DE102021214992A1 - Exhaust gas sensor device and exhaust bypass cooler with an exhaust gas sensor - Google Patents

Abstract

The invention relates to an exhaust gas bypass cooler (70) with an inlet (72) and an outlet (74) for connecting the exhaust gas bypass cooler (70) to an exhaust gas line (62), for example of an internal combustion engine, and to a bypass line (78) that connects the Inlet (72) connects to the outlet (74) and represents a path parallel to the exhaust gas line (62), and with a connection point (95) provided on the bypass line (78) for connecting an exhaust gas sensor (16). It can be at the exhaust gas sensor be, for example, an optical particle sensor. The invention also relates to an exhaust gas sensor device comprising an exhaust gas bypass cooler and an exhaust gas sensor mounted in it.

Description

State of the art

From the DE 10 2008 044 171 A1 the applicant is already aware of an exhaust gas sensor whose essential components are arranged in a bypass to an exhaust pipe.

The DE 10 2018 218 734 A1 on the other hand, the applicant discloses a particle sensor with means for generating laser light and with means for focusing laser light onto a laser focus and with means for detecting thermal radiation, which has at least one optical access which separates an area exposed to the measurement gas from an area facing away from the measurement gas, which is not exposed to the measurement gas, wherein the means for generating laser light and the means for detecting thermal radiation are arranged in the area facing away from the measurement gas, which has a housing in which the optical access is arranged, the housing having at least one Has an inlet opening through which a partial flow can be removed from the flow of the measurement gas and can be introduced into the interior of the housing, and has at least one outlet opening for the partial flow to exit from the housing.

Disclosure of Invention

The present invention relates to an exhaust gas bypass cooler with an inlet and an outlet for connecting the exhaust gas bypass cooler to an exhaust pipe, for example an internal combustion engine, and with a bypass pipe which connects the inlet to the outlet and represents a path parallel to the exhaust pipe, and with a the connection point provided in the bypass line for connecting an exhaust gas sensor.

This is based on the objective of being able to carry out measurements in the exhaust gas of high-performance internal combustion engines with exhaust gas sensors that have a certain temperature sensitivity, for example of the type of particle sensor from the prior art mentioned at the beginning, i.e. starting from very hot exhaust gases and very high exhaust gas velocities or very high exhaust gas mass flows. The exhaust gas bypass cooler reduces the temperature and possibly also the speed or the mass flow of the exhaust gas to which the exhaust gas sensor is exposed.

For example, the inlet may include an interface configured as a flange that may be sealingly fixed to a complementarily configured flange of the exhaust pipe.

The same applies to the outlet: it can, for example, comprise an interface designed as a flange, which can be fixed in a sealing manner to a flange of the exhaust gas line designed in a complementary manner.

The connection point for connecting the exhaust gas sensor can also be an interface that includes a flange. A flange of the exhaust gas sensor of complementary design can be fixed to it in a sealing manner. Alternatively, the connection point can include a thread that can be screwed to a thread of the exhaust gas sensor.

For effective cooling of the exhaust gas in the bypass line, mixing elements can be arranged in the bypass line. For example, mixing elements can be arranged in such a way that a static mixer is implemented, which significantly increases the distance covered by the gas flowing through the bypass line. This improves the thermal interaction of the gas with the exhaust gas bypass cooler, i.e. its cooling effect. However, a throttling of the flow through the exhaust gas bypass cooler by the mixing elements can and should only be slight.

Alternatively, the bypass line can be designed as a tube bundle, for example with a large number of tubes parallel to one another within the bypass line.

For cooling the bypass line and thus indirectly for the effective cooling of the exhaust gas in the bypass line, it can be provided that a cooling element or cooling elements are provided on the outside of the bypass line. The cooling elements can be cooling fins, for example. For example, a heat sink with cooling ribs, in particular a spiral-fin heat sink, can be fixed, for example welded, on the bypass line.

It can expediently be provided that the mixing elements and the cooling elements overlap along the extension of the bypass line, in particular are arranged completely in the same area. The exhaust gas to be cooled then interacts intensively with precisely that area of the wall of the bypass line which is cooled from the outside by the cooling elements.

The invention also relates to a sensor device which comprises an exhaust gas bypass cooler of the type described and an exhaust gas sensor which is connected to the connection point, for example mounted in a gas-tight manner. For example, the exhaust gas sensor can have a mounting flange that is connected to the connection point of the exhaust gas bypass cooler.

The exhaust gas sensor can be designed in such a way that it has means for generating laser light and means for focusing laser light onto a laser focus and has means for detecting thermal radiation. The exhaust gas sensor has in particular at least one optical access, which separates an area exposed to the measurement gas from an area facing away from the measurement gas and not exposed to the measurement gas. The means for generating laser light and the means for detecting thermal radiation are arranged in particular in the area facing away from the measurement gas.

Such an exhaust gas sensor is able to detect soot particles in particular using the principle of laser-induced incandescence.

It can be provided that the means for generating laser light is a laser. It can be provided that the means for focusing comprises a lens, in particular the optical access designed as a lens. Provision can be made for the means for detecting thermal radiation to be a photodetector, for example a single photon avalanche diode (SPAT). It can be provided that the optical access is a window.

It can be the case that the exhaust gas sensor has a housing in which the optical access is arranged, and that the exhaust gas sensor, in particular the housing, has at least one inlet opening through which a partial flow of the measurement gas can be removed and fed into the interior of the exhaust gas sensor, in particular of the housing, and has at least one outlet opening for the partial flow to exit from the exhaust gas sensor, in particular from the housing, and that the housing comprises a first partial housing, in which the means for generating laser light and the means for detecting thermal radiation are arranged, and that the housing comprises a second housing part, which is mounted on the first housing part, wherein the second housing part is tubular and wherein the means for focusing laser light onto the laser focus are arranged in the second housing part.

The provision of two partial housings enables thermal decoupling between the generally relatively temperature-sensitive components for generating and detecting radiation and the exhaust gas.

In an advantageous development, it is provided that the housing comprises a third housing part, which is mounted in particular on the first housing part, is in particular tubular in design and is in particular concentric with the second housing part. The third partial housing is able to thermally shield the second housing and thus indirectly also the first housing. If the third partial housing has cooling ribs on its outside, this is all the more the case.

In an advantageous further development it is provided that the optical access is mounted in or on the third partial housing, in particular on the side of the third partial housing which is remote from the first partial housing. In this case, the flow of heat from the rather hot optical access to the first partial housing is impeded by the third partial housing.

In an advantageous development, it is provided that a heat protection shield, in particular a collar-shaped one, is mounted on the third partial housing, in particular on the side of the third partial housing facing away from the first partial housing. It interrupts the flow of heat to and through the third sub-housing.

In an advantageous further development it is provided that a protective tube module is fixed to the third partial housing, in particular on the side of the third partial housing which is remote from the first partial housing. It can be designed, for example, as in the prior art mentioned at the outset.

In an advantageous development, it is provided that the first partial housing has cooling ribs on its outside. This cools the optical components inside.

Provision can be made for the means for focusing to comprise two converging lenses which are arranged in the two axial end regions of the second partial housing and in this way form a telescope. In this way, the telescope can be better thermally and mechanically decoupled from the exhaust gas, and the two converging lenses are spatially fixed relative to one another in this way, which makes the imaging through the telescope particularly robust.

The invention also relates to an exhaust tract, for example an internal combustion engine, with such an exhaust gas bypass cooler or with such a sensor device, the exhaust tract having an exhaust line with a discharge point and an inlet point, the discharge point of the exhaust tract being connected to the inlet of the exhaust gas bypass cooler and wherein the point of introduction of the exhaust tract is connected to the outlet of the exhaust bypass cooler.

The effect of the exhaust gas bypass cooler cooling the exhaust gas is improved if a heat protection device is installed between the exhaust pipe of the exhaust gas section and the bypass pipe of the bypass cooler. It can be a heat shield. It can, for example, shield the majority of the bypass line from the exhaust gas line along the extent of the bypass line.

• 1 eine Veranschaulichung des auf der laserinduzierten Inkandeszenz basierenden Messprinzips, das bei der Erfindung vorzugsweise verwendet wird;
• 2 einen prinzipiellen Aufbau zur Veranschaulichung der Funktionsweise des Sensors, wie er bei der Erfindung vorzugsweise verwendet wird;
• 3 beispielhaft einen prinzipiellen Aufbau eines Abgassensors, der im Rahmen der Erfindung verwendet werden kann;
• 4 einen Abgassensor, der im Rahmen der Erfindung verwendet werden kann;
• 5 ein Ausführungsbeispiel der Erfindung;
• 6 - 10 Detailansichten des Ausführungsbeispiels aus 5

Embodiments of the invention are shown in the drawings and are explained in more detail in the following description. The same reference symbols in different figures denote the same elements or elements that are at least comparable in terms of their function. Show it:

• 1 an illustration of the measurement principle based on the laser-induced incandescence, which is preferably used in the invention;
• 2 a basic structure to illustrate the functioning of the sensor, as it is preferably used in the invention;
• 3 an example of a basic structure of an exhaust gas sensor that can be used within the scope of the invention;
• 4 an exhaust gas sensor that can be used in the invention;
• 5 an embodiment of the invention;
• 6 - 10 Detailed views of the embodiment 5

1 illustrates the measurement principle based on laser-induced incandescence. High-intensity laser light 10 strikes a particle 12, for example a soot particle. The intensity of the laser light 10 is so high that the energy of the laser light 10 absorbed by the particle 12 heats the particle 12 to several thousand degrees Celsius. As a result of the heating, the particle 12 emits radiation 14 in the form of thermal radiation without a preferred direction. Part of the radiation 14 emitted in the form of temperature radiation is therefore also emitted in the opposite direction to the incident laser light 10 .

2 shows a schematic of a basic structure to illustrate how particle sensor 16 works. Particle sensor 16 has a laser 18 designed as a CW laser module (CW: continuous wave; continuous wave), whose preferably collimated laser light 10 is arranged with at least one in the beam path of laser 18 Converging lens 20 is focused on a very small focus 22 in which the intensity of the laser light 10 is sufficiently high for laser-induced incandescence. The invention is not limited to the use of a CW laser. It is also conceivable to use pulsed operated lasers.

The dimensions of the spot 22 are in the range of a few μm, in particular in the range of at most 200 μm, so that particles 12 traversing the spot 22 are excited to emit evaluable radiant power, either through laser-induced incandescence or through chemical reactions (particularly oxidation). As a result, it can usually be assumed that there is always at most one particle 12 in the spot 22 and that an instantaneous measurement signal of the particle sensor 16 only comes from this at most one particle 12 . The measurement signal is generated by a detector 26 which is arranged in the particle sensor 16 in such a way that it detects radiation 14 emanating from the particle 12 flying through the spot 22 , in particular thermal radiation. For this purpose, the detector 26 preferably has at least one photodiode 26.1. A single particle measurement is thus possible, which in principle even allows the extraction of information about the particle 12 such as size and speed.

3 shows an example of a basic structure of a particle sensor 16 according to the invention.

Particle sensor 16 has a protective tube module 200 composed of a first, outer protective tube 210 and a second, inner protective tube 220 . The arrangement of the protective tubes is only roughly and schematically shown here 4 referred.

The particle sensor 16 has a laser 18 which preferably generates collimated laser light 10 . A beam splitter 34 is located in the beam path of the laser light 10 . In this focus 22, the light intensity is high enough to heat the particles 12 transported with the exhaust gas 32 to several thousand degrees Celsius, so that the heated particles 12 emit significant radiation 14 in the form of thermal radiation. This radiation 14 is, for example, in the near-infrared and visible spectral range, without the invention being restricted to radiation 14 from this spectral range. Part of this radiation 14 , which is emitted in an undirected manner in the form of temperature radiation, is captured by the converging lens 20 and directed onto the detector 26 via the beam splitter 34 . This structure has the advantage that only one optical access 40 to the exhaust gas 32 is required, since the same optics, in particular the same converging lens 20, are used for generating the focus 22 and for detecting the particle 12 outgoing radiation 14 is used. The exhaust gas 32 is an example of a measurement gas. The measuring gas can also be another gas or gas mixture, for example room air.

The laser 18 has a laser diode 36 and a second lens 38 which preferably collimates the laser light 10 emanating from the laser diode 36 . The use of the laser diode 36 represents a particularly cost-effective and easy-to-handle option for generating laser light 10 . The laser light 10 , which is preferably collimated, is focused by the converging lens 20 .

The optical particle sensor 16 has a first part 16.1 (exhaust gas side) exposed to the exhaust gas and a second part 16.2 (clean gas side) which is not exposed to the exhaust gas and contains the optical components of the particle sensor 16. Both parts are separated by a partition 16.3, which runs between the protective tubes 210, 220 and the optical elements of the particle sensor 16. The wall 16.3 serves to insulate the sensitive optical elements from the exhaust gas 32. In the partition wall 16.3, an optical access 40 designed as a window is installed in the beam path of the laser light 10, through which the laser light 10 falls into the exhaust gas 32 and via the focus 22 outgoing radiation 14 can incident on the converging lens 20 and from there via the beam splitter 34 on the detector 26.

As an alternative to the exemplary embodiment illustrated here, the production of the focus 22 and the detection of the radiation 14 emanating from particles in the focus 22 can also take place via separate optical beam paths.

It is also conceivable to generate the focus 22 with lens combinations other than those given here merely as an exemplary embodiment. In addition, the particle sensor 16 can also be implemented with laser light sources other than the laser diodes 36 specified here for exemplary embodiments.

The 4 shows one of a particle sensor 16 for detecting particles 12. Has a first partial housing 101, which is provided with cooling fins 101.1 on its side surfaces, and in which a laser 18, a photodetector 26 and other electronic components 500, for example for signal detection and signal evaluation, are arranged.

The particle sensor 16 also has a second partial housing 102 which is mounted on the first partial housing 101 and is tubular. Two plano-convex lenses 20 are arranged in the two axial end regions of the second partial housing 102 and in this way form a telescope.

The particle sensor 16 also has a third housing part 103 which is mounted on the first housing part 101 , which is tubular and which is concentric with the second housing part 102 . An annular space is formed between the second and the third partial housing 103, which can be filled with air or evacuated, for example. The third partial housing 103 has cooling ribs 103.1 on its outside.

The optical access 40 in the form of a window 42 mounted in a window holder 41 is mounted on the side of the third partial housing 103 facing away from the first partial housing 101 .

Furthermore, a collar-shaped heat protection shield 44 is mounted on the side of the third partial housing 103 facing away from the first partial housing 101 . It consists, for example, of two metal sheets and a gap formed between them, which can be filled with air, for example.

Furthermore, a mounting flange 46 for mounting the particle sensor 16 on a measurement gas line is provided on the side of the third partial housing 103 facing away from the first partial housing 101 . It lies flat, for example, on a weld-in nipple 50 of an exhaust pipe and is fixed by means of a V-band clamp 52 known per se.

In addition, a protective tube module 200 is also fixed on the side of the third partial housing that faces away from the first partial housing.

In this example, the protective tube module 200 consists of a first protective tube 210, a second protective tube 220 and a third protective tube 230.

The first protective tube 210 is designed in the shape of a cup, with a cup wall forming a lateral surface and a cup bottom. In the pot wall, near the bottom of the pot, there is a circular ring of holes made up of, for example, 12 inlet openings 301 of the particle sensor 16 .

The second protective tube 220 has a substantially hat-like shape and is arranged substantially inside the first protective tube 210 . The second protective tube 220 rests radially on the inside of the pot wall of the first protective tube 210 . In an overflow opening section, a ring of holes is provided, in example 12 overflow openings 303 which form an annular space 240 formed between the first protective tube 210 and the second protective tube 220 with a gas space formed inside the second protective tube 220 250 connect. The overflow opening section of the second protective tube 220 is followed by a conically tapering area and this is followed by a cup-shaped end area of the second protective tube 220, which is pressed with its lateral surface into an opening in the pot bottom of the first protective tube 210. The outlet opening 302 of the particle sensor 16 is provided in the end face of the end region of the second protective tube 220, which in the present example is only slightly smaller than the end face itself.

The third protective tube 230 is again arranged inside the second protective tube 220 . It has a first straight cylindrical section. The straight cylindrical section of the third protective tube 230 is followed by a conically tapering section which is open on the side of the third protective tube 230 facing the exhaust gas.

Along an axial direction 400, which is defined, for example, by the direction pointing from the optical access 40 to the outlet opening 302, the conically tapering section of the third protective tube 230 is at the same axial height as the overflow openings 303 in the second protective tube 220.

5 shows an exhaust tract 60 of an internal combustion engine as an exemplary embodiment of the invention. An exhaust pipe 62 has an outlet point 64 and an inlet point 66 located downstream of it. The discharge point 64 of the exhaust tract 60 is connected to an inlet 72 of an exhaust gas bypass cooler 70 and the introduction point 66 of the exhaust tract 60 is connected to the outlet 74 of the exhaust gas bypass cooler 70 .

In the example, the connections are made via a flange 68 on the exhaust line side, on which a flange 76 on the bypass cooler side rests flat and is fixed, for example, via a V-band clamp or screw connections.

A seal, for example made of the thermally highly insulating material mica or phlogopite mica, can be provided between two flanges resting on one another, for example as a sealing ring and/or made of the material that is known under the brand name novamica. The mica seal contributes significantly to reducing heat flow from the exhaust pipe into the bypass cooler.

The exhaust bypass cooler 70 further includes a tubular bypass line 78 connecting the inlet 72 to the outlet 74 and providing a path parallel to the exhaust line 62 . The bypass line 78, as in the 5 shown, immerse in the exhaust pipe 62 in the area of the two connections. The immersed pipe ends 78a may be formed as half-pipes that open in the upstream direction (e.g., in the case of the inlet 72 of the exhaust bypass cooler 70) or in the downstream direction (e.g., in the case of the outlet 74 of the exhaust bypass cooler 70). are open, see 8th .

Mixing elements 80 are arranged within the bypass line 78, see also 6 . In the present example, they are designed as metal sheets arranged one behind the other along the extension of the bypass line 78, which are each twisted by 180°, so that they have the shape of a helix. In this case, each coil is rotated by 90° relative to its neighboring coil. The sense of rotation of the twist of each helix is oriented in the opposite direction to the sense of rotation of its neighboring helix. In the example, 8 coils are arranged one behind the other.

The arrangement of the mixing elements 80 in the bypass line 78 results in a static mixer which significantly increases the distance of the gas flowing through the bypass line 78 . This improves the thermal interaction of the gas with the exhaust gas bypass cooler 70, ie its cooling effect. By contrast, a throttling of the flow through the exhaust gas bypass cooler 70 due to the mixing elements 80 can and should be minimal at most (e.g. <10%).

The mixing elements 80, in particular the coils, can be connected to the bypass line 78 with a material fit, for example by welding or brazing.

At least one cooling element 90 is provided on the outside of the bypass line 78 . In the example, these are cooling ribs 92 or a spiral-shaped strip of ribs 94 which are/is welded onto the outside of the bypass line 78 . For example ( 5 ) the exhaust gas bypass cooler 70 is designed as a spiral fin tube heat sink with, for example, 86 turns.

Although an alternative embodiment also uses a cooling element 90, as explained above, instead of mixing elements 80, the surface area inside the bypass line is increased by a tube bundle 81, for example with a tube bundle 81 consisting of 7 individual tubes 81'. A cutaway view of such a finned-tube tube bundle cooler is in FIG 7 shown. It can be designed, for example, as a spiral fin tube tube bundle cooler, i.e. with a spiral fin strip 94.

A connection point 95 designed with a connection flange 50 for connecting an exhaust gas sensor 16 is provided on the bypass line 78 in a region downstream, for example as seen from the mixing elements 80 and from the cooling element 90 .

The connection point 95 can be, for example, a connection flange 50 or a weld-in nipple welded into the bypass line 78 . Provision can be made for the cross section of the bypass line 78 within the connecting flange 50 to be reduced, for example by at least 10%, in order to achieve a Venturi effect. The flow through an exhaust gas sensor 16 mounted at the connection point 95 can be intensified in this way, see FIG 9a and 9b , which show two mutually perpendicular cross sections through the connecting flange 50.

The exhaust gas sensor 16 is in the 5 only shown schematically. In this respect, it can be, for example, in detail in the 4 Particle sensor 16 shown and described above act. Other exhaust gas sensors 16, in particular those that are only able to withstand a limited amount of heat, can of course also be provided.

The connection point 95 and the exhaust gas sensor 16 can also be different than in FIG 5 shown, for example in such a way that the connection point 95 and the exhaust gas sensor 16 are oriented with their longitudinal axis 400 perpendicular to the bypass line 78 and/or perpendicular to the exhaust line 62 (e.g. in FIG 5 forward or backward).

The cooling capacity of the bypass cooler can be scaled by choosing the length of the heat sink. There is an approximately linear relationship between the cooling capacity and the length.

In order to be able to select a mass flow through the bypass cooler 70 independently of the mass flow and the flow rate of the exhaust gas in the exhaust pipe 62, it can be provided that a short throttle 82 with the required cross section is inserted in the bypass cooler 70. This can be, for example, a 5 mm long piece of pipe that is pressed into the bypass cooler 70, for example in its entry area.

Bypass coolers for many applications can then be manufactured with the same diameter and only differ from one another in terms of the throttle 82, which is adapted in terms of its inner diameter. The outer diameter of the choke can also be chosen to be the same for many applications.

In the present example, it is provided that a heat protection device 87 is mounted between the exhaust line 62 of the exhaust tract and the bypass line 78 of the bypass cooler, see FIG 5 and 10 . This is a stainless steel sheet that is curved for reinforcement and has a circumferential angled edge. In the example, it has two beaded and recessed screw connections.

In addition, the exhaust pipe 62 has two welded-on brackets 89 made of stainless steel sheet metal, to which the heat protection device 87 can be screwed with stainless steel screws. Alternatively, the heat protection device 87 can also be riveted or welded to the brackets 89 .

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited 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 assumes no liability for any errors or omissions.

Patent Literature Cited

• DE 102008044171 A1 [0001]
• DE 102018218734 A1 [0002]

Claims (15)

Exhaust gas bypass cooler (70) with an inlet (72) and an outlet (74) for connecting the exhaust gas bypass cooler (70) to an exhaust gas line (62), for example an internal combustion engine, and to a bypass line (78) which connects the inlet (72) connects to the outlet (74) and represents a path parallel to the exhaust gas line (62), and having a connection point (95) provided on the bypass line (78) for connecting an exhaust gas sensor (16). exhaust gas bypass cooler (70). claim 1 , mixing elements (80) being arranged within the bypass line (78). exhaust gas bypass cooler (70). claim 1 or 2 , At least one cooling element (90) being provided on the outside of the bypass line (78). Sensor device (86) with an exhaust gas bypass cooler (70). claim 1 , 2 or 3 , An exhaust gas sensor (16) being connected to the connection point (95) of the exhaust gas bypass cooler (70). sensor device claim 4 , characterized in that the exhaust gas sensor (16) has a mounting flange (46) which is connected to the connection point (95) of the exhaust gas bypass cooler (70). sensor device claim 4 or 5 , wherein the exhaust gas sensor has means for generating laser light (10) and with means for focusing laser light (10) onto a laser focus (22) and means for detecting thermal radiation (14), the exhaust gas sensor (16) having at least one optical access (40) which separates an area (16.1) exposed to the measurement gas from an area (16.2) facing away from the measurement gas and not exposed to the measurement gas, the means for generating laser light (10) and the means for detecting thermal radiation (14) are arranged in the area (16.2) facing away from the measurement gas. sensor device claim 6 , wherein the exhaust gas sensor (16) has a housing (100) in which the optical access (40) is arranged, and wherein the exhaust gas sensor (16), in particular the housing (100), has at least one inlet opening (301) through which a partial flow (321) can be removed from the flow of the measurement gas and introduced into the interior of the exhaust gas sensor (16), in particular the housing (100), and at least one outlet opening (302) for the partial flow to exit from the exhaust gas sensor, in particular from the housing ( 100), characterized in that the housing (100) comprises a first partial housing (101) in which the means for generating laser light (10) and the means for detecting thermal radiation are arranged, and in that the housing (100) a second partial housing (102), which is mounted on the first partial housing (101), which is tubular and in which the means for focusing laser light (10) onto the laser focus (22) are arranged. sensor device claim 7 wherein the housing (100) comprises a third sub-housing (103) mounted on the first sub-housing (101) and which is tubular and which is concentric with the second sub-housing (102). sensor device claim 8 , wherein the mounting flange (46) for mounting the exhaust gas sensor (16) is fixed on the third partial housing (103), in particular on the side of the third partial housing (103) facing away from the first partial housing (101). sensor device claim 8 or 9 , wherein a protective tube module (200), which has at least one inlet opening (101) through which the flow of the measurement gas, a partial flow (321) can be removed and introduced into the interior of the protective tube module (200) and which has at least one outlet opening (302) through which the partial flow (321) leaves the protective tube module (200), and which inside the protective tube module (200 ) a shield is provided, which deflects the partial flow (321) in a direction away from the optical access (40). Sensor device according to one of Claims 8 , 9 or 10 , wherein the protective tube module (200) has a first protective tube (210) which has at least one inlet opening (301) through which a partial flow (321) can be removed from the flow of the measurement gas and introduced into the interior of the protective tube module (200), and that the protective tube module (200) has a second protective tube (220), which is arranged in the first protective tube (210), so that an annular space (240) is formed between the first protective tube (210) and the second protective tube (220), and that the second protective tube (220) has at least one overflow opening (303), through which the partial flow (321) flows from the annular space (240) into a gas space (250) arranged inside the second protective tube (220), and that the outlet opening (302) is formed on the first protective tube (210) or on the second protective tube (220) and that a means is provided which directs the partial flow (321) into one of the optical access (40) during or after the flow through the overflow opening (303) direction away from the outlet opening (302). Sensor device according to one of Claims 4 until 11 , characterized in that the means for generating laser light (10) is a laser (18) and/or that the means for focusing comprises a lens (20), in particular the optical access (40) designed as a lens (20), and/or that the means for detecting thermal radiation is a photodetector (26) and/or that the optical access (40) is a window (42). Sensor device according to one of Claims 4 until 12 , wherein the means for focusing comprises two converging lenses (20) which are arranged in the two axial end regions of the second partial housing (102) and in this way form a telescope. Exhaust system (60), for example an internal combustion engine, with an exhaust gas bypass cooler (70) according to one of Claims 1 , 2 or 3 or a sensor device (86) according to any one of Claims 4 until 13 , wherein the exhaust tract (60) has an exhaust line (62) with an outlet point (64) and an inlet point (66), the outlet point (64) of the exhaust tract (60) having the inlet (72) of the exhaust gas bypass cooler (70) is connected and wherein the introduction point (66) of the exhaust tract (60) is connected to the outlet (74) of the exhaust gas bypass cooler (70). Exhaust tract (60) after Claim 14 , wherein between the exhaust line (62) of the exhaust tract (60) and the bypass line (78) of the bypass cooler (70) a heat protection device (87) is mounted.

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