GB1284417A - Improvements in governors for diesel engines - Google Patents

Abstract

1284417 Automatic control of speed ROBERT BOSCH GmbH 10 Oct 1969 [10 Oct 1968] 49750/69 Heading G3R In a governor system for a diesel engine e.g. driving a generator in which the setting of the injector is adjusted in response to the difference in frequency between pulses representative of actual and desired speeds, the two sets of pulses are applied to respective inputs of a bi-stable multivibrator whose outputs are connected to gates arranged so that an output (i.e. error) pulse is produced whenever the input pulses do not alternate with each other, and a logic circuit prevents an error pulse being produced when the input pulses occur simultaneously. The actual speed pulse train is produced by a tachogenerator 22, a Schmitt trigger 23 and a monostable multi-vibrator (m.v.) 24 and the reference pulses from an astable m.v. 20 and a monostable m.v. 21. They are connected to respective inputs of a bi-stable m.v. 25, to AND gates 26, 27 and to a NAND gate 28. The arrangement is such that pulses appear on the outputs of 26, 27 if a high or low speed error exists, respectively at a frequency depending upon the magnitude of the error. AND gates 26, 27 are blocked by loss of signal from NAND 28 if two input pulses occur simultaneously. The output pulses from 26, 27 are increased to a standard length by further monostable m.v.s., Figs.3 and 4 (not shown). The final pulses operate a thyristor controlled, injector regulating servomotor in a proportional manner and an integral term is added by algebraically counting the pulses and converting the count to an analogue voltage. This term is compared with a voltage from an injector position feedback potentiometer. In Fig. 5 (not shown) the respective voltages control the frequency of astable m.v.s., the frequencies then being compared but in Fig. 6 (not shown) the voltages to be compared are applied to respective Schmitt triggers to which is also applied a sawtooth waveform synchronized with the speed reference pulses. The triggers change over when their inputs are equal, thereby producing "increase" or "decrease" trains of pulses of variable width. In Fig. 7 (not shown) a differential term is added by feeding back the combined (P + I) controlling signal to the input of the counter (I channel). The servomotor may be reversible, or unidirectional with spring return. Reference has been directed by the Comptroller to Specification 1134059.