Method and apparatus for determining a zero gas flow state in a bidirectional gas flow conduit
US6681643B2 · kind B2 · utility
Assignee
Inventor
Key dates
| Filing date | Jan 31, 2002 |
| Grant date | Jan 27, 2004 |
| Priority date | — |
| Expiry date | Jan 31, 2022 |
Classification
- Technology area (CPC A)Human Necessities
- CPC primaryA61M2205/70
- WIPO fieldMedical technology
- WIPO sectorInstruments
Abstract
A method and apparatus for determining a state of zero gas flow in a conduit. A first gas flow signal has one polarity when gas flow is in one direction in the conduit and the opposite polarity when gas flow is in the opposite direction. A second gas flow 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 are present in a first predetermined combination of signs. A second point in time when the signs of the derivatives exhibit a second predetermined combination of signs different from the first combination is also determined. The combinations of signs are used to identify a state of zero gas flow in the conduit.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.