Planetary gear transmission systems or components – Nonplanetary variable speed or direction transmission... – Nonplanetary transmission is friction gearing
Patent
1991-03-25
1991-12-24
Diehl, Dwight
Planetary gear transmission systems or components
Nonplanetary variable speed or direction transmission...
Nonplanetary transmission is friction gearing
475186, F16H 3706
Patent
active
050748300
DESCRIPTION:
BRIEF SUMMARY
This invention relates to continuously variable transmissions of the kind having a toroidal race rolling traction unit in which the attitude of rollers between two discs defining the toroidal race may be adjusted in unison to vary a transmission ratio. More particularly the invention relates to a system in which the toroidal race rolling traction unit can be connected in two distinct ways to a final output so that the transmission has two regimes, in one of which the ratio of the rolling traction unit is varied though its full range and the overall transmission ratio varies through the lower part of its full range and in the other of which the ratio of the rolling traction unit varies back through its full range and the overall transmission ratio varies through the upper part of its full range. These two regimes, usually termed 'low' and 'high' regimes, may be provided by way of two different connections of the rolling traction unit to a final output, one connection being by way of an epicyclic stage and the other being a more direct geared or chain connection.
An object of the present invention is to provide a continuously variable speed ratio, preferably by means of a rolling assembly of the kind described, but to provide also at least one and preferably more than one, fixed overall transmission ratio which exhibits lower loss than normal and which is obtained by by-passing the variable unit altogether.
According to the present invention there is provided a transmission comprising an input rotary member, an output rotary member, a variable ratio unit driven by the input member and adjustable to provide a transmission ratio, between the input member and an intermediate member, which is continuously variable throughout a range, a first transmission coupling connectable between the intermediate member and the output member, a second transmission coupling connectable between the intermediate member and a rotary gear member which is disposed in an epicyclic gear stage, the output rotary member including a carrier for an epicyclic gear between the said rotary gear member and a geared driven by the input member and means operable to inhibit at least partially the epicyclic action of the epicyclic gear stage, so as to bypass the variable ratio unit and to provide a fixed overall transmission ratio within a range of continuously variable overall transmission ratios.
The invention will now be described by way of example with reference to the accompanying drawings.
DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic diagram of a continuously variable ratio transmission embodying the invention;
FIG. 2 is a diagram showing the relationship between various transmission ratios in the transmission;
FIG. 3 illustrates a modification of the transmission of FIG. 1;
FIG. 4 illustrates another embodiment of the invention; and
FIG. 5 illustrates a further embodiment of the invention.
DETAILED DESCRIPTION
In the transmission shown in FIG. 1 an input or main shaft 1 has at its input end a gear 2 which meshes with an input gear 3 on a shaft 4 that extends through a toroidal race rolling traction unit 5. This unit is of generally known form and comprises an input disc 6, keyed to the shaft 4 an output disc 7, rotatable with respect to the shaft 4, and a set of rollers 8, the attitudes of which can be varied in unison to adjust a transmission ratio between the discs 6 and 7, which define a toroidal race for the rollers 8.
The shaft 4 also carries a disc 9 which is engaged by a set of epicyclic rollers 10 (of which only one is shown) which are carried in a rotary carrier 11 formed as an extension to a shaft 12 which is in this arrangement coaxial with the shaft 4. The rollers 10 also engage the rear surface 13 of the output disc 7 to complete an epicyclic system and also to constitute a thrust bearing for the unit 5. The shaft 12 has a T-flange 14 which can be coupled to a gear 15 by means of a clutch Cl. The gear 15 connected by a chain (or idler gear) to a geared annulus 16 formed on an inward extension 17 from an output shaf
REFERENCES:
patent: 3866490 (1975-02-01), Orshansky, Jr.
patent: 4628766 (1986-12-01), de Brie Perry
patent: 4682511 (1987-07-01), Wittke
patent: 4872371 (1989-10-01), Fellows
patent: 4885955 (1989-12-01), Kraus
Diehl Dwight
Farley Walter C.
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