Internal-combustion engines – Combustion chamber means combined with air-fuel mixture...
Patent
1990-07-13
1992-04-21
Dolinar, Andrew M.
Internal-combustion engines
Combustion chamber means combined with air-fuel mixture...
123424, 123602, F02P 5155
Patent
active
051057859
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to an ignition timing control apparatus for changing the ignition timing of an internal combustion engine in accordance with the opening degree of a throttle valve which operates to adjust the amount of intake air sucked into the engine.
BACKGROUND ART
Conventionally, ignition timing control apparatus have been known which operates to change ignition timing of an internal combustion engine in accordance with the opening degree of a throttle valve which adjusts the amount of intake air sucked into the engine. In such ignition timing control apparatus, ignition timing is controlled in proportion to the change rate of the opening degree of a throttle valve as shown in FIG. 1. Specifically, as shown in FIG. 1(a), as the throttle opening changes from the closed state toward the fully open state, ignition timing is controlled to advance as shown in FIG. 1(b). On the other hand, as the throttle opening changes from the fully open state toward the closed state, ignition timing is controlled to retard in proportion to the rate of change of the throttle opening.
With a marine vehicle, for example, equipped with such an ignition timing control apparatus, however, brake is often applied to suddenly decelerate the vehicle by changing the engine operation from a forward drive into a rearward drive so as to make the propellant screw blade revolve in a reverse direction. In this case, the engine is subjected to an abrupt increase in load because the screw blade is brought into the rearward drive in spite of the marine vehicle still remaining in a forward driving state.
On the other hand, upon such a change in the drive condition of the engine, the opening degree of the throttle is normally in a fully closed state and ignition timing is thus at the most retarded piston position, so the engine is easily caused to stall due to an abrupt change in the load on the engine.
The present invention is proposed to solve the above-described problems, and has for its object the provision of an ignition timing control apparatus which is able to prevent a marine engine from being stalled upon rapid decelerations of a marine vehicle.
DISCLOSURE OF THE INVENTION
Specifically, the present invention comprises a throttle sensor for outputting a voltlage which is in inverse proportion to the opening degree of a throttle valve, a retardation moderating ciruit for receiving the output signal of the throttle sensor and having a diode connected in parallel with a resistor of an integration circuit, an ignition timing calculation circuit for outputting an ignition timing control signal which advances in inverse proportion to the output voltage of the retardation moderating circuit, wherein when the throttle opening changes toward the closing direction, the output of the retardation moderation circuit is controlled to gradually increase so that the ignition timing changes more gradually than the throttle opening does.
In addition, the present invention further comprises a timer circuit for disabling the output of the ignition timing calculation circuit for a predetermined time from the engine starting period, and a compensation circuit for increasing the output voltage of the retardation moderating circuit to a prescribed value so as to stabilize the engine operation during engine starting.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a characteristic view showing the relationship between ignition timing and throttle opening in a conventional ignition timing control apparatus;
FIG. 2 is a circuit diagram showing an ignition timing control apparatus of a first embodiment of the present invention;
FIG. 3 is a characteristic view showing the relationship between ignition timing and throttle opening in the apparatus of FIG. 2;
FIG. 4 is a circuit diagram showing an ignition timing control apparatus of a second embodiment of the present invention; and
FIG. 5 is a circuit diagram showing a third embodiment of the present invention.
THE BEST MODE FOR EMBODYING THE PRESENT INVENTION
The present inve
REFERENCES:
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patent: 4612899 (1986-09-01), Honjo et al.
patent: 4633834 (1987-01-01), Takeuchi et al.
patent: 4844034 (1989-07-01), Honjo et al.
patent: 4986239 (1991-01-01), Oishi
Dolinar Andrew M.
Mitsubishi Denki & Kabushiki Kaisha
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