DE102009055241B4 - Method for operating an internal combustion engine and corresponding device - Google Patents

Abstract

Method for operating an internal combustion engine (1), in particular a two-wheeled vehicle, in which an unheated lambda jump sensor (5) assigned to the internal combustion engine (1) is used to determine whether a certain proportion of a gas component in the exhaust gas of the internal combustion engine (1) falls below or exceeds a certain level temperature sensor (6) assigned to the internal combustion engine (1) for determining the temperature of the exhaust gas and a control unit (7) of the internal combustion engine for determining at least one operating parameter of the internal combustion engine (1) are used, and both the temperature of the exhaust gas and a falling below or The signal from the lambda jump probe (5) indicating that the specific proportion is exceeded can be fed directly to the control unit (7), and the control unit (7) calculates the at least one operating parameter of the internal combustion engine (1) at least from the value of the temperature of the exhaust gas and additionally with the signal from the lambda jump probe ( 5), a state dssize of the internal combustion engine (1) and / or another operating parameter of the internal combustion engine (1).

Description

The invention relates to a method for operating an internal combustion engine, in particular a two-wheeled vehicle. The invention also relates to a device for operating an internal combustion engine, a computer program and a computer program product.

State of the art

Methods of the type mentioned are known from the prior art. For example, a heated or unheated lambda probe and the temperature sensor can be assigned to the internal combustion engine. The heated oxygen sensor can be a broadband oxygen sensor or a jump oxygen sensor. If the method for operating the internal combustion engine is to be able to be implemented cost-effectively, the unheated lambda jump probe is often used. This is particularly the case with internal combustion engines for two-wheeled vehicles. If the unheated lambda probe is used to control and/or regulate the internal combustion engine, this is only possible in certain operating ranges of the internal combustion engine with the aid of simplifying or model-like assumptions.

It is also known to evaluate the signal from the lambda probe on the basis of the temperature determined using the temperature sensor. If the temperature is too low, it is assumed that the lambda probe is not yet ready for operation and the signal it supplies is discarded, ie it is not used to control and/or regulate the internal combustion engine. On the other hand, if the temperature is above a certain minimum temperature, which can correspond to the operating temperature of the lambda probe, the signal is used. The validity of the lambda probe signal or the operational readiness of the lambda probe is therefore inferred from the temperature. Such an evaluation is usually carried out in the lambda probe itself. The temperature sensor is assigned to this. The signal from the lambda probe is therefore only output by the lambda probe, for example to a control unit, when the temperature is greater than or equal to the minimum temperature.

Such methods are also from the U.S. 6,651,623 B1 and the U.S. 6,295,808 B1 known.

Disclosure of Invention

In contrast, the method with the features mentioned in claim 1 has the advantage that the internal combustion engine can have a cost-effective, unheated lambda jump probe and a reliable and precise setting of operating parameters of the internal combustion engine is nevertheless possible. According to the invention, this is achieved in that the unheated lambda jump sensor assigned to the internal combustion engine for determining whether a specific proportion of a gas component in the exhaust gas of the internal combustion engine is exceeded or not reached, a temperature sensor also assigned to the internal combustion engine for determining the temperature of the exhaust gas and a control unit of the internal combustion engine for determining at least one Operating parameters of the internal combustion engine are used. Both the temperature of the exhaust gas and a signal from the lambda jump probe indicating whether the specified percentage has been exceeded or fallen below are fed directly to the control unit. It is also provided that the control unit determines the at least one operating parameter of the internal combustion engine at least from the value of the temperature of the exhaust gas. Provision is therefore made for the operating parameter of the internal combustion engine to be determined or calculated directly from the value of the temperature. To do this, the temperature and the signal from the lambda jump probe are sent to the control unit. It is therefore not intended to determine whether or not the signal from the lambda jump probe is evaluated or not, or whether the signal from the lambda jump probe is fed to the control unit solely on the basis of the temperature.

This has the advantage that the operating parameters of the internal combustion engine can be set very precisely with the unheated lambda jump probe. This also applies in particular to operating states of the internal combustion engine in which the signal from the lambda jump sensor cannot provide a direct indication of the proportion of gas components in the exhaust gas of the internal combustion engine, for example because the temperature of the exhaust gas or the lambda jump sensor is too low. The use of a heated lambda probe, either a broadband lambda probe or a lambda jump probe, means that the signal from the lambda probe can be reliably evaluated, but the temperature of the exhaust gas cannot be reliably determined by means of the lambda probe in this case due to the heating of the lambda probe . The provision of a dedicated temperature sensor is not intended when using the heated lambda probe, since in this case the internal combustion engine can be controlled and/or regulated solely on the basis of the signal from the lambda probe.

If, on the other hand, the inexpensive, unheated lambda jump probe is to be used, it is advantageous to provide the temperature sensor for determining the temperature of the exhaust gas. Based of the value of the temperature of the exhaust gas, reliable control and/or regulation of the internal combustion engine can be carried out, in particular also in operating ranges of the internal combustion engine in which the signal from the lambda jump probe cannot be evaluated or is reliable. As already explained above, the temperature should not only be used to determine whether the signal from the lambda jump probe can be evaluated or is reliable in order to carry out the open-loop or closed-loop control of the internal combustion engine on the basis of the signal. Rather, the value of the temperature should be used to determine the operating parameters of the internal combustion engine, in particular directly. This preferably means that the value of the operating parameter is determined or calculated from the value of the temperature. In this way, the accuracy of the control or the regulation of the internal combustion engine and in particular the determination of the operating parameters of the internal combustion engine can be carried out much more reliably even when using the unheated lambda jump probe than with methods known from the prior art. This is possible in a particularly reliable manner if, in addition to the value of the temperature of the exhaust gas, other variables, such as the signal from the lambda jump probe, are used. The lambda jump probe and the temperature sensor can be designed, for example, as an integrated sensor arrangement.

The invention also provides that the operating parameter is additionally determined using the signal from the lambda jump probe, a state variable of the internal combustion engine, in particular load torque, and/or another operating parameter of the internal combustion engine, in particular speed, torque, fuel injection quantity and/or ignition point. In addition to the value of the temperature of the exhaust gas, at least one other variable is also used. This can include, for example, the signal from the lambda jump probe, with the signal signaling that the specific proportion of the gas component in the exhaust gas of the internal combustion engine has been exceeded or fallen below. The operating parameter is determined in the control unit of the internal combustion engine. For this reason, in principle any other variables that are advantageously already present in the control unit can be used in the determination. Such a variable is, for example, the load torque, ie the torque which is applied to the internal combustion engine, corresponding to the state variable. The other operating parameter can also be used. The other operating parameters are, for example, the rotational speed, the torque, the fuel injection quantity or the ignition point of the internal combustion engine. The operating parameter and the further operating parameter are set for operating the internal combustion engine on the latter. The at least one state variable of the internal combustion engine is then adjusted. The temperature of the exhaust gas or another temperature can also be understood as a state variable of the internal combustion engine. As already explained above, it is particularly advantageous if at least the value of the temperature and the signal of the lambda jump probe are used to control and/or regulate the internal combustion engine, ie to determine the operating parameter or the value of the operating parameter.

A development of the invention provides that the operating parameter is determined to heat up a catalytic converter of the internal combustion engine if the temperature is below a catalytic converter operating temperature, or to reduce the temperature if the temperature is above a specific maximum temperature. In this way, the heating of the catalytic converter can be optimized to its catalytic converter operating temperature. This leads to fuel savings. The duration of a heating-up phase of the catalytic converter is usually accelerated by the selection of certain operating parameters of the internal combustion engine. These operating parameters include, for example, the ignition timing and/or the fuel injection quantity. It is known from the prior art to estimate the instantaneous temperature using a temperature model and to switch to normal operation of the internal combustion engine as soon as the temperature reaches or exceeds the operating temperature of the catalytic converter. However, such temperature models are very imprecise, so that a sufficiently large tolerance band must be taken into account in order to switch to normal operation only when the catalytic converter has actually already reached the catalytic converter operating temperature. The heating of the catalytic converter can be optimized by determining the temperature of the exhaust gas of the internal combustion engine and determining the operating parameter of the internal combustion engine from the value of the temperature. Ideally, the internal combustion engine can be switched to normal operation after a shorter time than is known from the prior art, since measuring the temperature using the temperature sensor is significantly more accurate than determining the temperature from the temperature model.

Fuel consumption can be reduced by shortening the heating-up phase of the catalytic converter because the operating parameters of the internal combustion engine used to heat up the catalytic converter result in higher consumption. Furthermore, by determining the operating parameter from the value of the temperature, the temperature can be regulated while the catalytic converter is heating up, so that the heating-up process can be adapted to ambient conditions of the internal combustion engine, such as intake temperature, ambient temperature and/or altitude. Optimization or of emissions from the internal combustion engine can also be achieved in this way. For example, by using the temperature sensor to determine the temperature of the exhaust gas, an intake temperature sensor can be omitted. In this case, the intake temperature is determined by determining the temperature of the exhaust gas before the internal combustion engine is started. Before the internal combustion engine is started and after a sufficiently long shutdown time, it can be assumed that the temperature determined by the temperature sensor corresponds to the intake temperature or the ambient temperature. In this way, the cost of the internal combustion engine can be reduced.

Alternatively or additionally, the operating parameter of the internal combustion engine can also be determined in such a way that the temperature is reduced. This is particularly the case when the temperature is above the specified maximum temperature. In this way, protection for components of the internal combustion engine is achieved. For example, in order to avoid damage to the catalytic converter due to overheating (e.g. at temperatures > 980°C), a selected lambda value, in particular lambda=1, is deviated from in critical operating ranges of the internal combustion engine and, for example, cooling is carried out by introducing a larger quantity of fuel (enrichment). of the exhaust gas. It is known from the prior art to use temperature models for this as well. However, these have error tolerances of at least ± 50°C. The operating parameter must therefore be selected taking this error tolerance into account in order to reliably set the desired temperature of the exhaust gas. This leads to higher fuel consumption. If the operating parameter is determined from the value of the temperature of the exhaust gas, then there is less error tolerance, so that less fuel has to be introduced in order to reliably set the desired exhaust gas temperature.

A development of the invention provides that the operating parameter is initially determined on the basis of the signal from the lambda jump sensor and then corrected with the temperature of the exhaust gas. This is done, for example, by first selecting the operating parameter in such a way that a specific lambda value, in particular the jump value of the lambda step sensor, is set. The operating parameter is then corrected using the temperature of the exhaust gas, so that a specific temperature of the exhaust gas is set. In this way, errors in the signal of the lambda jump probe or in the determination of whether the specific proportion of the gas component has fallen below or exceeded can be corrected, since the setpoint temperature is usually known when a specific lambda value is present. In simplified terms, when the internal combustion engine is operated at a specific lambda value, in particular lambda=1, the highest temperature of the exhaust gas is present. Through the use of two parameters that are recorded independently of one another, namely by means of the lambda jump sensor and the temperature sensor, there is a redundancy with which inaccuracies or temporary failures of the lambda jump sensor can be compensated for. According to the invention, a subsequent correction of the lambda control, ie the operating parameter, takes place on the basis of the value of the temperature of the exhaust gas. In this way, for example, a control position that is too lean can be corrected.

A development of the invention provides that a correction value is determined at least from the temperature of the exhaust gas in order to correct the operating parameter. First, the correction value is determined from the value of the temperature of the exhaust gas. The operating parameter is then corrected with the correction value, for example by calculating a new value of the operating parameter from the original value and the correction value.

A further development of the invention provides that the correction value is additionally determined using the state variable and/or the additional operating parameter of the internal combustion engine. Therefore, not only the value of the temperature of the exhaust gas should be used, but other variables should be used in order to increase the accuracy of the control and/or regulation of the internal combustion engine on the basis of the operating parameter. These additional variables are, for example, the state variable or the additional operating parameter.

A development of the invention provides that the correction value is determined independently of the determination of the operating parameter. The correction value is therefore preferably permanently adjusted. In particular, even if the operating parameter is not determined. The determination of the correction value and the determination of the operating parameter can therefore be carried out in parallel. This can also be provided at time intervals that differ from one another.

Additionally or alternatively, the value of the temperature can be used to indicate the operational readiness of the lambda jump probe. It can also be used as a diagnostic criterion for determining the lambda value. It is known from the prior art to detect the operational readiness of heated or unheated lambda jump sensors, for example via the amplitude of the sensor voltage. This depends, for example, on an internal resistance of the sensor ceramic. If the value of the temperature is now also used, such information can be checked for plausibility, so that more reliable information about the operational readiness of the lambda jump probe is available.

The device according to the invention for carrying out the method relates firstly to a specially designed control unit which contains means for carrying out the method described above.

The control device is provided in particular to determine an operating parameter of the internal combustion engine. Both the temperature of the exhaust gas and a signal from a lambda jump sensor indicating that a specific proportion of a gas component in the exhaust gas of the internal combustion engine has been exceeded or not reached should be fed directly to the control unit, and the control unit should determine the at least one operating parameter of the internal combustion engine at least from the value of the temperature of the exhaust gas .

The computer program according to the invention provides that all steps of the method according to the invention, explained above, are carried out when it runs on a computer.

The computer program product according to the invention with a program code stored on a machine-readable carrier executes the method according to the invention when the program runs on a computer.

• Figur eine schematische Darstellung einer Brennkraftmaschine, wobei in einem Abgastrakt der Brennkraftmaschine eine unbeheizte Lambdasprungsonde sowie ein Temperatursensor vorgesehen sind.

The invention is explained in more detail below with reference to the exemplary embodiments illustrated in the drawing, without restricting the invention. It shows the only one

• FIG. 1 shows a schematic representation of an internal combustion engine, with an unheated lambda jump probe and a temperature sensor being provided in an exhaust tract of the internal combustion engine.

The figure shows an internal combustion engine 1 with an exhaust tract 2 , which consists essentially of an exhaust manifold 3 and an exhaust manifold 4 . At least one exhaust gas purification device, for example a catalytic converter or the like, can be provided in the exhaust manifold 4 . An unheated lambda jump probe 5 and a temperature sensor 6 are provided in the exhaust manifold 4 and are directly connected to a control unit 7 of the internal combustion engine 1 . Lambda jump probe 5 can be used to determine whether the gas component in the exhaust gas of internal combustion engine 1 that flows through exhaust tract 2 falls below or exceeds a specific proportion. The temperature sensor 6 is used to determine the temperature of the exhaust gas. The lambda jump probe 5 supplies a signal which indicates that the specific proportion has not been reached or exceeded. This signal is fed directly to control unit 7 . The temperature sensor 6 is also connected to the control unit 7, so the temperature of the exhaust gas is also available to the control unit 7 as an input variable.

It is now provided that the control unit 7 determines at least one operating parameter of the internal combustion engine 1 from the value of the temperature of the exhaust gas. This operating parameter is a fuel injection quantity, for example, which is set on a fuel injection system 8 . The fuel injection quantity determined by control unit 7 can be introduced into cylinder 9 of internal combustion engine 1 by means of fuel injection system 8 . In addition to the value of the temperature, the signal of the lambda jump probe 5 is advantageously included in the determination of the operating parameter of the internal combustion engine 1 . Instead of using the combination of temperature and signal from lambda jump probe 5, however, other variables can also be used instead of the signal. Other state variables and/or operating parameters of internal combustion engine 1 can also be taken into account. A state variable of the internal combustion engine 1 is, for example, the load torque which is applied to the internal combustion engine 1 . The other operating parameters include, for example, the speed, the torque, the fuel injection quantity and/or the ignition point. The operating parameter of internal combustion engine 1 is, for example, the fuel injection quantity or the ignition point. The internal combustion engine 1 is controlled or regulated on the basis of the operating parameter or the additional operating parameter.

For example, it is provided that the operating parameter is initially determined on the basis of the signal from the lambda jump probe 5 and is then corrected with the value of the temperature of the exhaust gas. For this purpose, a correction value is determined from the temperature of the exhaust gas and possibly the state variable and/or the additional operating parameter is subsequently used to correct the operating parameter. Also, based on the selection of the operating parameter of internal combustion engine 1 based on the value of the temperature of the exhaust gas, heating of the catalytic converter can be optimized and components of internal combustion engine 1 can be better protected.

Claims (10)

Method for operating an internal combustion engine (1), in particular a two-wheeled vehicle, in which an unheated lambda jump sensor (5) assigned to the internal combustion engine (1) is used to determine whether a certain proportion of a gas component in the exhaust gas of the internal combustion engine (1) falls below or exceeds a certain level temperature sensor (6) assigned to the internal combustion engine (1) for determining the temperature of the exhaust gas and a control unit (7) of the internal combustion engine for determining at least one operating parameter of the internal combustion engine (1) are used, and both the temperature of the exhaust gas and a falling below or The signal from the lambda jump probe (5) indicating that the specific proportion is exceeded can be fed directly to the control unit (7), and the control unit (7) calculates the at least one operating parameter of the internal combustion engine (1) at least from the value of the temperature of the exhaust gas and additionally with the signal from the lambda jump probe ( 5), a state dssize of the internal combustion engine (1) and / or another operating parameter of the internal combustion engine (1). procedure after claim 1 , characterized in that the state variable of the internal combustion engine (1) is a load torque, and / or the other operating parameter of the internal combustion engine (1) is a speed, a torque, a fuel injection quantity and / or an ignition point. Method according to one of the preceding claims, characterized in that the operating parameter is determined to heat up a catalytic converter of the internal combustion engine (1) if the temperature is below a catalytic converter operating temperature, or to reduce the temperature if the temperature is above a specific maximum temperature. Method according to one of the preceding claims, characterized in that the operating parameter is initially determined on the basis of the signal from the lambda jump probe (5) and is then corrected with the temperature of the exhaust gas. Method according to one of the preceding claims, characterized in that a correction value is determined at least from the temperature of the exhaust gas in order to correct the operating parameter. procedure after claim 5 , characterized in that the correction value is additionally determined with the state variable and/or the further operating parameter of the internal combustion engine (1). procedure after claim 5 or 6 , characterized in that the correction value is determined independently of the determination of the operating parameter. Device for operating an internal combustion engine, characterized in that a specially designed control unit (7) is provided, the means for carrying out the method according to one of Claims 1 until 7 contains. Computer program that performs all the steps of the method according to any of Claims 1 until 7 executes when the program is running on a computer. Computer program product with a program code stored on a machine-readable carrier for carrying out the method according to one of Claims 1 until 7 , if the program is running on a computer.

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