DE102016200718A1 - Method for operating a delivery and metering system for the reducing agent solution of an SCR catalyst - Google Patents

Abstract

In a method for operating a delivery and metering system for the reducing agent solution of an SCR catalyst in a motor vehicle, the delivery and metering system comprises at least one tank (10) for the reducing agent solution, at least one delivery module (20), lines (11, 12, 31 ) and at least one metering module (30). According to the invention, heating of the conveying and dosing system is controlled on the basis of route-based information (80) via a planned motor vehicle route.

Description

The present invention relates to a method for operating a delivery and metering system for the reducing agent solution of an SCR catalytic converter in a motor vehicle and to a computer program, a machine-readable storage medium and an electronic control unit, which are set up to carry out the method.

State of the art

Methods and apparatuses for operating an internal combustion engine, in particular in motor vehicles, are known, in the exhaust gas region of which an SCR catalytic converter (selective catalytic reduction) is provided, which reduces the nitrogen oxides (NOx) contained in the exhaust gas of the internal combustion engine to nitrogen in the presence of a reducing agent. As a result, the proportion of nitrogen oxides in the exhaust gas can be significantly reduced. Ammonia (NH ₃ ) is required for the reaction to proceed. Often, for the provision of ammonia, an aqueous urea solution is used, which is injected into the exhaust line upstream of the SCR catalyst.

For the delivery and metering of the reducing agent solution, ie the aqueous urea solution (eg ^AdBlue® ), a hydraulic delivery and metering system is generally provided which comprises a tank for the reducing agent solution, a delivery pump (delivery module), lines, inter alia a hydraulic supply line , and one or more metering valves (metering module).

At low temperatures, the reducing agent solution freezes. For example, the freezing point of the AdBlue ^® solution is around -11 ° C. There are therefore usually one or more heaters for the delivery and metering provided to thaw at low outdoor temperatures, the solution and enable the system in metering readiness.

Disclosure of the invention

Advantages of the invention

The method according to the invention is based on a method for operating a delivery and metering system for the reducing agent solution of an SCR catalyst in a motor vehicle, wherein the delivery and metering system has at least one tank for the reducing agent solution, at least one delivery module, lines and at least one metering module. Furthermore, one or more means are provided for heating the delivery and metering system, for example, a heater for the tank, one or more heaters for the delivery module, a heater for the metering module, and one or more heaters for the various conduits in the system. According to the invention, heating of the conveying and metering system is controlled on the basis of route-based information about a planned motor vehicle route. In a particularly preferred embodiment of the method according to the invention a superfluous heating of the conveying and metering system and thus a superfluous energy consumption are avoided by the consideration of distance-based information. In summary, according to the invention, route-based information is used in order to optimize and maximize the heating of the conveying and metering system in a distance-dependent and therefore demand-oriented manner, whereby preferably no unnecessary energy is consumed.

By the term "motor vehicle route" is meant the driving cycle between start and destination, for which purpose an input of the planned destination by the vehicle driver via a suitable interface is required before the motor vehicle is set in motion or at the beginning of the journey, for example shortly after Begin.

The inventive method shows its advantages, especially at low outside temperatures. Low temperatures, in particular temperatures below the freezing point of the reducing agent solution used in each case, for example temperatures of -11 ° C. or less, can lead to the freezing of the reducing agent solution, especially if a motor vehicle is parked, for example, overnight. The reducing agent solution can freeze, especially in the supply line, but also in the tank itself. In order to ensure optimum exhaust aftertreatment, the reducing agent must be thawed so that it is available in liquid form and can be injected into the exhaust gas line in a demand-dependent manner. For heating the conveying and metering system for providing liquid reducing agent, corresponding heating devices are usually operated via the on-board battery and / or via the thermal energy of an engine coolant. In particular, the state of charge of the on-board battery can be critical, so that excessive use of the on-board battery leads to problems. Especially at low outside temperatures sufficient battery power is required to allow the starting of the motor vehicle. Against this background, the inventive method is very advantageous because overuse of the on-board battery in particular for the required heating of the delivery and metering system is avoided. Nevertheless, the consideration of distance-based information for the control of the heating of the delivery and metering system ensures that as soon as possible sufficient can be provided liquid Reduktionsmittelösungsmenge, so that after the start of the motor vehicle optimal exhaust aftertreatment via the SCR system can be done as quickly as possible.

A prerequisite for carrying out the method according to the invention is that the motor vehicle driver at the beginning of a driving cycle feeds the planned destination of the driving cycle in a suitable manner in a corresponding system of the motor vehicle so that distance-based information can be determined and taken into account according to the invention. For example, for this purpose, the motor vehicle driver enter the planned destination in a conventional, provided in the vehicle navigation device. By means of this destination input and the vehicle route which can be derived therefrom, various information is determined according to the invention, on the basis of which statements can be made about the anticipated consumption of reducing agent. In a preferred embodiment, it is derived from the distance-based information as to whether the SCR catalytic converter or the SCR catalytic converter system will even be active on the planned route. For example, with a very short driving distance, it may be predictable that the SCR catalyst will not reach the required operating temperature, so that in this case no liquid reductant solution will be required. In this case, heating the delivery and metering system would bring no benefit, so that in this case the heaters are not activated according to the invention, whereby energy, especially battery energy, can be saved.

Furthermore, it can be determined in a preferred manner, taking into account the distance-based information, how much liquid reducing agent, if the SCR catalyst is expected to be active, is expected to be needed. The heating of the delivery and metering system is then carried out only to the extent necessary to provide the expected amount of liquid reductant. In this case, it is also preferably taken into account that electrical heating of the delivery and metering system for the reducing agent is usually necessary only in an initial phase of the driving cycle, since after a certain travel time the general temperature of the motor vehicle is sufficient to thaw the reducing agent solution or into to maintain a liquid state. In this phase, for example, heating via the thermal energy of an engine coolant may also be advantageous.

In carrying out the method according to the invention, after the destination input by the motor vehicle driver on the basis of distance-based information, therefore, the quantity of the reducing agent solution which is likely to be required is first determined. Subsequently, the heating of the conveying and metering system is controlled accordingly, wherein in particular the heating of the conveying and metering system can be stopped when the presumed required amount of the reducing agent is in liquid form.

With the method according to the invention thus a rapid emptying of the on-board battery due to unnecessary electrical heating of the delivery and metering system for the reducing agent solution is prevented. Furthermore, the demand-adapted heating of the delivery and metering system takes into account that the thermal energy quantity of an engine coolant may not be sufficient during driving, especially at low outside temperatures, so that then an electric heating can be requested at least supportive. Overall, by taking into account distance-based information, which preferably also include the outside temperature or the temperature profile of the planned route, the heating of the delivery and metering system are made in a distance-dependent and thus demand-dependent manner, so very quickly a sufficient amount of the liquid reducing agent solution low outside temperatures can be provided. Furthermore, the consumption of superfluous heating energy can be avoided if, for example, in very short distances or city driving, overrun, low engine load or low driving speed, the SCR system can not be activated and therefore a heating of the delivery and metering system is unnecessary.

In a preferred embodiment of the method according to the invention, the route-based information is provided via an external infrastructure, in particular via an internet service, for example via a cloud. Alternatively or additionally, the route-based information can be provided by means of a navigation device which has corresponding digital information, for example digital maps. The use of Internet services is particularly advantageous because it can be considered in a timely manner crucial and critical information about the planned vehicle route, for example, information about current speed limits, line closures, faults or the like.

The route-based information primarily takes into account the distance of the planned route, its duration and, if applicable, the topology of the route. From this, further distance-based information can be derived, in particular the estimated average vehicle speed, the anticipated average engine speed, estimated engine load, estimated exhaust mass flow, and expected exhaust gas temperature profile. For the determination of this information, different calculation models can be used taking into account motor vehicle-specific characteristics in a manner known per se. On the basis of this information, according to the invention, the estimated reduction agent consumption can be calculated and the heating of the delivery and metering system can be controlled accordingly. Temperature and / or weather data can continue to be included in this calculation, for example by taking into account the anticipated ambient temperature profile of the planned route.

Furthermore, it can be taken into account whether it is a city trip, an overland journey or a motorway journey, since this information also influences the expected consumption of the reducing agent. Furthermore, acceleration and deceleration points can be incorporated, since all these points influence the speed, the engine load and the estimated amount of reducing agent dependent thereon. Furthermore, it is also preferably taken into account here how the temperature profile of the motor vehicle during the journey is likely to develop, since this too has an influence on the required heating of the delivery and metering system. For example, for a longer travel time, the heating can be increasingly carried out via the heated coolant from a coolant pump of the engine. Furthermore, the outside temperature can be incorporated, since the development of the outside temperature along the planned route also has an influence on the required heating, as well as a weather profile along the planned route.

In the determination of the distance-based information, for example, digital maps, field monitoring, satellite imagery, aerial images of aircraft or similar route information can be incorporated. Furthermore, other information can be incorporated, for example, by the public (community) fed into appropriate databases, such as information on track closures, speed limits or the like. Generally, in principle, all appropriate information provided via Internet-based services from various sources can be incorporated.

If the route-based information is provided and / or processed via an external infrastructure, for example an internet service, it would be expedient to have a corresponding connectivity of the motor vehicle via a corresponding interface. In this context, for example, so-called IoT services (Internet of Things) can be claimed. This can be done after a corresponding registration with a suitable service data exchange. Taking into account the planned motor vehicle route and possibly taking into account further route-based information provided on the basis of the planned motor vehicle route via an external infrastructure or via digital information in a navigation device, the calculation of the presumably required amount of reducing agent, for example, in the engine control unit. The engine control unit can then schedule and trigger the heating of the delivery and metering system, and thus the thawing of the reductant solution in demand-dependent manner, thus avoiding unnecessary heating and unnecessary thawing of the reductant solution. In this way, excessive stress on the optionally critical battery energy and / or unnecessary consumption of the thermal energy of an engine coolant are avoided. By the savings of energy by avoiding unnecessary heating can be focused on the critical situation in which the heating is urgently needed, so that if necessary sufficient energy is available, if a very fast thawing of reducing agent solution is required.

The invention further comprises a computer program which is set up to carry out the steps of the method according to the invention. Moreover, the invention comprises a machine-readable storage medium, on which such a computer program is stored, and an electronic control unit, which is set up to carry out the steps of the method according to the invention. The embodiment of the method according to the invention as a computer program or as a machine-readable storage medium or as an electronic control unit has the particular advantage that in this way the method according to the invention can readily be used in existing motor vehicles as well, by taking into account route-based information about a planned motor vehicle route avoid unnecessary heating of the SCR system reductant delivery and dosing system.

Further features and advantages of the invention will become apparent from the following description of embodiments in conjunction with the drawings. In this case, the individual features can be implemented individually or in combination with each other.

In the drawing, the figure shows a schematic representation of a delivery and metering system for the reducing agent solution of an SCR catalyst whose heating is controlled according to the invention.

Description of exemplary embodiments

The figure illustrates a delivery and metering system for the reducing agent solution of an SCR catalyst in a motor vehicle, the delivery and metering system comprising a tank 10 for the reducing agent solution, a delivery module 20 and a dosing module (dosing valve) 30 includes. From the tank 10 leads a suction line 11 via a valve 24 to the pump 21 of the conveyor module 20 , About a filter 25 which a pressure sensor 22 is assigned, the liquid reducing agent solution passes through an outlet 26 in a pressure line (supply line) 31 to the metering valve 30 and is in demand-dependent manner in the exhaust line of an internal combustion engine, not shown here 40 injected upstream of an SCR catalyst, not shown here. Furthermore leads from the conveyor module 20 a return line 12 with a throttle 23 back to the tank 10 , The various components of the delivery and dosing system are heatable. For this purpose, various heating devices are provided. In detail, the suction line 11 , the return line 12 , the pump 21 , that of the pump 21 upstream valve 24 , the filter 25 and the outlet 26 and the pressure line 31 and optionally the tank 10 electric heaters 50 be assigned. The heaters 50 are supplied with electrical energy via the on-board battery. Furthermore, a heating via the thermal energy of the coolant of the internal combustion engine 40 provided, wherein the heated coolant by means of a coolant pump 60 over a line 61 to the dosing module 30 is directed. Furthermore, another line 62 provided for the heated coolant, which, controllable via the Tankheizventil 63 , the tank 10 especially in the area of the suction line 11 heated. The heating of the delivery and dosing system is via a control unit 70 controlled, in which case in particular the tank heating valve 63 as well as the various heating facilities 50 be driven (in the figure indicated by several arrows). According to the invention, the control of the various heating devices 50 and the tank heating valve 63 based on distance-based information 80 carried out on the planned motor vehicle route. For this purpose, the motor vehicle driver first enters the planned destination, for example in a conventional navigation device of the motor vehicle. On the basis of this information, it is possible in particular to determine the distance to be traveled and the expected duration of the motor vehicle route. For this purpose, the digital information that is stored in the navigation device, and also information that can be provided via an Internet service, preferably via a cloud, can be used. Based on this various information together with vehicle-specific characteristics, the average vehicle speed, the average engine speed, the expected engine load, the expected exhaust gas mass flow and the expected exhaust gas temperature profile can be determined, whereby the ambient temperature profile of the route can be taken into account. Based on some or all of this information, the expected amount of liquid reductant needed for the planned motor vehicle route may be determined. On this basis, according to the invention, the heating of the delivery and metering system is controlled, so that a possibly unnecessary heating under unnecessary energy consumption, which can go especially at the expense of the on-board battery, is avoided.

This process is especially effective at low outside temperatures, especially at outside temperatures below the freezing point of the reducing agent solution, for example below -11 ° C. The control of the heating devices 50 and 63 takes place via the control unit 70 , wherein in the control unit 70 the various distance-based information and, for example, weather and / or temperature data for the vehicle's location region are processed and converted into corresponding control signals. In particular, the controller may appropriately activate and stop the heating once a sufficient amount of liquid reductant solution has been provided for the current route. This ensures that the SCR catalyst can be operated optimally. Otherwise, the lack of liquid reductant at low outside temperatures would result in poor conversion of nitrogen oxides and increased NOx emissions.

Claims (9)

Method for operating a delivery and metering system for the reducing agent solution of an SCR catalytic converter in a motor vehicle, wherein the delivery and metering system comprises at least one tank ( 10 ) for the reducing agent solution, at least one delivery module ( 20 ), Cables ( 11 . 12 . 31 ) and at least one dosing module ( 30 ), characterized in that heating of the conveying and dosing system on the basis of distance-based information ( 80 ) is controlled via a planned motor vehicle route. A method according to claim 1, characterized in that by the consideration of distance-based information ( 80 ) an unnecessary heating of the delivery and metering system is avoided. A method according to claim 1 or claim 2, characterized in that heating of the conveying and metering system takes place only if from the distance-based information ( 80 ) is deducible that the SCR catalyst will be active. Method according to one of the preceding claims, characterized in that heating of the conveying and metering system takes place only as far as it is for the provision of liquid reducing agent, taking into account the route-based information ( 80 ) is expected to be needed. Method according to one of the preceding claims, characterized in that the distance-based information ( 80 ) via an external infrastructure, in particular an Internet service, preferably a cloud, and / or via digital information in a navigation device. Method according to one of the preceding claims, characterized in that the distance-based information ( 80 ) contain or suggest at least one of the following information relating to the planned motor vehicle route: removal of the motor vehicle route; - Duration of the motor vehicle route; - topology of the motor vehicle route; - average vehicle speed; - average engine speed; - engine load; - exhaust gas mass flow; - exhaust gas temperature profile; - Ambient temperature profile. Computer program adapted to perform the steps of a method according to any one of claims 1 to 6. Machine-readable storage medium on which a computer program according to claim 7 is stored. Electronic control unit ( 70 ) arranged to perform the steps of a method according to any one of claims 1 to 6.

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