SE537643C2 - Method and apparatus for cooling an HC dosing unit for exhaust gas purification - Google Patents

Abstract

SUMMARY The invention relates to a method of HC dosing system pre-exhaust purification, including a dosing unit (250) for fuel, comprising the steps of determining a need to, after shutting off an exhaust stream, cooling said dosing unit for fuel by means of fuel, and the step of predicting a temperature advance of at least a portion of said HC dosing system as a basis for determining said need. The invention also relates to a computer program product comprising program code (P) for a computer (200; 210) for implementing a method according to the invention. The invention also relates to a device of an HC dosing system and a motor vehicle equipped with the device. Figure 2 for publication

Description

The present invention relates to a method of an HC dosing system for pre-gas purification, including a fuel dosing unit. The invention also relates to a computer program product comprising program code for a computer for implementing a method according to the invention. The invention also relates to a device comprising an HC dosing system for exhaust gas purification, including a dosing unit for fuel, and a motor vehicle equipped with the device.

BACKGROUND In today's vehicles, diesel is used as fuel in DPF systems (Diesel ParticulateFilter) including a particulate filter. The particle filter is arranged to capture opt.ex. diesel particles and soot. During active regeneration of the particulate filter, diesel is supplied to an exhaust pipe downstream of an engine, which diesel is led into an oxidation catalyst, also called DOC. In the oxidation catalyst, said diesel is combusted and causes an increase in the temperature of the exhaust system. In this way, active regeneration of the particulate filter arranged downstream of the oxidation catalyst can be achieved.

One type of DPF system includes a container containing diesel. The DPF system also has a pump which is arranged to inflate said diesel from the container via a suction hose and supply it via a pressurized hose to a dosing unit which is arranged at an exhaust system of the vehicle, such as e.g. at an exhaust pipe of the exhaust system. The dosing unit is arranged to inject a required amount of diesel into the exhaust pipe upstream of the particulate filter according to drivers stored in a control unit of the vehicle. In order to more easily regulate 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 the single dosing unit by means of said diesel which flows from the container during cooling. this configuration, it is possible to return the cooling container via the pump and the dosing unit 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 substantially 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 motor, the dosing valve risks overheating. Overheating of the dosing unit can lead to degradation of the same consideration functionality, which can result in a degraded performance thereof.

The dosing unit today comprises electrical components, some of which comprise 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 several reasons. Excessively high temperatures of the dosing unit can result in degradation of the dielectric components, which can lead to costly repairs to the 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 an example, said diesel in the dosage unit undergoes pyrolysis, said diesel being at least partially converted to coke. Thus, at least a part of the sagda diesel can boil. It is therefore of the utmost importance that the temperature of the dosing unit of the DPF system does not exceed a critical temperature.

Cooling of the dosing unit of a DPF system in vehicles today takes place continuously during ordinary operation of the vehicle as said diesel is circulated within the DPF system in the manner specified above. To some extent, cooling of the dosing unit during operation of the vehicle today works satisfactorily.

However, there is always a need to improve the performance of existing subsystems, e.g. DPF systems, in vehicles, not least from a competition point of view.

During and after operation of the vehicle, there is a stored amount of thermal energy, mainly the exhaust system caused by said operation. This thermal energy can be led to the dosing unit from e.g. a muffler and the particulate filter metering unit, which can be heated to a temperature exceeding a critical value thereof.

When shutting down the vehicle and thus after shutting off the exhaust flow in the exhaust system, the dosing unit for diesel is cooled by means of said diesel in the same manner as during ordinary operation for a predetermined time, such as e.g. 30 minutes.

This action is associated with certain disadvantages. As an example, a relatively large amount of energy is required to drive the pump in the DPF system after shutting down the vehicle. In the event that a vehicle battery drives the pump of the DPF system, this can be discharged or reach a relatively low degree of charge.

Another disadvantage of cooling the dosing unit in the same way as subordinate operation is that the pump of the DPF system produces disturbing noise, which, for example. a driver of the vehicle may find it annoying, in particular when the driver is about to sleep in the cab after a driving session, or where the driver is in close proximity to the vehicle.

Thus, there is a need to improve the present cooling method of the dosing unit in the HC dosing system after the vehicle has been switched off in order to reduce or eliminate the above-mentioned disadvantages.

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

An object of the present invention is to provide a new and advantageous method for effecting cooling of a dosing unit of an HC dosing system after shutting off an exhaust gas flow therein.

Another object of the invention is to provide a new and advantageous device and a new and advantageous computer program for effecting cooling of a dosing unit of an HC dosing system after shutting off an exhaust gas flow therein.

A further object of the invention is to provide a method, device and a computer program for reducing the risk of a dosing unit in an HC dosing system overheating after shutting off an exhaust gas flow in the HC dosing system.

A further object of the invention is to provide an alternative method, an alternative device and an alternative computer program for achieving a reduction in the risk of a dosing unit in an HC dosing system overheating after switching off an exhaust gas flow in the HC dosing system.

These objects are achieved with a process for the HC dosing system for exhaust gas purification according to claim 1.

According to one aspect of the invention, there is provided a method of HC metering system for exhaust gas purification, including a fuel metering unit, comprising the steps of: - determining a need to, after shutting off an exhaust stream, cooling said fuel metering unit by fuel, and - predicting a temperature course in at least some of said HC dosing systems as a basis for determining said needs.

By providing a calculation model which is arranged to calculate the future maximum temperature of the dosing unit which will be reached, given stored energy of different parts of the HC dosing system, the shut-off of the exhaust gas flow can have a reduced influence of the HC dosing system. The calculation model is arranged to sample temperatures of different parts of the HC dosing system in the near future before and / or after switching off the exhaust gas flow and can on that basis predict whether the dosing unit will reach temperatures that are too high, at which temperatures the dosing unit could be damaged. In the event that it is determined that an excessively high temperature of the dosing unit is likely to be achieved, cooling of the fuel dosing unit by means of fuel can be maintained at any suitable level. In the event that it is determined that an excessively high temperature of the dosing unit will most likely not be reached, cooling of the dosing unit fuel by means of fuel can be switched off automatically. In this case, the number of occasions involving continued cooling of the fuel metering unit during shut-off of the exhaust gas flow can be reduced, which is advantageous in several aspects. For example. unnecessary use of electrical energy to drive a said fuel supply device in the HC dosing system is avoided.

The method may further comprise the step of predicting whether a predetermined temperature of the dosing unit will be reached after said shut-off of exhaust gas flow. By predicting a temperature course of the dosing unit, operation of the fuel supply device in the HC dosing system can be controlled in an optimal way, taking into account the use of electrical energy. By predicting a temperature course of the dosing unit, and automatically determining whether continued operation of the dispenser should cease, unnecessary cooling of the dosing unit can be avoided.

Said predetermined temperature may be a functionally critical temperature of the dosage unit. Said function-critical temperature is a temperature at which e.g. electronic components of the dosing unit may be damaged insofar as its functionality is degraded or eliminated. By setting said predetermined temperature to an appropriate value, a robust process is provided to reduce the risk of unit dosing in an HC dosing system overheating after shutting off an exhaust gas flow in the HC dosing system.

Said at least a portion of said HC dosing system may include any of a particulate filter, e.g. a DPF, a muffler, dosing unit advantageous temperature profile of the dosing unit. In cases such as a temperature course and the fuel. In particular, it is to be predicted for other components of the HC dosing system, such as e.g. the particulate filter or temperature profile of the dosage unit on the basis thereof. Said prediction muffler can be modeled a predicted of the temperature course of said at least a part of said HC dosing system thus enables indirect determination of a future temperature of the dosing unit. In particular, an indirect determination of a future maximum temperature of the dosing unit is made possible. Said prediction of the temperature course may include taking into account deheating effects of at least a part of the HC dosing system. Depending on how the HC dosing system has been operated, different amounts of thermal energy may be stored in different parts of the HC dosing system. This thermal energy can be led to the dosing unit even after switching off the exhaust gas flow.

According to one aspect of the invention, reheating effects are taken into account when modeling a temperature course of the dosing unit.

The method may further comprise the step of predicting said temperature course of at least a part of said HC dosing system by means of a calculation model including a predetermined parameter configuration. The parameter configuration may be any suitable parameter configuration, including e.g. a prevailing temperature of the particulate filter and / or a prevailing temperature of the muffler and / or a prevailing temperature of the fuel or metering unit.

The step of determining said need may be performed before said shutdown of exhaust gas flow, or the step of determining said need may be performed after said shutdown of exhaust flow. By determining said need before shutting off the exhaust flow, a decision to interrupt cooling of the dosing unit can be made more timely than if the step of determining said need is performed after said shutting off of exhaust flow. By determining the said need after shutting off the exhaust gas flow, a decision to interrupt cooling of the dosing unit can be made on the basis of a more updated basis compared with whether the said need is decided before shutting off the exhaust gas flow.

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

The procedure is easy to implement in existing motor vehicles. Software with an HC dosing system for exhaust gas purification according to the invention can be installed in a control unit of the vehicle in the manufacture thereof. A buyer of the vehicle can thus be given the opportunity to choose the function of the procedure as an option.

Alternatively, software comprising program code for performing the innovative process of an HC exhaust gas dosing system may be installed in the vehicle control unit when upgrading at a service station. In this case, the software can be loaded into a memory in the control unit. Implementation of the innovative method is thus cost-effective, especially since no additional components or subsystems need to be installed in the vehicle. Required hardware is already present in the vehicle today. The invention thus provides a cost-effective solution to the above problems.

Software comprising program code for determining a need to, after shutting down an exhaust stream, cooling a fuel metering unit, and predicting a temperature course of at least some of the said HC metering systems as a basis for determining said needs, according to an aspect of the invention, can be easily updated or replaced. Furthermore, different parts of the software that include program code to perform the innovative process are replaced independently. This modular configuration is advantageous from a maintenance perspective.

According to one aspect of the invention, there is provided an apparatus comprising an HC dosing system for exhaust gas purification, including a dosing unit of fuel. The device comprises means for determining a need to, after switching off an exhaust gas flow, cool said dosing unit for fuel by means of fuel, and means for predicting a temperature course of at least a part of said HC dosing system as a basis for determining said needs.

The device may further comprise means for predicting whether a predetermined temperature of the dosing unit will be reached after said shut-off of exhaust gas flow. Said predetermined temperature may be a functionally critical temperature for the dosing unit.

Said at least a portion of said HC dosing system may comprise any of a particulate filter, a muffler, the dosing unit or the fuel.

Said prediction of temperature course of said at least some of the above-mentioned HC dosing systems can enable indirect determination of a future temperature of the dosing unit.

Said prediction of the temperature course may include taking into account reheating effects of at least a part of the HC dosing system.

The device may further comprise means for predicting said temperature course of at least a part of said HC dosing system by means of a predetermined calculation model 'including a parameter configuration.

The means for determining said need may be arranged to determine said need before said shut-off of exhaust flow, or where the means for determining said need are arranged to determine said need after said shut-off of exhaust flow.

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

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

An advantage of the present invention is that the time as a control unit of the vehicle does not have to be activated as often or as long as before to monitor and control the fuel supply device.

According to one aspect of the invention, there is provided any platform comprising a device with an HC dosing system, such as e.g. watercraft. The watercraft can be of any kind, such as e.g. a motorboat, a ship, a ferry or a ship.

According to one aspect of the invention, there is provided a computer program of HC dosing system for exhaust gas purification, including a dosing unit of fuel, said computer program comprising program code stored on a computer readable medium for causing an electronic control unit or other computer connected to the electronic control unit to perform the steps according to any one of claims 1-9.

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 1-9, when said computer program is run on an electronic control unit or another computer connected to the electronic control unit.

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 the practice of the invention. While the invention is described below, it should be understood that the invention is not limited to the specific description details. 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: 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 3 schematically illustrates a subsystem of the vehicle shown in Figure 1, according to an embodiment of the invention; Figure 4a schematically illustrates a flow chart of a method, according to one embodiment of the invention; Figure 4b schematically illustrates in further detail a flow chart of a method, according to an embodiment of the invention; and Figure 5 schematically illustrates a computer, 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 with 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 other than an HC dosing system, 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 motors and / or motor-driven industrial robots and / or a stationary motor. 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 and the innovative device are well suited to 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 is well suited to any system which includes a particulate generator (eg an internal combustion engine) and an HC dosing system.

Here, the term "link" refers to a communication link which may be a monophysical line, such as an opto-electronic 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 fluid, such as e.g. a fuel in the liquid form. The pipe can be a pipe of any 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. Board fuel is, according to one embodiment, diesel. Of course, other types of 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, co-requisites 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 refer to 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 pre-regeneration of the selected particulate filter.

With reference 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. According to this example, the subsystem 299 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 pump230 may be a diaphragm pump comprising at least one filter. The pump230 is arranged to be driven by means of an electric motor. The pump is 230 arranged to pump up the fuel from the container 205 via the first line 271 and via the 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 metering unit 250 is arranged to supply said fuel to a 100. The metering unit 250 is arranged to supply in a controlled manner a suitable amount of exhaust system (not shown) to the vehicle. More specifically, it is fuel to an exhaust system of the vehicle 100. According to this embodiment, a particulate filter (not shown) for example a DPF, arranged downstream of a position of the exhaust system where the supply of fuel is provided. The amount of fuel 14 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 divert exhaust gases from the internal combustion engine 150 of the vehicle 100 to the 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 includes plastic and / or rubber components, arranged to handle communication with a control unit which may melt or otherwise be 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 in excess of operation of the vehicle or after operation of the vehicle unless cooling thereof is provided.

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 fuel fed to the metering valve 250 to the container 205. With this configuration, cooling of the dosing unit 250 is advantageously provided. In this way, the dosing unit 250 is cooled by means of a flow of the fuel as it is pumped through the dosing unit 250 from the pump 230 to the container 205.

A first control unit 200 is arranged for communication with a temperature sensor 220 via a link 293. The temperature sensor 220 is arranged to detect a prevailing temperature of the fuel where the sensor is mounted. According to this embodiment, the temperature sensor 220 is arranged in the container 205. The temperature sensor 220 is arranged to continuously send signals to the first control unit 200 including information about a prevailing temperature of the fuel. According to an alternative, the 220 dosing unit is 250 for detecting a prevailing temperature there. According to another embodiment of the temperature sensor, the temperature sensor 220 is arranged at the particle filter of the HC dosing system to detect a prevailing temperature there. An arbitrary number of temperature sensors may be provided in the subsystem 299 to detect a prevailing temperature therewith. The temperature sensor 220 or the temperature sensors 220 are arranged (e) to detect a prevailing temperature at a suitable position within the subsystem 299, which detected temperature can form the basis for controlling operation of the pump 230 for cooling the dosing unit by means of said flow of fuel.

The first control unit 200 is arranged for communication with the pump 230 via a link 292. The first control unit 200 is arranged to control the operation of the pump 230 in order to e.g. regulating a pressure in the line 272. Thereby, a return flow of the fuel from the dosing unit 250 to the container 205 can be described as a function of a pressure of the fuel upstream of the dosing unit 250. The first control unit 200 is arranged to regulate a prevailing temperature of the dosing unit by controlling operation of the pump 230.

The first control unit 200 is arranged for communication with the dosing unit 250 via a link 291. 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. The first control unit 200 16 is arranged to control the operation of the dosing unit 250 in order to e.g. regulate the re-supply of fuel to the tank 205.

The first control unit 200 is according to an embodiment arranged to control on the basis of the signals received from the temperature sensor including information about the prevailing temperature of the fuel at any suitable position of the HC dosing system control operation of the pump 230. In particular, the first control unit 200 according to one embodiment is arranged to on the basis of the received signals comprising a prevailing temperature of the fuel at the area of the pre-temperature sensor 220 intermittently control operation of the pump 230 with reduced power compared to ordinary operation after shutting off an exhaust gas fl from the engine.

A second control unit 210 is arranged for communication with the first control unit 200 via a link 290. The second control unit 210 may be releasably 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 can be arranged to perform the innovative process steps according to the invention. The second control unit 210 can be used to load overhead 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 the same functions as the first control unit 200, such as calculating a value for future maximum temperature of the dosing unit on the basis of the received signals comprising a prevailing temperature of the fuel and controlling operation of the pump 230 at any time. suitably on the basis of the calculated temperature value. The second control unit 210 is arranged to determine a need to, after switching off one exhaust gas flow, cool a dosing unit for fuel by means of fuel, and to predict a temperature course of at least a part of said HC dosing system as a basis for determining said needs. It should be noted that the innovative procedure 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 the embodiment schematically illustrated with reference to Figure 2, the first control unit 200 is arranged to control operation of the pump 230 with reduced power compared to ordinary operation after shutting off one exhaust gas flow from the engine in such a way that, where applicable, a quantity required electrical energy to cooling the dosing unit 250 to a safety-critical temperature is reduced compared to the prior art.

According to this embodiment, a source of compressed air 260 is arranged to supply compressed 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 dispense said fuel into the exhaust duct. The compressed air can also be used to, where applicable, blow out e.g. dosing unit 250 with respect to fuel present 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, 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 as 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 3 schematically illustrates a subsystem 399 of the vehicle 100. The subsystem 399 includes certain components described above with reference to Figure 2, such as e.g. the first control unit 200, the second control unit 210 and the temperature sensor 220 for detecting a prevailing temperature of the fuel in the container 205.

The subsystem 399 includes a temperature sensor 310 which is arranged to measure a prevailing temperature of exhaust gases in an exhaust system upstream particulate filter. The temperature sensor 310 is arranged for communication with the first control unit via a link 311. The temperature sensor 310 is arranged to continuously send signals including information about a prevailing temperature of the exhaust stream to the first control unit 200 via the link 311. According to one embodiment, the first control unit 200 is arranged to estimate a prevailing temperature of the particle filter on the basis of the prevailing prevailing temperature of the signals comprising information about an exhaust gas flow.

The subsystem 399 includes a temperature sensor 320 which is arranged to measure a prevailing temperature of the particulate filter. The temperature sensor 320 is arranged for communication with the first control unit via a link 321.

The temperature sensor 320 is arranged to continuously send signals 19 including information about a prevailing temperature of the particle filter to the first control unit 200 via the link 321.

The subsystem 399 includes a temperature sensor 330 which is arranged to measure a prevailing temperature of the dosing unit 250. The temperature sensor 330 is arranged for communication with the first control unit via a link331. The temperature sensor 330 is arranged to continuously send signal-containing information about a prevailing temperature of the dosing unit 250 to the first control unit 200 via the link 331.

The subsystem 399 includes a flow sensor 340 which is arranged to measure a prevailing flow of the fuel in the HC dosing system. The flow sensor 340 may be arranged at any suitable position of the HC-273 dosing unit 250. The flow sensor 340 is arranged for communication dosing system, such as e.g. at the line downstream of the first control unit via a link 341. The flow sensor 340 is arranged to continuously send signals including information about a prevailing flow of the fuel to the first control unit 200 via the link 341.

The signals transmitted by the sensors 310, 320, 330, 340 and 220, respectively, can be used by the first control unit to model a temperature profile of the dosing unit 250 according to an aspect of the invention. According to one embodiment, the first control unit 200 is arranged to model a temperature profile of the dosing unit 250 on the basis of the information of at least one of the signals received from the sensors 310, 320, 330, 340 and 220, respectively.

Figure 4a schematically illustrates a flow chart of a process in HC exhaust gas purification systems, including a fuel metering unit, according to an embodiment of the invention. The method comprises a first method step s401. The step s401 comprises the step of determining a need to, after switching off an exhaust flow, cooling said dosing unit for fuel by means of fuel, and the step of predicting a temperature course of at least a part of said HC dosing system as a basis for determining said need. After step s401, the process is terminated.

Figure 4b schematically illustrates a flow chart of a process in HC metering system for exhaust gas purification, including a fuel metering unit, according to an embodiment of the invention.

The method includes a first method step s410. Method step s410 includes the step of shutting off an exhaust gas flow from an internal combustion engine of the vehicle 100. At this time, the metering unit 250 is cooled in an ordinary manner, i.e. with the operating power of the pump 230 needed to maintain substantially the same cooling flow of the dosing unit as in normal operation.

Shut-off of the exhaust gas is effected when the engine of the vehicle 100 is switched off. After the process step s410, a subsequent process step s415 is performed. the temperature course can take place on the basis of one or a number of arbitrary parameters, such as e.g. a prevailing temperature of the particulate filterthos vehicle, a prevailing temperature of the fuel, a flow of the fuel in the HHC dosing system, a prevailing temperature of a muffler of the vehicle, a prevailing temperature of the dosing unit 250, an exhaust flow temperature before shutting down and / or a parameter associated with estimated engine load for a certain period of time before shutting off the exhaust gas flow. The calculation model is arranged to calculate a prevailing amount of stored energy in different parts of the HC dosing system in order to calculate on that basis and thereby predict a temperature course of the dosing valve 250 as a basis for determining a need to cool the dosing unit 250. By calculating a future temperature course 21 of the dosing unit 250 it can also be determined what maximum temperature the dosing unit 250 can reach in the event that cooling thereof does not proceed or is interrupted after the shut-off of the exhaust gas flow. By determining a modeled value for a maximum future temperature of the dosing unit 250, operation of the pump 230 can be optimally controlled after the s415 procedure step s420. basis thereof. the process step is performed a subsequent The process step s420 includes the step of evaluating whether there is a continuing need to cool the dosing unit by means of a flow of the fuel in the HHC dosing system. The step of determining whether there is a need to continue said cooling can be made on the basis of the determined modeled value for maximum future temperature of the dosing unit 250. According to one example, it is determined whether a continued cooling need exists on the basis of the signals from at least one of the sensor 220, sensor 310, sensor 320 , the sensor 330, the sensor 340, which signals include information in accordance with what has been described above with reference to Figure 3. If there is no further cooling need, the process is terminated. If there is a continuing cooling need, a subsequent procedure step s430 is performed.

Method step s430 includes the step of affecting the operation of the pump 230 in such a manner that the pump is operated intermittently and / or with reduced operating power compared to ordinary operation. According to one embodiment, the pump 230 is operated intermittently with a predetermined interval configuration. According to one embodiment, the pump 230 is operated intermittently with an operating power corresponding to ordinary operation. According to one embodiment, the pump 230 is operated intermittently with a reduced operating power compared to an operating power used to maintain a cooling flow housing dosing unit 250 during ordinary operation. After the process step s430, a subsequent process step s440 is performed.

Process step s440 includes the step of evaluating whether there is a continuing need to continue cooling the metering unit by means of a flow of the fuel in the HC metering system. The step of determining whether there is a need to continue said cooling can take place on the basis of an updated modeled value for maximum future temperature of the dosing unit 250. According to one embodiment, the calculation model is arranged to continuously update a fixed modeled value for the future maximum temperature of the dosing unit 250. updated value for said maximum temperature can be performed in essentially the same way as described e.g. with reference to procedure step s415. According to an example, it is determined whether a continued cooling demand exists on the basis of the signals from at least one of the sensor 220, sensor 310, sensor 320, sensor 330, sensor 340, which signals include information as described above with reference to Figure 3. If it is determined that if there is no need for further cooling, the procedure is terminated. If it is determined that there is a need for continued cooling, operation of the pump 230 continues in an arbitrary manner to ensure efficient cooling of the dosing unit 250. Eg. the pump 230 can continue to be operated intermittently, possibly even with reduced operating power compared to ordinary operation.

Referring to Figure 5, a diagram of an embodiment of a single device 500 is shown. The controllers 200 and 210 described with reference to Figure 2 may in one embodiment include the device 500. The device 500 includes a non-volatile memory 520, a data processing unit 510 and a read / write memory 550. The non-volatile memory 520 has a first memory portion 530 in which a computer program, such as an operating system, is stored to control the operation of the device 200. Further, the device 500 includes a bus controller, a serial communication port, I / O means , an A / D converter, one-time and date input and transfer unit, an event counter and an interrupt controller (not shown). The non-volatile memory 520 also has a second memory portion 540.

A computer program P is provided which comprises routines for determining a need to, after switching off an exhaust flow, cool a dosing unit for 23 fuel by means of fuel, and to predict a temperature course in at least a part of said HC dosing system as a basis for determining said need. under the innovative procedure. The Pinne program includes routines for predicting whether a predetermined temperature of the dosing unit will be achieved after said shutdown of the exhaust gas flow. The program P can be stored in an executable manner or in a compressed manner in a memory 560 and / or in a read / write memory 550.

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

The data processing device 510 can communicate with a data port 599 via the 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 to communicate with the data processing unit 510 via the data bus 511. the data processing unit 510 via a data bus unit 510. To the data port 599 edge.ex. links 311, 321, 331, 341, 293 and 290 are connected (see Figure 3).

The read / write memory 550 is arranged to communicate with When data is received on the data port 599 it is temporarily stored in the second memory part 540. When the received input data has been temporarily stored, the data processing unit 510 is prepared to perform code execution in the manner described above. According to one embodiment, signals received at the data port 599 include information of a prevailing temperature of a particulate filter housing of the vehicle 100. According to one embodiment, signals received at the data port 599 include information of a prevailing temperature of the fuel in the HC dosing system. According to one embodiment, signals received on the data port 599 include information about a prevailing flow of the fuel, e.g. 273. According to one embodiment, signals received at the data port 599 include information about a prevailing temperature of the dosing unit 24 250 of the HC dosing system. According to one embodiment, signal received at the data port 599 includes information about a prevailing temperature of an exhaust flow in the exhaust system of the vehicle 100.

The received signals on the data port 599 can be used by the device 500 to determine by means of a calculation model stored in the device 500 a need to, after switching off an exhaust flow, cool a dosing unit for fuel by fuel, and predict a temperature course in at least a part of said HC dosing system. basis for determining the said needs.

Parts of the methods described herein may be performed by the device 500 by means of the data processing unit 510 running the program stored in the memory 560 or read / write memory 550. When the device 500 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 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 (3)

A method of HC exhaust gas purification system, including a fuel metering unit (250), comprising the steps of: - determining a need to, after shutting off an exhaust stream, cooling said fuel metering unit (250), which forms part of said HC the dosing system, by means of fuel, which is supplied to the dosing unit (250), characterized by the steps of: - predicting a temperature course of the gag dosing unit (250) as a basis for determining said needs, said temperature course being predicted by means of a calculation model. a part of said HC dosing system for calculating on that basis a temperature course of the gas dosing unit (250), and thereby - predicting whether a predetermined temperature of the gd dosing unit (250) will be reached after said shut-off of exhaust gas flow. The method of claim 1, wherein said predetermined temperature is a functionally critical temperature for said dosage unit (250). A method according to any one of the preceding claims, wherein said at least one electricity of said HC dosing system comprises at least one of a particle filter, a silencer, said dosing unit (250) and said fuel. A method according to any one of the preceding claims, wherein said prediction of the temperature course involves consideration of reheating effects of at least a part of said HC dosing system. lay. A method according to any one of the preceding claims, wherein the step of determining said need is performed before said shut-off of exhaust gas flow, or the step of determining said need is performed after said shut-off of exhaust gas flow. SQ. A method according to any one of the preceding claims, wherein said fuel is diesel. HC dosing system comprising an exhaust gas purification device, including a fuel dosing unit (250), comprising: - means (200; 210; 500) for determining a need to cool said dosing unit (250) after shutting off an exhaust gas flow. for fuel, which forms part of the ggga fl C dosing system, by means of fuel, which is intended to be supplied to the ggd_dosing unit (250), characterized by - means (200; 210; 500) for predicting a temperature course of said dosing unit (250) as a basis for determining said If necessary, said temperature course is predicted by means of a calculation model which is arranged to calculate a prevailing amount of energy stored in at least one part of said HC dosing system in order to calculate on that basis a temperature course of said dosing unit (250), and hereby 27 means (200; 210; 500; ) to predict whether a predetermined temperature of the said dosage unit (250) will be reached after said shutdown of the exhaust gas flow. 40§. HC dosing system according to claim 9_7_, wherein said predetermined temperature is a functionally critical temperature for said dosing unit (250). an additional at least a portion of said HC dosing system includes at least some of a particulate filter, a muffler, said dosing unit (250) and said fuel. fl fâ fl. HC dosing system according to any one of claims 9Z-42Q, wherein said temperature course reheating effects taking into account said HC prediction of include at least a portion of the dosing system. HC1 dosing system according to any one of claims 447-10, wherein said means for determining said need is arranged to determine said need before said 28 shut-off of exhaust flow, or wherein said means for determining said need is arranged to determine said need after said shut-off of exhaust gas flow. train. HC dosing system according to any one of claims 91-4511, wherein said fuel is diesel. HQ. Motor vehicle (100; 110) comprising an HC dosing system according to any one of claims 9Z-4ßQ. fl fë fl. Motor vehicle (100; 110) according to claim HQ, wherein said motor vehicle is something of a truck, bus or passenger car. 4-91_5.including a dosing unit (250) for fuel, wherein said computer program (P) in HC dosing system for exhaust gas purification, computer program (P) comprises program code for causing an electronic control unit (200; 500) or another computer ( 210; 500) connected to the said electronic control unit (200; 500) to perform the steps according to any of the patent claims 1-8§. ZOJQ. Computer program product comprising a program code stored on a computer-readable medium for performing the process steps according to any one of claims 1-8, when said elater program is run on an electronic control unit (200; 500) or another computer (210; 500) connected electronic_e | electronic control unit (200; 500).