Patent ID: 8706343

Claim:
A method for detecting leaks in a tank system, wherein the presence of leaks is inferred from pressure changes in the tank system in response to externally caused pressure fluctuations, wherein the effect of the temperature in the tank system is taken into account in that an expected pressure change in the tank system for a predetermined leak size is determined as a function of the temperature, and the presence of leaks is inferred from the comparison of an actual pressure change to the expected pressure change, wherein in order to determine the expected pressure change the following steps are involved: determining, by a control system, the equilibrium vapor pressure as the partial pressure of the fuel (HC) Δ HCequi at a given temperature, determining, by the control system, the deviation between Δ HCequi and a modeled partial pressure of the fuel Δ HC , determining, by the control system, an evaporation rate of the fuel from the deviation between Δ HCequi and Δ HC , determining, by the control system, the net evaporation rate as the difference between the evaporation rate and a modeled HC leak flow, integrating, by the control system, the net evaporation rate over the time for determining the vaporous HC mass, determining, by the control system, the modeled partial pressure Δ HC from the vaporous HC mass at a given volume and given temperature and determining, by the control system, the modeled HC leak flow on the basis of the modeled Δ HC at a given partial pressure of the air Δ air at a predetermined leak size.