Patent GB-624858-A (GB)
Title: Improvements in or relating to variable-speed transmissions and control mechanisms therefor
IPC: F16H47/08
Filed: 1946-03-05
Abstract: 624,858. Hydraulic clutches. BORG - WARNER CORPORATION. March 5, 1946, No. 6777. Convention date, Jan. 9, 1942. [Class 69 (ii)] [Also in Group XXIV] In a series arrangement of hydraulic torque converter and epicyclic gearing, the converter and gearing reaction elements are connected to a common reaction means automatically released when the converter and gearing are byepassed by directdrive means. As shown applied to a motor vehicle, the engine fly-wheel 22, Fig. 2, is rigid with the impeller 23 of a hydraulic torque converter, the turbine 24 of which drives an intermediate shaft 15 to which is splined the interengaging planet carrier 37 of an epicyclic gear, the annulus 32 of which is mounted on a drum 33 connected to the output shaft 14. The reaction sun 34 and the converter reaction member 25 are connected, directly and through a one-way clutch 26, respectively, to a tubular shaft 16 prevented by a one-way detent 38 from backward rotation when a positive detent 19, described below, is engaged for forward drive. Torque multiplication then takes place in both the converter and gearing units unless conditions in the converter are such that the member 25 turns forwardly, when the converter acts as a fluid coupling. Either or both of the units may be locked solid by hydraulicallyoperated direct drive friction clutches 17, 18, described below, acting between the flywheel 22 and shaft 15 and between the annulus 32 and carrier 37 respectively. For reverse drive, the detent 19 is disengaged and a similar detent 21 engaged to station the carrier 37 and turbine 24, the member 25 and therefore the sun 34 and annulus 32 being driven backwards. A third detent 20 is provided to station the shaft 16 for push starting of the engine on a vehicle, during which the reactior on the sun 34 is reversed in direction. Clutches.-The clutch 17 comprises a single circumferentially-sprung intermediate driven plate 31 working in the converter fluid space and engaged when pressure fluid is supplied via conduits 50-52 to a combined piston and presser plate 28. In the absence of such fluid, the clutch is held engaged by leaf springs 79 only when the converter is empty, the pressure generated by its working fluid supplied through a conduit 61 being sufficient to overcome the springs and disengage the clutch. The multi-plate clutch 18 is engaged when fluid pressure is supplied via a conduit 47 to a similar combined piston and presser plate 45. Positive detents.-The detent 21 comprises a ratchet-toothed wheel 43, Fig. 5, on the carrier 37, engageable by a complementary sliding pawl 44. Incomplete working engagement of the pawl is prevented by a squaretoothed balking ring 96 co-axial with the wheel 43 and teeth 97 of which are normally held in alignment with the ratchet teeth 90 by the pawl but which is rotatable by a spring 100 through a small angle relative to the wheel 43 when the pawl is disengaged to block entry of the pawl too close to the working face of the teeth 90 as shown. The detent 19 similarly comprises a ratchet -toothed wheel 39 co-acting with the one-way brake 38 and engageable by a sliding pawl 40, like balking means being provided. To facilitate pawl operation, a hydraulicallyoperated friction brake 104, Fig. 2, is provided which, when engaged, stations the detent wheels to eliminate idling drag through the converter. The brake 104 comprises a combined piston and presser plate 105 normally spring-pressed to disengage, which acts through friction facings 108 ... 110 to press the detent wheels 43, 41, against a fixed abutment 111. The operation of the pawls 40, 44, and brake 104, is interconnected as described below, so that the brake is released immediately before pawl engagement occurs to enable, if necessary, the converter drag to rotate a blocked portion of the appropriate detent wheel teeth clear of the operative pawl. The pawls 40, 44 are mutually exclusively operated by a lever 129, Fig. 2, rocked by a control lever 139, Fig. 5, through slotted links 136, 132, connected by a pin 133 on a spring- pressed plunger 134 slidable in the link 136. The plunger 134 is normally locked in position by a spring-pressed pin 142 to prevent accidental jarring-out of the pawl in operation, but as the lever 139 passes through neutral a cam 145 unlocks the pin 142 and frees the plunger 134 to store temporarily the executive movement of the lever 139 if the pawl operated is momentarily baulked. A frictional gearlocating detent 146 is provided engaging notches in the link 136. The detent 20 comprises a ratchet-toothed wheel 41 engageable by a complementary sliding pawl 42, Fig. 5, operated from the vehicle dashboard by a Bowden control connected to a crank 162 whose movement is commimicated to the pawl by a link 159, a crank 155, and a plunger 148. Spring-biassed lost motion between the plunger 148 and pawl 42 is provided to store the executive energy when necessary. As described below, with the engine stopped there is no fluid supply to the converter and the clutch 17 is accordingly engaged by its springs 79, so that with the detent 20 operative the gearing is connected to rotate the engine from the road wheels of a vehicle for push starting of the engine. Audible ratcheting of the pawl 41 when the engine starts informs the operator that the pawl control may be released. Clutch and brake control means.-Operative fluid for the clutches 17, 18, the brake 104 and the converter is supplied, while the engine rotates, by a gear pump 53, Fig. 1, driven from a gear 55 on the converter impeller 23. Spring- loaded plunger relief valves 60, 62, monitor supply of fluid at a predetermined pressure to the converter via the conduit 61 and of fluid at a higher pressure to a manual valve 63 and a solenoid valve 48 via a conduit 164. The valve 63 connects the conduit 164 either to a conduit 122 supplying the brake 104, or to an exhaust conduit 170, and has also an intermediate position in which both the conduits 164, 122, are blocked off. The stems of the pawls 40, 44 are cut down at 115, 118 and 119 to act as valves further controlling the flow of fluid to the brake 104. With both pawls disengaged the conduit 122 is directly connected to the brake 104 as shown, but operation of either pawl cuts off the supply and connects the brake to an exhaust conduit 121, thus ensuring brake release before final pawl engagement as described above. The solenoid valve 48 controls the supply of fluid to the clutches 17, 18 via conduits 49, 51 and 52 and conduit 47, respectively. The valve 48 is spring-urged to the right to the position shown in which it connects both the clutches 17, 18 to exhaust, but is moved to the left by a two-stage solenoid 56, either to an intermediate position in which fluid is supplied to the clutch 17 alone, or to a final position in which fluid is supplied to both the clutches. Control of the solenoid 56 and of the engine starter is effected by electrical circuits 181, 180, Fig. 7, respectively. When switches 185, 186, in the circuit 180 are closed a relay 182 is energized and closes a switch 183 tooperate the engine starter 184. The switch 185 is the normal starter control switch and the switch 186 is actuated by a main forward-reverse gearing control lever as described below to prevent starter operation unless the gearing is in neutral. A similarlycontrolled switch 187 in the circuit 181 renders this circuit inoperative when reverse gear is engaged. When closed, the switch 187 supplies voltage to two parallel circuits, comprising " kick-down " switches 189, 190, which may be actuated by the accelerator 241 or independently thereof; switches 191, 192 closed above a first predetermined vehicle speed by a governor 58, Fig. 1, on the gearing output shaft 14; switches 194, 195 closed against spring-pressure by an engine suction-operated motor 196; and relays 202, 203 which when energized close switches 204, 207. Switch 207, when closed, energizes operating and holding coils 208, 209 of the solenoid 56 which are effective to move the valve 48 into its intermediate position; and switch 204, when closed, energizes further operating and holding coils 205, 206 which are additionally effective to move the valve into its final position. A windoperated switch 212 is closed above a second predetermined vehicle speed higher than the first. Holding resistances 213, 214 are provided in parallel with the switches 194, 195. Operation of gearing.-The main forwardreverse gear control lever 215, Fig. 6, referred to above, is manually controlled and actuates the pawl control lever 139, the valve 63 and a carburetter idling control 235, as well as the spring-opened switches 186, 187. The lever, which may be situated beneath the steering wheel, is pivoted vertically to an axially fixed rotatable-rod 217 and actuates a hollow rod 219 slidable thereon and having an arm 228 which on vertical movement engages one or other of slots 227, 225 in a fixed neutral bracket 226 and a forward-reverse control arm 223 linked to the lever 139. With the lever 215 in its neutral position the switch 186 is held closed by the end of the rod 219 and a lever 230 pivoted thereto and fulcrumed in the bracket 226 acts through spring-loaded bell-cranks both to turn the valve 63 so that the conduit 164 is connected to exhaust and to set the control 235 for fast idling. All the clutches and detents are at this time disengaged throughout the transmission. The engine may now be started by closing the switch 185. Subsequent vertical movement of the lever 215 to its forwardreverse position opens the switch 186 to disable the engine starter, sets the control 235 for slow idling, and turns the valve 63 first to its intermediate position to fill the converter and then to connect conduits 164 and 122 to supply the brake 104. When the arm 222 engages the arm 223, the lever 215 may be rotated horizontally to the right or left as seen in