Electro-pilotstatic valve for gas burners

Abstract

The object of the present invention is hence an electro-actuator ( 1 ) for gas cooktops or the like, piloted by actuating means, comprising at least one safety electromagnet ( 4 ) forming part of a pilotstat, at least one cut-off means ( 2 ) of the fuel gas, substantially a sleeve provided with an outlet channel ( 22 ) and a conduit ( 23 ) of the fuel gas, of at least one safety shutter ( 20 ) whereon a pushing/pulling force (F F ) acts that operates the safety closing of said outlet channel ( 22 ), at least a service shutter ( 20 ), and a support structure ( 10 ) provided with a cavity ( 100 ) within which a stem ( 21 ) is placed sliding, whereto at least one ferromagnetic element ( 32 ) cooperating with said safety electromagnet ( 4 ) and said shutter ( 20 ) cooperating with the cut-off means ( 2 ) of the fuel gas are constrained, where said safety shutter ( 20 ) and said service shutter ( 20 ) coincide in a same shutter ( 20 ); said ferromagnetic element ( 32 ) being anchored to said safety electromagnet ( 4 ) through an anchoring force (F P ) of mutual attraction that arises when said safety electromagnet ( 4 ) is electrically powered, in particular through the flame sensor of pilotstat, characterised in that: said pressing/pulling force (F F ) is of magnetic nature and susceptible to be won by the command forces (F S ) exerted for the opening of said outlet channel ( 22 ) and by said anchoring force (F P ).

1 . Electro-actuator ( 1 ) for gas cooktops or the like, piloted by actuating means, comprising at least one safety electromagnet ( 4 ) forming part of a pilotstat, at least one cut-off means ( 2 ) of the fuel gas, substantially a sleeve provided with an outlet channel ( 22 ) and a conduit ( 23 ) of the fuel gas, of at least one safety shutter ( 20 ), cooperating with said cut-off means ( 2 ) of the fuel gas, whereon a force (FF) acts that operates the safety closing of said outlet channel ( 22 ), at least a service shutter ( 20 ), where said safety shutter ( 20 ) and said service shutter ( 20 ) coincide in a same shutter ( 20 ), and a support structure ( 10 ) provided with a cavity ( 100 ) within which a stem ( 21 ) is placed sliding, where one end of said stem ( 21 ) is provided with at least one ferromagnetic element ( 32 ) that cooperates with said safety electromagnet means ( 4 ), while the other end of the stem ( 21 ) is integral with said shutter ( 20 ); said ferromagnetic element ( 32 ) being anchored to said safety electromagnet ( 4 ) through an anchoring force (FP) of mutual attraction that arises when said safety electromagnet ( 4 ) is electrically powered, in particular through the flame sensor of pilotstat, 
       I. characterised in that:
 said force (FF), that operates the safety closing of said outlet channel ( 22 ), is of magnetic nature and susceptible to be won by a command force (FS) exerted for the opening of said outlet channel ( 22 ) and by said anchoring force (FP); 
 wherein said force (FF), that operates the safety closing of said outlet channel ( 22 ), is given by the magnetic mutual attraction between a cursor ( 30 ) placed on said stem ( 21 ) and a bottom ( 101 ) placed in said cavity ( 100 ); 
 wherein said force (FF), that operates the safety closing of said outlet channel ( 22 ), achieves and ensures the closing of the electro-actuator ( 1 ), engaging the shutter ( 20 ) at the mouth of the outlet channel ( 22 ) of the fuel gas, so as to occlude it. 
 
     
     
         2 . Electro-actuator ( 1 ) according to  claim 1 , wherein the instant position (X) of said cursor ( 30 ) in relation to said bottom ( 101 ) varies between a minimum value (Xmin), in correspondence of which said outlet channel ( 22 ) is closed, and a maximum value (Xmax), in correspondence of which said outlet channel ( 22 ) is open, characterised in that:
 the force of mutual attraction (FF) between said cursor ( 30 ) and said bottom ( 101 ) is variable as a function of the instant position (X), and such that said force is maximum (FF=FF_MAX) when the instant position is minimum (X=Xmin); while this force is minimum (FF=FF_min) when the instant position is maximum (X=Xmax);   the anchoring force (FP) between the ferromagnetic element ( 32 ) and the electromagnet ( 4 ) is variable as a function of the instant position (X), and such that said force is maximum (FP=FP MAX) when the instant position is maximum (X=Xmax), while the said force is minimum (FP=FP_min) when the instant position is minimum (X=Xmin);   
       II. and characterised in that:
 said maximum anchoring force (FP=FP_MAX) is greater than the minimum mutual attraction force (FF=FF_min) between said cursor ( 30 ) and said bottom ( 101 ); 
 said maximum mutual attraction force (FF=FF MAX) between said cursor ( 30 ) and said bottom ( 101 ) is greater than said minimum anchoring force (FP=FP_min). 
 
     
     
         3 . Electro-actuator ( 1 ) according to  claim 1 , wherein said bottom ( 101 ) comprises a ferromagnetic element and said cursor ( 30 ) comprises a permanent magnet. 
     
     
         4 . Electro-actuator ( 1 ) according to  claim 1 , wherein said bottom ( 101 ) comprises a permanent magnet and said cursor ( 30 ) comprises a ferromagnetic element. 
     
     
         5 . Electro-actuator ( 1 ) according to  claim 1 , wherein said bottom ( 101 ) comprises a permanent magnet and said cursor ( 30 ) comprises a permanent magnet. 
     
     
         6 . Electro-actuator ( 1 ) according to  claim 1 , where for the opening of the outlet channel ( 22 ), that is for the switching on of the burner, through a manual or automatic action, the ferromagnetic element ( 32 ) of the stem ( 21 ) with the safety electromagnet ( 4 ) are brought into contact and kept integral at least until the activation of said safety electromagnet ( 4 ) subsequent to the switching on of the burner. 
     
     
         7 . Electro-actuator ( 1 ) according to  claim 1 , where for the opening or the voluntary closure of the outlet channel ( 22 ), that is for the voluntary switching on and off of the burner, the user manually couples and uncouples said ferromagnetic element ( 32 ) of said stem ( 21 ) with said electromagnet ( 4 ) through said actuation means. 
     
     
         8 . Electro-actuator ( 1 ) according to  claim 1 , further comprising at least a solenoid means ( 33 ) cooperating with said cursor ( 30 ) through a suitable magnetic field, so as to achieve the opening or the voluntary closure of the outlet channel ( 22 ), that is the voluntary switching on or switching off of the burner, through electrical supply to said solenoid ( 33 ). 
     
     
         9 . Electro-actuator ( 1 ) according to  claim 8 , wherein said command force (FS) is the resultant of the forces generated by the solenoid ( 33 ) acting on said cursor ( 30 ), the direction and intensity whereof depend on the sign and intensity of the current circulating through the coils of the solenoid ( 33 ); said command force (FS) being characterized in that:
 to command the opening of said outlet channel ( 22 ) said command force (FS=FS_MAX(+)) is greater than said maximum mutual attraction force (FF=FF_MAX);   to command the closing of said outlet channel ( 22 ) the sum of the command force (FS=FS_MAX(−)) and the minimum mutual attraction force (FF=FF_min) is greater than the maximum anchoring force (FP=FP_MAX).   
     
     
         10 . Electro-actuator ( 1 ) according to  claim 9 , where for the opening of the outlet channel ( 22 ), that is for the switching on of the burner, the user, through said actuating means, activates the electrical supply to said solenoid ( 33 ), which remains energized at least until the activation of said electromagnet ( 4 ) subsequent to the switching on of the burner. 
     
     
         11 . Electro-actuator ( 1 ) according to  claim 8 , wherein said cursor ( 30 ) is a permanent magnet and for the voluntary closure of the outlet channel ( 22 ), that is for the voluntary switching off the user, through said actuating means, activates the electrical supply to the solenoid ( 33 ), reversing the polarity of said solenoid ( 33 ) with respect to that provided for the opening of the outlet channel ( 22 ), that is for the switching on of the burner. 
     
     
         12 . Electro-actuator ( 1 ) according to  claim 8 , wherein said solenoid ( 33 ) can be fed with a square wave with duty cycle. 
     
     
         13 . Electro-actuator ( 1 ) according to  claim 7 , wherein said cursor ( 30 ) is a ferromagnetic element and for the voluntary closure of the outlet channel ( 22 ), that is for the voluntary switching off, the user, through the actuating means, cuts off the electrical supply to the safety electromagnet ( 4 ). 
     
     
         14 . Electro-actuator ( 1 ) according to  claim 13 , wherein said cut-off of the electrical supply to the electromagnet ( 4 ) takes place by closing a by-pass circuit of the electromagnet ( 4 ). 
     
     
         15 . Electro-actuator ( 1 ) according to  claim 13 , wherein said cut-off of the electrical supply to the electromagnet ( 4 ) takes place through a normally closed microswitch on the circuit of the safety electromagnet ( 4 ), which the user opens to cut-off the electric current. 
     
     
         16 . Electro-actuator ( 1 ) according to  claim 1 , characterised in that it further comprises an interference membrane ( 230 ) placed in the proximity of said stem ( 21 ) inside the said conduit ( 23 ) of the fuel gas. 
     
     
         17 . Cooktop with blown burners that use the electro-actuator ( 1 ) according to  claim 1 . 
     
     
         18 . Electro-actuator ( 1 ) according to  claim 8 , wherein said cursor ( 30 ) is a ferromagnetic element and for the voluntary closure of the outlet channel ( 22 ), that is for the voluntary switching off, the user, through the actuating means, cuts off the electrical supply to the safety electromagnet ( 4 ). 
     
     
         19 . Electro-actuator ( 1 ) according to  claim 18 , wherein said cut-off of the electrical supply to the electromagnet ( 4 ) takes place by closing a by-pass circuit of the electromagnet ( 4 ). 
     
     
         20 . Electro-actuator ( 1 ) according to  claim 18 , wherein said cut-off of the electrical supply to the electromagnet ( 4 ) takes place through a normally closed microswitch on the circuit of the safety electromagnet ( 4 ), which the user opens to cut-off the electric current.