Method for operating an internal combustion engine having a plurality of cylinders in homogeneous operation

Patent metadata

Field	Value
Publication number	US-9388755-B2
Application number	US-201314065227-A
Country	US
Kind code	B2
Filing date	Oct 28, 2013
Priority date	Oct 29, 2012
Publication date	Jul 12, 2016
Grant date	Jul 12, 2016

Abstract

A method is described for operating an internal combustion engine, having a plurality of cylinders in an homogeneous operation, in which an exhaust gas lambda value and an unsteady running of the internal combustion engine are recorded, a mixture composition being cyclically varied, at least intermittently. In a test operation, the mixture composition is cyclically varied, in a selected cylinder, about a determined lambda value, whereas meanwhile the mixture composition is held constant in the remaining cylinders. From the magnitude of a cyclical fluctuation of the unsteady running or of a variable characterizing this, one may conclude upon a trimming of the mixture composition in the selected cylinder.

First claim

What is claimed is:

1. A method for operating an internal combustion engine having a plurality of cylinders in a homogeneous operation, comprising:
in a test operation, while holding a mixture composition constant in remaining cylinders, cyclically varying a mixture composition in a selected cylinder between a first period in which a lambda value of the mixture composition in the selected cylinder is controlled in a positive direction with respect to a predetermined first lambda value and a second period in which the lambda value of the mixture composition in the selected cylinder is controlled in a negative direction with respect to the predetermined first lambda value;
recording values during the cyclical variation;
determining a magnitude of a cyclical fluctuation of the recorded values at transitions between immediately succeeding pairs of the first and second periods; and
based on the determined magnitude, determining a trimming of the mixture composition in the selected cylinder.

2. The method as recited in claim 1 , wherein the predetermined lambda value is about 1.

3. The method as recited in claim 1 , wherein the mixture composition of the remaining cylinders is held constant at the lambda value of 1, in the test operation.

4. The method as recited in claim 1 , wherein, in the case of an internal combustion engine that includes a number ‘n’ of cylinders, the control in the cyclical variation is for varying the mixture composition with a variation amplitude that is ‘n’ times a variation of all cylinders in a normal operation.

5. The method as recited in claim 1 , wherein the trimming ascertained of the selected cylinder is used to correct at least one of a fuel quantity that is to be injected and an air quantity of the selected cylinder of the internal combustion engine.

6. The method as recited in claim 1 , wherein the determining of the magnitude of the cyclical fluctuation includes:
in the test operation, forming from the recorded values a first unsteady running average value of a plurality of unsteady running values associated with the second period in which the mixture composition is relatively rich, and forming from the recorded values a second unsteady running average value of a plurality of unsteady running values associated with the first period in which the mixture composition is relatively lean;
forming a difference of the two unsteady running average values; and
comparing the difference to at least one threshold value to form a result.

7. The method as recited in claim 6 , wherein, if the difference is less than a lower threshold value, the trimming is one that, when applied, trims the selected cylinder towards rich, and, if the difference is greater than an upper threshold value, the trimming is one that, when applied, trims the selected cylinder towards lean.

8. A method for operating an internal combustion engine having a plurality of cylinders in an homogeneous operation in which an exhaust gas lambda value and an unsteady running of the internal combustion engine are recorded and a mixture composition is varied cyclically at least intermittently, the method comprising:
in a test operation, cyclically varying a mixture composition in a selected cylinder about a determined lambda value while holding constant a mixture composition in remaining cylinders;
forming a first unsteady running average value of a plurality of unsteady running values associated with a respective phase of the cyclical variation having a relatively rich mixture composition;
forming a second unsteady running average value of a plurality of unsteady running values associated with a respective phase of the cyclical variation having a relatively lean mixture composition;
forming a difference of the two unsteady running average values;
comparing the difference to at least one threshold value to form a result; and
from the result of the comparing, determining a trimming of the mixture composition in the selected cylinder.

9. The method as recited in claim 8 , wherein, if the difference is less than a lower threshold value, the trimming is one that, when applied, trims the selected cylinder towards rich, and if the difference is greater than an upper threshold value, the trimming is one that, when applied, trims the selected cylinder towards lean.

10. A non-transitory computer-readable medium on which a computer program is stored, the computer program containing instructions that are executable by a processor and that, when executed by the processor, cause the processor to perform a method for operating an internal combustion engine having a plurality of cylinders in an homogeneous operation, the method comprising:
in a test operation, while holding a mixture composition constant in remaining cylinders, cyclically varying a mixture composition in a selected cylinder between a first period in which a lambda value of the mixture composition in the selected cylinder is controlled in a positive direction with respect to a predetermined first lambda value and a second period in which the lambda value of the mixture composition in the selected cylinder is controlled in a negative direction with respect to the predetermined first lambda value;
recording values during the cyclical variation;
determining a magnitude of a cyclical fluctuation of the recorded values at transitions between immediately succeeding pairs of the first and second periods; and
based on the determined magnitude, determining a trimming of the mixture composition in the selected cylinder.

11. A control device for an internal combustion engine, comprising:
processing circuitry; and
a non-transitory computer-readable medium on which a computer program is stored, the computer program including instructions that are executable by the processing circuitry and that, when executed by the processing circuitry, cause the processing circuitry to perform a method for operating an internal combustion engine having a plurality of cylinders in an homogeneous operation, the method comprising:
in a test operation, while holding a mixture composition constant in remaining cylinders, cyclically varying a mixture composition in a selected cylinder between a first period in which a lambda value of the mixture composition in the selected cylinder is controlled in a positive direction with respect to a predetermined first lambda value and a second period in which the lambda value of the mixture composition in the selected cylinder is controlled in a negative direction with respect to the predetermined first lambda value;
recording values during the cyclical variation;
determining a magnitude of a cyclical fluctuation of the recorded values at transitions between immediately succeeding pairs of the first and second periods; and
based on the determined magnitude, determining a trimming of the mixture composition in the selected cylinder.

Assignees

• Bosch Gmbh Robert

Inventors

• Jessen Holger
• Tiebel Wolfgang

Classifications

• F02D41/1408

  Dithering techniques · CPC title

• F02D41/0085 Primary

  Balancing of cylinder outputs, e.g. speed, torque or air-fuel ratio · CPC title

• F02D41/1498

  measuring engine roughness · CPC title

• F02D41/1454

  the characteristics being an oxygen content or concentration or the air-fuel ratio · CPC title

• F02D2200/101

  Engine speed · CPC title