METHOD FOR THE REGENERATION OF AN ACTIVATED CARBON FILTER, AS WELL AS INTERNAL COMBUSTION ENGINE

Abstract

The invention relates to an internal combustion engine having an intake system and a fuel tank. In the intake system, there is a compressor and, downstream from the compressor, there is a throttle valve. The intake system comprises an air supply line that connects the compressor to an inlet of the internal combustion engine. The fuel tank has a venting line that connects the fuel tank to an activated carbon canister containing an activated carbon filter. It is provided for a conveying line to branch off from the air supply line and to connect the air supply line downstream from the compressor and upstream from the throttle valve to an intake line downstream from an air filter and upstream from the compressor. It is likewise provided for a control valve and a Venturi nozzle to be arranged in the conveying line, whereby the activated carbon canister is connected via a first flushing line to the air supply line downstream from the throttle valve and upstream from the inlet of the internal combustion engine, and whereby the activated carbon canister is connected via a second flushing line to the Venturi nozzle in the conveying line.

Claims

1. An internal combustion engine having: an intake system, comprising: an intake line that connects an air filter to a compressor, an air supply line that connects the compressor to an inlet of the internal combustion engine, and a throttle valve arranged in the air supply line, and a fuel tank, having a venting line that connects the fuel tank to an activated carbon canister containing an activated carbon filter, wherein a conveying line branches off from the air supply line and connects the air supply line downstream from the compressor and upstream from the throttle valve to the intake line downstream from the air filter and upstream from the compressor, wherein a control valve and a Venturi nozzle are arranged in the conveying line, wherein the activated carbon canister is connected via a first flushing line to the air supply line downstream from the throttle valve and upstream from the inlet of the internal combustion engine, and wherein the activated carbon canister is connected via a second flushing line to the Venturi nozzle in the conveying line.

2. The internal combustion engine according to claim 1, wherein the control valve is arranged in the conveying line upstream from the Venturi nozzle.

3. The internal combustion engine according to claim 1, wherein the control valve is arranged in the conveying line downstream from the Venturi nozzle.

4. The internal combustion engine according to claim 1, wherein the compressor is configured as an electrically or mechanically driven compressor.

5. The internal combustion engine according to claim 1, wherein the internal combustion engine is charged by means of an exhaust gas turbocharger, whereby the compressor is driven by a turbine situated in an exhaust gas channel of the internal combustion engine.

6. The internal combustion engine according to claim 5, wherein the turbine has an electrically regulated wastegate via which an exhaust gas stream can bypass the turbine of the exhaust gas turbocharger.

7. The internal combustion engine according to claim 1, wherein the first flushing line and the second flushing line have a shared line section, whereby a tank venting valve is arranged in the shared line section of the two flushing lines.

8. The internal combustion engine according to claim 1, further comprising a first non-return valve arranged in the first flushing line and a second non-return valve arranged in the second flushing line.

9. The internal combustion engine according to claim 1, further comprising a tank venting valve arranged in the first flushing line downstream from a branch of the first flushing line leading out of the second flushing line as well as upstream from the feed site of the first flushing line leading into the air supply line.

10. The internal combustion engine according to claim 1, wherein the first flushing line and the second flushing line run separately from each other along their entire lengths, whereby a tank venting valve is arranged in the first flushing line.

11. A method for the regeneration of an activated carbon filter in a tank venting system of a fuel tank of an internal combustion engine according to claim 1, comprising: generating, by the throttle valve, a negative pressure by means of which a first flushing flow is initiated which feeds the fuel vapors that were trapped in the activated carbon filter into the air supply line downstream from the throttle valve and upstream from the inlet, and initiating, by the Venturi nozzle, a second flushing flow which feeds the fuel vapors trapped in the activated carbon filter into the intake line downstream from the air filter and upstream from the compressor.

12. The method for the regeneration of an activated carbon filter according to claim 11, further comprising adjusting the flushing quantity of the second flushing flow by means of the control valve.

13. The method for the regeneration of an activated carbon filter according to claim 11, further comprising raising the rotational speed of the exhaust gas turbocharger in order to increase the flushing quantity of the second flushing flow.

14. The method for the regeneration of an activated carbon filter according to claim 11, further comprising using a reserve area RB of the exhaust gas turbocharger to effectuate an increase in the flushing mass flow ({dot over (m)}.sub.TE) as a function of the flushing demand and, at the same time, to actuate the control valve in such a way that the requested additional flushing quantity is systematically assigned to the flushing mass flow ({dot over (m)}.sub.TE).

15. The method for the regeneration of an activated carbon filter according to claim 11, wherein the tank venting valve controls the first flushing flow.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The invention will be explained below in embodiments on the basis of the accompanying drawings. The following is shown:

[0025] FIG. 1 is a first embodiment of an internal combustion engine according to the invention, with a fuel tank, an intake system and an exhaust gas system;

[0026] FIG. 2 is an alternative embodiment of an internal combustion engine according to the invention, with a fuel tank, an intake system and an exhaust gas system;

[0027] FIG. 3 is a preferred embodiment of an internal combustion engine according to the invention, with a fuel tank, an intake system and an exhaust gas system;

[0028] FIG. 4 is a diagram depicting the rotational speed of the exhaust gas turbocharger as a function of the charge pressure; and

[0029] FIG. 5 is a diagram depicting the mass flow through the Venturi nozzle as a function of the reserve quantity and as a function of the opening angle of the Venturi nozzle.

DETAILED DESCRIPTION OF THE INVENTION

[0030] FIG. 1 shows an internal combustion engine 10 with several combustion chambers 12. The internal combustion engine 10 is preferably configured as a gasoline engine. The internal combustion engine 10 can be operated with a fuel 32 that is stored in a fuel tank 30 of a motor vehicle. The fuel tank 30 can be filled through a filler neck and it is equipped with a filling level sensor to detect the filling level. A fuel pump feeds the fuel 32 to the internal combustion engine 10 via a fuel line that branches off from the fuel tank 30, where the fuel is injected into the combustion chambers 12 of the internal combustion engine 10 by means of a fuel injection system. A spark plug 14 is arranged on each combustion chamber 12 in order to ignite the air-fuel mixture in the combustion chambers 12. The internal combustion engine 10 is connected via its inlet 16 to an intake system 20 of the internal combustion engine 10, thus supplying the combustion chambers 12 with fresh air. Fresh air that has been drawn in from the environment is fed to the internal combustion engine 10 via the intake system 20 and it is then made available via an intake line 66 and an air supply line 60 to an inlet 16 that distributes the fresh air to the combustion chambers 12 of the internal combustion engine 10. Arranged in the intake system 20 in the flow direction of the fresh air through the intake system, there is an air filter 22, then downstream from the air filter 22, there is a compressor 26 of the exhaust gas turbocharger 68, and further downstream, there is a throttle valve 28. The air filter 22 is connected to the compressor 26 via an intake line 66. The compressor 26 is connected to the inlet 16 of the internal combustion engine 10 via an air supply line 60. A throttle valve 28 with which the air feed to the combustion chambers 12 of the internal combustion engine 10 can be controlled is arranged in the air supply line 60. A conveying line 64 that connects the intake system 20 downstream from the compressor 26 to the intake line 66 of the intake system 20 downstream from the air filter 22 and upstream from the compressor 26 branches off from the air supply line 60 at a branch 62. A control valve 58 and a Venturi nozzle 56 are arranged in the conveying line. Moreover, in order to determine the quantity of air fed to the compressor 26 of the exhaust gas turbocharger 68, an air mass meter 24 is arranged on the intake line 66 downstream from the air filter and upstream from the place where the conveying line 64 opens up.

[0031] The internal combustion engine 10 has an outlet 18 that is connected to an exhaust gas system 70 of the internal combustion engine 10. The exhaust gas system 70 comprises an exhaust gas channel 74 in which, in the flow direction of the exhaust gas of the internal combustion engine 10 through the exhaust gas channel 74, there is a turbine 72 of the exhaust gas turbocharger 68 and, downstream from the turbine 72, there is at least one exhaust gas aftertreatment component 78, especially a three-way catalytic converter or a particulate filter with a three-way catalytically active coating. The exhaust gas turbocharger 68 has a wastegate 76 that forms a bypass for the turbine 72, whereby a valve that serves to control the exhaust gas mass flow through the turbine 72 by means of the wastegate is arranged in the bypass.

[0032] The internal combustion engine 10 also has a fuel supply system with a fuel tank 30 in which a liquid fuel 32 is stored. Depending on the pressure and on the ambient temperature, a portion of the fuel 32 can evaporate and remain in the fuel tank 30 as fuel vapor 34. The fuel tank 30 is connected via a venting line 36 to an activated carbon canister 38 in which an activated carbon filter 40 is arranged which binds the fuel vapor and prevents the fuel vapor from escaping into the environment. The activated carbon canister 38 is also connected to a diagnostic module 42 that is capable of detecting a leak in the tank system.

[0033] The activated carbon filter 38 is connected via a flushing line 48, 50 to the intake system 20 of the internal combustion engine 10. A tank venting valve 44 is arranged in a first section of the flushing line 48, 50. Downstream from the tank venting valve 44, the flushing line 48, 50 branches off at a branch 46 into a first flushing line 48 and into a second flushing line 50. The first flushing line 48 connects the branch 46 to the air supply line 60 downstream from the throttle valve 28 and upstream from the inlet 16 of the internal combustion engine 10. In the first flushing line 48, there is a first non-return valve 52 that prevents fresh air from flowing back out of the air supply line 60 into the activated carbon canister 38. The second flushing line 50 connects the branch 46 to the Venturi nozzle 56 in the conveying line 64. In this context, in the second flushing line 50, there is a second non-return valve 54 that prevents fresh air from flowing back out of the conveying line 64 into the activated carbon canister 38.

[0034] The internal combustion engine 10 is connected to an engine control unit 80 that regulates the quantity of fuel that is metered into the combustion chambers 12 of the internal combustion engine 10. Moreover, the engine control unit 80 actuates the control valve 58 and the tank venting valve 44.

[0035] When the control valve 58 is open, a portion of the fresh air compressed by the compressor 26 flows via the conveying line 64 out of the air supply line 60 through the Venturi nozzle 56 back into the intake line 66. In this process, according to the principle of a suction jet pump, the Venturi nozzle 56 conveys a flushing air volume flow out of the activated carbon canister 38. As the altitude and heat increase, this flushing air volume flow cannot be provided to the full extent due to the altitude reserve HR for the exhaust gas turbocharger 68. Use of the control valve 58 can ensure that the flushing air flow is limited as a function of the ambient conditions.

[0036] FIG. 2 shows an alternative embodiment of an internal combustion engine 10 having an intake system 20 and an exhaust gas system 70 as well as a fuel tank 30. With an otherwise identical structure as depicted in FIG. 1, the control valve 58 in this embodiment is arranged in the conveying line 64 downstream from the Venturi nozzle 56.

[0037] FIG. 3 shows a preferred embodiment of an internal combustion engine 10 having an intake system 20 and an exhaust gas system 70 as well as a fuel tank 30. With an otherwise identical structure to the one depicted in FIG. 1 and FIG. 2, only the differences from these figures will be discussed below. In the embodiment shown in FIG. 3, the tank venting valve 44 is not arranged in the shared flushing line 48, 50 but rather, downstream from the branch 46 in the first flushing line 48. Moreover, the control valve 58 is arranged in the conveying line 64 downstream from the Venturi nozzle 56 and upstream from the place where the conveying line 64 opens up into the intake line 66. As a result, the two non-return valves 52, 54 can be dispensed with. Thanks to the geometric arrangement of the valves 44, 58, maximal regulation dynamics are possible, and this has a positive effect on the mixture formation.

[0038] FIG. 4 shows the rotational speed n of the exhaust gas turbocharger 68 as a function of the charge pressure p.sub.T. Owing to its structure, the exhaust gas turbocharger 68 has a maximum rotational speed n.sub.max. The momentary operating point of the exhaust gas turbocharger 68 and the charge pressure p.sub.T needed for this purpose as well as the altitude reserve HR yield a target rotational speed for the exhaust gas turbocharger 68. The difference between this target rotational speed and the maximum rotational speed n.sub.max of the exhaust gas turbocharger 68 constitutes the reserve area RB that can be employed to regulate the Venturi nozzle 56. In this context, the reserve area RB of the exhaust gas turbocharger 68 is used to effectuate an increase in the flushing mass flow {tilde over (m)}.sub.TE as a function of the flushing demand. This is especially done by increasing the rotational speed of the exhaust gas turbocharger 68. In the case of an exhaust gas turbocharger 68 with a variable guide geometry for the guide vanes of the turbine 72, this can also be done by adjusting the guide vanes. In particular, however, such an adjustment can help to increase the rotational speed of the exhaust gas turbocharger 68. At the same time, the control valve 58 is actuated in such a way that the requested additional flushing quantity is systematically assigned to the flushing mass flow {dot over (m)}.sub.TE.

[0039] FIG. 5 shows the resultant flushing quantity {dot over (m)}.sub.TE as a function of the mass flow {dot over (m)} through the Venturi nozzle 56 and as a function of the reserve quantity. Moreover, the mass flow is depicted as a function of the opening angle of the Venturi nozzle 56. Accordingly, the actuation of the tank venting valve 44 as well as the increase in the rotational speed n of the exhaust gas turbocharger 68 always have to take place as a function of the required flushing quantity.

[0040] The tank venting systems being put forward allow full engine power to be maintained, along with the maximum tank venting mass flow. In this process, the activated carbon canister 38 can be flushed in such a way that the activated carbon filter 40 is sufficiently regenerated and the fuel vapors 34 trapped in the activated carbon filter 40 are conveyed in their entirety into the intake system 20. In this manner, a complete regeneration of the activated carbon filter 40 can be achieved and the escape of fuel vapors 34 can be prevented.

LIST OF REFERENCE NUMERALS

[0041] 10 internal combustion engine [0042] 12 combustion chamber [0043] 14 spark plug [0044] 16 inlet [0045] 18 outlet [0046] 20 intake system [0047] 22 air filter [0048] 24 air mass meter [0049] 26 compressor [0050] 28 throttle valve [0051] 30 fuel tank [0052] 32 fuel [0053] 34 fuel tank vapor [0054] 36 venting line [0055] 38 activated carbon filter [0056] 40 activated carbon [0057] 42 diagnostic module [0058] 44 tank venting valve [0059] 46 branch [0060] 48 first flushing line [0061] 50 second flushing line [0062] 52 first non-return valve [0063] 54 second non-return valve [0064] 56 Venturi nozzle [0065] 58 control valve [0066] 60 air supply line [0067] 62 branch [0068] 64 conveying line [0069] 66 intake line [0070] 68 exhaust gas turbocharger [0071] 70 exhaust gas system [0072] 72 turbine [0073] 74 exhaust gas channel [0074] 76 wastegate [0075] 78 exhaust gas aftertreatment component [0076] 80 engine control unit [0077] {dot over (m)} mass flow [0078] {dot over (m)}.sub.TE resultant flushing quantity [0079] n.sub.max maximum rotational speed limit for the exhaust gas turbocharger [0080] n.sub.T rotational speed of the turbine of the exhaust gas turbocharger [0081] n(p.sub.T) rotational speed as a function of the charge pressure of the exhaust gas turbocharger [0082] HR altitude reserve [0083] R reserve quantity [0084] RB regulation area of the Venturi nozzle [0085] p.sub.T charge pressure of the exhaust gas turbocharger [0086] p.sub.UM ambient pressure [0087] opening angle of the Venturi nozzle