DE102022103350A1 - Method for heating an exhaust system, an exhaust system and a motor vehicle - Google Patents

Abstract

The invention relates to a method for heating an exhaust system (10) of a motor vehicle with a catalytic converter (12), the exhaust system (10) comprising an electrically heatable heating disc (14) which is located upstream of the catalytic converter (12) in the direction of flow of a carrier mass flow (16). is arranged in the exhaust system (10), comprising the steps of: determining values of one or more electrical parameters at time intervals during the heating of the electrically heatable heated pane (14); determine whether a sufficiently large carrier mass flow (16) is present by evaluating the determined values of the one or more electrical parameters of the electrically heatable heated pane (14). The invention also relates to an exhaust system and a vehicle with an exhaust system.

Description

The invention relates to a method for heating an exhaust system of a motor vehicle, an exhaust system of a motor vehicle and a motor vehicle with such an exhaust system.

To ensure extremely low emissions, a heating pane can be used to preheat an exhaust system of a motor vehicle. For this purpose, a carrier mass flow (e.g. air) flows around or through the electrically heated heating disk and the downstream catalytic converter is heated. If the carrier mass flow is not available or is only insufficiently available, the heating disc may overheat and be damaged.

US5740675A discloses a system and a method for estimating a temperature of an exhaust system with an electrically heatable catalytic converter, the temperature of the exhaust system being estimated using the electrical parameters of the electrically heatable catalytic converter.

The disadvantage here is that a missing or insufficient carrier mass flow cannot be reliably detected and the heating pane cannot be protected from damage due to overheating.

It is the object of the invention to provide a method for heating an exhaust system of a motor vehicle, an exhaust system of a motor vehicle and a motor vehicle with such an exhaust system, in which case a missing or insufficient carrier mass flow can be reliably detected and damage to the heated pane by overheating can be avoided.

The object is achieved by a method for heating an exhaust system of a motor vehicle according to claim 1, an exhaust system of a motor vehicle according to claim 8 and a motor vehicle according to claim 10.

• Ermitteln von (aktuellen) Werten (bspw. Messwerten) einer oder mehrerer elektrischer Kenngrößen in, insbesondere regelmäßigen, Zeitintervallen während des Beheizens der elektrisch beheizbaren Heizscheibe.

The method according to the invention for heating an exhaust system of a motor vehicle with a catalytic converter, in particular for heating or preheating the catalytic converter, the exhaust system comprising an electrically heatable heating disk which is arranged in the flow direction of a carrier mass flow (e.g. air) in front of the catalytic converter in the exhaust system , includes the steps:

• Determination of (current) values (e.g. measured values) of one or more electrical parameters in, in particular regular, time intervals during the heating of the electrically heatable heated pane.

Determining whether a sufficiently large carrier mass flow is present by evaluating the determined values of the one or more electrical parameters of the electrically heatable heated pane.

An insufficient carrier mass flow can be caused, for example, by a leak or a jammed valve in a line leading to the heating disc and the carrier mass flow. An insufficiently large carrier mass flow can be a missing carrier mass flow and/or a carrier mass flow that is interrupted at time intervals. An insufficiently large carrier mass flow can be present if the carrier mass flow is (constant) present, but not large enough (i.e. not sufficient to dissipate the thermal energy from the heated heating pane, so that it can overheat).

By evaluating the determined values of the one or more electrical parameters, it can be determined with certainty whether the carrier mass flow is present and whether it is large enough to dissipate the thermal energy from the heated heating pane. If it is determined that the carrier mass flow is not sufficiently large, the heating disc can be switched off, for example, and the heating disc can thus be prevented from overheating.

The carrier mass flow in the exhaust system can preferably be provided by a secondary air pump or an electric exhaust gas turbocharger.

The one or more electrical parameters of the electrically heatable heated pane can preferably be the electrical current intensity, the electrical resistance, the electrical voltage and/or the electrical power of the electrically heatable heated pane.

The electrical power cannot be determined (measured) directly. However, it can, for example, be determined (determined) from the ascertained voltage and current strength, in particular by calculation.

• Erstellen mindestens einer zeitabhängigen Funktion aus den ermittelten Werten der mindestens einen elektrischen Kenngröße. Vorzugsweise wird aus den ermittelten Werten der Kenngröße(n) und den Zeitintervallen, in denen die Werte ermittelt worden sind, eine Kennlinie erstellt. Anders ausgedrückt, die ermittelten Werte der Kenngröße(n) werden in einem Diagramm über der Zeit aufgetragen, so dass eine Kennlinie entsteht.

The evaluation of the determined values of the one or more electrical parameters can preferably include:

• Creating at least one time-dependent function from the determined values of the at least one electrical parameter. A characteristic curve is preferably created from the determined values of the parameter(s) and the time intervals in which the values were determined. In other words, the determined values of the parameter(s) are displayed in a slide gram plotted against time, resulting in a characteristic curve.

Determination and evaluation of at least one derivative function (or a gradient) of the time-dependent function of the determined values of the at least one electrical parameter of the electrically heatable heated pane.

By a derivative function is meant the derivative function of the first degree. In this case, the derivation function corresponds in particular to the derivation in the mathematical sense, ie the slope of the time-dependent function from the determined (measured) values of the electrical parameter.

• Vergleich des Verlaufs der Ableitungsfunktion (bzw. des Gradienten) mit einem Verlauf einer Idealableitungsfunktion, die aus einer Idealfunktion ermittelt wird, die aus idealen, vorbestimmten Idealwerten erstellt ist. Auch die Idealableitungsfunktion ist eine Ableitungsfunktion ersten Grades im mathematischen Sinne.

Preferably, evaluating the derivative function can include:

• Comparison of the course of the derivation function (or the gradient) with a course of an ideal derivation function that is determined from an ideal function that is created from ideal, predetermined ideal values. The ideal derivative function is also a first-degree derivative function in the mathematical sense.

In other words, an actual gradient (of the derivative function) can be compared with an (ideal) target gradient (of the ideal derivative function). It is also conceivable for the values to be evaluated by comparing the time-dependent function from the determined values with the ideal function or by comparing the individual values with the ideal values.

The ideal function can be created (determined) from ideal values that correspond to a carrier mass flow that is sufficiently large, that is, in order. If a discrepancy is established during the comparison, then it can be concluded that the carrier mass flow is absent and/or insufficient.

This can preferably include evaluating the derivative function: comparing the start value of the derivative function with the ideal start value of the ideal derivative function.

In particular, the deviation of the values (ie the distance between the respective X value in the characteristic curve diagram) can be greatest here. For example, right at the start of the heating-up phase of the heating pane, a faulty carrier mass flow can be deduced and appropriate measures can be taken, e.g. B. switching off the heated window and / or issuing an alarm signal (acoustic and / or optical) to the user or the driver of the motor vehicle.

• Ermitteln einer Zeitspanne, die zur Erreichung eines vorbestimmten Schwellwerts der Ableitungsfunktion benötigt wird.

Preferably, evaluating the derivative function can include:

• Determining a period of time that is required to reach a predetermined threshold value of the derivative function.

Comparison of the determined time span with an ideal time span that is required to reach the predetermined threshold value of the ideal derivation function.

If there is a discrepancy between the determined period of time and the ideal period of time, it can be concluded that the carrier mass flow is absent and/or insufficient.

According to the invention, an exhaust system of a motor vehicle comprising at least one catalytic converter and at least one electrically heatable heated window is proposed, the exhaust system being set up such that at least one value of an electrical parameter of the electrically heated heated window can be determined (measured).

The exhaust system can include a secondary air pump or an electric exhaust gas turbocharger.

Preferably, the exhaust system can be set up to be heated with a method according to the above statements. With regard to the advantages that can be achieved in this way, reference is made to the relevant statements on the method. The measures described in connection with the method and/or the measures explained below can be used to further refine the exhaust system.

In particular, the catalytic converter of the exhaust system can be heated with the method.

According to the invention, a motor vehicle is proposed with an exhaust system according to the above statements. With regard to the advantages that can be achieved in this way, reference is made to the relevant statements on the exhaust system. The measures described in connection with the exhaust system and/or the measures explained below can serve to further refine the motor vehicle.

The motor vehicle can include a secondary air pump or an electric exhaust gas turbocharger.

• 1 schematisch eine Abgasanlage eines Kraftfahrzeugs;
• 2 ein Verhalten der Abgasanlage bei konstanter Spannung mit zeitabhängigen Funktionen der ermittelten Werte von Kenngrößen ( 2c, 2e, 2g) und deren Ableitungsfunktionen (2d, 2f, 2h);
• 3 eine vergrößerte Darstellung des Diagramms gemäß 2d;
• 4 ein Verhalten der Abgasanlage bei konstanter Leistung mit zeitabhängigen Funktionen der ermittelten Werte von Kenngrößen ( 4c, 4e, 4g) und deren Ableitungsfunktionen (4d, 4f, 4h); und
• 5 eine vergrößerte Darstellung des Diagramms gemäß 4h.

Further advantageous configurations result from the following description and the drawing. In the drawing shows

• 1 schematically an exhaust system of a motor vehicle;
• 2 a behavior of the exhaust system at constant voltage with time-dependent functions of the determined values of parameters ( 2c , 2e , 2g) and their derivative functions ( 2d , 2f , 2h) ;
• 3 an enlarged representation of the diagram according to 2d ;
• 4 a behavior of the exhaust system at constant power with time-dependent functions of the determined values of parameters ( 4c , 4e , 4g) and their derivative functions ( 4d , 4f , 4 hours) ; and
• 5 an enlarged representation of the diagram according to 4 hours .

1 shows schematically an exhaust system 10 of a motor vehicle with a catalytic converter 12. The exhaust system includes an electrically heatable heated disk 14. In the present case, a carrier mass flow 16 is provided by a secondary air pump 18 or an electric turbocharger 20. The carrier mass flow 16 flows around or through the heated disk 14 and then reaches the catalytic converter 12. In other words, the heated disk 14 is arranged upstream of the catalytic converter 12 in the exhaust system 10 in the flow direction of the carrier mass flow 16.

If the heated disk 14 is heated (indicated by an arrow), it heats up and heats the carrier mass flow 16 which flows around or through the heated disk 14 . The carrier mass flow 16 heated in this way in turn heats the catalytic converter 12. If there is no carrier mass flow or if it is not sufficiently available, the heat energy is not removed or only insufficiently removed from the heated disk 14, so that the heated disk 14 can overheat. This can be prevented by determining and evaluating characteristic values of at least one electrical parameter of the heated pane 14 .

The 2a - 2h show a behavior of the exhaust system 10 at constant electrical voltage (U). In other words, the electrical voltage (U) remains constant over time (t) (cf. 2a) . 2 B illustrates the difference between an existing and sufficiently high carrier mass flow 16 (mSL) (solid line) and a non-existent carrier mass flow 16 (mSL) (dashed line) over time (t).

In the 2c , 2e , 2g a time-dependent function 22 of the determined values of parameters is plotted over time (t). The values of the time-dependent functions 22 were determined when the carrier mass flow 16 was not present. These time-dependent functions 22 are each represented by a dashed line. In addition, an ideal function 28 over time (t) is shown in each case by means of a dashed line. The ideal functions 28 each correspond to the ideal values that would be measured if the carrier mass flow 16 was present. The deviation of the respective values of the respective parameters as a function of a carrier mass flow 16 that is present or not present is thus illustrated.

In 2c the electrical current (l) is plotted against time (t) as a parameter. In 2e the electrical resistance (R) is plotted against time (t) as a parameter. In 2g the electrical power (P) is plotted against time (t) as a parameter.

In the 2d , 2f , 2h the derivative functions 24 of the time-dependent functions 22 and the ideal derivative functions 26 of the ideal functions 28 are shown in each case. So is in 2d the derivative of the electric current (I') plotted against time (t). In 2f the derivative of the electrical resistance (R') is plotted against time (t). In 2h the derivation of the electrical power (P') is plotted over time (t).

In 3 is an enlarged view of the 2d shown. It can be seen that the start value 30 of the derivative function 24 differs significantly from the ideal start value 32 of the ideal derivative function 26 . From the comparison of these two starting values 30, 32, it is possible to draw conclusions about the presence or absence of carrier mass flow 16. In the present case, the starting value 30 is smaller than the ideal starting value 32.

In addition, the time required to reach a predetermined threshold value 36 can be determined from the respective derivative functions 24, 26. This threshold value 36 is thus reached in the derivative function 24 after a period of time 34 . In the case of the ideal derivation function 26, this threshold value 36 is reached after an ideal period of time 38. From the comparison of these two periods of time 34, 38, it is possible to draw conclusions about the presence or absence of a carrier mass flow 16. In the present case, the period of time 34 is shorter than the ideal period of time 38.

The 4a - 4 hours show a behavior of the exhaust system 10 at constant electrical power (P). In other words, the electrical power (P) remains constant over time (t) (cf. 4a) . 4b illustrates the difference between a carrier mass flow 16 (mSL) present (solid line) and a non-existent carrier mass flow 16 (mSL) (dashed line) over time (t).

In the 4c , 4e , 4g a time-dependent function 22 of the determined values of parameters is plotted over time (t). The values of the time-dependent functions 22 were determined when the carrier mass flow 16 was not present. These time-dependent functions 22 are each represented by a dashed line. In addition, an ideal function 28 over time (t) is shown in each case by means of a dashed line. The ideal functions 28 each correspond to the ideal values that would be measured if the carrier mass flow 16 was present. The deviation of the respective values of the respective parameters as a function of a carrier mass flow 16 that is present or not present is thus illustrated.

In 4c the electrical current (I) is plotted against time (t) as a parameter. In 4e the electrical resistance (R) is plotted against time (t) as a parameter. In 4g the electrical voltage (U) is plotted against time (t) as a parameter.

In the 4d , 4f , 4 hours the derivative functions 24 of the time-dependent functions 22 and the ideal derivative functions 26 of the ideal functions 28 are shown in each case. So is in 4d the derivative of the electric current (I') plotted against time (t). In 4f the derivative of the electrical resistance (R') is plotted against time (t). In 4 hours the derivation of the electrical voltage (U') is plotted against time (t).

In 5 is an enlarged view of the 4 hours shown. It can be seen that the start value 30 of the derivative function 24 differs significantly from the ideal start value 32 of the ideal derivative function 26 . From the comparison of these two starting values 30, 32, it is possible to draw conclusions about the presence or absence of carrier mass flow 16. In the present case, the starting value 30 is greater than the ideal starting value 32.

In addition, the time required to reach a predetermined threshold value 36 can be determined from the respective derivative functions 24, 26. This threshold value 36 is thus reached in the derivative function 24 after a period of time 34 . In the case of the ideal derivation function 26, this threshold value 36 is reached after an ideal period of time 38. From the comparison of these two periods of time 34, 38, it is possible to draw conclusions about the presence or absence of a carrier mass flow 16. In the present case, the period of time 34 is longer than the ideal period of time 38.

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• US5740675A [0003]

Claims (10)

Method for heating up an exhaust system (10) of a motor vehicle with a catalytic converter (12), the exhaust system (10) comprising an electrically heatable heating disk (14) which, in the direction of flow of a carrier mass flow (16), is located upstream of the catalytic converter (12) in the exhaust system ( 10) is arranged, comprising the steps: - determining values of one or more electrical parameters at, in particular regular, time intervals during the heating of the electrically heatable heated pane (14); - Determining whether a sufficiently large carrier mass flow (16) is present by evaluating the determined values of the one or more electrical parameters of the electrically heatable heated pane (14). procedure after claim 1 , characterized in that the carrier mass flow (16) in the exhaust system (10) is provided by a secondary air pump (18) or an electric exhaust gas turbocharger (20). procedure after claim 1 or claim 2 , characterized in that the one or more electrical parameters of the electrically heatable heated pane (14) are the electrical current intensity, the electrical resistance, the electrical voltage and/or the electrical power of the electrically heatable heated pane (14). Method according to one of the preceding claims, characterized in that the evaluation of the determined values of the one or more electrical parameters comprises: - creating at least one time-dependent function (22) from the determined values of the at least one electrical parameter; - determining and evaluating at least one derivative function (24) of the time-dependent function (22) of the determined values of the at least one electrical parameter of the electrically heatable heated pane (14). procedure after claim 4 , characterized in that the evaluation of the derivative function (24) comprises: - a comparison of the profile of the derivative function (24) with a profile of an ideal derivative function (26) which is determined from an ideal function (28) which is created from ideal, predetermined ideal values . procedure after claim 4 or 5 , characterized in that the evaluation of the derivation function (24) comprises: - a comparison of the start value (30) of the derivation function (24) with the ideal start value (32) of the ideal derivation function (26). Procedure according to one of Claims 4 until 6 , characterized in that the evaluation of the derivative function (24) comprises: - determining a period of time (34) which is required to reach a predetermined threshold value (36) of the derivative function (24); - Comparison of the determined period of time (34) with an ideal period of time (38) that is required to reach the predetermined threshold value (36) of the ideal derivation function (26). Exhaust system (10) of a motor vehicle comprising at least one catalytic converter (12) and at least one electrically heatable heated window (14), the exhaust system (10) being set up in such a way that at least one value of an electrical parameter of the electrically heated heated window (14) can be determined . Exhaust system (10) after claim 8 , characterized in that the exhaust system (10) is set up to use the method according to any one of Claims 1 until 7 to be heated up. Motor vehicle comprising an exhaust system (10). claim 8 or 9 .

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