Land vehicles – Wheeled – Occupant propelled type
Reexamination Certificate
1998-10-15
2001-06-19
Mar, Michael (Department: 3619)
Land vehicles
Wheeled
Occupant propelled type
C280S244000, C280S250100, C074S523000, C074S528000, C074S545000, C192S111400
Reexamination Certificate
active
06247715
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a lever-operated wheelchair, which can be moved forward or maneuvered as one pleases by simply operating a lever or levers. More specifically, this invention relates to a wheelchair that is moved forward by the power generated by a reciprocating movement of an operation lever, and backward by the operation of push rims.
2. Prior Art
Most of the conventional hand-operated wheelchairs are operated with push rims, i.e., operation rings that are attached to the rims of the wheels. In order to make it possible to operate a wheelchair with one hand, the applicant of this invention proposed a lever-operated wheelchair for one-hand operation in the Japanese Patent Application No. 190091/1981 (Japanese Patent Publication No. 58808/1985). This wheelchair has an operation lever, which can be pushed forward or pulled backward from the neutral position to rotate the wheels forward or backward correspondingly. This wheelchair was granted a patent (Pat. No. 1330760) and has been widely used for one-hand operation applications. While this wheelchair moves forward when the operation lever is pushed forward, another type of wheelchair employing a pulling motion, which is thought to produce stronger power than a pushing motion, for the forward movement was proposed in the Japanese Patent Application No. 274210/1994 (Japanese Patent Laid-Open No. 103465/1996). This latter wheelchair is designed to use both hands. Apart from wheelchairs, a tricycle that is driven forward when a linearly reciprocal lever is pushed or pulled was published on pp. 78-79 of the Feb. 17, 1997, issue of the Nikkei Mechanical Magazine.
The two types of lever-operated wheelchairs for one-hand operation cited above are moved forward only when the lever is pushed (in the case of the former wheelchair) or only when the lever is pulled (in the case of the latter wheelchair). The tricycle, on the other hand, has a mechanism that uses both a push and a pull of the lever to move the tricycle forward, but this mechanism, comprising two roller clutches and five bearing gears, is very complicated and bulky, and is therefore difficult to be used in a wheelchair.
SUMMARY OF THE INVENTION
The present invention has been conceived in the light of the above points, with the object of providing a wheelchair having a simple and compact driving mechanism that is easily built into the wheelchair because it can be fitted between the wheel and the frame, and that efficiently moves the wheelchair forward by using both the push and the pull of the operation lever, while the push rim is continued to be used for the less frequent backward movement of the wheelchair.
In order to achieve the above object, the present invention presents a lever-operated wheelchair that is moved forward by operating a lever in a reciprocating motion and has a push rim on a wheel, comprising an operation lever rockably supported on a main pivot on each of the left and right sides of a frame, wherein each operating lever is provided with a pair of one-way-clutch-driving links in such a way that one ends of these links are linked to the operation lever via mutually spaced apart sub pivots at a certain distance forward from the main pivot, while the other ends of the links are linked to a pair of forward and backward arms, which are established on opposite sides of a hub spindle of a one-way clutch. These elements are configured in such a way that every time the operation lever is pushed or pulled, the bases of the arms engage with the one-way clutch, thereby driving a hub, which is established on the periphery of the one-way clutch and fastened to a wheel , in a normal rotational direction causing the wheelchair to move forward.
Thanks to the above configuration, in an alternating motion of the operation lever, when the operation lever moves forward, the driving force of the operation lever drives the forward arm of the one-way clutch in a normal rotational direction (and the backward arm in a reverse rotational direction) via the one-way-clutch-driving link, and the base of the arm frictionally engages with the one-way clutch and drives the hub, which is established on the periphery of the one-way clutch and fastened on the wheel, in a normal rotational direction, whereas when the operation lever moves backward, the driving force of the operation lever drives the backward arm of the one-way clutch in a normal rotational direction (and the forward arm in a reverse rotational direction) via the one-way-clutch-driving link, and the base of the arm frictionally engages with the one-way clutch and drives the aforementioned hub in a normal rotational direction, thereby moving the wheelchair forward with either movement of the operation lever.
In the above configuration, in order to drive the hub in a normal rotational direction by engaging the bases of the arms with the one-way clutch, it is effective to employ a configuration wherein the bases of the pair of arms of the one-way clutch are rotatably and coaxially mounted on the hub spindle, which is fastened to the frame of the wheelchair, in such a way that one rests on the periphery of the other, and the forward arm and the backward arm are linked to a one-way clutch main body via a normal rotation one-way clutch and a reverse rotation one-way clutch respectively, the clutch main body being provided with a spring clutch wound around its periphery, the spring clutch having projections on its both ends, one of which being inserted and settled in a groove formed on the clutch main body and the other of which being inserted and settled in a groove of a spring-clutch-end-supporting disc established via a normally rotating one-way clutch on the periphery of the hub spindle so that the hub is engaged and linked to the clutch main body via the spring clutch.
In this way, the one-way clutch part can be inserted into the hub to make a unit construction, and whenever the forward arm rotates in a normal direction or the backward arm rotates in a reverse direction, the one-way clutch is easily rotated in a normal direction.
On the other hand, when moving the wheelchair backward using the push rim the projection of the spring clutch inserted into the groove of the spring-clutch-end-supporting disc, i.e., the projection that is opposite the projection inserted into the groove of the one-way clutch main body, becomes stationary because the one-way clutch prevents the supporting disc from rotating backward. As a result when the push rim is pushed backward, the spring clutch is contracted, and the hub reversely rotates while slipping on the spring clutch, making it possible for the wheelchair to move backward smoothly.
Preferably the distance between the sub pivots linking the one-way-clutch-driving links to the operation lever and the main pivot of the operation lever can be extended or shortened. When the sub pivots are positioned farther than the standard positions from the main pivot, more power is required to push or pull the lever, but the stroke of the operation lever can be shortened. On the other hand when the sub pivots are positioned closer than the standard positions to the main pivot, less power is required to operate the lever, but the stroke of the operation lever has to be longer. Accordingly, the former type is suitable for a physically strong user while the latter type is suitable for a user with less physical strength.
In the above configuration, a balance spring is preferably established on the opposite side of the main pivot of the operation lever from the rockably attached sub pivots linking the one-way-clutch-driving links to the operation lever, so as to counterbalance the weight of the operation lever and one-way-clutch-driving links which are positioned forward of the main pivot.
REFERENCES:
patent: 323085 (1885-07-01), Taylor
patent: 4453729 (1984-06-01), Lucken
patent: 4506900 (1985-03-01), Korosue
patent: 4560181 (1985-12-01), Herron
patent: 4682784 (1987-07-01), Anderson
patent: 5358266 (1994-10-01), Roth et al.
patent: 5722
Koda & Androlia
Mar Michael
Phan Hau
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