Determination of the effective fuel-air ratio of a supercharged internal combustion engine with scavenging air component

Abstract

A method for the fuel consumption reduction and/or power increase of an internal combustion engine of a motor vehicle is disclosed. A crank angle of a crankshaft is detected at which out of a cylinder the exhaust gases of a cylinder can be representatively measured on a lambda probe. The exhaust gas flow is measured on the lambda probe. A signal of the lambda probe is scanned at the time of the detection of the crank angle. A value indicated the detected angle and/or the scanned signal is sent to a computer. The value is corrected with the help of an exhaust gas pressure or exhaust gas back pressure model stored in the computer. An effective combustion lambda of the cylinder is calculated based on the sent values and a global lambda value stored in the computer and used to the control of the internal combustion engine.

Claims

1. A method of engine control for fuel consumption reduction or power increase of an internal combustion engine of a motor vehicle, the method comprising: detecting a crank angle of a crankshaft at which a exhaust gas flow from at least one cylinder can be representatively measured on a lambda probe; measuring the exhaust gas flow on the lambda probe; scanning a signal of the lambda probe at the time of the detection of the crank angle to generate a scanned value; sending the scanned value to a computer; correcting the scanned value using an model having a global lambda value stored in the computer and representing at least one of an exhaust gas pressure or exhaust gas back pressure; calculating at least one of an effective combustion lambda of the at least one cylinder and a scavenging air component in the exhaust gas flow after the at least one cylinder a as a function of the scanned value and the global lambda value stored in the computer; and controlling an operating parameter of the internal combustion engine in response to the effective combustion lambda.

2. The method according to claim 1, wherein the exhaust gas flow is measured at the moment of the detection of the crank angle such that no scavenging air flow is visible in the measured exhaust gas flow.

3. The method according to claim 1, further comprising comparing the calculated combustion lambda with a set point value of the combustion lambda of the model.

4. The method according to claim 3, further comprising calculating a correction value from the set point value when a deviation of the effective combustion lambda is determined.

5. The method according to claim 1, wherein at the moment of the scanning of the angle of the crankshaft no scavenging air flow is visible in the scanned signal and the scavenging air flow is calculated by the computer together with the effective combustion lambda out of the measured air mass flow, the global lambda and the scanned lambda probe value.

6. The method according to claim 1 further comprising filtering and statistically evaluating the scanned signal in the computer.

7. The method according to claim 1, wherein controlling an operating parameter of the internal combustion engine comprises send a signal on the basis of the calculated effective combustion lambda from the computer to a control unit for adjusting an air-gas mixture to the cylinders in order to bring about at least one of a fuel consumption reduction and a power increase of the internal combustion engine.

8. The method according to claim 1, wherein controlling an operating parameter of the internal combustion engine comprises send a signal on the basis of a calculated scavenging air flow sends from the computer to a control unit for adjusting an air-gas mixture for the cylinders in order to bring about at least one of a fuel consumption reduction and a power increase of the internal combustion engine.

9. The method according to claim 1, wherein the crank angle is detected by the detector and the lambda probe value for each cylinder of the internal combustion engine is scanned by the scanner, and from these values the effective combustion lambda for each individual cylinder is calculated by the computer.

10. A computer program for carrying out a method according to claim 1.

11. A computer program product comprising program code means stored on a non-transitory computer-readable medium in order to carry out the method according to claim 1 when the program code is executed on the computer.

12. A drive system for a motor vehicle comprising: an internal combustion engine having a crankshaft, a turbocharger, and a camshaft for controlling valves for at least one cylinder of the internal combustion engine; a detector configured to detect an angle of rotation of the crankshaft; a lambda probe sensor configured to continuously detect an exhaust gas flow flowing out of the at least one cylinder; a scanner configured to scan current values of the lambda probe sensor at any time; and a computer operably coupled to receive signals from the detector and the scanner and having a memory storing global lambda values for the internal combustion engine; wherein the computer calculates at least one of an effective combustion lambda of the at least one cylinder and a scavenging air component in the exhaust gas flow after the at least one cylinder from at least one of the detected angle of rotation of the crankshaft, a scanned lambda probe signal and the global lambda values and controls an operating parameter of the internal combustion engine in response to the effective combustion lambda.

13. The drive system according to claim 12, wherein the detector detects the angle of rotation of the crankshaft, at which the exhaust gas flow out of the at least one cylinder for a single combustion is present on the lambda probe.

14. The drive system according to claim 13, wherein the scanner scans the lambda probe value at the time of the detection of the angle of rotation of the crankshaft.

15. The drive system according to claim 13, wherein the detector detects the angle of rotation of the crankshaft and the scanner individually scans the lambda probe value for each cylinder of the internal combustion engine, and wherein the computer calculates at least one of an effective combustion lambda and a scavenging air component for each of the cylinders.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The present disclosure will hereinafter be described in conjunction with the following drawing figures, wherein like numerals denote like elements.

(2) FIG. 1 schematically illustrates a drive system for a motor vehicle with an internal combustion engine having a turbocharger; and

(3) FIG. 2 schematically illustrates a method sequence.

DETAILED DESCRIPTION

(4) The following detailed description is merely exemplary in nature and is not intended to limit the present disclosure or the application and uses of the present disclosure. Furthermore, there is no intention to be bound by any theory presented in the preceding background or the following detailed description.

(5) A drive system 1 for a motor vehicle is schematically shown in FIG. 1. The drive system 1 includes an internal combustion engine 2 within the exemplary embodiment four cylinders 21, 22, 23, 24. Each of the cylinders 21, 22, 23, 24 has valves 5, which can be opened and closed by a camshaft which is not shown. The internal combustion engine 2 includes a turbocharger 4 with a compressor 12 and a turbine 13. The compressor 12 supplies the internal combustion engine 2 with compressed air for combustion; the exhaust gas flowing out of the cylinders 21, 22, 23, 24 is conducted through the turbine 13 and drives the compressor 12.

(6) On the crankshaft 3, a detector 6 is arranged, which can detect an angle of rotation of the crankshaft 3 and pass it on to a computer 9. With the detector 6, an angle of rotation of the crankshaft 3 and of a crankshaft trigger for controlling the valves 5 for each of the cylinders 21, 22, 23, 24 can be detected for example. Having left the cylinders 21, 22, 23, 24, an exhaust gas flow of a single combustion in one of the cylinders 21, 22, 23, 24 can be measured on a lambda probe 8.

(7) In a line 11, which connects the internal combustion engine 2 to the turbine 13 of the turbocharger 4, a lambda probe 8 is arranged. For rapid sequential scanning of the lambda probe value on the lambda probe 8 at a preset time, a scanner 7 in the form of an integrated circuit is arranged in the computer 9 in the shown exemplary embodiment. The computer 9 includes a memory 10, in which for example global lambda values for the internal combustion engine 2 and/or an exhaust gas pressure or exhaust gas back pressure model of the internal combustion engine 2 are stored.

(8) The detector 6, the lambda probe 8 and the scanner 7 are signal-connected to the computer 9. The computer 8 can process the received data of the detector 6 and of the scanner 7 and from this data calculate an effective combustion lambda for each of the cylinders 21, 22, 23, 24.

(9) In addition, the detector 6 detects an angle of rotation of the crankshaft 3 at which out of only one of the cylinders 21, 22, 23, 24 the exhaust gas flows after the combustion. On the lambda probe 8, the exhaust gas flow is continuously measured and at the moment, at which the detector has detected the corresponding crank angle, the scanner 7 scans the current value on the lambda probe 8.

(10) Since the exhaust gas mass flow at the time of the measurement on the lambda probe 8 is at least substantially free of scavenging air, the computer 9 can with a stored algorithm calculate the effective combustion lambda and/or a scavenging air component in the exhaust gas mass flow for the cylinder 21, 22, 23, 24 from at least one of the values of the detector 6 and/or of the scanner 7 and the global lambda value for the internal combustion engine 2 stored in the memory 10, the exhaust gas mass flow of which has just been measured on the lambda probe 8.

(11) FIG. 2 schematically illustrates a sequence for a method with which a fuel consumption of an internal combustion engine of a motor vehicle can be reduced and/or a power increase of the internal combustion engine can be achieved. The method includes the steps: detecting a crank angle A at which out of a cylinder the exhaust gases of a cylinder combustion are present on a lambda probe, measuring the exhaust gas flow B of the cylinder at the time of the detection of the crank angle and scanning of a signal C of a pre-turbine probe at the time of the detection of the crank angle. Calculating an effective combustion lambda of a cylinder combustion out of the scanned value and a correction value of a default model.

(12) The calculated effective combustion lambda can be compared with a modelled combustion lambda, respectively a set point value of an exhaust gas pressure or exhaust gas backpressure model stored in the computer. If the computer does not determine any deviations of the values or deviations of the values in a permissible limit value range, the method ends and can recommence.

(13) In the case of deviations, the computer can calculate correction values and send control inputs to a control, which can then carry out adjustments E on individual parameters of the drive system. The effectiveness of these adjustments can be verified during the next measurement for the same cylinder.

(14) While at least one exemplary embodiment has been presented in the foregoing detailed description, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment is only an example, and are not intended to limit the scope, applicability, or configuration of the present disclosure in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing an exemplary embodiment, it being understood that various changes may be made in the function and arrangement of elements described in an exemplary embodiment without departing from the scope of the present disclosure as set forth in the appended claims and their legal equivalents.