| 摘要 |
<p>PURPOSE:To measure a very small flow rate with high accuracy by providing a check valve whose passage resistance is large in a low flow rate area, and whose passage resistance becomes small in a high flow rate area, and measuring a flow rate of a fluid, based on a detection output of a strain gage. CONSTITUTION:On the lower face of a silicon substrate 40, a diaphragm 42 for generating a stress corresponding to differential pressure of both faces of the substrate 40 is formed, and in the vicinity of the center of the diaphragm 42, a minute hole 44 tapered from the upstream side to the downstream side is formed. There diaphragm 42 and minute hole 44 can be formed with high accuracy by a unit of micron order by performing a crystal anisotropic etching treatment by using an alkali etching liquid to the substrate 40. Also, on the substrate 40, a check valve 60 is provided on the downstream side of the minute hole 44, and the valve 60 is formed so that the passage resistance becomes large in a low rate area, and the passage resistance becomes small in a high flow rate area. In such a state, by measuring a flow rate of a fluid, based on a detection output of a strain gauge 46, a very small flow rate can be measured with this accuracy.</p> |
