Patent Application
20180047539
The present invention relates to a fuse resistor and a method of manufacturing the same, and more particularly, to a fuse resistor mounted at an electric circuit of an electronic product to prevent the electronic product from breaking down due to inrush current, increase of internal temperature, and continuous overcurrent, and a method of manufacturing the same.
Generally, in an electric circuit of a large electronic product such as an LCD TV, or a PDP TV, a protector such as a thermal fuse resistor for protecting the electric circuit is provided at an input terminal. Thereby, the protector prevents the electronic product from breaking down due to inrush current, increase of internal temperature, and continuous overcurrent, which are generated when powered on.
Such a fuse resistor includes a resistor, a thermal fuse, a lead wire connected between the resistor and the thermal fuse.
In addition, when the fuse blows, fragments occur in the fuse resistor. To prevent the fragments from affecting the other electric components, the resistor and the thermal fuse are packaged by a case and the case is filled with a filler.
Herein, a slurry type filler including silica (SiO2) is used as the filler in consideration of thermal resistance, conductivity, hardening, and so on. Generally, a case formed of a ceramic material is used as the case. The ceramic case is used as a general resistive case.
Furthermore, an end of the lead wire extends to be withdrawn outside the case. In the conventional fuse resistor, the end of the lead wire is soldered to a printed circuit board, and thus the resistor and the thermal fuse are vertically mounted at the printed circuit board.
Accordingly, in the case that inrush current is introduced, such a fuse resistor, as provided above, limits the inrush current to a certain current using the resistor. In the case that overcurrent is introduced, heat generated by heating of the resistor is transferred to the thermal fuse through the filler, and then a solid phase lead or a fuse formed of a polymer pellet, which is provided in the thermal fuse, blows to generate a short circuit. As a result, the electric circuit of the electric product is protected.
It is difficult to miniaturize the fuse resistor 10 in described Korean patent No. 10-1060013. Also, a process of manufacturing of the fuse resistor is complicated since a pair of lead wires 31 and 32 and a pair of lead wires 33 and 34 are connected to the resistor 10 and the thermal fuse 20, respectively, and then, the lead wire 31 of the resistor 10 and the lead wire 33 of the thermal fuse 20 are connected to each other.
Therefore, the present invention has been made in view of the above problems of the related art, and it is an object of the present invention to provide a thermal fuse capable of simplifying an assembly process by coupling a thermal fuse and a lead wire in a modularized manner and by fixing a fusing lead wire to the lead wire in an integrated manner to form a lower molding unit, and a method of manufacturing the same.
It is another object of the present invention to provide a fuse resistor having a simple structure and capable of being miniaturized as an integrated structure of the thermal fuse and the lead wire is inserted, and a method of manufacturing the same.
In accordance with an aspect of the present invention, the above and other objects can be accomplished by the provision of a fuse resistor including a resistor, a fusing lead wire including a first wire part coupled to one side of the resistor, a second wire part connected to a substrate, and a thermal fuse, one end of the thermal fuse being coupled to the first wire part, and the other end of the thermal fuse being coupled to the second wire part, a lead wire connected to the other side of the resistor, a lower molding unit mold-injected in the state that a part of the fusing lead wire and a part of the lead wire are spaced apart a certain distance from each other, and an upper casing having a cylinder shape, the upper casing being provided with an opening at one side thereof, the upper casing accommodating the resistor, a part of the fusing lead wire and a part of the lead wire, and the opening being coupled to the lower molding unit.
The upper casing may be filled with a filler, the filler may be formed of cement, and the lower molding unit may be formed of a resin having a thermal conductivity less than that of the filler.
The lower molding unit may be formed to have a thickness to accommodate a part of the first wire part, a part of the second wire part and the thermal fuse.
A distance from a horizontal central line of the resistor to an upper surface of the lower molding unit may be less than a distance from the horizontal central line of the resistor to an upper surface of the thermal fuse.
A distance from a horizontal central line of the resistor to an upper surface of the lower molding unit may be greater than a distance from the horizontal central line of the resistor to a lower surface of the thermal fuse.
The lower molding unit may be provided with a seating part at an edge portion thereof, and the seating part may have a width corresponding to a thickness of the upper casing.
The resistor may include a wire wound resistor including a ceramic rod, a pair of terminals disposed at both ends of the ceramic rod, and a lead wire wound on the ceramic rod, and silicon may be coated at surfaces of the ceramic rod and the lead wire to form a coating layer.
In accordance with another aspect of the present invention, a method of manufacturing a fuse resistor includes preparing a fusing lead wire and a lead wire, coupling both ends of a resistor to the fusing lead wire and the lead wire, respectively, forming a lower molding unit molded by an insert injection, in which a part of the fusing lead wire and a part of the lead wire are inserted into the lower molding unit and are spaced apart a certain distance from each other, filling an inner space of an upper casing with a filler through an opening, in which the upper casing is cylindrical and is provided with the opening at one side thereof, and coupling the upper casing to the lower molding unit with the resistor inserted into the upper casing.
The fusing lead wire may include a first wire part coupled to one side of the resistor, a second wire part connected to a substrate and a thermal fuse, one end of the thermal fuse may be coupled to the first wire part, and the other end of the thermal fuse may be coupled to the second wire part, and the first wire part, the second wire part, and the thermal fuse may each have an identical diameter.
The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:
Hereinafter, the embodiments of the present invention will be described in detail with reference to the accompanying drawings.
Referring
Upon applying overcurrent, the resistor 110 radiates heat such that a thermal fuse 125 mounted at the fusing lead wire 120 may blow. As illustrated in
In addition, a coating layer 115 may be formed on a surface of the resistor 110 as illustrated in
The coating layer 115 may function to protect the wire 113 and to improve explosion proofing. As illustrated in
The filling layer 115′ or 115″ may function to maximize explosion proofing of the resistor 110. As illustrated in
In the case that abnormal current is applied and the resistor 110 is exploded, the coating layer 115 or the filling layer 115′ or 115″ can initially absorb impact and noise by the exploding. Accordingly, explosion proofing of the product is improved.
The fusing lead wire 120 and the lead wire 130 are coupled to each of the terminals 117 of the resistor 110.
The fusing lead wire 120 includes a first wire part 121 coupled to the resistor with the first wire part 121 bent downward, a second wire part 123 connected to a substrate, and the thermal fuse 125. In this case, one end of the thermal fuse 125 is coupled to the first wire part 121 and the other end of the thermal fuse 125 is coupled to the second wire part 123.
As described above, the thermal fuse 125 is inserted between the first and second wire parts 121 and 123 of the fusing lead wire 120 and, as such, it is possible for the structure to be simplified and miniaturized.
The thermal fuse 125 blows by heat radiated from the resistor 110 to generate a short circuit. Thereby, the thermal fuse 125 functions to protect devices mounted on the circuit.
In addition, as illustrated in
The flex part 127 may function to agglomerate the melted fusible part 126. For example, the flex part 127 may include a chloride, a fluoride, a resin, and so on.
Upon coupling the thermal fuse 125 and the first and second wire parts 121 and 123, an end of the fusible part 126 formed of a metallic material is in contact with each of ends of the first and second wire parts 121 and 123 and then welding is performed. In this case, the thermal fuse 125 may have a diameter identical to each of diameters of the first and second wire parts 121 and 123. When the diameter of the thermal fuse 125 is greater than each of the diameters of the first and second wire parts 121 and 123, at least the flex part 127 is formed to have a diameter less than each of the diameters of the first and second wire parts 121 and 123. Thereby, the fusible part 126 should be in contact with the first and second wire parts 121 and 123.
In the thermal fuse 125, if the fusible part is formed to be inserted into a central portion of the flex part and heat supplied from the resistor heats the flex part and then heats the fusible part, fusing time is delayed and blowing property is decreased. In addition, as the flex part formed of a dielectric material is disposed on the thermal fuse, the flex part cannot be coupled using a spot welding process. Accordingly, the thermal fuse 125 may preferably have a structure, in which the flex part 127 is inserted into the fusible part 126.
The upper casing 150 may include any one of a thermohardening resin, a thermoplastic resin, and a ceramic material. The upper casing 150 is cylindrical and is provided with an opening 151 at one side. The resistor 110, a part of the fusing lead wire 120 and the lead wire 130 are inserted into the upper casing 150 through the opening 151.
The opening 151 of the upper casing 150 is sealed by the lower molding unit 140. The filler 160 providing explosion proofing fills the inner space of the upper case 150.
The filler 160 may absorb impact and noise upon explosion of the resistor 110. For example, the filler 160 may include cement, silicon, and a resin such as epoxy.
As illustrated in
In addition, the resistor 110, the fusing lead wire 120 and the lead wire 130 are modularized by the lower molding unit in an integrated manner and, as such, it is easy to couple the lower molding unit 140 to the upper casing 150. Furthermore, the fusing lead wire 120 and the lead wire 130 are spaced apart a certain distance from each other and, as such, defective products may be decreased during surface mounting of the fuse resistor.
The lower molding unit 140 is formed to have a block or plate shape having a size corresponding to the opening 151 of the upper casing 150 to seal the opening 151. A seating part 141 is provided at an edge region of an upper surface of the lower molding unit 140 to have a width corresponding to a thickness of the upper casing 150. In this case, the lower molding unit 140 is coupled to the upper casing 150 in an engaged manner.
Furthermore, as illustrated in
Hereinafter, in the case that the filler 160 is formed of cement and the lower molding unit 140 is formed of a resin, fusing characteristics between the lower molding unit 140 of
In the case of the lower molding unit 140 of
In the case of the lower molding unit 140′ of
Blowing property of each of the lower molding units 140 and 140′ will be given. In
Whereas, in
Hereinafter, a method of manufacturing the fuse resistor will be explained with reference to the accompanying drawings.
First, referring to
The thermal fuse 125 is coupled to the first and second wire parts 121 and 123 using a soldering process, a spot welding process or an ultrasonic welding process.
Then, referring to
Sequentially, referring to
Then, referring to
In conclusion, according to present invention, the thermal fuse 125 is inserted into the fusing lead wire 120 to form a simple structure and, as such, miniaturization of a product may be implemented. The fusing lead wire 120 and the lead wire 130 are fixed in an integrated manner to form the lower molding unit 140. In this case, the lower molding unit 140 is coupled to the upper casing 150 and, as such, a manufacturing process may be simplified.
As apparent from the above description, in accordance with the present invention, the thermal fuse and the lead wire are coupled to form one module and the fusing lead wire and the lead wire are fixed in an integrated manner to form the lower molding unit. Thus, an assembly process is simplified.
Furthermore, according to the illustrated embodiment of the present invention, the thermal fuse and the lead wire are formed to be an inserted structure in an integrated manner and, as such, the structure is simple and miniaturized.
Although the exemplary embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims. Accordingly, the scope of the present invention should not be limited to and defined by the embodiments described herein, and should be construed as including the following claims and equivalents thereof.
