Patent GB-1079693-A (GB)
Title: Automatic change-speed transmission
IPC: F16H61/00
Filed: 1965-08-06
Abstract: 1,079,693. Change-speed control. FORD MOTOR CO. Ltd. Aug. 6, 1965 [Aug. 17, 1964], No. 33728/65. Heading F2D. An automatic transmission comprises a valve arrangement 744, 706, 764 producing a pressure signal to act in a pressure regulating valve 308, controlling pressure in a supply line, for servomotors controlling friction devices to establish different ratios in an epicyclic gear, to increase supply line pressure with increase in engine induction pressure for a given position of an engine throttle valve and to decrease the supply pressure for a given induction pressure with opening movement of the throttle valve within a range of throttle positions. General.-The gear, Fig. 1, not shown, comprises two planetary gears 44, 46 with a common sun 58; the input shaft 28 from a torque converter 18 may be clutched to the sun 58 or ring 42 of planetary gear 44 and the output shaft 62 may be driven from the carrier 50 of gear 44 and/or the ring 48 of the gear 46. A one-way brake 68 on carrier 52 of gear 46 may be bridged by brake 64. For low speed, clutch 32 is engaged and drive is via clutch 32, ring 42, carrier 50, sun 58 and ring 48, the carrier 52 acting as a reaction member, so producing split torque drive via carrier 50 and ring 48 to shaft 62. In intermediate, brake 38 is engaged to anchor sun 58, carrier 50 and the shaft 62 being driven at increase speed ratio with one-way brake 68 freewheeling. In third or direct drive ratio, brake 38 is released and clutches 36, 32 engaged to connect sun 58 and ring 42 to rotate the planetary elements in unison. Reverse is obtained by releasing brake 38 and clutch 32 and engaging brake 64 and clutch 36, drive being through shell 60 and sun 58, the carrier 52 being held whereby ring 48 is driven in reverse at reduced speed. For continuous operation in low speed, brake 64 and clutch 32 are applied and brake 38 and clutch 36 released, carrier 52 being prevented from rotation and accommodates coast braking reaction torque when shaft 62 over-runs the shaft 28. Control system.-A front pump, Fig. 2, supplies pressure to main line 300. A main regulator valve 308 prevents flow to converter 18 via line 330 until pressure in main line 300 is sufficient to move spool 310 against spring 322; then a land 316 uncovers passage 330 before uncovering an exhaust port 328 whereby pressure in line 300 is regulated. Fluid returns from the converter via passage 332, cooler 336 and rear lubricating passage 338, a front lubricating passage 342 being supplied via valve 340 which with valve 334 maintains the converter full when the engine stops. A shuttle 350 can move spool 310 upwards to increase the main line pressure. A manual valve 364, Fig. 4, has a grooved control element 366 movable to positions P, R, N, D2, D1, L corresponding to park, reverse, neutral, second drive range, first drive range and low speed and is shown in neutral wherein land 392 blocks passage 396 which is connected to the main line 300. A primary governor valve, Fig. 4, has a spool 506 in chamber 516 connected via passage 518 with chamber 520 of a secondary valve. A passage 474 which is connected to main line passage 398, 300 when the manual valve is in the D1, D2 positions, is connected to chamber 520 and the pressure urges a valve spool 524 radially inwardly to pressurize passage 518 from passage 474 to urge spool 506 radially inwardly to interrupt the connection between passages 504 and 518. The spools 506, 524 are moved inwardly against springs and centrifugal action; thus at low speed no pressure is communicated to passage 504 which is vented via port 532. At a predetermined speed a modulated pressure is produced in passage 518 and in passage 504 to act on the 1-2 and 2-3 shift valves.  TV pressures.-The following TV pressures are effective for the functions stated. Primary TV pressure is metered into a line 570 from the pressure main 300 in accordance with engine manifold depression acting on a diaphragm 588. In the shift control valve system this primary TV pressure 570 acts only on a 2-3 back-out valve 646 which regulates the rate of engagement of the high-speed clutch during a 2-3 upshift as described below. TV pressure for loading the shift valves and hence determining shift speeds is required to be responsive to torque demand rather than to the actual torque produced as measured by primary TV pressure, which latter, for this purpose, is processed as follows. Primary TV pressure 570 is metered in a secondary throttle valve 560 into a line 556 in which secondary TV pressure is lower, but has a steeper characteristic (Fig. 5, not shown) than primary TV570. Secondary TV pressure 556 passes into a shift-valve control line 540 through a throttle booster valve 544, which leaves secondary TV pressure 540 unmodified until it reaches a predetermined value, whereupon a booster-valve spring 550 yields and permits the booster valve to meter line pressure 300 into the control pressure line 540 which now supplies boosted TV pressure with a steeper characteristic (Fig. 5, not shown). Boosted TV pressure 540, before loading the shift valves, is further trimmed in a throttle modulator valve 536 at the base of the 2-3 shift valve. TV pressure for loading the main regulator valve for control of servo pressure requires a different characteristic, provided by the combined effect of primary TV pressure, a mechanical TV valve, a boost control valve and a boost control amplifier valve functioning solely for this purpose, and forming the main subjectmatter of the invention. The spool 744 of the boost-control valve is loaded downwards by primary TV pressure 570, 704, and upwards by its own delivery pressure 758 acting in the hollow bore of the valve-spool, together with pressure 740 supplied by the mechanical TV valve 706 actuated by mechanical linkage 730 from the engine throttle and including a lost-motion and spring connection acting as follows to meter line pressure 300 into the mechanical TV pressure line 740. Over the range zero-20 degrees throttle opening the linkage merely absorbs lost motion and mechanical TV pressure is zero; over a range 20 to 50 degrees the throttle linkage shifts the valve abutment 706 to load the valve spool 714 and meter a gradually increasing pressure into the mechanical TV line 740; above 50 degrees there is no further increase. Thus the delivery line 758 of the boost control valve carries a pressure which, although responsive to primary TV pressure 570, 704, has the degree of response progressively reduced for increasing throttle openings in the 20 to 50 degree range. Boostcontrol valve delivery pressure 758 passes to the main pressure regulator valve through an amplifier valve 764 which leaves the pressure unmodified until it reaches a predetermined value whereupon the amplifier valve-spring yields, and causes the amplifier valve to meter additional pressure from the main line 300 into the delivery line 700. Pressure in the line 700 now increases more steeply but is still responsive to primary TV pressure. The amplifier valve 764 is rendered inoperative in reverse by reverse pressure supplied from the manual valve to a line 784. Operation. Reverse.-The control element 366 connects main line passage 398 to passage 400 and to passage 356 to act on shuttle 350 to augment spring 322 to produce a higher main line pressure to increase the capacity of clutch 36 and brake 64. The increased pressure passes from line 356 via orifice 402, Fig. 3, 2-3 shift valve and passage 404 to the clutch 36 and passage 400, 1-2 shift valve and passage 432 to brake 64; fluid also passes from passage 404 through orifice 406 to passage 408, Fig. 2, to the servo 410 to augment spring 412 to release the brake 38. Manual valve to first drive range D1.-The passages 356 and 400 are exhausted to the righthand side of the valve chamber, main line passage 398 is connected through recess 376 to passages 474, 476; and passage 418 is vented to the left-hand side. Passage 474 distributes control pressure directly to forward clutch 30 via passage 478 and also to 1-2 shift valve, Fig. 2, to raise spool 482 to the shown position wherein passages 400 and 432 are connected to exhaust the servo 434 of brake 64. A signal from a vehicle speed governor acts on land 484 of 1-2 shift valve through passage 504 and boosted TV pressure 540 acts on a plunger 536 in the 2-3 shift valve, Fig. 3, against spring 538 to determine pressure in a passage 496 which acts on a spool 482 of 1-2 shift valve to augment spring 500 and line pressure acting between lands 490 and 492. When governor pressure in passage 504 overcomes these forces, the spool 482 moves down in a snap action due to venting of the chamber between the lands 490, 492. In this upshift position, passages 494, 432 and hence servo 434 of brake 64 are vented through port 430 and passages 428, 474 are connected so that main line pressure flows from the manual valve through passages 474, 428, valve 422 to passage 416, 2-3 back-out valve, and passage 414 to servo 460 of brake 38 to anchor the suns and establish intermediate drive range. When governor pressure reaches a sufficiently high value the spool 616 of 2-3 shift valve is moved down so that passages 476, 404 are interconnected through passage 626, line pressure passing through passage 404 to 3-2 coasting control valve, Fig. 2, to direct clutch 36 and to passage 408 to release brake 38; both clutches are now engaged and both brakes disengaged for direct drive. At a predetermined vehicle speed the governor pressure acting via passage 504 moves spool 636 of 3-2 coasting valve upward to directly connect passages 404 and 408 and by-pass through restriction 406. To cushion application of the direct drive clutch 36, the land 648 of the 2-3 back-out valve is subject to pressure in passage 404 and the valve assumes the shown position; on shift to direct drive the pressure in passage 404 initially increases and at a prede