Method for determining the quantity of reducing agent in a tank

摘要

A method for determining the quantity of reducing agent in a tank of a motor vehicle, including: a storage material in the tank for storing and releasing the reducing agent according to demand; a heating device to supply heat to release the reducing agent, and a control device for driving the heating device. After the motor vehicle is started, driving the heating device so that it delivers constant power during an initial phase over which the pressure inside the tank increases until it reaches a predetermined value. The heating device then regulating the pressure around a datum value; then measuring the time of the initial phase or the derivative of pressure with respect to time during this initial phase; and comparing the measured time against various calibrated values of the initial phase in order to determine the quantity of reducing agent in the tank.

主权项

1. Method for determining the quantity of a reducing agent in a tank of a system to reduce the quantity of NOx in the exhaust gases of a motor vehicle, said system including:
a storage material arranged in the tank and for storing and releasing the reducing agent reversibly according to a demand for the reducing agent which may vary over the course of time; a heating device designed to supply heat in order to release the reducing agent from the storage material, and a control device for driving the heating device in order to release the reducing agent, wherein the method includes the following steps: a) immediately after the motor vehicle is started, driving the heating device so that it delivers constant power during an initial phase over which the pressure inside the tank increases until it reaches a predetermined value, the driving of the heating device then being adapted in order to regulate the pressure around a datum value; b) measuring the time of the initial phase and the derivative of the pressure with respect to time during the initial phase; c) comparing the measured time of the initial phase, said derivative of the pressure with respect to time or a combination of both against a plurality of calibrated values of the initial phase according to the quantity of reducing agent in the tank in order to determine said quantity of reducing agent in said tank.