TERMOSTATO A BULBO CON MEZZI DI SICUREZZA POSITIVA

The object of the present invention is a bulb thermostat (T), provided with means for carrying out the function of positive safety even in case of malfunctions of the thermo-sensitive elements (1). Said thermo-sensitive elements (1) comprise a membrane (1) filled with a expansible liquid vacuum inserted, to a temperature of about -40°C, so that it is already partially expanded at room temperature. Such positive safety means comprise: - a rocker (2) located underneath said membrane (1), - an elastic element (3) associated to said rocker (2) and adapted to keep it continuously in contact with said pre-expanded membrane (1), by operating in contrast with the movement of such membrane (1) caused by the expansion or contraction thereof, - an actuating stem (7), actuated by said rocker (2) in case of breakage of said thermo-sensitive elements that cause the loss of the pre-expansion of said membrane (1), the lower end (7.1) of said actuating stem (7) acting on the underlying arm (8) in order to open said electrical contacts (8.1, 8.2) permanently and irreversibly.