Internal-combustion engines – Charge forming device – Including cylinder pressure or temperature responsive means
Reexamination Certificate
2001-12-20
2003-11-25
Argenbright, Tony M. (Department: 3747)
Internal-combustion engines
Charge forming device
Including cylinder pressure or temperature responsive means
C123S090110, C123S436000, C123S345000, C123S347000
Reexamination Certificate
active
06651624
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method and a device for modifying the torque of an internal combustion engine having at least one first cylinder with an exhaust valve having a variable valve control.
BACKGROUND INFORMATION
Internal combustion engines, in particular for motor vehicles, may operate with one or more camshafts to control the engine valves according to a predetermined stroke sequence, and the stroke sequence may be specified by the mechanical structure of the camshaft. However, a specified stroke sequence may not permit optimal engine performance because different engine operating states in general require different stroke sequences.
In this regard, internal combustion engines having a hydraulic or electromagnetic camless valve drive instead of a rigid mechanical arrangement may constitute an advance in the design of valve controls. In a camless internal combustion engine, the amount of intake air and residual exhaust gas in each cylinder may be controlled by modifying the time of opening and/or closing of the intake and exhaust valves.
For these conventional internal combustion engines, the following control actions may be known for influencing, in a controlled manner, the torque delivered by the internal combustion engine.
First, with spark ignition engines in particular, a filling intervention may be carried out, modifying the gas filling of the cylinder via an electrically controllable throttle valve or a bypass controller. This filling intervention may be designed to be approximately neutral with regard to consumption or exhaust emissions, but the filling intervention may produce only a gradual change in torque and may not permit any change in the torque contribution of the cylinder during an operating cycle after closing the intake valves of the cylinder. Because of the gradual change, it may not be possible to have high quality idling, i.e., constant idling through the filling intervention alone.
The second method is a filling intervention via the intake valves of the corresponding cylinders with variable intake valve control. As in the case of the filling intervention via the electric throttle valve or the bypass controller, this control action may permit a setting which is approximately neutral with regard to consumption and emissions. However, the filling intervention involving the intake valves is also slow and may not allow any change in torque contribution during a working cycle after closing the intake valve of the respective cylinder.
A third method is a firing angle intervention. Firing angle intervention essentially makes it possible to influence the torque contribution of the respective cylinder and thus the torque of the internal combustion engine after the intake valve of the respective cylinder is closed, by making an adjustment, usually by delaying the firing angle. However, modifying the firing angle may have a negative effect on combustion in the cylinder, leading to increased fuel consumption and possibly also greater exhaust emissions. Furthermore, with this firing angle intervention, the adjustment options may be very minor, depending on the combustion method and the operating point of the internal combustion engine because reliable and stable ignition and combustion are necessary for reasons of fuel consumption, exhaust emissions and smooth running. Furthermore, although the firing angle intervention may be comparatively rapid, it may not allow any change in torque contribution during a working cycle after the beginning of combustion in the respective cylinder.
Finally, there may be injection measures through which the quantity of fuel supplied may be varied. This may provide a relatively quick modification in torque of the internal combustion engine, but the change cannot be implemented during ongoing combustion within a working cycle.
The individual combustion processes in the individual cylinders of the internal combustion engine may be subject to cyclic fluctuations in combustion. These cyclic combustion fluctuations may result from stochastic fluctuations in the local composition and kinematics of the individual fuel-air mixtures in the area of the spark plug at the time of ignition and their influences on the formation of the flame core and the duration of the ignition phase. This may result in different contributions of the individual cylinders to the torque of the internal combustion engine. These differences in individual torque contributions may result in out-of-true running of the internal combustion engine and in particular to poor idling quality. Moreover, the differences cause unnecessary fuel consumption and increased exhaust emissions.
Since all the control actions described above are carried out before the start of combustion in the respective cylinder, they may not be suitable for control, in particular for equalization of the individual torque contributions of the individual cylinders. The interventions referred to above may not suitable for compensating for cyclic fluctuations in combustion because they may not respond to changes or influences occurring during combustion within a working cycle, but instead they produce changes in the following working cycle of the following cylinder at the soonest.
SUMMARY OF THE INVENTION
An object of an exemplary embodiment and/or exemplary method of the present invention is to provide a method and a device for rapidly changing the torque of an internal combustion engine having at least one cylinder with an exhaust valve having a variable valve control.
In an exemplary method for modifying the torque of an internal combustion engine having at least one first cylinder with an exhaust valve having a variable valve control according to the present invention, a determination is made as to whether there may be a demand for modifying the torque within a first working cycle of the first cylinder, and if it is determined that it may be necessary to modify the torque during the first working cycle, a basic triggering of the exhaust valve of the first cylinder may be modified in the first working cycle.
A demand determining device for determining whether there may be a demand for modifying the torque within the first working cycle of the first cylinder is provided in a device according to an exemplary embodiment of the present invention, and there is a triggering modifying device that modifies the basic triggering of the exhaust valve of the first cylinder in the first working cycle when the demand determining device determines that the torque should be modified.
An exemplary embodiment and/or exemplary method of the present invention provides a method and/or a device by which the torque contribution of the corresponding cylinder and thus the torque of the internal combustion engine may be modified very quickly, even within the same working cycle of the respective cylinder. In this way it may be possible to achieve high idling quality. Moreover, the exemplary method and exemplary device may minimize or at least reduce any difference between individual torque contributions of individual cylinders, and thus achieve a high quality average pressure equalization of the individual cylinders among one another and a very good constancy of the average torque contribution of successive working cycles in steady-state operation.
Furthermore, the exemplary method and/or the exemplary device according to the present invention may permit a change in torque of an internal combustion engine when it may no longer be possible to perform a filling intervention via the throttle valve or a filling intervention using the intake valves, a firing angle measure or injection measure, in particular when combustion is already underway. On the whole, this may provide engine operation that is improved in both steady-state and non-steady-state operation with regard to target parameters, such as fuel consumption, exhaust emissions and smooth running in particular.
An exemplary embodiment and/or exemplary method of the present invention may permit the basic triggering of the exhaust valves to be mod
Beuche Volker
Diehl Udo
Gaessler Hermann
Grosse Christian
Mallebrein Georg
Argenbright Tony M.
Huynh Hari H.
Kenyon & Kenyon
Robert & Bosch GmbH
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