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Flow sensor and mass flow controller using the same

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TLDR
In this paper, a low cost, compact, high performance flow sensor that can be made small in size even for use in a large flow rate and a mass flow controller using the same are provided.
Abstract
A low cost, compact, high performance flow sensor that can be made small in size even for use in a large flow rate and a mass flow controller using the same are provided. The flow sensor includes a bypass passage, a sensor passage, and a bridge circuit including heat-generating resistance wires that constitute a part of the bridge circuit and are wound around the sensor passage. The flow sensor determines a total flow rate of a fluid that flows in a branched manner through the bypass passage and the sensor passage at a predetermined flow ratio. The total flow rate is determined by detecting, as an unbalance of the bridge circuit, heat transfer caused by the fluid flowing through the sensor passage and is outputted as a sensor output of the flow sensor. In the flow sensor, the bypass passage includes a plurality of fine flow passages each having a cross-section defined by a substantially linear edge and a curve in contact with the substantially linear edge. The ratio of the equivalent hydraulic diameter (d) of the fine flow passages to the common logarithm of the length (T) of the fine flow passages is 0.27 or less. The flow sensor is installed in the mass flow controller.

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Citations
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References
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Patent

Mass flow controller

TL;DR: In this article, a mass flow controller with a bypass portion provided in a body through which a large amount of gas is passed and a sensor portion, laid between a primary chamber which is an inlet of the bypass portion and a secondary chamber which are an outlet of bypass portion, through which gas flows at a small flow rate proportional to the flow rate of the gas passed through the bypass.
Patent

Thermal flow sensor having sensor and bypass passages

TL;DR: In this paper, a laminated filter is made of a mesh plate including a mesh part, a first blocking plate, a second blocking plate and a third blocking part which are arbitrarily combined and layered.
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Air flow meter

TL;DR: A hot-wire air flow meter (100) has a cylindrical housing (1) to be coupled to an intake air conduit of a vehicle in way that a main passage (2) is formed within said housing An egg-shape member (4) for forming a bypass passage (7) therein is supported by a plurality of supporting members in a center of the main passage as discussed by the authors.
Patent

Mass flow controller

TL;DR: A mass flow controller includes a base having a passage that allows a fluid to pass through the passage, and a second control valve controls a full scale of the mass flow of the fluid as discussed by the authors.
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Fluidized bed furnace utilizing exhaust gas

TL;DR: In this article, the use of a nonoxidation heat treatment and using gaseous fuel and the exhaust combustion gas of an internal combustion engine as the fluidizing gas to be fed into the fluidized bed of a fluidized-bed furnace for heat treating the metallic material was proposed.