| 摘要 |
<p>PURPOSE:To obtain a heat type flow-velocity measuring apparatus, which can obtain the output signal having the sufficient magnitude so that the output is monotonously increased or decreased with respect to a flow velocity by optimizing the size of the structure so as to match the thermal diffusivity of fluid and the maximum flow velocity to be measured. CONSTITUTION:A silicon substrate 21 constitutes a part of the wall of a fluid pipe. Temperature measuring elements are formed on the silicon substrate so as to face a flow path and measure the temperature difference between two points A and B, which are separated in the flowing direction of the fluid. A heating part 28 is provided at the central part between the two points A and B. These parts are provided in a flow-velocity measuring apparatus. The distance between the two points A and B is 0.9 times or more and 3.2 times or less as large as the value, which is obtained by dividing the value of the thermal diffusivity of the fluid by the value of the maximum flow velocity to be measured. The heating part 28 can be provided at the wall, which faces the central part between the two points A and B through the flow path. The temperature measuring elements are formed of thermopiles, a pair of diodes and a pair of transistors.</p> |
