PURPOSE: To automatically switch over a nozzle and to improve safety, by constituting nozzle switching device by secondary pressure drive part which is multi-stagedly displaced by the change of the pressure, and by a gas passage change part which changes the gas passage corresponding to each kind of gas, to operate in linkage with the displacement of the secondary pressure drive part.
CONSTITUTION: The secondary pressure in a governer is sensed from a secondary pressure interconnecting tube 26, and gas is fed to a universal burner from a gas injection port 29, changing the diameter of a nozzle in a gas passage change part 28 to fit to a kind of gas, by the operation of the secondary pressure drive part 27. The secondary pressure drive part 27 is divided into a pressure chamber 31 and a back pressure chamber 32 by a diaphragm 30, and a drive shaft 33 which is interllocked with the diaphragm 30 is connected to the gas passage change part 28, being interposed by a seal diaphragm 34. The gas passage change part 28 is supported by a selector valve 36 provided at the end of the drive shaft 33, an outer valve seat 37 being fixed to a position fronting to the selector valve 36, and the upper 38 and the lower 39 diaphragms of a complex valve seat. The gas passage change part 28 is constituted in such a manner that the complex valve seat 40, which is able to be displaced in the axial direction, is depressed to the center of an outer valve seat 37 by springs 41, and is abutted against the selector valve 36, earlier than the outer valve seat 37.
SHIRAI SHIGERU
MATSUMOTO TOMOHIDE
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