US 2002/0116994 A1 · Method and apparatus for determining a zero gas flow state in a bidirectional gas flow conduit

Abstract

A method and apparatus for determining a state of zero gas flow in a conduit, the zero flow state occurring between a first period in which gas flows in one direction in the conduit and a subsequent, second period in which gas flows in the opposite direction in the conduit. A first signal responsive to gas flow in the conduit is obtained. The first signal has one polarity when the gas flow is in one direction in the conduit and the opposite polarity when the gas flow is in the opposite direction. A second signal responsive to the gas flow in the conduit is also obtained. The second signal has the same polarity for either direction of gas flow in the conduit. The derivatives of the first and second signals are taken at successive points in time to determine when the signs of the derivatives of the first and second signals are present in a first predetermined combination of signs. A second point in time, subsequent to the first point, when the signs of the derivatives exhibit a second predetermined combination of signs different from the first combination is determined. This may occur when the sign of the derivative of the second signal changes with respect to the sign of the derivative of the first signal. The point at which this occurs is identified a state of zero gas flow in the conduit.

Claims30

Dependent claims

A method for determining a state of zero gas flow in a conduit, the zero gas flow state occurring between a first period in which gas flows in one direction in the conduit and a subsequent, second period in which gas flows in the opposite direction in the conduit, said method comprising the steps of:

obtaining a first signal responsive to gas flow in the conduit, the first signal having one polarity when the gas flow is in one direction in the conduit and the opposite polarity when the gas flow is in the opposite direction in the conduit;
obtaining a second signal responsive to gas flow in the conduit, said second signal having the same polarity for either direction of gas flow in the conduit;
obtaining the derivatives of the first and second signals at successive points in time;
determining that the signs of the derivatives of the first and second signals are present in a predetermined combination of signs;
when the derivatives have the first predetermined combination of signs, thereafter determining a first point in time at which the sign of the derivative of the second signal becomes opposite to its sign in the predetermined combination and the sign of the derivative of the first signal remains the same as its sign in the predetermined combination;
identifying a second point in time, prior to first point, as a state of zero gas flow in the conduit.

3 more elements

Apparatus for determining a state of zero gas flow in a conduit, the zero gas flow state occurring between a first period in which gas flows in one direction in the conduit and a subsequent, second period in which gas flows in the opposite direction in the conduit, said apparatus comprising:

a first gas flow sensor for obtaining a first signal responsive to gas flow in the conduit, the first signal having one polarity when the gas flow is in one direction in the conduit and the opposite polarity when the gas flow is in the opposite direction in the conduit;
a second gas flow sensor for obtaining a second signal responsive to gas flow in the conduit, said second signal having the same polarity for either direction of gas flow in the conduit;
means for obtaining the derivatives of the first and second signals at successive points in time and for determining their signs;
means for determining that the signs of the derivatives of the first and second signals are present in a predetermined combination of signs and thereafter determining a first point in time at which the sign of the derivative of the second signal becomes opposite to its sign in the predetermined combination and the sign of the derivative of the first signal remains the same as its sign in the predetermined combination, said means identifying a second point in time, prior to first point, as a state of zero gas flow in the conduit.

1 more element

Dependencies are inferred from the claim text.

Method and apparatus for determining a zero gas flow state in a bidirectional gas flow conduit

Life of this patent

Method and apparatus for determining a zero gas flow state in a bidirectional gas flow conduit

Life of this patent

Abstract

Claims30