| 摘要 |
<P>PROBLEM TO BE SOLVED: To highly accurately discriminate whether or not a liquid reducing agent is an empty, normal or dissimilar aqueous solution, by using a concentration sensor for indirectly measuring the concentration of the liquid reducing agent from a heat transfer characteristic between closely adjacent two points. <P>SOLUTION: Whether or not the liquid reducing agent is the empty, normal or dissimilar aqueous solution is discriminated on the basis of the concentration of the liquid reducing agent measured from an output signal of the concentration sensor every time when a measuring trigger signal is outputted with every predetermined time after starting an engine. When an idle discrimination or a dissimilar discrimination is made, whether or not its discrimination is proper is determined in response to a state of the liquid reducing agent. When the idle discrimination or the dissimilar discrimination is proper, an idle discrimination frequency or a dissimilar discrimination frequency of making the idle discrimination or the dissimilar discrimination is counted. When the idle discrimination frequency or the dissimilar discrimination frequency becomes a first predetermined frequency or more (S71, and S73), an idle discrimination fixing signal or a dissimilar discrimination fixing signal for indicating that its discrimination is fixed, is outputted (S72, and S74). <P>COPYRIGHT: (C)2007,JPO&INPIT |
