SE1251035A1 - SCR system and procedure of an SCR system - Google Patents

Abstract

SUMMARY The invention relates to a method of an SCR system comprising an encirculation pump (230) and a dosing unit (250) for assessing the need for heating in a container (205) arranged pre-exhaust gas by means of a container (205) through said container. circulating heating medium and on the one hand assess whether a start-up of circulation said reducing agent in said SCR system is suitable for such heating, including the steps of: - continuously determining (s410) one reducing agent in said container; temperature (T1) of said continuously determining (s420) a difference between a temperature (T2) of said heating medium and the temperature (T1) of said reducing agent in said container (205), or - continuously determining (s420) a difference between the temperature (s420) T2) said heating medium upstream of said container (205) and one temperature (T3) of said heating medium downstream of said container (205); and - continuously determining (s440) an accumulated amount of molten reducing agent based on said temperature difference as a basis for determining suitability for said start-up. The invention also relates to a computer program product comprising program code (P) for a computer (200; 210) for implementing a method according to the invention. The invention also relates to an SCR system and a motor vehicle which is equipped with the SCR system. Figure 2 for publication

Description

10 15 20 25 30 other parts of the SCR system to freeze at an ambient temperature below a certain time below said freezing point.

According to current regulations regarding emissions, certain vehicles must equipped with an SCR system is operated normally after a certain predetermined time after starting the vehicle. Said predetermined time can according to an example be 70 minutes. Thus, it must be frozen reducing agent is at least partially melted in order to be able to circulate in the SCR the system before dosing is started within the said time period.

According to a known method of assessing the start-up of the circulation pump and reducing agent dosage is appropriate use a temperature sensor present in the container to measure a prevailing temperature of said reducing agent. In this case, it can with a certain degree of probability determine whether said reducing agent in the container is thawed or not. One disadvantage of said method is that temperature measurements as a basis do not always gives a correct assessment, depending on, for example, where the sensor is mounted, the configuration of for example the suction hose and the container configuration and size. In this case, there are fairly large safety margins required to avoid starting a circulation pump of the SCR system too early. If the circulation pump is started up too early, then one does not sufficient amount of reducing agent has thawed, there is a risk that the pump "sucks dry", which can have a number of side effects. An example of such undesirable effect is that air enters the SCR system, which can significantly impair the performance of the system. Furthermore, effective continued thawing is prevented of frozen reducing agent.

In some cases, where frozen reducing agent in the tank, for example, is thawed by means of a circulating heating medium, and where the circulating pump sucks dry, can a situation arises where frozen reducing agent in the container cannot be thawed further by said circulating heating medium. This can get extremely serious consequences, where applicable legal requirements apply 10 15 20 25 30 emissions of the vehicle can not be met within the required time. Furthermore, can the pump is at risk of permanent damage or suffering from high wear and tear it is started too early.

US 8011176 describes a method for thawing frozen urea in an SCR system by means of a heater. It is further described that said heater is switched off after a certain time when it is judged that the heater has been in operation long enough for said urea has melted. A disadvantage of this procedure is that rather large safety margins are required, which means that operation of a pump and reducing agent dosing can be started only at a relatively late time.

US 20100095653 describes a process for thawing frozen urea there the dosing system is activated when said urea has reached a certain temperature.

SUMMARY OF THE INVENTION There is thus a need to reliably assess whether one circulation pump of the SCR system where reducing agent has frozen can start up, without using excessive safety margins to avoid said undesirable effects when the pump is forced to suck dry.

An object of the present invention is to provide a novel and advantageous procedure in an SCR system.

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

A further object of the invention is to provide a method of an SCR system, an SCR system and a computer program to accomplish a faster start-up of an SCR system of a motor vehicle where a exhaust gas reducing agent is at least partially frozen. 10 15 20 25 30 A further object of the invention is to provide a method of an SCR system, an SCR system and a computer program to accomplish a reliable commissioning of an SCR system of a motor vehicle.

A further object of the invention is to provide a method of an SCR system, an SCR system and a computer program to improve performance of a motor vehicle.

An object of the invention is to provide an SCR system in which dosing of a reductant, e.g. urea in the form of AdBlue, can be started faster at a situation where said reductant is initially, at least in part, in a frozen state.

An object of the invention is to provide an SCR system in which circulation of a reductant, e.g. urea in the form of AdBlue, can be started faster at a situation where said reductant is initially, at least in part, in a frozen state.

These objects are achieved by a method in an SCR system according to claim 1.

According to one aspect of the invention, there is provided a method of an SCR system comprising a circulation pump and a dosing unit for assess the need for heating in a container arranged reducing agent for exhaust gas purification by means of a heater circulating through said container medium and partly assess whether a start-up of circulation of the said reducing agent in said SCR system is suitable for such heating.

The procedure includes the steps of: continuously determining a temperature of said reducing agent in said container; - continuously determine a difference between a temperature of said heating medium and the temperature of said reducing agent in said containers, or 10 15 20 25 30 continuously determine a difference between the temperature of said heating medium upstream of said container and a temperature of said heating medium downstream of said container; and - continuously determine an accumulated amount of molten reducing agent based on said temperature difference as a basis for determining suitability for said start-up.

According to one embodiment, an estimated heat transfer is continuously integrated from said circulating heating medium to said reducing agent over time to determine a molten amount of reducing agent in the container. Hereby can the circulation pump is started when a first sufficient amount of reducing agent thawed instead of having to wait until a temperature of said reducing agent in the tank exceeded a certain limit value. In this case, dosing can of reducing agent is started when a sufficient second amount of reducing agent thawed instead of having to wait until a temperature of said reducing agent in the tank exceeded a certain limit value.

The procedure may further comprise the step of: continuously determine an accumulated amount of energy transferred to said reducing agent based on said temperature difference below said heating. This provides an improved method in an SCR system where an adequate estimate of the amount of energy transferred forms the basis for to determine as soon as possible whether the SCR system can be started up on one safe and component-friendly way.

The procedure may further comprise the step of: determining said accumulated amount of molten reducing agent based on said accumulated transferred amount of energy and the reducing agent melting enthalpy. This provides a simple and non-computationally heavy method for accurately calculating said accumulated amount molten reducing agent. The melting enthalpy of the reducing agent provided is in known in advance. By accurately modeling the existing one 10 15 20 25 30 amount of thawed reducing agent in the container according to the invention can be a prior start-up of the circulation pump and dosing of reducing agents achieved compared to technology where the pump is started up after a predetermined time or at an attained predetermined at temperature said reducing agents.

According to the present invention there is provided a method wherein circulation of reducing agents and later dosing thereof can not be performed even then all reducing agent in the container is thawed. It is according to the invention only necessary to thaw a predetermined first and second amount, respectively reducing agents to reliably activate said pump and dosing of reducing agent by means of the dosing unit.

Start-up of said circulation pump can be considered suitable for a certain determined accumulated amount of molten reducing agent. Said accumulated amount of molten reducing agent may be an appropriate amount. Said appropriate quantity can be determined on the basis of, for example, the size of the container, the amount of residual reducing agent and the configuration of the SCR system.

Said suitable amount may be, for example, 5 liters.

The procedure may further comprise the step of: start dosing said reducing agent at a certain accumulated amount of molten reducing agent. Said accumulated amount of melt reducing agent may be an appropriate amount. Said appropriate amount can determined on the basis of, for example, the size of the container, the quantity residual reducing agents and the configuration of the SCR system. Sagda suitable amount may be, for example, 15 liters. Innovative procedure is that a faster An advantage of that thawing process of at least partially frozen reductant present in the container is provided because the circulation pump can be started on a relatively early stage. By circulating said reducing agent 10 15 20 25 30 in the SCR system used heating elements can a faster thawing process is provided. According to an alternative embodiment, a circulating heating medium is used to heat the reductant of different portions of the SCR system outside the container.

By starting to circulate a sufficient amount of melt as early as possible reductant present in the container of the SRC system without dosing the same to the exhaust gases of the vehicle can a heating effect in others vehicle components, for example, a muffler, at the SCR system be used to melt the reductant in the container.

As a beneficial synergy effect of using for the container external heating element together with a said heating medium of the container achieves a faster thawing of the reductant in the container on the basis of increased agitation in the container. This is accomplished due to a flow of the reductant during a phase when it is circulating within the SCR system, and in particular in the container, without being metered into the exhaust stream.

According to one embodiment, a plurality of heating elements external to the container are used in the thawing process of the reductant contained in the container.

Because a faster start-up of normal operation of the SCR system achieved with the innovative procedure can a reduction of a total amount of unwanted emissions is realized.

According to one aspect of the invention, there are a number of different heating elements The SCR system, which are arranged to heat the reductant present in various wires and components of the SCR system of the vehicle.

The procedure is easy to implement in existing motor vehicles. Software at an SCR system according to the invention can be installed in a control unit of the vehicle in the manufacture of the same. A buyer of the vehicle can alternatively 10 15 20 25 30 be able to select the function of the procedure as an option. Alternatively can software including program code to perform the innovative procedure at an SCR system is installed in a control unit of the vehicle when upgrading at a service station. In this case, the software can be loaded into a memory in styrene hot.

According to one aspect of the invention, there is provided a device according to claim 6.

According to one aspect of the invention there is provided an SCR system comprising: - a circulation pump; - a dosage unit, bodies adapted to assess the need for heating in a container arranged reducing agent for exhaust gas purification by means of a genome said container circulating heating medium and partly assess a start-up of circulation of said reducing agent in said SCR system is suitable in such heating; means adapted to continuously determine a temperature of said reducing agents in said container; means adapted to continuously determine a difference between a temperature of said heating medium and the temperature of said reducing agent in said container, or bodies adapted to continuously determine a difference between the temperature of said heating medium upstream of said container and a temperature of said heating medium downstream of said container; and bodies adapted to continuously determine an accumulated amount of melt reducing agent based on said temperature difference as a basis for determination of suitability for said start-up.

The SCR system may further comprise: 10 15 20 25 30 bodies adapted to continuously determine an accumulated transfer amount of energy to said reducing agent based on said temperature difference during said heating.

The SCR system may further comprise: means adapted to determine said accumulated amount of melt reducing agent based on said accumulated amount of energy transferred and the melting enthalpy of the reducing agent.

The SCR system may further include means adapted to assess that the start-up of said circulation pump is suitable for a certain determined accumulated amount of molten reducing agent.

The SCR system may further comprise: means adapted to initiate dosing of said reducing agent at a certain accumulated amount of molten reducing agent.

The above objects are also achieved with a motor vehicle comprising the above said SCR system. The motor vehicle can be a truck, bus or car.

According to one aspect of the invention, there is provided an SCR system, which SCR system comprises a container for said reductant and a dosing unit in an exhaust system of a marine engine.

According to one aspect of the invention, there is provided an SCR system, which SCR system comprises a container for said reductant and a dosing unit in an exhaust system of an industrial engine.

According to one aspect of the present invention, there is provided a computer program in an SCR system, where said computer program comprises program code stored on a computer-readable medium to cause an electronic control unit 10 15 20 25 30 10 or another computer connected to the electronic control unit to perform the steps according to any one of claims 1-5.

According to one aspect of the present invention, there is provided a computer program in an SCR system, wherein said computer program includes program code for cause an electronic controller or other computer connected to it electronic control unit to perform the steps according to any one of claims 1-5.

According to a computer program product comprising a program code stored on one, by a computer aspect of the present invention there is provided readable, medium for performing the process steps according to any one of the claims 1-5, when said computer program is run on an electronic control unit or a another computer connected to the electronic control unit.

Additional objects, advantages and novel features of the present invention the invention will be apparent to those skilled in the art from the following details, as well via the practice of the invention. While the invention is described below, it will be apparent that the invention is not limited to those specifically described the details. Those who have access to the teachings herein will recognize and incorporations into others additional applications, modifications areas which are within the scope of the invention. SUMMARY DESCRIPTION OF THE DRAWINGS For a more complete understanding of the present invention and further purposes and benefits thereof, reference is now made to the following detailed description to be read together with the accompanying drawings there equally reference numerals refer to equal parts in the various figures, and in which: Figure 1 schematically illustrates a vehicle, according to an embodiment of the invention; 10 15 20 25 30 11 Figure 2 schematically illustrates a subsystem of the vehicle shown in Figure 1, according to an embodiment of the invention; Figure 3 schematically illustrates a subsystem of the vehicle shown in Figure 1, according to an embodiment of the invention; Figure 4a schematically illustrates a flow chart of a method, according to a embodiment of the invention; Figure 4b schematically illustrates in further detail a flow chart over one method, according to an embodiment of the invention; and illustrates a computer, Figure 5 schematically according to an embodiment of the invention.

DETAILED DESCRIPTION OF THE FIGURES Referring to Figure 1, a side view of a vehicle 100 is shown The exemplary vehicle 100 consists of a tractor 110 and a trailer 112.

The vehicle can be a heavy vehicle, such as a truck or a bus. The vehicle can alternatively be a car.

Here, the term "link" refers to a communication link that may be one physical wire, such as an opto-electronic communications wire, or a non-physical wiring, such as a wireless connection, such as a radio or microwave link.

Here, the term "reductant" refers to an agent used to react with certain emissions in an SCR system. These emissions can e.g. be NOX gas. Said reductant is according to an embodiment so-called AdBlue. Of course other types of reductants can be used. Here, AdBlue is listed as one example of a reductant but a professional realizes the innovative procedure and the innovative device can be realized for other types of reductants, with necessary adjustments, such as e.g. adaptations to adequate freezing point for selected reductants, in control algorithms for execution software code in accordance with the innovative procedure. 10 15 20 25 30 12 Here, the term "heating element" refers to a device which is arranged to heating an adjacent component, such as e.g. a line, pump or dosage unit containing said reductant. The ones listed here the heating elements are sold arranged to heat the reductant at different positions in the vehicle 100. A heating element may be an electric one heating elements which are energized by e.g. one or more batteries (not shown).

Alternatively, a heating element may be a coolant-based heating element which uses coolant from an engine of the vehicle to heat the said reductant in a reducing agent container of the SCR system.

It should be noted that the invention is suitable for application in a arbitrary SCR system and is not sold limited to SCR system at motor vehicle. The innovative procedure and the innovative the liquid supply system according to an aspect of the invention is well suited for platforms involving an SCR system other than motor vehicles, such as for example watercraft. The watercraft can be of any kind, such as for example motorboats, ships, ferries or ships.

The innovative procedure and the innovative SCR system according to one aspect of the invention is also well suited for e.g. systems including tractors, dumpers, power tools, industrial engines and / or motorized industrial robots.

The innovative procedure and the innovative SCR system according to one aspect of the invention is also well suited for different types of power plants, such as e.g. an electric power plant comprising a diesel generator.

The innovative procedure and the innovative SCR system are well suited for any motor system including an engine and an SCR system, such as e.g. at a locomotive or other platform. 10 15 20 25 30 13 The innovative procedure and the innovative SCR system are well suited for a system that includes a NOX generator, such as a diesel engine, whose exhaust gases are to be purified.

Here, the term "lead" refers to a passage for holding and transporting a fl uid, such as e.g. a reductant in liquid form. The wire can be a tube of arbitrary dimension. The management can consist of an arbitrary, appropriate materials, such as e.g. plastic, rubber or metal.

Referring to Figure 2, a subsystem 299 of the vehicle 100 is shown.

The subsystem 299 can be arranged in the tractor 110. The subsystem 299 can form part of an SCR system. Subsystem 299 consists accordingly example of a container 205 arranged to hold a reductant.

The container 205 is arranged to contain a suitable amount of reductant and is further arranged to be able to be refilled if necessary.

A first line 271 is arranged to lead the reductant to a pump 230 from the container 205. Said pump is 230 arranged to inflate the reductant from the container 205 via the first conduit 271 and via a second conduit 272 supply said reductant to a metering unit 250. The pump 230 is arranged to pressurize the reductant in the second line 272.

The dosing unit 250 is arranged to supply said reductant to a exhaust system of the vehicle 100. More specifically, the dosing unit is 250 arranged to supply a suitable amount of reductant to one in a controlled manner exhaust system of the vehicle 100. According to this embodiment, an SCR catalyst (not shown) arranged downstream of a position where supply of the reductant achieved. The amount of reductant added to the exhaust system is intended to be used in a conventional manner in the SCR catalyst to reduce the amount of unwanted emissions. 10 15 20 25 30 14 A third conduit 273 is provided between the metering device 250 and the container 205. The third conduit 273 is arranged to conduct return a certain amount of the reductant fed to the dosing unit 250 to the container 205.

A first fluid conduit 281 is provided to hold and transport a fluid.

Said fl uid is a warming medium. Said fluid may be coolant for one engine (not shown) of the vehicle 100. The first fluid line 281 is partial arranged in the container 205 to heat the reductant present therein. The the first fluid conduit 281 is partially disposed in the container 205 to, where it is applicable, melt the reductant present therein by energy transfer. The according to this example, the first fluid line 281 is arranged to lead coolant heated by the vehicle's engine in a closed loop through the container 205, via the pump 230 and a second fluid line 282 back to the engine of the vehicle 100.

According to one embodiment, a separate pump is, for example, a pump for the motor coolant, if present. According to this exemplary embodiment does not need the fluid is circulated by means of the pump 230. Said pump 230 can also referred to as a supply means or circulation pump. Said pump 230 can be of any suitable kind. Said pump 230 may be one diaphragm pump. Said pump 230 can according to one embodiment be heated with a circulating heating medium. According to one example, for example first line 271 be arranged to heat the pump 230 downstream of said container 205. According to an alternative, the pump can be heated with a circulating medium provided by dedicated equipment.

According to one embodiment, the first fluid conduit 281 is partially configured as a coil, which coil is arranged around said first conduit 271 and said third conduit 273 present in the container 205, as schematically is shown in Figure 2. With this configuration an efficient is achieved heating or melting the reductant in the container 205. The first 10 15 20 25 30 15 the fluid line 281 may alternatively have another suitable shape, for example a U-shape.

A first heating element 261 is arranged at the second line 272 to if necessary, heat the reductant present therein. A second heating element 262 is provided at the metering valve 250 to heat both if necessary 250 and third heating element 263 is arranged at the third line 273 so that when necessary the dosing valve reductant present therein. One heat the reductant present therein.

It should be pointed out that according to the invention it is possible to place one heating elements in any suitable place in the subsystem 299. Various configurations are possible to realize.

A first control unit 200 is arranged to control the operation of said first heating element 261, said second heating element 262 and said third heating element 263 in a suitable manner. Said first control unit 200 may be arranged to control operation of said first heating element 261, said second heating element 262 and said third heating element 263 independently of each other. According to one embodiment, the first control unit is arranged to activate and driving said heating element then circulating said reducing agent at The SCR system is considered suitable.

Said first control unit 200 is arranged for communication with a first temperature sensor 221 via a link L221. Said first temperature sensor 221 is arranged to detect a prevailing temperature of the reductant there the sensor is mounted. According to one embodiment, the first temperature sensor is 221 located in the immediate vicinity of the first and / or third line in the container 205. According to one embodiment, the first temperature sensor is 221 arranged in the immediate vicinity of the first and / or third line at the container 205. According to a first the temperature sensor 221 arranged in a lower part of the container 205. bottom of execution is it 10 15 20 25 30 16 The temperature sensor 221 is arranged to continuously send signals to it first control unit 200 including information about a prevailing temperature at the reductant via link L221.

The first control unit 200 is arranged for communication with the pump 230 via a link 292. The first control unit 200 is arranged to control the operation of the pump 230 to e.g. regulate flows of the reductant within the subsystem 299.

The first control unit 200 is arranged to activate circulation of said reducing agent when deemed appropriate, according to an embodiment of present invention.

The first control unit 200 is arranged for communication with dosing unit 250 via a link L250. The first control unit 200 is arranged to control operation of the dosing unit 250 to e.g. regulate supply of the reductant to the exhaust system of the vehicle 100. The first control unit 200 is arranged to activate dosing of said reducing agent when it is deemed appropriate, according to an embodiment of the present invention.

A second control unit 210 is provided for communication with the first the control unit 200 via a link L210. The second control unit 210 may be detachably connected to the first control unit 200. The second control unit 210 may be an external control unit for the vehicle 100. The second control unit 210 may be arranged to perform the innovative process steps according to the invention. The second control unit 210 can be used to overload software for the first control unit 200, in particular software for performing the innovative procedure. The second control unit 210 may alternatively be arranged for communication with the first control unit 200 via an internal network in the vehicle. The second control unit 210 may be arranged to perform substantially the same functions as the first control unit 200.

According to the embodiment schematically illustrated with reference to Figure 2 the first control unit 200 is arranged to control the pump 230 on such 10 15 20 25 30 17 at least, where applicable, at least a portion of said molten reductant extracted from the container 205 to enable heating thereof by means of at least one of the heating elements 261, 262 and 263 outside the container 205. The first control unit 200 is further arranged to control the pump 230 in such a way that the molten part of said reductant returned to the container 205 before dosing it by the dosing unit 250 is started in the SCR system.

Figure 3 schematically illustrates a part of the subsystem 299 which is described with reference to Figure 2. In Figure 3, some of the components that described with reference to Figure 2.

Said first control unit 200 is arranged for communication with a second temperature sensor 222 via a link L222. Said second temperature sensor 222 is arranged to continuously measure a prevailing temperature T2 of said fluid upstream of said container 205. Said second temperature sensor 222 is arranged to continuously send signals including information about prevailing temperature of the fluid to the first control unit 200 via said link L222. Said second temperature sensor 222 may be provided in immediate proximity to the container 205 at an upstream side thereof or at the engine of the vehicle or in a suitable place between said engine and said container 205.

Said first control unit 200 is arranged for communication with a third temperature sensor 223 via a link L223. Said third temperature sensor 223 is arranged to continuously measure a prevailing temperature T3 of said fluid downstream said container 205. Said third temperature sensor 223 is arranged to continuously send signals including information about prevailing temperature of the fluid to the first control unit 200 via said link L223. Said third temperature sensor 223 may be provided in immediate proximity to the container 205 at a downstream side thereof or at the engine of the vehicle or in a suitable place between said engine and said 10 15 20 25 30 18 container 205. According to one example, said third temperature sensor 223 be present at the pump 230.

According to one embodiment, said first control unit 200 is arranged to communicate with said temperature sensors via said second control unit 210. Which can be signal connected to said temperature sensors.

Said first conduit 281 is arranged to conduct a heating fluid to effecting melting of frozen reducing agent in the container 205. According to a For example, said first line is provided for cooling an engine of the vehicle. During said cooling of the engine, thermal energy is transferred from said motor for said fluid. According to one example, said fluid is a coolant of one engine cooling system. According to one example, said pump 230 is arranged to circulating said fluid from the engine to the container and back to the engine via wire 282 in a closed loop. It should be pointed out that said reducing agent and said warming fluid is never mixed but physically separated from said management.

According to an alternative embodiment, a vehicle external heating medium can be used. According to this embodiment, a separate container with a heater medium can be used, whereby the container can be connected to an existing one in the vehicle circulation line. In this case, either a vehicle external feeding device can or a dedicated feeding device of the vehicle is used for circulation of said heating fluid.

According to one embodiment, the first control unit 200 is arranged to on the basis of the received signals comprising a prevailing temperature T1 of the reductant at the area of the temperature sensor 221 and a prevailing one temperature T2 of the fluid upstream of said container 205 controls operation of the pump 230 and the dosing unit 250 in accordance with the innovative procedure. 10 15 20 25 30 19 According to one embodiment, the first control unit 200 is arranged to on the basis of the received signals comprising a prevailing temperature T1 of the reductant at the area of the temperature sensor 221 and a prevailing one temperature T2 of the fluid upstream of said container 205 determine one temperature difference thereof in accordance with an aspect of the innovative procedure.

According to one embodiment, the first control unit 200 is arranged to on the basis of the received signals comprising a prevailing temperature T3 of the fluid downstream said container 205 and a prevailing temperature T2 of fl uiden upstream of said container 205 determining a temperature difference thereof in in accordance with one aspect of the innovative process.

Figure 4a schematically illustrates a flow chart of a process at one SCR system comprising a circulation pump 230 and a dosing unit 250 in order to assess the need for heating in a container arranged reducing agent for exhaust gas cleaning by means of a container 205 through said container circulating warming medium and partly assess a start-up of circulation of said reducing agent in said SCR system is suitable for such heating, according to an embodiment of the invention. The procedure comprises a first process step s401. Step s401 includes the steps of: continuously determining a temperature of said reducing agent in said container 205, - continuously determine a difference between a temperature of said heating medium and the temperature of said reducing agent in said containers, or continuously determine a difference between the temperature of said heating medium upstream of said container and a temperature of said heating medium downstream of said container; and - continuously determine an accumulated amount of molten reducing agent based on said temperature difference as a basis for determining suitability for said start-up. 10 15 20 25 30 20 After the process step s401, the process is terminated.

Figure 4b schematically illustrates a flow chart of a process at one SCR system comprising a circulation pump 230 and a dosing unit 250 to assess on the one hand the need for heating in a container 205 arranged reducing agent for exhaust gas cleaning by means of a container 205 through said container circulating warming medium and partly assess a start-up of circulation of said reducing agent in said SCR system is suitable for such heating, according to an embodiment of the invention.

The method includes a first method step s410. Procedure step s410 may include the step of determining whether a reducing agent is present in the container 205 is at least partially frozen. This can be achieved by measuring the temperature of the reducing agent by means of the first temperature sensor 221. This can ambient temperature determined when the vehicle is switched off and / or alternatively achieved by considering one an ambient temperature at start-up of the vehicle. Procedure step s410 involves the step of continuously determining a temperature T1 of said reducing agent in said container. After the procedure step s410, one is performed subsequent procedure step s420.

Method step s420 includes the step of continuously determining a difference between a temperature T2 of said heating medium and the temperature T1 of said reducing agent in said container 205, or continuously determine a difference between the temperature of said heating medium upstream of said container and a temperature of container. After the process step s420 performs a subsequent process step s430. said heating medium downstream of said The method step s430 includes the step of continuously determining one accumulated amount of energy transferred to said reducing agent based on any of said temperature differences during said heating. This can 10 15 20 25 30 21 take place by means of a continuous integration of the estimated amount of energy transferred from said heating medium to said reducing agent in the container 205.

Said estimated amount of energy transferred can be based on said determined difference in temperature (T1-T2, T3-T2) multiplied by an appropriate heat transfer constant. Said heat transfer constant may be empirically established. Said heat transfer constant may be suitable value and is based on the characteristics of said reducing agent. After the process step s430 performs a subsequent process step s440.

The method step s440 includes the step of continuously determining one accumulated amount of molten reducing agent based on said temperature difference as a basis for determining suitability for said start-up. The method step s440 may include the step of determining said accumulated amount of molten reducing agent based on said accumulated transferred amount of energy and melting enthalpy of the reducing agent.

Process steps s420, s430 and s440 are performed until it is determined that start-up of pump 230 is appropriate. After the procedure step s440, one is performed subsequent step s450.

The process step s450 may include the step of, when deemed appropriate to start the pump 230 for circulating said reducing agent, start reducing agents. According to one In exemplary embodiments, it is considered appropriate to start the pump 230 when a the pump 230 for circulating said predetermined first amount of reducing agent has been thawed. Said first quantity reducing agent may be any suitable amount of reducing agent, for example 2, 5 or 10 liters. The step step s450 may include the step of 262 and / or heating reducing agent by means of the heating elements 261, 263.After the procedure step s450, a procedure step s460 is performed.

The process step s460 may include the step of, after being judged to be appropriate, start dosing of reducing agent according to in the first control unit 250. According to one stored drivers by means of said dosing unit 10 15 20 25 30 22 exemplary embodiment, it is considered appropriate to start the dosing unit 250 when a predetermined second amount of reducing agent has been thawed. Said others amount of reducing agent can be an arbitrary reducing agents, for example 12, 15 or 20 liters. appropriate amount After the procedure step s460, the procedure is terminated.

Referring to Figure 5, a diagram of an embodiment of one is shown device 500. The control units 200 and 210 described with reference to Figure 2 may in one embodiment comprise the device 500. 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 portion 530 wherein a computer program, such as an operating system, is stored for control the function of the device 500. Furthermore, the device 500 comprises a bus controller, a serial communication port, an I / O device, an A / D converter, a time and date input and transfer unit, an event counter and an interrupt controller (not shown). The non-volatile memory 520 also has a second memory part 540.

A computer program P is provided which includes routines for doing so assess the need for heating in a container arranged reducing agent for exhaust gas purification by means of a heater circulating through said container medium and partly assess whether a start-up of circulation of the said reducing agent in said SCR system is suitable for such heating.

The computer program P includes routines for continuously determining one container.

The computer program P includes routines for continuously determining a difference temperature of said reducing agent in said between a temperature of said heating medium and the temperature of said reducing agent in said container. Alternatively include computer program P routines to continuously determine a difference between the temperature of said heating medium upstream of said container 10 15 20 25 30 23 205 and a temperature of said heating medium downstream of said container 205. The computer program P includes routines for continuous determining an accumulated amount of molten reducing agent based on said temperature difference as a basis for determining suitability for said start-up. The computer program P includes routines for continuous determining an accumulated amount of energy transferred to said reducing agent based on said temperature difference during said heating.

The computer program P includes routines for determining the said accumulated amount of molten reducing agent based on said accumulated transferred amount of energy and melting enthalpy of the reducing agent.

The computer program P includes routines for judging the start-up of the said circulating pump is suitable for a certain determined accumulated amount of melt reducing agents. The computer program P includes routines for starting dosing of said reducing agent at a certain accumulated amount of melt reducing agents.

The program P can be stored in an executable way or in a compressed way in a memory 560 and / or in a read / write memory 550.

When it is described that the data processing unit 510 performs a certain function it should be understood that the data processing unit 510 performs a certain part of the program which is stored in the memory 560, or a certain part of the program which is stored in the read / write memory 550.

The data processing device 510 can communicate with a data port 599 via a data bus 515. The non-volatile memory 520 is for communication 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 data processing unit 510 via a data bus 514. To the data port 599 can for example links L210, L221, L222 and L223 are connected (see Figure 2 and Figure 3).

The read / write memory 550 is arranged to communicate with 10 15 20 25 24 When data is received on data port 599, it is temporarily stored in the other 540. When the data processing unit 510 is prepared to perform code execution on the memory part received input data has been temporarily stored, is a manner described above. According to one embodiment, signals include received on the data port 599 information about a prevailing temperature T1 at the reducing agent in the container 205. According to one embodiment, it comprises signals received on the data port 599 information about a prevailing temperature T2 of said heating medium upstream of the container 205. According to one embodiment includes signals received at the data port 599 information about a current temperature T2 of said heating medium downstream of the container 205.

Parts of the methods described herein may be performed by the device 500 by means of of the data processing unit 510 running the program stored in the memory 560 or read / write memory 550. When the device 500 is running the program, it is executed procedures described herein.

The foregoing description of the preferred embodiments of the present invention has been provided for the purpose of illustrating and describing the invention. It is not intended to be exhaustive or restrictive the invention to the described variants. Obviously many will come modifications and variations to be apparent to those skilled in the art. The embodiments was selected and described to best explain the principles of the invention and its practical applications, thus enabling professionals to understand the invention for different embodiments and with the different modifications as are suitable for the intended use.

Claims (14)

10 15 20 25 30 25 PATENT REQUIREMENTS A method of an SCR system comprising a circulation pump (230) and a dosing unit (250) for assessing, on the one hand, the need for heating in a container (205) arranged for exhaust gas purification by means of a heating medium circulating through said container (205) and secondly, assessing whether a start-up of circulation of said reducing agent in said SCR system is suitable for such heating, including the step of: (S410) a (T1) of reducing agent in said container (205), - continuously determining the temperature said characterized by the steps of: : - continuously determining (S420) a difference between a temperature (T2) of said heating medium and the temperature (T1) of said reducing agent in said container (205), or - continuously determining (S420) a difference between the temperature (T2) of said heating medium upstream of said container (205) and a temperature (T3) of said heating medium downstream of said container (205); and continuously determining (S440) an accumulated amount of molten reducing agent based on said temperature difference as a basis for determining suitability for said start-up. The method of claim 1, further comprising the step of: - continuously determining (S430) an accumulated amount of energy transferred to said reducing agent based on said temperature difference during said heating. The method of claim 2, further comprising the step of: - determining (S430) said accumulated amount of molten reducing agent based on said accumulated amount of energy transferred and the melting enthalpy of the reducing agent. 10 15 20 25 30 26 A method according to any one of the preceding claims, wherein start-up (s450) of said circulation pump is judged suitable for a certain determined accumulated amount of molten reducing agent. A method according to any one of the preceding claims, further comprising the step of: - starting dosing (s460) of said reducing agent at a certain accumulated amount of molten reducing agent. An SCR system comprising: - a circulation pump (230); - a dosage unit (250); means (200; 210; 500) adapted to assess the need to heat reducing agent arranged in a container (205) for exhaust gas purification by means of a heating medium circulating through said container (205) and to assess whether a start-up of circulation of said reducing agent in said SCR system is suitable for such heating; means (221) adapted to continuously determine a temperature (T1) of said reducing agent in said container (205), characterized by: - means (200; 210; 500) adapted to continuously determine a difference between a temperature (T2) of said heating medium and the temperature (T1) of said reducing agent in said container (205), or means (200; 210; 500) adapted to continuously determine a difference between the temperature (T2) of said heating medium upstream of said container (205) and a temperature (T3) of said heating medium downstream of said container (205); and - means (200; 210; 500) adapted to continuously determine an accumulated amount of molten reducing agent based on said temperature difference as a basis for determining suitability for said start-up. The SCR system of claim 6, further comprising: means (200; 210; 500) adapted to continuously determine an accumulated amount of energy transferred to said reducing agent based on said temperature difference during said heating. The SCR system of claim 7, further comprising: - means (200; 210; 500) adapted to determine said accumulated amount of molten reducing agent based on said accumulated amount of energy transferred and the melting enthalpy of the reducing agent. An SCR system according to any one of claims 6-8, comprising - means (200; 210; 500) adapted to judge that start-up of said circulation pump (230) is suitable at a certain determined accumulated amount of molten reducing agent. The SCR system of any of claims 6-9, further comprising: - means (200; 210; 500) adapted to initiate dosing of said reducing agent at a certain accumulated amount of molten reducing agent. A motor vehicle (100; 110) comprising an SCR system according to any one of claims 6-10. A motor vehicle (100; 110) according to claim 11, wherein the motor vehicle is something of a truck, bus or passenger car. Computer program (P) in an SCR system, wherein said computer program (P) comprises program code for causing an electronic control unit (200; 500) or another computer (210; 500) connected to the electronic control unit (200; 500) performing the steps according to any one of claims 1-5. A computer program product comprising a program code stored on a computer readable medium for performing the method steps according to any one of claims 1-5, when said computer program is run on an electronic control unit 28 (200; 500) or another computer (210; 500). ) connected to the electronic control unit (200; 500).