Dual-valve air-gas controller

Claim 1

A dual-valve controller adapted to mix incoming air and gas derived from air and gas sources to produce a combustible output mixture and to adjust the flow rate of the output mixture without altering the air-gas ratio, said controller comprising: (A) a mixing chamber yielding said output mixture; (B) an air-control valve whose input is coupled to the air source and whose output is coupled to said chamber to supply air thereto at a flow rate which depends on the extent to which this valve is open; (C) a gas-control valve whose input is coupled to the gas source and whose output is coupled to said chamber to supply air thereto at a flow rate which depends on the extent to which this valve is open, said gas-control valve being in parallel relation to said air-control valve; (D) means including a single control element coupled both to said air control and said gas control valve to concurrently operate these valves from an initially closed state to a fully open state whereby the flow rate of the output mixture yielded by the chamber may be varied progressively, said means including a circular cam block coupled to said control element and turned thereby, said block having an indented inner face defining upper and lower cam surfaces, said valves each having an axially displaceable valve element and provided with a cam follower which engages a respective cam surface, the upper cam surface having a depth relative to the inner face which is at a maximum value at one end of the block and is at a minimum value at the other end thereof, said lower cam surface having the reverse configuration whereby when the block is turned, both cam followers are concurrently displaced axially to progressively open their associated valves as the maximum setting of the controller is approached.