Machine element or mechanism – Mechanical movements – Rotary to intermittent unidirectional motion
Reexamination Certificate
2000-01-20
2001-12-11
Herrmann, Allan D. (Department: 3682)
Machine element or mechanism
Mechanical movements
Rotary to intermittent unidirectional motion
C280S236000, C475S170000
Reexamination Certificate
active
06327926
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to a direction-controlled transmission (free-running clutch) with an input element and an output element between which coupling elements such as coupling bodies, coupling rollers or coupling pawls are arranged that themselves or together with bodies connected to them both in the free-running position as in the torque-transmitting position are connected in the rotation direction of the output element with same and which in the free-running position move in an annular guide of the input element and in the torque-transmitting position are wedged on this guide.
BACKGROUND OF THE INVENTION
With prior-art known free-running or slip clutches, torque transmission takes place by means of pawls, coupling bodies, or balls that fit between the input and output elements. For example with a bicycle free-running hub, balls are used so that if the input shaft turns faster than the housing, the balls are urged outward by the shape of grooves in the shaft and wedge solidly between the input and output shafts so that the housing is entrained. If on the contrary the housing turns faster than the input shaft, the balls move inward in the grooves so that there is no force transmission.
All these clutches have in common that the coupling element is positioned radially between the input and output elements where it either in the coupling position blocks relative movement between the input and output elements or in the free-running position permits relative movement of the input element and the output element.
In order to make the free-running clutch simpler and cheaper to manufacture even with these functions, German 2,452,650 proposes a free-running clutch with nonround coupling bodies between an inner and an outer coupling ring and out of contact when slipping with the faster coupling ring, the coupling bodies each being held against the faster ring when slipping by means of a part-cylindrical surface parallel to the body axis. The clutch has an inner coupling ring fixed on a shaft and a concentric outer coupling ring on another shaft concentric with the inner ring. The gap between the two coupling rings holds nonround coupling bodies of which each has a bore extending parallel to its pivot axis and by means of which it is mounted on a hardened pivot bolt. The ends of the pivot bolt projecting past the coupling bodies are each force fitted in a bore seat of an inner annular flange of the outer coupling ring. The bore in the one flange and the surface formed by the pivot bolt also form the coupling surface for the outer coupling ring.
WO 95/03503 describes a steplessly or almost steplessly variable positive-contact planetary-gear transmission with input and output elements that have several wheels that together form a planet wheel that are in permanent mesh with a sun wheel. The ratios of the effective radii of the planet wheel and the sun wheel and the relative eccentric positions of the planet wheel and the sun wheel which can be varied by various means determine the speed relationship between the input and output elements. The wheels forming the planet wheel cyclically run, when set eccentrically to the sun wheel, through a torque-transmitting load path and a load-free path, the wheels rotating both about the planet-wheel axis and via respective one-way clutches about their own axes. On moving from the load-free path to the arcuate load path the wheels as a result of meshing block their actual rotation and transmit the applied torque. Any irregularity in the torque transmission is compensated for by variation of the radii determined by the load arc and/or the effective tangential component in a cyclical manner.
OBJECT OF THE INVENTION
It is an object of the present invention to provide a new directionally controlled transmission that is simple to build and that permits the transmission of considerable torque.
SUMMARY OF THE INVENTION
This object is attained by the transmission according to the invention which is usable as a steplessly or almost steplessly variable transmission or with no eccentric adjustability of the input element relative to the output element to provide a constant transmission ratio between the input and output elements. Basically however for both parts of the same embodiment the same advantages are usable to the same extent with both solutions.
According to the invention the output element has radial guides in each of which a projecting coupling-body pin or an element connected with the coupling body is radially guided and the output element is moveable eccentrically to the input element, the coupling elements when eccentric moving cyclically through a torque-transmitting load path or zone and a load-free path or zone and when moving from the load-free path to the torque-transmitting load path the applied torque is transmitted from the input element by force and/or structural engagement.
The claimed transmission includes embodiments where the input element has the described radial guide and the output element the annular guide. In a two-stage embodiment of a transmission one stage has the annular groove or body and the following stage the radial-groove disk so that stable phase positioning is obtained to reduce irregularities.
With this solution the coupling elements serve according to the invention direction both as sliding as well as force-transmitting elements without any further parts such as balls or roller cages, coupling grooves, or other inertially working coupling parts being necessary. Wedging of the coupling elements is initiated in only one part, namely the guide of the input element formed as an annular groove or body, so that separate pivoting or mounting on the input or output elements is not necessary. The hitherto necessary formation of an inner and an outer ring between which the coupling elements are mounted can be eliminated. In the simplest case the coupling elements themselves or their parts projecting out of the annular groove of the input element are coupled rotationally to the output element. The invention includes also embodiments where movable with the coupling elements in the guide or annular groove of the input element are bodies that are connected with the coupling elements and that serve as torque-transmitting elements rotationally coupled with the output element. The basic idea of the invention includes thus all arrangements where the coupling force does not—as in the transmissions according to the state of the art—transmit forces between separate bearings and shafts, thereby giving the advantage that only the substantially smaller tangential force between the coupling elements and the guides is effective during torque transmission.
In order to obtain with the transmission not only transmission ratios in the neighborhood of 1:1 but also to provide other transmission ratios, the transmission is set up as a gear drive such that the output element has radial guides in each of which is arranged for radial movement a projecting coupling-body pin or an element connected with the coupling body, the output element being adjustable eccentrically relative to the input element, the coupling elements running cyclically with eccentric positioning through a torque-transmitting load path and a load-free path in the described manner. In this manner one achieves stepless control of the rotation speed with good drive safety and a long service life. Speed variations as can occur with V-belt transmissions as a result of slip are eliminated.
Thus the input element is a disk with generally radially extending grooves as radial guides or alternatively can have a sort of gear wheel as output element in the form of a shaft with radially projecting arms whose axial surfaces are formed as radial guides and that the respective projecting coupling-body pins or the elements connected with the coupling bodies when passing through the arcuate load path transmit torque to the arms and when passing through the load-free path are entrained by entrainment connections, preferably a wire or an elastic ring, from the closest arm of the sh
Dubno Herbert
Herrmann Allan D.
Satellite Gear Systems Ltd.
Wilford Andrew
LandOfFree
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