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AssigneeSiemens Aktiengesellschaft
InventorsWolfgang Ludwig, Corinna Pfleger, Hong Zhang
Estimating the term…
Values for a raw NOx concentration of an internal combustion engine, that are stored on an operating point basis, are read out from a characteristic map and an adaptation of variations in concentration takes place on the basis of an output signal of an NOx sensor provided downstream of a NOx storage catalyst, either by modification of a reduction factor, which serves for the calculation of a corrected raw NOx concentration from the raw NOx concentration, or by direct correction of the values read out from the characteristic map for the raw NOx concentration with a raw concentration correction factor.
A method for adapting a raw NOx concentration value of an internal combustion engine operating at least in given operating ranges with an excess of air, the method which comprises:
Dependencies are inferred from the claim text.
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From the US filing history. Foreign family members aren’t listed.
Characterised by the absorbed or adsorbed substances: nitrogen oxides
To purge or regenerate the exhaust gas treating apparatus: the exhaust gas treating apparatus being a NOx trap or adsorbent
Characterised by the control or regulation method: adaptive control
Of the exhaust gases emitted by the engine: with determination means using an estimation
Term ended 3 Nov 2019 (estimated)
The invention relates to a method for adapting a raw NOx concentration value of an internal combustion engine operating with an excess of air.
To further reduce the fuel consumption of motor vehicles with spark-ignition engines, internal combustion engines which are operated with a lean mixture, at least in selected operating ranges, are increasingly being used.
To meet the exhaust emission limit values required, a special exhaust treatment is necessary in the case of such internal combustion engines. NOx storage reduction catalysts, referred to hereafter as NOx storage catalysts for the sake of simplicity, are used for this purpose. On account of their coating, these NOx storage catalysts are capable during a storing phase, also referred to as a loading phase, of adsorbing from the exhaust gas NOx compounds which are produced in lean combustion. During a regeneration phase, the adsorbed or stored NOx compounds are converted into harmless compounds by adding a reducing agent. CO, H2 and HC (hydrocarbons) may be used as the reducing agent for lean-operated spark-ignition internal combustion engines. These are generated by briefly operating the internal combustion engine with a rich mixture and are made available to the NOx storage catalyst as components of the exhaust gas, whereby the stored NOx compounds in the catalyst are broken down.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.
FIG. 1 is a schematic diagram of a lean-mix internal combustion engine with an NOx storage catalyst according to the invention;
FIG. 2 is a graph illustrating the amount of NOx and the NOx concentration during a lean phase of the internal combustion engine;
For the sake of simplicity, the expression NOx concentration is used here for the expression raw NOx concentration value.
Referring now to the figures of the drawings in detail and first, particularly, to FIG. 1 thereof, there is shown, in the form of a block diagram, a lean-mix internal combustion engine with an NOx exhaust treatment system for which the method according to the invention is used.
Only the components which are necessary for understanding the invention are represented here.