Patent Application
20180138003
Embodiments of the present disclosure relate generally to the field of fuses, and more particularly to a fuse including a strain-relieved terminal.
Fuses are used as circuit protection devices and form electrical connections with components in circuits to be protected. One type of fuse includes a fusible element that is disposed within a hollow fuse body and that extends between a pair of terminals. The terminals may be rigidly secured or fastened to other circuit components by bolts or other fasteners, which are mounted inside a plastic fuse box and constrain the fuse. In operation, the system may fluctuate in temperature, whereby the fuse box and components of the fuse may expand and/or contract. Since the fuse box and various components of the fuse are formed of different materials, the components may expand and contract at different rates and to different degrees due to differences in the coefficients of thermal expansion (CTE) of the materials, resulting in relative movement between the components. Since the fuse terminals are rigidly fixed in place within the fuse box, the components of the fuse may be pushed toward and/or pulled away from the terminals during expansion and contraction, subjecting the components to mechanical stress which may, in some cases, crack or otherwise damage the components.
It is with respect to these and other considerations that the present improvements may be useful.
This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended as an aid in determining the scope of the claimed subject matter.
In an embodiment of the present disclosure, a fuse includes a fuse body, a fuse element including a first terminal end extending from a first end of the fuse body, and a second terminal extending from a second end of the fuse body, wherein at least one of the first terminal end and the second terminal end extending out of the respective first and second ends of the fuse body include a strain relief feature, and wherein the strain relief feature is configured to flex in response to thermal fluctuation of the fuse.
In an embodiment, a method for forming a fuse includes joining a first terminal end and a second terminal end to opposing ends of a fuse element, inserting the fuse element into a fuse body, the first terminal end extending out of a first end of the fuse body, and the second terminal end extending out of a second end of the fuse body, mounting apertures being formed in the first and second terminal ends, joining end caps to the first and second ends of the fuse body, the first and second terminal ends extending through the end caps, and forming a strain relief feature in at least one of the first terminal end and the second terminal end, the strain relief feature being disposed intermediate a respective one of the mounting apertures and end caps, wherein the strain relief feature is configured to flex in response to thermal fluctuation of the fuse.
By way of example, specific embodiments of the disclosed device will now be described with reference to the accompanying drawings, in which:
A fuse in accordance with the present disclosure will now be described more fully hereinafter with reference to the accompanying drawings, in which certain exemplary embodiments of the fuse are presented. The fuse may be embodied in many different forms and is not to be construed as being 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 fuse to those skilled in the art. In the drawings, like numbers refer to like elements throughout unless otherwise noted.
Referring to
The fuse element 120 may be formed of an electrically conductive material, including, but not limited to, silver or copper, and may be configured to melt or otherwise separate upon the occurrence of a predetermined fault condition, such as an overcurrent condition in which an amount of current exceeding a predefined maximum current flows through the fuse element 120. The fuse element 120, which is depicted generically in
In operation, the terminal ends 120a, 120b of the fuse 100 may be rigidly fastened to other circuit elements (not shown) by bolts or other fasteners. As electrical current passes through the fuse 100, the components of the fuse 100 (e.g., the fuse element 120, the end caps 110, and the fuse body 105) may be subjected to thermal fluctuations and may therefore experience thermal expansion and contraction. Since the components of the fuse 100 are formed of different materials, the components may expand and contract at different rates and to different degrees due to differences in the coefficients of thermal expansion (CTE) of the materials, resulting in relative movement between the components. Often, the fuse may be mounted in a fuse box that is made from a material with a relatively high CTE in comparison to the fuse components. Since the terminal ends 120a, 120b are rigidly fixed in place, the components of the fuse 100 may be pushed toward and/or pulled away from the terminal ends 120a, 120b during expansion and contraction of the components or fuse box, subjecting the components to mechanical stress which may result in damage to the components. The fuse element 120, which is typically very thin and/or delicate, may be particularly susceptible to premature breakage from such mechanical stress.
Still referring to
The strain relief features 130a, 130b may each include one or more crimps, bends, folds, channels, corrugations, or the like formed in the terminal ends 120a, 120b that permit the terminal ends 120a, 120b to extend and retract in a spring-like manner in response to mechanical force applied thereto. The strain relief features 130a, 130b may be configured to flex in response to mechanical strain, typically induced by thermal fluctuation of the fuse or surrounding components to which the fuse is connected (e.g., a plastic fuse box). Thus, the strain relief features 130a, 130b may act as dampers that accommodate expansion and contraction of the fuse box and various components of the fuse 100 to prevent such expansion and contraction from placing mechanical stress on components of the fuse 100 that are susceptible to breakage. For example, if the fuse body 105 of the fuse 100 were to undergo thermal contraction, the fuse body 105 would pull inwardly on the terminal ends 120a, 120b. This pulling would cause the strain relief features 130a, 130b to flex and extend in an accordion-like manner inwardly, toward the fuse element 120, mitigating tensile strain in the relatively fragile internal features of the fuse element 120 and preventing the fuse element 120 from breaking. In the absence of the strain relief features 130a, 130b (i.e., in conventional fuses), the accumulation of tensile strain in the fuse element 120 would go unmitigated and the fuse element 120 may therefore break.
In various embodiments of the fuse 100 the strain relief features 130a, 130b may include channels or corrugations having different shapes and/or configurations for providing the terminals ends 120a, 120b with greater or lesser flexibility as desired. For example, referring to the embodiments of the fuse 100 shown in
In an embodiment, one or both of the strain relief features 130a, 130b may include a single corrugation, and in other embodiments one or both of the strain relief features 130a, 130b may include a plurality of corrugations 145. In an embodiment, the plurality of corrugations 145 may be alternating. The strain relief features 130a, 130b may each include a ridge 145′ and a groove 145″ as shown in
In various embodiments of the fuse 100, the strain relief features 130a, 130b may be identical to one another or may be different from one another. For example,
Referring now to
In an embodiment, a strain relief feature 130a, 130b may be disposed at one of the terminal ends 120a, 120b, while the other of the terminal ends 120a, 120b does not include a strain relief feature. For example,
Any of the above-described strain relief features may be implemented in any of a variety of fuse types. For example,
Referring now to
In an embodiment, the material thickness of the fuse element 120 may be variable, as shown in
At block 910, the fuse element including the first and second terminal ends is inserted into a tubular fuse body with the first and second terminal ends protruding from opposing ends of the fuse body. In some embodiments, the fuse body may include at least two portions that are joined together to define an internal cavity.
At block 915, ends caps are joined to the first end and the second end of the fuse body. The first terminal end and the second terminal end may extend through apertures in the end caps. Mounting apertures for receiving a bolt or other fastener to secure the fuse to other circuit components may be formed in portions of the first and second terminal ends that protrude from the end caps.
At block 920, a strain relief feature is formed in at least one of the first terminal end and the second terminal end. As described above, the strain relief features may be located intermediate the end caps and the mounting apertures of the terminal ends to advantageously permit the terminal ends to flex in response to thermal fluctuation (e.g., expansion and contraction) of the components of the fuse to prevent or mitigate damage that may otherwise result from mechanical stress on such components. The strain relief features may include channels or corrugations having different shapes and/or configurations for providing the terminals ends with greater or lesser flexibility as desired.
It should be understood that the strain relief features may be formed at any of various stages of forming the fuse. Strain relief channels may include one or more crimps, bends, folds, channels, corrugations, or the like, which may act as dampers that accommodate expansion and contraction of the various components of the fuse to prevent such expansion and contraction from placing mechanical stress on components of the fuse that are susceptible to breakage. In an embodiment, the strain relief feature may be formed in the terminal ends when the fuse element and terminal ends are processed. For example, the strain relief features may be formed in the terminal ends prior to joining to the fuse element in block 905. In another embodiment, the strain relief features may be formed as a secondary operation to completed the completed fuses, e.g., after the terminal ends are joined to the fuse element in block 905.
As used herein, references to “an embodiment,” “an implementation,” “an example,” and/or equivalents is not intended to be interpreted as excluding the existence of additional embodiments also incorporating the recited features.
The present disclosure is not to be limited in scope by the specific embodiments described herein. Indeed, other various embodiments of and modifications to the present disclosure, in addition to those described herein, will be apparent to those of ordinary skill in the art from the foregoing description and accompanying drawings. Thus, such other embodiments and modifications are intended to fall within the scope of the present disclosure. Furthermore, although the present disclosure has been described herein in the context of a particular implementation in a particular environment for a particular purpose, those of ordinary skill in the art will recognize its usefulness is not limited thereto and the present disclosure can be beneficially implemented in any number of environments for any number of purposes. Thus, the claims set forth below are to be construed in view of the full breadth and spirit of the present disclosure as described herein.
