GB824009A - Variable speed power transmission mechanisms - Google Patents

Abstract

824,009. Variable-speed gear. WICKMAN, A. C. Jan. 23, 1958 [Feb. 7, 1957; April 9, 1957], Nos. 4262/57 and 11485/57. Class 80 (2). [Also in Group XXXIV] A hydromechanical variable-speed transmission for motor cars comprises a hydrodynamic torque converter having an engine-driven impeller i, a first turbine t<SP>1</SP> connected through a one-way clutch c<SP>1</SP> to a shaft 3 and a sun gear s<SP>1</SP>, a second turbine t<SP>2</SP> fast with a shaft 4 and a sun-gear s<SP>2</SP>, a single, or, as shown, two-part reactor r<SP>1</SP>, r<SP>2</SP> connected through one-way detents c to a reaction shaft 2, a third sun gear s<SP>3</SP> controlled by an hydraulically engaged brake 6, and interengaging compound planet pinions p<SP>1</SP>, p<SP>2</SP>; p<SP>3</SP>, p<SP>4</SP> mounted in a carrier 8 fast with a final driven shaft 7. When starting the car from rest, the brake 6 is applied to station the third sun-gear s<SP>3</SP>, and the first turbine t<SP>1</SP> transmits drive, the second turbine t<SP>2</SP> rotating more slowly. As the speed increases, the second turbine t<SP>2</SP> begins to drive, causing the first sun-gear s<SP>1</SP> to be rotated more quickly than its turbine t<SP>1</SP>, with the one-way clutch c<SP>1</SP> over-running. To obtain direct drive with the hydro-dynamic torque converter bypassed, fluid under pressure is supplied to act upon a piston 29 and engage a friction clutch 21 between a shaft 10, fast with the torque converter impeller i, and the output shaft 7. In the form shown, the two-part reactor element r<SP>1</SP>, r<SP>2</SP> acts through its one-way detents c to turn the reaction shaft 2 which has an arm 22 fast therewith, a spring 23 engaging the arm and opposing rotation of the shaft. As soon as no torque is applied through the reactors r<SP>1</SP>, r<SP>2</SP> upon the shaft 2, the arm 22 moves to open a valve 24 which disengages the hydraulically applied brake 6 and engages the hydraulically controlled clutch 21 for direct drive. To obtain reverse, an hydraulically controlled brake 9 is applied to station the shaft 4 and the sun-gear s<SP>2</SP>. In a modification, Fig. 2 (not shown), a hydrodynamic torque converter has three turbines, two of which are connected through one-way clutches to two sun-gears, a third is connected directly to a third sun-gear and a fourth sun-gear can be braked to act as a reaction member. An additional low ratio is obtained by braking an internally toothed annulus engaging the planet pinions p<SP>1</SP>. The direct drive clutch is an hydraulically controlled disc clutch located within the housing h of the hydrodynamic torque converter. In another modification, hydrodynamic braking when the car over-runs its engine is obtained by engaging an hydraulically-controlled friction disc clutch 25, Fig. 5, in parallel with the one-way clutch c<SP>1</SP> connecting the first turbine t<SP>1</SP> to its shaft 3.