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    • 9. 发明授权
    • Surface acoustic wave gas flow rate sensor with self-heating feature
    • 具有自热特性的表面声波气体流量传感器
    • US4726225A
    • 1988-02-23
    • US899439
    • 1986-08-22
    • John G. BraceThomas S. Sanfelippo
    • John G. BraceThomas S. Sanfelippo
    • G01F1/68G01F1/66G01F1/688G01F1/69G01N29/00G01N29/02
    • G01F1/66G01F1/6882G01N2291/02836Y10S73/04
    • A surface acoustic wave device for measuring the mass flow rate of a gas includes a surface acoustic wave delay line formed of a piezoelectric substrate and having a temperature coefficient of delay on the order of 10.sup.-4 /.degree.C. The substrate has disposed thereon a transmitting and a receiving interdigital transducer, the transducers being configured to have an operating frequency in the range of from 10MHz to 1000MHz. That portion of the substrate located between the transducers defines a propagation region and has a medium deposited thereon for absorbing a portion of the acoustical and/or electrical energy flowing thereacross. This absorbed energy increases the temperature of the propagation region over that of the surrounding ambient.A mass flow of the gas across the sensor will decrease its temperature and result in an upward shift in the resonant frequency. A suitable amplifier and resonant frequency detector may be coupled to the sensor for detecting the change in resonant frequency, thereby permitting mass flow rate measurement.
    • 用于测量气体的质量流量的声表面波装置包括由压电基片形成并具有约10-4 /℃的延迟温度系数的声表面波延迟线。基板上设置有 发射和接收叉指式换能器,所述换能器被配置为具有在10MHz至1000MHz范围内的工作频率。 位于换能器之间的衬底的该部分限定了传播区域并且具有沉积在其上的介质,用于吸收在其上流动的一部分声学和/或电能。 这种吸收的能量增加了传播区域的温度超过周围环境的温度。 通过传感器的气体的质量流量将降低其温度并导致谐振频率向上移动。 合适的放大器和谐振频率检测器可以耦合到传感器,用于检测谐振频率的变化,从而允许质量流量测量。