Patent Publication Number: US-11393651-B2

Title: Fuse with stone sand matrix reinforcement

Description:
BACKGROUND OF THE INVENTION 
     The field of the invention relates generally to electrical circuit protection fuses and methods of manufacture, and more specifically to the manufacture of high voltage, electrical fuses with a reinforced sand matrix. 
     Fuses are widely used as overcurrent protection devices to prevent costly damage to electrical circuits. Fuse terminals typically form an electrical connection between an electrical power source or power supply and an electrical component or a combination of components arranged in an electrical circuit. One or more fusible links or elements, or a fuse element assembly, is connected between the fuse terminals, so that when electrical current flow through the fuse exceeds a predetermined limit, the fusible elements melt and opens one or more circuits through the fuse to prevent electrical component damage. Surrounding the fuse element assembly is an arc extinguishing filler such as quartz silica sand. 
     Electrical fuses are operable in electrical power systems to safely interrupt both relatively high fault currents and relatively low fault currents with equal effectiveness and high durability. In certain types of fuses the durability of the electrical fuse is related to the strength of the sand filler once it has been stoned with a sodium silicate binder. In view of constantly expanding variations of electrical power systems, known fuses of this type are disadvantaged in some aspects. Improvements in electrical fuses are therefore desired to meet the needs of the marketplace. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Non-limiting and non-exhaustive embodiments are described with reference to the following Figures, wherein like reference numerals refer to like parts throughout the various drawings unless otherwise specified. 
         FIG. 1  is an exemplary electrical fuse. 
         FIG. 2  is a side elevational view of an electrical fuse. 
         FIG. 3  is a side elevational view of an electrical fuse including a reinforcing element. 
         FIG. 4  is an end view with parts removed showing an internal construction of the electrical fuse shown in  FIG. 3 . 
         FIG. 5  is a flowchart of a first exemplary method of manufacturing the electrical fuse shown in  FIGS. 2 and 3 . 
         FIG. 6  is a flowchart of a second exemplary method of manufacturing the electrical fuse shown in  FIG. 1 . 
         FIG. 7  is a flowchart of a third exemplary method of manufacturing the electrical fuse shown in  FIG. 1 . 
         FIG. 8  is a schematic diagram of an electric vehicle. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Recent advancements in electric vehicle technologies, among other things, present unique challenges to fuse manufacturers. Electric vehicle manufacturers are seeking fusible circuit protection for electrical power distribution systems operating at voltages much higher than conventional electrical power distribution systems for vehicles, while simultaneously seeking smaller and more robust fuses to meet electric vehicle specifications and demands. 
     Electrical power systems for conventional, internal combustion engine-powered vehicles operate at relatively low voltages, typically at or below about 48 VDC. Electrical power systems for electric-powered vehicles, referred to herein as electric vehicles (EVs), however, operate at much higher voltages. The relatively high voltage systems (e.g., 200 VDC and above) of EVs generally enables the batteries to store more energy from a power source and provide more energy to an electric motor of the vehicle with lower losses (e.g., heat loss) than conventional batteries storing energy at 12 volts or 24 volts used with internal combustion engines, and more recent 48 volt power systems. 
     Electrical power systems for state of the art EVs may operate at voltages as high as 450 VDC. The increased power system voltage desirably delivers more power to the EV per battery charge. Operating conditions of electrical fuses in such high voltage power systems is much more severe, however, than lower voltage systems. Specifically, specifications relating to electrical arcing conditions as the fuse opens can be particularly difficult to meet for higher voltage power systems, especially when coupled with the industry preference for reduction in the size of electrical fuses. While known power fuses are presently available for use by EV OEMs in high voltage circuitry of state of the art EV applications, the size and weight, not to mention the durability, of conventional power fuses capable of meeting the requirements of high voltage power systems for EVs is impractically high for implementation in new EVs. 
     Providing relatively smaller power fuses that can capably handle high current and high battery voltages of state of the art EV power systems, while still retaining high robustness and durability as the fuse element operates at high voltages is challenging, to say the least. Fuse manufacturers and EV manufactures would each benefit from smaller, lighter, more durable fuses. While EV innovations are leading the markets desired for smaller, higher voltage fuses, the trend toward smaller, yet more powerful, electrical systems transcends the EV market. A variety of other power system applications would undoubtedly benefit from smaller fuses that otherwise offer comparable performance and superior durability to larger, conventionally fabricated fuses. Smaller, lighter, more durable high voltage power fuses are desired to meet the needs of EV manufacturers, without sacrificing circuit protection performance. Sodium silicate is applied to the sand matrix of a fuse to “stone” it to improve temperature rise performance, and interruption performance. The sodium silicate sand matrix is susceptible to damage via impact and shock forces experienced at various stages in its life cycle including; during manufacturing, handling, shipping, installation, and operation. Improvements are needed to longstanding and unfulfilled needs in the art. A reinforcement method is required to improve the robustness and durability of the stone sand matrix while meeting the temperature rise and interruption performance requirements of the fuse applications. 
     In addition to providing structural support for a fuse, the sodium silicate sand matrix of a fuse is designed to extinguish the arcing that occurs at the weak spots of a fuse when it heats up and melts. Damage to the sodium silicate sand matrix can result in the matrix failing to properly extinguish the arcing. This could result in damage to adjacent electrical components, and the EV itself. Additionally, damage to the sodium silicate sand matrix can result in damage to the fuse element, such that the fuse does not work as intended, resulting in the fuse heating up and melting in an undesirable location away from the center of the fuse element, or damage may result in the fuse not working at all. 
     Exemplary embodiments of electrical circuit protection fuses are described below that address these and other difficulties. Relative to known high voltage power fuses, the exemplary fuse embodiments advantageously offer increased durability and sturdiness during both handling and operation, while still maintaining a relatively smaller and more compact physical package size that, in turn, occupies a reduced physical volume or space in an EV  101 . Also relative to known fuses, the exemplary fuse embodiments advantageously offer a relatively higher power handling capacity, higher voltage operation, full range time-current operation, lower short-circuit let-through energy performance, and longer life operation and reliability. As explained below, the exemplary fuse embodiments are designed and engineered to provide very high current limiting performance as well as long service life and high reliability from nuisance or premature fuse operation. Method aspects will be in part explicitly discussed and in part apparent from the discussion below. 
     While described in the context of EV applications and a particular type of fuse having certain ratings discussed below, the benefits of the invention are not necessarily limited to EV applications or to the particular fuse type or ratings described. Rather the benefits of the invention are believed to more broadly accrue to many different power system applications and can also be practiced in part or in whole to construct different types of fuses having similar or different ratings than those discussed herein. 
     As shown in  FIGS. 1 and 2 , an exemplary electrical fuse  100  includes a housing  102  and terminal assemblies  104 ,  106 . Terminal assembly  104  includes endplate  108 , terminal contact block  110  and terminal blade  112 . Terminal assembly  106  includes endplate  114 , terminal contact block  116  and terminal blade  118 . Terminal blades  112 ,  118  are configured for connection to line and load side circuitry. Electrical fuse  100  further includes a fuse element assembly  120  including one or more fuse elements  122  (three fuse elements in the example illustrated) that completes an electrical connection coupled between the terminal blades  112 ,  118 . When subjected to predetermined current conditions, the fuse element melts, disintegrates, or otherwise structurally fails and opens the circuit path through the fuse element between the terminal blades  112 ,  118 . Load side circuitry is therefore electrically isolated from the line side circuitry, via operation of the fuse element(s), to protect load side circuit components and circuitry from damage when electrical fault conditions occur. 
     An arc extinguishing filler medium or material  124  surrounds the fuse element assembly  120 . The filler material  124  may be introduced to the housing  102  via one or more fill openings in one of the end plates  108 ,  114  that are sealed with fill plugs  236  (shown in  FIG. 4 ). The fill plugs  236  may be fabricated from steel, plastic or other materials in various embodiments. In other embodiments a fill hole or fill holes may be provided in other locations, including but not limited to the housing  102  to facilitate the introduction of the filler material  124 . 
     In one contemplated embodiment, the filling material  124  includes quartz silica sand and a sodium silicate binder. The quartz sand has a relatively high heat conduction and absorption capacity in its loose compacted state, but can be silicated to provide improved performance. For example, by adding a liquid sodium silicate solution to the sand and then drying the sand, silicate filler material  124  may be obtained with the following advantages. 
     The silicate material  124  creates a thermal conduction bond of sodium silicate to the fuse element assembly  120 , the quartz sand, the fuse housing  102 , and the end plates  108  and  114 . This thermal bond allows for higher heat conduction from the fuse element assembly  120  to its surroundings, circuit interfaces and conductors. The application of sodium silicate to the quartz sand aids with the conduction of heat energy out and away from the fuse element assembly  120 . The sodium silicate mechanically binds the sand to the fuse element assembly  120 , terminal assemblies  104 ,  106  and housing  102  increasing thermal conduction between these materials. Unlike a filler material that includes sand only, the silicated sand of the filler material  124  mechanically bonds to the fuse elements as opposed to making point contact with the conductive portions of the fuse elements. Much more efficient and effective thermal conduction is therefore made possible by the silicated filler material  124 . Specifically, the application of sodium silicate to the mixture of filler material  124  aids with the conduction of heat energy out and away from the fuse element weak spots and reduces mechanical stress and strain to mitigate load current cycling fatigue that may otherwise result. The sodium silicate mechanically binds the sand to the fuse element, terminal and housing increasing the thermal conduction between these materials. Less heat is generated in the weak spots and the onset of mechanical strain is accordingly retarded. 
     The silicated filler material  124 , however, introduces certain problems in other aspects. Specifically, the silicated filler material  124  hardens like a stone and is prone to cracking. The cracking may occur for various reasons, including manufacturing imperfections, impact, and vibration of the fuse in installation, service, or use in a power system. As shown in  FIG. 1 , cracks  128  may form in silicated filler material  124  and may extend across the cylindrical cross section of the fuse in locations adjacent to the fuse element assembly  120 . Such cracks in the stone sand matrix of the silicated filler material  124  may adversely affect the electrical performance and reliability of the fuse to operate as designed to interrupt a circuit and contain arc energy as the fuse elements open. 
       FIG. 2  illustrates an electrical fuse  100  including exemplary reinforcing fibers  126  to be used in combination with the silicated filler material  124  in fuse  100  and prevent the negative effects of cracking of the silicated filler material. In the exemplary embodiment, reinforcing fibers  126  are composed of inorganic (i.e., non-organic) material. In contemplated embodiments, reinforcing fibers  126  may be glass, fiberglass or other suitable materials. Additionally, reinforcing fibers  126  have varying lengths. When mixed with filler material  124 , reinforcing fibers  126  are suspended within filler material  124  and are configured to increase the tensile strength of the stone sand matrix such that the durability and structural integrity of the filler material  124  in the fuse  100  is increased. In an exemplary embodiment, reinforcing fibers  126  have varying lengths and a high tensile strength. A mixture of the filler material  124  and reinforcing fibers  126  surrounds the fuse element assembly  120 . The mixture of filler material  124  and reinforcing fibers  126  provides increased durability and structural support to fuse element assembly  120  and fuse  100 . 
     Additionally, the mixture of filler material  124  and reinforcing fibers are mixed with a silica binder material to mechanically bind the mixture to the fuse element assembly  120 , terminal assemblies  104 ,  106  and housing  102  increasing the thermal conduction and structural integrity between these materials. Because the reinforcement of the material  124  including the fibers  126 , the material is more resistant to the cracking discussed above that may present performance and reliability issues of the fuse  100  in operation. 
       FIG. 3  illustrates an electrical fuse  200  formed in accordance with an exemplary embodiment of the present invention. As shown in  FIG. 3 , the electrical fuse  200  includes a housing  202 , terminal assemblies  204 ,  206 . Terminal assembly  204  includes endplate  208 , terminal contact block  210  and terminal blade  212 . Terminal assembly  206  includes endplate  214 , terminal contact block  216  and terminal blade  218 . Terminal blades  212 ,  218  are configured for connection to line and load side circuitry. Electrical fuse  200  further includes a fuse element assembly  220  including one or more fuse elements that completes an electrical connection coupled between the terminal blades  212 ,  218 . The fuse element assembly  220  includes a fuse element  222 . When subjected to predetermined current conditions, the fuse elements melt in the assembly, disintegrate, or otherwise structurally fail and opens the circuit path through the fuse element between the terminal blades  212 ,  218 . Load side circuitry is therefore electrically isolated from the line side circuitry, via operation of the fuse element(s), to protect load side circuit components and circuitry from damage when electrical fault conditions occur. Additionally, housing  202  includes a first end  230 , an opposing a second end  232 , and an internal bore or passageway between the opposing ends  230 ,  232  that receives and accommodates the fuse element assembly  220 . 
     An arc extinguishing filler medium or material  224  surrounds the fuse element assembly  220 . Electrical fuse  200  further includes at least one reinforcing structure  226  suspended within the filler material  224 . In the present embodiment, reinforcing structure  226  is a plurality of reinforcing rods  228 . Reinforcing rods  228  are positioned on opposing sides of fuse element assembly  220 , and extend along the length of the fuse element assembly  220  from adjacent terminal assembly  204  to adjacent to terminal assembly  206 . Reinforcing rods  228  have a cylindrical shape and are fabricated from a non-organic (i.e., inorganic) material. In an exemplary embodiment, reinforcing rods  228  are fabricated from fiberglass or other suitable materials. 
     Reinforcing rods  228  provide increased structural support and added durability to the filler  224  that surrounds the fuse element assembly  220  in the fuse  200 . Reinforcing rods  228  therefore protect fuse element assembly  220  from damage due to impact or vibration, and the stone sand matrix is accordingly less likely to crack. Additionally, reinforcing rods  228  protect fuse element assembly  220  by protecting it from cracks that the stone sand matrix might experience by ensuring that cracks which may form as the result of impact occur in a location away from fuse element assembly  220 . This ensures that even when subject to severe impact and shock, damage to the filler  224  from cracking in the fuse  200  will be less likely to impact the operation or reliability of the fuse. When subjected to predetermined current conditions, the fuse element(s) melt, disintegrate, or otherwise structurally fail and opens the circuit path through the fuse element(s) between the terminal blades  212 ,  218 . Load side circuitry is therefore electrically isolated from the line side circuitry, via operation of the fuse element(s), to protect load side circuit components and circuitry from damage when electrical fault conditions occur. 
     While exemplary terminal blades  212 ,  218  are shown and described for the fuse  200 , other terminal structures and arrangements may likewise be utilized in further and/or alternative embodiments. For example, knife blade contacts may be provided in lieu of the terminal blades as shown, as well as ferrule terminals or end caps as those in the art would appreciate to provide various different types of termination options. The terminal blades  212 ,  218  may also be arranged in a spaced apart and generally parallel orientation if desired and may project from the housing  202  at different locations than those shown. 
     In various embodiments, the end plates  208 ,  214  may be formed to include the terminal blades  212 ,  218  or the terminal blades  212 ,  218  may be separately provided and attached. The end plates  208 ,  214  may be considered optional in some embodiments and connection between the fuse element assembly  220  and the terminal blades  212 ,  218  may be established in another manner. 
     In another exemplary embodiment, the at least one reinforcing structure  226  also includes a plurality of reinforcing fibers having a high tensile strength. The reinforcing fibers are configured to increase the strength of the stone sand matrix. Additionally, the reinforcing fibers do not include an organic material. In the exemplary embodiment, the reinforcing fibers include an inorganic material. In one embodiment, the reinforcing fibers are fabricated from glass. In another embodiment, the reinforcing fibers are fabricated from fiberglass. In the exemplary embodiment, the reinforcing fibers have varying lengths. In the exemplary embodiment, filler material  224  and the reinforcing fibers are mixed, such that the reinforcing fibers are suspended within filler material  224 . A mixture of the filler material  224  and reinforcing fibers surrounds the fuse element assembly  220 . The mixture of filler material  224  and reinforcing fibers provides increased durability and structural support to fuse element assembly  220  and fuse  200 . The mixture of filler material  224  and reinforcing fibers are mixed with a silica binder material to mechanically bind the mixture to the fuse element assembly  220 , terminal assemblies  204 ,  206  and housing  202  increasing the thermal conduction and structural integrity between these materials. 
     In another exemplary embodiment, the reinforcing structure  226  may also include a thermosetting resin. In the exemplary embodiment, the thermosetting resin does not include an organic material. The thermosetting resin is configured to form molecule chains when cured. In the exemplary embodiment the thermosetting resin is mixed with waterglass and includes melamine formaldehyde. The filler material  224  and thermosetting resin are mixed. A mixture of the filler material  224  and thermosetting resin surrounds the fuse element assembly  220 . The mixture of filler material  224  and thermosetting resin provides increased durability and structural support to fuse element assembly  220  and fuse  200 . The mixture of filler material  224  and thermosetting resin are mixed with a silica binder material to mechanically bind the mixture to the fuse element assembly  220 , terminal assemblies  204 ,  206  and housing  202  increasing the thermal conduction and structural integrity between these materials. 
     The features described above can be used to achieve increased durability and structural integrity in fuses as demonstrated above. In other words, by implementing the features described above, whether separately or in combination, the robustness and durability of a given fuse can be increased at all points in the life cycle of the fuse. 
       FIG. 4  is an end view with parts removed showing an internal construction of the electrical fuse  200 , shown in  FIG. 3 . The housing  202  is fabricated from a non-conductive material known in the art such as glass melamine in one exemplary embodiment. Other known materials suitable for the housing  202  could alternatively be used in other embodiments as desired. Additionally, the housing  202  shown is generally cylindrical or tubular and has a generally circular cross-section along an axis perpendicular to the axial length dimensions. The housing  202  may alternatively be formed in another shape if desired, however, including but not limited to a rectangular shape having four side walls arranged orthogonally to one another, and hence having a square or rectangular-shaped cross section. The housing  202  as shown includes a first end  230 , an opposing a second end  232  (shown in  FIG. 3 ), and an internal bore or passageway between the opposing ends  230 ,  232  that receives and accommodates the fuse element assembly  220  (shown in  FIG. 3 ). In some embodiments the housing  202  may be fabricated from an electrically conductive material if desired, although this would require insulating gaskets and the like to electrically isolate the terminal blades  212 ,  218  (Shown in  FIG. 3 ) from the housing  202 . 
     First and second ends  230 ,  232  include fill holes  234  through which filler material  224  is introduced into fuse  200 . Additionally, reinforcing structures  226 , such as reinforcing rods  228  are introduced into fuse  200  through fill holes  234 . Fill holes  234  are used to fill fuse  200  with filler material  224 , reinforcing structures  226 , and silica binder material. Fill plugs  236  are used to plug fill holes  234  after fuse  200  has been filled with filler material  224 . Reinforcing rods  228  and filler material  224  may be introduced into fuse  200  in any suitable order. For example, reinforcing rods  228  may be inserted into fuse  200  prior to filling fuse  200  with filler material  224 , or alternatively filler material  224  may be used to fill or partially fill fuse  200  prior to reinforcing rods  228  being inserted. 
       FIG. 5  illustrates a flowchart of an exemplary method  300  of manufacturing the electrical fuse  200  described above. 
     The method includes providing the housing at step  302 . The housing provided may correspond to the housing  202  described above. 
     At step  304 , at least one fuse element is provided. The at least one fuse element may include the fuse element assembly  220  described above. Other fuse element assemblies are possible, however, in alternative embodiments. 
     At step  306 , fuse terminals are provided. The fuse terminals may correspond to the terminal blades  212 ,  218  described above. 
     At step  308 , the components provided at steps  302 ,  304  and  306  may be assembled partially or completely as a preparatory step to the remainder of the method  300 . 
     As further preparatory steps, a filler material is provided at step  310 . The filler material may be a quartz sand material as described above. Other filler materials are known, however, and may likewise be utilized. 
     At step  312 , a silicate binder is applied to the filler material provided at step  310 . In one example, the silicate binder may be added to the filler material as a sodium silicate liquid solution. Optionally, the silicate material may be dried at step  314  to remove moisture. The dried silicate material may then be provided at step  316 . 
     At step  318  a plurality of reinforcing rods  228  are provided. The reinforcing rods may be fabricated using fiberglass as described above. Any number of reinforcing rods may be used. 
     At step  320  the plurality of reinforcing rods are inserted into the housing through the fill hole(s)  234  provided in the first and second ends  230 ,  232  such that the reinforcing rods are on opposing sides of the fuse element assembly and extend the length of the fuse element assembly. In another embodiment, however, the reinforcing rods could be located or arranged with respect to the fuse element assembly in another manner. 
     At step  322 , the housing may be filled with the silicate filler material provided at step  316  and loosely compacted in the housing around the fuse element assembly and reinforcing rods. Optionally, the filler is dried at step  324 . The fuse is sealed at step  326  by installing fill plugs  236  to complete the assembly. 
     Optionally, the order of steps  320  and  322  may be switched such that silicate filler is introduced into the housing prior to the insertion of the reinforcing rods. 
     Using method  300 , the thermal conduction bonds are established between the filler particles, the reinforcing rods  228  described above, the fuse element(s) in the housing, and any connecting terminal structure such as terminal assemblies  204 ,  206  described above. The silicate filler material in combination with the reinforcing rods provides an effective heat transfer system that cools the fuse elements in use, while adding tensile strength and structural support to the fuse element and fuse described above. 
     The mixture of filler material particles (quartz sand in this example) and the reinforcing rods  228  suspended within the filler are mechanically bonded together with the silicate binder (sodium silicate in this example), and the silicate binder further mechanically bonds the mixture of filler material particles and the reinforcing rods  228  suspended within the filler to the surfaces of the fuse element assembly. The binder further mechanically bonds the filler material particles and the reinforcing rods  228  suspended within the filler to the surfaces of terminal assemblies  204  and  206 , as well as to the interior surfaces of the housing  202 . Such inter-bonding of the elements is much more effective to structurally support the fuse element assembly and transfer heat than conventionally applied non-silicated filler materials that merely establish point contact when loosely compacted in the housing of a fuse. The increased tensile strength established by the combination of silicated filler particles and reinforcing rods  228  allows the fuse element assembly  220  and fuse  200  to withstand greater impact and shock forces than otherwise would be possible. 
       FIG. 6  illustrates another flowchart of another exemplary method  350  of manufacturing the electrical fuse  200 . The preparatory steps  302 ,  304 ,  306 ,  308  are the same as those described above for the method  300 . 
     At step  352 , a filler material such as quartz sand is provided. 
     At step  354 , reinforcing fibers are provided. The reinforcing fibers may be one of glass or fiberglass as described above. 
     At step  356 , the filler material and reinforcing fibers are mixed. 
     At step  358  the housing is filled with the mixture of filler material and reinforcing fibers, and the mixture is loosely packed around the fuse element(s) in the assembly of step  308 . 
     At step  360  the silicate binder is applied. The silicate binder may be added to the filler and reinforcing fiber mixture after being placed in the housing. This may be accomplished by adding a liquid sodium silicate solution through the fill hole(s)  234  provided in the first and second ends  230 ,  232  as explained above. Steps  358  and  360  may be alternately repeated until the housing is full of the filler and reinforcing fiber mixture and silicate binder in the desired amount and ratios. 
     At step  362 , the filler and reinforcing fiber mixture is dried to complete the mechanical and thermal conduction bonds. The fuse may be sealed at step  364  by installing the fill plugs  236  described above. 
     Using method  350 , the thermal conduction bonds are established between the filler particles, the reinforcing fibers, the fuse element(s) in the housing, and any connecting terminal structure such as terminal assemblies  204 ,  206  described above. The silicate filler material in combination with the reinforcing fibers provides an effective heat transfer system that cools the fuse elements in use, while adding tensile strength and structural support to the fuse element and fuse described above 
     The mixture of filler material particles (quartz sand in this example) and reinforcing fibers are mechanically bonded together with the silicate binder (sodium silicate in this example), and the silicate binder further mechanically bonds the mixture of filler material particles and reinforcing fibers to the surfaces of the fuse element assembly. The binder further mechanically bonds the mixture of filler material particles and reinforcing fibers to the surfaces of terminal assemblies  204 ,  206 , as well as to the interior surfaces of the housing  202 . Such inter-bonding of the elements is much more effective to structurally support the fuse element assembly and transfer heat than conventionally applied non-silicated filler materials that merely establish point contact when loosely compacted in the housing of a fuse. The increased tensile strength established by the combination of silicated filler particles and reinforcing fiber allows the fuse element assembly  220  and fuse  200  to withstand greater impact and shock forces than otherwise would be possible. 
       FIG. 7  illustrates another flowchart of another exemplary method  380  of manufacturing the electrical fuse  200 . The preparatory steps  302 ,  304 ,  306 ,  308  are the same as those described above for the method  300 . 
     At step  382 , a filler material such as quartz sand is provided. 
     At step  384 , a thermosetting resin is provided. The thermosetting resin is configured such that when cured it forms molecule chains of melanine formaldehyde. 
     At step  386 , the filler material and thermosetting resin are mixed. 
     At step  388  the housing is filled with the mixture of filler material and thermosetting resin, and the mixture is loosely packed around the fuse element(s) in the assembly of step  308 . 
     At step  390  the silicate binder is applied. The silicate binder may be added to the filler after being placed in the housing. This may be accomplished by adding a liquid sodium silicate solution through the fill hole(s)  234  provided in the first and second ends  230 ,  232  as explained above. Steps  388  and  390  may be alternately repeated until the housing is full of filler and silicate binder in the desired amount and ratios. 
     At step  392 , the mixture of filler material and thermosetting resin is dried to complete the mechanical and thermal conduction bonds. The fuse may be sealed at step  394  by installing the fill plugs  236  described above. 
     Using method  380 , the thermal conduction bonds are established between the filler particles, the thermosetting resin, the fuse element(s) in the housing, and any connecting terminal structure such as terminal assemblies  204 ,  206  described above. The silicate filler material in combination with the thermosetting resin provides an effective heat transfer system that cools the fuse elements in use, while adding tensile strength and structural support to the fuse element  220  and fuse  200  described above. 
     The mixture of filler material particles (quartz sand in this example) and thermosetting resin are mechanically bonded together with the silicate binder (sodium silicate in this example), and the silicate binder further mechanically bonds the mixture of filler material particles and thermosetting resin to the surfaces of the fuse element assembly. The binder further mechanically bonds the mixture of filler material particles and thermosetting resin to the surfaces of terminal assemblies  204 ,  206 , as well as to the interior surfaces of the housing  202 . Such inter-bonding of the elements is much more effective to structurally support the fuse element assembly and transfer heat than conventionally applied non-silicated filler materials that merely establish point contact when loosely compacted in the housing of a fuse. The increased tensile strength established by the combination of silicated filler particles and thermosetting resin allows the fuse element assembly  220  and fuse  200  to withstand greater impact and shock forces than otherwise would be possible. 
     In combination with the other features described above, the reinforcement of the fuse stone sand matrix strengthens the fuse against impact and shock forces, increasing the robustness of the fuse, allowing the fuse to better perform and display improved temperature rise performance and interruption performance while still capably performing at elevated current and voltages in applications such as those described above. 
     The benefits of the inventive concepts disclosed are now believed to have been amply demonstrated in relation to the exemplary embodiments disclosed. 
     An embodiment of an electrical fuse has been disclosed including: a housing; first and second terminal assemblies coupled to the housing; at least one fuse element assembly extending internally in the housing and coupled between the first and second terminal assemblies; a filler surrounding the at least one fuse element assembly, wherein the filler includes sodium silicate sand; and at least one reinforcing structure suspended within the filler. 
     Optionally, the at least one reinforcing structure does not include an organic material. Optionally, the at least one reinforcing structure may be a reinforcing rod. The reinforcing rod may be fabricated from an inorganic material. Optionally, the reinforcing rod may be fabricated from fiberglass. The reinforcing rod may have a cylindrical shape. The reinforcing rod may extend along the length of the fuse element assembly from adjacent to the first terminal assembly to adjacent to the second terminal assembly. Optionally, the housing may have a cylindrical shape. 
     Optionally, the at least one reinforcing structure may include a plurality of reinforcing fibers having a high tensile strength suspended in the filler. Optionally, reinforcing fibers may include an inorganic material. The reinforcing fibers may be fabricated from glass. Optionally, the reinforcing fibers may be fabricated from fiberglass. The reinforcing fibers may have varying lengths. Optionally, the sodium silicate sand filler and the reinforcing fibers may be mixed and surround the fuse element assembly. Optionally the at least one reinforcing structure may include a thermosetting resin. The thermosetting resin may include an inorganic material. Optionally, the thermosetting resin may be mixed with waterglass to increase tensile strength. The thermosetting resin may include melamine formaldehyde. Optionally, the thermosetting resin may be configured to form molecule chains when cured. Optionally, a mixture of the thermosetting resin and the sodium silicate sand filler may be cured and surround the fuse element assembly. 
     This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.