Method and apparatus for gas flow control

摘要

A method and apparatus for self-calibrating control of gas flow. The gas flow rate is initially set by controlling, to a high degree of precision, the amount of opening of a flow restriction, where the design of the apparatus containing the flow restriction lends itself to achieving high precision. The gas flow rate is then measured by a pressure rate-of-drop upstream of the flow restriction, and the amount of flow restriction opening is adjusted, if need be, to obtain exactly the desired flow.

主权项

1. A gas flow control valve, comprising:
a first body maintained static in space and having a flow restriction surface and an annular extension formed on the flow restriction surface; a second body inside the first body and having a complementary flow restriction surface machined to be flat so as to form a perfect seal when urged against the annular extension, wherein the annular extension of the flow restriction surface and the complementary flat flow restriction surface cooperate to form flow restriction valve; a lower flexure part forming a seal shaped as a round disk extending from the second body and coupling the first body and the second body and a second flexure part positioned above the lower flexure part and coupling the first body and the second body, wherein the lower flexure part and the second flexure part limit relative motion between the first body and the second body to vertical motion, thereby permitting only uniaxial motion between the first body and the second body; a lever connected to the second body; an actuator provided between the lever and a top portion of the first body, such that when the actuator expands, it raises the lever so as to raise the second body and elastically flex the lower and second flexure parts thereby inducing displacement between the first body and the second body; and, a displacement sensor installed in the first body to measure the displacement between the first body and the second body.