Patent GB-889344-A (GB)
Title: Improvements relating to the control of torque transmission systems
IPC: F16H47/08
Filed: 1959-11-02
Abstract: 889,344. Change-speed gear and control. GENERAL MOTORS CORPORATION. Nov. 2, 1959 [Nov. 6, 1958], No. 37094/59. Class 80 (2). [Also in Groups XXVIII and XXXIV] In a combined torque converter and planet gear in an automobile, between an input shaft 10 and an output shaft 14, wherein hydrodynamic braking is obtained between a turbine 22, overdriven by the output shaft through the planet gear, and an engine-connected impeller 20, the hydrodynamic braking is supplemented by braking the engine by a fluid-pressure engaged friction device 16 which serves as a clutch in a split-torque forward drive approaching 1/1 ratio and which, for engine braking, exerts a braking force dependent on output shaft speed. Function summary.-A manual selector valve has five settings P(park), N(neutral), D(drive) which provides forward reduced drive through the torque converter followed automatically by engagement of the friction device 16 in response to opposed output governor and TV (throttle variable) pressure for split-torque drive approaching 1/1 ratio, L(two-way low), and R(reverse). Torque converter and gear arrangement.-The torque converter comprises the impeller 20, the turbine 22 and a reactor 24 reacting on a one-way detent 42 braked by fluid-pressure at 40. The gear comprises long planets 30 in an output carrier 32 meshing a ring gear 26 connected to the turbine 22 and equal suns 36, 34 which latter sun reacts, for forward reduced drive through the converter, on a one-way detent 44 also braked at 40. The friction device 16 is fluid-pressure engaged, preferably at converter coupling point, to clutch the input shaft 10 to the sun 36 for split-torque drive approaching 1/1 ratio, the one-way detent 44 permitting forward rotation of the sun 34. For reverse, the turbine 22 and ring 26 are braked by fluid-pressure at 52, a fluid-pressure actuated clutch 48 by-passing the detent 44 is engaged, and the brake 40 and the friction device 16 are released so that the reactor 24 rotates reversely and drives the released sun 34 through the detent 42 and the clutch 48. The clutch 48 also provides two-way low by connecting the sun 34 to the engaged brake 40 thereby preventing rotation of the sun 34 in either direction; with the output shaft 14 driving hydrodynamic braking is then obtained between the turbine 22 overdriven by the ring gear 26 and the engine connector impeller 20; in addition, the hydrodynamic braking may be supplemented by retarding the engine by variably engaging the friction device 16 which acts as a slippable brake between the impeller 20 and the stationary sun 36. The one-way detents may be of the sprag or roller type. Fluid supply system.-Input and outputdriven pumps 56, 58 supply a system pressure main 70. The rear pump 58 comprising a piston 82 which incorporates a spring-loaded check valve 92 and is depressed towards an intake screen 112 against springs 86, 88 by an output driven cam 90 supplies the main 70, during push starting only, through a check valve 118. An output pump by-pass valve 120 is provided so that a predetermined line pressure, say 28 pounds per square inch, it delivers this pressure to the upper face of the pump piston 82 to render the output pump inoperative and non-power consuming. The vane or gear-type input pump 56 which is provided with an intake screen 66, supplies the main 70 which is provided with a relief valve 74, a secondary line 68 feeding the main 70 from the pump 56 through a check valve 72 to provide the initial fluid volume required. Fluid system components include: a pressure regulating valve 60; the manual PNDLR selector valve 126; TV(throttle variable) and detent valves 142 and 144 in which the detent valve 144 is moved against spring resistance by an accelerator pedal connected cam lever 158 and the force resulting from the throttle opening movement is transferred through a spring 164 to the TV valve 142 which regulates pressure proportional to throttle position; a dual-rate governor valve 188 which is actuated through an adjustable lever 202 by a centrifugal governor 194 on the output shaft so as to regulate a pressure proportional to output shaft speed, which pressure increases at a relatively fast rate for slow speeds say up to 15 m.p.h. and at a relatively slow rate for speeds say above 15 m.p.h.; a torque converter pressure-regulating valve 226 which is influenced in a pressure increasing direction by main line pressure; a lube pressure regulating valve 254; a shift valve 272 which is subject to opposing output governor and TV pressures and acts with a snap-action for both up and down shifts; a vacuum-governor modulator valve 298 supplying to the pressure regulating valve 60 a pressure reflective of output governor pressure and engine vacuum; two braking pressure regulating valves 322, 340, or a single braking valve (Fig. 7, not shown), regulating pressure in response to output governor pressure ; and shuttle valves 372, 382 respectively in the servo feed lines of the friction device 16 and the clutch 48, each shuttle valve having three ports and being so arranged that the port connected to exhaust will close. Operation,-With the engine started, pressurefluid is supplied to the pressure regulating valve 60 which is loaded by a spring 366, vacuum and governor modulated pressure via a line 320 and, in opposition, for reduced pressure in forward drive, main line pressure through a line 370. Firstly, main line pressure is supplied through a line 190 feeding the converter regulating valve 226, the governor valve 188 and the lube pressure regulating valve 254. When line 190 pressure equals main line pressure the pressure regulating valve 60 moves further until the secondary line 68 is relieved through the suction line 64. Finally, the valve 60 moves further to relieve excess main line pressure through the suction line 64. In Park(P) or Neutral(N) setting the manual valve 126 blanks the main line 70. In Park(P) setting a suitable mechanism, not shown, prevents output shaft rotation. In Drive(D) the manual valve 126 opens the main line to the TV valve 142 through a line 140, to the shift valve 272 through an inlet line 292 and, for forward reduced drive through the converter, to the brake 40 through the line 370, which line pressure also acts on the valve 60 to give a reduced line pressure adequate for Drive range operation. As governor pressure increases the main line pressure decreases due to the action of the modulated pressure in the line 320. When, between 20 and 65 m.p.h., the relationship between TV pressure through a line 166 and governor pressure through a line 192 and a branch 288 is sufficient to cause the shift valve 272 to upshift, main line pressure is opened to the friction device 16 through lines 292, 294, shuttle valve 372 and line 376, the servo of the friction device 16 being actuated against converter charging pressure. In order to reduce converter pressure during the splittorque drive the pressure in a branch 378 of the line 376 acts to eliminate the pressure increasing influence of main line pressure, through branches 250, 251, on the converter pressure regulating valve 226. Downshift may be effected during Drive range by (a) " detent," (b) " forced," (c) manual and (d) closed throttle. (a) " Detent " downshift is produced below say 63 m.p.h. by full accelerator pedal depression. At a point preferably coinciding with the position of full throttle opening an additional spring 186 is felt so that the driver may know that if downshift has not yet occurred further accelerator depression will induce downshift. With the detent valve 144 in the downshift position TV pressure from a branch 187 is opened to the shift valve 272 through a further line 172, the TV pressure being made equal to line pressure by consequential movement of the TV valve 142. Below 63 m.p.h. the pressures in lines 166 and 172 are sufficient to overcome governor pressure and downshift the shift valve 272 and block communication between lines 292, 294 which latter is exhausted through 296. (b) " Forced " downshift is produced with the accelerator pedal at, or short of, detent position, when proceeding forward at speeds less than 63 m.p.h., when TV pressure through the line 166 is sufficient to overcome governor pressure. (c) Manual downshift.-By moving the manual valve 126 to " L " communication between the main line 70 and the shift valve inlet line 292 is blocked, the latter being drained through the open end of the valve 126. (d) Closed throttle downshift occurs automatically below say 10 m.p.h., when governor pressure is insufficient to maintain the shift valve 272 in the upshift position against springs 280, 282. Low range (Driving).-In " L " setting, with the engine driving and throttle removed from the closed position, the manual valve 126 exhausts the line 292 so that the shift valve 272 is unable to produce an upshift, the forward brake 40 is still energized through the line 370 the pressure in which is also transferred to a braking pressure feed line 176 and thence, via a line 380, the shuttle valve 382 and a line 384, to the clutch 48, the line 176 being blocked at the detent valve 144 and a line 386 from the shuttle valve 382 being exhausted. As mentioned the clutch 48 affords overrun braking through the planet gear. Low range (Coast).-In " L " setting with the throttle closed pressure is also connected to the friction device 16 through the line 176, the detent valve 144, the line 178, the two braking pressure regulating valves 322, 340 shown, or the single braking valve (Fig. 7, not shown), a line 352, shuttle valve 372 and line 376, the line 294 being exhausted. The braking pressure regulating valves or valve are arranged so that braking pressure is blocked above 40 m.p.h.; as the speed drops to between 40 and 25 m.p.h. the braking pressure will increase as the speed decreases thereby engaging the friction device 16 with a steadily increasing pressure; an