Method and apparatus for a zero-point stabilization of an exaust gas sensor

An apparatus for a thermal energy conversion by a gaseous fuel, comprising

• (a) an exhaust gas conduit through which exhaust gases produced by the combustion of fuel pass;
• (b) a branch conduit having
• (1) a first inlet communicating with said exhaust gas conduit for introducing exhaust gas into said branch conduit;
• (2) a second inlet for introducing fresh air into said branch conduit;
• and
• (3) an outlet through which gases exit said branch conduit;
• and
• (c) a regulating device for reducing pollutant components in the exhaust gas;
• said regulating device including
• (1) an exhaust gas sensor disposed in said branch conduit downstream of said first and second inlets as viewed in a direction of gas flow in said branch conduit toward said outlet;
• (2) a valve movable into a first position in which said valve maintains open said first inlet and maintains closed said second inlet and a second position in which said valve maintains open said second inlet and maintains closed said first inlet;
• and
• (3) operating means for periodically moving said valve into said first and into said second position for alternatingly exposing said exhaust sensor to a flow of exhaust gas and to a flow of fresh air for effecting a zero-point stabilization of said exhaust gas sensor.