SE530234C2 - Arrangement is for injecting fuel or reduction medium into exhaust gas conduit from internal combustion engine and comprises mouthpiece assembly with mouthpiece head - Google Patents

Abstract

The arrangement (1) is for injecting fuel or reduction medium into the exhaust gas conduit from an internal combustion engine and comprises a mouthpiece assembly (20) with a mouthpiece head (21) into which issues a first conduit (22) for supply of pressurized gas, preferably in the form of compressed air to the mouthpiece head part. A second conduit (23) issues into the mouthpiece head part for the supply of fluid medium. The mouthpiece head part (21) has at least one outlet aperture (24) connected to the first and second conduits via which the fluid medium can be injected into the exhaust gas conduit after fine distribution and mixture with pressurized gas inside the mouthpiece head.

Description

530 23 530 234 The medium / air mixture is led to a nozzle which injects the mixture into the exhaust line during atomization of the reducing agent. It has proved difficult to achieve a satisfactory atomization of the reducing agent in the exhaust gases when using an injection device of this previously known type.

OBJECT OF THE INVENTION The object of the present invention is to provide a device for injecting a liquid agent into the exhaust line from an internal combustion engine, which device allows a good atomization of the liquid agent in the exhaust gases flowing through the exhaust line and at the same time allows a fast change in the amount of liquid agent injected into the exhaust line.

SUMMARY OF THE INVENTION According to the invention, said object is achieved by means of an injection device having the features stated in claim 1.

The injection device according to the invention comprises a nozzle device having a nozzle head from which the liquid means can be injected into the exhaust line, wherein: the nozzle device comprises a first line opening into the nozzle head for supplying pressurized gas, preferably a pressure nozzle the opening second line for supplying said liquid means to the nozzle head, and - the nozzle head is provided with at least one outlet opening connected to the first line and to the second line, via which said liquid means can be injected into the exhaust line during atomization after mixing with pressurized gas in a mixing area inside the nozzle head. By allowing the liquid agent to mix with pressurized gas inside the nozzle head, i.e. in a limited space immediately before the mixture thus obtained is sprayed out of the nozzle head via the outlet opening, a change in the dosage will occur. of the liquid agent very quickly to affect the amount of liquid agent which is injected into the exhaust line via the nozzle head. At the same time a first atomization of the liquid agent is obtained by mixing it in the flow of pressurized gas inside the nozzle head and a further atomization of the liquid agent when this together with said gas is injected into the exhaust line via the outlet opening of the nozzle opening. This makes it possible to achieve a satisfactory atomization of the liquid agent.

According to the invention, the device comprises a pressure sensor which is arranged to generate a pressure value representing the pneumatic pressure in the first line of the nozzle device, and an electronic control unit connected to the pressure sensor which is arranged to generate information regarding the functionality of the nozzle device based on said pressure value. The electronic control unit can, for example, be arranged to detect, by analysis of said pressure value, clogging of the nozzle opening of the nozzle head or some other malfunction of the nozzle device which affects the pressure in the first line.

According to an embodiment of the invention, the nozzle head comprises a first channel connected to the first line for guiding pressurized gas to the outlet opening and a second channel connected to the second line, one or more inlet holes connected to the second channel opening into the the first channel with the respective inlet holes so arranged that pressurized gas is allowed to flow through the first channel past the inlet hole and carry liquid medium flowing out of it to the outlet opening. Thus, the liquid agent is introduced into the pressurized gas flowing through the first channel so that this gas is allowed to effectively expose the agent flowing into the first channel to atomizing action.

According to another embodiment of the invention, the nozzle head is arranged inside the exhaust line, wherein at least the parts of the first line and the second line which extend into the exhaust line up to the nozzle head are coaxially arranged relative to each other with the first line arranged externally if the second management. As a result, the pressurized gas flowing through the first line in connection with the injection of the liquid agent can have a cooling and heat-insulating effect with respect to the liquid agent which is simultaneously in the second line. This makes it possible in a simple and efficient manner to prevent heat transfer from hot exhaust gases in the exhaust pipe causing an undesired overheating of the liquid agent during its passage through the second pipe to the nozzle head.

According to another embodiment of the invention, said outlet opening of the nozzle head is directed towards the intended flow direction of exhaust gases flowing through the exhaust line. This means that the liquid agent is injected into the exhaust line in the countercurrent direction of the exhaust line, whereby the injected liquid droplets have a longer transport distance and residence time in the exhaust line compared with a conventionally designed injection device where the injection takes place in the exhaust current direction. An increased residence time of the liquid droplets in the exhaust line provides an improved possibility of ensuring a desired evaporation of the liquid droplets before they reach a catalyst arranged downstream of the nozzle head.

According to another embodiment of the invention, the device comprises a first gas inlet intended for receiving said pressurized gas and a second gas inlet connected to at least one of said first and second lines 1030 20 5 530 234 of the nozzle device and which is intended for receiving pressurized air from the inlet air duct of the internal combustion engine to enable discharge of this air through the outlet opening of the nozzle head and thereby counteract clogging of the outlet opening during periods when no injection of said pressurized gas and / or said liquid means takes place the piece head. This makes it possible in a simple manner to counteract a blockage of said outlet opening caused by the exhaust gases flowing through the exhaust line.

Other preferred embodiments of the invention appear from the dependent claims and the following description.

The invention also relates to the use of a device according to the invention in a motor vehicle for injecting fuel into the exhaust line from the internal combustion engine of the motor vehicle upstream of an oxidation catalyst arranged in the exhaust line in connection with regeneration of an oxidation catalyst arranged in the exhaust line with a regeneration filter. the exhaust line downstream of the oxidation catalyst arranged NOX trap. The invention further relates to the use of a device according to the invention in a motor vehicle for injecting reducing agent into the exhaust line from the internal combustion engine of the motor vehicle upstream of an SCR catalyst or lean-NOX catalyst arranged in the exhaust line.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be described in more detail below with the aid of exemplary embodiments, with reference to the accompanying drawings.

It is shown in: Fig. 1 a schematic, partially cut-away side view of a device according to the present invention, with the nozzle head included in the device shown in a detailed enlargement, Fig. 2 a principle sketch of a device according to the present invention in interaction with an internal combustion engine, and Fig. 3 is a schematic front view of a component of the device illustrated in Fig. 1.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION Figures 1 and 2 illustrate a device 1 according to the present invention for injecting a liquid agent, such as fuel or reducing agent, into the exhaust line 2 of an internal combustion engine 20 having a nozzle head 21 from which the liquid means is intended to be injected into the exhaust line. The nozzle device 20 comprises a first line 22 opening into the nozzle head 21 for supplying pressurized gas, preferably in the form of compressed air, to the nozzle head and a second line 23 opening into the nozzle head 21 for supplying said liquid means to the nozzle head. The nozzle head 21 is provided with an outlet opening 24 connected to the first line 22 and to the second line 23, via which said liquid means can be injected into the exhaust line during atomization thereof after mixing with pressurized gas in a mixed medium. area 25 inside the nozzle head. In the illustrated example, the nozzle head 21 is provided with such an outlet opening 24, but alternatively two or more such outlet openings 24 could be arranged in the nozzle head.

In the embodiment illustrated in Fig. 1, the nozzle head 21 comprises a first channel 26 for connecting pressurized gas to the outlet opening 24 connected to the first line 22 and a second channel 27 connected to the second line 23.

One or more inlet holes 28 connected to the second channel 27 open into the first channel 26, the respective inlet holes 28 being arranged so that pressurized gas is allowed to flow through the first channel 26 past the inlet hole 28 and lead with liquid medium flowing therefrom to the outlet opening 24. The second channel 27 is thus flow-connected to the first channel 26 via said inlet hole 28. The first channel 26 and the second channel 27 are suitably coaxially arranged relative to each other, as illustrated in Fig. 1. , the first channel 26 being preferably arranged externally about the second channel 27. In the illustrated example, respective inlet holes 28 extend radially between the first channel 26 and the second channel 27, i.e. radially relative to the center axis of said channels 26, 27, whereby the liquid agent will flow into the pressurized gas flowing through the first channel 26 for in the inlet holes 28 substantially perpendicular to the flow direction of this gas. Thus, in this case, the above-mentioned mixing area 25 is formed by the part of the first channel 26 extending between the inlet holes 28 and the outlet opening 24. The liquid agent is atomized by and mixed with the pressurized gas when the agent via the inlet holes 28 enters the mixing area 25 and is then transported further together with the pressurized gas up to and out through the outlet opening 24. Upon passage through the outlet opening 24, a further atomization of the liquid agent takes place. The inlet holes 28 are suitably two or more in number and distributed in the circumferential direction of the second channel.

The device 1 further comprises a valve device 30 connected to the nozzle device 20, which comprises valves 31, 32, 33 for controlling the supply of pressurized gas and liquid means to the lines 22, 23 of the nozzle device. In the illustrated example, these valves 31, 32, 33 are mounted in a common valve housing 34.

The valve device 30 comprises a control valve 31 which controls the supply of liquid agent to the second line 23 of the nozzle device. This control valve 31 suitably consists of a pulse width modulated injection valve. By means of this valve 31 it is possible to control the amount of liquid agent to be injected into the exhaust line, i.e. the dosage of the liquid agent. In the illustrated embodiment, an inlet 35 is provided for receiving said liquid means arranged in the valve housing 34. Via the control valve 31 the liquid means can be led from the inlet 35 and into the second line 23. A pressure regulator 36 is arranged in the valve housing 34 to ensure a desired pressure of the liquid means which is led via the inlet 35 to the control valve 31.

The valve device 30 further comprises a first control valve 32, via which the first line 22 of the nozzle device is connectable to a source of pressurized gas, suitably in the form of a source of compressed air. With the aid of this control valve 32, it is thus possible to control the supply of pressurized gas to the first line 22. In the illustrated example, the first control valve 32 is a three-way valve. In the illustrated example, the valve device 30 also comprises a second control valve 33, via which the second line 23 of the nozzle device is connectable to said source of pressurized gas for purifying the second line 23 at desired occasions. With the aid of this control valve 33, it is thus possible to control the supply of pressurized gas to the second line 23.

In the illustrated embodiment, a first gas inlet 37 and a second gas inlet 38 are arranged in the valve housing 34. The first gas inlet 37 is intended for receiving said pressurized gas. Via the first control valve 32 the pressurized gas can be led from the first gas inlet 37 and into the first line 22 and via the second control valve 33 this gas can be led from the first gas inlet 37 and into the second line 23. The second gas inlet 38 is intended for receiving pressurized air from the inlet air duct of the internal combustion engine. Via the first control valve 32 the air can be led from the second gas inlet 38 and into the first line 22. Via the first line 22 the pressurized air received via the second gas inlet 38 can thus be led to the nozzle head 21 to be discharged through its outlet opening 24 and thereby counteract clogging of the outlet opening during periods when no injection of said pressurized gas and / or said liquid means takes place via the nozzle head 21.

The nozzle device 20 is connected to the valve device 30 via a coupling mechanism 39. In the illustrated example, the second conduit 23 of the nozzle device 20 extends a distance into an outlet channel 40 arranged in the valve housing 34.

The end of the conduit 23 received in the outlet channel 40 is held in place in the outlet channel by means of a sleeve-shaped holding member 41 which supports the conduit 23 in the radial direction. This holding means 41 together with the line 23 divides the outlet channel 40 into a first space 40a for receiving liquid means from the control valve 31 and a second space 40b for receiving pressurized gas. A channel 42 communicating with the control valve 32 opens into the second space 40b and this channel 42 is connected to the first conduit 22 of the nozzle device 20 via openings 43 in the holding means 41. A channel 44 communicating with the control valve 33 opens into the first space 40a to enable purification of the second line 23 with pressurized gas.

In the illustrated example, the device 1 comprises a pressure sensor 45 which is arranged to generate a pressure value representing the pneumatic pressure in the first line 22 of the nozzle device. The pressure sensor 45 is mounted in the valve housing 34 and communicates with the first conduit 22 via a channel 46 extending between the pressure sensor and the outlet channel 40.

The pressure sensor 45 is connected to an electronic control unit 50 (see Fig. 2) which is arranged to generate information regarding the operability of the nozzle device 20 and / or the valve device 30 based on said pressure value. The electronic control unit 50 is advantageously arranged to detect clogging of the nozzle opening 24 of the nozzle head by analysis of said pressure value. for example before and / or after an injection of liquid agent into the exhaust line.

In the illustrated example, the device 1 also comprises a pressure sensor 47 which is arranged to generate a pressure spring representing the hydraulic pressure of the liquid means upstream of the control valve 31. This pressure sensor 47 is mounted in the valve housing 34 and communicates with one in the valve housing. arranged inlet channel 48 for the liquid means via a channel 49 which extends between the pressure sensor 47 and this inlet channel 48. The pressure sensor 47 can also be connected to said electronic control unit 50, as illustrated in Fig. 2.

The nozzle head 21 is suitably arranged inside the exhaust line, as illustrated in Figs. 1 and 2. In this case it is advantageous to arrange the parts of the first line 22 and the second line 23 which extend into the exhaust line up to the nozzle head 21. coaxially with respect to each other, with the first conduit 22 arranged externally about the second conduit 23. Preferably, the first conduit 22 and the second conduit 23 are coaxially arranged with respect to each other along the entire distance between the valve housing 34 and the nozzle head 21.

In order to increase the residence time of the liquid agent in the exhaust gases, i.e. the time during which the liquid agent after the injection into the exhaust line is in contact with the exhaust gases in the exhaust line before it reaches the intended catalyst together with the exhaust gases, the outlet opening is 24 of the nozzle head advantageously directed towards the intended flow direction of exhaust gases flowing through the exhaust line, as illustrated in Figs. 1 and 2. In Figs. 1 and 2, this flow direction is marked with the arrows P1. In the illustrated example, the nozzle head 21 is arranged inside the exhaust line, in the center thereof, and is directed towards the intended flow direction of exhaust gases flowing through the exhaust line. Advantageously, a control means 60 is arranged in the exhaust line 2 downstream of the nozzle head 21, which control means 60 is arranged to flow through exhaust gases and create turbulence of the flowing exhaust gases in order thereby to achieve an increased dispersion. of the liquid agent accompanying the exhaust gases after being injected into the exhaust line 2 via the nozzle head 21. This improves the possibilities of achieving an even dispersion and rapid evaporation of the liquid agent in the exhaust gases before it reaches the intended catalyst. The control means 60 also helps to catch droplets of the liquid agent which have not yet been evaporated after the injection into the exhaust line 2.

The operation of a device 1 of the type illustrated in Fig. 1 will be described in the following with reference to Fig. 2. Fig. 2 illustrates an application where the device 1 is used in a motor vehicle for injecting liquid agent in the form of fuel into the exhaust line 2 from the combustion engine 3 of the motor vehicle upstream of an oxidation catalyst 4 arranged in the exhaust line in connection with regeneration of a filter 5 arranged in the exhaust line downstream of the oxidation catalyst. However, the device 1 according to the invention is also useful in a motor vehicle of fuel in the exhaust line from the internal combustion engine of the motor vehicle upstream an oxidation catalyst arranged in the exhaust line in connection with regeneration and desulphation of a NOX trap arranged in the exhaust line downstream of the oxidation catalyst.

The device 1 according to the invention is furthermore also useful in a motor vehicle for injecting liquid agent in the form of reducing agents, such as for instance urea or fuel, in the exhaust line from the internal combustion engine of the motor vehicle upstream of an SCR catalyst or lean-Nox catalyst arranged in the exhaust line. . In the example illustrated in Fig. 2, the device 1 comprises a fuel container 70, which is connected to the above-mentioned inlet 35 in the valve housing 34 via a supply line 71. In the supply line 71, a pump 72 is arranged for supplying fuel from the container 70 to the control valve 31 of the valve device 30. A fuel filter 74 is also provided in the supply line 71. A return line 73 directs excess fuel from the valve device 30 back to the fuel container 70 via an outlet 35 'in the valve housing 34.

The fuel container 70 is connected in a return fuel line 7 extending between the internal combustion engine 3 and a fuel tank 6 to receive return fuel from the internal combustion engine. Said fuel tank 6 constitutes an ordinary tank for motor fuel of the motor vehicle.

To the combustion engine 3 schematically shown in Fig. 2, air is taken via an air intake 8, in connection with which an air filter 9 can be arranged. The air is led via an inlet air duct, generally designated 10, in the direction of the combustion engine of the combustion engine. In the example illustrated in Fig. 2, the motor vehicle is provided with a turbocharger 11, which has a compressor wheel 11a for supplying the air to the internal combustion engine with overpressure and a turbine wheel 11b positioned so that it is set in rotation by actuating exhaust gases leaving the internal combustion engine. . The compressor wheel 11a and the turbine wheel 11b are operatively connected to each other, for example by being located on one and the same shaft 11c. As is customary in supercharging, the air, after being overpressured, can be subjected to cooling in an intercooler.

The exhaust gases leaving the combustion engine 3 move in the exhaust line 2 and exit into the environment via an exhaust outlet 13. Fig. 2 illustrates how the exhaust gases are led through the above-mentioned oxidation catalyst 4 and filter 5 before they exit into the environment via the exhaust outlet 13 The filter 5 is arranged to release the exhaust gases from particulate constituents. In the illustrated example, the nozzle head 21 is arranged in the exhaust line 2 between the turbine wheel 11b and the oxidation catalyst 4 with its outlet opening 24 directed towards the flow direction of exhaust gases flowing through the exhaust line 2. The above-mentioned second gas inlet 38 of the valve device 30 is connected via a line 14 to the inlet air duct 10 downstream of the compressor wheel 11a to receive air pressurized therefrom. In this line 14, a check valve 15 is suitably arranged, as illustrated in Fig. 2. In the illustrated example, the line 14 is connected to the inlet air duct 10 between the charge air cooler 12 and the internal combustion engine 3. The above-mentioned first gas inlet 37 of the valve device 30 is connected via a line 16 to a compressed air source 17. In this line 16 a non-return valve 18 is suitably arranged, as illustrated in Fig. 2. The control valve 31 and the control valves 32, 33 of the valve device are controlled depending on control signals from an electronic control unit 50, which is arranged to output control signals to said valves 31, 32, 33 in dependence on predetermined parameters. These parameters may include, for example, the exhaust gas temperature upstream of the oxidation catalyst 4, the exhaust gas temperature downstream of the filter 5, the exhaust gas mass flow, the pressure drop of the exhaust gases over the filter 5, etc. 45 to receive measured values from these related to the fuel pressure upstream of the control valve 31 and the pressure in the above-mentioned first line 22 of the nozzle device 20, respectively.

Before fuel is to be injected into the exhaust line 2, the control valve 33 is opened so that the fuel line 23 of the nozzle device, ie the above-mentioned second line, is blown clean by means of compressed air from the compressed air source 17. During this purge the control valve 31 is kept closed. Thereafter, the control valve 33 is closed, and the control valve 32 is caused to connect the air line 22 of the nozzle device, i.e. the above-mentioned first line, to the compressed air source 17. By opening the control valve 31, fuel is led into the fuel line 23 to mix with compressed air. council 25 in the nozzle head 21 and together with the compressed air is injected into the exhaust line 2 via the nozzle head outlet opening 24. When sufficient fuel has been injected, the control valve 33 is opened for blowing the fuel line 23. The control valve 31 is kept closed during this purge injection site. After purge, the control valve 33 is closed, and the control valve 32 is brought to connect the air line 22 to the internal combustion engine inlet air duct 10 for supplying charge air through the air line 22 and further out through the nozzle head outlet opening 24. When it is time for the next fuel injection the control valve 32 is caused to break the connection between the inlet air duct 10 and the air line 22 and the process described above is repeated. The process described here is also applicable when a device according to the invention is used for injecting reducing agent into an exhaust line from an internal combustion engine.

The invention is of course not in any way limited to the preferred embodiments described above, but a number of possibilities for modifications thereof should be obvious to a person skilled in the art, without this departing from the basic idea of the invention as defined. in the appended patent claims.

Claims (10)

53Ü 234 15 NEW PATENT REQUIREMENTS Device for injecting a liquid agent, such as fuel or reducing agent, into the exhaust line of an internal combustion engine, said device (1) comprising a nozzle device (20) having a nozzle head (21) from which the liquid agent is injectable in the exhaust line, the nozzle device (20) comprising a first line (22) opening into the nozzle head (21) for supplying pressurized gas, preferably in the form of compressed air, to the nozzle head and a second line (21) opening into the nozzle head (21). 23) for supplying said liquid means to the nozzle head, and - the nozzle head (21) is provided with at least one outlet opening (24) connected to the first line (22) and to the second line (23), via which said liquid agent is injectable into the exhaust line during atomization thereof after mixing with pressurized gas in a mixing area (25) inside the nozzle head, characterized that the device (1) comprises: - a pressure sensor (45) arranged to generate a pressure value representing the pneumatic pressure in said first line (22) of the nozzle device (20), and - a pressure sensor (45) connected electronic control unit (50) arranged to generate information regarding the operability of the nozzle device (20) based on said pressure value. 30 Device according to claim 1, characterized in that the nozzle head (21) comprises a first channel (26) connected to the first line (22) for conducting pressurized gas up to the outlet opening (24) and one to the second line 35 (23). ) connected second channel (27), and that one or more inlet holes (28) connected to the second channel (23) open into the first channel (22), the respective inlet holes (28) being so different. 30 35. Device according to claim 7, 530 234 16 arranged that pressurized gas is allowed to flow through the first channel (22) past the inlet hole (28) and to carry liquid medium flowing out therefrom to the outlet opening (24). . Device according to claim 2, characterized in that the first channel (26) and the second channel (27) are arranged coaxially in relation to each other. . Device according to claim 3, characterized in that the first channel (26) is arranged outside the second channel (27). . Device according to claim 3 or 4, characterized in that said inlet hole (28) extends radially between the second channel (27) and the first channel (26). . Device according to claim 5, characterized in that the inlet holes (28) are two or more in number and are distributed in the circumferential direction of the second channel. . Device according to any one of claims 1-6, characterized in that said outlet opening (24) of the nozzle head (21) is directed towards the intended flow direction of exhaust gases flowing through the exhaust line. characterized in that the nozzle head (21) is arranged inside the exhaust line, preferably in the center thereof, and is directed towards the intended flow direction of the exhaust gas flowing through the exhaust line. Use of a device according to any one of claims 1-8 in a motor vehicle for injecting fuel into the exhaust line from the internal combustion engine of the motor vehicle upstream of an oxidation catalyst arranged in the exhaust line in connection with regeneration of a filter arranged in the exhaust line downstream of the oxidation catalyst or in connection with regeneration of a NOx trap arranged in the exhaust line downstream of the oxidation catalyst in the exhaust line. Use of a device according to any one of claims 1-8 in a motor vehicle for injecting reducing agent into the exhaust line from the motor vehicle's internal combustion engine upstream of an SCR catalyst or lean-NOX catalyst arranged in the exhaust line.