CN215185855U - Circuit protection device - Google Patents

Abstract

The utility model discloses a circuit protection device to three kinds of mode protection to device or circuit are realized. MOVs used in conventional circuit protection devices are rearranged and the number of MOVs is reduced under certain conditions so that they can be shared between the modes. These MOVs are further made using high surge performance discs/powders, achieving smaller disc sizes without affecting MOV performance. Thin disks replace thicker disks with higher voltage rated MOVs to reduce product size and cost. The utility model discloses a circuit protection device, it adopts two dishes to realize three kinds of mode protection, adopts three thin high surge performance dish to realize three kinds of mode protection to adopt three thin high surge performance dish to increase symmetrical thermal protection. The circuit protection device may be a stand-alone device or may be a surface mount device adapted to be attached to a printed circuit board.

Description

Circuit protection device

Technical Field

The embodiment of the utility model provides a relate to circuit protection device field, more specifically say, relate to a metal oxide varistor piles up for surge protection.

Background

Overvoltage protection devices are used to protect electronic circuits and components from damage due to overvoltage fault conditions. The overvoltage protection device may include a Metal Oxide Varistor (MOV) connected between the circuit to be protected and ground. A varistor is a voltage-dependent nonlinear device whose electrical characteristics resemble back-to-back zener diodes. The varistor is mainly composed of zinc oxide ZnO with small additions of other metal oxides such as bismuth, cobalt, manganese, etc. The MOV sinters into a ceramic semiconductor during the manufacturing operation and forms a crystalline microstructure that allows the MOV to dissipate very high levels of transient energy throughout the volume of the device. Accordingly, MOVs are commonly used for lightning and other high energy transient suppression in industrial or AC line applications. In addition, MOVs are also used in direct current DC circuits, such as low voltage power supplies and automotive applications. Their manufacturing process allows for many different physical dimensions, with radial lead pads being the most common.

The varistor body structure consists of a matrix of grain boundaries separated conductive zinc oxide grains, providing P-N junction semiconductor properties. These grain boundaries are responsible for blocking conduction at low voltages and are a source of nonlinear conduction at high voltages. The symmetrical, sharp breakdown characteristics of the MOV make it possible to provide excellent transient voltage suppression performance. When exposed to high voltage transients, varistor impedance changes by many orders of magnitude, from near open circuit to high conduction levels, clamping transient voltages to safe levels. Potentially damaging energy of the incoming transient pulse is absorbed by the MOV, thereby protecting vulnerable circuit elements.

Miniaturization of the components increases the sensitivity to electrical stress. For example, the structure and conductive paths of a microprocessor cannot handle the large currents that are instantaneously created by electrostatic discharge (ESD). These components operate at very low voltages and therefore voltage disturbances must be controlled to prevent device disruptions and potential or catastrophic failures. Sensitive devices such as microprocessors are being employed at exponential speeds. In addition to being the core of computers, microprocessors are also increasingly used in household appliances, industrial controls, automobiles and even toys. Current electronic/industrial applications require electronic components with smaller size and higher performance, making product size a critical factor for some applications.

It is with respect to these and other considerations that the improvements of the present invention may be useful.

SUMMERY OF THE UTILITY MODEL

This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the detailed description. This summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended as an aid in determining the scope of the claimed subject matter.

According to an exemplary embodiment of the circuit protection device of the present invention, may comprise a first Metal Oxide Varistor (MOV) shaped as a rounded rectangular cube. The first MOV has a first side and a second side, each of which has the same surface area. The first metal terminal is connected to a first side of the MOV. The circuit protection device also has a second MOV in the shape of a second rounded rectangular cuboid. The second MOV has a third side and a fourth side, each side having the same surface area as the first side and the second side. The circuit protection device is further characterized by a second metal terminal connected between the second side and the third side, and a third metal terminal connected to the fourth side.

According to another exemplary embodiment of the circuit protection device of the present invention, may include a first metal terminal and a first MOV, wherein the first metal terminal is fixedly attached to the first MOV. The circuit protection device is further characterized by a second metal terminal and a second MOV, wherein the second metal terminal is fixedly attached to the second MOV. In addition, the circuit protection device further includes a third metal terminal and a third MOV, and the third metal terminal is fixedly attached to the third MOV. The second metal terminal is sandwiched between the second MOV and the third MOV.

An exemplary embodiment of a circuit protection device according to the present invention may include a first MOV, a second MOV and a third MOV, each MOV being a rectangular cuboid of the same size. The circuit protection device is further characterized by a first metal terminal, a second metal terminal, a third metal terminal and a fourth metal terminal, each terminal having a rectangular portion attached to one MOV, and a first metal portion and a second metal portion, each metal portion also having a rectangular portion for attachment to the MOV. The circuit protection device also includes two insulators and a spring connecting the device to the printed circuit board.

Drawings

FIG. 1 is a schematic diagram of a circuit protection device according to an example embodiment;

FIG. 2 is a schematic diagram of a circuit protection device according to an example embodiment;

fig. 3A and 3B are perspective and exploded perspective views of a circuit protection device according to an exemplary embodiment;

FIG. 4 is a schematic diagram of a circuit protection device according to an example embodiment;

FIG. 5 is a schematic diagram of a circuit protection device according to an example embodiment;

fig. 6 is a photographic image of the difference in size between MOVs of the device of fig. 4 and 5 according to an exemplary embodiment;

7A-7C are perspective and exploded perspective views of a circuit protection device according to an exemplary embodiment;

FIG. 8 is a schematic diagram of a circuit protection device according to an example embodiment;

9A-9C are perspective and exploded perspective views of a circuit protection device according to an exemplary embodiment;

FIG. 10 is a photographic image of a circuit protection device according to an exemplary embodiment; and

fig. 11 is a schematic diagram of a circuit protection device according to an example embodiment.

Detailed Description

According to embodiments described herein, a circuit protection device is disclosed to implement for an L/N/G circuit and an L₁/N/G/L₂Three modes of protection of the circuit. The MOVs used in conventional circuit protection devices are rearranged into a stackStacked and in some conditions reduced in number so that MOVs are shared between different modes. These MOVs are also made using high surge performance disks/powders to achieve smaller disk sizes without affecting MOV performance. Thinner disks replace a high rate of MOVs with thicker disks, thereby reducing the size and cost of the product. The utility model discloses a circuit protection device: 1) implementing L with two disks₁/L₂Protecting in three modes of/G; 2) three thin high surge performance disks are used for realizing three modes of protection; 3) three thin high surge performance disks are used to increase symmetric thermal protection. The circuit protection device may be a stand-alone device or may be a surface mount device suitable for attachment to a printed circuit board.

The circuit may have different power configurations, referred to as single phase and three phase. Single phase power supplies are two-wire Alternating Current (AC) power circuits. The three-phase power supply is a three-wire system AC power circuit with each phase of AC signal 120 electrical degrees apart. Single-phase circuits may employ different power configurations, such as phase, neutral, and ground (L/N/G), or may have a dual-line, phase 1 (L)₁) Phase line 2 (L)₂) And zero or ground (N/G), or (L)₁/N/G/L₂) Or may have a dual line, L₁And L₂And a ground line (L)₁/L₂and/G). Three-mode protection refers to surge protection between three modes of the circuit. Thus, the L/N/G power supply is configured with three modes: L-N, L-G, and N-G.

Current electronic/industrial applications use electronic components that are smaller in size relative to conventional components while providing higher performance than conventional components. As a result, the size of a given product or device used in these applications becomes more critical. Conventional L/N/G three mode surge protection devices, such as the 277V system described below, require at least three 320V MOV devices, which impacts some applications in terms of cost and space usage.

Fig. 1 is a schematic diagram of a circuit protection device 100 according to an example embodiment. The circuit protection device 100 includes connection lines 108, 110, 112. The connection line 108 may be a first connection line (L)₁) The connecting wire 110 may be a combined neutral/ground wireThe line (N/G)110, and the third connection line 112 may be a second connection line (L)₂). According to an exemplary embodiment, the connection lines 108, 110, and 112 are used to connect the protection device 100 between a power source (not shown) and a protected device or circuit (not shown).

A stack of Metal Oxide Varistors (MOVs) 102, 104 and 106 is arranged in electrical connection with connection lines 108, 110 and 112. The circuit protection device 100 may also include one or more hot melts or thermal links (not shown), such as may be formed from cold solder tabs. During normal operation of the circuit protection device 100 (i.e., in the absence of an overvoltage condition), the stack of MOVs 102, 104 and 106 generates sufficient heat to melt the hot melt or melts. However, since each MOV 102, 104 and 106 is a voltage sensitive device, the voltage applied across the MOV will heat up when it exceeds the rated voltage of the MOV, and the occurrence of an over-voltage condition will cause the stack of MOVs 102, 104 and 106 to heat up. When an overvoltage condition occurs, the heat radiated by the stack of MOVs 102, 104 and 106 is sufficient to cause one or more of the hot melts to melt, thereby creating an open circuit that prevents a device or circuit connected to circuit protection device 100 from being damaged by the overvoltage condition.

By way of background, each of the MOVs 102, 104 and 106 may be composed primarily of zinc oxide particles (which are sintered together to form circular or square disks) where the zinc oxide particles (as a solid) are a highly conductive material and the grain boundaries formed by the other oxides are highly resistive. Only at the point where the zinc oxide particles meet, sintering produces a "microvaristor" which behaves as a symmetric zener diode. The electrical characteristics of a metal oxide varistor are produced by a plurality of microvaristors connected in series or in parallel within the device. The sintered body of the MOV also explains its high electrical loading capacity, which allows high absorption of energy, and therefore extremely high surge current handling capacity.

In the conventional circuit protection device 100 of fig. 1, MOV 102 and MOV 104 are connected in series at the first connection line L ₁108 and a second connecting line L ₂112 with a neutral/ground wire 110 therebetween. The MOV 106 is arranged in parallel with the two MOVs 102 and 104 and is connected to the first connection line L ₁108 and a second connecting line L ₂112. MOV 102 and MOV 104 are each rated at 150V and MOV 106 is rated at 275V.

Fig. 2 is a schematic diagram of a circuit protection device 200 according to an example embodiment, the circuit protection device 200 being suitable for replacing the conventional circuit protection device 100 of fig. 1. The circuit protection device 200 provides a circuit protection device for a conventional L₁/N/G/L₂A novel alternative to three-mode surge protection. The circuit protection device 200 has two 150V MOVs, while the conventional circuit protection device 100 has three MOVs, two 150V MOVs and one 275V MOV. Thus, in some embodiments, the circuit protection device 200 is both less expensive and takes up less space than the circuit protection device 100.

The circuit protection device 200 includes connection lines 208, 210, and 212. The connection line 208 may be a first connection line L₁The connection line 210 may be an N/G combination line, and the connection line 212 may be a second connection line L₂. According to an exemplary embodiment, the connection lines 208, 210, and 212 are used to connect the protection device 200 between a power source (not shown) and a device or circuit to be protected (not shown).

A stack of Metal Oxide Varistors (MOVs) 202 and 204 are arranged in electrical connection with connection lines 208, 210 and 212. The circuit protection device 200 may also include one or more hot melts (not shown). During normal operation of the circuit protection device 200, the stack of MOVs 202, 204 does not generate sufficient heat to melt the hot melt or melts. However, the occurrence of an overvoltage condition exceeding the rated voltage of the MOV (150V) can cause the stack of MOVs 202, 204 to heat up and cause one or more hot melts to melt, thereby forming an open circuit. Thus, the circuit protection device 200 may protect devices or circuits connected thereto from an overvoltage condition.

In some embodiments, the novel circuit protection device 200 is more advantageous than the conventional circuit protection device 100 by sharing one MOV between any two modes. MOVs 202 and 204 are arranged in series with each other, wherein MOV 202 is arranged at a first connection line L ₁208 and a combined neutral/ground line N/G210, the MOV 204 being arranged between the N/G line 210 and the second connecting line L ₂212. Rated voltage of both MOVs 202, 204At 150V, MOV 102, MOV 104, MOV 106 of circuit protection device 100 are rated at 150V, 275V, respectively. Thus, circuit protection device 200 implements L using two MOV disks₁/L₂the/G three-mode surge protection has better surge performance than the circuit protection device 100 in the figure 1.

Fig. 3A and 3B are perspective and exploded perspective views, respectively, of a novel circuit protection device 300 according to an exemplary embodiment. The circuit protection device 300 is an embodiment of the circuit protection device 200 (fig. 2). The circuit protection device 300 has two MOVs 302, 304 and three metal terminals 308, 310, 312, wherein the metal terminals provide connection lines for connecting the circuit protection device between a power source and a device or circuit to be protected. In an exemplary embodiment, the MOVs 302, 304 are based on high surge performance disks/powders, enabling smaller sized disks with comparable performance to larger sized conventional MOVs.

In an exemplary embodiment, the MOVs 302, 304 are shaped as rounded rectangular cubes having two equally sized longer sides and four shorter edge sides. In one embodiment, MOV 302 is substantially similar in its dimensions (shape and size) to MOV 304. Therefore, the longer side has a larger surface area than the edge side. Metal terminals 308, 310 and 312 are shaped to be disposed along one of the two longer sides of the MOV and fixedly attached. Since the MOVs 302, 304 are rectangular cubes, each metal terminal again includes a rectangular portion (which is fixedly attached along the longer side surface of the MOV) and legs that extend beyond the edges of the MOV. In an exemplary embodiment, the metal terminal is disposed along the longer side of the MOV and fixedly attached such that the rectangular portion of the metal terminal is equidistant from the edges of the MOV and covers some portion of the longer side. Each metal terminal consists of four sides arranged in a rectangular shape like a rectangular portion, with one side longer than the other three sides, the longer side thereby forming a leg extending beyond the surface of the MOV. Although each metal terminal may be described as having four sides, or alternatively a rectangular portion and a leg portion, each metal terminal is preferably stamped from a single piece of metal into the desired shape.

As can be seen in particular in the exploded view of fig. 3B, the metal terminals 308, 310 and 312 may be considered "P-shaped" or "Q-shaped" because they resemble lower case versions of the letters P and Q. In the exemplary embodiment, terminals 308 and 312 are in a q-shaped arrangement and terminal 510 is in a p-shaped arrangement. In an exemplary embodiment, the metal terminals 308, 310, and 312 are arranged to alternate between p-shapes and q-shapes, thereby maximizing the distance between the leg portions of each metal terminal in the circuit protection device 300. In another embodiment, metal terminals 308 and 312 are p-shaped and metal terminal 310 is q-shaped.

The leg portion of each metal terminal enables the circuit protection device 300 to be connected between a power source and a device or circuit to be protected. In an exemplary embodiment, the metal terminals 308, 310, and 312 form solid rectangular (or other shaped) terminals with legs that extend beyond the edge surfaces of the MOV (e.g., the "hole" of "p" or "q" is filled). In an exemplary embodiment, the edge of the metal terminal does not extend all the way to the edge of the longer side of the MOV, but rather a distance d, i.e., a "free area," is maintained between the metal terminal and the edge of the MOV (fig. 3A).

The MOVs 302, 304 may take any number of different shapes. Where MOVs 302, 304 assume shapes other than the rounded rectangular cubes of fig. 3A and 3B, metal terminals 308, 310 and 312 may likewise have different shapes. In an exemplary embodiment, the metal terminals are shaped according to the shape of the MOV, so the metal terminals can be fixed on both long sides of the MOV (not along the edges), covering a portion of the long sides, and at equal distances from the edge surfaces of the MOV.

The MOV and terminal arrangement allows for a dual structure of circuit protection device 300. A first metal terminal 308 is attached to one of the two longer sides of MOV 302. A second metal terminal 310 is attached to the other of the two longer sides of MOV 302 and also to one of the two longer sides of MOV 304, such that the metal terminal 310 is sandwiched between the two MOVs 302, 304. The third terminal 312 is attached to the second of the two longer sides of the MOV 304, i.e., the side opposite the metal terminal 310. The two metal terminals 308 and 312 are arranged in one direction (q-shape) and the middle metal terminal 310 is arranged in the other direction (p-shape).

In some embodiments, the circuit protection device 300 has advantages in terms of cost and space consumption savings. By stacking two MOVs together, the circuit protection device 300 takes up less space than a conventional MOV. The two 150V rated MOVs 202 and 204 of the equivalent circuit of fig. 2 may be less expensive than the three 150V, 150V and 275V rated MOVs of fig. 1, respectively. Further, two MOVs may occupy less space than three MOVs. However, in some embodiments, the particular arrangement of the MOVs, such as the stacked arrangement in fig. 3, provides additional space savings. Further, in the exemplary embodiment, the MOVs 302, 304 are disc/powder based high surge performance, enabling smaller sized discs to have performance comparable to larger sized conventional MOVs. Thus, circuit protection device 300 uses two MOV pads to implement L₁/L₂And G three-mode surge protection.

Fig. 4 is a schematic diagram of a circuit protection device 400 according to an example embodiment. The circuit protection device 400 includes connection lines 408, 410, and 412. Connecting wire 408 may be phase (L), connecting wire 410 may be neutral (N), and connecting wire 412 may be ground (G). According to an exemplary embodiment, the connection lines 408, 410, and 412 are used to connect the protection device 100 between a power source (not shown) and a device or circuit to be protected (not shown). Although the circuit protection devices 100, 200, 300 provide L₁/L₂The surge protection of/G, but the circuit protection device 400 provides surge protection of L/N/G, which is just a difference in power supply configuration.

Metal Oxide Varistors (MOVs) 402, 404 and 406 are provided in electrical connection with connection lines 408, 410 and 412. Circuit protection device 400 may also include one or more hot melts (not shown). The stack voltage ratings of MOVs 402, 404 and 406 are all 320V. When the voltage applied across the MOV exceeds the rated voltage of the MOV, the occurrence of an overvoltage condition causes the stack of MOVs 402, 404 and 406 to heat up, causing one or more of the hot melts to melt, thereby creating an open circuit that prevents the device or circuit connected thereto from being damaged by the overvoltage condition.

In the conventional circuit protection device 400 of fig. 4, MOVs 402 and 404 are connected in series between a connection 408 and a ground 412 with a neutral wire 410 therebetween. The MOV 406 is disposed in parallel with the two MOVs 402 and 404 and is also connected between the connection 408 and ground 412. The three MOVs 402, 404, 406 are 320V MOVs and the circuit protection device 400 provides 277V surge protection in this configuration. For some applications, an MOV with three 320V is both expensive and takes up more space than is available.

Fig. 5 is a schematic diagram of a circuit protection device 500 according to an example embodiment. Circuit protection device 500 provides a novel alternative to conventional L/N/G three-mode surge protection, such as conventional circuit protection device 400 in fig. 4. In some embodiments, circuit protection device 500 is both less expensive and takes up less space than circuit protection device 400.

The circuit protection device 500 includes connection lines 508, 510, and 512. Connecting wire 508 may be phase (L), connecting wire 510 may be neutral (N), and connecting wire 512 may be ground (G). According to an exemplary embodiment, the connection lines 508, 510, and 512 are used to connect the protection device 500 between a power source (not shown) and a device or circuit to be protected (not shown).

A stack of Metal Oxide Varistors (MOVs) 502, 504 and 506 are provided in electrical connection with connection lines 508, 510 and 512. The circuit protection device 500 may also include one or more hot melts (not shown). During normal operation of the circuit protection device 500, the stack of MOVs 502, 504 and 506 does not generate sufficient heat to melt the hot melt or melts. However, upon an overvoltage condition that exceeds the rated voltage of the MOVs (each having a rated voltage of 175V), the stack of MOVs 502, 504 and 506 will heat up, causing one or more of the hot melts to melt, thereby forming an open circuit that prevents a device or circuit connected to circuit protection device 500 from being damaged by the overvoltage condition.

As with the circuit protection device 200 (fig. 2), the circuit protection device 500 shares MOVs between modes. Thus in FIG. 5, L-N and L-G share MOV 502, L-N and N-G share MOV 504, and L-G and N-G share MOV 506. The three MOVs are stacked together. In contrast, the conventional circuit 400 in fig. 4 does not share MOVs between modes. Accordingly, in some embodiments, the novel circuit protection device 500 is more advantageous than the conventional circuit protection device 400. MOVs 502 and 504 are disposed in series with one another between phase 508 and neutral 510. MOV 506 is disposed between the two MOVs 502 and 504 on one end and connected to ground 512 on the other end. Each MOV 502, 504 and 506 is rated at 175V, while MOVs 402, 404 and 406 (fig. 4) are each rated at 320V. However, circuit protection device 500 also provides 277V protection and the same anti-surge capability, although device 500 is smaller in size than circuit protection device 400.

The novel circuit protection device 500 is designed to share one MOV between any two modes. In an exemplary embodiment, this design significantly reduces product size and cost. Furthermore, the MOV-forming discs are based on high surge performance discs/powders which allow the MOV to be smaller in size while maintaining the higher performance of larger MOVs.

Table 1 shows MOV stack dimensions (in mm) between the MOVs of fig. 4 and 5, according to some embodiments. The table shows that the MOV of device 500 is thinner than the MOV of device 400.

TABLE 1 MOV Stack size

Fig. 6 is a photographic image of the difference in size between the MOVs of devices 400 and 500 according to an exemplary embodiment. Image 602 shows the stack of MOVs of device 400 and image 604 shows the stack of MOVs of device 500. The stack 602 of the MOV of device 400 is thicker than the stack 604 of the MOV of device 500. The illustration of fig. 6 and table 1 shows that, in addition to the sharing mode, for some applications, a smaller size MOV stack makes device 500 preferable to device 400.

Fig. 7A-7C are two perspective views and an exploded perspective view, respectively, of the novel circuit protection device 700 according to an exemplary embodiment. The circuit protection device 700 is an embodiment of the circuit protection device 500 (fig. 5). The circuit protection device 700 thus uses three thin high surge performance MOV disks to achieve the three modes of L/N/G surge protection.

Circuit protection device 700 is comprised of three MOVs 702, 704 and 706, three metal terminals 708, 710 and 712, two metal portions 714, 716 and an insulator 718. According to an exemplary embodiment, metal terminals 708, 710, and 712 are used to connect the protection device 700 between a power source (not shown) and a device or circuit to be protected (not shown).

The exploded perspective view of fig. 7C shows three MOVs 702, 704 and 706. In an exemplary embodiment, MOVs 702, 704 and 706 are shaped as rounded rectangular cubes having two equal sized longer sides and four shorter edge sides. In one embodiment, MOV 702 is substantially similar in its dimensions (shape and size) to MOV 704 and MOV 706. Therefore, the longer side has a larger surface area than the edge side. Metal terminals 708, 710 and 712 are shaped to be disposed along one of the two longer sides of the MOV and fixedly attached. Since the MOVs 702, 704, 706 are rectangular cubes, each metal terminal again includes a rectangular portion fixedly attached along the surface of the longer side of the MOV, and a leg that extends beyond the edge of the respective MOV. Metal terminals 708 are disposed on the longer side of MOV 702. A metal terminal 712 is provided on the longer side of MOV 706. Metal terminals 708 and 712 are q-shaped, as are metal terminals 308 and 312 in circuit protection device 300 (fig. 3B). A third metal terminal 710 is sandwiched between the longer side of MOV 704 and insulator 718. Although the extended leg of the p-shaped metal terminal 710 is not visible in fig. 7C, the third metal terminal 710 is p-shaped, the leg of which is apparent in fig. 7A.

Furthermore, in the exemplary embodiment, circuit protection device 700 includes two additional metal portions 714 and 716 that are designed to mate with each other over the top of MOV 704. Metal portions 714 and 716 are rounded rectangular in shape and are adapted to be disposed on the long sides of the MOV. In addition to the rounded rectangular shape, metal portions 714 and 716 each have a leg disposed orthogonally with respect to the rectangular portion, wherein the legs are designed to be located above the top of the intermediate MOV 704. Metal portion 714 includes leg portion 720 and metal portion 716 includes leg portion 722. As shown in fig. 7B, these legs are paired with each other. In an exemplary embodiment, the legs 720 and 722 are welded together during the manufacture of the circuit protection device 700.

As with the metal terminals 708, 710, 712, the metal portions 714, 716 conform to the shape of the MOV to which they are attached. In an exemplary embodiment, the metal portions 714, 716 are each disposed along the longer side of the MOV such that the metal portions are each equidistant from the edge of the respective MOV to which they are attached. Further, metal portions 714, 716 cover portions of the longer sides. In an exemplary embodiment, as shown in fig. 7A-7C, the metal terminals 708, 710, 712 and metal portions 714, 716 include rectangular cutouts (e.g., "holes" for "p" or "q"). In another embodiment, the metal terminals 708, 710, 712 and metal portions 714, 716 do not include rectangular shaped cutouts, but rather the rectangular portions are solid rounded rectangular pieces of metal (e.g., "holes" in "p" or "q" are filled).

In an exemplary embodiment, the insulator 718 protects the circuit protection device 700 from high temperatures. In one embodiment, insulator 718 is made of, for example, Al₂O₃Is made of the ceramic of (1). In another embodiment, insulator 718 is made of a high temperature resin. In another embodiment, the insulator 718 is made of p-phenylenediamine (PPD). In another embodiment, insulator 718 is made of a Liquid Crystal Polymer (LCP).

Thus, circuit protection device 700 is configured as a stack of MOV devices. MOV 702 is sandwiched between metal terminal 708 on one side and metal portion 714 on the other side. MOV 704 is disposed between the other side of metal portion 714 and metal terminal 710, with leg 720 disposed above MOV 704. An insulator 718 is disposed between the metal terminal 710 and the second metal portion 716. A second metal portion 716 is attached to MOV 706, with MOV 706 sandwiched between second metal portion 716 and metal terminal 712. When joined together, leg 720 of metal portion 714 is paired with leg 722 of metal portion 716 and this pairing occurs over one shorter side of MOV 704. In an exemplary embodiment, the three MOVs 702, 704, 706 are thin high surge performance disks to enable three modes of protection for the circuit or device to which the circuit protection device is connected.

In both circuit protection device 300 (fig. 3A and 3B) and circuit protection device 700 (fig. 7A-7C), the thinner disk with the lower voltage rating replaces the thicker disk with the higher voltage rating. For example, the circuit protection device 300 is based on the circuit protection device 200, and the circuit protection device 200 corresponds to the circuit protection device 100 with respect to the surge protection function. Circuit protection device 100 employs three MOVs, two rated at 150V and one rated at 275V, while circuit protection device 200 employs two MOVs of 150V. Thus, the product size and cost of the circuit protection device 300 is reduced relative to the product size and cost of the circuit protection device 100. Also, the circuit protection device 600 is based on the circuit protection device 500, and the circuit protection device 500 corresponds to the circuit protection device 400 with respect to the surge prevention function. Circuit protection device 400 employs three MOVs, each rated at 320V, while circuit protection device 500 employs three MOVs of 175V. Thus, at least the cost of circuit protection device 300 may be reduced relative to the cost of circuit protection device 400.

Fig. 8 is a schematic diagram of a circuit protection device 800 according to an example embodiment. The device 800 is similar to the circuit protection device 500 except that the MOV 806 is rearranged relative to the MOV 506. Circuit protection device 800 has three 175V MOVs 802, 804, 806 and connections 808(L), 810(N), 812 (G). In addition, the circuit protection device 800 includes two hot melts 814 and 816. A first hot melt 814 is disposed between MOV 802 and MOV 806; the second hot melt is disposed between MOV 806 and MOV 804. The occurrence of an over-voltage condition will heat up the stack of MOVs 802, 804 and 806. When an overvoltage condition occurs, the heat radiated by the stack of MOVs 802, 804 and 806 is sufficient to cause one or more of the hot melts 814, 816 to melt, thereby forming an open circuit that protects the device or circuit connected to circuit protection device 800 from the overvoltage condition.

In the exemplary embodiment, circuit protection device 800 employs three thin high surge performance disks to achieve symmetric thermal protection. This enables, for example, the L connection 808 and the N connection 810 to be reversed. The circuit protection device 800 can be easily integrated to provide thermal protection, whether as a stand-alone device (see fig. 10) or as a surface mount device connected to a printed circuit board (see fig. 9A and 9B below).

Fig. 9A-9C are two perspective views and an exploded perspective view, respectively, of the novel circuit protection device 900 according to an exemplary embodiment. Circuit protection device 900 is an embodiment of circuit protection device 800 (fig. 8). In an exemplary embodiment, circuit protection device 900 employs three thin high surge performance disks to achieve symmetric thermal protection. In one embodiment, this enables the L and N connections to be reversed. Further, in contrast to the previous examples disclosed herein, the circuit protection device 900 employs surface mount technology to attach the device to a printed circuit board.

As shown in the exploded perspective view of fig. 9C, the circuit protection device 900 has three MOVs 902, 904, 906, as well as four metal terminals 908, 910, 912, 914, metal portions 916, 918, insulators 920, 922 and a spring 930. The metal terminals 908, 910, 912, 914 are composed of rounded rectangular portions (where one of the four sides of the rectangle is longer than the remaining sides) and leg portions orthogonal to the plane of the rectangular portions. For example, the metal terminal 908 includes a rounded rectangular portion 924, one of the four sides of which extends to form a q-shape, and a leg portion 926 disposed orthogonally relative to the rectangular portion. The metal terminal 910 includes a rounded rectangular portion 928 with a leg 930 extending from one side of the rectangle, the rounded rectangular portion and the leg being planar (in the same plane) with each other, and an orthogonally disposed leg 932 attached to the extended leg. Metal terminal 912 includes a rounded rectangular portion 934 with leg 936 in the same plane as the rectangular portion and extending from one side of the rectangle, and leg 938 disposed orthogonally to leg 936 and rectangular portion 934. The metal terminal 914 includes a rounded rectangular portion 940 with a leg portion 920 in the same plane as the rectangular portion and extending from one side of the rectangle, and a leg portion 944 disposed orthogonally to the leg portion 942 and the rectangular portion 940.

Further, in the exemplary embodiment, the orthogonally disposed leg 926 of the first metal terminal 908 and the orthogonally disposed leg 932 of the second metal terminal 910 are positioned to be disposed on one side of the three MOVs 902, 904, 906, while the orthogonally disposed leg 938 of the third metal terminal 912 and the orthogonally disposed leg 944 of the fourth metal terminal 914 are positioned to be disposed on an opposite side of the three MOVs 902, 904, 906. In an exemplary embodiment, the rounded rectangular portion of each metal terminal is substantially similar to the rounded rectangular portions of the other metal terminals.

The metal portions 916, 918 each consist of a rounded rectangular portion and a leg portion that extends in the same plane as the rectangular portion. The metal portion 916 includes a rounded rectangular portion 952 with legs 954 extending out from one side of the rectangle in the same plane as the rectangular portion. Metal portion 918 includes a rounded rectangular portion 956 with leg portions 958 in the same plane as the rectangular portion and extending from one side of the rectangle. In an exemplary embodiment, the rounded rectangular portion of each metal portion is substantially similar to the other metal portions and the rounded rectangular portions of the metal terminals.

In an exemplary embodiment, the insulators 920, 922 protect the circuit protection device 900 from high temperatures. In one embodiment, insulators 920, 922 are made of, for example, Al₂O₃Is made of the ceramic of (1). In another embodiment, the insulators 920, 922 are made of a high temperature resin. In another embodiment, the insulators 920, 922 are made of p-phenylenediamine (PPD). In another embodiment, the insulators 920, 922 are made of Liquid Crystal Polymer (LCP).

Furthermore, in the exemplary embodiment, circuit protection device 900 includes a spring 950. The spring 950 is comprised of two tines 946, 948 enabling the device 900 to be attached to a Printed Circuit Board (PCB)962, such as FR 4. PCB 962 includes pads 960 for receiving metal terminals 908, 910, 912, 914 and springs 950. By connecting the metal terminals 908, 910, 912, 914 to pads 960 on the PCB 962, an electrical connection is established between the power supply, the circuit protection device 900 and the device or circuit to be protected. In some embodiments, tines 946, 948 of spring 950 sense the temperature rise of the MOV during an abnormal condition and then spring up and break the circuit. In an exemplary embodiment, the spring 950 is made of beryllium copper, tin, copper, or other highly resilient material.

Referring back to fig. 8, it can be easily seen that the circuit protection device 800 is symmetrical in structure/design. The L connection 808 and the N connection 810 may be reversed. Although not obvious, the circuit protection device 900 also provides a symmetrical structure/design that enables the device to be connected such that the L-connection and N-connection are reversed. The circuit protection device 900 is easily integrated to provide thermal protection for various applications.

Fig. 10 is a schematic diagram of a circuit protection device 1000 according to an example embodiment. As described above, the circuit protection device 1000 includes a thin MOV pad in a body and terminals 1002, 1004, 1006. In some embodiments, MOV 1000 is a compact structure that provides integrated three-mode protection.

Fig. 11 is a depiction of a circuit protection device 1100, which circuit protection device 1100 may be added to a PCB, for example, using surface mount technology. As illustrated and described herein, circuit protection devices 1000 (fig. 10) and 1100 (fig. 11) demonstrate that there may be different packaging/profiles for circuit protection devices with stacked MOVs.

In exemplary embodiments, the circuit protection devices described herein are housed in a high temperature resin, such as polyphenylene sulfide (PPS), Liquid Crystal Polymer (LCP), polybutylene terephthalate (PBT), bakelite (bakelite), and the like. The metal terminals and metal portions are made using a metallized layer of ceramic, using silver, copper, aluminum, or a combination of these materials.

As used herein, an element or step recited in the singular and proceeded with the word "a" or "an" should be understood as not excluding plural elements or steps, unless such exclusion is explicitly recited. Furthermore, references to "one embodiment" of the present disclosure are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features.

Although the present disclosure has been described with reference to certain embodiments, many modifications, alterations, and changes to the described embodiments are possible without departing from the scope and spirit of the present disclosure, as defined in the appended claims. Accordingly, it is intended that the disclosure not be limited to the described embodiments, but that it have the full scope defined by the language of the following claims, and equivalents thereof.

Claims (20)

1. A circuit protection device, comprising:

a first metal oxide varistor comprising a first rounded rectangular cube having:

a first side having a first surface area;

a second side having the first surface area;

a first metal terminal coupled to the first side;

a second metal oxide varistor comprising a second rounded rectangular cube having:

a third side having the first surface area; and

a fourth side having the first surface area;

a second metal terminal coupled between the second side and the third side; and

a third metal terminal coupled to the fourth side.

2. The circuit protection device of claim 1, wherein the first metal terminal further comprises:

a rectangular portion fixedly attached to the first side; and

a leg extending beyond an edge of the first metal oxide varistor;

wherein the rectangular portion and the leg portion form a q-shape.

3. The circuit protection device of claim 2, wherein the first metal terminal is arranged on a first side of the first metal oxide varistor such that the rectangular portion is equidistant from an edge of the first metal oxide varistor.

4. The circuit protection device of claim 1, wherein the second metal terminal further comprises:

a rectangular portion fixedly attached between the second side and the third side; and

a leg extending beyond an edge of the first metal oxide varistor and beyond a second edge of the second metal oxide varistor;

wherein the rectangular portion and the leg portion form a p-shape.

5. The circuit protection device of claim 4, wherein the second metal terminal is arranged on a second side of the first metal oxide varistor and a third side of the second metal oxide varistor such that the rectangular portion is equidistant from an edge of the first metal oxide varistor and a second edge of the second metal oxide varistor.

6. The circuit protection device of claim 1, wherein the third metal terminal further comprises:

a rectangular portion fixedly attached to the fourth side;

a leg extending beyond an edge of the first metal oxide varistor and a second edge of the second metal oxide varistor;

wherein the rectangular portion and the leg portion form a q-shape.

7. The circuit protection device of claim 1 wherein said first metal terminal establishes a first phase connection, said second metal terminal establishes a combined neutral/ground connection, and said third metal terminal establishes a second phase connection, wherein said first phase connection, said combined neutral/ground connection, and said second phase connection enable said circuit protection device to be coupled between a power source and a device or circuit to be protected.

8. A circuit protection device, comprising:

a first metal terminal;

a first metal oxide varistor, the first metal terminal fixedly attached to the first metal oxide varistor;

a second metal terminal;

a second metal oxide varistor to which the second metal terminal is fixedly attached;

a third metal terminal; and

a third metal oxide varistor, the third metal terminal fixedly attached to the third metal oxide varistor;

wherein the second metal terminal is disposed between the second metal oxide varistor and the third metal oxide varistor.

9. The circuit protection device of claim 8, wherein said first and third metal terminals are q-shaped and said second metal terminal is p-shaped.

10. The circuit protection device of claim 8, further comprising:

a first metal part fixedly attached between the first metal oxide varistor and the second metal oxide varistor;

an insulator; and

a second metal part fixedly attached between the third metal oxide varistor and the insulator.

11. The circuit protection device of claim 10, wherein the first metal portion comprises:

a first rectangular portion; and

a first leg, wherein the first leg is orthogonally disposed relative to the first rectangular portion.

12. The circuit protection device of claim 11, wherein the second metal portion comprises:

a second rectangular portion; and

a second leg, wherein the second leg is orthogonally disposed relative to the second rectangular portion;

wherein the first leg is paired with the second leg above a top edge of the second metal oxide varistor.

13. A circuit protection device, comprising:

a first metal oxide varistor, a second metal oxide varistor and a third metal oxide varistor, wherein each metal oxide varistor comprises a rectangular cuboid having substantially similar dimensions;

a first metal terminal, a second metal terminal, a third metal terminal and a fourth metal terminal, each metal terminal comprising a rectangular portion disposed against one metal oxide varistor;

a first metal part and a second metal part, each metal part comprising a rectangular portion arranged against one metal oxide varistor;

a first insulator and a second insulator; and

a spring for coupling the circuit protection device to a printed circuit board.

14. The circuit protection device of claim 13, wherein:

the first metal terminal is affixed to a first side of a first metal oxide varistor and the first metal portion is affixed to a second side of the first metal oxide varistor;

the second metal portion is affixed to a first side of a second metal oxide varistor and the second metal terminal is affixed to a second side of the second metal oxide varistor; and

the third metal terminal is affixed to a first side of a third metal oxide varistor and the fourth metal terminal is affixed to a second side of the third metal oxide varistor.

15. The circuit protection device of claim 14, wherein said first insulator is disposed between said first metal portion and said second metal portion.

16. The circuit protection device of claim 15, wherein said second insulator is disposed between said second metal terminal and said third metal terminal.

17. The circuit protection device of claim 13, wherein the first metal terminal comprises:

a rectangular portion to be attached to a side of the first metal oxide varistor, wherein a side of the rectangular portion extends to form a q-shape; and

a leg disposed orthogonally with respect to the rectangular portion, the leg being coupled to a pad of a printed circuit board.

18. The circuit protection device of claim 13, wherein the second metal terminal comprises:

a rectangular portion to be attached to one side of the second metal oxide varistor;

a leg extending from one side of the rectangular portion, wherein the rectangular portion and the leg are planar to each other; and

a second leg attached to the leg, wherein the second leg is orthogonally disposed relative to the rectangular portion;

wherein the second leg is coupled to a pad of a printed circuit board.

19. The circuit protection device of claim 13, wherein the third metal terminal comprises:

a rectangular portion to be attached to one side of the third metal oxide varistor;

a leg extending from one side of the rectangular portion, wherein the rectangular portion and the leg are planar to each other; and

a second leg attached to the leg, wherein the second leg is orthogonally disposed relative to the rectangular portion;

wherein the second leg is coupled to a pad of a printed circuit board.

20. The circuit protection device of claim 13, wherein the fourth metal terminal comprises:

a rectangular portion to be attached to a second side of the third metal oxide varistor;

a leg extending from one side of the rectangular portion, wherein the rectangular portion and the leg are planar to each other; and

a second leg attached to the leg, wherein the second leg is orthogonally disposed relative to the rectangular portion;

wherein the second leg is coupled to a pad of a printed circuit board.

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