Control apparatus for internal combustion engine

Abstract

The present invention provides a control apparatus for an internal combustion engine which can make a determination on fuel property with high accuracy without causing a cost increase. The control apparatus for the internal combustion engine includes: an intake air amount control unit for controlling an intake air amount of the engine;

Description

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings:

FIG. 1 is a block diagram showing an entire system including a control apparatus for an internal combustion engine according to a first embodiment of the present invention;

FIG. 2 is a timing chart showing catalyst heat-up control performed by catalyst heat-up control means of an ECU of FIG. 1;

FIG. 3 is a flowchart showing how the catalyst heat-up control means of the ECU according to the first embodiment of the present invention operates to perform catalyst heat-up control;

FIG. 4 is a flowchart showing how fuel property determining means of the ECU according to the first embodiment of the present invention operates to make a determination on fuel property;

FIG. 5 is an explanatory diagram showing a relationship between a coolant temperature and a threshold in the determination on fuel property shown in FIG. 4;

FIG. 6 is a flowchart showing how fuel injection amount changeover means of the ECU according to the first embodiment of the present invention operates to make a changeover in fuel injection amount based on fuel property;

FIG. 7 is a timing chart showing how the fuel property determining means of the ECU according to the first embodiment of the present invention operates to make a determination on fuel property;

FIG. 8 is a flowchart showing how fuel property determining means of an ECU according to a second embodiment of the present invention operates to make a determination on fuel property;

FIG. 9 is an explanatory diagram showing a relationship between a coolant temperature and a threshold in the determination on fuel property shown in FIG. 8;

FIG. 10 is a timing chart showing how the fuel property determining means of the ECU according to the second embodiment of the present invention operates to make a determination on fuel property;

FIG. 11 is a flowchart showing how fuel property determining means of an ECU according to a third embodiment of the present invention operates to make a determination on fuel property;

FIG. 12 is an explanatory diagram showing a relationship between a coolant temperature and a threshold in the determination on fuel property shown in FIG. 11;

FIG. 13 is a timing chart showing how the fuel property determining means of the ECU according to the third embodiment of the present invention operates to make a determination on fuel property;

FIG. 14 is a flowchart showing how fuel property determining means of an ECU according to a fourth embodiment of the present invention operates to make a determination on fuel property;

FIG. 15 is an explanatory diagram showing a relationship between a coolant temperature and a threshold in the determination on fuel property shown in FIG. 14;

FIG. 16 is a timing chart showing how the fuel property determining means of the ECU according to the fourth embodiment of the present invention operates to make a determination on fuel property;

FIG. 17 is a flowchart showing how fuel property determining means of an ECU according to a fifth embodiment of the present invention operates to make a determination on fuel property;

FIG. 18 is an explanatory diagram showing a relationship between a coolant temperature and a threshold in the determination on fuel property shown in FIG. 17; and

FIG. 19 is a timing chart showing how the fuel property determining means of the ECU according to the fifth embodiment of the present invention operates to make a determination on fuel property.

Claims

1. A control apparatus for an internal combustion engine, comprising: intake air amount control means for controlling an intake air amount of the internal combustion engine;ignition timing control means for controlling an ignition timing of the internal combustion engine;catalyst heat-up control means for increasing the intake air amount after cold start of the internal combustion engine and performing control for retarding the ignition timing;air-fuel ratio detecting means for detecting an air-fuel ratio of exhaust gas in the internal combustion engine; andfuel property determining means for making a determination on fuel property through a comparison between a parameter value calculated from the air-fuel ratio and a preset reference value when the catalyst heat-up control means performs the control for retarding the ignition timing.

2. A control apparatus for an internal combustion engine according to claim 1, further comprising a first air-fuel ratio difference integrating means for integrating a difference between the air-fuel ratio and a preset reference air-fuel ratio until a predetermined time elapses since start of the control for retarding the ignition timing through the catalyst heat-up control means, wherein the fuel property determining means uses an integrated value of a first air-fuel ratio difference, which has been integrated by the first air-fuel ratio difference integrating means, as the parameter value.

3. A control apparatus for an internal combustion engine according to claim 1, further comprising: average air-fuel ratio calculating means for calculating an average of the air-fuel ratio immediately before start of the control for retarding the ignition timing through the catalyst heat-up control means to output an average air-fuel ratio; anda second air-fuel ratio difference integrating means for integrating a difference between the air-fuel ratio and the average air-fuel ratio until a predetermined time elapses since start of the control for retarding the ignition timing through the catalyst heat-up control means,wherein the fuel property determining means uses an integrated value of a second air-fuel ratio difference, which has been integrated by the second air-fuel ratio difference integrating means, as the parameter value.

4. A control apparatus for an internal combustion engine according to claim 1, further comprising: air-fuel ratio feedback correction means for outputting an air-fuel ratio feedback correction amount for correcting a fuel injection amount such that the air-fuel ratio coincides with a target air-fuel ratio; andair-fuel ratio feedback correction amount integrating means for integrating the air-fuel ratio feedback correction amount until a predetermined time elapses since start of the control for retarding the ignition timing through the catalyst heat-up control means,wherein the fuel property determining means uses an integrated value of an air-fuel ratio feedback correction amount, which has been integrated by the air-fuel ratio feedback correction amount integrating means, as the parameter value.

5. A control apparatus for an internal combustion engine according to claim 1, further comprising air-fuel ratio lean peak detecting means for detecting a lean peak of the air-fuel ratio until a predetermined time elapses since start of the control for retarding the ignition timing through the catalyst heat-up control means, wherein the fuel property determining means uses a value of the lean peak of the air-fuel ratio, which has been detected by the air-fuel ratio lean peak detecting means, as the parameter value.

6. A control apparatus for an internal combustion engine according to claim 1, further comprising air-fuel ratio lean time detecting means for detecting a time in which the air-fuel ratio is leaner than a preset reference air-fuel ratio until a predetermined time elapses since start of the control for retarding the ignition timing through the catalyst heat-up control means, wherein the fuel property determining means uses a value of an air-fuel ratio lean time, which has been detected by the air-fuel ratio lean time detecting means, as the parameter value.

7. A control apparatus for an internal combustion engine according to claims 1, wherein the reference value is set in accordance with a temperature of a coolant for cooling the internal combustion engine.

8. A control apparatus for an internal combustion engine according to claims 1, further comprising: fuel property storing means for storing a result of a determination made by the fuel property determining means; andfuel injection amount changeover means for making a changeover in a fuel injection amount based on the result of the determination,wherein the fuel injection amount changeover means increases the fuel injection amount when the result of the determination made by the fuel property determining means indicates low volatile fuel, in comparison with a fuel injection amount at a time when the result of the determination made by the fuel property determining means indicates standard fuel.