Arc-quenching fuse filler for current-limiting fuses

Abstract

1. A method for producing an arc-quenching fuse filler, comprising the steps of: providing a conventional fuse filler material; mixing the conventional fuse filler material with a binder; mixing the conventional fuse filler material and the binder with an arc-quenching accelerator; and curing the binder, whereby granules of the arc-quenching accelerator are bonded to granules of the conventional fuse filler material.

Description

[Technical field]

[0001] The present disclosure relates generally to the field of circuit protection devices. More specifically, the present disclosure relates to an arc-quenching fuse filler that includes a binder to enable a substantially uniform composition. [Background technology]

[0002] Fuses are commonly used as circuit protection devices and are typically installed between a power source and a component to be protected in an electrical circuit. A conventional fuse includes a fusible element disposed within a hollow, electrically insulating fuse body. Upon the occurrence of a fault condition, such as an overcurrent condition, the fusible element melts or otherwise separates to interrupt the flow of electrical current through the fuse.

[0003] When a fusible element of a fuse separates as a result of an overcurrent condition, it may be possible for an electrical arc to propagate between the separated portions of the fusible element (e.g., through residual vaporized particles between the separated portions of the fusible element). If not extinguished, the electrical arc may allow significant subsequent current to flow from the power source to the protected components in the circuit, resulting in damage to the protected components despite the fusible element being physically open. Additionally, the electrical arc may rapidly heat the surrounding air and environmental particles, which may cause a small explosion within the fuse. In some cases, the explosion may burn and / or rupture the fuse body, potentially damaging surrounding components. The likelihood of rupture is generally proportional to the severity of the overcurrent condition. The maximum current that a chip fuse can withstand without rupturing is referred to as the "breaking capacity" of the fuse. It is generally desirable to maximize the breaking capacity of a fuse without significantly enlarging the size or form factor of the fuse. This is especially true in modern electric vehicle applications where space is limited and voltage requirements are very high.

[0004] To minimize the harmful effects of electric arcs, fuses are often filled with a so-called "fuse filler" that surrounds the fusible element. Typically, the material used as a fuse filler is sand. Sand acts as a heat absorber because its phase changes from solid to liquid when exposed to the heat generated by an electric arc. Thus, the sand cools and ultimately extinguishes the electric arc by rapidly extracting heat from it. While sand and other traditional fuse filler materials (e.g., calcium carbonate, steatite, etc.) are effective in providing arc extinction in some applications, they are generally insufficient to provide fuses with the large interrupting capacity and rapid extinguishing times required for modern high voltage applications (e.g., electric vehicles).

[0005] It is with respect to these and other considerations that the present improvements may be useful. Summary of the Invention

[0006] This Summary is provided to introduce certain concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to aid in determining the scope of the claimed subject matter.

[0007] A method for producing an arc-quenching fuse filler according to the present disclosure may include the steps of providing a conventional fuse filler material, mixing the conventional fuse filler material with a binder, mixing the conventional fuse filler material and the binder with an arc-quenching enhancer, and curing the binder, whereby granules of the arc-quenching enhancer are bonded to the granules of the conventional fuse filler material.

[0008] An arc-quenching fuse filler according to the present disclosure may include a conventional fuse filler material, an arc-quenching enhancer, and a binder that binds the granules of the arc-quenching enhancer to the granules of the conventional fuse filler material.

[0009] A fuse according to the present disclosure may include an electrically insulating tubular fuse body, electrically conductive first and second end caps disposed over opposite ends of the fuse body, a fusible element extending through the fuse body and connecting the first end cap to the second end cap, the fusible element having a central portion adapted to melt and separate upon an overcurrent condition in the fuse, and an arc-quenching fuse filler disposed within the fuse body and at least partially surrounding the central portion of the fusible element, where the arc-quenching fuse filler includes a conventional fuse filler material, an arc-quenching enhancer, and a binder that bonds granules of the arc-quenching enhancer to the granules of the conventional fuse filler material. [Brief description of the drawings]

[0010] [Figure 1A] 1A-1C illustrate a method of manufacturing an arc-quenching fuse filler according to an exemplary embodiment of the present disclosure. [Figure 1B] 1A-1C illustrate a method of manufacturing an arc-quenching fuse filler according to an exemplary embodiment of the present disclosure. [Figure 1C] 1A-1C illustrate a method of manufacturing an arc-quenching fuse filler according to an exemplary embodiment of the present disclosure. [Figure 1D] 1A-1C illustrate a method of manufacturing an arc-quenching fuse filler according to an exemplary embodiment of the present disclosure.

[0011] [Figure 2A] 1 is a cross-sectional side view of a fuse according to an exemplary embodiment of the present disclosure in normal operating conditions;

[0012] [Figure 2B] 2B is a cross-sectional side view of the fuse of FIG. 2A upon the occurrence of an overcurrent condition. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Exemplary embodiments of the arc-quenching fuse filler and method of making the same according to the present disclosure will now be described in more detail below with reference to the accompanying drawings. However, the fuse filler and method may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that the present disclosure will convey certain exemplary aspects of the arc-quenching fuse filler and method to those skilled in the art.

[0014] In one aspect, and as described in more detail below, the present disclosure is directed to an arc-quenching fuse filler composition formed of a conventional fuse filler material (e.g., sand) mixed with an arc-quenching promoter (e.g., melamine) to provide a fast and robust arc-quenching response in the fuse upon the occurrence of an overcurrent condition in the fuse. Because the granules of the conventional fuse filler material in the composition will generally have a size and density different from the size and density of the granules of the adhesion promoter in the composition, the two materials will tend to separate from each other when the composition is dispensed into the fuse or when the composition is exposed to vibration (a phenomenon called the "Brazil Nut Effect"), such as when the composition is outdoors (e.g., in fuses installed in electric vehicles). Such separation can be detrimental to the effectiveness of the composition. Thus, the present disclosure is further directed to a novel method of preparing an arc-quenching fuse filler, which includes coating the granules of the conventional fuse filler material with a binder prior to introducing the adhesion promoter. Thus, when the adhesion promoter is mixed into the conventional fuse filler material, the granules of the adhesion promoter will bond to the granules of the conventional fuse filler material. As will be explained in more detail below, this bond prevents the adhesion promoter from separating from the conventional fuse filler material while maintaining the flowability of the conventional fuse filler material.

[0015] 1A-1D show sequential steps of an exemplary method for forming an arc-quenching fuse filler according to the present disclosure, and are detailed close-up views showing individual granules and their constituent parts of the arc-quenching fuse filler, which are described further below.

[0016] In a first stage of the exemplary method illustrated in FIG. 1A, a quantity of conventional fuse filler material 10 (hereinafter "conventional filler 10") may be provided. As used herein, the term "conventional filler 10" shall be defined to mean one or more of silica, silica sand, calcium carbonate, calcium sulfate dihydrate, fuller's earth, or steatite, all of which are recognized by those skilled in the art as materials traditionally used as fuse fillers. The granules of conventional filler 10 may be substantially uniform in size and shape, or may vary in size and shape, as illustrated in FIG. 1A. The present disclosure is not limited in this respect. In a non-limiting example, the granules of conventional filler 10 may have a size (e.g., length or diameter) ranging from 150 um to 600 um.

[0017] In a further step of the exemplary method shown in FIG. 1B, a binder 12 may be mixed with the conventional filler 10. The binder 12 may be or may include a silicone-based binder, a carbon-based binder (e.g., polyvinyl alcohol, epoxy, cellulose, etc.), or an inorganic binder (e.g., calcium aluminate, alumina silicate, sodium silicate, etc.). The present disclosure is not limited in this respect. The binder 12 may be provided in a liquid or semi-liquid form. As shown in FIG. 1B, when mixed with the conventional filler 10, the binder 12 may coat the granules of the conventional filler 10 in a substantially uniform manner.

[0018] In a further step of the exemplary method shown in FIG. 1C, an arc extinction accelerant 14 may be mixed with the conventional filler 10 and binder 12. The arc extinction accelerant 14 may be or may include one or more of melamine, guanidine, guanine, hydantoin, allantoin, urea, melamine formaldehyde, melamine cyanurate polymer, boric acid, aluminum trihydrate, and derivatives and mixtures thereof, in powder or granular form. The granules of the arc extinction accelerant 14 may be substantially uniform in size and shape, or may vary in size and shape, as shown in FIG. 1C. The present disclosure is not limited in this respect. In a non-limiting example, the granules of the arc extinction accelerant 14 may have a size (e.g., length or diameter) ranging from 5 um to 60 um. Generally, the granules of the arc extinction accelerant 14 will be smaller than the granules of the conventional filler 10. For example, in various embodiments, the granules of the arc extinction accelerant 14 may be 0.3%-10% of the size of the granules of the conventional filler 10. The present disclosure is not limited in this respect. When the arc extinction accelerant 14 is mixed with the conventional filler 10 and the binder 12, the granules of the arc extinction accelerant 14 may adhere to the granules of the conventional filler 10 via the binder 12. For example, as shown in FIG. 1C, one or more granules of the arc extinction accelerant 14 may be bonded to each granule of the conventional filler 10.

[0019] In a further step of the exemplary method illustrated in FIG. 1D, the binder 12 in the mixture described above may be dried or cured, such as by subjecting the mixture to a thermal cure, moisture cure, UV cure, or the like. Once the binder 12 has been so cured, the granules of the arc-quenching accelerant 14 may be firmly adhered to the granules of the conventional filler 10, and the arc-quenching fuse filler 16 of the present disclosure may be complete and ready to be implemented in a fuse as further described below. Importantly, the flowability of the arc-quenching fuse filler 16 may be the same or similar to the flowability of a conventional filler (e.g., silica, silica sand, or the like). Thus, the arc-quenching fuse filler 16 may be poured, flowed, or otherwise dispensed into the fuse body using conventional vibration techniques used to dispense conventional fillers (e.g., with a conventional sand filler). Because the granules of the arc-quenching accelerant 14 are bound to the granules of the conventional filler 10, such dispensing may be accomplished without the granules of the arc-quenching accelerant 14 becoming separated from the granules of the conventional filler 10, thus maintaining the effectiveness of the composition. Similarly, the homogeneity and effectiveness of the arc quenching fuse filler 16 can be maintained when the composition is exposed to vibration in the field, such as when the arc quenching fuse filler 16 is implemented in a fuse installed in a vehicle that experiences or generates vibration when driven.

[0020] Referring to FIG. 2A, a side cross-sectional view is shown illustrating an exemplary fuse 100 incorporating the arc-quenching fuse filler described above. In various embodiments, the fuse 100 may be a cartridge fuse having a tubular fuse body 112. The disclosure is not limited in this respect. In various alternative embodiments, the fuse 100 may be a surface mount fuse or other type of fuse having a fusible element extending through a generally hollow fuse body. The fuse body 112 may be formed from a material that is electrically insulating and preferably heat resistant. Examples of such materials include, but are not limited to, ceramic, glass, and glass fiber filled melamine formaldehyde resin.

[0021] A pair of conductive end caps 118, 120 may be disposed on opposite ends of the fuse body 112 and may be adapted to facilitate electrical connection of the fuse 100 in a circuit. A fusible element 124 may extend through the hollow interior of the fuse body 112 and may be connected to the end caps 118, 120 in electrical communication therewith, such as by solder. The end caps 118, 120 may be formed of a conductive material, including but not limited to copper or one of its alloys, and may be plated with nickel or other conductive corrosion-resistant coatings. The fusible element 124 may be formed of a conductive material, including but not limited to tin or copper, and may be configured to melt and separate upon the occurrence of a predetermined fault condition, such as an overcurrent condition in which an amount of current flows through the fusible element 124 that exceeds a predetermined maximum value. This maximum value is typically referred to as the "rating" of the fuse 100.

[0022] The fusible element 124 may be any type of fusible element suitable for the desired application, including, but not limited to, a wire, a corrugated strip, a wire wound around an insulating core, and the like. The central portion 125 of the fusible element 124 may be thinned, narrowed, perforated, or otherwise weakened relative to other portions of the fusible element 124 to ensure that the fusible element 124 separates at the central portion 125. In various embodiments, a quantity of dissimilar metal 126, sometimes referred to as a "Metcalf spot" (hereinafter "metal spot 126"), may be applied to the central portion 125 of the fusible element 124. The metal spot 126 may be formed of one or more of nickel, indium, silver, tin, or other metals that have a lower melting temperature than the base metal (e.g., copper) from which the fusible element 124 is formed. Thus, the metal spot 126 may melt more easily than the base metal of the fusible element 124 and diffuse into the base metal upon the occurrence of an overcurrent condition. The base metal of fusible element 124 and the dissimilar metal of metal spot 126 are selected so that diffusion of one into the other creates an intermetallic phase with a lower melting temperature and higher resistance than the base metal alone, thereby causing center portion 125 of fusible element 124 to melt more easily than other portions of fusible element 124. In various embodiments of fuse 100, metal spot 126 may be omitted entirely.

[0023] 2A, the fuse body 112 may be partially or completely filled with the above-described arc-quenching fuse filler 16 of the present disclosure, which may partially or completely surround the fusible element 124. In various alternative embodiments, the fuse body 112 may include multiple interior walls or partitions that define sealed chambers surrounding the central portion 125 of the fusible element 124, and only such chambers may be filled with the arc-quenching fuse filler 16. The present disclosure is not limited in this respect.

[0024] During an overcurrent condition in the fuse 100, the central portion 125 of the fusible element 124 can melt and separate, and an electric arc 136 can propagate across the gap left between the separated ends of the fusible element 124, as shown in FIG. 2B. Heat from the electric arc 136 can burn and decompose the conventional filler 10 (e.g., silica) in the arc-quenching fuse filler 16. When the conventional filler 10 melts and changes from a solid to a liquid, it can absorb heat from the electric arc 136, thus cooling the electric arc 136. The heat from the electric arc 136 can also simultaneously burn and decompose the arc-quenching accelerant 14 (e.g., melamine, guanidine, guanine, hydantoin, etc., listed above) of the arc-quenching fuse filler 16. When the arc-quenching accelerant 14 decomposes, it undergoes an endothermic chemical reaction that absorbs heat. This causes the electric arc 136 to cool rapidly. Furthermore, depending on the particular arc extinction accelerant 14 implemented in the arc extinction fuse filler 16, some by-products of the endothermic chemical reaction may be non-conductive gases (e.g., ammonia) that may impede the ability of the electrical arc 136 to sustain. Thus, upon the occurrence of an overcurrent condition in the fuse 110, the arc extinction fuse filler 16 may absorb heat and release gases that are unfavorable to the sustainment of the electrical arc 136, thereby contributing to a more rapid and robust extinction of the arc than may be achieved with conventional fuse filler materials alone. Thus, the breaking capacity of the fuse 100 is significantly increased as compared to fuses utilizing conventional fuse filler materials alone, and components connected to and / or located in close proximity to the fuse 100 are protected from damage that would otherwise occur if the electrical arc 136 were allowed to sustain.

[0025] As used herein, elements or steps described in the singular and preceded by the word "a" or "an" are to be understood as not excluding a plurality of elements or steps, unless such exclusion is expressly stated. Moreover, 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.

[0026] Although the present disclosure refers to particular embodiments, numerous modifications, alterations, and variations can be made to the described embodiments without departing from the sphere and scope of the present disclosure as defined in the appended claims. Accordingly, it is intended that the present disclosure not be limited to the described embodiments, but rather have its full scope defined by the language of the following claims and their equivalents. (Other possible items) [Item 1] preparing a conventional fuse filler material; mixing said conventional fuse filler material with a binder; mixing said conventional fuse filler material and said binder with an arc extinction enhancer; and curing the binder, whereby the granules of the arc-quenching enhancer are bonded to the granules of the conventional fuse filler material. 16. A method for producing an arc-quenching fuse filler, comprising: [Item 2] 2. The method of claim 1, wherein the conventional fuse filler material comprises at least one of silica, silica sand, calcium carbonate, calcium sulfate dihydrate, fuller's earth, and steatite. [Item 3] 3. The method of claim 1 or 2, wherein the arc extinction promoter comprises at least one of melamine, guanidine, guanine, hydantoin, allantoin, urea, melamine formaldehyde, melamine cyanurate polymer, boric acid, aluminum trihydrate, and derivatives thereof. [Item 4] 4. The method of any one of claims 1 to 3, wherein the binder comprises at least one of silicone, polyvinyl alcohol, epoxy, cellulose, calcium aluminate, alumina silicate, and sodium silicate. [Item 5] 5. The method according to any one of items 1 to 4, wherein the granules of the arc-extinguishing promoter have a length or diameter in the range of 5 um to 60 um. [Item 6] 6. The method of any one of claims 1 to 5, wherein the granules of the arc-extinguishing enhancer are 0.3% to 10% of the size of the granules of the conventional fuse filler material. [Item 7] 7. The method of any one of claims 1 to 6, wherein curing the binder comprises exposing the mixed conventional fuse filler material, the binder, and the arc extinction accelerator to one of a thermal cure, a moisture cure, and a UV cure. [Item 8] Conventional fuse filler materials; Arc extinction promoter; and A binder that binds the granules of the arc extinction enhancer to the granules of the conventional fuse filler material. 1. An arc quenching fuse filler comprising: [Item 9] 9. The arc-quenching fuse filler of claim 8, wherein the conventional fuse filler material comprises at least one of silica, silica sand, calcium carbonate, calcium sulfate dihydrate, fuller's earth, and steatite. [Item 10] 10. The arc-quenching fuse filler of claim 8 or 9, wherein the arc-quenching promoter comprises at least one of melamine, guanidine, guanine, hydantoin, allantoin, urea, melamine formaldehyde, melamine cyanurate polymer, boric acid, aluminum trihydrate, and derivatives thereof. [Item 11] 11. The arc-quenching fuse filler of any one of items 8 to 10, wherein the binder comprises at least one of silicone, polyvinyl alcohol, epoxy, cellulose, calcium aluminate, alumina silicate, and sodium silicate. [Item 12] 12. The arc-quenching fuse filler of any one of items 8 to 11, wherein the granules of the arc-quenching enhancer are 0.3%-10% of the size of the granules of the conventional fuse filler material. [Item 13] 13. The arc quenching fuse filler of any one of items 8 to 12, wherein the arc quenching fuse filler has a flowability that facilitates dispensing the arc quenching fuse filler into fuses using a conventional sand filling machine. [Item 14] A fuse, An electrically insulating tubular fuse body; first and second conductive end caps disposed over opposite ends of the fuse body; a fusible element extending through the fuse body and connecting the first end cap to the second end cap, the fusible element having a central portion adapted to melt and separate upon an overcurrent condition within the fuse; and an arc-quenching fuse filler disposed within the fuse body and at least partially surrounding the central portion of the fusible element, the arc-quenching fuse filler comprising: Conventional fuse filler materials; Arc extinction promoter; and a binder that bonds the granules of the arc extinction enhancer to the granules of the conventional fuse filler material A fuse. [Item 15] 15. The fuse of claim 14, wherein the conventional fuse filler material comprises at least one of silica, silica sand, calcium carbonate, calcium sulfate dihydrate, fuller's earth, and steatite. [Item 16] 16. The fuse of claim 14 or 15, wherein the arc-quenching enhancer comprises at least one of melamine, guanidine, guanine, hydantoin, allantoin, urea, melamine formaldehyde, melamine cyanurate polymer, boric acid, aluminum trihydrate, and derivatives thereof. [Item 17] 17. The fuse of any one of claims 14 to 16, wherein the binder comprises at least one of silicone, polyvinyl alcohol, epoxy, cellulose, calcium aluminate, alumina silicate, and sodium silicate. [Item 18] 18. The fuse of any one of claims 14 to 17, wherein the granules of the arc-extinguishing enhancer are 0.3% to 10% of the size of the granules of the conventional fuse filler material.

Claims

1. A method for producing an arc-quenching fuse filler, comprising: providing a conventional fuse filler material; mixing said conventional fuse filler material with a binder; mixing said conventional fuse filler material and said binder with an arc extinction enhancer; and curing said binder, thereby bonding said granules of arc-quenching enhancer to said granules of conventional fuse filler material. Equipped with the binder is a silicone-based binder; A method for producing an arc-quenching fuse filler, wherein the arc-quenching fuse filler has a flowability that facilitates dispensing the arc-quenching fuse filler into fuses using conventional sand filling machines.

2. 10. The method of claim 1, wherein the conventional fuse filler material comprises at least one of silica, silica sand, calcium carbonate, calcium sulfate dihydrate, fuller's earth, and steatite.

3. 3. The method of claim 1 or 2, wherein the arc extinction promoter comprises at least one of melamine, guanidine, guanine, hydantoin, allantoin, urea, melamine formaldehyde, melamine cyanurate polymer, boric acid, aluminum trihydrate, and derivatives thereof.

4. 4. The method of claim 1, wherein the granules of the arc-extinguishing accelerator have a length or diameter in the range of 5 um to 60 um.

5. The method of any one of claims 1 to 4, wherein the granules of the arc-extinguishing enhancer are 0.3% to 10% of the size of the granules of the conventional fuse filler material.

6. 6. The method of claim 1, wherein curing the binder comprises exposing a mixture of the conventional fuse filler material, the binder, and the arc extinction accelerator to one of a thermal cure, a moisture cure, and a UV cure.

7. An arc quenching fuse filler comprising: Conventional fuse filler materials; Arc extinction promoter; and A binder that binds the granules of the arc extinction enhancer to the granules of the conventional fuse filler material. Equipped with the binder is a silicone-based binder; An arc-quenching fuse filler, wherein the arc-quenching fuse filler has a flowability that facilitates dispensing the arc-quenching fuse filler into fuses using conventional sand filling machines.

8. 8. The arc-quenching fuse filler of claim 7, wherein the conventional fuse filler material comprises at least one of silica, silica sand, calcium carbonate, calcium sulfate dihydrate, fuller's earth, and steatite.

9. 9. The arc-quenching fuse filler of claim 7 or 8, wherein the arc-quenching promoter comprises at least one of melamine, guanidine, guanine, hydantoin, allantoin, urea, melamine formaldehyde, melamine cyanurate polymer, boric acid, aluminum trihydrate, and derivatives thereof.

10. The arc-quenching fuse filler of any one of claims 7 to 9, wherein the granules of the arc-quenching enhancer are 0.3% to 10% of the size of the granules of the conventional fuse filler material.

11. A fuse, an electrically insulating tubular fuse body; first and second conductive end caps disposed over opposite ends of the fuse body; a fusible element extending through the fuse body and connecting the first end cap to the second end cap, the fusible element having a central portion adapted to melt and separate upon an overcurrent condition within the fuse; and an arc-quenching fuse filler disposed within the fuse body and at least partially surrounding the central portion of the fusible element; The arc extinguishing fuse filler comprises: Conventional fuse filler materials; Arc extinction promoter; and a binder that bonds granules of the arc extinction enhancer to granules of the conventional fuse filler material; the binder is a silicone-based binder; A fuse, wherein the arc-quenching fuse filler has a flowability that facilitates dispensing the arc-quenching fuse filler into the fuse using conventional sand filling machines.

12. 12. The fuse of claim 11, wherein the conventional fuse filler material comprises at least one of silica, silica sand, calcium carbonate, calcium sulfate dihydrate, fuller's earth, and steatite.

13. 13. The fuse of claim 11 or 12, wherein the arc-quenching accelerator comprises at least one of melamine, guanidine, guanine, hydantoin, allantoin, urea, melamine formaldehyde, melamine cyanurate polymer, boric acid, aluminum trihydrate, and derivatives thereof.

14. The fuse of any one of claims 11 to 13, wherein the granules of the arc-extinguishing enhancer are 0.3% to 10% of the size of the granules of the conventional fuse filler material.

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