Fuse with cast arc suppression material for improved breaking capability

Abstract

The present invention relates to a fuse comprising: a fuse body; the fusible element is arranged in the fuse body; a first terminal and a second terminal extending from opposite ends of the fusible element and out of the fuse body; and an amount of an arc suppressing material formed on the fusible element, wherein the arc suppressing material is formed from a mixture of sand, an arc suppressing agent, and a flame retardant binder.

Description

Technical Field

[0001] The present disclosure generally relates to the field of circuit protection devices, and more particularly, to a fuse with high breaking capacity having arc mitigation features. Background Art

[0002] Fuses are commonly used as circuit protection devices and are typically installed between a power source and the components to be protected in a circuit. Generally, a fuse includes a fusible element disposed within an electrically insulating fuse body. Conductive terminals extend from opposite ends of the fusible element to facilitate electrical connection of the fuse in the circuit. When an overcurrent condition occurs in the circuit, the fusible element melts or otherwise opens to prevent current from flowing through the fuse, thereby protecting the connected electrical components.

[0003] When the fusible element of a fuse melts during an overcurrent condition, an arc may sometimes propagate between the separated portions of the fusible element (e.g., through evaporated particles from the melted fusible element). The arc can rapidly heat the surrounding air and particles in the environment and may cause a small explosion within the fuse. In some cases, the explosion may rupture the fuse body, which can potentially damage surrounding components. The likelihood of rupture is generally proportional to the severity of the overcurrent condition. The maximum current that a fuse can block 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 increasing the cost, size, or form factor of the fuse.

[0004] In view of these and other considerations, the present improvement may be useful. Summary of the Invention

[0005] The present 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 features or essential features of the claimed subject matter, nor is it intended to be used to help determine the scope of the claimed subject matter.

[0006] A fuse according to an exemplary embodiment of the present disclosure may include: a fuse body; a fusible element disposed within the fuse body; a first terminal and a second terminal extending from opposite ends of the fusible element and extending out of the fuse body; and a quantity of arc suppression material formed on the fusible element, wherein the arc suppression material is formed from a mixture of sand, an arc inhibitor, and a flame retardant binder. Brief Description of the Drawings

[0007] Figure 1 is a perspective view showing a fuse according to an exemplary embodiment of the present disclosure;

[0008] Figure 2 shows Figure 1 a cross-sectional side view of the fuse;

[0009] Figure 3A shows the Figure 1 top view of a fuse assembly of a fuse in an un-tripped state;

[0010] Figure 3B shows the Figure 1 side view of a fuse assembly of a fuse in an un-tripped state;

[0011] Figure 4A shows the Figure 1 top view of a fuse assembly of a fuse in a tripped state;

[0012] Figure 4B shows the Figure 1 side view of a fuse assembly of a fuse in a tripped state;

[0013] Figure 5A shows the top view of a fuse assembly according to another embodiment of the present disclosure;

[0014] Figure 5B shows the Figure 5A top view of a fuse assembly disposed within the fuse body of a cartridge fuse;

[0015] Figures 6A - 6D shows a series of top views of a method of assembling a surface-mounted fuse according to an embodiment of the present disclosure.

[0016] The drawings are not necessarily to scale. The drawings are merely exemplary and are not intended to depict the specific parameters of the present disclosure. The drawings are intended to depict exemplary embodiments of the present disclosure and should not be considered as limiting the scope. In the drawings, like numbers represent like elements.

[0017] In addition, for clarity, some elements in some of the drawings may be omitted or not drawn to scale. Cross-sectional views may be in the form of "slices" or "close-up" cross-sectional views, and certain background lines visible in a "true" cross-sectional view are omitted for clarity. In addition, for clarity, some reference numerals may be omitted in some of the drawings. Detailed Description

[0018] The fuses according to the present disclosure will now be described more fully hereinafter with reference to the accompanying drawings, in which certain exemplary embodiments of the fuses are shown. The fuses may be implemented in many different forms and should not be construed as limited to the embodiments set forth herein. These embodiments are provided so that this disclosure will be thorough and complete and will fully convey the scope of the fuses to those skilled in the art. In the drawings, unless otherwise noted, the same numbers always refer to the same elements.

[0019] Reference Figure 1 and Figure 2 provide, respectively, a perspective view and a cross-sectional side view of a fuse 10 according to an exemplary embodiment of the present disclosure. For convenience and clarity, terms such as "top", "bottom", "upper", "lower", "upper portion", "lower portion", "above", and "below" may be used herein to describe the relative positions and orientations of the various components of the fuse 10, all of which are relative to Figure 1 and Figure 2 the geometry and orientation of the fuse 10 as presented in. The terms include the above words, their derivatives, and words of similar meaning.

[0020] The fuse 10 generally may include a conductive fuse assembly 11 disposed partially within an electrically insulating fuse body 14. The fuse assembly 11 may include a fusible element 12, and first and second terminals 16a and 16b that extend from opposite ends of the fusible element 12 and extend out of the fuse body 14. The fusible element 12 and the first and second terminals 16a and 16b may be made of any of a variety of conductive materials, including but not limited to copper, tin, silver, zinc, aluminum, alloys including these materials, or combinations thereof. The fuse body 14 may be formed of any suitable dielectric material, including but not limited to plastics, ceramics, various composite materials, etc. The fuse assembly 11 may be formed using any of a variety of techniques, including but not limited to stamping, cutting, and printing, and may include forming the fusible element 12 and the first and second terminals 16a and 16b either separately or as a single workpiece. If the fusible element 12 and the first and second terminals 16a and 16b are formed separately (i.e., in separate workpieces), then these workpieces may subsequently be joined together using various techniques, including, for example, brazing, welding, or other known joining processes.

[0021] In various embodiments, the fuse body 14 may include a plurality of segments or portions that are joined together to define a cavity 18 within which the fusible element 12 is disposed. For example, the fuse body 14 may include an upper segment 20a and a lower segment 20b that are capable of being joined together (e.g., via thermal riveting, riveting, ultrasonic welding, etc.) to form a continuous, substantially sealed body that protects the fusible element 12 from external elements. The first and second terminals 16a and 16b may extend from the fuse body 14 and may facilitate the electrical connection of the fuse 10 within a circuit. For example, the first and second terminals 16a and 16b may include respective first and second mounting holes 22a and 22b formed therein for receiving bolts or studs (not shown) to connect the fuse 10 to a power source (e.g., a battery) and to a load.

[0022] ReferenceFigure 3A and Figure 3B , shows top and side views of the fusible element 12 of the fuse 10 and the first terminal 16a and the second terminal 16b (the fuse body 14 is omitted for clarity). The fusible element 12 can be configured to melt, decompose, or otherwise open if the current flowing through the fuse 10 exceeds a predetermined threshold or “rated current” of the fuse 10. In certain embodiments, the fusible element 12 can have a meandering shape as shown in Figure 3A . The present disclosure is not limited to this aspect. In various embodiments, the fusible element 12 can include perforations, slots, thinned or narrowed sections, and / or various other features for making certain portions of the fusible element 12 more fusible or breakable relative to other portions of the fusible element 12.

[0023] The fuse 10 can further include an amount of arc suppression material 30 disposed on the fuse assembly 11, conformally coated and covering the fusible element 12 and adjacent portions of the first terminal 16a and the second terminal 16b in close contact with the fusible element. The arc suppression material 30 can be a mixture of sand, an arc suppressant, and a flame retardant binder. In various examples, the arc suppressant can be melamine or cyanuric acid, and the flame retardant binder can be a silicone-based material such as polydimethylsiloxane (PDMS). The arc suppressant can be provided in an amount of 5.00% to 12.00% by weight of the arc suppression material 30, and the flame retardant binder can be provided in an amount of 3.00% to 6.00% by weight of the arc suppression material 30. The present disclosure is not limited to this aspect. During the manufacture of the fuse 10, any suitable casting process can be used to directly cast the arc suppression material 30 onto the fusible element 12 and adjacent portions of the first terminal 16a and the second terminal 16b.

[0024] When an overcurrent condition occurs in the fuse 10, the fusible element 12 can melt and separate, and an arc 32 can propagate through a gap 34 remaining between the separated ends of the fusible element 12, as shown in Figure 4A and Figure 4BAs shown. The heat from the electric arc 32 can melt the arc suppression material 30, and then the arc suppression material in a fluid state can flow into the gap 34 and extinguish the electric arc 32. The heat from the electric arc 32 can also burn / decompose the arc suppression material 30, causing an endothermic chemical reaction in the arc suppression material 30 that absorbs heat. The electric arc 32 is thus rapidly cooled. In addition, some by-products of the endothermic chemical reaction can be non-conductive gases (e.g., ammonia), which can impede the ability of the electric arc 32 to persist. Therefore, when an overcurrent situation occurs in the fuse 10, the arc suppression material 30 can absorb heat and release gases that are not conducive to maintaining the electric arc. Thus, the duration and severity of the arc discharge within the fuse 10 are reduced, which in turn provides the fuse 10 with improved interrupting ability relative to conventional fuses.

[0025] The arc suppression material 30 implemented in the fuse 10 described above can be similarly implemented in various other types of fuse configurations. For example, referring to Figure 5A , an embodiment of the present disclosure is shown, in which the arc suppression material 30 can be directly cast onto a fuse assembly 111 adapted for use in a cartridge fuse. In particular, the arc suppression material 30 can be cast onto the fusible element 112 and adjacent portions of the first terminal 116a and the second terminal 116b of the fuse assembly 111. Referring to Figure 5B , the fuse assembly 111 can be inserted into a fuse body 114, and the fuse body 114 can be filled with a certain amount of sand or other arc quenching filler 119 that surrounds the fusible element 112.

[0026] Referring to Figures 6A - 6D , another embodiment of the present disclosure is shown, in which the above-described arc suppression material 30 is implemented in a surface-mounted fuse that includes a fuse assembly 211 disposed within a base 220a of the fuse body, and a cover 220b disposed above the fuse assembly 211 and fastened (e.g., via thermo-riveting, riveting, ultrasonic welding, etc.) to the base 220a. Different from the above embodiment, the arc suppression material 30 is not directly cast on the fuse assembly 211. Instead, the arc suppression material 30 can be pre-cast into first and second segments or disks 230a, 230b that surround or sandwich the fusible element 212 of the fuse assembly 211. For example, referring to Figure 6A , a first step in the process of assembling a surface-mounted fuse is shown, in which a first disk 230a of the arc suppression material 30 is placed within the base 220a of the fuse body. Referring to Figure 6B , then the fuse assembly 211 is placed in the base 220a, the fusible element 212 is disposed on top of the first disk 230a, and the first terminal 216a and the second terminal 216b of the fuse assembly 211 extend out of the base 220a. Referring to Figure 6C, the second disk 230b of the arc suppression material 30 may be disposed on top of the fusible element 212. In various embodiments, as Figure 6B best shown in Figure 6D , the first terminal 216a and the second terminal 216b may be formed or bent to define a bracket for receiving and holding the second disk 230b. Referring to

[0027] As used herein, an element or step recited in the singular and preceded by the word "a" or "an" should be understood to not exclude a plurality of elements or steps, unless such exclusion is explicitly recited. Additionally, a reference to "one embodiment" of the present disclosure is not to be construed as excluding the existence of additional embodiments that also incorporate the recited features.

[0028] Although the present disclosure refers to certain embodiments, many modifications, variations, and changes may be made to the described embodiments without departing from the scope and spirit of the present disclosure as defined in the appended claims. Accordingly, the present disclosure is not limited to the described embodiments, but rather has the full scope defined by the language of the appended claims and their equivalents.

Claims

1. A fuse, comprising: Fuse body; a fusible element, the fusible element being disposed within the fuse body; a first terminal and a second terminal extending from opposite ends of the fusible element and out of the fuse body; as well as A quantity of arc-suppressing material is formed on the fusible element, wherein the arc-suppressing material is formed from a mixture of sand, an arc suppressant, and a flame-retardant binder.

2. The fuse according to claim 1, wherein: The arc inhibitor is one of melamine and cyanuric acid.

3. The fuse according to claim 1, wherein: The flame retardant binder is polydimethylsiloxane.

4. The fuse according to claim 1, wherein: The arc-suppressing material is cast directly onto the fusible element.

5. The fuse according to claim 1, wherein: The fuse body is filled with an arc-extinguishing material that surrounds the fusible element and the arc-suppression material.

6. The fuse according to claim 5, wherein: The arc extinguishing material is sand.

7. A fuse, comprising: Fuse body; a fusible element, the fusible element being disposed within the fuse body; a first terminal and a second terminal extending from opposite ends of the fusible element and out of the fuse body; a first disk formed of an arc-suppressing material and disposed on a first side of the fusible element; as well as a second disk formed of an arc-suppressing material and disposed on a second side of the fusible element opposite the first side; The arc suppression material is formed of a mixture of sand, an arc suppressant and a flame retardant binder.

8. The fuse according to claim 7, wherein: The arc inhibitor is one of melamine and cyanuric acid.

9. The fuse according to claim 7, wherein: The flame retardant binder is polydimethylsiloxane.

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