SE1100921A1 - Method of HC dosing with pressure control on the basis of a temperature at exhaust pipes - Google Patents

Abstract

The invention relates to a method in the HC dosing system of a motor vehicle (100; 110), comprising a feeding device (230) for supplying fuel from the container (205) to a dosing unit (250) for supplying said fuel to an exhaust duct of the vehicle (100). ; 110). The method comprises the step of controlling the dosing of the dosing unit (250) by means of a pressure (Pr) below which fuel is dosed. The invention also relates to a computer program product comprising program code (P) for a computer (200; 210) for implementing a method according to the invention. The invention also relates to an HC dosing system and a motor vehicle (100) equipped with the HC dosing system. Figure 2 for publication

Description

25 30 back to the container. According to this configuration, it is possible to cool the dosing unit by means of said diesel which, when cooled, flows from the container via the pump and the dosing unit back to the container.

There is a constant need to reduce the amount of emissions from the engines of motor vehicles. This applies not least to heavy motor vehicles such as e.g. trucks and buses as legal requirements for ever smaller emissions are continuously tightened.

There are various ways to reduce emissions from motor vehicles. One way is to regulate in a different way a prevailing temperature of the exhaust gas flow in order to optimize a degree of conversion between exhaust gases and evaporated metered fuel in the vehicle.

SUMMARY OF THE INVENTION There is a constant need to improve the current HC dosing system to reduce the amount of unwanted emissions from an internal combustion engine.

An object of the present invention is to provide a new and advantageous HC dosing system. Another object of the invention is to provide a new and advantageous HC dosing system 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 reducing the amount of unwanted emissions from an internal combustion engine. 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 HC dosing system.

These objects are achieved by a method in an HC dosing system of a motor vehicle according to claim 1.

According to one aspect of the invention, there is provided a method of HC dosing system of a motor vehicle, comprising a feeding device for supplying fuel from a container to a dosing unit for supplying said fuel to an exhaust duct of the vehicle. The method comprises the step of controlling the dosing of the dosing unit by means of a pressure below which fuel is dosed.

HC working pressure of said fuel This enables a flexible dosing of fuel in a dosing system. A relatively high generally produces smaller droplets that can be more easily captured in an exhaust stream from the vehicle's engine. A relatively low operating pressure of said fuel can generally produce larger droplets which with a higher kinetic energy are not affected by the exhaust gas flow in the same way as smaller droplets. In some operating cases it is advantageous with smaller drops, e.g. at low exhaust temperature where a small drop can evaporate relatively quickly in the exhaust flow. In another operating case, where a high thermal energy is stored in the exhaust system, it is advantageous to have larger droplets which can then be directed towards e.g. a surface of the exhaust system. This results in an improved performance of the HC dosing system.

By according to the invention varying the working pressure in a suitable manner, depending on e.g. inherent characteristics of the dosing unit, a cone angle of the dosed fuel can be advantageously changed in a desired manner. In analogy to the above, this can be used to optimize the hit image and / or mixture of fuel and exhaust gases. By changing an operating pressure of the HC dosing system, the speed of the fuel droplets can also be affected. This entails substantially identical benefits as described above.

By controlling the dosing of the dosing unit by means of the pressure under which fuel is dosed, an associated droplet size distribution can thus be influenced. This can have a big impact depending on the type of dosing equipment used.

The method may include the step of controlling the pressure below which fuel is dispensed by controlling a speed of said feed device. Hereby an accurate method is provided in an HC dosing system according to an aspect of the invention. Said pump speed can be controlled with very high accuracy and thus a working pressure of the HC dosing system can also be controlled with a high accuracy. In this case, a robust method can be achieved in a reliable manner.

The method may include the step of controlling the pressure by changing a throttle in a fuel return line from the metering unit to said container. Hereby an accurate method is provided in an HC dosing system according to an aspect of the invention. Said throttling can be changed with very high accuracy and thus a working pressure of the HC dosing system can also be controlled with a high accuracy. In this case, a robust method can be achieved in a reliable manner.

The method may include the step of controlling the pressure by changing the configuration of the dosage unit. Hereby an accurate method is provided in an HC dosing system according to an aspect of the invention.

Said configuration can be changed with very high accuracy and thus a working pressure of the HC dosing system can also be controlled with a high accuracy. In this case, a robust method can be achieved in a reliable manner. The method may comprise the step of controlling the dosing of the dosing unit by the pressure on the basis of a prevailing temperature of an exhaust gas flow from an engine and / or a prevailing mass flow of exhaust gases from an engine. Hereby an improved performance of the HC dosing system can be achieved.

In this case, a versatile procedure is also provided with an HC dosing system, since alternative embodiments are possible. A prevailing mass flow of the exhaust gases can be calculated by a control unit of the vehicle, or alternatively measured by means of a mass flow sensor. Since temperature sensors are relatively inexpensive, a cost-effective method according to one aspect of the invention is also provided.

The method may comprise the step of controlling the dosing of the dosing unit by means of the pressure on the basis of a prevailing temperature of a surface in an exhaust pipe of the vehicle. Therefore, the intended temperature sensor must be installed in the vehicle in a suitable manner if one is not already installed.

The method may comprise the step of controlling the dosing of the dosing unit by means of the pressure on the basis of a prevailing temperature of an ambient air of the vehicle. Therefore, the intended temperature sensor must be installed in the vehicle in a suitable manner if one is not already installed.

The method may include the step of controlling the dosing of the dosing unit by means of the pressure on the basis of previous operating cases of the vehicle. In this case, a control unit of the vehicle is arranged to control the dosage of the dosing unit by means of the pressure in a suitable manner by means of calculations according to a stored model.

The method may include the step of controlling the dosage of the dosage unit by the pressure and a cycle frequency of the dosage. In this case, a process is provided in an HC dosing system with improved performance. By combining control of the dosing unit dosing by means of the pressure of the fuel during dosing and by means of changes of a prevailing cycle frequency of HC dosing system, an optimized spray image of said dosed fuel can be achieved. In this case, the amount of undesired emissions from the vehicle's engine can be advantageously reduced.

The process may comprise the step of varying the pressure of the fuel within a range of [5, 15] bar. According to one embodiment, the method may comprise the step of varying the pressure of the fuel within a range of [7, 13] bar. According to one embodiment, the method may comprise the step of varying the pressure of the fuel within a range of [10, 50] bar. According to one embodiment, the method may comprise the step of varying the pressure of the fuel within a range of [100, 300] bar. According to one embodiment, the method may comprise the step of varying the pressure of the fuel within any suitable interval. Hereby a robust method is provided where a working interval is defined in advance and thus eliminates risk of unwanted spray image caused by too low or high working pressure. Hereby a reliable and reliable method is provided in an HC dosing system according to an aspect of the present invention.

The method may comprise the step of varying the pressure of the fuel steplessly in said control of the dosage of the dosing unit. Hereby a method is provided where a desired spray image of said fuel can be set in a well-defined manner. In this case, a method of an HC dosing system is advantageously provided where a desired mixture of exhaust gases and fuel can be set with a very high accuracy.

The method may further comprise the step of varying the pressure of the fuel in discrete steps in said control of the dosing unit dosage. This provides a method of an HC dosing system where relatively simple programming routines are required. By providing control of the dosing unit dosing where discrete adjustable steps of the working pressure are present, a speed of the feeding device can be controlled towards predetermined setpoints, which has the advantage that less computationally heavy data processing is required. The method may comprise the step of changing a cycle frequency of the dosage steplessly. Hereby a method is provided where a desired spray image of said fuel can be set in a well-defined manner. In this case, a method of an HC dosing system is advantageously provided where a desired mixture of exhaust gases and fuel can be set with a very high accuracy.

The method may comprise the step of changing a cycle frequency of the dosage in discrete steps in said control of the dosage of the dosage unit. By providing control of the dosing unit dosage where discrete adjustable steps of the cycle frequency are present, a speed of the feeding device can be controlled towards predetermined setpoints, which has the advantage that less computationally heavy data processing is required.

The method may comprise the step of controlling the dosing of the dosing unit by means of the pressure and a cycle frequency of the dosing on the basis of a prevailing exhaust gas temperature and / or a prevailing exhaust gas mass flow of exhaust gases from an engine of the motor vehicle.

It should be noted that the method may include one or more of the above features in an appropriate combination.

The procedure is easy to implement in existing motor vehicles. Software in an HC dosing system 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 have the opportunity to choose the function of the procedure as an option. Alternatively, software may include program code to perform the innovative procedure of an HC dosing system. 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. Required hardware is today 10 15 20 25 30 already pre-arranged in the vehicle. The invention thus provides a cost-effective solution to the above problems.

Software that includes program code for an HC dosing system according to the invention can be easily updated or replaced. Furthermore, different parts of the software that include the program code can be replaced independently of each other.

This modular configuration is advantageous from a maintenance perspective.

According to one aspect of the invention, there is provided an HC dosing system of a motor vehicle, comprising a feeding device for feeding fuel from a container to a dosing unit for supplying said fuel to an exhaust duct of the vehicle. The HC dosing system comprises means for controlling the dosing of the dosing unit by means of a pressure below which fuel is dosed.

The HC dosing system may further comprise means for controlling the pressure by controlling a speed of said feeding device.

The HC dosing system may include means for controlling the pressure by changing a throttle in a fuel return line from the dosing unit to said container.

The HC dosing system may include means for controlling the pressure by changing the configuration of the dosing unit.

The HC dosing system may comprise means for controlling the dosing of the dosing unit by means of the pressure on the basis of a prevailing temperature of an exhaust gas flow from an engine and / or a prevailing mass flow of exhaust gases from an engine.

The HC dosing system may further comprise means for controlling the dosing of the dosing unit by means of the pressure of the fuel and a cycle frequency of the dosing. The HC dosing system may further comprise means for varying the pressure of the fuel within a range of [5, 15] bar.

The HC dosing system may comprise means for varying the pressure of the fuel steplessly in said control of the dosing unit.

The HC dosing system may comprise means for varying the pressure of the fuel in discrete steps in said control of the dosing unit dosage.

The HC dosing system may comprise means for changing a cycle frequency of the dosing steplessly or in discrete steps in said control of the dosing unit dosing.

The HC dosing system may comprise means for controlling the dosing of the dosing unit by means of the pressure and a cycle frequency of the dosing on the basis of a prevailing exhaust gas temperature and / or a prevailing exhaust mass flow of exhaust gases from an engine of the motor vehicle.

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

According to one aspect of the invention, there is provided a computer program for an HC dosing system, 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 perform the steps of any of the claims 1-11.

According to one aspect of the invention, there is provided a computer program for an HC dosing system, said computer program comprising program code for causing an electronic control unit or another computer connected to the electronic control unit to perform the steps according to any one of claims 1-11. 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 according to any one of claims 1-11, 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 through 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 incorporations within other additional applications, modifications, and 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 according to an embodiment of Figure 4, a computer schematically illustrates the invention. DETAILED DESCRIPTION OF THE FIGURES Referring to Figure 1, a side view of a vehicle 100 is shown. The exemplary vehicle 100 consists of a tractor 110 and a trailer 112.

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

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 HC dosing system according to an aspect of the invention are also well suited for e.g. systems including industrial engines and / or powered industrial robots.

The innovative method and the innovative HC dosing system 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 procedure and the innovative 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 particle generator (eg an internal combustion engine) and an HC dosing system. 10 15 20 25 30 12 The innovative method and the innovative device are well suited for an arbitrary system which includes a device which generates exhaust gases with particles and a filter which can store particles, which particles are combusted during a regeneration of said filter, in particular during an active regeneration of said filter.

It should be noted that the HC dosing system can be any HC dosing system, although it is exemplified herein as an HC dosing system in a DPF system of a vehicle. The feed device may be any feed device, and need not be a diaphragm pump as described herein.

The fuel of the HC dosing system may be any suitable fuel, such as e.g. oil, such as e.g. lubricating oil, diesel or other hydrocarbon-based fuel, such as e.g. gasoline, ethanol or methane, etc.

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.

Herein, the term "conduit" refers to a passageway for holding and transporting a fluid, such as e.g. a fuel in 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.

Here, 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 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 the necessary adaptations, such as e.g. adjustments to adequate boiling temperature for selected fuels, in control algorithms to execute software code in accordance with the innovative procedure.

Here, the term cycle frequency refers to a frequency defined by the number of dosing intervals, also called dosing cycles, per second. It should be noted, however, that at least one active dosing of fuel of the dosing unit can be performed during a dosing cycle.

Here, the term pressure of the fuel refers to a pressure below that mentioned in that dosing system. The pressure below which said fuel is dosed and fuel is dosed from a dosing unit innovative HC working pressure Pr is used synonymously herein. Although the term "HC dosing system" is used herein to denote 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 hold 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 205 may be an existing fuel tank of the vehicle.

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 may be arranged to be operated by means of an electric motor (not shown). The pump 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 device, by means of which a flow of to the exhaust system added fuel can be controlled. The dosing unit 250 may comprise 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, which may also be called a throttle valve, against which said pressure of the fuel can be built up in the subsystem 299. This pressure is referred to herein as the working pressure Pr of HC- dosing system.

Dosing unit 250 is arranged to supply said fuel to a 100. Dosing unit 250 is arranged to supply in a controlled manner a suitable amount of exhaust system (not shown) to the vehicle. More specifically, fuel is to an exhaust system of the vehicle 100. According to this embodiment, an oxidation catalyst (not shown) arranged downstream of a position of the exhaust system where the supply of fuel is effected. The amount of fuel supplied to the exhaust system is intended to be used in the oxidation catalyst to effect active regeneration.

The dosing unit 250 may be arranged at an exhaust pipe (not shown) which is arranged to direct exhaust gases from an internal combustion engine (not shown) of the vehicle 100 to the oxidation catalyst and further to an environment of the vehicle.

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 dosing unit 250 is cooled by 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 pressure sensor 220 via a link 221. The pressure sensor 220 is arranged to detect a prevailing pressure Pr of the fuel where the sensor is mounted. According to this embodiment, the pressure sensor 220 is arranged at the second line 272 to measure the working pressure Pr of the fuel downstream of the pump 230. According to another embodiment, the pressure sensor 220 is arranged in the dosing unit 250 to measure the working pressure Pr of the fuel downstream of the pump 230. The pressure sensor 220 is arranged to signals continuously sent via the link 221 to the first control unit 200 including information about a prevailing pressure Pr of the fuel.

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. According to an example, the first control unit 200 is arranged to control the pump 230 by means of an electric motor. The first control unit 200 is arranged to influence the working pressure Pr in the second line 272. This can be done in various suitable ways.

According to one example, the first control unit 200 is arranged to change a prevailing speed RPM of the pump 230. In this case, the pressure Pr can be changed in a desired manner. By increasing the RPM speed of the pump 230, the working pressure Pr can be increased. By lowering the RPM speed of the pump 230, the working pressure Pr can be reduced.

According to another example, the first control unit 200 may be arranged to influence the pressure Pr by controlling a change of a stroke of a piston or a diaphragm of the pump 230. By influencing an internal configuration or internal geometry of the pump 230, the pressure Pr may also be varied. while maintaining a substantially constant RPM speed of the pump 230. In this case, the influence of the pressure Pr can be achieved by e.g. change a stroke of pistons or diaphragms of the pump 230. The first control unit 200 is arranged for communication with a temperature sensor 240 via a link 241. The temperature sensor 240 is arranged to detect a prevailing temperature T of an exhaust stream from the vehicle engine. . According to one example, the temperature sensor 240 is arranged directly downstream of the engine of the vehicle and upstream of a dosing unit 250.

The temperature sensor 240 is arranged to continuously detect a prevailing temperature T of the exhaust gas stream and send signals including information about said prevailing temperature T via the link 241 to the first control unit 200.

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. regulate the supply of fuel to the exhaust system of the vehicle 100.

The dosing unit 250 may comprise a nozzle for dosing the fuel for mixing with exhaust gases in an exhaust system of the vehicle 100. According to one embodiment, a geometry of said nozzle may be variable, whereby a control of the pressure Pr of the fuel can be achieved. The first control unit 200 is the dosing unit so as to control the pressure Pr of the fuel. arranged to influence said variable configuration of the first control unit 200 is according to an embodiment arranged to drive said pump 230 on the basis of the signals received from the pressure sensor 220 comprising information about a prevailing pressure of the fuel in a manner which according to an aspect of the innovative method . In this case, a feedback control of the working pressure Pr.

The first control unit 200 is arranged to calculate an exhaust mass flow MF of the exhaust gases from the vehicle engine. The first control unit 200 is arranged to continuously determine an exhaust mass flow MF of the exhaust gases from the vehicle engine. This can be done in any suitable way.

According to one embodiment, the subsystem comprises a mass flow sensor (not shown) which is arranged to continuously measure a prevailing exhaust mass fl from the engine of the vehicle 100. Said mass flow sensor is arranged to continuously send signals including information about a prevailing exhaust mass flow to the first control unit.

The first control unit 200 may be arranged to control the dosing of the dosing unit 250 by means of a pressure Pr during which fuel is dosed. The first control unit 200 may be arranged to control the pressure Pr by controlling the RPM speed of the pump 230. The first control unit 200 may be arranged to control the pressure Pr by changing a throttle in the line 273 for fuel from the dosing unit 250 to the container 205. According to a alternatively, the first control unit 200 is arranged to control the pressure Pr by changing a throttle of fuel flow in the dosing unit 250, which fuel flow is intended to lead to the container 205. The first control unit 200 may be arranged to control the pressure Pr by changing the configuration of the dosing unit 250 dosing device . The first control unit 200 may be arranged to control the dosing of the dosing unit 250 by means of the pressure Pr on the basis of a prevailing temperature T of an exhaust gas flow from an engine and / or a prevailing mass flow MF of exhaust gases from an engine. The first control unit 200 may be arranged to control the dosing of the dosing unit 250 by means of the pressure Pr of the fuel and a cycle frequency CF of the dosing. The first control unit 200 may be arranged to vary the pressure Pr of the fuel within a range of [5, 15] bar. The first control unit 200 may be arranged to vary the pressure Pr of the fuel steplessly in said control of the dosage of the dosing unit 250. The first control unit 200 may be arranged to vary the pressure Pr of the fuel in discrete steps in said control of the dosage of the dosing unit 250. The first control unit 200 may be arranged to change a cycle frequency CF of the dosing steplessly or in discrete steps in said control of the dosing unit 250 dosing. The first control unit 200 may be arranged to control the dosing of the dosing unit 250 by means of the pressure Pr of the fuel and a cycle frequency CF of the dosing on the basis of a prevailing exhaust gas temperature T and / or a prevailing exhaust mass flow MF of exhaust gases from an engine of the motor vehicle.

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. to control the dosing of the dosing unit 250 by means of a pressure Pr below which fuel is dosed. 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.

Below are some examples of how the working pressure Pr can be controlled by the first control unit 200 for some different operating cases of the motor vehicle 100.

Example 1. This determines a change from a reference state to a state with higher exhaust gas temperature and higher exhaust gas mass flow MF (e.g.

T> 400 degrees C and MF> 1000 kg / h.) The working pressure Pr is thereby reduced (from eg 9 bar to 5 bar) to produce larger dosed fuel droplets that can be better controlled in the high exhaust gas flow and hit the desired hot surface in the exhaust system of the vehicle. In this case, a controlled wall hit is advantageously achieved. Example 15 This determines a change from a reference state to a state with higher exhaust gas temperature T and lower mass flow (eg T> 400 degrees C and MF <1000 kg / h). The working pressure Pr is thereby raised (from, for example, 9 bar to 15 bar) in order to produce smaller fuel droplets which can be evaporated directly in the exhaust gas flow before it hits a surface in the exhaust system of the vehicle. In this case, advantageously improved evaporation of fuel is achieved before hitting the wall.

Example 3. This determines a change from a reference state to a state with lower exhaust gas temperature T and higher exhaust gas mass flow MF, (e.g.

T <25O degrees C and MF> 1000kg / h). The working pressure Pr can in this case be kept at a reference level (eg 9 bar) in order to achieve a droplet size distribution which contains both large and small droplets of the fuel. This means that some droplets can be drawn into the exhaust gas flow while other droplets can be controlled through the flow. In this case, a large impact surface is provided in the exhaust system of the vehicle in order to make the best use of the heat energy available therein and to avoid local cooling.

Example 4. This determines a change from a reference state to a state with lower exhaust gas temperature T and lower exhaust gas mass flow MF, (e.g.

T <25O degrees C and MF <1000kg / h). The working pressure Pr can then be raised to produce small droplets which can evaporate more quickly on the surfaces in the exhaust system which are hit or may possibly have time to evaporate in the exhaust gas flow.

In this case, a rapid evaporation is achieved in the exhaust gas and / or on surfaces in the exhaust system as this operating case has the lowest heat energy available for evaporation of said fuel.

In a case of transient operation, the procedure can be supplemented so that control is based on a previous operating case. According to one example, the exhaust system of the vehicle after a long period of operation with relatively high exhaust temperature T and a relatively high exhaust flow may still be hot even though a prevailing exhaust mass flow and a prevailing exhaust temperature are currently low. 10 15 20 25 30 20 In this case, a corresponding previously prevailing working pressure can advantageously continue to be used for a suitable period of time.

According to one aspect of the invention, the working pressure Pr can be controlled on the basis of a change of a detected exhaust back pressure of the vehicle. In the event of an increase in the exhaust back pressure of the vehicle, the working pressure can advantageously be increased in a suitable manner in order to maintain a desired spray image with respect to metered fuel.

According to one aspect of the invention, the working pressure Pr can be controlled on the basis of a prevailing temperature of ambient air of the vehicle.

In a condition where the ambient air temperature is lower than 0 degrees C, the working pressure can be increased in a suitable manner, e.g. with 2 bar, to change the droplet size distribution towards smaller droplets which can facilitate the evaporation of dosed fuel.

According to one aspect of the invention, the working pressure Pr can be controlled on the basis of a prevailing temperature of the fuel of the HC dosing system of the vehicle.

In a state where the prevailing temperature of the fuel is higher than e.g. 50 degrees C, the working pressure can be lowered in a suitable way, e.g. with 2 bar, to compensate for a faster evaporation rate that the hot fuel brings.

Figure 3a schematically illustrates a flow chart of a method of HC dosing system of a motor vehicle, comprising a feeding device for feeding fuel from a container to a dosing unit for supplying said fuel to an exhaust duct of the vehicle, according to an embodiment of the invention. The method comprises a first method step s301. Step s301 includes the step of controlling the dosing of the dosing unit by means of a pressure below which fuel is dosed. After step s301, the process is terminated. Figure 3b schematically illustrates a flow chart of a method of HC dosing system of a motor vehicle, comprising a feeding device for feeding fuel from a container to a dosing unit for supplying said fuel to an exhaust duct of the vehicle, according to an embodiment of the invention.

The method comprises a first method step S310. Process step S310 includes the step of determining an prevailing temperature T of exhaust gases from the vehicle 100 engine. This can be done by means of the temperature sensor 240. After the process step S310, a subsequent process step S320 is performed. to determine a prevailing exhaust gas mass flow MF of said exhaust gases. The exhaust gas mass flow MF can be calculated according to the process step S320 including step one example with the first control unit 200. Alternatively, the exhaust gas mass flow MF can be detected by means of a suitable sensor or equipment. After the process step S320, a subsequent process step S330 is performed.

Method step S330 includes the step of controlling the dosing of the dosing unit 250 by means of a pressure Pr below which fuel is dosed. The pressure Pr can be changed by influencing a speed of the pump 230. The pressure Pr can alternatively or in combination be changed by influencing a throttle in the line 273. The pressure Pr can alternatively or in combination be changed by changing the configuration of the dosing unit 250 dosing device.

According to a preferred embodiment, the dosing of the dosing unit 250 is controlled by means of the pressure Pr on the basis of said determined prevailing temperature T of the exhaust gas flow and / or on the basis of said determined prevailing exhaust gas mass flow MF.

After the process step S330, a subsequent process step S340 is performed. The process step s340 comprises the step of controlling the dosing of the dosing unit 250 by means of a cycle frequency of the HC dosing system. According to one embodiment, said control of the dosing of the dosing unit 250 is performed by means of the pressure Pr under which fuel is dosed at the same time as said control of the dosing of the dosing unit 250 is performed by means of a cycle frequency of the HC dosing system.

According to one embodiment, the dosing of the dosing unit 250 is controlled by the pressure Pr of the fuel and by a cycle frequency CF of the dosing at the same time on the basis of said determined prevailing exhaust gas temperature T and / or said determined prevailing exhaust mass flow MF.

After the procedure step s340, 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 lock / 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 400. 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 controlling the dosing of the dosing unit 250 by means of a pressure Pr during which fuel is dosed. The program P includes routines for controlling the pressure Pr by controlling the RPM speed of the pump 230. The program P includes routines for controlling the pressure Pr by changing a throttle in the fuel line 273 from the metering unit 250 to the container 205. According to an alternative The program P includes routines for controlling the pressure Pr by changing a throttle flow in the dosing unit 250, which fuel flow is intended to lead to the container 205. The program P includes routines for controlling the pressure Pr by changing the configuration of the dosing unit 250 dosing device. The program P comprises routines for controlling the dosing of the dosing unit 250 by means of the pressure Pr on the basis of a prevailing temperature T of an exhaust gas flow from an engine and / or a prevailing mass flow MF of exhaust gases from an engine. The program P includes routines for controlling the dosage of the dosing unit 250 by means of the pressure Pr of the fuel and a cycle frequency CF of the dosing. The program P includes routines for varying the pressure Pr of the fuel within a range of [5, 15] Bar. The program P comprises routines for varying the pressure Pr of the fuel steplessly in said control of the dosing unit 250 dosing. The program P comprises routines for varying the pressure Pr of fuel in discrete steps in said control of the dosing unit 250 dosage. The program P comprises routines for changing a cycle frequency CF of the dosing steplessly or in discrete steps in said control of the dosing unit 250 dosing. The program P comprises routines for controlling the dosing of the dosing unit 250 by means of the pressure Pr of the fuel and a cycle frequency CF of the dosing on the basis of a prevailing exhaust gas temperature T and / or a prevailing exhaust mass flow MF of exhaust gases from an engine of the motor vehicle.

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 412. data bus 411. the data processing unit 410 via a data bus 414. To the data port 499, e.g. links 201, 221, 231, 241 and 251 are connected (see Figure 2).

The read / write memory 450 is arranged to communicate with When data is received on the data port 499, it is temporarily stored in the second memory part 440. When the data processing unit 410 is prepared to perform execution of code on the received input data is temporarily stored, a mode as described above. According to one embodiment, signals received at the data port 499 include information about a prevailing operating pressure Pr of the fuel in the HC dosing system. According to one embodiment, signals received at the data port 499 include information about a prevailing temperature T of the exhaust gases in an exhaust system of the vehicle. According to one embodiment, signals received at the data port 499 include information about a prevailing exhaust mass flow MF of the exhaust gases in an exhaust system of the vehicle.

The received signals on the data port 499 can be used by the device 400 to perform the innovative method herein.

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 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 (26)

10 15 20 25 30 26 PATENT REQUIREMENTS A method of HC metering system of a motor vehicle (100; 110), comprising a feeding device (230) for supplying fuel from a container (205) to a metering unit (250) for supplying said fuel to an exhaust duct of the vehicle (100). ; 110), characterized by the step of: - controlling the dosing of the dosing unit (250) by means of a pressure (Pr) under which fuel is dosed. The method of claim 1, further comprising the step of: - controlling the pressure (Pr) by controlling a speed (RPM) of said feeding device (230). The method of claim 1 or 2, further comprising the step of: - controlling the pressure (Pr) by changing a throttle in a fuel return line (273) from the dosing unit (250) to said container (205). A method according to any one of the preceding claims, further comprising the step of: - controlling the pressure (Pr) by changing the configuration of the dosing unit (250). A method according to any one of the preceding claims, further comprising the step of: - controlling the dosing of the dosing unit (250) by means of the pressure (Pr) on the basis of a prevailing temperature (T) of an exhaust gas flow from an engine and / or a prevailing mass flow (MF) in exhaust gases from an engine. A method according to any one of the preceding claims, further comprising the step of: - controlling the dosing of the dosing unit (250) by means of the pressure (Pr) and a cycle frequency (CF) of the dosing. A method according to any one of the preceding claims, further comprising the step of: - varying the pressure (Pr) of the fuel within a range of [5, 15] Bar. 10 15 20 25 30 27 A method according to any one of the preceding claims, further comprising the step of: - varying the pressure (Pr) of the fuel steplessly in said control of the dosage of the dosing unit (250). A method according to any one of claims 1-7, further comprising the step of: - varying the pressure (Pr) of the fuel in discrete steps in said control of the dosage of the dosing unit (250). A method according to any one of claims 6-9, further comprising the step of: - changing a cycle frequency (CF) of the dosage steplessly or in discrete steps in said control of the dosage of the dosing unit (250). A method according to any one of the preceding claims, further comprising the step of: - controlling the dosing of the dosing unit (250) by means of the pressure (Pr) and a cycle frequency (CF) of the dosing on the basis of a prevailing exhaust gas temperature (T) and / or a prevailing exhaust mass flow ( MF) of exhaust gases from an engine of the motor vehicle (100; 110). An HC dosing system of a motor vehicle (100; 110), comprising a feeding device (230) for supplying fuel from a container (205) to a dosing unit (250) for supplying said fuel to an exhaust duct of the vehicle (100; 110). ), characterized by: - means (200; 210; 400) for controlling the dosing of the dosing unit (250) by means of a pressure (Pr) below which fuel is dosed. The HC dosing system of claim 12, further comprising: - means (200; 210; 400) for controlling the pressure (Pr) by controlling a speed (RPM) of said feeding device (230). 10 15 20 25 30 28 The HC dosing system of claim 12 or 13, further comprising: - means (200; 210; 400) for controlling the pressure (Pr) by changing a throttle in a fuel return line (273) from the dosing unit (250) to said container (205). An HC dosing system according to any one of claims 12 to 14, further comprising: - means (200; 210; 400) for controlling the pressure (Pr) by changing the configuration of the dosing unit (250). An HC dosing system according to any one of claims 12 to 15, further comprising: - means (200; 210; 400) for controlling the dosing of the dosing unit (250) by means of the pressure (Pr) on the basis of a prevailing temperature (T) of an exhaust gas flow from an engine and / or a prevailing mass flow (MF) of exhaust gases from an engine. HC dosing system according to any one of claims 12-16, further comprising: - means (200; 210; 400) for controlling the dosing of the dosing unit (250) by means of the pressure (Pr) and a cycle frequency (CF) of the dosing. HC dosing system according to any one of claims 12-17, further comprising: - means (200; 210; 400) for varying the pressure (Pr) of the fuel within a range of [5, 15] Bar. HC dosing system according to any one of claims 12-18, further comprising: - means (200; 210; 400) for varying the pressure (Pr) of the fuel steplessly in said control of the dosing unit (250) dosing. HC dosing system according to any one of claims 12-18, further comprising: - means (200: 210; 400) for varying the pressure (Pr) of the fuel in discrete steps in said control of the dosing unit (250) dosing. The HC dosing system according to any one of claims 17 to 20, further comprising: means (200; 210; 400) for changing a cycle frequency (CF) of the dosing steplessly or in discrete steps in said control of dosage unit (250) dose fi ng. The HC dosing system according to any one of claims 12 to 21, further comprising: - means (200; 210; 400) for controlling the dosing of the dosing unit (250) by the pressure (Pr) and a cycle frequency (CF) of the dosing on the basis of a prevailing exhaust gas temperature (T) and / or a prevailing exhaust mass flow (MF) of exhaust gases from an engine of the motor vehicle (100; 110). Motor vehicle (100; 110) comprising an HC dosing system according to any one of claims 12-22. A motor vehicle (100; 110) according to claim 23, wherein the motor vehicle is something of a truck, bus or passenger car. A computer program (P) in an HC dosing system, comprising a feeding device (230) for supplying fuel from a container (205) to a dosing unit (250) for supplying said fuel to an exhaust duct of the vehicle (100; 110), wherein said computer program (P) comprises program code 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 according to any one of claims 1-11. A computer program product comprising a program code stored on a computer readable medium for performing the method steps of any of claims 1-11, 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).