Valve and system for controlling a gas burner

Abstract

A gas fire system comprises a gas valve ( 104 ), a spark generator ( 108 ) for igniting a gas flowing out of the gas valve ( 104 ), a microprocessor-based controller 106 for controlling the operation of the gas valve ( 104 ) and the spark generator ( 108 ) and a user interface ( 110, 112 ) for providing instructions to the controller ( 106 ). The gas valve ( 104 ) comprises a valve body ( 202 ) having a gas inlet ( 266 ), a main gas outlet ( 268 ) and a bore ( 212 ). The bore ( 212 ) has an interior surface ( 298 ) a part of which defines a gas flow cavity, the gas inlet ( 266 ) and the main gas outlet ( 268 ) being in communication with the gas flow cavity. The gas valve ( 104 ) further comprises a valve spindle ( 206 ) arranged to move into and out of the gas flow cavity, an exterior portion of the valve spindle forming a flow control surface ( 262 ) and defining a gap having a volume between the flow control surface ( 262 ) and the interior surface ( 298 ) of the gas flow cavity. Relative movement of the flow control surface ( 262 ) and the gas flow cavity varies the volume of the gap and regulates a flow of gas from the gas inlet ( 266 ) to the main gas outlet ( 268 ).

1 . A gas valve for controlling flow of gas to a gas burner, the valve comprising:
 a valve body having a gas inlet, a main gas outlet and a bore, the bore having an interior surface a part of which defines a gas flow cavity, the gas inlet and the main gas outlet being in communication with the gas flow cavity; and   a valve spindle having an exterior surface and a first seal, the exterior surface including means for receiving the first seal and a portion forming a flow control surface, the valve spindle being arranged to move into and out of the gas flow cavity, the flow control surface defining a gap having a volume between the flow control surface and the interior surface of the gas flow cavity, wherein relative movement of the flow control surface and the gas flow cavity varies the volume of the gap and is adapted to regulate a flow of gas from the gas inlet to the main gas outlet and wherein the first seal is adapted to form a seal with the interior surface of the gas flow cavity to prevent the flow of gas over the flow control surface.   
     
     
         2 . A gas valve as claimed in  claim 1 , wherein at least one of the flow control surface and the interior surface of the gas flow cavity are tapered. 
     
     
         3 . A gas valve as claimed in  claim 2 , wherein the at least one of the flow control surface and the interior surface of the gas flow cavity are frusto-conical. 
     
     
         4 . A gas valve as claimed in  claim 3 , wherein the flow control surface is frusto-conical and the interior surface of the gas flow cavity has a uniform circular diameter. 
     
     
         5 . A gas valve as claimed in  claim 3 , wherein the frusto-conical surface is inclined to an axis of the valve spindle at an angle of between 2.5° and 10°. 
     
     
         6 . A gas valve as claimed in  claim 1 , wherein the bore has a longitudinal axis and the relative movement of the flow control surface and the gas flow cavity is along the axis. 
     
     
         7 . A gas valve as claimed in  claim 6 , further comprising a linear motor for propelling the valve spindle along the axis. 
     
     
         8 . A gas valve as claimed in  claim 7 , wherein the linear motor and the valve spindle are each provided with cooperating threaded portions for attaching the motor to the valve spindle. 
     
     
         9 . A gas valve as claimed in  claim 7 , wherein the linear motor is mounted at a first end of the longitudinal bore. 
     
     
         10 . A gas valve as claimed in  claim 7 , wherein the valve spindle is provided with a second seal to prevent flow of gas to the motor. 
     
     
         11 . A gas valve as claimed in  claim 1 , wherein the first seal is adapted to cooperate with the interior surface of the gas flow cavity to prevent flow of gas from the gas inlet to the gas outlet. 
     
     
         12 . A gas valve as claimed in  claim 1 , wherein the valve body further comprises a pilot gas outlet in communication with the bore. 
     
     
         13 . A gas valve as claimed  claim 1 , wherein the valve body further comprises a low rate cross drilling bore between the gas flow cavity and the main gas outlet, for providing gas flow to provide a low rate flame. 
     
     
         14 . A gas valve as claimed in  claim 13 , further comprising means for adjusting the flow rate through the low rate cross drilling bore. 
     
     
         15 . A gas valve as claimed in  claim 14 , wherein the means for adjusting the flow rate through the low rate cross drilling bore is a low rate adjuster screw which projects into the low rate cross drilling bore. 
     
     
         16 . A gas valve as claimed in  claim 1  and further comprising a flame safety device for sealing the gas flow cavity to prevent flow of gas from the gas inlet to the main gas outlet. 
     
     
         17 . A gas valve as claimed in  claim 16 , wherein the flame safety device is mounted at a second opposed end of the longitudinal bore. 
     
     
         18 . A gas fire system, comprising:
 a gas valve as defined in  claim 1 ;   a spark generator for igniting a gas flowing out of the gas valve;   a microprocessor-based controller for controlling the operation of the valve spindle and the spark generator; and   a user interface for providing instructions to the controller.   
     
     
         19 . A gas fire system as claimed in  claims 18 , wherein the user interface is one of a wired and wireless user interface. 
     
     
         20 - 21 . (canceled)