Thermal fuse and household appliance

Abstract

The utility model discloses a thermal fuse and a household electrical appliance. The thermal fuse comprises a metal housing; a first lead; the PTC resistor is electrically connected with the inner side end, extending into the metal shell, of the first lead; the circuit breaking spring sleeves the outer side of the PTC resistor, and one end of the circuit breaking spring abuts against the insulator; the star-shaped reed is in contact with the inner side wall of the metal shell, and the other end of the circuit breaking spring abuts against the star-shaped reed; one end of the elastic body abuts against the star-shaped reed, and the other end of the elastic body abuts against the temperature sensing body; one end of the heat conduction block is in contact with the PTC resistor, and the other end is in contact with the temperature sensing body; the second lead is connected with the metal shell; the temperature sensing body has a melting temperature, when the temperature sensing body is not melted, the circuit breaking spring and the elastic body act together to enable the PTC resistor and the heat conduction block to make close contact with the star-shaped reed, and when the temperature sensing body is melted, the circuit breaking spring and the elastic body release elastic force to push the star-shaped reed to be disengaged from the PTC resistor. According to the utility model, the heater can be reliably protected.

Description

Technical Field

[0001] The utility model relates to the technical field of thermal fuses, in particular to a thermal fuse and a household appliance with the thermal fuse. Background Art

[0002] In household appliances (such as refrigerators, air conditioners, etc.), heaters are sometimes configured for defrosting and heating. To prevent the heater from continuously heating and causing high temperature or even fire, a thermal fuse is usually connected in series to the power supply line of the heater. When the temperature sensed by the thermal fuse reaches a certain value, the internal circuit of the thermal fuse will be disconnected, and the heater will not work.

[0003] The melting temperature of the existing thermal fuse is 68±5°C, that is, when the temperature sensed by the temperature-sensitive body inside the thermal fuse reaches about 68°C, the internal circuit of the thermal fuse will be disconnected. At this time, the heater will no longer be able to heat.

[0004] However, this type of thermal fuse is mainly sensitive to temperature and insensitive to the current flowing through the thermal fuse. Even if the current continuously flowing through the thermal fuse reaches about 10A, or when the heater generates a large current of dozens of amperes instantaneously during a spark (for example, when the internal conductive components of a steel pipe heater (such as a conductive rod, heating wire) have poor insulation (such as magnesium powder getting damp, impurities in the insulation layer, etc.) and spark to the steel pipe shell), a high temperature will be generated around a certain spark point. If the thermal fuse is installed at a position far from the spark point, the heat generated by the spark cannot cause the thermal fuse to reach the melting temperature, and the thermal fuse will not melt. Therefore, the sparking will continue. When the sparking is severe to a certain extent, it will char or even ignite the plastic parts around the steel pipe heater, such as the inner liner, air duct cover plate, foaming material, etc.

[0005] Therefore, the existing thermal fuse can prevent the high temperature and fire hazards caused by the continuous heating of the heater, but it cannot prevent the fire hazards caused by the local short circuit of the internal conductive components of the heater to the ground or the generation of local large current due to sparking. Summary of the Utility Model

[0006] Some embodiments of the present application provide a thermal fuse that uses a PTC resistor to convert the local large current flowing through the thermal fuse into heat and transfer it to the temperature-sensitive body, avoiding the fire hazard caused by the failure of the internal conductive components of the heater.

[0007] To achieve the above utility model purpose, some embodiments of the present utility model adopt the following technical solutions:

[0008] Some embodiments of the present application relate to a thermal fuse, including:

[0009] A metal shell;

[0010] The first lead is wrapped around one end of the metal housing and extends into the metal housing through an insulator located within the metal housing;

[0011] The PTC resistor is electrically connected to the inner end of the first lead extending into the metal housing;

[0012] The break spring is sleeved outside the PTC resistor and one end thereof abuts against the insulator;

[0013] The star-shaped spring piece is located within the metal housing and contacts the inner side wall of the metal housing, and the other end of the break spring abuts against the star-shaped spring piece;

[0014] The elastic body is located within the metal housing, one end thereof abuts against the star-shaped spring piece and the other end abuts against the temperature-sensitive body;

[0015] The heat-conducting block is located within the elastic body, one end thereof contacts the PTC resistor and the other end contacts the temperature-sensitive body;

[0016] The second lead is connected to the metal housing;

[0017] Wherein, the temperature-sensitive body has a melting temperature. When the temperature-sensitive body is not melted, the break spring and the elastic body act together to make the PTC resistor and the heat-conducting block respectively in close contact with the star-shaped spring piece. When the temperature-sensitive body is melted, the break spring and the elastic body release elastic force to push the star-shaped spring piece to be separated from contact with the PTC resistor.

[0018] The thermal fuse involved in some embodiments of the present application has the following advantages and beneficial effects:

[0019] (1) When the temperature-sensitive body senses that the surrounding temperature has not reached its melting temperature, the temperature-sensitive body is not melted. At this time, the circuit formed by connecting the first lead, the PTC resistor, the star-shaped spring piece, the metal housing and the second lead in sequence is connected, so that the thermal fuse is in a normal protection state. When the temperature-sensitive body senses that the surrounding temperature rises to the melting temperature, the temperature-sensitive body is melted. At this time, the elastic restoring force of the break spring makes the star-shaped spring piece bounce away from the PTC resistor. Thus, the above-mentioned circuit is disconnected, realizing the open-circuit protection of the thermal fuse in the case of a relatively high surrounding temperature;

[0020] (2) When a high current is generated due to a fault in the internal conductive components of the heater, the PTC resistor generates high heat due to the increase in current. This heat is sequentially transferred to the temperature-sensitive body through the star-shaped spring piece 510C and the heat-conducting block. When the temperature of the temperature-sensitive body reaches the melting temperature due to the heat generated by the increase in current, the temperature-sensitive body is melted, and the elastic restoring force of the break spring makes the star-shaped spring piece bounce away from the PTC resistor. Thus, the above-mentioned circuit is disconnected, realizing the open-circuit protection of the thermal fuse in the case of high temperature generated due to the change in the flowing current.

[0021] In some embodiments of the present application, the thermal fuse further includes:

[0022] A sealing resin, which is disposed at the connection end of the metal housing and the first lead.

[0023] The sealing resin is used to fix the first lead and prevent the contact between the first lead, the PTC resistor and the star-shaped spring from loosening.

[0024] In some embodiments of the present application, the thermal fuse further includes:

[0025] A first heat conducting sheet, which is clamped between the side of the star-shaped spring away from the first lead and one end of the heat conducting block, and does not contact the inner side wall of the metal housing;

[0026] A second heat conducting sheet, which is clamped between the other end of the heat conducting block and the temperature sensing body, and does not contact the inner side wall of the metal housing.

[0027] The arrangement of the first heat conducting sheet and the second heat conducting sheet increases the contact area and the force-bearing area between the heat conducting block and the star-shaped spring and the temperature sensing body respectively. When the temperature sensing body is not melted, the contact reliability between the star-shaped spring and the temperature sensing body and the heat conducting block is improved. When the temperature sensing body is melted, the uniformity of the force applied by the open circuit spring to push the star-shaped spring towards the heat conducting block is improved.

[0028] In some embodiments of the present application, the star-shaped spring is formed by a sheet-shaped metal thin plate.

[0029] In some embodiments of the present application, the star-shaped spring has a plurality of arc-shaped claws arranged in a radioactive manner, and a chamfer for contacting the inner side wall of the metal housing is formed at the free end of each claw.

[0030] The use of chamfered contact facilitates the reliability of the open circuit spring to push the star-shaped spring towards the heat conducting block after the temperature sensing body is melted.

[0031] In some embodiments of the present application, the elastic body is a spring.

[0032] In some embodiments of the present application, the insulator is a ceramic insulator.

[0033] In some embodiments of the present application, the insulator includes:

[0034] A first boss, whose outer side wall contacts the inner side wall of the metal housing;

[0035] A second boss, having a cross-sectional area smaller than that of the first boss, with the first lead passing through the first boss and the second boss and extending into the metal housing, and the open circuit spring sleeved outside the second boss and abutting against one side of the first boss facing the second boss.

[0036] Some embodiments of the present application also relate to a household appliance, comprising:

[0037] A heater for generating heat during operation;

[0038] A thermal fuse, comprising:

[0039] A metal housing;

[0040] A first lead, which is wrapped and disposed at one end of the metal housing and passes through an insulator located within the metal housing and extends into the metal housing, with the free end of the first lead connected to the power supply line of the heater;

[0041] A PTC resistor electrically connected to the inner end of the first lead extending into the metal housing;

[0042] An open circuit spring sleeved outside the PTC resistor and having one end abutting against the insulator;

[0043] A star-shaped spring piece located within the metal housing and in contact with the inner side wall of the metal housing, with the other end of the open circuit spring abutting against the star-shaped spring piece;

[0044] An elastomer located within the metal housing, having one end abutting against the star-shaped spring piece and the other end abutting against a temperature-sensitive body;

[0045] A heat conducting block located within the elastomer, having one end in contact with the PTC resistor and the other end in contact with the temperature-sensitive body;

[0046] A second lead, having one end connected to the metal housing and the other end connected to the power supply line;

[0047] Wherein, the temperature-sensitive body has a melting temperature. When the temperature-sensitive body is not melted, the open circuit spring and the elastomer act together to make the PTC resistor and the heat conducting block respectively in close contact with the star-shaped spring piece. When the temperature-sensitive body melts, the open circuit spring and the elastomer release elastic force to push the star-shaped spring piece out of contact with the PTC resistor.

[0048] For the household appliance as described above, the heater can be used for example for heating and defrosting treatment, and the thermal fuse is used for high-temperature protection to avoid the potential risk of fire.

[0049] In some embodiments of the present application, the household appliance is a refrigerator or an air conditioner.

[0050] After reading the specific embodiments of the present utility model in conjunction with the accompanying drawings, other features and advantages of the present utility model will become clearer. Description of the Drawings

[0051] In order to more clearly illustrate the technical solutions in the embodiments of the present utility model or the prior art, the following will briefly introduce the accompanying drawings required for the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are some embodiments of the present utility model. For those of ordinary skill in the art, without creative efforts, other accompanying drawings can also be obtained based on these drawings.

[0052] Figure 1 Is a perspective view of an embodiment of a refrigerator as a household appliance according to the present application;

[0053] Figure 2 Is a perspective view of an embodiment of a refrigerator as a household appliance according to the present application, in which the refrigerator door body is opened;

[0054] Figure 3 Is a schematic structural diagram of a refrigeration system in an embodiment of a refrigerator as a household appliance according to the present application;

[0055] Figure 4 Is the principle of the thermal fuse applied in a heater according to the present application Figure 1 ;

[0056] Figure 5 Is the principle of the thermal fuse applied in a heater according to the present application Figure 2 ;

[0057] Figure 6 Is an external view of the thermal fuse according to the present application;

[0058] Figure 7 Is a cross-sectional view of the thermal fuse according to the present application along the A-A direction when the passage is connected Figure 6 ;

[0059] Figure 8 Is Figure 7 An enlarged view of part B in;

[0060] Figure 9 Is a cross-sectional view of the thermal fuse according to the present application along the A-A direction when the passage is disconnected Figure 6 ;

[0061] Figure 10 Is Figure 9 An enlarged view of part C in.

[0062] Reference Signs:

[0063] 100, storage room; 100A, freezer; 100B, refrigerator; 200, door body; 200A, freezer door; 200B, refrigerator door; 300, refrigeration system; 310, compressor; 320, condenser; 330, solenoid valve; 340, throttling device; 341, first throttling device; 342, second throttling device; 350, evaporator; 351, refrigerator evaporator; 352, freezer evaporator; 360, liquid reservoir; 400, heater; 500, thermal fuse; 510, passage; 510A, first lead; 510B, PTC resistor; 510C, star-shaped reed; 511C, arc claw; 510D, metal shell; 510E, second lead; 520, break spring; 530, heat conducting block; 540, elastomer; 550, temperature sensing body; 560, sealing resin; 570, insulator; 580, first heat conducting sheet; 590, second heat conducting sheet. Detailed implementation

[0064] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

[0065] In the description of the present application, it should be understood that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present application.

[0066] The terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present application, unless otherwise stated, the meaning of "a plurality" is two or more.

[0067] In the description of the present application, it should be noted that, unless otherwise clearly specified and defined, the terms "installed", "connected", and "coupled" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected, or indirectly connected through an intermediate medium, and it may be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances.

[0068] In the present utility model, unless otherwise clearly specified and defined, the first feature being "above" or "below" the second feature may include the direct contact between the first and second features, or may include the situation where the first and second features are not in direct contact but in contact through other features therebetween. Moreover, the first feature being "above", "over", and "on top of" the second feature includes that the first feature is directly above and obliquely above the second feature, or merely indicates that the horizontal height of the first feature is higher than that of the second feature. The first feature being "below", "beneath", and "underneath" the second feature includes that the first feature is directly below and obliquely below the second feature, or merely indicates that the horizontal height of the first feature is lower than that of the second feature.

[0069] The following disclosure provides many different embodiments or examples for implementing different structures of the present utility model. To simplify the disclosure of the present utility model, the components and settings of specific examples are described below. Of course, they are merely examples and are not intended to limit the present utility model. In addition, the present utility model may repeat reference numerals and / or reference letters in different examples. Such repetition is for the purpose of simplification and clarity, and does not itself indicate the relationship between the various embodiments and / or settings discussed. In addition, the present utility model provides examples of various specific processes and materials, but those of ordinary skill in the art can be aware of the application of other processes and / or the use of other materials.

[0070] In household appliances such as air conditioners and refrigerators, a heater 400 is often provided for defrosting treatment, and at the same time, a thermal fuse 500 is also provided on the power supply line of the heater 400 to disconnect the power supply line when the surrounding temperature is sensed to be relatively high, so as to protect the heater 400.

[0071] Generally, the thermal fuse 500 is used in household appliances where the heater 400 has a relatively large power and there are plastic parts (such as inner liners, air duct covers, foaming materials) around the heater 400, to prevent the high heat from burning out the heater 400, scorching or even igniting the plastic parts around the heater 400.

[0072] When the household appliance is specifically a refrigerator, the following reference Figures 1 to 3 is given to introduce the structure and working principle of the refrigerator.

[0073] Figure 1 and Figure 2 are perspective views of a specific embodiment of the refrigerator involved in the present application; see Figure 1 and Figure 2 , the refrigerator of this embodiment has an approximately cuboid shape.

[0074] The appearance of the refrigerator is defined by a storage chamber 100 that defines a storage space and a plurality of door bodies 200 provided in the storage chamber 100. Among them, see Figure 2 , the door body 200 includes a door body outer shell (not labeled) located outside the storage chamber 100, a door body inner liner (not labeled) located inside the storage chamber 100, and an insulating layer (not labeled) between the upper end cover and the lower end cover; generally, the insulating layer is filled with foaming material.

[0075] The storage chamber 100 has an open box body, and the storage chamber 100 is vertically partitioned into a lower freezer compartment 100A and an upper refrigerator compartment 100B. Each of the separated spaces may have an independent storage space.

[0076] Specifically, the freezer compartment 100A is defined at the lower side of the storage chamber 100 and can be selectively covered by a drawer-type freezer door body 200A. The space defined above the freezer compartment 100A is partitioned into left and right sides to respectively define the refrigerator compartment 100B.

[0077] The refrigerator compartment 100B can be selectively opened or closed by a refrigerator door body 200B pivotally mounted on the refrigerator compartment 100B.

[0078] Figure 3 Shows the refrigeration system 300 of the refrigerator.

[0079] See Figure 3 , the refrigeration system 300 includes a compressor 310, a condenser 320, a throttling device 340, and an evaporator 350. A liquid storage device 360 is provided between the outlet of the freezer evaporator 352 and the suction port of the compressor 310.

[0080] Among them, as Figure 3 shown, in the embodiment of the present application, the evaporator 350 includes a refrigerator evaporator 351 and a freezer evaporator 352.

[0081] The high-temperature and high-pressure gaseous refrigerant discharged by the compressor 310 becomes a normal-temperature liquid refrigerant after being cooled by the condenser 320. It is divided into two paths through the electromagnetic valve 330. One path of the refrigerant passes through the first throttling device 341 (for example, the first capillary tube) for throttling and pressure reduction and then enters the refrigerating chamber evaporator 351. The other path of the refrigerant passes through the second throttling device 342 (for example, the second capillary tube) for throttling and enters the freezing chamber evaporator 352. The refrigerant pipeline flowing out of the refrigerating chamber evaporator 351 is connected to the pipeline between the second throttling device 342 and the freezing chamber evaporator 352. The liquid refrigerant flowing out of the freezing chamber evaporator 352 flows back into the liquid receiver 360, and the gaseous refrigerant flows back to the suction port of the compressor 310.

[0082] When the freezing chamber 100A has a refrigeration requirement, the compressor 310 starts, controls the electromagnetic valve 330 to introduce the refrigerant into the pipeline where the second throttling device 342 is located. The refrigerant passes through the freezing chamber evaporator 352 and then flows through the liquid receiver 360 into the suction port of the compressor 310. The refrigeration of the freezing chamber 100A is achieved through the above cycle process.

[0083] When the refrigerating chamber 100B has a refrigeration requirement, control the electromagnetic valve 330 to introduce the refrigerant into the pipeline where the first throttling device 341 is located. The refrigerant sequentially passes through the refrigerating chamber evaporator 351, the freezing chamber evaporator 352 and then flows through the liquid receiver 360 into the suction port of the compressor 310. The refrigeration of the refrigerating chamber 100B is achieved through the above cycle process.

[0084] When the household appliance is an air conditioner, the working principle of the air conditioner is given as follows.

[0085] The air conditioner performs the refrigeration cycle of the air conditioner by using a compressor, a condenser, an expansion valve and an evaporator. The refrigeration cycle includes a series of processes involving compression, condensation, expansion and evaporation to cool or heat the indoor space.

[0086] The low-temperature and low-pressure refrigerant enters the compressor, and the compressor compresses it into a refrigerant gas in a high-temperature and high-pressure state and discharges the compressed refrigerant gas. The discharged refrigerant gas flows into the condenser. The condenser condenses the compressed refrigerant into a liquid phase, and the heat is released to the surrounding environment through the condensation process.

[0087] The expansion valve expands the high-temperature and high-pressure liquid-phase refrigerant formed by condensation in the condenser into a low-pressure liquid-phase refrigerant. The evaporator evaporates the refrigerant expanded in the expansion valve and returns the refrigerant gas in a low-temperature and low-pressure state to the compressor. The evaporator can achieve the refrigeration effect by using the latent heat of evaporation of the refrigerant for heat exchange with the material to be cooled. During the whole cycle, the air conditioner can adjust the temperature of the indoor space.

[0088] The outdoor unit of an air conditioner refers to the part of the refrigeration cycle that includes a compressor and an outdoor heat exchanger. The indoor unit of the air conditioner includes an indoor heat exchanger, and the expansion valve can be provided in the indoor unit or the outdoor unit.

[0089] The indoor heat exchanger and the outdoor heat exchanger are used as condensers or evaporators. When the indoor heat exchanger is used as a condenser, the air conditioner serves as a heater in the heating mode. When the indoor heat exchanger is used as an evaporator, the air conditioner serves as a cooler in the cooling mode.

[0090] Whether in an air conditioner or a refrigerator, a heater 400 is used for heating defrosting during defrosting. To ensure the safety of using the heater 400, a thermal fuse 500 is provided on the power supply line of the heater 400. See Figure 4 and Figure 5 .

[0091] See Figure 4 and Figure 5 , which shows the power supply for the heater 400. The positive terminal of the power supply is Pow+, and the negative terminal of the power supply is Pow-.

[0092] See Figure 4 , a thermal fuse 500 can be provided between the positive terminal Pow+ and the positive power supply terminal of the heater 400; see Figure 5 , or a thermal fuse 500 can also be provided between the negative terminal Pow- and the negative power supply terminal of the heater 400.

[0093] The thermal fuse 500 is equivalent to a switch on the power supply line of the heater 400. When the thermal fuse 500 is connected, the power supply line is connected, and the heater 400 works normally. When the thermal fuse 500 is disconnected, the power supply line is disconnected, and the heater 400 stops working.

[0094] Some embodiments of the present application relate to the thermal fuse 500 as described above, which can timely disconnect the thermal fuse 500 when the temperature around it is high or the current on the line is large, resulting in high heat generation, to avoid causing a fire hazard.

[0095] See Figures 6 to 10 , the thermal fuse 500 includes a metal shell 510D, a first lead 510A, a PTC resistor 510B, a breaking spring 520, a star-shaped spring piece 510C, an elastomer 540, a heat conducting block 530, and a second lead 510E.

[0096] Among them, PTC is the abbreviation of Positive Temperature Coefficient, which is translated as positive temperature coefficient.

[0097] The metal shell 510D forms the appearance of the thermal fuse 500, and it can be designed in different shapes.

[0098] The first lead 510A and the second lead 510E are respectively arranged at different ends of the metal housing 510D. The first lead 510A is wrapped around one end of the metal housing 510D and extends into the interior of the metal housing 510D through the insulator 570 inside the metal housing 510D.

[0099] The insulator 570 is used to fix the first lead 510A on one hand and electrically insulate the first lead 510A from the metal housing 510D on the other hand.

[0100] The insulator 570 can be a ceramic insulator or an insulator made of other materials, as long as it can provide electrical insulation.

[0101] In some embodiments of the present application, referring to Figure 7 and Figure 9 , the insulator 570 includes a continuous first boss (not marked) and a second boss (not marked). The cross-sectional area of the first boss is larger than that of the second boss, so that a corner is formed between the first boss and the second boss, and the first lead 510A penetrates through the first boss and the second boss from the outside and extends into the interior of the metal housing 510D.

[0102] The outer side wall of the first boss is in contact with the inner side wall of the metal housing 510D. The open-circuit spring 520 is sleeved outside the second boss and one end abuts against the side surface of the first boss close to the second boss.

[0103] In some embodiments of the present application, the end of the metal housing 510D into which the first lead 510A extends is sealed and insulated with a sealing resin 560.

[0104] The PTC resistor 510B is electrically connected to the inner end of the first lead 510A extending into the metal housing 510D and is also located inside the open-circuit spring 520. Referring to Figure 7 and Figure 8 .

[0105] Wherein, one end of the open-circuit spring 520 abuts against the insulator and the other end abuts against the star-shaped spring piece 510C.

[0106] Referring to Figure 7 , the star-shaped spring piece 510C is located between the PTC resistor 510B and the heat-conducting block 530, and the star-shaped spring piece 510C is in contact connection with the inner side wall of the metal housing 510D.

[0107] In some embodiments of the present application, the star-shaped spring piece 510C is formed by shaping a sheet metal thin plate.

[0108] The metal thin plate can be an alloy material containing silver and copper, which is obtained through an internal oxidation process of the alloy.

[0109] The silver-copper alloy can form a limited solid solution. Heat treatment is carried out in an oxygen atmosphere to form oxides of the solute element copper, which are uniformly distributed in the alloy matrix metal. It has the characteristics of good compactness, fine oxide particles, arc corrosion resistance, long electrical life, and also has good ductility, electrical conductivity, corrosion resistance, arc extinguishing property, etc. The hardness of this alloy material remains basically unchanged before and after heat aging.

[0110] In some embodiments of the present application, in order to ensure reliable contact between the star-shaped spring piece 510C and the inner side wall of the metal housing 510D, the star-shaped spring piece 510C has a plurality of arc-shaped claws 511C arranged radially. The plurality of arc-shaped claws 511C form a bowl-shaped opening facing the PTC resistor 510B. A chamfer (not shown) is formed at the free end of each arc-shaped claw 511C. These claws are in contact connection with the inner side wall of the metal housing 510D. After the temperature-sensitive body 550 melts, the chamfer at the end of the arc-shaped claw 511C helps to slide reliably along the inner side wall of the metal housing 510D. And when the temperature-sensitive body 550 has not melted, the chamfer helps the star-shaped spring piece 510C to be in reliable contact with the inner side wall of the metal housing 510D.

[0111] As described above, a part of the open-circuit spring 520 sleeved outside the PTC resistor 510B extends into the bowl-shaped opening of the star-shaped spring piece 510C and abuts against the bottom wall of the bowl-shaped opening, realizing the abutment of the open-circuit spring 520 against the star-shaped spring piece 510C.

[0112] The elastomer 540 is a structure that can undergo elastic deformation, that is, it accumulates elastic force when an external force is applied and releases elastic force when the external force is removed.

[0113] In some embodiments of the present application, the elastomer 540 can be a spring, and the elastomer 540 is located between the star-shaped spring piece 510C and the temperature-sensitive body 550.

[0114] In some embodiments of the present application, a heat conduction block 530 is arranged inside the elastomer 540. One end of the heat conduction block 530 abuts against the star-shaped spring piece 510C and the other end abuts against the temperature-sensitive body 550.

[0115] When the temperature-sensitive body 550 has not melted, by the interaction between the elastomer 540 and the open-circuit spring 520, the star-shaped spring piece 510C is tightly clamped between the PTC resistor 510B and one end of the heat conduction block 530, and the heat conduction block 530 is tightly clamped between the star-shaped spring piece 510C and the temperature-sensitive body 550, so that the components inside the metal housing 510D are stably arranged along its length direction (see the direction of the dotted arrow shown in Figure 7 ).

[0116] In this way, it is ensured that the components are reliably connected when the thermal fuse 500 is working normally.

[0117] In some embodiments of the present application, the heat conducting block 530 is made of metal, and it can conduct the heat generated by the PTC resistor 510B to the temperature sensing body 550.

[0118] The second lead 510E is connected to the metal housing 510D.

[0119] When the thermal fuse 500 is applied to the power supply line of the heater 400, referring to Figure 4, the free end of the first lead 510A is electrically connected to the positive power supply terminal Pow+ of the power supply, and the free end of the second lead 510E is connected to the positive power supply terminal of the heater 400; referring to Figure 5, the free end of the first lead 510A is electrically connected to the negative power supply terminal Pow- of the power supply, and the free end of the second lead 510E is connected to the negative power supply terminal of the heater 400.

[0120] As follows, the working process of the thermal fuse 500 will be described.

[0121] (1) The temperature sensing body 550 has a melting temperature. It will only melt when it reaches its own melting temperature or senses that the surrounding temperature reaches the melting temperature. Otherwise, it will not melt (i.e., maintain its original volume).

[0122] Referring to Figure 7 and Figure 8 , after the thermal fuse 500 is put into operation, when the temperature sensed by the temperature sensing body 550 has not reached the melting temperature, for example, the current from the positive terminal Pow+ on the power supply line passes through the first lead 510A, the PTC resistor 510B, the star-shaped spring piece 510C, the metal housing 510D and the second lead 510E and flows to the positive power supply terminal of the heater, realizing power supply to the heater 400. At this time, the heater 400 works normally.

[0123] The path formed between the first lead 510A, the PTC resistor 510B, the star-shaped spring piece 510C, the metal housing 510D and the second lead 510E as described above is called the path 510.

[0124] (2) When the thermal fuse 500 is arranged near the heater 400, the temperature sensing body 550 can sense the change in its surrounding temperature. As described above, when the temperature sensed by the temperature sensing body 550 has not reached the melting temperature, the heater 400 remains working normally. Referring to Figure 7 and Figure 8 .

[0125] When the temperature sensing body 550 senses that the surrounding high temperature reaches the melting temperature, the temperature sensing body 550 begins to melt.

[0126] Referring to Figure 9 and Figure 10, due to the melting of the temperature-sensitive body 550, the open-circuit spring 520 and the elastic body 540 release elastic force, pushing the star-shaped reed 510C, the heat-conducting block 530 and the elastic body 540 to move towards the temperature-sensitive body 550, while the position of the PTC resistor 510B remains unchanged. Therefore, the connection between the star-shaped reed 510C and the PTC resistor 510B is disconnected, that is, the path 510 as described above is disconnected. At this time, electrical energy cannot be provided to the heater 400, and the heater 400 stops working. In this way, it is avoided that the heater 400 continues to generate high temperature and causes a fire hazard.

[0127] (3) When a large current is generated due to arcing in the internal conductive components of the heater 400 itself, since the arcing occurs at a certain point on the heater 400 and the temperature around the arcing point is relatively high, if the thermal fuse 500 is installed at a position far from the arcing point, the heat generated by the arcing cannot raise the temperature of the temperature-sensitive body 550 to the melting temperature. Therefore, the arcing will continue to occur. When the arcing is severe to a certain extent, it will char or even ignite the plastic parts around the heater 400. Therefore, the thermal fuse 500 also needs to take this situation into account.

[0128] The PTC resistor 510B is connected to the first lead 510A. Therefore, before the thermal fuse 500 is disconnected, when a large current is generated due to arcing in the conductive components of the heater 400, the PTC resistor 510B also passes through this large current. When the current passing through the PTC resistor 510B exceeds a certain value, the PTC resistor 510B will quickly heat up, and the heat generated is transferred to the temperature-sensitive body 550 through the star-shaped reed 510C and the heat-conducting block 530. When the heat accumulates to the temperature of the temperature-sensitive body 550 reaching the melting temperature, the temperature-sensitive body 550 melts.

[0129] After the temperature-sensitive body 550 melts, the path 510 as described above is disconnected, and no current flows through the heater 400 anymore, and the arcing process ends, avoiding the fire hazard caused by the heat generated by the instantaneous large current inside the heater 400.

[0130] The thermal fuse 500 involved in this application can not only avoid the fire hazard caused by the surrounding high temperature, but also avoid the fire hazard caused by the instantaneous large current generated inside the heater 400, improving the reliability of the heater 400 in use.

[0131] In some embodiments of the present application, in order to achieve reliable contact between the heat-conducting block 530 and the PTC resistor 510B through the star-shaped reed 510C, see Figures 7 to 10 , a first heat-conducting sheet 580 is arranged between the side of the star-shaped reed 510C away from the first lead 510A and one end of the heat-conducting block 530.

[0132] The outer edge of the first heat-conducting sheet 580 does not contact the inner wall of the metal housing 510D. That is, the area of the first heat-conducting sheet 580 is smaller than the inner tube area of the metal housing 510D. In this way, the heat generated by the PTC resistor 510B will not be transferred to the metal housing 510D but directly transferred to the heat-conducting block 530.

[0133] In some embodiments of the present application, the cross-sectional shape of the metal housing 510D can be designed as an annular shape, and the first heat-conducting sheet 580 can be selected as a metal disc. In this way, the diameter of the first heat-conducting sheet 580 is smaller than the inner diameter of the metal housing 510D. Setting the first heat-conducting sheet 580 can increase the contact area between the heat-conducting block 530 and the PTC resistor 510B through the star-shaped spring piece 510C, and the elastic force applied to the heat-conducting block 530 by the average breaking spring 520 after the temperature-sensitive body 550 melts.

[0134] Similarly, in some embodiments of the present application, in order to achieve reliable contact between the heat-conducting block 530 and the temperature-sensitive body 550, a second heat-conducting sheet 590 is arranged between the heat-conducting block 530 and the temperature-sensitive body 550.

[0135] The outer edge of the second heat-conducting sheet 590 also does not contact the inner wall of the metal housing 510D. That is, the area of the second heat-conducting sheet 590 is smaller than the inner tube area of the metal housing 510D. In this way, the heat generated by the PTC resistor 510B will not be transferred to the metal housing 510D but directly transferred to the temperature-sensitive body 550.

[0136] Setting the second heat-conducting sheet 590 can increase the contact area between the heat-conducting block 530 and the temperature-sensitive body 550, which helps to transfer heat quickly.

[0137] In some embodiments of the present application, the cross-sectional shape of the metal housing 510D can be designed as an annular shape, and the second heat-conducting sheet 590 can be selected as a metal disc. In this way, the diameter of the second heat-conducting sheet 590 is smaller than the inner diameter of the metal housing 510D.

[0138] In the description of the above embodiments, specific features, structures, materials or characteristics can be combined in a suitable manner in any one or more embodiments or examples.

[0139] The above is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered by the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. A thermal fuse, characterized in that: include: Metal housing; A first lead wire, which is wrapped around one end of the metal shell and passes through an insulator located in the metal shell and extends into the metal shell; A PTC resistor electrically connected to an inner end of the first lead extending into the metal housing; A circuit breaker spring, which is sleeved on the outside of the PTC resistor and has one end against the insulator; a star-shaped spring, which is located in the metal shell and contacts the inner wall of the metal shell, and the other end of the circuit breaker spring abuts against the star-shaped spring; An elastic body, which is located in the metal shell, with one end abutting against the star-shaped reed and the other end abutting against the temperature sensing body; A heat conductive block, located in the elastic body, with one end contacting the PTC resistor and the other end contacting the temperature sensing body; A second lead wire connected to the metal housing; Wherein, the temperature sensing body has a melting temperature. When the temperature sensing body is not melted, the circuit breaker spring and the elastic body work together to make the PTC resistor and the heat conductive block closely contact with the star-shaped reed respectively; when the temperature sensing body melts, the circuit breaker spring and the elastic body release the elastic force to push the star-shaped reed out of contact with the PTC resistor.

2. The thermal fuse according to claim 1, characterized in that: The thermal fuse also includes: A sealing resin is provided at the connection end between the metal housing and the first lead.

3. The thermal fuse according to claim 1, characterized in that: The thermal fuse also includes: A first heat conducting sheet, which is sandwiched between a side of the star-shaped spring sheet away from the first lead and an end of the heat conducting block and does not contact the inner wall of the metal shell; The second heat conducting sheet is sandwiched between the other end of the heat conducting block and the temperature sensing body and does not contact the inner wall of the metal shell.

4. The thermal fuse according to claim 1, characterized in that: The star-shaped reed is formed by forming a sheet metal thin plate.

5. The thermal fuse according to claim 1, characterized in that: The star-shaped spring sheet has a plurality of arc-shaped claws arranged radially, and the free end of each claw forms a chamfer contacting the inner side wall of the metal shell.

6. The thermal fuse according to claim 1, characterized in that: The elastic body is a spring.

7. The thermal fuse according to claim 1, characterized in that: The insulator is a ceramic insulator.

8. The thermal fuse according to claim 1, characterized in that: The insulator comprises: A first boss, the outer side wall of which contacts the inner side wall of the metal shell; The second boss has a cross-sectional area smaller than that of the first boss. The first lead passes through the first and second bosses and extends into the metal shell. The circuit breaker spring is sleeved on the outside of the second boss and abuts against the first boss on one side facing the second boss.

9. A household appliance, characterized in that: include: A heater, which is used to generate heat when in operation; A thermal fuse comprising: Metal housing; A first lead wire, which is wrapped around one end of the metal shell and extends into the metal shell through an insulator located in the metal shell, and a free end of the first lead wire is connected to a power supply line of the heater; A PTC resistor electrically connected to an inner end of the first lead extending into the metal housing; A circuit breaker spring, which is sleeved on the outside of the PTC resistor and has one end against the insulator; a star-shaped spring, which is located in the metal shell and contacts the inner wall of the metal shell, and the other end of the circuit breaker spring abuts against the star-shaped spring; An elastic body, which is located in the metal shell, with one end abutting against the star-shaped reed and the other end abutting against the temperature sensing body; A heat conductive block, located in the elastic body, with one end contacting the PTC resistor and the other end contacting the temperature sensing body; A second lead, one end of which is connected to the metal housing, and the other end of which is connected to the power supply line; Wherein, the temperature sensing body has a melting temperature. When the temperature sensing body is not melted, the circuit breaker spring and the elastic body work together to make the PTC resistor and the heat conductive block closely contact with the star-shaped reed respectively; when the temperature sensing body melts, the circuit breaker spring and the elastic body release the elastic force to push the star-shaped reed out of contact with the PTC resistor.

10. The household appliance according to claim 9, characterized in that: The household appliance is a refrigerator or an air conditioner.

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