DE112022006302T5 - SCR MIXER AND MOTOR - Google Patents

Abstract

The present application relates to the technical field of engines and proposes an SCR mixer and an engine comprising a cylinder housing, a first flow guide means and a second flow guide means. A mixing chamber is formed in the interior of the cylinder housing, and the cylinder housing is provided with a nozzle seat bore for connecting a urea nozzle. The first flow guide means is connected to an opening at one end of the cylinder housing, wherein a conical first flow chamber is formed inside the first flow guide means, which communicates with the mixing chamber. The second flow guide means is connected to an opening at another end of the cylinder housing, wherein a conical second flow chamber is formed inside the second flow guide means, which communicates with the mixing chamber. The inner wall of the cylinder housing and the outer walls of the first and second flow guide means together form a meandering flow channel. Under the guiding action of the first flow guide means, the mixing chamber and the second flow guide means, the exhaust gases flow along a longer path through the actually limited mixing space, thereby ensuring that there is sufficient time for the urea droplets to completely mix with the exhaust gases, evaporate and decompose, which increases the homogeneity of the NH3 mixture and the crystallization resistance.

Description

cross-reference application

This application is based on the Chinese patent application with application number 202210010899 .X, filed on January 5, 2022, and claims priority thereto. The entire contents of this Chinese patent application are incorporated into this application by reference.

technical field

This application relates to the technical field of engines and in particular to an SCR mixer. This application also relates to an engine.

background technology

The content provided in this section is merely background information in connection with this disclosure and does not necessarily constitute prior art.

The function of the SCR (Selective Catalytic Reduction) mixer is to mix urea with exhaust gases to increase the conversion efficiency. However, the existing SCR mixers have limited mixing space and short mixing distance for urea and exhaust gases. This results in there being insufficient time for the urea to fully mix with the exhaust gases, making the distribution of _NH3 in the mixed gas uneven. This affects the reaction with the catalyst and ultimately leads to a reduction in the SCR conversion efficiency.

disclosure of the invention

• Ein erster Aspekt der vorliegenden Anmeldung stellt einen SCR-Mischer bereit, der Folgendes umfasst:
  • - ein Zylindergehäuse, dessen Innenraum eine Mischkammer bildet, wobei beide Enden des Zylindergehäuses offen sind und das Zylindergehäuse mit einer Düsensitzbohrung zur Verbindung einer Harnstoffdüse versehen ist;
  • - ein erstes Strömungsführungsmittel, das innerhalb des Zylindergehäuses angeordnet ist und mit einer Öffnung an einem Ende des Zylindergehäuses verbunden ist, wobei im Inneren des ersten Strömungsführungsmittels eine erste Strömungskammer gebildet ist, die konisch ist und mit der Mischkammer kommuniziert;
  • - ein zweites Strömungsführungsmittel, das innerhalb des Zylindergehäuses angeordnet ist und mit einer Öffnung am anderen Ende des Zylindergehäuses verbunden ist, wobei im Inneren des zweiten Strömungsführungsmittels eine zweite Strömungskammer gebildet ist, die konisch ist und mit der Mischkammer kommuniziert;
  • - wobei die Innenwand des Zylindergehäuses und die Außenwand des ersten Strömungsführungsmittels sowie die Außenwand des zweiten Strömungsführungsmittels gemeinsam umgrenzt einen mäanderförmigen Strömungsführungskanal bilden.

The object of the present application is to solve at least the problem of lower SCR conversion efficiency due to the poor mixing uniformity of the SCR mixer in the prior art. The object is solved by the following technical solutions:

• A first aspect of the present application provides an SCR mixer comprising:
  • - a cylinder housing, the interior of which forms a mixing chamber, both ends of the cylinder housing being open and the cylinder housing being provided with a nozzle seat bore for connecting a urea nozzle;
  • - a first flow guide means arranged within the cylinder housing and connected to an opening at one end of the cylinder housing, wherein a first flow chamber is formed inside the first flow guide means which is conical and communicates with the mixing chamber;
  • - a second flow guide means arranged within the cylinder housing and connected to an opening at the other end of the cylinder housing, wherein a second flow chamber is formed inside the second flow guide means which is conical and communicates with the mixing chamber;
  • - wherein the inner wall of the cylinder housing and the outer wall of the first flow guide means as well as the outer wall of the second flow guide means together form a meandering flow guide channel.

The SCR mixer proposed in the present application has a meandering flow guide channel. Under the guiding effect of the first flow guide means, the mixing chamber and the second flow guide means, the exhaust gases flow along a longer path through the actually limited mixing space. This ensures that there is enough time for the urea droplets to sufficiently mix with the exhaust gases, evaporate and decompose, thereby improving the homogeneity of the NH3 mixture and increasing the crystallization resistance of the aftertreatment system. This solves the problem of urea crystallization in the SCR aftertreatment system at low speeds and low load of the engine as well as the problem of unacceptably high NOX emissions.

In addition, the present application enables a modular design of the structure that is applicable to engines of different displacements. By appropriately adjusting the structure of the first and second flow guide means according to the exhaust aftertreatment specifications, a perfect match with the engine is achieved. No complex connection and assembly structure is required, which ensures high reliability.

• In einigen Ausführungsformen der vorliegenden Anmeldung umfasst der SCR-Mischer mindestens eine Harnstoffbrechplatte, die im Strömungsführungskanal angeordnet ist und der Sprühbahn der Harnstoffdüse gegenüberliegt.

Furthermore, the SCR mixer proposed according to the present application may have the following additional technical features:

• In some embodiments of the present application, the SCR mixer comprises at least one urea breaking plate arranged in the flow guide channel and opposite the spray path of the urea nozzle.

In some embodiments of the present application, a plurality of urea breaking plates are arranged along the spray path of the urea nozzle, wherein a part of the urea breaking plates is arranged at an angle to the axial direction of the cylinder housing, and another part of the urea breaking plates is arranged parallel to the axial direction of the cylinder housing.

In some embodiments of the present application, the length of the urea breaking plate in the axial direction of the cylinder housing is positively correlated with the distance of the urea breaking plate to the nozzle seat bore, and the urea breaking plates are arranged in a step-like manner in the radial direction of the cylinder housing.

In some embodiments of the present application, the first flow guide means is conical, wherein the larger end of the first flow guide means is connected to the opening at one end of the cylinder housing and the smaller end of the first flow guide means protrudes into the mixing chamber, the second flow guide means is conical, wherein the larger end of the second flow guide means is connected to the opening at the other end of the cylinder housing and the smaller end of the second flow guide means protrudes into the mixing chamber.

In some embodiments of the present application, the smaller end of the first flow guide means is arranged in the vicinity of the nozzle seat bore, the first flow guide means has a recess at a location corresponding to the nozzle seat bore, and the smaller end of the second flow guide means is arranged on the side of the mixing chamber facing away from the nozzle seat bore.

In some embodiments of the present application, the SCR mixer further comprises a third flow guide means and a fourth flow guide means arranged in the mixing chamber, wherein the third flow guide means is located between the cylinder housing and the second flow guide means and the fourth flow guide means is located between the first flow guide means and the second flow guide means.

In some embodiments of the present application, the flow guide channel is S-shaped.

In some embodiments of the present application, a bore for inserting a flow sensor is further provided on the first flow guide means.

A second aspect of the present application relates to an engine which has the same advantageous effects as the SCR mixer proposed in the first aspect of the present application, which is why this will not be further explained here.

Description of the drawings

• 1 zeigt schematisch eine Strukturansicht des SCR-Mischers gemäß einer Ausführungsform der vorliegenden Anmeldung;
• 2 zeigt schematisch eine Schnittstrukturansicht des SCR-Mischers gemäß einer Ausführungsform der vorliegenden Anmeldung;
• 3 zeigt schematisch eine Strukturansicht des ersten Strömungsführungsmittels gemäß einer Ausführungsform der vorliegenden Anmeldung aus einem ersten Blickwinkel;
• 4 zeigt schematisch eine Strukturansicht des ersten Strömungsführungsmittels gemäß einer Ausführungsform der vorliegenden Anmeldung aus einem zweiten Blickwinkel;
• 5 zeigt schematisch eine Strukturansicht des zweiten Strömungsführungsmittels gemäß einer Ausführungsform der vorliegenden Anmeldung;
• 6 zeigt schematisch eine Strukturansicht der Harnstoffbrechplatte gemäß einer Ausführungsform der vorliegenden Anmeldung aus einem ersten Blickwinkel;
• 7 zeigt schematisch eine Strukturansicht der Harnstoffbrechplatte gemäß einer Ausführungsform der vorliegenden Anmeldung aus einem zweiten Blickwinkel.

Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of the preferred embodiments. The drawings are for illustrative purposes only of the preferred embodiments and are not limitative of the present application. In addition, the same reference characters refer to the same parts throughout the drawings. In the drawings:

• 1 schematically shows a structural view of the SCR mixer according to an embodiment of the present application;
• 2 schematically shows a sectional structural view of the SCR mixer according to an embodiment of the present application;
• 3 schematically shows a structural view of the first flow guide means according to an embodiment of the present application from a first viewing angle;
• 4 schematically shows a structural view of the first flow guide means according to an embodiment of the present application from a second viewing angle;
• 5 schematically shows a structural view of the second flow guide means according to an embodiment of the present application;
• 6 schematically shows a structural view of the urea breaking plate according to an embodiment of the present application from a first viewing angle;
• 7 schematically shows a structural view of the urea breaking plate according to an embodiment of the present application from a second viewing angle.

• 10: Zylindergehäuse, 101: Düsensitzbohrung, 11: erstes Strömungsführungsmittel, 111: Bohrung zum Einsetzen eines Durchflusssensors, 112: Einsteckschlitz, 12: zweites Strömungsführungsmittel, 13: drittes Strömungsführungsmittel, 14: viertes Strömungsführungsmittel, 15: Harnstoffbrechplatte.

In the drawings, the reference symbols indicate the following:

• 10: cylinder housing, 101: nozzle seat bore, 11: first flow guide means, 111: bore for inserting a flow sensor, 112: insertion slot, 12: second flow guide means, 13: third flow guide means, 14: fourth flow guide means, 15: urea breaking plate.

Detailed embodiments

Hereinafter, exemplary embodiments of the disclosure will be described in more detail with reference to the accompanying drawings. Although exemplary embodiments of the disclosure are illustrated in the drawings, it should be understood that the disclosure may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to provide a more thorough understanding of the disclosure and to convey the full scope of the disclosure to those skilled in the art.

It should be understood that the terms used in the text are used only for the purpose of describing specific example embodiments and are not intended to be limiting. Unless the context expressly indicates otherwise, the singular terms used in the text such as "a," "an," and "the" can also include the plural form. The terms "comprising," "containing," "include," and "having" are inclusive and therefore indicate the presence of the specified features, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and/or combinations thereof. The method steps, processes, and operations described in the text should not be interpreted as requiring performance in the specific order described or illustrated, unless the order is expressly stated. It should further be understood that alternative or substitute steps may be used.

Although terms such as "first," "second," "third," etc. are used in the text to describe various elements, components, regions, layers, and/or sections, these elements, components, regions, layers, and/or sections should not be limited by these terms. These terms are used merely to distinguish one element, component, region, layer, or section from another region, layer, or section. Unless the context clearly indicates otherwise, terms such as "first," "second," and other numerical terms in the text do not imply any order or arrangement. Therefore, the elements, components, regions, layers, or sections discussed below may be referred to as a "second element," "second component," "second region," "second layer," or "second section" without departing from the teachings of the exemplary embodiments.

For ease of description, spatial relative terms may be used in the text to describe the relationship of an element or feature shown in the drawings relative to another element or feature. These spatial relative terms include, for example, "inside," "outside," "inboard," "side," "bottom," "below," "top," "above," etc. These spatial relative terms are intended to encompass orientations of the device in use or operation other than those shown in the drawings. For example, if the device shown in the drawings is turned over, the element described as being "below another element or feature" or "below another element or feature" would then be oriented as being "above another element or feature" or "above another element or feature." Accordingly, the exemplary terms "below" and "below" may include the positions "above" and "above." The device may also be oriented differently (e.g., rotated 90 degrees or in other directions), and the spatial relative terms used in the text should be interpreted accordingly.

• ein Zylindergehäuse 10, ein erstes Strömungsführungsmittel 11 und ein zweites Strömungsführungsmittel 12, wobei der Innenraum des Zylindergehäuses 10 eine Mischkammer bildet. Das Zylindergehäuse 10 ist mit einer Düsensitzbohrung 101 zur Verbindung einer Harnstoffdüse versehen und die beiden Enden des Zylindergehäuses 10 sind offen. Das erste Strömungsführungsmittel 11 ist im Inneren des Zylindergehäuses 10 angeordnet und mit einer Öffnung an einem der Enden des Zylindergehäuses 10 verbunden, wobei im Inneren des ersten Strömungsführungsmittels 11 eine konische erste Strömungskammer gebildet ist, die mit der Mischkammer in Verbindung steht. Das zweite Strömungsführungsmittel 12 ist im Inneren des Zylindergehäuses 10 angeordnet und mit dem anderen offenen Ende des Zylindergehäuses 10 verbunden, wobei im Inneren des zweiten Strömungsführungsmittels 12 eine konische zweite Strömungskammer gebildet ist, die mit der Mischkammer in Verbindung steht. Die Innenwand des Zylindergehäuses 10 und die Außenwände des ersten Strömungsführungsmittels 11 und des zweiten Strömungsführungsmittels 12 bilden gemeinsam umgrenzt einen mäanderförmigen Strömungsführungskanal.

As in the 1 to 7 As shown, the SCR mixer according to the first aspect of this application comprises:

• a cylinder housing 10, a first flow guide means 11 and a second flow guide means 12, the interior of the cylinder housing 10 forming a mixing chamber. The cylinder housing 10 is provided with a nozzle seat bore 101 for connecting a urea nozzle and the two ends of the cylinder housing 10 are open. The first flow guide means 11 is arranged inside the cylinder housing 10 and connected to an opening at one of the ends of the cylinder housing 10, a conical first flow chamber being formed inside the first flow guide means 11 and communicating with the mixing chamber. The second flow guide means 12 is arranged inside the cylinder housing 10 and connected to the other open end of the cylinder housing 10, a conical second flow chamber being formed inside the second flow guide means 12 and communicating with the mixing chamber. The inner wall of the cylinder housing 10 and the outer walls of the first flow guide means 11 and the second flow guide means 12 together form a meandering flow guide channel.

Note that the cylinder housing 10 may have a circular cylindrical structure or a cuboid structure, the cylinder housing being hollow inside. The first end of the cylinder housing 10 serves to receive the engine exhaust gases, and the second end of the cylinder housing 10 serves to discharge the mixed gas. The first flow guide means 11 and the second flow guide means 12 may be formed as funnel-shaped structures, which can be manufactured by sheet metal stamping, for easy formation of the conical flow chambers. The meandering flow guide channel may have an S-shape or Z-shape, etc., as long as a meandering path is formed in the limited space of the cylinder housing 10 by means of the first and second flow guide means 11 and 12. The outer edges of the first flow guide means 11 and the second flow guide means 12 are connected to the cylinder housing 10 by welding or snapping. The urea nozzle is mounted in the nozzle seat hole 101, and the exhaust gases coming from the engine enter the mixing chamber through the first flow guide means 11. Under the influence of the conical shape, the flow velocity of the exhaust gases gradually increases, thereby improving the flowability of the exhaust gases. With the urea injected, the exhaust gases and the urea mix in the mixing chamber and flow along the meandering flow guide channel, thereby lengthening the mixing path and sufficiently mixing the urea with the exhaust gases. Finally, the mixed gas exits from the second flow guide means 12.

The SCR mixer proposed in this application has a meandering flow channel through which the exhaust gases travel a longer path in the actually limited mixing space under the guiding effect of the first flow guiding means 11, the mixing chamber and the second flow guiding means 12. This ensures that there is enough time for the urea droplets to sufficiently mix with the exhaust gases, evaporate and decompose in order to increase the homogeneity of the NH3 mixture and the crystallization resistance of the aftertreatment system. This solves the problem of urea crystallization in the SCR aftertreatment system at low speeds and low engine loads as well as the problem of unacceptably high NOX emissions.

In addition, this application enables a modular design of the structure that is applicable to engines with different displacements. By appropriately adjusting the structure of the first flow guide means 11 and the second flow guide means 12 according to the exhaust aftertreatment specifications, a perfect match with the engine is achieved. No complicated connection and assembly structure is required, which increases reliability.

In some embodiments of this application, the SCR mixer comprises at least one urea breaking plate 15, which urea breaking plate 15 is arranged in the flow guide channel and is opposite the urea nozzle. The urea breaking plate 15 can be rectangular or round, but also have a star-shaped or irregular shape. Several through holes can be arranged in the urea breaking plate 15 in the form of a matrix in order to further crush the urea. The urea breaking plate 15 can be attached to the first flow guide means 11 or to the cylinder housing 10 by welding or snapping in, preferably the urea breaking plate 15 is inserted into an insertion slot 112 of the first flow guide means.

In some embodiments of this application, the SCR mixer is provided with a plurality of urea breaking plates 15 at intervals along the spray path of the urea nozzle, with a portion of the urea breaking plates 15 arranged at an angle to the axial direction of the cylinder housing 10 and another portion of the urea breaking plates 15 arranged parallel to the axial direction of the cylinder housing 10. The spray direction of the urea nozzle is generally perpendicular to the inflow direction of the exhaust gases. The urea breaking plates 15 arranged parallel to the axial direction of the cylinder housing 10 allow, on the one hand, the impinging urea to be crushed, thereby forming smaller droplets that mix better with the exhaust gases, and, on the other hand, they act as flow directors so that the inflowing exhaust gases are guided through the urea breaking plates 15, whereby the gas flow becomes more stable and faster. The urea breaking plates 15 arranged at an angle to the axial direction of the cylinder housing 10 allow a more diverse spray direction of the urea, which leads to a better mixing of the urea with the exhaust gases.

In some embodiments of this application, the length of the urea breaking plates 15 in the axial direction of the cylinder housing 10 correlates positively with the distance of the urea breaking plates 15 to the nozzle seat bore, and the urea breaking plates 15 are arranged in a step-like manner in the radial direction of the cylinder housing 10. The engine exhaust gases enter through the first flow guide means 11, the flow cross section of which decreases, whereby the flow velocity of the engine exhaust gases gradually increases and reaches its maximum at the outlet of the first flow guide means 11. value is reached. The urea solution is sprayed in the spray direction of the urea nozzle and hits the urea breaking plate 15 located underneath, with some of the drops bouncing off, being crushed, re-entering the exhaust gases and being carried forward by the hot exhaust gases; another part of the drops settles on the surface of the urea breaking plate 15, but is immediately blown away by the high-speed gases at the outlet of the first flow guide means 11 and re-entering the hot exhaust gases, which carry them forward.

In some embodiments of this application, the first flow guide means 11 is conical, with the larger end of the first flow guide means 11 being connected to an opening at one end of the cylinder housing 10 and the smaller end of the first flow guide means 11 protruding into the mixing chamber. The second flow guide means 12 is also conical, with the larger end of the second flow guide means 12 being connected to an opening at the other end of the cylinder housing 10 and the smaller end of the second flow guide means 12 protruding into the mixing chamber. Both flow guide means 11 and 12 are arranged inside the cylinder housing 10, which results in a compact overall structure of the mixer. The first flow guide means 11 and the second flow guide means 12 can be formed into conical structures by sheet metal stamping and connected to the cylinder housing 10 by welding or snapping. In addition, the inlet and outlet diameters of the flow guide means 11 and 12 can be adjusted to achieve perfect matching with the engine. No complicated connection and assembly structure is required, which increases reliability.

In some embodiments of this application, the smaller end of the first flow guide means 11 is arranged near the nozzle seat bore 101 and the first flow guide means 11 is provided with a recess at a location corresponding to the nozzle seat bore 101, while the smaller end of the second flow guide means 12 is arranged on the side of the mixing chamber facing away from the nozzle seat bore 101. The axial direction of the cylinder housing 10 is generally parallel to the horizontal, and the urea spray is sprayed into the mixing chamber from top to bottom. The outlet end, i.e. smaller end of the first flow guide means 11 is arranged near the urea nozzle so that the exhaust gas flow accelerated by the first flow guide means 11 is quickly mixed with the urea spray, which improves the homogeneity of the mixture. In addition, the second flow guide means 12 is arranged away from the urea nozzle, thereby extending the mixing distance and the mixing time of urea and exhaust gas, which further improves the homogeneity of the mixture.

In some embodiments of this application, the SCR mixer also comprises a third flow guide means 13 and a fourth flow guide means 14 arranged in the mixing chamber. The third flow guide means 13 is located between the cylinder housing 10 and the second flow guide means 12, while the fourth flow guide means 14 is arranged between the first flow guide means 11 and the second flow guide means 12. Since the first flow guide means 11 and the second flow guide means 12 are conical, flow dead zones can arise between them and the cylinder housing 10, in which the flow velocity decreases and urea can crystallize on the walls. The third flow guide means 13 is arranged between the cylinder housing 10 and the second flow guide means 12 so that the gas flow is deflected by the third flow guide means 13, thereby preventing the gas flow from entering dead zones. This increases the flow velocity and improves the homogeneity of the mixture of urea and exhaust gas. The third flow guide means 13 can be designed as a curved plate structure and connected to the cylinder housing 10 and the second flow guide means 12 by welding or snapping. The fourth flow guide means 14 has a similar function and structure to the third flow guide means 13, so it will not be described further here.

In some embodiments of this application, the flow channel is S-shaped or Z-shaped, formed and delimited by the inner wall of the cylinder housing 10 and the outer walls of the first flow guide means 11 and the second flow guide means 12. The outlet of the first flow guide means 11 is aligned with the urea nozzle, while the inlet of the second flow guide means 12 also extends to the position of the urea nozzle, so that the exhaust gases are first mixed with the urea spray when they exit the first flow guide means 11, before they flow further and are deflected by the third flow guide means 13. They then flow to the position between the first flow guide means 11 and the second flow guide means 12, are deflected again by the fourth flow guide means 14 and finally exit the second flow guide means 12. This meandering flow channel extends the flow path of the exhaust gases within the limited mixing chamber space, thereby extending the mixing time of exhaust gases and urea spray and thus improving the homogeneity of the mixture.

In some embodiments of this application, the first flow guide means 11 is provided with a bore 111 for inserting a flow sensor, which serves for inserting an SCR upstream temperature sensor. The SCR upstream temperature sensor can be electrically connected to the ECU in order to monitor the exhaust gas temperature upstream of the SCR (i.e. upstream of the mixer) and to control the injection timing of the urea.

The engine proposed in the second aspect of this application has the same advantages as the SCR mixer proposed in the first aspect of this application, which is why this is not further discussed here.

The embodiments described above merely represent preferred specific embodiments of this application, but the scope of this application is not limited thereto. Any changes or modifications that can be readily made by one skilled in the art within the scope of disclosure of this application also fall within the scope of this application. Therefore, the scope of this application should be determined by the scope of the claims.

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions.

Cited patent literature

• 202210010899 [0001]

Claims (10)

An SCR mixer, characterized in that it comprises: • a cylinder housing, the interior of which forms a mixing chamber, both ends of the cylinder housing being open and the cylinder housing being provided with a nozzle seat bore for connecting a urea nozzle; • a first flow guide means arranged inside the cylinder housing and connected to an opening at one end of the cylinder housing, wherein a first flow chamber is formed inside the first flow guide means, which is conical and communicates with the mixing chamber; • a second flow guide means arranged inside the cylinder housing and connected to an opening at the other end of the cylinder housing, wherein a second flow chamber is formed inside the second flow guide means, which is conical and communicates with the mixing chamber; • wherein the inner wall of the cylinder housing and the outer walls of the first flow guide means and the second flow guide means together form a meandering flow guide channel. SCR mixer after claim 1 , characterized in that the SCR mixer comprises at least one urea breaking plate which is arranged in the flow guide channel and opposite the urea nozzle. SCR mixer after claim 2 , characterized in that a plurality of urea breaking plates are arranged at intervals along the spray path of the urea nozzle, wherein a part of the urea breaking plates is arranged at an angle to the axial direction of the cylinder housing, and another part of the urea breaking plates is arranged parallel to the axial direction of the cylinder housing. SCR mixer after claim 3 , characterized in that the length of the urea breaking plates in the axial direction of the cylinder housing correlates positively with the distance of the urea breaking plates to the nozzle seat bore, and a plurality of the urea breaking plates are arranged in steps in the radial direction of the cylinder housing. SCR mixer after claim 1 , characterized in that the first flow guide means is conical, the larger end of the first flow guide means being connected to an opening at one end of the cylinder housing and the smaller end of the first flow guide means protruding into the mixing chamber, the second flow guide means is also conical, the larger end of the second flow guide means being connected to the opening at the other end of the cylinder housing and the smaller end of the second flow guide means protruding into the mixing chamber. SCR mixer after claim 5 , characterized in that the smaller end of the first flow guide means is arranged in the vicinity of the nozzle seat bore, the first flow guide means has a recess at a location corresponding to the nozzle seat bore, and the smaller end of the second flow guide means is arranged on the side of the mixing chamber facing away from the nozzle seat bore. SCR mixer after claim 1 , characterized in that the SCR mixer further comprises a third flow guide means and a fourth flow guide means arranged in the mixing chamber, the third flow guide means being located between the cylinder housing and the second flow guide means and the fourth flow guide means being located between the first flow guide means and the second flow guide means. SCR mixer after claim 1 , characterized in that the flow channel is S-shaped. SCR mixer according to one of the Claims 1 until 8 , characterized in that the first flow guide means also has a bore for inserting a flow sensor. An engine, characterized in that it comprises an SCR mixer according to one of the Claims 1 until 9 includes.

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