Fuel supply system for an internal combustion engine
In a fuel supply system for an internal combustion engine including a fuel tank with an activated carbon canister in communication therewith for removing hydrocarbons from the fuel tank venting gases, the activated carbon canister is vented selectively by compressed air conducted from a pressurized air supply for the engine through the canister under the control of a valve which, during flushing of the activated carbon canister, blocks the communication line between the fuel tank and the activated carbon canister and by which the fuel vapors are returned to an engine intake manifold via a suction line, or during normal operation of the engine, by air sucked through the activated carbon container to an inlet manifold of the engine. The activated carbon container can be flushed with positive pressure when the engine is operated with supercharging and with negative pressure when the engine is operated in a normally aspirated fashion.
1. A fuel supply system for an internal combustion engine ( 1 ), comprising a fuel tank ( 5 ), an activated-carbon canister ( 6 ), an inlet manifold ( 3 ) on the internal combustion engine ( 1 ), an air supply duct ( 8 ) leading to the inlet manifold ( 3 ), and an air-mass flow meter ( 12 ) arranged in the air supply duct ( 8 ) and a valve ( 17 ) for controlling the connection of the fuel tank ( 5 ) to the atmosphere via the activated-carbon canister ( 6 ) and, downstream of the air-mass flow meter ( 12 ), a branch ( 13 ) extending from the air supply duct ( 8 ) back to the inlet manifold ( 3 ) via the activated-carbon canister ( 6 ), the branch ( 13 ) inlcuding a mechanically operated regenerating valve ( 18 ) downstream of the activated-carbon canister ( 6 ), the connection ( 21 ) of the fuel tank ( 5 ) to the atmosphere and the connection of the branch ( 13 ) from the air supply duct ( 8 ) to the activated-carbon canister ( 6 ) being both valve-controlled so as to be activated alternately for ventilation of the fuel tank ( 5 ) and for regeneration of the activated-carbon canister ( 6 ).
2. The fuel supply system as claimed in claim 1 , wherein the air supply duct ( 8 ) includes a pressure source ( 9 ) upstream of the air-mass flow meter ( 12 ).
3. The fuel supply system as claimed in claim 1 , wherein the air supply duct ( 8 ) includes a pressure source ( 9 ) downstream of the air-mass flow meter ( 12 ).
4. The fuel supply system as claimed in claim 2 , wherein the pressure source ( 9 ) is a supercharger.
5. The fuel supply system as claimed in claim 4 , wherein the pressure source ( 9 ) is provided with a bypass ( 10 ) including a recirculating flow control valve ( 11 ).
6. The fuel supply system as claimed in claim 4 , wherein the pressure source ( 9 ) is a mechanical supercharger.
7. The fuel supply system as claimed in claim 4 , wherein the pressure source ( 9 ) is a compressor of an exhaust gas turbocharger.
8. The fuel supply system as claimed in claim 1 , wherein the connection ( 21 ) of the fuel tank ( 5 ) to the activated-carbon canister ( 6 ) and the branch ( 13 ) from the air supply duct ( 8 ) to the activated-carbon canister ( 6 ) are controlled together via a directional control valve ( 17 ).
9. The fuel supply system as claimed in claim 8 , wherein the directional control valve ( 17 ) is a 4/2-way valve.
10. The fuel supply system as claimed in claim 8 , wherein the directional control valve ( 17 ) is a 4/3-way valve.
11. The fuel supply system as claimed in claim 1 , wherein the activated carbon canister ( 6 ) is in communication with the atmosphere via a non-return valve ( 20 ).
12. The fuel supply system as claimed in claim 1 , wherein the activated carbon canister ( 6 ) is in communication with the atmosphere via a mechanically operated valve ( 20 ).
13. The fuel supply system as claimed in claim 12 , wherein the mechanically operated valve ( 20 ) is closed during regeneration of the activated-carbon canister ( 6 ) with a negative pressure.
14. The fuel supply system as claimed in claim 1 , wherein the internal combustion engine has an exhaust manifold ( 2 ) and a lambda probe ( 22 ) is arranged in the exhaust manifold ( 2 ) such that the entire air mass flow supplied to the internal combustion engine, including the flushing air quantity, is conducted past the lambda probe ( 22 ).
15. The fuel supply system as claimed in claim 14 , wherein the loading of the activated-carbon filter ( 6 ) is detected via the lambda probe ( 22 ) during flushing of the activated carbon canister ( 6 ).