JPS6446614A - Gas flow rate detection sensor - Google Patents

Abstract

PURPOSE:To unite a pressure detection part and an output part and to simplify the structure by making a contact coupled with a diaphragm contact the contact on an output circuit side through the deformation of the diaphragm which limits the gas shunt path of an ejector part. CONSTITUTION:When a gas flow rate becomes larger than a proper flow rate, ejector effect surpasses the force of a spring 14 to draw the diaphragm 16, and contacts 17a and 17b come into contact with a contact 15c coupled with an excessive flow rate circuit including the resistance R1 of an output circuit 17 and a contact 15d coupled with a power source 19 to output an excessive flow rate output P1. When the gas flow rate becomes smaller than the proper flow rate, the ejector effect becomes smaller than the force of the spring 14 and the diaphragm 16 is pushed out and the contacts 15b and 15a come into contact with the contact 15c connected to a fine flow rate circuit including the resistance R2 of an output circuit and the contact 15d to output a fine flow rate output P2; and the outputs P1 and P2 are inputted to a needle valve 20 to adjust the flow rate.