Method and device for controlling the temperature of a component in an exhaust tract of an internal combustion engine by means of a predictor

Abstract

The invention relates to a method and a device for regulating the temperature of a component (170) in an exhaust duct (110) of an internal combustion engine (100), wherein the exhaust duct (110) has a temperature sensor (180) which is arranged in the exhaust duct (110) upstream of the component (170), wherein the method comprises the following steps: - providing a control circuit for regulating the temperature of the component (170); - detecting a measurement signal (310) using the temperature sensor (180) during operation of the internal combustion engine (100), wherein the measurement signal (310) 10) characterizing an exhaust gas temperature (312) of the exhaust gas (160) upstream of the component (170), wherein the measurement signal (310) is used as a measured control variable (330) for the control loop for controlling the temperature of the component (170); providing a temperature model (320) for the exhaust gas temperature (312) of the exhaust gas (160) upstream of the component (170), wherein the temperature model (320) is used as a predictor for the control loop, and wherein a modeled control variable (340) is provided from the temperature model (320).

Description

Technical Field

[0001] The invention relates to a method and a device for controlling the temperature of a component in an exhaust tract of an internal combustion engine, wherein the exhaust tract has a temperature sensor which is arranged in the exhaust tract upstream of the component and wherein a control loop with a predictor is used for controlling the temperature of the component. Background Art

[0002] The exhaust duct of an internal combustion engine is designed, in particular, to conduct exhaust gases away from the internal combustion engine. In addition, in modern internal combustion engines, the exhaust duct is designed to remove or reduce harmful substances from the exhaust gas of the internal combustion engine. In this regard, the exhaust duct has, for example, an exhaust gas catalytic converter, which binds harmful substances in the exhaust gas catalytic converter by means of a chemical conversion by oxidation or by reduction. In addition, the exhaust duct can have a particle filter for filtering particles. During the operation of the internal combustion engine, the particle filter filters particles formed during the combustion of fuel in the internal combustion engine from the exhaust gas and thereby reduces the number of particles emitted to the surrounding environment.

[0003] The necessary operating temperatures of components in the exhaust tract, such as exhaust gas catalytic converters or exhaust gas particle filters, which are provided for reducing / filtering pollutants / particles from the exhaust gas of an internal combustion engine, vary. Since the exhaust gas catalysis performed in the exhaust gas catalytic converter requires a certain minimum temperature for effective aftertreatment, the necessary operating temperature of conventional exhaust gas catalytic converters is, for example, In the range of 200°C.

[0004] The temperature of components in the exhaust duct is conventionally regulated by means of temperature sensors arranged upstream or downstream of the respective component. For this purpose, a measurement signal detected by the temperature sensor is forwarded as an input variable to a control device, wherein the measurement signal characterizes the temperature of the exhaust gas in the exhaust duct at the respective position of the temperature sensor, whereby the parameters of the internal combustion engine are set by means of the control device in order to achieve the desired temperature of the respective component in the exhaust duct as quickly as possible.

[0005] Due to the delay times of such control systems and the relatively long heating phases of components in the exhaust tract, such as the exhaust gas catalytic converter, conventional control systems must be set very conservatively / slowly / carefully. Such setting of the control system results in suboptimal control and the control system cannot react optimally when manipulated variables occur. Summary of the invention

[0006] The object of the present invention is to provide a method and a device with which it is possible to reliably control the temperature of components in the exhaust tract of an internal combustion engine.

[0007] This object is achieved by a method having the features of the independent patent claim and a device designed to carry out the method. Advantageous embodiments of the method are described in the dependent claims.

[0008] According to the disclosure, a method for regulating the temperature of a component in an exhaust tract of an internal combustion engine comprises the following steps, wherein the exhaust tract has a temperature sensor which is arranged in the exhaust tract upstream of the component:

[0009] - providing a regulating circuit for regulating the temperature of said component;

[0010] - detecting a measurement signal with the temperature sensor during operation of the internal combustion engine, wherein the measurement signal characterizes the exhaust gas temperature of the exhaust gas upstream of the component, wherein the measurement signal is used as a measured controlled variable of a control circuit for controlling the component for controlling the temperature of the component;

[0011] - providing a temperature model for the exhaust gas temperature of the exhaust gas upstream of the component, wherein the temperature model is used as a predictor for the control loop and wherein a modeled control variable is provided from the temperature model;

[0012] - Using the modeled manipulated variable and the measured manipulated variable to set a manipulated variable of the control loop for controlling the temperature of the component.

[0013] According to one embodiment, the internal combustion engine can be a gasoline-operated or diesel-operated internal combustion engine. According to another embodiment, the internal combustion engine can also be operated using other fuels. The exhaust duct of the internal combustion engine is constructed to lead the exhaust gas of the internal combustion engine away from the internal combustion engine. Therefore, the exhaust gas of the internal combustion engine flows into the exhaust duct at the inlet area and flows out at the outlet area. Different components can be arranged in the exhaust duct between the inlet area and the outlet area. For example, these components are used to treat the exhaust gas and thereby reduce or filter harmful substances from the exhaust gas. According to the present disclosure, the temperature sensor is arranged upstream of the component in the exhaust duct. This means that the exhaust gas package flowing from the internal combustion engine through the exhaust duct first flows through or flows through the temperature sensor, and then flows through or flows through the component. According to the present disclosure, the control loop is a self-contained action process (in sich geschlossener Wirkungsablauf) for influencing the physical parameters in the technical process. At present, the control loop is used to set the temperature of the components in the exhaust duct of the internal combustion engine. Therefore, a temperature sensor is used to detect a measurement signal, which characterizes the exhaust gas temperature of the exhaust gas upstream of the component in the exhaust duct, correspondingly at the location of the temperature sensor. According to one embodiment, the measurement signal can be, for example, the exhaust gas temperature directly or another variable that characterizes the exhaust gas temperature of the exhaust gas. According to the disclosure, the measurement signal of the temperature sensor is used as a measured control variable for a control loop for controlling the temperature of the component. Therefore, the measurement signal is input into the control loop.

[0014] In addition, according to the present disclosure, a temperature model is provided for the exhaust gas temperature of the exhaust gas upstream of the component. According to one embodiment, the temperature model can be composed of one or more characteristic curve families, which provide corresponding output parameters for the exhaust gas temperature of the exhaust gas upstream of the component as a function of input parameters. The temperature model is thus used as a predictor for the control loop. The temperature model uses the models / calculations stored therein in order to output a prediction for future control variable changes based on the input parameters fed into the temperature model as a predictor. According to the present disclosure, the temperature model provides a modeled control variable. Therefore, the modeled control variable contains a prediction from the temperature model and the corresponding input parameters belonging thereto.

[0015] According to the disclosure, the modeled control variable and the measured control variable are used to set the manipulated variable of the control loop for adjusting the temperature of the component. In other words, the information of the modeled control variable and the measured control variable is incorporated into the manipulated variable. Therefore, on the one hand, the prediction from the temperature model as a predictor and the currently existing information from the temperature sensor as the measured control variable are incorporated into the manipulated variable. As a result, the manipulated variable can be adapted more quickly and better overall for adjusting the temperature of the component in a desired manner. Therefore, the modeled control variable contains information about the expected exhaust gas temperature based on the input parameters, while the measured control variable contains information about the actual existing temperature of the exhaust gas at the location of the temperature sensor. Both types of information are used to set the manipulated variable in an aggregated manner. Therefore, the manipulated variable and thus the entire control loop can be set in an aggressive manner / quickly / fast-response manner as a whole, whereby the control loop can set or adjust the temperature of the component very reliably and quickly as desired. In general, the temperature of the component can be set very quickly and reliably using the control loop using the method according to the present invention. In addition, it is possible to react quickly and reliably to disturbance variables or other external influences which influence the temperature control of the component.

[0016] According to one embodiment, the component is a particle filter, which is arranged in the exhaust tract of an internal combustion engine. The particle filter is a component that is operated at different temperatures. Therefore, it is increasingly important to adjust the temperature of the particle filter in the exhaust tract accordingly. The method for adjusting the temperature of a particle filter in the exhaust tract of an internal combustion engine according to this embodiment can advantageously set or adjust the temperature in the particle filter quickly and accurately, so that the particle filter as a whole can be operated in its optimal temperature window during its operating time depending on the operating phase.

[0017] According to another embodiment, the component is an exhaust gas catalytic converter, which is arranged in the exhaust duct of the internal combustion engine. The exhaust gas catalytic converter is arranged in the exhaust duct in order to reduce and bind harmful substances from the exhaust gas. In order to optimally operate the exhaust gas catalytic converter, it is necessary that the exhaust gas catalytic converter reaches a specific operating temperature or is operated as far as possible within a specific operating window so that the exhaust gas catalytic converter can well reduce harmful substances from the exhaust gas. For example, it is very important to quickly place the exhaust gas catalytic converter at the required operating temperature during the cold start of the internal combustion engine so that the exhaust gas catalytic converter can be operated in its optimal operating temperature window and can optimally reduce harmful substances from the exhaust gas. According to the method of this embodiment, the temperature of the exhaust gas catalytic converter in the exhaust duct is advantageously set or adjusted quickly so that the exhaust gas catalytic converter can be placed at the desired operating temperature very quickly or does not leave its temperature window. According to an additional embodiment, the component is an exhaust gas catalytic converter and a particle filter, so that the temperature of the exhaust gas catalytic converter and the particle filter is adjusted accordingly.

[0018] According to one embodiment, the manipulated variable of the control loop is a reserve torque of the internal combustion engine, which is set by controlling the ignition timing of the individual cylinders of the internal combustion engine. As disclosed herein, the reserve torque is a manipulated variable of the control loop. Therefore, the reserve torque is set according to or based on a modeled manipulated variable and a measured manipulated variable. According to the disclosure, the reserve torque is set by controlling the ignition timing of the individual cylinders of the internal combustion engine. Therefore, the control of the ignition timing is based on the modeled manipulated variable and the measured manipulated variable of the control loop. The ignition timing of the individual cylinders is an operating parameter of the internal combustion engine that can be set very accurately, so that the temperature of the component can be regulated very accurately and quickly by controlling the ignition timing.

[0019] According to one specific embodiment, a modeled manipulated variable is provided based on at least one operating parameter of the internal combustion engine using a temperature model. In other words, one of the operating parameters of the internal combustion engine is input into the temperature model, whereby the modeled manipulated variable is determined and provided to the control loop.

[0020] According to one embodiment, at least one of the operating parameters is the speed of the internal combustion engine, the load of the internal combustion engine, the current ignition angle of the internal combustion engine, the lambda value of the internal combustion engine, the exhaust gas mass flow of the internal combustion engine or the coolant temperature of the internal combustion engine. Other operating parameters of the internal combustion engine can be provided to the temperature model in addition. The above operating parameters of the internal combustion engine directly affect the temperature of the components in the exhaust duct. Therefore, by taking into account these operating parameters, the modeled control variables can be derived from the temperature model in a very accurately modeled manner. According to another embodiment, a large number of the above operating parameters plus possible additional parameters are supplied to the temperature model, from which the modeled control variables are determined and provided to the control loop.

[0021] According to one embodiment, a modeled regulating variable is additionally provided based on at least one ambient parameter with the aid of a temperature model. In other words, at least one ambient parameter is input together for determining the modeled regulating variable. By additionally setting the regulating variable based on the existing ambient conditions according to this embodiment, the regulation of the temperature of the component is additionally made more precise and more reliable. According to one embodiment, at least one of the ambient parameters is the ambient air temperature or the ambient air pressure. In particular, the ambient air temperature has an influence on the temperature of the component immediately after a cold start of the internal combustion engine, but also during the operation of the internal combustion engine. Therefore, it is particularly advantageous to take the ambient air temperature and the ambient air pressure into account when determining the modeled regulating variable with the aid of a temperature model. According to one embodiment, the component temperature is equated with the exhaust gas temperature in the temperature model.

[0022] According to one embodiment, the temperature model is a dynamic temperature model, which suppresses disturbance variables of the control loop by means of a damping function. A dynamic temperature model differs from a temperature model in that additional parameters are taken into account. According to one embodiment, the heat conduction from the exhaust gas to the component is taken into account in the dynamic temperature model. In this case, the gradient of the heat conduction is described by the temperature drop between the exhaust gas temperature and the component temperature. According to this embodiment, the component has a higher heat capacity than the exhaust gas. The heat capacity influences the heating and cooling characteristics of the component. According to this embodiment, this is taken into account in the dynamic temperature model.

[0023] According to one embodiment, the temperature model has a temperature model without dead time and a temperature model with dead time. The time interval between the signal change at the system input of the control loop and the signal response at the system output is called the dead time (Totzeit). The temperature model without dead time is that part of the temperature model that is not affected by the influence of the dead time or is only very slightly affected by the influence of the dead time. In contrast, the temperature model with dead time is that part of the temperature model that is more or less strongly affected by the influence of the dead time. By separating the temperature model without dead time from the temperature model with dead time, the influence can be additionally accurately distributed or clustered, thereby additionally enabling faster and more accurate regulation of the temperature of the component. According to one embodiment, the temperature model is a Smith predictor.

[0024] According to another aspect of the present disclosure, a computer program product has at least one computer-readable storage medium having computer-executable program code instructions stored thereon, wherein the computer-executable program code instructions are configured to perform the above method. The computer program product can be stored, for example, in an engine control unit of an internal combustion engine.

[0025] According to another aspect of the disclosure, a device for regulating the temperature of a component in an exhaust duct of an internal combustion engine has a control unit, which is configured to control the above method. The device can be, for example, an engine control unit. It is also conceivable that the device is part of the engine control unit or is installed as an additional control unit, for example in a vehicle with an internal combustion engine. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Embodiments and improvements of the method according to the present disclosure are shown in the figures and are explained in more detail according to the following description.

[0027] Figure 1 A schematic diagram showing an internal combustion engine with an exhaust tract and a control unit,

[0028] Figure 2 A block diagram of a method for controlling the temperature of a component in an exhaust tract of an internal combustion engine is shown. DETAILED DESCRIPTION

[0029] Figure 1The schematic diagram of an internal combustion engine 100 is shown with an exhaust duct 110, which is designed to discharge exhaust gas 160 of the internal combustion engine 100. The internal combustion engine 100 has an internal combustion engine block 120 and an ignition system 130. The ignition system 130 is designed to control the ignition of individual fuel-air mixtures in the cylinders of the internal combustion engine block 120. The internal combustion engine 100 also has an intake duct 140, which is designed to conduct intake air 150 into the internal combustion engine block 120. The exhaust duct 110 discharges the exhaust gas 160 from the internal combustion engine block 120. According to Figure 1 , the exhaust passage 110 has a particle filter 172 and an exhaust gas catalytic converter 174. The exhaust gas catalytic converter is arranged downstream of the internal combustion engine block 120. The particle filter 172 is arranged downstream of the exhaust gas catalytic converter 174 in the exhaust gas flow direction. The particle filter 172 and the exhaust gas catalytic converter 174 are arranged in the exhaust passage 110 as components 170. The exhaust passage 110 additionally has a temperature sensor 180. The temperature sensor 180 is arranged in the exhaust passage 110 upstream of the exhaust gas catalytic converter 174 and downstream of the internal combustion engine block 120. The temperature sensor 180 is configured to detect a measurement signal 310 ( Figure 2 ), wherein measurement signal 310 characterizes exhaust gas temperature 312 ( Figure 2 ).

[0030] Figure 1 Furthermore, a control unit 200 is shown, which has a computing unit 210, a data memory 220, a program memory 230 and an error memory 240. The control unit 200 is designed to process a measurement signal 310 of the temperature sensor 180. The control unit 200 is also designed to carry out the method according to the disclosure and thereby regulate the temperature of the component 170 in the exhaust duct 110 of the internal combustion engine 100. In this regard, the necessary parameters can be stored in the data memory 220 of the control unit 200. In addition, a temperature model 320 ( Figure 2 ) can be stored in program memory 230 of control unit 200. During operation of internal combustion engine 100, computing unit 210 of control unit 200 can determine modeled manipulated variable 340 ( Figure 2 ) and the measured control variable 330 ( Figure 2 ) and is provided to the control loop, from which a manipulated variable 350 ( Figure 2), wherein manipulated variable 350 is supplied to ignition system 130 of internal combustion engine 100 in order to adjust the temperature of at least one of components 170 in exhaust duct 110 of internal combustion engine 100. If an error should occur during the adjustment of the temperature of at least one of components 170, the error can be stored in error memory 240 of control unit 200. In addition, error display device 250 can be activated in order to display the error to a user of internal combustion engine 100 or a driver of a vehicle having internal combustion engine 100.

[0031] Figure 2 A block diagram 300 of an exemplary embodiment of a method according to the disclosure is shown, which method can be executed on a control unit 200, for example. According to the block diagram 300, a measurement signal 310 is provided, which characterizes an exhaust gas temperature 312. From the measurement signal 310, a measured control variable 330 is provided, which is used to control the temperature of a component. In addition, a temperature model 320 is provided, wherein the temperature model 320 has a temperature model 322 without dead time and a temperature model 324 with dead time. The temperature model 320 can be stored in the program memory 230 of the control unit 200. The temperature model 320 is used as a predictor 326 of a control loop for controlling the temperature of the component 170. An operating parameter 342 and an environmental parameter 344 of the internal combustion engine 100 are input into the temperature model 320. With the aid of the temperature model 320 and the input data (operating parameter 342 and environmental parameter 344), a modeled control variable 340 is determined, which is used to control the temperature of the component 170. A manipulated variable 350 for the control loop is determined from modeled manipulated variable 340 and measured manipulated variable 330. Manipulated variable 350 is transmitted to ignition system 130 of internal combustion engine 100, whereby a reserve torque is controlled by means of the ignition angle, whereby the temperature of component 170 in exhaust duct 110 is regulated.

Claims

1. A method for regulating the temperature of a component (170) in an exhaust duct (110) of an internal combustion engine (100), wherein the exhaust duct (110) has a temperature sensor (180) which is arranged in the exhaust duct (110) upstream of the component (170), wherein the method comprises the following steps: - providing a regulating circuit for regulating the temperature of the component (170); - detecting a measurement signal (310) with the temperature sensor (180) during operation of the internal combustion engine (100), wherein the measurement signal (310) characterizes an exhaust gas temperature (312) of the exhaust gas (160) upstream of the component (170), wherein the measurement signal (310) is used as a measured control variable (330) for the control circuit for controlling the temperature of the component (170); - providing a temperature model (320) for the exhaust gas temperature (312) of the exhaust gas (160), wherein the temperature model (320) is used as a predictor for the control loop, and wherein a modeled control variable (340) is provided from the temperature model (320); - using the modeled manipulated variable (340) and the measured manipulated variable (330) to set a manipulated variable (350) of the control loop for regulating the temperature of the component (170), The temperature model (320) comprises a temperature model without dead time (322) and a temperature model with dead time (324), wherein the time interval between a signal change at the system input of the control loop and a signal response at the system output is referred to as the dead time, wherein the component (170) is a particle filter (172) arranged in an exhaust duct (110) of the internal combustion engine (100), or wherein the component (170) is an exhaust gas catalytic converter (174) arranged in an exhaust duct (110) of the internal combustion engine (100), The manipulated variable (350) of the control loop is a reserve torque of the internal combustion engine (100), which is set by controlling the ignition timing of the individual cylinders of the internal combustion engine (100). The modeled manipulated variable (340) is provided with the aid of the temperature model (320) based on at least one operating parameter (342) of the internal combustion engine (100).

2. The method according to claim 1, wherein at least one of the operating parameters (342) is a rotational speed of the internal combustion engine (100), a load of the internal combustion engine (100), an ignition angle of the internal combustion engine (100), a lambda value of the internal combustion engine (100), an exhaust gas mass flow rate of the internal combustion engine (100), or a coolant temperature of the internal combustion engine (100). 3 . The method according to claim 1 , wherein the modeled manipulated variable ( 340 ) is additionally provided with the aid of the temperature model ( 320 ) based on at least one ambient parameter ( 344 ).

4. The method of claim 3, wherein at least one of the environmental parameters (344) is an ambient air temperature or an ambient air pressure. 5 . The method according to claim 1 , wherein the temperature model ( 320 ) is a dynamic temperature model which suppresses disturbance variables on the control loop by means of a damping function.

6. A device for regulating the temperature of a component (170) in an exhaust duct (110) of an internal combustion engine (100), wherein the device has a control unit (200) for controlling the method according to any of the preceding claims.

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