• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    The invention relates to a device and a method for injecting a reactant, for example an aqueous solution of urea into an exhaust line (3) of an internal combustion engine. The device comprises an injector (14) which is arranged with a resilient part (20) in connection with the attachment of the injector (14) to the exhaust line and which has caused at least the nozzle of the injector (15, 21) to be resiliently attached to the exhaust line (3). This allows the nozzle (15, 21) to be allowed a limited movement relative to the exhaust line (3), and which during operation of the internal combustion engine causes the nozzle (15, 21) of the injector to be subjected to vibrations from the internal combustion engine which causes the nozzle injected from the nozzle (3). This avoids the reactant cooling parts of the exhaust line, which can prevent the intended evaporation of the same. (Fig. 2)
    公开号:SE0950404A1
    申请号:SE0950404
    申请日:2009-06-04
    公开日:2010-12-05
    发明作者:Ola Stenlaaaas
    申请人:Scania Cv Ab；
    IPC主号:
    专利说明:

    If the layer of urea becomes sufficiently thick, the urea and its decomposition products will react with themselves. The result is primitive polymers on urea base, so-called ureak- lumps. Such lumps of urea can eventually block an exhaust line.
    As a solution to said problem, various ways have previously been proposed to ensure that the urea is better decomposed by directing the jets' rays towards a grid as described in EP 1748162.
    Another variant of solution is described in EP 1781908, where the solution is that the injection is made in a heat-insulating pipe, so that the injected jets do not risk hitting cold surfaces in the exhaust line.
    According to a further variant described in WO 2006/084551, an injector with a rotating nozzle part is used. The nozzle part is angled so that the nozzle can rotate by the reaction forces that the injection gives rise to. In order for this rotation to be as efficient as possible, it is necessary that the nozzles are arranged at a large radial distance from its center of rotation. This is in close proximity to the exhaust line walls which are the areas you want to avoid.
    Common to the known solutions is that they in different ways require that different components must be arranged in connection with the injectors and the devices thus become more or less expensive. In some cases, regular inspections and maintenance are also required, which further increases costs.
    SUMMARY OF THE INVENTION The object of the present invention is to provide an apparatus and a method for injecting a urea solution into an exhaust line where the formation of urea lumps in the exhaust line is prevented.
    A further object is that it should be done in a manner which does not exhibit the disadvantages of the known solutions, and moreover does so in a simpler and less costly manner.
    These objects are achieved with the device of the kind mentioned in the introduction, which is characterized by the features stated in the characterizing part of claim 1. A prerequisite for urea lumps to be able to form inside the exhaust line is that the same area of the interior surface of the exhaust line is hit by unevaporated urea solution for a longer period of time. The fastening of the nozzle of the injection means according to the invention allows the injection of ureal solution to take place against different areas, which thereby do not risk being cooled down, whereby the conditions for accumulation of urea lumps are significantly reduced. With such a variation of, the risk is eliminated that the same area is hit by unvaporized urea solution during engine operation and thus that urea lumps form in the exhaust line.
    According to a preferred embodiment of the present invention, where the nozzle of the injection means consists of a nozzle inserting into the exhaust line, the resilient part consists of a resilient intermediate nozzle which is arranged between a fixed part of the nozzle connected to the exhaust line and a movable part of the nozzle including the nozzle outlet. With such a design a simple solution is obtained at the same time as it is possible for a number of already known solutions to be supplemented with only a few parts in order to obtain a solution according to the invention.
    Further preferred embodiments of the invention appear from the following descriptive examples, all of which are characterized by the fact that they are simple and relatively inexpensive to arrange on existing exhaust lines. Thus, no extensive modifications of existing exhaust systems are required and it is possible to choose an embodiment that is best suited for each application.
    In another advantageous embodiment, the engine is arranged as a drive engine in a vehicle. In such a case, in addition to the vibrations arising from the operation of the engine, vibrations arising from the operation of the vehicle will also cause the nozzle to be subjected to vibrations.
    These vibrations caused by the operation of the vehicle can in some cases be considerably stronger than the vibrations arising from the operation of the engine, which entails favorable circumstances to ensure that no urea lumps form in the exhaust line.
    BRIEF DESCRIPTION OF THE DRAWINGS In the following, exemplary embodiments of the invention are described by way of example with reference to the accompanying drawings, in which: Fig. 1 schematically shows a device for injecting urea solution into an exhaust line according to a first embodiment of the present invention, Fig. 2 shows the injection zone in FIG. 1 in more detail, and a first embodiment of the invention, Fig. 3 shows a device for injecting urea solution into an exhaust line according to an alternative second embodiment, Fig. 4 shows a device for injecting urea solution into an exhaust line according to an alternative third embodiment, and Fig. 5 shows a device for injecting urea solution into an exhaust line according to an alternative fourth embodiment.
    DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION Fig. 1 schematically shows an internal combustion engine of a diesel engine 1. The diesel engine 1 may be intended as a drive engine for a vehicle, for example a heavier vehicle such as a truck or a bus. The exhaust gases from the cylinders of the diesel engine 1 are led, via an exhaust gas collector 2, to an exhaust line 3. The exhaust line 3 has here been provided with a catalytic exhaust purification according to the method called SCR (Selective Catalytic Reduction).
    This method means that reducing agent, in this example in the form of a urea solution, is supplied to the exhaust gases in the diesel engine's exhaust line 3. The urea solution is stored in a tank 4 and led, via a line 6 (including a pump not shown), to an injector (dosing unit ) 14 for injecting urea solution into the exhaust line 3. The injector 14 is further connected to control means (not shown) which, depending on known parameters, control the injection in a manner known per se.
    The injector 14 comprises a nozzle 15, which is shown in more detail in Fig. 2, arranged in a dedicated portion 13 of the exhaust line 3. The exhaust line comprises downstream of the portion 13 an SCR catalyst 5. The exhaust line 3 may in addition comprise a turbocharger driven by the exhaust gases for supercharging of the engine and additional components (for example mufflers, particle filters, catalysts and the like) of a kind known per se, but as these are not important for understanding the invention, they are not described in more detail.
    Fig. 2 shows the portion 13 according to Fig. 1 of the exhaust line 3 in more detail. The exhaust flow direction in the exhaust line 3 is indicated by arrows 10. The injector 14 thus comprises a nozzle 15 which protrudes into the exhaust line 3, it initially extending substantially radially into the exhaust line 3, after which it has a curvature in exhaust direction of fate.
    The nozzle 15 is in the portion at the passage through the wall of the exhaust line surrounded by a bracket 16 by means of which it is fixedly arranged at the wall of the exhaust line 3. In the portion at the bracket 16 the nozzle is formed as a fixed tube 17 while its other end comprises an angled, tubular part 18 and at the end of which a number of radial heels 21 are arranged through which urea solution can be injected into the exhaust gas in the exhaust line 3. The wine the end of the kelbocked part 18 protrudes into the exhaust line substantially to its center so that the terminating end is in the area around the center line of the exhaust line (not shown).
    The holes 21 at the end of the nozzle 15 extend around its entire circumference so that the urea solution can be evenly distributed in the circulating exhaust gas stream. The urea solution is injected substantially uniformly like a plume 19. The urea solution is injected into the exhaust line 3 in atomized form by means of a compressed air fate effected in the injector 14. The non-distributed urea solution is evaporated relatively quickly by the hot exhaust gases in the exhaust line 3.
    The fixed pipe 17 of the nozzle is connected to the angle-bent part 18 via a resilient intermediate piece 20, which means that the angled-bent part 18 is allowed a limited movement relative to the pipe 17 fixedly connected to the exhaust line. In Fig. 2 this is indicated by the angled part 18 is shown in two of its outer positions. In the position shown in solid lines, the angularly bent part 18 is maximally angled downwards, and the urea solution will then be injected in the direction similar to a plume 19 shown in solid lines. In this position, urea solution injected through the holes 21 located on the underside of the nozzle will be directed towards the wall of the exhaust line at a position which is axially (relative to the exhaust line) relatively close to the angled bend while urea solution injected from the holes 21 on the top will to be directed towards the wall of the exhaust line at a position which is axially located much further downstream from the angle-bent part 18. Fig. 2 shows in broken lines when the angle-bent part 18 is maximally angled upwards when the injection takes place in the opposite way, and ureal solution will then be injected in the direction shown by dashed lines. Urea solution injected via the holes 21 on the underside is directed towards the position more downstream, while ureal solution which is injected via the holes on the upper side is directed towards the position closer to the angled part.
    The fixed pipes 17 or angled bent part 18 of the nozzle are preferably made of stainless steel or similar material in order to be able to withstand the hot and corrosive environment prevailing inside the exhaust line 3. The intermediate piece 20 is for the same reason made of suitable material which in addition to being able to withstand the hot and corrosive environment also allows a limited movement between the parts. The possibility of movement can be achieved by forming the intermediate piece 20 of a bellows of stainless material or by choosing a thinner material thickness than the connecting parts 17, 18. Fig. 2 shows as above how the end is allowed to move up and down between its outer positions in the plane shown. However, the resilient intermediate piece 17 allows movement of the angle-bent part 18 also laterally, with the consequence that what has been described above with regard to upward and downward movement applies in an analogous manner to lateral movements. During operation, the angle-bent part 18 will thus be able to move between its outer positions and also be able to assume all intermediate positions between them.
    Depending on the resilient movements allowed by the resilient intermediate piece, the injected urea solution will alternately be directed at different parts of the exhaust pipe wall. The same parts of the wall are thereby not subjected to continuous spraying nor to continuous cooling through the injected urea solution.
    The said movement of the angle-bent part 18 of the injector is effected primarily by the movements caused by vibrations during operation of the vehicle and engine, and which are transmitted via the exhaust line connection to the vehicle chassis and engine 1 to the portion 13 where the injector is attached. By analyzing which speeds for the motor are critical and which cause the greatest vibrations, the resilient intermediate piece 20 can be dimensioned so that a suitably large movement is obtained. It is alternatively possible during the operation of the vehicle and the engine to effect and / or intensify the resilient movement by varying the pressure of the injected urea solution, whereby different reaction forces acting on the angled part 18 produce different magnitude movements. Of course, material selection and dimensioning of the resilient adapter 20 also affects the amplitude and frequency of the resilient movement. According to the exemplary embodiment, the fixed tube 17 of the injector and the angle-bent part 18 are substantially rigid bodies which are connected to a resilient intermediate piece 20. Alternatively, substantially the entire angle-bent part 18 may itself be resilient and in such In the embodiment, the resilient intermediate piece 20 is not needed, since the desired movement is achieved in an analogous manner.
    Fig. 3 shows an alternative second design of a urea solution injector 30. In this case, the injector 30 is designed as a unit which is connected via a line 6 in the same manner as described above to a tank 4 containing an aqueous solution of urea.
    The injector 30 is attached to the wall of the exhaust line 3 without any part of it inserting into the exhaust line 3 or into the exhaust stream in the manner described with reference to the embodiments according to Fig. 1 above. In this case, only a small part of the nozzle 32 of the injector 30 is inserted into the exhaust line. In an alternative embodiment, no part of the nozzle 32 needs to be inserted into the exhaust stream. The nozzle 32 of the injector 3 in this case is designed with openings which cause the injection to be directed radially inwards and along the exhaust stream in the manner illustrated in Fig. 3 with a number of jets 33. For attaching the injector 3 to the exhaust line, this is provided with an injector circumferential fl end 34 which is fastened to the exhaust line 3 by means of a number of screw connections. Resilient washers 35 are arranged between the fl end 34 and the exhaust line in connection with the screw connections which entail that the entire injector 3 is allowed limited movement relative to the exhaust line 3. In addition, a seal (not shown) is arranged between the injector 30 and the exhaust line 3, which ensures that exhaust gases cannot flow out of the exhaust line.
    Because the attachment of the injector 30 is designed to be resilient in this way, the injection nozzle 32 arranged with the injector 30 will also be resiliently attached to the wall of the exhaust line 3. As a result, the injection of ureal solution will also in this case during operation of the engine take place so that its jets 33 are directed towards different positions in the exhaust stream towards different positions of its wall. In Fig. 3, only jets 33 are shown in a certain position by the injector 30, and in cases where the injector 30 has assumed a different position, the jets 33 will be directed towards other places in the exhaust line 3.
    Admittedly, the end 34 itself or some corresponding fastening means could in itself be made of a material which is itself resilient. But more suitably, the attachment itself is made resilient, for example by utilizing spring washers as indicated. Alternatively, the resilient attachment can be provided by using spiral springs in its attachment which in an analogous manner enable relative movement between the nozzle 32 and the exhaust line 3.
    Fig. 4 shows a further third alternative embodiment of the invention. The injector 30 is in this case of the same type as described above with reference to Fig. 3. The injector 30 is thus also in this embodiment provided with a shaft 34 for its attachment. But in this case the injector 34 of the injector fast is fixed to a holding plate 36 of resilient material. The resilient property of the holding plate 36 can be conveniently obtained by forming it in a relatively thin material and where its thickness makes it relatively folded, at least relatively surrounding wall of the exhaust line 3. The holding plate 36 is in turn attached to the exhaust line 3 in a recess, wherein the attachment of the holding plate 36 to both the injector 30 and the exhaust line 3 is designed completely tight so that no exhaust gases can flow out of the exhaust line 3.
    Fig. 5 shows a further alternative fourth embodiment of the invention. In this case the injector 30 is of the same type as described above with reference to Figs. 3 and Figs. 4. The difference is that in this case the end of the injector fl 34 is connected to an outside of the exhaust line 3 via a bellows 37, for example by sheet material, which in an analogous manner with previously described embodiments causes the injector 30 to have an attachment to the wall of the exhaust line 3 which allows it to move relative to the exhaust line 3. The bellows 37 is suitably fastened by means of welding joints, at least to the wall of the exhaust line 3 so that it also forms a seal between the injector 30 and the wall 3.
    The function of the described arrangement should have already been apparent to a significant extent. During engine operation, exhaust gases are led in the exhaust line 3 and, depending on various engine parameters, the exhaust gas solution is supplied via the injector 14, 30.
    The added urea solution is heated by the exhaust gases in the exhaust line 3 so that it evaporates and is converted to ammonia. The mixture of ammonia and the exhaust gases is then passed on in the exhaust line 3 to the catalyst 5. A chemical reaction takes place in the catalyst 5. The nitrogen of the nitrogen oxides in the exhaust gases reacts here with the nitrogen in the ammonia so that nitrogen gas is formed. The oxygen of the nitrogen oxides reacts with the hydrogen in the ammonia to form water. The nitrogen oxides in the exhaust gases are thus reduced in the catalyst 14 to nitrogen gas and water vapor, which is passed on in the exhaust gas line and finally out to the surrounding air. 10 15 20 25 30 It is assumed that the exhaust line is connected to the internal combustion engine in a manner known per se in such a way that vibrations caused by the combustion are propagated to the portion of the injector's attachment to the exhaust line. During the operation of the engine, the combustion will cause vibrations which via the exhaust line 3 are also propagated to the portion 13 for the attachment of the injector 14, 30. In case the engine consists of an engine in a vehicle, vibrations caused by the vehicle driving on a surface will also cause vibrations. which is also led to this area via the vehicle's wheel suspension, chassis, etc.
    Contrary to what is usually sought in this case, the injector 14, 30 or at least its nozzle 15, 32 will perform a vibrating movement caused by the vibrations supplied to the current portion 13. This results in the injection taking place more or less randomly and directed towards different areas in the exhaust line 3. The same area of the exhaust line will thus not be exposed to continuous cooling of injected urea solution. This improves the conditions for the injected urea solution to actually be dissolved by the exhaust gases. The preconditions for the formation of deposits of undissolved urea solution have in this way been substantially eliminated and the problems caused by such provisions have been significantly reduced and in some cases completely solved.
    In the above description, one type of injector 14 has been described with reference to Fig. 2 and another type of injector 30 has been described with reference to Figs. 3-5.
    It is obvious that the injector 14 as described with reference to Fig. 2 can in an analogous manner also use a fastening as described with reference to Figs. 3-5, and vice versa.
    The invention is not limited to the embodiments shown in the drawings, but it can be varied freely within the scope of the claims. The injector does not have to be designed in the manner shown in the drawings, but it can have a substantially arbitrary design and in addition the nozzle can have an arbitrary number of openings for injecting the urea solution into the exhaust line. Likewise, the injector does not have to be arranged on a tubular line such as an exhaust line, but it can be attached to another part of the exhaust line, for example to an end in a muffler or other component in the exhaust line.
    Some types of injectors are designed as valves that perform alternating opening and closing movements during injection. In these cases, the injection means performs a vibrating movement caused by these valve movements, which can be used to amplify the vibrations to which the nozzle is subjected during operation.
    The invention also comprises a method in which a device as described above is used to subject the injector nozzle to vibrations which cause the reactant injected from the nozzle to be directed towards different areas in the exhaust line.
    The method then comprises the step of utilizing vibrations attributable to the operation of the engine (1) to subject at least the nozzle (15, 32) of the injector to vibrations from the internal combustion engine (1) which cause the reactant injected from the nozzle (15, 32) to be directed towards different areas in the exhaust line (3).
    The method also includes that the combustion engine (1) is connected to the exhaust line (3) so that the injection means (14, 30) arranged in the exhaust line is exposed to vibrations caused by the operation of the combustion engine (1). The method also includes using pulsations from the injection to expose the injection nozzle for the vibrating movement.
    In the case where the engine constitutes the drive motor of a vehicle, the method is used to utilize vibrations attributable to the operation of the vehicle to subject the injection nozzle (15, 32) to the vibrating movement.
    权利要求:
    Claims (10)
    [1]
    An apparatus for injecting a reactant into an exhaust line of an internal combustion engine comprising an injector (14, 30) for injecting a desired amount of reactant into the exhaust line (3), and said injector being provided with a nozzle (l5,32 ) with an outlet from which the reactant can be injected into the exhaust line during the operation of the internal combustion engine, characterized by a resilient part (20, 35, 36, 37) arranged in connection with the injector's attachment to the exhaust line and which causes at least the injector nozzle (15, 32) is resiliently attached to the exhaust line (3) and which allows the nozzle (15, 32) to be allowed a limited movement relative to the exhaust line (3), and which during operation of the internal combustion engine (1) causes at least the injector nozzle (15, 32) to be exposed for vibrations from the internal combustion engine (1) whereby the reactant injected from the nozzle is directed towards different areas in the exhaust line (3).
    [2]
    Device according to claim 1, wherein the nozzle of the injection means consists of a nozzle inserting into the exhaust line, characterized in that the resilient part consists of a resilient intermediate piece (20) arranged between a fixed part (17) of the nozzle connected to the exhaust line (3) and a movable part (18) of the nozzle comprising the nozzle outlet (21).
    [3]
    Device according to claim 1, characterized in that the resilient part comprises a resilient part (35) arranged between the injector (30) and the exhaust line (3) and which resilient part is so weak that it allows the injector (30) to move relatively the exhaust line (3) during operation of the internal combustion engine.
    [4]
    Device according to claim 1, characterized in that the resilient part comprises a holding plate (36) to which the injector (30) is fixedly arranged and which holding plate (36) is fixedly arranged to the exhaust line and that the holding plate (36) has properties to be so bent that it allows the injector (30) to move relative to the exhaust line (3) during operation of the internal combustion engine. 10 15 20 25 30 35 12
    [5]
    Device according to claim 1, characterized in that the resilient part comprises a bellows (37) to which the injector (30) is fixedly arranged and which bellows (37) is fixedly arranged to the exhaust line (3) and that the bellows (37) has the property of being so weak that it allows the injector (30) to move relative to the exhaust line (3) during operation of the internal combustion engine.
    [6]
    Vehicle comprising as propulsion engine an internal combustion engine (1) provided with a device according to any one of the preceding claims, characterized in that the exhaust line (3) is arranged in the vehicle to be at least partially exposed to the forces to which the vehicle is subjected when driven on a substrate so that vibrations caused by the driving of the vehicle are also used to subject the injector nozzle (15, 32) to vibrations which cause the reactant injected from the nozzle (15, 32) to be directed towards different areas in the exhaust line (3).
    [7]
    A method of an internal combustion engine for injecting a reactant into an exhaust line (3), comprising an injecting means (14, 30) for injecting a desired amount of reactant and which injecting means (14, 30) is provided with a nozzle (15 , 32) with outlet from which the reactant is injected during the operation of the internal combustion engine, characterized by utilizing vibrations attributable to the operation of the engine (1) to subject at least the nozzle (15, 32) of the injection means to vibrations from the internal combustion engine (1) which cause the reactant injected from the nozzle (15, 32) is directed towards different areas in the exhaust line (3).
    [8]
    Method according to Claim 7, characterized in that the internal combustion engine (1) is connected to the exhaust line (3) so that the injection means (14, 30) arranged in the exhaust line is exposed to vibrations caused by the operation of the internal combustion engine (1).
    [9]
    Method according to claim 7, characterized by using pulsations from the injection to expose the injection nozzle to the vibrating movement.
    [10]
    Method according to claim 7 and wherein the engine constitutes a drive motor for a vehicle, characterized by utilizing vibrations attributable to the operation of the vehicle to subject the injection nozzle (15, 32) to the vibrating movement.
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    同族专利:
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    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    法律状态:
    2017-01-31| NUG| Patent has lapsed|
    优先权:
    申请号 | 申请日 | 专利标题
    SE0950404A|SE533951C2|2009-06-04|2009-06-04|Resilient device for injecting reactant into an exhaust pipe and method utilizing such device|SE0950404A| SE533951C2|2009-06-04|2009-06-04|Resilient device for injecting reactant into an exhaust pipe and method utilizing such device|
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