Apparatus for detecting imbalance abnormality in air-fuel ratio between cylinders in multi-cylinder internal combustion engine

• US 9,279,378 B2
• Filed: 02/21/2014
• Issued: 03/08/2016
• Est. Priority Date: 03/22/2013
• Status: Active Grant

• Current Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Original Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Inventors: Katayama, Akihiro, Akisada, Kazuhiro, Insixiengmai, Leuth, Maruta, Sei, Nakagoshi, Shinichi, Okada, Masahide
• Primary Examiner(s): Cronin, Stephen K
• Assistant Examiner(s): Kirby, Brian
• Application Number:
  US14/186,043
• Publication Number:
  US 20140288802A1
• Time in Patent Office: 746 Days
• Field of Search: 123/436, 123/673, 123/435, 123/406.24, 123/406.58, 123/672, 123674-675, 123690-692, 123 544- 552, 123/339.19, 123687-388, 123/703, 123/486, 701103-107, 701110-111, 73/350.9, 731/140.3, 731/140.4, 731/140.7, 7311425-11427, 731/144.9
• US Class Current: 1/1
• CPC Class Codes: F02D 2200/101 Engine speed
• CPC Class Codes: F02D 41/0082 per groups or banks F02D41/0087 takes precedence
• CPC Class Codes: F02D 41/0085 Balancing of cylinder outputs, e.g. speed, torque or air-fuel ratio
• CPC Class Codes: F02D 41/0097 using means for generating speed signals
• CPC Class Codes: F02D 41/1456 with sensor output signal being linear or quasi-linear with the concentration of oxygen

Abstract

An apparatus for detecting imbalance abnormality in an air-fuel ratio between cylinders in a multi-cylinder internal combustion engine is disclosed. The apparatus includes an imbalance determining unit programmed to determine imbalance in an air-fuel ratio of a first cylinder belonging to a cylinder group based upon a difference value between an index value correlative with a crank angular speed detected in the first cylinder and an index value correlative with a crank angular speed detected in a second cylinder belonging to another cylinder group, and further a correction unit programmed to correct the difference value for the first cylinder based upon the index value detected in at least one of other cylinders belonging to the same cylinder group as that of the first cylinder.

Claims

1. An apparatus for detecting imbalance abnormality in an air-fuel ratio between cylinders in a multi-cylinder internal combustion engine provided with a plurality of cylinder groups configured with a plurality of the cylinders, comprising:

an imbalance determining unit programmed to determine imbalance in an air-fuel ratio of a first cylinder belonging to a cylinder group based upon a difference value between an index value correlative with a crank angular speed detected in the first cylinder and an index value correlative with a crank angular speed detected in a second cylinder belonging to another cylinder group; and

a correction unit programmed to correct the difference value for the first cylinder by subtracting the difference value calculated for at least one of other cylinders belonging to the same cylinder group as that of the first cylinder or a value correlative therewith or by subtracting an average value of the difference values calculated for all other cylinders belonging to the same cylinder group as that of the first cylinder

wherein a notification is provided to the user if an imbalance in the air-fuel ratio between the first cylinder and the second cylinder is detected.

2. An apparatus according to claim 1, wherein

the imbalance determining unit is further programmed to compare the difference value for the first cylinder with a predetermined abnormality threshold to determine the imbalance in the air-fuel ratio of the first cylinder, and

the correction unit is further programmed to perform guard process such that an amount of correction performed by the correction unit is smaller in an absolute value than the abnormality threshold.

3. An apparatus according to claim 1, wherein

the imbalance determining unit is further programmed to determine the imbalance in the air-fuel ratio between the cylinders based upon a difference value of index values correlative with crank angular speeds detected respectively in at least one set of opposing cylinders that belong to the cylinder groups different with each other and are different by 360 degrees in a crank angle with each other.