Tank-venting apparatus as well as a method and an arrangement for checking the operability of a tank-venting valve

A method for checking the operability of a controllable tank-venting valve of a tank-venting apparatus of an internal combustion engine having an intake pipe, the tank-venting apparatus including:

• a tank having a tank pressure sensor for measuring pressure in said tank and an adsorption filter, the absorption filter communicating with said tank, said tank-venting valve (TEV) and the ambient via a venting check valve (BSV), said tank-venting valve (TEV) being connected to pass vapors from said tank-venting apparatus to said intake pipe, the method comprising the steps of:
• driving the venting check valve (BSV) so as to close and driving said tank-venting valve (TEV) so as to open;
• checking as to whether a tank difference pressure (pT) is equal to or less than a predetermined first threshold value;
• if this is the case, then closing said tank-venting valve (TEV) and measuring time from the time point at which said tank-venting valve (TEV) is closed;
• determining whether the pressure (pT) measured by said tank pressure sensor has exceeded a predetermined second threshold value;
• if this is not the case, then determining whether a predetermined test time span (t) has elapsed;
• if this is not the case, then again making an inquiry as to whether the pressure (pT) measured by said tank pressure sensor has exceeded said second threshold value and;
• if the test time span (t) has run said predetermined test time span (t), then providing a statement that said tank-venting valve is intact.

An arrangement for checking the operability of a controllable tank-venting valve of a tank-venting apparatus of an internal combustion engine having an intake pipe, the tank-venting apparatus including:

• a tank having a tank pressure sensor for measuring pressure in said tank and an adsorption filter, the absorption filter communicating with said tank, said tank-venting valve (TEV) and the ambient via a venting check valve (BSV), said tank-venting valve (TEV) being connected to pass vapors from said tank-venting apparatus to said intake pipe, the arrangement comprising:
• means for closing said venting check valve;
• means for driving said tank-venting valve (TEV) to open;
• means for monitoring said tank pressure sensor to determine a reaction thereof;
• means for driving said tank-venting valve (TEV) to close;
• means for again monitoring said tank pressure sensor to determine a reaction thereof;
• and,
• means for emitting a fault signal to indicate that said tank-venting valve (TEV) is defective when said pressure in said tank changes in the same direction before and after opening and closing said tank-venting valve.