KR20230122545A - Method for heating an exhaust gas system, an exhaust gas system, and a motor vehicle - Google Patents

Abstract

The present invention relates to a method for heating a motor vehicle exhaust system (10) having a catalytic converter (12), wherein the exhaust system (10) has a flow direction of a carrier mass flow (16) in the exhaust system (10). an electrically heated heating disk (14) disposed upstream of the catalytic converter (12), wherein the method comprises the following steps: value of one or more electrical parameters at time intervals during heating of the electrically heated heating disk (14); Calculating; determining whether a sufficiently large carrier mass flow (16) is present by evaluating calculated values of one or more electrical parameters of the electrically heated heating disk (14). The invention also relates to an exhaust gas system and a motor vehicle having an exhaust gas system.

Description

METHOD FOR HEATING AN EXHAUST GAS SYSTEM, AN EXHAUST GAS SYSTEM, AND A MOTOR VEHICLE

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

For the purpose of ensuring lowest emissions, heating disks can be used to preheat the vehicle's exhaust gas system. To this end, a carrier mass flow (eg air) flows around or through the electrically heated heating disk, and the downstream catalytic converter is heated. Absent or insufficient carrier mass flow can cause overheating or damage to the heating disk.

US 5740675 A discloses a system and method for estimating the temperature of an exhaust gas system having an electrically heatable catalytic converter, wherein the temperature of the exhaust system is estimated via electrical parameters of the electrically heatable catalytic converter.

Disadvantages in this case are that an absent or insufficient carrier mass flow cannot be reliably detected and the heating disk cannot be protected from damage due to overheating.

The object of the present invention is a method for heating an exhaust gas system of a motor vehicle, an exhaust gas system of a motor vehicle, in which an absent or insufficient carrier mass flow can be reliably detected and damage to the heating disk due to overheating can be prevented. and an automobile having such an exhaust gas system.

The problem is solved by a method for heating a vehicle exhaust gas system according to claim 1, a vehicle exhaust gas system according to claim 8, and a vehicle according to claim 10.

In the method according to the invention for heating the exhaust gas system of a motor vehicle having a catalytic converter, in particular for heating or preheating a catalytic converter, said exhaust gas system contains a carrier mass flow (eg air) in said exhaust gas system. An electrically heated heating disk arranged upstream of the catalytic converter in the flow direction, the method comprising the following steps:

calculating (current) values (eg measured values) of one or more electrical parameters during heating of the electrically heated heating disk, in particular at regular, time intervals;

determining whether a sufficiently high carrier mass flow is present by evaluating calculated values of one or more electrical parameters of the electrically heated heating disk.

An insufficient amount of carrier mass flow can be caused, for example, by leaking or sticking valves in the line leading to the heating disk and guiding the carrier mass flow. An insufficient amount of carrier mass flow may be an absent and/or intermittent carrier mass flow. An insufficient amount of carrier mass flow may occur if the carrier mass flow is (constantly) present but not large enough to dissipate thermal energy from the heated heating disk so that the heating disk may overheat. can exist

By evaluating the calculated values of one or more electrical parameters, it is possible to reliably determine whether a carrier mass flow is present and sufficient to dissipate thermal energy from the heated heating disk. If it is determined that the carrier mass flow is not high enough, the heating disk can for example be switched off, thus preventing overheating of the heating disk.

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

Preferably, the one or more electrical parameters of the electrically heated heating disk may be current strength, electrical resistance, voltage and/or power of the electrically heated heating disk.

Power cannot be calculated (measured) directly. However, the power can be determined (calculated), in particular by calculation, for example on the basis of the calculated voltage and current intensity.

Preferably, evaluation of the calculated value of one or more electrical parameters may include:

generating at least one time dependent function from the calculated values of the at least one electrical parameter. Preferably, the characteristic curve is generated from the calculated values of the parameter(s) and the time intervals over which the values were calculated. In other words, the calculated values of the parameter(s) are plotted in a diagram over time to create a characteristic curve.

Determining and evaluating at least one derivative (or gradient) of a time dependent function of a calculated value of at least one electrical parameter of an electrically heated heating disk.

Here, the derivative means the first derivative. A derivative corresponds in particular to a derivative in the mathematical sense, ie the slope of a time-dependent function from a calculated (measured) value of an electrical parameter.

Preferably, the evaluation of the derivative may include:

Comparing the profile of the derivative (or gradient) with the profile of the ideal derivative calculated from an ideal function generated from ideal predetermined ideal values. An ideal derivative is also a first derivative in a mathematical sense.

In other words, a comparison of the actual gradient (of the derivative) and the (ideal) target gradient (of the ideal derivative) may be performed. It is also conceivable that the evaluation of the value is performed by comparison of a time-dependent function of calculated values with an ideal function or by comparison of individual values with ideal values.

The ideal function can be generated (determined) from a sufficiently large number of outliers corresponding to the normal carrier mass flow. If a deviation is identified in the comparison, an absent and/or insufficient carrier mass flow can be inferred.

Preferably, the evaluation of the derivative may include:

Comparing the starting value of the derivative with the ideal starting value of the ideal derivative.

In particular, the deviation of the values (ie, the distance between each X value in the characteristic curve diagram) may be greatest here. Thus, for example, immediately at the start of the heating phase of the heating disk, the absence of carrier mass flow can be deduced and a corresponding action, such as switching off the heating disk and/or prompting the user or driver of the motor vehicle (acoustic Actions may be taken, such as outputting a warning signal (visually and/or visually).

Preferably, the evaluation of the derivative may include:

Calculating the period required to achieve a predetermined threshold of the derivative.

comparing the calculated duration with the ideal duration required to achieve a predetermined threshold of the ideal derivative.

If there is a deviation between the calculated period and the ideal period, an absent and/or insufficient carrier mass flow can be inferred.

According to the invention, a motor vehicle exhaust system is proposed, comprising at least one catalytic converter and at least one electrically heated heating disk, wherein the exhaust gas system calculates the value of at least one electrical parameter of the electrically heated heating disk ( is configured to be measured).

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

Preferably, the exhaust gas system can be configured to be heated by the method according to the above description. With respect to the advantages that can be achieved in this way, reference is made to the relevant description of the method. The measures described in relation to the method and/or described further below may be used in other configurations of the exhaust gas system.

In particular, the catalytic converter of the exhaust gas system can be heated in this way.

According to the present invention, an automobile having an exhaust gas system according to the above embodiment is proposed. With regard to the advantages that can be achieved herewith, reference is made to the relevant description of the exhaust gas system. The measures described in relation to the exhaust gas system and/or described further below may be used in another configuration of the motor vehicle.

Vehicles may include a secondary air pump or an electric exhaust turbocharger.

Another preferred configuration of the present invention is set forth in the following description and drawings.

1 is a schematic diagram of an exhaust gas system of a vehicle.
Fig. 2 shows the behavior of the exhaust gas system at constant voltage, with time-dependent functions of the calculated values of the parameters (Figs. 2c, 2e, 2g) and their derivatives (Figs. 2d, 2f, 2h); it is a graph
Fig. 3 is an enlarged view of the diagram according to Fig. 2d;
Fig. 4 shows the behavior of the exhaust gas system at constant power, with time-dependent functions of the calculated values of the parameters (Figs. 4c, 4e, 4g) and their derivatives (Figs. 4d, 4f, 4h). It is the graph shown.
Fig. 5 is an enlarged view of the diagram according to Fig. 4h;

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

When the heating disk 14 is heated (indicated by the arrow), the heating disk 14 itself heats up and heats the carrier mass stream 16 flowing around or through it. The carrier mass stream 16 heated in this way in turn heats the catalytic converter 12 . If the carrier mass flow is absent or insufficient, thermal energy may not be removed from the heating disk 14 or only insufficiently removed, resulting in overheating of the heating disk 14 . This can be prevented by calculating and evaluating the characteristic value of at least one electrical parameter of the heating disk 14 .

2a to 2h show the behavior of the exhaust gas system 10 at a constant voltage U. In other words, voltage U remains constant over time t (see FIG. 2A). In this case, FIG. 2b shows the difference between a sufficiently large carrier mass flow 16 (mSL) present (solid line) and an absent carrier mass flow 16 (mSL) (dashed line) over time t.

In Figures 2c, 2e and 2g, the time dependence function 22 of the calculated value of the parameter as a function of time t is shown, respectively. The value of the time dependent function 22 was calculated when no carrier mass flow 16 was present. Each of these time dependent functions 22 is shown as a broken line. Additionally, the ideal function 28 as a function of time t is shown as a dashed line. Each of the ideal functions 28 corresponds to an outlier to be measured in the presence of a carrier mass flow 16 . Thus, the deviation of the respective values of each parameter is illustrated as a function of the present or absent carrier mass flow 16 .

2C shows the current intensity I as a function of time t as a parameter. Fig. 2e shows the electrical resistance R as a function of time t as a parameter. Figure 2g shows power (P) as a function of time (t) as a parameter.

2d, 2f and 2h respectively show the derivative 24 of the time dependent function 22 as well as the ideal derivative 26 of the ideal function 28. That is, the derivative of the current intensity (I') according to time (t) is shown in FIG. 2D. Figure 2f shows the derivative of electrical resistance R' as a function of time t. 2H shows the derivative of power P' as a function of time t.

Figure 3 shows an enlarged view of the diagram of Figure 2d. It can be seen that the starting value 30 of the derivative 24 differs significantly from the ideal starting value 32 of the ideal derivative 26. Here, the presence or absence of the carrier mass flow 16 can be inferred from the comparison of the two starting values 30 and 32 . Here, the starting value 30 is smaller than the ideal starting value 32.

Further, from each of the derivatives 24 and 26 the time required to reach the predetermined threshold 36 can be determined. That is, the threshold 36 is reached after a period 34 for the derivative 24 . In the case of an ideal derivative (26), the threshold (36) is achieved after an ideal period (38). Here, the presence or absence of carrier mass flow 16 can be inferred from the comparison of the two periods 34, 38. The period 34 here is shorter than the ideal period 38 .

Figures 4a to 4h show the behavior of the exhaust gas system 10 at a constant power P. In other words, power P remains constant with time t (see FIG. 4A). In this case, FIG. 4b shows the difference between the present carrier mass flow 16 (mSL) (solid line) and the absent carrier mass flow 16 (mSL) (dashed line) over time t.

In Figures 4c, 4e and 4g, the time dependence function 22 of the calculated value of the parameter as a function of time t is shown, respectively. The value of the time dependent function 22 was calculated when no carrier mass flow 16 was present. Each of these time dependent functions 22 is shown as a broken line. Additionally, the ideal function 28 as a function of time t is shown as a dashed line. Each of the ideal functions 28 corresponds to an outlier to be measured in the presence of a carrier mass flow 16 . Thus, the deviation of the respective values of each parameter is illustrated as a function of the present or absent carrier mass flow 16 .

4C shows the current intensity I as a function of time t as a parameter. Fig. 4e shows the electrical resistance R as a function of time t as a parameter. Figure 4g shows the voltage U as a function of time t as a parameter.

The ideal derivative 26 of the ideal function 28 as well as the derivative 24 of the time dependent function 22 are shown in FIGS. 4d, 4f and 4h, respectively. That is, the derivative of the current intensity (I') according to time (t) is shown in FIG. 4D. The derivative of the electrical resistance R′ as a function of time t is shown in FIG. 4f. The derivative of voltage U' as a function of time t is shown in FIG. 4H.

Figure 5 shows an enlarged view of the diagram of Figure 4h. It can be seen that the starting value 30 of the derivative 24 differs significantly from the ideal starting value 32 of the ideal derivative 26. Here, the presence or absence of the carrier mass flow 16 can be inferred from the comparison of the two starting values 30 and 32 . Here, the starting value 30 is greater than the ideal starting value 32 .

Further, from each of the derivatives 24 and 26 the time required to reach the predetermined threshold 36 can be determined. That is, the threshold 36 is reached after a period 34 for the derivative 24 . In the case of an ideal derivative (26), the threshold (36) is reached after an ideal period (38). Here, the presence or absence of carrier mass flow 16 can be inferred from the comparison of the two periods 34, 38. The period 34 here is longer than the ideal period 38 .

Claims (10)

A method for heating a motor vehicle exhaust gas system (10) having a catalytic converter (12), said exhaust gas system (10) in the direction of flow of a carrier mass stream (16) in said exhaust gas system (10) a catalytic converter and an electrically heated heating disk (14) disposed upstream of (12), the method comprising the following steps:
calculating values of one or more electrical parameters during heating of the electrically heated heating disk (14), in particular at regular, time intervals;
determining whether a sufficiently large carrier mass flow (16) is present by evaluating a calculated value of one or more electrical parameters of an electrically heated heating disk (14). Heating of the exhaust gas system according to claim 1, characterized in that the carrier mass flow (16) in the exhaust gas system (10) is provided by a secondary air pump (18) or an electric exhaust gas turbocharger (20). method. 3. The method according to claim 1 or 2, characterized in that at least one electrical parameter of the electrically heated heating disk (14) is current strength, electrical resistance, voltage, and/or power of the electrically heated heating disk (14). Heating method of the exhaust gas system. 4. The method according to any one of claims 1 to 3, wherein the evaluation of the calculated value of the one or more electrical parameters:
generating at least one time dependent function (22) from the calculated values of the at least one electrical parameter;
determining and evaluating at least one derivative (24) of a time-dependent function (22) of the calculated value of at least one electrical parameter of the electrically heated heating disk (14); heating method of the system. 5. The method of claim 4, wherein the evaluation of the derivative (24) is:
comparing the profile of the derivative (24) with the profile of the ideal derivative (26) calculated from the ideal function (28) generated from ideal predetermined ideal values. heating method. 6. The method of claim 4 or 5, wherein the evaluation of the derivative (24) is:
A method for heating an exhaust gas system, characterized in that it comprises a step of comparing the starting value (30) of the derivative (24) with the ideal starting value (32) of the ideal derivative (26). 7. The method according to any one of claims 4 to 6, wherein the evaluation of the derivative (24) is:
calculating a period of time (34) required to achieve a predetermined threshold (36) of the derivative (24);
comparing said calculated period (34) with an ideal period (38) required to achieve a predetermined threshold value (36) of an ideal derivative (26); method. A motor vehicle exhaust system (10) comprising at least one catalytic converter (12) and at least one electrically heated heating disk (14),
The exhaust system (10), wherein the exhaust system (10) is configured such that the value of at least one electrical parameter of the electrically heated heating disk (14) can be calculated. 9. The exhaust gas system (10) according to claim 8, characterized in that the exhaust gas system (10) is configured to be heated with the method according to any one of claims 1 to 7. A motor vehicle comprising an exhaust gas system (10) according to claim 8 or 9.