WO2012146417A1

WO2012146417A1 - Sensor apparatus for detecting a parameter of a flowing fluid medium

Info

Publication number: WO2012146417A1
Application number: PCT/EP2012/053397
Authority: WO
Inventors: Alexander Martin; Martin Schilling; Richard Fix; Marc Brueck; Tobias WOERZ
Original assignee: Robert Bosch Gmbh
Priority date: 2011-04-29
Filing date: 2012-02-29
Publication date: 2012-11-01
Also published as: CN103492873A; DE102011017772A1; CN103492873B; KR20140022397A

Abstract

The invention proposes a sensor apparatus (110) for detecting at least one parameter of a fluid medium flowing through a flow pipe (112), comprising at least one housing (114) and at least one sensor element (134), which is accommodated in the housing (114), for detecting the parameter, and a flow pipe. The housing (114) has at least one external housing (120) and at least one internal housing (122) which is at least partially surrounded by the external housing (120), wherein at least one gap, in particular at least one annular gap (124), is formed between the external housing (120) and the internal housing. The housing (114) is formed in such a way that at least a partial flow of the fluid medium can flow into the gap through at least one inlet opening (126) in order to arrive at the sensor element (134) and in order to then flow back into the flow pipe (112) through the internal housing (122) via at least one outlet opening (130). The housing (114) also has at least one retaining element (138). The housing (114) can be connected to the flow pipe (112) by means of the retaining element (138), wherein a portion of the housing (114) projects into the flow pipe (112). The inlet opening (126) is arranged at a distance from an internal wall (144) of the flow pipe (112). The sensor element (134) is arranged outside the flow pipe (112).

Description

Description title

Sensor device for detecting a parameter of a flowing fluid medium prior art

A variety of sensor devices for detecting one or more parameters of a flowing fluid medium are known in the prior art. The flowing fluid medium may be, for example, a gas or a liquid. The invention will be described below in particular with reference to exhaust gases of internal combustion engines, for example in the exhaust system of a motor vehicle. However, other applications are possible in principle. The at least one parameter to be detected may be, for example, a physical and / or chemical parameter. For example, it can be a flow parameter, for example a flow velocity, a mass flow or a volume flow of the fluid medium. However, it is particularly preferred if the at least one parameter to be detected at least one component, so for example a percentage and / or a partial pressure, of at least one component of the fluid medium, for example at least one

Gas component, includes or is. For example, this at least one component, which can be detected qualitatively and / or quantitatively, can be oxygen and / or nitrogen and / or nitrogen oxides and / or at least one

Hydrocarbon act. In general, the at least one parameter that is detected can be, for example, a component of at least one gas component.

Examples of such sensor devices, by means of which a proportion of at least one gas component in a gas can be detected, in particular an exhaust gas, are so-called lambda probes, ie generally sensor elements based on the use of at least one solid electrolyte material, preferably at least one ceramic solid electrolyte material, and such They are described for example in Robert Bosch GmbH: Sensors in the motor vehicle, 1st edition 2010, pages 160-165.

In addition, however, the present invention is applicable to a variety of other types of parameters to be detected and / or other types of sensor devices. Also in DE 10 2006 060 312 A1, in DE 10 2007 040 726 A1 and in DE 10 2008 041 038 A1 sensor devices are described which in the context of

can be used in principle modified in the present invention. Furthermore, so-called chemical field effect transistors as sensor elements in

Sensor devices used. Examples of such chemical field-effect transistors for use in automotive engineering are in H. Wingbrant: Studies of MISiC-FET Sensors for Car Exhaust Gas Monitoring, Linkoping Studies in Science and Technology,

Dissertation no. 931, pages 51 to 57, Linköping 2005 or in H. Wingbrant et al: Using a Misić FET Sensor for Detecting NH ₃ in the SCR system, IEEE sensor Journal, Vol 5, No.. October 5, 2005, pages 1099-1105.

In many current sensor devices, such as exhaust gas sensors, a sensor element is used, which may for example be electrically heated and which may be configured, for example, ceramic. This can, for example, by one or more metallic protective tubes from direct contact with the

Exhaust gas flow are at least partially shielded, as described for example in the above-mentioned prior art. The main tasks of the protective tubes are to limit the exhaust gas mass flow over the sensor element, to prevent condensation in the exhaust system from the sensor element, i.

especially in a protection against water hammer on the hot ceramic, which can lead to breakage of the sensor element, in ensuring a sufficient

Probe dynamics (rapid gas exchange in the vicinity of the sensor element) and in a protection of the sensor element against mechanical stress, for example in a shoring. However, these requirements for the thermowells are partly

in opposite directions. So is a high dynamics usually only by sufficient

Flow rate to achieve, however, a water transport to

Sensor element makes more likely and also increases the cooling by cold exhaust gas. As a rule, a part of the sensor element, which is usually of elongated design, is located spatially within the exhaust pipe in the case of current sensors.

It would therefore be desirable to have a sensor device which can ensure sufficient dynamics combined with high robustness and protection against water hammer.

Disclosure of the invention

To overcome the technical challenges of the known

Sensor devices accordingly become a sensor device for detecting at least one parameter of a fluid flowing through a flow tube Medium proposed. With regard to the possible embodiments of the fluid medium and the at least one parameter to be detected, which can be detected qualitatively and / or quantitatively, reference may be made to the above description. The fluid medium can in particular with a main flow direction through the

Flow the flow tube. Under a main flow direction is doing a

Main direction of a mass transport of the fluid medium understood in the flow tube. Local deviations from this main flow direction may possibly be negligible, such as local turbulence or the like. In principle, the main flow direction can also be reversible during operation. The flowing fluid medium may in particular comprise a gaseous medium, in particular an exhaust gas of an internal combustion engine.

The sensor device comprises at least one housing and at least one sensor element at least partially accommodated in the housing for detecting the at least one parameter. Under a housing is generally understood an element which has at least one interior, in this case at least one interior for receiving the at least one sensor element, and which is preferably adapted to a protective effect against at least

to ensure mechanical loads. For example, the housing may be at least partially made of a rigid material which

for example, in a fixing of the housing in the flow tube of the fluid medium under normal forces, for example, at normal Verschraubungskräften, undergoes no deformation. The housing may for example be wholly or partly made of a metallic material and / or a plastic material.

In the context of the present invention, a sensor element is understood to mean an element which is set up to qualitatively and / or quantitatively detect the at least one parameter and to generate a corresponding signal.

For example, the at least one sensor element may comprise at least one sensor chip. As will be explained in more detail below, the sensor element may in particular comprise at least one ChemFET, for example according to the above-described prior art. The sensor element may generally comprise, for example, at least one sensor surface, wherein the sensor element may be accommodated in the housing such that the sensor surface is in contact with the fluid medium

can be acted upon. The sensor element may in particular be a miniature component in a very small installation space, for example with a construction space of less than 2 cm ³ , in particular less than 1 cm ³ and more preferably less than 0.5 cm ³ . In particular, the miniature component may be a miniature component in cubic form.

The housing has at least one outer housing and at least one of the

Outer housing at least partially enclosed inner housing. At least one gap, in particular at least one annular gap, is formed between the outer housing and the inner housing. Without limitation of other possible

Embodiments will hereinafter be particularly referred to a configuration as at least one annular gap reference. The housing is designed such that at least a partial flow of the fluid medium can flow through at least one inlet opening into the gap, ie from the flow tube into the gap and thus into the housing in order to reach the sensor element. The housing is further designed such that the partial flow then through the inner housing via at least one

Outlet opening can flow back into the flow tube.

The housing further has at least one retaining element. The housing can be connected to the flow tube by means of the retaining element, wherein a part of the housing projects into the flow tube. The inlet opening is from an inner wall of the

Flow tube arranged spaced, wherein the sensor element is arranged outside of the flow tube.

The housing is thus connected by means of the retaining element with the flow tube. For this purpose, the flow tube may, for example, have at least one opening, wherein the housing projects completely or partially through this opening into the flow tube. By means of the holding element, the housing in the

Flow tube be fixable, for example by the housing by means of

Retaining element in a position and / or orientation relative to the flow tube is fixable, wherein a fixation in one, two or three dimensions is possible. Under a holding element is generally an element to understand, which can establish a connection between the housing and the flow tube. This connection can be for example a non-positive and / or positive and / or material connection. For example, the holding element may comprise at least one thread. For example, the at least one retaining element of the housing cooperate with at least one element of the flow tube, for example with a mating thread. Thus, for example, both the housing and the flow tube each have at least one thread, so that the housing is preferably fixable in the flow tube. Alternatively or additionally, the holding element, for example, comprise a simple stop surface, by means of which the housing can be applied to the flow tube. For example, the housing may comprise a collar, for example, a circumferential projecting edge on the housing, which rests on the flow tube when the housing is inserted or inserted into the flow tube, so that a depth limitation of the insertion or insertion takes place. In general, the holding element can be designed such that it positions the housing in at least one dimension relative to the flow tube, for example in a direction perpendicular to the main flow direction and / or perpendicular to a tube axis of the flow tube. For example, as stated above, the housing can be positioned relative to the flow tube in such a way that it always projects into the flow tube at the same depth. The holding element can cooperate with at least one flow tube-side holding element.

The housing has, as described above, at least one outer housing and at least one of the outer housing at least partially enclosed

Inner housing on. For example, the outer housing and / or the

Be configured at least partially tubular, so that in the following, without limitation, other possible embodiments, with reference to the

Outside housing is also spoken by an outer tube, and with reference to the inner housing of an inner tube. The outer housing may, for example, enclose the inner housing in an annular manner. Between the outer casing and the inner casing, the gap, for example the annular gap, is formed, which preferably surrounds the entire inner casing or only around a part of the inner casing

Inner housing may extend, preferably at least 80% of the inner housing. The annular gap may at least partially enclose the inner housing.

The housing is configured such that the fluid medium can flow into the gap to get to the sensor element and then to flow through the inner housing back into the flow tube. For example, the inner housing may have at least one inner space, for example a substantially cylindrically shaped inner space through which the fluid medium can flow back into the flow tube. For example, the fluid medium can flow in an axial direction into the annular gap, get to the sensor element, and

then again in an opposite axial direction through the Flow the inner housing back into the flow tube. An axial direction is to be understood as meaning in general a direction parallel to an axis of the sensor device. For example, the sensor device may be designed substantially cylindrical, so that the axis may be, for example, a rotation axis of the housing and / or a part of the housing. For example, the housing may be fixable in the flow tube, in particular by means of the holding element, that the axis is aligned substantially perpendicular to the main flow direction, wherein the main flow direction may be aligned, for example parallel to a tube axis of the flow tube. In the context of the present invention, the term "substantially perpendicular or substantially parallel" is generally understood to mean a deviation from a vertical orientation or a parallel orientation which is not more than 30 °, preferably not more than 15 ° and in particular not more than 5 ° and more preferably 0 °. The flow tube may, for example, have a diameter of 30 mm to 150 mm, for example a diameter of 50 mm to 100 mm and particularly preferably a flow tube cross section of 70 mm. For example, depending on the displacement of an engine cross sections of the exhaust systems can be designed differently. Usual pipe diameters for passenger cars are between 30 mm and 100 mm. In commercial vehicles, the diameters are usually 100 mm to 150 mm. Others too

Diameters are possible. For example, the fluid medium, particularly the exhaust, may flow through the flow tube at an average flow rate of from 1 to 300 meters per second, or even at flow rates in excess of 300 meters per second, for example at a flow rate of from 2 to 7 meters per second. The flow rate may in turn be dependent on, for example, a cross section of the exhaust system and / or a

Operating point of the motor.

To avoid the problem described above, in the context of the present invention, in particular, the housing is thus proposed

to design that the inlet opening is arranged at a distance from an inner wall of the flow tube. The retaining element may in particular be arranged such that the inlet opening is spaced from the inner wall by at least 3 mm, in particular by at least 5 mm. For example, the inlet opening may be spaced from the inner wall by 3 mm to 20 mm, in particular by 5 mm to 15 mm and particularly preferably by 10 mm. The holding element can continue to be set up in this way be that the outlet opening is further spaced from the inner wall than the

Inlet opening. In particular, the outlet opening may be spaced from the inner wall by at least 5 mm, preferably by at least 10 mm. In particular, the outlet opening may be spaced from the inner wall by 8 mm to 30 mm, for example by 10 mm to 20 mm and particularly preferably by 15 mm.

The holding element can thus be configured, for example, such that a part of the sensor device located inside the flow tube and a part of the sensor device located outside the flow tube are defined. The sensor element can be arranged in the outer part, in particular for

Cooling of the sensor element. A distance of the sensor element to the inner wall of the flow tube can be in particular at least 20 mm, preferably at least 30 mm and particularly preferably at least 40 mm. The sensor device and in particular the housing may in particular comprise at least one heat sink arranged outside the flow tube, in particular a heat sink with at least one cooling fin. For example, at least one cooling rib may be provided, which simultaneously acts as a radiation protection sheet.

The sensor device may further comprise at least one tempering element. For example, this at least one tempering at least one

Include heating element. Furthermore, the sensor device may, for example, have at least one temperature control and / or at least one temperature control. The at least one tempering element and preferably the at least one

Temperature control or temperature control can be set up in particular to set a temperature of the sensor element, in particular to control or regulate.

The sensor device may further comprise at least one filter element, wherein, for example, at least one filter element may be provided, selected from the group consisting of: a chemical filter, a catalyst, a

fluidic measure, such as a mist eliminator and / or a Partikelabscheider.

In a further aspect of the present invention, a sensor system

proposed, which is a sensor device according to one or more of the above or below described embodiments as well as at least one Has flow tube, wherein the sensor device is connected by means of the holding member with the flow tube. For example, as described above, the sensor system may protrude into the interior of the flow tube through at least one opening in the flow tube. For further possible embodiments of the sensor system, reference may be made to the above description of the sensor device.

The proposed sensor device and the sensor system in one or more embodiments described above or below have a number of advantages over known sensor devices and sensor systems. Thus, this can be used in particular with new sensor elements as exhaust gas sensors, in which the sensor element is designed, for example, as a miniature component in a very small space in a cubic shape. Such sensor elements are described for example in DE 10 2007 040 726 A1. By means of the proposed sensor device, typical main requirements for the installation of such sensor elements can be fulfilled well. These main requirements are in particular that an operating temperature of the sensor element is below the temperature of current sensors and preferably below maximum occurring exhaust gas temperatures. For example, typical operating temperatures of the sensor element may be 300 ° C and typical

Exhaust gas temperatures, depending on installation position, for example at 700 ° C to briefly 1000 ° C or even permanently up to 1000 ° C. In operation, the sensor element can be heated electrically continuously, for example by means of the tempering element, and the temperature can be regulated in this case, for example. The exhaust gas temperature may, for example, at each operating point of the engine below the maximum

Operating temperature of the sensor element are. With previous sensor elements, a minimum temperature must generally be achieved. A higher gas temperature is rather uncritical for the sensor element in many cases and rather desirable in the sense of a lower heating power requirement. Furthermore, by means of the proposed sensor devices, the requirements of conventional sensor devices on the dynamics can also be met well. Thus, by means of the sensor device, a transport of the fluid medium, in particular a gas transport, to the sensor element at least

Realize approximately instantaneous. Particularly advantageous is the

proposed sensor device, however, in terms of requirements for protection against drops and particle impact and resistance to contamination, for example by soot. The arrangement of the sensor element spatially outside the flow tube and optionally a suitable geometry of the housing can ensure that the sensor element is supplied with a sufficient amount of fluid medium.

Furthermore, the fluid medium can also be cooled on its way to the sensor element, for example by the above-mentioned at least one heat sink, for example by cooling fins, which can be arranged on an outer side of the housing outside the flow tube, such that it has a flow path between the inlet opening and can cool the sensor element. Also one

Design without such cooling fins, however, is possible in principle.

By means of the proposed sensor device, therefore, several requirements can be met simultaneously, with a design principle which can largely be based on the geometry of known casings for exhaust gas sensors. This results in cost savings and the possibility of using existing infrastructures. For the realization of the present invention, for example, only comparatively small mechanical modifications of known housing geometries are necessary. The invention further enables partial flow sampling of fluid medium, for example exhaust gas, from a main flow in the flow tube and

preferably its cooling on the way to the installation location of the sensor element. Thus, the fluid medium, for example, the exhaust gas, preferably at any operating point with a temperature reach the sensor, which is below the actual operating temperature of the sensor. Furthermore, the supply of the removed fluid medium, for example of the exhaust gas, can take place with such a high speed to the installation location of the sensor element in the housing, that sufficient dynamics for measuring changes in concentration can be ensured. Another advantage is that with the sensor device according to the invention, a largely independent of a rotation angle of the sensor relative to the flow independent function of the gas sampling can be realized. In particular, the inlet opening can be designed such that it encloses the inner housing and / or the outlet opening annularly completely or partially. The sensor device can be constructed in such a way that a function of the sensor device is at least largely independent of a rotation of the sensor device about an axis of the sensor device

Sensor device. Furthermore, filtering and / or pretreatment of the removed fluid medium may also take place before the actual measurement. For this purpose, as above described, for example, be provided one or more filter elements. This at least one filter element can, for example, in the gap between the

Be arranged inlet opening and the sensor element. For example, a chemical filtering and / or catalysis can take place here. Alternatively or additionally, fluidic measures for droplet separation and / or particle separation can be taken before such impurities strike the sensor element.

The sensor device can, as described above, comprise a housing with protective tubes, that is, for example, an outer tube and an inner tube, wherein the housing can be made geometrically such that an optimum flow of a sensor element, for example a semiconductor sensor, is made possible in view of the above-mentioned requirements , For example, the sensor element may include at least one semiconductor sensor for measuring concentrations of one or more different gases in the exhaust gas of an internal combustion engine.

The holding element described above may, for example, comprise at least one collar, which is provided for engagement with the flow tube. The

Sensor device may include a flow guide, in which the branched partial flow is geometrically out of the flow tube, for example, the exhaust pipe and is deflected, for example, at a position in the greatest possible distance from the outer wall of the exhaust pipe, passed over the sensor element and then back into the flow tube to become.

The mode of operation of a partial flow take-off from a main flow through the flow tube, for example from a main exhaust gas mass flow, can take place in particular according to a principle already known from a lambda probe. The protective tubes of the probe housing may include inlet and outlet openings for the exhaust gas. In the vicinity of the at least one inlet opening, a delay of the flow with the consequence of an increase of the static pressure in the flow can be caused, for example, by a congestion zone, for example in the form of a part of the protective tubes oriented perpendicular to the main gas flow. At the same time by a reduction of a free cross section of the flow tube, in particular of the exhaust pipe, by the installation of the sensor device, an acceleration of the flow and thus

accompanied by a decrease in the static pressure in the flow in the region of the outlet opening can be realized. This pressure difference between the congestion zone and narrowest cross-section can be a driving force for the flow through the

Form sensor device.

Brief description of the drawings

Further details and features of the invention will become apparent from the following description of preferred embodiments, which are shown schematically in Figures 1 and 2. In detail show:

Figure 1 shows an embodiment of a sensor device according to the invention; and

Figure 2 shows a flow tube with the sensor device according to the invention according to Figure 1 in the installed state.

Embodiments of the invention

FIG. 1 shows a sectional view of a sensor device 110 according to the invention for detecting at least one parameter of a fluid medium flowing through a flow tube (indicated by the reference numeral 112). FIG. 2 shows a perspective illustration of the sensor device 110 in a state installed in a flow tube 112, hereinafter also referred to as an exhaust tube. Both figures will be referred to collectively below. The sensor device 110 and the flow tube 112 together form components of a sensor system 11 1.

The sensor device 110 comprises a housing 114, which projects into the flow tube 112 through an opening 116 substantially perpendicular to a main flow direction 118 of the fluid medium in the flow tube 112. The housing 1 14 has an outer housing 120 and an inner housing 122. The outer housing 120 surrounds the inner housing 122 in an annular manner, so that an annular gap 124 is formed between the outer housing 120 and the inner housing 122. At a top of the

Outer housing 120, that is, in a region in which the outer housing 120 preferably protrudes furthest into the flow tube 122, an inlet opening 126 is provided, which can surround, for example, the inner housing 122 annular. In the region of this inlet opening 126 forms, as described above, a Stowage zone 128 off. Furthermore, an outlet opening 130 is provided at the upper end of the inner housing 122, which protrudes furthest into the flow tube 112 and which may be designed, for example, tapered at its upper end. In this area forms, as also described above, a

Vacuum zone 132 off.

The fluid medium or a partial flow of the fluid medium, which of a

Main flow is branched off in the flow tube 112, at the inlet opening 126, as indicated in Figure 1 by arrows, enter the annular gap 124, flows through this in an axial direction of the sensor device 110, is deflected at the lower end and reaches a sensor element 134th With regard to possible embodiments of this sensor element 134, reference may be made, for example, to the above description. The partial flow can be cooled, for example, on its way from the inlet opening 126 to the sensor element 134, for example by one or more heat sinks not shown in detail in FIG. 1 on an outside outside of the flow tube 112. The partial flow can overflow at least one measuring surface 136 of the sensor element 134, for example , Subsequently, the partial flow is deflected again and flows through the inner housing 122 in the opposite axial direction and exits the housing 114 again at the outlet opening 130. The flow of the partial flow is in total by the pressure difference between the storage zone 128 and the

Vacuum zone 132 driven.

The housing 1 14 comprises at least one retaining element 138. A retaining element can generally be understood as meaning a connecting element which is set up to connect the housing 114 to the flow tube 112. In the illustrated

For example, the retaining element 138 may include a collar 140, which may rest on an outer side 142 of the flow tube 112. The collar 140 can be connected to the flow tube 112 in a non-positive and / or materially bonded and / or form-fitting manner, for example. For example, at least one thread can be provided. Other configurations are possible in principle. In the context of the present invention, a collar is generally to be understood as an arbitrary stop, which has a positioning,

In particular, a limitation of an insertion depth, the sensor device 110 causes relative to the flow tube 112. The holding element 138 is dimensioned such that the sensor element 134 outside the flow tube 112, in particular outside an inner region of the

Flow tube 112, is arranged. For example, a distance between an inner wall 1 4 of the flow tube 1 12 and the inlet opening 126, which is denoted di in FIG. 1, can be 3 mm to 20 mm, in particular 5 mm to 15 mm and particularly preferably 10 mm. A distance d ₂ between the inlet opening 126 and the outside 142 of the flow tube 112 may be, for example, 2 to 10 mm, in particular 3 to 7 mm and particularly preferably 10 mm greater than the distance di. Depending on the design of the flow tube 112, the distance d _{2 may} also be designed differently. For example, in this or in other exemplary embodiments, typical wall thicknesses (d ₂ - di) of the flow pipe 112, for example a simple exhaust pipe, may be 1 mm to 10 mm, in particular 2 mm to 3 mm. In particular, in the case of double-walled, air-gap-insulated exhaust systems, two or more sheets may also be provided, for example each with a thickness of 1 mm to 5 mm, in particular 2 mm, and an air gap of, for example, 1 mm to 10 mm, in particular 2 mm to 5 mm. A distance d ₃ between the inner wall 144 and the sensor element 134, for example the measuring surface 136, may be for example at least 20 mm, preferably at least 30 mm and particularly preferably at least 40 mm. For example, this distance can be 20 to 60 mm.

The mode of operation of the partial flow takeoff from the main exhaust gas mass flow in the arrangement according to FIGS. 1 and 2 can take place, for example, according to the principle already known from a lambda probe, for example according to the prior art described above. Thus, as described above, the storage zone 128 forms in the form of an overpressure zone on a side of the inlet opening 126 facing the main flow direction 118. The vacuum zone 132 is formed due to a reduced free cross-section of the flow tube 112. For example, the flow tube 112 may have the cross sections described above, for example, an inner diameter D in Figure 2 of 30 mm to 150 mm, in particular from 50 mm to 100 mm.

In contrast to the above-described prior art is in the

According to the embodiment of the invention according to Figures 1 and 2, the reduction of the free cross-section preferably significantly larger, and, consequently, results in a larger pressure difference between the storage zone 128 and the vacuum zone 132nd This leads to a higher branched partial mass flow, which has a faster response time of the sensor device 110 and thus increased dynamics result. By pulled into the interior of the flow tube 112 in

Sidewall of the outer housing 120, in contrast to the described prior art, entrainment of impurities, such as water, which as a wall film on the inner wall 144 of the flow tube 112, for example

Exhaust pipe, can be transported along prevented. Thus, this geometric design is more robust against a water hammer on the sensor element 134. An optimization of the requirements for maximum gas temperatures at a mounting position of the sensor element 134 and with respect to a dynamic

Response behavior leads in practice to an opposite behavior, which is also known as temperature-dynamic shear. High dynamics can be achieved, for example, by a large partial mass flow, which ensures rapid flushing of the housing volume of the housing 114 with fresh gas. However, a high mass flow at high gas temperatures at the same time for a high convective Enthalpieeintrag in the housing 1 14, and thus result in high

Gas temperatures at the sensor element 134. For temperature control of the sensor element 134, for example, at least one tempering element 146, in particular at least one active tempering element 146 may be provided, which in Figure 1 only

is hinted at. For example, this tempering element 146 may comprise at least one heating element and / or at least one cooling element.

For example, a resistive heating and / or a resistive cooling can be provided. Furthermore, a temperature control, in particular a temperature control can be provided. To reduce the gas temperature, the gas on its way to the sensor position of the sensor element 138 should preferably be allowed to be in contact with cold surfaces as intensively as possible in order to allow heat exchange between the gas and the housing 14. An enlargement of the

Heat transfer available area and a reduction of

Case temperature can be increased by increasing the distance from the location of the

Sensor element 128 to the inner wall 144 and / or to the outside 142 can be realized.

The sensor device 110 and the sensor system 111 shown in FIGS. 1 and 2 can be used, in particular, in an exhaust gas tract of an internal combustion engine. Particularly preferred is the use in a motor vehicle.

Claims

Claims 1. A sensor device (1 10) for detecting at least one parameter of a fluid medium flowing through a flow tube (112), comprising at least one housing (114) and at least one accommodated in the housing (114)

Sensor element (134) for detecting the parameter, wherein the housing (1 14) at least one outer housing (120) and at least one of the outer housing (120) at least partially enclosed inner housing (122), wherein between the outer housing (120) and the inner housing (122) at least one gap, in particular at least one annular gap (124) is formed, wherein the housing (114) is formed such that at least a partial flow of the fluid medium through at least one inlet opening (126) can flow into the gap to the sensor element (134) to arrive and then by the

Inner housing (122) via at least one outlet opening (130) back into the flow tube (112) to flow, wherein the housing (1 14) further at least one holding element (138), wherein the housing (114) by means of the holding element (138) the flow tube (112) is connectable, wherein a part of the housing (114) projects into the flow tube (112), wherein the inlet opening (126) of a

Inner wall (144) of the flow tube (112) is arranged spaced, wherein the sensor element (134) outside of the flow tube (1 12) is arranged.

2. Sensor device (1 10) according to the preceding claim, wherein the

Holding element (138) is arranged such that the inlet opening (126) of the

Inner wall (144) is spaced by at least 3 mm, in particular to

at least 5 mm.

3. Sensor device (1 10) according to any one of the preceding claims, wherein the holding element (138) is arranged such that the inlet opening (126) of the

Inner wall (144) is spaced by 3 mm to 20 mm, in particular by 5 mm to 15 mm and particularly preferably by 10 mm.

4. Sensor device (1 10) according to any one of the preceding claims, wherein the holding element (138) is arranged such that the outlet opening (130) further from the inner wall (144) is spaced apart than the inlet opening (126).

5. Sensor device (1 10) according to any one of the preceding claims, wherein the holding element (138) is arranged such that the outlet opening (130) from the inner wall (144) is spaced by at least 5 mm, in particular by at least 10 mm.

6. Sensor device (110) according to any one of the preceding claims, wherein the holding element (138) is arranged such that the outlet opening (130) from the inner wall (144) by 8 mm to 30 mm spaced, in particular by 10 mm to 20 mm and more preferably 15 mm.

7. Sensor device (1 10) according to any one of the preceding claims, wherein a distance of the sensor element (134) to the inner wall (144) is at least 20 mm, preferably at least 30 mm and more preferably at least 40 mm.

8. Sensor device (1 10) according to one of the preceding claims, wherein the sensor device (1 10) has at least one outside of the flow tube (112) arranged cooling body with at least one cooling fin.

9. Sensor device (1 10) according to one of the preceding claims, wherein the sensor device (1 10) comprises at least one tempering element (146).

10. Sensor device (1 10) according to one of the preceding claims, wherein the sensor device (1 10) comprises at least one filter element.

11. Sensor system, comprising at least one sensor device (1 10) according to one of the preceding claims and at least one flow tube (1 12), wherein the sensor device (1 10) by means of the holding element (138) with the flow tube (112) is connected.