SE537641C2 - Process of an HC dosing system and an HC dosing system - Google Patents

Abstract

SUMMARY The invention relates to a method of an HC dosing system comprising a dosing unit (250) for dosing fuel into an engine exhaust duct (290) upstream of a particulate filter (270) for purifying exhaust gases from said engine, wherein said HC dosing systems include pressurizing means (230) for supplying fuel from a container (205) to said dosing unit (250) arranged to dose said fuel under pressure to said exhaust duct (290). The method comprises the step of: - during periods of non-continuous dosing of fuel, during continued maintenance operation of said pressurizing means (230), lowering the pressure (s301; s320) of said branch at said dosing unit (250) with the pressure at continuous dosing. 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 1 also relates to an HC dosing system and a motor vehicle which is equipped with said HC dosing system.

Description

TECHNICAL FIELD The present invention relates to a process for an HC dosing system (Hydro Carbon, carbonate) comprising a dosing unit for dosing fuel into an engine exhaust duct. 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 an HC dosing system and a motor vehicle equipped with the HC dosing system.

BACKGROUND In today's vehicles, e.g. diesel as a fuel in DPF (Diesel Particulate Filter) systems including a particulate filter. The particle filter is arranged to capture e.g. diesel particles and soot. During active regeneration of the particle filter, diesel is fed 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 provides a homing of the temperature of the exhaust system. In this way, active regeneration of the particle 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 pump up 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 container can be the vehicle's fuel tank or a separate container with the DPF 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 dosage amounts, the system also consists of a return hose which is arranged from a pressure side of the system back to the container. The dosing can, for example, take place at a predetermined rate, such as between 1 Hz, where the dosing unit is open for a certain predetermined period of each rate, whereby fueled industry can be dosed. 1 There is a constant need to reduce the amount of emissions from engines of motor vehicles. This applies not least to heavy motor vehicles such as e.g. trucks and buses because legal requirements p5 alit minor emissions continuously skArps. It is therefore of the utmost importance that the HC dosing system of vehicles performs a satisfactory function so that performance is not reduced.

In many operating cases of the vehicle, no fuel is metered into the exhaust system, as active regeneration is not required as often. Such an operating case is when regeneration of the particle filter is not required, since the particle filter is not considered to have a sufficiently high degree of storage. Another such operational case can e.g. be dA the vehicle's exhaust temperature is lower At a certain predetermined temperature. Another such operating case where no dosing takes place may be when a prevailing temperature of a surface of or component of the exhaust duct from the vehicle's engine is lower than a certain predetermined temperature. In this case, the dosed industry cannot be evaporated to any great extent. Leakage of fuel can have a negative effect on a finishing system of a vehicle. It should be noted that a finishing system in, for example, heavy vehicles of today accounts for a significant part of the total value of the vehicle.

The dosing unit is thus kept closed in many operating cases so that dosing of fuel is simply not undesirable.

As the branch of the HC dosing system is pressurized, there may for various reasons be unintentional leakage of fuel from the dosing unit to the exhaust duct, Even during periods when the dosing unit is closed for not dosing the branch. In the event of adverse conditions, this leakage can cause undesired transient temperature rises in exhaust gases from said engine, which can adversely affect the HC dosing system. This can also have a negative effect on an SCR system of the vehicle.

A problem associated with industry leakage of the dosing unit when dosing should not take place is that this industry is sometimes not evaporated or burned in a correct manner, this industry can be stored in catalysts arranged downstream of a dosing stall of a 2 exhaust duct from an engine. This can adversely affect said catalysts or lead to undesired combustion at the wrong location of the exhaust duct. Unwanted leakage of fuel at the dosing unit can adversely affect a finishing system, including in thermal terms.

It is thus unreasonable to state that no or minimal leakage of fuel occurs when the dosing unit is closed.

SUMMARY OF THE INVENTION An object of the present invention is to provide a new and advantageous procedure in an HC dosing system which prevents the leakage of fuel when a dosing unit of the HC dosing system is closed.

Another object of the invention is to provide a new and advantageous HC dosing system and a new and advantageous computer program with an HC dosing system.

A further object of the invention is to provide a method, an HC dosing system and a computer program in an HC dosing system for achieving improved performance of a motor vehicle.

A further object of the invention is to provide a method, an HC dosing system and a computer program in an HC dosing system for reducing the risk of undesired temperature rises of exhaust gases of an exhaust duct from an engine.

A further object of the invention is to provide a method, an HC dosing system and a computer program in an HC dosing system for reducing the risk of fuel leakage Iran a dosing unit for dosing fuel to an exhaust duct to conduct exhaust gases from an engine.

These objects are achieved by a method of an HC dosing system according to claim 1. According to one aspect of the present invention there is provided a method of an HC dosing system comprising a dosing unit for dosing fuel into an engine exhaust duct upstream of a particulate filter for purifying exhaust gases from said engine. , wherein said HC dosing system includes pressurizing means (230) for supplying fuel from a container to said dosing unit arranged to dose pressurize said fuel to said exhaust duct. The method comprises the step of: - during periods of non-continuous dosing of fuel, during continued maintenance of said pressurizing means, lowering the pressure of said branch at the dosing unit compared with the pressure at continuous dosing.

According to one aspect of the present invention there is provided a method of an HC metering system for purifying exhaust gases from an engine wherein said HC metering system includes pressurizing means for supplying fuel from a container to a metering unit arranged to pressurize metering said fuel into an exhaust duct, the method comprising: the step of during periods of non-continuous dosing of fuel, during operation of said pressurizing means, lowering the pressure of said fuel at the dosing unit compared with the pressure at continuous dosing.

According to an aspect of the invention, the pressurizing means can supply fuel from a container to said dosing unit and thereby pressurize said fuel to a suitable pressure, for example a pressure between 5 and 15 Bar, for example 9 Bar, when dosing said fuel to said exhaust duct. During periods of non-continuous dosing of the industry, the pressure in the industry can be reduced from a higher pressure level (where dosing takes place continuously) to a lower pressure level, for example a pressure level between 1 and 6 Bar, such as 2 Bar or 5 Bar. According to one example, the pressure in the industry can be reduced from a pressure level of, for example, 50 Bar, when dosing takes place, to a pressure level of, for example, 5 Bar, where continuous dosing does not take place.

By lowering the pressure of the fuel at the dosing unit, the risk of leakage of the fuel during periods of non-dosing of said fuel is reduced. A leakage of fuel can adversely affect the function of the HC dosing system, which can mean that undesirable exhaust gases are emitted from a finishing system of the vehicle. Leakage of fuel in the dosing unit can cause a trafficking surface of the exhaust duct to be adversely affected, which can adversely affect the function of the HC dosing system. Since the pressurizing means, even during non-dosing arida, is in operation, it is faster to work up the pressure again to a level when dosing of the fuel takes place in comparison with the procedure where the pressurizing means is switched off completely. At the same time, advantageous cooling of the dosing unit can be maintained by means of a fuel flowing around it.

A period of non-continuous dosing of fuel can be a certain pre-determined time that is installable. An example of a time interval within which said installable predetermined time is may be between 1 s and 60 s, but other predetermined time periods are also possible.

A period of non-continuous dosing of fuel may involve a certain number of beats when dosing does not take place.

According to one aspect of the invention, the pressure of the industry at the dosing unit may be reduced from a first higher pressure level to a lower second pressure level after a predetermined period of non-dosing and then back to said first higher pressure level, or other appropriate higher pressure level, after a predetermined period of dosing.

According to an exemplary embodiment, a pressure of said fuel at the dosing unit can be increased from said lower pressure level to said higher pressure level at a fixed dosing cup. In this case, dosing of the fuel can be resumed (started) when the said pressure at the fuel reaches the said higher pressure level.

According to one aspect of the invention, the pressure of the industry at the metering unit can be collected at a certain predetermined pressure drop rate.

According to one aspect of the invention, a period of non-continuous dosing may occur depending on the operating condition of the engine. An operating case where continuous dosing does not take place can be when the exhaust gases from the engine have a temperature that is below a certain predetermined temperature. Another operating case where continuous dosing does not occur may be when the engine is idling. There are also other operational cases as continuous dosing of fuel does not take place. In a number of operating cases 6 continuous dosing does not take place, the inventive method can be used.

Dosing of fuel by means of the dosing unit takes place before the particle filter is to be regenerated.

According to another aspect of the present invention, the pressure of the industry can be reduced during periods of non-continuous dosing only if certain criteria are met. These criteria can be, for example, one or more of the following: the temperature 6 the exhaust gases are below a certain predetermined value; and / or leakage of the industry of the dosing unit has been detected.

Said varnish can be fixed 6 light set. According to this aspect and only in cases where one or ten of the above criteria are met, the pressure of sanctions is met during periods of non-dosing of industry.

Maintaining all operation of said pressurizing means meant that the pressurizing means is in operation, i.e. it does not close ay.

The pressurizing means may, for example, comprise a pump, such as a diaphragm pump.

The method may comprise the step of: lowering the pressure of said fuel at the metering unit by reducing a speed of said pressurizing means. In this case an effective set is achieved to lower said pressure 6 suitably. Said pressurizing means can then be controlled to other said pressures relatively quickly.

According to one aspect of the invention, the pressurizing means is a pump for which the speed can be adjusted to reduce its effect and thereby reduce the pressure of the industry at said dosing unit. The method may comprise the step of: - lowering the pressure of said fuel at the dosing unit by reducing a stroke frequency of said pressurizing means. In doing so, an effective way of collecting said pressure is achieved. Said pressurizing means can then be controlled to other said pressures relatively quickly.

According to one aspect of the invention, the pressurizing means is a pump for which the stroke frequency can be adjusted to reduce the effect and thereby reduce the pressure of the industry at the dosing unit.

The method may comprise the step of: - lowering the pressure of said branch at the dosing unit by controlling a valve configuration of a downstream side of the dosing unit. In doing so, an effective way of collecting said pressure is achieved. Said pressurizing means can then be controlled to other said pressures relatively quickly. By increasing the flow of fuel in the valve configuration, the pressure of the fuel at the dosing unit can be reduced in an efficient manner.

According to one aspect of the invention, the pressure of the industry at the dosing unit is lowered by fully opening said valve configuration located downstream of the dosing unit. At normal pressure, such as during continuous dosing of fuel, the valve configuration may be closed or only open to a certain extent. With a pressure drop of the fuel, as with non-continuous dosing of fuel, the valve configuration can be opened more and the fuel can pass more easily through the valve configuration, which means that the pressure of the fuel at the dosing unit decreases.

For pressurizing means with a controllable displacement, said control of a pressure of the branch at the dosing unit can be achieved during the maintained speed. That is, according to one embodiment, said pressure changes can be effected without changing a speed of said pressurizing means. The method may comprise the step of: lowering the pressure of said fuel at the dosing unit by passing said fuel from said pressurizing means to said container past said dosing unit.

According to one aspect, when the pressure is to be collected, the fuel can be led past the dosing unit, from the pressurizing means to the container. A valve configuration consisting of one or more valves can, for example, control the flow of fuel, either to the dosing unit or past the dosing unit. Said first control unit may be arranged to control said valve configuration in accordance with the present invention.

The method may comprise the step of: lowering the pressure of said fuel at the dosing unit by controlling a feeding means arranged downstream of the dosing unit.

By placing a supply means downstream of the dosing unit, the pressure of the branch can be reduced by the supply means collecting the pressure downstream of the dosing unit.

The supply means may, for example, be a pump such as a diaphragm pump or another type of pump.

The method may comprise the step of substantially lowering the pressure of said fuel at the dosing unit.

The pressure can, for example, be reduced from a level of p5 9 Bar to a level of p5 2 Bar. Alternatively, the pressure can be reduced from a level of 9 Bar to a level of 5 Bar. Lowering the pressure significantly can mean that the pressure drops by at least 20% relative to the pressure of the reducing agent during continuous dosing. Lowering the pressure significantly can mean that the pressure drops by at least 40% relative to the pressure in the industry during continuous dosing. Lowering the pressure of the said branch at the dosing unit can significantly mean lowering the pressure by more than 80% relative to the pressure of the branch during continuous dosing.

The process may involve a stepless lowering of the pressure. This stepless lowering of the pressure of the industry can be accomplished with any of the components which lower the pressure such as: the pressure setting means; a valve configuration downstream of the dosing unit; At least one valve configuration that directs fuel past the dosing unit.

The stepless collection can take place at varying speeds. The speed can vary depending on different parameters such as engine type, etc., and it can also vary during an ongoing reduction of the pressure of the industry.

The process may involve a reduction in the pressure of the industry in steps.

This lowering of the pressure of the industry in steps can be accomplished with any of the components which can effect a lowering of the pressure such as: the pressurizing means; a valve configuration downstream of the dosing unit; At least one valve configuration that directs fuel past the dosing unit.

The pressure in the industry can be reduced in any number of steps.

The method may comprise the step of: in the case of resumption of continuous dosing, raising the pressure of said industry at the dosing unit.

The method may comprise the step of: raising the pressure of said brat-Isle at the dosing unit before continuous dosing is resumed or started.

The method may comprise the step of: raising the pressure of said industry at the dosing unit before continuous dosing is resumed or started on the basis of a fixed dosing request.

After a period of non-dosing of the industry, the industry can be dosed again. Then the pressure of the branch at the dosing unit is raised again to a suitable pressure level which is set for dosing the branch. The procedure may comprise the step of: - at a predetermined time before a fixed time when continuous dosing of fuel is to cease, start pressure reduction of said industry at the dosing unit.

In order for the pressure in the industry to be at a legal level when the dosing unit is closed, the pressure drop can, according to an exemplary embodiment, be started for a predetermined time before a fixed time cla dosing of the industry should cease.

The procedure is easy to implement in existing motor vehicles. Program code for controlling a pressure drop of a fuel at a dosing unit in an HC dosing system to prevent leakage of fuel when the dosing unit is closed, according to an aspect of the invention, can be installed in a control unit of the vehicle during manufacture thereof. A buyer of the vehicle may thus have the option of choosing the function of the procedure as an option. Alternatively, program code for performing the innovative procedure can be installed in a control unit of the vehicle when upgrading at a service station. In this case, the program mode can be loaded into a memory in the control unit.

Program code for pressure reduction of a fuel at a dosing unit in a HC dosing system to prevent leakage of fuel when the dosing unit is closed can be easily updated or replaced. Furthermore, different parts of the program code can be exchanged independently of each other. This modular configuration is advantageous from an underpass perspective.

According to one aspect of the present invention, there is provided an HC dosing system arranged to dose fuel into an engine exhaust duct upstream of a particulate filter for purifying exhaust gases from said engine, said HC dosing system comprising: a dosing unit adapted to dose said fuel to said fuel under pressure. exhaust duct; a pressurizing means adapted to supply fuel from a container to said dosing unit; means adapted to, during periods of non-continuous dosing of fuel, during continued upright operation of said pressurizing means, lower the pressure of said fuel at the dosing unit compared with the pressure at continuous dosing.

According to one aspect of the invention, there is provided an HC dosing system wherein said pressurizing means comprises a pump with controllable speed. According to one aspect of the invention, there is provided an HC dosing system wherein said pressurizing means comprises a pump with controllable stroke frequency. The device may comprise a valve configuration arranged at a downstream side of the dosing unit. The device may comprise means for substantially lowering the pressure of said fuel. The device may comprise means for lowering the pressure of said fuel step. The device may comprise means for lowering the pressure of said fuel in steps. The device may comprise means for directing said fuel from said pressurizing means to said container past said dosing unit. The device may comprise a feeding means arranged downstream of the dosing unit. The HC dosing system may include a DPF. The HC dosing system may be included in a DPF system. The HC dosing system may comprise a DOC unit arranged upstream of said particulate filter of said exhaust duct from said engine. The fuel can be diesel or other carbonate-based fuel.

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

According to one aspect of the invention, there is provided a computer program for pressurizing a fuel at a metering unit in an HC metering system to prevent leakage of fuel when the metering unit is closed, said computer program comprising program code for causing an electronic controller or other computer connected thereto. 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 for pressure sinking a fuel at a metering unit in an HC metering system to prevent leakage of the fuel metering unit is closed, said computer program comprising program code stored on a computer readable medium to cause a 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 in an HC dosing system, said computer program comprising program code for causing an electronic controller or another computer connected to the electronic controller to perform the steps of any of claims 1-11.

According to one aspect of the invention, there is provided a computer program in an HC dosing system, said computer program comprising program code stored on a computer readable medium for causing an electronic controller or another computer connected to the electronic controller to perform the steps of any 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 of any of claims 1-11, when said program code is crossed 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 the practice of the invention. While the invention is described below, it should be understood that the invention is not limited to the specific details described. Those skilled in the art having access to the teachings will again appreciate further applications, modifications and incorporations within other fields 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, we will now refer 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 2a schematically illustrates an HC dosing system, according to an embodiment of the invention; Figure 2b schematically illustrates a dosing unit of the HC dosing system; Figure 3a schematically illustrates a flow chart of a process, according to an embodiment of the invention; Figure 3b schematically illustrates in further detail a flow chart of a method, according to an aspect of the invention; Figure 4a schematically illustrates a diagram, according to an aspect of the invention; Figure 4b schematically illustrates a diagram, according to an aspect of the invention; Figure 4c schematically illustrates a diagram, according to an aspect of the invention; Figure 4d schematically illustrates a diagram, according to an aspect 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 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. The vehicle may alternatively be a truck, dumper or crane, or other suitable platform including an engine and a HC dosing system.

It was pointed out that the invention is suitable for application to any suitable HC dosing system comprising a fuel dosing unit and a particulate filter and is not limited to the HC dosing system of motor vehicles. The innovative process for an HC dosing system and the innovative HC dosing system according to an aspect of the invention are suitable for other platforms which include an HC dosing system for motor vehicles, such as e.g. watercraft. The watercraft can be of any suitable type, such as e.g. motorboats, ships, ferries or ships.

The innovative process and the innovative HC dosing system according to an aspect of the invention are also suitable for e.g. systems including, for example, a stone crusher or the like. The innovative method and the innovative HC dosing system according to an aspect of the invention are also suitable for e.g. systems including industrial engines and / or motorized industrial robots.

The innovative process and the innovative HC dosing system according to an aspect of the invention also make choices for different types of power plants, such as e.g. an electric power plant comprising a diesel generator.

The innovative process and the innovative HC dosing system make choices for an arbitrarily suitable engine system that includes an engine and an HC dosing system with a dosing unit and a particulate filter, such as e.g. at a locomotive or other platform.

The innovative procedure and the innovative HC dosing system are suitable for an arbitrary lamp dosing system that includes a NOR generator and an HC dosing system with a dosing unit and a particulate filter.

The method according to the invention is suitable for a suitable system which generates exhaust gases with particles and a filter which stores particles, which particles can be combusted during a regeneration of said filters, in particular during an active regeneration of said filters.

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

The invention is applicable to industry dosing systems which are arranged to HO a temperature of the exhaust gases from the engine for other reasons than to regenerate said particle filter.

The fuel of the HC dosing system can be a suitable industry, such as e.g. oil, Asom e.g. lubricating oil, diesel or other hydrocarbon-based industries, such as e.g. petrol, ethanol or methane, etc. 14 The term "lank" 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 link. or microwave Slim.

In this he refers to the term "conduit" to a passage for holding and transporting a fluid, such as e.g. a branch in liquid form. The pipe can be a rudder of any dimension. The wire can consist of an arbitrary, suitable material, such as e.g. plastic, rubber or metal.

The term "fuel" refers to an agent used for the active regeneration of a particulate filter in an HC dosing system. The said industry is according to a performing diesel. Of course, other types of carbonate based industries can be used. Hari states diesel as an example IDA a industry but a professional realizes that the innovative procedure and the innovative device can be realized for other types of industry, with the necessary adaptations, such as e.g. adjustments to adequate boiling temperature for selected industries, in control algorithms to execute program code in accordance with the innovative procedure.

Although the term HC dosing system is used herein to indicate a particulate filter system, the invention is not limited to the use of a diesel particulate filter. On the contrary, other types of particle filters can be used according to the invention. One skilled in the art will recognize what kind of industry the bast lamps are for regenerating the selected particulate filter.

Referring to Figure 2a, there is shown an HC dosing system 299 of the vehicle 100. The HC dosing system 299 may be located in the tractor 110. According to this example, the HC dosing system 299 includes a container 205 arranged to have a branch. The container 205 is arranged to contain a suitable amount of fuel and is further arranged to be able to be filled if necessary.

A first line 271 is provided to direct the fuel to a pump 230 Irk container 205.

The pump 230 may also be referred to as the pressurizing means. The pump 230 can be a 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 230 may be arranged to pump up 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 may comprise an electrically controlled dosing device, by means of which a flow of fuel added to the exhaust system can 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 can also be called a throttling valve, against which said pressure of the fuel can be built up in the device 299. The throttling unit is further described with reference to Figure 2b.

The dosing unit 250 is arranged to supply said fuel to an exhaust duct 290 of the vehicle 100. More specifically, the dosing unit 250 is arranged to supply in a controlled manner a suitable amount of fuel to an exhaust duct 290 of the vehicle 100. According to this embodiment, a diesel particulate filter (DPF) 270 arranged downstream of a layer of the exhaust system where the supply of fuel takes place. Said diesel particulate filter can also be called a DPF unit. The amount of fuel supplied to the exhaust system is intended to be combusted in an oxidation catalyst 269, which is arranged upstream of said diesel particulate filter 270 of the exhaust duct 290.

The dosing unit 250 may be arranged at said exhaust duct 290 which is arranged to direct exhaust gases from an internal combustion engine (not shown) of the vehicle 100 to said and further to said diesel particulate filter 270 and further to an environment of the vehicle.

According to one example, a precatalyst is mounted in series with the particulate filter 270. In this case, said precatalyst is arranged upstream of said particulate filter 270.

A third conduit 273 is provided disposed between the metering unit 250 and the container 205. The third conduit 273 is arranged to return non-metered fuel fed to the metering unit 250 to the container 205.

A fourth conduit 274 arranged to direct the fuel between the pump 230 and the sensor 20 past the dosing unit 250 may, according to one embodiment, be included in the HC dosing system. The first control unit 200 may be signal connected to a valve configuration (not shown) of the fourth line 274. The first control unit 200 may then be adapted to control the line of the fuel from the pump 230 or the second line 272 directly to the container 205 without the fuel passing dosing unit 205. In this case, the pressure at the dosing unit 250 can be reduced in an appropriate manner according to an aspect of the invention.

The first control unit 200 is arranged for communication with the pump 230 via a long L230. The first control unit 200 is arranged to control the operation of the pump 230. According to one example, the first control unit 200 is arranged to control the pump 230 by means of an electric motor (not shown). The first control unit 200 is arranged to control a pressure P of the branch in the second line 272. This can be done in various convenient ways. According to one example, the first control unit 200 is arranged to control a rotating speed RPM of the pump 230. In this case, the pressure of another 13'6 may be set four times. By equalizing the speed of the pump 230, the pressure P can be equalized. By lowering the speed of the pump 230, the pressure P can be reduced. According to another example, the first control unit 200 is arranged to second a stroke of the pump 230.

By equalizing the stroke of the pump 230, the pressure P can be increased. By reducing the stroke of the pump, the pressure P can be reduced. According to another example, the first control unit 200 is arranged to second a stroke frequency of the pump 230. By equalizing the stroke frequency of the pump 230, the pressure P can be equalized. By reducing the stroke frequency of the pump 230, the pressure P can be reduced.

A second pump 300 may, according to one embodiment, be included in the HC dosing system. Said second pump 300 may also be referred to as feed means or feed means. The first control unit 200 is arranged for communication with the pump 300 via a long L300. The first control unit 200 is arranged to control operation of the pump 300. According to one example, the first control unit 200 is arranged to control the pump 300 by means of an electric motor (not shown). By controlling the pump 300 to reduce a pressure of the branch of an upstream side of the pump 300, the pressure of the branch in the line 272 can be reduced.

The first control unit 200 is arranged for communication with the dosing unit 2 and said throttling unit, which may be included in the dosing unit 250. By controlling the throttling unit, the pressure in the line 272 can be controlled. By reducing the opening in the choke unit, the pressure P in the line 272 can be equalized and by enlarging the opening in the choke unit, the pressure P in the line 272 can be reduced.

The first control unit 200 is arranged that during periods of non-continuous dosing of fuel, during continued upright operation of said pressurizing means 230, the pressure of said branch at said dosing unit 250 compares with the pressure at continuous dosing. The first control unit 200 is arranged to lower the pressure of said branch at the dosing unit 250 by reducing the speed of said pressurizing means 230. The first control unit 200 is arranged to lower the pressure of said branch at said dosing unit 250 by reducing a stroke frequency of said pressurizing means 230. the first control unit 200 is arranged to lower the pressure of said branch at the dosing unit 250 by controlling a valve configuration (not shown) of a downstream side of the dosing unit 250.

The first control unit 200 is arranged to lower the pressure of said fuel at the dosing unit 250 by guiding said branch of said fuel from said pressurizing means 230 to said container 205 past said dosing unit 250. The fuel is led past said dosing unit via line 274.

The first control unit 200 is arranged to lower the pressure of said branch at the dosing unit 250 by controlling feed means 300 arranged downstream of the dosing unit 250. The first control unit 200 is arranged to lower the pressure of said branch at the dosing unit substantially. The first control unit 200 is arranged to lower the pressure of said industry steplessly. The first control unit 200 is arranged to lower the pressure of said industry in steps. The first control unit 200 may be arranged to increase the pressure of said branch at the dosing unit 250 during resumed continuous dosing at the dosing unit 250. The first control unit 200 may be arranged to raise the pressure to a suitable level of said branch at the dosing unit 250 before continuous dosing. The first control unit 200 may be arranged to raise the pressure to an appropriate level of said fuel at the dosing unit 250 before continuous dosing is started on the basis of a dosing request. Said request can be determined by a suitable system of, for example, the vehicle 100. The first control unit 200 is arranged that at a predetermined time before a fixed time cla continuous dosing of fuel should cease, start pressure reduction of said branch at the dosing unit 250. 18 The first control unit 200 is arranged for communication with the dosing unit 250 via a long L250. The first control unit 200 is arranged to control the operation of the dosing unit 250 in order to e.g. regulate the supply of fuel to the exhaust system of the vehicle 100.

A second control unit 210 is arranged for communication with the first control unit 200 via a long L210. 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 may be arranged to perform the inventive method steps according to the invention. The second control unit 210 can be used to load Over program code to the first control unit 200, in particular program code to perform the inventive 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 e.g. that during non-continuous dosing of fuel of the HC dosing system, during continued maintenance of said pressurizing means, lower the pressure of said fuel at the dosing unit compared with the pressure at continuous dosing.

The first control unit 200 is arranged for communication with a first temperature sensor 240 via a long L240. The temperature sensor 240 is arranged to detect an ambient temperature Ti of an exhaust stream from the vehicle's engine. According to one example, the first temperature sensor 240 is arranged at said exhaust duct 290 directly downstream of the vehicle upstream dosing unit 250. The temperature sensor 240 may be provided at a suitable location of said exhaust duct 290. The first temperature sensor 2 is arranged to continuously detect an exhaust gas temperature and send signals containing information about the said temperature Tempi via the line L240 to the first control unit 200.

The first control unit 200 is arranged for communication with a second temperature sensor 260 via a long L260. The second temperature sensor 260 may be arranged to detect a radiating temperature Temp2 of a surface in the exhaust system where the fuel evaporates. The second temperature sensor 260 may be arranged to detect a radiating temperature Temp2 of the exhaust duct 290 in a suitable place. The second temperature sensor 260 may be arranged to detect a radiating temperature Temp2 of a suitable surface or component of the exhaust duct 290. According to one example, the second temperature sensor 260 is arranged at the exhaust duct 290 upstream of the dosing unit 250. According to one example, the second temperature sensor 260 is arranged in the exhaust duct. 290 upstream of the dosing unit 250. According to another example, the second temperature sensor 260 is arranged in an evaporator unit (not shown) or an SCR catalyst (not shown) downstream of the particle filter 270. The second temperature sensor 260 is arranged to continuously detect a radiating temperature Temp2 of a surface or a component of the exhaust duct 290 and send signals including information about said radiating temperature Temp2 via the line L260 to the first control unit 200.

According to one embodiment, there is a temperature sensor disposed between the oxidation catalyst 269 and the particulate filter 270. This temperature sensor is used here to enable temperature detection monitoring of the oxidation catalyst 269.

According to one embodiment, the first control unit 200 and / or the second control unit 2 are arranged to calculate said first temperature Tempt. This can be done by means of a stored calculation model. The first control unit 200 and / or the second control unit 210 may be arranged to calculate said first temperature Tempi on the basis of, for example, a radiating exhaust mass flow, radiating speed of the engine and radiating load of the engine.

According to one embodiment, the first control unit 200 and / or the second control unit 2 are arranged to calculate said second temperature Temp2. This can be done by means of a stored calculation model. The first control unit 200 and / or the second control unit 210 may be arranged to calculate said second temperature Temp2 on the basis of, for example, a radiating exhaust mass flow, radiating speed of the engine and radiating load of the engine.

A first NOx sensor 255 is provided for communication with the first control unit 200 via a long L255. The first NOx sensor 255 is arranged to continuously determine a radiating NOR content of the exhaust stream upstream of said SCR catalyst, for example upstream of said particle filter 270. According to an example, the first NOx sensor 255 is arranged at the exhaust duct 290 upstream of said dosing unit 250. The first NO 1 sensor 255 is arranged to continuously send signals including information about a radiating NOR content upstream of said SCR catalyst to the first control unit 200.

A second NO 1 sensor 265 is provided for communication with the first control unit 200 via a long L265. The second NO 1 sensor 265 is arranged to continuously determine a radiating NO 2 content of the exhaust gas stream downstream of said SCR catalyst. The second NOR sensor 265 is arranged to continuously send signals including information about a radiating NOR content downstream of said SCR catalyst to the first control unit 200.

According to one embodiment, the first control unit 200 and / or the second control unit 210 are arranged to calculate said first NOR content upstream of said SCR catalyst. This can be done by means of a stored calculation model. The first control unit 200 and / or the second control unit 210 may be arranged to calculate said first NON content on the basis of, for example, a radiating exhaust mass flow, radiating speed of the engine and radiating load of the engine.

The first control unit 200 is arranged to determine a radiating NO, conversion degree on the basis of said calculated or fed NON content upstream of said SCR catalyst and said fed NOR content downstream of said SCR catalyst.

The first control unit 200 is arranged to continuously control the operation of the HC dosing system 299 on the basis of said first temperature Temp and / or said second temperature Temp2.

The first control unit 200 is arranged for communication with a pressure sensor 279 via a long L279. The pressure sensor 279 is arranged to detect a radiating pressure P of the branch of the second line 272. According to an example, the pressure sensor 271 is arranged of said dosing unit 250 to detect a pressure P of the branch at the dosing unit 250.

The pressure sensor 271 may be provided in a suitable place to supply a pressure of the branch at the dosing unit 250. The pressure sensor 271 is arranged to continuously detect a radiating pressure P of the branch and send signals including information about said radiating pressure P via the line L271 to the first the control unit 200.

According to one embodiment, the first control unit 200 and / or the second control unit 2 are arranged to calculate said pressure P of the industry at said dosing unit 250. This can be done by means of a stored calculation model. The first control unit 200 and / or the second control unit 210 may be arranged to calculate said pressure P on the basis of, for example, a radiating speed of the pump 230 and / or installations of the valve configuration 288 and / or speeds of the pump 300 and / or installations of valve means of said fourth line 274.

The first control unit 200 is arranged to continuously determine a radiating degree of clogging of said particle filter 270. This can be done in an appropriate manner. The first control unit 200 is arranged to continuously control the operation of the HC dosing system 299 on the basis of said degree of clogging. In this case, it can be decided, for example, whether, and in that case when, an active regeneration of said particle filter 270 is to be initiated. The first control unit 200 is arranged to control a regeneration process of said particle filter 270, for example by continuous dosing of said fuel to achieve the required temperature rise of exhaust gases in said exhaust duct 290. These dosing can take place at a suitable pressure P, for example 9 Bar. In the case of non-dosing, said pressure P is controlled to a lower pressure, for example 2 Bar, according to an aspect of the present invention.

The first control unit 200 is arranged to control at least one SCR system of the vehicle on the basis of said NOR content upstream of said SCR catalyst and / or said NOR content downstream of said SCR catalyst.

The first control unit 200 is arranged to continuously control the operation of the HC dosing system 299 on the basis of said pressure P of the industry of the dosing unit 250.

Figure 2b schematically shows the dosing unit 250. The dosing unit 250 comprises a cradle 252 with a sate 253 and an elongate device 251. Said device 251 may be a pin or a 22 needle. Said device 251 is slidably arranged. Said device 251 is arranged to be displaced by means of lamp equipment, for example an electromagnetic equipment, in a reciprocating movement marked in Figure 2b in the form of a bidirectional arrow R. Said device 251 is displaceably arranged between two breaths. In a first breath, as shown in Figure 2b, one end of the device abuts substantially against a sate 253, the dosing unit 250 being closed and no dosing taking place. At a second abutment, one spirit of the device does not abut said sate 253, whereby the dosing unit 250 is open and dosing can take place.

Bransle is arranged to be led to the dosing unit 250 via the line 272 under pressure. When dosing the fuel, the device is moved in an upward direction, which means that the fuel can pass out through a passage 254 to the exhaust duct 290. In the case of continuous dosing, the device 251 can be retained for a predetermined period of time at a certain rate at said other water layers. into the exhaust duct 290 and for a certain period of time at a certain rate the device 251 can be retained in said first breath, and thereby abut against said sate 253, so that fuel is not dosed into the exhaust duct 290.

Although the device 251 is in said first abutment, abutting the set 253, a certain leakage of fuel can occur between the device 251 and the set 253, in particular under a relatively high pressure P of said branch at the dosing unit 250. The inventive method, where said pressure in said industry is reduced as dosing should not take place, this advantageously reduces said leakage.

Fuel is supplied to the dosing unit 250 via the passage 272. Fuel that is not dosed is fed from the dosing unit 250 to said container 205 via the line 273. A river direction for said non-dosed fuel is shown by arrows F in Figure 2b.

The first control unit 200 is arranged for communication with a valve configuration 288 via a long L288. Said first control unit 200 is arranged to control the valve configuration 288 and can thereby set an opening degree of said valve configuration 288. By controlling the valve configuration 288 to an at least partially open layer, the pressure P of said branch of the dosing unit 250 can be reduced, according to an aspect of the present invention. . By controlling the valve configuration 288 to an at least partially open layer, at the same time as said pressurizing means 230 controls a pressure drop of the branch, the pressure P of the branch of the dosing unit 250 can advantageously be lowered relatively quickly. According to one aspect of the present invention, thus, beneficial synergy effects can be achieved. It should be noted that the industry pressure of the metering unit 250 can be increased by directing the valve configuration toward a rod bearing.

Said dosing unit 250 can be designed according to alternative embodiments. Dosage control by means of said device 251 is only an exemplary embodiment. Other dosage configurations are realizable. According to one example, a displaceable plate, which thanks to said passage 254, may be provided for dosing fuel in a similar manner.

Figure 3a schematically illustrates a flow chart of a method of an HC dosing system comprising a dosing unit 250 for dosing fuel into an engine exhaust duct 290 upstream of a particulate filter 270 for purifying exhaust gas in said engine, said HC dosing system including pressurizing means 230 for feeding fuel. from a container 205 to said dosing unit 250 arranged to dose under pressure said fuel to said exhaust duct 290. The method comprises a first method step s301. The process step s301 comprises the step of: - during periods of non-continuous dosing of fuel, during continued sustained operation of said pressurizing means 230, lowering the pressure of said branch at the dosing unit compared with the pressure at continuous dosing.

After step s301, the procedure is terminated.

Figure 3b schematically illustrates a flow chart of a process in an HC dosing system comprising a dosing unit 250 for dosing fuel into an engine exhaust duct 290 upstream of a particulate filter 270 for purifying exhaust gases from said engine, said HC dosing system including pressurizing means 230 for feeding fuel from a container 205 to said dosing unit 250 arranged to dose said fuel under pressure to said exhaust duct 290, according to an aspect of the present invention. The method comprises a method step s305. The process step s305 comprises the step of continuously dosing fuel by means of said dosing unit 250 to said exhaust duct 209. Dosing can then take place at a pressure P1, for example 9 Bar. After the process step s305, a subsequent step s310 is performed.

The method step s310 may include the step of activating the inventive method. Named activation can take place automatically. Said activation can take place when the first control unit 200 determines that said continuous dosing of fuel must be interrupted. Said activation can alternatively take place when the first control unit 200 determines that said continuous dosing of fuel has been interrupted.

The process step s310 may include the step of determining a need to lower the pressure of the industry. Said need to lower the pressure of the industry can be determined by including one or more of the following steps: an operating condition of said engine is checked; time elapsed from the start of non-continuous dosing is recorded; a radiating exhaust temperature and or temperature of a suitable surface or component of said exhaust duct 290 is detected; - an exhaust gas flow is detected.

After the procedure step s310, a subsequent stirring step s320 is performed.

The process step s320 comprises the step of lowering the pressure P of the industry under predetermined operating conditions of said HC dosing system. Said lowering may include a lowering from a pressure P1 to a pressure P2, as described with reference to, for example, Figures 4a-4d. Said predetermined operating conditions may include that dosing of industry shall cease or have ceased. Said operating conditions can be determined on the basis of said steps as exemplified in process step s310, for example by comparison with criteria stored in the first control unit 200. Step s320 may include lowering said pressure by: reducing a radiating speed RPM of the pressurizing means 230; reducing a stroke frequency of the pressurizing means 230; or controlling a valve configuration 288 of a downstream side of the metering unit 250; and / or - directing fuel from the pressurizing means 230 to the container 205 past the dosing unit 250; and / or controlling an additional pressurizing means 300 arranged downstream of the dosing unit 250.

Method s320 may include the step of substantially lowering the pressure of the industry. Method s320 may include the step of lowering the pressure of the industry steplessly. Method s320 may alternatively include the step of lowering the pressure of the industry in steps.

After the procedure step s320, a subsequent procedure step s330 is performed.

The method step s330 may include the step of determining if a degree of storage of the particulate filter 270 is less than a predetermined value. If not, there may be a need to start fueling dosing again.

The process step s330 may include the step of determining the need to drive the pressure of the industry. During re-dosing of the fuel, the pressure of the fuel in line 272 at the dosing unit 250 Ater must be increased to obtain a correct dosing of fuel in the exhaust duct. Alternatively, said need can be determined on the basis of a request to start continuous dosing of fuel. After step s330, a subsequent step s340 is performed.

The process step s340 comprises, if the need is determined, starting dosing of fuel from the dosing unit 250 to the exhaust duct 290 and thereby again raising the pressure P in an appropriate manner, for example from a pressure P2 to a pressure P1. Alternatively, the pressure P can be increased in a suitable manner, for example from a pressure P2 to a pressure P1, after which dosing of fuel from the dosing unit 250 to the exhaust duct 290 is started. After the process step s340, the inventive process is completed. Referring to Figure 4a, a diagram is shown in which the pressure P of the industry at the dosing unit 250 is indicated as a function of time T. The pressure P can be supplied by said pressure sensor 279. Alternatively, the pressure P can be calculated by means of the first control unit 200 in a suitable manner. At a time TWO rod dosing of the branch ay. At a time T1, a pressure drop in the industry is initiated by the dosing unit from a first predetermined pressure level P1 to a second predetermined pressure level P2. The time Ti occurs yid a certain predetermined time period after TO. This time period can be an appropriate time period, for example 2 seconds. Figure 4a shows an example where the pressure drop takes place steplessly. At a certain time period after Ti, yid a time T2, the pressure P night has the second predetermined level P2. The predetermined time period between time T1 and time T2, and the armed pressure drop rate, may, for example, depend on various operating factors of the vehicle. The first pressure level P1 can, for example, be 9 Bar. The second pressure level P2 can be, for example, 2 Bar. The time period between the times T1 and T2 can be, for example, 5 seconds. When initiating the dosing of fuel by means of the dosing unit 250, the pressure P can be controlled to a suitable pressure level, for example to said first pressure level Pi, in a suitable manner, for example stepless.

According to an exemplary embodiment, said pressure P1, where applicable, can be collected directly to said pressure P2. According to an exemplary embodiment, said pressure P2 can be applied directly to said pressure P1 where applicable.

Referring to Figure 4b, a diagram is shown in which the pressure P of the branch at the dosing unit 250 is indicated as a function of time T. The pressure P can be supplied by said pressure sensor 279. Alternatively, the pressure P can be calculated by means of the first control unit 200 in a suitable manner. At a time TWO rod dosing of the branch ay. At a time T1, the pressure drop of the industry yid the dosing unit 250 is initiated from a first predetermined pressure level P1 to a second predetermined pressure level P2. The time Ti occurs yid a certain predetermined time period after TO. This time period can be an appropriate time period, for example 2 seconds. Figure 4b illustrates an embodiment where the pressure drop takes place in an appropriate number of steps, for example 5 steps. Said steps can be on board different sizes. Said steps can be on board the same size. At a certain time period after T1, at a time T2, the pressure P night has the second predetermined level P2. The predetermined time period between time Ti and time 12, as well as the steps in which the pressure drop takes place, may depend on different operating factors of the vehicle. The first pressure level P1 can, for example, be 9 Bar. The second pressure level P2 can be, for example, 2 Bar. The time period between the times T1 and T2 can be, for example, 5 seconds. A step can be, for example, 1 or 2 Bar. When initiating dosing of fuel by means of the dosing unit 250, the pressure P can be controlled to a suitable pressure level 5, for example to said first pressure level P1, p5 suitably set, for example stepless.

Referring to Figure 4c, a diagram is shown in which the pressure P of the branch at the dosing unit 250 is indicated as a function of the time T. The pressure P can be supplied by said pressure sensor 279. Alternatively, the pressure P can be calculated by the first control unit 200 in a suitable manner. At a time TWO rod dosing of brat-Islet ay. At a time Ti, a pressure drop in the industry at the dosing unit 250 is initiated from a first predetermined pressure level P1 to a predetermined pressure level PX. The time Ti occurs at a certain predetermined time period after TO. This time period can be an appropriate time period, for example 5 seconds. Figure 4c illustrates an embodiment where the pressure drop takes place in two steps. At a certain time period after Ti, a pressure drop is initiated when the pressure drops steplessly from said first predetermined pressure level P1 to said pressure level PX. The pressure P is said pressure level PX at a second time T2. Time 12 occurs at a certain predetermined time period after time Ti. This time period can be an appropriate time period, for example 2 seconds. The predetermined time period between the time T1 and the time T2, and thus the pressure drop speed, may, for example, depend on different operating factors of the vehicle. In doing so, said pressure level PX is maintained at a predetermined time T3. At said time T3 a second stepless pressure drop is initiated from said pressure level PX to a second pressure level P2. The pressure P reaches said second pressure level P2 at a fixed time T4. Time T4 Intl-Oar at a certain predetermined time period after time T3. This time period can be an appropriate time period, for example 3 seconds. The predetermined time period between time T3 and time T4, and thus the pressure drop speed, may, for example, depend on different operating factors of the vehicle. The first pressure level P1 can, for example, be Bar. The second pressure level P2 can be, for example, 2Bar. Pressure level PX can be, for example, Bar. When initiating dosing of fuel by means of the dosing unit 250, the pressure P 28 can be controlled to a suitable pressure level, for example to said first pressure level P1, in a suitable manner, for example stepless.

By first controlling the pressure P from said level P1 to said level PX, and thereby waiting for a certain period of time, it is advantageously possible to evaluate and choose whether a further pressure drop from level PX to said level P2 is to be carried out or not. In the event that a further pressure drop from the level PX is not required, at the start of dosing, a pressure increase to said level P1 can be achieved relatively quickly, compared with a pressure increase from the pressure level P2 to the pressure level P1.

Referring to Figure 4d, a diagram is shown in which the pressure P of the branch at the dosing unit 250 is indicated as a function of time T. The pressure P can be supplied by said pressure sensor 279. Alternatively, the pressure P can be calculated by means of the first control unit 200 in a suitable manner. At time TWO rod dosing of the branch ay. At a time Ti, a pressure drop in the industry at the dosing unit 250 is initiated from a first predetermined pressure level P1 to a pressure level PX. The time Ti occurs at a certain predetermined time period after TO. This time period can be an appropriate time period, for example 3 seconds. Figure 4c illustrates an embodiment where the pressure drop takes place in two steps. At a certain time period after Ti, a pressure drop is initiated when the pressure drops to said level PX. At time T2, which occurs a certain predetermined time period after T1, for example 10 seconds, a second pressure drop is initiated from the pressure level PX to a second pressure level P2. The first pressure level P1 can, for example, be 15 Bar. The second pressure level P2 can be, for example, 5 Bar. The pressure level PX can be, for example, 10 Bar. In this case, said pressure drops take place essentially momentarily. When initiating dosing of fuel by means of the dosing unit 250, the pressure P can be controlled to a suitable pressure level, for example to said first pressure level P1, in a suitable manner, for example stepless.

It should be noted that pressure reduction of the fuel at the dosing unit 250 according to certain embodiments only takes place under predetermined criteria. These criteria may be, for example, one or more of the following: the temperature of a luminescent surface of or component i of the exhaust duct 290 or of the exhaust gases in exhaust duct 290 is below a certain predetermined value, for example 200 degrees Celsius; branch leakage of the dosing unit 250 has been detected; regeneration of the particle filter 270 is not required; regeneration of the particle filter 270 is not active.

Referring to Figure 5, there is shown a diagram of an embodiment of a device 500. 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 fifteenth memory portion 530 used in a computer program, such as an operating system, stored to control the operation of the device 500. Further, the device 500 includes a bus controller, a serial communication port, I / O means, an A / D converter, a time and date input and transfer unit, a trade calculator 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 may include routines for pressure reduction of a fuel at a metering unit in an HC metering system to prevent leakage of fuel when the metering unit is closed. The computer program P may comprise routines for during periods of non-continuous dosing of fuel, during continued maintenance of said pressurizing means 230, lowering the pressure P of said branch at dosing unit 250 compared with the pressure at continuous dosing. The computer program P may include routines for lowering the pressure P of said fuel at the metering unit 2 by reducing the speed of said pressurizing means 230. The computer program P may include routines for lowering the pressure of said branch at the metering unit 250 by reducing the stroke frequency of said pressurizing means 230. The computer program P may include routines for lowering the pressure of said fuel at the metering unit 250 by controlling a valve configuration 288 of a downstream side of the metering unit 250. The computer program P may include routines for lowering the pressure of said branch at the metering unit 250 by controlling line of said branch from said pressurizing means 230 to said container 205 past said dosing unit 250. Said control may comprise controlling at least one valve configuration (not shown) of, for example, said line 274. The fuel may then be led past said dosing unit via said line 274. The computer program P may include routines for lowering the pressure of said branch at the metering unit by controlling a feed means 300 disposed downstream of the metering unit 250. The computer program P may include routines for substantially lowering the pressure of said branch at the metering unit. The computer program P may include routines for lowering the pressure in said industry steplessly. The computer program P may include routines for lowering the pressure of said industry in steps. The computer program P may comprise routines for increasing the pressure of said branch at the dosing unit 250 when the continuous dosing is resumed. The computer program P may comprise routines for, at a predetermined time before a fixed time d5 continuous dosing of the branch ceases, dosage unit 250.

The program P can be stored p5 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 should be understood that the data processing unit 510 performs a certain part of the program which is stored in the memory 560, or a certain part of the program which is stored in the read / write memory 550.

The data processing device 510 can communicate with a data port 599 via a data bus 515. The non-volatile memory 520 is 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 a data bus 511. Read / write memory 5 is arranged to communicate with the data processing unit 510 via a data bus 514. To the data port 599, e.g. the lanes L210, L230, L240, L250, L255, L260, L265, L279, L288 and L300 are connected (see Figure 2a and Figure 2b).

When data is received at the data port 599, it is temporarily stored in the second memory portion 540.

Once the received input data has been temporarily stored, the data processing unit 510 is ready to perform code execution in a manner described above. According to one embodiment, signals received on the data port 599 comprise information about a radiating pressure P of the branch at said dosing unit 250. According to one embodiment, signals received on the data port 599 comprise information about a radiating temperature of a suitable surface of or component i of the exhaust duct 290 or a radiating temperature of the exhaust gases in said exhaust duct 290.

The received signals on data port 599 may be used by the device 500 to lower the pressure of a fuel at the metering unit 250 of an HC metering system to prevent leakage of fuel when the metering unit is closed.

Parts of the methods described herein may be performed by the device 500 using the data processing unit 510 as the program stored in the memory 560 or the 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 in order 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 which are appropriate to the intended use. 32

Claims (24)

PATENT REQUIREMENTS A method of an HC dosing system comprising a dosing unit (250) for dosing fuel into an engine exhaust duct (290) upstream of a particulate filter (270) for purifying exhaust gases from said engine, said HC dosing system including pressurizing means (230) to supply fuel from a container (205) to said dosing unit (250) arranged to dose said fuel under pressure to said exhaust duct (290), characterized by the step of: - during periods of non-continuous dosing of fuel, during continued maintenance of said pressurizing means (230), lowering the pressure (s301; s320) of said branch at the dosing unit (250) compared with the pressure at continuous dosing. The method of claim 1, comprising the step of: - lowering the pressure (s320) of said branch at the metering unit (250) by reducing a speed (RPM) of said pressurizing means (230). The method of claim 1, comprising the step of: 1. lowering the pressure (s320) of said branch at the metering unit (230) by reducing a stroke frequency of said pressurizing means (230). A method according to any one of claims 1-3, comprising the step of: 1. lowering the pressure (s320) of said branch at the dosing unit (250) by controlling a valve configuration (288) of a downstream side of the dosing unit (250). A method according to any one of claims 1-4, comprising the step of: 1. lowering the pressure (s320) of said branch at the dosing unit (250) by directing said branch from said pressurizing means (230) to said container (205) past said dosage unit (250). A method according to any one of claims 1-4, comprising the step of: 1. lowering the pressure (s230) of said fuel at the dosing unit (250) by controlling a feed means (300) arranged downstream of said dosing unit (250). A method according to any one of claims 1-4, comprising the step of: - substantially lowering the pressure (s320) of said industry at the dosing unit (250). A method according to any one of claims 1-7, wherein said lowering of the pressure of said fuel at the dosing unit (250) takes place steplessly. A method according to any one of claims 1-7, said lowering of the pressure of said branch at the dosing unit (250) takes place in steps. A method according to any one of the preceding claims, comprising the step of: 1. at Resumed continuous dosing, raising the pressure (s340) of said fuel at the dosing unit (250). A method according to any one of claims 1-10, comprising the step of: 1. at a predetermined time before a fixed time d5 continuous dosing of fuel is to cease, starting pressure drop of said branch at the dosing unit (250). 34 HC dosing system arranged to dose fuel into an engine exhaust duct (290) upstream of a particulate filter (270) for purifying exhaust gases from said engine, said HC dosing system comprising: - a dosing unit (250) adapted to dose said pressure under pressure. fuel for said exhaust duct (290); a pressurizing means (230) adapted to feed fuel from a container (205) to said dosing unit (250), characterized in that: - means (200; 210; 500) adapted to, during periods of non-continuous dosing of fuel, during continued maintaining the operation of said pressurizing means (230), lowering the pressure of said branch at the dosing unit (250) in comparison with the pressure during continuous dosing. The HC dosing system of claim 12, wherein said pressurizing means (230) comprises a controllable speed (RPM) pump. The HC dosing system of claim 12, wherein said pressurizing means (230) comprises a pump with controllable stroke frequency. An HC dosing system according to any one of claims 12-14, comprising: - a valve configuration (288) arranged at a downstream side of the dosing unit (250). An HC dosing system according to any one of claims 12-15, comprising: - means (200; 210; 500) adapted to substantially lower the pressure of said fuel at said dosing unit (250). An HC dosing system according to any one of claims 12-16, comprising: 1. means (200; 210; 500) adapted to lower the pressure of said fuel at said dosing unit (250) steplessly. HC dosing system according to any one of claims 12-16, comprising: - means (200; 210; 500) adapted to lower the pressure of said industry in steps. An HC dosing system according to any one of claims 12-18, comprising: 1. means (274) adapted to direct said fuel from said pressurizing means (230) to said container (205) past said dosing unit (250). An HC dosing system according to any one of claims 12-19, comprising: 1. a supply means (300) arranged downstream of the dosing unit (250). A motor vehicle (100; 110) comprising an HC dosing system according to any one of claims 12-20. A motor vehicle (100; 110) according to claim 21, wherein the motor vehicle is any of a truck, bus or passenger car. A computer program (P) in an HC dosing system for purifying exhaust gases in an engine, wherein said computer program (P) comprises program code for causing an electronic control unit (200; 500) or another computer (210; 500) connected to it electronic control unit (200; 500) 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 program code is crossed on an electronic control unit (200; 500) or another computer (210; 500) connected to the electronic control unit (200; 500). 36 1/6 100 0 (112