Cylinder-selective control of the air-fuel ratio

• US 6,276,349 B1
• Filed: 10/08/1999
• Issued: 08/21/2001
• Est. Priority Date: 10/08/1998
• Status: Expired due to Term

• Current Assignee: Bayerische Motoren Werke AG
• Original Assignee: Bayerische Motoren Werke AG
• Inventors: Albrecht, Florian, Kofler, Franz, Meder, Georg
• Primary Examiner(s): ARGENBRIGHT, TONY MICHAEL
• Application Number:
  US09/414,646
• Time in Patent Office: 683 Days
• Field of Search: 123/673, 123/687, 701/109
• US Class Current: 123/673
• CPC Class Codes: F02D 41/008 Controlling each cylinder individually
• CPC Class Codes: F02D 41/1458 with determination means using an estimation
• CPC Class Codes: F02D 41/1474 by detecting the commutation time of the sensor

Abstract

Cylinder-selective control of the air-fuel ratio in a multi-cylinder internal-combustion engine is provided, wherein a lambda probe arranged in the exhaust pipe system generates a voltage signal corresponding to an air-fuel ratio. The voltage signal is supplied to a computing unit which determines the air-fuel ratio for each individual cylinder. A fuel metering unit determines a fuel injection quantity at least as a function of a basic fuel injection value and the determined air-fuel ratios of the individual cylinders, and a fuel supply unit supplies the fuel injection quantity determined by the fuel metering unit to the cylinders of the internal-combustion engine. The computing unit crank-angle-synchronously detects the voltage signal and assigns it to a certain cylinder. A voltage deviation and corresponding injection quantity correction is determined for each cylinder in relation to the voltage signals of the adjacent cylinders.

Claims

1. A cylinder-selective control process for an air-fuel ratio of a multi-cylinder internal-combustion engine, wherein a lambda probe arranged in an exhaust pipe system generates a voltage signal corresponding to an air-fuel ratio, said voltage signal being supplied to a computing unit which determines the air-fuel ratio for each individual cylinder, a fuel metering unit being provided to determine a fuel injection quantity at least as a function of a basic fuel injection value and the determined air-fuel ratios of the individual cylinders, and a fuel supply unit being provided for supplying the fuel injection quantity determined by the fuel metering unit to the individual cylinders of the internal-combustion engine, the process comprising the acts of:

detecting the voltage signal from the lambda probe in a crank-angle-synchronous manner via the computing unit;

assigning the detected voltage signal to a certain cylinder;

determining a voltage deviation for each cylinder in relation to the voltage signals assigned to sequentially adjacent cylinders; and

correcting the fuel injection quantity as a function of the determined voltage deviation.

2. The cylinder-selective control process according to claim 1, further comprising the act of obtaining a correction value for the fuel injection quantity from one of a characteristic curve and characteristic diagram.

3. The cylinder-selective control process according to claim 1, wherein the lambda probe is a surge probe.

4. The cylinder-selective control process according to claim 2, wherein the lambda probe is a surge probe.

5. The cylinder-selective control process according to claim 1, further comprising the act of no longer correcting the fuel injection quantity above a defined engine rotational limit speed.

6. The cylinder-selective control process according to claim 2, further comprising the act of no longer correcting the fuel injection quantity above a defined engine rotational limit speed.

7. The cylinder-selective control process according to claim 3, further comprising the act of no longer correcting the fuel injection quantity above a defined engine rotational limit speed.

8. The cylinder-selective control process according to claim 1, wherein two correction values for the fuel injection quantity are computed per cylinder.

9. The cylinder-selective control process according to claim 2, wherein two correction values for the fuel injection quantity are computed per cylinder.

10. The cylinder-selective control process according to claim 3, wherein two correction values for the fuel injection quantity are computed per cylinder.

11. The cylinder-selective control process according to claim 5, wherein two correction values for the fuel injection quantity are computed per cylinder.

12. The cylinder-selective control process according to claim 1, wherein correction values are stored in a non-volatile manner.

13. The cylinder-selective control process according to claim 8, wherein correction values are stored in a non-volatile manner.

14. A system for implementing cylinder-selective control of an air-fuel ratio in a multi-cylinder internal-combustion engine, comprising:

a lambda probe provided in an exhaust pipe system, said lambda probe generating a voltage signal corresponding to an air-fuel ratio;

a determination unit receiving the voltage signal from the lambda probe, said determination unit determining the air-fuel ratio for each individual cylinder of the multi-cylinder internal-combustion engine;

a fuel metering unit determining a fuel injection quantity at least as a function of a basic fuel injection value and the determined air-fuel ratios of the individual cylinders;

a fuel supply unit supplying the fuel injection quantity determined by the fuel metering unit to the individual cylinders of the internal-combustion engine; and

wherein said determination unit includes means for detecting the voltage signal in a crank-angle-synchronous manner and assigning said detected voltage signal to a certain cylinder, means for determining a voltage deviation for each cylinder in relation to the voltage signals of sequentially adjacent cylinders, and means for carrying out a correction of the fuel injection quantity as a function of the voltage deviation.

15. A software product for controlling a system which implements cylinder-selective control of an air-fuel ratio in a multi-cylinder internal-combustion engine, comprising:

a computer readable medium having stored thereon program code segments that;

detect a voltage signal received from a lambda probe in a crank-angle-synchronous manner;

assign the detected voltage signal to a certain cylinder;

determine a voltage deviation for each cylinder of the multi-cylinder engine in relation to the detected voltage signals assigned to sequentially adjacent cylinders; and

correct a fuel injection quantity value as a function of the determined voltage deviation.