| 摘要 |
<p>PURPOSE:To obtain a thermal flow sensor in which response is enhanced significantly by improving thermal conduction and thermal insulation effect of a board having a membrane resistor. CONSTITUTION:In the thermal flow sensor 20, a membrane resistor 24 and wirings 25, 26 are formed on the surface of a thin rectangular board 22. The board 22 comprises a heat transmitting part 22b formed of a material having high thermal conductivity in the longitudinally central part and thermal insulating parts 22a, 22c formed of a material having low thermal conductivity at the opposite ends in the longitudinal direction. The membrane resistor 24 is printed in pattern on the surface of the heat transmitting part 2b while the wirings 25, 26 are printed in pattern on the surface of the thermal insulating parts 22a, 22c. When flow rate is measured, heat generated from the membrane resistor 24 is transmitted quickly to the heat transmitting part 22b and prevented from being transmitted to other parts by means of the thermal insulating parts 22a, 22b. Since temperatures at the heat transmitting part 22b and the membrane resistor 24 settle in a short time upon variation of flow rate, response of sensor output is enhanced.</p> |
