Ignition timing control apparatus for an internal combustion engine
First Claim
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 programmed 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 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.
11 Citations
12 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 programmed 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 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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8. An ignition timing control apparatus for controlling an ignition unit of an internal combustion engine, comprising:
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a knocking sensor, to be attached to the engine, for detecting vibration of the engine and for producing a knocking detection signal indicating the occurrence of knocking; and a control unit for generating an ignition timing signal to control said ignition unit on the basis of selected basic ignition timing values, including a processor having means for storing at least a first ignition timing table of basic ignition timing values for high-octane fuel and a second ignition timing table of basic ignition timing values for low-octane fuel, said processor being programmed to execute the following steps; (a) at the time of starting of the engine, selecting said second ignition timing table to provide basic ignition timing values for generating said ignition timing signal; (b) detecting a predetermined operational condition of the engine after the starting of the engine; (c) automatically switching from said second ignition timing table to said first ignition timing table to provide basic ignition timing values for generating said ignition timing signal upon detecting said predetermined operational condition; and (d) determining whether to continue to generate said ignition timing signal on the basis of basic ignition timing values from said first ignition timing table or to switch back to said second ignition timing table in accordance with the receipt of a knocking detecting signal..Iaddend. .Iadd. - View Dependent Claims (9, 10)
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11. reduced to zero..Iaddend. .Iadd.16. An ignition timing control apparatus according to claim 15, wherein said processor is programmed to execute the following additional step:
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(c) during the switching over performed in step (b), determining whether to continue to generate said ignition timing signal on the basis of basic ignition timing values from said other of said first and second ignition timing tables or to switch back to said one of said first and second ignition timing tables in accordance with receipt of a knocking detection signal..Iaddend. .Iadd.17. An ignition timing control apparatus according to claim 16, wherein said step (c) comprises; (c1) detecting receipt of a knocking detection signal during substeps (b2) to (b4); (c2) comparing the value of said correction amount to a predetermined threshold value; and (c3) switching back to said one of said first and second ignition tables when the value of said correction amount has a predetermined relationship to said threshold value when said knocking detection signal is
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12. received..Iaddend. .Iadd.18. An ignition timing control apparatus according to claim 15, wherein said correction amount is determined from the difference between basic ignition timing values in said first and second ignition timing tables..Iaddend.
Specification