| abstract |
The invention relates to a method for determining at least one physical property of a gas in at least one measuring gas chamber (132), in particular for determining an oxygen concentration in the exhaust gas of an internal combustion engine. To this end, a sensor element (114) is used, which comprises at least one first electrode (120) and at least one second electrode (126), and at least one solid electrolyte (122), which connects the first electrode (120) and the second electrode (126). The first electrode (120) and the second electrode (126) are connected to the measuring gas chamber (132) such that gas from the measuring gas chamber (132) can be applied to said electrodes. The method comprises the following steps: at least one first pumping voltage is applied between the first electrode (120) and the second electrode (126), and at least one first pumping current is measured between the first electrode (120) and the second electrode (126); at least one second pumping voltage is applied between the first electrode (120) and the second electrode (126), and at least one second pumping current is measured between the first electrode (126) and the second electrode (126), wherein said second pumping voltage has a polarity inverse to said first pumping voltage. A unique measured variable, from which the physical property is concluded, is calculated using at least one linear combination of a maximum of the first pumping current and the second pumping current with a minimum of the first pumping current and the second pumping current. |