ABNORMALITY DIAGNOSIS APPARATUS FOR INTERNAL COMBUSTION ENGINE

• US 20090314071A1
• Filed: 06/17/2009
• Published: 12/24/2009
• Est. Priority Date: 06/23/2008
• Status: Active Grant

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: MUKAI, Yasuo
• Granted Patent: US 8,225,647 B2
• Time in Patent Office: Days
• US Class Current: 73/114.380
• CPC Class Codes: F02D 19/0623 Failure diagnosis or prevention; Safety measures; Testing
• CPC Class Codes: F02D 19/084 Blends of gasoline and alcohols, e.g. E85
• CPC Class Codes: F02D 19/087 with determination of densities, viscosities, composition, concentration or mixture ratios of fuels
• CPC Class Codes: F02D 19/088 by estimation, i.e. without using direct measurements of a corresponding sensor
• CPC Class Codes: F02D 2200/0612 determined by estimation
• CPC Class Codes: F02D 41/0025 Controlling engines characterised by use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures
• CPC Class Codes: F02D 41/22 Safety or indicating devices for abnormal conditions in air/fuel ratio feedback systems F02D41/1495, in electric control linkage F02D11/107, in purge control systems F02M25/0809
• CPC Class Codes: G01N 33/2852 alcohol/fuel mixtures
• CPC Class Codes: Y02T 10/30 Use of alternative fuels, e.g. biofuels
• CPC Class Codes: Y02T 10/40 Engine management systems

Abstract

An alcohol concentration sensor detecting alcohol concentration of fuel is provided in a fuel tank or a fuel passage. An alcohol concentration detected at a previous driving of an engine is stored in a backup RAM. When a current alcohol concentration is different from the previous alcohol concentration, a procedure of an abnormality diagnosis is prohibited or invalidated until all of the fuel remaining in the fuel passage is consumed.

Claims

1. An abnormality diagnosis apparatus for an internal combustion engine, including a fuel property detecting means for detecting a property of a fuel supplied from a fuel tank to a fuel injector, the abnormality diagnosis apparatus performing an abnormality diagnosis with respect to a specified object based on the property of the fuel, the abnormality diagnosis apparatus comprising:

an erroneous diagnosis preventing means for prohibiting or invalidating processes of the abnormality diagnosis until a specified time period has passed when a currently detected property of the fuel is different from a previously detected property of the fuel.

4. An abnormality diagnosis apparatus according to claim 1, wherein

the specified time period is established based on a time which is required for all of the fuel remaining in a fuel passage between the fuel property detecting means and the fuel injector to be injected or on an integral fuel injection quantity.

5. An abnormality diagnosis apparatus according to claim 1, wherein

the fuel property detecting means includes an alcohol concentration sensor detecting an alcohol concentration of the fuel.

6. An abnormality diagnosis apparatus according to claim 1, wherein

the fuel property detecting means is provided in the fuel tank.

2. An abnormality diagnosis apparatus for an internal combustion engine, including a fuel property detecting means for detecting a property of a fuel supplied from a fuel tank to a fuel injector, the abnormality diagnosis apparatus performing an abnormality diagnosis with respect to a specified object based on the property of the fuel, the abnormality diagnosis apparatus comprising:

an erroneous diagnosis preventing means for performing an abnormality diagnosis with respect to a specified object by use of an abnormality threshold which is established according to a previously detected property of the fuel until a specified time period has passed when a currently detected property of the fuel is different from the previously detected property of the fuel.

3. An abnormality diagnosis apparatus according to claim 2, wherein

the erroneous diagnosis preventing means makes a final diagnosis result based on a diagnosis result by use of a threshold which is established according to the previously detected property of the fuel and on a diagnosis result by use of a threshold which is established according to the currently detected property of the fuel until the specified time period has passed when the currently detected property of the fuel is different from the previously detected property of the fuel.

7. An abnormality diagnosis apparatus for an internal combustion engine, including a fuel property estimating means for estimating a fuel property based on an engine control condition which varies due to the fuel property, the abnormality diagnosis apparatus performing an abnormality diagnosis with respect to a specified object based on the fuel property, the abnormality diagnosis apparatus comprising:

a nonvolatile memory means for storing the estimated fuel property; and

an erroneous diagnosis preventing means for invalidating processing data of the abnormality diagnosis which has been executed from a starting of the engine until it becomes apparent that a currently estimated fuel property is different from a previously estimated fuel property stored in the nonvolatile memory means.

8. An abnormality diagnosis apparatus according to claim 7, wherein

the fuel property estimating means includes:

an estimating means for estimating a fuel property based a control condition of an air-fuel ratio feedback control which is executed based on an output of an exhaust gas sensor disposed in an exhaust passage of the engine; and

a means for using a previous fuel property stored in the memory means as a current fuel property temporarily until the exhaust gas sensor is activated so that the air-fuel ratio feedback control can be executed.

9. An abnormality diagnosis apparatus according to claim 7, wherein

the fuel property estimating means includes a means for prohibiting an estimation of the fuel property until a specified time period has elapsed after engine is started.

10. An abnormality diagnosis apparatus according to claim 9, wherein

the specified time period is established based on a time which is required for all of the fuel remaining in a fuel passage between a fuel tank and a fuel injector to be injected or on an integral fuel injection quantity.

11. An abnormality diagnosis apparatus according to claim 7, wherein

the fuel property estimating means estimates an alcohol concentration of the fuel.