Control unit for controlling the delivery of a combustible gas in valve units, particularly for water heating apparatuses, and valve unit including said unit

Abstract

A control unit is provided for controlling the delivery of a combustible gas in a valve unit of the type having a valve for shutting off the gas which is subject to the operational control of a magnetic safety unit with a thermocouple. The control unit includes an electronic circuit assembly arranged for connection to a sensor adapted to detect the presence of inflammable vapours or other dangerous substances. The circuit assembly is supplied by an electric power generator. The circuit assembly has an electronic type switch, acting on the electric circuit for supplying the magnetic safety unit so as to interrupt the circuit and operate the valve for closure in the presence of inflammable vapours detected by the sensor.

1 . A control unit for controlling the delivery of a combustible gas in a valve unit of the type having valve means for shutting off the gas which is subject to the operational control of a magnetic safety unit with a thermocouple, the control unit comprising: an electronic circuit assembly arranged for connection to sensor means adapted to detect the presence of inflammable vapours or other dangerous substances, said circuit assembly being supplied by electric power generating means, the circuit assembly having an electronic type switch acting on the electric circuit for supplying the magnetic safety unit so as to interrupt said circuit and operate said valve means for closure in the presence of inflammable vapours detected by said sensor means.  
   
   
       2 . The control unit according to  claim 1 , wherein said electric power generating means having thermopile means supplied by a flame of a pilot burner associated with said valve unit.  
   
   
       3 . The control unit according to  claim 1 , wherein said electric power generating means is of the type with battery, and the circuit assembly is arranged to be electrically supplied exclusively by said generating means with battery.  
   
   
       4 . The control unit according to  claim 1 , wherein said sensor means having transducer means adapted to transform the signal indicating the presence of inflammable vapours into an electrical magnitude sent to the circuit assembly, said circuit assembly having comparison means for comparing the value of such a magnitude with a preset threshold value and consequently sending an operating signal (S) for opening said electronic switch, whenever the value of said magnitude is above the threshold value set.  
   
   
       5 . The control unit according to  claim 4 , wherein said magnitude is an ohmic resistance (R).  
   
   
       6 . The control unit according to  claim 2 , wherein the resistive part of the electronic circuit assembly is electrically supplied by said thermocouple.  
   
   
       7 . The control unit according to  claim 1 , wherein said electronic switch is of a low resistance type and is connected in series with the thermocouple and the magnetic unit in said electric circuit.  
   
   
       8 . The control unit according to  claim 1 , wherein said electronic switch is of the type with MOSFET transistor.  
   
   
       9 . The control unit according to  claim 2 , further comprising electric power generating means with battery which is arranged for electrically supplying the circuit assembly, limited in a phase of ignition of the pilot burner and until the power produced by the thermopile generating means is sufficient to supply the electronic circuit assembly.  
   
   
       10 . The control unit according to  claim 2 , wherein said generating means with battery is electrically connected to an igniter device for lighting the flame of the pilot burner to provide sufficient power to said igniter device in the flame ignition phase.  
   
   
       11 . The control unit according to  claim 10 , wherein said igniter device is controlled by said circuit assembly to be disabled in the presence of inflammable vapours detected by said sensor means.  
   
   
       12 . The control unit according to  claim 2 , wherein an igniter device for lighting the flame at the pilot burner is provided, and operated independently of the circuit assembly.  
   
   
       13 . The control unit according to  claim 12 , wherein said igniter device is of the piezoelectric type.  
   
   
       14 . A valve unit for the delivery of a combustible gas, particularly in water heating apparatuses, comprising a control unit for controlling the delivery of the gas according to  claim 1.