CONTROL SYSTEM FOR VEHICLES

摘要

1466867 Regulating IC engines CAV Ltd 29 March 1974 [14 April 1973] 18092/73 Heading FIB [Also in Divisions F2 and H3] The output of an engine fuel pump 15, and hence the rate of engine fuel supply, is controlled through a rod 35 by an electro-mechanical actuator 16a, energized through a drive circuit 45 in response to three tranducers 36, 37, 38 responding respectively to engine speed, rate of fuel supply and engine speed demand, the last named being the usual engine accelerator pedal, which provides a voltage opposing the other two. The transducer outputs, converted to currents by resistors 36a &c., are applied to the inverting terminals of operational amplifiers 39, 40, supplied by positive and negative terminals 41, 42, and having their non-inverting terminals 43 at a midway reference potential. The amplifiers control the drive circuit 45 inversely through diodes 44, 46, which discriminate in favour of that amplifier 39 or 40 which is producing the more positive output. Feedback resistors 47, 48 compensate for the temperature-dependent voltage drop across the diodes 44, 46. The amplifier 39 compares the actual and demanded speed signals, and adjusts the pump control until the signals approach a relative value determined by the pump output signal. The amplifier 40 receives only the output from the pump output transducer 37 and a predetermined reference current from a source 49, and, when pump output exceeds a value determined thereby, takes over from the amplifier 39 to reduce the fuel supply until the amplifier 39 demands less fuel than the predetermined maximum of the amplifier 40, whereupon the amplifier 39 again resumes control. During a ratio shift in an associated electronically controlled change-speed gear, (see F2D), the full voltage line 42 is connected to the inverting input 49, 37b of the amplifier 40 whereby the latter produces a larger positive output than the amplifier 39, and therefore takes over from 39 to reduce the fuel supply during shift and subsequently increase it gradually to pre-shift value as the signal from the shift circuit decays. Fig. 13 (not shown), provides a means for increasing the engine fuel supply to prevent stall when engaging a gear ratio with the engine idling in neutral. Signals from individual ratio establishing circuits (see F2D) are connected through diodes (D17) and a resistor (68) to a capacitor (C9), which discharges and causes, at some point, a transistor (TR19) to conduct and thereby adjust the voltage across a capacitor (C8), which voltage varies the current fed from an independent source (70) to the inverting input of the amplifier 39, Fig. 6, thereby adjusting the fuel control rod 35, when entering a ratio from neutral, and reversing the adjustment when neutral is resumed. Resistors (64, 67) determine the engine idle speed.