For example, in the case where a concentration of moisture contained in the exhaust gas is measured by a non-dispersive infrared absorption (NDIR) method, the exhaust gas is cooled and the moisture is condensed, and this results in an erroneous measurement value different from that of the original one. In order to prevent such an erroneous measurement, a sampling line up to reach the moisture concentration meter is heated in some cases (JP2002-340778A).
In this configuration, it is configured that the temperature of the exhaust gas in the sampling line is regulated to be equal to or higher than 100° C. to thereby prevent the moisture contained in the exhaust gas from being condensed. Further, even in the case where only the concentration other than the moisture contained in the exhaust gas is measured, when the concentration of the moisture is largely changed, the measurement accuracy of the other components is affected. Therefore, it is configured so that the temperature of the exhaust gas in the sampling line is also regulated to be equal to or higher than 100° C.
However, since the vehicle mounted type exhaust gas analyzing apparatus uses, for example, a battery of the vehicle as a power supply source thereof and the power capacity is limited. Therefore, in the case where a large power consumption occurs in such a temperature regulation mechanism, an operational time of the exhaust gas analyzing apparatus is extremely limited and it is difficult to perform a sufficient exhaust gas analysis.