Internal-combustion engines – Charge forming device – Including exhaust gas condition responsive means
Reexamination Certificate
2000-01-25
2001-12-04
Argenbright, Tony M. (Department: 3747)
Internal-combustion engines
Charge forming device
Including exhaust gas condition responsive means
C123S443000, C123S692000, C123S696000
Reexamination Certificate
active
06325056
ABSTRACT:
The invention relates to a method for the cylinder-selective control of an air/fuel mixture to be burnt in a multi-cylinder internal combustion engine, in which method the lambda values for different cylinders or groups of cylinders are sensed and controlled separately, and the invention also relates to a multi-cylinder internal combustion engine which is suitable for carrying out the operating method.
A multi-cylinder internal combustion engine in which there is a lambda probe in an exhaust duct, through which exhaust gases are jointly removed from all cylinders, is described in DE 36 20 775 A1. The lambda probe measurements are evaluated in a cylinder-selective manner, i.e. one individually associated with the cylinders of the internal combustion engine, by means of a selector unit. In this way, it is possible to draw conclusions on the composition of the air/fuel mixture burnt during the respective working stroke in each cylinder. In addition, control stages—by means of which the composition of the air/fuel mixture is controlled to a common, specified required value for each cylinder individually—are associated with the cylinders.
A method of injecting fuel is known, from DE 36 33 671 A1, in which the output signal of an exhaust gas probe arranged in an exhaust gas duct is evaluated sequentially. The value of the exhaust gas probe signal respectively occurring during a time segment is then used to control an injection quantity at that injection valve which is associated with the cylinder to whose exhaust gases the exhaust gas probe is subjected in the respective time segment. The control takes place in such a way that fuel metering, which is as uniform as possible, is provided for the individual cylinders.
DE 43 10 145 A1 reveals a multi-cylinder internal combustion engine in which a correction of the fuel injection quantity takes place during the mixture formation procedure on the basis of measurements from at least one lambda probe, which is located in a common exhaust gas duct of the cylinders. In this arrangement, provision is made to supply one group of cylinders with a weak air/fuel mixture and another group of cylinders with a rich air/fuel mixture during idling or part-load operation. The object of this is to heat a catalyser located in the exhaust gas duct rapidly to operating temperature by means of subsequent exothermal reactions taking place in it.
SUMMARY OF THE INVENTION
The object of the invention is to provide a method for the cylinder-selective control of an air/fuel mixture, of the type mentioned at the beginning, to be burnt in a multi-cylinder internal combustion engine and to create an internal combustion engine suitable for carrying out the method, which make it possible to operate the internal combustion engine with comparatively accurately controlled and adjustable exhaust gas composition in a novel, advantageous manner.
This object is achieved by means of an operating method for a multi-cylinder internal combustion engine. In the operating method the lambda values of the individual cylinders or cylinder groups are simultaneously controlled to different required values with the use of an integrating I-control proportion with variable integrator slope and/or a differentiating D-control proportion. In accordance with another aspect of the invention, a control device with a plurality of parallel controller units for the separate control of the lambda values for different cylinders or cylinder groups by means of corresponding activation of a mixture formation appliance associated with each cylinder and one or a plurality of lambda probes is provided for sensing the lambda values for the different cylinders or cylinder groups, the control units being equipped for the simultaneous adjustment of different required lambda values for the different cylinders or cylinder groups and having an I-controller component with variable integrator slope and/or a D-controller component.
In this way, the air/fuel ratio for each cylinder or each group of cylinders can be controlled individually to an arbitrary individually required lambda value and, if required, to one which alternates rapidly with time without high control amplitudes appearing. By this means, the thermal load on a catalyser arranged in the exhaust gas ducting system can be adjusted and, if appropriate, reduced in a controlled manner. The quantity of rich and weak exhaust gas emissions following one another in sequence can be adjusted in a controlled manner with low control amplitudes. If required, these exhaust gas emissions can produce exothermal reactions in the catalyser and therefore heating of it.
In a further development, of the method for cylinder-selective control of an air/fuel mixture to be burnt, in appropriately spread rich/weak operating phases, the required lambda values for a first subgroup of the cylinders are selected in the rich range and they are selected for the residual second subgroup of the cylinders in the weak range, and the distance between the two required lambda values is varied as a function of the engine operation.
In a further development, of the method, in corresponding operating phases, the required lambda value is selected, for individual cylinders or for a plurality or cylinders combined in one group, alternately in the rich range and the weak range from working cycle to working cycle. This creates a method in which the control parameters can be easily adjusted and which permits smooth running of the internal combustion engine.
In a further development, of the method, the lambda value of a particular cylinder or a particular group of cylinders is measured with a proportional lambda probe and the integrator slope of an associated lambda-value control unit with I-controller component is adjusted as a function of the control deviation of the measured lambda value from the associated required value. This further improves the flexibility of the control method with the objective of an optimum exhaust gas composition in the catalyser.
In a further development, of the method, the control of the particular lambda value includes an adjustment of the mixture composition, for a respectively next working cycle of the relevant cylinder or the relevant group of cylinders, as a function of the lambda value already measured in the previous working cycle. This creates an individual combustion control method which can react rapidly to changing operating parameters of the internal combustion engine.
A multi-cylinder internal combustion engine further developed in accordance with the principles of the invention includes a lambda probe configured as a proportional measurement probe, and the respective control unit has an I-controller component with variably adjustable integrator slope as a function of the associated lambda value control deviation. The proportionally measuring lambda probe, which has a measurement behaviour which is in principle linear even if it is not absolutely mathematically accurately linear, permits the adjustment of required lambda values deviating specifically from the stoichiometric value of unity. A variable integrator slope permits the rapid reduction of control deviations which appear. A high level of flexibility of the control device for the multi-cylinder internal combustion engine is achieved in this way, by means of which very precise individual combustion control is possible for each cylinder or each group of cylinders.
REFERENCES:
patent: 5131372 (1992-07-01), Nakaniwa
patent: 5657736 (1997-08-01), Maki et al.
patent: 5755094 (1998-05-01), Maki et al.
patent: 5911682 (1999-06-01), Kato et al.
patent: 5983874 (1999-11-01), Suzuki et al.
patent: 3620775 (1987-01-01), None
patent: 3633671 (1988-04-01), None
patent: 4310145 (1994-04-01), None
patent: 3500594 (1995-08-01), None
patent: 60-209657 (1985-10-01), None
Weining Hans-Karl
Wollenhaupt Gottfried
Argenbright Tony M.
Crowell & Moring LLP
Daimler-Chrysler AG
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