Patent GB-668329-A (GB)
Title: Improvements in or relating to power transmission
IPC: F16H61/14
Filed: 1949-07-21
Abstract: 668,329. Clutches; variable-speed gearing. AKTIEBOLAGET LJUNGSTROMS ANGTURBIN. July 21, 1949 [July 22, 1948], No. 19212/49. Class 80 (ii). [Also in Group XXIX] In a power transmission system for motor-vehicles comprising a friction or dog clutch in parallel with a hydraulic torque converter, the clutch engages, above a minimum speed, upon the occurrence of a predetermined minimum reaction torque in the converter, and manual control means are provided. As shown in Fig. 1, the converter comprises an engine-driven casing 12 carrying impeller blades 18, turbine blades 28, 30 carried by the output shaft 24, and reaction blades 46 carried by a sleeve 34. A friction clutch 48 between the casing 12 and sleeve 34 is controlled bv a lever 60. The sleeve 34 has a oneway connection 64 with shaft 24 and a one-way connection 72 with a ring 78 capable of limited backward turning movement in the stationary housing 10 against the action of an adjustable spring 96, as shown in Fig. 2. The lever 60 is operated by a solenoid 178, Fig. 4, energised by a relay switch 186 controlled by three switches 122, 140, 128 in series, the solenoid having a second coil 188 which is in parallel with 178 but which is cut out by a switch 196 as the clutch engages. Switch 122 is controlled by the ring 78 so as to be held open under the influence of reaction torque transmitted to the ring 78 but to be closed when the reaction torque falls below a predetermined value dependent on the adjustment of the spring 96. Switch 140 is normally open but is closed at a predetermined speed by a centrifugal governor 132 driven from a worm 102 on shaft 24. Switch 128 is normally closed but is adapted to be opened via toggle levers when the accelerator 142 is depressed beyond full-throttle position. In starting from rest, clutch 48 is disengaged and shaft 24 is driven through the converter with increased torque, torque reaction on the sleeve 34 causing the ring 78 to turn backwards to the limiting position shown in Fig. 2. As the shaft 234 accelerates, switch 140 closes at about 12 m.p.h., and the reaction torque diminishes until, at about 50 m.p.h., spring 96 is able to turn the ring 78 forwards to close switch 122. The relay circuit is thus completed to cause the clutch 48 to engage, drive from the casing 12 to shaft 24 being now via clutch 48, sleeve 34 and one-way connection 64, and the clutch normally' remains so engaged until the speed drops below 12 m.p.h., when switch 140 opens. Above 12 m.p.h., the clutch may, however, be engaged at will by releasing the accelerator. The clutch may be disengaged at will by depressing the accelerator beyond full-throttle position so as to open switch 128; the arrangement being such that the switch remains open until the accelerator is allowed to rise above the full-throttle position. A second speed-responsive switch 160 operates, however, to short-circuit the switch 128 at a speed of about 50 m.p.h. Further, a manual switch 170 may be closed to short-circuit the switches 122, 140, 160, 128 so as to cause clutch engagement at any time. The throttle linkage may include a spring-loaded lost-motion connection 200, Fig. 5, and a solenoid 206 may be energised by a contact on the switch 196 so that its armature 208 may momentarily close the throttle during the clutch engaging movement, to prevent shock. When a dog clutch is used instead of a friction clutch, means are provided for momentarily relieving the driving torque during the disengaging movement, as by momentarily closing the throttle. If the converter is of the stationary casing type, a ring carrying the reaction blades may have limited turning movement in the fixed casing against spring loading and have teeth meshing with a pinion operating the switch 122. Alternatively, a vane 328, Fig. 7, carried by a spindle 326 freely mounted in the fixed casing 310 is disposed in the hydraulic circuit between the first row of turbine blades 320 and the fixed reaction blades 324. The vane adapts itself to the direction of flow from the blades 320, which is indicative of the reaction torque applied to the blades 324, the spindle 326 operating the switch 122. U.S.A. Specification 1,900,119 is referred to.