Power transmission mechanism including hydrodynamic torque converter

摘要

Power transmission mechanism, for vehicles, of the kind comprising a hydrodynamic torque converter 60 in series with stepped change-speed gearing 62 have a relatively low efficiency and are not continuously variable over their full working ranges. Their efficiency is significantly improved and continuous variability achieved by inserting in the power path an epicyclic gear 61 one element 22 of which is driven from the turbine 19 of the torque converter, another element 23 of which is held against rotation in one direction and is driveable in the other direction by a clutch 26 from a transmission input member 16 which drives the impeller 15 of the torque converter, and a further element 26 of which drives the change-speed gearing, the clutch being alternately engaged and disengaged automatically during upshifts through the change-speed gearing whenever the torque converter reaches its minimum slip condition and during downshifts through the change-speed gearing whenever the speed ratio of the torque converter falls to a predetermined value. A reversing gear 52 follows the change-speed gear 62 which may be epicyclic instead of the countershaft gear 62 shown. IMAGE