Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – With indicator or control of power plant
Reexamination Certificate
2000-03-29
2001-10-16
Wolfe, Willis R. (Department: 3747)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
With indicator or control of power plant
C701S101000, C060S285000, C060S295000
Reexamination Certificate
active
06304815
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a method for controlling an exhaust gas temperature of an internal combustion engine. In particular, the method relates to controlling the exhaust gas temperature to allow regeneration of an exhaust filter during low engine speeds or low engine load conditions.
BACKGROUND OF THE INVENTION
Emission after treatment devices are utilized to collect particulate matter from the exhaust gas of an internal combustion engine. In particular, conventional emission aftertreatment devices for diesel engines include particulate filters, oxidation catalysts, and nitrous oxide (NOx) catalysts. A problem associated with particulate filters is that the particulates, which consist largely of carbon particles, tend to plug the filters resulting in a restriction to the exhaust gas flow. A conventional method of regenerating/cleaning the filter involves increasing the exhaust gas temperature above a predetermined temperature (e.g., above 450° C.) to incinerate the carbon particles in the filter.
Conventional methods have increased the exhaust gas temperature of an engine by controlling a throttle valve in an intake manifold of the engine. In particular, it is known that by throttling/closing the throttle valve, the exhaust gas temperature may be increased. Further, numerous methodologies have been utilized for controlling the throttle valve. In one conventional method, the intake throttle valve is controlled utilizing the difference between a calculated target intake manifold pressure and an actual intake manifold pressure. The target intake manifold pressure is calculated using an engine speed and an engine load. This conventional method has a drawback of being unable to regenerate the particulate filter during low engine speeds or low engine load conditions because the required amount of throttling would result in unstable engine operation. Accordingly, when the engine is operating during low engine speeds or low engine load conditions, the particulate filter may become clogged creating an undesirable restriction in the exhaust gas flow and allowing increased exhaust gas emissions.
There is thus a need for a method of controlling an exhaust gas temperature of an engine during low engine speeds and/or low engine load conditions to initiate the regeneration of a particulate filter or the like.
SUMMARY OF THE INVENTION
The present invention provides a method of controlling an exhaust gas temperature of an engine to allow regeneration of an exhaust filter during low engine speeds and/or low engine load conditions.
A method for controlling an engine exhaust temperature in accordance with the present invention may be utilized in an engine having cylinders, an intake manifold, and a throttle valve disposed within the intake manifold. The method may include the steps of calculating a target engine operational parameter responsive to an air/fuel ratio of the engine and an engine speed error of the engine. The target operational parameter may comprise one of the following parameters: a target intake manifold pressure, a target intake manifold mass air flow, or a target air/fuel ratio. The method may further include the step of calculating a commanded position for the throttle valve responsive to the target engine operational parameter and a measured engine operational parameter. The measured engine operational parameter may comprise one of the following parameters: a measured intake manifold pressure, a measured intake manifold mass air flow, or a measured air/fuel ratio. The method may further include the step of controlling the throttle valve responsive to the commanded position to control the exhaust gas temperature. The method may further include the step of setting a commanded engine speed to a predetermined speed to further control the exhaust gas temperature. Finally, the method may include the step of injecting a predetermined amount of fuel into one of the cylinders of the engine late in a power stroke of the cylinder to further control the exhaust gas temperature.
A method for controlling the exhaust gas temperature of an engine in accordance with the present invention represents a significant improvement over conventional methods. In particular, the inventive method allows for the regeneration of particulate filters during low engine speeds conditions (e.g., an engine speed less than 1000 RPM) and/or low engine load conditions. As a result, the inventive method allows particulate filters to operate more effectively when the engine is idling or is being operated at relatively low speeds.
These and other features and advantages of this invention will become apparent to one skilled in the art from the following detailed description and the accompanying drawings illustrating features of this invention by way of example.
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Chevalier Alain Marie Roger
Christen Urs
Kuenstler Johannes
Moraal Paul Eduard
Buckert John F.
Ford Global Technologies Inc.
Lippa Allan J.
Wolfe Willis R.
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