Oil-resistant high-precision embedded thermal resistor

Abstract

The utility model provides an oil-resistant high-precision embedded thermal resistor, which belongs to the technical field of embedded thermal resistors, and comprises a reference end and a measuring end, the measuring end comprises a pipe sleeve head and two resistor elements arranged in the pipe sleeve head, the upper part of the pipe sleeve head is welded with an armored lead wire through laser, and the armored lead wire is connected with the reference end and the measuring end. The armored lead is sleeved with a silica gel heat shrink tube or a polytetrafluoroethylene tube, and a shielding lead is arranged between the armored lead and the reference end. According to the embedded thermal resistor, double resistor elements are adopted, so that the redundancy of a product is increased, cross validation can be realized, the measurement error is reduced, meanwhile, the lead directly connected with the measurement end is an armored lead, and a silica gel heat shrink tube or a polytetrafluoroethylene tube is sleeved on the lead, so that the oil resistance of the embedded thermal resistor is greatly improved, and the service life of the embedded thermal resistor is prolonged. In addition, environmental interference can be inhibited, thermal stability can be maintained, the service life can be prolonged, and the effective precision under actual working conditions is remarkably improved, especially in high-electromagnetic-interference, severe-temperature-change or corrosive environments.

Description

Technical Field

[0001] This utility model relates to the field of embedded thermal resistor technology, specifically to an oil-resistant, high-precision embedded thermal resistor. Background Technology

[0002] Resistance temperature detectors (RTDs) are the most commonly used temperature detectors in the medium and low temperature range. RTD temperature measurement is based on the characteristic that the resistance of a metallic conductor increases with temperature. Its main characteristics are high measurement accuracy and stable performance. Platinum RTDs offer the highest measurement accuracy and are widely used not only in industrial temperature measurement but also as standard reference instruments. Most RTDs are made of pure metals, with platinum and copper being the most common. Nickel, manganese, and rhodium are also increasingly used in RTD manufacturing. A variety of temperature-sensing materials are commonly used in metal RTDs, with platinum wire being the most prevalent. Besides platinum wire, industrial RTD materials include copper, nickel, iron, and iron-nickel composites.

[0003] Embedded resistance temperature detectors (RTDs) are commonly used to measure the bearing temperature of motors in power plant turbines, blowers, compressors, and smoke generator units. Compared to conventional RTDs, which have a minimum measuring end length of 2cm, embedded RTDs require even shorter measuring ends due to installation limitations. Ensuring the measurement accuracy and oil resistance of such short measuring ends is a problem that urgently needs to be solved. Utility Model Content

[0004] The purpose of this invention is to overcome the shortcomings and deficiencies of the existing technology and to provide an oil-resistant, high-precision embedded thermal resistor.

[0005] The technical solution adopted by this utility model is as follows: This application provides an oil-resistant high-precision embedded thermal resistor, including a reference end and a measuring end. The measuring end includes a tube sleeve and two resistive elements disposed inside the tube sleeve. The upper part of the tube sleeve is laser-welded with an armored lead wire. The armored lead wire is covered with a silicone heat shrink tubing or a PTFE tubing. A shielding lead wire is disposed between the armored lead wire and the reference end.

[0006] In some embodiments, the wall thickness of the upper part of the tube sleeve and the portion of the armored lead laser welded together is greater than the wall thickness of the lower part.

[0007] In some embodiments, the bottom of the sleeve head is provided with a convex portion, a first spring is sleeved on the sleeve head, and the lower end of the first spring is fixed to the convex portion, with at least a portion of the armored lead wire located inside the first spring.

[0008] In some embodiments, the upper end of the first spring is connected to a star-shaped clip, and the star-shaped clip has a through hole in the middle for the armor lead wire to pass through. The star-shaped clip moves with the extension and retraction of the first spring.

[0009] In some embodiments, the tube end is filled with epoxy resin.

[0010] In some embodiments, the length of the measuring end is no greater than 9 mm.

[0011] In some embodiments, the armored lead wire is provided with two sets of three-wire conductors and is respectively connected to two resistive elements, and the diameter of a single conductor is 0.25mm-0.3mm.

[0012] In some embodiments, the diameter of the armored lead wire is 1.5mm-2.5mm.

[0013] In some embodiments, a first armor sleeve is fitted onto one end of the shielding lead near the armor lead, and the lower end of the first armor sleeve is laser-welded to the armor lead. A second armor sleeve is provided on the shielding lead near the reference end. Epoxy resin is filled between the first and second armor sleeves and the shielding lead inside them. A second spring is fitted onto the connection between the first armor sleeve and the shielding lead, and the connection between the second armor sleeve and the shielding lead. One end of the second spring forms a flared opening and connects to the corresponding armor sleeve.

[0014] In some embodiments, a telescopic protective sleeve is provided between the star-shaped clip and the convex disc portion, and the telescopic protective sleeve extends and retracts as the star-shaped clip moves.

[0015] The beneficial effects of this utility model are as follows: The use of dual resistance elements in this utility model not only increases the redundancy of the product, but also enables cross-verification and reduces measurement errors. At the same time, the lead wires directly connected to the measuring end are armored and covered with silicone heat shrink tubing or PTFE tubing, which greatly improves the oil resistance of the embedded thermal resistor, suppresses environmental interference, maintains thermal stability and extends service life, and significantly improves the effective accuracy under actual working conditions, especially in environments with high electromagnetic interference, drastic temperature changes or corrosive environments. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, obtaining other drawings based on these drawings without creative effort still falls within the scope of this utility model.

[0017] Figure 1 A schematic diagram of an oil-resistant, high-precision embedded thermal resistor in this utility model;

[0018] Figure 2 A schematic diagram of a measuring end in this utility model;

[0019] Figure 3 A schematic diagram of the tube sleeve of this utility model;

[0020] Figure 4 A schematic diagram of another measuring end in this utility model. Detailed Implementation

[0021] The following description provides specific application scenarios and requirements for this specification, intended to enable those skilled in the art to make and use the contents of this specification. Various partial modifications to the disclosed embodiments will be apparent to those skilled in the art, and the general principles defined herein can be applied to other embodiments and applications without departing from the spirit and scope of this specification. Therefore, this specification is not limited to the embodiments shown, but rather to the widest scope consistent with the claims.

[0022] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "longitudinal", "lateral", "radial", "length", "width", "thickness", "upper", "lower", "left", "right", "front", "rear", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are mainly for the purpose of better describing this application and its embodiments, and are not intended to limit the indicated device, element or component to have a specific orientation, or to be constructed and operated in a specific orientation.

[0023] Secondly, the terms "first," "second," and similar words do not indicate any order, quantity, or importance, but are merely used to distinguish different components and should not be construed as limiting the embodiments of this application.

[0024] Furthermore, the terms "installation," "setup," "equipped with," "connection," and "connected" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral constructions; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium, or internal connections between two devices, components, or parts.

[0025] Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0026] Regarding the accompanying drawings of this application, it should be clearly understood that the drawings are for illustrative and descriptive purposes only and are not intended to limit the scope of this specification. It should also be understood that the drawings are not necessarily drawn to scale.

[0027] like Figures 1 to 4As shown in the figure, this specification provides an oil-resistant, high-precision embedded resistance temperature detector (RTD), including a reference end 1 and a measuring end 2. The measuring end 2 includes a sleeve head 3 and two resistive elements disposed within the sleeve head 3. The resistive elements are preferably thin-film resistive elements, requiring an operating temperature of -50 to +300℃. Simultaneously, the sleeve head 3 is filled with epoxy resin to encapsulate the two resistive elements. This configuration not only increases the product's redundancy but also allows for cross-verification. By comparing the data from the two resistive elements, if the error range is too large, it indicates that the RTD may be faulty.

[0028] Secondly, an armored lead wire 4 is laser-welded to the upper part of the sleeve head 3. The armored lead wire 4 is covered with a silicone heat shrink tubing or a PTFE tubing. A shielded lead wire 5 is provided between the armored lead wire 4 and the reference end 1. Traditional embedded thermal resistors generally only use shielded lead wire 5. When measuring the temperature of the motor bearings of power plant turbines, blowers, compressors, and smoke generators, it is easily corroded by oil. Therefore, by using an armored lead wire 4 and covering it with a silicone heat shrink tubing or a PTFE tubing, the oil resistance of the embedded thermal resistor is greatly improved. This suppresses environmental interference, maintains thermal stability, and extends service life, significantly improving the effective accuracy under actual working conditions, especially in environments with high electromagnetic interference, drastic temperature changes, or corrosive environments.

[0029] Furthermore, when embedded RTDs are used in the above-mentioned measurement environment, the length of the measuring end 2 cannot be too long due to installation limitations. However, this product can make the length of the measuring end 2 no more than 9mm. For example, when the measuring end 2 is only 6.5mm, it can still achieve Class A accuracy.

[0030] In some embodiments, the wall thickness of the upper part of the sleeve head 3 and the portion of the armored lead 4 laser-welded is greater than the wall thickness of the lower part. Since the sleeve head 3 is generally thin-walled, and traditional argon arc welding would burn through the sleeve head 3, damaging the resistive element, laser welding, suitable for thin-walled welding, is used; however, the wall thickness still needs to be increased for the welded portion. Figure 3 As shown, the wall thickness of the pipe sleeve 3 is 0.4mm-0.6mm, and the part used for welding is set in a frustum shape to increase its wall thickness.

[0031] In some embodiments, the bottom of the sleeve head 3 is provided with a convex portion 30, and a first spring 6 is sleeved on the sleeve head 3, with the lower end of the first spring 6 fixed to the convex portion 30, and at least a portion of the armored lead wire 4 located within the first spring 6. The first spring 6 effectively protects the measuring end and the armored lead wire 4 extending into the measuring part, especially for armored lead wires 4 with a smaller wire diameter. Optionally, the wire diameter of the armored lead wire 4 is 1.5mm-2.5mm.

[0032] In some embodiments, such as Figure 2As shown, the upper end of the first spring 6 is connected to a star-shaped clip 7. The star-shaped clip 7 has a through hole 70 in the middle for the armor lead wire 4 to pass through. The star-shaped clip 7 moves with the extension and retraction of the first spring 6. Generally, the device being tested is provided with a test port. The star-shaped clip 7 abuts against the edge of the test port, and the measuring end 2 extends into the test port for measurement.

[0033] Furthermore, such as Figure 4 As shown, a telescopic protective sleeve 11 is provided between the star-shaped clamp 7 and the convex disc 30. The telescopic protective sleeve 11 extends and retracts with the movement of the star-shaped clamp 7. The telescopic protective sleeve 11 also needs to be made of oil-resistant and high / low temperature-resistant material, such as silicone rubber or fluororubber. It should be noted that the telescopic protective sleeve 11 should not cover the bottom end face of the tube head 3, because the bottom end face is the main detection end face. This can further improve the oil resistance of the thermal resistor.

[0034] In some embodiments, the armored lead wire 4 is provided with two sets of three-wire conductors and is connected to two resistor elements respectively. The diameter of a single conductor is 0.25mm-0.3mm. The three-wire conductor can effectively eliminate lead resistance error and improve the accuracy of long-distance transmission.

[0035] In some embodiments, a first armored sleeve 8 is fitted onto one end of the shielding lead 5 near the armored lead 4. The lower end of the first armored sleeve 8 is laser-welded to the armored lead 4. A second armored sleeve 9 is provided on the shielding lead 5 near the reference end 1. Epoxy resin is filled between the first armored sleeve 8 and the second armored sleeve 9 and the shielding lead 5 therein. A second spring 10 is fitted onto the connection between the first armored sleeve 8 and the shielding lead 5, and the connection between the second armored sleeve 9 and the shielding lead 5. One end of the second spring 10 forms a flared opening and connects to the corresponding armored sleeve. The second spring 10 can protect the shielding lead 5.

[0036] In some embodiments, the shielding lead 5 of the reference end 1 is provided with a heat shrink tubing 12 for printing model identification, and the shielding lead 5 is provided with six wires, and the wires are provided with pin-type terminals 13.

[0037] In summary, after reading this detailed disclosure, those skilled in the art will understand that the foregoing detailed disclosure is presented by way of example only and is not restrictive. Although not explicitly stated herein, those skilled in the art will understand that the requirements of this application encompass various reasonable changes, improvements, and modifications to the embodiments. These changes, improvements, and modifications are intended to be made by this application and are within the spirit and scope of the exemplary embodiments of this application.

[0038] Furthermore, it should be understood that in the foregoing description of the embodiments of this application, various features are combined in a single embodiment, drawing, or description for the purpose of simplifying the understanding of a feature. However, this does not mean that the combination of these features is necessary, and those skilled in the art may readily identify some of the devices as separate embodiments when reading this application. That is, the embodiments in this application can also be understood as an integration of multiple sub-embodiments. It is also valid when each sub-embodiment contains fewer than all the features of a single foregoing disclosed embodiment.

[0039] Finally, it should be understood that the embodiments disclosed herein are illustrative of the principles of the embodiments of this application. Other modified embodiments are also within the scope of this application. Therefore, the embodiments disclosed herein are merely examples and not limitations. Those skilled in the art can adopt alternative configurations to implement the applications in this application based on the embodiments in this application. Therefore, the embodiments of this application are not limited to the embodiments precisely described in the application.

Claims

1. An oil-resistant high-precision embedded thermal resistor, characterized by comprising: The measuring end comprises a sleeve head and two resistance elements arranged in the sleeve head, an upper part of the sleeve head is laser welded with an armored lead, the armored lead is sleeved with a silica gel heat shrink tube or a tetrafluoro tube, and a shielding lead is arranged between the armored lead and the reference end.

2. The oil-resistant high-precision embedded thermal resistor according to claim 1, characterized in that, The wall thickness of the part of the sleeve head and the armored lead laser welded is greater than that of the lower part.

3. The oil-resistant high-precision embedded thermal resistor according to claim 1, characterized in that, A convex disc part is arranged at the bottom of the sleeve head, a first spring is sleeved on the sleeve head, and the lower end of the first spring is fixed with the convex disc part, and at least part of the armored lead is located in the first spring.

4. The oil-resistant high-precision embedded thermal resistor according to claim 3, characterized in that, The upper end of the first spring is connected with a star-shaped clip, a through hole is arranged in the middle of the star-shaped clip for the armored lead to pass through, and the star-shaped clip moves along with the first spring.

5. The oil-resistant high-precision embedded thermal resistor according to claim 1, characterized in that, The sleeve head is filled with epoxy glue.

6. The oil-resistant high-precision embedded thermal resistor according to claim 1, characterized in that, The length of the measuring end is not greater than 9 mm.

7. The oil-resistant high-precision embedded thermal resistor according to claim 1, characterized in that, Two groups of three-wire leads are arranged in the armored lead and connected with the two resistance elements respectively, and the diameter of a single lead is 0.25-0.3 mm.

8. The oil-resistant high-precision embedded thermal resistor according to claim 7, characterized in that, The diameter of the armored lead is 1.5-2.5 mm.

9. The oil-resistant high-precision embedded thermal resistor according to claim 1, characterized in that, A first armored sleeve head is sleeved on one end of the shielding lead close to the armored lead, the lower end of the first armored sleeve head is laser welded with the armored lead, a second armored sleeve head is arranged on the shielding lead close to the reference end, the first armored sleeve head and the second armored sleeve head are both filled with epoxy glue between the shielding lead and the shielding lead in the first armored sleeve head and the second armored sleeve head, a second spring is sleeved on the connection between the first armored sleeve head and the shielding lead and the connection between the second armored sleeve head and the shielding lead, and one end of the second spring is formed with a flared opening corresponding to the connection of the armored sleeve head.

10. The oil-resistant high-precision embedded thermal resistor according to claim 4, characterized in that, An extension protection sleeve is arranged between the star-shaped clip and the convex disc part, and the extension protection sleeve moves along with the star-shaped clip.

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