GB1227883A - - Google Patents

Abstract

1,227,883. 883. Fluid logic and switching circuits; regulating I. C. engines. NATIONAL RESEARCH DEVELOPMENT CORP. Aug. 1, 1969 [Aug. 1, 1968], No.36677/68. Headings F1B and F1P. [Also in Division G3]. A fuel supply system for an I. C. engine 10 Fig. 1 comprises means for generating a primary signal in the form of a series of time-spaced air pressure pulses in a line 19 and of frequency dependant on engine speed, e.g. an air pump 14, nozzle 15 and a slotted disc 18 driven by the engine, means 20 for modulating the pulses e.g. duration thereof as a function of a parameter representative of the fuel requirements for a given air intake and liquid fuel injection means 13, 24 responsive to the modulated pulses to determine the rate of fuel supply. The pulse modulating means may comprise a variable delay unit 29 Fig. 2 connected by a restricted line 21 branching from the air intake manifold 11 upstream of a throttle valve 12, a fixed delay unit 30 in parallel with unit 29, and a monostable amplifier 33 having control ports 37, 38 respectively connected to the output of units 30, 29 a constant air supply line 34, a vent output 40 and a working output line 23 leading to main inlet 64 Fig.4 of the liquid fuel injection means 24, which latter is an air to fuel transducer. In operation fuel from a pump 25 is admitted to an inlet 63 and in the absence of an air pulse at 64 the liquid fuel passes along a passage 65 and an outlet 67 to a return tank (not shown). An air pulse at 64 deflect the light fuel along a passage 68 to an outlet 71 connected by a line 26 to injector 13 whilst the air pulse is deflected by arcuate surfaces 69, 70 along passage 65. Passages 72, 73 are provided for matching fluidic load at the entrances to 65,68 irrespective of the loading at outlets 67, 71. The basic pulse signal in line 19 at high and low engine speeds is shown in the left and right hand portions of curve A Fig. 5 and the variably and fixed delayed pulses at high manifold pressures are shown in curves B, C. The control signal in line 23 at low and high engine speeds and high manifold pressure is shown by curve D from which it is seen that whilst the pulse frequency and magnitude is equal to those of the basic signal in line 19 the duration i. e. the width of each pulse in line 23 is reduced. Curve E shows the variality delayed signal in line 31 at low manifold pressure, whilst curve F shows the control signal in line 23 at low manifold pressure. Fig. 3, 7 (not shown) show alternative pulse width modulation circuits whilst Fig. 9 (not shown) shows a circuit for modulating the amplitude of the primary pulses proportional to the absolute pressure in the manifold.