Ignition timing controlling system for engine

Details Ignition timing controlling system for engine Ignition timing controlling system for engine

1992-04-28

1993-06-29

Argenbright, Tony M.

Internal-combustion engines

Engine speed regulator

Idle speed control

123418, 123421, F02P 515

Patent

active

052224708

DESCRIPTION:

BRIEF SUMMARY
FIELD OF THE INVENTION

This invention relates to an ignition timing controlling system for an engine (internal combustion engine) of the spark ignition type such as a gasoline engine, and more particularly to an ignition timing controlling system including means for preventing transition knocking of an engine upon acceleration.


BACKGROUND OF THE INVENTION

Ignition timing control of a gasoline engine is conventionally performed, for example, in the following manner.
In particular, operating conditions of an engine are detected from a flow rate sensor for detecting an amount of intake air of the engine and an engine rotational speed sensor for detecting a rotational speed of the engine, and basic ignition timing information is determined, based on results of such detection from the sensors, from a two-dimensional map (ignition timing map) having lead angle values (ignition timing information) which depend upon an engine rotational speed Ne and a volumetric efficiency Ev (real volumetric efficiency Evr) obtained as a value A/N by dividing an intake air amount A by the engine rotational speed Ne, and then suitable correction is performed for such basic ignition timing information. Then, ignition means (ignition plugs, an ignition coil and so forth) is operated in accordance with the thus obtained ignition timing information to control the ignition timing of the engine.
By the way, since sampling of an intake air amount A of an engine generally delays upon acceleration of the engine, if an ignition timing is looked up from an ignition timing map in accordance with a real volumetric efficiency Ev (hereinafter referred to sometimes as Evr) based on the thus sampled intake air amount A, then an ignition timing on the partial side (lower intake air amount side) with respect to an ignition timing based on a real intake air amount will be looked up, and consequently, the thus looked up ignition timing exhibits a little lead, which will cause transient knocking.
Thus, in order to prevent such transient knocking, it is a possible solution to correct a volumetric efficiency (ignition timing map looking up volumetric efficiency) Ev (hereinafter referred to sometimes as Evm) for looking up an ignition timing from an ignition timing map so that it may have a value free from a delay thereby to indirectly retard the ignition timing.
For example, taking notice of a variation (deviation) .DELTA..theta. of a throttle opening as an index to an accelerating condition, the ignition timing map looking up volumetric efficiency Evm can be corrected in accordance with such throttle opening variation (throttle opening deviation) .DELTA..theta..
Curves (a) to (c) of FIG. 7 illustrate correction of such ignition timing map looking up volumetric efficiency Evm, and the curve (a) shows a throttle opening variation .DELTA..theta. upon acceleration of the engine; the curve (b) shows an ignition timing map looking up volumetric efficiency Evm corresponding to such throttle opening variation .DELTA..theta.; and the curve (c) shows a controlling condition of the ignition timing corresponding to such ignition timing map looking up volumetric efficiency Evm.
It is to be noted that the following description will proceed by way of an example of a four-cylinder engine.
When the throttle opening variation .DELTA..theta. increases after a point of time at which acceleration is judged as seen from the curve (a) of FIG. 7, the volumetric efficiency Evr will be corrected so that it may increase by such an amount as represented by a hatched portion of the curve (b) of FIG. 7 in response to a magnitude of the throttle opening variation .DELTA..theta..
Such correction is performed in accordance with the following expression (1): K.sub.EUNE is an ignition timing acceleration correction rotational speed coefficient.
It is to be noted that the ignition timing acceleration correction rotational speed coefficient K.sub.EUNE varies in such a manner as shown in FIG. 9 in response to an engine rotational speed Ne.
However, when the throttle opening variation .D

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patent: 4658787 (1987-04-01), Takizawa
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patent: 4947816 (1990-08-01), Nakaniwa et al.
patent: 4986243 (1991-01-01), Weissler, II et al.
patent: 5070840 (1991-12-01), Kanno et al.

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