thermometer

Abstract

The invention relates to a device (1) for determining and / or monitoring the temperature (T) of a medium (M) in a container (2), comprising a measuring insert having a temperature sensor (5) for detecting the temperature (T), a protection tube (3) in which the temperature sensor (5) is arranged, and a thermally conductive moulding (8) which is arranged in the protection tube (3) and surrounds at least sections of the measuring insert (4), in particular also in the region of the temperature sensor facing away from the process.

Description

Technical Field

[0001] This invention relates to a thermometer for determining and / or monitoring the temperature of a medium in automation technology, and a method for producing the apparatus of this invention. Background Technology

[0002] Thermometers are known in various embodiments of the prior art. Therefore, there are thermometers for measuring temperature that utilize the expansion of a liquid, gas, or solid with a known coefficient of thermal expansion, or that correlate the electrical conductivity of a material, or variables derived therefrom, with temperature, such as, for example, resistance in the case of a resistive element, or the thermoelectric effect in the case of a thermocouple. Conversely, in the case of radiation thermometers (especially pyrometers), thermal radiation is utilized to determine the temperature of a substance. The measurement principles of these measuring devices are described in numerous published documents.

[0003] In the case of temperature sensors, particularly those in the form of resistive elements, so-called thin-film and thick-film sensors, as well as so-called NTC thermistors, are known. In the case of thin-film sensors, resistance temperature detector (RTD) sensor elements are particularly used; for example, sensor elements equipped with connecting wires and coated on a substrate, wherein the back of the supporting substrate is typically coated with metal. The sensor elements used are so-called resistive elements, which are, for example, based on platinum elements and are also commercially available, particularly under names such as PT10, PT100, and PT1000.

[0004] In the case of temperature sensors in the form of thermocouples, temperature is determined by a thermoelectric voltage that occurs between single-sided connected thermocouple wires made of different materials. For temperature measurement, thermocouples conforming to DIN standard IEC 584 are typically used as temperature detectors, such as type K, J, N, S, R, B, T, or E thermocouples. However, other material pairs (especially those with measurable Seebeck effects) are also possible.

[0005] Temperature sensors are typically part of a measuring insert, which is introduced, for example, into an immersion body or protective tube to enter the medium. However, similar embodiments of thermometers are also known for non-invasive temperature measurement. In this case, the temperature sensor contacts the medium via the wall of the container containing the medium and is suitably fixed to the container wall.

[0006] For reliable temperature determination, it is important that the temperature sensor and the medium are essentially in thermal equilibrium with each other, at least for the specific time required to record the temperature. The response time of a thermometer to a temperature change is also known as the thermometer's response time.

[0007] In this context, the accuracy of the thermometer measurement is sensitively dependent on thermal contact and dominant heat conduction. Particularly in this case, the heat flow between the medium, the container containing the medium, the thermometer components, and the process environment plays a decisive role. In invasive temperature measurements using an immersion body, heat loss to the environment increases with decreasing immersion body length. Heat from the process is transferred not only to the temperature sensor but also to the environment via a protective tube. In non-invasive temperature measurements, this undesirable heat loss has an even greater impact on the environment because, in this case, the temperature sensor is not directly surrounded by the medium. Summary of the Invention

[0008] Therefore, the purpose of this invention is to improve the measurement accuracy of thermometers.

[0009] The apparatus of the present invention for determining and / or monitoring the temperature of a medium in a container (particularly a containment vessel or pipe) comprises: a measuring insert having a temperature sensor for recording the temperature; and a protective tube in which the temperature sensor is disposed. Furthermore, the apparatus includes a thermally conductive molded part disposed within the protective tube and at least partially surrounding the measuring insert, particularly in a region of the temperature sensor remote from the process.

[0010] The molded part is used for heat conduction from the process to the temperature sensor, and for heat distribution within the thermometer. In particular, the molded part is used to ensure a substantially uniform temperature distribution within a predetermined volume surrounding the temperature sensor. In this way, a significantly reduced temperature gradient appears in the region of the temperature sensor due to heat dissipation to the environment. The region surrounding the temperature sensor is heated substantially uniformly. Compared to thermal paste, the molded part of the present invention advantageously provides reproducible, substantially time-constant thermal contact.

[0011] Depending on the embodiment of the thermometer, the molded part is implemented such that it at least partially surrounds the temperature sensor and is in thermal contact with at least one additional component of the thermometer (particularly the protective tube). In this case, the area surrounding the temperature sensor and away from the process also experiences reduced heat loss.

[0012] Advantageously, the molded parts of the present invention can also be used to modify existing thermometers.

[0013] In an advantageous embodiment, the molded part is made of copper, silver, graphite, boron nitride, steel (especially stainless steel) or an alloy containing at least one of these materials.

[0014] In a preferred embodiment, the molded part is at least partially tubular, particularly cylindrical. Within the tubular region, the molded part is further arranged within a protective tube around the measuring insert and thus positioned between the measuring insert and the protective tube.

[0015] Another preferred embodiment includes a can-shaped molded part. Therefore, the molded part includes a tubular section and a base plate. Such an embodiment is suitable for applications such as non-invasive thermometers. Here, the measuring insert is located within the can-shaped molded part.

[0016] In another embodiment of the molded part with a can shape, the base plate of the molded part has a hole, which allows the measuring insert to be guided. Such an embodiment is further suitable for, for example, invasive temperature determination. The base plate is specifically arranged on the side of the temperature sensor away from the process. In principle, with the hole, the base plate acts as a cover and restricts the volume surrounding the temperature sensor, protecting it from environmental influences. However, such an embodiment can also be implemented in conjunction with a non-invasive thermometer.

[0017] In a particularly preferred embodiment of the invention, the molded part has at least partially a geometry corresponding to the geometry of the protective tube and / or the measuring insert. Specifically, the geometry of the molded part at least partially matches the geometry of a region of the protective tube into which the molded part can be inserted, and / or matches the geometry of a region of the measuring insert in which the molded part surrounds the measuring insert. Due to this measure, the molded part can be at least partially and precisely introduced and fitted into the protective tube. In this way, thermal contact between the molded part and the protective tube or the measuring insert is improved, depending on the circumstances.

[0018] In another embodiment, the molded part includes an end member with an outer diameter larger than the outer diameter of the molded part in the intermediate region of the molded part. Such an embodiment is particularly advantageous for protective tubes with variable inner diameters, especially for protective tubes in which the inner diameter of the protective tube in a first region where a temperature sensor can be arranged is smaller than the inner diameter in a second region farther from the process. In this case, the end member is specifically arranged in the second region and at least partially seals the first region from the environment.

[0019] In this respect, the end piece is advantageously disc-shaped. Depending on the embodiment of the thermometer, it is further advantageous that the end piece has a hole through which the measuring insert can be guided.

[0020] Furthermore, it is advantageous that the geometry of the end piece corresponds at least partially to the geometry of the protective tube in the region into which the molded part can be introduced. For protective tubes with first and second regions having different diameters, the geometry of the molded part is particularly adapted to the geometry of the protective tube at the transition between the first and second regions.

[0021] In an additional, particularly preferred embodiment, the device further includes a securing device for securing the molded part (particularly in a releasable manner) within the protective tube and / or to the measuring insert. The securing device improves thermal contact between the molded part and the protective tube and / or between the molded part and the measuring insert.

[0022] Advantageously, the fixing device is implemented and arranged such that a (particularly predetermined) compressive force can be applied to the molded part by means of the fixing device. In order to provide compressive force or apply a predetermined pressure to the molded part, the fixing device can be implemented, for example, to utilize the spring force of the measuring insert itself.

[0023] In other embodiments, the securing device may include, for example, a spring, a threaded cap, or a bayonet cap. Regarding securing devices, virtually all methods known to those skilled in the art for properly securing the molded part in the protective tube and / or the measuring insert can be used and fall within the scope of this invention.

[0024] In a preferred embodiment, the fixing device has at least one (particularly cylindrical) base that can be arranged around the molded part within a protective tube. The base can, for example, be used to transfer a predetermined compressive force to the molded part.

[0025] Furthermore, in embodiments of the invention, the substrate can be made of a thermally insulating material. In this case, the substrate also provides isolation from the environment. The substrate serves as additional thermal isolation from the environment when the molded part provides a uniform heat distribution near the temperature sensor.

[0026] The matrix is ​​advantageously formed from plastics (especially PEEK, PEK, or PPS).

[0027] However, in another embodiment, the substrate can also be made of a thermally conductive material. In this case, for example, a low thickness or advantageous geometry can be selected for the substrate to achieve shielding of the molded part from the environment.

[0028] Another embodiment includes a fixing device having at least one spring, through which a predetermined compressive force can be supplied by means of a base. The spring at least partially surrounds the base. The base is suitably configured to supply the force. For example, the base includes a shoulder in an outer region on which the spring may be disposed.

[0029] Finally, another embodiment of the invention includes: the temperature sensor includes at least one resistive element or thermocouple. Attached Figure Description

[0030] The invention will now be explained in more detail with reference to the accompanying drawings. The figures in the drawings are illustrated below:

[0031] Figure 1 It is a thermometer with a protective tube for invasive temperature measurement based on existing technology;

[0032] Figure 2 It is a thermometer for non-invasive temperature measurement based on existing technology;

[0033] Figure 3 This is a first embodiment of the thermometer of the present invention, used for non-invasive temperature determination using the molded part of the present invention;

[0034] Figure 4 These are examples of molded parts of the present invention;

[0035] Figure 5 This is a second embodiment of the thermometer of the present invention, used for invasive temperature determination using the molded part of the present invention; and

[0036] Figure 6 This is an embodiment of the molded part of the present invention, which has a fixing device.

[0037] In the figure, the same elements have the same reference numerals. Detailed Implementation

[0038] Figure 1 The diagram shows a schematic of a thermometer 1 according to the prior art, used to record the temperature T of a medium M flowing through a pipe 2. The thermometer 1 is introduced into the pipe 2 via a protective tube 3. A temperature sensor 5 is part of a measuring insert 4, which can be removably introduced into the protective tube 3. In this type of assembly, the achievable measurement accuracy depends particularly on the heat dissipation W into the process environment. Undesirable heat dissipation increases with the penetration depth of the protective tube 3 into the pipe 2, thus increasing the measurement error, especially for small-diameter pipes 2.

[0039] Similar problems also arise in non-invasive temperature determination scenarios, such as... Figure 2 As shown. In this case, thermometer 1 does not extend into pipe 2; instead, it rests externally on the pipe wall 2a of pipe 2. Similarly, in this case, the measuring insert 3 includes temperature sensor 5. Furthermore, Figure 2The thermometer 1 is shown with connecting wires 6a and 6b, through which the temperature sensor 5 can be connected to the electronics 7. Although the illustrated thermometer 1 is implemented with a compact structure including the integrated electronics 7, in the case of other thermometers 1, the electronics 7 may also be arranged separately from the measuring insert 3. The temperature sensor 5 may include, for example, a resistive element or a thermocouple, and the number of connecting wires 6 used may vary depending on the embodiment of the temperature sensor 5. Similarly, in this case, undesirable heat loss W to the environment occurs, which degrades the measurement accuracy of the thermometer 1.

[0040] To reduce the negative impact of heat emission, the thermometer of the present invention includes a molded part 8 disposed within a protective tube 3 and at least partially surrounding a measuring insert 4. Therefore, the molded part 8 is at least partially disposed between the measuring insert 4 and the protective tube 3.

[0041] exist Figure 3 A first embodiment of the apparatus 1 of the present invention, having a molded part of the present invention, is shown. This apparatus is similar to... Figure 2 The thermometer 1 is a non-invasive thermometer 1. The molded part 8 in this embodiment is can-shaped. In the embodiment shown here, it is arranged in the region of the base plate B of the molded part 8, between the base plate of the measuring insert 4 and the protective tube 3, and the container wall 2a. The molded part 3 is used to provide preferably uniform heating to the volume V surrounding the temperature sensor 5 and to prevent undesirable temperature gradients in the region of the temperature sensor 5 due to heat loss to the environment.

[0042] Figure 4 The figures shown represent three possible preferred embodiments of the molded part 8 of the present invention, and all of these embodiments, as well as others, are also shown. Figure 3 The molded parts shown are applicable to both invasive and non-invasive thermometers. Figure 4 The molded part 8 of a is tubular or pipe-shaped. The illustrated variation has a circular cross-sectional area; however, other cross-sectional areas are also possible and fall within the scope of the invention. However, in additional embodiments not shown separately, the molded part 8 may be... Figure 3 Similarly, the diagram also includes a base plate B. Furthermore, the base plate B may have a hole through which the measuring insert can be guided. This hole then has a diameter, specifically matching the diameter of the measuring insert 4 and smaller than the outer diameter of the molded part 8. The outer diameter of the molded part 8, for example, adapts to the inner diameter of the protective tube 3, at least in the tubular section. In the end region E, the geometry of the molded part 8 may also match the geometry of the measuring insert 4 and / or the protective tube 3.

[0043] exist Figure 4Figure b shows another embodiment of the molded part 8 of the present invention. In this case, the molded part 8 also includes a cylindrical segment. Furthermore, the molded part 8 has an end member 9, the outer diameter d9 of which is larger than the outer diameter d8 of the middle region of the molded part 8. The end member 9 is disc-shaped in the illustrated embodiment. In this case, the end member 9 also includes an optional hole, which allows the measuring insert 3 to be guided. Similarly, Figure 4 The molded part 8 shown in Figure c includes a tubular segment and an end piece 9. However, with Figure 4 Compared to b, end piece 9 is adapted to the geometry of the protective tube 3, or is implemented to correspond to such geometry.

[0044] exist Figure 5 Another example of an embodiment of the device 1 of the present invention is shown. In this case, with Figure 1 Similar to thermometer 1, this relates to a thermometer 1 used for invasive temperature determination. Thermometer 1 includes components similar to... Figure 4 The molding 8 is implemented in the form of the protective tube 3. The molding 8 is arranged within the protective tube 3 and partially surrounds the measuring insert 4. The protective tube 3 has a variable inner diameter. In the first region B1, it has a smaller inner diameter than in the second region B2. The end piece 9 of the molding 8 is arranged at the transition between the first region B1 and the second region B2 of the protective tube 3, and is arranged to correspond to the geometry of the protective tube in the transition region. In the case of the transition region, the end piece 9 effectively functions as a cap, sealing and isolating the volume V surrounding the temperature sensor 5 from the environment. The molding 8 is used to conduct heat flowing to the environment via the protective tube 3 to the temperature sensor 5. In this way, a uniform temperature distribution around the temperature sensor 5 can be ensured, and unwanted heat loss W to the process environment can be prevented.

[0045] To ensure optimal thermal contact between the molded part 9, the protective tube 3, and the measuring insert 4. Figure 5 The device 1 includes, optionally, a fixing device 10. It should be noted that all embodiments of the thermometer 1 of the present invention shown herein may optionally use a suitable fixing device 10, and all fixing devices 10 known to those skilled in the art are possible according to the present invention.

[0046] Figure 5 The fixing device includes: a cylindrical base 11, which is arranged at least partially around the molded part 8 in the protective tube 3; and a spring 12 for applying a predetermined compressive force to the molded part. In order to transmit the compressive force of the spring 12, the base 11 includes a shoulder 13 on which the spring 12 is arranged.

[0047] Figure 6 A more detailed view of this arrangement is shown in the image. Figure 5In the view shown, the substrate 11 also serves to thermally insulate the molded part 8 from the environment. For this purpose, for example, the substrate 11 is made of a heat-insulating material and is arranged such that it surrounds a cylindrical segment of the molded part.

[0048] List of reference numerals

[0049] 1 Equipment

[0050] 2. Container; 2a. The wall of the container.

[0051] 3. Protective tube

[0052] 4. Measuring insert

[0053] 5. Temperature sensor

[0054] 6. Connecting cable

[0055] 7 Electronic devices

[0056] 8 Molded parts

[0057] 9 terminal components

[0058] 10 Fixing devices

[0059] 11 Matrix

[0060] 12 springs

[0061] 13. Shoulder of the base

[0062] M medium

[0063] T temperature

[0064] W heat emission

[0065] d Diameter

[0066] Areas B1 and B2

[0067] V is the volume surrounding the temperature sensor.

[0068] B. Base plate of the molded part

Claims

1. An apparatus (1) for determining and / or monitoring the temperature (T) of a medium (M) in a container (2), comprising: A measuring insert having a temperature sensor (5) for recording temperature (T), The temperature sensor (5) is arranged in the protective tube (3). as well as A thermally conductive molded part (8) is arranged in the protective tube (3) and at least partially surrounds the measuring insert (4), including surrounding the area of ​​the temperature sensor away from the process. The molded part (8) is at least partially tubular, and in the tubular region, the molded part (8) is further arranged around the measuring insert (4) in the protective tube (3), and is thus located between the measuring insert and the protective tube. The device (1) further includes a fixing device (10) for releasably fixing the molded part (8) in the protective tube (3) and to the measuring insert (4). The fixing device (10) has at least one base (11) which can be arranged around the molded part (8) in the protective tube (3), and wherein the base (11) is made of heat-insulating material.

2. The device (1) according to claim 1, in, The molded part (8) is made of copper, silver, graphite, boron nitride, steel, stainless steel or an alloy containing at least one of these materials.

3. The device (1) according to claim 1 or 2, in, The molded part (8) is at least partially cylindrical.

4. The device (1) according to claim 1 or 2, in, The molded part (8) is can-shaped.

5. The device (1) according to claim 4, in, The base plate (B) of the molded part (8) has a hole, which allows the measuring insert (4) to be guided.

6. The device (1) according to claim 1, in, The molded part (8) has at least a partial geometry that corresponds to the geometry of the protective tube (3) and / or the measuring insert (4).

7. The device (1) according to claim 1, in, The molded part (8) includes an end piece (9) whose outer diameter (d9) is greater than the outer diameter (d8) of the molded part (8) in the middle region of the molded part (8).

8. The device (1) according to claim 7, in, The end piece (9) is disc-shaped.

9. The device (1) according to claim 7 or 8, in, The geometry of the end piece (9) corresponds at least partially to the geometry of the protective tube (3) in the region in which the molded part (8) can be introduced.

10. The device (1) according to claim 1, in, The fixing device (10) is implemented and arranged such that a compressive force can be applied to the molded part (8) by means of the fixing device (10).

11. The device (1) according to claim 10, in, The substrate (11) is made of plastic.

12. The device (1) according to claim 11, in, The substrate (11) is made of PEEK, PEK or PPS.

13. The device (1) according to claim 1, in, The fixing device (10) has at least one spring (12) by means of which a predetermined compressive force can be provided by means of the base (11).

14. The device (1) according to claim 1, in, The temperature sensor (5) includes at least one resistive element or thermocouple.

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