Patent GB-883879-A (GB)
Title: Improvements in and relating to hydrodynamic transmissions
IPC: F16H61/62
Filed: 1960-02-10
Abstract: 883,879. Change-speed gear. GENERAL MOTORS CORPORATION. Feb. 10, 1960 [Feb. 24, 1959], No. 4659/60. Class 80 (2). [Also in Group XXIX] An hydrodynamic transmission comprises a lock-up clutch 11, Fig. 2, which can be automatically engaged by the pressure from a governor 159, Fig. 3, acting on a lock-up clutch valve 351, Fig. 6. The input shaft 17, Fig. 2, of the transmission is connected to the impeller 23 of a torque converter having a turbine 36, connected to a driven shaft 39, and reactors 41, 42 connected by one-way clutches 43, 44 to a stationary member 64 secured to the transmission casing 27. The driven shaft 39 is connected to a two-speed unit 14, Fig. 3, providing a direct drive and an over-drive, and a three-speed and reverse unit 16, Fig. 4, the arrangement being such that the transmission provides four forward speeds, neutral, and two reverse speeds. The turbine 36 of the converter may be locked to the impeller 23 by fluid pressure supplied to a chamber 58 moving a flexible plate 53 so that a friction member 51 of the lock-up clutch clamps a driven plate 46, secured to the turbine, to an abutment 49 fixed to the impeller casing. The two-speed unit 14 has a planet carrier 71 which is secured to the driven shaft 39 and carries planet gears 72 engaging a sun gear 73 and an internal gear 74 connected to an intermediate shaft 77. Fluid pressure supplied to a piston-and-cylinder device 81, 82 actuates clutch 84, 85 to connect the sun gear to the planet carrier to lock the unit 14 for direct drive, and fluid pressure supplied to a piston-and-cylinder device 94, 96 actuates a clutch 91 to hold the sun gear against rotation to position the unit for overdrive. The intermediate shaft 77 is connected to sun gears 111, 112 of the unit 16. Sun gear 111 meshes with pinions 116 on a carrier 117 secured to an output shaft 120, the pinions, in turn, meshing with an internal gear 121 which can be held against rotation by fluid pressure supplied to a piston-and-cylinder device 128, 129 actuating a clutch 123 to provide a low ratio transmission in the unit 16. The sun gear 112 meshes with pinions 133 on a carrier 134, the pinions also meshing with an internal gear 136 which can be held against rotation by fluid pressure supplied to a chamber 144 moving a piston 142 to engage a clutch 137 and provide an intermediate ratio transmission in the unit 16. The carrier 134 can be held against rotation to provide a high ratio drive by a clutch 151 which is actuated by fluid pressure supplied to a piston-and-cylinder device 152, 153. A planet carrier 168 in the unit 16 is splined to the output shaft 120 and carries pinions 167 meshing with a sun gear 169, connected to the carrier 134, and an internal gear 172 which can be held against rotation by a clutch 173 actuated by fluid pressure supplied to a piston-andcylinder device 178, 179 to provide a reverse drive. The intermediate shaft 77 is connected by a member 114 to the can 161 of the governor which is of the Pitot tube type, the can having a plurality of fins 162 which rotate fluid past the tube 163 leading to a line 216 connected to the lock-up clutch valve 351. An hydrodynamic brake 101 is arranged between the casing of the transmission and the intermediate shaft 77 and consists of a plurality of blade 103 which are formed on a plate 102 secured to the shaft 77 and co-operate with blades 106 on the casing, fluid to and from the brake being controlled by a valve 426. The fluid supply for operating the devices actuating the clutches and for the working circuit of the converter is provided by a pump 193 driven by a gear 32 connected to the impeller 23. The pressure of the fluid is regulated by a valve 196 which has a spool 197 which is moved to the left against a spring 203 to permit excess fluid to be discharged to a line 218 leading to the inlet to the converter. A line 214 is connected to a land c to reduce the pressure of the fluid when a manual selection valve 221 is moved to certain positions. In addition, the pressure in the line 216 connected to the governor also affects the pressure regulated by the valve in such a way that the main line pressure decreases with increase of transmission speed. The fluid is directed to the devices actuating the clutches by the valve 221 which can be manually moved to selected positions where it is retained by spring-pressed balls 226. When the valve 221 is moved to change the ratio of the drive, the fluid pressure to the devices actuating the respective clutches is controlled by a regulating valve 391, so that, initially, the pressure supplied to the selected device is low as determined by fluid from a line 331 connected to a chamber 401 at the righthand end of the valve moving a two-part spool 392, 393 to the left against a spring 394 and passing to an exhaust 403. Fluid, however, passes through an orifice 402 to a space between the parts which are gradually separated so that the spring 394 is further compressed and consequently the pressure in the line 333 gradually increases until the part 392 engages a stop 398. Thereafter, the part 393 moves to the right until the exhaust 403 is closed, the pressure in the line then rapidly increasing to a level sufficiently high to prevent slipping of the engaged clutch. When the change is between low ratio and intermediate ratio, the pressure to the devices actuating the respective clutches is also controlled by valves 451, 452 so that engagement of the clutches in these ratios is rapid and disengagement slow to ensure a smooth change over. The line 331 is also connected to a control valve 366 which is supplied with fluid pressure from a line 376 connected to a valve 381 which is manually operable to connect the line 376 to the Pitot tube 163 of the governor or the supply line 194 from the pump. When the selector valve 221 is actuated to change the ratio of the transmission, the spool of the valve 366 is moved to the left to disconnect the line 376 from a line 364 leading to the lock-up clutch valve and connect it to exhaust 378; at the same time, the line 364 is connected to exhaust 378 to prevent engagement of the lock-up clutch. When the pressure in the line 331 rises to its operative value, as controlled by the valve 391, the spool 367 of the valve 366 returns to its original position to connect the line 376 to the line 364 leading to the lock-up clutch valve. The pressure in line 364 acts on one end of the lock-up valve and when the pressure in this line reaches a predetermined value, moves the spool of the valve to the left to connect the main pressure line 194 from the pump to a line 354 leading to the chamber 58 and engage the lock-up clutch. The pressure in the line 354 also acts through a restriction on the spool of a valve 411 to connect the line 218 supplying fluid to the converter circuit to an exhaust 418 to reduce the pressure acting in the converter. The spool of the lock-up clutch normally moves only against the pressure of a spring 357 but where the selector valve 221 is moved to engage the overdrive transmission, the pressure in a line 341 leading to the device 94, 96 actuating the clutch 91, acts on a piston 358 in the lockup clutch valve to compress the spring and increase the spring pressure against which the spool moves. The exhaust line 432 from the converter is connected to a cooler 434 and a lubrication line 436 for the parts of the transmission, the resistance of the cooler and lubrication line maintaining the pressure in the converter. When the transmission is to be braked, the spool of the valve 426 is moved downwardly so that an exhaust line 429 from the hydrodynamic brake is connected to the cooler and lubrication line, and the converter inlet line 218 is connected to the inlet line 438 of the brake.