Patent GB-1010876-A (GB)
Title: Motor vehicle automatic transmission
IPC: F16H61/04
Filed: 1963-10-04
Abstract: 1,010,876. Change-speed control. FORD MOTOR CO. Ltd. Oct. 4, 1963 [Oct. 12, 1962], No. 39091/63. Heading F2D. A vehicle automatic transmission comprises an hydrodynamic torque converter followed by an epicyclic gear having hydraulically engaged ratio establishing clutches, and brakes supplied with servo pressure regulated in accordance with the inlet manifold depression of the vehicle engine, and being controlled so that for reverse drive the servo pressure is augmented. Gearing.-The gearing provides three forward speed ranges and reverse, and comprises a torque converter having a pump 22 connected to an input shaft, a reactor 26 mounted by means of a one-way brake 54, and a turbine 24 splined to a shaft 40 fast with the driving parts of a front clutch 64 and a rear clutch 66 the driven parts of which are respectively fast with sun gears 98, 100. The sun 98 meshes planet pinions 110 which intermesh with planets 106 which in turn mesh a ring gear 112 fast with an output shaft 14. The planets 106 are fast with planets 104 which mesh the sun gear 100, the planets being mounted in a carrier 120 which is stationable by a one-way brake 126 and by an hydraulically engaged brake 124. The sun 100 is stationable by an hydraulically-applied brake 92. The clutches 64, 66 are of the multi-plate type, clutch 64 being engaged by a piston 86 acting through a Bellveille spring 82, and the clutch 66 being engaged directly by a piston 90 against the pressure of a spring 94. Operating summary.-The gearing is controlled by an hydraulic system having a manual selector valve 178 having park P, reverse R, neutral N, drive 2 D2, drive 1 D1, and low L positions. In the D1 position three speed ranges are provided, the torque converter being filled throughout. For first speed the clutch 64 is engaged and the planet carrier is held by the one-way brake 126. As the output shaft speeds up the front brake 92 is applied to station the sun 100, the clutch 64 remaining engaged so that the second speed is obtained. Upon further increase in vehicle speed clutches 64, 66 are applied and the brake 92 disengaged. In the D2 position of the manual valve the gear is maintained in its second speed range, in the L position clutch 64 is engaged and brake 124 applied to station the planet carrier 120 to provide engine braking. Servo pressure supply and regulation.-Pressure is supplied by a front pump 60 driven by the input shaft and by a rear pump 130 driven by the output shaft 14 and is supplied through check valves to a main line 164 at a pressure regulated by a valve 134 which has a spool biased downwardly by a spring and biased upwardly by the main 164 pressure acting on a differential land 140 and by compensator pressure supplied through a line 314. The compensator pressure 314 is derived from the main pressure 164 through a compensator valve 292 which modulates the main pressure that is supplied to it from a passage 312 in accordance with governor pressure and TV (torque variable) pressure. The governor pressure is supplied through a line 306 by an output driven governor 132 and acts upon the right-hand end of a plunger 304 and upon the left-hand end of a plunger 298. The TV pressure acts upon the differential area between lands 288, 290 of the valve 292 and is supplied thereto through a passage 286 which communicates with the main passage 164 through a TV valve 274 which modulates the pressure in passage 286 in accordance with the inlet manifold depression by means of a vacuum servomotor 280. In the reverse R position of the manual selector valve 178 main pressure 164 is supplied to a passage 196 and acts upon differential areas of lands 276, 278 to modulate the TV pressure 286 and consequently modulate the compensator pressure 314 thereby reducing the upward bias on the regulator valve 134 and thus increasing the main pressure 164. Operation.-In the D1 setting of valve 178 liquid is distributed to the torque converter by the regulator valve 134, and main pressure 164 is supplied through a line 190 to a servo 166 to engage the front clutch 64 to give the low-speed range. One-two upshift.-The output driven governor 132 is urged centrifugally outwardly to open a passage 260 to main pressure 164 through passages 190, 204, the pressure in passage 260 acting to bias an inhibitor valve 224, a twothree shift valve 248 and a one-two shift valve 214 downwardly. As the pressure in passage 260 increases the one-two shift valve 214 is moved downwardly thereby blocking communication between a line 222 and a line 192 which is connected through the manual valve to main pressure 164 and opening the line 222 to exhaust 226. Line 222 communicates through the inhibitor valve 224 with a passage 236 biasing a valve spool 202 upwardly; when passage 236 is opened to exhaust the valve spool 202 moves downwardly under main pressure supplied through passages 190, 204 and main pressure is supplied through a line 212 to a servo 170 engaging the brake 92. Two three upshift.-With increasing governor pressure 260 the two-three shift valve 248 is moved downwardly thereby communicating a passage 188 which is supplied with main pressure with a passage 256 leading to a servo 168 engaging the rear clutch 66, the pressure in passage 256 also being applied through a threetwo kickdown control valve 368 to the release side of servomotor 170 to ensure the release of brake 92. Downshift.-A three-two coasting control valve 344 is provided to allow free exhaust of liquid from the release side of the front brake 92 servo 170 when the engine is delivering torque, and give restricted exhaust from the release side under coasting conditions to cushion the downshift. If the vehicle speed is greater than a desired value, the inhibitor valve 224 will move downwardly so that it is impossible to admit pressure to the lower end of the transition valve 202 or to the rear servomotor 172 for the rear brake 124. This prevents a forced downshift when the vehicle speed is higher than a safe value. A forced downshift can be obtained by means of a downshift valve 354 and is under the control of the vehicle throttle. If the throttle is fully opened the valve is actuated and communication is established between main pressure passage 312 and the passage 360 which extends to the inhibitor valve and the lower end of each of the shift valves. Forced downshift to either of the lower speed ratios can thus occur depending upon the vehicle speed at which the downshift is attempted. During a three-two kick-down shift the control valve 372 provides a greater restriction to exhaust of liquid from the release side of the servo 170 to provide a higher degree of overlap between clutch release and, brake engagement at high vehicle speeds than during low speed operation.