Patent Publication Number: US-9887055-B2

Title: Mechanical fuse device

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Application Ser. No. 62/163,257 to MURRAY S. McTIGUE, et al., entitled MECHANICAL FUSE DEVICE, filed on May 18, 2015, which is hereby incorporated herein in its entirety by reference. 
    
    
     BACKGROUND 
     Field of the Invention 
     Described herein are devices relating generally to fuses for use in electrical devices and systems, and specifically to fuses comprising mechanical and/or hermetically sealed features. 
     Description of the Related Art 
     In the field of electronics and electrical engineering, various devices can be employed in order to provide overcurrent protection, which can thus prevent short circuits, overloading, and permanent damage to an electrical system or a connected electrical device. Two of these devices include fuses and circuit breakers. A conventional fuse is a type of low resistance resistor that acts as a sacrificial device. Typical fuses comprise a metal wire or strip that melts when too much current flows through it, interrupting the circuit that it connects. Conventional fuses are thus thermal activating solid-state devices. 
     As society advances, various innovations to electrical systems and electronic devices are becoming increasingly common. An example of such innovations include recent advances in electrical automobiles, which may one day become the energy-efficient standard and replace traditional petroleum-powered vehicles. In such expensive and routinely used electrical devices, overcurrent protection is particularly applicable to prevent device malfunction and permanent damage to the devices. Furthermore, overcurrent protection can prevent safety hazards, such as electrical fires. 
     Some problems with the utilization of traditional fuses in many modern applications, such as with electrical automobiles, is that many conventional solid-state fuses have difficulty efficiently operating at high currents. Utilizing the electrical automobile example, fuses that will trigger at lower currents will interrupt device function at a much lower current than is actually hazardous, resulting in the automobile becoming unnecessarily powered down. Furthermore, once a conventional fuse is triggered, it is sacrificed and must be completely replaced. 
     SUMMARY 
     Described herein are efficient mechanical fuse devices capable of operating at high current. These fuse devices are configured such that they have a first non-triggered or “set” position, which causes the device to allow current to flow through it and maintain a circuit connection, and a second trigged position, which causes the device to not allow current to flow through it. These mechanical fuse devices can operate at higher currents than conventional solid-state fuse devices and in some embodiments, the fuse devices can be “reset” such that the devices can be reusable. 
     In some embodiments, the fuse devices comprise electromagnetic components. In some embodiments, the fuse devices are configured in a set orientation by one or more mechanical components and are triggered when a desired current level causes an electromagnetic field to generate a force sufficient to overcome the force of the mechanical components. In some embodiments, one or more components of the fuse devices can also be housed within a hermetically sealed housing. 
     In one embodiment, a fuse device comprises a body comprising at least one body portion and internal components within the fuse device configured to change the state of the fuse device between a set state allowing current flow through the device and a triggered state which interrupts current flow through the device. At least some of the internal components are at least partially surrounded by the body portion. The fuse device also comprises contact structures electrically connected to the internal components for connection to external circuitry. The fuse device is configured such that when a threshold current level passes through the internal components, the body changes configuration in response to a generated electromagnetic field, which causes the device to transition to the triggered state. 
     In another embodiment, a fuse device, comprises a body comprising at least one body portion and internal components, wherein the internal components comprise: fixed contacts electrically isolated from one another, with the fixed contacts at least partially surrounded by at least one body portion, one or more movable contact, allowing current flow between the fixed contacts when the movable contact is contacting the fixed contacts, an internal pin component connected to the movable contact, the pin being biased toward a position that moves the movable contact out of contact with the fixed contacts, and a pin retention structure configured to hold the internal pin component in place such that the movable contact is contacting the fixed contacts. The fuse device also comprises contact structures electrically connected to the internal components for connection to external circuitry. The fuse device is configured such that when a threshold current level passes through the internal components, the pin retention structure changes configuration in response to a generated electromagnetic field, which causes the internal pin component to move according to its bias. 
     In yet another embodiment, a fuse device, comprises a body comprising at least one body portion, movable and fixed contacts contacts configured to change the state of said fuse device between a set state allowing current flow through the device and a triggered state which interrupts current flow through the device, one or more secondary contact elements electrically contacting the fixed contacts and contact structures electrically connected to said fixed contacts for connection to external circuitry. The fuse device is configured such that when a threshold current level passes through the contact structures and the movable and fixed contacts, the body changes configuration in response to a generated electromagnetic field, which causes the device to transition to the triggered state. The fuse device is also configured such that the secondary contact element is configured to degrade and no longer contact said fixed contacts when the movable contact is not contacting the fixed contacts and current is flowing through the secondary contact elements. 
     These and other further features and advantages of the invention would be apparent to those skilled in the art from the following detailed description, taken together with the accompanying drawings, wherein like numerals designate corresponding parts in the figures, in which: 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a front view of an embodiment of a fuse device incorporating features of the present invention; 
         FIG. 2  is a back view of the embodiment of the fuse device of  FIG. 1 ; 
         FIG. 3  is a top view of the embodiment of the fuse device of  FIG. 1 ; 
         FIG. 4  is a bottom view of the embodiment of the fuse device of  FIG. 1 ; 
         FIG. 5  is a front view of the embodiment of the fuse device of  FIG. 1 , shown with the compartment endcap portion removed; 
         FIG. 6  is a top sectional view of the embodiment of the fuse device of  FIG. 1 , shown further housed within a housing structure; 
         FIG. 7  is a front sectional view of the embodiment of the fuse device of  FIG. 6 ; 
         FIG. 8  is a left-side sectional view of the embodiment of the fuse device of  FIG. 6 ; 
         FIG. 9  is a front perspective view of the embodiment of the fuse device of  FIG. 6 ; 
         FIG. 10  is a top sectional view of another embodiment of a fuse device incorporating features of the present invention, shown in a non-triggered position and shown further housed within a housing structure; 
         FIG. 11  is a top sectional view of the embodiment of the fuse device of  FIG. 10 , shown in a triggered position; 
         FIG. 12  is a right-side sectional view of the embodiment the fuse device of  FIG. 10 , shown in a non-triggered position; 
         FIG. 13  is a right-side sectional view of the embodiment the fuse device of  FIG. 10 , shown in a triggered position; 
         FIG. 14  is an exploded view of the embodiment of the fuse device of  FIG. 10 ; and 
         FIG. 15  is a partial exploded view of the embodiment of the fuse device of  FIG. 10 . 
     
    
    
     DETAILED DESCRIPTION 
     The present disclosure will now set forth detailed descriptions of various embodiments. These embodiments set forth fuse devices comprising mechanical components that are configured such that the fuse devices have triggered states (in which a circuit or other electrical flow is interrupted and the fuse is “tripped”) and non-triggered states (in which a circuit or other electrical flow is not interrupted and the fuse is “set”). In some embodiments, these mechanical components include a pin structure that is configured with one or more contacts to maintain or interrupt a circuit. In some embodiments, this pin structure is biased toward a triggered position that would break a circuit connected to the fuse device and is maintained against its bias by a mechanical pin retention structure. In some embodiments, one or more of the components of these devices are housed within a hermetically sealed portion. In some embodiments, the devices comprise a metal body at least partially surrounding a conductor. 
     In some embodiments, the devices are configured such that when a sufficient level of current flows through the device, the body and/or the mechanical pin retention structure will change configuration and cause internal components within the body to interrupt current flow through the device. In some embodiments, this configuration change causes a movable contact to move out of contact with one or more fixed contacts, interrupting current flow. In some embodiments, this configuration change causes release of the pin structure mentioned above, such that the pin moves in accordance to its bias and will break a connected circuit or otherwise interrupt electrical flow. 
     In some embodiments, this desired breakage current level is translated into force by an electromagnetic field, such that the set mechanical force holding the pin against its bias can be overcome by the force of a corresponding electromagnetic field generated by the required current level. The required values of a fuse for a certain current level, for example, a fuse that will interrupt electrical flow at a current of 3,000 Amps, can be calculated such that the above-described configuration change of the body will be caused by the electromagnetic field generated by the desired current level and therefore will interrupt electrical flow through the fuse device. 
     Throughout this description, the preferred embodiment and examples illustrated should be considered as exemplars, rather than as limitations on the present invention. As used herein, the term “invention,” “device,” “present invention,” or “present device” refers to any one of the embodiments of the invention described herein, and any equivalents. Furthermore, reference to various feature(s) of the “invention,” “device,” “present invention,” or “present device” throughout this document does not mean that all claimed embodiments or methods must include the referenced feature(s). 
     It is also understood that when an element or feature is referred to as being “on” or “adjacent” to another element or feature, it can be directly on or adjacent the other element or feature or intervening elements or features may also be present. It is also understood that when an element is referred to as being “attached,” “connected” or “coupled” to another element, it can be directly attached, connected or coupled to the other element or intervening elements may be present. In contrast, when an element is referred to as being “directly attached,” “directly connected” or “directly coupled” to another element, there are no intervening elements present. 
     Relative terms, such as “outer,” “above,” “lower,” “below,” “horizontal,” “vertical” and similar terms, may be used herein to describe a relationship of one feature to another. It is understood that these terms are intended to encompass different orientations in addition to the orientation depicted in the figures. 
     Although the terms first, second, etc. may be used herein to describe various elements or components, these elements or components should not be limited by these terms. These terms are only used to distinguish one element or component from another element or component. Thus, a first element or component discussed below could be termed a second element or component without departing from the teachings of the present invention. As used herein, the term “and/or” includes any and all combinations of one or more of the associated list items. 
     The terminology used herein is for describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises,” “comprising,” when used herein, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. 
     Embodiments of the invention are described herein with reference to different views and illustrations that are schematic illustrations of idealized embodiments of the invention. As such, variations from the shapes of the illustrations as a result, for example, of manufacturing techniques and/or tolerances are expected. Embodiments of the invention should not be construed as limited to the particular shapes of the regions illustrated herein, but are to include deviations in shapes that result, for example, from manufacturing. 
     It is understood that when a first element is referred to as being “between,” “sandwiched,” or “sandwiched between,” two or more other elements, the first element can be directly between the two or more other elements or intervening elements may also be present between the two or more other elements. For example, if a first element is “between” or “sandwiched between” a second and third element, the first element can be directly between the second and third elements with no intervening elements or the first element can be adjacent to one or more additional elements with the first element and these additional elements all between the second and third elements. 
       FIGS. 1-5  show external views of an example embodiment of a fuse device  100  and therefore mostly illustrate the external components of the fuse device  100 . The internal components are best viewed in  FIGS. 6-8 .  FIG. 1  shows the fuse device  100  comprising a body  102 , which comprises at least one body portion, and contact structures  104 ,  106  (two shown) which are configured to electrically connect the fuse device to external circuitry, for example, an electrical system or device. The body  102  can comprise any suitable material that can support the structure and function of the fuse device as disclosed herein, with a preferred material being a material that can interact with an electromagnetic field generated by current flowing through the device, for example, a metal or metallic material. In some embodiments, the body  102  comprises iron. In some embodiments, the body at least partially surrounds the various internal components. 
     The contact structures  104 ,  106  are configured such that the various internal components of the fuse device  100  that are housed within the body  102  or another portion of the fuse device  100  (such as a compartment as discussed in further detail below) can electrically communicate with an external electrical system or device, such that the fuse device  100  can function as an electrical fuse. The contact structures  104 ,  106  can comprise any suitable conductive material for providing electrical contact to the internal components of the fuse device, for example, various metals and metallic materials or any electrical contact material and/or structure that is known in the art. 
     Some of the internal components of the fuse device  100  can be housed in a compartment  108  of the fuse device. The compartment  108  can comprise materials similar to those listed herein with regard to the body  102  as well as any suitable material for providing structural support for the fuse device  100  and protection for the internal components. In some embodiments, the compartment  108  comprises a metal or metallic substance. In some embodiments, the compartment  108  comprises a durable plastic or polymer. In the embodiment shown in  FIG. 1 , the compartment  108  comprises a plastic material and the body  102  is metallic. 
     The compartment  108  can comprise an endcap  110  that can be removable and replaceable. In the embodiment shown, the endcap  110  is a front endcap. In some embodiments, the endcap  110  is configured to provide mechanical resistance to a spring force of the internal components of the device, as will be discussed in more detail further below. The compartment  108  can be configured such that the internal space of the compartment, which can house some of the various internal components of the device, is hermetically sealed. This hermetically sealed configuration can help mitigate or prevent electrical arcing between adjacent conductive elements, and in some embodiments, helps provide electrical isolation between contacts separated by a space. In some embodiments, the compartment  108  can be under vacuum conditions. 
     In some embodiments, the compartment  108  can be at least partially filled with an electronegative gas, for example, sulfur hexafluoride or mixture of nitrogen and sulfur hexafluoride. In some embodiments, the compartment  108  comprises a material having low or substantially no permeability to a gas injected into the housing. In some embodiments, the body itself comprising the hermetically sealed compartment  108 , with the internal components therein. In some embodiments, the compartment can comprise various gases, liquids or solids configured to increase performance of the device. 
     As mentioned previously herein, fuse devices incorporating features of the present invention can comprise mechanical features for setting and triggering the fuse device. In the embodiment shown in  FIG. 1 , the fuse device  100  is shown in its non-triggered or “set” mechanical orientation. The various non-triggered and triggered orientations will become more apparent as the various drawings are explained in greater detail. 
     The fuse device  100  can be held in the set orientation by various structures, for example, mechanical structures such as a mechanical resistance structure  112 . In the embodiment shown, the mechanical resistance structure  112  is a mechanical arm that is configured to hold the device in the set position until the device is triggered. In the embodiment shown, the mechanical arm  112  is connected to a position bolt  114 , which is in turn connected to a part of the body  102 . In some embodiments, wherein the fuse device  100  is further housed in a housing, for example, a hermetically sealed housing, the housing can function as the mechanical resistance structure. In some embodiments, the mechanical resistance  112  structure is not utilized and the body is configured to be held in a set position by other means. 
     The fuse device  100  can be configured such that triggering the fuse device  100  by reaching a pre-determined threshold current level will generate an electromagnetic field sufficient to overcome the force provided by the mechanical resistance structure  112  (or the configuration of the body or another mechanical structure holding the device in a non-triggered position) and trigger the device. The body  102 , the mechanical resistance structure  112  and/or the various other components of the fuse device  100  can be configured such that when the current through the device reaches a certain pre-determined current level, for example, 2,000 amps, it will generate a sufficient magnetic field to cause the fuse device  100  to overcome the force of the mechanical resistance structure  112  and trigger the device. 
     Some various structures that can maintain the fuse device  100  in its set position are better shown in  FIG. 2 .  FIG. 2  shows the fuse device  100 , the body  102 , the contact structures  104 ,  106 , mechanical resistance structure  112  and the position bolt  114 .  FIG. 2  shows that in its set orientation, the fuse device  100  also comprises a mechanical position gap  150 , that at least partially separates a first body portion  152  from a second body portion  154 . The mechanical position gap  150  can be maintained by force applied by the mechanical resistance structure  112 , either alone or in conjunction with one or more structures. In some embodiments, a pin retention structure  156  can be utilized to further hold an internal pin component  158  in place, while the device is in its set position. As will be discussed in more detail further below, the pin  158  can be configured with an internal spring structure such that it is under a spring force which biases the pin  158  toward a position where the pin  158  can interact with other internal components and break the circuit. The pin retention structure  156  can be any component, either alone or in conjunction with the mechanical resistance structure  112  that is configured to resist the spring force and hold the pin  158  in place so that the fuse device  100  is in its set position. 
     It is understood that while the present disclosure specifically recites electromagnetic embodiments configured to overcome pre-set mechanical forces, other configurations generating a force corresponding to a pre-determined current, such that the force can overcome a pre-determined mechanical force is within the scope of the present disclosure. 
     Once a sufficient electromagnetic force is generated due to the pre-determined current value being reached, the fuse device transitions from its set position, wherein the fuse device allows electrical flow through it, to the triggered position, wherein the electrical device breaks the connected circuit. In the embodiment shown, this transition between positions occurs when the generated electromagnetic field causes the first body portion  152  to become drawn toward the second body portion  154 , for example, to a degree that overcomes the force applied by the mechanical resistance structure  112  and/or the pin retention structure  156 . This at least partially reduces (and can totally eliminate) the mechanical position gap  150  and therefore mechanically alters or otherwise changes the configuration of the pin retention structure  156 . This causes the pin  158  to no longer be restrained, which causes the pin  158  to change orientation within the fuse device  100  and break the circuit. 
     To help further conceptualize the external components of the fuse device  100 ,  FIGS. 3-4  show a top and bottom view of the fuse device  100  respectively.  FIG. 3  shows the fuse device  100 , the body  102 , the contact structures  104 ,  106 , the compartment  108 , the mechanical resistance structure  112 , the position bolt  114 , the pin retention structure  156  and the pin  158 .  FIG. 3  shows an example orientation of a way in which the mechanical resistance structure can be connected to the position bolt  114 , for example, wrapped around it, such that the first body portion  152  is separated by the second body portion such that mechanical position gap is created. 
       FIG. 4  shows a bottom view of the fuse device  100 , including the body  102 , the contact structures  104 ,  106  and the compartment  108 . As shown in  FIG. 4 , the bottom portion of the compartment  108  can be solid to further protect the components internal to the compartment  108 . 
     Transitioning now into further discussion of the internal components,  FIG. 5  shows a front view of the fuse device  100 , however this time with the endcap removed such that some of the internal components are exposed. As in  FIG. 1 ,  FIG. 5  shows the fuse device  100 , the body  102 , the contact structures  104 ,  106 , the compartment  108 , the mechanical resistance structure  112  and the position bolt  114 .  FIG. 5  further shows an internal portion of the pin  158 , one or more movable contacts  200  (one shown) and one or more fixed contacts  202 ,  204  (two shown). 
     The fixed contacts  202 ,  204  can comprise similar materials to the contact structures  104 ,  106  and can be configured such that they are in contact with their respective contact structures  104 ,  106 , such that an electrical signal running through the first contact structure  104  will be conducted through the first fixed contact  202  and an electrical signal running through the second contact structure  106  will be conducted through the second fixed contact  204 . The first and second fixed contacts  202 ,  204  can be configured such that there is electrical isolation between them, for example, the contacts  202 ,  204  can be separated by an electrically insulating material or simply by an electrically isolating spatial gap. In some embodiments, wherein the housing  108  is hermetically sealed, under vacuum conditions and/or filled with an electronegative gas, potential electrical arcing between the fixed contacts  202 ,  204  can be further reduced or prevented, resulting in further electrical isolation. In some embodiments, the fixed contacts  202 ,  204  are separate structures in electrical contact with their respective contact structures  104 ,  106 . In other embodiments, the fixed contacts  202 ,  204  are integrated with or part of the contact structures  104 ,  106 . 
     When the fuse device  100  is in its set position, the movable contact  200  can be connected to both of the electrically isolated fixed contacts  202 ,  204 , such that the movable contact  200  functions as a bridge allowing an electrical signal to flow through the device, for example, from the first contact structure  104 , to the first fixed contact  202 , to the movable contact  200 , to the second fixed contact  204 , to the second contact structure  106  and vice versa. Therefore, the fuse device  100  can be connected to an electrical circuit, system or device and complete a circuit while in its set position and when the movable contact is in electrical contact with the fixed contacts. 
     As shown in  FIG. 5 , the pin  158  can be configured with the movable contact  200 , such that a change in orientation of the pin  158  can cause the movable contact  200  to no longer be in contact with the fixed contacts  202 ,  204 . This would therefore break a connected circuit due to the electrical isolation between the fixed contacts  202 ,  204  without the movable contact  202  to bridge the isolation gap. 
     The internal components of the fuse device  100  are further shown in the sectional views of  FIGS. 6-8 .  FIG. 6  shows a top sectional view of the fuse device  100 .  FIG. 6  shows the body  102 , the contact structures  104 ,  106 , the compartment  108 , the compartment endcap  110 , the pin retention structure  156 , the pin  158 , the movable contact  200  and the fixed contacts  202 ,  204 .  FIG. 6  further shows the fuse device  100  housed within a housing  256 , which can provide protection, structural support, and/or a hermetically sealed environment for the fuse device  100 .  FIG. 6  further shows one or more springs  250 ,  252  (two shown) which are configured to bias the pin  158  toward the compartment endcap  110 . Since the movable contact  200  is connected to the pin  158 , if the pin  158  were to move according to the bias provided to it by the springs  250 ,  252 , the movable contact  200  would also move and lose contact with the fixed contacts  202 ,  204 , causing the electrical connection to be broken. 
     In the embodiment shown, the primary component holding the pin  158  in place against its bias is the pin retention structure  156 . When sufficient electromagnetic force is generated, for example, sufficient force to cause the first and second portions of the body to come together as set forth above, the pin retention structure  156  can be broken or displaced, releasing the pin  158  and allowing it to move in accordance with the bias provided by the springs  250 ,  252 . This typically results in the pin  158  causing the endcap  110  to be ejected and potentially the pin  158  leaving the compartment entirely. This likewise causes the movable contact  200  to no longer be in electrical communication with the fixed contacts  202 ,  204 , thus breaking the electrical connection. 
     A front sectional view of the fuse device  100  is shown in  FIG. 7 .  FIG. 7  shows the body  102 , the contact structures  104 ,  106 , the compartment  108 , the position bolt  114 , the pin  158 , the movable contact  200 , the fixed contacts  202 ,  204  and the housing  256 . This front sectional view further shows the position of the pin  158  in relation to the movable contacts  200 . 
     The sectional view of  FIG. 8  shows the interaction of the various internal and external components in transitioning the fuse device  100  from a set position to a triggered position.  FIG. 8  shows the body  102  (comprising the first body portion  152  and the second body portion  154 ), the compartment  108 , the compartment endcap  110 , the position bolt  114 , the mechanical position gap  150 , the pin retention structure  156 , the pin  158 , the movable contact  200 , the first fixed contact  202  the springs  250 ,  252  and the housing  256 . 
       FIG. 8  shows the pin  158  held in position by the pin retention structure  154 . The pin  158  is positioned such that the springs  250 ,  252  are compressed and the spring force biases the pin  158  toward the compartment endcap  110 . The movable contact  200  is configured with the pin  158  such that should the pin  158  move according to its bias, the movable contact will move with the pin and break contact with the fixed contacts. This configuration is one example set position of the fuse device  100 . 
     When a sufficient electric current runs through the device  100 , an electromagnetic field sufficient to overcome preset mechanical forces keeping the first body portion  152  separated from the second body portion  154  is generated. This in turn disrupts the position of the pin retention structure  154  and allows the pin  158  to move in accordance with its bias and cause the movable contact  200  to break contact with the fixed contacts. As mentioned previously, this will typically result in the compartment endcap  110  being ejected from the compartment  108 . The surrounding housing  256  can also serve the purpose of controlling the extent to which the endcap  110  ejects. This prevents an ejected endcap from potentially interfering with a device or electrical system connected to the fuse device  100 . 
     In some embodiments, the fuse device  100  can be resettable and thus can be used more than once, unlike conventional fuses. After the pin  158  and/or the endcap  110  has been ejected, these structures can be replaced and repositioned into the set position. Alternatively, a replacement pin  158  and endcap  110  can be integrated with the fuse device  100 . This allows for the fuse device  100  to be utilized multiple times, without the need to be completely replaced. 
     An external perspective view of the fuse device sealed within the housing  256  is shown in  FIG. 9  (the fuse device being internal to the housing and thus not shown).  FIG. 9  further shows that the housing  256  can comprise one or more housing contact structures  300  (one shown, however, the embodiment shown comprises a second housing contact structure on the other side not visible according to the viewing angle of  FIG. 9 ). The contact structures  300  can be configured to allow for electrical contact of the corresponding contact structures of the fuse device, without compromising the hermetic seal on the housing  256 . In other embodiments, the contact structures of the fuse device itself can protrude from the housing, while still maintaining a hermetic seal. 
     The housing and/or the compartment  108  can be hermetically sealed utilizing any known means of generating hermetically sealed electrical devices. Some examples of hermetically sealed devices include those set forth in U.S. Pat. Nos. 7,321,281, 7,944,333, 8,446,240 and 9,013,254, all of which are assigned to Gigavac, Inc., the assignee of the present application, and all of which are hereby incorporated in their entirety by reference. 
     In some alternate embodiments, the mechanical resistance structure can be configured with the compartment, such that movement of the mechanical resistance structure causes movement of the compartment (or the endcap) which can trigger a corresponding change to the internal components and break the circuit. For example, the mechanical resistance structure can be configured such that a sufficient force will cause the position bolt to pull the mechanical resistance structure in a direction that causes the endcap to be removed. In this embodiment, the endcap can be configured such that it is primarily holding back the spring force biasing the pin toward a triggered state, rather than the pin retention structure performing this function. When the endcap is removed, the pin will move toward its bias and break the circuit. 
     Even further designs and further features can be utilized with fuse devices incorporating features of the present invention.  FIG. 10  shows a fuse device  500  in a set position (allowing electrical flow), which can comprise features similar to the fuse device  100  shown in  FIG. 1  above with some features configured differently. For example,  FIG. 10  shows that the fuse device  500  can comprise one or more first body portions  501  (two shown), which can at least partially surround the fixed contacts, one or more fixed contacts  502 ,  504  (similar to the fixed contacts  204 ,  206  above), one or more movable contacts  506  (one shown; similar to the movable contact  200  above), a pin  508  (similar to the pin  158  above), a pin retention structure  510  (similar to the pin retention structure  156  above), one or more springs  512 ,  514  (similar to the springs  250 ,  252  above), a compartment  516  (similar to the compartment  108  above), a housing  518  (similar to the housing  256  above), and one or more housing contact structures  520 ,  522  (similar to the housing contact structures  300  above). 
     As with the embodiment of  FIG. 1  above, the housing  518  and/or the compartment  516  in  FIG. 10  can be hermetically sealed and can comprise features to facilitate hermetic sealing of the housing. In some embodiments, the housing comprises a lid portion  524 , which can be sealed to the housing  518  through a sealing material  526 , such as an epoxy, therefore forming an airtight seal. A tube  528  can be included in the fuse device to allow for the creation of vacuum conditions and/or for the introduction of one or more electronegative gases as described herein. The fuse device  500  can also be hermetically sealed utilizing any known means of generating hermetically sealed electrical devices. As previously mentioned herein, some examples of hermetically sealed devices include those set forth in U.S. Pat. Nos. 7,321,281, 7,944,333, 8,446,240 and 9,013,254, all of which are assigned to Gigavac, Inc., the assignee of the present application, and all of which are hereby incorporated in their entirety by reference. 
     Some differences between the embodiment shown in  FIG. 10  and the embodiment of  FIG. 1  include that instead of a larger body portion surrounding most of the device components, the first body portions  501  (two shown) are magnetic circuits surrounding only a portion of the fixed contacts  502 ,  504 . The first body portions  501  are configured to interact with one or more second body portions (two in this embodiment) which are shown in  FIGS. 12-15  and which will be discussed in further detail below. Like with the embodiment in  FIG. 1  above, when the flow of current through the device  500  reaches a desired level, a magnetic field will be generated causing the first body portion  501  to become drawn to a second body portion, causing a change in configuration of the body and a resulting change in configuration of the pin retention structure  510 , resulting in movement of the pin  508  and therefore the movable contact  506  away from the fixed contacts  502 ,  504 . 
     Some more additional features included in the fuse device  500  include one or more arc magnets  602 , one or more armature springs  604 , a pin striking plate  606 , and one or more secondary contact elements  608 . It is understood that these additional features set forth in  FIG. 10  can be incorporated into any of embodiments incorporating features of the present invention, including the embodiment of  FIG. 1 . The arc magnets  602  are configured to further control the flow of electricity through the device to prevent and/or to mitigate electrical arcing and/or to change or otherwise control the resulting magnetic field caused by electricity flowing through the one or more fixed contacts  502 ,  504  and the movable contact  506 . This can allow for fine-tuning of the force generated by the magnetic field and can assist with more efficient triggering and setting of the fuse device  500 . 
     The armature springs  604  can be configured to maintain a space between different portions of the housing  518 , for example, maintaining a mechanical position gap as described in the embodiment of  FIG. 1  above. In some embodiments, the armature springs  604  can provide a bias that can partially resist the pull of a generated magnetic field, for example, functioning as a mechanical resistance structure for the electromagnetic field to overcome as discussed above. The pin striking plate  606 , functions to prevent the pin  508  from over-travelling or exiting the fuse device  500  when the fuse device  500  is triggered. This can make resetting of the fuse device  500  easier as the pin  508  is not rapidly ejected over a significant distance when the device is triggered. 
     Another significant additional feature set forth in the embodiment of  FIG. 10  is the one or more secondary contact elements  608 . While various positioning configurations of the secondary contact element are possible, in the embodiment shown in  FIG. 10 , there is a single secondary contact element  608 , which loops around the top portion of the fuse device  500  and makes contact with the first and second fixed contacts  502 ,  504  (this is shown more clearly in  FIGS. 14-15 ). The secondary contact element  208  can comprise various structures that can bridge electrical isolation between the first and second fixed contacts  502 ,  504  to allow at least some electricity to flow through the device. While the embodiments described herein set forth secondary contact elements contacting the fixed contacts, it is understood that in some embodiments incorporating features of the present invention, the secondary contact elements can contact the movable contacts. 
     In some embodiments, the secondary contact element  608  is configured to degrade or “burn away” in response to a predetermined current threshold or as a result of bearing the current between the fixed contacts when the movable contact is no longer in contact with the fixed contacts. As the secondary contact element  608  is completing the circuit for electrical flow from the first fixed contact  502  to the second fixed contact  504 , when the secondary contact element  608  degrades such that it is no longer contacting the fixed contacts  502 ,  504 , the flow of electricity through the fuse device  500  is interrupted. The secondary contact element  608  can comprise any suitable high-resistance conductor, for example copper, nichrome, of alloys of nickel, chromium, iron, copper, and/or other elements. In some embodiments, the secondary contact element  608  can comprise a wire-structure. In some embodiments, the secondary contact comprises nichrome wire. 
     When used in conjunction with the movable contact  506 , the secondary contact element  608  serves to prevent or mitigate electrical arcing in smaller fuse devices. For example, the fuse device  500  can be configured such that when a first current threshold is reached, the movable contact  506  is forced away from the fixed contacts  502 ,  504 . As this change is sudden, electrical arcing between the contacts can occur. In order to stagger this change or make this change more gradual, the secondary contact element  608  can be used and can allow some electrical flow to continue between the fixed contacts  502 ,  504  in absence of the movable contact  506  contacting the fixed contacts  502 ,  504 . As the secondary contact has a high resistivity, the current through the fuse device is reduced. The secondary contact element  608  can then start to degrade to continue the complete interruption of the electrical flow through the fuse device  500 , which will occur after the secondary contact element has degraded to the point where it no longer contacts the fixed contacts  502 ,  504 . As the electricity can travel through the secondary contact element  608  for an interval of time before the secondary contact element  608  degrades, electrical arcing caused by the sudden interruption of the electrical flow through the device  500  is prevented or mitigated due to the additional electrical pathway provided by the secondary contact element. 
     While the embodiment of  FIG. 10  discloses utilizing the secondary contact element  608  in addition to the movable contact  506 , it is understood that in some embodiments, an element such as a wire-structure configured to degrade upon a certain current threshold being reached can be used in lieu of the movable contact. In these embodiments, the secondary contact element  608  actually functions as the primary structure to interrupt the flow of electricity through the fuse device. 
       FIG. 10  shows the fuse device  500  in a set or non-triggered state, with the pin  508  held in place by the pin retention structure  510  and the movable contact  506  physically contacting the first and second fixed contacts  502 ,  504 . This allows electricity to flow through the fuse device  500 . The fuse device  500  in its triggered or interrupted state is shown in  FIG. 11 , which shows, the one or more first body portions  501 , the one or more fixed contacts  502 ,  504 , the one or more movable contacts  506 , the pin  508 , the one or more springs  512 ,  514 , the compartment  516 , the housing  518 , the one or more housing contact structures  520 ,  522 , the lid portion  524 , sealing material  526 , the tube  528 , the one or more arc magnets  602 , the one or more armature springs  604 , the pin striking plate  606 , and the one or more secondary contact elements  608 .  FIG. 11  shows the pin  508  unlatched from the pin retention structure and contacting the pin striking plate  606 , which limits its movement as discussed above. 
     The body configuration of the embodiment of  FIG. 10 , and how it differs from the embodiment of  FIG. 1 , can be clearly seen in  FIG. 12 , which shows the fuse device  500  in a non-triggered position, showing one of the first body portions  501 , the second fixed contact  504 , the pin retention structure  510 , the compartment  516 , the housing  518 , the lid portion  524 , sealing material  526 , the tube  528 , and one of the second body portions  702 .  FIG. 12  further shows a mechanical position gap  704  (similar to the mechanical position gap  150  in  FIG. 2  above), located between the first body portion  501  and the second body portion  702 . 
     In the embodiment shown in  FIG. 12 , the first body portion  501  and the second body portion  702  comprise magnetic circuits, for example, a conductive metal such as iron around a conductive element, although in some embodiments, these body portions  501 ,  702  can comprise other materials as set forth herein. As described in the embodiment of  FIG. 1  above, when a threshold current flows through the device, a magnetic field is generated that is strong enough to overcome a mechanical force, for example, a force inherent to the body or a force generated by the armature springs, causing the first body portion  501  and the second body portion  702  to be drawn together, eliminating or shortening the mechanical position gap  704 . This in turn causes the pin retention structure  510  to be displaced, which causes the pin and movable contact to move and interrupt the flow of electricity through the device. The fuse device  500  is shown in a non-triggered position in  FIG. 12 . 
     The fuse device  500  is shown in a triggered position in  FIG. 13 , which shows one of the first body portions  501 , the second fixed contact  504 , the pin retention structure  510 , the compartment  516 , the housing  518 , the lid portion  524 , sealing material  526 , the tube  528 , and one of the second body portions  702 . As shown in  FIG. 13 , when the device  500  is triggered, the mechanical position gap is eliminated, which changes the configuration of the pin retention structure  510 . 
     An overview of the position of the functional elements  800  of the fuse device  500  is shown in  FIG. 14  in an exploded view, which shows the fuse device  500  comprising the housing  518 , which comprises a lower housing portion  802  and an upper housing portion  804 , the first and second housing contact structures  520 ,  522 , and the tube  528 . As can be seen in  FIG. 14  the functional elements, which include features such as portions of the body and the various contact elements, can be contained in a housing structure, which can be hermetically sealed as set forth above. 
     The functional elements  800  described above are shown in more detail in  FIG. 15 , which shows, the one or more first body portions  501  (two shown), the one or more fixed contacts  502 ,  504 , the one or more movable contacts  506 , the pin  508 , the pin retention structure  510 , the one or more springs  512 ,  514 , the compartment  516  (which comprises an inner housing  900 , a secondary contact element chamber cover  902 , the lid portion  524 , a housing mount  904  and an endcap  906 ), the one or more arc magnets  602 , the one or more armature springs  604 , the one or more secondary contact elements  608  and the one or more second body portions  702  two shown). 
     As the the first body portion  501  and the second body portion  702  are present in select areas of the device, rather than a body portion surrounding the majority of the device as with the embodiment of  FIG. 1 , large portions of the device can be manufactured with lightweight and economical materials such as various plastics, resins and non-metals. Also in contrast to the embodiment of  FIG. 1 , wherein the body  102  substantially surrounds the compartment  108 , the embodiment of  FIGS. 10-15  comprises a compartment  516  that substantially surrounds the first body portion  501  and the second body portion  702 . As shown in  FIG. 15 , the first body portions  501  are configured to at least partially surround the fixed contacts  502 ,  504 , and the second body portions  702  can be mounted to a portion of the compartment  516 . 
     The secondary contact element  608  can be positioned in any suitable configuration that allows contact with the fixed contacts  502 ,  504 . In some embodiments, the secondary contact element can be mostly contained in a separate portion of the compartment  516 , for example, a portion of the inner housing  900  that is partially separated from the other internal components, such as the movable and fixed contacts. This separate portion of the compartment  516  can be at least partially enclosed within the inner housing  900  by the secondary contact element chamber cover  902 . Portions of the secondary contact element  608  can be configured to pass into other areas of the inner housing  900  and to make contact with the fixed contacts as described herein. 
     Although the present invention has been described in detail with reference to certain preferred configurations thereof, other versions are possible. Embodiments of the present invention can comprise any combination of compatible features shown in the various figures, and these embodiments should not be limited to those expressly illustrated and discussed. Therefore, the spirit and scope of the invention should not be limited to the versions described above. 
     The foregoing is intended to cover all modifications and alternative constructions falling within the spirit and scope of the invention as expressed in the appended claims, wherein no portion of the disclosure is intended, expressly or implicitly, to be dedicated to the public domain if not set forth in any claims.