| 摘要 |
A magnetic wind oxygen sensing device provides a local magnetic field defined by magnetic pole pieces, and employs a plurality of thermal elements in a bridge in the local magnetic field to measure oxygen concentration in a surrounding gas mixture, creating a magnetic wind and determining the thermal effects induced in sensing elements as a result of the wind. A pair of sensing elements are positioned such that one lies upstream and one downstream of each wind generator, and both are substantially in thermal equilibrium with adjacent gas so they are unaffected by changes in thermal capacity of background gas components. When oxygen is present, the two sensing elements are passively cooled below, and heated above the temperature set by a local heater, respectively. In the absence of oxygen, the sensors reside at the same temperature, so they are self zero-ing, and this zero point does not shift when background gases with differing thermal characteristics are present. The arrangement is also immune to thermal creep and changes in physical position of the sensing elements that would otherwise introduce bridge asymmetries, offsets and drift artifacts.
|
