Ignition timing control apparatus for an internal combustion engine
First Claim
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1. An ignition timing control apparatus for an internal combustion engine, comprising:
- ignition unit means for supplying an ignition signal to the engine at a predetermined ignition timing;
knocking sensor means, attached to the engine, for detecting the vibration of the engine and producing a knocking detection signal indicating the degree of occurring knocking;
control unit means including a processor, which has plural tables for providing basic ignition timings and is programed so as to execute the following steps;
selecting one of the plural tables on the basis of the knocking detection signal; and
determining, in accordance with the selected ignition timing table, an actual ignition timing to be supplied for said ignition unit as the predetermined ignition timing,characterized in thatthe plural ignition timing tables includes a first ignition timing table providing a basic ignition timing for high-octane fuel and a second ignition timing table providing a basic ignition timing for low-octane fuel, andwhen one of the first and second ignition timing tables is switched over to the other ignition timing table, the processor included in said control unit means further executes the processing of the following steps;
setting the other ignition timing table;
obtaining a difference between the basic ignition timings according to the first and second ignition timing tables;
reducing the difference with time at a predetermined constant rate;
correcting the basic ignition timing according to the one ignition timing table by the reducing difference so that when the reducing difference becomes zero, the actual ignition timing becomes equal to the basic ignition timing according to the other ignition timing table;
comparing the reducing difference with a certain threshold provided in advance; and
determining whether the one ignition timing table is to be maintained or switched over to the other ignition timing table in accordance with the comparison result of the preceding step.
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Abstract
There are provided a first ignition timing table for high-octane fuel and a second ignition timing table for low-octane fuel. When the second table is switched over to the first table, there is at first the difference in between basic ignition timings according to the first and second tables, and then the difference is reduced with time at a constant rate. An actual ignition timing during the switchover of an ignition timing table is determined by subtracting the reducing difference from the basic ignition timing according to the first table. The actual ignition timing when knocking is detected is compared with a predetermined threshold. If the former exceeds the latter, the second table is switched over to the first table, and otherwise the second table is maintained, whereby the actual ignition timing can be changed smoothly even during the switchover of an ignition timing table.
201 Citations
7 Claims
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1. An ignition timing control apparatus for an internal combustion engine, comprising:
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ignition unit means for supplying an ignition signal to the engine at a predetermined ignition timing; knocking sensor means, attached to the engine, for detecting the vibration of the engine and producing a knocking detection signal indicating the degree of occurring knocking; control unit means including a processor, which has plural tables for providing basic ignition timings and is programed so as to execute the following steps; selecting one of the plural tables on the basis of the knocking detection signal; and determining, in accordance with the selected ignition timing table, an actual ignition timing to be supplied for said ignition unit as the predetermined ignition timing, characterized in that the plural ignition timing tables includes a first ignition timing table providing a basic ignition timing for high-octane fuel and a second ignition timing table providing a basic ignition timing for low-octane fuel, and when one of the first and second ignition timing tables is switched over to the other ignition timing table, the processor included in said control unit means further executes the processing of the following steps; setting the other ignition timing table; obtaining a difference between the basic ignition timings according to the first and second ignition timing tables; reducing the difference with time at a predetermined constant rate; correcting the basic ignition timing according to the one ignition timing table by the reducing difference so that when the reducing difference becomes zero, the actual ignition timing becomes equal to the basic ignition timing according to the other ignition timing table; comparing the reducing difference with a certain threshold provided in advance; and determining whether the one ignition timing table is to be maintained or switched over to the other ignition timing table in accordance with the comparison result of the preceding step. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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Specification
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Current AssigneeHitachi Automotive Engineering Company Limited (Hitachi, Ltd.), Hitachi, Ltd.
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Original AssigneeHitachi Automotive Engineering Company Limited (Hitachi, Ltd.), Hitachi, Ltd.
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InventorsKatogi, Kozo, Otani, Asahiko
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Primary Examiner(s)WOLFE JR, WILLIS RAY
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Application NumberUS07/319,726Time in Patent Office392 DaysField of Search123/416, 123/417, 123/425, 123/435US Class Current123/406.32CPC Class CodesF02B 1/04 with fuel-air mixture admis...F02P 5/1527 with means allowing burning...Y02T 10/40 Engine management systems
