Tank-venting system and motor vehicle having the system as well as a method and an arrangement for checking the operability of the system

A motor vehicle comprising:

• an internal combustion engine having an exhaust-gas channel;
• a compressed-air source for supplying compressed air;
• a tank-venting system including:
• a tank;
• an adsorption filter;
• a tank-connection line connecting said adsorption filter to said tank;
• said adsorption filter having a venting line;
• a tank-venting valve;
• a valve line connecting said tank-venting valve to said adsorption filter;
• a pressure connection connected to said valve line close to said tank-venting valve;
• a pressure sensor on said tank;
• and, a shut-off valve in said venting line;
• and,
• a switch-over valve for selectively switching over the compressed air from the compressed-air source to said pressure connection connected to said valve line of the tank-venting system in a first position of said switch-over valve.

A method for checking the operability of a tank-venting system having a tank, an adsorption filter, which is connected to the tank via a tank-connecting line and has a venting line, and a tank-venting valve which is connected to the adsorption filter via a valve line, the method comprising the steps of:

• closing the tank-venting valve and the venting line with the aid of a shut-off valve arranged on the venting line;
• supplying compressed air to the tank-venting system at the end of the tank-venting valve which faces toward the adsorption filter;
• measuring the pressure in the tank;
• and,
• checking if the pressure satisfies a pregiven pressure condition and determining the tank-venting system as being inoperable in the event that this is not the case.

An arrangement for checking the operability of a tank-venting system having a tank, an adsorption filter, which is connected to the tank via a tank-connecting line and has a venting line, and a tank-venting valve, which is connected to the adsorption filter via a valve line, the arrangement comprising:

• means for closing the tank-venting valve and the venting line with the aid of a shut-off valve mounted in the venting line;
• means for supplying compressed air to the tank-venting system at the end of the tank-venting valve facing toward the adsorption filter;
• means for measuring the pressure in the tank;
• and,
• means for checking whether the pressure of a pregiven pressure condition is satisfied and to determine that the tank-venting system is not operable in the event that this is not the case.