Heated probe fuel flowmeter with fuel temp. compensation - uses pyroelectric conductor and resistor combination sensing probe heating power

摘要

a flow measurement device, esp for instantaneous vehicle fuel consumption measurement, has a probe in the fuel flow held at constant temp. with a circuit compensating the fuel temp. using a pyroelectric conductor immersed in the fuel. Fuel temp. is compensated economically over a wide temp. range without analogue or digital dividers, analogue -to-digital conversion, or the non-linearities associated with bridge circuits. A combination (7) of pyroelectric conductor and resistors has a resistance decreasing linearly with pyroelectric conductor temp. and is connected in series with a resistor (8) to form a compensation circuit. The compensation circuit is subjected to a voltage proportional to the probe (1) heating power and produces a temp. compensated measurement signal at the series resistor (8). The signal is output via an amplifier (9).