Machine element or mechanism – Gearing – Backlash take-up
Patent
1995-07-26
1997-06-10
Marmor, Charles A.
Machine element or mechanism
Gearing
Backlash take-up
74461, 74462, F16H 5518
Patent
active
056365500
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a no-backlash gearing mechanism.
2. Discussion of the Related Art
A no-backlash gearing mechanism is disclosed in United Kingdom patent specification No. 1 251 941 in which the teeth of at least one of a pair of meshing toothed elements are formed of elastic rubber or plastics material and may additionally be formed with slots or bores to improve their deformability. By urging the toothed elements together when meshing, the deformable teeth of one element fully mesh with the teeth of the other element without back-lash. However, this gearing arrangement is only suitable for very light loads since, due to the deformability of the teeth, slippage of the meshing toothed elements can occur.
European patent specification No. 0 084 197 also offers a solution to the problem of back-lash in gearing mechanisms. The gearing mechanism of EP 0 084 197 comprises a pair of meshing toothed elements, each of which have teeth of transverse asymmetrical shape which, when meshing, are urged into contact with each other in a direction normal to the plane of rotation of the toothed elements. In addition, the teeth of the toothed elements may be slotted to improve their deformability and thus ensure no-backlash. This arrangement necessitates the inclusion of means for urging the meshing toothed elements into contact in a direction normal to the plane of rotation of the toothed elements.
United Kingdom specification No. 1 202 806 also offers a solution to the problem of back-lash in gearing mechanisms. The solution discussed is even more similar to that of GB 1 251 941 than that of EP 0 084 197. The gearing mechanism of GB 1 202 806, whilst being an internal/ring gear mechanism, utilises the principle of having a first meshing toothed element with teeth formed of deformable material urged into meshing engagement with a second toothed element, wherein the deformable teeth, when meshing, deform to completely mesh with the teeth of the second toothed element thereby preventing back-lash. This gearing mechanism is also susceptible to slippage due to the high deformability of the teeth.
OBJECTS AND SUMMARY OF THE INVENTION
It is an object of the present invention to obviate and mitigate the aforesaid disadvantages of the prior art gearing mechanisms by providing a gearing mechanism for eliminating back-lash without unduly compromising the drive capabilities of the mechanism so formed.
According to the present invention there is provided a gearing mechanism comprising meshing toothed elements wherein at least some of the teeth of one of said elements have an undulated longitudinal transverse section whereby the elements can be meshed such that at any one time one of the teeth having an undulated longitudinal transverse section makes at least one point of contact with each of two opposing adjacent teeth of the other element.
Preferably, all of the teeth of one of the elements have an undulated longitudinal transverse section.
Preferably further, all of the teeth of the other element have a corresponding conversely undulated longitudinal transverse section.
Preferably also, the teeth of the meshing toothed elements having an undulated longitudinal transverse section have a regularly undulated form.
The teeth of the meshing toothed elements may be resiliently deformable.
The meshing toothed elements may each be generally in the form of gear wheels.
Alternatively, one of said meshing toothed elements may be a rack, thus providing a gearing mechanism in the form of a rack and pinion.
Preferably, the pitch of teeth on one meshing toothed element exceeds by a small amount the spaces between teeth of the other meshing element.
The gearing mechanism may comprise a spur gear, bevel gear or internal gear mechanism.
BRIEF DESCRIPTION OF THE DRAWINGS
The foregoing and further features of the present invention will be more readily understood from the following description of preferred embodiments, by way of example thereof, with reference to the accompanyi
REFERENCES:
patent: 1443837 (1923-01-01), Eberhardt
patent: 1702860 (1929-02-01), Bottcher
patent: 2065021 (1936-12-01), Pioch et al.
patent: 2572334 (1951-10-01), Guibert
patent: 2764034 (1956-09-01), Hotine
patent: 3122938 (1964-03-01), Visser
patent: 3292390 (1966-12-01), Wildhaber
patent: 4552030 (1985-11-01), Szecsei
Patent Abstract of Japan, vol. 8, No. 238, Oct. 1984, JP-A-59 117951.
Grabow Troy
Marmor Charles A.
Perkins Limited
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