Miniature fuse

A fuse comprising:

• a body of insulating material having a cavity therein opening onto at least one longitudinal side surface of said body;
• a pair of terminals secured within opposite end portions of said insulating body and conductive fuse element attachment surfaces forming conductive extensions at the inner ends of said terminals beyond opposite margins of said cavity, the outer ends of said terminals being exposed to the exterior of the fuse at the longitudinal ends of said body to make electrical connection to an external circuit;
• said body having a pair of narrow grooves extending outwardly from opposite margins of said cavity toward and in the vicinity of said attachment surfaces and opening onto opposite sides of said body, said grooves being initially open over their full lengths onto said side surface of said body so that said fuse element may be laid into said grooves from said one side surface with the fuse element exiting said grooves;
• a fuse element disposed in said grooves and conductively secured between said fuse element attachment surfaces of said terminals and passing over or within an open side of said cavity, the defining walls of said grooves forming arc barriers to prevent expansion of an arc onto said attachment surfaces when the fuse element blows;
• and closure means enveloping the longitudinal sides of said body for sealing the openings in the longitudinal sides of said insulating body.

A fuse comprising:

• a body of insulating material having a cavity therein opening onto at least one longitudinal side surface of said body;
• a pair of terminals extending outwardly from opposite longitudinal ends of said body to make direct electrical connection with an external circuit and having conductive fuse element attachment surfaces forming conductive extensions of said terminals and located substantially beyond the margins of said cavity at opposite end portions of said body,
• said body having a pair of narrow grooves extending from opposite margins of said cavity toward and in the vicinity of said attachment surfaces;
• a fuse element disposed in said grooves and conductively secured between said attachment surfaces and passing over or within an open side of said cavity, the defining walls of said grooves forming arc barriers to prevent expansion of an arc onto said attachment surfaces when the fuse element blows;
• and
• enclosure means for sealing the openings on the sides of said body communicating with said cavity, said enclosure means being an open ended insulating sleeve fitted longitudinally over said body from one end thereof and sealed around the opposite longitudinal ends thereof.

In a fuse comprising:

• a body of insulating material having a cavity therein opening onto at least one longitudinal side surface of said body;
• a pair of terminals secured within opposite end portions of said insulating body and conductive fuse element attachment surfaces forming conductive extension at the inner ends of said terminals beyond the margins of said cavity, the outer ends of said terminals being exposed to make electrical connection to an external circuit, said body having a pair of narrow grooves extending outwardly from opposite margins of said cavity toward and in the vicinity of said attachment surfaces;
• said grooves extending outwardly from said cavity toward the opposite ends of said body and initially opening over their full lengths onto said one side surface of said body so that said fuse element may be laid into said grooves from said one side surface;
• a fuse element disposed in said grooves and conductively secured between said exposed surfaces of said terminals and passing over or within an open side of said cavity, the defining walls of said grooves forming arc barriers to prevent expansion of an arc onto said attachment surfaces when the fuse element blows;
• and enclosure means for sealing the openings in the sides of said insulating body,
• the improvement wherein said grooves in advance of said attachment surfaces are intersected by enlarged recesses opening onto said one side surface;
• and
• a rigid plug of insulating, arc-inhibiting material in each of said recesses and extending into contiguous relation with the fuse element in the bottom of said grooves.

A fuse comprising:

• a body of insulating material having a cavity therein, said cavity opening onto opposite longitudinal sides of said insulating body through cavity openings thereat;
• a pair of terminals secured within said insulating body at opposite ends thereof and conductive fuse element attachment surfaces forming conductive extensions of said terminals and located beyond the margins of said cavity, said terminals extending from said body to make electrical connection to an external circuit;
• a fuse element conductively secured between said attachment surfaces of said terminals and passing over or within said open said of said cavity;
• and
• means for closing off the openings on the sides of said body communicating with said cavity and comprising enclosure means engaging said insulating body for sealing the openings in the sides of said body communicating with said cavity and forming opposite said cavity openings expandable wall means which expand substantially without breaking to increase the volume of said cavity under the pressures built up in said cavity when the fuse blows, to reduce the pressure and temperatures within the cavity and to assist in the complete quenching of the arc which develops momentarily when the fuse blows.

A fuse comprising:

• a body of insulating material having a cavity therein, said cavity opening onto opposite longitudinal sides of said insulating body through cavity openings thereat;
• a pair of terminals secured within said insulating body at opposite ends thereof and conductive fuse element attachment surfaces forming conductive extensions of said terminals and located beyond the margins of said cavity, said terminals extending from said body to make electrical connection to an external circuit;
• a fuse element conductively secured between said attachment surfaces of said terminals and passing over or within said open said of said cavity;
• said body having a recess forming a recessed ledge around one of said cavity openings upon which ledge a cavity closure plate can be secured to close off one end of said cavity, so that the cavity can be filled with an arc quenching material before the enclosure means is applied to the insulating body;
• and
• means for closing off the openings on the sides of said body communicating with said cavity and comprising enclosure means engaging said insulating body for sealing the openings in the sides of said body communicating with said cavity.

A method of making a miniature fuse comprising the steps of:

• providing a body of insulating material with a cavity opening onto at least one side surface of said body and a pair of terminals secured within said insulating body and projecting from opposite longitudinal ends of said body to make direct electrical connection to an external electric circuit, said terminals having conductive fuse attachment surfaces forming conductive extensions of the inner ends of said terminals and located beyond the margins of said cavity, said attachment surfaces being disposed adjacent to diagonally opposite ends of said body where they are on opposite sides of the longitudinal axis thereof, said body having aligned grooves extending longitudinally outwardly from opposite end portions of said cavity to oppositely facing surfaces of said body, the grooves extending to the vicinity of said attachment surfaces and opening onto said one side surface of the body for substantially their full lengths, so that the grooves are lay-in grooves into which a fuse element can be placed from said one side surface;
• orienting said body so that said cavity and one side surface of the body face upwardly where said cavity and grooves open to the top of the body;
• laying a fuse element in said grooves so it spans said cavity;
• mechanically and electrically connecting the ends of said fuse element to said terminal fuse attachment surfaces;
• and then applying an open ended sleeve longitudinally over said insulating body to seal off the open sides of the cavity and said lay-in grooves and sealing said sleeve around at least the opposite longitudinal ends of said body.

A method of making a miniature fuse comprising the steps of:

• providing a body of insulating material with a cavity opening onto at least one side surface of said body and a pair of terminals secured within opposite ends portions of said insulating body and exposed thereat for direct connection to an external circuit, bendable tabs which initially project from oppositely facing surfaces of the body, said body having aligned grooves longitudinally extending outwardly from opposite portions of said cavity to the vicinity of said tabs and opening onto said one side surface of the body for substantially their full lengths, so that the grooves are lay-in grooves into which a fuse element can be placed from said one side surface;
• orienting said body so that said cavity and one side surface of the body face upwardly where said cavity and grooves open to the top of the body;
• laying a fuse element in said grooves so it spans said cavity and extends to said tabs;
• bending said tabs downwardly and securing said fuse element to said tabs;
• and applying enclosure means to said body to seal off the open sides of the cavity and said lay-in grooves.

A method of mass producing miniature fuses comprising the steps of:

• providing a carrier strip of conductive material from which are punched longitudinally spaced laterally confronting pairs of terminals, each pair of said laterally confronting terminals having spaced confronting inner end portions which form exposes surfaces to which the ends of a fuse element are to be connected;
• individually molding a body of insulating material around and extending between each of said pair of confronting inner end portions of each pair of terminals and which define a cavity therebetween leaving the outer ends of the terminals projecting therefrom and opening onto a side thereof, leaving exposed inner tip ends of said terminals;
• severing said strip at longitudinally spaced points therealong to separate the individual insulating bodies molded around parts of the inner end portions of said terminals;
• before or after the separation of said insulating bodies and pairs of terminals from said strip placing a fuse element between said exposed tip ends of each pair of terminals and mechanically and electrically attaching the ends of the fuse elements to said tip ends of each pair of terminals;
• and applying a sleeve around each insulating body to seal over the cavity and other openings on the sides of each body enclosed thereby.

In a fuse comprising a body of insulating material having a cavity therein opening onto at least one side of said body;

• a pair of terminals secured within said insulating body and conductive fuse element attachment surfaces forming conductive extensions at the inner ends of said terminals beyond opposite margins of said cavity, the outer ends of said terminals being exposed to the exterior of the fuse to make electrical connection to an external circuit;
• said body having a pair of narrow grooves extending outwardly from opposite margins of said cavity toward and in the vicinity of said attachment surfaces and opening onto opposite sides of said body other than said one side, said grooves being initially open over their full lengths onto said one side surface of said body so that said fuse element may be laid into said grooves from said one side surface with the fuse element exiting said grooves;
• a fuse element disposed in said grooves and conductively secured between said fuse element attachment surfaces of said terminals and passing over or within an open side of said cavity, the defining walls of said grooves forming arc barriers to prevent expansion of an arc onto said attachment surfaces when the fuse element blows;
• and enclosure means for sealing the openings in the longitudinal sides of said insulating body, the improvement wherein said attachment surfaces to which the fuse element ends are attached are located beyond the ends of the grooves and face and are exposed respectively to said opposite sides of said body other than said one side thereof and are out of alignment with and are located in planes inside the ends of said grooves, the ends of said fuse element in said grooves exiting said grooves and then bending inwardly to engage said attachment surfaces, and there being no other exposed conductive surfaces in alignment with said grooves.