Torotrak (development) Limited

Torotrak Limited

Philip Duncan Winter

Christopher John Greenwood

Thomas G Fellows

David Burt

An infinitely-variable transmission system is disclosed. The system comprises an input shaft () and an output shaft (). The transmission is operative to transmit rotational drive between the input shaft () and the output shaft (). The transmission includes a variator () that can transmit drive at a continuously variable ratio between a minimum variator ratio and a maximum variator ratio. The transmission can operate a low-speed regime and in a high-speed regime. The transmission is operative in the low-speed regime, at a neutral low regime variator ratio, the transmission is in geared neutral, in which, the output of the transmission is stationary irrespective of the speed of the input of the transmission and at a maximum low regime variator ratio, the output of the transmission is driven from the input of the transmission at a maximum low-regime transmission ratio, In the high-speed regime, at a minimum high regime variator ratio, the output of the transmission is driven from the input of the transmission at a minimum high-regime ratio and at a maximum high regime variator ratio, the output of the transmission is driven from the input of the transmission at a maximum high-regime transmission ratio.

Infinitely-variable transmission for a vehicle

A multi-regime continuously variable ratio transmission has a transmission input shaft, a transmission output shaft, and a ratio varying unit having a rotating input and a rotating output, the rotational axes of the input and the output being coaxial. A shunt having first and second epicyclic gear sets is connected across the ratio varying unit. One gear set has an input driven by the input shaft and an input driven by one side of the ratio varying unit and the other gear set has an input from the first gear set and an input from one side of the ratio varying unit. The gear sets rotate about a common axis and are offset with respect to, and parallel to, the rotational axes of the input and output of the ratio varying unit. A clutch is operable to selectively connect the output of the second gear set to the output shaft.

Continuously variable ratio transmission

A continuously variable transmission having a transmission input () and a transmission output () is described. The transmission has a variator (). This is a device which transmits drive at steplessly variable ratio. It further comprises an epicyclic gear arrangement () incorporating a clutch arrangement (). The epicyclic gear arrangement has three rotary members. One of these is coupled to a planet carrier () having at least one planet gear (). Another of the rotary members is coupled to a main gear () meshing with the planet gear. The clutching arrangement serves to couple the remaining rotary member to either of first and second alternative gears (), both of which mesh with the planet gear and which rotate at different speeds. One of the aforesaid rotary members is coupled to the transmission input at a fixed drive ratio. One of them is coupled to the variator output. The last of the rotary members is coupled to the transmission output. By way of the clutching arrangement the transmission can be changed between first and second ratio ranges.

Continuously variable transmission

The invention is concerned with a continuously variable transmission incorporating a variator of the type having at least two co-axial races (D-D) between which drive is transferred at a continuously variable variator ratio. The variator races are mounted for rotation about a variator shaft (). The transmission has a layshaft () which is laterally separated from the variator shaft. It has two epicyclic gears. A splitter epicyclic () has an input member driven from the transmission input () and two output members arranged respectively to drive the layshaft and the variator shaft. A recirculater epicyclic has first and second input members for coupling respectively to the variator shaft and to the layshaft and a recirculater output member. An arrangement of clutches is provided for selectively engaging any of at least three regimes. In one regime the recirculater output member drives the transmission output. In another the layshaft drives the transmission output. In a third, the variator shaft drives the transmission output. The arrangement of the components is such that the variator shaft is co-axial with the transmission output, the recirculater epicyclic, a first coupling, between the recirculater output member and the transmission output, which serves to drive the transmission output in the first regime, and a second coupling, between the variator shaft and the transmission output, which serves to drive the transmission output in the third above-mentioned regime.

A roller control system for a continuously-variable-ratio transmission of the toroidal race, rolling traction type, in which rollers (60) of variable orientation transmit traction between a part-toroidal race (85) formed on an input disc (61) and a similar race (87) formed on a coaxial output disc (62). Each roller is mounted to rotate about a fixed centre (66) and a fixed axis (58) within a rigid carriage (67), one end of which contacts operating mechanism reciprocable over a predetermined stroke of operating movement and operable to apply a control force to the carriage. The assembly of roller and carriage is located by only three contacts with adjacent structure, namely the two disc/roller contacts (86, 88) and the contact (82) with the operating mechanism. These three contacts suffice to cause the roller constantly to seek a ratio angle at which the instantaneous value of the control force is balanced by the instantaneous value of the traction forces to which the roller assembly is subjected due to the contact between the roller and the two discs, and at which the transmission is therefore in equilibrium.

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Blackburn, United Kingdom

Philip Duncan Winter