A tmov temperature-sensitive resistor

Abstract

The utility model relates to a pressure sensitive resistance technical field, and disclose a kind of TMOV temperature type pressure sensitive resistance, including pressure sensitive resistance sheet, electrode, electronic lead, temperature fuse and paper tape adhesive tape.Pressure sensitive resistance sheet is core conductive element, realizes surge voltage suppression and overvoltage protection;Two electronic leads one end is welded with pressure sensitive resistance sheet two sides, and the other end connects external circuit.Electrode is fixed on the one side end surface of pressure sensitive resistance sheet and one electronic lead, temperature fuse is connected with this electronic lead and is soldered fixed, can be disconnected when pressure sensitive resistance sheet overheats.Paper tape adhesive tape is wrapped electronic lead, which is away from electrode and temperature fuse, and is adhered on insulating paper board.The utility model temperature fuse can be disconnected when the heat quantity of pressure sensitive resistance exceeds normal use, can effectively prevent resistance burst, guarantee component and circuit safety, and pressure sensitive resistance can realize surge voltage suppression function, ensure component stable work.

Description

Technical Field

[0001] This utility model belongs to the field of varistor technology, specifically relating to a TMOV temperature-sensitive varistor. Background Technology

[0002] In fields such as power electronics, consumer electronics, and industrial control, circuit systems often face surge voltage threats caused by lightning strikes and power grid fluctuations. Without effective protection, surge voltages can easily damage precision components such as chips and capacitors, leading to equipment failure or even complete scrapping. Therefore, surge protection components are a crucial part of safe circuit operation. Among them, TMOV (Thermally Protected Metal Oxide Varistor) is a new type of component that integrates surge suppression and overheat protection. With its dual characteristics of surge protection and thermal safety assurance, it is gradually becoming an important alternative to traditional single-protection components. Its core design concept is to combine a temperature protection mechanism with a varistor to suppress surge voltage while avoiding safety risks caused by component overheating.

[0003] However, traditional varistors (non-TMOV type) rely solely on their nonlinear volt-ampere characteristics for surge suppression, lacking targeted thermal protection design. When abnormal conditions such as sustained overvoltage or short circuits occur in the circuit, the varistor's performance deteriorates due to prolonged heating, and may even lead to casing explosion and internal material splashing. This single protection mode not only directly damages surrounding components but may also cause safety accidents such as fires and electric shocks. It cannot meet the requirements of modern power systems for dual safety protection and is difficult to adapt to application scenarios with high safety requirements, becoming a core defect restricting the application range of traditional varistors.

[0004] Even though some existing technologies attempt to add temperature protection components next to the varistor, they generally suffer from design flaws: on the one hand, the correlation between the temperature protection component and the varistor is insufficient, making it impossible to accurately sense the real-time temperature changes of the varistor. This results in either delayed protection due to temperature response lag or malfunctions due to external environmental interference. On the other hand, the connection stability between the temperature protection component and the varistor and circuit leads is poor, lacking reliable fixing and insulation structures. In long-term use, problems such as loose connections and protection failures are prone to occur, failing to truly achieve the design goal of synergistic operation of surge protection and thermal protection, and making it difficult to achieve the stable and reliable dual protection effect pursued by TMOV temperature-type varistors.

[0005] In view of this, we propose a TMOV temperature-sensitive varistor to solve the above problems. Utility Model Content

[0006] The present invention aims to solve the technical problem that in the prior art, the varistor can only suppress surge voltage, lacks an overheat protection mechanism, and is prone to bursting when it overheats abnormally, posing a safety hazard.

[0007] To achieve the above objectives, this utility model provides the following technical solution:

[0008] A TMOV temperature-sensitive varistor includes:

[0009] Varistors, as the core conductive components, are used to achieve surge voltage suppression.

[0010] The electronic leads consist of two wires, one end of which is welded and fixed to both sides of the varistor, and the other end is used to connect to an external circuit.

[0011] An electrode is provided, which is fixedly connected to one end face of the varistor and one of the electronic leads;

[0012] A thermal fuse is connected in series with an electronic lead having electrodes, and the thermal fuse and the electronic lead are fixed by soldering. The thermal fuse works in conjunction with a varistor to disconnect the connection when the heat generated by the varistor exceeds the normal operating temperature.

[0013] Paper tape is wrapped around the outside of the electronic leads that are away from the electrodes and thermal fuses, and is used to fix, insulate and cushion the electronic leads.

[0014] As a preferred option, the varistor is made of a material with nonlinear volt-ampere characteristics, which can clamp the voltage during overvoltage and protect other components in the circuit. Its diameter is 5-25mm and its thickness is 2-9mm, ensuring good surge voltage absorption capability.

[0015] Preferably, the electrodes are made of copper and have a thickness of 0.5–10 mm to ensure current conduction efficiency and good fit with the varistor.

[0016] Preferably, the thermal fuse is a thermally fused fuse, and its melting temperature is set according to the normal heating limit of the varistor.

[0017] Preferably, the rated operating temperature of the thermal fuse is set to 1.1-1.3 times the maximum normal operating temperature of the varistor. When the heat generated by the varistor exceeds the normal range and the temperature reaches the rated operating temperature of the thermal fuse, the thermal fuse will automatically melt and disconnect the circuit.

[0018] Preferably, the electronic leads are made of tin-plated copper wire with a diameter of 0.5–1.5 mm.

[0019] Preferably, the paper tape is an insulating kraft paper tape, which adheres and fixes the electronic leads to the insulating cardboard. The electronic leads adhered and fixed to the insulating cardboard have an inverted U-shaped structure, and the paper tape has two wrapping points for the electronic leads at the inverted U-shaped structure.

[0020] Preferably, the two electronic leads are positioned at an angle at one end of the varistor.

[0021] Preferably, the thermal fuse is a D8 type thermal fuse with a rated operating temperature T of 136℃, a melting temperature of 131℃, a holding temperature T of 108℃, a limiting temperature T of 200℃, a rated current Iᵣ of 5A, and a rated voltage Uᵣ of 300V.

[0022] Preferably, the paper tape and insulating cardboard have round holes punched in them, with each round hole located between two adjacent sets of varistors.

[0023] Compared with the prior art, the technical effects and advantages of this utility model are:

[0024] This TMOV temperature-controlled varistor achieves overload protection by connecting a temperature fuse in series with the electronic leads. When the varistor generates heat beyond the normal range due to abnormal conditions, the temperature reaches the rated operating temperature of the temperature fuse, which will automatically melt and disconnect the circuit. This fundamentally prevents the varistor from exploding due to continuous heating, effectively reducing safety hazards and improving the safety of the component.

[0025] Using paper tape to wrap the internal components in multiple reverse layers not only firmly fixes the varistor, electrodes, and thermal fuse, preventing them from loosening or shifting, but also provides good insulation to prevent leakage between the internal components and the external environment. At the same time, the paper tape has a certain cushioning property, which can reduce the damage to the internal components from external impacts and extend the product's service life.

[0026] The materials and dimensions of each component are designed in a reasonable way. For example, the zinc oxide varistor ensures surge suppression, the copper electrodes ensure current conduction, the tinned copper wire electronic leads improve bending resistance, and the ceramic shell thermal fuse enhances high temperature resistance. As a result, the entire varistor has good electrical performance and structural stability, and can meet the needs of various application scenarios. Attached Figure Description

[0027] Figure 1 This is a first-view diagram of the present invention;

[0028] Figure 2 This is a second-view diagram of the present invention;

[0029] Figure 3This is a first-view view of the paper tape and insulating cardboard of this utility model after they have been removed.

[0030] Figure 4 This is a second-view view of the paper tape and insulating cardboard of this utility model after they have been removed.

[0031] Figure 5 This is a first-view view of the TMOV temperature-sensitive varistors of this utility model arranged at equal intervals;

[0032] Figure 6 This is a second-view perspective view of the TMOV temperature-sensitive varistors of this utility model, arranged at equal intervals.

[0033] In the diagram: 1. Varistor; 2. Electronic lead; 3. Electrode; 4. Thermal fuse; 5. Paper tape; 6. Insulating cardboard; 7. Wrapping area; 8. Round hole; 9. Silicone cushioning pad. Detailed Implementation

[0034] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0035] The following combination Figures 1 to 6 This application will be described in further detail.

[0036] This application discloses a TMOV (Temperature-Modulated Varistor) comprising a varistor 1, an electrode 3, electronic leads 2, a thermal fuse 4, and paper tape 5. The varistor 1, as the core conductive component, functions to suppress surge voltage and provide critical overvoltage protection for the circuit. Two electronic leads 2 are provided, one end of which is welded to both sides of the varistor 1, and the other end is used to connect to an external circuit. One electrode 3 is fixedly connected to one end face of the varistor 1 and one of the electronic leads 2. The thermal fuse 4 is connected in series with the electrode 3. An electronic lead 2 is attached to a thermal fuse 4, which is fixed to the electronic lead 2 by soldering. The thermal fuse 4 works with the varistor 1 to disconnect when the heat generated by the varistor 1 exceeds the normal operating temperature. Paper tape 5 is wrapped around the outside of the electronic lead 2, which is away from the electrode 3 and the thermal fuse 4, to fix, insulate and buffer the electronic lead 2. The paper tape 5 is used to bond and fix the electronic lead 2 to the insulating cardboard 6. The electronic lead 2 bonded and fixed to the insulating cardboard 6 has an inverted U-shaped structure, and the paper tape 5 has two wrapping points 7 at the inverted U-shaped structure of the electronic lead 2.

[0037] The varistor 1 is made of zinc oxide varistor material. Specifically, it is made of zinc oxide varistor material, which has excellent nonlinear volt-ampere characteristics. It can quickly clamp the voltage when the circuit is over-voltaged and efficiently absorb surge energy. Compared with other ordinary resistor materials, it has a more significant protection effect on other precision components in the circuit. It can effectively prevent components from being damaged by over-voltage and greatly extend the service life of the entire circuit system.

[0038] The diameter of the varistor 1 is set to 5-25mm and the thickness is set to 2-9mm. This size range has been precisely calculated to ensure that the varistor 1 has sufficient volume to store and release surge energy and ensure good surge voltage absorption capability, while not occupying too much circuit space due to excessive size. This adapts to the needs of various installation scenarios and improves the versatility of the product.

[0039] The outer surface of the varistor 1 (except for the end face connected to the electrode 3 and electronic lead 2) is coated with a high-temperature resistant insulating coating made of silicone resin, with a coating thickness of 0.5–1.5 mm. This coating effectively enhances the moisture resistance and insulation of the varistor 1, preventing leakage due to condensation or dust accumulation even in humid environments, thus reducing the risk of short circuits. Furthermore, the coating process employs vacuum spraying followed by drying at 120°C for 30 minutes, ensuring a uniform, bubble-free coating and more stable and durable protection, further improving the operational reliability of the varistor 1.

[0040] Electronic lead 2 is a key conductive component connecting the varistor 1 to the external circuit, bearing the important responsibility of current transmission. Electronic lead 2 uses tin-plated copper wire. The tin plating effectively prevents oxidation and corrosion of the copper wire, extending the service life of electronic lead 2, while reducing contact resistance and ensuring the stability of current transmission. The wire diameter is set at 0.5–1.5 mm. This wire diameter meets the current carrying requirements during normal circuit operation, avoiding overheating and burnout due to excessive current caused by an excessively thin wire diameter, while also avoiding increased product cost and installation difficulty due to an excessively thick wire diameter, thus achieving a balance between performance and cost.

[0041] The two electronic leads 2 are located at one end of the varistor 1 and are set at an angle. This angled structure can avoid unnecessary interference between the electronic leads 2 and other components of the varistor 1, and at the same time reserve sufficient space for the installation of other components, which facilitates the assembly operation of the entire product and improves the assembly efficiency. In addition, the electronic leads 2, which are glued and fixed on the insulating cardboard 6, have an inverted U-shaped structure. The inverted U-shaped structure has a certain elastic buffering capacity. When the circuit is subjected to slight vibration, it can absorb the vibration energy through its own deformation, reduce the stress impact of vibration on the welding joint between the electronic leads 2 and the varistor 1, and reduce the risk of the welding joint falling off.

[0042] A silicone buffer pad 9 is placed between the inverted U-shaped electronic lead 2 and the insulating cardboard 6. The silicone buffer pad 9 is bonded to the insulating cardboard 6 and the electronic lead 2 with high-temperature resistant double-sided adhesive. When the product is subjected to external vibration, the silicone buffer pad 9 can further absorb the stress of the vibration on the electronic lead 2, preventing the inverted U-shaped structure from breaking due to long-term vibration fatigue. This significantly improves the structural stability and service life of the electronic lead 2, ensuring the continuous normal operation of the entire circuit.

[0043] Electrode 3 is a crucial conductive connection component between the varistor 1 and the electronic lead 2, playing a key role in current conduction efficiency and connection stability. Electrode 3 is made of copper, which possesses excellent conductivity, effectively reducing losses during current transmission and ensuring efficient current conduction. The thickness of electrode 3 is set at 0.5–1 mm. This thickness ensures sufficient mechanical strength for proper fit with the varistor 1, preventing insufficient adhesion due to excessive thinness that could affect conductivity, while also avoiding excessive thickness that would increase the overall weight and size of the product, thus balancing conductivity performance with the need for lightweight design.

[0044] Electrode 3 and one end face of varistor 1 are fixed by a composite method of silver paste sintering and laser spot welding. The silver paste sintering layer is 0.1-0.3mm thick. Silver paste has good conductivity and adhesion, which can achieve a tight conductive connection between electrode 3 and varistor 1, ensuring stable current transmission. The laser spot welding points are evenly distributed along the edge of electrode 3 (4-6 welding points per ring). Laser spot welding has the characteristics of high welding strength, small and precise welding points, which can significantly enhance the mechanical fixing strength between electrode 3 and varistor 1, effectively preventing electrode 3 from falling off due to vibration, temperature changes and other factors during long-term use, and ensuring the long-term stable operation of the product.

[0045] The thermal fuse 4 is connected in series with an electronic lead 2 having an electrode 3. It is a key protective component to ensure the safe operation of the varistor 1 and can effectively prevent the varistor 1 from exploding due to overheating.

[0046] The thermal fuse 4 is a thermally blowing fuse, and its melting temperature is set according to the upper limit of the normal heating of the varistor 1, achieving a precise match between the protection function and the operating characteristics of the varistor 1. Furthermore, its rated operating temperature is set to 1.1-1.3 times the highest normal operating temperature of the varistor 1. When the heat generated by the varistor 1 exceeds the normal range and the temperature reaches the rated operating temperature of the thermal fuse 4, the thermal fuse 4 can automatically melt to cut off the circuit. This design not only avoids the thermal fuse 4 from accidentally melting due to temperature fluctuations during the normal operation of the varistor 1, but also ensures timely operation when the varistor 1 is truly overheated, quickly cutting off the circuit and preventing the varistor 1 from further heating up and bursting, thus maximizing circuit safety.

[0047] The thermal fuse 4 is a D8 model, with a rated operating temperature T of 136℃, a melting temperature of 131℃, a holding temperature T of 108℃, a limiting temperature T of 200℃, a rated current Iᵣ of 5A, and a rated voltage Uᵣ of 300V. All parameters of this thermal fuse 4 have undergone rigorous testing and verification, precisely matching the operating requirements of the varistor 1. When the varistor 1 experiences abnormal heating, it can reliably melt within the specified temperature range. Simultaneously, its rated current and rated voltage meet the requirements of most circuits, ensuring no malfunction under normal operating current and voltage, and guaranteeing the normal operation of the circuit.

[0048] The distance between the end faces of the thermal fuse 4 and the varistor 1 is set to 3-5mm. This distance ensures that the thermal fuse 4 can promptly sense the temperature change of the varistor 1 and respond quickly when the varistor 1 overheats. It also prevents the thermal fuse 4 from accidentally melting due to the normal operating temperature of the varistor 1 caused by the close distance. Furthermore, the thermal fuse 4 is encased in a high-temperature resistant insulating shell (made of polytetrafluoroethylene, with a wall thickness of 0.2-0.4mm). Polytetrafluoroethylene has excellent high-temperature resistance and insulation properties. The insulating shell can reduce the interference of the external environment (such as dust and humidity changes) on the temperature sensing of the thermal fuse 4, ensuring its accurate response to the heating of the varistor 1. On the other hand, it can prevent metal debris generated when the thermal fuse 4 melts from contacting other components, preventing secondary faults such as short circuits, and significantly improving the safety of the product.

[0049] The paper tape 5 and the insulating cardboard 6 together constitute the fixing, insulation and protection system of the electronic lead 2, which is crucial to ensuring the stable operation of the electronic lead 2 and the overall insulation performance of the product.

[0050] The paper tape 5 is an insulating kraft paper tape. The insulating kraft paper tape has good insulation properties, which can effectively isolate the current conduction between the electronic lead 2 and other components and prevent leakage accidents. At the same time, it has a certain strength and flexibility. When it is wrapped around the electronic lead 2 away from the electrode 3 and the thermal fuse 4, it can reliably fix the electronic lead 2 and prevent the electronic lead 2 from being displaced by external forces, which would affect the circuit connection. In addition, the kraft paper material also has a certain buffering performance, which can buffer and protect the electronic lead 2 when subjected to slight impacts, reducing the impact damage to the electronic lead 2.

[0051] The insulating paperboard 6 is made of epoxy glass cloth paperboard with a thickness of 1.5-2mm. Epoxy glass cloth paperboard has excellent insulation properties, high temperature resistance, and mechanical strength, providing a stable mounting support for the electronic lead 2. It also effectively isolates the electronic lead 2 from other external conductive components, ensuring the overall insulation performance of the product. Its good high temperature resistance can adapt to temperature changes during circuit operation, preventing deformation or damage to the insulating paperboard 6 due to excessive temperature, ensuring long-term stable insulation and support functions. Sufficient mechanical strength can withstand the weight of the electronic lead 2 and external forces generated during assembly and use, preventing the insulating paperboard 6 from breaking and ensuring the stability of the electronic lead 2 mounting structure.

[0052] The paper tape 5 and the insulating cardboard 6 have round holes 8 punched in them, with each round hole 8 located between two adjacent sets of varistors. The round hole 8 is designed to facilitate the positioning and fixing of the product during the production and assembly process, improving assembly accuracy and efficiency; at the same time, the round hole 8 also provides convenience for hanging or other types of installation of the product, expanding the installation methods of the product.

[0053] This TMOV temperature-controlled varistor uses a varistor element 1 as its core. During normal operation, the varistor element 1 suppresses surge voltage due to its inherent characteristics. Through the synergistic action of the electrode 3 and the electronic lead 2, the varistor element 1 is connected to the external circuit, ensuring stable current transmission. Simultaneously, paper tape 5 and insulating cardboard 6 work together to fix the electronic lead 2, ensuring overall structural stability and insulation performance. When a circuit malfunction causes the varistor element 1 to generate heat exceeding the normal range, the temperature fuse 4, connected in series with the electronic lead 2, senses the temperature change of the varistor element 1 and automatically disconnects upon reaching the rated operating temperature, cutting off the circuit. This prevents the varistor element 1 from exploding due to continuous overheating, providing dual protection for both the varistor element 1 and the entire circuit.

[0054] Traditional varistors can only suppress surge voltage on their own and lack overheat protection mechanisms. When faced with abnormal operating conditions such as continuous overvoltage or short circuits, they are prone to performance degradation or even explosion due to prolonged heating, which can damage surrounding components and cause safety accidents. This TMOV temperature-controlled varistor, however, incorporates a temperature fuse 4, creating a dual protection system of surge suppression and overheat protection. This system can promptly cut off the circuit when the varistor element 1 overheats abnormally, fundamentally avoiding the risk of resistor explosion. This significantly improves the safety and reliability of the circuit system and solves the core defect of traditional varistors that only focus on surge protection while neglecting overheat safety.

[0055] Existing temperature-protected varistor solutions have shortcomings in the installation and protection design of the temperature protection element. Either the improper spacing between the temperature protection element and the varistor 1 leads to malfunctions or delayed protection, or the lack of a stable connection structure and protective measures makes it prone to loose connections and temperature interference in complex environments, resulting in protection failure. This TMOV temperature-type varistor optimizes the design of the cooperation between the temperature fuse 4 and the varistor 1, and upgrades the structure and materials of components such as the electrode 3, electronic leads 2, and paper tape 5. This ensures that the temperature fuse 4 can accurately sense temperature changes in the varistor 1 and operate reliably. It also improves the stability of the overall structure in environments with vibration and humidity, effectively avoiding the problems of inaccurate protection and functional failure in existing solutions, further enhancing the effectiveness and long-term stability of temperature protection.

[0056] Finally, it should be noted that the above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Although the present utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A TMOV temperature-sensitive varistor, characterized in that, include: A varistor (1) serves as the core conductive element and is used to achieve surge voltage suppression. Electronic leads (2) are provided, one end of each electronic lead (2) is welded and fixed to both sides of the varistor (1), and the other end is used to connect to the external circuit. An electrode (3) is provided, which is fixedly connected to one end face of the varistor (1) and soldered to one of the electronic leads (2); A thermal fuse (4) is connected in series with an electronic lead (2) having an electrode (3), and the thermal fuse (4) and the electronic lead (2) are fixed by soldering. The thermal fuse (4) is used in conjunction with the varistor (1) to disconnect when the heat generated by the varistor (1) exceeds the normal operating temperature. Paper tape (5) is wrapped around the outside of the electronic lead (2) located away from the electrode (3) and the thermal fuse (4) to fix, insulate and buffer the electronic lead (2).

2. The TMOV temperature-sensitive varistor according to claim 1, characterized in that: The varistor (1) is made of a material with nonlinear volt-ampere characteristics, with a diameter of 5 to 25 mm and a thickness of 2 to 9 mm.

3. The TMOV temperature-sensitive varistor according to claim 1, characterized in that: The electrode (3) is made of copper and has a thickness of 0.5 to 10 mm.

4. The TMOV temperature-sensitive varistor according to claim 1, characterized in that: The thermal fuse (4) is a thermal fuse, and its melting temperature is set according to the normal heating limit of the varistor (1).

5. A TMOV temperature-sensitive varistor according to claim 4, characterized in that: The rated operating temperature of the thermal fuse (4) is set to 1.1-1.3 times the maximum normal operating temperature of the varistor (1). When the heat generated by the varistor (1) exceeds the normal range and the temperature reaches the rated operating temperature of the thermal fuse (4), the thermal fuse (4) will automatically melt to cut off the circuit.

6. The TMOV temperature-sensitive varistor according to claim 1, characterized in that: The electronic lead (2) is made of tin-plated copper wire, and the wire diameter of the electronic lead (2) is 0.5 to 1.5 mm.

7. A TMOV temperature-sensitive varistor according to claim 1, characterized in that: The paper tape (5) is an insulating kraft paper tape. The paper tape (5) glues and fixes the electronic lead (2) to the insulating cardboard (6). The electronic lead (2) glued and fixed to the insulating cardboard (6) has an inverted U-shaped structure, and the paper tape (5) has two wrapping points (7) for the electronic lead (2) at the inverted U-shaped structure.

8. A TMOV temperature-sensitive varistor according to claim 1, characterized in that: The two electronic leads (2) are located at one end of the varistor (1) and are set at an angle.

9. A TMOV temperature-sensitive varistor according to claim 7, characterized in that: The paper tape (5) and the insulating cardboard (6) have round holes (8) punched in them, and each round hole (8) is located between two adjacent groups of varistors.

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