Thermal protection metal oxide rheostat with indicating circuit
By introducing an indicator circuit that changes the pin contact state by moving a slider in a thermally protected rheostat, the problems of complexity and high cost of existing thermally protected rheostats are solved, achieving compact and reliable signal output and simplified maintenance, suitable for rapid disconnection of circuits.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-26
- Publication Date
- 2026-03-27
AI Technical Summary
Existing thermal protection rheostats are complex and costly, and are not easy to maintain, making it difficult to protect equipment from overvoltage transients in circuits.
A thermal protection device comprising a variable resistor body and an indicator circuit within a housing is designed. By moving a slider in the event of a thermal event, the contact state of the pins is changed, providing a disconnection indication and simplifying the design of a microswitch.
It achieves a compact and reliable signal output, simplifies the maintenance process, ensures circuit safety and quick disconnection, and is suitable for 200kA short-circuit testing.
Smart Images
Figure CN121749060A_ABST
Abstract
Description
Technical Field
[0001] This disclosure generally relates to protecting electrical and electronic circuits and equipment from power surges, and more specifically, to a thermally protected metal oxide rheostat including an indicating circuit. Background Technology
[0002] Overvoltage protection devices are used to protect electronic circuits and components from damage caused by overvoltage fault conditions. These devices can include metal oxide varistors (MOVs) connected between the circuit to be protected and ground. MOVs have specific current-voltage characteristics that allow them to be used to protect such circuits from catastrophic voltage surges. Typically, these devices utilize spring elements and linking materials that melt to form an open circuit during abnormal conditions. In particular, when a voltage greater than the nominal or threshold voltage is applied to the device, current flows through the MOV, generating heat. This causes the linking elements to melt. Once the link melts, an open circuit is created, preventing the MOV from catching fire.
[0003] While thermal protection rheostats exist, currently available thermal trip rheostats involve complex components and are costly to manufacture. Another drawback of known thermal protection rheostats is that they are single-use components and must be replaced once thermal tripping is triggered. Because thermal circuit breakers are typically enclosed in a housing, individuals maintaining the equipment may not be able to easily determine when a thermal tripping has occurred and when replacement is necessary.
[0004] Therefore, there is a need for an efficiently constructed varistor to protect sensitive circuits and equipment from abnormal overvoltage transients, while also being easy to maintain and repair. This improvement is made with these and other factors in mind. Summary of the Invention
[0005] This summary is provided to present selected concepts in a simplified form, which will be further described in the detailed description below. This summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to help determine the scope of the claimed subject matter.
[0006] In some embodiments, the thermal protection device may include a rheostat body within a housing, the rheostat body including a thermoelectric electrode disposed along a first side. The thermal protection device may also include a first terminal connected to the first side and a second terminal connected to a second side of the thermoelectric electrode. The thermal protection device may further include an indicator circuit including a first pin and a second pin disposed along the first side of the rheostat body, wherein the second pin is connected to a slider, wherein a thermal event causes the slider to move between a first position and a second position, and wherein when the slider is in the second position, the first pin and the second pin are separated from each other.
[0007] In some embodiments, a metal oxide rheostat (MOV) device may include a rheostat body within a housing, the rheostat body including a thermoelectric electrode disposed along a first side, a first terminal connected to the first side, and a second terminal connected to a second side of the thermoelectric electrode. The MOV device may also include an indicator circuit including a first pin and a second pin disposed along the first side of the rheostat body, wherein the second pin is connected to a slider, wherein a thermal event causes a disconnection between the first terminal and the thermoelectric electrode, wherein the disconnection causes the slider to move between a first position and a second position, and wherein when the slider is in the second position, the first pin and the second pin are separated from each other.
[0008] In some embodiments, a thermal metal oxide varistor (TMOV) device may include a varistor body within a housing, the varistor body including a thermoelectric electrode disposed along a first side, a first terminal connected to the first side, and a second terminal connected to a second side of the thermoelectric electrode. The TMOV may also include an indicator circuit including a first pin and a second pin disposed along an inner wall of the housing, wherein the second pin is connected to a slider, wherein a thermal event causes a disconnection between the first terminal and the thermoelectric electrode, wherein the disconnection causes the slider to move along the inner wall between a first position and a second position, and wherein when the slider is in the second position, the first pin and the second pin are separated from each other. Attached Figure Description
[0009] The accompanying drawings illustrate exemplary embodiments designed to date for the practical application of their principles, and wherein:
[0010] Figure 1 A circuit diagram including an MOV device according to an embodiment of the present disclosure is depicted;
[0011] Figure 2 This is a top perspective view of an MOV device according to an embodiment of the present disclosure;
[0012] Figure 3 This is a cross-sectional view of an MOV device according to an embodiment of the present disclosure;
[0013] Figure 4 This is a top perspective view of an MOV device according to an embodiment of the present disclosure;
[0014] Figure 5 This is a top perspective view of an MOV device according to an embodiment of the present disclosure;
[0015] Figure 6 This is a top perspective view of an MOV device according to an embodiment of the present disclosure;
[0016] Figure 7This is a close-up perspective view of the terminal connections of an MOV device according to an embodiment of this disclosure; and
[0017] Figure 8 This is a bottom perspective view of an MOV device according to an embodiment of the present disclosure.
[0018] The accompanying drawings are not necessarily drawn to scale. The drawings are for illustrative purposes only and are not intended to depict specific parameters of this disclosure. The drawings are intended to describe typical embodiments of this disclosure and should therefore not be considered as limiting the scope. In the drawings, similar numbers denote similar elements.
[0019] Furthermore, for clarity, certain elements in some figures may be omitted or depicted not to scale. Cross-sectional views may be in the form of "slices" or "near-view" cross-sectional views; for clarity, some background lines that would otherwise be visible in the "true" cross-sectional view have been omitted. Additionally, for clarity, some reference numbers may be omitted in some figures. Detailed Implementation
[0020] The protection device according to this disclosure will now be described more fully below with reference to the accompanying drawings, in which embodiments of the system and method are illustrated. However, the protection device may be embodied in many different forms and should not be construed as limited to the embodiments described herein. Rather, these embodiments are provided to make this disclosure thorough and complete, and will fully convey the scope of the system and method to those skilled in the art.
[0021] Now go to Figure 1 This document describes a thermally protected variable resistor (TPV) device 10 for use with circuit 2 according to embodiments of the present disclosure. The TPV device 10 may be a thermally modified resistor (TMR). The simplified circuit 2 typically includes the TPV device 10, a power supply 3, and a protected circuit or device 4. As those skilled in the art will understand, during normal operation, the TPV device 10, which may be positioned in parallel between a first terminal of the power supply 3 and the protected circuit 4, is in a closed or open position, and the protected circuit 4 is powered by the power supply 3. As described below, in the event of an overvoltage, the TPV device 10 is open. The circuit 2 described herein is not intended to be limiting, but merely an illustrative example of a general circuit for the context.
[0022] Now go to Figures 2 to 4The MOV device (hereinafter referred to as the "device") 100 according to embodiments of the present disclosure will be described in more detail. Device 100 may be the same as or similar to the TPV device 10 described above. As shown, device 100 may include a housing 102 accommodating a rheostat body 106, which in this embodiment has a rectangular or cuboid shape. The rheostat body 106 may include a thermoelectric electrode 108 disposed along a first side 110 and an electrode (not shown) disposed along a second side 116. A first terminal 120 is electrically connected to the thermoelectric electrode 108 along the second side 116 of the rheostat body 106, while a second terminal 122 is electrically connected to the electrode. In some embodiments, the thermoelectric electrode 108 is a ceramic, silver, copper, aluminum, or copper-aluminum metallization layer.
[0023] The housing 102 may include a base 124 and a central portion 125, wherein the central portion 125 includes an inner wall 126 extending between peripheral walls 127. Although not shown, the housing 102 may include a top cover. The inner wall 126 and the peripheral walls 127 define an interior 128 of the housing 102. Within the interior 128 is a first end 130 of a first terminal 120, positioned adjacent to a slider 132. As will be described in more detail herein, the slider 132 may be positioned on top of / near the inner wall 126 and may be connected to an indicating circuit 136 including a first pin 138 and a second pin 140.
[0024] In some embodiments, the first terminal 120 may include a spring body 142 extending above the slider 132, the spring body 142 being located between a first end 130 and a second end 148 of the first terminal 120. The first end 130 of the first terminal 120 may extend through an opening 144 in the inner wall 126 and may be connected to the thermoelectric electrode 108 via a thermal link element (e.g., solder). If the thermal link element exceeds its melting point, for example in an overcurrent event, the spring body 142 will disengage from and move away from the thermoelectric electrode 108 exposed through the opening 144, resulting in a disconnection from the power supply. The thermal link element prevents the free end 130 from moving away from the thermoelectric electrode 108 before being heated, and thus also prevents the slider 132 from rotating toward the opening 144. In some embodiments, the first terminal 120 may include a protrusion 150 operable to engage the body 152 of the slider 132.
[0025] The indicator circuit 136 is operable to provide indication of the open / closed state of the first terminal 120 and the thermoelectric electrode 108. That is, in the first position of the slider 132, such as... Figures 2 to 3 As shown, the first pin 138 and the second pin 140 are in direct physical and electrical contact with each other. When the slider 132 is in the second position, that is, when the slider 132 rotates toward the opening 144, as... Figure 4As shown, the first pin 138 and the second pin 140 are disconnected from each other. This disconnection between the first pin 138 and the second pin 140 results in a change in the status signal. As shown, the second pin 140 is directly coupled to the slider 132, and the first end 154 of the first pin 138 is operable to engage / disengage the first end 158 of the second pin 140. The second end 160 of the first pin 138 and the second end 162 of the second pin 140 extend to the outside of the housing 102. In some embodiments, the second pin 140 may include a coiled portion 166 wound around a support 170 of the housing 102, causing the second pin 140 to operate as a torsion spring. More specifically, the second pin 140 may include an "L"-shaped first portion connected to one of the peripheral walls 127, while the first end 158 may extend within the body 152 of the slider 132. Thus, the second pin 140 provides a force against the spring body 142 of the first terminal 120 via the slider 132.
[0026] Figures 5 to 6 Another MOV device (hereinafter referred to as "device") 200 according to an embodiment of this disclosure is shown and will be described in more detail. Device 200 may be the same as or similar to Device 100 described above. Therefore, for the sake of brevity, only certain aspects of Device 200 will be described below. As shown, Device 200 may include a housing 202 accommodating a rheostat body 206, which may include a thermoelectric electrode 208 disposed along a first side and an electrode (not shown) disposed along a second side. A first terminal 220 is electrically connected to the thermoelectric electrode 208 along the second side of the rheostat body 206, while a second terminal 222 is electrically connected to the electrode. In some embodiments, the thermoelectric electrode 208 is a ceramic, silver, copper, aluminum, or copper-aluminum metallization layer.
[0027] The housing 202 may include a base 224 and a central portion 225, wherein the central portion 225 includes an inner wall 226 extending between peripheral walls 227. Although not shown, the housing 202 may include a top cover. The inner wall 226 and the peripheral walls 227 define an interior 228 of the housing 202. Within the interior 228 is a first end 230 of a first terminal 220 positioned adjacent to a slider 232. The slider 232 may be positioned on top of / near the inner wall 226 and may be connected to an indicating circuit 236 including a first pin 238 and a second pin 240.
[0028] In some embodiments, the first terminal 220 may include a spring body 242 extending above the slider 232, the spring body 242 being located between a first end 230 and a second end 248 of the first terminal 220. The first end 230 of the first terminal 220 may extend through an opening 244 in the inner wall 226 and may be connected to the thermoelectric electrode 208 via a thermal link element (e.g., solder). If the thermal link element exceeds its melting point, for example in an overcurrent event, the spring body 242 will disengage from the thermoelectric electrode 108 exposed through the opening 144 and move away from the thermoelectric electrode 208, resulting in a disconnection from the power supply. The thermal link element prevents the free end 230 from moving away from the thermoelectric electrode 208 before being heated, and thus also prevents the slider 232 from rotating toward the opening 244. In some embodiments, the first terminal 220 may include a protrusion 250 operable to engage the body 252 of the slider 232.
[0029] The indicator circuit 236 is operable to provide indication of the open / closed state of the first terminal 220 and the thermoelectric electrode 208. That is, in the first position of the slider 232, such as... Figure 5 As shown, the first pin 238 and the second pin 240 are in direct physical and electrical contact with each other. When the slider 232 is in the second position, that is, when the slider 232 rotates toward the opening 244, as... Figure 6 As shown, the first pin 238 and the second pin 240 are disconnected from each other. This disconnection between the first pin 238 and the second pin 240 results in a change in the status signal. As shown, the second pin 240 is directly coupled to the slider 232, and the first end 254 of the first pin 238 is operable to engage / disengage the first end 258 of the second pin 240. More specifically, the first end 254 of the first pin 238 may include a coiled portion 261, wherein when the slider 232 is in a first position, the second pin 260 is clamped between adjacent coiled elements of the coiled portion 261. The second end 260 of the first pin 238 and the second end 262 of the second pin 240 extend to the outside of the housing 202. In some embodiments, the second pin 240 may include a coiled portion 266 wound around the support 270 of the housing 202, causing the second pin 240 to operate as a torsion spring that provides a force against the spring body 242 of the first terminal 220 via the slider 232.
[0030] Figure 7An example first end 330 of a first terminal 320 according to an embodiment of the present disclosure is shown. In this embodiment, the first end 330 may include a retaining member 333 located within a central opening 335. The retaining member 333 may extend toward an opening 344 of the housing 302 and may be operable to engage the body 352 of the slider 332. The retaining member 333 may be a rib or a finger that helps reduce stress on the solder joint 337 by the slider 332 and helps to elevate the first terminal 320 in the event of a thermal disconnection. The retaining member 333 may be included as part of the first terminals 120 and 220 described herein.
[0031] Figure 8 The back side of an example device 400 according to an embodiment of the present disclosure is shown. As shown, the rheostat body 406 may include a second terminal 422 disposed along a second side 416 of the rheostat body 406. That is, a first end 480 of the second terminal 422 may extend along the electrodes of the rheostat body 406, and a second end 482 of the second terminal 422 may extend to the outside of the device housing 402. Device 400 may be the same as or similar to devices 100, 200 and 300 described above.
[0032] In summary, the embodiments described herein offer at least the following benefits. First, the indicating function is mechanically linked to the thermal circuit breaker and provides a reliable / accurate signal output. Second, these devices are compact in design and feature a simplified microswitch / indicator design, saving space for end-customer applications. Third, the fast, robust, and reliable design of the thermal disconnection mechanism contributes to safe survivability (interrupting main circuit current), for example, under a 200kAsscr test.
[0033] As used herein, elements or steps described in the singular and beginning with "a" or "an" should be understood to not exclude plural elements or steps unless such exclusion is explicitly stated. Furthermore, references to "one embodiment" in this disclosure are not intended to exclude the existence of additional embodiments that also incorporate the described features.
[0034] The use of “including,” “comprising,” or “having,” and variations thereof in this document means to include the items listed below and their equivalents, as well as additional items. Therefore, the terms “including,” “comprising,” or “having,” and variations thereof are open-ended expressions and may be used interchangeably throughout this document.
[0035] The scope of this disclosure is not limited to the specific embodiments described herein. In fact, various other embodiments and modifications of this disclosure, besides those described herein, will be apparent to those skilled in the art from the foregoing description and drawings. Therefore, such other embodiments and modifications are intended to fall within the scope of this disclosure. Furthermore, this disclosure has been described herein in the context of specific implementations for specific purposes in specific environments. Those skilled in the art will recognize that its usefulness is not limited thereto, and that this disclosure can be advantageously practiced in any number of environments for any purpose. Therefore, the claims are to be interpreted in accordance with the full breadth and spirit of this disclosure as set forth herein.
Claims
1. A thermal protection device, the thermal protection device comprising: The rheostat body inside the housing includes a thermoelectric electrode disposed along a first side; A first terminal connected to the first side, and a second terminal connected to the second side of the thermoelectrode; and An indicator circuit includes a first pin and a second pin disposed along a first side of the rheostat body, wherein the second pin is connected to a slider, wherein a thermal event causes the slider to move between a first position and a second position, and wherein the first pin and the second pin are separated from each other when the slider is in the second position.
2. The thermal protection device according to claim 1, wherein, The housing includes an inner wall, wherein the inner wall includes an opening, and wherein when the slider is in the first position, a first end of the first terminal extends through the opening.
3. The thermal protection device according to claim 2, wherein, The first end of the first terminal includes a protrusion operable to engage the body of the slider.
4. The thermal protection device according to claim 1, wherein, The second pin is a torsion spring coupled to the peripheral wall of the housing.
5. The thermal protection device according to claim 1, wherein, The first pin includes a first end extending into the housing, and wherein when the slider is in the first position, the first end is in direct contact with the second pin.
6. The thermal protection device according to claim 5, wherein, The first end of the first pin includes a coiled portion.
7. The thermal protection device according to claim 1, wherein, The second pin includes a coiled portion that is wound around a support member of the housing.
8. The thermal protection device according to claim 1, wherein, The first terminal includes a spring body extending above the slider.
9. The thermal protection device according to claim 1, wherein, The first terminal is connected to the thermal electrode via a thermal link material.
10. A metal oxide varistor (MOV) device, comprising: The rheostat body inside the housing includes a thermoelectric electrode disposed along a first side; A first terminal connected to the first side, and a second terminal connected to the second side of the thermoelectrode; and An indicator circuit includes a first pin and a second pin disposed along a first side of the rheostat body, wherein the second pin is connected to a slider, wherein a thermal event causes a disconnection between the first terminal and the thermal electrode, wherein the disconnection between the first terminal and the thermal electrode causes the slider to move between a first position and a second position, and wherein when the slider is in the second position, the first pin and the second pin are separated from each other.
11. The MOV device according to claim 10, wherein, The housing includes an inner wall, wherein the inner wall includes an opening, and wherein when the slider is in the first position, a first end of the first terminal extends through the opening.
12. The MOV device according to claim 11, wherein, The first end of the first terminal includes a protrusion operable to engage the body of the slider.
13. The MOV device according to claim 10, wherein, The second pin is a torsion spring coupled to the peripheral wall of the housing.
14. The MOV device according to claim 10, wherein, The first pin includes a first end extending into the housing, and wherein when the slider is in the first position, the first end is in direct contact with the second pin.
15. The MOV device according to claim 14, wherein, The first end of the first pin includes a coiled portion, and the second pin is located between two adjacent coiled elements of the coiled portion when the slider is in the first position.
16. The MOV device according to claim 10, wherein, The second pin includes a coil wrapped around a support member of the housing.
17. The MOV device according to claim 10, wherein, The first terminal includes a spring body extending above the slider.
18. A thermal metal oxide varistor (TMOV) device, comprising: The rheostat body inside the housing includes a thermoelectric electrode disposed along a first side; A first terminal connected to the first side, and a second terminal connected to the second side of the thermoelectrode; and An indicator circuit includes a first pin and a second pin disposed along the inner wall of the housing, wherein the second pin is connected to a slider, wherein a thermal event causes a disconnection between the first terminal and the thermal electrode, wherein the disconnection between the first terminal and the thermal electrode causes the slider to move along the inner wall between a first position and a second position, and wherein when the slider is in the second position, the first pin and the second pin are separated from each other.
19. The TMOV device according to claim 18, wherein, The inner wall includes an opening, and wherein when the slider is in the first position, a first end of the first terminal extends through the opening.
20. The TMOV device according to claim 18, wherein, The first end of the first terminal includes a protrusion operable to engage the body of the slider.