Method for monitoring an exhaust system for excessive temperatures

Abstract

The invention relates to a method for monitoring an exhaust system (100) connected to an exhaust outlet (112) of an internal combustion engine (110) with regard to excessively high temperatures, wherein a current temperature is determined for one or more components (130, 140, 150) of the exhaust system (100), wherein, in the presence of a release criterion relating to one or more current temperature values, at least one countermeasure is introduced and / or carried out, which is selected from a plurality of predetermined countermeasures (G0-G13) in accordance with at least one application criterion (A1-A4).

Description

Technical Field

[0001] The present invention relates to a method for monitoring an exhaust system connected to the exhaust outlet of an internal combustion engine for excessively high temperatures, as well as a computing unit and a computer program for performing the method. Background Technology

[0002] In modern exhaust systems for internal combustion engines, the temperature of individual components can be monitored to ensure that they do not exceed specific limits, thus protecting these components (such as the turbine of a turbocharger) from thermal damage. Summary of the Invention

[0003] According to the present invention, a method for monitoring an exhaust system, as described in the independent claims, is proposed, along with a computing unit and a computer program for performing the method. Advantageous designs are the subject of the dependent claims and the following description.

[0004] This invention relates to an exhaust system connected to the exhaust outlet of an internal combustion engine for monitoring excessively high temperatures, and particularly to preventing such excessively high temperatures. To this end, the current temperature value is calculated for one or more components of the exhaust system. In practice, multiple components are related here. These may include, for example, the catalytic converter (which may also be distinguished as internal and external according to temperature), the kerf, the turbocharger, the flexible pipe (a so-called exhaust decoupling element, typically including a wire mesh), and the λ sensor.

[0005] These current temperature values ​​can be determined or measured, for example, using appropriately arranged sensors (temperature sensors). However, using a temperature model of the exhaust system is also suitable, mapping at least one component of the exhaust system (the temperature value of which should be determined) into the temperature model. Preferably, all components present in the exhaust system, or at least those necessary to generate temperature, are mapped into the temperature model. This model can also be constructed modularly, that is, composed of multiple model modules, and thus can be matched, for example, with other exhaust systems having other components when needed. For example, model modules can be set up for each component individually.

[0006] Based on input parameters such as motor load and motor speed, ignition angle efficiency, and λ value, and if necessary, additional adjustment parameters such as vehicle speed, ambient temperature, or parameters for delayed injection, the current temperature value of a specific component can be determined, and exhaust temperature is usually determined as well. Of course, sensors and models can also be used together, whether for different components or for the same component, to determine more accurate values.

[0007] When there is at least one release criterion relating to the one or more current temperature values, then at least one countermeasure is introduced (e.g., by triggering a controller different from the running controller) and / or executed (e.g., by the running controller itself), selecting the at least one countermeasure from a plurality of predetermined countermeasures according to at least one application criterion.

[0008] For different components in the exhaust system, there are typically temperature limits that should not or cannot be exceeded (during internal combustion engine operation). These temperature limits are, for example, predetermined by the vehicle manufacturer. Each temperature value can now be compared to its corresponding temperature limit, specifically forming a temperature difference. When this temperature difference is now below a specific, predetermined threshold (which is usually predetermined consistently for all components or individually), that is, when the temperature of the component is too close to the limit, then countermeasures can be introduced or implemented (aimed at reducing the temperature of the relevant component or generally in the exhaust system, or at least preventing further temperature increases). In this sense, temperature monitoring is a release criterion (for introducing or implementing countermeasures). Such countermeasures can also be called component protection measures.

[0009] Within the scope of this invention, instead of simply executing a fixed-defined countermeasure when a release criterion exists, one or more countermeasures are selected or implemented based on one or, if necessary, multiple application criteria. Possible countermeasures (from which the desired countermeasure can be selected) can, for example, be stored on the operating controller. Such application criteria can, for example, relate to the current operating point of the internal combustion engine. It is conceivable that, depending on the current load or speed, another countermeasure might be more effective. For example, multiple countermeasures can also be introduced or implemented in parallel; however, time-staggered or graded introduction or implementation can also be considered. This can, for example, be accurately determined in advance.

[0010] Under this interrelationship, it is also appropriate to consider multiple application criteria (i.e., at least one first and one second application criterion). Therefore, at least one first countermeasure can be introduced or executed when the first application criterion exists, and at least one second countermeasure can then be introduced or executed (if necessary, later in time) when the second application criterion exists. When the first application criterion then relates to, for example, the already mentioned current operating point of the internal combustion engine and selects an appropriate countermeasure accordingly, the second application criterion may include the fact that the currently introduced or executed countermeasure is insufficient, for example because the temperature rises further, or that the currently introduced or executed countermeasure has reached its effective limit, for example because the basic adjustment parameters (e.g., maximum possible enrichment) have reached their maximum values.

[0011] Correspondingly, it is also preferable to stop at least one of the imported or executed countermeasures when at least one shutdown criterion exists. Alternatively, at least one first countermeasure among the imported or executed countermeasures can be stopped when at least one first shutdown criterion exists, and then at least one second countermeasure among the imported or executed countermeasures can be stopped when a second shutdown criterion exists. Furthermore, a stop criterion can be used in contrast to a release criterion, stopping all countermeasures when a stop criterion exists (this can ultimately coincide with the final shutdown criterion). The stop criterion can be based on temperature difference, just like the release criterion. For example, it can be considered that the stop criterion is met when the temperature difference is no longer below its corresponding threshold. This threshold need not be consistent with the threshold of the release criterion.

[0012] In general, different levels or stages (in the sense of multiple application criteria or shutdown criteria) that can be successively activated or deactivated can be defined in a simple way, and specific countermeasures can be assigned to different levels or stages respectively. A matrix structure can be defined here, which can or should be determined to be applicable, for example, at the start of project processing. Pre-control and adjustment of adjustment parameters can be performed in parallel, and when this adjustment parameter reaches a defined limit, the next stage is controlled. Different component protection measures are performed hierarchically, so that these component protection measures do not affect each other.

[0013] The predetermined countermeasures can be of different types. For example, countermeasures that control or regulate by adjusting parameters can be predetermined, but countermeasures that are introduced or executed by trigger signals (triggers) can also be predetermined. In countermeasures with adjusting parameters, pre-control and / or regulation can be performed, depending on the type. Possible countermeasures are preferably as follows: injecting water into the cylinders of the internal combustion engine; reducing the cylinder fill of the internal combustion engine; enriching the air-fuel mixture in the cylinders of the internal combustion engine; leaning the air-fuel mixture in the cylinders of the internal combustion engine; controlling external exhaust gas recirculation; adapting the shift strategy of the automatic transmission; controlling external cooling devices (e.g., opening the cooler louvers or switching to other motor base parameter sets, in which case the temperature in the exhaust system is optimized).

[0014] A particular advantage of the proposed approach is that the countermeasures or component protection measures can be considered coordinated to some extent. New and, for example, existing measures to protect components in the exhaust system from overheating (e.g., by water spraying, by reducing filler, by hardware measures, by software measures, or other measures for component thermal protection) can be quickly and clearly integrated into the programmstand and activated. Another advantage is the free priority and determination of active countermeasures for component thermal protection when backup measures (i.e., other or additional countermeasures) are ineffective, more precisely, particularly independent of the program level.

[0015] The computing unit according to the invention, such as a controller for a motor vehicle, is particularly configured in terms of programming technology to execute the method according to the invention.

[0016] It is also advantageous to operate the method of the present invention in the form of a computer program for performing all the method steps or a computer program product with program code, because this results in particularly low costs, especially when the running controller is also used for other tasks and is therefore always present. Suitable data carriers for providing the computer program are, in particular, magnetic, optical, and electrical memories, such as hard disks, flash memory, EEPROM, DVDs, etc. Downloading the program via computer networks (Internet, local area networks, etc.) is also possible.

[0017] Further advantages and design solutions of the present invention are derived from the specification and drawings. Attached Figure Description

[0018] The present invention is schematically illustrated in the accompanying drawings by means of embodiments and is described below with reference to the drawings: Figure 1 An exhaust system for an internal combustion engine is schematically shown, in which the method according to the invention can be performed; Figure 2 The illustrations schematically show countermeasures that can be considered within the scope of the method according to the invention; Figure 3 The flow of the method according to the invention in a preferred embodiment is illustrated schematically. Detailed Implementation

[0019] exist Figure 1 The diagram schematically illustrates an exhaust system 100 for an internal combustion engine 110, in which the method according to the invention can be performed. This can be done, for example, on a computing unit 170 configured as a motor controller. The internal combustion engine 110 has, for example, four cylinders 111, which are connected to exhaust outlets 112 and, for example, to a turbocharger 130 via a suitable piping system 120.

[0020] The turbocharger 130 is connected to the catalytic converter 140 via a suitable piping system 120. The catalytic converter 140 is, for example, divided into three sections or segments 141, 142, and 143. Furthermore, a particulate filter 150 is connected to the catalytic converter 140 via a suitable piping system 120. The particulate filter 150 is also, for example, divided into three sections or segments 151, 152, and 153.

[0021] For different components in the exhaust system 100, or for specific parts or locations therein, the corresponding temperatures are now advantageously shown, and when the temperature values ​​of the components in the exhaust system should be determined, the corresponding temperatures can be taken into account in the corresponding temperature model.

[0022] A temperature model specifically for the exhaust system 100, capable of real-time operation, can be modularly adapted to the corresponding configuration of the system and the corresponding components contained within it. (The temperature at the outlet of the internal combustion engine is mentioned.) For this reason, people would assume, for example, that this temperature depends on the ignition angle efficiency and the λ value, but if necessary, it also depends on other adjustment parameters such as idling speed or delayed injection parameters, but these are not mentioned here for the sake of simplicity.

[0023] If the motor outlet temperature is known, the inlet temperature of the first component in the exhaust system (such as the turbocharger) can be calculated using a pipe temperature model, which is essentially dependent on the motor outlet temperature. Ambient temperature, vehicle speed, and exhaust mass flow rate.

[0024] Calculate the turbine outlet temperature or turbocharger outlet temperature. For example, it can be assumed that this temperature depends on the turbine inlet temperature and the pressure ratio on the turbocharger or its turbine.

[0025] The catalyst can be divided into multiple sections or segments according to its length, depending on its structure. The average temperature can then be calculated, for example, for each segment. Figure 1 The example shown calculates the average temperature, for example, in the middle and rear segments. and .

[0026] If the temperature in the section downstream of the catalyst is known, then the input temperature for another catalyst or, as in the example shown, a particulate filter can also be calculated using another pipe temperature model. The temperature for the second catalyst or particulate filter can be calculated similarly to that for the first catalyst. For this purpose, these components are again divided into multiple sections (e.g., three sections) according to length. However, for example, to determine the output temperature of the second catalyst or particulate filter... A temperature sensor 160 is also provided (this temperature sensor can be located, for example, at the input and / or output of the particulate filter).

[0027] Therefore, the temperature values ​​for one or more components in the exhaust system 100 can be determined using the explained temperature model and / or by using a suitable temperature sensor. Based on this, suitable countermeasures can then be introduced or implemented within the scope of the invention, as should be explained in more detail below.

[0028] exist Figure 2 Therefore, a series of countermeasures or component protection measures that can be considered within the scope of the invention are first schematically shown. This can be accomplished, for example, in the form of matrix 200 shown herein, which is stored on the running computing unit as a vector matrix in the form of a bitmask, a table, or a synthesis characteristic curve or the like.

[0029] For example, fourteen strategies G0 to G13 are shown (or at least the storage space allocated for this on the computing unit), which are categorized according to their type as strategies that are controlled or adjusted by means of adjusting parameters (ratios). (Note) and this countermeasure (using) that is introduced or executed by means of a trigger signal (trigger) (Note). The countermeasures are advantageously configured with four different levels (grades) L0 to L3, which can be turned on or off again depending on the application criteria. This matrix can be applied, for example, to specific operating conditions of an internal combustion engine, or other matrices can be set up for other operating conditions. This should also be referred to below. Figure 3 To explain in more detail.

[0030] In matrix 200, a 1 represents the allocation of a game to a level, and the remaining cells are represented by 0. It should be noted that some games are not even assigned to levels, for example, because these games are not necessary or suitable for the operating conditions to which this matrix applies; there is also unused storage space containing no games. Through this matrix 200, the priority and order of games can be ultimately determined.

[0031] For example, the following strategies should be used to occupy storage space G0 to G13: G0: Mixture buildup, briefly used to intercept temperature peaks during ignition angle delay adjustment (can be performed in parallel with other countermeasures). G1: Temperature drop caused by mixture accumulation (accompanied by pre-control of the operating point and λ pre-determined). G2: Exhaust temperature is regulated by enriching the exhaust gas (λ value is used as an adjustment parameter depending on the exhaust temperature of the component to be protected). G3: Not occupied G4: Leaning out in the case of CNG (compressed natural gas, natural gas) (Abmagern) G5: Water spraying (accompanied by pre-control and pre-planning of the amount of water to be sprayed depending on the operating point) G6: Exhaust temperature is adjusted by spraying water (the amount of water used as an adjustment parameter depends on the exhaust temperature of the component to be protected). G7: First stage: Adjusting the exhaust temperature by reducing the filling to a usable threshold. G8: Second stage (smaller value than the first stage in G7) by reducing the exhaust temperature adjustment to a usable threshold. G9: Temperature regulation by reducing exhaust gas temperature exceeding the pre-controlled and adjusted absolute value. G10: Controls external exhaust recirculation G11: Control measures that rely on software (such as shift strategies in automatic transmissions, which can be accomplished, for example, by using a set of parameters that depend on exhaust temperature). G12: Control measures using hardware (such as cooler louvers, water flow regulation via cooled bends). G13: Not occupied.

[0032] Now Figure 3 The diagram schematically illustrates the flow of the method according to the invention in a preferred embodiment, where the countermeasures just explained are appropriately selected, introduced, or executed. Temperature T is plotted for this purpose over time t. The temperature can be the exhaust temperature at the location of the component to be protected or directly the temperature of the component (e.g., the catalytic converter). The temperature change curves shown are illustrated. Here Figure 3 The example illustrates the temperature value or temperature change curve over time for a specific component in the exhaust system that needs to be prevented from overheating. This refers to the maximum permissible temperature of this component, i.e., the temperature limit.

[0033] Once the temperature of the component exceeds the value That is, when the temperature difference Exceeding a specific threshold At that time, the level L0 of the countermeasure is activated according to the first application standard A1, which means that the import or execution is carried out according to... Figure 2 Or matrix 200 is configured with countermeasures for level L0. These are currently countermeasures G0, G5, and G6. For countermeasures that operate based on adjustments to the exhaust temperature or material temperature of the component at the location of the component to be protected, T3 is used to establish a maximum permissible temperature. Regulation difference .

[0034] As can be seen, if the temperature of the component rises further in the example, and a second application criterion A2 is present, the level of countermeasure L1 (in addition to L0) is activated; that is, countermeasure G7 is additionally imported or executed. Application criterion A2 may include, for example, that the countermeasure at level L0 is not effective enough or has reached its limit with respect to the adjustment parameters.

[0035] If the temperature continues to rise, then if another application standard A3 exists, the level of the countermeasure L2 is activated (in addition to L0 and L1), that is, the additional countermeasure G2 is introduced or executed. If the temperature continues to rise, then if another application standard A4 exists, the level of the countermeasure L3 is activated (in addition to L0, L1 and L2), that is, the additional countermeasure G8 is introduced or executed.

[0036] As can be seen, the temperature decreases before reaching the temperature limit. Then, level L3 can be disabled again when the first shutdown criterion B1 is present; that is, the stop criterion G8 is activated. Correspondingly, level L2 is disabled when shutdown criterion B2 is present, and level L1 is disabled when shutdown criterion B3 is present. Finally, level L0 can be disabled when shutdown criterion B4, which also coincides with the stop criterion (i.e., below the threshold T1), is present.

Claims

1. A method for monitoring excessively high temperatures in an exhaust system (100) connected to the exhaust outlet (112) of an internal combustion engine (110). in, Calculate the current temperature (T) for one or more components (130, 140, 150) of the exhaust system (100). ist ), Wherein, when there is a release criterion involving one or more current temperature values, at least one countermeasure is introduced and / or executed, the countermeasure being selected from a plurality of predetermined countermeasures (G0-G13) based on at least one application criterion (A1-A4) involving the current operating point of the internal combustion engine (110).

2. The method according to claim 1, wherein, When a first application standard exists, at least one first countermeasure is imported or executed, and when a second application standard exists, at least one second countermeasure is imported or executed.

3. The method according to claim 1 or 2, wherein, If at least one shutdown criterion (B1-B4) exists, stop at least one of the imported or executed countermeasures.

4. The method according to claim 3, wherein, When a first shutdown criterion exists, at least one of the imported or executed countermeasures is stopped, and when a second shutdown criterion exists, at least one of the imported or executed countermeasures is stopped.

5. The method according to claim 1 or 2, wherein, The multiple predetermined countermeasures (G0-G13) include at least one countermeasure controlled or adjusted by means of adjusting parameters, and / or wherein the multiple predetermined countermeasures include at least one countermeasure introduced or executed by means of a trigger signal.

6. The method according to claim 1 or 2, wherein, Several predetermined countermeasures (G0-G13) are selected from: injecting water into the cylinders of the internal combustion engine or injecting water into the air intake pipe of the internal combustion engine; reducing the cylinder fill of the internal combustion engine; enriching the air-fuel mixture in the cylinders of the internal combustion engine; enriching the air-fuel mixture in the cylinders of the internal combustion engine; controlling external exhaust gas recirculation; adapting the shifting strategy of the automatic transmission; and controlling external cooling devices.

7. The method according to claim 1 or 2, wherein, Using sensor (160), determine the current value (T) of the temperature of at least one component of the exhaust system (100). ist ).

8. The method according to claim 1 or 2, wherein, Using the temperature model of the exhaust system, determine the current value (T) of the temperature of at least one component of the exhaust system (100). ist ), mapping at least one component of the exhaust system in the temperature model.

9. The method according to claim 1 or 2, wherein, The release criteria include one or more current temperature values ​​and their respective predetermined temperature limits (T). max The temperature difference (ΔT) is lower than the threshold (ΔT).

10. The method according to claim 1 or 2, wherein, One or more components (130, 140, 150) of the exhaust system are selected from: catalytic converter, bend, turbocharger, flexible pipe and λ sensor.

11. A computing unit (170) configured to perform all method steps of the method according to any one of the preceding claims.

12. A computer program product having program code that, when run on a computing unit (170), causes the computing unit (170) to perform all the method steps of the method according to any one of claims 1 to 10.

13. A machine-readable storage medium having a computer program stored thereon, which, when run on a computing unit (170), causes the computing unit (170) to perform all the method steps of the method according to any one of claims 1 to 10.

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