Ultrasonic fuel injection quantity measurement for diesel engines - using frequency analogue signals and phase comparison circuit for output from piezoelectric sensors

摘要

The fuel measurement device, is esp. for diesel engines and measures the quantity, pref. the mass, of fuel flowing through a tube(3) from a given time of the start of an injection cycle. Mechanical to electrical transducers measure the flow quantity and start time. The corresp. electronic signals are suitable for simple processing in a microprocessor. They are produced in frequency analogue form. An ultrasonic receiver(2), esp. a piezoelectric plate type, is placed downstream of an ultrasonic transmitter(1). An evaluation circuit compares the phases of the waves output from the transmitter and the signals produced by the receiver. The injection period finish time may also be measured. Calibration may be periodically performed in between injection cycles using the known flow speed to set a null.