Patent GB-1307421-A (GB)
Title: Power transmission
IPC: F16H37/00
Filed: 1970-03-17
Abstract: 1307421 Vehicle transmissions TRW Inc 17 March 1970 [17 March 1969] 12799/70 Heading B7H [Also in Divisions G3 and H2] In a first mode of operation, the speed of an internal combustion engine driving a road wheel 20, via an epicyclic gear train 6, 8, 10, 12 and via. a three phase alternator 22, whose rectified output supplies a D.C. series or permanent magnet machine 28 coupled to the wheel, is kept constant. Fluctuations in work demand are met by machine 28, which may also function as a generator charging the lead-acid or nickel cadmium battery 44, which may also be charged by alternator 22. Alternator 22 absorbs the torque reaction on planet carrier 6, and, by control via controller 40, of the electrical load seen by the alternator 22, and hence its speed, the gear ratio between shafts 4, 18 may be varied to keep engine speed constant. In a second mode of operation, the alternator 22 is locked at rest by a brake 46, and the engine speed varies, machine 28 continuing to be utilized as motor, or generator. There may be clutches, or gear trains between shaft 4 and sun gear 5 for reversing or speed change. Transistion between modes takes place smoothly as the alternator speed goes to zero. Control of machine 28, Fig: 4 (i) Motoring.-For the lower positions of control pedal 270, mode switch 108 connects the armature 210 and field 200 across battery 44 via SCR 114 which is fired, via variable time pulses 104 a controllable interval after its preceding quenching, a sync. signal 148 discharging timing capacitor 258 each time SCR 114 is quenched, its charging time being controlledby the setting of potentiometer 272. Acommutating circuit, including SCR 124, capacitor 126, and saturable reactor 132 operates at constant intervals under control of clock pulser 102 to quench SCR 114. A lockout 154 ensures that neither of pulses 102, 104 can function unless capacitor 126 is charged. The frequency of pulser 104 also depends on the outputs from an overcurrent detector 166 sensing the voltage across resistors 163, 164 and voltage comparator 282 comparing voltages at the armature of machine 28, and the battery. (ii) Generating.-For the upper positions of control pedal 270, mode switch 108 changes over to cause SCK 114, when conducting, to short circuit the machine 28, the resulting build-up of current in armature and field windings representing energy storage, which, when SCR 114, is quenched, passes impulsively via diode 118 to the battery 44, so that high battery voltage can be used. The overcurrent detector, by disconnecting resistor 163, is made more sensitive in the generating mode. The field 200 is connected with the current polarity for motoring or generating, allowing also for the direction of vehicle motion, by switches 196, 198, 202, 204, controlled by coils 186, 188, which also control safety switches 296, 298, 300, 302. Current overriding coils 206, 208 ensure that changeover can occur only when machine current is substantially zero. Switch 152 shorts out SCR 114 for 100% duty. The generated power may alternatively be dissipated in resistive elements (not shown).  Control of alternator 22, Fig. 5 (not shown).- The output of the alternator, after rectification by diodes (318, 318<SP>1</SP> 320, 320<SP>1</SP> 322, 322<SP>1</SP>) is passed to the battery (44), when SCR (326), controlled in the manner of SCR 114 in Fig. 4, is rendered non-conductive, the alternator output being inductively stored, inductance (324) being provided, when SCR (326) is inductive. The frequency of time variable pulser (330) is controlled independence on an error signal derived in comparator 336 from an adjustable reference signal (338) corresponding to desired motor speed and a signal from engine driven tachogenerator 36, Fig. 1, such as to keep engine speed constant. Should high battery voltage occur, as determined by comparision withareference voltage derivedfrom Zener (349), SCR (352) is fired, alternator energy being dissipated in network (354), and SCR (352) being quenched by SCR (326). Should battery voltage still remain high, for a period defined by the network (368, 370) the network comprising transistors (360, 362, 364) is rendered conductive, activating throttle control coil (366) to decrease engine output until battery voltage falls. A similar network (not shown) may cause boosting of engine output if battery voltage falls below a predetermined amount. It is stated that an engine override control is used to keep engine produced enviromental pollution to a minimum.