Internal-combustion engines – Poppet valve operating mechanism – With means for varying timing
Reexamination Certificate
2000-08-07
2001-12-11
Denion, Thomas (Department: 3748)
Internal-combustion engines
Poppet valve operating mechanism
With means for varying timing
C073S117020, C073S118040, C123S568140, C123S568210
Reexamination Certificate
active
06328007
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to an internal cylinder intake-air quantity calculating apparatus and method for a variable valve open/closure timing controlled internal combustion engine in which open and closure timings of intake and exhaust valves are arbitrarily controlled. The present invention, more particularly, relates to the internal cylinder intake-air quantity calculating apparatus and method which accurately calculate a cylinder intake-air quantity sucked into each one of a plurality of engine cylinders (hereinafter referred to as an internal cylinder intake-air quantity) on the basis of an output of an airflow meter installed on a portion of an intake-air passage which is located at an upstream of an intake manifold.
2. Description of the Related Art
A Japanese Patent Application First Publication No. Showa 61-258942 published on Nov. 17, 1986 exemplifies a previously proposed fuel injection controlling apparatus in which a weight mean is carried out for the intake-air quantity measured by means of an airflow meter to calculate the internal cylinder intake-air quantity in a first-lag order relationship in order to cope with a stepwise change in an opening angle of an engine throttle valve in a normally available internal combustion engine in which an opening angle of the throttle valve is controlled to adjust the intake-air quantity supplied to the engine.
SUMMARY OF THE INVENTION
In addition, another fuel injection controlling apparatus has previously been proposed in which a quantity of air stream flowing into the intake manifold is calculated from an output of the airflow meter installed on the upstream portion of the intake manifold, a cylinder volume is calculated, an income-and-outgo calculation for the intake-air quantity between the air quantity flowing into the intake manifold and that flowing from the intake manifold into an inside of the cylinder is carried out to derive the intake-air quantity in the manifold portion, and the desired internal cylinder intake-air quantity is calculated on the basis of the air quantity in the manifold portion and the cylinder volume.
Consequently, a highly accurate calculation for the internal cylinder intake-air quantity can be achieved.
However, in the variable valve open/closure timing controlled internal combustion engine in which the open and/or closure timing of intake valve(s) and exhaust valve(s) are controlled, particularly, the closure timings of the intake valve(s) are controlled to adjust the internal cylinder intake-air quantity, a control over the intake valve closure timing causes a substantial change in the cylinder volume so that the internal cylinder intake-air quantity is accordingly varied in the stepwise manner. However, in the variable valve open/closure timing controlled internal combustion engine in which the open and/or closure timing of intake valve(s) are controlled, particularly, the closure timings of the intake valve(s) are controlled to adjust the intake-air quantity, a control over the intake valve closure timing(s) causes a substantial change in the cylinder volume so that the cylinder intake-air quantity is varied in the stepwise manner. Following to this variation, the intake-air quantity passing through the throttle valve may often be varied. Hence, in the latter previously proposed fuel injection controlling apparatus, the cylinder intake-air quantity is calculated on an assumption that an actual cylinder volume is not abruptly varied (constant) and cannot respond to this abrupt change. Consequently, an automotive industry has demanded a more accurate calculation of the above-described internal cylinder intake-air quantity. The same problem occurs in a case where a valve overlap displacement between the intake and exhaust valves is varied to vary a remaining gas quantity (internal EGR).
It is, therefore, an object of the present invention to provide internal cylinder intake-air quantity calculating apparatus and method for the valve open/closure timing controlled internal combustion engine which can accurately calculate the internal cylinder intake-air quantity even when the abrupt change in the cylinder volume occurs or when the abrupt change in the valve overlap displacement occurs.
According to one aspect of the present invention, there is provided an apparatus for calculating an internal cylinder intake-air quantity for a variable valve timing controlled engine, comprising: an airflow meter installed in an upstream portion of an intake manifold with respect to an intake valve whose at lease closure timing is variably controlled; and a controller programmed to calculate an air quantity flowing into the intake manifold from an output of the airflow meter; to calculate a cylinder volume of a corresponding cylinder of the engine; to calculate an income and outgo of an air quantity flowing into the intake manifold and a cylinder intake-air quantity flowing from the intake manifold into the corresponding cylinder to derive an air quantity in the intake manifold; to calculate the internal cylinder intake-air quantity on the basis of the air quantity of the intake manifold and the cylinder volume; and to correct the calculated cylinder volume on the basis of at least valve closure timing of the intake valve.
According to another aspect of the present invention, there is provided a method for calculating an internal cylinder intake-air quantity for a variable valve timing controlled engine, comprising: calculating an air quantity flowing into the intake manifold from an output of an airflow meter, the airflow meter being installed in an upstream portion of an intake manifold with respect to an intake valve whose at lease closure timing is variably controlled; calculating a cylinder volume of a corresponding cylinder of the engine; calculating an income and outgo of an air quantity flowing into the intake manifold and a cylinder intake-air quantity flowing from the intake manifold into the corresponding cylinder to derive an air quantity in the intake manifold; calculating the internal cylinder intake-air quantity on the basis of the air quantity of the intake manifold and the cylinder volume; and correcting the calculated cylinder volume on the basis of at least valve closure timing of the intake valve.
This summary of the invention does not necessarily describe all necessary features so that the invention may also be a sub-combination of these described features.
REFERENCES:
patent: 61-258942 (1986-11-01), None
Hirasawa Takahiko
Nagaishi Hatsuo
Yoshioka Yoshiaki
Corrigan Jamie
Denion Thomas
Foley & Lardner
Nissan Motor Co,. Ltd.
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