WO2011157471A1

WO2011157471A1 - Apparatus for detecting a temperature of a fluid medium

Info

Publication number: WO2011157471A1
Application number: PCT/EP2011/056671
Authority: WO
Inventors: Johannes Schmid; Michael Piwonski; Hasan Sert; Florian Mueller; Hartmut Stetter; Arno Clauss; Marc Rosenland; Ulrich Gralka; Lothar Diehl; Sascha Klett; Markus Linck; Marc Brueck
Original assignee: Robert Bosch Gmbh
Priority date: 2010-06-15
Filing date: 2011-04-27
Publication date: 2011-12-22
Also published as: DE102010030075A1

Abstract

An apparatus (110) for detecting a temperature of a fluid medium is proposed. Said apparatus comprises at least one temperature sensor (114) which is set up to be introduced into the fluid medium. The temperature sensor (114) has a sensor body (124) and a measuring head (128) which projects into the fluid medium. At least one sensor element (130) for detecting a temperature is accommodated in the measuring head (128). The sensor element (130) is accommodated in the measuring head (128) in such a manner that the measuring head is at least largely thermally decoupled from the sensor body (124).

Description

Description title

PRIOR ART Temperature is an important parameter in numerous technical applications and processes which have to be detected by means of corresponding devices. For example, the temperature plays an important role in a control and / or regulation in process engineering, component protection or similar applications. Accordingly, from the prior art numerous sensors for detecting a temperature of fluid media, such as gases or

Liquids, known. In this regard, reference may be made in this regard to Robert Bosch GmbH: Sensors in motor vehicles, Edition 2007, pages 96-105. The measurement principles described there for detecting the temperature can in principle also be used in the context of the present invention. In particular, an electrical temperature measurement can be carried out, for example by means of thermocouples, the

Take advantage of Seebeck effect. Alternatively or additionally, resistance temperature sensors or other types of temperature sensors can also be used.

Although the temperature measurement, in particular the electrical temperature measurement, for example by means of thermocouples, a suitable for over 100 years

Measuring principle for detecting temperatures remains the individual

Measuring requirements of technical applications in many cases a large one

Challenge, in particular with regard to the measurement accuracy, the measurement dynamics, the upper temperature limits and / or the long-term stability.

To measure the temperature of flowing fluid media will be common

Temperature sensor used, which are usually configured as a rod-shaped sensor and are brought into contact with the fluid medium. Through various mechanisms of heat transfer (for example, convection, heat conduction, or radiation) the sensor thermal energy is supplied to and / or dissipated by this, whereby the sensor has a temperature similar to the

Fluid temperature assumes. Inside the probe is usually placed a sensor, For example, a thermocouple, a resistor with negative

Temperature coefficient (NTC), a positive temperature coefficient (PTC) resistor, a resistor or the like. The sensor generates due to its

thermophysical properties of an electrical signal associated with the temperature. This is further processed in a connected electronics.

From US 2007/0195857 AI are a temperature sensor and a method for

Production of the same known. The temperature sensor has a fixation, by means of which the sensor can be introduced vertically into a housing of a flow tube. Furthermore, the sensor has a sensor head with a plurality of

rotationally symmetrical about a sensor axis arranged ribs to increase the surface of the sensor head for the purpose of improving a

Heat transfer between the temperature sensor and the fluid on. Despite the known from the prior art improvements of

Temperature sensors with regard to their accuracy continues to exist

Need for optimization of these temperature sensors, especially in terms of their

Accuracy and its dynamics, for example, during rapid temperature changes. Disclosure of the invention

Accordingly, an apparatus for detecting a temperature of a fluid medium is proposed, which addresses the challenges described above and in particular an improved accuracy with respect to the

Temperature measurement and improved dynamics offers. The fluid medium can rest or flow. Hereinafter, without limitation of other possible embodiments, it is assumed that it is a flowing fluid medium. The device is designed to detect a temperature of the fluid medium, for example a liquid or a gas, in particular an exhaust gas of an internal combustion engine. The device comprises at least one temperature sensor which is adapted to be introduced into the fluid medium. For this purpose, the temperature sensor, for example, at least one

Fastening device for attachment in a tube wall of a flow tube of the fluid medium. This may be, for example, one or more threads, by means of which the temperature sensor or a part of the Temperature sensor can be screwed into the pipe wall. The

Fastening device is preferably designed such that the attachment of the temperature sensor in the pipe wall is media-tight and / or pressure-tight. The introduction can preferably be made such that the temperature sensor in

Substantially perpendicular to the pipe wall is introduced into the same, so with a deviation of preferably less than 20 °, in particular less than 10 ° and particularly preferably less than 5 ° to the pipe wall, for example, to an axis of the flow tube. The temperature sensor may be configured, for example, as a measuring finger, which projects completely or partially into the flow of the fluid medium. Of the

Temperature sensor has a sensor body and a in the fluid medium

protruding measuring head. For example, the sensor body may be designed to be substantially cylindrical and into the measuring head ends, or the measuring head may be applied to the sensor body at the end facing the fluid medium. At least one sensor element for detecting a temperature of the fluid medium is received in the measuring head. The sensor element can be, for example, one or more of the temperature sensors described above, for example an electrical sensor element, for example a

Temperature measuring resistor, a resistor with a negative temperature coefficient, a resistor with a positive temperature coefficient, a thermocouple

(For example, based on the Seebeck effect thermocouple) or another type of sensor element. Alternatively or additionally, a plurality of sensor elements may also be accommodated, for example a plurality of sensor elements in the measuring head and / or also at other locations within the device. In addition to the at least one sensor element for detecting the temperature, further sensor elements can be accommodated, for example one or more sensor elements for detecting a pressure of the fluid medium. Various configurations are possible.

The sensor element is received in the measuring head in such a way that it is at least largely decoupled thermally from the sensor body. This means that the heat transfer from the sensor element to the sensor body should be lower than within a same transmission path within the sensor body itself. Furthermore, the heat transfer from the sensor element to the sensor body can be configured such that it is less than a heat transfer from the sensor body

Sensor element to the surrounding fluid medium. Under a heat transfer is Generally, a heat transfer in one direction or in the reverse direction or bidirectional to understand. In particular, the at least substantial thermal decoupling can be configured such that a

Heat transfer in the axial direction, i. along an axis of an elongate temperature sensor, at least at the transition between the measuring head and the

Sensor body, less than a heat transfer in the radial direction, that is perpendicular to the axis of the temperature sensor.

The thermal decoupling of the sensor element from the sensor body can be done in various ways. In particular, at least one insulating element arranged between the sensor element and the sensor body can be provided. This insulating element can be designed in one piece or also in several parts and is designed to suppress a heat transfer between the sensor element and the sensor body. By way of example, the suppression can be configured by at least a factor of 2, preferably by at least a factor of 10 or even by at least a factor of 100, compared with a configuration without such an insulation element. The insulation element may comprise, for example, an element with low thermal conductivity, in particular an insulation layer and / or an insulation sleeve. Alternatively or additionally, the insulation element may also comprise one or more gaps, which may be filled with a gas (gas gap), for example an air gap and / or a gap filled with an inert gas.

The measuring head may be at least partially surrounded by a thermally conductive protective sleeve. Under a protective sleeve is an element to understand that in the

Is designed substantially sleeve-shaped, which, however, may also have one or more openings and which ensures a protective effect against, for example, mechanical loads and / or media influences from the outside. The protective sleeve can be made for example of a thermally conductive material. For example, this may be a plastic material and / or a metallic material. The protective sleeve can in particular be made thin-walled, for example with a wall thickness of less than 1 mm.

In particular, the wall thickness may be less than a wall thickness of a jacket of the sensor body. As thermally conductive materials, for example, metals, in particular metal sheets, can be used, or even thermally conductive

Plastics, such as plastics, for improving the thermal conductivity with a thermally conductive filler such as a metallic filler and / or a ceramic filler are filled. However unfolded plastics can also be used in principle, in particular if the wall thickness of the protective sleeve is made as small as possible. The measuring head can in particular compared to the sensor body a smaller

Have diameter. In the case of a round configuration of the measuring head and / or of the sensor body, the term "diameter" is the actual one

Diameter, for example, perpendicular to an axis of the temperature sensor to understand. If a non-round design is provided, then takes the place of the actual diameter, a dimension which the extension in lateral

Direction, for example, perpendicular to the axis of the temperature sensor, characterized. For example, this may be a characteristic edge length, a diagonal or the like. For example, at the transition between the sensor body and the measuring head, a shoulder may occur in which the diameter of the temperature sensor is reduced. Other embodiments are possible. In this way, the thermal coupling between the sensor element and the surrounding fluid medium can be further increased.

In particular in the region of the sensor element in the radial direction to improve heat exchange between the sensor element and the fluid medium, that is, for example, in a direction perpendicular to an axis of the sensor element, the measuring head can be configured at least largely gap-free. This may mean, for example, that no gaps with a gap width of more than 500 μm, preferably no gaps of more than 100 μm, occur in this radial direction. This gap-free configuration can be configured for example by a positive connection and / or by a material connection in the region of the measuring head. For example, the sensor element may be incorporated in a form-fitting manner in further elements of the measuring head, for example in a form-fitting manner in the protective sleeve and / or in a form-fitting manner in a coupling element to be described in more detail below. This positive connection can be effected, for example, with the aid of a melt bead, via which the sensor element is introduced substantially without gaps into the measuring head, for example into the coupling element and / or into the protective sleeve. Various

Embodiments will be described in more detail below. Alternatively or additionally, a positive insertion can also take place, for example by a

Press fit is used. Thus, for example, the coupling element and / or the sensor element can be accommodated in the measuring head by a form fit, for example by a press fit in the protective sleeve and / or by a Positive fit and / or by at least one filler material (for example, a thermal paste and / or a liquid, for example, a liquid metal).

As already mentioned several times above, the sensor element can in particular be accommodated at least partially in at least one coupling element, wherein the

Coupling element may be configured to heat exchange between the sensor element and the fluid medium (which may include both transmission directions) compared to a heat exchange between the

Sensor element and the sensor body to favor. This can for example be done by a coupling element with a particularly high thermal

Conductivity is used at least in the radial direction, ie in the direction of immediate exchange with the fluid medium. The coupling element may for example be designed as a sleeve or comprise a sleeve. The

Coupling element may be configured in particular thermally decoupled from the sensor body, for example, the at least one optional, above-described insulation element and / or another type of insulation element of the described embodiments may be used. For example, the coupling element can also be separated from the sensor body by at least one gas gap, for example an air gap, and / or by one or more thermally insulating material layers.

In particular, the coupling element may comprise a material having one or more of the following properties: a material having a density less than the average density of the materials of the sensor body in an area of the sensor body adjacent to the measuring head; a material with a lower specific heat capacity than the average specific heat capacity of the materials of the sensor body in an area adjacent to the sensor head

Sensor body; a material with a higher thermal conductivity than the average thermal conductivity of the materials of the sensor body in an adjacent to the measuring head region of the sensor body. Various other embodiments of the coupling element are possible or combinations of the above or other options.

The coupling element may in particular be selected from one or more of the following coupling elements: one the sensor element at least partially

enclosing sleeve of a ceramic material, in particular a ceramic material with high thermal conductivity and / or high thermal diffusivity; a sleeve at least partially surrounding the sensor element made of a plastic material, in particular a plastic material with high thermal conductivity; a sleeve at least partially surrounding the sensor element made of a metallic material, such as an iron material, an aluminum material or a copper material; one that

Sensor element at least partially enclosing the melted bead, in particular a melted bead of a plastic material and / or a melted bead of a metallic material and / or a melted bead of a glass material (wherein the melted bead in all cases can also be part of the sensor element itself); a filling material in a space between the

Sensor element and the measuring head at least partially enclosing

Protective sleeve.

In order to improve the thermal coupling and to improve the heat transfer between the measuring head or the sensor element and the surrounding fluid medium, furthermore, the surface facing the fluid medium, for example a flow of the fluid medium, can have at least one turbulator element. A turbulator element is to be understood as meaning an element which is set up in order to be introduced into a flow of the fluid medium

Temperature sensor an envelope from a laminar flow to a turbulent one

To cause flow on the surface. By inducing turbulence, in contrast to conventional laminar flow around the temperature sensor, mixing of surface-near layers of the fluid medium with layers of the fluid medium removed from the surface is effected. As a result, an improved temperature exchange of the fluid medium with the measuring head and thus with the sensor element is effected, which overall significantly improves the connection and the dynamics of the measurement. The known from US 2007/0195857 AI ribs, which are aligned in the vertical introduction of the sensor described therein in the flow of the fluid medium parallel to the flow of the fluid medium, however, cause no such turbulence and thus no corresponding

Mixing and therefore do not have the advantages described.

In particular, the turbulator element may comprise a microstructure which comprises a plurality of structural elements, that is, elevations or depressions in the surface. The structural depth of the structural elements, that is to say a maximum elevation or minimum depression of the structural elements, can not be 50 μm exceed, more preferably 10 μηη. An average structure depth of the

Structural elements may in particular be 0.5 to 5 μm, preferably 1 to 2 μm.

The turbulator element may be configured in various ways to provide a turbulent flow and / or an early transition from a laminar flow

Boundary layer flow to cause a turbulent boundary layer flow. For example, the turbulator element may be selected from: elevations, wherein at least one of the elevations is impinged by the fluid medium in such a way that the elevation acts as a turbulator element; Wells, wherein at least one of the wells is flowed by the fluid medium in such a way that the depression acts as a turbulator element. The turbulator element may for example be selected from: a wire, in particular a tripwire, preferably a

Wire basket with multiple tripping wires, which can for example completely or partially enclose the measuring head; a needle, in particular a conical (blunt or pointed) or rounded tapered needle, in particular a plurality of needle-shaped or pointed elevations; a wedge-shaped

elongated elevation, that is a survey with a sharp, extending into the fluid medium into the edge, which is overflowed by the fluid medium, in particular a plurality of substantially axially parallel aligned wedge-shaped elevations; an elongated recess, in particular a groove or groove with a rounded and / or angular profile; a point-shaped elevation, in particular a survey with a round or angular cross-section, in particular a plurality of punctiform elevations; a punctiform depression, in particular a depression with a round or angular cross-section, in particular a plurality of punctiform depressions or a golf ball pattern; a grid with several intersecting elevations; a grid having a plurality of intersecting recesses; a honeycomb pattern; a knurl, in particular a knurl with paraxial grooves, a right knurl, a left knurl, a left-right knurl or a cross knurl; a tear-off edge, in particular a tear-off edge with an angle of at least 30 °; a diamond-shaped

survey; a diamond-shaped depression; a pyramid. In particular, the turbulator element may comprise a grid having at least two, preferably a plurality of, mutually crossing elongated structural elements. For example, a first type of structural elements may be provided, which in one direction

elongated and a second type aligned in a second direction such that the first and second types of structural elements intersect at a plurality of crossing points. The measuring head may in particular have a substantially rounded shape. Alternatively or additionally, however, the measuring head can also have a

have cylindrical and / or stepped shape. If the measuring head is substantially rounded, then the turbulator element can be arranged, for example, in the region of the rounding off. It can in particular a plurality of several

Be provided turbulator elements. For example, several

Turbulator elements may be arranged with a symmetry to an axis of the temperature sensor. For example, this may be an N-count

Rotational symmetry act around the axis of the temperature sensor. The

Turbulator element may be configured in particular as an interrupted turbulator element and comprise a plurality of structural elements. The structural elements can in particular be arranged such that the inflowing fluid medium experiences a repeated stall at the structural elements.

Brief description of the figures

Embodiments of the invention are illustrated in the figures and are explained in more detail below description.

In detail show:

Figure 1 shows different installation situations conventional temperature sensor; FIGS. 2A to 2C show flow conditions and thermal conditions above a surface overflowed by a fluid medium;

Figure 3 shows various mechanisms of heat exchange in the range of a temperature sensor;

Heat exchange of a sensor element of a temperature sensor with the environment;

FIGS. 5A to 5H different embodiments of a measuring head of a

inventive temperature sensor; Figures 6A to 6G different embodiments of a measuring head of a

Temperature sensor with a knurl;

FIG. 7 shows a typical structure of a measuring head of a temperature sensor with a sensor element;

FIGS. 8A and 8B show different views of a device according to the invention

Embodiment of a temperature sensor; and

Figures 9 and 10 further embodiments of an inventive

Temperature sensor.

embodiments

In the following, various embodiments of devices 110 for detecting a temperature of a fluid medium will be described. The fluid medium can be, for example, a gas which flows through a flow tube 112 according to FIG. For example, this may be an exhaust gas of an internal combustion engine. In this case, two different installation situations of a

Temperature sensor 114 of the device 110 according to the invention shown in the flow tube 112. The reference number 116 indicates the direction of flow of the fluid medium, that is to say the direction of the flow and / or the direction of the main mass transport on fluid medium through the flow tube 112.

FIG. 1 shows once an angled temperature sensor 114 which is currently being installed in the flow tube 112 (left temperature sensor 114 in FIG. 1) and a temperature sensor 114 (right

Representation), which can be installed at a curvature of the flow tube 112 against the main flow direction 116 in the flow tube 112.

The temperature sensors 114 are usually rod-shaped, as shown in FIG. 1, and are brought into contact, for example, with the fluid medium in the manners illustrated in FIG. Through various mechanisms of heat transfer, such as convection and / or heat conduction and / or radiation, the temperature sensor 114 is supplied with energy or energy dissipated by this, whereby it assumes a temperature similar to the fluid temperature. Within the temperature sensor 114 each have a sensor element is arranged (not visible in Figure 1), in which it is for example a thermocouple, a NTC (negative temperature coefficient resistor), a PTC (positive temperature coefficient resistor), a common thermal resistor, or a similar sensor element, which sensor element can produce a temperature associated signal, such as an electrical signal, due to its thermophysical properties. This is preferably further processed in an optionally connected electronics, which is not shown in Figure 1 and which may also be part of the device 110 or which may also be configured as external electronics. The installation possibilities of the temperature sensors 114 shown in FIG. 1 are used, for example, in plant construction. The plants are usually operated in quasi-stationary operating conditions, and the temperatures hardly change, and if changes should occur, they take place relatively slowly. In contrast, the measurement of the temperature of exhaust gases, for example from thermal piston or turbomachinery, for example, for reasons of component protection usually very high demands on the measurement and thus also on the temperature sensor 114. The two main demands of such

Temperature sensor 114, for example for use in motor vehicle technology, usually consist of a high measuring accuracy, that is to say a low one

Deviation between the actual fluid temperature and temperature indicated by the temperature sensor 114, and high dynamics. High dynamics in this context means the possibility of rapid changes in the gas temperature with the temperature sensor 114 with the least possible delay and higher

To resolve accuracy. In addition, in many cases a free choice of installation position or installation position is desired. From a technical point of view directed installations such as the curved embodiment shown in Figure 1 are undesirable.

In most cases, an installation perpendicular to a pipe wall 118 of the flow tube 112 at the installation site in a straight version of the temperature sensor 114 is required or desired. Inaccuracies in the temperature measurement and low dynamics lead to a high application cost or even to the exclusion of the measuring method for certain applications. By appropriate design measures on

Temperature sensor 114, the accuracy and the dynamics can be increased according to the invention. This is to be shown in the context of the following

Embodiments of inventive devices 110 and temperature sensor 114 will be explained. In exhaust systems, due to the high temperatures, there is usually an increased energy exchange through convection and radiation between the exhaust gas

Exhaust system, the built-in temperature sensor 114 and the environment. The heat output of the hot temperature sensor 114 as a sensor to the colder environment or in the reverse case, the heat absorption from the hotter

Environment results in a systemic deviation of the temperature displayed by the device 110 from the actual fluid temperature. Likewise, this heat dissipation or heat absorption leads to a delayed response of the device 110. By deliberately influencing the energy transport, the heat transfer and / or the heat absorption to the environment or from the

Reduced environment and the heat absorption or heat output to the actual sensor element can be increased. This increases both the measurement accuracy and the dynamics of the temperature measurement. FIG. 3 schematically shows the installation situation of a temperature sensor 114 and the occurring energy flows. Shown here is an embodiment of a temperature sensor 114, which has a on a passage 120 with fixation 122, for example, a screw, preferably with sealing effect, performed by a tube wall 118 of a flow tube 112 sensor body 124. In this exemplary embodiment, the sensor body 124 is oriented substantially perpendicular to a tube axis 126 of the flow tube and / or substantially perpendicular to the tube wall 118. The sensor body 124 opens into a rounded measuring head 128, which in this embodiment connects seamlessly to the sensor body 124 and is integrally formed therewith. However, other embodiments are possible, for example embodiments in which the measuring head 128 is configured offset from the sensor body 124. In the measuring head 128, a sensor element 130 is recorded for detecting the temperature of the fluid. The sensor element is shown in an enlarged view in FIG.

The energy flows that occur in the heat transfer are characterized in Figures 3 and 4 each with arrows. Reference numerals 132 denote convective heat transfers, reference numerals 134 heat transfer by conduction, and reference numerals 136 heat transfer by radiation. Furthermore, different temperatures are designated in FIG. 3, namely with Tu the temperature of the environment, with T _{w> a} the temperature of the pipe wall 118 on the outside, ie the side facing away from the fluid medium, with T _w , i the temperature on the Inside the pipe wall 118, ie on the side facing the fluid medium, with T _A, the temperature of the exhaust gas or the fluid medium, with T _K, the temperature of the temperature sensor 114 in the region of a cable outlet and T _s, the temperature of the temperature sensor 114 at the Tip, in the region of the measuring head 128.

If the exhaust gas temperature is higher than the sensor temperature or T _s , then heat transfer usually takes place by convection of the exhaust gas in the temperature sensor 114 over the entire outer surface of the protruding into the exhaust gas temperature sensor 114. In the region of the attachment of the temperature sensor 114 in the pipe wall 118, this has a good thermal contact with the pipe wall 118. Due to heat conduction, heat dissipation into the pipe wall 118 takes place. Because the

Wall temperature is usually lower than the exhaust gas temperature, heat is transported by conduction in the axial direction of the temperature sensor 114. There is also at best a radiation heat exchange between the hotter lateral surface of the

Temperature sensor and the colder inner wall of the flow tube 112 instead (see a) in Figure 3). The environmental portion of the temperature sensor 114 typically undergoes convective cooling by the lower ambient temperature, as well as heat input by radiation exchange with the hotter outer wall of the flow tube 112 (see b) in FIG. 3). Possibly carry further, external

Radiation sources (e.g., hot surfaces of an exhaust turbocharger, catalyst or the like) additionally add energy (see c) in Figure 3). By heat conduction continues to be an energy transport in the direction of an axis 138 of the temperature sensor 114 toward the cable outlet instead.

In the case of a rapid change to cold exhaust gas heat transfer takes place by convection of temperature sensor 114 to the fluid medium or the exhaust gas, usually over the entire outer surface of the exhaust sensor projecting into the exhaust gas 114. In the region of the attachment or fixing 122 of the temperature sensor 114th In the pipe wall 118, heat flows from the still hot pipe wall 118 in the

Sensor body 124 of the temperature sensor 114, which may also be configured as a shaft, in the direction of the position of the sensor element 130 after. There is also radiation heat exchange between the colder surface of the temperature sensor and the now hotter inner wall of the exhaust pipe instead. The protruding into the environment part of the temperature sensor 114 continues to experience a convective cooling by the lower ambient temperature and a supply of heat through

Radiation exchange with the hotter outer wall of the flow tube 112. Eventually contribute additional external radiation sources (for example, hot surfaces of exhaust gas turbochargers, catalysts or the like) in addition to energy. Due to the heat conduction energy transport continues to take place in the direction of the axis 138 of the temperature sensor 114 toward the cable outlet.

FIG. 4 schematically shows the energy flows in the region of the sensitive tip of the temperature sensor 114. The actual sensor element 130 experiences a supply and / or dissipation of heat, which are influenced by the ambient conditions and the constructive connection of the sensor element 130 to the temperature sensor 114. Once a stationary state is reached, the incoming and outgoing energy flows are in equilibrium, and the sensor element 130 maintains a constant temperature. This usually corresponds to the temperature determined by an evaluation of the device 110. However, it is not identical to the gas temperature, which causes a system-related measurement error.

To increase the measurement accuracy and the dynamics of the device 110, the principle that the energy supply to the sensor element 130 or the

Energy removal from the sensor element 130 in the radial direction, ie perpendicular to the axis 138, must be as fast as possible, whereas the energy supply to

Sensor element 130 or the energy dissipation from the sensor element 130 in the axial

Direction, ie parallel to the axis 138 of the temperature sensor 114, must be prevented as possible. This ensures that the sensor element 130 detects a change in the temperature as quickly as possible and the temperature of the sensor element 130 deviates as little as possible from the temperature of the fluid medium. The minimization of the energy flows in the axial direction can be technically realized, for example, by a thermal decoupling of the sensor element 130 or the measuring head 128 from the sensor body 124, for example from the shaft of the temperature sensor 114, via an air gap or an insert of a material with low thermal conductivity. This will be explained in more detail below. In the radial direction, however, is a good thermal connection of the sensor element 130 to the fluid

Medium and, for example, a wall of the temperature sensor 114 or a

Minimization of air gaps to realize. To increase the radial

Energy transport of the ideally thermally decoupled from the sensor body 124 tip or the measuring head 128 of the temperature sensor 114 carries among other things a

Minimizing the mass and the specific heat capacity of the system, in particular the measuring head 128, and maximizing the Heat transfer coefficient and the area available for heat transfer at.

The constructive design of the temperature sensor can afford the following contributions.

A) Thermal decoupling of the sensor element 130 from the sensor body 128, for example by

Air gap insulation and / or

- An insulating, for example, a layer of material with less

Thermal conductivity and / or

a small wall thickness of the protective sleeve 140 surrounding the sensor element 130; and / or B) minimizing the mass and / or specific heat capacity of the

Temperature sensor 114, in particular of the measuring head 128, and / or an improvement of the energy transport in the solid of the temperature sensor 114, in particular of the measuring head 128, for example by:

Reducing the dimensions of the sensor element 130 and / or the temperature sensor 114 in the region of the installation of the

Sensor element 130 and / or

Use of materials in the vicinity of the sensor element with low density and / or low specific heat capacity, but with high thermal conductivity; and or

C) Maximize the heat transfer between the sensor element 130 and the fluid medium, for example by improving the thermal coupling to the fluid medium, by increasing the

Heat transfer coefficient and / or by increasing a surface 142 of the temperature sensor 114 in the region of the measuring head 128, for example by:

Cl) enlargement of the heat transfer surface 132, as described for example in US 2007/0195857 AI, and / or

C2) Enlargement of the heat transfer coefficient by disturbance of the heat transfer coefficient

Construction of a laminar hydrodynamic and thermal

Boundary layer by using one or more Turbulator elements on the temperature sensor 114, in particular the measuring head 128th

The measures to influence the boundary layer according to C2) usually aim at two effects. On the one hand, the envelope should turn into a turbulent boundary layer as early as possible, i. done after a short run length. Serve for this purpose turbulator elements, which are shown by way of example in Figures 5A to 5H and 6A to 6G and designated there by the reference numeral 144. These turbulator elements 144 are respectively applied to the surface 142 of the measuring head 128 and incorporated therein and comprise various types of structural elements 146, ie elevations of the

For example, FIG. 5A shows a turbulator element 144 in the form of a wire basket with tripping wires, FIG. 5B shows an embodiment of a turbulator element 144 in the form of protruding ribs with an additional wire basket over the rounding of the measuring head 128, FIG. 5C 5D shows an exemplary embodiment with elevations which run in the form of sharp edges parallel to the axis 138 of the temperature sensor 114 and act as "trip hazards", FIG. 5E shows an embodiment with demarcation edges through an angular shape of the measuring head 128, FIG. FIG. 5F shows an exemplary embodiment with grooves with a round cross section or an angular cross section in an otherwise rounded measuring head 128, FIG. 5G shows an exemplary embodiment with punctiform, circular depressions (golf ball pattern) in an otherwise rounded measuring head 128, and FIG. 5H

Embodiment with a grid of crossed grooves, which may for example be configured as "negative" of the wire basket according to FIG 5A. Alternatively or additionally, the structural elements 146 of the turbulator element 144 may also include, for example, diamonds, needles, pyramids, other types of tear-off edges, or generally polygonal shapes.

The measures with the at least one turbulator element 144 can

For example, be integrated into the devices 110 according to Figures 1, 3 and 4. The measures to influence the boundary layer usually aim at two effects. On the one hand, the envelope should turn into a turbulent boundary layer as early as possible, i. done after a short run length. Serve this purpose

Turbulator elements 144, which may include, for example, small obstacles, depressions, surface roughness or the like. On the other hand, the

Boundary layer structure as possible constantly new, since the heat transfer is particularly high. This is interrupted, for example, by appropriately Ridges, needles or other forms reached, each representing a new flow of a separate body with a corresponding boundary layer structure.

The principle of boundary layer influencing is explained in FIGS. 2A to 2C. FIG. 2A shows the formation of a fluid-dynamic boundary layer when a surface 142 flows over in the form of a flat plate. The fluid adheres to the solid wall. With increasing run length, starting at a plate leading edge 148, the flow rate increases continuously to the value in the free flow. It forms a laminar boundary layer 150, which increases with increasing run length. Within this laminar boundary layer 150 there is a

Layer flow before, i. it finds - in contrast to the mostly turbulent ones

Outside flow - no cross-exchange of momentum and energy with direction perpendicular to the surface 142 instead. Upon reaching a critical run length N _crit , an envelope of the boundary layer state takes place. It forms a turbulent boundary layer 152, which continues to grow. Within this is an exchange of momentum, mass and energy transverse to the main flow direction 116 due to the turbulent flow

Fluctuation speeds possible. In the vicinity of the surface 142, a laminar lower layer 154 forms, which is, however, substantially thinner than the previous laminar boundary layer.

Analogous to the fluid dynamic boundary layer, as shown in FIG. 2C and in FIG. 2B the fluid dynamic boundary layer is compared, a thermal boundary layer is formed. For these, the same laws apply as for the fluid dynamic boundary layer shown in Figure 2B. Within the laminar boundary layer heat transfer takes place only by heat conduction through the layers

Direction of the wall instead. The fluid-dynamic boundary layer thickness is denoted by δ in FIG. 2B, whereas the thermal boundary layer thickness in FIG. 2C is designated by δ _τ . The core flow is designated by the reference numeral 156. The thicker the boundary layer grows, the smaller the transferable heat flow. With the transition into a turbulent boundary layer, an increase in the transferred heat flux sets in, since the laminar underlayer is thinner than the laminar boundary layer and because the turbulent fluctuation rates constantly convey fluid medium at a higher temperature into the vicinity of the wall. The embodiments of turbulator elements illustrated in FIGS. 5A to 5H

144 on the surface 142 of the temperature sensor 114, in particular in the region of the measuring head 128, thus cause an earlier transition into a turbulent Boundary layer and a constantly new structure of the boundary layer. As a result, the heat transfer is designed to be particularly high. The temperature sensors 114 are preferably used such that the flow direction 116 of the fluid medium extends transversely to at least one edge of a turbulator element 144. This is given in all of the embodiments shown in Figures 5A to 5H. Furthermore, the turbulator elements 144, as known from US 2007/0195857 AI, additionally increase the surface available for the heat transfer, in addition to increasing the heat transfer coefficient by influencing the boundary layer structure according to FIGS. 2A to 2C. The options for shaping the surface 142 shown here correspond in part to the patterns used on an industrial scale to increase the

Heat transfer in stationarily operated heat exchangers, for example in plant construction, air conditioning or the like. However, these have hitherto been used only to increase the efficiency of heat exchangers, but not to increase the dynamics and / or the measurement accuracy of temperature sensors. A

Overview of further shaping possibilities of the turbulator elements 144 can be found, for example, in Ralph L. Webb: "Principles of Enhanced Heat Transfer", John Wiley & Sons, Inc., 1992, p. 231, 241 and 248. The heat transfer coefficient in the case of a circulated body therefore depends on as explained above, both from the geometry and surface structure of the body as well as from the Umströmungsbedingungen. The turbulator elements 144 in the illustrated embodiments are preferably constructed as a microstructure and preferably have a tread depth, i. a maximum depth or height of the

Structural elements 146, of at most 10 μηη, in particular 1 to 2 μηη on. As such, an artificial surface roughness may be provided by the turbulator elements 144 having the structural members 146 in the form of a microstructure that provides for permanent disturbance of the hydrodynamic and thermal boundary layers. This leads to an increase in the heat transfer coefficient due to the thus increased pulse and energy exchange. The artificial surface roughness in the form of turbulator elements 144 is characterized in that their

characteristic height is small compared to the remaining dimensions of the temperature sensor 114, in particular of the measuring head 128. Thus, the typical widths of the structural elements 146 and / or their heights can be, for example, around

at least a factor of 10, preferably at least a factor of 100 and even at least a factor of 1000 smaller than the diameter of the measuring head 128 perpendicular to the axis 138 of the temperature sensor 114. In addition, the roughness by a suitable design of the structural elements 146 both from the surface 142 to the outside (eg in the form of the trip wires or needles according to the

Embodiments in Figures 5A to 5D) as well as inwardly (e.g., in the form of grooves, dents, grooves, or the like, for example, in accordance with Figs

Embodiments in Figures 5F to 5H) be directed.

A further exemplary embodiment of a turbulator element 144 according to the invention in the region of a measuring head 128 of a temperature sensor 114 is shown in FIG. 6A. Here, the turbulator element 144 comprises a knurl 158. Under a knurl is to understand a profile structure having a plurality of parallel grooves. In this case, at least one group of grooves should have a transverse component perpendicular to the main flow direction 116 of the fluid medium. Embodiments of these knurls are shown in FIGS. 6B to 6F. Thus, Figure 6B shows a knurl with axially parallel grooves, which are preferably aligned completely perpendicular to the flow direction 116 of the fluid medium. A cross-section through the grooves is shown in FIG. 6G. In this case, the letter t denotes standardized divisions, which may be, for example, 0.5, 0.6, 0.8, 1.0, 1.2 or 1.6 mm, di denotes a nominal diameter, and d ₂ an initial diameter. For example, in the case of the knurl according to FIG. 6B:

FIG. 6C shows a so-called right knurl. The angle α between the axis 138 and the grooves may, for example, be from 10 to 50 °, preferably from 20 to 40 ° and in particular 30 °, and it may be: d ₂ = di - 0.5 ^■ t. The same applies to a so-called left-hand knurl shown in FIG. 6D. FIG. 6E shows a so-called left-right knurl, for which the angle α can likewise be from 10 to 50 °, in particular from 20 to 40 and particularly preferably 30 °. For example, for an increased left-right knurl, d ₂ = di-0.67 ^■ t, and for a recessed left-hand knurl, d ₂ = di-0.33 ^■ t.

Finally, FIG. 6F shows a so-called cross knurl, with a plurality of grooves parallel to the axis 138 and a plurality of grooves running perpendicular to the axis 138. For an increased cross knurl, for example, d ₂ = di - 0.67 ^■ t and for a recessed cross knurl d ₂ = di - 0.33 ^■ t. The grooves may, for example, have a groove angle β, which is also shown in FIG. 6G. This groove angle can be, for example, 70 ° to 110 °, in particular 80 ° to 100 ° and particularly preferably 90 °. However, other embodiments are at least possible. In any case, those shown in Figures 6B to 6F

Turbulator elements 144 in the form of knurls 158 are each given components perpendicular to the flow direction 116 of the fluid medium. In particular, in the case of a left-right Rändeis according to Figure 6E or in the case of Kreuzrändeis according to Figure 6F, the roughness are also directed perpendicular or at an angle to the flow.

As shown above, the concepts A), B) and C) are independent of each other or in any combination A-B, A-C, B-C or A-B-C feasible. Thus, the configurations shown in FIGS. 5A to 6G with turbulator elements 144, which represent possibilities of realization of the concept C), can also be combined with the concepts B) and / or C), which, incidentally, can also be implemented independently of A). Embodiments of the concepts B) and / or C) will be briefly described below. For this purpose, should be based on a schematic

Representation in Figure 7 shows a typical structure of a temperature sensor 114 according to the

State of the art will be explained briefly. The temperature sensor 114 in turn has a sensor body 124, which in this case merges seamlessly into a measuring head 128 with a sensor element 130. The sensor element 130 is configured in this case, for example, as a thermocouple and is formed by the connection of two metallic conductors 160 made of different materials, which on a

Measuring point 162, which forms the actual sensor element 130, are interconnected. The connected conductors 160 (thermal conductors) are also referred to as thermocouples. The connection of the thermal conductors acting as metallic conductor 160 is generated for example by welding and / or soldering. The metal combinations of the metallic conductors 160 for thermowires are typically standardized so that various types of thermocouples are known in the art. The size of the diameter of the thermocouples 160 correlates with the cost and typically the life of the thermocouple. The typical temperature sensor 114 shown in FIG. 7 is a so-called

Sheathed thermocouple. The thermal conductors 160 are typically embedded in a ceramic insulating package 164, such as MgO and / or Al ₂ O ₃ . Outwardly, the electrically insulated thermocouple is through a jacket 166 with a

Sheath material, such as stainless steel and / or ceramic, protected from the environment. Sheath thermocouples as exemplified in Figure 7

Temperature sensor 114 with metallic sheath are usually made of a so-called mineral insulated line (MIL), which in almost any Material combinations with respect to the thermal lines 160, the insulating material of the insulating 164 and the jacket material of the shell 166 and in different defined dimensions, especially in diameter, shell thickness, thickness of the thermal cables 160 or similar dimensions, can be obtained as endless. It is usually important to note that the maximum

Operating temperature of the jacket thermocouple depends on the jacket and cable diameter and the insulation resistance of the mineral insulator. When manufacturing the MIL is cut to length and mineral at one end

Insulating removed to expose the actual thermoelectric lines 160. The exposed wires are welded to the measuring point, and the missing

Insulating material is replenished and compacted. Subsequently, the jacket tube of the shell 166 is closed at the same end, for example by welding. At the other end, so at the opposite end of the measuring head 128 of the temperature sensor 114, a piece of the jacket tube is removed to the

Thermo cables 160 expose as connecting wires, for example for a

Plugs, crimps or similar.

The above-described concepts A) to C) for improving the thermal configuration of the temperature sensor 114 can be individually, in any desired

Pair combination or total, in principle also on temperature sensor 114 with

Thermocouples transmitted analogously to the embodiment according to Figure 7, in which the actual sensor element 130 is formed by a junction between at least two metallic conductors 160 and / or thermocouples. Thus, for example, the configurations of the surface 142 in the region of the measuring head 128 can be achieved by using one or more turbulator elements 144

Embodiment transferred. Alternatively or additionally, the concepts A) and / or B) can also be transferred to this concept of the temperature sensor 114. This will be shown below by way of example. For example, the sensor element 130 may be received in the measuring head 128 in such a way that it is at least largely thermally decoupled from the sensor body 124. This means that a heat transfer between the sensor element 130 and the surrounding fluid medium by constructive

Embodiment of the measuring head 128 is favored, in particular in comparison to a heat transfer to the sensor body 124, which is preferably suppressed. This can be done, for example, by a structural design adaptation at the measuring point 162. An energy exchange by convection and radiation and so that the heat transfer between a built-in device 110 sensor element 130 and its surroundings and the height of the occurring

Temperatures (especially due to an influence of radiation from

Temperatures above 500 ° C) lead to a systemic deviation of the measured temperature and the actual prevailing temperature in the medium.

In addition, the heat transfer or the heat exchange cause a delayed response of the temperature sensor 130 at the measuring point 162. By means of the concepts A) to C) described above or at least the concepts A) and / or B), the accuracy and the dynamics can be increased. Thus, the energy supply to the measuring point 162 or the energy dissipation from this measuring point 162 in radial

Direction, ie perpendicular to the axis 138, are designed very fast. As a result, the temperature change in the entire medium with minimal temporal

Delay transferred to the measuring point 162. Alternatively or additionally, the energy supply to the measuring point 162 or the sensor element 130 (which

should be synonymous) and / or the energy dissipation from the measuring point 162 in the axial direction, ie parallel to the axis 138, prevented or at least reduced. The temperature difference between the measuring point 162 and the fluid medium remains as small as possible. These basic principles and aspects derived therefrom can be realized, for example, in the exemplary embodiments presented below. Such is an embodiment of an inventive

Temperature sensor 114 and a part of a device 110 according to the invention in the figures 8A (partial sectional view from the side) and 8B (partially opened perspective view) shown. Again, this is an example of a jacket thermocouple with the MIL structure described above with reference to FIG. 7, with a sensor body 124 and a measuring head 128. The thermoelectric lines are again designated by the reference numeral 160. The actual sensor element 130 is again formed by a connection of the conductors 160 at a measuring point 130, which may also be a more extensive measuring range. The sensor element 130 is in this embodiment of a coupling element 168 in

Surround form of a ceramic sleeve 170 and a ceramic tube. The

Coupling element 168 in turn is surrounded by a thin-walled, preferably thermally conductive protective sleeve 172 or protective cap, which provides a mechanical protection for the sensor element 130 and fixes the measuring head on the sensor body 124. The protective cap can on the end face of the temperature sensor 114th

closed or at least partially open configured. The

Protective cap can for example be made of a plastic material with high thermal Conductivity and / or a metallic material to be made. Optionally, on the outer surface 142 of the protective sleeve 172, one or more

Turbulator elements 144 may be arranged, for example according to the above

described embodiments, which are not shown in Figures 8A and 8B.

The completion of the temperature sensor 114 shown in FIGS. 8A and 8B differs from the prior art described in FIG. 7 as follows. After cutting the MIL to length, a length of the jacket tube 166 is removed and the thermal lines 160 are exposed. The thus exposed metallic

Conductors 160 are preferably nipped and / or pressed together, for example, to create a planar contact between the conductors 160. Subsequently, the MIL with compacted measuring point 162 and the protective sleeve 172 with pressed-ceramic tube or pressed-ceramic sleeve 170, as shown in Figures 8A and 8B, joined. Towards the MIL, the protective sleeve 172 is connected to the jacket 166 of the MIL, for example by welding.

As illustrated above, an end face 174 of the measuring head 128 can be opened or also designed to be closed. At an open end face 174, as shown in Figure 9 as an optional embodiment, with the aid of, for example, a suitable

Welding process such as a laser welding, a melt bead 176 are generated, which may also be part of the coupling element 168. In this way it can be achieved, for example, that a substantially gap-free transition, for example in the form of a positive connection 178, arises between the sensor element 130 or the measuring point 162 and the ceramic tube of the ceramic sleeve 170. Thus, a gap-free transition between the sensor element 130 and the coupling element 168 and preferably also the protective sleeve 172 can be generated. Furthermore, in order to reduce a thermal conductivity in the axial direction, between the sensor element 130 and the sensor body 124 at least one

Isolation element 180 may be arranged. In the illustrated exemplary embodiments according to FIGS. 8A to 9, this may be, for example, an air gap 182. Alternatively or additionally, other types of

Isolation elements 180 are used, for example, one or more

Layers of a thermally insulating material, one or more

Insulating sleeves or the like. In this way, a heat transfer in axial

Direction be reduced. The end face 174 of the temperature sensor 114 according to FIGS. 8A to 9 can be closed. For this purpose, for example After the process steps described above, the protective sleeve 172 are welded to the end face 174 with a lid, or the protective sleeve 172 can be configured from the outset as a closed protective sleeve. For example, by the manufacturing method described in Figures 8A to 9, but also by means of other embodiments of the present invention, the above-described basic principles A) and / or B) can be implemented constructively well. Thus, good heat conduction takes place in the radial direction, ie perpendicular to the axis 138 of the temperature sensor 114. A good thermal connection of the sensor element 130 or the measuring point 162 to the fluid medium is achieved by reducing, for example, the air gaps in the radial direction to a minimum. This is achieved, for example, in the exemplary embodiments described above with the aid of a positive connection and / or an interference fit between the protective sleeve 172 and the coupling element 168 and / or the sensor element 130, optionally in combination with the optional positive connection between the coupling element 168 and the above-described

Sensor element 130 via, for example, a melted bead or another type of positive connection. Additionally, optionally, the mass and / or the specific

Thermal capacity of the material of the measuring head 128 at the measuring point 162 is reduced or even minimized by suitable miniaturization and / or material selection. At the same time, alternatively or additionally, by a suitable structuring of

Surface 142 by means of the optional at least one turbulator element 144 according to strategy C) of the above options, both the area available for heat transfer and the heat transfer coefficient can be maximized. Alternatively or additionally, as described above, a thermal decoupling in the axial direction, ie parallel to the axis 138, so that a

Heat transfer between the measuring head 128 and the sensor body 124 is reduced at least in comparison with a continuous sensor body 124 in a one-piece embodiment according to FIG. This can be achieved, for example, as shown in Figure 9, by means of an air gap insulation. In addition, the wall thickness of the protective sleeve 172, for example, the protective cap can be reduced, in particular in the radial direction, for example, to wall thicknesses below 1 mm, preferably below 0.5 mm.

FIG. 10 shows a further exemplary embodiment of a device 110 according to the invention and a temperature sensor 114 according to the invention, which has a

Variation of the embodiment in Figure 9 represents. Accordingly, reference may largely be made to the above description. Again, the temperature sensor points 114 a sensor body 124 and a measuring head 128 on. As well as in the

In the above described embodiments, the measuring head 128 can also be reduced in this embodiment with a reduced compared to the sensor body 124

Diameter be configured. For example, a diameter reduction may be made to two thirds of the diameter of the sensor body 124 or less. The measuring head 128 may in turn be surrounded by a protective sleeve 173, which may in principle be formed integrally with the jacket 166 of the sensor body 124, which, however, may also be connected only to this jacket 166 or otherwise connected to the sensor body 124, for example Analogously to the embodiments in FIGS. 8A to 9, the surface 142 of this protective sleeve 172, in particular the circumferential surface 142 and / or the frontal surface 142, may in turn be structured by means of one or more turbulator elements 144. In this as well as in others

Embodiments may also include one or more additional ones between the protective sleeve 172 and the sensor body 124, for example the jacket 166

Isolator elements may be arranged. Again, the temperature sensor 114 has at least one sensor element 130 at a measuring point 162, for example according to the embodiment in FIGS. 8A to 9 or according to other embodiments. For example, NTCs, PCTs, resistors, thermocouples or other types of sensor elements 130 may be used again.

In order to achieve a high dynamic of the temperature measurement, that must

Sensor element 130 is heated as quickly as possible or cooled as quickly as possible. The amount of energy to be transported is proportional to the product of mass and specific heat capacity of the area to be cooled or heated. To keep this area as small as possible, its dimensions must be reduced. For rapid heating or cooling, this region of the measuring head 128 should, as in the preceding embodiments, be thermally decoupled from the sensor body 124, for example the shaft of the temperature sensor 114. This prevents energy from flowing into the sensor body 124 to heat up and not being available for heating, or, in the reverse case, energy flowing from the sensor body 124 and retarding the cooling of the sensing head 128 area. The thermal decoupling can also take place in the exemplary embodiment shown in FIG. 10 again via one or more insulation elements 180, for example via one or more air gaps.

In order to achieve the best possible thermal coupling between the sensor element 130 and the surrounding fluid medium, a gap between the Sensor element 130 and the protective sleeve 172 are completely or partially filled with a filler 184. This filling material 184 can be, for example, a metallic and / or ceramic filling material and / or a plastic filling material. The filling material 184 may be introduced into the intermediate space, for example in the form of a powdery filling material, and / or in another manner, for example in the form of a liquid or viscous one

Filling material 184. Subsequently, an optional hardening can take place. Also thermally conductive plastics, such as thermally conductive thermosets, elastomers or thermoplastics can be used.

The exemplary embodiments of a conversion of the concepts A) and / or B) as described above with reference to FIGS. 8A to 10 can also be combined with the embodiments of the concept C) as described above. Thus, the exemplary embodiments can be combined individually or in combination, for example, with the examples of the turbulator elements 144 according to FIGS. 5A to 6G so that these turbulator elements 144 are optionally also applied, for example, to the diameter-reduced measuring head 128 according to the exemplary embodiments according to FIGS. 8A to 10 can be. Alternatively or additionally, for example, the insulating element 180 and / or the coupling element 168 can be integrated into the exemplary embodiments according to FIGS. 5A to 6G or into other exemplary embodiments of the concept C).

Various combinations are conceivable.

Claims

Apparatus (110) for sensing a temperature of a fluid medium comprising at least one temperature sensor (114), wherein the temperature sensor (114) is adapted to be introduced into the fluid medium, wherein the temperature sensor (114) comprises a sensor body (124) and a measuring head (128) projecting into the fluid medium, wherein in the measuring head (128) at least one sensor element (130) for detecting a temperature

is received, wherein the sensor element (130) is received in the measuring head (128) such that this at least substantially thermally of the

Sensor body (124) is decoupled.

Device (110) according to one of the preceding claims, wherein the thermal decoupling of the sensor element (130) from the sensor body (124) via at least one arranged between the sensor element (130) and the sensor body (124) insulation element (180), wherein the insulation element (180) is arranged to suppress heat transfer between the sensor element (130) and the sensor body (124).

Device (110) according to the preceding claim, wherein the

Insulating element (180) is selected from: an element with low thermal conductivity, in particular an insulating layer and / or an insulating sleeve; a gas gap (182).

Device (110) according to one of the preceding claims, wherein the

Measuring head (128) is at least partially surrounded by a thermally conductive protective sleeve (172).

Device (110) according to one of the preceding claims, wherein the

Measuring head (128) compared to the sensor body (124) a smaller

Diameter.

6. Device (110) according to one of the preceding claims, wherein the

Measuring head (128) in the region of the sensor element (130) in the radial direction is designed at least substantially gap-free. 7. Device (110) according to one of the preceding claims, wherein the

Sensor element (130) is at least partially accommodated in at least one coupling element (168), wherein the coupling element (168) is designed to heat exchange between the sensor element (130) and the fluid medium compared to a heat exchange between the sensor element (130) and to favor the sensor body (124).

8. Device (110) according to the preceding claim, wherein the coupling element (168) of the sensor body (124) is thermally decoupled. 9. Device (110) according to one of the two preceding claims, wherein the coupling element (168) comprises at least one material having one or more of the following properties: a material with a lower density than the average density of the materials of the sensor body (124) in one the measuring head (128) adjacent area; a material with less

specific heat capacity as the average specific heat capacity of the materials of the sensor body (124) in a region adjacent to the gauge head (128); a material with a higher thermal

Conductivity as the average thermal conductivity of the materials of the probe body (124) in an area adjacent the probe (128).

10. Device (110) according to one of the three preceding claims, wherein the coupling element (168) is selected from: a the sensor element (130) at least partially enclosing sleeve of a ceramic material, in particular a ceramic material with high thermal conductivity; a sleeve at least partially surrounding the sensor element (130) made of a plastic material, in particular a plastic material with high thermal conductivity; a sleeve of a metallic material at least partially enclosing the sensor element (130); one that

Sensor element (130) at least partially enclosing the melted bead (176), in particular a melted bead (176) made of a plastic material and / or a melted bead (176) of a metallic material and / or a melted bead (176) of a glass material; a filling material (184) in one Interspace between the sensor element (130) and the measuring head (128) at least partially enclosing protective sleeve (172).