Proportional control valve for gas burners

Claim 2

A gas control valve providing proportional control of gas flow between an inlet and an outlet, said valve comprising: a diaphragm; on one side of said diaphragm a first chamber which is in communication with said inlet and, on the other side of said diaphragm, a second chamber; a throttle valve for controlling the passage of gas from said inlet to said outlet, said throttle valve having at least one movable member mechanically coupled to said diaphragm with the flow of gas through the throttle valve being thereby controllable as a function of the position of said diaphragm; electromotive means which is responsive to a control signal which alternates between first and second states at a substantially predetermined frequency and variable duty cycle; and pilot valve means controlled by said electromotive means for admitting gas from said inlet to said second chamber when said control signal is in said first state and for venting gas from said second chamber when said control signal is in said second state, said second chamber being sufficiently large in relation to the rate at which gas is admitted to and vented from said second chamber that fluctuations in the second chamber pressure at said frequency are substantially damped and the pressure in said second chamber is variable as a function of the duty cycle of sAid control signal whereby the gas flow through said valve is also variable as a function of the duty cycle of said control signal.

Claim 3

A gas control valve providing proportional control of gas flow between an inlet and an outlet, said valve comprising: a diaphragm; on one side of said diaphragm a first chamber which is in communication with said inlet and, on the other side of said diaphragm, a second chamber; a fully closable valve coupled to said diaphragm; a throttle valve for controlling the passage of gas from said inlet to said outlet, said throttle valve having at least one movable member mechanically coupled to said diaphragm through a lost motion connection, said throttle valve providing a predetermined minimum gas flow at the initial position of said member with the flow of gas through the throttle valve being thereafter controllable as a function of the position of said diaphragm; a first calibrated orifice for admitting gas from said inlet to said second chamber; a second calibrated orifice for venting gas from said second chamber; and a lever which can be oscillated between a first position in which said first orifice is blocked and said second orifice is open and a second position in which said second orifice is blocked and said first orifice is open; and electromotive means, responsive to a control signal which alternates between first and second states at a substantially predetermined frequency and variable duty cycle, for substantially synchronously rocking said lever between its first and second positions, said second chamber being sufficiently large in relation to the rate at which gas is admitted to and vented from said second chamber that fluctuations in the second chamber pressure at said frequency are substantially damped and the pressure in said second chamber is variable as a function of the duty cycle of said control signal whereby, after an initial flow of minimum volume is established, the gas flow through said valve is variable as a function of the duty cycle of said control signal.

Claim 4

A gas control valve providing proportional control of gas flow between an inlet and an outlet, said valve comprising: a diaphragm; on one side of said diaphragm a first chamber which is in communication with said inlet and, on the other side of said diaphragm, a second chamber; a fully closable valve coupled to said diaphragm; a throttle valve for controlling the passage of gas from said inlet to said outlet, said throttle valve having at least one movable member mechanically coupled to said diaphragm through a lost motion connection, said throttle valve providing a predetermined minimum gas flow at the initial position of said member with the flow of gas through the throttle valve being thereafter controllable as a function of the position of said diaphragm; a first calibrated orifice for admitting gas from said inlet to said second chamber; a second calibrated orifice for venting gas from said second chamber; and a lever which can be oscillated between a first position in which said first orifice is blocked and said second orifice is open and a second position in which said second orifice is blocked and said first orifice is open; and electromotive means, responsive to a control signal which alternates between first and second states at a substantially predetermined frequency and variable duty cycle, for substantially synchronously rocking said lever between its first and second positions, said second chamber being sufficiently large in relation to the rate at which gas is admitted to and vented from said second chamber that fluctuations in the second chamber pressure at said frequency are substantially damped and the pressure in said second chamber is variable as a function of the duty cycle of said control signal whereby, after an initial flow of minimum volume is established, the gas flow through said valve is variable as a function of the duty cycle of said control signal.

Claim 5

A gas control valve as in claim 2 wherein the throttle valve movable member is slidable on a rod extending from said diaphragm to an extent determined by a fixed stop on the rod.

Claim 6

A gas control valve as in claim 2 including a bypass around said throttle valve from the space between said fully closable valve and said throttle valve and said outlet.

Claim 7

A gas control valve as in claim 2 wherein said throttle valve movable member provides a predetermined minimum opening permitting a minimum flow suitable for ignition of a burner.

Claim 8

A gas control valve as in claim 2 wherein said throttle valve movable member includes a taper portion providing a progressively increasing throttle opening as said member is moved by said diaphragm.