| US 7,483,781 B2 | ||
| Engine control apparatus | ||
| Keiji Wakahara, Inazawa (Japan); and Takeshi Fujimoto, Obu (Japan) | ||
| Assigned to Denso Corporation, (Japan) | ||
| Filed on Oct. 30, 2007, as Appl. No. 11/929,293. | ||
| Claims priority of application No. 2006-305612 (JP), filed on Nov. 10, 2006. | ||
| Prior Publication US 2008/0110447 A1, May 15, 2008 | ||
| Int. Cl. B60T 7/12 (2006.01); F02D 41/00 (2006.01) | ||
| U.S. Cl. 701—103 [123/672] | 9 Claims |
| 1. An engine control apparatus comprising:
an air-fuel ratio sensor disposed in an exhaust pipe of a multi-cylinder engine for producing a sensor signal indicative of
an exhaust air-fuel ratio of exhaust gas of the engine; and
an electronic control unit for executing a feedback control to control a mixture air-fuel ratio of air-fuel mixture supplied
to each cylinder of the engine based on the exhaust air-fuel ratio,
wherein the control unit includes
an exhaust ratio change rate integration means for calculating an exhaust air-fuel ratio change rate at every predetermined
interval and integrating an absolute value of the exhaust air-fuel ratio change rate, and
a diagnosis means for diagnosing whether an air-fuel ratio in any one of cylinders of the engine is abnormal based on an integration
value of the exhaust air-fuel ratio change rate.
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