Patent ID: 8418525
Filing Date: 2013-04-16
Classification: B60K,F02M

Abstract:
1. A method for testing the operability of a tank shutoff valve of a fuel tank system which is controlled by valves, comprising: a) performing a defined triggering of the tank shutoff valve, wherein the defined triggering includes opening the tank shutoff valve; b) substantially simultaneous with the defined triggering, introducing one of an overpressure or partial vacuum into the fuel tank system using a pressure source, wherein the introduction of one of the overpressure or partial vacuum into the fuel tank system occurs with a tank ventilation valve that is closed; and c) determining the operability of the tank shutoff valve on the basis of a detected variable which characterizes the introduction of the one of the overpressure or partial vacuum; wherein if the detected variable which characterizes the introduction of the one of the overpressure or partial vacuum has a different time gradient in the case of the tank shutoff valve triggered to open in comparison to a predefined reference time gradient which characterizes an open tank shutoff valve, the tank shutoff valve is determined to be jammed in the closed position; and wherein if the detected variable which characterizes the introduction of the one of the overpressure or partial vacuum has a time gradient corresponding to the predefined reference time gradient which characterizes an open tank shutoff valve, the tank shutoff valve is subsequently triggered to close, and the tank shutoff valve is determined to be jammed in the open position if the increase over time of the variable which characterizes the introduction of the one of the overpressure or partial vacuum does not subsequently change.