The present application claims the benefit under 35 U.S.C. § 119 of German Patent Application No. DE 10 2023 202 404.7 filed on Mar. 16, 2023, which is expressly incorporated herein by reference in its entirety.
The present invention is based on a method and a device for operating an internal combustion engine.
German Patent No. DE 195 08 013 C1 describes an air supply to an internal combustion engine in which a first air duct and a second air duct are provided. Air is supplied through the first air duct to cylinders of the internal combustion engine. Air is supplied through a second air duct to a heater for heating an exhaust system of the internal combustion engine.
A method according to the present invention for operating an internal combustion engine comprising a first air duct for supplying air to a cylinder of the internal combustion engine and a second air duct for supplying air to a heater for heating an exhaust system of the internal combustion engine may have an advantage that, by taking into account the mutual influence of the air flowing through the first or second air duct, the internal combustion engine can be controlled in an improved manner. Significantly more efficient combustions or lower pollutant loads by the combustion can thus be realized. The operation of an internal combustion engine is thus significantly improved.
Further advantages and improvements result from the measures of disclosed herein. In particular, the method according to the present invention can be used for different operating modes of the internal combustion engine. The accuracy of the regulation and the associated effort can thereby be adjusted. In particular, according to an example embodiment of the present invention, in order to precisely regulate the large amounts of air required for the operation of the cylinders, it is advantageous for the flow through the first air duct to provide different measuring functions for a second and a third operating mode. Due to the smaller amount of flowing air, the deviations in the flow through the second air duct are greater so that different measuring functions are useful in the first and second operating modes. A particularly good regulation of the internal combustion engine or the amount of air is achieved if a separate measuring function is used for each operating mode for both the first and the second air duct.
A device designed according to the present invention for operating an internal combustion engine is particularly suitable for operating the internal combustion engine since the advantages of the method according to the present invention are thus realized.
An air system adapted according to the present invention makes it possible from the outset to minimize the mutual influence by the first and second air ducts. In particular, an arrangement of the first and second air ducts as a parallel arrangement of the longitudinal extents has proven to be a measure that keeps a mutual influence low.
Exemplary embodiments of the present invention are illustrated in the figures and explained in more detail in the description below.
Starting from the air filter 31, a sensor element 11, a throttle valve 21, and then at least one cylinder 10 are arranged in the first air duct 1. Starting from the air filter 31, a sensor element 12, an air pump 14, a shut-off valve 22 and then a heater 15 are arranged in the second air duct 2. Alternatively, the sensor element 12 can also be arranged at a different location in the air duct 2 upstream of the heater 15, for example downstream of the air pump 14 or downstream of the shut-off valve 22.
A sensor element 11, which has a mass flow sensor, is provided in the air duct 1. The mass flow sensor measures the mass of air flowing through the air duct 1. Furthermore, a pressure sensor and a temperature sensor can each additionally be provided in the sensor element 11. The pressure in the air duct 1 is measured by the pressure sensor. The temperature of the air flowing through the air duct 1 is measured by the temperature sensor. The air flowing through the air duct 1 can flow to the cylinders 10 according to the actuation of the control elements, i.e., the throttle valve 21.
A sensor element 12, which has a mass flow sensor and optionally also a pressure sensor and/or a temperature sensor, is provided in the air duct 2. The mass flow sensor measures the mass of air flowing through the air duct 2. The optional pressure sensor measures the pressure and the optional temperature sensor measures the temperature in the air duct 2.
The mass which flows through the air duct 1 is controlled by the throttle valve 21. For this purpose, a valve flap 33 is actuated in such a way that it controls the air flow.
The amount of air flowing through the air duct 2 is determined by the air pump 14 and the shut-off valve 22. Only when the air pump 14 is switched on is a negative pressure generated which leads to a flow in the second air duct 2. Furthermore, the amount of air flowing through the air duct 2 can be influenced depending on the position of a valve flap 34 of the shut-off valve 22. The amount of air can be influenced by the delivery rate of the air pump 14 and the position of the valve flap 34. In a particularly simple embodiment, the valve flap 34 can only assume the completely open position or the completely closed position, and the air quantity is controlled only by the delivery rate or rotational speed of the air pump 14. In the representation in
The cylinders 10 and the heater 15 are each connected to an exhaust system 35 so that the exhaust gases of the cylinders 10 and of the heater 15 are routed through the exhaust system 35. Catalytic converters 13 and at least one lambda sensor 19 are provided in the exhaust system 35. The catalytic converters 13 may have a plurality of partial catalytic converters, for example a first and a second three-way catalytic converter, a particle filter, and a catalytic converter for NOx reduction. The precise function and arrangement of the partial catalytic converters is not important for understanding the present invention. The residual oxygen content in the exhaust gas of the cylinder 10 is determined by the lambda sensor 19. It can thus be ensured that the total quantity of fuel introduced into the cylinders 10 is in a stoichiometric ratio to the introduced air, since only in such an operating range is good cleaning of the exhaust gas ensured.
The heater 15 comprises a fuel injector 16 and an igniter 17. The fuel injector 16 is designed as a conventional fuel injection valve and allows a precisely defined quantity of fuel to be introduced into the heater 15 for a heating operation. The igniter 17 is typically designed as a spark plug or as a glow plug for igniting a fuel/air mixture. A further lambda sensor 18 can optionally also be arranged in the connecting pipe between the heater 15 and the exhaust system 35 for measuring the oxygen content in the exhaust gas of the heater 15, by means of which further lambda sensor it can be ensured that the quantity ratios of air and fuel in the heater 15 correspond to a desired setpoint value.
Typically, the heater 15 is switched on before the internal combustion engine 40 is started or during an early operating phase of the internal combustion engine. For example, the start-up of an internal combustion engine can be delayed and initially only an operation of the heater 15 take place. A heating of the exhaust system 35 is thus already achieved before an internal combustion engine is started. As a result of this measure, cleaning of the exhaust gas is already allowed in early operation of the internal combustion engine, since it is not necessary to wait until the exhaust gases of the cylinders 10 reach the operating temperature of the catalytic converters 13 for converting the exhaust gases in the exhaust system 35. A start-up of the internal combustion engine is therefore delayed for a short time (for example 1 to 10 seconds) in order to ensure a minimum temperature of the exhaust system at a start-up of the internal combustion engine. Typically, a second operating phase then takes place in which the internal combustion engine is already being operated by combustion processes in the cylinders 10 and, at the same time, heating by the heater 15 is also taking place. A further rapid heating of the exhaust system 35 up to an optimal operating temperature of the catalytic converters 13 is thereby ensured. In a third continuous operation of the combustion in the cylinders 10, it is possible for the heater 15 then not to be operated further. If operating phases occur with insufficient heat introduction into the exhaust system 35 during further operation of the internal combustion engine, the heater 15 can be activated again.
For controlling and diagnosing the device according to
It has now been found that, in this operating state, in which the cylinder (s) 10 and the heater 15 are supplied with air simultaneously, a mutual dependence or crosstalk exists between the two flows in the first and second air ducts 1, 2. This mutual dependence of the two flows would lead to a falsification of the expected air flow in the first and second air ducts 1, 2 and is therefore taken into account according to the present invention. The flow of air through the second air duct 2 is substantially constant after a possible run-up of the air pump 14. A typical value would here be an amount of air of 30 kg/h. The amount of air through the air duct 1 varies very strongly with the power generated by the cylinders 10. In an idle state of the internal combustion engine, the air requirement of the cylinders 10 is in the order of magnitude of approximately 20 kg/h, while several 100 kg/h are required during full-load operation. Furthermore, an exhaust gas backpressure in the exhaust system 35 changes depending on the air requirement of the cylinders 10. If air thus flows simultaneously through the first and second air ducts 1, 2, the mutual influence of the air flowing through the first and second air ducts must be taken into account.
As stated above, in a first operating state, air only flows through the second air duct 2 to the heater 15 in order to heat the exhaust system 35 before a start-up of the internal combustion engine in order to ensure at least a partial function of the catalytic converters. In this first operating state, only the air flow through the second air duct 2 therefore must be taken into account, which typically takes place by a simple measuring function which represents the relationship between the measured signal of the sensor element 12 and the air requirement of the heater 15. This measuring function can, for example, take place by a characteristic map, i.e., a table, in which an air flow to the heater 15 is assigned to a corresponding measurement signal of the mass flow sensor in the sensor element 12.
In a third operating state, air only flows through the first air duct to the cylinder (s) 10, which corresponds to normal operation of the internal combustion engine without additional operation of the heater 15. In this third operating state, a measuring function which represents the relationship between an air requirement of the cylinders 10 and the measurement signal of the mass flow sensor in the sensor element 11 can also be easily ascertained. This measuring function can also take place using a simple characteristic map.
In the second operating state, when the cylinders 10 and the heater 15 are simultaneously supplied with air, the measuring function must be taken into account a mutual influence of the air flow through the first and second air ducts 1, 2. In this case, the geometric arrangement of the first and second air ducts 1, 2 relative to the air filter 31 must also be taken into account.
In
It has been found that the dependencies of the influence of the flow of the first and second air ducts 1, 2 depend on the relevant geometry. In an arrangement according to
Different measuring functions can be used depending on the operating state of the internal combustion engine. The efforts respectively involved in the compensation of the deviations of the flow through the first and second air ducts 1, 2 are different.
In
In a particularly complex variant of
A certain simplification is achieved in
Another simplification of
The selection of the adaptation of the measuring functions to the respective operating states is primarily a question of the effort and the technical advantages achieved therewith or the acceptance of technical disadvantages.
Number | Date | Country | Kind |
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102023202404.7 | Mar 2023 | DE | national |