| 摘要 |
PROBLEM TO BE SOLVED: To provide a compact flow rate detection mechanism of a mass flowmeter excellent in linearity, capable of securing a stable laminar flow even if the pressure on the inlet side of a sensor part changes, and allowing big improvement in a gas replacement characteristic. SOLUTION: This flow rate detection mechanism 1 comprises a block 2 having a hole H allowing insertion of a nearly cylindrical holder 3 and two gas communicating holes 2a, 2b respectively communicating with two points apart from each other inside the hole H, a sensor passage tube 4 provided between the two gas communicating holes 2a, 2b, and a resistance member 5 inserted in the holder 3. Peripheral parts at both ends of the holder 3 are respectively formed with groove parts 3a, 3b communicating and connecting with the two gas communicating holes 2a, 2b. Gas G0 flowing in the hole H flows separately through a sensor passage P1 flows the sensor passage tube 4 via the groove part 3a to the groove part 3b via the gas communicating hole 2a, and the gas communicating hole 2b, and a bypass passage P2 formed by the resistance member 5 inside the holder 3.
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