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 installed on both sides of the resistance heating element, and a first lead and a second lead respectively led from the pair of electrodes; and a thermal fuse, which is accommodated in the housing and includes a thermal fuse body; and a third lead and a fourth lead respectively connected to both ends of the thermal fuse body. Here, the second lead and the third lead are connected to each other in the housing.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to and the benefit of Korean Patent Application No. 2019-0113185, filed on September 12, 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] In this circuit protection device, a state (a) in which the first relay S1 is closed and the second relay S2 is open during driving is converted to a state (b) in which the first relay S1 is open and the second relay S2 is closed after a certain time.

[0007] In state (a), the input current passes through the fuse resistor RF and the first relay S1 and is input to the circuit. 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 circuit is short-circuited to melt the fused body including the solid lead or polymer particles disposed inside the thermal fuse F, thereby protecting the circuit of the household appliance. After a certain time (e.g., about 0.5 seconds) when the surge current disappears and the input current stabilizes, 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, 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 more 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 and closing the first relay S1 and the second relay S2 is repeatedly performed every time the electronic product is turned on or off, its durability is reduced. Therefore, when the electronic product is used for a long time, a malfunction may occur. The malfunction of the first relay S1 and the second relay S2 may cause an inflow of an 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] The present invention is directed to providing a circuit protection device which 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, a circuit protection device is provided, comprising: a housing; a negative temperature coefficient thermistor, which is accommodated in the housing and includes a resistance heating element, a pair of electrodes installed on both sides of the resistance heating element, and a first lead and a second lead respectively led from the pair of electrodes; and; and a thermal fuse, which is accommodated in the housing and includes a thermal fuse body and a third lead and a fourth lead respectively connected to both ends of the thermal fuse body. Here, the second lead and the third lead are connected to each other in the housing.

[0013] The circuit protection device may further include a first pin connected to the first lead and a second pin connected to the fourth 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 led outward from the housing, and the second guide groove being configured to guide the second pin to be led outward from the housing.

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

[0015] The bodies of the first pin and the second pin may respectively include a first part connected to the first lead on one side and inserted into the first guide groove and a first part connected to the fourth lead on one side and inserted into the second guide groove, and may each include a second part extending from the other side of the first part on one side and having a width greater than that of the first part and leading outward 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 thermal 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 lead and a second lead respectively led 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 lead and a fourth lead respectively led from the pair of electrodes; and a thermal fuse, which is accommodated in the housing and includes a thermal fuse body, and a fifth lead and a sixth lead respectively connected to both ends of the thermal fuse body. Here, the first lead and the third lead are connected to each other in the housing, and the second lead, the fourth lead, and the fifth lead are connected to each other in the housing.

[0018] The circuit protection device may further include a first pin connected to the first lead and the third lead and a second pin connected to the sixth 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 led outward from the housing, and the second guide groove being configured to guide the second pin to be led outward from the housing.

[0019] The first pin may include a plate-shaped body connected at one side to the first lead and the third lead, 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.

[0020] The body of the first pin may include a first portion connected to the first lead and the third lead at one side and inserted into the first guide groove, and may include a second portion extending from the other side of the first portion and having a width greater than that of the first portion to be located outside the housing.

[0021] The second pin may include a plate-shaped body connected to the sixth lead at one side, and may include at least one extension portion extending from the other side of the body and having a width smaller than that of the body.

[0022] The body of the second pin may include a first portion connected to the sixth lead at one side and inserted into the second guide groove, and may include a second portion extending from the other side of the first portion and having a width greater than that of the first portion to be located outside the housing.

[0023] The housing may include a partition wall extending from an inner wall of the housing and disposed between the thermal fuse body and the first and second resistance heating elements.

[0024] The first resistance heating element and the second resistance heating element may be disposed to face each other.

[0025] The circuit protection device may include a first cable and a second cable, one end of the first cable is connected to the first lead and the third lead, and one end of the second cable is connected to the sixth lead. Here, a first guide groove and a second guide groove may be formed in the housing, the first guide groove is configured to guide the first cable to be led out of the housing, and the second guide groove is configured to guide the second cable to be led out of the housing. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] 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:

[0027] Figure 1 The components and operation of a conventional circuit protection device are shown;

[0028] Figure 2 is a perspective view of a circuit protection device according to a first embodiment of the present invention;

[0029] Figure 3A and Figure 3B are cross-sectional views of the negative temperature coefficient thermistor 20 taken along lines AA and BB, respectively;

[0030] Figure 4 The housing 10 is shown as receiving Figure 2A perspective view of the negative temperature coefficient thermistor 20, thermal fuse 30, etc., shown in FIG. 3, and then filled with filler;

[0031] Figure 5 is a perspective view of a circuit protection device according to a second embodiment of the present invention;

[0032] Fig. 6A and Figure 6B are cross-sectional views of negative temperature coefficient thermistors 50 and 60 taken along lines AA and BB, respectively;

[0033] Figure 7 The housing 10 is shown as receiving Figure 5 A perspective view of the negative temperature coefficient thermistors 50 and 60, the thermal fuse 30, etc., shown in FIG. 3 , and then filled with filler;

[0034] Figure 8 The circuit protection device according to the first or second embodiment of the present invention is shown as being mounted on a circuit board;

[0035] Fig. 9 is a perspective view of a circuit protection device according to a third embodiment of the present invention;

[0036] Fig.10 The housing 10 is shown as receiving Fig. 9 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. DETAILED DESCRIPTION

[0037] 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 denoted by the same reference numerals, and repeated descriptions thereof will be omitted. In addition, in the description of the embodiments of the present invention, if a detailed description of a known function or component of the prior art would obscure the understanding of the embodiments of the present invention, such detailed description will be omitted.

[0038] Figures 2 to 4 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 are cross-sectional views of the negative temperature coefficient thermistor 20 taken along lines AA and BB, respectively. Figure 4 The housing 10 is shown as receiving Figure 2 2 is a perspective view of a state where the negative temperature coefficient thermistor 20, the thermal fuse 30, etc. are then filled with a filler.

[0039] The circuit protection device according to the first embodiment of the present invention includes a housing 10 , a negative temperature coefficient thermistor 20 , a thermal fuse 30 , a first pin 40_1 , and a second pin 40_2 .

[0040] The housing 10 includes, for example, a ceramic material, and includes a side wall 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 thermal fuse 30 are received. A first guide groove 15_1 and a second guide groove 15_2 are formed on the rear wall 13 to guide the first pin 40_1 and the second pin 40_2 to be led out from the housing 10.

[0041] like Figures 2 to 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, a first lead 25 and a second lead 26 respectively led out from the pair of electrodes 22 and 23, and all of the above components are coated with a coating material 24.

[0042] 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 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.

[0043] The thermal fuse 30 includes a thermal fuse body 31 and a third lead 32 and a fourth lead 33 respectively connected to both ends of the thermal fuse body 31. Typically, the thermal fuse body 31 includes an insulating ceramic rod having a certain length and a fusion body, and the third lead 32 and the fourth lead 33 can be connected to conductive covers respectively mounted on both ends of the ceramic rod.

[0044] like Figure 2 As shown in FIG. 1 , the second lead 26 of the negative temperature coefficient thermistor 20 and the third lead 32 of the thermal fuse body 31 are connected to each other. The second lead 26 and the third lead 32 may be connected by welding, arc welding, spot welding, laser welding, clamping, or the like.

[0045] At the same time, the first pin 40_1 and the second pin 40_2 as conductive materials are connected to the circuit board to perform electrical connection between the circuit and the circuit protection device. One end of the first pin 40_1 is connected to the first lead 25 of the 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 led outward from the housing 10. One end of the second pin 40_2 is connected to the fourth lead 33 of the thermal fuse 30 in the housing 10, and extends through the second guide groove 15_2 so that the other end thereof is led outward from the housing 10.

[0046] In an embodiment of the present invention, when the circuit protection device is mounted on a circuit board, the first pin 40_1 and the second pin 40_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 certain interval.

[0047] The first pin 40_1 and the second pin 40_2 may include plate-shaped bodies 41_1 and 41_2 and extensions 42_1 and 42_2 extending from the bodies 41_1 and 41_2, respectively, with a width smaller than that of the bodies 41_1 and 41_2. Generally, the extensions 42_1 and 42_2 are portions that are inserted into holes of a circuit board and are soldered to perform electrical connection, and the bodies 41_1 and 41_2 are portions that are configured to dissipate heat and space the housing 10 from the circuit board at a certain interval.

[0048] In detail, the first pin 40_1 may include a body 41_1 and an extension 42_1, one side of the body 41_1 is connected to the first lead 25, and the extension 42_1 extends from the other side of the body 41_1, and the width is smaller than the width of the body 41_1. The second pin 40_2 may include a body 41_2 and an extension 42_2, one side of the body 41_2 is connected to the fourth lead 33, and the extension 42_2 extends from the other side of the body 41_2, and the width is smaller than the width of the body 41_2. The first lead 25, the fourth lead 33, and the bodies 41_1 and 41_2 may be connected by welding, arc welding, spot welding, laser welding, clamping, etc.

[0049] Moreover, the main bodies 41_1 and 41_2 may include first portions 41a_1 and 41a_2 having relatively small widths and second portions 41b_1 and 41b_2 having relatively large widths. Typically, the first portions 41a_1 and 41a_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 41b_1 and 41b_2 are portions that are led outward from the housing 10 to space the housing 10 from the circuit board by a certain interval. In addition, the second portions 41b_1 and 41b_2 may include one or more protrusions 41c configured to improve heat dissipation performance.

[0050] In detail, the body 41_1 of the first pin 40_1 includes a first portion 41a_1 and a second portion 41b_1, one side of the first portion 41a_1 is connected to the first lead 25 and inserted into the first guide groove 15_1, and the second portion 41b_1 extends from the other side of the first portion 41a_1, has a width greater than the width of the first portion 42a_1, and is led outward from the housing 10. The body 41_2 of the second pin 40_2 includes a first portion 41a_2 and a second portion 41b_2, one side of the first portion 41a_2 is connected to the fourth lead 33 and inserted into the second guide groove 15_2, and the second portion 41b_2 extends from the other side of the first portion 41a_2, has a width greater than the width of the first portion 41a_2, and is led outward from the housing 10.

[0051] Meanwhile, since the negative temperature coefficient thermistor 20 and the thermal fuse 30 are disposed adjacent to each other in the sealed space in the housing 10, the temperature of the circuit protection device or the temperature of its environment is increased, so the thermal fuse 30 may be short-circuited due to the heating of the negative temperature coefficient thermistor 20. Therefore, a partition wall 16 may be installed between the resistance heating element 21 and the thermal fuse body 31 so as to maintain a certain interval or more between the resistance heating element 21 of the negative temperature coefficient thermistor 20 and the thermal fuse body 31. The partition wall 16 may extend from an inner wall of the housing 10, such as the bottom wall 14 or the rear wall 13. The partition wall 16 is installed so as not to completely separate the two spaces, thereby forming a path for the second lead 26 and the third lead 32 to extend.

[0052] Reference Figure 4 When the negative temperature coefficient thermistor 20, the thermal fuse 30, etc. are accommodated in the housing 10, the housing 10 is filled with a filler 80. The filler 80 not only supports the negative temperature coefficient thermistor 20 and the thermal fuse 30 in the accommodation groove, but also enables heat to be effectively dissipated from the negative temperature coefficient thermistor 20 and the thermal fuse 30. Therefore, the filler 80 can be a material with high heat dissipation.

[0053] 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, a large resistance value is used to limit the surge current to a certain current when driving, and a resistance value that decreases due to temperature increase is used to maintain a normal input current after a certain time. At the same time, when the negative temperature coefficient thermistor 20 is overheated due to an overcurrent inflow caused by circuit abnormality or an abnormal rise in ambient temperature, the thermal fuse 30 short-circuits and cuts off the current inflow to prevent fire. Therefore, the circuit protection device according to the first embodiment can replace Figure 1In 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 less space is occupied. In addition, since no relay is used, the risk factor caused by the failure of the relay can be fundamentally eliminated.

[0054] Meanwhile, in the case of large household appliances such as air conditioners, washing machines, refrigerators, dryers, etc., since the circuit protection device must adapt to large currents, a circuit protection device with good heating characteristics is required. In the case of the first embodiment, in order to reduce the calorific value 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 calorific value by simply increasing the size of the negative temperature coefficient thermistor 20.

[0055] Therefore, hereinafter, as an embodiment in which the heat generation of the circuit protection device is reduced without increasing the size of the negative temperature coefficient thermistor and having all the advantages of the first embodiment, an embodiment in which two negative temperature coefficient thermistors are connected in parallel to reduce the amount of heat generation using their reduced combined resistance value is provided. For convenience, in the following embodiments, redundant descriptions overlapping with the first embodiment will be omitted.

[0056] Figures 5 to 7 2 is a view showing components of a circuit protection device according to a second embodiment of the present invention. Figure 5 is a perspective view of a circuit protection device according to a second embodiment. Fig. 6A and Figure 6B are cross-sectional views of the negative temperature coefficient thermistors 50 and 60 taken along lines AA and BB, respectively. Figure 7 The housing 10 is shown as housing Figure 5 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.

[0057] 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 thermal fuse 30 , a first pin 40_1 , and a second pin 40_2 .

[0058] 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 thermal fuse 30 are received. The first guide groove 15_1 and the second guide groove 15_2 are formed on the rear wall 13 to guide the first pin 40_1 and the second pin 40_2 to be led out from the housing 10.

[0059] like Figures 5 to 6B As shown in , the first negative temperature coefficient thermistor 50 includes a first resistance heating element 51, a pair of electrodes 52 and 53 installed on both sides of the first resistance heating element 51, a first lead 55 and a second lead 56 respectively led out from the pair of electrodes 52 and 53, and all of the above components are coated with a coating material 54. Like 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 installed on both sides of the second resistance heating element 61, and a third lead 65 and a fourth lead 66 respectively led out from the pair of electrodes 63 and 63, and all of the above components are coated with a coating material 54.

[0060] The thermal fuse 30 includes a thermal fuse body 31 , and a fifth lead 32 and a sixth lead 33 connected to both ends of the thermal fuse body 31 , respectively.

[0061] Reference Figures 5 to 6B , the first lead 55 of the first NTC thermistor 50 and the third lead 65 of the second NTC thermistor 60 are connected to each other, and the second lead 56 of the first NTC thermistor 50 and the fourth lead 66 of the second NTC thermistor 60, and the fifth lead 32 of the thermal fuse 30 are connected to each other. These leads may be connected by welding, arc welding, spot welding, laser welding, clamping, etc.

[0062] One end of the first pin 40_1 is connected to the first lead 55 of the first NTC thermistor 50 and the third lead 65 of the second NTC thermistor 60 in the housing 10. One end of the second pin 40_2 is connected to the sixth lead 33 of the thermal fuse 30 in the housing 10.

[0063] The first pin 40_1 may include a main body 41_1 and an extension 42_1, one side of the main body 41_1 is connected to the first lead 55 and the third lead 65, and the extension 42_1 extends from the other side of the main body 41_1, and the width is smaller than the width of the main body 41_1. The second pin 40_2 may include a main body 41_2 and an extension 42_2, one side of the main body 41_2 is connected to the sixth lead 33, and the extension 42_2 extends from the other side of the main body 41_2, and the width is smaller than the width of the main body 41_2. The lead may be connected to the main body by welding, arc welding, spot welding, laser welding, clamping, etc.

[0064] The body 41_1 of the first pin 40_1 includes a first portion 41a_1 and a second portion 41b_1, one side of the first portion 41a_1 is connected to the first lead 55 and the third lead 65 and is inserted into the first guide groove 15_1, and the second portion 41b_1 extends from the other side of the first portion 41a_1, has a width greater than the width of the first portion 42a_1, and is led outward from the housing 10. The body 41_2 of the second pin 40_2 includes a first portion 41a_2 and a second portion 41b_2, one side of the first portion 41a_2 is connected to the sixth lead 33 and is inserted into the second guide groove 15_2, and the second portion 41b_2 extends from the other side of the first portion 41a_2, has a width greater than the width of the first portion 41a_2, and is led outward from the housing 10.

[0065] Meanwhile, a partition wall 16 may be installed between the thermal 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 between the thermal fuse body 31 and the first and second resistance heating elements 51 and 61 .

[0066] Reference Figure 7 In a state where the first and second negative temperature coefficient thermistors 50 and 60, the thermal fuse 30, etc. are accommodated in the housing 10, the housing 10 is filled with a filler 80. The filler 80 not only supports the first and second negative temperature coefficient thermistors 50 and 60 and the thermal fuse 30 in the accommodation groove, but also enables heat to be effectively dissipated from the first and second negative temperature coefficient thermistors 50 and 60 and the thermal fuse 30.

[0067] 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.

[0068] 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 is 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 by the first resistance heating element 51 or the second resistance heating element 61 alone.

[0069] 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 larger resistance value is transferred to the other having a smaller resistance value therein, thereby promoting a change in resistance of the resistance heating element having a smaller 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 slightly decreases to 4Ω, causing the temperature to rise 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, and even in the resistance heating element with a resistance value of 5.1Ω, the amount of current is increased, so that heat is further 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.

[0070] Figure 8 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.

[0071] Reference Figure 8 , the extension 42 of the pin 40 of the circuit protection device is inserted to pass through the hole H formed in the circuit board P and is soldered, 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 is formed to be greater than the thickness dP of the circuit board P.

[0072] 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, a molded part M having a waterproof material such as urethane is used to mold the circuit board P to protect the circuit board P from water. Since the molded part M is relatively heat-averse, when the heat generated from the circuit protection device is directly transferred to the molded part M, the molded part M may melt and destroy the waterproof performance. 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 part M by a certain interval. The second part 41b of the pin 40 led outward from the housing 10 is installed so that the housing 10 is separated from the circuit board P or the molded part M by a certain interval. The housing 10 is separated from the circuit board P by a height d1 of the second part 41b. When the thickness of the molded part M is expressed as dM, the housing 10 is separated from the molded part M by d1-dM. Therefore, d1 may be greater than dM. In addition, the molded part M diffuses the heat from the circuit protection device to assist in heat dissipation.

[0073] 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 certain 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.

[0074] [Table 1]

[0075]

[0076] As shown in Table 1, the temperature of the bottom end of the case 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 portion 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 urethane molded part, the temperature of the bottom end of the case and the temperature of the soldering portion are lower in the case with the urethane molded part than in the case without the urethane molded part.

[0077] Figures 9 and 10 2 is a view showing components of a circuit protection device according to a third embodiment of the present invention. Fig. 9 is a perspective view of a circuit protection device according to a third embodiment. Fig.10 The housing 10 is shown as receiving Fig. 9 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.

[0078] Compared with the second embodiment, in the third embodiment, the first pin 40_1 and the second pin 40_2 are replaced by the first cable 70_1 and the second cable 70_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 separately from the circuit board, and connected to the corresponding terminals of the circuit board using the first cable 70_1 and the second cable 70_2. For convenience, in the third embodiment, redundant descriptions overlapping with the second embodiment will be omitted.

[0079] The first cable 70_1 and the second cable 70_2 each include a conductive wire 71 and a coating 72 covering the conductive wire 71. The first cable 70_1 and the second cable 70_2 may be harness cables.

[0080] In the first cable 70_1, one end of the wire 71 is connected to the first lead 55 of the first negative temperature coefficient thermistor 50 and the third lead 65 of the second negative temperature coefficient thermistor 60 in the housing 10, and extends through the first guide slot 15_1 so that the other end thereof is led outward from the housing 10. In the second cable 70_2, one end of the wire 71 is connected to the sixth lead 33 of the thermal fuse 30 in the housing 10, and extends through the second guide slot 15_2 so that the other end thereof is led outward from the housing 10.

[0081] Since the circuit protection device according to the third 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.

[0082] The circuit protection device according to the present invention can replace the circuit protection device including the fuse resistor RF, the first relay S1 and the second relay S2, and includes a low-priced negative temperature coefficient thermistor and a thermal fuse, thereby reducing the cost. In addition, the negative temperature coefficient thermistor and the thermal fuse have a small volume compared with the relay to occupy less space, and without using a relay, the risk of overcurrent or fire caused by a fault of the relay can be fundamentally eliminated.

[0083] 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 will be 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 negative temperature coefficient thermistor housed in the housing and comprising a resistance heating element, a pair of electrodes mounted on both sides of the resistance heating element, and a first lead and a second lead respectively led from the pair of electrodes; and a thermal fuse housed in the housing and comprising a thermal fuse body and a third lead and a fourth lead respectively connected to both ends of the thermal fuse body, wherein the second lead and the third lead are connected to each other in the housing, wherein the housing comprises a partition wall extending from an inner wall of the housing and disposed between the resistance heating element and the thermal fuse body, wherein the partition wall extends beyond the length of the thermal fuse body, and The partition wall is installed so as not to completely separate a space where the resistance heating element is disposed and a space where the thermal fuse body is disposed.

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

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

4. The circuit protection device according to claim 3, wherein: The bodies of the first pin and the second pin respectively include a first part connected to the first lead on one side and inserted into the first guide groove and a first part connected to the fourth lead on one side and inserted into the second guide groove, and each includes a second part extending from the other side of the first part on one side, having a width greater than that of the first part and leading outward from the shell.

5. 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 lead and a second lead respectively led from the pair of electrodes; a second negative temperature coefficient thermistor accommodated in the housing and comprising a second resistance heating element, a pair of electrodes mounted on both sides of the second resistance heating element, and a third lead and a fourth lead respectively led from the pair of electrodes; and a thermal fuse housed in the housing and comprising a thermal fuse body, and fifth and sixth leads respectively connected to both ends of the thermal fuse body, wherein the first lead and the third lead are connected to each other in the housing, and wherein the second lead, the fourth lead and the fifth lead are connected to each other in the housing, wherein the housing includes a partition wall extending from an inner wall of the housing and disposed between the thermal fuse body and the first resistance heating element and the second resistance heating element, wherein the partition wall extends beyond the length of the thermal fuse body, and The partition wall is installed so as not to completely separate a space where the first resistance heating element and the second resistance heating element are disposed and a space where the thermal fuse body is disposed.

6. The circuit protection device according to claim 5, further comprising: a first pin connected to the first lead and the third lead; as well as The second pin is connected to the sixth lead, A first guide groove and a second guide groove are formed in the housing, the first guide groove is configured to guide the first pin to be led out of the housing, and the second guide groove is configured to guide the second pin to be led out of the housing.

7. The circuit protection device according to claim 6, wherein: The first pin includes a plate-shaped body having one side connected to the first lead and the third lead, and includes at least one extension extending from the other side of the body and having a width smaller than that of the body.

8. The circuit protection device according to claim 7, wherein: The body includes a first portion having one side connected to the first lead and the third lead and inserted into the first guide groove, and includes a second portion extending from the other side of the first portion and having a width greater than that of the first portion to be located outside the housing.

9. The circuit protection device according to claim 6, wherein: The second pin includes a plate-shaped body having one side connected to the sixth lead, and includes at least one extension portion extending from the other side of the body and having a width smaller than that of the body.

10. The circuit protection device according to claim 9, wherein: The body includes a first portion having one side connected to the sixth lead and inserted into the second guide groove, and includes a second portion extending from the other side of the first portion and having a width greater than that of the first portion to be located outside the housing.

11. The circuit protection device according to claim 5, wherein: The first resistance heating element and the second resistance heating element are disposed to face each other.

12. The circuit protection device according to claim 5, further comprising: a first cable having one end connected to the first lead and the third lead; as well as a second cable, one end of which is connected to the sixth lead, A first guide groove and a second guide groove are formed in the housing, the first guide groove is configured to guide the first cable to be led out of the housing, and the second guide groove is configured to guide the second cable to be led out of the housing.

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