Mass flow controller

Claim 1

An apparatus for controlling the mass flow of a gas through a conduit, said apparatus comprising: a housing having therethrough a longitudinal passage and to be connected to a conduit such that an inlet end of said passage receives gas from the conduit and an outlet end of said passage discharges gas to the conduit; at least one by-pass within said passage adjacent said inlet end thereof for passing therethrough the gas; a mass flow sensor positioned within said passage adjacent the outlet of said by-pass for sensing the mass flow of the gas passing through said by-pass and for generating a signal representative thereof; a flow regulating valve positioned within said passage adjacent said outlet end thereof, said valve comprising a member defining an orifice communicating with said outlet end, and an armature positioned between said sensor and said orifice defining member and having a seal member directed toward said orifice, said armature being movable longitudinally within said passage between a closed position whereat said seal member blocks said orifice and opened positions whereat said seal member is spaced from said orifice; an electromagnetic coil within said housing at a position surrounding said armature; automatic control circuit means, connected to said sensor for receiving said signal therefrom and connected to said electromagnetic coil, for energizing said electromagnetic coil to generate a field to move said armature between said closed and open positions thereof, and thereby for controlling the flow of gas through said orifice as a function of the mass flow of gas detected by said sensor; and means for selectively adjusting the respective longitudinal positions of said orifice defining member and said electromagnetic coil within said housing.

Claim 2

An apparatus for controlling the mass flow of a gas through a conduit, said apparatus comprising: a housing having therethrough a longitudinal passage and to be connected to a conduit such that an inlet end of said passage receives gas from the conduit and an outlet end of said passage discharges gas to the conduit; at least one by-pass within said passage adjacent said inlet end thereof for passing therethrough the gas; a mass flow sensor positioned within said passage adjacent the outlet of said by-pass for sensing the mass flow of the gas passing through said by-pass and for generating a signal representative thereof; a flow regulating valve positioned within said passage adjacent said outlet end thereof, said valve comprising a member defining an orifice communicating with said outlet end, and an armature positioned between said sensor and said orifice defining member and having a seal member directed toward said orifice, said armature being movable longitudinally within said passage between a closed position whereat said seal member blocks said orifice and opened positions whereat said seal member is spaced from said orifice; an electromagnetic coil within said housing at a position surrounding said armature; automatic control circuit means, connected to said sensor for receiving said signal therefrom and connected to said electromagnetic coil, for energizing said electromagnetic coil to generate a field to move said armature between said closed and open positions thereof, and thereby for controlling the flow of gas through said orifice as a function of the mass flow of gas detected by said sensor; and means for selectively adjusting the respective longitudinal positions of said orifice defining member and said electromagnetic coil within said housing.