METHOD FOR OPERATING AN INTERNAL COMBUSTION ENGINE

Abstract

A method for operating an internal combustion engine having an exhaust gas line that conducts an exhaust gas, starting from the internal combustion engine, across an exhaust gas turbocharger, wherein a second pressure in a second section of the exhaust gas line downstream from the exhaust gas turbocharger is determined by measuring a first pressure in a first section of the exhaust gas line downstream from the internal combustion engine and upstream from the exhaust gas turbocharger; wherein this determination of the second pressure is derived from the condition that in certain operating points of the internal combustion, the first pressure corresponds to the second pressure at certain crankshaft angle positions.

Claims

1. A method for operating an internal combustion engine comprising an exhaust gas line that conducts an exhaust gas, starting from the internal combustion engine, across an exhaust gas turbocharger, the method comprising: determining a second pressure, in a second section of the exhaust gas line downstream from the exhaust gas turbocharger, by measuring a first pressure, in a first section of the exhaust gas line downstream from the internal combustion engine and upstream from the exhaust gas turbocharger; wherein the determination of the second pressure is derived from a relationship according to which the first pressure in predetermined operating points of the internal combustion engine corresponds to the second pressure at predetermined crankshaft angle positions.

2. The method according to claim 1, further comprising determining the predetermined operating points and the predetermined crankshaft angle positions by operating the internal combustion engine on a test stand, using a test stand method.

3. The method according to claim 2, wherein the test stand method comprises: measuring a first course of the first pressure during operation of the internal combustion engine, using a first sensor; and measuring a second course of the second pressure during operation of the internal combustion engine, using a second sensor; wherein determining the predetermined operating points and the predetermined crankshaft angle positions comprises determining operating points and crankshaft angle positions for which the first pressure corresponds to the second pressure; and wherein, for the test stand method, a state of the exhaust gas line downstream from the exhaust gas turbocharger with regard to a flow resistance and a resulting instantaneous exhaust gas back pressure in the second section is known.

4. The method according to claim 3, further comprising: determining a characteristic curve for an adaptation value based on the determination of the predetermined operating points and the predetermined crankshaft angle positions; and determining, for other operating points of the internal combustion engine, a third pressure, in the second section of the exhaust gas line downstream from the exhaust gas turbocharger, from the measurement of the first pressure based on the characteristic curve for the adaption value.

5. The method according to claim 3, further comprising, during operation of the internal combustion engine, determining the second pressure and the instantaneous exhaust gas pressure based on a change in the first pressure.

6. The method according to claim 5, further comprising a control method comprising, using the instantaneous exhaust gas back pressure for: controlling a charge pressure for the internal combustion engine; controlling a charge cycle model of the internal combustion engine; diagnosing an exhaust gas turbocharger overspeed; and controlling a regeneration of a gas treatment component situated in the second section.

7. The method according to claim 5, further comprising determining a loading of at least one gas treatment component with soot by ascertaining the instantaneous exhaust gas back pressure, in the second section upstream from the gas treatment component; wherein the instantaneous exhaust gas back pressure is influenced as a function at least of the loading of the gas treatment component.

8. A computer program that is configured to execute the method according to claim 1.

9. A machine-readable memory medium comprising the computer program according to claim 8.

10. An internal combustion engine comprising: an exhaust gas line configured to conduct an exhaust gas, starting from the internal combustion engine, across an exhaust gas turbocharger, wherein the exhaust gas line has: a first section downstream from the internal combustion engine and upstream from the exhaust gas turbocharger, and a second section downstream from the exhaust gas turbocharger; a first sensor, situated in the first section, for measuring a first pressure; and a control unit configured to determine a second pressure, in the second section, by measuring the first pressure, wherein the determination of the second pressure is derived from a relationship according to which the first pressure in predetermined operating points of the internal combustion engine corresponds to the second pressure at predetermined crankshaft angle positions.

11. The internal combustion engine of claim 10, wherein the control unit is further configured to perform a test stand method comprising: measure a first course of the first pressure during operation of the internal combustion engine, using a first sensor; and measure a second course of the second pressure during operation of the internal combustion engine, using a second sensor; wherein the predetermined operating points and the predetermined crankshaft angle positions are predetermined by determining operating points and crankshaft angle positions for which the first pressure corresponds to the second pressure; and wherein, for the test stand method, a state of the exhaust gas line downstream from the exhaust gas turbocharger with regard to a flow resistance and a resulting instantaneous exhaust gas back pressure in the second section is known.

12. The internal combustion engine of claim 11, wherein the control unit is further configured to: determine a characteristic curve for an adaptation value based on the determination of the predetermined operating points and the predetermined crankshaft angle positions; and determine, for other operating points of the internal combustion engine, a third pressure, in the second section of the exhaust gas line downstream from the exhaust gas turbocharger, from the measurement of the first pressure based on the characteristic curve for the adaption value.

13. The internal combustion engine of claim 11, wherein the control unit is further configured to, during operation of the internal combustion engine, determine the second pressure and the instantaneous exhaust gas pressure based on a change in the first pressure.

14. The internal combustion engine of claim 13, wherein the control unit is further configured to, utilize the instantaneous exhaust gas back pressure to: control a charge pressure for the internal combustion engine; control a charge cycle model of the internal combustion engine; diagnose an exhaust gas turbocharger overspeed; and control a regeneration of a gas treatment component situated in the second section.

15. The internal combustion engine of claim 13, wherein the control unit is further configured to determine a loading of at least one gas treatment component with soot by ascertaining the instantaneous exhaust gas back pressure, in the second section upstream from the gas treatment component; wherein the instantaneous exhaust gas back pressure is influenced as a function at least of the loading of the gas treatment component

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0052] The invention and the technical context are explained in greater detail below with reference to the figures. It is pointed out that the invention is not to be construed as being limited by the illustrated exemplary embodiments. In particular, unless explicitly stated otherwise, it is also possible to extract partial aspects of the information shown in the figures and combine them with other components and findings from the present description and/or figures. In particular, it is noted that the figures and in particular the illustrated proportions are only schematic. Identical objects are denoted by the same reference numerals, so that explanations concerning other figures may possibly be supplementally used. In the figures:

[0053] FIG. 1: shows an internal combustion engine having an exhaust gas line; and

[0054] FIG. 2: shows a pressure-time diagram.

DETAILED DESCRIPTION OF THE INVENTION

[0055] FIG. 1 shows an internal combustion engine 1 having an exhaust gas line 2. Starting from the internal combustion engine 1, an exhaust gas 3 is conducted through the exhaust gas line 2 and across an exhaust gas turbocharger 4. The exhaust gas line 2 has a first section 6 downstream from the internal combustion engine 1 and upstream from the exhaust gas turbocharger 4, and a second section 8 downstream from the exhaust gas turbocharger 4. A first sensor 13 for measuring a first pressure 5 is situated in the first section 6. The internal combustion engine 1 also includes a control unit 21 that is suitable for carrying out the described method.

[0056] A second pressure 7 in a second section 8 of the exhaust gas line 2 downstream from the exhaust gas turbocharger 4 is determined by measuring a first pressure 5 in a first section 6 of the exhaust gas line 2. This determination of the second pressure 7 is derived from the condition that in certain operating points 9 of the internal combustion engine 1, the first pressure 5 corresponds to the second pressure 7 at certain crankshaft angle positions 10.

[0057] A gas treatment component 17 (particle filter, catalytic converter, flow influencer, injection device, heating device, etc.) is situated in the second section 8.

[0058] In a test stand method, a second (pressure) sensor 15 (indicated here by dashed lines) may be situated in the second section 8, and the second pressure 7 and the second course 14 in the second section 8 may thus be detected by measurement. Thus, in the test stand method, for each configuration of the internal combustion engine 1, exhaust gas line 2, gas treatment components 17, drive train (for example, transmission, additional drive units, etc.), the operating points 9 and crankshaft angle positions 10 for which the magnitudes of the first pressure 5 and the second pressure 7 are equal may be determined.

[0059] The operating points 9 and crankshaft angle positions 10 thus determined in the test stand method may then be used in the method described above, so that the internal combustion engine 1, manufactured in large production volumes, of the same type as the configuration used in the test stand method may be used without a second sensor 15.

[0060] In the second section 8, a gas treatment component 4 [sic; 17] (a particle filter, for example) is situated in the second section 8, by means of which, in the second section 8 upstream from the gas treatment component 4 [sic; 17], the instantaneous exhaust gas back pressure 11 is influenced as a function at least of loading 18 of the gas treatment component 17 with soot. The loading 18 is determinable by ascertaining the instantaneous exhaust gas back pressure 11 (or the second pressure 7).

[0061] The control unit 21 is able to detect the pressures 5, 7. The computer program 19, which is stored on a machine-readable memory medium 20, is stored in the control unit 21. The characteristic curve 16 is also stored in the control unit 21.

[0062] FIG. 2 shows a pressure-time diagram. The pressure 5, 7 is plotted on the vertical axis. Time 22 and the recurring crankshaft angle position 10 [are plotted] on the horizontal axis.

[0063] The first pressure 5 in the first section 6 varies as a function of the particular operating point 9 that is present, and the crankshaft angle position 10 (in the particular operating point 9). The exhaust valves of the combustion chambers are actuated as a function of the crankshaft angle position 10, so that exhaust gas 3 from the combustion chambers can enter the first section 6. It has now been established that in certain operating points 9, and for certain crankshaft angle positions 10 that are then present, the first pressure 5 upstream from the exhaust gas turbocharger 4 has the same magnitude as the second pressure 7 downstream from the exhaust gas turbocharger 4 (see intersection points of the first course 12 of the first pressure 5 and of the second course 14 of the second pressure 7). In addition, it has been established that this point in time in the first course 12 of the first pressure 5 may be determined very accurately, so that the second pressure 7 may be derived from the first course 12 of the first pressure 5 with great accuracy.

[0064] In addition, it is known that the second pressure 7 has a certain second course 14 as a function of the first course 12 of the first pressure 5.

[0065] Based on these conditions, it has been deduced that the second course 14 of the second pressure 7 may be determined as a function of the first course 12 of the first pressure 5. In addition, based on a change in the first pressure 5, in particular in the certain operating points 9 and at the certain crankshaft angle positions 10, it is possible to determine a change in the second pressure 7, and thus an instantaneously present exhaust gas back pressure 11 in the second section 8 of the exhaust gas line 2.

LIST OF REFERENCE NUMERALS

[0066] 1 internal combustion engine [0067] 2 exhaust gas line [0068] 3 exhaust gas [0069] 4 exhaust gas turbocharger [0070] 5 first pressure [0071] 6 first section [0072] 7 second pressure [0073] 8 second section [0074] 9 operating point [0075] 10 crankshaft angle position [0076] 11 exhaust gas back pressure [0077] 12 first course [0078] 13 first sensor [0079] 14 second course [0080] 15 second sensor [0081] 16 characteristic curve [0082] 17 gas treatment component [0083] 18 loading [0084] 19 computer program [0085] 20 machine-readable memory medium [0086] 21 control unit [0087] 22 time