Patent GB-1039890-A (GB)
Title: Automatic change speed transmission
IPC: F16H59/40
Filed: 1964-05-01
Abstract: 1,039,890. Change-speed gear and control; friction clutches. FORD MOTOR CO. Ltd. May 1, 1964 [May 3, 1963], No. 18304/64. Headings F2C and F2D. A change-speed gear for a motor car has its ratios established by two hydraulically-operated servos, one of which is double-acting, a control circuit connecting the two servos and including shift valves also including a time-delay valve, subjected to an hydraulic pressure dependent upon inlet manifold depression and to an opposed pressure developed in both servos, to control the rate of engagement of the first servo. Function summary.-A pressure regulator valve 308, subjected to secondary throttle (TV) pressure modulation, reverse boost modulation, and high output speed reduction, supplies main pressure 300 to 1-2 and 2-3 shift valves 482, 616, themselves subjected to opposed output speed pressure and TV boosted pressure. An engine suction servo 586 supplies primary TV pressure, reduced by a secondary TV valve 558 and boosted by a valve 544. A " back-out " time delay valve 646 controls the rate of engagement of a direct drive clutch and disengagement of a second ratio brake during 2-3 upshifts in dependence upon primary TV pressure. The D2 position of a manual ratio-range selector valve 364 enforces second ratio starts, and in its L position holds first ratio. A " kickdown " shift valve 664 enforces downshifts upon accelerator pedal overdepression. Gearing.-The turbine 74 of an hydrodynamic torque converter, connected to the motor car engine, drives through a shaft 86 to an hydraulically controlled multi-disc clutch 146 which is engaged to establish first ratio, drive then passing to a ring gear 176 meshed by planet pinions 178 on a carrier 184 splined to an output shaft 190, the planet pinions 178 meshing a freely journalled long sun gear 192 also meshed by planet pinions 204 in a carrier 210 now held against rotation by a one-way detent 250, the planet pinions 204 meshing a ring gear 218 also splined to the output shaft 190. A multi-wrap band brake 216, in parallel with the one-way detent 250, can be simultaneously applied to station the carrier 210, so as to permit engine braking on over-run. To establish a second ratio, a band brake 142 is applied to a drum connected to the sun gear 192, and the one-way detent 250 over-runs. Third ratio (direct drive) is established by disengaging the band brake 142 and instead engaging a second, hydraulically controlled multi-disc clutch 126, together with the clutch 146, to lock-up the gearing. Reverse is obtained with the band brake 216 applied to station the carrier 210 and the clutch 126 engaged to transmit drive to the sun gear 192. Friction clutches.-The clutch 126 is engaged when oil under pressure is admitted to a servo cylinder containing a ring-shaped piston 118, moved in the clutch-engaging direction against the bias of compression springs 120. The clutch 146 is engaged when liquid under pressure is admitted to a servo cylinder containing a ring-shaped piston 162 which acts through the leverage of a Belleville spring 158 upon the clutch pressure plate. Pressure regulator valve.-A front pump 56, Fig. 2, draws oil through the usual filter from a sump and passes it through a pipe 326 to a pressure regulator valve 308 which is pressure-opened to a sump return passage 324 against spring bias, thus providing regulated main pressure in a pipe 300 for application to the servos controlling the ratio establishing clutches and brakes. Regulated main pressure 300 is increased by secondary TV pressure applied through a pipe 358 to a piston 350 actuating the pressure regulator valve 308, and by pressure applied through a pipe 356 to the piston 350 when reverse is established. Regulated main pressure 300 is supplied through pipes 396, 398 to a manual ratio-range selector valve 364 having the usual P, R, N, D2, D1, L positions. The pressure regulator valve controls admission of regulated pressure through a pipe 330 to the torque converter 74, &c., and to rear and front lubricating pipes 342, 338, spring-biased valves being arranged to maintain the converter full when the engine is stationary. To modulate main pressure 300 when the car is running at speed, output speed dependent governor pressure 504 (see below) is applied to open a " cutback " valve 672 to a pipe 680, so that main pressure 300 is fed thereto from a pipe 554, and thence to a line reducer valve 688 through which reduced pressure is fed to a pipe 694, in order to apply bias to the regulator valve 308. TV pressure.-The engine-manifold-depression actuated diaphragm servo 586 controls a primary throttle valve 572 to admit main regulated pressure 300 to a pipe 570 feeding a secondary throttle valve 558. Primary TV pressure 570 is then reduced by the secondary throttle valve 558, and is passed to a pipe 556 in turn feeding a throttle booster valve 554. Main regulated pressure 300 is fed through a pipe 552 to the throttle booster valve 544, the final boosted TV pressure being fed through pipes 540, 630 to the 1-2 and 2-3 shift valves 482, 496, respectively. Reverse.-By moving the manual ratiorange selector valve 364 to its R position, main pressure 300 is connected through a pipe 400 to the pipe 356, the latter acting to boost the main pressure, as described above. The pipe 356 also connects through the 2-3 shift valves 616 with a pipe 404, 140 leading to the front clutch 146, which is accordingly engaged. The pipe 404 also feeds the disengaged side of a double-acting second ratio servo 410 controlling the band brake 142, normally spring disengaged. The apply side of the servo 410 is now vented to sump through a 2-3 back-out valve 646, a three-way valve 422 and a pipe 418. The pipe 400 also feeds through the 1-2 shift valve 482 to a pipe 432 feeding a servo 434 energizing the rear band brake 216. Drive range.-When the ratio-range selector valve 364 is slidden to its D1 position, main pressure 300 is connected to two pipes 474, 476, the former feeding through the pipes 170 to the servo engaging the clutch 146, and also through a pipe 478 to the 1-2 shift valve 482. At the same time the other clutch 126 and the two band brakes 142, 216 are disengaged. First ratio is accordingly established, the oneway detent 250 then taking the reaction of the second planet carrier. Main regulated pressure 300 in the pipe 474 is also fed to an outputspeed-responsive governor 266 having secondary and main valve spools 522, 510 connected in series by a pipe 518. At low speeds the secondary valve spool 522 is in its closed position, increasing speed opening this valve to supply a modulated pressure to the main valve spool 510, and thence to a pipe 504 leading to the 1-2 shift valve 482 and the 2-3 shift valve 616. The governor pressure in the pipe 504 ultimately increases to move the 1-2 shift valve spool downwards against spring bias, against the bias of TV pressure supplied through a pipe 496 and against regulated main pressure 300 supplied through the pipe 474 so differential area lands on the shift valve spool 482. Main pressure in the pipe 474 now passes through the pipe 478 to a pipe 428, through the three-way valve 422 to a pipe 416, through a pipe 414 and a restriction to the double-acting servo 410 for engagement of the band brake 142, thus stationing the double sun gear and establishing second ratio. With further increasing speed and increasing governor pressure 504, the 2-3 shift valve 616 is moved downwards against spring and TV pressure bias, thus connecting main pressure 300 in the pipe 476 through the 2-3 shift valve to a pipe 404 and a 3-2 " coasting " time delay valve 640, and thence to a pipe 408. The pipe 404 is connected directly to the servo of the clutch 126, which engages to lock-up the gearing for direct drive, and the pipe 408 leads to the disengaged side of the doubleacting servo 410, releasing the brake 142 stationing the sun gear. With decreasing speed, the 2-3 shift valve 616 is restored to its second speed position, connecting the pipe 404 to the pipe 356 and thence to sump. The 3-2 coasting time delay valve 640 is biased by governor pressure 504 to open at high speeds and by-pass a restriction 406 between the pipes 404, 408. If a 3-2 downshift takes place at a relatively high speed with the motor car coasting, the 3-2 coasting time delay valve 640 is held open and the restriction 406 is by-passed, so that the downshift takes place rapidly; if, however, the 3-2 downshift takes place at a lower speed, the 3-2 time delay valve 640 has already closed and the direct drive clutch servo is vented more slowly through the restriction 406, so that the second ratio band brake 142 is applied both slowly and gently. 2-3 upshift is cushioned by the 2-3 " back-out " time delay valve 646, opened by increasing pressure in the pipe 404 feeding the direct-drive clutch servo against spring bias and primary TV pressure 570 to connect the pipe 404 through the pipe 414 with the engage side of the double-acting brake servo 410; pressure fed through the pipe 408 to the disengage side of the servo 410 overcomes the engaging pressure, and the brake 142 is maintained released. However, opening of the 2-3 time delay valve 646 under these circumstances delays build-up of pressure in the direct drive clutch servo, and the direct drive clutch 126 does not engage until the brake band 142 is released. If the 2-3 upshift instead takes place when the primary TV pressure is high, the 2-3 back-out time delay valve 646 remains closed and the direct drive clutch 126 is engaged before the brake 142 is fully disengaged, thus preventing partial disestablishment of both ratios under heavy load. When the ratio-range selector valve 364 is slidden to its D2 position, main regulated pressure 300 is fed directly to the pipe 418, and through the three-way valve 422 to the pipe 416, for energization of the second ratio brake 142. A single automatic upshift alone is then