Device for controlling the supply of fuel gas to a burner , in particular for water heater appliances

Abstract

A device for controlling a gas supply to a burner includes a main duct, which is provided with at least one main valve including a valve seat and associated shutter with a control for opening the seat in opposition to a resilient recall member. A pilot duct leads from the main duct to supply a pilot burner, the main duct includes a magnetic thermoelectric safety unit which is manually or automatically armed, acting on the pilot duct to enable gas to flow to the pilot burner when armed. The pilot duct includes a pressure regulator having a shutter with a membrane control, the membrane subject to pressure regulated by the regulator and to a calibration pressure determined in a calibration chamber of the regulator. The device includes a fluid connector between the calibration chamber and the main valve to provide a pressure signal correlated with the gas supply pressure.

1 . A device for controlling the supply of fuel gas to a burner comprising:
 a main duct for supplying the gas between an inlet section and an outlet section,   the main duct being provided with at least one main valve including a respective valve seat associated with a corresponding shutter with a respective control for opening of the seat in opposition to a respective resilient recall member,   a pilot duct for supplying a pilot burner leading from the main duct upstream of at least the one main valve,   the main duct being provided, upstream of at least the one main valve, with a magnetic thermoelectric safety unit with a manually armed switch or with an automatic arming system, which acts on the pilot duct to enable the gas to flow to the pilot burner when the unit is armed,   the pilot duct being provided with a pressure regulator having a shutter with a membrane control, the membrane being subject on one hand to the pressure regulated by the regulator and on the other hand to a calibration pressure determined in a calibration chamber of the regulator, a calibration spring being provided in the chamber and acting on the membrane, and   a fluid connector between the calibration chamber of the pressure regulator and at least the one main valve, in order to supply to the calibration chamber a pressure signal correlated with the gas supply pressure when supplied to the main duct such that the pressure regulated by the regulator can be regulated at least to a first level, when there is no gas supply in the main duct, and to a second level, greater than the first level, when gas is being supplied in the main duct, the flow of gas supplied to the pilot duct being correlated with the respective levels of the pressure signal supplied to the calibration chamber.   
     
     
         2 . The device according to  claim 1 , wherein the fluid connector comprises a connection duct extending between the calibration chamber and a section of the main supply duct downstream of the valve seat of at least the one main valve with respect to the direction of flow of the gas, the pressure signal supplied to the calibration chamber corresponding to the gas supply pressure obtained through the main valve. 
     
     
         3 . The device according to  claim 1 , wherein at least the one main valve comprises a respective control electrovalve with a mechanical or electric operator to control opening/closing of the main valve, the electrovalve configured to open/close a drive duct of a respective servo-assisted drive circuit so as indirectly to control, by the membrane control, the respective shutter of the corresponding valve, the respective duct of the drive circuit bringing the main duct into fluid communication with a respective drive chamber of the main valve, one side of the membrane of the membrane control being subject to pressure in the respective drive chamber, the fluid connector comprising a duct connecting the calibration chamber of the pressure regulator and a section of the drive duct of the valve, the section being disposed between the electrovalve and the drive chamber. 
     
     
         4 . The according to  claim 2 , wherein the pressure signal supplied to the calibration chamber of the regulator, by the connection duct, is correlated with a regulated gas supply pressure supplied to the burner when the main valve is in an open position. 
     
     
         5 . The device according to  claim 3 , wherein the pressure signal supplied to the calibration chamber of the regulator, by the connection duct, is correlated with a regulated gas supply pressure supplied to the burner when the main valve is in an open position.