| 摘要 |
PURPOSE:To enable measurement of an alcohol content from the outside of a fuel pipe by passing a fuel mixture contg. alcohol in microwave transmission paths and detecting the alcohol content from the attenuating rate of a microwave. CONSTITUTION:The microwave transmitted from an oscillator 5 propagates into waveguides 2, 21a, 21b from a coaxial cable 4a, and passes through a coaxial cable 4b to a detector 6. The microwave is converted by the detector 6 to a DC voltage proportional to the amplitude of the microwave and is fed as a sensor signal through a lead wire 6a to an air-fuel ratio control device. The characteristic impedance in the waveguide 2 is increased by the increase in the alcohol content in the fuel passing in a fuel piping 1 penetrating the waveguide 2 in parallel therewith, by which the microwave is attenuated. The attenuating rate of the microwave is detected by the detector 6, by which the alcohol content in the fuel is measured. |
