| 摘要 |
PURPOSE:To obtain a compact, long-life measuring device for fluid characteristics by forcing a piezoelectric oscillator provided in oil to oscillate, measuring the amplitude of the output signal of the piezoelectric oscillator and calculating the viscosity of the oil, and detecting the deterioration of the oil. CONSTITUTION:The piezoelectric oscillator 1 is inserted into the bottom part of the oil pan of an engine and put in the oil. A pulse generator 30C generates a pulse signal of frequency equal to the characteristic frequency of the oscillator 1, and its oscillation output is supplied to an electromagnetic coil 6 from a constant current circuit 30-D as an exciting signal through lead wires 6a and 6b to allow the oscillator 1 to oscillate according to the output. The output signal of the oscillator 1 is passed through lead wires 5a and 5b and converted by a differential amplifier 30E, rectifying circuit 30F, and smoothing circuit 30G into a DC signal proportional to the amplitude, and amplitude data A is obtained by an A/D converter 30H. The output signal of a temperature sensor 31 in the oil is converted by an A/D converter 30B into temperature data T, which is outputted. A main arithmetic circuit 30J reads the data T and A and the deterioration of the oil is detected on the basis of those data. |
