WO2015072918A1

WO2015072918A1 - Method and system at cold start of a motor vehicle

Info

Publication number: WO2015072918A1
Application number: PCT/SE2014/051365
Authority: WO
Inventors: Martin KLASSON; Klara EKEBERG; Thomas COLTON
Original assignee: Scania Cv Ab
Priority date: 2013-11-18
Filing date: 2014-11-18
Publication date: 2015-05-21

Abstract

The invention relates to a method at the cold start of a motor vehicle (100), wherein said motor vehicle (100) comprises a combustion engine (231) and an exhaust purification system comprising an SCR catalyst (265), as well as a first control function to force a temperature increase in the exhausts from said combustion engine (231). The method comprises the steps to: - continuously (s410) determine a prevailing temperature (T1; T2; T3; T4; T5; Tmod) of said exhaust purification system, - deactivate (s430) said first control function, when the determined temperature (T1; T2; T3; T4; T5; Tmod) of said exhaust system falls below a predetermined value (TH1); and - activate (s440) a second control function, with the objective of achieving a relatively slow increase of said temperature (T1; T2; T3; T4; T5; Tmod) in said exhaust purification system. The invention also relates to a computer program product comprising program code (P) for a computer (200; 210) to implement a method according to the invention. The invention also relates to a system at the cold start of a motor vehicle (100) and a motor vehicle (100) equipped with said system.

Description

Method and system at cold start of a motor vehicle

TECHNICAL FIELD

The present invention relates to a method at the cold start of a motor vehicle. The invention also relates to a computer program product, comprising program code for a computer, to implement a method according to the invention. The invention also relates to a system at the cold start of a motor vehicle, and a motor vehicle equipped with said system.

BACKGROUND

In vehicles today, e.g. urea is used as a reducing agent in SCR systems (Selective Catalytic Reduction) comprising an SCR catalyst, in which catalyst said reducing agent and NO_x gas (nitrogen oxides) may react and transform into nitrogen and water. Different types of reducing agents may be used in SCR systems. A commonly occurring reducing agent is e.g. AdBlue.

In one type of SCR system a container holding a reducing agent is comprised. The SCR system also has a pump, which is arranged to pump said reducing agent from the container via a suction hose, and add it via a pressurised hose to a dosage device, which is arranged in an exhaust system of a vehicle, e.g. in a silencer of the exhaust system. The dosage device is arranged to feed a suitable amount of reducing agent into the silencer upstream of the SCR catalytic converter, according to operational procedures stored in a control device of the vehicle. In order to control the pressure at small or no dosage amounts more easily, the system also has a return flow hose, arranged to go from a pressure side of the system back to the container.

At cold start of vehicles equipped with SCR systems, NO gas is stored in the SCR catalyst. The term cold start relates to temperatures in the exhaust system, which fall below 50 degrees Celsius. Said exhaust system may also be called an after- treatment system. When, following cold start, the exhaust system is heated successively from a relatively low temperature, e.g. 5 degrees Celsius, said stored NO gas transforms into NO₂ gas. Said NO₂ gas is yellowish and also a health hazard. Said NO2 gas impacts humans and the environment negatively, in particular when the vehicle is cold started inside a closed space with poor ventilation, such as a garage.

Today, a function is used in vehicles which may be referred to as a white smoke limiter. This function may be stored in a control device of the vehicle in the form of program code. White smoke limiters are arranged to increase the temperature of the exhaust system in order to facilitate, relatively quickly, activation of e.g. said SCR catalyst. When said SCR catalyst is active and in operation, the SCR system may be operated in a desirable manner, in order to reduce the amount of emissions from said vehicle.

US20120004833 describes a method to operate a combustion engine with an emission control system.

US20120004825 describes a method to operate a combustion engine comprising an emission control system and an SCR catalyst.

SUMMARY OF THE INVENTION

One objective of the present invention is to provide a novel and advantageous method at the cold start of a motor vehicle.

Another objective of the invention is to provide a novel and advantageous system at the cold start of a motor vehicle and a novel and advantageous computer program for said system.

Another objective of the invention is to provide a method, a system and a computer program to facilitate environmentally friendly cold start of a vehicle with an SCR system. Another objective of the invention is to provide an alternative method at the cold start of a motor vehicle, an alternative system at the cold start of a motor vehicle and an alternative computer program for said system.

These objectives are achieved with a method at the cold start of a motor vehicle according to claim 1 . Other objectives are achieved with a system according to claim 10. Advantageous embodiments are specified in the dependent claims.

According to one aspect of the invention, a method at the cold start of a motor vehicle is provided, wherein said motor vehicle comprises a combustion engine and an exhaust purification system comprising an SCR catalyst, as well as a first control function, in order to force a temperature rise in exhausts from said combustion engine. The method comprises the steps:

- to continuously determine a prevailing temperature of said exhaust purification system,

- to deactivate said first control function, when the determined temperature of said exhaust system falls below a predetermined value; and

- to activate a second control function with the objective of achieving a relatively slow increase of said temperature in said exhaust purification system.

Said first control function is a so-called white smoke limiter. Said second control function is a so-called yellow smoke limiter. By actively maintaining, according to one aspect of the present invention, the white smoke limiter forcedly disabled when the yellow smoke limiter is on, a reduction of emissions from the vehicle in the form of NO₂ may advantageously be achieved at cold start of the vehicle. After the exhaust system has achieved a predetermined suitable temperature, said yellow smoke limiter may be deactivated and said white smoke limiter may be activated, so that normal starting logic may be used.

The method may comprise the step to:

- via said first control function, achieve said forced temperature rise through activation of an exhaust brake in said engine. Here, a robust and efficient manner of increasing the temperature of exhausts from said engine is achieved. Said first control function may be activated manually by an operator of the vehicle, with a push button intended for this purpose or another suitable means. According to the inventive method this may, however, occur only once a suitable temperature of the SCR catalyst has been achieved. Hereat, a suitable point in time for activation of said first control function may be indicated for said operator in a suitable manner at cold start of said motor vehicle. Activation of said first control function may, according to the inventive method, occur only after a certain suitable temperature has been achieved in said SCR catalyst, e.g. 40 or 50 degrees Celsius. According to one alternative embodiment, said first control function is activated automatically after said second control function has been deactivated.

The method may comprise the step to:

- via said first control function, achieve said forced temperature rise through control of the fuel supply to said combustion engine. Here, a robust and efficient manner of increasing the temperature of exhausts from said engine is achieved. By supplying an excess of fuel to said engine, which fuel entails an increased heat development in the exhaust system, devices in the exhaust system, e.g. a DOC device and said SCR catalyst, may achieve a suitable operating temperature relatively quickly. By controlling the point in time for supply of fuel to said engine, an amplified heat development may be achieved in the exhaust system. Thus, devices in the exhaust system, e.g. a DOC device and said SCR catalyst, may relatively quickly achieve a suitable operating temperature.

The method may comprise the step to:

- via said second control function, achieve said relatively slow increase of said temperature in said exhaust purification system through deactivation of an exhaust brake in said engine. Thus, transformation of NO stored in said SCR catalyst into NO2 may be reduced/minimised/eliminated efficiently.

The method may comprise the step to:

- via said second control function, achieve said relatively slow increase of said temperature in said exhaust purification system through control of the fuel supply to said combustion engine. Thus, transformation of NO stored in said SCR catalyst into NO2 may be reduced/minimised/eliminated efficiently. The method may comprise the step to:

- deactivate said second control function, when the determined temperature in said exhaust system exceeds said predetermined value. Hereat, said first control function may be activated to achieve a relatively quick temperature rise in the vehicle's exhaust system, in order to facilitate reduction of emissions with said SCR system. Here, an environmentally friendly method is achieved at cold start of said vehicle.

The method may comprise the step to:

- determine a temperature of said SCR catalyst based on said temperature of said exhaust purification system. Said temperature of said SCR catalyst may be

determined based on a temperature of any suitable component of said exhaust purification system. Said temperature of said SCR catalyst may be determined based on a temperature of exhausts from said engine. According to one alternative embodiment, said temperature of said SCR catalyst may be determined with a calculation model stored in a control device of said vehicle. Thus, a robust and versatile method for cold start of a motor vehicle is achieved.

The method may comprise the step to:

- apply said relatively slow temperature rise within a predetermined temperature range. Said predetermined temperature range may be defined by 20-40 degrees Celsius. Said first control function will only be shut off during a limited time period, which advantageously entails that normal operating procedures may be activated without any significant delay, after said second control function has been activated at the cold start of said motor vehicle.

The method may be implemented in existing motor vehicles. A program code for a system for cold start of a motor vehicle according to the invention may be installed in a control device of the vehicle during manufacture of the same. A purchaser of the vehicle may thus be afforded the opportunity to select the method performance function as an extra option. Alternatively, a program code to perform the method according to the invention in said system for cold start of a motor vehicle may be installed in a control device of the vehicle, when upgraded at a service station. In this case, said program code may be uploaded into a memory in the control device. Implementation of the inventive method is thus cost effective. The invention thus provides a cost effective solution to the above problems.

A program code for a system for cold start in a motor vehicle may be updated or replaced. In addition, different parts of said program code for said system may be replaced independently of each other. This modular configuration is advantageous from a maintenance perspective.

According to one aspect of the present invention, a system is provided at cold start of a motor vehicle, wherein said system comprises a combustion engine and an exhaust purification system comprising an SCR catalyst, as well as a first control function adapted to force a temperature rise in exhausts from said combustion engine. The system comprises:

- elements to continuously determine a prevailing temperature of said exhaust purification system;

- elements adapted to deactivate said first control function, when the determined temperature of said exhaust system falls below a predetermined value; and

- elements adapted to activate a second control function with the objective of achieving a relatively slow increase of said temperature in said exhaust purification system.

The system may comprise:

- elements adapted, via said first control function, to achieve said forced temperature rise through activation of an exhaust brake in said engine.

The system may comprise:

- elements adapted, via said first control function, to achieve said forced temperature rise through control of the fuel supply to said combustion engine.

The system may comprise:

- elements adapted, via said second control function, to achieve said relatively slow increase of said temperature in said exhaust purification system through deactivation of an exhaust brake in said engine. The system may comprise:

- elements adapted, via said second control function, to achieve said relatively slow increase of said temperature in said exhaust purification system through control of the fuel supply to said combustion engine.

The system may comprise:

- elements adapted to deactivate said second control function, when the determined temperature in said exhaust system exceeds said predetermined value.

The system may comprise:

- elements adapted to determine a temperature of said SCR catalyst, based on said temperature of said exhaust purification system.

The system may comprise:

- elements adapted to apply said relatively slow temperature rise within a

predetermined temperature range.

According to one aspect of the present invention, a motor vehicle is provided, comprising said system for cold start of said motor vehicle.

Said motor vehicle may be a truck, a bus or a car.

According to one aspect of the present invention, a computer program is provided for cold start of a motor vehicle, wherein said system comprises a combustion engine and an exhaust purification system comprising an SCR catalyst, as well as a first control function adapted to force a temperature rise of the exhausts from said combustion engine, wherein said computer program comprises program code stored in a computer-readable medium, in order to cause an electronic control device, or another computer connected to the electronic control device, to perform the steps according to any of claims 1 -9.

According to one aspect of the present invention, a computer program is provided for cold start of a motor vehicle, wherein said system comprises a combustion engine and an exhaust purification system comprising an SCR catalyst, as well as a first control function adapted to force a temperature rise of the exhausts from said combustion engine, wherein said computer program comprises program code to cause an electronic control device, or another computer connected to the electronic control device, to perform the steps according to any of claims 1 -9.

According to one aspect of the present invention, a computer program is provided for cold start of a motor vehicle, wherein said computer program comprises program code in order to cause an electronic control device, or another computer connected to the electronic control device, to perform the steps according to any of claims 1 -9.

According to one aspect of the present invention, a computer program product is provided comprising program code stored in a computer-readable medium to perform the method steps according to any of the claims 1 -9, when said program code is executed in an electronic control device, or in another computer connected to the electronic control device.

Additional objectives, advantages and novel features of the present invention will be apparent to one skilled in the art from the following details, and through exercising the invention. While the invention is described below, it should be apparent that the invention is not limited to the specifically described details. One skilled in the art, having access to the teachings herein, will recognise additional applications, modifications and incorporations in other areas, which are within the scope of the invention.

DETAILED DESCRIPTION OF THE FIGURES

A side view of a vehicle 100 is shown with reference to Figure 1 . The exemplary vehicle 100 consists of a tractor 1 10 and a trailer 1 12. The vehicle may be a heavy goods vehicle, such as a truck or a bus. The vehicle may also be a car.

It should be pointed out that the invention is suitable for application in a platform with any suitable SCR system, and is therefore not limited to SCR systems of motor vehicles. The method according to the invention and the system according to the invention are well suited, according to one aspect of the invention, to platforms other than motor vehicles that comprise an SCR system, e.g. watercraft. The watercraft may be of any suitable type, such as motor boats, ships, ferries or vessels.

The method according to the invention and the system according to the invention are also well suited, according to one aspect of the invention, for e.g. systems comprising industrial engines and/or engine-driven industrial robots.

The method according to the invention and the system according to the invention are also well suited, according to one aspect of the invention, for different types of power plants, e.g. electricity production plants comprising a diesel generator.

The method according to the invention and the system according to the invention are also well suited for any suitable motor system comprising an engine, such as e.g. in a locomotive or another platform.

The method according to the invention and the SCR system according to the invention are also well suited to any suitable system which comprises an NO_x generator.

The term "link" herein refers to a communications link, which may be a physical line, such as an opto-electronic communication line, or a non-physical line, such as a wireless connection, e.g. a radio or microwave link.

The term "conduit" herein means a passage to hold and transport a fluid, such as a reducing agent in liquid form. The conduit may be a conduit of any dimension. The conduit may consist of any suitable material, such as plastic, rubber or metal.

The terms "reducing agent" or "reductant", as used herein, mean a substance used to react with certain emissions in an SCR system. These emissions may e.g. be NO_x gas. The terms "reductant" and "reducing agent" are used synonymously herein. Said reducing agent is, according to one embodiment, also known as AdBlue. Obviously other types of reducing agents may be used. Herein, AdBlue is provided as an example of a reducing agent, but a person skilled in the art will realise that the method according to the invention, and the system according to the invention, may be realised for other types of reducing agent, with the required adaptations in control algorithms in order to execute program code in accordance with the method according to the invention.

Figure 2 shows a sub-system 299 in the vehicle 100.

The sub-system 299 is arranged in the tractor 1 10. The sub-system 299 may form part of an SCR system. The sub-system 299 comprises, according to this example, a container 205 which is arranged to hold a reducing agent. The container 205 is arranged to comprise a suitable amount of reducing agent and is also arranged to be filled as needed.

A first conduit 271 is arranged to lead the reducing agent to a pump 230 from the container 205. The pump 230 may be any suitable pump. The pump 230 may be arranged to be operated by an electric motor. The pump 230 may be arranged to pump the reducing agent from the container 205, via the first conduit 271 and via a second conduit 272, to add said reducing agent to a dosage device 250. The dosage device 250 comprises an electrically controlled dosage valve, through which a flow of reducing agent added to the exhaust system may be controlled. The pump 230 is arranged to pressurise the reducing agent in the second conduit 272. The dosage device 250 is arranged with a throttle device, against which said pressure of the reducing agent is built up in the sub-system 299.

The dosage device 250 is arranged to add said reducing agent to an exhaust system (see Fig. 3) in the vehicle 100. More precisely, the dosage device 250 is arranged to, in a controlled manner, add a suitable amount of reducing agent to an exhaust system in the vehicle 100. According to this embodiment, an SCR catalyst (see Fig. 3) is arranged downstream of a position in the exhaust system where supply of the reducing agent is achieved. The amount of reducing agent added to the exhaust system is intended to reduce the amount of undesired emissions, in a prior art manner. The dosage device 250 is arranged at e.g. an exhaust conduit, which is arranged to lead exhausts from a combustion engine (see Fig. 3) of the vehicle 100 to the SCR catalyst.

A third conduit 273 is arranged between the dosage device 250 and the container 205. The third conduit 273 is arranged to lead back a certain amount of the reducing agent, which has been fed to the dosage device 250, to the container 205. With this configuration, cooling of the dosage device 250 is advantageously achieved. Thus, the dosage device 250 is cooled with a flow of the reducing agent, when this is pumped through the dosage device 250 from the pump 230 to the container 205.

The first control device 200 is arranged for communication with the pump 230 via a link L292. The first control device 200 is arranged to control the operation of the pump 230, in order to e.g. control the flow of the reducing agent within the subsystem 299. The first control device 200 is arranged to control an operating power of the pump 230, by controlling the electric engine thereat.

The first control device 200 is arranged for communication with the dosage device 250 via a link L250. The first control device 200 is arranged to control the operation of the dosage device 250, in order to e.g. control the supply of reducing agent to the exhaust system of the vehicle 100. The first control device 200 is arranged to control the operation of the dosage device 250, in order to e.g. control the resupply of reducing agent to the container 205.

The first control device 200 may be arranged to deactivate said first control function, when a determined temperature of said exhaust system falls below a predetermined value, and to activate a second control function with the objective of achieving a relatively slow increase of said temperature in said exhaust purification system.

A second control device 210 is arranged for communication with the first control device 200 via a link L210. The second control device 210 may be detachably connected to the first control device 200. The second control device 210 may be a control device external to the vehicle 100. The second control device 210 may be arranged to carry out the method steps according to the invention. The second control device 210 may be used to transfer program code to the first control device 200, in particular program code to perform the method according to the invention. Alternatively, the second control device 210 may be arranged for communication with the first control device 200 via an internal network in the vehicle. The second control device 210 may be arranged to carry out substantially similar functions to the first control device 200, e.g. to deactivate said first control function when a determined temperature of said exhaust system falls below a predetermined value, and to activate a second control function with the objective of achieving a relatively slow increase of said temperature in said exhaust purification system. The method according to the invention may be carried out by the first control device 200, or by the second control device 210, or by both the first control device 200 and the second control device 210.

Figure 3 schematically illustrates a sub-system 289 of the vehicle 100 shown in Figure 1 , according to one embodiment of the invention. The sub-system 289 may constitute a part of the system according to the invention.

At operation, an engine 231 causes an exhaust flow, which is led to an after- treatment device 260 via a first passage 235. Said after-treatment device 260 may comprise a DOC device (Diesel Oxidation Catalyst) and a DPF device (Diesel Particulate Filter). Said DOC device is arranged upstream of said DPF device. A second passage 245 is arranged to lead said exhausts from said after-treatment device 260 to an SCR catalyst arrangement 265. Said SCR catalyst arrangement 265 comprises an evaporation module and a catalyst section. Said SCR catalyst arrangement 265 may comprise an end catalyst. A third passage 255 is arranged to lead exhausts to an environment of the vehicle 100 from said SCR catalyst arrangement 265.

Herein, an evaporation module is described, comprising an area upstream of said catalyst section, where the fed reducing agent may be evaporated.

The first control device 200 is arranged for communication with the engine 231 via a link L231 . The first control device 200 is arranged to control the operation of said engine 231 . The first control device 200 is arranged to control the supply of fuel to said engine 231 . Hereat, e.g. the injection timing, injection angle and/or supplied amount of fuel may be controlled.

The first control device 200 is arranged for communication with an exhaust brake 220 via a link L220. The first control device 200 is arranged to control said exhaust brake 220 in accordance with the inventive method.

According to one example, the first control device 200 is arranged to activate said exhaust brake when said first control function is active. Hereat, said exhaust brake is controlled in such a way, that a current load of said engine 231 corresponds to a relatively high load. Hereat, a temperature of exhausts from said engine 231 may be increased in an efficient manner.

According to one example, the first control device 200 is arranged to deactivate said exhaust brake, when said second control function is active. Hereat, said exhaust brake is controlled in such a way that a current load of said engine 231 corresponds to a relatively low load. Hereat, a temperature of exhausts from said engine 231 may be increased relatively slowly, entailing that the amount of yellow smoke from said third passage 255 may be kept to a minimum, according to one aspect of the present invention.

The first control device 200 comprises a stored first control function, which is arranged to achieve a sharp/rapid temperature rise in exhausts from said engine 231 in a suitable manner. This first control function is referred to herein as a white smoke limiter. The first control device 200 comprises a stored second control function, which is arranged to achieve a relatively slow temperature rise in exhausts from said engine 231 in a suitable manner. This second control function is referred to herein as a yellow smoke limiter.

According to one embodiment, the first control device 200 is arranged to deactivate said white smoke limiter at a determined cold start of the vehicle 100, and to activate said yellow smoke limiter. According to one embodiment, the first control device 200 is arranged to, when a temperature of the SCR catalyst arrangement 265 exceeds a predetermined value, deactivate said yellow smoke limiter and to activate said white smoke limiter. According to one embodiment, the first control device 200 is arranged to, when a temperature of the SCR catalyst arrangement 265 exceeds a predetermined value, deactivate said yellow smoke limiter and to allow said white smoke limiter to remain deactivated.

The first control device 200 is, according to one embodiment, arranged to automatically switch between said white smoke limiter and yellow smoke limiter, according to the inventive method. The first control device 200 is, according to one embodiment, arranged to automatically deactivate said white smoke limiter and to activate said yellow smoke limiter, according to the inventive method, and to automatically deactivate said yellow smoke limiter and allow manual activation of said white smoke limiter, when an operator of the vehicle 100 finds this suitable.

The first control device 200 is arranged to control the operation of the dosage device 250, in order to feed reducing agent into the first passage 235. Said evaporation module is arranged to evaporate said fed reducing agent, in order to achieve a mixture of exhausts and reducing agent for the treatment with said SCR section.

A first ΝΟχ sensor (not displayed) may be arranged upstream of said after-treatment device 260 at said first passage 235. Said first NO_x sensor is arranged for communication with the first control device 200 via a link intended for this purpose. The first NO_x sensor is arranged to continuously determine a prevailing NO_x level in the first passage 235. The first NO_x sensor is arranged to continuously send signals comprising information about a prevailing NO_x level to the first control device 200 via said link.

A second NO_x sensor (not displayed) may be arranged downstream of said SCR catalyst arrangement 265 at said third passage 255. Said second NO_x sensor is arranged for communication with the first control device 200 via a link intended for this purpose. The second NO_x sensor is arranged to continuously determine a prevailing NO_x level in the third passage 255. The second NO_x sensor is arranged to continuously send signals comprising information about a prevailing NO_x level to the first control device 200 via said link. According to one embodiment, the first control device 200 may be arranged to determine a prevailing NO_x level (including the fraction of NO and NO2) in the first passage 235 and the third passage 255, with the use of a calculation model stored in a memory.

Said first NO_x sensor and said second NO_x sensor may be used to provide information about the prevailing level of NO and NO2 in the first passage 235 and the third passage 255. Hereat, the first control device 200 may be arranged to control e.g. the fuel supply to said engine 231 and/or said exhaust brake 220 in a suitable manner, based on information thereon. Such control is carried out with the white smoke limiter and the yellow smoke limiter in a suitable manner.

A sensor (not displayed) to measure a prevailing exhaust mass flow MF may be arranged in the first passage 235. Said exhaust mass flow sensor is arranged to continuously determine a prevailing exhaust mass flow MF in the first passage 235, and to send signals comprising information thereon to the first control device 200 via a link intended for this purpose (not displayed). According to one alternative embodiment, said prevailing exhaust mass flow may be calculated/modelled/estimated with the first control device 200 in a suitable manner. According to another example, said exhaust mass flow MF may be determined based on information about air intakes on the inlet side of the engine 231 . This may be determined with a suitable air mass meter (not displayed).

According to one embodiment, the first control device 200 is arranged to, via a calculation model stored therein, determine a prevailing exhaust mass flow MF in the first passage 235. Said prevailing exhaust mass flow MF in the first passage 235 may be determined based on e.g. a determined operating mode of the engine 231 .

A first temperature sensor 227 is arranged upstream of said after-treatment device 260 at said first passage 235. The first temperature sensor 227 is arranged for communication with the first temperature control device 200 via a link L227. Said first temperature sensor 227 is arranged to continuously determine a prevailing temperature T1 of the exhausts in the first passage 235. Said first temperature sensor 227 is arranged to continuously send signals comprising information about a prevailing temperature T1 of the exhausts to the first control device 200 via the link L227.

According to one embodiment, the first control device 200 is arranged, with a calculation model stored therein, to determine a prevailing temperature T1 of the exhausts in the first passage 235. Said prevailing temperature T1 of the exhausts in the first passage 235 may be determined based on e.g. a determined exhaust mass flow and a measure of the amount of fuel fed to the engine 231 .

A second temperature sensor 237 is arranged in said after-treatment device 260. Said second temperature sensor 237 may be arranged between said DOC device and said DPF device. Said second temperature sensor 237 is arranged for communication with the first control device 200 via a link L237. Said second temperature sensor 237 is arranged to continuously determine a prevailing temperature T2 of said after-treatment device 260. Said second temperature sensor 237 is arranged to continuously send signals comprising information about a prevailing temperature T2 of said after-treatment device 260 to the first control device 200 via the link L237.

According to one embodiment, the first control device 200 is arranged, with a calculation model stored therein, to determine a prevailing temperature T2 in said after-treatment device 260. Said prevailing temperature T2 of said after-treatment device 260 may be determined based on e.g. a determined exhaust mass flow MF and a measure of the amount of fuel fed to the engine 231 .

A third temperature sensor 247 is arranged downstream of said after-treatment device 260 at said second passage 245. Said third temperature sensor 247 is arranged for communication with the first control device 200 via a link L247. Said third temperature sensor 247 is arranged to continuously determine a prevailing temperature T3 of the exhausts in the second passage 245. Said third temperature sensor 247 is arranged to continuously send signals comprising information about a prevailing temperature T3 of the exhausts to the first control device 200 via the link L247. According to one embodiment, the first control device 200 is arranged, with a calculation model stored therein, to determine a prevailing temperature T3 of the exhausts in the second passage 245. Said prevailing temperature T3 of the exhausts in the second passage 245 may be determined based on e.g. a determined exhaust mass flow MF and a measure of the amount of fuel fed to the engine 231 .

A fourth temperature sensor 257 is arranged in said SCR catalyst arrangement 265. Said fourth temperature sensor 257 is arranged for communication with the first control device 200 via a link L257. Said fourth temperature sensor 257 is arranged to continuously determine a prevailing temperature T4 of said SCR catalyst arrangement 265. Said fourth temperature sensor 257 is arranged to continuously send signals comprising information about a prevailing temperature T4 of said SCR catalyst arrangement 265 to the first control device 200 via the link L257.

According to one embodiment, the first control device 200 is arranged, with a calculation model stored therein, to determine a prevailing temperature T4 of said SCR catalyst arrangement 265. Said prevailing temperature T4 of said SCR catalyst arrangement 265 may be determined based on e.g. a determined exhaust mass flow MF and a measure of the amount of fuel fed to the engine 231 .

A fifth temperature sensor 267 is arranged downstream of said SCR catalyst arrangement 265 at said third passage 255. Said fifth temperature sensor 267 is arranged for communication with the first control device 200 via a link L267. Said fifth temperature sensor 267 is arranged to continuously determine a prevailing temperature T5 of the exhausts in the third passage 255. Said fifth temperature sensor 267 is arranged to continuously send signals comprising information about a prevailing temperature T5 of the exhausts to the first control device 200 via the link L267.

According to one embodiment, the first control device 200 is arranged, with a calculation model stored therein, to determine a prevailing temperature T5 of the exhausts in the third passage 265. Said prevailing temperature T5 of the exhausts in the third passage 255 may be determined based on e.g. a determined exhaust mass flow MF and a measure of the amount of fuel fed to the engine 231 . The first control device 200 is arranged, with a model stored therein, to continuously estimate a prevailing temperature Tmod of said catalyst section in said SCR catalyst in said SCR catalyst arrangement 265. The first control device 200 is arranged, with a model stored therein, to continuously estimate a prevailing temperature Tmod of said catalyst arrangement 265. The first control device 200 is arranged with said model to calculate a prevailing temperature TMod of the SCR catalyst arrangement 265, based on said determined temperature T1 of the exhausts in the first passage 235. The first control device 200 is arranged to, with the use of said model, calculate a prevailing temperature Tmod of the SCR catalyst arrangement 265, based on said determined temperature T2 of the after-treatment device 260. The first control device 200 is arranged to, with the use of said model, calculate a prevailing temperature Tmod of the SCR catalyst arrangement 265, based on said determined temperature T3 of the exhausts in the second passage 245. The first control device 200 is arranged to, with the use of said model, calculate a prevailing temperature Tmod of said SCR catalyst arrangement 265, based on said determined temperature T5 of the exhausts in the third passage 255.

The first control device 200 is arranged to determine a prevailing temperature of said SCR catalyst arrangement 265, based on at least one of the temperatures T1 -T5 and Tmod.

The first control device 200 is arranged to measure/detect/determine/calculate/model a prevailing temperature of said SCR catalyst arrangement in a suitable manner. For example, said temperature may be determined based on a prevailing temperature of the vehicle's engine 231 at the start-up of said vehicle 100. For example, said temperature may be determined based on a prevailing outdoor temperature at the start-up of said vehicle 100. For example, said temperature may be determined based on the accumulated calculated heat development of the vehicle's engine 231 at a cold start process of said vehicle 100.

The first control device 200 is arranged to activate and deactivate said white smoke limiter and said yellow smoke limiter, based on said determined temperature of said SCR catalyst arrangement 265. The first control device 200 is arranged to activate and deactivate said first control function and said second control function, based on said determined temperature of said SCR catalyst arrangement 265.

The first control device 200 is arranged to handle the operation of said motor vehicle at a cold start thereof, where said motor vehicle comprises a combustion engine and an exhaust purification system comprising an SCR catalyst, as well as a first control function in order to force a temperature rise in exhausts from said combustion engine

The first control device 200 is arranged, with a suitable temperature sensor configuration, to continuously determine a prevailing temperature of said exhaust purification system. The first control device 200 is arranged to deactivate said first control function, when the determined temperature of said exhaust system falls below a predetermined value TH1 . Said predetermined value TH1 is a suitable value. Said predetermined value TH1 may be 50 degrees Celsius. Said predetermined value TH1 may be 40 degrees Celsius. Said predetermined value TH1 may be 20 degrees Celsius. Said predetermined value TH1 may be 0 degrees Celsius.

The first control device 200 is arranged to activate a second control function with the objective of achieving a relatively slow increase of said temperature in said exhaust purification system.

The first control device 200 is arranged to, via said first control function, achieve said forced temperature rise through activation of an exhaust brake in said engine 231 .

The first control device 200 is arranged to, via said first control function, achieve said forced temperature increase through control of the fuel supply to said combustion engine 231 .

The first control device 200 is arranged to, via said second control function, achieve said relatively slow increase of said temperature in said exhaust purification system through deactivation of an exhaust brake in said engine 231 . The first control device 200 is arranged to, via said second control function, achieve said relatively slow increase of said temperature in said exhaust purification system through control of the fuel supply to said combustion engine 231 .

The first control device 200 is arranged to deactivate said second control function, when the determined temperature T of said exhaust system exceeds a

predetermined value TH2. Said second predetermined value TH2 is a suitable value. Said second predetermined value does not fall below 40 degrees Celsius. Said second predetermined value TH2 may be equal to said first predetermined value TH1 . Said second predetermined value TH2 is greater than or equal to said first

predetermined value TH1 .

The first control device 200 is arranged to determine a temperature of said SCR catalyst based on at least some suitable temperature of the vehicle, reflecting a prevailing temperature of said exhaust purification system, and in particular reflecting a prevailing temperature of said SCR catalyst arrangement 265.

According to one embodiment, said first control device 200 is arranged to determine a prevailing temperature of the surrounding air of the vehicle 100, as well as any elapsed time during which the vehicle 100 was exposed to such temperature, if applicable. Hereat, the first control device 200 is arranged to calculate a prevailing temperature of the SCR catalyst arrangement 265, based on said ambient

temperature and exposure duration. The first control device 200 is, according to one example embodiment, arranged to activate said yellow smoke limiter automatically, based on said determined prevailing temperature of the SCR catalyst arrangement 265.

The first control device 200 is arranged to apply said relatively slow temperature increase within a predetermined temperature range. Said temperature range may be a range with an open lower limit and an upper limit which is defined by 30, 40 or 50 degrees Celsius. Said range is, according to one example, 20-40 degrees Celsius. Said range is, according to one example, 10-50 degrees Celsius. Said range is, according to one example, 15-35 degrees Celsius. Figure 4a illustrates schematically a flow chart of a method at the cold start of a motor vehicle 100, where said motor vehicle comprises a combustion engine 231 and an exhaust purification system comprising an SCR catalyst 265, as well as a first control function in order to force a temperature increase in exhausts from said combustion engine 231 , according to one embodiment of the present invention.

The method comprises an initial method step s401 . Step s401 comprises the steps to:

- continuously determine a prevailing temperature of said exhaust purification system;

- deactivate said first control function, when the determined temperature of said exhaust system falls below a predetermined value; and

- activate a second control function with the objective of achieving a relatively slow increase of said temperature in said exhaust purification system. The method is completed after step s401 .

Figure 4b illustrates schematically a flow chart of a method at the cold start of a motor vehicle 100, where said motor vehicle comprises a combustion engine 231 and an exhaust purification system comprising an SCR catalyst 265, as well as a first control function in order to force a temperature increase in exhausts from said combustion engine 231 , according to one embodiment of the present invention.

The method may, according to one aspect of the present invention, may be activated when said combustion engine 231 is started.

The method comprises an initial method step s410. The step s410 comprises the step to continuously determine a prevailing temperature of said exhaust purification system. This may be entailed by at least one of the temperature sensors 227, 237, 247, 257 and 267, as well as with the first control device 200 or the second control device 210. Hereat, a prevailing temperature of the SCR catalyst arrangement 265 is determined, and in particular a prevailing temperature of an SCR substrate of said SCR catalyst arrangement 265. Following the method step s410, a subsequent method step s420 is completed. The method step s420 comprises the step of determining a state in the vehicle 100. Here, it is determined whether a cold start in the vehicle is prevailing. In the event that at least one of said temperatures T1 -T5 and/or Tmod falls below a

predetermined temperature value TH1 , it is determined that a cold start of the vehicle 100 is prevailing. TH1 may e.g. be 20, 30, 40 or 50 degrees Celsius. In the event a cold start prevails, a subsequent method step s430 is carried out. If a cold start does not prevail, the method is completed and activation of said first control functions is carried out.

The method step s430 comprises the step of deactivating said first control function when the determined temperature of said exhaust system falls below said predetermined value TH1 . Here, a so-called white smoke limiter is deactivated in said first control device 200. Following the method step s430, a subsequent method step s440 is completed.

The method step s440 comprises the step of activating a second control function, with the objective of achieving a relatively slow increase in said temperature of said exhaust purification system. Said second control function achieves a reduction of NO2 gas from said SCR catalyst arrangement 265. Said second control function reduces a fraction of yellow smoke in the vehicle's exhausts that reach an

environment surrounding the vehicle. This may comprise not applying an exhaust brake in said engine 231 . Hereat, said exhaust brake, which may be adapted in the form of an adjustable damper, at least partly opens. Preferably, said damper is kept fully open. In addition, or alternatively, this may comprise not to carry out certain temperature rising measures in the vehicle, wherein a rise of the exhaust

temperature is forced in an active manner. This may comprise not applying post- injections in the combustion engine 231 , or shifting an injection angle, or postponing an injection timing for fuel in said engine 231 . Here, a so-called yellow smoke limiter is activated in said first control device 200. Following the method step s440, a subsequent method step s450 is completed. The method step s450 comprises the step of determining whether said state still prevails. This may be carried out by determining whether a temperature of said SCR catalyst arrangement 265 exceeds a predetermined value TH2. If said temperature of said SCR catalyst arrangement 265 exceeds said predetermined value TH2, it is determined that a cold start no longer prevails and a subsequent method step s460 is carried out. If it is determined that a cold start still prevails, said first control function will continue to be deactivated and said second control function will continue to be active. This is carried out until a temperature of said SCR catalyst arrangement 265 exceeds said predetermined value TH2. By keeping said second control function active and said first control function deactivated, a prevailing temperature may, according to the method of the invention, be increased relatively slowly for a certain duration, i.e. when the prevailing temperature is within a predetermined range, e.g. 20-40 degrees Celsius.

The method step s460 comprises the step of deactivating said second control function. The method step s460 may comprise to automatically activate said first control function, after said second control function has been deactivated.

Following the method step s460, the method is completed.

With reference to Figure 5, a diagram of an embodiment of a device 500 is shown. The control devices 200 and 210, which are described with reference to Figure 2, may in one embodiment comprise the unit 500. The unit 500 comprises a non-volatile memory 520, a data processing unit 510 and a read/write memory 550. The nonvolatile memory 520 has a first memory part 530, wherein a computer program, such as an operating system, is stored to control the function of the unit 500. Further, the unit 500 comprises a bus controller, a serial communications port, an I/O device, an A/D converter, a date-time input and transmission 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, comprising procedures for control at cold start of a motor vehicle, where said motor vehicle comprises a combustion engine 231 and an exhaust purification system comprising an SCR catalyst, as well as a first control function in order to force a temperature increase in exhausts from said combustion engine 231 .

The computer program P comprises procedures to continuously determine a prevailing temperature of the said exhaust purification system. The computer program P comprises procedures to deactivate said first control function, when the determined temperature of said exhaust system falls below a predetermined value. The computer program P comprises procedures to activate a second control function, with the objective of achieving a relatively slow increase in said temperature of said exhaust purification system.

The computer program P may comprise procedures to achieve, via said first control function, said forced temperature increase through activation of an exhaust brake in said engine 231 .

The computer program P may comprise procedures to achieve, via said first control function, said forced temperature increase through control of the fuel supply to said combustion engine 231 .

The computer program P may comprise procedures to achieve, via said second control function, said relatively slow increase of said temperature in said exhaust purification system through deactivation of an exhaust brake in said engine 231 .

The computer program P may comprise procedures to achieve, via said second control function, said relatively slow increase of said temperature in said exhaust purification system through control of the fuel supply to said combustion engine 231 .

The computer program P may comprise procedures to deactivate said second control function, when the determined temperature of said exhaust system exceeds a predetermined value.

The computer program P may comprise procedures to determine a temperature of said SCR catalyst, based on said temperature of said exhaust purification system. The computer program P may comprise procedures to apply said relatively slow temperature increase within a predetermined temperature range.

The computer program P may be stored in an executable manner or in a compressed manner in a memory 560 and/or a read/write memory 550.

A statement that the data processing unit 510 performs a certain function means that the data processing unit 510 performs a certain part of the program stored in the memory 560, or a certain part of the program stored in the read/write memory 550.

The data processing unit 510 may communicate with a data port 599 via a data bus 515. The non-volatile memory 520 is intended for communication with the data processing unit 510 via a data bus 512. The separate memory 560 is intended for communication with the data processing unit 510 via a data bus 51 1 . The read/write memory 550 is arranged for communication with the data processing unit 510 via a data bus 514. The links L210, L220, L227, L231 , L237, L247, L250, L257, L267 and L292 may e.g. be connected to the data port 599 (see Fig. 2 and Fig. 3).

When data is received in the data port 599, it is temporarily stored in the second memory part 540. When in-data received is temporarily stored, the data processing unit 510 is ready to carry out execution of code in the manner described above.

According to one embodiment, signals received in the data port 599 comprise information about the prevailing temperature in the exhaust system. Said temperature may be at least one of said first temperature T1 , second temperature T2, third temperature T3, fourth temperature T4 and fifth temperature T5. The signals received in the data port 599 may be used by the device 500 to deactivate said first control function when the determined temperature of said exhaust system falls below a predetermined value, and to activate a second control function, with the objective of achieving a relatively slow increase of said temperature in said exhaust purification system. Parts of the methods described herein may be carried out by the unit 500 with the help of the data processing unit 510, which runs the program stored in the memory 560 or the read/write memory 550. When the unit 500 runs the program, the procedures described herein are executed.

The foregoing description of the preferred embodiments of the present invention has been furnished for illustrative and descriptive purposes. It is not intended to be exhaustive, or to limit the invention to the variants described. Many modifications and variations will obviously be apparent to one skilled in the art. The embodiments have been chosen and described in order to best explicate the principles of the invention and its practical applications, and to thereby enable one skilled in the art to understand the invention in terms of its various embodiments, and with the various modifications that are applicable to its intended use.

Claims

1 . Method at the cold start of a motor vehicle (100), wherein said motor vehicle (100) comprises a combustion engine (231 ) and an exhaust purification system comprising an SCR catalyst (265), as well as a first control function in order to force a

temperature increase in exhausts from said combustion engine (231 ), comprising the step to:

- continuously determine (s410) a prevailing temperature (T1 ; T2; T3; T4; T5; Tmod) of said exhaust purification system,

characterised by the steps to:

- deactivate (s430) said first control function, when the determined temperature (T1 ; T2; T3; T4; T5; Tmod) of said exhaust system falls below a predetermined value (TH1 ); and

- activate (ss440) a second control function, with the objective of achieving a relatively slow increase of said temperature (T1 ; T2; T3; T4; T5; Tmod) in said exhaust purification system.

2. Method according to claim 1 , comprising the step to:

- via said first control function, achieve said forced temperature increase through activation of an exhaust brake (220) in said combustion engine (231 ).

3. Method according to claim 1 or 2, comprising the step to:

- via said first control function, achieve said forced temperature increase through control of the fuel supply to said combustion engine (231 ).

4. Method according to any one of the previous claims, comprising the step to:

- via said second control function, achieve said relatively slow increase of said temperature (T1 ; T2; T3; T4; T5; Tmod) in said exhaust purification system through deactivation of an exhaust brake (220) in said combustion engine (231 ).

5. Method according to any one of the previous claims, comprising the step to:

- via said second control function, achieve said relatively slow increase of said temperature (T1 ; T2; T3; T4; T5; Tmod) in said exhaust purification system through control of the fuel supply to said combustion engine (231 ).

6. Method according to any one of the previous claims, comprising the step to:

- deactivate (s440) said second control function, when the determined temperature (T1 ; T2; T3; T4; T5; Tmod) in said exhaust system exceeds said predetermined value (TH1 ; TH2).

7. Method according to any one of the previous claims, comprising the step to:

- determine a temperature of said SCR catalyst (265) based on said temperature (T1 ; T2; T3; T4; T5; Tmod) of said exhaust purification system.

8. Method according to any one of the previous claims, comprising the step to:

- apply said relatively slow temperature rise within a predetermined temperature range.

9. Method according to any one of claims 6-8, comprising the step to:

- activate (s460) said first control function after said second control function has been deactivated.

10. System at the cold start of a motor vehicle (100), wherein said system comprises a combustion engine (231 ) and an exhaust purification system comprising an SCR catalyst (265), as well as a first control function adapted to force a temperature increase in exhausts from said combustion engine (231 ), comprising:

- elements (227; 237; 247; 257; 267; 200; 210; 500) adapted to continuously determine a prevailing temperature (T1 ; T2; T3; T4; T5; Tmod) of said exhaust purification system,

characterised by:

- elements (200; 210; 500) adapted to deactivate said first control function, when the determined temperature (T1 ; T2; T3; T4; T5; Tmod) of said exhaust system falls below a predetermined value (TH1 ); and

- elements (200; 210; 500) adapted to activate a second control function, with the objective of achieving a relatively slow increase of said temperature (T1 ; T2; T3; T4; T5; Tmod) in said exhaust purification system.

1 1 . System according to claim 10, comprising:

- elements (200; 210; 500) adapted to, via said first control function, achieve said forced temperature increase through activation of an exhaust brake (220) in said combustion engine (231 ).

12. System according to claim 10 or 1 1 , comprising:

- elements (200; 210; 500) adapted to, via said first control function, achieve said forced temperature increase through control of the fuel supply to said combustion engine (231 ).

13. System according to any one of claims 10-12, comprising:

- elements (200; 210; 500) adapted to, via said second control function, achieve said relatively slow increase of said temperature in said exhaust purification system through deactivation of an exhaust brake (220) in said combustion engine (231 ).

14. System according to any one of claims 10-13, comprising:

- elements (200; 210; 500) adapted to, via said second control function, achieve said relatively slow increase of said temperature (T1 ; T2; T3; T4; T5; Tmod) in said exhaust purification system through control of the fuel supply to said combustion engine (231 ).

15. System according to any one of claims 10-14, comprising:

- elements (200; 210; 500) adapted to deactivate said second control function, when the determined temperature (T1 ; T2; T3; T4; T5; Tmod) in said exhaust system exceeds said predetermined value (TH1 ; TH2).

16. System according to any one of claims 10-15, comprising:

- elements (200; 210; 500) adapted to determine a temperature of said SCR catalyst (265), based on said temperature (T1 ; T2; T3; T4; T5; Tmod) of said exhaust purification system.

17. System according to any one of claims 10-16, comprising: - elements (200; 210; 500) adapted to apply said relatively slow temperature increase within a predetermined temperature range.

18. System according to any one of claims 15-17, comprising:

- elements (200; 210; 500) adapted to activate said first control function after said second control function has been deactivated.

19. Motor vehicle (100; 1 10), comprising a system according to any one of claims 10- 18.

20. Motor vehicle (100; 1 10) according to claim 19, wherein the motor vehicle is a truck, a bus or a car.

21 . Computer program (P) for cold start of a motor vehicle (100), wherein said system comprises a combustion engine (231 ) and an exhaust purification system comprising an SCR catalyst (265), as well as a first control function adapted to force a temperature increase of the exhausts from said combustion engine (231 ), wherein said computer program (P) comprises program code to cause an electronic control device (200; 500), or a computer (210; 500) connected to said electronic control device (200; 500), to perform the steps according to any one of claims 1 -9.

22. Computer program product, comprising a program code stored in a computer- readable medium, in order to perform the method steps according to any one of claims 1 -9, wherein said program code is executed in an electronic control device (200, 500), or in a computer (210, 500) connected to said electronic control device (200, 500).