Temperature measuring device

Abstract

The present invention relates to a temperature measuring device comprising a measuring element (12; 112), a connection element (14; 114) having a housing, a line arrangement (16; 116), the line arrangement (16; 116) at least in sections comprising connection lines (46; 146), at least one thermocouple having at least two different thermocouple wires (32; 132; 232, 236a, 236b, 236c), the two thermocouple wires (32; 132; 232, 236a, 236b, 236c) being connected to one another at a measuring point and in each case so as to form a connecting point with a connection line, the measuring point being provided in the measuring element (12; 112) and the connecting points being located inside the housing of the connection element (14; 114), the line arrangement (16; 116) having a first line portion (40; 140) with an outer sheath (44; 144), in which the at least two connection lines (46; 146) are routed, the first line portion being fixedly connected to the connection element (14; 114) in the region of a first end and the interior of said first line portion being filled with an electrically insulating, high-temperature-resistant material at least in the region of the first end.

Description

[0001] Temperature measuring device

[0002] Description:

[0003] Technical field:

[0004] The present invention relates to a temperature measuring device, in particular a temperature measuring device which is suitable for use at very high temperatures, such as those that occur in the manufacture of glass.

[0005] State of the art:

[0006] Melting glass requires very high temperatures, which can range from 1500°C to 1600°C. Most processes for manufacturing glass products from molten glass necessitate monitoring the temperature of the molten glass itself. Due to these extremely high temperatures, the temperature measuring devices used must meet very high standards. In practice, thermocouples have proven to be suitable temperature measuring devices for monitoring the temperature during glass production, particularly for measuring the temperature of molten glass.

[0007] Thermocouples are very versatile and can be used to measure both very low and very high temperatures. A thermocouple consists of two different thermocouple wires connected at a measuring point. To determine the temperature, the thermocouple wires are brought to the point of measurement. The thermally induced voltage in the thermocouple wires is detected by a signal acquisition device, such as a resistance meter, located some distance from the measuring point. Depending on the temperature range in which the thermocouple is used, the materials of the thermocouple wires and the components required for its operation vary.

[0008] Since thermocouples are used in environments where temperatures can cause some materials to melt or decompose, at least the parts of the thermocouple that come into contact with a measuring point at very high temperatures must be made of materials that can withstand high temperatures. Additionally or alternatively, the environmental conditions at the measurement point can trigger chemical reactions in the materials used, especially the thermocouple wires, so these materials, particularly the thermocouple wires, must be protected accordingly.

[0009] For use in very high temperature ranges and / or chemically reactive environments, ceramic-insulated thermocouples have proven effective. In a ceramic-insulated thermocouple, the thermocouple wires required for its function are contained within a ceramic insulating rod. Using this ceramic insulating rod and, if necessary, additional protective devices such as platinum shielding tubes, the thermocouple wires can be positioned at the desired measurement location, for example, in a glass melting furnace, to measure the temperature of the molten glass.

[0010] The voltage difference measurement necessary for determining the temperature is performed remotely from the actual point being measured, in a moderate-temperature environment, so that the signal acquisition devices, especially resistance meters, are not damaged. For this reason, the thermocouple wires often need to be very long.

[0011] Especially when using thermocouples in a melt at very high temperatures, thermocouple wires with very high temperature resistance must be used. Such wires are made of a platinum and rhodium alloy and are therefore comparatively expensive.

[0012] It is known that extending thermocouple wires by using cost-effective compensating leads, for example made of copper, also yields satisfactory measurement results. Compensating leads consist of substitute materials that differ from those of the thermocouple wires but possess the same thermoelectric properties within a permissible temperature range. These compensating leads can be connected to the thermocouple wires using appropriate connectors. Suitable connectors, typically housed in a terminal block, are provided for connecting the thermocouple wires to the compensating leads. For cost reasons, the terminal blocks should therefore be located as close as possible to the measuring point.

[0013] Also for cost reasons, the connection head is usually made of lightweight metal, such as aluminum. Seals and washers required in the connection head are usually made of carbon-based materials, such as plastic. As is well known, carbon-based plastics generally do not have very high temperature resistance. The use of such connection heads and corresponding sealing elements is therefore typically limited to a temperature range between 100°C and 200°C.

[0014] If the connection heads are located too close to the high-temperature point being measured, such as a glass melting furnace, there is a risk that the materials made of organic substances will soften, melt, or burn depending on the temperature, which can damage the connection head. Furthermore, such changes in material state usually lead to a so-called "poisoning" of the thermocouple wires and thus to the failure of the thermocouple.

[0015] In processes involving extremely high temperatures, such as glass manufacturing, there is always a risk of significant temperature fluctuations occurring even at a relatively large distance from the actual measurement point. These fluctuations can generate temperatures so high that they can damage the connecting elements or the sensor head. Therefore, a sufficient safety distance must be maintained, meaning the sensor head must not be positioned too close to the measurement point. However, this safety distance is often impractical and inevitably leads to the use of longer and more expensive thermocouple wires.

[0016] Description of the invention:

[0017] It is therefore an object of the present invention to provide an improved temperature measuring device that is suitable for use in high-temperature environments, for example, in glass manufacturing processes, is cost-effective to manufacture, and reliably provides accurate temperature readings. In particular, it is an object of the present invention to provide a thermocouple with extended thermocouple wires in which the safety distance between the terminal head and the measuring point can be reduced.

[0018] According to the invention, the problem is solved by a temperature measuring device comprising a measuring element, a connection element with a housing, a cable arrangement, wherein the cable arrangement comprises at least sectional connection cables, and a data acquisition device, wherein the data acquisition device is connected to the measuring element by means of the cable arrangement, at least one thermocouple with at least two different thermocouple wires, each having two opposite ends, wherein the two thermocouple wires are connected to each other at one end in a measuring point and at the other end each to a connection cable forming a connection point, wherein the measuring point is provided in the measuring element, the connection points between the connection cable and the thermocouple wire are located inside the housing of the connection element, wherein the cable arrangement has a first cable section,comprising an outer sheath with a first end and an oppositely located second end, wherein the at least two connecting leads are guided in the outer sheath, the outer sheath is firmly connected to the connecting element in the region of its first end, and the outer sheath is filled internally with an electrically insulating, high-temperature-resistant material, at least in the region of its first end.

[0019] The temperature measuring device is, for example, a thermocouple in which the measuring element has a protective element, such as a sheath or a protective fitting, in which the thermocouple wires are located. The measuring point is electrically isolated from the protective element. As is known from the prior art, the protective element can be composed of several elements, in particular several layers or sheaths.

[0020] The two thermocouple wires are each extended by means of corresponding connecting leads, so that the voltage difference between the two thermocouple wires can be measured in a data acquisition device located remotely from the measuring point, such as a resistance meter. The connection between the connecting lead and the thermocouple wire is housed in the connection element's casing. The connection element can be, for example, a terminal head. The connections between the connecting lead and the thermocouple are generally permanent.

[0021] The basic idea of ​​the invention is to make the connection head of existing thermocouples more temperature-resistant by avoiding, as far as possible, temperature-sensitive materials such as carbon-based plastics.

[0022] The concrete implementation of this basic idea consists of routing the connecting leads and / or the connection between the connecting leads and the thermocouple wire inside the temperature measuring device, without using temperature-sensitive materials such as carbon-containing plastics. Specifically, the outer sheath is designed to be filled, at least in the area of ​​the first end, with an electrically insulating, high-temperature-resistant material, preferably a non-carbon-containing organic material and ideally containing no carbon at all.

[0023] In the area of ​​the first cable section, this increases the temperature resistance of the temperature measuring device. The outer sheath in this area can be filled with the electrically insulating, high-temperature-resistant material along its entire length or only in sections along the length of the cable section. In the areas where the first cable section is filled with the electrically insulating, high-temperature-resistant material, the outer sheath can be completely or partially filled with the electrically insulating, high-temperature-resistant material in cross-section. Crucially, the connecting leads within the outer sheath must be electrically insulated from one another. The electrically insulating, high-temperature-resistant material can surround the connecting leads, at least in sections.Preferably, the connecting cables located in the outer sheath are each completely surrounded by the electrically insulating, high-temperature-resistant material.

[0024] Additionally, it is advantageous that the housing of the connection element is filled inside with an electrically insulating, high-temperature resistant material.

[0025] It is understood that further cavities of the temperature measuring device may be filled with an electrically insulating, high-temperature resistant material.

[0026] For example, the electrically insulating, high-temperature resistant material is a mineral material, preferably a high-temperature cement.

[0027] The same electrically insulating, high-temperature-resistant material can be used inside the outer casing and inside the housing. However, different electrically insulating, high-temperature-resistant materials can also be used. It is particularly advantageous if the electrically insulating, high-temperature-resistant material inside the housing is high-temperature cement.

[0028] The electrically insulating, high-temperature-resistant material can be in powder form in the outer casing and / or the housing. In a particular embodiment, where the electrically insulating, high-temperature-resistant material is a high-temperature cement, the outer casing and / or the housing can be filled with it.

[0029] In this context, a high-temperature resistant material is understood to be a material that can withstand continuous temperatures up to 300°C and peak temperatures above 300°C for a certain period of time.

[0030] Particularly for use in the glass industry, it is advantageous that the high-temperature resistant material can withstand continuous temperatures up to 500°C and peak temperatures well above 700°C for a certain period of time.

[0031] Mineral materials such as high-temperature cement have the advantage that they are thermally resistant for at least a certain period of time at temperatures far exceeding the aforementioned range of 300°C, up to the temperatures prevailing during glass melting.

[0032] The connecting leads and / or thermowires as well as the connection points are thus preferably individually surrounded by the electrically insulating, high-temperature-resistant material, at least in the area of ​​the connection points, in particular individually embedded in the powder or, in the case of high-temperature cement, individually surrounded by the solid high-temperature cement.

[0033] To further reduce the amount of plastic materials in the temperature measuring device, it is advantageous that the connecting leads, at least in the area from the outer sheath to the connection point between the connecting lead and the thermocouple wire, consist only of electrically conductive material. In these areas, the connecting leads are primarily made of pure metal wires. In this case, it is understood that the individual metal wires are spaced apart and each is surrounded by electrically insulating, high-temperature-resistant material, so that no short circuit occurs between the connecting leads in these areas.

[0034] Furthermore, it is advantageous that, at least in the area of ​​the first end of the outer sheath, the connecting wires consist solely of electrically conductive material. In this case as well, it is understood that the individual metal wires are spaced apart and each is surrounded by the electrically insulating, high-temperature-resistant material, so that no short circuit occurs between the connecting wires in this area. The connecting wires can be designed as a purely electrically conductive material, in particular as metal wire, not only in the area of ​​the first end of the outer sheath, but also along the entire length of the sheath where the high-temperature-resistant material is located.

[0035] Since the connecting cables are embedded at a distance from each other in the high-temperature resistant material, it is possible to do without the cable insulation of the connecting cables, which usually consists of organic material, and thus without organic materials with low temperature resistance, such as carbon-based plastic materials.

[0036] To withstand high ambient temperatures, it is advantageous for the housing of the connection element and / or the outer sheath to be made of stainless steel. Particularly high temperature resistance is achieved by using a high-temperature-resistant stainless steel for the housing of the connection element and / or the outer sheath.

[0037] To avoid unwanted thermal bridges between the connection element and the outer jacket and / or to prevent the ingress of unwanted gases into the interior of the temperature measuring device, it is advantageous that the connection element and the outer jacket are gas-tightly connected to each other.

[0038] It is particularly preferred that both the housing of the connection element and the outer sheath are made of stainless steel, especially high-temperature-resistant stainless steel. This allows for a simple, temperature-resistant, and in particular gas-tight connection between the housing of the connection element and the outer sheath. For example, the housing of the connection element and the outer sheath can be joined by welding.

[0039] The measuring element is preferably also firmly and tightly, in particular gas-tight, connected to the connecting element, whereby the measuring element can be permanently fixed, for example, welded to the connecting element. Alternatively, the measuring element can be detachably connected to the connecting element, for example, by means of a compression fitting. In a preferred embodiment, the connecting element comprises a sleeve with a first end face and a second end face, wherein the measuring element is arranged at the first end face and the outer casing at the second end face of the connecting element. This is a very cost-effective design of the connecting element, since the sleeve can be part of the housing of the connecting element.

[0040] To create a tight connection between the outer shell and the connecting element, it is advantageous to have a cover with an opening on the second end face of the connecting element through which the first end of the outer shell protrudes.

[0041] Since the measuring points are very sensitive to external mechanical and chemical influences, the measuring element preferably has an outer protective element, with the measuring points located inside this outer protective element. Additionally, sections of the thermocouple wires may also be located within the outer protective element.

[0042] The outer protective element can, for example, be a housing made of high-temperature-resistant ceramic with a stainless steel support tube. It can be multi-layered or composed of several elements.

[0043] Cavities in the area inside the outer protective element can be filled with an electrically insulating, high-temperature resistant material such as high-temperature cement.

[0044] Additionally or alternatively, an internal protective element, such as an insulating rod, can be provided to mechanically protect and electrically insulate the thermocouple wires. This internal protective element can be made of a ceramic material, for example.

[0045] In a first preferred embodiment, the insulating rod has a free end, and the inner protective element is firmly connected to the outer protective element in the region of the free end. The outer and inner protective elements form a single unit. This results in particularly good thermal, chemical, and / or mechanical protection of the thermocouple wires and / or measuring points. This embodiment of a temperature measuring device is therefore particularly stable and tamper-proof.

[0046] For various applications, there is a need to replace the outer protective element. For flexible use of outer protective elements, it is advantageous that the outer protective element and the thermocouple wires are separable. In a preferred embodiment, the inner protective element therefore has a free end, and this free end is firmly connected to the connecting element. Because the inner protective element is firmly connected to the connecting element, it is ensured that the thermocouple wires are at least mechanically protected from external influences. Furthermore, this embodiment allows the thermocouple wires and the connection points to be housed in a common gas-tight environment and connected to different protective elements as needed.

[0047] In a preferred embodiment, the connecting element is permanently attached to the outer protective element. In the area of ​​the thermocouple wires, the temperature measuring device, together with the first power section, forms a structural unit that effectively protects the thermocouple wires inside this unit. This embodiment is particularly advantageous when the inner protective element has a free end and is permanently attached to the outer protective element in the area of ​​this free end.

[0048] For example, the outer protective element includes a support tube, one end of which is firmly connected to the connecting element. If both the connecting element and the support tube are made of a metal such as stainless steel, they can be joined together, for example, by welding. The other end of the support tube can be connected to a ceramic protective sleeve.

[0049] In an alternative embodiment, the connecting element is detachably attached to the outer protective element. This allows for a flexible, modular design of the temperature measuring device. This embodiment is particularly advantageous when the inner protective element has a free end and is permanently attached to the connecting element in the area of ​​this free end. In this case, the outer protective element can be easily detached as a module from the other components of the temperature measuring device.

[0050] To detachably connect the connecting element to the outer protective element, a compression fitting can be used, for example. The compression fitting creates a gas-tight connection. The measures already mentioned make it possible to reduce the proportion of temperature-sensitive plastic materials in the area of ​​the connection between connecting leads and thermocouple wires, thereby increasing the temperature resistance of the measuring device in this area.

[0051] It is further advantageous that a second cable section is provided, which forms an extension of the first cable section at the second end of the outer sheath. This second cable section has a first end and an oppositely positioned second end and is flexible. This allows the measuring device to be flexibly installed at any desired location. The flexible second cable section also allows structural obstacles between the data acquisition device and the measuring tip to be overcome.

[0052] For example, the second conductor section can have a flexible sheath in which the at least two connecting leads are guided. In this case, the flexible sheath can be made of a plastic, since it can be assumed that the ambient temperatures decrease with increasing distance between the measuring tip and the conductor section, so that the temperatures are in a range where the plastic no longer deforms. In this embodiment, it is understood that the two connecting leads are each electrically insulated from each other within the flexible sheath. This can be achieved by providing the electrical insulation normally found on connecting leads.

[0053] The transition from the first pipe section to the second pipe section can, for example, be achieved using a transition element. According to a preferred embodiment, a transition element is provided which is firmly connected to the first pipe section in the region of its second end. In particular, the transition element can be a sleeve made of stainless steel. It can be made of high-temperature-resistant stainless steel, but this is no longer strictly necessary.

[0054] As is known from the prior art, it is advantageous for the connecting cable to have an electrical conductor wire that, within a defined temperature range, exhibits the same thermoelectric properties as the thermoelectric wires. In this case, the connecting cable is a compensating cable. Alternatively, however, the connecting cable may have a metallic conductor wire that has different thermoelectric properties than the thermoelectric wires. In this case, the connecting cable is no longer a compensating cable. For example, the connecting cable can be made of a base metal such as copper or nickel. This has the advantage that the connecting cable has conductor wires made of materials with a higher temperature resistance than those that would exhibit the same thermoelectric properties as the thermoelectric wires if it were a compensating cable.

[0055] Particularly in cases where the connecting leads have an electrical conductor with different thermoelectric properties than thermoelectric wires, it is advantageous to provide an additional temperature measuring device, especially a resistance sensor or measuring resistor, inside the connecting element. Using the temperatures known inside the connecting element, the voltage difference between the connecting leads detected by the data acquisition device can be corrected accordingly to accurately reflect the temperature actually measured by the temperature measuring device.

[0056] The resistance temperature measuring device could, for example, be a measuring resistor such as a PT100, PT1000 or NTC.

[0057] To measure the temperature inside the connection element, the additional temperature measuring device must have electrical leads that connect it to the data acquisition device. It is advantageous for the electrical leads of the additional temperature measuring device to be routed parallel to and at a distance from the connection leads within the outer sheath.

[0058] To control the temperature distribution in the glass melt, it is advantageous that at least one multi-stage thermocouple is provided in the measuring element.

[0059] In a preferred embodiment, at least two additional thermocouple wires are provided in the measuring tip, each thermocouple wire being connected to a connecting lead, and the additional connecting leads being routed parallel to the existing connecting leads inside the outer sheath, electrically insulated from one another. In a preferred embodiment of a multi-stage thermocouple, at least two additional thermocouple wires are provided in the measuring element, wherein two of the at least two additional thermocouple wires have opposite polarities and are connected to each other by forming a junction. In this case, it is advantageous if the two existing thermocouple wires also have opposite polarities.

[0060] Additionally or alternatively, the measuring element provides at least one thermocouple wire of a first polarity and at least two thermocouple wires of a second polarity, wherein the at least two thermocouple wires of the second polarity are each connected to the thermocouple wire of the first polarity, forming a measuring point. In this embodiment, the number of thermocouple wires required can be kept low while maintaining a large number of measuring points.

[0061] Furthermore, this type of wiring allows for a comparatively small footprint, enabling the provision of compact temperature control devices. In addition, assembly and material costs are reduced.

[0062] The connection points designed as measuring points are preferably arranged one after the other along the thermocouple wire of the first polarity.

[0063] It is understood that more than two connection points designed as measuring points may be provided on the thermocouple wire of the first polarity.

[0064] Preferably, the thermocouple wire of the first polarity can be mechanically reinforced compared to the at least two thermocouple wires of the second polarity, in particular having a larger diameter.

[0065] The corresponding connecting cables are preferably routed parallel to each other inside the outer sheath, electrically insulated from each other.

[0066] For processing the measurement signals at the measuring points, integrated IO-Link electronics can be provided. The integrated IO-Link electronics can convert the thermoelectric voltage directly into digital signals within the temperature sensor, thus reducing interference on the line. Brief description of the drawings:

[0067] Preferred embodiments are explained in more detail with reference to the accompanying drawings, which show:

[0068] Fig. 1 shows a temperature measuring device according to a first embodiment,

[0069] Fig. 2 shows a cross-section through the measuring tip of the measuring element,

[0070] Fig. 3 shows a cross-section through the temperature measuring device in the area of ​​the connection element,

[0071] Fig. 4 shows a temperature measuring device according to a second embodiment,

[0072] Fig. 5 shows a cross-section through the temperature measuring device of the second embodiment in the area of ​​the connection element,

[0073] Fig. 6 shows a sensor module of the temperature measuring device according to the second embodiment,

[0074] Fig. 7 shows a protective fitting of the temperature measuring device according to the second embodiment,

[0075] Fig. 8 shows a first embodiment of a multi-stage thermocouple and

[0076] Fig. 9 shows a second embodiment of a multi-stage thermocouple.

[0077] Best way to implement the invention:

[0078] Figure 1 shows a temperature measuring device 10 with a measuring element 12, a connection element 14, a cable arrangement 16, a plug 18 and a data acquisition device 20.

[0079] The measuring element 12 comprises a measuring tip 22, a protective tube 24, a protective sleeve 26, and a support tube 28. The protective tube 24 has a front end and a rear end, with the tubular protective sleeve 26 being located at the front end of the protective tube 24. The support tube 28 is located at the rear end of the protective tube 24 and surrounds it.

[0080] Furthermore, an insulating rod 30 made of a ceramic material extends inside the protective sheath 26 and the protective tube 24 (see Fig. 2). The insulating rod 30 is firmly connected to the protective tube 24 by means of a metallic fixing ring 31 shown in Fig. 3.

[0081] The protective tube 24, the protective cover 26 and the support tube 28 are part of an outer protective element designed as a protective fitting.

[0082] The insulation rod 30 serves as an internal protective element and electrical insulator. It is made of a ceramic material.

[0083] The protective casing 26 is made of platinum and / or rhodium. The protective tube 24 is made of ceramic and the support tube 28 is made of high-temperature-resistant stainless steel.

[0084] Inside the insulating rod 30 is a multi-stage thermocouple. The multi-stage thermocouple comprises three thermocouple wire pairs 31a, 31b, 31c, each with two different thermocouple wires 32. The individual thermocouple wires 32 are spaced apart from one another within the insulating rod 30 and aligned parallel to the longitudinal axis of the insulating rod 30 (see Fig. 8). Each thermocouple wire pair has two opposite ends. At one end, both thermocouple wires 32 of each thermocouple wire pair are connected to each other at a measuring point 34a, 34b, 34c. The other end of each thermocouple wire 32 protrudes from the insulating rod 30. The measuring points 34a, 34b, 34c are located in the measuring tip 22, while the free ends of the thermocouple wires 32 are located in the area of ​​the support tube 28. The thermowires 32 are made of platinum or an alloy of platinum and rhodium.

[0085] The line arrangement 16 comprises a first line section 40 and a second line section 42.

[0086] The first conductor section 40 is formed from a metallic outer sheath 44 with a first end and an oppositely located second end, with connecting wires 46 guided inside (see Fig. 3). The connecting wires 46 comprise metal wires made of a more economical material than those of the thermocouple wires 32. For example, these are made of copper or nickel.

[0087] The outer casing 44 is made of a high-temperature resistant material, such as high-temperature resistant stainless steel. Inside the outer casing 44 is an electrically insulating, high-temperature resistant material, in particular a high-temperature resistant powder. This material is a mineral material, specifically high-temperature cement.

[0088] The connecting cables 46 guided in the outer sheath consist of a pure metal conductor without cable insulation and are arranged at a distance from each other, aligned parallel to the longitudinal direction of the outer sheath and embedded in the electrically insulating, high-temperature resistant material.

[0089] The connecting leads 46 protrude from the outer sheath 44 at its end face and are connected to the thermocouple wires 32 protruding from the insulating rod 30. Each thermocouple wire 32 forms a connection point with a connecting lead 46.

[0090] The connection points between connecting leads 46 and thermocouple wire 32 are all located in the connection element 14 to protect the connection points. The connection element 14 comprises a sleeve 48, the sleeve 48 having a first and a second end face.

[0091] The connecting element 14 is connected at its first end face to the support tube 28 of the measuring element 12. The support tube 28 has a smaller outer diameter than the sleeve 48 of the connecting element 14, so that the end section of the support tube 28 projects into the sleeve 48. The sleeve 48 and the support tube 28 are firmly and tightly connected to each other.

[0092] On the second end face is a cover 50 with an opening 52, the opening being surrounded by a nozzle 54. The cover 50 is firmly connected to the sleeve. Both the sleeve 48 and the cover 50 are made of a high-temperature-resistant metal, such as high-temperature-resistant stainless steel, so that the cover 50 can be firmly and tightly connected to the sleeve 48. For example, the cover 50 and the sleeve 48 can be welded together. The outer sheath 44 projects with its first end section through the opening 52 of the cover 50 and is firmly connected to the cover. Inside the connection element 14 is a measuring resistor 56, which is connected to the data acquisition device 20 via appropriate electrical leads 58. The measuring resistor can be a PT100, PT1000, or NTC.

[0093] Similar to the connecting leads 46, the electrical leads 58 of the measuring resistor 56 are pure metal wires, arranged without cable insulation, spaced apart from each other and from the connecting leads 46, and aligned parallel to the longitudinal direction of the outer sheath. The electrical leads 58 are also embedded in the electrically insulating, high-temperature-resistant material.

[0094] The second conductor section 42 comprises a flexible sheath in which the connecting leads and the electrical leads of the measuring resistor 56 are guided. The connecting leads and electrical leads in the second conductor section are the same as in the first conductor section 40, except that, unlike the connecting leads 46 and electrical leads 58 in the first conductor section 40, the connecting leads and electrical leads in the second conductor section 42 each have cable insulation to prevent short circuits between the connecting leads and the electrical leads of the measuring resistor.

[0095] The first conductor section 40 and the second conductor section 42 are connected to each other by means of a transition element 60. The transition element 60 is a sleeve that is connected at one end face to the second end of the outer sheath 44 of the first conductor section 40 and at the other end face to the flexible sheath of the second conductor section 42.

[0096] The second line section 42 terminates in the connector 18. The connector 18 is in turn connected to the data acquisition device 20.

[0097] Typically, the connecting leads have an electrical conductor wire that has the same thermoelectric properties as the thermoelectric wires.

[0098] In the illustrated embodiment, however, the connecting leads 46 have an electrical conductor wire that possesses different thermoelectric properties than the thermoelectric wires 32. This has the advantage that materials with a higher temperature resistance can be used for the conductor wires of the connecting leads 46 than the conductor wires of the connecting leads that would have the same thermoelectric properties as the thermoelectric wires 32.

[0099] In the event that the connecting leads 46 have an electrical conductor wire with different thermoelectric properties than the thermoelectric wires 32, the measuring resistor 56 is provided inside the connecting element 14. A temperature measurement can be carried out in the connecting element 14 by means of the measuring resistor 56, and the measured values ​​acquired by the measuring resistor can be used to correct the data acquired in the data acquisition device.

[0100] All of the measures mentioned contribute to making the temperature measuring device in the area of ​​the connection element 14 more heat-resistant, so that the connection element 14 can be positioned relatively close to measuring points that are exposed to very high temperatures.

[0101] To measure the temperature, the measuring tip 22 is placed at the desired location. The resistance between the thermocouple wires 32 and the value obtained from the measuring resistor are recorded in the data acquisition device 20. In a processing unit (not shown), the values ​​from the data acquisition device 20 are processed so that the temperature value present at the measuring points can be determined from the recorded values.

[0102] Instead of the measuring element 12 shown in Figures 1 to 3, other measuring elements of a thermocouple known from the prior art can also be used. In particular, other temperature-resistant materials can be used for the manufacture of the measuring element 12.

[0103] Figure 4 shows an alternative embodiment of a temperature measuring device 110 with a measuring element 112, a connection element 114, a cable arrangement 116, a connector 118 equipped with 10 Link electronics and a data acquisition device 120, in which, in contrast to the embodiment of a temperature device 10 shown in Figures 1 to 3, the outer protective element can be removed.

[0104] The measuring element 112 comprises, analogously to the first embodiment, a measuring tip 122, a protective tube 124, a protective sleeve 126, and a support tube 128, wherein the protective tube 124, the protective sleeve 126, and the support tube 128 form the outer protective element. The protective tube 124 has a front end and a rear end, with the tubular protective sleeve 126 being located at the front end of the protective tube 124. The support tube 128 is located in the region of the rear end of the protective tube 124 and surrounds the protective tube 124.

[0105] Furthermore, an insulating rod 130 made of a ceramic material is provided, which forms the inner protective element and is positioned inside the protective sheath 126 and the protective tube 124. A free end of the insulating rod 130 protrudes from the protective tube 124. The insulating rod 130 is detachably arranged inside the protective tube 124.

[0106] The protective casing 126 is made of platinum and / or rhodium. The protective tube 124 is made of ceramic, and the support tube 128 is made of high-temperature-resistant stainless steel.

[0107] Inside the insulating rod 130, as in the first embodiment, is a multi-stage thermocouple with three thermocouple wire pairs 31a, 31b, 31c, each pair comprising two different thermocouple wires 132 of opposite polarity. The individual thermocouple wires 132 are spaced apart within the insulating rod 130 and aligned parallel to its longitudinal axis. Each thermocouple wire pair has two opposite ends. At one end, both thermocouple wires 132 of each pair are connected at a measuring point 34a, 34b, 34c (see Fig. 8). The other end of each thermocouple wire 132 protrudes from the insulating rod 130. The measuring points 34a, 34b, 34c are located in the measuring tip 122, while the free ends are situated in the area of ​​the support tube 128. The thermowires 132 are made of platinum or an alloy of platinum and rhodium.

[0108] The conductor arrangement 116 comprises a first conductor section 140 and, as in the first embodiment, can have a second conductor section not shown.

[0109] The first conductor section 140 is formed from a metallic outer sheath 144 with a first end and an oppositely located second end, with connecting conductors 146 being guided inside (see Fig. 5).

[0110] The connecting leads 146 comprise metal wires made of a less expensive material than those of the thermoelectric wires 132. For example, they are made of copper or nickel. Since the connecting leads 146 have an electrical conductor wire that has different thermoelectric properties than the thermoelectric wires 132, a measuring resistor 156 is provided inside the connecting element 114.

[0111] The outer casing 144 is made of a high-temperature-resistant material, such as high-temperature-resistant stainless steel. Inside the outer casing 144 is an electrically insulating, high-temperature-resistant material, in particular a high-temperature-resistant powder. This material is a mineral.

[0112] In both the embodiment of a temperature measuring device 10 shown in Figures 1 to 3 and in this embodiment of a temperature measuring device 110, the area inside the sleeve 48; 114, in particular the area where the connection points are located, is filled with an electrically insulating, high-temperature resistant material such as high-temperature cement.

[0113] The connecting lines 146 guided in the outer sheath 144, as well as the connecting lines 146 up to the connection point, consist of a pure metal conductor without cable insulation and are arranged at a distance from each other, aligned parallel to the longitudinal direction of the outer sheath 144 and embedded in the electrically insulating, high-temperature-resistant material.

[0114] The connecting leads 146 protrude from the outer sheath 144 at its end face and are connected to the thermocouple wires 132 protruding from the insulating rod 130. Each thermocouple wire 132 forms a connection point with a connecting lead 146.

[0115] In this embodiment as well, the connection points between connecting leads 146 and thermowire 132 are located in the connection element 114 to protect the connection points. The connection element 114 comprises a sleeve 148, wherein the sleeve 148 has a first and a second end face.

[0116] The connecting element 114 is firmly connected to the insulation rod 130 at its first end face by means of a metallic fixing ring 136 in the region of the free end of the insulation rod 130. As can be seen particularly in Fig. 6, the first conductor arrangement 116, the connecting element 114 and the insulation rod 130 together with the connecting conductors 146 and thermocouple wires 132 contained therein form a structural unit, namely a sensor module 150.

[0117] The protective tube 124, the protective cover 126 and the support tube 128 form a protective fitting 160, wherein the protective fitting 160 forms a separate component independent of the sensor module 150.

[0118] To connect the protective fitting 160 to the sensor unit 150, a clamping connection 170 is provided, which is attached to the protective fitting 160. The clamping fitting 170 comprises a clamping sleeve 172, which is fixedly connected to the support tube 128 at one end. At the other end of the clamping sleeve 172, offset inwards from the end face, is a wall 174 with a passage 176 for the insulating rod 130. A clamping screw connection 180 is provided at the same end of the clamping sleeve 172. The clamping screw connection 180 comprises a clamping device 182 with wedge elements and threaded elements 184 for screwing.

[0119] To connect the protective fitting 160 to the sensor unit 150, the insulating rod 130 is inserted into the protective fitting 160. The protective fitting 160 is then attached to the connection element 114 using the compression fitting 180. In the assembled state, the connection element 114 is located essentially inside the compression fitting 180.

[0120] In embodiments not shown, the number of thermocouples may vary. For example, fewer than three or more than three thermocouples may be provided.

[0121] In an embodiment not shown, in which the connecting leads have an electrical conductor wire which has the same thermoelectric properties as the thermowires, the measuring resistor 56 can be omitted.

[0122] Instead of the individual thermocouples of the multi-stage thermocouple shown in connection with Figures 1 to 7, the multi-stage thermocouple can have one thermocouple wire of a first polarity and at least two thermocouple wires of a second polarity, wherein the at least two thermocouple wires of the second polarity are each connected to the one thermocouple wire of the first polarity, forming a measuring junction.

[0123] This alternative embodiment of a multi-stage thermocouple is shown in Fig. 9. Here, a single thermocouple wire of first polarity 232 is provided, but three thermocouple wires with opposite second polarity 236a, 236b, 236c are included. As can be seen in Fig. 9, the single thermocouple wire of first polarity 232 can be positive or negative. Similarly, the three thermocouple wires with opposite second polarity 236a, 236b, 236c can be negative or positive.

[0124] The three thermowires of the second polarity 236a, 236b, 236c are firmly connected to the thermowire of the first polarity 232, the connection points forming the measuring points 234a, 234b, 234c and the connection points of the individual thermowires of the second polarity 236a, 236b, 236c with the thermowire of the first polarity 232 are arranged one after the other along the thermowire of the first polarity 232.

[0125] The three thermocouple wires of the second polarity 236a, 236b, 236c and the thermocouple wire of the first polarity 232 can be made from the aforementioned materials for thermocouple wires, as in the embodiment of a multi-stage thermocouple shown in conjunction with Fig. 8. The thermocouple wire of the first polarity 232 is mechanically reinforced compared to the at least two thermocouple wires of the second polarity 236a, 236b, 236c by having a larger diameter.

[0126] For processing the measurement signals at measuring points 234a, 234b, and 234c, integrated IO-Link electronics can be provided. The integrated IO-Link electronics can convert the thermoelectric voltage directly into digital signals within the temperature sensor, thus reducing interference on the line.

Claims

22 Patent claims:

1. Temperature measuring device comprising a measuring element (12; 112), a connection element (14; 114) with a housing, a conductor arrangement (16; 116) wherein the conductor arrangement (16; 116) comprises at least sectional connecting conductors (46; 146), a data acquisition device (20; 120) wherein the data acquisition device (20; 120) is connected to the measuring element (12; 112) by means of the conductor arrangement (16; 116), at least one thermocouple with at least two different thermocouple wires (32; 132; 232, 236a, 236b, 236c) each having two opposite ends, wherein the two thermocouple wires (32; 132; 232, 236a, 236b, 236c) are connected at one end in a measuring point (34a, 34b, 34c) are connected to each other and at the other end to a connecting line, forming a connection point, wherein the measuring point (34a, 34b, 34c) is provided in the measuring element (12; 112) and the connection points between connecting lines (46;146) and thermocouple wire (32; 132; 232, 236a, 236b, 236c) are located inside the housing of the connection element (14; 114), characterized in that the conductor arrangement (16; 116) has a first conductor section (40; 140) comprising an outer sheath (44; 144) with a first end and an oppositely located second end, wherein the at least two connection leads (46; 146) are guided in the outer sheath (44; 144), the outer sheath (44; 144) is firmly connected to the connection element (14; 114) in the region of its first end, and the outer sheath (44; 144) is filled internally with an electrically insulating, high-temperature-resistant material, at least in the region of the first end.

2. Temperature measuring device according to claim 1, characterized in that the interior of the housing of the connection element (14; 114) is filled with an electrically insulating, high-temperature resistant material.

3. Temperature measuring device according to one of the preceding claims, characterized in that the electrically insulating, high-temperature resistant material is a mineral material, in particular high-temperature cement.

4. Temperature measuring device according to one of the preceding claims, characterized in that the high-temperature resistant material is in powder form and is located in powder form in the outer jacket.

5. Temperature measuring device according to one of the preceding claims, characterized in that the connecting leads (46; 146) consist only of electrically conductive material, at least in the area from the outer sheath (44, 144) to the connection point between connecting leads (46; 146) and thermowire (32; 132; 232, 236a, 236b, 236c).

6. Temperature measuring device according to one of the preceding claims, characterized in that the connecting element (14; 114) and / or the outer casing (44; 144) is made of stainless steel, in particular of a high-temperature resistant stainless steel.

7. Temperature measuring device according to one of the preceding claims, characterized in that the measuring element (12, 112) has an outer protective element and the measuring points (34a, 34b, 34c; 234a, 234b, 234c) are located inside the outer protective element.

8. Temperature measuring device according to one of the preceding claims, characterized in that the connecting element (14; 114) comprises a sleeve (48; 148) with a first end face and a second end face, wherein the outer protective element (12; 112) is arranged on the first end face and the outer sheath (44; 144) is arranged on the second end face of the connecting element (14; 114).

9. Temperature measuring device according to one of the preceding claims, characterized in that an insulating rod (30; 130) is provided which surrounds the measuring points (34a, 34b, 34c).

10. Temperature measuring device according to claim 9, characterized in that the insulating rod (30) has a free end and the insulating rod (30) is firmly connected to the outer protective element in the area of ​​the free end.

11. Temperature measuring device according to claim 9, characterized in that the insulating rod (130) has a free end and the insulating rod (130) is firmly connected to the connecting element (114) in the area of ​​the free end.

12. Temperature measuring device according to one of claims 7 to 11, characterized in that the connecting element (14) is permanently connected to the outer protective element.

13. Temperature measuring device according to one of claims 7 to 11, characterized in that the connecting element (114) is detachably connected to the outer protective element.

14. Temperature measuring device according to claim 13, characterized in that a clamping screw connection (180) is provided which is designed to connect the outer protective element and the connecting element (114).

15. Temperature measuring device according to one of the preceding claims, characterized in that the line arrangement (16; 116) has a second line section (42) which forms an extension of the first line section (16; 116) (40), wherein the second line section (42) has a first end and an oppositely located second end and is designed to be flexible.

16. Temperature measuring device according to claim 15, characterized in that a transition element (60) is provided which is firmly connected to the first line section (40) in the area of ​​the second end of the first line section (40).

17. Temperature measuring device according to one of the preceding claims, characterized in that the connecting leads (46; 146) have an electrical conducting wire which has different thermoelectric properties than the thermoelectric wires (32; 132; 232, 236a, 236b, 236c).

18. Temperature measuring device according to one of the preceding claims, characterized in that an additional temperature measuring device, in particular a measuring resistor (56; 156) is provided inside the connection element (14; 114). 25 19. Temperature measuring device according to one of the preceding claims, characterized in that at least one further thermocouple wire (32; 132; 232, 236a, 236b, 236c) is provided in the measuring element (12; 112), wherein each thermocouple wire (32; 132; 232, 236a, 236b, 236c) is connected to a connecting line (46; 146) and the additional connecting lines (46; 146) are guided inside the outer sheath (44; 144).

20. Temperature measuring device according to one of the preceding claims, characterized in that a multi-stage thermocouple is provided.

21. Temperature measuring device according to one of the preceding claims, characterized in that at least two further thermowires (32; 132) of a thermocouple are provided in the measuring element (12; 112), wherein two of the at least two further thermowires (32; 132) have different polarities and are connected to each other to form a measuring point.

22. Temperature measuring device according to one of the preceding claims, characterized in that at least one thermocouple wire of a first polarity (232) and at least two thermocouple wires of a second polarity (236a, 236b, 236c) are provided in the measuring element (12; 112), wherein the at least two thermocouple wires of the second polarity (236a, 236b, 236c) are each connected to the one thermocouple wire of the first polarity (232) to form a measuring point.

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