US 8,914,219 B2Granted

Method for operating an internal combustion engine

AssigneeAndreas Stihl AG & Co. KG

InventorsAndreas Neubauer, Jörg Präger

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Abstract

In a method for operating an internal combustion engine for adjusting a desired fuel/air mixture, wherein the rotary speed is determined by an operating curve based on a fuel/air mixture composition, wherein the operating curve has ascending and descending branches and a maximum, wherein a lambda value is smaller than 1 on the descending branch, it is first determined by statistic evaluation whether the operating point is on the ascending or descending branch. In a second method step, when the operating point is not on a desired branch of the operating curve desired as a starting point for a third method step, at least one operating parameter is changed until the operating point is positioned on the desired branch. In a third method step, the maximum of the operating curve is determined. Based on the determined maximum, the desired operating point of the internal combustion engine is then adjusted.

Claims25

Dependent claims

A method for operating an internal combustion engine, wherein the internal combustion engine comprises a combustion chamber, a piston that delimits the combustion chamber and drives in rotation a crankshaft, a device for supplying fuel, a device for supplying combustion air, and a device for detecting a rotary speed of the crankshaft, wherein the rotary speed is determined in accordance with an operating curve based on a composition of a fuel/air mixture, wherein operating points of the internal combustion engine are lying on the operating curve and the operating curve has an ascending branch, a maximum, and a descending branch, wherein a lambda value in the combustion chamber of the internal combustion engine is smaller than 1 in the range of the descending branch, wherein, for adjusting a desired fuel/air mixture composition, the method comprises:

in a first method step, determining by a statistic evaluation whether an operating point of the internal combustion engine is on the ascending branch or the descending branch;
in a second method step, when the operating point is not positioned on a desired branch of the operating curve that is desired as a starting point for a third method step, changing at least one operating parameter until the operating point is positioned on the desired branch of the operating curve by adjusting the at least one operating parameter in adjusting steps and, after a change of the at least one operating parameter, checking based on the statistic evaluation whether the operating point is on the desired branch;
in a third method step, determining a position of the maximum of the operating curve by adjusting the at least one operating parameter in adjusting steps in a direction toward the maximum of the operating curve and determining a resulting rotary speed change, wherein in the second method step the adjusting steps for adjusting the at least one operating parameter are multiple times greater than the adjusting steps for adjusting the at least one operating parameter in the third method step;
and
in a fourth method step, based on the determined maximum of the operating curve, adjusting the desired operating point of the internal combustion engine.

2 more elements

A method for operating an internal combustion engine, wherein the internal combustion engine is a single-cylinder internal combustion engine and comprises a combustion chamber, a piston that delimits the combustion chamber and drives in rotation a crankshaft, a device for supplying fuel, a device for supplying combustion air, and a device for detecting a rotary speed of the crankshaft, wherein the rotary speed is determined in accordance with an operating curve based on a composition of a fuel/air mixture, wherein operating points of the internal combustion engine are lying on the operating curve and the operating curve has an ascending branch, a maximum, and a descending branch, wherein a lambda value in the combustion chamber of the internal combustion engine is smaller than 1 in the range of the descending branch, wherein, for adjusting a desired fuel/air mixture composition, the method comprises:

in a first method step, determining by a statistic evaluation whether an operating point of the internal combustion engine is on the ascending branch or the descending branch by determining in which preceding engine cycles a combustion has occurred in the combustion chamber, wherein, for determining whether a combustion has occurred in an engine cycle, a rotary speed change resulting from the engine cycle is determined;
in a second method step, when the operating point is not positioned on a desired branch of the operating curve that is desired as a starting point for a third method step, changing at least one operating parameter until the operating point is positioned on the desired branch of the operating curve;
in a third method step, determining a position of the maximum of the operating curve due to changing the at least one operating parameter;
and
in a fourth method step, based on the determined maximum of the operating curve, adjusting the desired operating point of the internal combustion engine.

2 more elements

Dependencies are inferred from the claim text.

Facts

Application: 12/829,430Filed 2 Jul 2010
Priority: DE 10 2009 031 7074 Jul 2009
Published: US 2011/0004395 A16 Jan 2011
Granted: 16 Dec 2014
Term ends: Not estimatedThe source records don’t support an estimate.

Classification9 codes

F02D 41/16
Introducing closed-loop corrections: for idling
F02D 41/1401
Introducing closed-loop corrections: characterised by the control or regulation method
F02D 41/1497
Introducing closed-loop corrections: with detection of the mechanical response of the engine
F02D 41/2451
Methods of calibrating or learning: characterised by what is learned or calibrated