| 摘要 |
<p>PURPOSE:To reduce the change of a thermal flowmeter with the elapse of time by reducing the amount of the dust particle adhered to a heat-sensitive resistor, by providing a conductive air pervious body to the air passage part on the upstream side of the heat-sensitive resistor in a thermal air amount measuring apparatus in an earthed state. CONSTITUTION:The dust particle introduced into an air cleaner passes through an air cleaner element 10 to be charged by the friction with the element 10 but the charge of the charged dust particle is neutralized by the ion formed by the discharge of a conductive fiber 11. Since the dust particle having residual charge not neutralized is collided with and adhered to a metallic distributing element 12 as an earthed conductive air pervious body and the residual charge is leaked, the charge of the dust particle reaching the detection element of a heat generating resistor 6 is reduced to a large extent. As a result, the electrostatic force acting on the dust particle becomes a negligible level and the adhesion amount of the dust particle to the surface of the detection element of the heat generating resistor 6 is reduced and the change of a thermal flowmeter with the elapse of time can be reduced.</p> |
