Patent GB-926859-A (GB)
Title: Transmission
IPC: F16H47/08
Filed: 1961-08-24
Abstract: 926,859. Hydrodynamic torque converters. GENERAL MOTORS CORPORATION. Aug. 24, 1961 [Sept. 14, 1960], No. 30532/61. Class 69 (2). [Also in Group XXIV] A change-speed gear for vehicles comprises a torque converter 13 having twin turbines, a first turbine T1 being connected to an output shaft 27 through a reduction planetary gear 30 and a second turbine T2 being connectable to the output shaft 27 either directly by means of a neutral clutch 26 or through a second reduction planetary gear. As shown in Fig. 7, an input shaft 10 drives a pump P of the torque converter, the turbine T1 of which is connected to a sun 25 of the planetary gear 30 which has an output connected planet carrier 29 which is clutchable by an hydraulically-engaged friction clutch 28 to the driving converter housing 15 for direct drive. The ring gear 32 is held one-way by a one-way clutch 39 and a brake 41 for forward drive, and is connected to the sun 34 of a reverse gear having an output carrier 36 and a reaction ring 37 stationed by a brake 38 for reverse. The turbine T2 (see Fig. 2), is axially slidable on a hub 73 which has a spline connection with the output shaft, and the turbine has a friction surface 79 engageable with a conical friction surface on an axially fixed member 77. Pressure in the torque converter moves the friction surfaces into engagement, the clutch being disengaged by supplying pressure to a chamber 82. Blades 83 on the rear of the turbine pump liquid out of the chamber 82 between the friction surfaces to give initial soft clutch engagement. Control system (Figs. 2-6). The gearing is controlled by a manually-operated switch 217 having forward F, neutral N and reverse R positions and controlling solenoid-operated valves 211, 212. A pump 143 supplies liquid to a main line 144, and in the position shown in which the switch 217 is set to forward and the solenoids of valves 211, 212 de-energized, is supplied from line 144, through valve 212 and a line 253 to a chamber 112 to apply the forward brake 41. Pressure in line 144 also acts on the upper side of a land b of the spool 152 of a valve 150, moving the spool downwardly to open line 144 to a line 163 which is connected through a valve 174 to a line 191 from which liquid is supplied, through a bearing 95 to the working chamber of the torque converter. The chamber 82 is exhausted through a line 244 and the valve 211, so that the neutral clutch 26 is engaged. Torque is initially transmitted through the turbine T1 and reduction gear 30 to the output shaft 27, and gradually taken up by the second turbine T2, until at a predetermined output speed a pitot governor 133 delivers a pressure through a governor line 170 which acting on the top of a valve spool 176 of the valve 174 is sufficient to move the spool downwardly, thus opening the main line 144 to a line 171 leading to the direct drive clutch 28 which is thereby engaged. The direct drive clutch line 171 incorporates a one-way throttle 196 to give a smooth engagement, and the pressure in line 171 acts on differential lands a, b of the valve 174 to ensure that the clutch 28 disengages at a lower speed than that at which it engages. The pressures in lines 170, 171 act on the spool of valve 150 which is moved downwardly against the bias of a spring 158 to open a restricted passage between the main line 144 and an exhaust line 164 to reduce the main line pressure. If the vehicle throttle pedal 222 is moved beyond its fully opened position it closes a switch 221, so energizing the solenoid 226 of the valve 211, which is moved upwardly so that line 144 is opened to a line 189 leading to the underside of valve spool 176. Except at high vehicle speeds the valve spool is moved upwardly against the governor pressure 170, so that the direct drive clutch 28 is disengaged and drive is again through the torque converter. In the neutral N position of the switch 217 solenoids 226, 232 of valves 211, 212 are both energized, disengaging clutches 26, 28 and releasing brakes 38, 41 to interrupt drive. In the reverse R position of the switch the solenoid valve 212 is actuated to supply liquid through a line 242, valve 211 and line 243 to the reverse brake chamber 129 to apply the brake 38. The clutch 26 is also engaged so that the turbine T2 is driven reversely by the output shaft 27, but this does not interfere with reverse drive at low speeds, and the first turbine T1 drives the output shaft at a lower ratio than in forward drive. Modifications.-The gearing of Fig. 7 can be modified by having the planetary gear 30 on the same side of the input shaft 10 as the reverse gear 40, also the direct drive clutch 28 can be replaced by a clutch between the driving casing 15 and the ring gear 32 of the reduction gear 30 to give torque-split drive instead of direct drive. In a further modification, Fig. 12, the first turbine T1 is connected to the reduction gear 30 by way of a torque-splitting reduction gear 301, which has an input driven sun 306, a ring 302 fast with the turbine T1 and a carrier 304 fast with the sun 25 of the reduction gear 30. In another modification the torque converter turbine T1 has two sets of blades, the second set being interposed between the pump P and reactor S, and the neutral clutch 26 is engaged by pressure supplied to the chamber 82 and disengaged by the converter pressure. In this case the turbine T2 is fixed axially and the clutch member 77 is axially slidable. The control system is suitably modified and provides for increased supply through line 191 to the converter when the solenoid valve 211 is actuated to ensure disengagement of the direct drive clutch 28 and the neutral clutch 26 which are both disengaged by the converter pressure. In the modification shown in Fig. 11 the second turbine T2, instead of being connected to the output shaft 27 by the clutch 26, is connected to the ring gear 289 of a reduction gear 291 having an output carrier and a reaction sun 294 which can be stationed by a brake 297 to give reduced drive from turbine T2 to the output shaft 27, or can be locked solid by a clutch 298 between the sun and carrier to give direct drive between the turbine T2 and the output shaft. In this embodiment the control system is similar to that shown in Figs. 4-6, the brake 297 and clutch 298 being controlled by the second turbine clutch line 244, both being spring-applied and pressurereleased, the liquid being selectively applied to the brake and clutch by an additional manual valve. When the clutch 28 is engaged the brake 297 must be released, and the control pressure in line 171 which engages the direct drive clutch 28 acts on the manual valve to ensure that it is not in the position to engage the brake 297. A simplified version of this modification dispenses with the lock-up clutch 298, and the brake 297 acts on the sun 294 through a one-way clutch to prevent reverse rotation of the sun.