Patent ID: 6938473
Filing Date: 2005-09-06
Classification: G01F

Abstract:
1. An apparatus for measuring flow amount of medium, the apparatus comprising: a main passage in which the medium flows; a bypass passage for introducing a part of the medium flowing in the main passage, an inner diameter of the bypass passage being substantially constant along an entire length thereof; a sensor element for measuring flow amount; a sensing passage accommodated in the bypass passage and having an inlet for introducing the medium, the sensing passage supporting the sensor element therein; and an obstruction member disposed in said bypass passage, upstream of the inlet of the sensing passage, the obstruction member having a smooth surface along a flow direction of the medium and providing a projected area larger than the inlet so that the inlet is completely hidden behind the obstruction member with respect to the flow direction of the medium, said obstruction member being disposed upstream of the inlet of the sensing passage by a predetermined distance whereby air flow disrupted by said obstruction member becomes substantially steady at the inlet of the sensing passage, but dust is deflected from said inlet.