Heated injection nozzles and reducing agent metering systems for reducing agent preparation

Abstract

The present application relates to a heated injection nozzle and a reducing agent dosing system for the production of reducing agent. An injection nozzle (100) for injecting reducing agent into an exhaust gas stream of an internal combustion engine for selective catalytic reduction, the injection nozzle (100) comprising an outer nozzle housing (110), an inner body (160) arranged in the nozzle housing (110) and a nozzle head (130) with at least one outlet opening (140), the nozzle housing (110) having a reducing agent inlet (120), at least one flow channel (150) being formed between the nozzle housing (110) and the inner body (160) extending from the reducing agent inlet (120) to the nozzle head (130), the inner body (160) having at least one heating element or being formed as a heating element, the flow channel (150) being formed at least partially by a thread, in particular a single thread or a multi-thread, around the inner body (110) from the reducing agent inlet (120) to the nozzle head (130).

Description

[0001] The invention relates to an injection nozzle (Einspritzdüse) for injecting a reducing agent into an exhaust gas stream of an internal combustion engine for selective catalytic reduction, wherein the injection nozzle comprises an outer nozzle mantle (Düsenmantel), an inner body arranged in the nozzle mantle and a nozzle head having at least one outlet opening, wherein the nozzle mantle has a reducing agent inlet and at least one flow channel is formed between the nozzle mantle and the inner body which extends from the reducing agent inlet to the outlet opening, wherein the injection nozzle has at least one heating element.

[0002] Such a nozzle is known from the prior art. The disadvantage thereof is that the structure for heating the nozzle is complex and occupies a very large installation space. A further disadvantage of the known nozzle is that the intended effect of heating the nozzle in order to improve the efficiency of the selective catalytic reduction is not sufficient during the cold start phase of the internal combustion engine.

[0003] Furthermore, the invention also relates to a reducing agent dosing system (Reduktionsmitteldosiersystem) for injecting a reducing agent into an exhaust gas stream of an internal combustion engine for selective catalytic reduction, which has at least one delivery pump by means of which reducing agent from a reducing agent tank is drawn off from the tank via a suction line, is delivered via at least one pressure line and is introduced into the exhaust gas stream of the internal combustion engine via at least one injection nozzle.

[0004] Catalytic converters for selective catalytic reduction (English: selective catalytic reduction, abbreviation: SCR), so-called SCR catalytic converters, are used to reduce nitrogen oxide emissions from diesel engines, combustion plants, waste incineration plants, industrial plants and the like. For this purpose, a dosing device is used to inject a reducing agent into the exhaust gas system. Ammonia or ammonia solutions or other reducing agents are used as reducing agents.

[0005] Since the carriage of ammonia in vehicles is of great importance for safety reasons, in particular according to DIN 70070, aqueous urea solutions with a urea content of usually 32.5% are used. When the temperature exceeds 150 degrees Celsius, the urea in the exhaust gas decomposes into gaseous ammonia and CO2. The parameters of the urea decomposition are mainly time (vaporization time and reaction time), temperature and the droplet size of the injected urea solution. In these SCR catalytic converters, the emission of nitrogen oxides is reduced by approximately 90% by selective catalytic reduction.

[0006] The term reducing agent solution or reducing agent includes any reducing agent suitable for selective catalytic reduction, here preferably a urea solution according to DIN 70070 is used. However, the invention is not limited thereto. The term reducing agent dosing system or dosing system is used synonymously in the invention. The terms nozzle and injection nozzle are also used synonymously.

[0007] In known reducing agent metering systems for injecting reducing agent into the exhaust gas flow of an internal combustion engine for selective catalytic reduction, relatively low exhaust gas temperatures, for example during a cold start of the internal combustion engine, i.e. before the operating temperature of the internal combustion engine is reached, can have a negative impact on the function of the SCR catalyst.

[0008] After the urea-water solution is injected into the exhaust gas duct, ammonia (NH3) must first be formed for the SCR reaction to proceed. Here, the reduced ammonia is released by the thermal decomposition (thermolysis) of urea and the hydrolysis of the generated isocyanic acid.

[0009] In the first reaction, thermolysis, urea is converted into ammonia (NH3) and isocyanic acid (HNCO) under the influence of temperature. In the second step, hydrolysis occurs in the presence of water, where isocyanic acid is also converted into ammonia with the formation of carbon dioxide (CO2). Relatively low temperatures, such as those encountered during a cold start of an internal combustion engine, slow the progression of these reactions.

[0010] The object of the present invention is therefore to further develop an injection nozzle for a reducing agent metering system in such a way that the function of the SCR catalytic converter is improved, in particular at low temperatures, such as occur during a cold start of an internal combustion engine, i.e., in particular before the operating temperature of the internal combustion engine is reached.

[0011] This object is achieved according to the invention by an injection nozzle according to claim 1 and a reducing agent metering system according to claim 14. Advantageous developments of the invention are specified in the dependent claims.

[0012] In an injection nozzle for injecting a reducing agent into the exhaust gas flow of an internal combustion engine for selective catalytic reduction, the injection nozzle comprises an outer nozzle housing, an inner body arranged in the nozzle housing, and a nozzle head having at least one outlet opening, wherein the nozzle housing has a reducing agent inlet and at least one flow channel extending from the reducing agent inlet to the nozzle head is formed between the nozzle housing and the inner body, wherein the injection nozzle has at least one heating element, it is particularly advantageous here that the flow channel is at least partially formed by a thread, in particular a single-start thread or a multi-start thread, around the inner body from the reducing agent inlet to the nozzle head.

[0013] Arranging the heating element enables the reducing agent to be heated while it is being conveyed through the heated nozzle inside the nozzle. In addition, a compact design is achieved thereby, as further heating elements can be omitted.

[0014] Here, the flow channel is at least partially formed by a single-start thread or a multi-start thread around the inner body from the reducing agent inlet to the nozzle head.

[0015] The core of the present invention lies in the fact that by designing a flow channel in the nozzle, in the form of a single-thread or multi-threaded thread around the inner body, from the reducing agent inlet to the nozzle tip, the travel distance from the reducing agent inlet to the nozzle tip of the nozzle is extended. This also extends the flow duration from the reducing agent inlet to the nozzle tip with the outlet opening. This increased residence time of the reducing agent in the nozzle further increases the degree of heating of the reducing agent. In particular, depending on the set heating power, partial or complete evaporation of the reducing agent can be achieved. The transition of the reducing agent from the liquid to the gaseous phase results in considerable expansion and volume increase. The formation of vapor bubbles in the reducing agent and the associated volume increase accelerate the reducing agent and cause it to be blown out through the outlet opening in the nozzle tip into the exhaust gas flow of the internal combustion engine. This blowing, caused by the generated vapor bubbles, results in a particularly fine distribution of the reducing agent in the exhaust gas flow, which in turn significantly improves the quality of the selective catalytic reduction, particularly during the cold start phase of the internal combustion engine.

[0016] This achieves a significant reduction in nitrogen oxides at low temperatures or during cold starts of the internal combustion engine. This is achieved in particular by preheating the reducing agent, in particular a urea solution, and introducing the conversion products with the highest possible steam content into the exhaust tract of the internal combustion engine.

[0017] According to the present invention, the flow passage is formed in the form of one or more threaded passages extending around the inner body. In particular, the threaded passage may have a trapezoidal cross-section. By forming the flow channel in the form of one or more threaded passages from the reducing agent inlet to the outlet opening, the stroke length from the reducing agent inlet to the nozzle head having the outlet opening is significantly increased, thereby significantly increasing the flow duration from the reducing agent inlet to the nozzle head having the outlet opening.

[0018] Here, segments with different thread pitches can be interconnected in the axial direction of the nozzle. In particular, the flow channel can be formed by alternating right-handed and left-handed thread segments, thereby forming a serpentine line along the nozzle in the axial direction of the nozzle. The term serpentine line here includes any shape other than a straight line, which has abrupt or curved changes in direction that result in an increase in the length of the flow channel from the reducing agent inlet to the nozzle tip.

[0019] However, it is particularly advantageous in terms of production technology and fluid technology if the flow channel is formed by a single-start thread or a multi-start thread with a constant pitch from the reducing agent inlet to the nozzle head.

[0020] The heating element can be used to heat the reducing agent until it evaporates. This improves the aerosol formation and spray quality of the reducing agent, particularly by reducing the reducing agent droplet size when injected into the exhaust gas flow of an internal combustion engine. The significantly smaller reducing agent droplets can significantly improve the catalytic effect of the SCR catalyst, particularly at relatively low exhaust gas temperatures, in particular below approximately 200°C, such as those prevailing during cold starts of internal combustion engines, because the injected reducing agent evaporates more quickly due to the smaller droplets.

[0021] In particular, the reducing agent can be heated to a temperature level above the instantaneous exhaust gas temperature. This is achieved by means of a heating element, via which thermal energy is supplied. Furthermore, a control or regulation of the heating power can be provided. This allows the reducing agent to be heated to a desired and / or predeterminable temperature level. In particular, the water content can be evaporated in the heated nozzles and the urea solution can be converted.

[0022] Furthermore, the start or continued thermal decomposition of urea can be achieved already in the nozzle. By guiding the reducing agent through the flow channel, it is heated well and evenly. This allows for optimal utilization of the evaporation process, thereby increasing the volume of conversion products discharged through the nozzle head and subsequently mixed with the exhaust gas. Furthermore, a fine spray of reducing agent components that have not yet evaporated and chemically converted can be provided. This ensures a defined distribution of reducing agent conversion products into the exhaust tract. This results in the desired rapid conversion of the reducing agent in the exhaust tract, as well as the aforementioned advantages of accelerated nitrogen oxide reduction at low temperatures and during cold engine starts.

[0023] Another advantage is that while the reducing agent is being heated, there is no direct contact between the reducing agent and the heating element. By routing the reducing agent through the flow channel, only a low backpressure is generated within the metering system during metering. Furthermore, positioning the nozzle close to the engine, in the exhaust duct of the internal combustion engine, allows for optimal utilization of the exhaust gas temperature. This minimizes the energy required to heat the nozzle.

[0024] Furthermore, thanks to the heating element, any internal deposits can also be self-cleaned by significantly increasing the temperature. This cleaning can be performed in particular if the back pressure is too high, which indicates deposits. A pressure sensor can be arranged to detect the back pressure.

[0025] Furthermore, since the heating function is already integrated into the nozzle, this arrangement allows for simple integration into the overall design of the reducing agent metering system. The injection nozzle has a compact design and extremely low mass, eliminating the need for complex support structures in the exhaust duct.

[0026] In particular, the heating element can be electrically actuated. Preferably, the nozzle housing has a top plate at its end opposite the nozzle head having the outlet opening, through which the electrical connections for the heating element are routed. In particular, the connections can be sealed relative to the outer body. The top plate can be constructed in one piece or in multiple pieces with the nozzle housing.

[0027] Furthermore, the reducing agent can be atomized using compressed air or fuel gas. Atomization can occur inside or outside the injection nozzle. To this end, the injection nozzle, in particular the nozzle housing, can have a compressed air connection for introducing compressed air into the nozzle. In particular, the reducing agent inlet can have a valve, in particular a pressure valve and / or a check valve. However, due to partial evaporation of the reducing agent, this is not absolutely necessary, as the reducing agent is already expelled by the generated vapor bubbles.

[0028] Preferably, the nozzle housing and the inner body are arranged concentrically with respect to one another. In particular, the nozzle housing can be designed cylindrically and / or the inner body can be designed cylindrically.

[0029] In a preferred embodiment, the inner body has at least one heating element or is designed as a heating element; in particular, the heating element or the inner body itself can be designed as a heating cartridge.

[0030] The inner body has at least one heating element or is configured as a heating element, in which way heating occurs inside the nozzle, minimizing heat loss to the nozzle surroundings. In addition, the nozzle housing can also have other means for thermal isolation from the surroundings.

[0031] Preferably, the heating element or the inner body itself is designed as a heating cartridge. The heating cartridge generally comprises an outer shell, preferably made of a particularly cylindrical metal body, in particular of stainless steel. This ensures a high degree of corrosion protection. Preferably, a heating coil is located inside the heating cartridge, wound around a core, in particular a core made of ceramic. The space between the outer shell and the core is preferably filled with magnesium oxide and then preferably compressed according to the required heating power. Such a heating cartridge can be easily installed in the nozzle and is chemically and mechanically robust.

[0032] Alternatively or additionally, the heater can be arranged in the form of a heating coil surrounding the nozzle housing. The nozzle is heated by the heating coil wound around the nozzle housing and heat is transferred to the reducing agent transported in the flow channel.

[0033] Preferably, the heating element is formed by a resistance heater. Here, it is particularly advantageous that the duration of the heating and the heating power can be precisely controlled via the control device and / or regulated in a closed control loop.

[0034] The injection nozzle particularly preferably has at least one temperature sensor. The temperature sensor is preferably arranged upstream within the nozzle, in thermal contact with the reducing agent directly in front of the outlet opening, to detect the temperature of the reducing agent. In particular, the heating power of the heating element can be regulated by the control device in a closed control loop based on the temperature signal from the sensor to set the desired temperature of the reducing agent directly in front of the outlet opening.

[0035] In particular, the temperature sensor can be integrated into the nozzle head and / or arranged at the end of the flow channel directly in front of the nozzle head.

[0036] In a preferred embodiment, the flow channel is formed by a single-start thread or a multi-start thread on the outer side of the inner body and / or on the outer side of a sleeve arranged concentrically with the inner body.

[0037] Therefore, the flow channel may be an additional component or the inner body itself, on the outer side of which a single-start thread or a multi-start thread is arranged to form the flow channel from the reducing agent inlet to the nozzle head.

[0038] Alternatively or additionally, the flow channel is formed by a single-thread or multi-thread internal thread on the inside of the nozzle housing. Here, if the nozzle housing is a multi-piece design, it can be an additional component in the form of a sleeve, or if the nozzle housing is a one-piece design, it can be the nozzle housing itself.

[0039] In this case, the threaded passage forms a flow channel from the reducing agent inlet to the nozzle tip, which flow channel is wound around the inner body in the form of a thread.

[0040] Thus, the flow channel can function via an external thread on the inner body or on a sleeve surrounding the inner body, and / or via an internal thread on the inner side of the nozzle housing or of the sleeve inserted into the nozzle housing. In particular, the flow channel can be formed by both external and internal threads. In this case, the thread paths of the external and internal threads can overlap or differ in their course, in particular in the thread pitch.

[0041] Preferably, the flow channel is formed by a plurality of segments of a serpentine and / or a plurality of straight segments which are connected to one another in the axial extension of the inner body and / or by a helix which extends around the inner body. Thus, the flow channel can be formed by a plurality of different segments which are connected to one another in the axial direction of the inner body. For example, straight segments can be arranged for the purpose of making the manufacture of the nozzle simpler and cheaper, for example, as long as it is not necessary to arrange a flow channel in the form of one or more helical channels over the entire axial extension of the inner body in order to achieve the desired temperature level of the reducing agent at the outlet opening of the nozzle head. The axial direction of the inner body refers to the extension of the inner body from the end opposite the nozzle head to the nozzle head. Here, as already set out, the serpentine can be formed by right-handed and left-handed helical segments which follow one another in a repeating sequence.

[0042] Preferably, the flow channel is formed by a plurality of helical channels which have one or more short-circuit connections to one another.

[0043] Preferably, the flow channel is formed by a plurality of segments of a helix which extend around the inner body and which are connected to one another in the axial extension of the inner body with different thread pitches.

[0044] By means of such short-circuit connections and / or segments with different thread pitches, it is possible to determine the desired length of travel and thus the desired duration of the flow through from the reducing agent inlet to the nozzle head, given a predefined mass flow of the reducing agent.

[0045] Preferably, a heat conductor is arranged between the inner body and the sleeve which forms the flow channel on the outside thereof. Here, the term that the flow channel is formed on the outside of the sleeve encompasses both embodiments in which an external thread is introduced into the sleeve and embodiments in which an internal thread is introduced on the inside of a nozzle housing which surrounds the sleeve, wherein the nozzle housing can be embodied in one piece or in multiple pieces. The arrangement of the heat conductor between the inner body and the sleeve serves to transfer heat to the reducing agent which is conveyed in the flow channel, in particular when the inner body has a heating element or the inner body itself is configured as a heating cartridge.

[0046] In a preferred embodiment, the flow channel has at least in sections a coating, wherein the coating has at least one hydrolysis catalyst, in particular Ti02and / or Si02and / or Zr02and / or has a corrosion protection, in particular Al203and / or FeCrAl.

[0047] Preferably, the flow channel has at least in sections a coating, wherein the coating comprises an inorganic oxide, in particular an inorganic oxide with a carrier material Nb205and / or Ta205and / or W03and / or an aluminosilicate and / or a zeolite.

[0048] In particular, the inner wall of the nozzle housing and / or the outer wall of the inner body can be coated by means of a coating. Here, the inner body can be coated with a first type of coating, while the nozzle housing can be coated with another or similar coating. The coating can contribute to corrosion protection and / or promote the desired reaction of the reducing agent.

[0049] Thus, in particular, the coating can be a so-called hydrolysis coating, that is to say, the flow channel is at least partially provided with a coating, wherein the coating has at least one hydrolysis catalyst. The term hydrolysis coating refers to a coating having at least one component (e.g. Ti02) which promotes the hydrolysis of the reducing agent. Thereby, the hydrolysis temperature can be reduced, so that an increase in the ammonia conversion rate can be achieved and thus the amount of fixed decomposition products can be reduced.

[0050] In particular, the coating can have components such as aluminium oxide Al203and / or FeCrAl, which serve for corrosion protection.

[0051] In particular, the coating can have Ti02and / or Al203and / or H-zeolite, in particular H-mordenite and / or H-ZSM5, and / or Si02and / or Zr02. In the case of a mixture of the coating with Ti02and / or H-zeolite and / or Si02and / or Zr02, the proportion of aluminium oxide to the other compounds can be 9:1 to 1 :9, in particular 8:2 or 7:3 or 6:4 or 5:5 or 4:5 or 3:7 or 2:8. In particular, the coating can have fine-grained inorganic oxides, in particular Nb205and / or Ta205and / or W03, and / or aluminium silicate and / or H-zeolite. In particular, the coating can have FeCrAl, in particular as an alloy.

[0052] Preferably, the nozzle head consists of a nozzle cone and a nozzle cap, wherein the nozzle cap has at least one outlet opening. In particular, the nozzle housing can partially or completely surround the nozzle head.

[0053] Preferably, the nozzle head has at least one reducing agent outlet, in particular the nozzle head can be configured to taper conically towards the reducing agent outlet. In particular, the nozzle head can have a plurality of reducing agent outlets.

[0054] Preferably, the nozzle head and / or the inner body are connected to the nozzle housing directly or indirectly in a material-fit manner and / or in a force-fit manner and / or in a form-fit manner. In particular, the nozzle head and / or the inner body can be reversibly mounted on the nozzle housing, in particular in a force-fit manner and / or in a form-fit manner. In this way, the nozzle head and / or the inner body can be removed, so that maintenance of the injection nozzle, in particular cleaning and / or replacement of individual elements, can be carried out during its service life.

[0055] The nozzle housing preferably has a compressed air chamber and a compressed air inlet leading to the compressed air chamber. In particular, the compressed air chamber can form a heat shield that at least partially thermally isolates the reducing agent nozzle. To this end, the compressed air chamber can at least partially or completely surround the inner body. In particular, the compressed air chamber can be connected indirectly or directly to the reducing agent outlet of the nozzle head. This allows the reducing agent to be atomized using compressed air.

[0056] Alternatively or additionally, the nozzle head can have at least one compressed air outlet, wherein the flow channel conducting the reducing agent opens indirectly or directly into the reducing agent outlet, and the compressed air chamber opens indirectly or directly into the compressed air outlet. In this way, the nozzle can be configured as an external-mix two-substance nozzle. In particular, the reducing agent outlet and the compressed air outlet can be arranged concentrically. In particular, the compressed air outlet can at least partially or completely surround the reducing agent outlet. Alternatively, the reducing agent outlet can at least partially or completely surround the compressed air outlet. Thus, in such an external-mix two-substance nozzle, the mixture of urea solution and compressed air is formed outside the nozzle.

[0057] Alternatively or additionally, the mixture can be formed inside the nozzle. Thus, an internal mixing nozzle can also be realized. In such an internal mixing nozzle, the compressed air outlet opens into the flow channel that guides the reducing agent.

[0058] Furthermore, the nozzle can also be designed in such a way that the preparation of the mixture outside the nozzle and inside the nozzle are combined.

[0059] In a reducing agent metering system for injecting reducing agent into the exhaust gas flow of an internal combustion engine for selective catalytic reduction, the reducing agent metering system has at least one delivery pump, with the help of which the reducing agent in a reducing agent tank is sucked out of the tank via a suction line, delivered via at least one pressure line, and introduced into the exhaust gas flow of the internal combustion engine via at least one nozzle. It is particularly advantageous that the at least one nozzle is formed by the injection nozzle according to the present invention.

[0060] The terms reducing agent metering system or metering system are used synonymously in the present invention. The terms reducing agent solution or reducing agent include any reducing agent suitable for performing selective catalytic reduction, for which purpose urea solutions according to DIN 70070 are preferably used. However, the present invention is not limited thereto.

[0061] The injection nozzle with integrated heating element achieves a compact and easy-to-install overall design of the reducing agent metering system.

[0062] The widely used reducing agent solution according to DIN 70070 coagulates at approximately -11 °C due to its water content. Therefore, advantageously, in the case of very low ambient temperatures, heating devices are provided within the metering system in order to heat the reducing agent solution. Such heating devices can be arranged in addition to the heating elements, in particular within the tank.

[0063] Preferably, the reducing agent metering system has a control device by means of which the heating elements of the delivery pump and / or of the injection nozzle are controlled, in particular regulated in a closed control loop as a function of the operating state.

[0064] In particular, the heating elements of the delivery pump and / or of the injection nozzle can be supplied with electrical energy by means of the control device. Preferably, the regulation of the heating elements of the delivery pump and / or of the injection nozzle takes place as a function of the operating state, i.e. in particular as a function of the exhaust gas temperature and / or of the reducing agent temperature at the nozzle head, which can be determined by means of a temperature sensor in the injection nozzle.

[0065] In particular, the metering system can have a compressed air supply, and the reducing agent is atomized by means of compressed air, in particular inside the nozzle and / or outside the nozzle. BRIEF DESCRIPTION OF DRAWINGS

[0066] Embodiments of the application are shown in the drawings, which will be explained in the following. Therein:

[0067] Figure 1 A schematic diagram of a reducing agent metering system is shown;

[0068] Figure 2 A sectional view of an injection nozzle of a reducing agent metering system according to Figure 1 is shown;

[0069] Figure 3 A view of a flow channel of an injection nozzle according to Figure 2 is shown.

[0070] The same components are denoted by the same reference signs. Figure 1A schematic diagram of a reducing agent metering system 10 for injecting reducing agent into the exhaust duct 80 of an internal combustion engine 70 for selective catalytic reduction is shown. Reducing agent is drawn from a reducing agent tank 30 via a suction line 40 by a delivery pump 20 and delivered to an injection nozzle 100 via a pressure line 50. The reducing agent is introduced into the exhaust duct 80 of the internal combustion engine 70 via the injection nozzle 100. A catalyst for selective catalytic reduction, a so-called SCR catalyst 90, is connected downstream of the reducing agent introduction point in the exhaust duct 80 of the internal combustion engine. The metering system 10 is controlled by a control unit 60, which communicates with the metering system 10 via a data and control line 61 and with the internal combustion engine 70 via another data and control line 62. Both operating states and sensor signals, as well as control signals, are transmitted via the data and control lines 61 and 62. In both cases, the transmission is bidirectional, as indicated by the double arrows 61 and 62.

[0071] Figure 2 The cross-sectional view shows the Figure 1 The injection nozzle 100 has a nozzle housing 110 and an inner body 160 arranged in the nozzle housing 100. The nozzle housing has a reducing agent inlet 120. The pressure line 50 from the delivery pump 20 is connected to the reducing agent inlet 120. Figure 2 At its lower end, the injection nozzle 100 has a nozzle head 130 formed by a nozzle cone 135 and a nozzle cap 136. An outlet opening 140 is located in the nozzle cap 136, through which the reducing agent is introduced from the nozzle 100 into the exhaust gas duct of the internal combustion engine. Furthermore, the injection nozzle 100 has a temperature sensor 190.

[0072] The cylindrical inner body 160 is configured as a heating element. The inner body has electrical connections 180 at its end opposite the nozzle head 130, which are used on the one hand to Figure 1 The control device 60 shown in FIG. 1 controls the heating element and supplies electrical energy to the heating element. In addition, the electrical connection is also used to transmit the sensor signal of the temperature sensor 190 to the control device 60.

[0073] Inner body 160 is configured as a heating element in the form of a heating cartridge. Inner body 160 is mounted on nozzle housing 110 via a top plate, with electrical connection wires 180 routed through the top plate. Both nozzle housing 110 and inner body 160 are cylindrical and concentrically arranged.

[0074] The sleeve 150 made of heat conductive material is concentrically arranged between the nozzle housing 110 and the inner body 160, and a heat conductive material such as a heat conductive material is introduced outside the sleeve 150. Figure 3 The six-thread external thread ( The threaded passage in the sleeve 150 forms a flow channel 155 for the reducing agent and connects the reducing agent inlet 120 to the nozzle head 130 .

[0075] By changing the thread pitch, the desired stroke length of the flow channel 155 from the reductant inlet 120 to the nozzle head 130 can be determined. Therefore, by defining the desired stroke length of the flow channel 155, the residence time of the reductant in the nozzle 100 is also determined given the mass flow rate of the delivery pump 20.

[0076] A heat exchanger 170 is arranged between the inner body 160 and the sleeve 150 concentric with the inner body 160. The heat exchanger 170 is used to transfer heat from the inner body 160, which is configured as a heating cylinder, to the sleeve 150, and thus to the reducing agent flowing in the flow channel 155. The heat exchanger 170 is made of a heat-conductive material and thus has good thermal conductivity.

[0077] By configuring the inner body 160 as a heating cartridge, the reducing agent delivered through the nozzle 100 can be heated and at least partially evaporated in a compact structure while being delivered to the interior of the nozzle 100 .

[0078] The injection nozzle 100 can improve the performance of an SCR catalyst by using heated and partially evaporated reductant. Such a nozzle also contributes to a compact and easily installable design of the reductant metering system 10, as the heating element is integrated into the nozzle 100 and the flow channel 155 formed in the nozzle 100 enables heating and evaporation of the reductant by extending the travel length from the reductant inlet 120 to the nozzle tip 130. The flow channel 155, formed in the form of multiple threaded passages extending around the inner body 160, increases the residence time of the delivered reductant in the nozzle 100 to a point where the reductant can be heated and, if necessary, evaporated. This improves the quality of nitrogen oxide reduction within the SCR catalyst, particularly during the cold start phase of the internal combustion engine 70.

Claims

1. An injection nozzle (100) for injecting a reducing agent into an exhaust gas flow of an internal combustion engine (70) for selective catalytic reduction, wherein the injection nozzle (100) comprises an outer nozzle housing (110), an inner body (160) arranged in the nozzle housing (110), and a nozzle head (130) having at least one outlet opening (140), wherein the nozzle housing (110) has a reducing agent inlet (120), and at least one flow channel (155) is formed between the nozzle housing (110) and the inner body (160) and extends from the reducing agent inlet (120) to the nozzle head (130), wherein the injection nozzle (100) has at least one heating element, It is characterized in that The flow channel (155) is at least partially formed by a thread, in particular a single-thread thread or a multi-thread thread, around the inner body (160) from the reducing agent inlet (120) to the nozzle head (130), and the flow channel (155) is formed by a plurality of segments of thread lines with different thread pitches connected to each other in the axial extension direction of the inner body (160), and the thread lines extend around the inner body (160).

2. The injection nozzle (100) according to claim 1, characterized in that The inner body (160) has at least one heating element or is configured as a heating element, in particular, the heating element or the inner body (160) itself is configured as a heating cartridge.

3. The injection nozzle (100) according to claim 1, characterized in that The heating element is formed by a resistive heater.

4. The injection nozzle (100) according to claim 1, characterized in that The injection nozzle (100) has at least one temperature sensor (190).

5. The injection nozzle (100) according to claim 1, characterized in that The flow channel (155) is formed by a single-start thread or a multi-start thread on the outer side of the inner body (160) and / or on the outer side of a sleeve (150) arranged concentrically with the inner body (160).

6. The injection nozzle (100) according to claim 1, characterized in that The flow passage (155) is formed by a single-start internal thread or a multi-start internal thread on the inner side of the nozzle housing (110).

7. The injection nozzle (100) according to any one of claims 1 to 6, characterized in that The flow channel (155) is formed by a plurality of threaded passages having one or more short-circuit connections between each other.

8. The injection nozzle (100) according to any one of claims 1 to 6, characterized in that A heat conductor (170) is arranged between the inner body (160) and the sleeve (150) forming the flow channel (155) on the outer side thereof.

9. The injection nozzle (100) according to any one of claims 1 to 6, characterized in that The flow channel (155) is at least partially coated, wherein the coating comprises at least one hydrolysis catalyst, in particular TiO2 and / or SiO2 and / or ZrO2 and / or a corrosion protector, in particular Al2O3 and / or FeCrAl.

10. The injection nozzle (100) according to any one of claims 1 to 6, characterized in that The flow channel (155) is at least partially coated, wherein the coating comprises an inorganic oxide, in particular an inorganic oxide having the support material Nb2O5 and / or Ta2O5 and / or WO3 and / or an aluminosilicate and / or a zeolite.

11. The injection nozzle (100) according to any one of claims 1 to 6, characterized in that The nozzle head (130) consists of a nozzle cone (135) and a nozzle cap (136), wherein the nozzle cap (136) has at least one outlet opening (140).

12. A reducing agent metering system (10) for injecting reducing agent into the exhaust gas flow of an internal combustion engine (70) for performing selective catalytic reduction, the reducing agent metering system comprising at least one delivery pump (20), by means of which the reducing agent in a reducing agent tank (30) is sucked out of the reducing agent tank (30) via a suction line (40), delivered via at least one pressure line (50), and introduced into the exhaust gas flow of the internal combustion engine (70) via at least one nozzle. It is characterized in that The at least one nozzle is formed by an injection nozzle (100) according to any one of claims 1-11.

13. The reducing agent metering system (10) according to claim 12, characterized in that The reducing agent metering system (10) has a control device (60) by means of which a delivery pump (20) and / or a heating element of the injection nozzle are controlled, in particular in a closed control loop, depending on the operating state.

14. A method for operating a reducing agent metering system (10) for injecting reducing agent into the exhaust gas flow of an internal combustion engine (70) for selective catalytic reduction, the reducing agent metering system comprising at least one delivery pump (20), by means of which the reducing agent in a reducing agent tank (30) is sucked out of the reducing agent tank (30) via a suction line (40), delivered via at least one pressure line (50), and introduced into the exhaust gas flow of the internal combustion engine (70) via at least one injection nozzle (100), wherein the injection nozzle The nozzle (100) comprises an outer nozzle housing (110), an inner body (160) arranged in the nozzle housing (110), and a nozzle head (130) having at least one outlet opening (140), wherein the nozzle housing (110) has a reducing agent inlet (120), and at least one flow channel (155) extending from the reducing agent inlet (120) to the nozzle head (130) is formed between the nozzle housing (110) and the inner body (160), wherein the injection nozzle (100) has at least one heating element, It is characterized in that The flow channel (155) is at least partially formed by a thread, in particular a single-thread or multi-thread thread, around the inner body (160) from the reducing agent inlet (120) to the nozzle head (130), the flow channel (155) being formed by a plurality of segments of thread lines with different thread pitches connected to each other in the axial extension direction of the inner body (160), the thread lines extending around the inner body (160), and the reducing agent delivered through the injection nozzle (100) is heated and at least partially evaporated while being delivered to the interior of the injection nozzle (100).

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