Machine element or mechanism – Gearing – Toothed gear and recirculated unconnected elements
Patent
1991-03-28
1992-05-12
Herrmann, Allan D.
Machine element or mechanism
Gearing
Toothed gear and recirculated unconnected elements
741905, F16H 1508
Patent
active
051117100
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION This invention relates to toroidal race rolling
traction transmission units.
BACKGROUND OF THE INVENTION
Such units, as is well known, typically comprise two coaxial confronting discs defining a toroidal race and a plurality of rollers each engaging the discs to provide a variable transmission ratio between the discs in accordance with the attitude of the rollers with respect to the common axis of the discs. The discs are urged towards each other by a suitable end load in order to provide sufficient traction between the toroidal race of each disc and the rollers. By varying, usually in unison, the common attitude of the rollers with respect to the main, common axis of the input and output discs the transmission ratio may be changed. It is in practice necessary to change the attitude of the rollers by steering them in helical paths with respect to the discs. In a common form of construction, each roller is mounted in a carriage which has a rotary axis lying in a plane substantially normal to the main common axis of the discs. Each carriage may have its rotary axis defined by, at one end of the carriage, a sliding pivot such as a ball guide, and at the other end a spherical ball joint comprising a race and a ball which may be connected to a rocker arm which is or can be pivoted in unison with corresponding rocker arms for the other carriages in order to achieve a change in the attitude of the rollers and accordingly a change in the transmission ratio between the input and output discs.
Toroidal race rolling traction units of the general type are described in GB 979062 and GB 1069874; an arrangement including rocker arms is described in GB 2107009.
In many designs of this general kind there is difficulty in providing sufficient working clearances around the ball socket of the carriage for the roller in order to provide full angular travel of the carriage during a ratio change and yet to keep sufficient material to support the ball on the rocker against severe impulse loading. It is also necessary though difficult to maintain proper clearances between the carriage and the rocker at extreme limits of the range of variation of the attitude of the rollers and accordingly the transmission ratios that they provide.
SUMMARY OF THE INVENTION
One aspect of the present invention is to provide an improved transmission unit including an improved ratio changing mechanism including rocker arms.
The present invention is based on the provision of a ball race which is disposed at an angle which is substantially less than ninety degrees though substantially more than zero degrees with respect to the rotary axis of the carriage. Another aspect of the invention is the provision of a ratio changing mechanism in which each carriage has a sliding pivot connection with one rocker arm and a spherical ball joint connection with another rocker arm, each rocker arm thereby supporting the opposite ends of two carriages, and the rocker arms being movable in unison to cause a change in the attitude of the rollers.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a view of part of a toroidal race rolling traction transmission unit showing the characteristic features of the present invention; and
FIG. 2 is an explanatory diagram.
DESCRIPTION OF THE PREFERRED EMBODIMENT
FIG. 1 illustrates rollers 1 which are disposed between two confronting coaxial discs 20 in a toroidal race rolling traction unit of the kind described in GB 2107009. The rollers 1 of the present embodiment correspond to the rollers 4 of the aforementioned GB 2107009. The main axis of the discs is identified at 2 in FIG. 1. Each roller is mounted in a carriage 3 corresponding to the carriage 9 in the aforementioned specification.
Each carriage is disposed for bodily movement in a plane which is normal to the main axis 2 and is also capable of movement about an axis 4 defined between a sliding pivot 5 and a ball joint 6. The sliding pivot 5 comprises a cylindrical socket 7 in which is slidable a part spherical head 8 carried on an extension 9 of a
REFERENCES:
patent: 3371546 (1968-03-01), Spangler et al.
patent: 3410146 (1968-11-01), Nordeen
patent: 3430504 (1969-03-01), Dickenbrock
patent: 3455177 (1969-07-01), Schofield
patent: 3653272 (1972-04-01), Scheiter
patent: 3802284 (1974-04-01), Sharpe
patent: 3823613 (1974-07-01), Abbott
patent: 4499782 (1985-02-01), Perry
Farley Walter C.
Herrmann Allan D.
Krolikowski Julie
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