Process for producing a probe element and probe element

Abstract

The invention relates to a method for producing a probe element (10), comprising the following steps: providing an elongated probe body (14) having a longitudinal axis (11.2), in which the probe body (4) is produced by a generative manufacturing process, in particular an additive manufacturing process, by means of a 3D printing process using at least two different materials, wherein the probe body (14) has an outer probe sleeve (11) and an inner probe core (12) arranged in the probe sleeve (11), and wherein the probe core (11) and the probe sleeve (12) are integrally connected to each other in a generative manufacturing process. The invention also relates to such a probe element and to a thermal flow meter having such a probe element.

Description

Technical Field

[0001] The present invention relates to a method for producing a probe element, such a probe element, and a thermal flowmeter having such a probe element. Background Art

[0002] A thermal flowmeter typically includes probe elements that extend into the measuring tube of such a flowmeter, and during operation, a medium, in particular a fluid, flows around the measuring tube. Usually, at least one probe element is configured to sense the temperature of the medium (temperature-sensing probe element), and at least one probe element is configured to heat the medium (heating probe element). For example, the mass flow rate can be inferred from the heating current that is necessary to maintain the temperature difference between the heating probe element and the temperature-sensing probe element.

[0003] In order to be able to quickly sense changes in the temperature or flow rate of the medium, a lower thermal mass of the probe element and a good thermal transition between the probe element and the medium are important.

[0004] DE 10 2016 121 110 A1 proposes producing a probe element by melting silver in a probe sleeve as a probe core. In principle, a good thermal transition can be produced between the probe element and the medium in this way, but this process is prone to forming bubbles, making it difficult to control the formation of cavities. This results in a high proportion of defective products in the manufacture of the probe element.

[0005] To solve this problem, DE 10 2019 110 312 A1 proposes providing a rod for the probe element. A separate probe sleeve and probe core are provided. By means of explosive welding, the probe sleeve is radially deformed completely towards the probe core with respect to the longitudinal axis, and this forms an integral connection between the probe sleeve and the probe core, and thus the rod is manufactured. Compared with DE 102016 121 110 A1, this solution reduces the formation of cavities. However, a disadvantage of explosive welding is that the shape of the probe body is limited to an extruded profile. In addition, a circular probe head is then mounted on the rod, so the probe core is subsequently only closed by a plug. Summary of the Invention

[0006] Therefore, an object of the present invention is to provide an improved method for producing a probe element and an improved probe element.

[0007] This object is achieved by a method for producing a probe element and a probe element.

[0008] Regarding the method for producing a probe element, this object is achieved as follows:

[0009] A method for producing a probe element insertable into a medium, in particular a probe element of a temperature sensor for measuring the temperature of the medium or a probe element of a thermal flowmeter for measuring the mass flow of the medium in a measuring tube, the method comprising the following steps: - Providing an elongate probe body having a longitudinal axis, wherein the probe body is produced by a generative manufacturing process, in particular an additive manufacturing process, by means of a 3D printing process using at least two different materials, wherein the probe body has an outer probe sleeve and an inner probe core located in the probe sleeve, wherein in particular the probe sleeve at least partially surrounds the probe core spatially, and wherein the probe core and the probe sleeve are integrally connected to each other in the generative manufacturing process.

[0010] In particular, within the scope of the present invention, the probe body is thus produced by generative manufacturing in a primary shaping process (classified as group 1.10 of the primary shaping manufacturing processes according to DIN 8580).

[0011] In the generative manufacturing process (also known as the 3D printing process; all known generative production processes will be subsumed under the term "3D printing process"), advantageously, an integral connection between the inner probe core and the outer probe sleeve is directly established. This results in an improved thermal transition between the probe core and the probe sleeve. Furthermore, in the generative manufacturing process, there are basically no restrictions on the shape of the elongate probe body.

[0012] In particular, in the generative manufacturing process, the probe core and the probe sleeve are manufactured by a combined printing procedure.

[0013] In one embodiment of the method, the probe body is manufactured, in particular in the generative manufacturing process, such that the probe body has a medium-facing cap at which the probe body is sealed against the medium.

[0014] Thus, in particular, the cap is already part of the probe body manufactured in the generative manufacturing process and is directly manufactured to be medium-sealed. No additional probe head or plug is required to close the probe body on the medium side. The medium-sealed cap is in particular provided by the outer probe sleeve, i.e. it is directly formed by the probe sleeve. The shape of the cap is optimized, for example flow-optimized. In particular, the cap has a circular shape.

[0015] In one embodiment of the method, the method comprises the following steps: - Mechanically process the surface of the probe element, particularly the surface of the probe sleeve, especially by machining, such that after the probe body is provided by a generative manufacturing process, the average roughness (Ra) of the surface is less than 3.2 µm (micrometers), especially less than 0.8 µm.

[0016] In particular, the average roughness of the probe body according to the present invention is less than 0.3 µm.

[0017] In particular, the machined surface is the surface of the probe body, particularly the surface of the probe sleeve, which can come into contact with the medium.

[0018] In particular, the probe body is fully machined. In the case of a substantially cylindrical probe body, the probe body is machined, for example, by turning. Preferably, this occurs on the entire cylindrical lateral surface.

[0019] In one embodiment of the method, the method comprises the following steps: - Mechanically process the joint surface in the connection region of the probe body, especially by machining, and in particular, the connection region is opposite to the cap with respect to the longitudinal axis of the probe body; - Place at least one sensor element on the joint surface such that the at least one sensing element is thermally coupled to the probe core; - Assemble a connection sleeve onto the probe body on this side of the joint surface such that the at least one sensor element is covered by the connection sleeve.

[0020] Preferably, the sensor element is thermally coupled to the probe core, wherein the internal probe core is exposed or becomes exposed at the joint surface, especially at least partially exposed, and the probe element placed on the joint surface is attached to the region of the joint surface where the probe core is exposed. This results in direct contact between the probe core and the sensor element, thereby establishing a thermal coupling between the sensor element and the probe core. For example, after the step of providing the probe body, i.e., only during machining, the probe core is exposed at the joint surface. Alternatively, within the scope of the present invention, the probe core that is at least partially exposed at the joint surface can also be designed to be directly exposed during the production of the probe body by a generative printing process.

[0021] In particular, the average roughness at the joint surface is less than 3.2 µm (micrometers).

[0022] Optionally, the joint surface is angled with respect to the longitudinal axis; for example, refer to the exemplary embodiment explained below.

[0023] In one embodiment of the method, the at least one sensor element is mechanically connected to a machined connection surface and the at least one sensor element is soldered, glued and / or sintered to the connection surface.

[0024] Preferably, the sensor element is sintered to the machined connection surface.

[0025] In one embodiment of the method, after the connection sleeve is assembled to the probe body, a hermetic connection is established between the connection sleeve and the probe body.

[0026] In particular, this is achieved by soldering the connection sleeve to the probe body.

[0027] In one embodiment of the method, the probe sleeve is made of a first material, the probe core is made of a second material, and the thermal conductivity of the first material is lower than that of the second material.

[0028] In one embodiment of the method, during a generative manufacturing process, the probe core and the probe sleeve are stacked layer by layer, and the layer thickness of the layers formed during the generative manufacturing process is 10 - 500 µm.

[0029] In one embodiment of the method, the generative manufacturing process is an additive manufacturing process, and in this additive manufacturing process, one of the following additive manufacturing processes is used: selective laser melting, electron beam melting, selective laser sintering.

[0030] Regarding the probe element, this object is achieved as follows:

[0031] A probe element, in particular a probe element for a temperature sensor for measuring the temperature of a medium or a probe element for a thermal flowmeter for measuring the mass flow of a medium in a measuring tube, in particular a probe element that can be obtained by the method according to the invention. The probe element comprises: - An elongate probe body, which is produced by a generative manufacturing process using at least two different materials and has a longitudinal axis, the probe body comprising an outer probe sleeve and an inner probe core located in the probe sleeve, wherein in particular, the probe sleeve at least partially surrounds the probe core spatially, and wherein the probe core and the probe sleeve are integrally connected, in particular integrally connected to each other by virtue of the generative manufacturing process.

[0032] In one embodiment of the probe element, the probe element comprises: - At least one sensor element, which is placed on a connection surface in a connection region of the probe body, in particular, the connection region is opposite to the cap with respect to the longitudinal axis of the probe body, The at least one sensor element is thermally coupled to the probe core; and - A connection sleeve, which is assembled on the probe body on this side of the connection surface such that the connection sleeve covers the at least one sensor element, and the connection sleeve and the probe body are connected to each other in a fluid-tight manner.

[0033] In one embodiment of the probe element, the at least one sensor element is one of the following: - A temperature sensor element; - A heating element; - A sensor element designed to measure temperature and heating.

[0034] For example, the sensor element is a resistance-based sensor element, such as a cold-conduction resistance element, in particular Pt100. In the latter case, the sensor element is designed as a combined heating / temperature measurement element, which is designed to measure temperature and to heat depending on the operation.

[0035] In one embodiment of the probe element, the probe sleeve has a first material, the probe core has a second material, and the thermal conductivity of the first material is lower than that of the second material.

[0036] In one embodiment of the probe element, the second material has a thermal conductivity of at least 100 W / (m·K), in particular at least 300 W / (m·K).

[0037] In one embodiment of the probe element, the first material is stainless steel and / or nickel steel, and / or the second material is selected from one of the following: silver, copper or an alloy containing silver and / or copper, in particular an alloy containing at least 60 weight percent of silver and / or copper.

[0038] In one embodiment of the probe element, the probe body has a substantially cylindrical shape, in which the probe body has a circular or elliptical cross-sectional area perpendicular to the longitudinal axis.

[0039] In one embodiment of the probe element, the probe body has a streamlined and / or angular cross-sectional area perpendicular to the longitudinal axis.

[0040] In one embodiment of the probe element, the probe body has a cross-sectional area perpendicular to the longitudinal axis, and the cross-sectional area varies along the longitudinal axis, in particular tapers from the connection region towards the cap of the probe body.

[0041] In one embodiment of the probe element, the probe core has a minimum diameter of at least 1.5 mm, and / or the probe sleeve has a maximum diameter of at most 5 mm.

[0042] In one embodiment of the probe element, the probe sleeve forms a wall for the probe body, and the wall thickness is less than 0.5 mm, particularly less than 0.1 mm.

[0043] In one embodiment of the probe element, in each cross-sectional area of the probe body perpendicular to the longitudinal axis, the probe core constitutes at least 80%, particularly at least 90%, of the cross-sectional area in the probe core portion, and the probe core portion extends in the longitudinal axis direction from the connection surface to the end of the probe core adjacent to the cap.

[0044] The present invention also relates to a thermal flowmeter, which includes: A measuring tube for guiding a flowable medium; At least one probe element according to the present invention, which is located in the measuring tube; An electronic measurement / operation circuit, which is used to operate the at least one probe element and to provide a flow measurement value; and A housing, which is used to accommodate the electronic measurement / operation circuit.

[0045] In one embodiment of the thermal flowmeter, the thermal flowmeter includes: A first probe element, which has at least one sensor element designed to heat; And a second probe element, which has at least one sensor element designed to measure temperature; Wherein, the electronic measurement / operation circuit is configured to heat the first probe element and to determine the temperature of the medium by means of the second probe element. Description of the Drawings

[0046] The present invention will be further explained with reference to the accompanying drawings, which are not drawn to scale, and wherein the same reference numerals represent the same features. For clarity, or if it seems reasonable for other reasons, the previously mentioned reference numerals will not be repeated in the following figures. In the drawings:

[0047] Figure 1a Is a cross-sectional view of an embodiment of the probe body 14 of the probe element 10 according to the present invention;

[0048] Figure 1b 、 Figure 1c Shows the cross-sectional area along the direction A perpendicular to the longitudinal axis 11.2 in different embodiments of the probe body 14 of the probe element 10 according to the present invention;

[0049] Figure 1d Is a cross-sectional view of another embodiment of the probe body 14 of the probe element 10 according to the present invention;

[0050] Figures 2a - 2dIn an embodiment of the probe element 10 according to the invention, it is a sectional view of the details of the connection region 14.4 of the probe body 14 according to the invention, and has a sensor element 16 on the connection surface 12.1 in the connection region 14.4;

[0051] Figure 3 is a sectional view of an embodiment of the probe element 10 according to the invention; and

[0052] Figure 4 shows an embodiment of a thermal flowmeter according to the invention having two probe elements 10a, 10b. Detailed Description

[0053] Figure 1a ) shows a cross-section of the elongated probe body 14 along its longitudinal axis 11.2, and the probe body is produced by a generative manufacturing process. The probe body 14 is formed by layer-by-layer additive deposition, such as by selective laser melting, electron beam melting, selective laser sintering, etc., and has an internal probe core 12, where the internal probe core 12 is surrounded by an external probe sleeve 11. Preferably, in the method according to the invention for producing the probe body 14, the probe core 12 and the probe sleeve 11 are simultaneously deposited layer by layer, and an integral connection is directly produced in the generative production process. This optimizes the above heat transfer. For example, the generative production process for producing the probe element can be clearly seen from the multiple layers of the probe body 14.

[0054] For example, as shown here, the probe body 14 has a circular shape, such as a hemispherical or semi-elliptical shape, at the medium-facing cap 14.3, which is beneficial to the flow resistance of the probe body 14. Preferably, the exact shape of the cap 14.3 can be freely designed within the framework of the generative manufacturing process and optimized by those skilled in the art for specific applications.

[0055] After the probe body 14 is produced in the generative manufacturing process, its surface, especially the surface of the external probe sleeve 11, is machined. For example, the entire lateral surface of the probe sleeve 11 is machined to achieve a sufficiently small average roughness Ra. The average roughness Ra is less than 3.2 µm, especially less than 0.8 µm. Preferably, the average roughness Ra is less than 0.3 µm, and those skilled in the art optimize the average roughness Ra of the probe body 14 or its surface (with respect to flow aspects) for specific applications.

[0056] In the context of the present application, the "cross-sectional area perpendicular to the longitudinal axis 11.2" refers to the cross-sectional area having an area normal that is parallel to the longitudinal axis 11.2.

[0057] In the simplest case, the probe body 14 is cylindrical, in particular the probe body 14 has a circular or oval cross-sectional area in a direction perpendicular to the longitudinal axis 11.2, Figure 1a The auxiliary arrow A shown in

[0058] Figure 1b ) and Figure 1c ) show possible alternative cross-sectional areas that utilize the design freedom of generative manufacturing processes. They show a plan view of the cross-sectional area of the probe body, so compared to the view in Figure 1a ), the auxiliary arrow A shown is rotated by 90°.

[0059] Figure 1b ) shows a cross-sectional area that is at least partially angled and at least partially circular. In the case of a cross-sectional area that is at least partially angled, a separation edge is provided. Figure 1c ) shows another shape of the cross-sectional area, in which case a streamlined shape (also known as a droplet shape) is selected. Depending on the direction of the incident flow and / or the application, the shape design of the cross-sectional area according to Figure 1b ) or Figure 1c ) may be preferred.

[0060] Figure 1d ) shows another possibility for designing the shape of the probe body 14, in which the cross-sectional area decreases from the connection region 14.4 towards the cap 14.3.

[0061] Regardless of the embodiments shown here, the length of the probe body 14 in the direction of the longitudinal axis 11.2 is typically 1 to 3 cm.

[0062] As described above, the probe sleeve 11 is thinner than the probe core 12 and thus forms the wall of the probe body 14. This is because, for example, the wall thickness of the probe sleeve 11 is less than 0.5 mm, in particular less than 0.1 mm, and the wall thickness of the probe core 12 is at least 1.5 mm.

[0063] Regardless of the specific embodiment, the probe core 12 occupies most of the cross-sectional area in the probe core portion. This probe core portion extends in the direction of the longitudinal axis 11.2 from the connection surface 12.1 in the connection region 14.4 (see Figure 2a ) - Figure 2d )) to the end of the probe core 12 adjacent to the cap 14. In the above-mentioned probe core portion, the probe core 12 constitutes at least 60% of the cross-sectional area, such as 2 / 3, preferably at least 80%.

[0064] The wall of the probe sleeve 11 forms the dielectric sealing surface of the probe body 14. The probe sleeve 11 almost completely surrounds the probe core 12, except for the (exposed) connection surface 12.1 of the probe core 12 in the connection area 14.4 (see Figures 2a - 2d ).

[0065] For example, at the connection surface 12.1, the probe core 12 is directly produced to be exposed in the generative manufacturing process. Alternatively, the probe core 12 is first exposed by mechanical treatment of the connection surface 12.1, especially by machining, i.e., after the generative manufacturing process.

[0066] In any case, at the connection surface 12.1, the probe core 12 is at least partially exposed so that at the connection surface 1210, the sensor element 16 subsequently applied thereto can be thermally coupled to the probe core 12. What is explained below Figure 2a )- Figure 2d ) gives a more detailed introduction to this.

[0067] Figure 2a ) shows the details of the connection area 14.4 of the probe body 14. The sensor element 16 lies flat on the connection surface 12.1. The sensor element 16 is fastened to the connection surface 12.1, for example, by welding, gluing or sintering. In this embodiment, the connection surface 12.1 is perpendicular to the longitudinal axis 11.2; other arrangements are shown in Figures b)-d). The connection surface 12.1 is formed by the end face of the probe core 12 so that the sensor element 16 is directly thermally coupled to the probe core 12. The sensor element 16 has a plurality of electrical connection lines 16.1 by means of which the sensor element 16 can be connected to the electronic measurement / operation circuit 3 (see Figure 4 ), for example, to operate the sensor element 16 in a two-wire, three-wire, four-wire, etc. circuit through the electronic measurement / working circuit 3.

[0068] The probe sleeve 11 has a tapered portion 11.1 adjacent to the connection surface 12.1 for connecting the probe sleeve 11 to the connection sleeve 17. The connection sleeve is pushed onto the tapered portion 11.1 (see Figure 3 shown below). The tapered portion 11.1 of the probe sleeve 11 is directly obtained in the generative process and / or produced by subsequent processing (such as machining).

[0069] Figure 2b ) to Figure 2d ) shows the cross-sectional area of an exemplary probe body 14 with a probe core 12 and a probe sleeve 11 according to the present invention. Figure 2b ) and Figure 2c) show a raised portion 12.3 with a connection surface 12.1 protruding from the probe core 12 in the exposed area of the connection region 14.4. Similar to the tapered portion 11.1 of the probe sleeve 11, this raised portion is produced by processing and / or is created directly as part of a generative manufacturing process. The sensor element 16 is mounted on the connection surface 12.1. In Figure 2d ), the diameter of the probe body is large enough to place the sensor element 16 flat on the connection surface 12.1 perpendicular to the longitudinal axis 11.2 of the probe body 14. Figure 2b ) and Figure 2c ) of the exemplary embodiments shown allow the probe element 10 to be manufactured with a small diameter. For Figure 2b ) and Figure 2c ) of this arrangement, in one embodiment of the probe element 10, the angle formed by the connection surface 12.1 and the longitudinal axis 11.2 is less than 30 degrees, particularly less than 20 degrees, and preferably less than 10 degrees. In this way, the thermal mass of the probe element 10 can be optimized and thus the response behavior can be optimized.

[0070] Figure 3 shows the final stage of the production of the probe element 10 according to the invention, in which, after the sensor element 16 is attached to the connection surface 12.1, the connection sleeve 17 is pushed onto the probe body 14 in the connection region 14.4, particularly onto the Figures 2a - 2d tapered portion 11.1 shown in the detailed view. In particular, the connection sleeve 17 is pushed onto the probe body 14 such that the exposed area of the probe core 12 is completely received inside the connection sleeve 17. After the connection sleeve 17 is fastened, for example by welding, particularly by means of peripheral laser welding, the connection sleeve 17 and the probe sleeve 11 are connected to each other in a fluid-tight manner, and the probe core 12 and the sensor element 16 are completely located inside the probe sleeve 11 and the connection sleeve 17.

[0071] Figure 1a ) to Figure 1d ), Figure 2a ) to Figure 2d ) and Figure 3 ) The probe sleeve 11 shown is made of a first material including stainless steel and / or nickel steel, the probe core 12 is made of a second material, such as including silver or copper, and the thermal conductivity of the second material is at least 100 W / (m*K), particularly at least 200 W / (m*K) and preferably at least 300 W / (m*K). The connection sleeve 17 is particularly also made of the first material.

[0072] Since the thermal conductivity of the stainless steel or nickel steel is lower than that of the second material, the temperature change of the probe sleeve 11 caused, for example, by the temperature change of the medium results in a uniform or nearly constant temperature distribution in the probe core 12, and thus also for the probe element 10 according to the invention.

[0073] Figure 4 Fig. 4 shows a schematic front view of an exemplary thermal flowmeter 1, which has a measuring tube 2, two probe elements 10a, 10b according to the invention, and a housing 4. The two probe elements are arranged in the inner cavity of the measuring tube 2, and the housing 4 has an electronic measuring / operating circuit 3. The electronic measuring / operating circuit 3 is configured to operate the probe elements 10a, 10b and to provide a flow measurement value. In order to measure the mass flow rate of the flowable medium passing through the measuring tube 2, for example, the first probe element 10a in the medium flowing through the measuring tube 40 is heated so that the temperature difference relative to the temperature of the medium remains constant. The second probe element 10b can be used to measure the temperature of the medium. Assuming that the properties of the medium are consistent, such as density or composition, the mass flow rate of the medium can be determined via the heating current required to maintain the temperature. The thermal flowmeter 1 given here is an example; when needed, those skilled in the art will combine multiple probe elements 10, 10a, 10b and arrange them in the measuring tube 2 in the required manner. The method for operating such probe elements 10, 10a, 10b is prior art.

[0074] Reference signs and symbols

[0075] 1 Thermal flowmeter

[0076] 2 Measuring tube

[0077] 3 Electronic measuring / operating circuit

[0078] 4 Housing

[0079] 10, 10a, 10b Probe elements

[0080] 11 Probe sleeve

[0081] 11.1 Tapered

[0082] 11.2 Longitudinal axis

[0083] 12 Probe core

[0084] 12.1 Connection surface

[0085] 12.3 Protrusion

[0086] 14 Probe body

[0087] 14.3 Cover of the probe body

[0088] 14.4 Connection area

[0089] Sensor elements 16, 16a, 16b

[0090] Connector 16.1

[0091] Connection sleeve 17

Claims

1. A method for producing a probe element (10) that can be inserted into a medium, in particular a probe element (10) of a temperature sensor for measuring the temperature of the medium or a probe element (10) of a thermal flowmeter for measuring the mass flow rate of the medium in a measuring tube, the method comprising the following steps: - Providing an elongate probe body (14) having a longitudinal axis (11.2), wherein the probe body (14) is produced by a generative manufacturing process, in particular an additive manufacturing process, by means of a 3D printing process using at least two different materials, wherein the probe body (14) has an outer probe sleeve (11) and an inner probe core (12) located in the probe sleeve (11), wherein, in particular, the probe sleeve (11) at least partially surrounds the probe core (12) spatially, and wherein the probe core (12) and the probe sleeve (11) are integrally connected to each other in the generative manufacturing process.

2. The method according to claim 1, Among them, the probe body (14) being manufactured such that, in particular in the generative manufacturing process such that - the probe body (14) has a cover (14.3) facing the medium, at which the probe body (14) is hermetically sealed by the medium.

3. The method according to claim 1 or 2, comprising the following steps: - Mechanically treating the surface of the probe body (14), in particular the surface of the probe sleeve (11), in particular by machining, such that after providing the probe body (14) by the generative manufacturing process, the average roughness (Ra) of the surface is less than 3.2 µm, in particular less than 0.8 µm.

4. The method according to at least one of the preceding claims, comprising the following steps: - Mechanically treating, in particular machining, a connection surface (12.1) in a connection region (14.4) of the probe body (14), in particular, the connection region (14.4) being opposite the cover (14.3) with respect to the longitudinal axis (11.2) of the probe body (4); - Placing at least one sensor element (16) on the connection surface (12.1) such that the at least one sensor element (16) is thermally coupled to the probe core (12); - Fitting a connection sleeve (17) onto the probe body (14) on the side of the connection surface (12.1) such that the at least one sensor element (16) is covered by the connection sleeve.

5. The method according to claim 4, Among them, the at least one sensor element (16) being connected to the machined connection surface (12.1), and wherein the at least one sensor element (16) is welded or sintered onto the connection surface (12.1).

6. The method according to claim 4 or 5, wherein When the connection sleeve (17) is fitted onto the probe body (14), a hermetic connection is established between the connection sleeve (17) and the probe body (14), In particular, the hermetic connection is established by welding the connection sleeve (17) to the probe body (14).

7. The method according to at least one of the preceding claims, Among them, wherein the probe sleeve (11) is made of a first material and the probe core (12) is made of a second material, and wherein the thermal conductivity of the first material is lower than that of the second material.

8. The method according to at least one of the preceding claims, wherein During the generative manufacturing process, the probe core (12) and the probe sleeve (11) are stacked layer by layer, and during the generative manufacturing process, the layer thickness of the formed layers is 10 - 500 µm (micrometers).

9. The method according to at least one of the preceding claims, Among them, wherein the generative manufacturing process is an additive manufacturing process, and one of the following additive manufacturing processes is used in the additive manufacturing process: - Selective laser melting, electron beam melting, selective laser sintering.

10. A probe element (10), in particular a temperature sensor for measuring the temperature of a medium or a probe element of a thermal flowmeter for measuring the mass flow rate of a medium in a measuring tube, in particular a probe element that can be obtained by the method according to at least one of claims 1 to 9 above, the probe element (11) comprising: - An elongated probe body (14) produced by a generative manufacturing process and having a longitudinal axis (11.2), the probe body (4) comprising an external probe sleeve (11) and an internal probe core (12) located in the probe sleeve (11), - wherein, in particular, the probe sleeve (11) at least partially surrounds the probe core (12) spatially, - and wherein the probe core (12) and the probe sleeve (11) are integrally connected to each other, in particular integrally connected to each other by virtue of the generative manufacturing process.

11. The probe element (10) according to claim 10, comprising: - At least one sensor element (16) placed on a connection surface (12.1) in a connection region (14.4) of the probe body (14), in particular, the connection region (14.4) is opposite to the cap (14.3) with respect to the longitudinal axis (11.2) of the probe body (4), the at least one sensor element (16) is thermally coupled to the probe core (12); and - A connection sleeve (17) assembled to the probe body (14) on the side of the connection surface (12.1) such that the connection sleeve (17) covers the at least one sensor element (16), and the connection sleeve (17) and the probe body (14) are hermetically connected to each other.

12. The probe element (10) according to claim 11, wherein, The at least one sensor element (16) is one of the following: - A temperature sensor element; - A heating element; - A sensor element designed to measure temperature and heating.

13. The probe element (10) according to at least one of claims 10 to 12, wherein, The probe sleeve (11) has a first material and the probe core (12) has a second material, and wherein the first material has a lower thermal conductivity than the second material.

14. The probe element (10) according to claim 13, wherein the second material has a thermal conductivity of at least 100 W / (m*K), in particular at least 300 W / (m*K).

15. The probe element (10) according to claim 13 or 14, Among them, wherein the first material is stainless steel and / or nickel steel, and / or wherein the second material is selected from one of the following: silver, copper, or an alloy containing silver and / or copper, in particular an alloy containing at least 60 weight percent of silver and / or copper.

16. The probe element (10) according to at least one of the preceding claims 10 to 15, wherein, The probe body (14) has a substantially cylindrical shape, in which case the probe body (14) has a circular or elliptical cross-sectional area perpendicular to the longitudinal axis (11.2).

17. The probe element (10) according to at least one of the preceding claims 10 to 15, wherein, The probe body (14) has a streamlined and / or angular cross-sectional area perpendicular to the longitudinal axis (11.2).

18. The probe element (10) according to at least one of the preceding claims 10 to 17, wherein, The probe body (14) has a cross-sectional area perpendicular to the longitudinal axis (11.2), the cross-sectional area varying along the longitudinal axis (11.2), and in particular tapering from the connection region (14.4) towards the cap (14.3).

19. The probe element (10) according to at least one of the preceding claims 10 to 18, wherein, The probe core (12) has a minimum diameter of at least 1.5 mm, and / or wherein the probe sleeve (11) has a maximum diameter of at most 5 mm.

20. The probe element (10) according to at least one of the preceding claims 10 to 19, Among them, wherein the probe sleeve (11) forms the wall of the probe body (14), and the wall thickness is less than 0.5 mm, in particular less than 0.1 mm.

21. The probe element (10) according to at least one of the preceding claims 10 to 20, Among them, in each cross-sectional area of the probe body (14) perpendicular to the longitudinal axis (11.2), the probe core constitutes at least 60%, in particular at least 80%, preferably at least 90% of the cross-sectional area in the probe core portion, and the probe core portion extends in the direction of the longitudinal axis (11.2) from the connection surface (12.1) to the end of the probe core (12) adjacent to the cap (14.3).

22. A thermal flowmeter (1), comprising: a measuring tube (2) for guiding a flowable medium; at least one probe element (10) according to at least one of claims 10 to 21, the probe element (11) being located in the measuring tube; an electronic measurement / operation circuit (3) for operating the at least one probe element (10) and for providing a flow measurement value; and a housing (4) for accommodating the electronic measurement / operation circuit (3).

23. The thermal flowmeter according to claim 22, comprising: a first probe element (10a) having at least one sensor element (16a) designed to be heated; and a second probe element (10b) having at least one sensor element (16b) designed to measure temperature; wherein the electronic measurement / operation circuit (3) is configured to heat the first probe element (16a) and determine the temperature of the medium by means of the second probe element (16b).

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