| 摘要 |
<p>PURPOSE:To allow the holding of responsiveness to temperature change within an engine room and durability better without infiltration of dust from outside by making a closed spaced where a control circuit is arranged communicate with a hollow space of a center member. CONSTITUTION:Introduction air flowing through a main path 2 increases in flow velocity with a downstream side path choke part C to generate a vacuum. An output path 16 of a bypass path 7 is opened at the choke part C and a flow of air is generated at the path 7 by a differential pressure from an inlet section 8. A resistor 12 for measuring flow velocity set in the path 7 is heated at a fixed temperature difference from a suction temperature with a control circuit 14 and the flow of the air in the path 7 is measured to detect an amount of suction air. With the generation of heat of the circuit 14 or heating from outside, air sealed in a housing chamber 11 expands thermally with a rise in temperature. Here, as a center space 6 and the housing chamber 11 is made to communicate through a tubule 19, a part of the air expanded in the housing chamber 11 moves to the center space 6 thereby enabling maintaining of a pressure stable constantly with easing of the pressure rise in the housing chamber 11.</p> |
