DE112013004168B4 - SCR system and method for reliably determining whether a reductant circulating pump is safe to start - Google Patents

Abstract

Method relating to an SCR system provided with a circulating pump (230) and a dosing unit (250), in order not only to assess the need to heat a reducing agent present in a container (205) for exhaust gas purification by means of a heating medium circulating through the container (205). , but also to assess whether a start-up of the circulation of the reducing agent in the SCR system in response to such heating is appropriate, the method comprising the following steps:- determining whether the reducing agent present in the container (205). is at least partially frozen, and if that is the case,- continuously determining (s410) a temperature (T1) of the reducing agent in the container (205), characterized by the following steps:- continuously determining (s420) a difference between a temperature of the heating medium and the temperature (T1) of the reducing agent in the container (205), or- continuously determining (s420) a difference between the temperature (T2) of the heating medium upstream of the container (205) and a temperature (T3) of the heating medium downstream of the container ( 205); and- continuously determining (s440) an accumulated amount of molten reductant based on the temperature difference as a basis for determining the adequacy of the start-up.

Description

TECHNICAL AREA

The present invention relates to a method relating to an SCR system. The invention also relates to a computer program product with a program code for a computer for implementing a method according to the invention. The invention also relates to an SCR system and a motor vehicle equipped with the SCR system.

BACKGROUND

For example, vehicles today use urea (uric acid) as a reductant in SCR systems, which include an SCR catalyst in which the reductant and _NOx gas can react with each other and be converted to nitrogen gas and water. Different types of reducing agents can be used in SCR systems. These reducing agents have different freezing points. AdBlue is an example of a commonly used reducing agent.

One type of SCR system includes a canister that holds a reductant. The system also includes a pump arranged to draw the reductant from the canister via a suction hose and direct it via a pressurized hose to a metering unit located adjacent an exhaust system of the vehicle. The dosing unit is arranged to inject a necessary amount of reducing agent into the exhaust system upstream of the SCR catalytic converter according to operating routines stored in a control unit of the vehicle.

The reducing agent may have a freezing point within a range of -10 to -15 degrees Celsius. Various reducing agents have specific freezing points that depend, among other things, on their material composition. For example, AdBlue has a freezing point of around -12 degrees Celsius. This means that if an ambient temperature is below freezing for a period of time, the reductant in the canister and other parts of the SCR system will freeze.

Current emissions regulations require certain vehicles equipped with an SCR system to run normally within a specified time after the vehicle is started. The predetermined time may be 70 minutes in one example. This means that frozen reductant must be at least partially melted in order to be able to circulate in the SCR system before dosing starts within the period.

A known way of assessing whether it is appropriate to start up a circulating pump and start dosing the reductant is to use a temperature sensor positioned in the tank to measure an actual temperature of the reductant. This makes it possible to determine with a certain degree of probability whether or not the reducing agent in the container has thawed. A disadvantage of the method is that temperature measurements do not always provide a basis for a correct assessment, e.g. depending on where the sensor is mounted, the configuration of e.g. a suction hose and the configuration and size of the container. This means that relatively large safety margins are necessary to avoid starting a circulating pump of the SCR system too early. If the circulation pump is started up too early, when an insufficient amount of reducing agent has thawed, there is a risk that the pump will "suck dry", with a number of possible undesirable effects, e.g. air ingress into the SCR system, which will significantly affect the performance of the system could affect. Actual continuous thawing of frozen reductant is also prevented.

In certain cases where frozen reducing agent in the container is thawed by, for example, a circulating heating medium and the circulating pump sucks dry, a situation may arise that frozen reducing agent in the container cannot be further thawed by the circulating heating medium. This can have particularly serious consequences in cases where applicable legal requirements regarding vehicle emissions cannot be met within the required time. There is also a risk of permanent damage or severe wear to the pump if started too soon.

The U.S. 8,011,176 B2 describes a method for thawing frozen urea in an SCR system using a heater. It also states that the heater will turn off after a certain period of time when it is deemed to have operated long enough for the urea to have melted. A disadvantage of this method is that relatively large safety margins are necessary, which means that the operation of a pump and the dosing of a reducing agent can only be initiated at a relatively late point in time.

The U.S. 2010/0 095 653 A1 describes a method for thawing frozen urea, whereby the dosing system is activated when the urea has reached a certain temperature.

Also describes the WO 2010/148 237 A2 a device for controlling the temperature of a reducing agent in a reducing agent tank. For this purpose, coolant from the internal combustion engine is conducted at a determined flow rate through lines which run in a spiral shape inside the reducing agent tank. Determining the flow rate includes calculating a heat exchange factor between the reductant and the coolant, the calculation depending on whether the reductant is at a temperature above or below its freezing point. A temperature sensor is provided in the reducing agent tank to determine the temperature of the reducing agent.

The DE 11 2004 002 530 T5 describes a reductant heating arrangement in which recirculated fuel is used as a heat source for heating the reductant to a temperature above its freezing point.

SUMMARY OF THE INVENTION

Therefore, there is a need to reliably assess whether a circulating pump of an SCR system in which reductant is frozen can be started without applying too large safety margins to avoid the undesirable effects of the pump being forced to suck dry .

An aim of the present invention is to propose a new and advantageous method relative to an SCR system.

Another object of the invention is to propose a new and advantageous SCR system and a new and advantageous computer program related to an SCR system.

Another object of the invention is to propose a method relating to an SCR system, an SCR system and a computer program for achieving a faster start-up of an SCR system of a motor vehicle in cases where a reducing agent for exhaust gas purification is at least partially frozen.

Another object of the invention is to propose a method related to an SCR system, an SCR system and a computer program for achieving reliable operation of an SCR system of a motor vehicle.

Another object of the invention is to propose a method related to an SCR system, an SCR system and a computer program for improving the performance of a motor vehicle.

An aim of the invention is to propose an SCR system, whereby the dosing of a reducing agent, for example urea in the form of AdBlue, can be started faster in a situation where the reducing agent is initially at least partially in a frozen state.

An aim of the invention is to propose an SCR system, whereby the circulation of a reducing agent, for example urea in the form of AdBlue, can be started faster in a situation where the reducing agent is initially at least partially in a frozen state.

These goals are achieved with a method relating to an SCR system according to claim 1.

• - Bestimmen, ob das in dem Behälter vorhandene Reduktionsmittel wenigstens teilweise gefroren ist, und, wenn das der Fall ist,
• - kontinuierliches Bestimmen einer Temperatur des Reduktionsmittels im Behälter;
• - kontinuierliches Bestimmen einer Differenz zwischen einer Temperatur des Erwärmungsmediums und der Temperatur des Reduktionsmittels im Behälter, oder
• - kontinuierliches Bestimmen einer Differenz zwischen der Temperatur des Erwärmungsmediums stromaufwärts des Behälters und einer Temperatur des Erwärmungsmediums stromabwärts des Behälters; und
• - kontinuierliches Bestimmen einer angehäuften Menge geschmolzenen Reduktionsmittels basierend auf der Temperaturdifferenz, als Basis für die Bestimmung der Angemessenheit des Anfahrens.

An aspect of the invention proposes a method related to an SCR system provided with a circulating pump and a metering unit, not only for assessing the need for heating the reducing agent for exhaust gas purification present in a canister by means of a heating medium, circulating through the canister, but also to determine whether starting up circulation of reductant in the SCR system in response to heating is appropriate. The procedure includes the following steps:

• - determining whether the reducing agent present in the container is at least partially frozen and, if so,
• - continuously determining a temperature of the reducing agent in the container;
• - continuously determining a difference between a temperature of the heating medium and the temperature of the reducing agent in the container, or
• - continuously determining a difference between the temperature of the heating medium upstream of the container and a temperature of the heating medium downstream of the container; and
• - continuously determining an accumulated amount of molten reductant based on the temperature difference as a basis for determining the adequacy of the start-up.

One version continuously integrates an estimated heat transfer from the circulating heating medium to the reductant over time to determine a quantity of molten reducing agent in the vessel. It is thus possible for the circulating pump to be started when a sufficient first quantity of a reducing agent has thawed, instead of having to wait until a temperature of the reducing agent in the container has risen above a certain limit value. It is thus possible for the dosing of the reducing agent to be started when a sufficient second quantity of a reducing agent has thawed, instead of having to wait until a temperature of the reducing agent in the container has risen above a certain limit value.

• - kontinuierliches Bestimmen einer angehäuften Menge an Energie, die auf das Reduktionsmittel basierend auf der Temperaturdifferenz während des Erwärmens übertragen wird. Das Ergebnis ist ein verbessertes Verfahren bezüglich eines SCR-Systems, wobei eine adäquate Schätzung der Menge an übertragener Energie als Basis für die schnellstmögliche Bestimmung dient, ob das SCR-System sicher und mit minimalem Schaden an den Bauteilen angefahren werden kann.

The method may further include the step of:

• - continuously determining an accumulated amount of energy transferred to the reducing agent based on the temperature difference during heating. The result is an improved approach to an SCR system, wherein an adequate estimate of the amount of energy transferred serves as a basis for determining as quickly as possible whether the SCR system can be started safely and with minimal damage to the components.

• - Bestimmen der angehäuften Menge an geschmolzenem Reduktionsmittel basierend auf der angehäuften Menge an übertragener Energie und der Schmelzenthalpie des Reduktionsmittels. Das Ergebnis ist ein Verfahren, das einfach und rechnerisch nicht arbeitsaufwändig ist, um akkurat die angehäufte Menge an geschmolzenem Reduktionsmittel zu berechnen. Die Schmelzenthalpie von zugeführten Reduktionsmitteln ist bereits bekannt. Ein Bestimmen durch akkurates Abbilden der Menge an im Behälter vorhandenem aufgetautem Reduktionsmittel ermöglicht, gemäß der Erfindung, ein früheres Anfahren der Umlaufpumpe und Dosieren des Reduktionsmittels als mithilfe von Techniken, bei welchen die Pumpe, nach einer vorgegebenen Zeit oder wenn eine vorgegebene Temperatur des Reduktionsmittels erreicht wird, angefahren wird.

The method may further include the step of:

• - determining the accumulated amount of melted reductant based on the accumulated amount of transferred energy and the enthalpy of fusion of the reductant. The result is a method that is simple and computationally inexpensive to accurately calculate the accumulated amount of molten reductant. The enthalpy of fusion of the reducing agents supplied is already known. Determining by accurately mapping the amount of thawed reductant present in the tank allows, according to the invention, earlier start-up of the circulating pump and dosing of the reductant than using techniques in which the pump, after a predetermined time or when a predetermined temperature of the reductant reaches is approached.

The present invention proposes a method in which the circulation of reducing agent and its subsequent dosing can take place even if all the reducing agent in the tank has not been thawed. According to the invention, it is only necessary to thaw predetermined respective first and second quantities of reducing agent in order to activate the pump and the dosing of the reducing agent via the dosing unit in a reliable manner.

The start-up of the circulating pump may be deemed appropriate when a certain accumulated amount of reductant is determined. The accumulated amount may be an appropriate amount, which may be determined based on, for example, the size of the canister, the amount of remaining reductant, and the configuration of the SCR system. It can be 5 liters, for example.

• - Starten des Dosierens des Reduktionsmittels bei einer bestimmten angehäuften Menge an geschmolzenem Reduktionsmittel. Die angehäufte Menge kann eine geeignete Menge sein, die beispielsweise auf Basis der Größe des Behälters, der Menge an übrigem Reduktionsmittel und der Konfiguration des SCR-Systems bestimmt werden kann. Sie kann beispielsweise 15 Liter betragen.

The method may further include the step of:

• - Starting the dosing of the reducing agent at a certain accumulated amount of melted reducing agent. The accumulated amount may be an appropriate amount, which may be determined based on, for example, the size of the canister, the amount of remaining reductant, and the configuration of the SCR system. It can be 15 liters, for example.

An advantage of the innovative method is that a faster process for thawing at least partially frozen reducing agent present in the container is achieved by the possibility that the circulation pump is started at a relatively early stage. The use of heating elements while circulating the reductant in the SCR system enables a faster thawing process to be achieved. In an alternative version, a circulating heating medium can be used to heat the reductant in different parts of the SCR system outside of the canister.

Beginning the circulation of a sufficient amount of molten reductant in the SCR system's canister as soon as possible, without metering it into the vehicle's exhaust gases, allows a heating effect of other vehicle components, e.g. a muffler, adjacent to the SCR system to melt the reductant in the canister is used.

An advantageous synergistic effect from the use of heating elements outside the container in connection with a said heating medium in the container is that a faster thawing of the reducing agent in the container is achieved as a result of greater movement in the container due to a flow of the reducing agent during a phase in which it is inside of the SCR system, and in particular in the tank, without being metered into the exhaust gas stream.

One version uses a plurality of heating elements outside the container in the course of thawing the reducing agent present in the container.

Using the innovative method to achieve normal operation of the SCR system more quickly allows reducing an overall amount of unwanted emissions.

One aspect of the invention contemplates providing the vehicle's SCR system with a number of different heating elements placed to heat the reductant present in various lines and components of the SCR system.

The method is easy to implement in existing motor vehicles. Software related to an SCR system according to the invention can be installed in a control unit of the vehicle during manufacture of the vehicle. A purchaser of the vehicle may alternatively have the option of selecting the function of the method as an option. Alternatively, software with program code for applying the innovative method to an SCR system can be installed in a vehicle's control unit on the occasion of the upgrade at a service point, in which case the software can be loaded into a memory in the control unit.

One aspect of the invention proposes a system according to claim 6.

• - eine Umlaufpumpe;
• - eine Dosiereinheit;
• - ein Mittel, das nicht nur für die Beurteilung der Notwendigkeit der Erwärmung von Reduktionsmittel zur Abgasreinigung geeignet ist, das in einem Behälter vorhanden ist, mithilfe eines Erwärmungsmediums, das durch den Behälter zirkuliert, sondern auch zur Beurteilung, ob das Anfahren der Zirkulation des Reduktionsmittels in dem SCR-System ansprechend auf eine derartige Erwärmung geeignet ist;
• - ein Mittel, das zum Bestimmen geeignet ist, ob das in dem Behälter vorhandene Reduktionsmittel wenigstens teilweise gefroren ist;
• - ein Mittel, das zum kontinuierlichen Bestimmen einer Temperatur des Reduktionsmittels in dem Behälter geeignet ist;
• - ein Mittel, das zum kontinuierlichen Bestimmen einer Differenz zwischen einer Temperatur des Erwärmungsmediums und der Temperatur des Reduktionsmittels im Behälter geeignet ist, oder
• - ein Mittel, das zum kontinuierlichen Bestimmen einer Differenz zwischen der Temperatur des Erwärmungsmediums stromaufwärts des Behälters und einer Temperatur des Erwärmungsmediums stromabwärts des Behälters geeignet ist; und
• - ein Mittel, das zum kontinuierlichen Bestimmen einer angehäuften Menge geschmolzenen Reduktionsmittels basierend auf der Temperaturdifferenz geeignet ist, als Basis für die Bestimmung der Angemessenheit des Anfahrens.

One aspect of the invention proposes an SCR system comprising:

• - a circulation pump;
• - a dosing unit;
• - a means suitable not only for assessing the need for heating the reducing agent present in a tank for cleaning exhaust gases by means of a heating medium circulating through the tank, but also for assessing whether the starting of the reducing agent circulation in the SCR system is appropriate in response to such heating;
• - a means suitable for determining whether the reducing agent present in the container is at least partially frozen;
• - a means suitable for continuously determining a temperature of the reducing agent in the container;
• - a means suitable for continuously determining a difference between a temperature of the heating medium and the temperature of the reducing agent in the container, or
• - a means suitable for continuously determining a difference between the temperature of the heating medium upstream of the container and a temperature of the heating medium downstream of the container; and
• - a means suitable for continuously determining an accumulated amount of molten reducing agent based on the temperature difference as a basis for determining the adequacy of the start-up.

• - ein Mittel, das zum kontinuierlichen Bestimmen einer angehäuften Menge an Energie, die auf das Reduktionsmittel basierend auf der Temperaturdifferenz während des Erwärmens übertragen wird, geeignet ist.

The SCR system may also include:

• - means suitable for continuously determining an accumulated amount of energy transferred to the reducing agent based on the temperature difference during heating.

• - ein Mittel, das zum Bestimmen der angehäuften Menge geschmolzenen Reduktionsmittels basierend auf der Menge an übertragener Energie und der Schmelzenthalpie des Reduktionsmittels geeignet ist.

The SCR system may also include:

• - means suitable for determining the accumulated amount of melted reducing agent based on the amount of energy transferred and the enthalpy of fusion of the reducing agent.

• - ein Mittel, das zum Erachten geeignet ist, dass das Anfahren der Umlaufpumpe angemessen ist, wenn eine bestimmte angehäufte Menge geschmolzenen Reduktionsmittels bestimmt wird.

The SCR system may also include:

• - a means suitable for deeming that the start-up of the circulating pump is appropriate when a certain accumulated amount of molten reducing agent is determined.

• - ein Mittel, das zum Starten des Dosierens des Reduktionsmittels bei einer bestimmten angehäuften Menge geschmolzenen Reduktionsmittels geeignet ist.

The SCR system may also include:

• - a means suitable for starting the dosing of the reducing agent at a certain accumulated amount of molten reducing agent.

The above objectives are also achieved with a motor vehicle provided with the aforementioned SCR system. The vehicle can be a truck, a bus or a car.

One aspect of the invention proposes an SCR system that is provided with a container for the reducing agent and a metering unit for an exhaust system of a ship's engine.

One aspect of the invention proposes an SCR system that is provided with a container for the reducing agent and a metering unit for an exhaust system of an industrial engine.

One aspect of the present invention proposes a computer program relating to an SCR system, comprising program code stored on a computer-readable medium such that an electronic control unit or another computer connected to the electronic control unit is caused to perform the steps according to one of claims 1 to 5 to execute.

One aspect of the present invention proposes a computer program relating to an SCR system, comprising program code to cause an electronic control unit or other computer connected to the electronic control unit to carry out the steps according to any one of claims 1 to 5.

One aspect of the present invention proposes a computer program product comprising program code stored on a computer-readable medium for performing the method steps according to any one of claims 1 to 5 when the computer program is on an electronic control unit or another computer connected to the electronic control unit is performed.

Other objects, advantages and novel features of the present invention will become apparent to those skilled in the art from the following details and also by practice of the invention. While the invention is described below, it is to be understood that it is not limited to the specific details described. One skilled in the art having access to the teachings herein will recognize other uses, modifications, and insertions in a similar context.

character list

• 1 eine schematische Darstellung eines Fahrzeugs gemäß einer Ausführungsform der Erfindung;
• 2 eine schematische Darstellung eines Teilsystems des in 1 dargestellten Fahrzeugs gemäß einer Ausführungsform der Erfindung;
• 3 eine schematische Darstellung eines Teilsystems des in 1 dargestellten Fahrzeugs gemäß einer Ausführungsform der Erfindung;
• 4a ein schematisches Flussdiagramm eines Verfahrens gemäß einer Ausführungsform der Erfindung;
• 4b ein detaillierteres schematisches Flussdiagramm eines Verfahrens gemäß einer Ausführungsform der Erfindung; und
• 5 eine schematische Darstellung eines Computers gemäß einer Ausführungsform der Erfindung.

For a better understanding of the present invention and its further objects and advantages, the detailed description set forth below should be read in conjunction with the accompanying drawings, in which the same reference numbers indicate similar elements throughout the various diagrams. Show it:

• 1 a schematic representation of a vehicle according to an embodiment of the invention;
• 2 a schematic representation of a subsystem of the in 1 illustrated vehicle according to an embodiment of the invention;
• 3 a schematic representation of a subsystem of the in 1 illustrated vehicle according to an embodiment of the invention;
• 4a a schematic flow diagram of a method according to an embodiment of the invention;
• 4b a more detailed schematic flow diagram of a method according to an embodiment of the invention; and
• 5 a schematic representation of a computer according to an embodiment of the invention.

DETAILED DESCRIPTION OF THE DRAWINGS

1 12 shows a side view of a vehicle 100. The illustrated vehicle includes a tractor 110 and a trailer 112. The vehicle may be a heavy vehicle such as a truck or a bus. Alternatively, it may be a car.

As used herein, the term "link" refers to a communication link, which may be a physical link, such as an optoelectronic communication line, or a non-physical link, such as a wireless link, eg, a radio link or a microwave link. As used herein, the term “reductant” refers to an agent used to react with certain emissions in an SCR system. These emissions can be NO _x gas, for example. In one version, the reducing agent is so-called AdBlue. Other types of reducing agents can of course also be used. AdBlue is cited herein as an example of a reductant, but one skilled in the art recognizes that the innovative method and apparatus can be used with other types of reductants, subject to necessary adjustments, e.g are possible with the innovative process.

As used herein, the term "heating element" refers to a device designed to heat an adjacent component, eg, a conduit, pump, or metering unit containing the reducing agent. The heating elements specified herein are therefore provided to heat the reductant at various locations in the vehicle 100 . A heating element can be an electrical heating element powered by, for example, one or more batteries, not shown.

Alternatively, a heating element may be a coolant-based heating element that uses radiator fluid from an engine of the vehicle to heat the reductant in a reductant tank of the SCR system.

It should be noted that the invention is suitable for application in any SCR system and is therefore not limited to motor vehicle SCR systems. The innovative method and the innovative fluid supply system according to one aspect of the invention are well suited for platforms other than motor vehicles with an SCR system, e.g. The watercraft can be any, e.g., a motor boat, a steamboat, a ferry, or a ship.

The innovative method and the innovative SCR system according to an aspect of the invention are also well suited for, for example, systems comprising tractors, dump trucks, power tools, industrial engines and/or motors.

The innovative method and the innovative SCR system according to an aspect of the invention are also well suited for different types of power plants, for example an electric power plant provided with a diesel generator.

The innovative process and SCR system are also well suited to any engine system that includes an engine and an SCR system, such as a locomotive or other platform.

The innovative method and the innovative SCR system are well suited for a system that includes a _NOx generator, eg a diesel engine, in which exhaust gases have to be cleaned.

As used herein, the term "conduit" refers to a passage for holding and conveying a fluid, e.g., a reducing agent, in liquid form. The conduit may be any size tubing and may be made of any suitable material such as plastic, rubber or metal.

2 12 shows a subsystem 299 of the vehicle 100. The subsystem may be positioned in the tractor 110. FIG. The subsystem can be part of an SCR system.

In this example, the subsystem comprises a container 205 which is arranged to receive a reducing agent. The reservoir is arranged to contain an appropriate amount of reducing agent and is refillable when required.

A first line 271 is provided to direct the reductant to a pump 230 from the tank 205 . The pump is arranged to draw the reducing agent from the container via the first line 271 and direct it to a metering unit 250 via a second line 272 . The pump is arranged to pressurize the reductant in the second line 272 .

The dosing unit 250 is configured to direct the reducing agent to an exhaust system of the vehicle 100 . More specifically, it is designed to power a vehicle. In this version, an SCR catalyst (not shown) is positioned downstream of a position where reductant supply takes place. The amount of reductant fed into the exhaust system is intended to be used in a conventional manner in the SCR catalytic converter to reduce the amount of unwanted emissions.

A third line 273 runs between the dosing unit 250 and the canister 205 and is configured to direct a certain amount of the reducing agent that is supplied to the dosing unit 250 back to the canister.

A first fluid line 281 is provided to receive and convey a fluid. The fluid is a heating medium. It may be radiator fluid for an engine (not shown) of the vehicle 100 . The first fluid line is partially positioned within the canister 205 to heat the reductant therein. The first fluid line is positioned partially within the container for optionally melting the reductant therein through energy transfer. The first fluid line in this example is arranged to direct radiator fluid, which has been heated by the vehicle's engine in a closed loop, through the reservoir, via the pump 230 and a second fluid line 282 back to the vehicle's engine.

In one version, a separate pump is provided, eg a pump for the engine's radiator fluid. In this example, the fluid does not have to be circulated by the pump 230, which can also be called a feed means or circulation pump. The pump can be any suitable type of pump. It can be a diaphragm pump. It can be heated in one version by a circulating heating medium. For example, in one version, the first conduit 271 may be arranged to connect the pump 230 downstream ward of the container 205 warms. In an alternative, the pump can be heated by a circulating medium supplied by a device serving this purpose. In one version, the first fluid line 281 is designed in part as a heating coil that runs around the first line 271 and the third line 273 in the container 205, for heating or melting the reducing agent in the container. The first fluid line may alternatively have another suitable form, e.g a U shape. A first heating element 261 is provided adjacent to the second conduit 272 to heat the reductant therein as needed. A second heating element 262 is provided adjacent the dosing unit 250 to heat both the dosing valve and the reductant therein when needed. A third heating element 263 is provided adjacent to the third conduit 273 to heat the reductant therein as needed.

It should be noted that it is possible for a heating element to be provided at any suitable location in subsystem 299 in accordance with the invention. Various configurations are possible.

A first control unit 200 is provided to control the operation of the first heating element 261, the second heating element 262 and the third heating element 263 appropriately. The first control unit can be arranged to control the operation of the first heating element, the second heating element and the third heating element independently of one another. In one version, the first control unit is arranged to activate and operate the heating elements when the circulation of the reductant of the SCR system is deemed appropriate.

The first control unit 200 is arranged to communicate with a first temperature sensor 221 via a link L221. The first temperature sensor is configured to detect an actual temperature of the reducing agent where the sensor is installed. In one version, this first temperature sensor is positioned in the container 205 in close proximity to the first and/or third conduit. In one version, it is positioned in close proximity to the first and/or third duct at the bottom of the tank. In one version it is positioned in a lower portion of the container. The sensor is configured to continuously send signals containing information about a prevailing temperature of the reducing agent to the first control unit via connection L221.

The first control unit 200 is arranged to communicate with the pump 230 via a link L230. The first control unit is configured to control operation of the pump to regulate the flow of reductant within subsystem 299, for example. The first control unit is configured to activate the circulation of the reducing agent when deemed appropriate according to an embodiment of the present invention.

The first control unit 200 is arranged to communicate with the dosing unit 250 via a connection L250. The first control unit is configured to control the operation of the dosing unit, for example to regulate the routing of the reducing agent to the exhaust system of the vehicle 100 . The first control unit is configured to activate the dosing of the reducing agent when deemed appropriate according to an embodiment of the present invention.

A second control unit 210 is arranged to communicate with the first control unit 200 via a link L210. The second control unit can be detachably connected to the first control unit. The second control unit may be a control unit outside the vehicle 100 . The second control unit can be designed to carry out the innovative method steps according to the invention. It can be used to upload software to the first control unit, in particular software for carrying out the innovative method. As an alternative to communication with the first control unit, it can be arranged on board the vehicle via an internal network. It can be arranged to perform functions essentially similar to those of the first control unit.

In the schematic in 2 In the illustrated embodiment, the first control unit 200 is arranged to control the pump 230 in such a way that at least part of the molten reducing agent is extracted from the elements 261, 262 and 263 outside the container, if necessary. The first control unit is further configured to control the pump in such a way that the melted part of the reducing agent is returned to the container before its dosing by the dosing unit 250 in the SCR system starts.

3 FIG. 12 shows schematically a part of the subsystem 299 shown in relation to FIG 2 is described. Some of the regarding 2 components described have been omitted here.

The first control unit 200 is arranged to communicate with a second temperature sensor 222 via a link L222. The second sensor is designed to continuously measure a prevailing temperature T2 of the fluid upstream of the container 205 . The second sensor is configured to continuously send signals containing information about the actual temperature of the fluid to the first control unit via the connection L222. The second sensor may be positioned in close proximity upstream of the tank or adjacent to the vehicle's engine or at a suitable position between the engine and the tank.

The first control unit 200 is arranged to communicate with a third temperature sensor 223 via a link L223. The third sensor is designed to continuously measure a prevailing temperature T3 of the fluid downstream of the container 205 . The third sensor is configured to continuously send signals containing information about the prevailing temperature of the fluid to the first control unit via connection L223. The third sensor may be positioned immediately downstream of the tank or adjacent to the vehicle's engine or at a suitable position between the engine and the tank. In one example, the third temperature sensor may be adjacent to pump 230 .

In one version the first control unit 200 is arranged to communicate with the temperature sensors via the second control unit 210 . The first line 281 is arranged to conduct a heating fluid for melting frozen reductant in the container 205 . In one version, the first line is connected to a system designed to cool an engine of the vehicle.

During engine cooling, thermal energy is transferred from the engine to the fluid. In one example, the fluid is radiator fluid of an engine cooling system. In one version, the pump 230 is arranged to circulate the fluid from the motor to the tank and back to the motor via line 282 in a closed loop. It should be noted that the reductant and the heating fluid are never mixed but are physically separated across the lines.

In an alternative version, a heating medium can be used external to the vehicle, in which case a separate container with a heating medium can be used and connected to a circulation line present in the vehicle. This allows the use of either a supply device external to the vehicle or a supply device on board the vehicle for this purpose for the circulation of the heating fluid.

In one version, the first control unit 200 is arranged to use the received signals, which represent a prevailing temperature T1 of the reducing agent in the region of the temperature sensor 221 and a prevailing temperature T2 of the fluid upstream of the container 205, as a basis for controlling the operation of the pump 230 and the dosing unit 250 according to the innovative method.

In one version, the first control unit is arranged to use the received signals, which represent a prevailing temperature T1 of the reducing agent in the region of the temperature sensor 221 and a prevailing temperature T2 of the fluid upstream of the container 205, as a basis for determining a temperature difference between the two according to to use one aspect of the innovative process.

The first control unit is arranged in one version to use the received signals representing a prevailing temperature T3 of the fluid downstream of the container 205 and a prevailing temperature T2 of the fluid upstream of the container as a basis for determining a temperature difference between the two according to one aspect to use the innovative process.

• - Bestimmen, ob das in dem Behälter 205 vorhandene Reduktionsmittel wenigstens teilweise gefroren ist, und, wenn das der Fall ist,
• - kontinuierliches Bestimmen einer Temperatur des Reduktionsmittels im Behälter;
• - kontinuierliches Bestimmen einer Differenz zwischen einer Temperatur des Erwärmungsmediums und der Temperatur des Reduktionsmittels im Behälter, oder
• - kontinuierliches Bestimmen einer Differenz zwischen der Temperatur des Erwärmungsmediums stromaufwärts des Behälters und einer Temperatur des Erwärmungsmediums stromabwärts des Behälters; und
• - kontinuierliches Bestimmen einer angehäuften Menge geschmolzenen Reduktionsmittels basierend auf der Temperaturdifferenz, als Basis für die Bestimmung der Angemessenheit des Anfahrens.

4a 13 is a schematic flowchart of a method related to an SCR system provided with a circulation pump 230 and a metering unit 250 not only for assessing the need for heating the reducing agent for exhaust gas purification present in a canister 205 using a heating medium circulating through the tank, but also to assess whether starting up the circulation of the reducing agent in the SCR system in response to such heating is appropriate, according to the invention. The method includes a first step s401, which includes the following steps:

• - determining whether the reducing agent present in the container 205 is at least partially frozen and, if so,
• - continuously determining a temperature of the reducing agent in the container;
• - continuously determining a difference between a temperature of the heating medium and the temperature of the reducing agent in the container, or
• - continuously determining a difference between the temperature of the heating medium upstream of the container and a temperature of the heating medium downstream of the container; and
• - continuously determining an accumulated amount of molten reductant based on the temperature difference as a basis for determining the adequacy of the start-up.

The process ends after step s401.

4b 13 is a schematic flowchart of a method related to an SCR system provided with a circulation pump 230 and a metering unit 250 not only for assessing the need for heating the reducing agent for exhaust gas purification present in a canister 205 using a heating medium circulating through the tank, but also to assess whether starting up the circulation of the reducing agent in the SCR system in response to such heating is appropriate, according to the invention.

The method includes a first step s410, which includes the step of determining whether the reducing agent present in the container 205 is at least partially frozen. This can be achieved by measuring the temperature of the reductant using the first temperature sensor 221 . It may alternatively be achieved by considering an ambient temperature determined at the time the vehicle is parked and/or an ambient temperature determined at the time the vehicle is started. Step s410 comprises the step, when the reducing agent present in the container is at least partially frozen, of continuously determining a temperature T1 of the reducing agent in the container. Step s410 is followed by a step s420.

• - des kontinuierlichen Bestimmens einer Differenz zwischen der Temperatur T2 des Erwärmungsmediums stromaufwärts des Behälters und einer Temperatur des Erwärmungsmediums stromabwärts des Behälters. Schritt s420 ist gefolgt von einem Schritt s430.

The method step s420 includes the step of continuously determining a difference between a temperature of the heating medium and the temperature T1 of the reducing agent in the container 205, or

• - continuously determining a difference between the temperature T2 of the heating medium upstream of the tank and a temperature of the heating medium downstream of the tank. Step s420 is followed by a step s430.

The method step s430 includes the step of continuously determining an accumulated amount of energy transferred to the reducing agent based on one of the temperature differences during the heating. This can be done by continuously integrating estimated amounts of energy transferred from the heating medium to the reductant in the canister. The estimated amounts of energy transferred may be based on the determined temperature differences (T1-T2, T3-T2), which multiplied by a constant may give an appropriate value, and may be based on the properties of the reductant. Step s430 is followed by a step s440.

The method step s440 includes the step of continuously determining an accumulated amount of melted reducing agent based on the temperature difference as a basis for determining the adequacy of the start-up. It may include the step of determining the cumulative amount of melted reductant based on the cumulative amount of transferred energy and the enthalpy of fusion of the reductant. Steps s420, s430 and s440 are executed until it is deemed appropriate to start the pump 230. Step s440 is followed by a step s450.

The method step s450 may comprise the step, if starting the pump 230 for circulating the reducing agent is deemed appropriate, starting the pump therefor. In an example embodiment, it is deemed appropriate to start the pump when a predetermined first amount of reductant has thawed. The first amount of reducing agent can be any suitable amount, for example 2, 5 or 10 litres. The step s450 can include the step of heating the reducing agent by the heating elements 261, 262 and/or 263. Step s450 is followed by a step s460.

The method step s460 may comprise the step of starting the dosing of the reducing agent by means of the dosing unit 250 according to operating routines stored in the first control unit after it has been deemed appropriate. In an example embodiment, it is deemed appropriate to start the dosing unit when a predetermined second amount of reductant has thawed. The second amount of reducing agent can be any suitable amount, for example 12, 15 or 20 litres.

The method ends after step s460.

5 FIG. 12 is a diagram of one version of an apparatus 500. The controllers 200 and 210 shown with respect to FIG 2 may include device 500 in one version. The device 500 includes a non-volatile memory 520, a data processing unit 510 and a read-write memory 550. The non-volatile memory 520 has a first memory element 530, in which a computer program, for example an operating system, for controlling the function of Device 500 is stored. The device 500 further includes a bus controller, a serial Interface, I/O means, an A/D converter, a time and date input and a transition unit, an event counter and an interrupt controller (not shown). The non-volatile memory 520 also includes a second storage element 540 .

A proposed computer program P includes routines not only for judging the necessity of heating reducing agent for exhaust gas purification present in a canister by means of a heating medium circulating through the canister, but also for judging whether starting the circulation of the reducing agent in of the SCR system in response to such heating.

The computer program P includes routines for continuously determining a temperature of the reducing agent in the container. It includes routines for determining whether the reductant present in the container is at least partially frozen. It includes routines for continuously determining a difference between a temperature of the heating medium and the temperature of the reducing agent in the container. Alternatively, it includes routines for continuously determining a difference between the temperature of the heating medium upstream of the vessel and a temperature of the heating medium downstream of the vessel. It includes routines for continuously determining an accumulated amount of molten reductant based on the temperature difference, as a basis for determining the adequacy of the start-up. It includes routines for continuously determining an accumulated amount of energy transferred to the reductant. It includes routines for determining the cumulative amount of melted reductant based on the cumulative amount of energy transferred and the enthalpy of fusion of the reductant. It includes routines for judging that it is appropriate to start the circulating pump when a certain accumulated amount of melted reductant is determined. It includes routines for starting the dosing of the reductant at a certain accumulated amount of molten reductant.

The computer program P can be stored in an executable form or in a compressed form in a memory 560 and/or in a read-write memory 550.
Where computing unit 510 is described as performing a particular function, it means executing a particular portion of the program stored in memory 560 or a particular portion of the program stored in read-write memory 550 .

The data processing device 510 can communicate with a data interface 599 via a data bus 515 . The non-volatile memory 520 is intended to communicate with the data processing unit 510 via a data bus 512 . The separate memory 560 is intended to communicate with the data processing unit 510 via a data bus 511 . The read-write memory 550 is configured to communicate with the data processing unit 510 via a data bus 514 . The data interface 599 can, for example, be connected to the connections L210, L221, L222 and L223 (see 2 and 3 ).

When data is received at the data interface 599, it is temporarily stored in the second memory element 540. If received input data has been temporarily stored, the data processing unit 510 is prepared to perform code execution as previously described. In one version, signals received at the data interface 599 contain information about a prevailing temperature T1 of the reducing agent in the container 205. In one version, signals contain information about the heating medium upstream of the container. In one version, signals received at the data interface contain information about a prevailing temperature T2 of the heating medium downstream of the container.

Portions of the methods described herein may be performed by device 500 using computing device 510 executing programs stored in memory 560 or read-write memory 550 . When the device 500 executes the program, methods described herein are performed.

The foregoing description of the preferred embodiments of the present invention has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the variants described. Many modifications and variations will be apparent to those skilled in the art. The embodiments have been chosen and described in order to best explain the principle of the invention and its practical applications, and thus to enable a person skilled in the art to utilize the invention with various embodiments and with the different modifications appropriate to the intended use. understands.

Claims (14)

Method relating to an SCR system provided with a circulating pump (230) and a dosing unit (250), in order not only to avoid necessity a heating of a reducing agent present in a tank (205) for exhaust gas purification by means of a heating medium circulating through the tank (205), but also to judge whether a start-up of circulating the reducing agent in the SCR system in response to such heating is appropriate, the method comprising the following steps: - determining whether the reducing agent present in the container (205) is at least partially frozen, and if this is the case, - continuously determining (s410) a temperature (T1) of the Reducing agent in the container (205), characterized by the following steps: - continuously determining (s420) a difference between a temperature of the heating medium and the temperature (T1) of the reducing agent in the container (205), or - continuously determining (s420) a difference between the temperature (T2) of the heating medium upstream of the tank (205) and a temperature (T3) the heating medium downstream of the tank (205); and - continuously determining (s440) an accumulated amount of molten reductant based on the temperature difference as a basis for determining the adequacy of the start-up. procedure after claim 1 , further comprising the step of: - continuously determining (s430) an accumulated amount of energy transferred to the reducing agent based on the temperature difference during the heating. procedure after claim 2 , further comprising the step of: - determining (s440) the accumulated amount of melted reducing agent based on the accumulated amount of transferred energy and the enthalpy of fusion of the reducing agent. A method according to any one of the preceding claims, wherein a start-up (s450) of the circulating pump is deemed appropriate when a certain accumulated amount of molten reductant is detected. A method according to any one of the preceding claims, further comprising the step of: - starting the dosing (s460) of the reducing agent at a certain accumulated amount of melted reducing agent. SCR system, comprising: - a circulation pump (230); - a dosing unit (250); - a device that is not only suitable for assessing the need to heat a reducing agent present in a container (205) for exhaust gas purification by means of a heating medium circulating through the container (205), but also for assessing whether starting the circulation of the reducing agent in the SCR system is adequate in response to such heating; - A device which is suitable for assessing whether the reducing agent present in the container (205) is at least partially frozen; - A device which is suitable for continuously determining a temperature (T1) of the reducing agent in the container (205); characterized by : - a device which is suitable for continuously determining a difference between a temperature of the heating medium and the temperature (T1) of the reducing agent in the container (205), or - a device which is suitable for continuously determining a difference between the temperature (T2 ) of the heating medium upstream of the container (205) and a temperature (T3) of the heating medium downstream of the container (205); and - means adapted to continuously determine an accumulated amount of molten reductant based on the temperature difference as a basis for determining the adequacy of the start-up. SCR system after claim 6 , further comprising: - means suitable for continuously determining an accumulated amount of energy transferred to the reducing agent based on the temperature difference during heating. SCR system after claim 7 , further comprising: - means suitable for determining the accumulated amount of melted reductant based on the accumulated amount of energy transferred and the enthalpy of fusion of the reductant. SCR system according to one of the Claims 6 until 8th A system comprising: - means adapted to judge that starting the circulating pump (230) is appropriate when a certain accumulated amount of molten reductant is detected. SCR system according to one of the Claims 6 until 9 , further comprising: - means for starting dosing of the reducing agent at a certain accumulated amount of molten reducing agent is appropriate. Motor vehicle (100; 110) with an SCR system according to one of Claims 6 until 10 is provided. Motor vehicle (100; 110) according to claim 11 , where the vehicle is any of the following: a truck, a bus, or a car. Computer program (P) relating to an SCR system, the program comprising a program code which causes an electronic control unit (200) or another computer connected to the electronic control unit (200) to perform the steps according to one of Claims 1 until 5 to execute. Computer program product with a computer program (P) on a computer-readable medium for performing the method steps according to one of Claims 1 until 5 is stored when the computer program is executed on an electronic control unit (200) or another computer connected to the electronic control unit (200).

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