192 clutches and power-stop control – Clutches – Automatic
Reexamination Certificate
2002-05-23
2003-12-02
Lorence, Richard M. (Department: 3681)
192 clutches and power-stop control
Clutches
Automatic
C192S050000
Reexamination Certificate
active
06655515
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to clutches useful for lawn and garden implements, specifically bi-directional overrunning clutches.
2. Description of the Related Art
Lawn and garden implements, for example, mowers, tillers and snow throwers, often comprise a transaxle through which power from an engine is transmitted to ground-engaging wheels attached to axles extending from the transaxle for propelling the implement. These implements are often difficult to steer, owing to their weight, size, or the particular way in which the geartrain of the transaxle is designed. As to their geartrain design, many transaxles are provided with a solid axle which transmits an equal amount of torque to each of the pair of ground-engaging wheels, and during a turn, the wheel at the inside of the turn rotates at the same speed as the wheel at the outside of the turn; the wheel at the inside of the turn must be skidded on the ground to some degree, a considerable degree for sharp turns, in order to negotiate the turn. Controlling the implement can thus be a problem for some operators having insufficient strength or weight to force the implement through the turn as desired.
Previous attempts to address this problem include providing the transaxle with a differential, which allows the two ground-engaging wheels to rotate at different speeds, as is well known in the art. Through use of a differential, the wheel at the inside of the turn is not skidded on the ground during the turn; rather it slows down, while the wheel at the outside of the turn correspondingly speeds up. Differential arrangements, while improving the amount of control during cornering, add considerable cost to the transaxle. Moreover, even if the implement is provided with a differential-equipped transaxle, a not insubstantial amount of force is still required to initiate the turn and hold the implement therethrough. Thus, transaxles having differential arrangements do not provide satisfactorily controllable implements for all operators.
Another possible approach is the use of clutches to control the implement by powering or disengaging power from the ground engaging wheels, thereby providing a limited means for steering the implement. Some clutches which provide such control include means for selective disengagement of the input and output members (see, e.g., U.S. Pat. Nos. Re. 25,229, 2,951,568, and 3,429,408) or, specifically, include a spring which expands to produce engagement between the input and output members (see, e.g., U.S. Pat. Nos. 3,040,855 and 5,029,689). Previous wheel clutches may also use left and right hand grip-mounted triggers to engage and disengage the clutches. Such systems do provide means for simple engagement and disengagement of the clutches and limited power steering capabilities, but do not provide an intuitive, passive means for easily controlling the turning of the implement.
Another alternative has been steering mechanisms which use bi-directional overrunning clutches at each wheel. One such clutch is the Bi-Directional Clutch, designed and manufactured by the Motion Control Division of Hilliard Corporation of Elmira, N.Y. A change in the direction and/or speed of the implement causes the bi-directional clutch to sense the change and to allow overrunning of its connected wheel. Sensing the change in direction and speed is accomplished with a roller ramp design which allows a roller (maintained within a roll cage) to move between an outer race and multiple flat cams to engage and disengage the engine and transaxle. This clutch must be assembled directly to the axle, piece-by-piece, such as would occur when the implement is originally manufactured. Thus, as a practical matter, this clutch may only be added to an implement by the original equipment manufacturer, thereby preventing the operator of the implement from easily adding the clutch to an existing implement.
SUMMARY OF THE INVENTION
The inventive wheel clutch unit is modular, self-contained, and is assembled as a unit to the axle of a walk-behind machine, such as a lawnmower or a snow thrower. Furthermore, the clutch is bi-directional, similar to previous bi-directional overrunning clutches; however, unlike the previous overrunning clutches, the inventive modular and self-contained clutch unit does not need to be assembled to an implement component-by-component or by the implement manufacturer. The modular, self-contained clutch may be assembled separately and added to an existing implement after the final assembly and sale to a consumer. Additionally, a consumer may add the clutch to his implement since no assembly of the clutch itself is required by the consumer. The use of a self-contained and modular wheel clutch unit expands the addition of an overrunning clutch to anytime, including after the implement has been sold to the consumer, and by anyone, including the consumer.
The present invention provides a modular, bi-directional wheel clutch unit adapted to be assembled to the driving axle of a walk-behind machine including a rotatable wheel-driving hub including a casing portion, a clutch cage disposed in the casing portion and surrounded thereby and which has a plurality of circumferentially-distributed openings, a rotatably driven cam element disposed in the casing portion and surrounded by the clutch cage and which has a plurality of discrete surfaces thereon, and a plurality of rollers rotatably disposed within the casing portion and within the clutch cage openings. The rollers are located between the casing portion and the cam element discrete surfaces and have an engaged position wherein the cam element and the hub are in binding engagement through the rollers and the hub is rotatably driven by the cam element, and a disengaged position wherein the hub is freely rotatable relative to the cam element. The wheel clutch unit is self-contained and is selectively attachable and detachable as a unit to and from the axle of the machine.
The present invention further provides, in combination, a walk-behind machine having an engine, an axle rotatably driven by the engine, and a pair of ground engaging wheels, one the wheel located at each end of the axle, and at least one unitized wheel clutch unit. The clutch unit includes a rotatable wheel-driving hub detachably fixed to a the wheel and including a casing portion, a clutch cage disposed in the casing portion and surrounded thereby and having a plurality of circumferentially-distributed openings, a cam element detachably fixed to the axle and disposed in the casing portion, and a plurality of rollers rotatably disposed within the casing portion and within the clutch cage openings. The cam element is surrounded by the clutch cage and having a plurality of discrete surfaces thereon. The rollers are located between the casing portion and the cam element discrete surfaces, and have an engaged position wherein the cam element and the hub are in binding engagement through the rollers and the hub is rotatably driven by the cam element, and a disengaged position wherein the hub is freely rotatable relative to the cam element. The wheel clutch unit is self-contained and is selectively attachable and detachable as a unit to and from the axle of the machine.
The present invention further provides a modular, bi-directional wheel clutch unit adapted to be assembled as a unit to the driving axle of a walk-behind machine including a rotatable casing, a clutch cage disposed in and surrounded by the casing and which has a plurality of openings along a circumference of the clutch cage, a rotatably driven cam element disposed in the casing and surrounded by the clutch cage, and a plurality of rotatable elements rotatably disposed within the casing and within the clutch cage openings. The cam element has a plurality of discrete surfaces thereon. The rotatable elements are located between an interior surface of the casing and the cam element discrete surfaces, the casing being selectively driven by the cam element through selective engagement of the casing wit
Coble Vance E.
Cox C. Paul
Baker & Daniels
Lorence Richard M.
Tecumseh Products Company
LandOfFree
Modular bi-directional overrunning wheel clutch does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Modular bi-directional overrunning wheel clutch, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Modular bi-directional overrunning wheel clutch will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3165501