Patent GB-666092-A (GB)
Title: Improved variable-speed power transmission mechanism for motor vehicles
IPC: F16H47/08
Filed: 1949-07-12
Abstract: 666,092. Hydromechanical variable speed gear; friction clutches. GENERAL MOTORS CORPORATION. July 12, 1949 [July 31, 1948], No. 18359/49. Class 80 (ii). [Also in Group XXIX] A hydrodynamic torque-converter has an impeller 3, permanently fast on the input member 1, a reactor R supported by a one-way detent 15, and main and auxiliary turbines O, O<SP>1</SP>, the latter at maximum radius to take the greater torque, each such turbine O, O<SP>1</SP> being connected to a separate element of a three-element planetary train, the third element of which is connected to the final output shaft 50, the arrangement being such that drive occurs in four successive phases, first by the auxiliary turbine O<SP>1</SP>, second by the main turbine O, with the auxiliary overrunning by virtue of a one-way clutch 10 connecting it with the main turbine, third with the converter acting as a fluid coupling with overrunning reactor, and fourth in which one of the members of the converter is frictionally clutched to the output shaft, providing in some constructions an all mechanical direct-drive and in another (Fig. 6) a split-torque hydromechanical drive. In Fig. 6 this friction clutch is engaged by the hydraulic pressure in the converter casing. Reduced and reverse-drive hydraulically-actuated friction brakes 36, 35, Fig. 1, are also provided. In Fig. 1, the auxiliary turbine O<SP>1</SP> is connected through the one-way clutch 10 and sleeve 11 to a pair of integral suns 18, 20, the main turbine O being connected through a sleeve 13 with a first planet-carrier 21 supporting planets 27 meshing the first sun 18 and a ring 24 permanently fast to the final output shaft 50 by way of the driven casing of the direct-drive clutch 26, and carrying the second planets 28 meshing the second sun 20 and a freely-mounted ring 23. The inner driving member 30 of the direct-drive clutch 26 is connected permanently to the input member 1 through an innermost shaft 14. In the first drive phase, the second ring 23 is held by a reduced-drive brake-band 36 and the auxiliary turbine 0' drives the second sun 20 so that the second train alone drives the output 50. Speedincrease to the second phase causes the main turbine O to drive the first carrier 21, thus increasing the speed of the second carrier and output shaft, the auxiliary turbine O<SP>1</SP> then overrunning its ratchet 10. Further speed-increase introduces a third phase with the reactor R overrunning its detent 15 so that the converter acts as a coupling. The fourth, all mechanical, phase is provided by manually operating a valve to disengage the reduced drive brake 36 and apply the direct-drive clutch 26, through a piston 33, liquid pressure being provided by input and output driven pumps P, Q. Reverse is by braking the first carrier 21 at 35 so that the auxiliary turbine O' drives through the first train alone. Fig. 2 (not shown) and Fig. 6 modify the gear train by providing single long planets (not shown in Fig. 6, but like those 107 in Fig. 3) carried by the output shaft 50, and meshing respectivelya freely mounted second sun 70 having a reduced-drive brake 71; a first and only ring-gear 67 directly driven by the main turbine 0; and, through intermeshed short planets 63 on the same carrier, a first sun 61, ratchet-driven by the auxiliary turbine as before. The ring-gear 67 has a reverse-drive brake 68. Fig. 2 (not shown) uses this train with a rearwardly mounted direct-drive clutch as in Fig. 1, with its input central shaft driven through a spring coupling. Fig. 6 uses a forwardly-mounted direct-drive clutch inside the converter casing. The right face of its presser-plate 138 is subject permanently to converter-pressure supplied continuously by a pump, whilst its left face is subject to the same pump-pressure supplied to a sealed chamber 160 through the hollow forward extension 50a of the output shaft 50 which carries the driven disc 136. Normally, with pressure on both sides of the presser-plate, the clutch is disengaged by springs 143. Exhausting the left chamber 160 by a manual control valve causes converter-pressure to engage the clutch for direct mechanical drive, and at the same time, pump-pressure releases the reduced-drive brake. Pressure-circuit details are in Fig. 4 (not shown). Fig. 3 uses a train somewhat similar to Fig. 6, having long planets 107 carried by the output shaft 50, and meshing respectively-a. first ring 114 driven by the main turbine and having a reverse-drive brake; short planets 115 meshing also a sun 112 driven by the auxiliary turbine; a reaction-sun 117 having a reduced-drive brake 120, all as in Fig. 6; and in addition, fast on the output shaft 105 of the forwardly mounted mechanical clutch, a central sun 106 equal in size to 117 so that when the mechanical clutch is engaged, a split-torque hydro-mechanical directdrive is transmitted to the final output shaft 50. Fig. 5 (not shown), uses three separate sunring trains the middle one giving the lowest speed phase and having a sun integral with the shaft of the auxiliary turbine which is now the centre shaft; a ring reacting through a one-way detent to a brake drum; and a final driven carrier. The first train has a ring driven by the main turbine, a carrier fast to the final output member and a reaction sun which can be held by a brake for reduced drive and is clutched to the carrier for direct-drive, which, in this case, is still through the converter. The last train has a carrier fast on the final output shaft, a sun fast to the ring of the second train, and a reaction ring which is braked for reverse. The Specification as open to inspection under Sect. 91 includes Fig. 7, (Cancelled), which differs from all the above forms in having a single train, with the carrier 171 directly connected to the output shaft 50, and to the main turbine O; a sun 166 directly connected to the auxiliary turbine O<SP>1</SP>, without an interposed oneway clutch; and a reaction-ring 167 which can be held fast by either of two brake-bands 169, 175 one, 175, of which acts through a one-way detent 170. The converter has two impellers I, I<SP>1</SP>, connected by a one-way clutch Z, and two reactors R, R' connected by separate one-way detents 15, 15<SP>1</SP>, to the fixed frame. No mechanical clutch is provided. This subject-matter does not appear in the Specification as accepted.