Patent ID: 7499814

Claim:
An apparatus for detecting a concentration and a remaining amount of a liquid reducing agent comprising: a sensing unit disposed in a storage tank that stores a liquid reducing agent for outputting a signal in relation to a concentration and a remaining amount of the liquid reducing agent based on a heat transfer characteristic between two points distant apart from each other; and a control unit that includes therein a built-in computer, wherein the control unit performs: outputting a measurement trigger at every moment of a predetermined time interval after starting of an engine; determining that a vehicle state is stable when a stop time for which a vehicle is continuously in a stationary state reaches the set determination time; calculating the concentration of the liquid reducing agent based on the signal from the sensing unit when the measurement trigger is output and when it is determined that the vehicle state is stable; and determining the remaining amount of the liquid reducing agent when the measurement trigger is output, based on the signal from the sensing unit, wherein the control unit calculates a deceleration of the vehicle and sets the determination time on the basis of the deceleration which was calculated.