| 摘要 |
PURPOSE:To compensate the temperature coefficient of the resonant frequency of a vibrating body, by fixing a temperature coefficient compensating plate whose temperature coefficient of Young's modulus is negative to a piezoelectric plate whose temperature coefficient of the Young's modulus is positive. CONSTITUTION:A base part 12b of the vibrating body 12 is supported and fixed to a base table 10 which is attached to the engine under the state the base part 12b is compressed by a pushing plate 14. The vibrating body 12 comprises two piezoelectric plates 16 and 18 which are mutually fixed with the polarization directions being opposite and the temperature coefficient compensating plates 20 and 22 which have the thickness 1/100-1/10 time the thickness of two piezoelectric plates 16 and 18 and are fixed to both surface of the piezoelectric plates 16 and 18. The piezoelectric plates 16 and 18 are made of titanic acid lead zirconate whose temperature coefficient beta of the Young's modulus E is positive. The temperature coefficient compensating plates 20 and 22 are made of Ni or Ni-Fe alloy whose temperature coefficient beta of the Young's modulus E is negative. When the temperature coefficient beta of the Young's modulus E of the piezoelectric plates 16 and 18 is positive, the plates are combined with the temperature coefficient compensating plates 20 and 22 having the negative value, and the temperature coefficient of the resonant frequency of the vibrating body 12 can be compensated. |
