Method of and apparatus for controlling the ignition timing of an internal combustion engine

Claim 1

A method of controlling the ignition timing of an internal combustion engine, comprising the steps of: detecting the operating condition of the engine to produce at least one first electrical signal which indicates the detected operating condition; calculating, in response to the produced first electrical signal, a spark advance angle which corresponds to an optimum ignition timing at the detected operating condition; detecting whether or not the engine is in a first specific state in which said calculation is difficult to correctly perform, to produce a second electrical signal which indicates that the engine is in the first specific state; producing an indication of a reference speed related to the coolant temperature of said engine, said reference speed increasing as said coolant temperature is decreasing; detecting whether or not the engine is in a second specific state where the rotational speed of the engine is greater than said reference speed to produce a third electrical signal which indicates that the engine is in the second specific state; adjusting the timing of the sparks applied to the engine depending upon said calculated spark advance angle; and in response to said second and third electrical signals, only when the engine is in the first specific state but not in the second specific state, keeping the timing of the sparks applied to the engine at a predetermined fixed timing.

Claim 2

A method of controlling the ignition timing of an internal combustion engine, comprising the steps of: detecting the operating condition of the engine to produce at least one first electrical signal which indicates the detected operating condition; calculating, in response to the produced first electrical signal, a spark advance angle which corresponds to an optimum ignition timing at the detected operating condition; detecting whether or not the engine is in a first specific state in which said calculation is difficult to correctly perform, to produce a second electrical signal which indicates that the engine is in the first specific state; producing an indication of a reference speed related to the coolant temperature of said engine, said reference speed increasing as said coolant temperature is decreasing; detecting whether or not the engine is in a second specific state where the rotational speed of the engine is greater than said reference speed to produce a third electrical signal which indicates that the engine is in the second specific state; adjusting the timing of the sparks applied to the engine depending upon said calculated spark advance angle; and in response to said second and third electrical signals, only when the engine is in the first specific state but not in the second specific state, keeping the timing of the sparks applied to the engine at a predetermined fixed timing.

Claim 9

A method of controlling the ignition timing of an internal combustion engine, comprising the steps of: producing at least one first electrical signal which indicates the operating condition of the engine; producing a second electrical signal which indicates that a predetermined period of time has elapsed after starting; calculating, in response to said first electrical signal, a spark advance angle which corresponds to an optimum ignition timing at the operation condition indicated by said first electrical signal; adjusting the timing of the sparks applied to the engine depending upon said calculated spark advance angle when said second electrical signal is produced; keeping the timing of the sparks applied to the engine at a predetermined fixed timing when said second electrical signal is not produced; producing a third electrical signal which indicates the rotational speed of the engine; producing a fourth electrical signal which indicates the warm-up condition of the engine; producing, in response to said fourth electrical signal, a fifth electrical signal which indicates a reference engine speed dependent upon the warm-up condition of the engine; comparing said third electrical signal with said fifth electrical signal to produce a sixth electrical signal which indicates that the engine rotational speed is higher than said reference engine speed; and stopping the operation of keeping the spark timing at a predetermined fixed timing when said sixth electrical signal is produced and adjusting the spark timing depending upon said calculated spark advance angle.

Claim 10

A method of controlling the ignition timing of an internal combustion engine, comprising the steps of: producing at least one first electrical signal which indicates the operating condition of the engine; producing a second electrical signal which indicates that a predetermined period of time has elapsed after starting; calculating, in response to said first electrical signal, a spark advance angle which corresponds to an optimum ignition timing at the operation condition indicated by said first electrical signal; adjusting the timing of the sparks applied to the engine depending upon said calculated spark advance angle when said second electrical signal is produced; keeping the timing of the sparks applied to the engine at a predetermined fixed timing when said second electrical signal is not produced; producing a third electrical signal which indicates the rotational speed of the engine; producing a fourth electrical signal which indicates the warm-up condition of the engine; producing, in response to said fourth electrical signal, a fifth electrical signal which indicates a reference engine speed dependent upon the warm-up condition of the engine; comparing said third electrical signal with said fifth electrical signal to produce a sixth electrical signal which indicates that the engine rotational speed is higher than said reference engine speed; and stopping the operation of keeping the spark timing at a predetermined fixed timing when said sixth electrical signal is produced and adjusting the spark timing depending upon said calculated spark advance angle.

Claim 13

An apparatus for controlling the ignition timing of an internal combustion engine, comprising: means for producing at least one first electrical signal which indicates the operating condition of the engine; means for producing a second electrical signal which indicates that a predetermined period of time has elapsed after starting; means for calculating, in response to said first electrical signal, a spark advance angle which corresponds to an optimum ignition timing at the operation condition indicated by said first electrical signal; means for adjusting the timing of the sparks applied to the engine depending upon said calculated spark advance angle when said second electrical signal is produced; said calculating keeping the timing of the sparks applied to the engine at a predetermined fixed timing when said second electrical signal is not produced; means for producing a third electrical signal which indicates the rotational speed of the engine; means for producing a fourth electrical signal which indicates the warm-up condition of the engine; means for producing, in response to said fourth electrical signal, a fifth electrical signal which indicates a reference engine speed dependent upon the warm-up condition of the engine; means for comparing said third electrical signal with said fifth electrical signal to produce a sixth electrical signal which indicates that the engine rotational speed is higher than said reference engine speed; and said calculating means stopping the operation of keeping the spark timing at a predetermined fixed timing when said sixth electrical signal is produced and calculating said optimum ignition timing in accordance with said first electrical signal.

Claim 14

An apparatus for controlling the ignition timing of an internal combustion engine, comprising: means for producing at least one first electrical signal which indicates the operating condition of the engine; means for producing a second electrical signal which indicates that a predetermined period of time has elapsed after starting; means for calculating, in response to said first electrical signal, a spark advance angle which corresponds to an optimum ignition timing at the operation condition indicated by said first electrical signal; means for adjusting the timing of the sparks applied to the engine depending upon said calculated spark advance angle when said second electrical signal is produced; said calculating keeping the timing of the sparks applied to the engine at a predetermined fixed timing when said second electrical signal is not produced; means for producing a third electrical signal which indicates the rotational speed of the engine; means for producing a fourth electrical signal which indicates the warm-up condition of the engine; means for producing, in response to said fourth electrical signal, a fifth electrical signal which indicates a reference engine speed dependent upon the warm-up condition of the engine; means for comparing said third electrical signal with said fifth electrical signal to produce a sixth electrical signal which indicates that the engine rotational speed is higher than said reference engine speed; and said calculating means stopping the operation of keeping the spark timing at a predetermined fixed timing when said sixth electrical signal is produced and calculating said optimum ignition timing in accordance with said first electrical signal.