Patent GB-732651-A (GB)
Title: Motor vehicle change speed gearing
IPC: F16H47/08
Filed: 1950-02-02
Abstract: 732,651. Hydromechanical variable-speed gear. VOITH GES., J. M. Feb. 2, 1950 [May 13, 1949], No. 2774/50. Class 80 (2). [Also in Group XXIX] A motor-vehicle transmission comprising a turbo torque-converter 22, driven through a torque-splitting planet-gear 20, with means for cutting out the fluid power-path (Figs. 2-5) or the mechanical path (Figs. 6-8), is such that a ratio u/#wopt. lies between 0.5 and 1.2; u being defined as the ratio of the planet gear, as expressed by the speed of the output shaft 17 divided by that of the turbo impeller 22 when the input shaft 15 is fixed, and #wopt. as the speed ratio between the turbine 24 and impeller 22 of the torque-converter at its point of maximum efficiency. The control of the changeover may be manual or automatic (not described), and where fluid drive is superseded, the torque-converter may be emptied, the reactor released, as by a controllable or one-way brake, or permitted to be over-run at a one-way clutch which may be locked for hydrodynamic internal braking in the converter. The output shaft 17 may drive the final output shaft 32 through fixed or multi-ratio planet gear. In Fig. 2 the torque-split planet gear comprises input and output suns 15, 16 meshing stepped planets carried by the converter impeller 22, application of a brake 23 to which provides an all-mechanical overdrive to the output shaft 17 which latter over-runs the turbine 24 at 25. Three brakes 29, 30 and 31 of the triple output train give respectively two reduced forward ratios and one reverse between the shaft 17 and a final output shaft 32. The converter is jacketed at 27 for coolant. Modified arrangements are as follows. Fig. 4 (not shown) uses as the torque-split train a simple sun-ring train, with input planet carrier, ring secured to the final output shaft and sun fast with the converter impeller and brakeable for all-mechanical overdrive. A disc clutch between the sun and carrier provides an allmechanical direct-drive. The converter turbine drives the output shaft through fixed-ratio sunring reducing gear, and the converter is emptied during all-mechanical drives. The torque-split train of Fig. 5 (not shown) uses input and output suns, stepped planets and two rings, one driving through a one-way clutch the impeller of the torque-converter, the turbine of which is oneway mounted on the final output shaft, no output train being used. Brakes can be applied to the planet-carrier for all-mechanical overdrive, and to either ring for two lower all-mechanical ratios. Fig. 8 provides an all-fluid drive to an intermediate output shaft 172 when a brake 180 is applied to the planet-carrier of a torque-split train which then overdrives the converter impeller. The converter turbine, fast on the intermediate shaft 172, drives the final output shaft 177 through triple sun-ring trains having all corresponding wheels of equal size. Brakes 168, 169 and 170 provide respectively normal, low and reverse. In the two other forms providing all-fluid drive at change-over, Figs. 6 and 7 (not shown), a parallel input shaft drives the torque-split train through gear pairs. In Fig. 6 (not shown), the initial torque-split phase is obtained by braking the torque-converter reactor which, for all-fluid drive, is subsequently released and a brake applied to a ring gear oneway mounted on the final output shaft, so that the converter impeller, fast with a sun, is now overdriven by the input-planet carrier and the converter acts as a fluid coupling. The turbine is fast on the final output shaft. Fig. 7 (not shown) modifies this arrangement, by a twospeed torque-split train having stepped planets on an input carrier, and brakes for two suns one of which is one-way mounted on the final output shaft to be over-run in the all-fluid phases. The turbine is fast on the output shaft and the impeller fast with a single ring. The one-way connection can be locked for braking by hydrodynamic internal action in the converter, and the torque-converter reactor may be released for fluid-coupling operation.