Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – With indicator or control of power plant
Reexamination Certificate
1999-10-18
2001-04-17
Yuen, Henry C. (Department: 3747)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
With indicator or control of power plant
C701S102000, C123S436000, C123S399000
Reexamination Certificate
active
06219611
ABSTRACT:
FIELD OF THE INVENTION
The field of the invention relates to engine control, wherein the engine has multiple control devices.
BACKGROUND OF THE INVENTION
In some engines, an electronically controlled throttle is used for improved performance. In particular, the electronic throttle is used to control airflow to a desired value determined from operating conditions and an operator command. In this way, the vehicle can achieve improved drive feel and improved fuel economy.
In this system, the required airflow is used to determine an initial setting of the throttle. Also, a difference between required airflow and actual measured airflow is used to adjust the initial setting of the throttle. Thus, the throttle is used to control airflow and thereby engine torque. Such a system is described in U.S. Pat. No. 5,019,989.
It is also known to have a variable camshaft timing mechanism to adjust engine breathing and residual burnt gas fraction. In this system, camshaft timing is generally determined as a function engine speed and engine load. Position the camshaft as a function of speed and load is used to optimize steady state performance giving minimized emissions and fuel consumption. Such a system is disclosed in U.S. Pat. No. 4,856,465.
The inventors herein have recognized a disadvantage with the above approaches. In particular, a disadvantage with using throttle position is that the throttle cannot quickly change engine torque since the throttle controls flow entering an intake manifold.
Controlling flow entering the manifold cannot rapidly control cylinder charge due to manifold volume. For example, if the throttle is instantly closed, cylinder air charge does not instantly decrease to zero. The engine must pump down the air stored in the manifold, which takes a certain number of revolutions. Therefore, the cylinder air charge gradually decreases toward zero.
Also, the inventors herein have recognized that prior art approaches for controlling variable camshaft timing systems sacrifice dynamic performance. In other words, since the variable cam timing is scheduled versus engine speed and load to provide optimum steady state performance, transient operation is sub-optimal and many opportunities go overlooked. Further, these methods for providing variable cam timing steady state setpoint control are done without regard to manifold dynamics and cause degraded performance.
SUMMARY OF THE INVENTION
An object of the present invention is to provide an engine control method for an engine having both an inlet control device and an outlet control device to provide optimum steady state performance as well as good dynamic response.
The above object is achieved and disadvantages of prior approaches overcome by a method for controlling an engine having at least one cylinder, the engine also having an intake manifold, an outlet control device for controlling flow from the intake manifold into the cylinder, and an inlet control device for controlling flow into the intake manifold, comprising: determining a desired outlet control device setpoint; and adjusting said inlet control device and said outlet control device based on said desired outlet control device setpoint without changing amount of flow into the cylinder.
By adjusting the inlet and outlet control device in opposite directions, it is possible to provide the desired steady state optimized performance, without suffering from degraded performance. In addition, disadvantages of the prior approaches are overcome when transitioning to the steady state conditions since the air amount is provided even when the outlet control device is being adjusted.
An advantage of the above aspect of the present invention is improved drive feel since changes in engine airflow are avoided even when adjusting the outlet control device to a desired value.
In another aspect of the present invention, the above object is achieved and disadvantages of prior approaches overcome by a method for controlling an engine having at least one cylinder, the engine also having an intake manifold, an outlet control device for controlling flow from the intake manifold into the cylinder, and an inlet control device for controlling flow into the intake manifold, comprising: determining a desired air amount entering the cylinder; determining a desired outlet control device setpoint; adjusting said inlet control device and said outlet control device in response to a respective inlet control device command and an outlet control device command; adjusting said inlet control device command and said outlet control device command to provide said desired air amount; and adjusting said inlet control device command and said outlet control device command to provide said desired outlet control device setpoint.
By using both the outlet control device to rapidly adjust flow into the cylinder faster than possible by using the inlet control device alone, it is possible achieve rapid airflow control. In other words, dynamic control response is greatly improved. Further, steady state optimization is still provided by gradually adjusting both the inlet and outlet control devices to provide the desired air amount as well as the steady state outlet control device setpoint.
An advantage of the above aspect of the invention is improved dynamic control while optimizing steady state performance.
Another advantage of the above aspect of the invention is improved airflow control.
Other objects, features and advantages of the present invention will be readily appreciated by the reader of this specification.
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Ford Global Technologies Inc.
Russell John D.
Vo Hieu T.
Yuen Henry C.
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