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US 4,231,733 AGranted
Combined O.sub.2 /combustibles solid electrolyte gas monitoring device
AssigneeWestinghouse Electric Corp.
InventorsWilliam M. Hickam, Ching-Yu Lin, John M. Zomp
Life of this patent
Estimating the term…
Abstract
A circuit means in combination with a conventional oxygen ion conductive solid electrolyte cell establishes the cell in a voltage mode for the purposes of measuring excess oxygen and developing a voltage signal indicative thereof, and switching the cell to a current mode of operation in response to an excess combustible environment wherein current drawn by the cell to pump oxygen for combustible reaction with the excess combustibles environment is measured as an indication of the combustibles content of the gas.
Claims6
An oxygen/combustibles monitoring apparatus for generating a voltage signal indicative of the oxygen content of an excess oxygen condition in a monitored gas environment and a current signal indicative of the combustibles content of an excess combustibles content in a monitored gas environment, comprising:
- an oxygen ion conductive solid electrolyte cell having first and second electrodes, said first electrode being exposed to the monitored gas environment, said second electrode being isolated from said monitored gas environment and exposed to an oxygen reference environment;
- an electronic circuit means connected to said first and second electrodes, said electronic circuit means including a voltage measuring circuit and a current measuring circuit, said current measuring circuit including a constant voltage source and a current measuring means, and switching means for alternatively connecting said voltage measuring circuit and said current measuring circuit to said first and second electrode in response to a predetermined difference in oxygen partial pressure at said first and second electrodes;
- said predetermined difference being set such that said voltage measuring means is operatively connected to said first and second electrodes during an excess oxygen condition of the monitored gas environment, an EMF signal generated by said solid electrolyte electrochemical cell as measured by said voltage measuring means being indicative of
- the oxygen content of said monitored gas environment;
- said predetermined difference being such that said current measuring circuit is connected to said first and second electrodes during an excess combustibles condition of the monitored gas environment, said constant voltage source of said current measuring circuit maintaining a preset voltage level across said solid electrolyte electrochemical cell, said predetermined difference corresponding to a change in said monitored gas environment from an excess oxygen condition to an excess combustibles condition, said solid electrolyte electrochemical cell drawing current from said constant voltage source to transfer oxygen from said oxygen reference environment at said second electrode to said first electrode to combustibly react with said excess combustibles at said first electrode, the level of current required to transfer oxygen being measured by said current measuring means, said current being indicative of the combustibles content of said monitored gas environment.
2 more elements
In a fuel/air control system for controlling the fuel/air ratio of a combustion system in response to the fuel/air content of a monitored gas environment, the combination of:
- an oxygen ion conductive solid electrolyte cell having first and second electrodes, said first electrode being exposed to the monitored gas environment, said second electrode being isolated from said monitored gas environment and exposed to an oxygen reference environment;
- an electronic circuit means connected to said first and second electrodes, said electronic circuit means including a voltage measuring circuit and a current measuring circuit, said current measuring circuit including a constant voltage source and a current measuring means, and switching means for alternatively connecting said voltage measuring circuit and said current measuring circuit to said first and second electrode in response to a predetermined difference in oxygen partial pressure at said first and second electrodes;
- said predetermined difference being set such that said voltage measuring means is operatively connected to said first and second electrodes during an excess oxygen condition of the monitored gas environment, an EMF signal generated by said solid electrolyte electrochemical cell as measured by said voltage measuring means being indicative of the oxygen content of said monitored gas environment;
- said predetermined difference being such that said current measuring circuit is connected to said first and second electrodes during an excess combustibles condition of the monitored gas environment, said constant voltage source of said current measuring circuit maintaining a preset voltage level across said solid electrolyte electrochemical cell, said predetermined difference corresponding to a change in said monitored gas environment from an excess oxygen condition to an excess combustibles condition, said solid electrolyte electrochemical cell drawing current from said constant voltage source to transfer oxygen from said oxygen reference environment at said second electrode to said first electrode to combustibly react with said excess combustibles at said first electrode, the level of current required to transfer oxygen being measured by said current measuring means, said current being indicative of the combustibles content of said monitored gas environment;
- and
- a fuel/air control means operatively connected to said electronic circuit means and responsive to output signals thereof to control the fuel/air ratio of a combustion system.
3 more elements
Dependencies are inferred from the claim text.