DE102020129001B4 - Exhaust system with exhaust gas turbocharger, ejector and exhaust gas catalytic converter - Google Patents

Abstract

Exhaust system (1) of an internal combustion engine, comprising an exhaust gas turbocharger (2), at least one bypass line (3) and an ejector (4), comprising an ejector inflow area (8) which is immediately downstream of the turbine outlet (5) and a conically tapering area pipeline section, a mixing section (9) which has a largely constant pipeline diameter and a diffuser area (10) which forms a conically enlarging pipeline section, with at least one exhaust gas catalytic converter (11, 12) is arranged. A first exhaust gas catalytic converter (11) is arranged inside the ejector inflow area (8) and/or a second exhaust gas catalytic converter (12) inside the diffuser area (10), the catalyst support materials of the two exhaust gas catalytic converters (11, 12) being different. The catalyst carrier material of the first exhaust gas catalytic converter (11) forms a multi-way exhaust gas catalytic converter and that of the second exhaust gas catalytic converter (12) forms a particle filter. At least one exhaust gas catalytic converter (11, 12), which is arranged within a conical pipe section of the ejector (4), has a conical shape.

Description

technical field

The present invention relates to a device for treating the exhaust gas of an internal combustion engine, in particular the combination of an exhaust gas turbocharger, an ejector and at least one exhaust gas catalytic converter.

State of the art

Exhaust gas turbochargers of supercharged internal combustion engines can be controlled by means of a bypass. The bypass can be designed as a bypass line, with the inlet of the bypass line being arranged upstream of the inlet and its outlet being arranged downstream of the outlet of the exhaust gas turbocharger. By completely or partially opening or closing the bypass line, the proportion of the exhaust gas mass flow can be adjusted, which is routed via the turbine wheel of the exhaust gas turbocharger. The proportion of the exhaust gas mass flow that flows through the bypass line, or the bypass flow, has a higher enthalpy than the proportion of the exhaust gas mass flow that flows via the turbine wheel, or the turbine flow, due to the energy conversion to the turbine. There is therefore an enthalpy difference between the bypass flow and the turbine flow downstream of the turbine. If the bypass line is routed into a common exhaust gas discharge line downstream of the turbine, into which the outlet of the turbine also flows, and if the outlet of the bypass line is arranged in the common exhaust gas discharge line in the immediate vicinity of the turbine outlet, a jet pump is created in this way, with the bypass flow as a Driving jet and the turbine flow is designed as a suction jet. The jet pump creates a pressure reduction at the turbine outlet and thus increases the pressure drop across the turbine, which contributes to an increase in turbine power output.

In the disclosure document DE3048933A1 discloses a control valve for an exhaust gas turbocharger, the control valve being arranged within the bypass line and comprising a conical nozzle body which completely or partially opens or closes the outlet of the bypass line into the common exhaust gas discharge line. The outlet of the bypass line is arranged largely in the middle and coaxially to the further course of the exhaust gas discharge line, so that the outlet of the bypass line forms the driving jet and the outlet of the turbine forms the suction jet of a jet pump. The exhaust gas discharge line arranged downstream of the nozzle body also includes a mixing section and a diffuser, so that the entire arrangement forms an ejector.

In the disclosure document DE102018129130A1 such a turbine control device is disclosed, with a ring catalytic converter being arranged around the mixing section and the diffuser in order to save installation space and to place the exhaust gas catalytic converter close to the internal combustion engine.

The efficiency advantages of such an ejector design with regard to the turbine output power of an exhaust gas turbocharger are offset by the disadvantages of a possible exhaust gas aftertreatment of such an arrangement. For functional reasons, the use of a named ejector requires installation space for the ejector inflow area, the mixing section and for a diffuser area, which means that downstream exhaust gas catalytic converters must be positioned at a greater distance from the internal combustion engine. This circumstance is in conflict with the legal requirements regarding exhaust gas emissions from internal combustion engines, particularly in the motor vehicle sector, whereby, on the one hand, due to the relative proximity to the internal combustion engine, its waste heat is utilized and, on the other hand, due to a relatively short distance of the exhaust gas to an exhaust gas catalyst, a shortened light-off time should be reached.

In order to meet this requirement, in addition to the arrangement of exhaust gas catalytic converters in a ring design, there are also existing in the prior art DE102018129130A1 further approaches, in which in particular the structural design of the catalyst support is adapted. Through the disclosures JP H03- 169 348 A , KR2019970040536U , DE10224436A1 , DE102012220172A1 such as US20140178260A1 Catalyst carriers with a conical design are known in order to achieve a homogeneous distribution of the exhaust gas mass flow on the catalyst carrier material, an extended utilization of the installation space in pipe transitions between the catalyst jacket and its inlet and outlet and an improvement in the light-off temperature.

From the disclosure documents JP S61-4 813 A and US20080190081A1 , as well as from the patent specification DE102016002517B3 Monoliths of particulate filters are known in at least partially conical design, whereby the conical structure, in combination with adapted flow channels, the structural mechanical load on the monolith, a reduction in shear forces caused by the exhaust gas mass flow, and improved exhaust gas aftertreatment, achieved through changed flow conditions should be. The approaches mentioned include devices that are conventionally arranged in the usual sequence of exhaust gas discharges, i.e. downstream of the exhaust gas turbocharger, so that the additional use of an ejector mentioned still has the disadvantages of remote positioning of exhaust gas aftertreatment devices.

Furthermore, from the utility model specification DE 295 15 054 U1 an exhaust gas catalytic converter with secondary air intake according to the Venturi principle is known, with exhaust gas passing at least one catalytic surface before and after the Venturi nozzle and the negative pressure resulting from the exhaust gas flow being used to introduce air into the exhaust gas flow.

object of the invention

The present invention is now based on the object of providing an exhaust system which comprises at least one exhaust gas catalytic converter and reflects the advantages of the ejector design with regard to improving the efficiency of the exhaust gas turbocharger and at the same time ensures a short light-off time for said exhaust gas catalytic converter.

solution of the task

The object is achieved by an exhaust system according to claim 1, characterized in that at least one exhaust gas catalytic converter is arranged within at least one conical pipe section of the ejector. Further embodiments result from the dependent subclaims.

Presentation of the invention

• 1 die Strömungsverhältnisse einer aus dem Stand der Technik bekannten Abgasanlage mit Abgasturbolader und Ejektor,
• 2 eine erfindungsgemäße Abgasanlage mit Abgasturbolader, Ejektor sowie zwei integrierten Abgaskatalysatoren.

The intention of the invention is to utilize the installation space around an internal combustion engine that is additionally required by the use of an ejector downstream of an exhaust gas turbocharger, with at least one exhaust gas catalytic converter being integrated into the exhaust gas system according to the invention. By arranging an exhaust gas catalytic converter within the ejector, the catalytic converter support material is advantageously arranged closer to the internal combustion engine, so that it can effectively utilize the waste heat of the exhaust gas mass flow generated during operation of the internal combustion engine. Due to the small pipe diameter of the ejector exhaust pipe, in order to implement the principle of the jet pump, the exhaust gas catalytic converter is also of smaller dimensions than conventional main catalytic converters and can be used as a pre-catalytic converter. Due to the small dimensions of the pre-catalyst, the catalyst support material according to the invention advantageously reaches the light-off temperature more quickly, even when the internal combustion engine is operated under partial load. If a flow-optimized structure is added to the catalyst support material, for example by means of directed flow channels, the flow through the ejector can be rectified, which has a positive effect on the mode of operation of the jet pump. By using the exhaust system according to the invention with exhaust gas catalysts integrated in an ejector, the efficiency of the internal combustion engine is effectively increased and at the same time the emitted exhaust gas emissions are effectively reduced. For a better understanding and to support the description, reference is made to the following illustrations. Here show:

• 1 the flow conditions of an exhaust system known from the prior art with exhaust gas turbocharger and ejector,
• 2 an exhaust system according to the invention with exhaust gas turbocharger, ejector and two integrated exhaust gas catalysts.

Referring to 1 comprises an exhaust system (1) known from the prior art, an exhaust gas turbocharger (2) and an ejector (4) which is arranged downstream of the turbine outlet (5) of the exhaust gas turbocharger (2). The outlet of a bypass line (3) is arranged coaxially to the ejector (4) and the turbine outlet (5), which leads the bypass flow to the exhaust gas turbocharger (2). The bypass line (3) can begin at any position upstream of the exhaust gas turbocharger (2), so that a conventional bypass is represented in this way. The bypass flow can be controlled via a valve (6). To improve the flow conditions of the jet pump, the outlet of the bypass line (3) can be designed as a nozzle unit, comprising a nozzle (7) and a valve (6) matched to the outer shape of the nozzle (7). The valve (6) can be set up to fully or partially open or close the nozzle (7).

The function of such an ejector (4) now arises when the valve (6) is fully or partially open, with a portion of the exhaust gas mass flow of the internal combustion engine being routed as a bypass flow through the bypass line (3) and this by passing through the nozzle (7) leaves in the direction of the ejector (4). At the same time, another portion of the exhaust gas mass flow is routed via at least one turbine of the exhaust gas turbocharger (2) and leaves the turbine outlet (5) as a turbine flow. Due to the work done by the turbine flow at the turbine, this shows a lower enthalpy than the bypass flow (narrow flow arrows). Due to the resulting enthalpy difference, the bypass flow is higher fluid pressure than the turbine flow (bold flow arrows). The resulting negative pressure at the turbine outlet can increase the efficiency of the exhaust gas turbocharger (2) and thus of the entire internal combustion engine.

The ejector (4) arranged downstream of the turbine outlet (5) increases the effect of the jet pump, whereby it can be divided into an inflow area (8), a mixing section (9) and a diffuser area (10). The inflow area (8) is designed as a tapering, conical pipe section. Within the inflow area (8), the driving jet (bypass flow) is fed to the suction jet (turbine flow). The tapered frusto-conical shape further increases the fluid pressure within the tubing and enhances the effectiveness of the jet pump. Downstream of the inflow area (8) follows the mixing section (9), which has a largely constant pipe diameter. Within the mixing section (9), the motive and suction jets are mixed and swirled (circled flow arrows). Both jets mix in the mixing section (9) until an exhaust gas mass flow that is largely homogeneous in terms of enthalpy, flow rate and fluid pressure prevails. Due to this requirement, a defined minimum length expansion is required for the mixing section (9) due to its function. In internal combustion engines for passenger cars, the length of the entire ejector (4) can be up to 500 mm. The exhaust gas mass flow, which is now homogeneous, is then expanded in the diffuser area (10) and fed into the other pipe sections of the exhaust gas discharge line.

The previous description of the structure and functioning of a known exhaust system (1) is not intended to define the invention described below or to limit the design of its embodiments, rather it serves to convey a general understanding of the structure and functioning of a known exhaust system (1), whereby the advantageous Operation of the exhaust system according to the invention (1) described below is illustrated.

Referring to 2 an exhaust gas system (1) mentioned and described is expanded in an advantageous manner by at least one exhaust gas catalytic converter (11, 12). The additional exhaust gas catalytic converters (11, 12) are arranged within the pipe sections of the ejector (4), in particular the inflow area (8) and/or the diffuser area (10). By arranging the exhaust gas catalytic converters (11, 12) within the ejector (4), the installation space blocked by this is to be used in an advantageous manner. Due to the functionally required minimum longitudinal dimensions of the ejector (4) according to the invention, exhaust gas aftertreatment systems can only be arranged at an increased distance from the internal combustion engine, which entails the disadvantages described in the prior art. The arrangement of exhaust gas catalytic converters (11, 12) within the ejector according to the invention reduces the distance between them and the exhaust gas turbocharger (2) and the internal combustion engine, so that exhaust gases which flow through them have a higher temperature in an advantageous manner, and the exhaust gas catalytic converters (11 , 12) are better heated even by the waste heat of the internal combustion engine. Due to the lower geometric dimensions of the exhaust gas catalysts (11, 12) additionally arranged according to the invention in relation to conventional exhaust gas catalysts, caused by the tapering, truncated cone shape and the small diameter of the pipe sections of the ejector (4), they reach their light-off temperature in a less time. This is particularly advantageous because in the motor vehicle sector, internal combustion engines, especially in partial load operation and due to the advanced combustion process, generate ever lower exhaust gas temperatures, so that the complete conversion of the pollutant fractions is made considerably more difficult.

In one embodiment, a first exhaust gas catalytic converter (11) is arranged inside the inflow area (8) and/or a second exhaust gas catalytic converter (12) inside the diffuser area (10) of the ejector (4). The two exhaust gas catalytic converters (11, 12) are preferably arranged within the conical pipe sections of the ejector (4). Depending on the function, the pipe section of the mixing section (9) should be free of flow obstacles so that the motive and suction jets can be mixed effectively. At the same time, the conversion of the pollutants in the exhaust gas mass flow increases if the remaining available space within the ejector (4) is fully utilised.

In an advantageous embodiment, the entry surface of the first exhaust gas catalytic converter (11) starts immediately at the start of the inflow area (8) of the ejector (4) or immediately after the nozzle (7), the outlet of the bypass line (3) or the turbine outlet (5). The exact beginning of the entry area of the first exhaust gas catalytic converter (11) can depend on the physical design of the connection between the exhaust gas turbocharger (2) and the ejector (4) and on the geometric design of the nozzle (7), outlet of the bypass line (3) and turbine outlet (5). The type and design of the connection between the exhaust gas turbocharger (2) and the ejector (4) is not the subject of the invention and can any embodiment known in the art or any other embodiment. Accordingly, the length of the first exhaust gas catalytic converter (11) preferably ends with its exit surface at the end of the conical narrowing of the inflow area (8), i.e. the transition to the mixing section (9), so that this does not have a negative impact on the shape of the first exhaust gas catalytic converter (11) in terms of flow technology being affected. In accordance with the requirements mentioned, the second exhaust gas catalytic converter (12) preferably begins with its entry surface directly at the end of the mixing section (9) or in the transition from this to the conical shape of the diffuser area (10) and ends with its exit surface at the physical end of the ejector (4) or at the end of the conical shape of the diffuser area (10). Alternatively, the two exhaust gas catalytic converters (11, 12) can have any start and end position of their entry and exit surfaces if this is necessary, for example, due to space-related conditions or can have a favorable effect on the flow conditions within the ejector (4).

The first exhaust gas catalytic converter (11) comprises a first and the second exhaust gas catalytic converter (12) comprises a second catalytic converter support material. In a preferred embodiment, the catalyst support materials of the two exhaust gas catalysts (11, 12) are different. In this way, the catalyst support materials can advantageously be flexibly adapted to the respective areas of the ejector (4) or to different applications of the internal combustion engine. In one embodiment, a catalyst carrier material comprises properties of a three-way catalyst known from the prior art and a further catalyst carrier material comprises properties of the functioning of known particle filters. The composition of the catalyst support materials is not the subject of the invention, rather it should be made clear that a catalyst support material, which has the properties of a three-way catalytic converter, is to be understood within the meaning of the invention as a catalyst support material which acts as an oxygen store and thus the exhaust gas emission components nitrogen oxides ( NOx), carbon monoxide (CO) and hydrocarbons (HC) or can affect their ratio to each other in the exhaust gas mass flow in a known manner. At the same time, a catalyst support material that has the properties of a particle filter is generally to be understood as a catalyst support material that can capture and store soot particles from the exhaust emissions. According to the invention, a reduction in pollutants and in soot particles emitted by the internal combustion engine in the exhaust gas mass flow can advantageously already take place within the ejector.

In one embodiment, the catalyst support material of at least one exhaust gas catalyst (11, 12) has a conical shape. In a preferred embodiment, the shape of at least one catalyst support material and thus the shape of the associated exhaust gas catalysts (11, 12) follow the course of the inside diameter of the conical pipe sections of the ejector (4) in which they are arranged. The radial dimensions of the exhaust gas catalytic converters (11, 12) thus preferably largely correspond to the inner diameter of the pipe sections of the ejector (4) at the respective axial position. Due to the conical shape of the catalyst carrier materials or the exhaust gas catalysts (11, 12) themselves, the pipe volume of the inflow area (8) and diffuser area (10) is optimally utilized in order to achieve the most effective possible conversion of the pollutants in the exhaust gas.

In an advantageous embodiment, flow channels are formed by the structure of the catalyst support materials, which follow the outer shape of the exhaust gas catalysts (11, 12) with respect to the longitudinal alignment. For the purposes of the invention, this means that the flow channels are not aligned parallel to the axial alignment of the exhaust gas catalytic converters (11, 12). Rather, the flow channels that are formed follow the conical shape of the exhaust gas catalytic converters (11, 12), so that due to the geometric properties of the truncated cone of the conical pipe sections of the ejector (4), flow ducts that are at a large radial distance from the central axis of the truncated cone, which is aligned in the longitudinal direction, have a larger angle form between that center axis and its own center axis than those flow channels that have a smaller radial distance to said center axis of the truncated cone. In this way, the flow conditions of the exhaust gas mass flow within the ejector (4) are advantageously influenced, with the flow channels of the catalyst support materials rectifying the flow of the exhaust gas in the direction of the shape of the truncated cones. For a first exhaust gas catalytic converter (11), which is arranged in the inflow area (8) of the ejector (4), the driving and suction jets of the jet pump are first linearized and rectified by the shape of the flow channels in the direction of the mixing section, which affects the mode of operation of the nozzle (7) further strengthened and can thus have a positive influence on the efficiency of the jet pump. For a second exhaust gas catalytic converter (12), which is arranged in the diffuser area (10) of the ejector (4), the exhaust gas mass flow homogenized by the mixing section (9) is distributed evenly over the entry surface of the catalyst support material and leaves the outlet tread surface of the catalyst support material is correspondingly uniform, so that any subsequent further devices for exhaust gas aftertreatment can develop an improved effect.

In an advantageous embodiment, flow channels are formed by the structure of the catalyst support materials, which follow the external shape of the exhaust gas catalysts (11, 12) with regard to the cross-sectional area. For the purposes of the invention, this means that the cross-sectional area of the flow channels of the catalyst support material of the first exhaust gas catalytic converter (11) essentially narrows in the flow direction and/or the cross-sectional area of the flow channels of the structure of the catalyst support material of the second exhaust gas catalytic converter (12) essentially increases in the flow direction . In this way, the stated mode of action of the directed flow channels is further enhanced. In an alternative embodiment, the cross-sectional areas of the individual flow channels are different at the same position with respect to the longitudinal orientation. In this way, the flow conditions within the exhaust gas catalytic converters (11, 12) can be further influenced. For example, the flow channels of the first exhaust gas catalytic converter (11), which are arranged near the longitudinal axis of the ejector (4), can have smaller cross-sectional areas at the inlet of the catalyst support material than those that are closer to the inner wall of the pipeline of the ejector (4), so that due to the different flow cross-sectional areas, the fluid pressure of the driving jet is further increased compared to the fluid pressure of the suction jet, as a result of which the mode of operation of the jet pump can be further improved. Alternatively, each individual flow channel can have a cross-sectional profile that is the same as or different from at least one other flow channel of the catalyst support material, in order in this way to influence flow conditions of the exhaust gas mass flow, in particular for targeted pressure increase or relaxation. Corresponding characteristics of the structure of the catalyst support material can be made for the second exhaust gas catalyst (12).

exemplary embodiments

• 3 die Strömungsverhältnisse in einer Abgasanlage (1) mit einem ersten Abgaskatalysator (11) im Einströmbereich (8) des Ejektors (4),
• 4 die Strömungsverhältnisse in einer Abgasanlage (1) mit einem zweiten Abgaskatalysator (12) im Diffusorbereich (10),
• 5 die Strömungsverhältnisse in einer Abgasanlage (1) mit zwei integrierten Abgaskatalysatoren (11, 12).

Exemplary embodiments of the described embodiments are shown below. These serve to illustrate the principle, the exhaust system (1) according to the invention not being limited by the exemplary embodiments shown. Further special features and advantages result from the supporting diagrams, which show:

• 3 the flow conditions in an exhaust system (1) with a first exhaust gas catalytic converter (11) in the inflow area (8) of the ejector (4),
• 4 the flow conditions in an exhaust system (1) with a second exhaust gas catalytic converter (12) in the diffuser area (10),
• 5 the flow conditions in an exhaust system (1) with two integrated exhaust gas catalytic converters (11, 12).

In 3 a first exhaust gas catalytic converter (11) is arranged within the inflow area (8) of the ejector (4), this starting with its entry surface at a small distance immediately downstream of the nozzle (7) of the outlet of the bypass line (3) and at a small distance immediately ends before the beginning of the mixing section (9). The entry surface of the first exhaust gas catalytic converter (11) should preferably be placed in the immediate vicinity of the nozzle (7), so that the propulsion and suction jets do not already mix significantly upstream of said entry surface. The bypass flow (thick flow arrows) flows out of the nozzle (7) with increased enthalpy and fluid pressure compared to the turbine flow (thin flow arrows) and meets the flow channels of the catalyst support material, which are located in radial proximity to the central axis of the ejector and are therefore still largely coaxial or parallel to the mentioned axis run. The turbine flow is fed to the ejector in radial proximity to the inner diameter of the pipelines of the turbine outlet (5) and the inflow area (8) of the ejector (4) and accordingly meets the flow channels of the catalyst support material, which are located at a greater radial distance from the central axis of the ejector.

In an advantageous embodiment, the cross-sectional area of the flow channels close to the center, through which the bypass flow flows as a driving jet, is larger than that of the flow channels farther away from the center, through which the turbine flow is guided as a suction jet. In this way, the driving jet is confronted with proportionally fewer flow obstacles and is linearized and rectified by the flow channels, which are largely parallel to the central axis, whereby the nozzle effect of the nozzle (7) is continued. Correspondingly, the suction jet is confronted with proportionately more flow obstacles than the propulsion jet, as a result of which the enthalpy of the propulsion jet is further reduced. Accordingly, such an arrangement advantageously contributes to an increase in the enthalpy difference between the propulsion jet and the suction jet, with pollutant emissions being reduced in the entire exhaust gas mass flow at the same time.

Following the exit surface of the first exhaust gas catalytic converter (11), the motive and suction jets are combined, with the exhaust gas mass flow being largely homogenized in the manner mentioned in terms of enthalpy, flow velocity and fluid pressure, expanded through the diffuser area (10) and fed into the further exhaust gas discharge line becomes. The sole arrangement of a first exhaust gas catalytic converter (11) in the inflow area (8) of the ejector (4) is particularly advantageous when the increase in the ejector effect and thus the efficiency of the exhaust gas turbocharger (2) and the internal combustion engine compared to the properties of a second exhaust gas catalytic converter (12 ) are given higher priority or if further installation space is to be saved, with the diffuser area (10) being designed with correspondingly small dimensions, so that the arrangement of a further exhaust gas catalytic converter (12) carries the risk of an unfavorable cost-benefit ratio.

In 4 a second exhaust gas catalytic converter (12) is arranged individually within the diffuser area (10) of the ejector (4), this beginning with its entry surface at a small distance immediately after the end of the mixing section (9) and at a small distance immediately before the end of the Diffuser area (10) ends. A single exhaust gas catalytic converter (12), which is arranged in the diffuser area (10) of the ejector (4), is particularly advantageous if the pollutant-reducing effect of the second exhaust gas catalytic converter (12) is prioritized over the increased ejector effect. If the second exhaust gas catalytic converter (12) is designed as a particle filter, it represents a flow obstacle due to the known structure of the catalytic converter support material and its functional principles and is not suitable for continuing the function of a nozzle (7) or a jet pump. Accordingly, this is then arranged in the diffuser area (10), with the inflow area (8) and the mixing section (9) being able to be reduced in their longitudinal dimensions, so that the effectiveness of the ejector is reduced, but is still present, as well as the second exhaust gas catalytic converter ( 12) can effectively reduce the proportion of soot particles from the exhaust gas mass flow. The arrangement of a second exhaust gas catalytic converter (12) configured as a particle filter within the diffuser area (10) of the ejector (4) is particularly advantageous because the exhaust gas mass flow, which has been largely homogenized by the mode of operation of the mixing section (9), evenly hits the reduced entry cross-sectional area, caused by the inverse frusto-conical shape of the catalyst support material when viewed in the direction of flow. This effect can be further intensified if the entry cross-sectional areas of the flow channels of the catalyst support material are of the same size and evenly distributed, based on the entry cross-sectional area. Advantageously according to the invention, the cross-sectional courses of the flow channels can correlate with the pipe diameter of the diffuser area (10), which progressively increases in the direction of flow, and also expand in equal parts, so that the homogenized exhaust gas mass flow expands evenly and is correspondingly distributed over the largest possible proportion of the surface of the catalyst support material in order to avoid soot particles to reduce effectively.

In 5 is a combination of the embodiments of FIG 3 and 4 shown, wherein a first exhaust gas catalytic converter (11) is arranged within the inflow area (8) of the ejector (4), this starting with its entry surface at a small distance immediately downstream of the nozzle (7) of the outlet of the bypass line (3) and with a ends a short distance immediately before the start of the mixing section (9) and a second exhaust gas catalytic converter (12) is arranged within the diffuser area (10) of the ejector (4), with its entry surface at a short distance immediately after the end of the mixing section (9 ) and ends a short distance immediately before the end of the diffuser area (10). This combined arrangement combines the advantages of the two individual arrangements mentioned. Although both exhaust gas catalytic converters (11, 12) in themselves represent flow obstacles, which can have a negative impact on the ejector's mode of operation as such, the most important pollutants and soot particles are, in particular due to the design of different catalyst carrier materials, in addition to improving the efficiency of the exhaust gas turbocharger (2nd ) and the internal combustion engine.

Viewed as a whole, the device according to the invention also provides a modular application, the efficiency of the exhaust gas turbocharger (2) being increased by the mode of operation of the ejector (4), the pollutants nitrogen oxides (NOx) being reduced by the use of a first exhaust gas catalytic converter (11) as a multi-way catalytic converter, Carbon monoxide (CO) and hydrocarbons (HC) can be reduced and the soot particles in the exhaust gas mass flow can be reduced by using a second exhaust gas catalytic converter (12) as a particle filter. Depending on the prioritization, the relationship between these modes of action can be adjusted. If the focus is on efficiency advantages and the reduction of pollutants, the volume of the second exhaust gas catalytic converter (12) can be reduced. If the focus is on reducing soot particles and improving efficiency, the volume of the first exhaust gas catalytic converter (11) can be reduced the. An additional configuration of the flow channels of the catalyst support materials, in the manner mentioned, further increases the possible combinations, so that an application-specific adaptation of the device according to the invention can take place in an advantageous manner.

Reference List

1

exhaust system

2

exhaust gas turbocharger

3

bypass line

4

ejector

5

turbine exit

6

Valve

7

jet

8th

ejector inflow area

9

mixing section

10

diffuser area

11

first catalytic converter

12

second catalytic converter

Claims (7)

Exhaust system (1) comprising an exhaust gas turbocharger (2), at least one bypass line (3), an ejector (4) and at least one exhaust gas catalytic converter (11, 12), the bypass line (3) ending downstream of the exhaust gas turbocharger (2) and the ejector ( 4) downstream of the exhaust gas turbocharger (2) immediately adjacent to a turbine outlet (5) and the outlet of the bypass line (3) is arranged inside and coaxially with the turbine outlet (5), the outlet of the bypass line (3) being closable by a valve (6). is characterized in that the ejector (4) has an ejector inflow area (8), which is immediately downstream of the turbine outlet (5) and forms a conically tapering pipeline section, a mixing section (9) which has a largely constant pipeline diameter, and a diffuser area (10), which forms a conically enlarging pipeline section, wherein at least one exhaust gas catalytic converter (11, 12) is arranged within at least one conical pipeline section. Exhaust system (1) after claim 1 , characterized in that a first exhaust gas catalytic converter (11) is arranged inside the ejector inflow area (8) and/or a second exhaust gas catalytic converter (12) inside the diffuser area (10) in the conical pipe sections of the ejector (4), the catalytic converter support materials of the two Exhaust catalysts (11, 12) are different. Exhaust system (1) after claim 2 , characterized in that the catalyst support material of the first exhaust gas catalytic converter (11) forms a multi-way exhaust gas catalytic converter and that the catalyst support material of the second exhaust gas catalytic converter (12) forms a particle filter. Exhaust system (1) according to one of the preceding claims, characterized in that the catalyst carrier material of at least one exhaust gas catalyst (11, 12) which is arranged within a conical pipe section of the ejector (4) has a conical shape. Exhaust system (1) according to one of claims 2 , 3 or 4 , characterized in that flow channels are formed by the structure of the catalyst support materials of the exhaust gas catalysts (11, 12), the alignment of the flow channels following the shape of the conical pipe sections of the ejector (4), in which the exhaust gas catalysts (11, 12) are arranged, so that the longitudinal axis of flow channels that have a larger radial distance to the longitudinal axis of the ejector (4) form a larger angle between their longitudinal axis and that of the ejector (4) than those longitudinal axes of flow channels that have a smaller radial distance to the longitudinal axis of the ejector (4) hold. Exhaust system (1) according to one of claims 2 until 5 , characterized in that flow channels are formed by the structure of the catalyst support materials of the exhaust gas catalysts (11, 12), the individual flow channels to at least one further flow channel having the same or different cross-sectional areas. Exhaust system (1) after claim 6 , characterized in that flow channels are formed through the structure of the catalyst support materials of the exhaust gas catalytic converters (11, 12), the cross-sectional area of the flow channels of the structure of the catalyst support material of the first exhaust gas catalytic converter (11) tapering in the direction of flow and/or the cross-sectional area of the Flow channels of the structure of the catalyst support material of the second exhaust gas catalyst (12) enlarged in the direction of flow substantially.

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