Cylinder air charge estimation assembly

Details Cylinder air charge estimation assembly Cylinder air charge estimation assembly

2000-01-06

2001-10-30

Kwon, John (Department: 3747)

Internal-combustion engines

Engine speed regulator

Open loop condition responsive

C123S478000

Reexamination Certificate

active

06308683

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to a cylinder air charge estimation assembly and more particularly, to an assembly which dynamically estimates the amount of air resident within the cylinders of an engine by the use of several estimation methodologies and/or techniques.
BACKGROUND OF THE INVENTION
An internal combustion engine, such as that which is typically deployed within a vehicle, respectively includes several cylinders into which air and fuel are selectively mixed. The air-fuel mixture is then ignited, effective to cause a piston to move and to impart torque upon a crankshaft, thereby allowing the vehicle to be driven.
In order to reduce the amount of undesirable emissions, in order to reduce undesirable vibration or “engine knocking”, and in order to allow the engine to more efficiently utilize the fuel, it is desirable to cause the ratio of the contained air and fuel within each of the respective engine cylinders to substantially equal a certain value or to reside within a relatively narrow range of values.
This objective is typically achieved by estimating the amount of air which is contained within each of the cylinders, commonly referred to as “the air charge”, and then, based upon these respective estimates, dynamically regulating or metering the amount of fuel which is operatively communicated into the respective cylinders. Conventionally, the air charge is estimated by use of only one of four known techniques or methodologies which respectively utilize the engine speed and throttle position; the engine speed and the pressure of the intake manifold; the engine speed and a measured flow rate of air entering the intake manifold; and the position of the throttle and the pressure which is resident within the intake manifold.
Each of these previously delineated techniques has certain undesirable and varying measurement inaccuracies. The use of only one of these four previously delineated techniques therefore produces air-charge estimates having varying degrees or amounts of inaccuracy, thereby preventing the attainment of the previously delineated and desired cylinder air-fuel ratio. The third previously delineated technique is also undesirable since it requires the use of a relatively costly flow meter, thereby further increasing overall vehicle costs and undesirably increasing the complexity of the engine assembly.
There is therefore a need for a cylinder air-charge estimation assembly and technique which overcomes at least some of the previously delineated drawbacks of prior air-charge estimation assemblies and techniques and which, more particularly, allows the air-fuel ratio of each of the engine cylinders to be made substantially and respectively equal to a certain desired value or to reside within a relatively narrow range of desired values as the engine is operated.
SUMMARY OF THE INVENTION
It is a first object of the invention to provide a cylinder air charge estimation assembly and technique which overcomes at least some of the drawbacks of prior cylinder air charge estimation assemblies and techniques.
It is a second object of the invention to provide a cylinder air charge estimation assembly which overcomes at least some of the drawbacks of prior cylinder air charge estimation assemblies and which uses several air charge estimation techniques and/or methodologies, effective to provide a relatively accurate estimate of the amount of air contained within each of the cylinders of an engine.
It is a third object of the invention to provide a cylinder air charge estimation assembly which allows for the dynamic metering of fuel into each of the engine cylinders, effective to substantially reduce undesired engine emissions, to substantially reduce undesirable engine vibrations or “knock”, and to allow the fuel to be efficiently utilized by the engine.
According to a first aspect of the present invention, an assembly is provided for use with an engine of the type having at least one cylinder which operably contains a certain amount of air. The assembly includes a controller; a first sensor which is coupled to the controller and which selectively provides certain first information to the controller; a second sensor which is coupled to the controller and which selectively provides certain second information to the controller; a third sensor which is coupled to the controller and which selectively provides certain third information to the controller. The third information is selectively used by the controller in combination with the certain first information to estimate the certain amount of air by a first technique and is selectively used by the controller in combination with the certain second information to estimate the certain amount of air by a second technique. The third information has a value which is used by the controller to select only one of the first and second techniques.
According to a second aspect of the invention, a method is provided for estimating the amount of air contained within a cylinder of an engine, the engine operating at a certain speed and being of the type having a throttle which selectively occupies a certain position. The method includes the steps of measuring the speed; measuring the throttle position; providing a first and a second cylinder air estimating technique; selecting one of the first and second cylinder air estimating techniques by use of the measured engine speed and throttle position; and estimating the amount of air contained within the cylinder by use of the selected one of the first and second cylinder air estimating techniques.


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