| 摘要 |
PROBLEM TO BE SOLVED: To provide a liquid state detection device capable of determining a more accurate concentration abnormality, by determining the stationary state, based on the present concentration value of liquid stored in a liquid storing container and the concentration value detected just before. SOLUTION: A concentration conversion value Cn (present concentration value) is determined from a differential valueΔVmn of each voltage value of a heating resistor measured after energization start and after lapse of a fixed time. A differential value between a preceding concentration conversion value Cn (just prior concentration value) stored when preceding processing is performed and the present concentration value is calculated as a concentration fluctuation width (S102). If the value is larger than a threshold L determined beforehand as a reference of the stationary state, it is determined that urea aqueous solution is not in the stationary state (S111). If the urea aqueous solution is not in the stationary state, even if an abnormal state of the urea aqueous solution is detected, reliability of determination is heightened, since the opportunity (the number of times) of detection of an abnormal state is increased until determining to be in the abnormal state. COPYRIGHT: (C)2007,JPO&INPIT
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