around the drive cable pulley and engagingly wrapped twice around the first clutch drum. The cable extends from the first clutch drum engagingly around a reversing pulley rotatably mounted on a pulley stem secured to the frame, and from the reversing pulley is engagingly wrapped twice around the second clutch drum in the opposite direction from its winding around the first clutch drum, and then returns to the drive cable pulley to form a closed cable loop.
Rotation of the first and second clutch drums about the wheel half-axle in opposing rotational directions causes the first clutch to drive the wheel axle in a forward rotational direction while second clutch does not engage, and rotation of the first and second clutch drums about the wheel axle in reversed opposing rotational directions causes the second clutch to drive the wheel axle in a forward rotational direction while the first clutch does not engage. As a result of this construction, pivoting the lever arm in a forward direction rotates the first clutch drum in a first rotation direction and thereby drives the wheel half-axle and wheel forwardly, and pivoting the lever arm in the opposite, second rotational direction continues to drive the wheel half-axle and wheel forwardly. Thus no movement of the lever arm is wasted, and maximum efficiency is achieved because all movement of the lever arm causes forward wheel half-axle and wheel rotation.
2. Description of the Prior Art
There have long been wheel chairs for mobilizing the injured and disabled, either under the power of an assistant pushing the chair or under the power of the chair occupant or user. In the latter instance, prior art wheel chairs have been highly inefficient because the user typically has to grip an outer ring on the side of a chair wheel and rotate the wheel a few degrees, slide the hand back and rotate it a few more degrees. This is inefficient because half of the hand movement, that is, sliding the hand back to begin rolling the wheel again, delivers no propelling drive to the wheel. Another problem is that the arm and chest muscles must be exerted while the arms are in an awkward position, causing soreness and fatigue. Still another problem has been that the chairs collapse inefficiently and have two forward caster wheels, making turning a high friction-resistance exercise.
It is thus an object of the present invention to provide a wheel chair which can be powered by hand with the arms in a comfortable and maximized muscle power delivery position.
It is another object of the present invention to provide such a wheel chair which delivers muscle power to the wheels throughout the entire arm motion cycle, so that speed and efficiency are maximized.
It is still another object of the present invention to provide such a wheel chair which folds compactly and efficiently, and which has only one, central forward caster wheel, so that turning friction from rotating the caster wheel axle structure is minimized.
It is finally an object of the present invention to provide such a wheel chair which is relatively inexpensive to manufacture and is sturdy and reliable.
SUMMARY OF THE INVENTION
The present invention accomplishes the above-stated objectives, as well as others, as may be determined by a fair reading and interpretation of the entire specification.
A wheel chair is provided, including a wheel chair frame including a seat portion, an axle structure and two lateral wheels mounted to the axle structure for rolling the wheel chair over a support surface; and a manual propulsion mechanism including first and second clutches mounted to the wheel axle structure, each of the clutches having an outer clutch drum which engages and rotates an internal clutch core affixed to the wheel axle structure when rotated in one direction and disengages the clutch core and spins freely when rotated in the opposing direction; a lever arm affixed to a lever arm axle rotatably fitted through the frame to a drive cable pulley; a drive cable engagingly wrapped around the drive cable pulley and engagingly around the first clutch drum, and extending from the first clutch drum engagingly around a reversing pulley rotatably mounted on a pulley stem secured to the frame, and from the reversing pulley engagingly around the second clutch drum wound in the opposite direction from its winding around the first clutch drum, and then returning to the drive cable pulley to form a continuous cable loop; so that pivoting the lever arm in one direction rotates the first and second clutch drum about the wheel axle structure in opposing first rotational directions so that the first clutch drives the wheel axle structure in a forward rotational direction while second clutch does not engage, and pivoting the lever arm in the opposite rotational direction to rotate the first and second the clutch drums about the wheel axle in second opposing rotational directions causing the second clutch to drive the wheel axle structure in a forward rotational direction while the first clutch does not engage.
The wheel chair preferably additionally includes a tensioning pulley biased against the cable with a pulley biasing mechanism. The wheel chair preferably still additionally includes a turnbuckle in the cable for adjusting cable tension.
The wheel chair frame is preferably collapsible and includes two spaced apart wheels, each wheel being affixed to a wheel half-axle; a seat made up of two U-shaped lateral seat support bars, each pivotally secured at its rearmost end to a corresponding upright lateral backrest support bars, so that one of the wheel half-axles fits through a passageway extending through the frame at the intersection of the seat support bars and the backrest support bars on each side of the chair; a flexible seat fabric sheet extending between the lateral seat support bars; a flexible backrest fabric sheet extending between the lateral backrest support bars; a first rear strut pivotally connected to each of the backrest support bars and extending toward the center of the frame, where each of the rear pivot struts is pivotally connected to a rearward interconnection bracket; where the two wheel half-axles are each pivotally connected at their inward ends to the rear interconnection bracket; a forward interconnection bracket; a second pivot strut pivotally connected to each of the seat support bars and to a forward interconnection bracket; so that the lateral seat and backrest support bars are pivotable on the pivot struts to fold toward each other to bring the chair into a compact storage configuration and to fold back away from each other to bring the chair into a operational configuration, while the flexible seat and backrest fabric sheets collapse and unfold with the folding and unfolding, respectively, of the chair; and a forward wheel and forward wheel support mechanism.
The wheel chair preferably additionally includes a generally L-shaped arm rest bar pivotally connected at one end to the corresponding seat support bar and at the other end to the corresponding backrest support bar, and an elongate arm platform connected to the upper surface of the arm rest bar; the arm rest b
Johnson Brian L.
Oltman Flynn & Kubler
Winner Tony
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