Internal-combustion engines – Charge forming device – Including means responsive to instantaneous change in engine...
Patent
1995-09-14
1997-11-18
Argenbright, Tony M.
Internal-combustion engines
Charge forming device
Including means responsive to instantaneous change in engine...
731173, F02D 4500
Patent
active
056876920
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to a combustion state determination method of an internal combustion engine and also to a combustion state control method and combustion state control system for an internal combustion engine, which are suited for use with a lean-burn internal combustion engine which performs a lean-burn operation at an air-fuel ratio on a side leaner than a stoichiometric air/fuel ratio under predetermined operation conditions.
BACKGROUND ART
Lean-burn internal combustion engines (i.e., so-called lean-burn engines) have been provided in recent years, which perform a lean-burn operation at an air/fuel ratio on a side leaner than a stoichiometric air/fuel ratio under predetermined operation conditions.
When a lean burn is performed by making leaner the air/fuel ratio of an air-fuel mixture to be fed to an engine, the production of NOx in this lean-burn range is known to generally decrease to a substantial extent by the above-mentioned leaning as illustrated in FIG. 29. From the view point of decreasing NOx, it is therefore effective to operate an engine by setting the air/fuel ratio still closer toward a lean limit.
In such lean-burn engines, the air/fuel ratio is accordingly set as high as possible (in other words, an air-fuel mixture is set as lean as possible) during a lean-burn operation so that the emission of NOx can be decreased. The value of the air/fuel ratio is generally set close to a limit (lean limit) within which the air-fuel mixture can undergo stable combustion.
By performing such a lean-burn operation, it is possible to significantly improve the gas mileage while suppressing the emission of NOx.
To perform a lean-burn operation, it is the common practice to control the state of combustion by a control system. It has been reported in articles and the like to estimate an engine torque from an angular acceleration of a crankshaft in such control.
However, these estimations are performed moment by moment by using varying momentary values. It has not been contemplated to perform stable and precise control at predetermined intervals while taking into consideration the probabilistic and statistical nature of engine torque Pi.
Further, as is depicted in FIG. 27, combustion variance in an engine varies from one cylinder to another. This variation is caused by a variation in air/fuel ratio, which in turn takes place due to a variation or variations in the shape of an injector or an intake pipe, valving timing, and/or the like.
With the foregoing in view, the state of combustion in a lean-burn operation is therefore controlled in relation to the air/fuel ratio of the cylinder that is undergoing the greatest combustion variance.
Such an approach is, however, accompanied by the problem that no operation is feasible at a limit air/fuel ratio in a cylinder or cylinders of a relatively small combustion variance.
With the foregoing problem in view, the present invention has as a first object the provision of a combustion state determination method of an engine as well as a combustion state control method and combustion state control system for an engine, which in a lean-burn operation, takes into account the probabilistic and statistical nature of combustion variance and makes it possible to perform sure combustion control, especially sure combustion control with respect to each of cylinders.
Incidentally, when lean-burn control is performed based on the level of a combustion variance, a variance equal to or greater than a predetermined level is taken as deterioration in the state of combustion so that the fuel injection quantity or the like is controlled to shift the air/fuel ratio toward a rich side.
When such a control method is performed by estimating a combustion variance from a revolution variance of an engine, there is the potential problem that because of the possibility of occurrence of a large revolution variance upon rough road running too, corrective control may be performed excessively toward the rich side.
With the foregoing problem in view, the present invention has
REFERENCES:
patent: 3789816 (1974-02-01), Taplin et al.
patent: 4112879 (1978-09-01), Assenheimer et al.
patent: 4188920 (1980-02-01), Bianchi et al.
patent: 4197767 (1980-04-01), Leung
patent: 4930479 (1990-06-01), Osawa et al.
patent: 5016591 (1991-05-01), Nanyoshi et al.
patent: 5035220 (1991-07-01), Uchinami et al.
patent: 5044195 (1991-09-01), James et al.
patent: 5109695 (1992-05-01), James et al.
patent: 5222392 (1993-06-01), Baba et al.
patent: 5237862 (1993-08-01), Mangrulkar et al.
patent: 5503007 (1996-04-01), Plee et al.
Hirako Osamu
Omori Shogo
Togai Kazuhide
Argenbright Tony M.
Mitsubishi Jidosha Kogyo Kabushiki Kaisha
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