Patent ID: 7434988

Claim:
An acoustic signal generator for generating an acoustic signal with a high amplitude, sudden onset for measuring the temperature in a process chamber with an acoustic pyrometer, comprising: an outer tank closed at top and bottom ends by top and bottom plates, said outer tank enclosing a first chamber; a cylinder supported within said tank and having top and bottom opposed ends, said cylinder enclosing a second chamber; a mid-plate extending across said cylinder and defining said bottom end, and an axial opening in said mid-plate receiving a shaft of a piston assembly having an upper piston in said second chamber and a lower piston at a lower end of said shaft; a throat received in an opening through to said bottom plate and receiving said lower piston, said lower piston sealing said throat when received in said throat; said upper piston slidable in said in said cylinder under influence of air pressure; a pneumatic operating system for charging said first and second chambers with gas at a moderate pressure, said pneumatic operating system including a coupling for connection to a source of gas pressure and a remotely operated vent to allow said pressurized gas in said second chamber to escape through an exhaust opening, thereby allowing said piston assembly to open said throat suddenly and allow pressurized gas to escape rapidly from said first chamber through said throat and produce a shock wave that propagates into said process chamber for use by said acoustic pyrometer.