Method for operating an internal combustion engine

• US 20070033997A1
• Filed: 08/02/2006
• Published: 02/15/2007
• Est. Priority Date: 08/04/2005
• Status: Active Grant

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Schueler, Matthias, Mader, Christian, Youssef, Mohamed, Hugel, Christian
• Granted Patent: US 7,305,872 B2
• Time in Patent Office: Days
• US Class Current: 73/117.30
• CPC Class Codes: F02B 77/085 with sensors measuring combustion processes, e.g. knocking, pressure, ionization, combustion flame
• CPC Class Codes: F02D 2200/025 Engine noise, e.g. determined by using an acoustic sensor
• CPC Class Codes: F02D 2400/08 Redundant elements, e.g. two sensors for measuring the same parameter
• CPC Class Codes: F02D 41/123 the fuel injection being cut-off
• CPC Class Codes: F02D 41/222 relating to the failure of sensors or parameter detection devices
• CPC Class Codes: F02D 41/2474 Characteristics of sensors
• CPC Class Codes: G01M 15/08 by monitoring pressure in cylinders
• CPC Class Codes: G01M 15/12 by monitoring vibrations
• CPC Class Codes: Y02T 10/40 Engine management systems

Abstract

In an internal combustion engine, a structure-borne noise generated in a combustion chamber is detected by a structure-borne noise sensor. A quantity is ascertained on the basis of the structure-borne noise signal. A reference quantity of an undrifted structure-borne noise sensor is ascertained for a certain reference operating state for the combustion chamber, during continuous operation of the engine the quantity is ascertained for the reference operating state, and from a change over time of the ascertained quantity with respect to the reference quantity, a drift of the structure-borne noise sensor is ascertained.

Claims

1. A method for operating an internal combustion engine comprising:

detecting a structure-borne noise generated by a pressure change in a combustion chamber by at least one structure-borne noise sensor;

ascertaining a quantity as a function of the structure-borne noise signal, using an undrifted structure-borne noise sensor, wherein during continuous operation of the engine the quantity is ascertained by the at least one structure-borne noise sensor; and

ascertaining a drift of the structure-borne noise sensor from a change over time of the quantity ascertained during continuous operation, with respect to a reference quantity.

2. The method according to claim 1, further comprising obtaining a drift-compensated structure-borne noise signal on the basis of the ascertained drift and the detected structure-borne noise signal.

3. The method according to claim 1, further comprising plausibility-checking a detected drift using a signal of at least one second sensor, specific to a same combustion chamber.

4. The method according to claim 3, further comprising:

forming a first ratio from reference quantities of the two sensors for the same combustion chamber;

forming a second ratio from drift-compensated structure-borne noise signals of the two sensors for the same combustion chamber; and

for checking the drift compensation, comparing a difference between the first ratio and the second ratio to at least one limiting value.

5. The method according to claim 1, further comprising ascertaining the reference quantity on a reference engine.

6. The method according to claim 5, wherein the reference quantity is a maximum amplitude.

7. The method according to claim 1, further comprising:

ascertaining the reference quantity for different reference operating states; and

forming a reference characteristic curve from them.

8. The method according to claim 1, further comprising ascertaining quantities in a reference operating state in which no fuel is injected.

9. The method according to claim 2, further comprising performing a cylinder diagnosis during engine operation, using the drift-compensated structure-borne noise signal.

10. A computer-readable medium containing a computer program which, when executed by a processor, performs the following steps for operating an internal combustion engine:

detecting a structure-borne noise generated by a pressure change in a combustion chamber by at least one structure-borne noise sensor;

ascertaining a quantity as a function of the structure-borne noise signal, using an undrifted structure-borne noise sensor, wherein during continuous operation of the engine the quantity is ascertained by the at least one structure-borne noise sensor; and

ascertaining a drift of the structure-borne noise sensor from a change over time of the quantity ascertained during continuous operation, with respect to a reference quantity.

11. A control/regulating unit for an internal combustion engine, comprising:

means for detecting a structure-borne noise generated by a pressure change in a combustion chamber by at least one structure-borne noise sensor;

means for ascertaining a quantity as a function of the structure-borne noise signal, using an undrifted structure-borne noise sensor, wherein during continuous operation of the engine the quantity is ascertained by the at least one structure-borne noise sensor; and

means for ascertaining a drift of the structure-borne noise sensor from a change over time of the quantity ascertained during continuous operation, with respect to a reference quantity.