Internal-combustion engines – Engine speed regulator – Idle speed control
Reexamination Certificate
2000-03-17
2001-08-14
Dolinar, Andrew M. (Department: 3747)
Internal-combustion engines
Engine speed regulator
Idle speed control
Reexamination Certificate
active
06273063
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an apparatus and method for controlling idle rotation speed of an internal combustion engine. In particular the invention relates to technology in an internal combustion engine equipped with a fuel vapor treatment unit, for feedback controlling engine rotation speed to a target rotation speed at the time of idle operation.
RELATED ART OF THE INVENTION
Heretofore there is known a fuel vapor treatment apparatus which is furnished with; a canister provided with active carbon for absorbing and retaining fuel vapor generated in a vehicle fuel tank, purge piping which supplies fuel purged from the canister to an engine intake passage using the negative intake pressure of the engine, and a purge control valve disposed in the purge piping, the construction being such that an amount of purge gas supplied to the engine is adjusted by controlling the purge control valve depending on the engine operating conditions (refer to Japanese Unexamined Patent Publication No. 11-182360).
Furthermore, there is known an idle rotation speed control apparatus which compares an actual engine rotation speed with a target rotation speed and feedback controls an engine intake air quantity in order to make the engine rotation speed at the time of engine idle operation coincide with the target rotation speed (refer to Japanese Unexamined Patent Publication No. 11-093736).
When purging is performed at the time of idle operating conditions and open control conditions of air-fuel ratio, the torque generated in the engine increases due to the rich shift in the air-fuel ratio. However, with a feedback control of the idle rotation speed, the engine intake air quantity is decreased in order to suppress a rise in rotation speed as a result of the increased torque.
When in such a purge condition the purging is stopped, the air-fuel ratio becomes leaner and returns to the vicinity of the original target air-fuel ratio. However, since the intake air quantity at that time has a low value in conformity with the purge condition, there has been a problem in that until this intake air quantity is increasingly changed to a value conforming to the purge stopped condition, the idle rotation speed decreases.
In particular, in engines in which the target air-fuel ratio during the idle operation condition becomes far leaner than the theoretical air-fuel ratio, there is the problem of a significant influence of the rich shift caused by purging, and an even greater change in rotation speed when purging is stopped.
SUMMARY OF THE INVENTION
The present invention has takes into consideration the abovementioned problems, with the object of providing an idle rotation speed control apparatus which can suppress the lowering of the idle rotation speed when purging is stopped.
In order to achieve the above object, the present invention is constructed such that a feedback control of the idle rotation speed in the purge stopped condition, and a feedback control of the idle rotation speed in the purge execution condition, are carried out separately.
Moreover, the construction is such that when purge is started during the feedback control of the idle rotation speed, an operating amount for immediately prior to starting purge is stored, and then when purge is stopped, an initial value of the operating amount for control in the purge stopped condition is made a final value in the stored purge stopped condition for the previous time, and the feedback control for the purge stopped condition is restarted from this initial value.
On the other hand, the construction is such that when purge is started during the feedback control of the idle rotation speed, the operating amount for immediately prior to starting purge is stored, and when the purge is stopped, the operating amount computed during purging is forcibly shifted to the beforementioned stored operating amount in the purge stopped condition.
Other objects and aspects of this invention will become apparent from the following description of the embodiment, in association with the appended drawings.
REFERENCES:
patent: 5215055 (1993-06-01), Orzel
patent: 5228421 (1993-07-01), Orzel
patent: 7-139398 (1995-05-01), None
patent: 11-93736 (1999-04-01), None
patent: 11-182360 (1999-07-01), None
Furuya Junichi
Saruwatari Masayuki
Dolinar Andrew M.
Foley & Lardner
Unisia Jecs Corporation
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