Patent GB-846301-A (GB)
Title: A hydrodynamic transmission, principally for motor vehicles
IPC: F16H47/08
Filed: 1957-07-04
Abstract: 846,301. Variable-speed gear. ROCKWELL G.m.b.H. July 4, 1957 [July 12, 1956], No. 21160/57. Class 80 (2). [Also in Group XXXIV] A hydrodynamic transmission for motor-cars comprises a power-dividing differential gear driving through a mechanical power path directly to a final output shaft and also driving through a parallel hydraulic power path consisting of a torque converter and a change-speed gear to the final output shaft, the change-speed gear being located between the turbine of the torque converter and the final output shaft while the mechanical power path bridges both the torque converter and the change-speed gear. Gearing.-An input-shaft 1, Fig. 2, drives the ring-gear 2 of a planetary differential gear which splits the torque transmitted, sending part through planet pinions 6 and a carrier 5 to an output shaft 7 and part through a sun gear 3 to the impeller 4 of a hydrodynamic torque converter having its turbine 9 connected by a shaft 10 to the sun gears 11, 14 of two planetary geartrains. The sun gears 11, 14 mesh planet pinions 12, 15 supported by a common carrier 17 fast with the output shaft 7, the planet pinions meshing ring-gears selectively stationed by actuation of mechanically, electrically or hydraulically-operated brakes 18, 19. To obtain a wholly mechanical drive, a brake 8 is applied to station the torque converter impeller 4. With the brake 8 disengaged, application of one or other of the gear brakes 18, 19 gives a split torque drive in one of two ratios. More than two trains of planetary gears may be inserted between the turbine 9 and output-shaft 7, to give more than two alternative ratios. Hydrodynamic braking when the output shaft 7 drives the driving-shaft 1 is obtained by engaging the brake 8, to station the impeller 4, simultaneously with engagement of one or other of the brakes 18, 19. In a modification, Fig. 3 (not shown), the output shaft 7 drives a simple sun-planetsring gear reversing gear. In another modification, Fig. 4, the sun gear 11 of Fig. 2 is omitted and the ring gear 16 of the second change-ratio train is connected by a drum 33 to the sun gear 20 of a reversing planetary gear, having planet pinions 24 on a carrier 32 fast with the output shaft 7, these planet pinions meshing a ring gear stationed by a brake 31 for reverse. In a further modification, the gears &c. are arranged in the same way as in Fig. 4 but are spatially disposed with the input shaft 1, Fig. 5, differential gear 3, 6, and change-ratio gears 12 ... 16 all on the same side of the torque converter 4, 8, 9. The planet pinions 6, 12, 15 are mounted on a common carrier 34 which drives through gears 35, 36 to the output shaft 7. In the forms of Figs. 4 and 5, application of the reverse brake band 31 when the output shaft 7 drives the input shaft at the same time as the driving-shaft 1 is rotated in the normal way, produces a braking effect on the output shaft. Control.-A pressure-fluid control circuit for the forward and reverse ratio brakes of the gearing comprises an output-driven pump 39, Fig. 6, supplying fluid-pressure through a pipe 40 to a hand-operated selector valve 43 which connects with pipes 44 ... 46 leading to the gear brakes. An output-shaft-driven speed-responsive governor 42 acts upon a slide-valve 41, when a sufficiently high output shaft speed is reached, to prevent the supply of pressure-fluid to the selector valve 43 and instead opens a pipe leading to the impeller brake 8, so that the wholly mechanical drive results. The slide valve 41 can also be operated by mechanism 47, 48 connected to the motor car throttle. In another form applied to the gearing shown in Fig. 4, the pump 39, Fig. 7, is driven from the input shaft 1 and supplies fluid under pressure through oneway valves 50, 51 to pipes 52, 53 which both lead into the hydrodynamic torque converter 4, 9. The pump 39 also supplies fluid under pressure through a pipe 54 to a slide-valve 41 opened by an output-driven speed-responsive 'governor 42 when the motor car road speed exceeds a predetermined value, so that pressure fluid then passes through a pipe 55 to the impeller brake 8 for wholly mechanical drive. A pipe 58 leads from the torque converter 15 to a hand-operated selector valve 59 which, in the position shown, feeds a pipe 64 leading through a slide-valve 56 to a pipe 65 and thence to the brake 19. This is the position for normal drive. When the speed governor 42 opens the valve 41 to supply fluid pressure to the pipe 55 and engage the impeller brake 8, fluid-pressure acts simultaneously upon the slide valve 56 to shut off the supply of pressure-fluid from the pipe 64, and connects the pipe 65 through a pipe 67 and the -casing 60 of the selector valve with an exhaustpipe 66, so that the brake 19 is disengaged. The engagement of the impeller brake 8 can also be effected by operation of the motor car throttle, acting through mechanism 47, 48. The low and reverse ratios are obtained by hand operation of the selector valve 59 to connect the pipe 58 to pipes 61, 63, respectively.