METHOD FOR DETERMINING THE SIZE OF A LEAK

摘要

The invention relates to a method for determining the leak in a tank device containing a liquid on a vehicle, in particular, a motor vehicle, wherein the liquid affects the pressure in the tank device as a result of evaporation, comprising the following steps: generating a first pressure in the tank device as reference pressure at a first time (t₁), recording a first resulting pressure curve to a second time (t₂), generating a second pressure at a third time (t₄), the first pressure and the second pressure being selected to be different, recording a second resulting pressure curve to a fourth time (t₅), determining the pressure gradient of the first pressure curve to the second time (t₂) and the pressure gradient of the second pressure curve to the third time (t₄), determining a first pressure difference between the pressure at the second time (t₂) and reference pressure, determining a second pressure difference between the pressure at the third time (t₄) and the reference pressure, calculating the size of the leak depending on the determined pressure gradients and pressure differences and the assumption that the evaporation rate in the tank device is constant and that a leak rate results which is proportional to the root of the corresponding pressure difference.