Method for measuring the oxygen concentration in a gaseous mixture, especially for determining the percentage of oxygen in the exhaust gases of an internal or external combustion engine, and ionisation probes for carrying out the method

摘要

Method of measuring the oxygen concentration in a gaseous mixture in particular of determining the oxygen percentage in the exhaust gases of an internal combustion or external combustion engine, and ionization probes for carrying out this method. For determining the oxygen percentage in the exhaust gases of an internal combustion or external combustion engine, an ionization probe (1) is disposed in the path of the gases. This probe is supplied in parallel with an identical probe (2) traversed by the ambient air raised to the same temperature as the exhaust gases. The sum (13) of the currents picked up by the two probes is compared (14) either with a voltage proportional to the high voltage (17 to 19), or with a constant voltage (16), or with a constant current (16a), and, as a function of the difference, the high voltage (7) supplying the probes is controlled. In addition, the currents picked up by the probes are compared (10) and the result of the comparison enables the oxygen percentage to be determined. IMAGE