Circuit protection device

Abstract

A circuit protection device is disclosed, comprising: a housing; a negative temperature coefficient thermistor, which is accommodated in the housing and includes a resistance heating element, a pair of electrodes mounted on both sides of the resistance heating element, and a first thermistor lead and a second thermistor lead respectively drawn out from the pair of electrodes; and a fuse, which is accommodated in the housing and includes a fuse body, and a first fuse lead and a second fuse lead respectively connected to both ends of the fuse body. Here, the fuse body includes a fuse rod having a plating layer formed thereon and a pair of fuse caps coupled to both ends of the fuse rod and having conductivity, and the first fuse lead and the second fuse lead are respectively joined to the pair of fuse caps.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to and the benefit of Korean Patent Application No. 2019-0123686, filed on October 7, 2019, the disclosure of which is incorporated herein by reference in its entirety. Technical Field

[0003] The present invention relates to a circuit protection device, and more particularly, to a circuit protection device configured to limit surge current when an electronic product is initially driven and prevent fire caused by an increase in internal temperature or overcurrent. Background Art

[0004] Typically, in the circuits of large electronic products such as air conditioners, washing machines, refrigerators, dryers, etc., a circuit protection device is provided at the power input terminal of the circuit, and protects the power circuit from malfunctions caused by surge currents, increases in internal temperature, continuous overcurrents, etc., which occur when the power is turned on.

[0005] Figure 1 Components and operation of an existing circuit protection device are shown. The existing circuit protection device includes a fuse resistor RF, a first relay S1 connected in series with the fuse resistor RF, and a second relay S2 connected in parallel with the fuse resistor RF and the first relay S1. The fuse resistor RF includes a resistor R and a thermal fuse F, and the resistor R and the thermal fuse F are connected in series with each other.

[0006] After a certain time, the circuit protection device is switched from state (a) in which the first relay S1 is closed and the second relay S2 is open when driven to state (b) in which the first relay S1 is open and the second relay S2 is closed.

[0007] In state (a), the input current is input to the circuit via the fuse resistor RF and the first relay S1. Here, when the resistor R limits the surge current to a certain current and an overcurrent flows therein, the heat generated by the resistor R is conducted to the thermal fuse F, and the fusion body including the solid lead or polymer particles disposed inside the thermal fuse F is melted to short-circuit the circuit, thereby protecting the circuit of the household appliance. After the surge current disappears and the input current stabilizes for a certain time (e.g., about 0.5 seconds), the circuit protection device changes to state (b), so that a normal input current passes through the second relay S2 and is input to the circuit.

[0008] Since the circuit protection device includes three components, namely, the fuse resistor RF and the first relay S1 and the second relay S2, they have a relatively large volume, high cost and occupy a large space. In addition, the normal input current is in the range of 2A to 4A in the case of a washing machine, and 7A or higher in the case of a dryer. Therefore, it is necessary to use a high-current relay for the first relay S1 and the second relay S2. Here, since the high-current relay is expensive and there are few commercial domestic products, most of the high-current relays must be imported from Japan and the like.

[0009] In addition, since the operation of opening or closing the first relay S1 and the second relay S2 is repeatedly performed whenever the electronic product is started or deactivated, the durability of the electronic product decreases and failures occur as the electronic product is used for a long time. Failure of the first relay S1 and the second relay S2 may cause an inflow of overcurrent or even cause a fire. Therefore, in a circuit protection device using a relay, this risk is always inherent. Summary of the invention

[0010] An object of the present invention is to provide a circuit protection device that can replace a circuit protection device including a fuse resistor RF, a first relay S1, and a second relay S2, and can reduce costs and occupy less space without using relays.

[0011] Aspects of the present invention are not limited to the above-mentioned aspects, and those skilled in the art will understand other undescribed aspects of the present invention from the following description.

[0012] According to one aspect of the present invention, there is provided a circuit protection device, comprising: a housing; a negative temperature coefficient thermistor, which is accommodated in the housing and includes a resistance heating element, a pair of electrodes mounted on both sides of the resistance heating element, and a first thermistor lead and a second thermistor lead respectively drawn out from the pair of electrodes; and a fuse, which is accommodated in the housing and includes a fuse body, and a first fuse lead and a second fuse lead respectively connected to both ends of the fuse body. Here, the fuse body includes a fuse rod having a plating layer formed thereon and a pair of fuse caps coupled to both ends of the fuse rod and having conductivity, and the first fuse lead and the second fuse lead are respectively joined to the pair of fuse caps. In addition, the second thermistor lead and the first fuse lead are connected to each other in the housing.

[0013] The circuit protection device may further include a first pin connected to the first thermistor lead and a second pin connected to the second fuse lead. Here, a first guide groove and a second guide groove may be formed in the housing, the first guide groove being configured to guide the first pin to be withdrawn outward from the housing, and the second guide groove being configured to guide the second pin to be withdrawn outward from the housing.

[0014] The first pin and the second pin may respectively include a plate-shaped body, one side of which is respectively connected to the first thermistor lead and the second fuse lead, and the first pin and the second pin each include at least one extension portion extending from the other side of the body and having a width smaller than a width of the body.

[0015] The bodies of the first pin and the second pin may include a first part and a second part, one side of the first part of the two is respectively connected to the first thermistor lead and the second fuse lead, and is respectively inserted into the first guide groove and the second guide groove, and the second part of the two extends from the other side of the first part, has a width greater than the width of the first part, and is pulled out from the shell.

[0016] The housing may include a partition wall extending from an inner wall of the housing and disposed between the resistance heating element and the fuse body.

[0017] According to another aspect of the present invention, a circuit protection device is provided, which includes: a housing; a first negative temperature coefficient thermistor, which is accommodated in the housing and includes a first resistance heating element, a pair of electrodes installed on both sides of the first resistance heating element, and a first thermistor lead and a second thermistor lead respectively drawn from the pair of electrodes; a second negative temperature coefficient thermistor, which is accommodated in the housing and includes a second resistance heating element, a pair of electrodes installed on both sides of the second resistance heating element, and a third thermistor lead and a fourth thermistor lead respectively drawn from the pair of electrodes; and a fuse, which is accommodated in the housing and includes a fuse body, and a first fuse lead and a second fuse lead respectively connected to both ends of the fuse body. Here, the fuse body includes a fuse rod with a plating layer formed thereon and a pair of fuse caps coupled to both ends of the fuse rod and having conductivity, and the first fuse lead and the second fuse lead are respectively joined to the pair of fuse caps. The first thermistor lead and the third thermistor lead are connected to each other in the housing. Additionally, the second thermistor lead, the fourth thermistor lead, and the first fuse lead are interconnected within the housing.

[0018] The circuit protection device may further include a first pin connected to the first thermistor lead and the third thermistor lead and a second pin connected to the second fuse lead. Here, a first guide groove and a second guide groove may be formed in the housing, the first guide groove being configured to guide the first pin to be withdrawn outward from the housing, and the second guide groove being configured to guide the second pin to be withdrawn outward from the housing.

[0019] The first pin may include a plate-shaped body having one side connected to the first thermistor lead and the third thermistor lead, and may include at least one extension extending from the other side of the body and having a width smaller than the width of the body. The body may include a first portion and a second portion, the first portion having one side connected to the first thermistor lead and the third thermistor lead and inserted into the first guide groove, and the second portion extending from the other side of the first portion and having a width larger than the width of the first portion to be located outside the housing.

[0020] The second pin may include a plate-shaped body connected to the second fuse lead at one side, and may include at least one extension extending from the other side of the body and having a width smaller than that of the body. The body of the second pin may include a first portion and a second portion, the first portion having one side connected to the second fuse lead and inserted into the second guide groove, and the second portion extending from the other side of the first portion and having a width larger than that of the first portion so as to be located outside the housing.

[0021] The housing may include a partition wall extending from an inner wall of the housing and disposed between the first resistance heating element, the second resistance heating element, and the fuse body.

[0022] The first resistance heating element and the second resistance heating element may be disposed to face each other.

[0023] The circuit protection device may further include a first cable and a second cable, one end of the first cable being connected to the first thermistor lead and the third thermistor lead, and one end of the second cable being connected to the second fuse lead. Here, a first guide groove and a second guide groove may be formed in the housing, the first guide groove being configured to guide the first cable to be pulled out of the housing, and the second guide groove being configured to guide the second cable to be pulled out of the housing.

[0024] According to another aspect of the present invention, there is provided a circuit protection device, comprising: a housing; a first negative temperature coefficient thermistor, which is accommodated in the housing and includes a first resistance heating element, a pair of electrodes mounted on both sides of the first resistance heating element, and a first thermistor lead and a second thermistor lead respectively drawn out from the pair of electrodes; a fuse, which is accommodated in the housing and includes a fuse body and a first fuse lead and a second fuse lead respectively connected to both ends of the fuse body; and a second negative temperature coefficient thermistor, which is accommodated in the housing and includes a second resistance heating element, a pair of electrodes mounted on both sides of the second resistance heating element, and a third thermistor lead and a fourth thermistor lead respectively drawn out from the pair of electrodes. Here, the fuse body includes a fuse rod having a plating layer formed thereon and a pair of fuse caps coupled to both ends of the fuse rod and having conductivity, and the first fuse lead and the second fuse lead are respectively joined to the pair of fuse caps. Furthermore, the second thermistor lead and the first fuse lead are connected to each other, and the second fuse lead and the third thermistor lead are connected to each other in the housing.

[0025] The circuit protection device may further include a first pin connected to the first thermistor lead and a second pin connected to the fourth thermistor lead. Here, a first guide groove and a second guide groove may be formed in the housing, the first guide groove being configured to guide the first pin to be withdrawn outward from the housing, and the second guide groove being configured to guide the second pin to be withdrawn outward from the housing.

[0026] The first pin and the second pin may respectively include a plate-shaped body, one side of each of the plate-shaped bodies being connected to the first thermistor lead and the fourth thermistor lead, respectively, and the first pin and the second pin each including at least one extension portion extending from the other side of the body and having a width smaller than a width of the body.

[0027] The bodies of the first pin and the second pin may include a first part and a second part, one side of the first part of the two is respectively connected to the first thermistor lead and the fourth thermistor lead, and is respectively inserted into the first guide groove and the second guide groove, and the second part of the two extends from the other side of the first part, has a width greater than a width of the first part, and is pulled out from the housing.

[0028] The housing may include a partition wall extending from an inner wall of the housing and disposed between the first resistance heating element, the second resistance heating element, and the fuse body. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The above and other objects, features and advantages of the present disclosure will become more apparent to those skilled in the art by describing in detail exemplary embodiments of the present disclosure with reference to the accompanying drawings, in which:

[0030] Figure 1 The components and operation of a conventional circuit protection device are shown;

[0031] Figure 2 is a perspective view of a circuit protection device according to a first embodiment of the present invention;

[0032] Figure 3A and Figure 3B It is shown in Figure 2 sectional views of the negative temperature coefficient thermistor 20 shown in FIG. 1 and taken along lines AA and BB, respectively;

[0033] Figure 4 It is shown Figure 2 Detailed configuration diagram of the fuse 30 shown in FIG.

[0034] Figure 5 The housing 10 contains Figure 2 A perspective view of the negative temperature coefficient thermistor 20, the fuse 30, etc., which are then filled with filler;

[0035] Figure 6 is a perspective view of a circuit protection device according to a second embodiment of the present invention;

[0036] Fig. 7A and Figure 7B It is shown in Figure 6 sectional views of negative temperature coefficient thermistors 50 and 60 shown in FIG. 1 and taken along lines AA and BB, respectively;

[0037] Figure 8 The housing 10 contains Figure 6 A perspective view of the negative temperature coefficient thermistors 50 and 60, the fuse 30, etc., which are then filled with fillers;

[0038] Fig. 9 The circuit protection device according to the first or second embodiment of the present invention is shown as being mounted on a circuit board;

[0039] Fig.10 is a perspective view of a circuit protection device according to a third embodiment of the present invention;

[0040] Fig.11A and Fig. 11B It is shown in Fig.10 sectional views of the first negative temperature coefficient thermistor 20 shown in FIG. 1 and taken along lines AA and BB, respectively;

[0041] Fig. 12A and Fig. 12B It is shown in Fig.10 sectional views of the second negative temperature coefficient thermistor 40 shown in FIG. 1 and taken along lines CC and DD, respectively;

[0042] Fig.13 The housing 10 contains Fig.10 A perspective view of the negative temperature coefficient thermistors 20 and 40, the fuse 30, etc., which are then filled with filler;

[0043] Fig.14 is a perspective view of a circuit protection device according to a fourth embodiment of the present invention;

[0044] Fig.15 The housing 10 contains Fig.14 The negative temperature coefficient thermistors 50 and 60, the thermal fuse 30, etc. are shown in a perspective view of a state in which they are then filled with filler. DETAILED DESCRIPTION

[0045] Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. Hereinafter, throughout the specification and the accompanying drawings, substantially the same elements will be referred to as the same reference numerals, and repeated descriptions thereof will be omitted. In addition, in the description of the embodiments of the present invention, detailed descriptions of known functions or components of the prior art will be omitted when it is considered that the understanding of the embodiments of the present invention will be obscured.

[0046] Figures 2 to 5 1 is a view showing components of a circuit protection device according to a first embodiment of the present invention. Figure 2 is a perspective view of a circuit protection device according to a first embodiment. Figure 3A and Figure 3B It is shown in Figure 2 2 and are cross-sectional views of the negative temperature coefficient thermistor 20 taken along lines AA and BB, respectively. Figure 4 It is shown Figure 2 A detailed configuration diagram of the fuse 30 is shown in FIG. Figure 5 The housing 10 contains Figure 2 The negative temperature coefficient thermistor 20, the fuse 30, etc. are shown in a perspective view of a state in which they are then filled with filler.

[0047] The circuit protection device according to the first embodiment of the present invention includes a housing 10 , a negative temperature coefficient thermistor 20 , a fuse 30 , a first pin 70_1 and a second pin 70_2 .

[0048] The housing 10 is formed of, for example, a ceramic material, and includes two side walls 11, a front wall 12, a rear wall 13, and a bottom wall 14, thereby forming a receiving groove with an open top, in which the negative temperature coefficient thermistor 20 and the fuse 30 are received. A first guide groove 15_1 and a second guide groove 15_2 are formed in the rear wall 13 to guide the first pin 70_1 and the second pin 70_2 to be respectively withdrawn outward from the housing 10.

[0049] like Figure 2 , Figure 3A and Figure 3B As shown in the figure, the negative temperature coefficient thermistor 20 includes a resistance heating element 21, a pair of electrodes 22 and 23 installed on both sides of the resistance heating element 21, and a first thermistor lead 25 and a second thermistor lead 26 respectively drawn out from the pair of electrodes 22 and 23, all of which are coated with a coating material 24.

[0050] Thermistor is a resistor element with a thermal resistance value that changes sensitively, and in particular has a characteristic that the resistance value changes according to the change of its temperature or ambient temperature. Among such thermistors, thermistors with a negative temperature coefficient are called negative temperature coefficient thermistors. Negative temperature coefficient thermistors have a resistance value that decreases according to the increase of its temperature or ambient temperature.

[0051] The fuse 30 includes a fuse body 31 and a first fuse lead 32 and a second fuse lead 33 respectively connected to both ends of the fuse body 31 .

[0052] Reference Figure 4 The fuse body 31 may include a fuse rod 34 , a plating layer 35 , a first fuse cap 36 , a second fuse cap 37 and a fuse protection layer 35 .

[0053] The fuse rod 34 may have a cylindrical shape, a prism shape, etc., and may be formed of a ceramic material.

[0054] The plating layer 35 is a conductive coating formed on the surface of the fuse rod 34, and may be formed by forming a tin layer as a fusible element layer on a plating layer including a nickel alloy or a copper alloy.

[0055] The first fuse cap 36 and the second fuse cap 37 may be inserted into and coupled to both ends of the fuse rod 34 on which the plating layer 35 is formed. To this end, each of the first fuse cap 36 and the second fuse cap 37 may be in the shape of a cap having a container structure (e.g., a cylindrical structure or an angular container structure) with one end closed.

[0056] The first fuse lead 32 and the second fuse lead 33 may be respectively connected to the outside of the first fuse cap 36 and the outside of the second fuse cap 37. The first fuse lead 32 and the second fuse lead 33 may be respectively bonded to the outside of the first fuse cap 36 and the outside of the second fuse cap 37 by spot welding, laser welding, soldering, etc.

[0057] The fuse protection layer 38 surrounds the fuse rod 34 on which the plating layer 35 is formed, the first fuse cap 36, and the second fuse cap 37. Therefore, the fuse protection layer 38 protects the coating of the plating layer 35 and the surfaces of the first fuse cap 36 and the second fuse cap 37. In addition, the fuse protection layer 38 has an insulating function for insulating from the outside (for example, another component, etc.).

[0058] like Figure 2 As shown in FIG. 1 , the second thermistor lead 26 of the NTC thermistor 20 and the first fuse lead 32 of the fuse body 31 are connected to each other. The second thermistor lead 26 and the first fuse lead 32 may be connected by brazing, arc welding, spot welding, laser welding, clamping, or the like.

[0059] At the same time, the first pin 70_1 and the second pin 70_2 having a conductive material are connected to the circuit board to perform electrical connection between the circuit and the circuit protection device. One end of the first pin 70_1 is connected to the first thermistor lead 25 of the negative temperature coefficient thermistor 20 in the housing 10, and extends through the first guide slot 15_1 so that the other end thereof is drawn outward from the housing 10. One end of the second pin 70_2 is connected to the second fuse lead 33 of the fuse 30 in the housing 10, and extends through the second guide slot 15_2 so that the other end thereof is drawn outward from the housing 10.

[0060] In an embodiment of the present invention, when the circuit protection device is mounted on a circuit board, the first pin 70_1 and the second pin 70_2 perform the functions of performing electrical connection between the circuit and the circuit protection device, dissipating heat generated by the circuit protection device, and separating the housing 10 from the circuit board by a specific interval.

[0061] The first pin 70_1 and the second pin 70_2 may include plate-shaped bodies 71_1 and 71_2 and extensions 72_1 and 72_2 extending from the bodies 71_1 and 71_2, respectively, and having a width smaller than that of the bodies 71_1 and 71_2. Generally, the extensions 72_1 and 72_2 are parts inserted and soldered into holes of a circuit board to perform electrical connection, and the bodies 71_1 and 71_2 are parts configured to dissipate heat and space the housing 10 from the circuit board by a certain interval.

[0062] In detail, the first pin 70_1 may include a main body 71_1 and an extension 72_1, one side of the main body 71_1 is connected to the first thermistor lead 25, and the extension 42_1 extends from the other side of the main body 71_1, and the width is smaller than the width of the main body 71_1. The second pin 70_2 may include a main body 71_2 and an extension 72_2, one side of the main body 71_2 is connected to the second fuse lead 33, and the extension 72_2 extends from the other side of the main body 71_2, and the width is smaller than the width of the main body 71_2. The first thermistor lead 25, the second fuse lead 33, and the main bodies 71_1 and 71_2 can be connected by brazing, arc welding, spot welding, laser welding, clamping, etc.

[0063] Moreover, the main bodies 71_1 and 71_2 may include first portions 71a_1 and 71a_2 having relatively small widths and second portions 71b_1 and 71b_2 having relatively large widths. Typically, the first portions 71a_1 and 71a_2 are portions connected to the leads 25 and 33 and inserted into the guide grooves 15_1 and 15_2, while the second portions 71b_1 and 71b_2 are portions drawn outward from the housing 10 to space the housing 10 from the circuit board by a certain interval. In addition, the second portions 71b_1 and 71b_2 may each include one or more protrusions 71c for improving heat dissipation performance.

[0064] Specifically, the body 71_1 of the first pin 70_1 includes a first portion 71a_1 and a second portion 71b_1, one side of the first portion 71a_1 is connected to the first thermistor lead 25 and inserted into the first guide groove 15_1, and the second portion 71b_1 extends from the other side of the first portion 71a_1, has a width greater than the width of the first portion 71a_1, and is drawn outward from the housing 10. The body 71_2 of the second pin 70_2 includes a first portion 71a_2 and a second portion 71b_2, one side of the first portion 71a_2 is connected to the second fuse lead 33 and inserted into the second guide groove 15_2, and the second portion 71b_2 extends from the other side of the first portion 71a_2, has a width greater than the width of the first portion 71a_2, and is drawn outward from the housing 10.

[0065] Meanwhile, since the negative temperature coefficient thermistor 20 and the fuse 30 are disposed adjacent to each other in the sealed space in the housing 10, so that the temperature of the circuit protection device or the temperature of its environment increases, there is a concern that even when it is necessary to prevent the fuse 30 from short-circuiting, the fuse 30 may short-circuit due to the heat generated by the negative temperature coefficient thermistor 20. Therefore, a partition wall 16 may be installed between the fuse body 31 and the resistance heating element 21 of the negative temperature coefficient thermistor 20 so as to maintain a certain interval or more between the fuse body 31 and the resistance heating element 21. The partition wall 16 may extend from an inner wall (e.g., the bottom wall 14 or the rear wall 13) of the housing 10. The partition wall 16 is installed so as not to completely separate the two spaces, thereby forming a path for the second thermistor lead 26 and the first fuse lead 32 to extend.

[0066] Reference Figure 5 In a state where the negative temperature coefficient thermistor 20, the fuse 30, etc. are accommodated in the housing 10, a filler 80 is filled. The filler 80 not only supports the negative temperature coefficient thermistor 20 and the fuse 30 in the accommodation groove, but also can effectively perform heat dissipation from the negative temperature coefficient thermistor 20 and the fuse 30. Therefore, the filler 80 may include a material having high heat dissipation.

[0067] According to the first embodiment of the present invention, since the resistance value of the negative temperature coefficient thermistor 20 is large at room temperature or relatively low temperature, and decreases as its temperature or ambient temperature increases, the surge current is limited to a specific current using a large resistance value when driving, and the normal input current is maintained using a resistance value that decreases due to temperature increase after a specific time. At the same time, when an overcurrent flows into the circuit or the circuit is overheated due to an abnormal phenomenon in the circuit, the fuse 30 is short-circuited and the inflow of current is cut off to prevent a fire. Therefore, the circuit protection device according to the first embodiment can replace Figure 1 In addition, since the negative temperature coefficient thermistor 20 has a relatively small volume and low price compared with a large current relay, the cost of the circuit protection device is reduced and the occupied space is reduced. Moreover, since no relay is used, the dangerous factors caused by the failure of the relay can be fundamentally eliminated.

[0068] Meanwhile, in the case of large household appliances such as air conditioners, washing machines, refrigerators, dryers, etc., since it is necessary to adapt to large currents, a circuit protection device with high heat generation performance is required. In the case of the first embodiment, in order to reduce the heat generation of the negative temperature coefficient thermistor 20, its size must be increased. Here, as the size of the negative temperature coefficient thermistor 20 increases, its manufacturing cost increases geometrically. Therefore, there is a limitation in reducing the heat generation by simply increasing the size of the negative temperature coefficient thermistor 20.

[0069] Therefore, hereinafter, as an embodiment capable of reducing the amount of heat generated by the circuit protection device without increasing the size of the negative temperature coefficient thermistor and having all the advantages of the first embodiment, an embodiment is provided in which two negative temperature coefficient thermistors are connected in parallel and the resistance value is reduced using the combined resistance value thereof, thereby reducing the amount of heat generated. For convenience, in the following embodiments, redundant descriptions overlapping with the first embodiment will be omitted.

[0070] Figures 6 to 8 2 is a view showing components of a circuit protection device according to a second embodiment of the present invention. Figure 6 is a perspective view of a circuit protection device according to a second embodiment. Fig. 7A and Figure 7B It is shown in Figure 6 2 and are cross-sectional views of negative temperature coefficient thermistors 50 and 60 taken along lines AA and BB, respectively. Figure 8 The housing 10 contains Figure 6 The negative temperature coefficient thermistors 50 and 60, the thermal fuse 30, etc. are shown in a perspective view of a state in which they are then filled with filler.

[0071] The circuit protection device according to the second embodiment of the present invention includes a housing 10 , a first negative temperature coefficient thermistor 50 , a second negative temperature coefficient thermistor 60 , a fuse 30 , a first pin 70_1 , and a second pin 70_2 .

[0072] The housing 10 includes two side walls 11, a front wall 12, a rear wall 13 and a bottom wall 14, thereby forming a receiving groove with an open top, in which the first negative temperature coefficient thermistor 50, the second negative temperature coefficient thermistor 60 and the fuse 30 are received. A first guide groove 15_1 and a second guide groove 15_2 are formed in the rear wall 13 to guide the first pin 70_1 and the second pin 70_2 to be drawn out of the housing 10, respectively.

[0073] like Figure 6 , Fig. 7A and Figure 7B As shown in FIG. , the first negative temperature coefficient thermistor 50 includes a first resistance heating element 51, a pair of electrodes 52 and 53 mounted on both sides of the first resistance heating element 51, and a first thermistor lead 55 and a second thermistor lead 56 respectively drawn out from the pair of electrodes 52 and 53, all of which are coated with a coating material 54. As with the first negative temperature coefficient thermistor 50, the second negative temperature coefficient thermistor 60 includes a second resistance heating element 61, a pair of electrodes 62 and 63 mounted on both sides of the second resistance heating element 61, and a third thermistor lead 65 and a fourth thermistor lead 66 respectively drawn out from the pair of electrodes 63 and 63, all of which are coated with a coating material 64.

[0074] The fuse 30 includes a fuse body 31 and a first fuse lead 32 and a second fuse lead 33 respectively connected to both ends of the fuse body 31 .

[0075] Reference Figure 6 , Fig. 7A and Figure 7B , the first thermistor lead 55 of the first negative temperature coefficient thermistor 50 and the third thermistor lead 65 of the second negative temperature coefficient thermistor 60 are connected to each other, and the second thermistor lead 56 of the first negative temperature coefficient thermistor 50 and the fourth thermistor lead 66 of the second negative temperature coefficient thermistor 60, and the first fuse lead 32 of the fuse 30 are connected to each other. The leads may be connected by soldering, arc welding, spot welding, laser welding, clamping, etc.

[0076] One end of the first pin 70_1 is connected to the first thermistor lead 55 of the first NTC thermistor 50 and the third thermistor lead 65 of the second NTC thermistor 60 in the housing 10. One end of the second pin 70_2 is connected to the second fuse lead 33 of the fuse 30 in the housing 10.

[0077] The first pin 70_1 may include a main body 71_1 and an extension 72_1, one side of the main body 71_1 is connected to the first thermistor lead 55 and the third thermistor lead 65, and the extension 72_1 extends from the other side of the main body 71_1 and has a width smaller than the width of the main body 71_1. The second pin 70_2 may include a main body 71_2 and an extension 72_2, one side of the main body 71_2 is connected to the second fuse lead 33, and the extension 72_2 extends from the other side of the main body 71_2 and has a width smaller than the width of the main body 71_2. The leads may be connected to the main body by soldering, arc welding, spot welding, laser welding, clamping, etc.

[0078] The body 71_1 of the first pin 70_1 includes a first portion 71a_1, one side of which is connected to the first thermistor lead 55 and the third thermistor lead 65 and inserted into the first guide groove 15_1, and a second portion 71b_1 extending from the other side of the first portion 71a_1, having a width greater than the width of the first portion 71a_1 and being drawn outward from the housing 10. The body 71_2 of the second pin 70_2 includes a first portion 71a_2, one side of which is connected to the second fuse lead 33 and inserted into the second guide groove 15_2, and a second portion 71b_2 extending from the other side of the first portion 71a_2, having a width greater than the width of the first portion 71a_2 and being drawn outward from the housing 10.

[0079] Meanwhile, a partition wall 16 may be installed between the fuse body 31 and the first and second resistance heating elements 51 and 61 of the first and second NTC thermistors 50 and 60 to maintain a certain interval therebetween.

[0080] Reference Figure 8 , a filler 80 is filled while accommodating the first and second negative temperature coefficient thermistors 50 and 60, the fuse 30, etc. in the housing 10. The filler 80 not only supports the first and second negative temperature coefficient thermistors 50 and 60 and the fuse 30 in the accommodating groove, but also can effectively perform heat dissipation from the first and second negative temperature coefficient thermistors 50 and 60 and the fuse 30.

[0081] Meanwhile, in this embodiment, the first resistance heating element 51 and the second resistance heating element 61 are plate-shaped as a whole and are arranged to be adjacent to and face each other. Since the first resistance heating element 51 and the second resistance heating element 61 are arranged to be adjacent to and face each other, the size of the circuit protection device can be reduced, and at the same time, the first resistance heating element 51 and the second resistance heating element 61 thermally affect each other, thereby reducing thermal imbalance. That is, when current flows through the resistance heating elements 51 and 61, the resistance heating elements 51 and 61 generate heat. Here, heat can be transferred from the resistance heating element with a large amount of heat to the resistance heating element with a small amount of heat, thereby alleviating the thermal imbalance between the resistance heating elements 51 and 61.

[0082] In addition, the first resistance heating element 51 and the second resistance heating element 61 may have the same resistance value or different resistance values. Since the first resistance heating element 51 and the second resistance heating element 61 have a parallel connection structure even with any resistance value, the combined resistance value becomes smaller than the resistance value of the first resistance heating element 51 and the resistance value of the second resistance heating element 61. Therefore, a circuit protection device having a relatively small combined resistance value can be realized, which is difficult to realize using only one of the first resistance heating element 51 or the second resistance heating element 61.

[0083] In particular, when the first resistance heating element 51 and the second resistance heating element 61 have different resistance values, heat from one of the first resistance heating element 51 and the second resistance heating element 61 having a smaller resistance value is transferred to the other having a larger resistance value, thereby promoting a change in resistance of the resistance heating element having a larger resistance value. For example, when a surge current is applied to a resistance heating element having a resistance value of 5Ω and a resistance heating element having a resistance value of 5.1Ω, the resistance of the resistance heating element having a resistance value of 5Ω decreases to 0.2Ω, causing the temperature to rise to 130°C. However, the resistance of the resistance heating element having a resistance value of 5.1Ω decreases slightly to 4Ω, so that the temperature rises to 45°C. Therefore, even when the difference between the resistance values ​​of the two resistance heating elements is small, a thermal imbalance is temporarily caused between the two thermistors. However, the thermal imbalance decreases or alleviates over time. Here, since the heat generated from the resistance heating element with a resistance value of 5Ω is transferred to the resistance heating element with a resistance value of 5.1Ω, the resistance value of the resistance heating element with a resistance value of 5.1Ω is greatly reduced, the amount of current is increased even in the resistance heating element with a resistance value of 5.1Ω, so that a larger amount of heat is generated even in the resistance heating element with a resistance value of 5.1Ω, thereby alleviating the thermal imbalance between the two resistance heating elements and actually maintaining a certain temperature in a thermal equilibrium state.

[0084] Fig. 9 A state in which the circuit protection device according to the first or second embodiment of the present invention is mounted on a circuit board P is shown.

[0085] Reference Fig. 9 , the extension 72 of the pin 70 of the circuit protection device is inserted to pass through the hole H formed in the circuit board P and is soldered there, so that the circuit protection device is fixed to the circuit board P and electrically connected to the circuit on the circuit board P. Therefore, the length d2 of the extension 72 is formed to be greater than the thickness dP of the circuit board P.

[0086] Meanwhile, in the case of an electronic product such as a washing machine or a dryer to which water is supplied or from which water is generated, the circuit board P includes a molded portion M having a waterproof material such as polyurethane to protect the circuit board P from water. Since the molded portion M is relatively heat-resistant, when the heat generated from the circuit protection device is directly transferred to the molded portion M, the molded portion M may melt and its waterproof performance may deteriorate. Therefore, it is necessary to install the housing 10 of the circuit protection device to be separated from the circuit board P or the molded portion M by a certain interval. The second portion 71b of the pin 70 drawn out from the housing 10 is installed so that the housing 10 is separated from the circuit board P or the molded portion M by a certain interval. The housing 10 is separated from the circuit board P by a height d1 of the second portion 71b. When the thickness of the molded portion M is referred to as dM, the housing 10 is separated from the molded portion M by d1-dM. Therefore, d1 may be greater than dM. In addition, the molded portion M diffuses the heat from the circuit protection device to assist in heat dissipation.

[0087] After a resistance heating element with a diameter of 15Φ and a resistance value of 8Ω (combined resistance of 4Ω) was used for the first resistance heating element 51 and the second resistance heating element 61 in the second embodiment and a current of 4.4A was applied to the circuit protection device for a period of time (15 minutes), the heating temperature of the resistance heating element, the heating temperature of the bottom end of the shell 10 and the heating temperature of the welding part of the circuit board P were measured, and the results are shown in Table 1.

[0088] [Table 1]

[0089]

[0090] As shown in Table 1, the temperature of the bottom end of the housing directly affecting the molded part M or the circuit board P is sufficiently reduced, rather than the temperature of the resistance heating element, and even the temperature of the soldering part of the circuit board P is 73.6°C and 67.8°C, which are allowable values. In particular, due to the heat dissipation function of the polyurethane molded part, the temperature of the bottom end of the housing and the temperature of the soldering part are lower in the case with the polyurethane molded part than in the case without the polyurethane molded part.

[0091] Figures 10 to 13 2 is a view showing components of a circuit protection device according to a third embodiment of the present invention. Fig.10 is a perspective view of a circuit protection device according to a third embodiment. Fig.11A and Fig. 11B It is shown in Fig.10 2 and are cross-sectional views of the first negative temperature coefficient thermistor 20 taken along lines AA and BB, respectively. Fig. 12A and Fig. 12B It is shown in Fig.10 2 and are cross-sectional views of the second negative temperature coefficient thermistor 40 taken along lines CC and DD, respectively. Fig.13The housing 10' contains Fig.10 The negative temperature coefficient thermistors 20 and 40, the fuse 30, etc. are shown in a perspective view of a state in which they are then filled with filler.

[0092] The circuit protection device according to the third embodiment of the present invention includes a housing 10 ′, a first negative temperature coefficient thermistor 20 , a fuse 30 , a second negative temperature coefficient thermistor 40 , a first pin 70_1 , and a second pin 70_2 .

[0093] The housing 10' comprises, for example, a ceramic material, and includes two side walls 11, a front wall 12, a rear wall 13, and a bottom wall 14, thereby forming a receiving groove with an open top, in which the first negative temperature coefficient thermistor 20, the fuse 30, and the second negative temperature coefficient thermistor 40 are received. A first guide groove 15_1 and a second guide groove 15_2 are formed in the rear wall 13 to guide the first pin 70_1 and the second pin 70_2 to be drawn out of the housing 10', respectively.

[0094] like Fig.10 , Fig.11A and Fig. 11B As shown in the figure, the first negative temperature coefficient thermistor 20 includes a first resistance heating element 21, a pair of electrodes 22 and 23 installed on both sides of the first resistance heating element 21, and a first thermistor lead 25 and a second thermistor lead 26 respectively drawn out from the pair of electrodes 22 and 23, and the above components are coated with a coating material 24.

[0095] like Fig.10 , Fig. 12A and Fig. 12B As shown in the figure, the second negative temperature coefficient thermistor 40 includes a second resistance heating element 41, a pair of electrodes 42 and 43 installed on both sides of the second resistance heating element 41, and a third thermistor lead 45 and a fourth thermistor lead 46 respectively drawn out from the pair of electrodes 42 and 43, and the above components are coated with a coating material 44.

[0096] like Fig.10 As shown in , the second thermistor lead 26 of the first negative temperature coefficient thermistor 20 and the first fuse lead 32 of the fuse 30 are connected to each other. The second thermistor lead 26 can be bent and extended to be connectable to the first fuse lead 32 of the fuse 30. In addition, the second fuse lead 33 of the fuse 30 and the third thermistor lead 45 of the second negative temperature coefficient thermistor 40 are connected to each other. The third thermistor lead 45 can be bent and extended to be connectable to the second fuse lead 33. In addition, the connection between the second thermistor lead 26 and the first fuse lead 32, the connection between the second fuse lead 33 and the third thermistor lead 45 can also be performed by brazing, arc welding, spot welding, laser welding, clamping, etc.

[0097] At the same time, the first pin 70_1 and the second pin 70_2 including the conductive material are connected to the circuit board to perform electrical connection between the circuit and the circuit protection device. One end of the first pin 70_1 is connected to the first thermistor lead 25 of the first negative temperature coefficient thermistor 20 in the housing 10', and extends through the first guide groove 15_1 so that the other end thereof is drawn outward from the housing 10'. One end of the second pin 70_2 is connected to the fourth thermistor lead 46 of the second negative temperature coefficient thermistor 40 in the housing 10', and extends through the second guide groove 15_2 so that the other end thereof is drawn outward from the housing 10'.

[0098] In an embodiment of the present invention, when the circuit protection device is mounted on a circuit board, the first pin 70_1 and the second pin 70_2 perform the functions of performing electrical connection between the circuit and the circuit protection device, dissipating heat generated by the circuit protection device, and separating the housing 10' from the circuit board by a specific interval.

[0099] The first pin 70_1 and the second pin 70_2 may include plate-shaped bodies 71_1 and 71_2 and extensions 72_1 and 72_2, respectively, extending from the bodies 71_1 and 71_2, respectively, with widths smaller than the widths of the bodies 71_1 and 71_2. Generally, the extensions 72_1 and 72_2 are portions that are inserted and soldered into holes of a circuit board to perform electrical connection, and the bodies 71_1 and 71_2 are portions that are configured to dissipate heat and space the housing 10' from the circuit board by a certain interval.

[0100] In detail, the first pin 70_1 may include a main body 71_1 and an extension 72_1, one side of the main body 71_1 is connected to the first thermistor lead 25, and the extension 72_1 extends from the other side of the main body 71_1, and the width is less than the width of the main body 71_1. The second pin 70_2 may include a main body 71_2 and an extension 72_2, one side of the main body 71_2 is connected to the fourth thermistor lead 46, and the extension 72_2 extends from the other side of the main body 71_2, and the width is less than the width of the main body 71_2. The first thermistor lead 25, the fourth thermistor lead 46, and the main bodies 71_1 and 71_2 may be connected by brazing, arc welding, spot welding, laser welding, clamping, etc.

[0101] Moreover, the main bodies 71_1 and 71_2 may include first parts 71a_1 and 71a_2 having relatively small widths and second parts 71b_1 and 71b_2 having relatively large widths, respectively. Typically, the first parts 71a_1 and 71a_2 are parts connected to the leads 25 and 46 and inserted into the guide grooves 15_1 and 15_2, while the second parts 71b_1 and 71b_2 are parts drawn outward from the housing 10' to space the housing 10' from the circuit board by a certain interval. In addition, the second parts 71b_1 and 71b_2 may each include one or more protrusions 71c for improving heat dissipation performance.

[0102] Specifically, the main body 71_1 of the first pin 70_1 includes a first portion 71a_1 and a second portion 71b_1, one side of the first portion 71a_1 is connected to the first thermistor lead 25 and inserted into the first guide groove 15_1, and the second portion 71b_1 extends from the other side of the first portion 71a_1, has a width greater than the width of the first portion 72a_1, and is drawn outward from the housing 10'. The main body 71_2 of the second pin 70_2 includes a first portion 71a_2 and a second portion 71b_2, one side of the first portion 71a_2 is connected to the fourth thermistor lead 46 and inserted into the second guide groove 15_2, and the second portion 71b_2 extends from the other side of the first portion 71a_2, has a width greater than the width of the first portion 71a_2, and is drawn outward from the housing 10'.

[0103] Meanwhile, since the negative temperature coefficient thermistors 20 and 40 and the fuse 30 are disposed adjacent to each other in the sealed space in the housing 10', so that the temperature of the circuit protection device or the temperature of its environment increases, there is a concern that even when it is necessary to prevent the fuse 30 from short-circuiting, the fuse 30 will short-circuit due to the heat generated by the negative temperature coefficient thermistors 20 and 40. Therefore, a partition wall 16' may be installed between the fuse body 31 and the resistance heating elements 21 and 41 of the negative temperature coefficient thermistors 20 and 40, so that the fuse body 31 and the resistance heating elements 21 and 41 are maintained above a specific interval. The partition wall 16' may extend from the inner wall (e.g., the rear wall 13) of the housing 10'. The partition wall 16' is installed so as not to completely separate the space accommodating the resistance heating elements 21 and 41 from the space accommodating the fuse body 31, thereby forming a path through which the second thermistor lead 26 and the first fuse lead 32 extend, and forming a path through which the second fuse lead 33 and the third thermistor lead 45 extend. In one embodiment, the partition wall 16 ′ may include a first partition wall 16 a extending from the rear wall 13 and a second partition wall 16 b extending in both directions from one end of the first partition wall 16 a , the second partition wall 16 b having a width substantially corresponding to the length of the fuse body 31 .

[0104] Reference Fig.13The housing 10' is filled with a filler 80 while accommodating the negative temperature coefficient thermistors 20 and 40, the thermal fuse 30, etc. The filler 80 not only supports the negative temperature coefficient thermistors 20 and 40 and the fuse 30 in the accommodating groove, but also enables heat to be effectively dissipated from the negative temperature coefficient thermistors 20 and 40 and the fuse 30.

[0105] Figure 14 to Figure 15 2 is a view showing components of a circuit protection device according to a fourth embodiment of the present invention. Fig.14 is a perspective view of a circuit protection device according to a fourth embodiment. Fig.15 The housing 10 contains Fig.14 1 is a perspective view of a state where the negative temperature coefficient thermistors 50 and 60, the thermal fuse 30, etc. are then filled with a filler.

[0106] In the fourth embodiment, compared with the second embodiment, the first pin 70_1 and the second pin 70_2 are replaced by the first cable 90_1 and the second cable 90_2, respectively. That is, in this embodiment, the circuit protection device is implemented not to be directly mounted on the circuit board, but to be mounted to be separated from the circuit board, and connected to the corresponding terminals of the circuit board using the first cable 90_1 and the second cable 90_2. For convenience, in the fourth embodiment, redundant descriptions overlapping with the second embodiment will be omitted.

[0107] The first cable 90_1 and the second cable 90_2 each include a conductive wire 91 and a sheath 92 covering the conductive wire 91. The first cable 90_1 and the second cable 90_2 may be harness cables.

[0108] In the first cable 90_1, one end of the conductive wire 91 is connected to the first thermistor lead 55 of the first negative temperature coefficient thermistor 50 and the third thermistor lead 65 of the second negative temperature coefficient thermistor 60 in the housing 10, and the conductive wire 91 extends through the first guide slot 15_1 so that the other end thereof is pulled outward from the housing 10. In the second cable 90_2, one end of the conductive wire 91 is connected to the second fuse lead 33 of the fuse 30 in the housing 10, and the conductive wire 91 extends through the second guide slot 15_2 so that the other end thereof is pulled outward from the housing 10.

[0109] Since the circuit protection device according to the fourth embodiment is mounted separately from the circuit board, there is an advantage that heat generated at the circuit protection device is not transferred to the circuit board at all.

[0110] In the fourth embodiment, although it has been described that the first pin 70_1 and the second pin 70_2 of the second embodiment are replaced by the first cable 90_1 and the second cable 90_2 respectively, the first pin 70_1 and the second pin 70_2 of the first and third embodiments may also be replaced by the first cable 90_1 and the second cable 90_2 respectively.

[0111] The circuit protection device according to the present invention can replace the current protection device including the fuse resistor RF, the first relay S1 and the second relay S2. Since the circuit protection device includes the negative temperature coefficient thermistor and the fuse, which are relatively low in price, the cost can be reduced. Compared with the relay, the negative temperature coefficient thermistor and the fuse have a small volume and occupy less space. In addition, since the relay is not used, the risk of overcurrent or fire caused by the failure of the relay can be fundamentally eliminated.

[0112] Exemplary embodiments of the present invention have been described above. It will be appreciated by those skilled in the art that the present invention may be implemented in a modified form without departing from the basic features of the present invention. Therefore, the disclosed embodiments should not be considered restrictive, but descriptive. The scope of the present invention is shown in the claims rather than in the above description, and all differences within their equivalent ranges should be interpreted as included in the present invention.

Claims

1. A circuit protection device, comprising: case; a first negative temperature coefficient thermistor accommodated in the housing and comprising a first resistance heating element, a pair of electrodes mounted on both sides of the first resistance heating element, and a first thermistor lead and a second thermistor lead respectively drawn out from the pair of electrodes; a fuse accommodated in the housing and comprising a fuse body and first and second fuse leads respectively connected to both ends of the fuse body; as well as a second negative temperature coefficient thermistor, which is accommodated in the housing and includes a second resistance heating element, a pair of electrodes mounted on both sides of the second resistance heating element, and a third thermistor lead and a fourth thermistor lead respectively drawn out from the pair of electrodes, wherein the fuse body comprises a fuse rod having a plating layer formed thereon and a pair of fuse caps coupled to both ends of the fuse rod and having conductivity, and the first fuse lead and the second fuse lead are respectively joined to the pair of fuse caps, and wherein the second thermistor lead and the first fuse lead are connected to each other in the housing, and the second fuse lead and the third thermistor lead are connected to each other, wherein the housing comprises a partition wall extending from an inner wall of the housing and disposed between the first resistance heating element, the second resistance heating element and the fuse body, and The partition wall includes: a first partition wall extending from a rear wall of the housing; and a second partition wall extending from one end of the first partition wall in two directions and having a width corresponding to a length of the fuse body.

2. The circuit protection device according to claim 1, further comprising: a first pin connected to the first thermistor lead; as well as The second pin is connected to the fourth thermistor lead, A first guide groove and a second guide groove are formed in the housing, wherein the first guide groove is configured to guide the first pin to be withdrawn outward from the housing, and the second guide groove is configured to guide the second pin to be withdrawn outward from the housing.

3. The circuit protection device of claim 2, wherein the first pin and the second pin respectively include a plate-shaped body, one side of each of the plate-shaped bodies is connected to the first thermistor lead and the fourth thermistor lead, respectively, and the first pin and the second pin each include at least one extension extending from the other side of the body and having a width smaller than a width of the body.

4. The circuit protection device according to claim 3, wherein the main bodies of the first pin and the second pin include a first portion and a second portion, one side of the first portion of the two is respectively connected to the first thermistor lead and the fourth thermistor lead, and is respectively inserted into the first guide groove and the second guide groove, and the second portion of the two extends from the other side of the first portion, has a width greater than the width of the first portion, and is drawn outward from the housing.

Images