Internal-combustion engines – Poppet valve operating mechanism – Electrical system
Reexamination Certificate
2004-01-30
2004-11-09
Mohanty, Bibhu (Department: 3747)
Internal-combustion engines
Poppet valve operating mechanism
Electrical system
C123S395000
Reexamination Certificate
active
06814035
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an intake quantity control apparatus of an internal combustion engine.
2. Description of the Related Art
Known in the art is an intake quantity control apparatus of an internal combustion engine having a variable valve mechanism for controlling a valve opening characteristic of at least one of an intake valve and exhaust valve and having a throttle valve for controlling an intake pressure which is designed to control a quantity of air taken into a combustion chamber (hereinafter referred to as an “intake quantity”) by coordinated control of the valve opening characteristic and the opening degree of the throttle valve (more particularly the intake pressure).
In this type of intake quantity control apparatus, changes in characteristics of the valve spring, changes in friction due to fouling, etc. sometimes cause the time lag of the valve opening or valve closing operation with respect to a valve opening or valve closing instruction (operation time lag) to vary among the cylinders or the operation time lag to vary with each intake even in one cylinder. Due to this, sometimes the intake quantity will fluctuate along with time or the intake quantity will fluctuate among cylinders.
Japanese Unexamined Patent Publication (Kokai) No. 2000-204983 discloses as a method for suppressing variation or fluctuation in the intake quantity the method of reducing the opening degree of the throttle valve to cause the intake pressure to drop and thereby lengthen the valve opening time of the intake valve when taking in the same amount of air so as to lower the ratio of the operation time lag with respect to the total valve opening time and thereby reduce its effect.
SUMMARY OF THE INVENTION
Incidentally, in the above intake quantity control apparatus, in general a target intake quantity is determined from the operating state of the internal combustion engine, then the valve opening characteristic or intake pressure for realizing this target intake quantity is estimated. In estimation of the valve opening characteristic or intake pressure, a predetermined method is utilized to estimate the valve opening characteristic and intake pressure realizing the target intake quantity and giving the optimum combination of the fuel consumption, emission, torque fluctuation, and other conditions in accordance with the operating state of the internal combustion engine. Further, the thus estimated valve opening characteristic or intake pressure is used as a target control value to control the valve opening characteristic of the intake valve or the exhaust valve or the opening degree of the throttle valve.
However, in practice, due to the above-mentioned time lag or factors in the performance of the variable valve mechanism etc., sometimes the above valve opening characteristic or intake pressure cannot reach the target control value in a predetermined time (for example, control period) or sometimes factors in the mechanism etc. mean the valve opening characteristic or intake pressure cannot reach the target control value.
Further, the valve opening characteristic or intake pressure which ends up being adopted in such cases is sometimes not necessarily optimal in terms of the intake quantity. That is, for example, there is sometimes a valve opening characteristic or intake pressure which can realize the target intake quantity or an intake quantity closer to the target intake quantity in a range of valve opening characteristic or intake pressure realizable in the above predetermined time. That is, in such a case, there is room for controlling the intake quantity more suitably. Japanese Unexamined Patent Publication (Kokai) No. 2000-204983 does not touch upon this problem at all and therefore does not consider it at all.
An object of the present invention is to provide an intake quantity control apparatus of an internal combustion engine able to control the intake quantity more suitably by controlling the valve opening characteristic of at least one of the intake valve and exhaust valve and the intake pressure.
The present invention provides various aspects of intake quantity control apparatuses of internal combustion engines described in the claims as means for achieving this object.
According to a first aspect of the invention, there is provided an intake quantity control apparatus for an internal combustion engine having a valve opening characteristic control means for controlling a valve opening characteristic of at least one of an intake valve and an exhaust valve and an intake pressure control means for controlling an intake pressure and controlling the valve opening characteristic and the intake pressure so as to control the intake quantity, comprising a target intake quantity determining means for determining a target intake quantity for after elapse of a predetermined time, a means for determining a range of the valve opening characteristic realizable in a predetermined time by the valve opening characteristic control means, and a means for determining a range of intake pressure realizable in a predetermined time by the intake pressure control means, the valve opening characteristic and the intake pressure being controlled by the valve opening characteristic control means and the intake pressure control means so as to become a target valve opening characteristic and target intake pressure set in the realizable ranges based on the target intake quantity.
If setting the valve opening characteristic and intake pressure targeted for control, that is, the target valve opening characteristic and target intake pressure, without considering the ranges realizable in the predetermined time, if the set target valve opening characteristic and target intake pressure are not in the above realizable ranges, the intake quantity realized by the valve opening characteristic and intake pressure adopted as a result of the control will sometimes differ considerably from the target intake quantity. Further, in such a case, sometimes the above target intake quantity can be realized or an intake quantity closer to the target intake quantity can be realized if using another valve opening characteristic and intake pressure in the above realizable ranges.
According to the present invention, since the target valve opening characteristic and the target intake pressure are set in ranges realizable in a predetermined time while considering the target intake quantity and valve opening characteristic and intake pressure are controlled to the target valve opening characteristic and target intake pressure, the target valve opening characteristic and target intake pressure not being realized and the intake quantity ending up becoming an unintentional intake quantity is prevented. That is, by suitably setting the target valve opening characteristic and target intake pressure, it is possible to reliably realize control giving the optimal intake quantity in the range realizable in a predetermined time and as a result the intake quantity is more optimally controlled. Note that the “valve opening characteristic” in the present specification means one or more of the valve lift, action angle, and valve opening/closing timing.
According to a second aspect of the invention, there is provided an intake quantity control apparatus of the first aspect of the invention further comprising a means for estimating a valve opening characteristic and intake pressure for realizing the target intake quantity by a predetermined method, wherein when both the valve opening characteristic and intake pressure estimated by the means are in the realizable ranges, the estimated valve opening characteristic and intake pressure are set as the target valve opening characteristic and the target intake pressure, while when at least one of the estimated valve opening characteristic and intake pressure is not in the realizable range, a valve opening characteristic and intake pressure in the realizable ranges whereby the intake quantity becomes closest to the target intake quantity or the inta
Mohanty Bibhu
Oliff & Berridg,e PLC
Toyota Jidosha & Kabushiki Kaisha
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