| 摘要 |
<p>PURPOSE:To make accurate measurement of flow rate possible by enhancing straightening effect of fluid flowing through a flowmeter without increasing pressure loss. CONSTITUTION:An air flowmeter comprises a central cylindrical part 100, an upstream cylindrical part 200, and a downstream cylindrical part 300, and a main passage is formed internally. Sensor parts 570, 580 for measuring flow rate of air are disposed in a branch path for feeding air introduced through an inlet opening part 410. Since a bellmouthed part 210 is resin molded integrally with the upstream cylindrical part 200, no step nor protrusion is present on the inner wall constituting the main passage. Inner diameters D1, D2 of the bell-mouthed part, respectively, on the down stream side and upstream side are set such that the diaphragm ratio D2/D1>=1.15. Since straightened flow in the main channel stabilizes negative pressure at an outlet opening 440, turbulence in branch path is retarded and flow rate in the branch path corresponds accurately to the flow rate in the main passage. This constitution allows accurate measurement of flow rate at the sensor parts 570, 580.</p> |
