| 摘要 |
<p>PURPOSE: To provide a mass flow controller which can accurately control the position of a valve body by feeding back a measured mass flow rate and has a complete cutting-off function. CONSTITUTION: The mass flow controller, having a mass flowmeter part 2 which measures the mass flow rate of fluid flowing in a conduit 15 from the values of currents flowing to two resistance bodies R1 and R2 wound around the duct 15 independently of each other and varying in resistance value with the temperature of the fluid and a proportional valve mechanism which is sit in the passage of the fluid and varies the flow rate by varying the gap formed with a valve seat 27, has diaphragm 24 formed integrally with the valve body 17, a solenoid valve 35 for supply and a solenoid valve 36 for discharge which control compressed air operating on the diaphragm 24 to change the position of the valve body, and a control means 32 and a pulse converting circuit 33 which control the solenoid valve 35 for supply and solenoid valve 36 for discharge on the basis of the mass flow rate of the fluid measured by the mass flowmeter part 2 and feed the mass flow rate of the fluid back to a specific value.</p> |
