DE102018208132A1 - Method for the prospective maintenance of a filter of a conveying and dosing system - Google Patents

Abstract

The invention relates to a method for the prospective maintenance of a filter of a delivery and metering system in an SCR system. The method compares determined data (WDe) on material properties and / or working features of the SCR system with reference data (WDr) which can be retrieved via a radio connection and which contain information about material properties and / or working characteristics of SCR systems under different system conditions ( 105). Based on this comparison (105), the implementation and timing of corrective maintenance of the filter are set (107, 109).

Description

The present invention relates to a method for prospective maintenance of a filter of a delivery and metering system in an SCR system. Furthermore, the invention relates to a computer program that performs each step of the method when it runs on a computing device, and a machine-readable storage medium that stores the computer program. Finally, the invention relates to an electronic control unit which is set up to carry out the method according to the invention at least partially and to a cloud computing unit which is set up to carry out the method according to the invention at least partially.

State of the art

Today, in the after-treatment of exhaust gases of an internal combustion engine, the SCR (Selective Catalytic Reduction) method is used to reduce nitrogen oxides (NOx) in the exhaust gas. The DE 103 46 220 A1 describes the basic principle. In this case a 32.5% strength urea-water solution (HWL), commercially known as AdBlue ^® metered into the exhaust gas. Typically, for this purpose, a delivery and metering system is provided with a metering valve to meter the HWL upstream of an SCR catalyst in the exhaust stream. From the HWL splits off ammonia, which is then bound to the reactive surface of the SCR catalyst. There, the ammonia reacts with the nitrogen oxides, resulting in water and nitrogen. The HWL is conveyed by means of a delivery module with a feed pump from a reducing agent tank through a pressure line to the metering valve. The delivery module builds up pressure and maintains it until the HWL is metered in via the dosing valve.

Usually, a filter at the output of the delivery module is arranged to the pressure line, so that the HWL is transported via the filter to the metering valve. Foreign particles in the HWL, such. As dirt, the metering valve can clog and are harmful to the metering valve, so the metering valve must be protected by the filter from these foreign particles. The filter is used to filter out these foreign particles from the HWL before it flows through the metering valve. In order to achieve a high rate of deposition of the foreign particles, the filter has a large surface area with a filter coating, e.g. B. a special resin coating, which comes into contact with the HWL. By filtering the filter is loaded with the foreign particles. From time to time the filter must be replaced. This usually happens in the course of a workshop service.

From the DE 10 2012 201 595 A1 For example, methods for determining a loading of the filter are known. An already known method provides that the loading of the filter is determined by means of an additional pressure sensor, which measures the pressure upstream of the filter. In the method described, a current measurement of a pump flow of the feed pump is performed and closed from the pump flow to a pressure drop across the filter. From the resulting pressure difference then the loading of the filter can be determined.

Disclosure of the invention

A method is proposed for the prospective maintenance of a filter of a delivery and metering system in an SCR system. The filter is arranged between a dosing module and a delivery module in a pressure line, in particular at the outlet of the delivery module. The delivery module has a delivery pump that delivers reductant solution from a reductant tank via the filter into the dosing module, where it is then metered through a metering valve into an exhaust line of an internal combustion engine. The filter filters foreign particles, especially dirt, from the reducing agent solution so that the metering valve is not blocked by the foreign particles. The captured foreign particles, the filter can clog itself, whereby the reducing agent can not be provided in sufficient form the metering valve available. In addition, the filter is subject to age-related wear, so its effectiveness decreases over time.

Predictive maintenance is the planning of corrective maintenance where the corresponding component is maintained or replaced, based on determined data indicating the current state of the component, and reference data representing the wear of the component or a comparison component , in front. This reduces unexpected downtime during operation. For this purpose, data on material characteristics and / or working characteristics of the SCR system are compared with reference data, which contain information about material properties and / or working characteristics of SCR systems under different system conditions. The determined data are current data of the SCR system, which allow statements about a wear and / or a clogging of the filter. They can be measured and evaluated and stored by an electronic control unit. Examples of preferred sources from which the data obtained are presented below. The reference data can be called up via a radio link, preferably via a wireless Internet connection, at least for comparison. For this purpose, the reference data has been acquired in advance and stored on a cloud computing unit. In addition, the reference data can also be cached, for example, in an electronic control unit and retrieved for comparison.

Based on this comparison, the implementation and timing of the corrective maintenance of the filter are set. The comparison itself can be performed either by the electronic control unit or by the cloud computing unit. Also a combined calculation for the comparison is possible. Based on the prospective maintenance of the filter, the corrective maintenance of the filter can be planned. This offers the advantage that fewer and shorter workshop stays are possible. Other benefits include increased filter life, increased failure safety of the SCR system, fewer accidents with negative environmental effects, and an optimal handling of spare parts that can be accurately delivered to corrective maintenance.

In the event that at least a portion of the determined data is above a threshold determined from the reference data, one aspect provides that corrective maintenance be fixed before the filter and / or the SCR system is predicted to be non-functional or failed , As a result, the maintenance or replacement of the filter can be scheduled to take place before the SCR system's operation is compromised or even failed.

If the at least part of the determined data is not above the threshold, the corrective maintenance of the filter, i. H. the maintenance or the replacement, purely in principle in a conventional manner at a time specified by a service interval time are performed. Advantageously, in this case, in which the at least one part of the determined data lies below or corresponds to a threshold determined from the reference data, the corrective maintenance of the filter, which is provided within the predetermined service interval, is postponed to a later point in time. Since the filter in this case is considered to be functional, can be dispensed with the maintenance and replacement of the filter. This prolongs the intervals between corrective maintenance based on prospective maintenance.

• - Eine insgesamt eindosierte Reduktionsmittelmasse, welche basierend auf einem an die Förderpumpe, genauer an eine Steuerung für den Pumpenmotor, angelegten Tastverhältnis über die Zeit ermittelt wird;
• - die Betriebstemperatur des Fördermoduls;
• - einem Verlauf des Drucks stromabwärts des Filters, insbesondere dessen Historie und darin vorkommende Druckspitzen;
• - die Anzahl der Systemstarts;
• - eine Zeit, die zum Druckaufbau während des Starts benötig wird;
• - die Betriebsstunden des SCR-Systems;
• - ein Tastverhältnis der Förderpumpe, wenn keine oder eine bekannte konstante Reduktionsmittellösung eindosiert wird.

For the two abovementioned cases, the same threshold is preferably used, which therefore only has to be determined once from the reference data. Preferably, this threshold represents a wear and / or blockage just not functional filter of the delivery and metering. The threshold can then be calculated from system parameters which characterize the wear and / or blockage of the filter. With this threshold, a precise distinction between a functional filter and a defective filter can be made. Such system parameters are for example:

• - A total metered reducing agent mass, which is determined based on a voltage applied to the feed pump, more precisely to a controller for the pump motor duty cycle over time;
• the operating temperature of the conveyor module;
• a course of the pressure downstream of the filter, in particular its history and pressure peaks occurring therein;
• - the number of system starts;
• a time required to build up the pressure during the start;
• - the operating hours of the SCR system;
• - A duty cycle of the feed pump, if no or a known constant reducing agent solution is metered.

• - einer Pumpgeschwindigkeit der Förderpumpe des Förder- und Dosiersystems, mit der die Reduktionsmittellösung durch den Filter zum Dosierventil gepumpt wird;
• - ein Druckniveau stromabwärts des Filter;
• - eine Zeit bis zum Erreichen eines bestimmten Druckniveaus stromabwärts des Filters;
• - einem gesamten Stromverbrauch des Förder- und Dosiersystems zum Erreichen des bestimmten Druckniveaus stromabwärts des Filters;
• - Parameter zur Erregung des Förder- und Dosiersystems, wie zum Beispiel ein Pumpenstrom zur Erregung der Förderpumpe.

The data obtained is preferably from one or more of the following sources:

• a pumping speed of the delivery pump of the delivery and metering system with which the reducing agent solution is pumped through the filter to the metering valve;
• a pressure level downstream of the filter;
• a time to reach a certain pressure level downstream of the filter;
• a total power consumption of the delivery and metering system to reach the determined pressure level downstream of the filter;
• - Parameters for the excitation of the delivery and dosing, such as a pump current to excite the feed pump.

As already described, the feed pump delivers the reductant solution through the filter to the pressure valve. Accordingly, the pressure downstream of the filter is an indication of the wear and / or blockage of the filter. The pressure can be measured by a pressure sensor downstream of the filter. Alternatively, it can be concluded from the current measurement of the pump flow of the feed pump to a pressure drop, which in turn is an indication of the wear and / or the blockage of the filter. The determined data can thus be measured directly or determined indirectly from measured values or from adjusted parameters. The determined data can be detected and processed mainly by the electronic control unit and be stored by this.

The following describes how the reference data can be obtained: The reference data can refer to records of previous maintenance. The records may refer to the SCR system used or refer to a comparison system. It is also possible to supplement the records relating to the comparison system by the currently used system. The records have information about the physical characteristics and / or working characteristics of the SCR system used and / or comparison systems under different system conditions, and may in particular include the condition of the filter during maintenance and / or replacement. The recordings are stored on the cloud computing unit and can be retrieved from this.

Alternatively or additionally, the reference data can fall back on a model. Here, the physical properties and / or the working characteristics of SCR systems are modeled under different system conditions. The calculations for the model can run on the cloud computing unit. In this case, the model can be improved by the determined data of the system used.

The computer program is set up to perform the method, in particular if it is performed on an electronic control unit or a computing unit, in particular a cloud computing unit. In this case, the computer program can perform part of the steps on the control unit and perform a further part of the steps on the arithmetic unit. For implementation, in particular on the electronic control unit, it is stored on the machine-readable storage medium.

The electronic control unit is set up to at least partially control the prospective maintenance of the filter of the conveying and dosing system by means of the method described above. In this case, the electronic control unit can detect and process above all the determined data. In addition, the electronic control unit can store the determined data on the physical properties and / or the working features of the SCR system.

A cloud computing unit is proposed, which is set up to at least partially control the prospective maintenance of the filter of the conveying and metering system by means of the method described above. In particular, the cloud computing unit can record and process the reference data. In addition, the cloud computing unit can store the reference data, which includes information about material properties and / or working characteristics of SCR systems under different system conditions. Finally, the reference data can preferably be retrieved by the cloud computing unit via a radio connection, in particular a wireless Internet connection.

The electronic control unit and the cloud computing unit can be connected to one another via a radio link, in particular via a wireless Internet connection. About this wireless connection, the electronic control unit can retrieve the reference data from the cloud computing unit. Conversely, the cloud computing unit can retrieve the determined data from the electronic control unit. The comparison of the data can be performed either by the electronic control unit or by the cloud computing unit and then made available via the radio link.

list of figures

• 1 zeigt einen schematischen Aufbau eines SCR-Systems mit einem Filter, bei dem gemäß einer Ausführungsform des erfindungsgemäßen Verfahrens eine prospektive Instandhaltung durchgeführt wird.
• 2 zeigt ein Ablaufdiagramm einer Ausführungsform des erfindungsgemäßen Verfahrens.

Embodiments of the invention are illustrated in the drawings and explained in more detail in the following description.

• 1 shows a schematic structure of an SCR system with a filter in which a prospective maintenance is performed according to an embodiment of the method according to the invention.
• 2 shows a flowchart of an embodiment of the method according to the invention.

Embodiments of the invention

1 shows a schematic structure of an SCR system with a delivery and metering system 1 for an SCR catalyst 2 and an oxidation catalyst 3 for exhaust aftertreatment of an internal combustion engine, not shown, in a motor vehicle. The oxidation catalyst 3 and the SCR catalyst 2 are consecutively in an exhaust system 4 arranged the internal combustion engine and act on the expelled from the engine exhaust gas. The conveying and dosing system 1 has a conveyor module 10 with a feed pump 11 on which a reducing agent solution via a delivery line 13 from a reducing agent tank 12 and via a pressure line 15 to a metering valve 14 promotes. About the metering valve 14 the reductant solution then enters the exhaust line 4 upstream of the SCR catalyst 2 metered. Non-metered reducing agent solution flows through a return line 16 into the reducing agent tank 12 back.

In the pressure line 15 is at the output of the conveyor module 10 a filter 17 arranged, which filters the reducing agent solution while removing foreign particles, in particular dirt, from the reducing agent solution. The filter 17 has a large surface coated with a resin coating and receives the foreign particles through this surface with the filter medium. This increases the loading of the filter 17 , Is the loading of the filter 17 too high, the filter can 17 be clogged by the foreign particles. In addition, the filter is subject 17 age-related wear. Therefore, the filter needs 17 be serviced or replaced from time to time to improve the functionality of the delivery and metering system 1 sure. The filter 17 usually has a heating element, not shown here, which ensures that the reducing agent solution does not freeze or thaw a frozen reducing agent solution faster.

It is intended to provide a pressure drop across the filter 17 to determine to get out of this on the loading of the filter 17 close. In 1 There are two ways to determine the pressure drop. For one, a pressure sensor 50 in the pressure line 15 downstream of the filter 17 be provided, via which the pressure in the pressure line is measured. On the other hand, a power meter 51 the electric current to the feed pump 11 measure up. In known manner, the pressure drop across the filter 17 be determined and finally on the loading of the filter 17 getting closed. The determination of the pressure drop and the load runs on an electronic control unit 6 off, which with the pressure sensor 50 and / or the ammeter 51 connected is. The data collected are from the electronic control unit 6 recorded and stored.

Furthermore, it is a cloud computing unit 7 provided, for example, a computer network that has a wireless Internet connection. The cloud computing unit 7 is set up to store and provide reference data containing information about physical characteristics and / or working characteristics of SCR systems under different system conditions. For a more detailed description of the reference data, refer to the description 2 directed. The electronic control unit 6 is set up, at least the reference data from the cloud computing unit 7 retrieve. This is the electronic control unit 6 with a receiver 61 connected to the reference data via a wireless radio link from the cloud computing unit 7 can receive and to the electronic control unit 6 forwards. In a preferred embodiment, the wireless radio connection is a wireless internet connection in which the electronic control unit 6 through "cloud computing" on the cloud computing unit 7 can access. The receiver 61 may in a further embodiment in the electronic control unit 6 integrated or be a part of this. In addition, the receiver 61 Also be designed as a transceiver, ie as a combination of receiver and transmitter, so that the data obtained to the cloud computing unit 7 can be sent. In yet further embodiments, an additional transmitter is for communicating with the cloud computing unit 7 intended.

• - einer Pumpgeschwindigkeit der Förderpumpe 11 des Fördermoduls 10 des Förder- und Dosiersystems 1, mit der die Reduktionsmittellösung durch den Filter 17 zum Dosierventil 14 gepumpt wird;
• - ein Druckniveau stromabwärts des Filter 17, welches durch den Drucksensor 50 gemessen wird;
• - eine Zeit bis zum Erreichen eines bestimmten Druckniveaus stromabwärts des Filters 17, welches durch den Drucksensor 50 gemessen wird;
• - der gesamte Stromverbrauch des Förder- und Dosiersystems 1, welcher durch das Strommessgerät 51 gemessen wird, zum Erreichen des bestimmten Druckniveaus stromabwärts des Filters, welches durch den Drucksensor 50 gemessen wird;
• - ein Pumpenstrom, der durch das Strommessgerät 51 gemessen wird, zur Erregung der Förderpumpe 11 des Fördermoduls 10.

2 shows a flowchart of an embodiment of the method according to the invention. In a first step 100 currently determined data WDe on physical properties and / or working characteristics of the SCR system, which allow statements about wear and / or clogging of the filter, determined. The determined data WDe originate from one or more of the following sources:

• - A pump speed of the feed pump 11 of the conveyor module 10 of the conveying and dosing system 1 with which the reducing agent solution passes through the filter 17 to the metering valve 14 is pumped;
• a pressure level downstream of the filter 17 , which by the pressure sensor 50 is measured;
• - A time to reach a certain pressure level downstream of the filter 17 , which by the pressure sensor 50 is measured;
• - the total power consumption of the delivery and dosing system 1 which by the ammeter 51 is measured, to reach the certain pressure level downstream of the filter, which by the pressure sensor 50 is measured;
• - A pump current flowing through the flowmeter 51 is measured to excite the feed pump 11 of the conveyor module 10 ,

The first step 100 is through the electronic control unit 6 executed.

• - Eine insgesamt eindosierte Reduktionsmittelmasse, welche basierend auf einem an eine Steuerung für einen Pumpenmotor (nicht dargestellt) der Förderpumpe 11 angelegten Tastverhältnis über die Zeit ermittelt wird;
• - die Betriebstemperatur des Fördermoduls 10;
• - einem Verlauf des Drucks stromabwärts des Filters 17, der durch den Drucksensor 50 gemessen wird, mitsamt dessen Historie und darin vorkommenden Druckspitzen;
• - die Anzahl der Systemstarts;
• - eine Zeit, die zum Druckaufbau während des Starts benötig wird;
• - die Betriebsstunden des SCR-Systems;
• - ein Tastverhältnis der Förderpumpe 11, wenn keine Reduktionsmittellösung eindosiert wird.

From a model 101 and from records of previous maintenance 102 will be in another step 103 Reference data WDr determines what information about physical properties and / or working characteristics of SCR systems in different system conditions. From the reference data WDr is in a further step 104 a threshold S determined. This threshold S represents a filter of the conveying and metering system that is not functional due to wear and / or blockage 1 , For this purpose, the threshold S from system parameters, which is the wear and / or blockage of the filter mark, calculated. These system parameters include:

• - A total metered reducing agent mass, which based on a to a controller for a pump motor (not shown) of the feed pump 11 applied duty cycle over time is determined;
• - The operating temperature of the conveyor module 10 ;
• a course of the pressure downstream of the filter 17 passing through the pressure sensor 50 is measured, together with its history and occurring pressure peaks;
• - the number of system starts;
• a time required to build up the pressure during the start;
• - the operating hours of the SCR system;
• - A duty cycle of the feed pump 11 if no reducing agent solution is metered in.

The steps 103 and 104 as well as the model 101 be on the cloud computing unit 7 executed or calculated. The steps 103 and 104 as well as the model 101 can already be executed in advance, ie before the data obtained WDE in step 100 be determined and the reference data WDr and the threshold S can then be on the cloud computing unit 7 be stored. The records of previous maintenance 102 are also in the cloud computing unit 7 saved and can be updated. In addition, the model can 101 through the determined data WDE be improved. For this purpose, the determined data WDe from the electronic control unit 6 via the wireless radio connection (Internet connection) to the cloud computing unit 7 over ends.

The following steps can be done both on the electronic control unit 6 as well as on the cloud computing unit 7 be executed. It will be a comparison 105 the data determined WDE with the threshold S which is being tested. If at least part of the determined data WDe lies above the threshold S, that is, the wear and / or the blockage of the filter 17 above that for the non-functional SCR catalyst, which is determined by the threshold determined from the reference values WDr S is represented, a corrective maintenance is set 106 regardless of whether the workshop service is in a service interval or not. The corrective maintenance date is set 106 before the filter 17 and / or the SCR system is deemed to be inoperative or failed. During corrective maintenance, the filter is used as part of a workshop service 17 serviced or exchanged.

Returns the comparison 105 in that the determined data WDe lie below the threshold S or correspond to it, the corrective maintenance is not necessarily fixed. Instead, one for the filter 17 considered a predetermined service interval. If in a query 108 In the service interval currently no service, ie no corrective maintenance, for the filter 17 is provided, so no corrective maintenance is performed according to the inventive method 108 , Is according to the query 107 Service with corrective maintenance of the filter in the service interval 17 provided, it is moved according to the inventive method to a later date 109 ,

As already described, the filter 17 usually a heating element. The maintenance of the heating element is independent of the maintenance of the filter 17 carried out. Accordingly, the heating element is assigned its own service interval. If in a query 110 is provided that the service of the heating element is to be performed according to the service interval, a corrective maintenance 106 regardless of the comparison 105 set. Is according to the query 110 Currently no service is provided for the heating element, the comparison 105 executed as described.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been 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.

Cited patent literature

• DE 10346220 A1 [0002]
• DE 102012201595 A1 [0004]

Claims (15)

Method for the prospective maintenance of a filter (17) of a conveying and dosing system (1) in an SCR system, in which determined data (WDe) on material properties and / or working characteristics of the SCR system with reference data (WDr) retrievable via a radio link , which comprise information about material properties and / or working characteristics of SCR systems under different system conditions, are compared (105) and on the basis of this comparison (105) determine the implementation and the time of corrective maintenance of the filter (17) (107, 109 ) become. Method according to Claim 1 characterized in that the corrective maintenance is set (107) before, the filter (17) and / or the SCR system is predicted to be non-functional or failed if at least a portion of the determined data (WDe) is above one of the Reference data (WDr) certain threshold (S) are. Method according to one of Claims 1 or 2 characterized in that the corrective maintenance provided within a predetermined service interval is postponed to a later time (109) if at least part of the determined data (WDe) are below a threshold (S) determined from the reference data (WDr) or this correspond. Method according to one of Claims 2 or 3 Is characterized in that the threshold (S) represents a non-functional due to wear and / or constipation filter of the conveying and metering system (1) and calculated from system parameters which characterize the wear and / or the clogging of the filter (17) (104). Method according to one of the preceding claims, characterized in that the determined data (WDe) comes from one or more of the following sources: - a pumping speed of a feed pump (11) of the conveying and metering system (1); a pressure level downstream of the filter (17); - A time to reach a certain pressure level downstream of the filter (17). - A total power consumption of the delivery and metering system to reach the specific pressure level downstream of the filter (17); - Parameters for the excitation of the conveying and dosing system (1). Method according to one of the preceding claims, characterized in that the reference data (WDr) refer to records of previous maintenance (102). Method according to one of the preceding claims, characterized in that the reference data (WDr) fall back on a model (101). Method according to Claim 7 , characterized in that the model (101) is improved by the determined data (WDr). Method according to one of the preceding claims, characterized in that the radio connection is a wireless Internet connection. Computer program, which is set up, the method according to one of Claims 1 to 9 perform. Machine-readable storage medium on which a computer program is based Claim 10 is stored. Electronic control unit (6), which is adapted to operate by means of a method according to one of Claims 1 to 9 at least partially to control a prospective maintenance of a filter (17) of a conveying and metering system (1). Electronic control unit after Claim 12 , characterized in that determined data (WDr) on physical properties and / or working characteristics of the SCR system on the electronic control unit (6) can be stored. Cloud computing unit (7), which is adapted to operate by means of a method according to one of Claims 1 to 9 at least partially to control a prospective maintenance of a filter (17) of a conveying and metering system (1). Cloud computing unit (7) after Claim 14 , characterized in that reference data, which includes information about physical properties and / or working characteristics of SCR systems under different system conditions, on the cloud computing unit (7) can be stored and retrieved from this.

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