Patent GB-1130764-A (GB)
Title: Automatic transmission for a motor vehicle
IPC: F16H47/08
Filed: 1966-06-07
Abstract: 1,130,764. Change-speed gear and control. FORD MOTOR CO. Ltd. 7 June, 1966 [9 June, 1965], No. 25312/66. Heading F2D. In a vehicle change-speed planetary gear giving three forward gears and reverse which are selectively engaged by hydraulically-actuated brakes 58, 94 and clutches 80, 86 controlled by automatic shift valves 200, 202 which respectively control 1-2 and 2-3 gear-shifts in accordance with opposing signal pressures responsive to vehicle speed (sensed by a governor 76) and engine inlet manifold depression and a manually operable ranging valve 168 controlling servo-pressure distribution from a regulator valve 114 to the shift valves, the governor pressure 368 acts on a transition valve 396 to block the supply of governor pressure 368 to the shift valve governor line 226 when the governor pressure is below a predetermined level, but opens the shift valve line 226 to governor pressure 368 when the governor pressure is above the predetermined level. The calibration of the automatic shift valves 200, 202 is such that during acceleration from rest the 1-2 upshift occurs immediately the transition valve 396 supplies governor pressure through the line 226 to the shift valves to depress the 1-2 shift valve 200. Thus the shift points for the 1-2 upshift and 2-1 coasting downshift (at a lower speed) are determined by the transition valve 396 alone and not by the automatic shift valves. The latter can thus be calibrated to provide better quality for the remaining shifts without regard to that of the 1-2 and coasting 2-1 shifts. Function Summary.-The manual selector valve 168 has five settings. Reverse, neutral, two drive settings D2, D1 and low. In low, the gear is locked in first, while Drive, D1 allows one-way first gear start with automatic shifts between the three forward gears, and Drive D2, allows second gear start and one automatic upshift to third gear. 3-2 and 2-1 accelerator kick-downshift is provided below predetermined speeds in the Drive range. Servo pressure is regulated in accordance with a pressure derived from engine manifold depression (T.V. pressure) and is reduced prior to a 1-2 upshift drive acceleration from a standing start. In Reverse the servo pressure is increased. At small throttle openings the 3-2 downshift is smoothed by a valve 412. Gear arrangement.-The engine drives the gear input shaft 36 through a torque converter 24. The gear comprises two planetary tracks 38, 40, having a common sun 48 and an output shaft 74 drivingly connected to the planet carrier 44 of the train 38 and the ring gear 50 of the train 40. For two-way compounded first gear in low range, a clutch 80 connects the ring gear 42 of the train 38 to the input shaft 36, and a brake 58 is applied to the planet carrier 52 of the train 40. For one-way first in Drive (D2) range, clutch 80 is engaged and the planet carrier 52 is held from reverse rotation by a one-way detent 228. For second, using the, train 38 alone, the clutch 80 remains engaged, and the sun 48 is held by applying a brake 94. For direct drive third, clutches 80, 86 clutch the ring gear 42 and sun 48 to the input shaft to lock the train 38. For reverse, using the train 40 along the drives the sun 48, and the planet carrier 52 is held by the brake 58. Brakes and clutches.-Brakes 58, 94 are servo applied band brakes. Clutches 80, 86 are servo applied multi-plate friction clutches. Fluid pressure supply and regulation.-The pressure regulator valve 114, which is fed by an engine-driven pump 106 only supplies oi l  through a line 146 to the torque converter and regulates the servo-pressure in lines 108, 162 and 164 in accordance with T.V. pressure in a line 152. Pressure in a line 148, connected, through a cutback control valve 358 opened when governor pressure 368 exceeds a predetermined value to the servo line to the clutch 80, acts on the spool of the regulator valve 114 to reduce servo pressure prior to a 1-2 upshift during acceleration from a standing start, while in Reverse setting of the manual valve 168 pressure in a line 150 acts on the spool 114 to increase the servo pressure. Shift control pressures.-(1) T.V. pressure 284, 152 is derived from line pressure by a T.V. valve 272 loaded by a vacuum servo-motor 288 connected to engine intake manifold pressure. T.V. pressure 284 reaches 1-2, 2-3 shift valves 200, 202 through a line 266 and a boost valve 298 which at low throttle openings feeds unmodified T.V. pressure 284, but increasing T.V. pressure moves the boost valve spool leftwards to supply line pressure 312 to line 266 to provide at large throttle openings an increased T.V. pressure more closely resembling the actual engine torque demand. T.V. pressure reaches the 1-2 shift valve 200 through a reducing valve 258, below the 2-3 shift valve 202, and feeding a line 230 in which pressure is progressively reduced as the boosted T.V. pressure 266 increases. (2) Governor pressure. An output-driven governor valve 76 provides a two-stage centrifugal control of exhaust from a line 368, 392 which is fed with servo pressure 194, 410 from the first speed clutch 80 through two restrictors 412, 414 in series. The governor pressure retained in the line 368, 392 following these restrictors is determined by the degree of exhaust to outlets 384, 386 established by two centrifugal ball valves sealing orifices leading from a common pressure chamber 390, one ball 376 unloaded, the second and smaller ball 378 being loaded by a spring which is overcome by governor pressure at a predetermined speed to modify the pressure characteristic. The supply of governor pressure 392, 368 to the shift valves 200, 202, as well as an augmenting of governor pressure at high speeds are controlled by the transition valve 396, which at low speeds is shifted left by a spring to cut off communication of governor pressure 368 from a governor pressure line 226 leading to the shift valves. At a predetermined speed, governor pressure 368 shifts the transition valve right to supply governor pressure to the shift valve line 226 for normal control. At high speeds the valve shifts further right to by-pass the second governor-supply restrictor 414 thus augmenting governor pressure. Shift valves.-The spool of the 1-2 shift valve 200 is urged downwards against T.V. pressure 230 and a spring 220 by governor pressure 226 to a position connecting servo pressure 234 to the line 232 to apply the brake 94 to engage second gear; unless the manual valve 168 is in the D2 position. The spool of the 2-3 shift valve 400 is urged downwards against T.V. pressure 266 and a spring 254 by governor pressure 226 to a position connecting servo pressure 192 to a line 262 to engage the clutch 86 for third gear, and to release brake 94. A 3-2 coasting control valve 412 acted on by T.V. pressure 440 against a spring 416, provides a delay and cushioning of engagement of the second ratio band-brake on a 3-2 down-shift by connecting the release line 418 of the intermediate servo to the exhausted clutch line 262 either through a restrictor 420 for delayed engagement or directly at high T.V. pressure for rapid engagement. Operation-Nentral.-The manual selector valve 168 closes the servo pressure lines 162, 164 and all brakes and clutches are disengaged. Drive.-D1 setting of the selector valve 168 admits pressure to lines 192 and 194 and the clutch 80 alone is engaged. Start is made in one way first gear with the planet carrier 52 reacting on the one way detent 62. On accelerate ing rising governor pressure 392 overcomes spring 404 in the transition valve 396 and passes to line 226 to move immediately the spool 204 of the 1-2 shift valve 200 downwards to admit servo pressure 234 into line 232 to engage the brake 94 for second gear. A further speed increase causes governor pressure 226 to move the spool of the 243 shift valve 202 downwards to admit servo pressure 192 to the line 262 to engage the clutch 86 and release the brake 94 for third gear. Kick down shift is by a downshift detent valve 313 actuated when the acceleration pedal is fully depressed to admit servo-pressure from the line 340 via a limit valve 328 to a line 268 to move the shift valves 200, 202 into their lower gear positions provided that the governor pressure is low enough. The spool of the limit valve is loaded leftwards by a spring 336 and T.V. pressure, and leftwards by the output pressure of the valve, to regulate said output pressure in accordance with T.V. pressure. .. D2 setting of the selector valve 168 admits pressure to lines 190, 192 and 194 to engage clutch 80 and brake 94. Start is made in second gear and increasing vehicle speed results in ore automatic 203 upshift to third gear. Low setting of the selector valve 168 admits servo pressure to line 194 to engage the clutch 80 and to line 196 to engage the brake 58. Shift valve 200 allows the engagement of the brake 58 to give two-way low only when the governor pressure is low enough to allow the valve spool to be in the upper position, but once servo-pressure is admitted to the line 224 it locks the spool in this position. Reverse setting of the valve 168 admits pressure to line 198 to increase servo pressure and to apply clutch 86, and to line 196 to apply brake 58.