Method for detecting combustion misfires at one or more permanently misfiring cylinders

• US 5,893,042 A
• Filed: 09/23/1996
• Issued: 04/06/1999
• Est. Priority Date: 09/21/1995
• Status: Expired due to Fees

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Forster, Jurgen, Lohmann, Andrea, Ries-Muller, Klaus
• Primary Examiner(s): Zanelli, Michael
• Assistant Examiner(s): PIPALA, EDWARD J
• Application Number:
  US08/717,898
• Time in Patent Office: 925 Days
• Field of Search: 701/29, 701/99, 701/101, 701/102, 701/110, 701/111, 701/114, 73/116, 73/117.2, 73/117.3, 123/419, 123/436, 123/479, 123/480, 123/481, 364/550, 364/551.01
• US Class Current: 701/111
• CPC Class Codes: G01M 15/11 by detecting misfire

Abstract

The invention is directed to a method for detecting combustion misfires on the basis of a first input feature signal in which the nonuniformity of the rotational movement (on the basis of rpm or segment times) of the engine is mapped within the first order. According to the method, a permanent misfire at a cylinder is preliminarily detected when a first threshold value is exceeded by the amount of a first input feature signal and a detection signal for permanent misfires at several cylinders is active (and in this way, permanent misfires at several cylinders are recognized) when a threshold value is exceeded by the magnitude of further assigned input feature signals or by the magnitude of the first feature signal when a second threshold value is exceeded. The detection signal for permanent misfires at a cylinder is always switched to be inactive when there is an active detection signal for permanent misfire at several cylinders. When there is an inactive detection signal for permanent misfire at several cylinders, the preliminary detection signal for the permanent misfire at a cylinder becomes finally active and permanent misfires at a cylinder are recognized.

Claims

1. A method for detecting combustion misfires in an internal combustion engine, the method comprising the steps of:

providing a first input feature signal wherein the nonuniformity of the rotational movement of the engine is defined on the basis of rpm or segment times and mapped within a first order;

comparing the magnitude of said first input feature signal to a first threshold value and to a second threshold value greater than said first threshold value;

providing additional input feature signals wherein the nonuniformity of the rotational movement of the engine is defined on the basis of rpm or segment times and mapped within additional orders;

the number of said additional input feature signals being dependent upon the number of cylinders of the engine;

providing threshold values assigned to respective ones of said additional orders;

comparing the magnitudes of said additional feature signals to a corresponding threshold value of each of said orders;

preliminarily recognizing a permanent misfire at a cylinder when said magnitude of said first input feature signal exceeds said first threshold value;

causing a recognition signal to be active for permanent misfires at several cylinders and thereby recognize permanent misfires at several cylinders when the magnitude of the corresponding additional input feature signal exceeds at least one of the threshold values or when the magnitude of said first input feature signal exceeds said second threshold value;

always switching off the recognition signal for permanent misfires at a cylinder when there is an active recognition signal for permanent misfires at several cylinders; and

,

causing said preliminary recognition signal for permanent misfires to become finally active and thereby recognize permanent misfires at a cylinder when the recognition signal for permanent misfires at several cylinders is inactive.

2. The method of claim 1, comprising the further step of:

switching a reference generator in the signal path of the individual input feature signal before or after formation of the absolute value for the threshold value comparison; and

,

performing a signal smoothing in said reference generator via linear or nonlinear lowpass filtering.

3. The method of claim 1, comprising the further step of providing an identification of the misfiring cylinder when there is an inactive recognition signal for permanent misfires at several cylinders and when there is an active recognition signal for permanent misfires at one cylinder.

4. The method of claim 1, comprising the further step of providing an identification of at least two permanent misfiring cylinders when there is an active recognition signal for permanent misfires at several cylinders.