GB1536657A - Control system for a hydrodynamic torque converter - Google Patents

Abstract

1536657 Change - speed control SRM HYDROMEKANIK AB 14 Nov 1975 [14 Nov 1974] 49317/74 Heading F2D A lock-up clutch 14 of an hydrodynamic torque converter is controlled by a comparison of signals representing input speed 24, and engine torque demand 26 (accelerator pedal setting). Control is electronic and the input signals are represented as a function of time in a counter circuit, by frequencies, or in analogue or digital forms. Hysteresis is provided. The torque demand signal is obtained from an accelerator-controlled potentiometer. Also included is a separating clutch 16 between the converter turbine and the input to, e.g. a synchromesh change speed gear, the shift lever of which carries a clutch release switch 28. A further switch 30 prevents closure of the engine start circuit unless the separating clutch 16 is released. Two electro-hydraulic valves 18, 20 control the supply of engaging pressure to the two clutches 14, 16. Performance curves are given as is also a complete transistor circuit, Fig. 2, not shown, in which component values are specified. The following block diagrams are also included. In Figs. 2a and 2b (not shown) comparison is made between the voltage output of a throttlecontrolled potentiometer and the speedresponsive voltage derived by a converter from the speed-responsive frequency picked up at the engine ignition or by equivalent pick-up. In Fig. 2c, not shown, each pulse of an input speed responsive frequency triggers a monostable switch controlled by a throttle potentiometer which determines the pulse finish. The comparator is a flip-flop clocked by the pulses and controlling an output relay. In Fig. 2d, not shown, a throttle potentiometer (44) or capacitor controls the output frequency of a voltagecontrolled oscillator (V.C.O.) forming a phaselocked-loop with a low pass filter (50) and phase detector (48), in which latter the frequency and phase of the input speed signal (24) and V.C.O. (46) are compared, the feed back to the V.C.O. causing it to attain frequency and phase synchronization with the speed signal, whereby the output signal is speed and throttle dependent. In Fig. 2e (not shown) input speed pulses are counted in a counter (54) timed by a time base (55) to provide a digital signal for direct comparison with a digital signal derived through a converter from a throttle-angle pick-up. A microcomputer may alternatively be used.