Fuel property detecting device

A fuel property detecting device comprising:

• an electrode part that includes electrodes immersed in fuel and that is charged with or discharges an amount of electric charge which changes according to a concentration of alcohol contained in fuel between the electrodes;
• a voltage conversion part that is configured to convert the amount of electric charge, with which the electrode part is charged or which is discharged by the electrode part, into a detection voltage;
• a standard voltage application part that is configured to apply a standard voltage to the voltage conversion part;
• an amplifying part that is configured to amplify the detection voltage and to output the amplified detection voltage;
• a temperature detection means for detecting fuel temperature and for outputting a signal that is in accordance with the detected fuel temperature;
• a storage means for storing:
• a map indicating a relationship between capacitance of the electrode part and the fuel temperature;
• a coefficient of a temperature property indicating a relationship between electric conductivity of the electrode part and the fuel temperature;
• a past electric conductivity of the electrode part;
• and
• the fuel temperature detected by the temperature detection means at time of calculation of the past electric conductivity, as a past fuel temperature;
• a first calculation means for calculating the capacitance of the electrode part based on the amplified detection voltage outputted by the amplifying part;
• a second calculation means for calculating the concentration of alcohol contained in fuel based on:
• the capacitance calculated by the first calculation means;
• a present fuel temperature detected by the temperature detection means;
• and
• the map;
• a third calculation means for calculating a present electric conductivity of the electrode part based on the amplified detection voltage outputted by the amplifying part;
• a conductivity determination means for determining whether the present electric conductivity calculated by the third calculation means is equal to or larger than a predetermined electric conductivity;
• a fourth calculation means for calculating the relationship between the electric conductivity of the electrode part and the fuel temperature based on:
• the past electric conductivity;
• the past fuel temperature;
• the present electric conductivity calculated by the third calculation means;
• and
• the present fuel temperature;
• and
• an abnormality determination means for determining whether the electrode part is abnormal based on:
• the relationship between the electric conductivity of the electrode part and the fuel temperature calculated by the fourth calculation means;
• and
• the coefficient of the temperature property.