Flow rated control valve using a high-temperature stacked-type displacement device

A mass flow controller including:

• (a) a flow rate control valve comprising:
• a valve chest having an open end;
• an inflow passage and outflow passage each having one end communicating with said valve chest and the other end open;
• a valve seat provided at said one end of said inflow passage or said outflow passage communicating with said valve chest;
• a sheet-like diaphragm provided to tightly close the open end of said valve chest and forming a gap with said valve seat;
• and
• a stacked-type displacement device made of an electromechanical transducing material exhibiting a maximum value of piezoelectric distortion constant in the temperature range 100.degree. C. and above, said displacement device being positioned to exert a pressure on said diaphragm by its deformation, whereby said diaphragm is displaced to control the gap between said valve chest and said diaphragm;
• (b) flow rate detecting means provided in said inflow passage or said outflow passage;
• (c) means for comparing the output of said flow rate detecting means with a set control value;
• and
• (d) control means for controlling said flow control valve on the basis of said compared result.