SE1050649A1 - Method of HC dosing system and device of HC dosing system - Google Patents

Abstract

A method pertaining to an HC dosing system for cleaning of exhaust gases from an engine (150), including a dosing unit in thermal contact with the engine's exhaust system (250) and supplying a fuel to an exhaust duct (240) of the exhaust system, the step of determining (s340) whether there is an undesired temperature level of the dosing unit (250), and if so, limiting (s360) the temperature of the exhaust duct (240) by control of operation of the engine. Also a computer programme product containing programme code (P) for a computer (200; 210; 400) for implementing the method, and also to a device and a motor vehicle (100) which is equipped with the device.

Description

the pressure at small or no dosing amounts, the system also consists of a return hose which is arranged from a pressure side of the system back to According to the dosing unit by means of said diesel which flows from the container when cooled. In this configuration, it is possible to cool the container via the pump and the dosing unit back to the container. In this way an active cooling of the dosing unit is provided. The return flow from the dosing valve to the container is today essentially constant.

Since the dosing unit is currently arranged at the exhaust system of the vehicle, which exhaust system during operation of the vehicle is heated depending on e.g. load on the engine, the dosing valve risks overheating. Overheating of the dosing unit may result in degradation of the same consideration functionality, which may result in a degraded performance thereof.

The dosing unit today comprises electrical components, some of which include a circuit board. Said circuit boards can e.g. be provided for controlling the dosing of diesel to the exhaust system of the vehicle. These electrical components are sensitive to high temperatures for skäl your reasons. Excessive temperatures of the dosing unit can result in degradation of the electrical components, which can lead to costly repairs at a service workshop. Furthermore, diesel present in the dosing unit can at least partially change to solid form at too high temperatures, which can lead to clogging of the dosing unit. According to one example, said diesel in the dosing unit undergoes pyrolysis, said diesel being at least partially converted to coke. Thus, at least a part of said can cook. diesel It is therefore of the utmost importance that the temperature of the dosing unit of the DPF system does not exceed a critical temperature.

Thus, there is a need to improve the current HC dosing system to reduce or eliminate the above mentioned disadvantages.

SUMMARY OF THE INVENTION An object of the present invention is to provide a new and advantageous method for improving the performance of an HC dosing system.

An object of the present invention is to provide a new and advantageously improved HC dosing system, where a cooling flow of a dosing unit is missing or is a process for the performance of an insufficient one.

Another object of the invention is to provide a new and advantageous device of an HC dosing system and a new and advantageous computer program for improving the performance of an HC dosing system.

Another object of the invention is to provide a new and advantageous device of an HC dosing system and a new and advantageous computer program for improving the performance of an HC dosing system, where a cooling flow of a dosing unit is missing or insufficient.

An object of the present invention is to provide a method of an HC dosing system, which method provides a reduced risk of the functional HC dosing system clogging of undesired degradation of components of and / or a reduced risk of components, e.g. a dosing unit, of the HC dosing system with respect to a fuel.

A further object of the invention is to provide an alternative method of an HC dosing system and an alternative computer program of an HC dosing system and an alternative device of an HC dosing system.

These objects are achieved by a process in an HC metering system for exhaust gas purification for an engine, according to claim 1.

According to one aspect of the invention, there is provided a method of an HC metering system for purifying exhaust gases from an engine, comprising a metering unit for supplying a fuel to an exhaust duct, comprising the step of determining whether an undesired temperature level of said metering unit is present. The method also includes the step of, if said undesired temperature level is determined to exist, limiting the temperature of said exhaust duct by controlling the operation of said engine.

In cases where cooling of the dosing unit is not sufficient, whereby a temperature of the dosing unit rises to an undesirable level, a temperature of exhaust gases in the exhaust system can be controlled by influencing the operation of the engine.

Advantageously, a method is provided which entails a reduced risk of overheating of the fuel at the dosing unit. it is avoided that or that clogging of the idor unit due to coking. high temperatures the dosing unit is permanently damaged causing a Said limitation of the temperature can be achieved by reducing a maximum available torque of an output shaft of the engine. In this case, a driver or a stored driver cannot request a torque higher than the maximum available. By reducing the maximum available torque, a temperature of the exhaust gases in the exhaust duct will fall. Said reduction of the maximum available torque can take place by means of ramping or in discrete steps. Said reduction of the maximum available torque can take place on the basis of a detected, or by means of a stored model calculated, temperature of the exhaust gases in the exhaust duct.

Alternatively, said reduction of the maximum available torque can take place on the basis of a measured, or calculated by means of a stored model, temperature of the dosing unit.

Said limitation of the temperature can be achieved by influencing an EGR content of the engine. By influencing said EGR content, a temperature of the exhaust gases in the exhaust duct can be actively regulated to a desired predetermined level. By changing said EGR content, a temperature of the exhaust gases in the exhaust duct can be actively lowered to a desired predetermined level.

In this case, improved cooling of the dosing unit will be made possible.

Said limitation of the temperature can be effected by influencing the injection time of fuel of at least one cylinder of the engine or by influencing the ignition timing of at least one cylinder of the engine.

By changing the injection time of at least one cylinder of a diesel engine, alternatively a ignition time of at least one cylinder of an Otto engine, a temperature of the exhaust gases in the exhaust duct can be actively regulated to a desired predetermined level. By shifting the injection time or an ignition time, a temperature of the exhaust gases in the exhaust duct can be actively lowered to a desired predetermined level. In this case, improved cooling of the dosing unit will be made possible.

Said undesired temperature level can be set on the basis of properties of said fuel. Said temperature level can in particular be set on the basis of a temperature at which said fuel begins to be adversely affected and / or become unstable. Said temperature level can be in a range between 80-130 degrees Celsius. Said temperature level may be a temperature higher than 130 degrees Celsius. According to an example with rather sensitive fuel, said temperature level can be in a range between 60-90 degrees Celsius.

The step of determining whether there is an undesired temperature level of said dosing unit can take place on the basis of at least one of the steps of: - measuring a temperature directly of the dosing unit; - measuring a temperature of an exhaust stream in said exhaust duct; and - calculating a calculation model by means of a temperature of said dosage unit.

By measuring a temperature directly at the dosing unit, an exact measurement of the prevailing temperature there is obtained.

By measuring a temperature of the exhaust stream in the exhaust duct, or an HC dosing system, such as e.g. the exhaust duct, an indication of a temperature of a component of the exhaust system of the prevailing temperature of the dosing unit can be obtained. The measurement of the temperature of the exhaust stream in the exhaust duct is a good complement or alternative to directly measuring a temperature of the dosing unit.

By calculating a temperature of said dosing unit by means of a calculation model, a variant is produced where no physical sensor at the dosing unit and / or the exhaust duct (exhaust system) is required.

This is thus a cost-effective variant for determining a temperature of the dosing unit. or by determining (measuring or calculating) a By measuring (measuring) a temperature of temperature of another component of the HC dosing system, which can determine the possible presence of an undesired temperature level of a temperature corresponding to a temperature of dosing unit, dosing unit arranged to supply fuel to an exhaust duct.

According to one example, a future temperature of the dosing unit can be predicted by means of a stored calculation model. According to an example, e.g. a prevailing load on an engine of the HC dosing system is taken into account. It is well known that an increase in the temperature of the exhaust gases during an increase in the load on the engine is associated with a certain time delay. A future temperature of the dosing unit can thus be predicted on the basis of a prevailing load, or load change, of the engine of the HC dosing system.

Said fuel may be diesel or another hydrocarbon-based fuel.

The method may further comprise the step of manually interrupting the step of controlling the operation of said engine to limit the temperature of said exhaust duct. In operating conditions where insufficient cooling of the dosing unit takes place, an automatic control of the operation of the engine is initiated so as to lower a temperature of the exhaust gas stream in the desired manner. In a case where the HC dosing system is mounted in an emergency vehicle, such as e.g. a fire truck, a driver or other personnel of the emergency vehicle may choose to actively interrupt said control of engine operation. This can have the undesirable consequence that e.g. the dosage unit is destroyed due to excessive temperatures and that the vehicle may emit undesired emissions to an excessive extent. However, in the event of an emergency, the innovative procedure can be overridden, in order to prioritize high speed and a high available torque of the engine. Deactivation of the innovative method can take place by means of a pushbutton mounted in a driver's cab of the vehicle, which pushbutton is signal-connected to a control unit of the vehicle.

The procedure is easy to implement in existing motor vehicles. Software in an HC dosing system for exhaust gas purification for an engine 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 thus be given the opportunity to choose the function of the procedure as an option. Alternatively, software including program code for performing the innovative process of an HC exhaust system for engine exhaust can be 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 the control unit.

Implementing the innovative procedure is thus cost-effective, especially since no additional sensors or components need to be installed in the vehicle. The required hardware is already present in the vehicle today. The invention thus provides a cost-effective solution to the above problems.

According to one aspect of the present invention, there is provided an apparatus of an HC metering system for purifying exhaust gases from an engine, comprising a metering unit for supplying a fuel to an exhaust duct, further comprising: means for determining whether an undesired temperature level of said metering unit is present. , and - means for, if said undesired temperature level is determined to exist, limiting the temperature of said exhaust duct by controlling the operation of said engine.

The device may comprise means for reducing a maximum available torque of an output shaft of the motor in order to effect said limitation of the temperature.

The device may comprise means for influencing an EGR content of the engine to effect said limitation of the temperature. Said limitation of the temperature can be effected by influencing the injection time of fuel of at least one cylinder of the engine or by influencing the ignition timing of at least one cylinder of the engine.

The device may comprise at least one of: - means for measuring a temperature directly at the dosing unit; means for measuring a temperature of an exhaust stream in said exhaust duct; and - means for calculating a temperature of said dosage unit by means of a calculation model.

The above objects are also achieved with a motor vehicle incorporating the features of the device of an HC dosing system described herein.

The motor vehicle can be a truck, bus or car.

According to one aspect of the invention, there is provided a computer program of an HC exhaust gas purification system for an engine, said computer program comprising program code stored on a computer readable medium to cause an electronic control unit or another computer connected to the electronic control unit to performing the steps according to any one of claims 1-7.

According to one aspect of the invention, there is provided a computer program product comprising a program code stored on a computer readable medium for performing the method steps of any of claims 1-7, when said computer program is run on an electronic control unit or another computer connected to the electronic control unit. .

Software that includes program code for an HC exhaust system for engine exhaust purification can be easily updated or replaced. Furthermore, different parts of the software that include program code in an HC metering system for exhaust gas purification for an engine can be replaced independently. This modular configuration is advantageous from a maintenance perspective.

Additional objects, advantages and novel features of the present invention will become apparent to those skilled in the art from the following details, as well as through the practice of the invention. While the invention is described below, it should be understood that the invention is not limited to the specific details described. Those skilled in the art having access to the teachings herein will recognize and incorporate within other further 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 objects and advantages thereof, reference is now made to the following detailed description which is to be read in conjunction with the accompanying drawings in which like reference numerals refer to like parts in the various figures, and in which: 1 schematically illustrates a vehicle, according to an embodiment of the invention; Figure 2 schematically illustrates a subsystem of the vehicle shown in Figure 1, according to an embodiment of the invention; Figure 3a schematically illustrates a flow chart of a method, according to an embodiment of the invention; Figure 3b schematically illustrates in further detail a flow chart of a method, according to an embodiment of the invention; and illustrates a computer, Figure 4 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 with an engine 150 and a trailer 112. The vehicle may be a heavy vehicle, such as a truck or a bus. The vehicle can alternatively be a car.

It should be noted that the invention is suitable for use in any suitable HC dosing system and is not limited to DPF systems in motor vehicles. The innovative method and the innovative device according to an aspect of the invention are well suited for platforms which include an HC dosing system other than motor vehicles, such as e.g. watercraft. The watercraft can be of any kind, such as e.g. motorboats, ships, ferries or ships.

The innovative method and the innovative device according to an aspect of the invention are also well suited for e.g. systems including industrial engines and / or motorized industrial robots. The innovative method and the innovative device according to an aspect of the invention are also well suited for different types of power plants, such as e.g. an electric power plant comprising a diesel generator.

The innovative method of an HC dosing system and the innovative device of an HC dosing system are well suited for any engine system which includes an engine and an HC dosing system, such as e.g. at a locomotive or other platform.

The innovative method and device are well suited for an arbitrary system that includes a particulate generator (eg, an internal combustion engine) and an HC dosing system.

The innovative method and the innovative device are well suited for an arbitrary system which includes an arbitrary system which generates exhaust gases with particles and a filter which stores particles, which particles are burned during a regeneration of said filters, in particular during an active regeneration of said filters. filter.

Here, the term "link" refers to a communication link which may be a physical line, such as an optoelectronic communication line, or a non-physical line, such as a wireless connection, for example a radio or microwave link.

Here, the term "conduit" refers to a passage for holding and transporting a fluid, such as e.g. a fuel in liquid form. The conduit can be a pipe of any suitable dimension. The conduit may consist of any suitable material, such as e.g. plastic, rubber or metal.

Herein, the term "fuel" refers to an agent used for the active regeneration of a particulate filter in an HC dosing system. Said fuel is according to one embodiment diesel. Of course, other types of 12 hydrocarbon-based fuels can be used. Here, diesel is mentioned as an example of a fuel, but a person skilled in the art realizes that the innovative method and the innovative device can be realized for other types of fuels, with requirements such as e.g. adequate adjustments, adjustments to the boiling temperature of selected fuels, in control algorithms for executing software code in accordance with the innovative procedure. Although the term HC dosing system is used herein to indicate a particulate filter system, the invention is not limited to the use of a diesel particulate filter. On the contrary, other types of particle filters can be used according to the invention. One skilled in the art will recognize what kind of fuel is best suited for regenerating the selected particulate filter.

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

The subsystem 299 is arranged in the tractor 110. The subsystem 299 may form part of an HC dosing system. The subsystem 299 according to this example consists of a container 205 which is arranged to contain a fuel. The container 205 is arranged to contain a suitable amount of fuel and is further arranged to be able to be refilled if necessary. The container can hold e.g. 200 or 1500 liters of fuel.

A first line 271 is arranged to lead the fuel to a pump 230 from the container 205. The pump 230 may be any suitable pump. The pump 230 may be a diaphragm pump comprising at least one filter. The pump 230 is arranged to be driven by means of an electric motor. The pump 230 is arranged to pump the fuel from the container 205 via the first line 271 and via a second line 272 supply said fuel to a dosing unit 250.

The dosing unit 250 comprises an electrically controlled dosing valve, by means of which a flow of fuel added to the exhaust system can be controlled. The pump 230 is arranged to pressurize the fuel in the second line 272.

The dosing unit 250 is arranged with a throttling unit, against which said pressure of the fuel is built up in the subsystem 299. The dosing unit 250 is arranged to supply said fuel to a 100. the dosing unit 250 is arranged to supply in a controlled manner a suitable amount of exhaust system (not shown) in the vehicle More specifically, fuel for an exhaust system of the vehicle is 100. According to this embodiment, a particulate filter (not shown), e.g. a DPF, arranged downstream of a position of the exhaust system where the supply of fuel is provided. The amount of fuel supplied to the exhaust system is intended to be used in a conventional manner in the HC dosing system for active regeneration of the particulate filter.

The dosing unit 250 is arranged at e.g. an exhaust pipe arranged to direct exhaust gases from the internal combustion engine 150 of the vehicle 100 to said particulate filter. The dosing unit 250 is arranged in thermal contact with the exhaust system of the vehicle 100. This means that thermal energy is stored in e.g. an exhaust pipe, muffler, particulate filter and SCR catalyst can then be led to the dosing unit 250.

The dosing unit 250 comprises an electronic control card, which is 200.

The dosing unit 250 also comprises plastic and / or rubber components, arranged to handle communication with a control unit which may melt or be otherwise adversely affected at excessive temperatures.

The dosing unit 250 is sensitive to temperatures above a certain temperature value, such as e.g. 120 degrees Celsius. Since e.g. exhaust pipe, this temperature value there is a risk that the dosing unit 250 may overheat the muffler and the particulate filter of the vehicle 100 exceeds during operation of the vehicle or after operation of the vehicle unless cooling thereof is achieved.

It should be noted that fuel present in the dosage unit 250 may be adversely affected at temperatures significantly lower than the 120 degrees Celsius 14 indicated above. At temperatures exceeding e.g. 70 degrees Celsius, the fuel can become unstable, in order to possibly boil at slightly higher temperatures and in the long run possibly cause clogging of the dosing unit 250.

A third conduit 273 is provided between the metering unit 250 and the container 205. The third conduit 273 is arranged to return a certain amount of the fuel supplied to the metering valve 250 to the container 205. With this configuration advantageous cooling of the metering unit 250 is provided. the metering unit 250 is cooled by a flow of the fuel as it is pumped through the metering unit 250 from the pump 230 to the container 205.

A first control unit 200 is arranged for communication with a first temperature sensor 220 via a link 221. The first temperature sensor 220 is arranged to detect a prevailing temperature of the dosing unit 250.

The first temperature sensor 220 is arranged to continuously send signals to the first control unit 200 including information about a prevailing first temperature T1 of the dosing unit 250.

The first control unit 200 is arranged for communication with the pump 230 via a link 231. The first control unit 200 is arranged to control operation of the pump 230 in order to e.g. regulating flows of fuel within the subsystem 299. The first control unit 200 is arranged to control an operating power of the pump 230 by regulating the electric motor therewith.

The first control unit 200 is arranged for communication with a second temperature sensor 280 via a link 281. The second temperature sensor 280 is arranged to detect a prevailing temperature of the exhaust duct 240. The second temperature sensor 280 is arranged to continuously send signals to the first control unit 200 including information about a prevailing temperature of the exhaust duct 240.

The first control unit 200 is arranged to calculate an estimated prevailing temperature test of the dosing unit 250 on the basis of the signals received from the second temperature sensor 280.

The first control unit 200 is arranged for communication with the dosing unit 250 via a link 251. The first control unit 200 is arranged to control operation of the dosing unit 250 in order to e.g. regulating the supply of fuel to the exhaust system of the vehicle 100. According to one example, the first control unit 200 is arranged to control operation of the dosing unit 250 in order to e.g. regulate the re-supply of fuel to the tank 205.

According to one embodiment, the first control unit 200 is arranged, on the basis of the signals received from the first temperature sensor 220 and / or the second temperature sensor 280, if necessary, to limit the temperature of said exhaust duct by controlling the operation of said engine, in accordance with an aspect of the innovative procedure.

In particular, the first control unit 200 according to an embodiment is arranged to, on the basis of the signals received from the first temperature sensor 220 and / or the second temperature sensor 280, if necessary, reduce a maximum available torque of an output shaft of the motor, and / or influence an EGR content of the engine.

The first control unit 200 according to an embodiment arranged to, on the basis of the signals received from the first temperature sensor 220 and / or the second temperature sensor 280,, if necessary, influence the injection time of fuel of at least one cylinder of the engine or influence the ignition timing of at least one cylinder of the engine. , in accordance with one aspect of the innovative process. This can also be achieved in combination with said reduction of the maximum available torque of an output shaft of the engine, and / or said effect of EGR content of the engine. A second control unit 210 is arranged for communication with the first control unit 200 via a link 201. The second control unit 210 may be detachably connected to the first control unit 200. The second control unit 210 may be a control unit external to the vehicle 100. The second control unit 210 may be arranged to perform the innovative method steps according to the invention. The second control unit 210 can be used to upload software to the first control unit 200, in particular software for performing the innovative method. 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 similar functions as the first control unit 200, such as e.g. determining whether an undesired temperature level of the metering unit 250 is present, which metering unit 250 is arranged to supply fuel to an exhaust duct, and if said undesired temperature level is determined to exist, limiting the temperature of said exhaust duct by controlling said engine operation. The innovative method can be performed by the first control unit 200 or the second control unit 210, or by both the first control unit 200 and the second control unit 210.

According to this embodiment, a source of compressed air 260 is arranged to supply pressurized air to the dosing unit 250 via a line 261. The dosing unit 250 is arranged to use said supplied pressurized air to further atomize the fuel being dosed. The compressed air can also be used to at least partially drive the dosing unit to dose said fuel into the exhaust duct. The compressed air can also be used to, where applicable, blow out e.g. the dosage unit 250 with respect to fuel contained therein. This can be done during operation of the motor 150, or after the motor 150 has been switched off.

According to one embodiment, the container 205 may be the vehicle's fuel tank, with parts of the vehicle's existing fuel system being used in accordance with the present invention. According to another example, the container may be a separate container, i.e. not the same container as the vehicle's fuel tank.

According to one embodiment, the dosing unit 250 is arranged directly at an exhaust duct of the HC dosing system. According to another example, the dosing unit 250 is provided with a passive nozzle presently provided through said exhaust duct for dosing said fuel directly into the exhaust duct.

According to one embodiment, said pump 230 is the same pump that normally generates fuel pressure for an injection system of the engine 150. According to another example, said pump 230 is a separate pump, i.e. not the same pump that normally generates the fuel pressure to the injection system.

According to one example, a precatalyst and / or oxidation catalyst is mounted in series with the particulate filter. In this case, said precatalyst and / or oxidation catalyst are arranged upstream of said particle filter.

Figure 3a schematically illustrates a flow chart of a process in an HC dosing system for purifying exhaust gases from an engine 150, comprising a dosing unit (250) for supplying a fuel to an exhaust duct 240, according to an embodiment of the invention. The method comprises a first method step s301. Step s301 includes the steps of determining s340 whether an undesired temperature level of said dosage unit 250 is present; and if said undesired temperature level is determined to exist, s360 limits the temperature of said exhaust duct 240 by controlling said engine operation. After step s301, the process is terminated.

Figure 3b schematically illustrates a flow chart of a process in an HC metering system for purifying exhaust gases from an engine (150), comprising a metering unit (250) for supplying a fuel to an exhaust duct (240), according to an embodiment of the invention. The method comprises a first method step s310. The process step s310 includes the step of determining a prevailing temperature of the dosing unit 250. This is done by directly measuring the prevailing temperature at the dosing unit 250. In process step s310, a first temperature value T1 representing a prevailing temperature of the dosing unit 250 is measured.

Method step s320 includes the step of determining an estimated prevailing temperature test of the dosage unit 250 indirectly. This is done by measuring a prevailing temperature T2 at a component other than the dosing unit 250 of the HC dosing system. In process step s310, a second temperature value T2 of a component other than the dosing unit 250 is measured. By means of the measured temperature T2, a first estimated prevailing temperature T1est of the dosing unit 250 can be determined (calculated). According to an alternative, a second estimated prevailing temperature T2est of the dosing unit 250 can be determined (calculated) by means of a calculation model which has parameters other than temperature of a component of the HC dosing system as input value. Such an input parameter can e.g. be a prevailing load of the motor 150. It should also be pointed out that according to one embodiment it is possible to use only the measured temperature T1 of the dosing unit 250 to determine a maximum temperature value Tmax as below. In some cases it is advantageous to use both the measured temperature T1 and at least one of the estimated prevailing temperatures T1 est and T2est to determine a maximum temperature value Tmax as below, since a more robust process is thereby obtained. It should be noted that step s310 and s320 After can be performed substantially or in process step s320 a subsequent process step s330 is performed. at the same time, reverse order.

The method step s330 includes the step of comparing the determined first temperature T1 and at least one of said estimated prevailing 19 Tlest T2est of 250. the method step s330 is performed a subsequent method step s340. temperature and the dosing unit After the process step s340, the step comprises, on the basis of a result of said comparison between the determined first temperature T1 and the at least one estimated prevailing temperature (T1est, T2est) of the dosing unit 250, selecting the highest value of the compared values. This highest temperature value is also called Tmax. Method step s340 also includes determining the dosing unit is present, wherein said dosing unit is arranged to supply fuel to a step of whether an undesired temperature level of the exhaust duct. This can be done by a comparison with a limit value Tth, such as a predetermined temperature value, e.g. 70 or 100 degrees Celsius, depending on the type of fuel used in the HC dosing system. If Tmax is greater than or equal to Tth, it can be determined that an undesired temperature level of the dosage unit is present. If Tmax is less than Tth, it can be determined that an undesired temperature level of the dosage unit 250 is not present.

According to an alternative embodiment, as described above, it can be determined whether an undesired temperature level of the dosing unit 250 is present on the basis of only the measured temperature T1 of the dosing unit. According to this embodiment, a less complex method is provided, according to an aspect of the invention.

After the process step s340, a subsequent process step s350 is performed.

The process step s350 includes the step of, on the basis of the selected value Tmax, determining a maximum permissible exhaust gas temperature Tem. The maximum permissible set-up process is determined, where the selected value Tmax is associated with an exhaust gas temperature Tem can through a maximum permissible exhaust gas temperature Tem, e.g. in tabular form. The maximum permissible exhaust gas temperature Tem can alternatively be determined by means of a calculation model, where the selected value Tmax is an input value for said calculation model. After the process step S350, a subsequent process step S360 is performed.

The process step S360 comprises the step of, on the basis of the determined maximum permissible exhaust gas temperature Tem, taking at least one measure for influencing the temperature of the exhaust gas stream in the exhaust duct 240. According to one embodiment, this at least one measure is selected from a group comprising: - reducing a maximum available torque at an output shaft of the engine; - affect an EGR content of the engine; influencing the injection time of fuel of at least one cylinder of the engine, or influencing the ignition timing of at least one cylinder of the engine; and - influencing an air flow of the engine by means of one or more dampers, e.g. a throttle at the inlet and / or outlet side of the engine.

After procedure step S360, the procedure is terminated.

Referring to Figure 4, there is shown a diagram of an embodiment of a device 400. The controllers 200 and 210 described with reference to Figure 2 may in one embodiment include the device 400. The device 400 includes a non-volatile memory 420, a data processing unit 410, and a read / write memory 450. The non-volatile memory 420 has a first memory portion 430 in which a computer program, such as an operating system, is stored to control the operation of the device 200. Further, the device 400 includes a bus controller, a serial communication port , I / O means, 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 420 also has a second memory portion 440.

A computer program P is provided which includes routines for determining whether an undesired temperature level of a dosing unit 250 is present, 21 where the dosing unit 250 is arranged to supply fuel to an exhaust duct 240, and if said undesired temperature level is determined to exist, limiting the temperature of said exhaust duct of the operation of said engine, in accordance with the innovative procedure.

The program P includes routines for, where applicable, reducing a maximum available torque of an output shaft of the engine, to effect a limitation of the temperature of the exhaust duct 240.

The program P includes routines for, where applicable, influencing an EGR content of the engine 150, to effect a limitation of the temperature of the exhaust duct 240.

The program P includes routines for, where applicable, influencing the fuel injection time of at least one cylinder of the engine 150 or by influencing the ignition timing of at least one cylinder of the engine 150, to effect a limitation of the temperature of the exhaust duct 240.

The program P can be stored in an executable manner or in a compressed manner in a memory 460 and / or in a read / write memory 450.

When it is described that the data processing unit 410 performs a certain function, it is to be understood that the data processing unit 410 performs a certain part of the program which is stored in the memory 460, or a certain part of the program which is stored in the read / write memory 450.

The data processing device 410 can communicate with a data port 499 via a data bus 415. The non-volatile memory 420 is intended for communication with the data processing unit 410 via a data bus 412. The separate memory 460 is intended to communicate with the data processing unit 410 via a data bus 411. Read / write memory 450 is arranged to communicate with the data processing unit 410 via a data bus 414. To the data port 499, e.g. links 201, 221, 231, 251 and 281 are connected (see Figure 2).

When data is received on the data port 499, it is temporarily stored in the second memory part 440. Once the received input data has been temporarily stored, the data processing unit 410 is arranged to perform code execution in a manner described above. According to one embodiment, signals received at the data port 499 include information about a prevailing temperature of the dosing unit 250. According to one embodiment, signals received at the data port 499 include information about a prevailing temperature of an exhaust stream in the exhaust duct 240. According to an alternative embodiment, signals received at the data port 499 include information if a prevailing temperature of a suitable component of the subsystem 299, e.g. a prevailing temperature of the exhaust duct, a prevailing temperature of the particulate filter, or a prevailing temperature of a muffler of the HC dosing system. Such a signal can be used to calculate a prevailing temperature of the dosing unit 250 by means of a calculation model stored in the memory 460. The received signals on the data port 499 can be used by the device 400 to determine the exhaust duct 240 is present and on that basis affect operation of the engine 150. temperature of the exhaust stream so as to obtain a desired temperature of the exhaust stream.

Parts of the methods described herein may be performed by the device 400 by means of the data processing unit 410 running the program stored in the memory 460 or the read / write memory 450. When the device 400 runs the program, the methods described herein are executed.

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 to limit the invention to the variations described. Obviously, many modifications and variations will occur to those skilled in the art. The embodiments 23 were selected and described to best explain the principles of the invention and its practical applications, thereby enabling those skilled in the art to understand the invention for various embodiments and with the various modifications appropriate to the intended use.

Claims (18)

10 15 20 25 30 24 PATENT REQUIREMENTS A method of an HC metering system for purifying exhaust gases from an engine (150), comprising a metering unit (250) for supplying a fuel to an exhaust duct (240), comprising the step of: - determining (s340) whether an undesired temperature level of said dosing unit (250) is characterized by the step of: - if said undesired temperature level is determined to exist, limiting (s360) the temperature of said exhaust duct (240) by controlling operation of said engine. The method of claim 1, wherein said limiting the temperature is accomplished by reducing a maximum available torque of an output shaft of the engine (150). A method according to claim 1 or 2, wherein said limiting of the temperature is effected by affecting an EGR content of the engine (150). A method according to any one of claims 1-3, wherein said limiting of the temperature is effected by influencing the injection time of fuel of at least one cylinder of the engine (150) or by influencing the ignition timing of at least one cylinder of the engine (150). A method according to any one of the preceding claims, wherein said undesired temperature level is set on the basis of properties of said fuel. A method according to any one of the preceding claims, wherein the step of determining whether an undesired temperature level of said dosing unit (250) is present takes place on the basis of at least one of the steps of: - measuring a temperature (T1) directly at the dosing unit (250): - measuring a temperature of an exhaust stream in said exhaust duct (240); and calculating a temperature of said dosage unit (250) by means of a calculation model. A method according to any one of the preceding claims, wherein said fuel is diesel or another hydrocarbon-based fuel. Apparatus of an HC metering system for purifying exhaust gases from an engine (150), comprising a metering unit (250) for supplying a fuel to an exhaust duct (240), further comprising: - means (200; 210; 400) for determining whether an undesired temperature level of said dosing unit (250) is characterized by: means (200; 210; 400) for limiting the temperature of said exhaust duct (240) if said undesired temperature level is present by controlling operation of said engine. The apparatus of claim 8, comprising means (200; 210; 400) for reducing a maximum available torque of an output shaft of the motor (150) to effect said temperature limitation. Device according to claim 8 or 9, comprising means for influencing an EGR content of the engine (150) to effect said temperature limitation. Device according to any one of claims 8-10, wherein said limitation of the temperature is effected by influencing the injection time of fuel of at least one cylinder of the engine (150) or by influencing the ignition timing of at least one cylinder of the engine (150). Device according to any one of claims 8-11, wherein said undesired temperature level is set on the basis of properties of said fuel. 10 15 20 25 26 Device according to any one of claims 8-12, comprising at least one of: - means (220) for measuring a temperature directly of the dosing unit; means for measuring a temperature of an exhaust stream in said exhaust duct; and means (200; 210; 400) for calculating a temperature of said dosage unit by means of a calculation model. Device according to any one of claims 8-13, wherein said fuel is diesel or another hydrocarbon-based fuel. Motor vehicle (100; 110) comprising a device according to any one of claims 8-14. A motor vehicle (100; 110) according to claim 15, wherein the motor vehicle is something of a truck, bus or passenger car. A computer program (P) in an HC metering system for purifying exhaust gases from an engine (150), comprising a metering unit (250) for supplying a fuel to an exhaust duct (240), said computer program (P) comprising program code stored on a computer readable medium for causing an electronic control unit (200; 400) or another computer (210; 400) connected to the electronic control unit (200; 400) to perform the steps of any of claims 1-7. A computer program product comprising a program code stored on a computer readable medium for performing the method steps of any of claims 1-7, when said computer program is run on an electronic control unit (200; 400) or another computer (210; 400) connected to the electronic control unit (200; 400).