Normally open thermoswitch

Abstract

The normally-open thermoswitch comprises a shell, a first conductor and a second conductor are arranged in a cavity of the shell in a penetrating mode, and the first conductor and the second conductor in the shell are arranged in an insulated mode; one end of the first conductor located in the shell is arranged in a cantilever mode, an expansion bag is arranged between the first conductor arranged in the cantilever mode and the shell, and one end of the limiting indicator and one end of the second conductor located in the shell are located on a displacement path of the first conductor arranged in the cantilever mode. One end of the limiting indicator is limited on the wall of the shell in a penetrating manner, the other end of the limiting indicator is arranged on the first conductor, and when the temperature of the expansion bag reaches a set temperature threshold value and the expansion bag expands towards the first conductor, the first conductor is driven to move to be in conductive contact with the second conductor, so that the first conductor and the second conductor are directly conducted; the driving limiting indicator extends out of the shell. The normally-open thermoswitch is simple in structure, and the heat dissipation component can be quickly connected into a circuit to protect a power device.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of power control and electric vehicles, in particular to a device for protecting power devices in the event of a fault current. BACKGROUND

[0002] Power devices are an important component of modern power electronic systems, mainly referring to electronic components designed to handle high voltage and large current, achieve power conversion and control, such as MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor), IGBT (Insulated Gate Bipolar Transistor), power diode, etc. They have high efficiency, low loss and good switching characteristics, and are widely used in motor control, solar photovoltaic, new energy vehicles, etc. However, these devices may face overcurrent, overvoltage and short circuit failures in actual application, resulting in high temperature of power devices, which may cause performance degradation, reduced life and even damage, etc. Therefore, the heat dissipation design of power devices is very important.

[0003] When the above faults occur, the heat dissipation requirement of the power device will be higher, and a more effective heat dissipation method is needed, such as using a heat dissipation fan, a heat sink or a cooling system, etc. When the power device is working normally, its own heat dissipation is sufficient, and the heat dissipation fan, the heat sink or the cooling system will bring extra power loss if connected to the circuit for a long time. Therefore, in order to avoid connecting the power loss components such as heat dissipation fan, heat sink or cooling system in the circuit during normal operation, the heat dissipation fan, heat sink or cooling system needs to be connected in the circuit in time through the switch when the temperature reaches a certain threshold range.

[0004] However, the current single switch function cannot realize the above temperature-dependent connection function, and it needs to be realized by combining temperature monitoring instruments and control circuits. This results in a complex circuit structure and high space occupancy.

[0005] In view of the above working conditions, a new type of thermal switch is invented. The switch is a closed integrated device, which is directly connected in series or parallel to the branch near the power device. When the circuit fails, the high thermal expansion coefficient liquid or gas or solid in the closed capsule directly contacted with one of the conductors expands rapidly due to the heat generated by the power device. The expanded closed capsule pushes one of the conductors to move and contact with the other conductor, thereby conducting the circuit. When the working circuit of the power device fails, the thermal switch operates in time to connect the heat dissipation branch of the power device, thereby cooling the power device. SUMMARY

[0006] The technical problem solved by the present application is that the normally open thermal switch is arranged, the branch circuit where the heat dissipation fan, the radiator or the cooling system is located is connected in series with the thermal switch, then is connected in parallel with the circuit near the power device, the thermal switch is arranged close to the power device, when the temperature of the power device reaches the threshold range of the designed warning, the thermal switch is closed, the branch circuit where the heat dissipation fan, the radiator or the cooling system is located is turned on, the heat dissipation fan, the radiator or the cooling system works, and the power device is protected by heat dissipation.

[0007] To solve the above technical problems, the technical scheme provided by the present application is a normally open thermal switch, which comprises a shell with a cavity, a first conductor and a second conductor are arranged in the cavity of the shell, one end of the first conductor and the second conductor located outside the shell is respectively used as a connection end of the normally open thermal switch, and the first conductor and the second conductor located inside the shell are insulated; one end of the first conductor located inside the shell is arranged in a cantilevered manner, an expansion capsule is arranged between the cantilevered first conductor and the shell, a limit indicator and one end of the second conductor located inside the shell are respectively located on the displacement path of the cantilevered first conductor; one end of the limit indicator is limited on the shell wall, and the other end is arranged on the first conductor, when the temperature of the expansion capsule reaches the set temperature threshold, the expansion capsule expands towards the first conductor, drives the first conductor to displace and make contact with the second conductor, makes the first conductor and the second conductor directly conduct, and at the same time, drives the limit indicator to extend out of the shell.

[0008] Preferably, a containing space is arranged in the shell, the opening end of the containing space faces the cantilevered first conductor, the expansion capsule is located in the containing space, the expansion capsule can only expand towards the opening end of the containing space through the containing space, the first conductor crosses the opening end of the containing space in a cantilevered manner and is located on the expansion direction path of the expansion capsule and in contact with the expansion capsule; the limit indicator is located outside the containing space.

[0009] Preferably, a convex rib is arranged on one side of the containing space, and the first conductor is arranged on the convex rib.

[0010] Preferably, a positioning groove is arranged on the convex rib, and the first conductor is arranged in the positioning groove.

[0011] Preferably, a heating resistor is arranged in the shell cavity as a current-limiting component, and the expansion bag is arranged on the heating resistor; the two ends of the heating resistor are respectively electrically connected with the first conductor and the second conductor in the shell to form a current-limiting circuit; when the first conductor and the second conductor are directly in electrical contact, the current flows through the series circuit formed by the first conductor and the second conductor in series.

[0012] Preferably, the limiting indicator is clamped on the first conductor to limit the initial position of the first conductor. Preferably, the limiting member is arranged on the outer circumferential surface of the limiting indicator inside the shell, a limiting hole is arranged on the first conductor, and one end of the limiting indicator inside the shell is inserted into the limiting hole; the limiting member is pressed on the first conductor to limit the initial position of the first conductor.

[0013] Preferably, the limiting member is a horizontal rod-shaped structure arranged on the opposite two outer sides of the limiting indicator, and one side of the limiting member facing the first conductor is arranged as an inclined surface; the first conductor keeps in contact with the limiting member in the initial position and the final position.

[0014] Preferably, a mounting hole is arranged on the shell wall of the shell, and the limiting indicator is mounted in the mounting hole.

[0015] Preferably, the initial position of the limiting indicator is limited by a limiting structure; the limiting structure is that a springy barb structure is arranged on the outer circumferential surface of the limiting indicator, the barb structure is in springy contact with the mounting hole to form the limiting structure, or the limiting indicator is assembled in the mounting hole in an interference manner to form the limiting structure, or a limiting spring is arranged between the limiting member and the shell wall of the shell to form the limiting structure.

[0016] Preferably, one end of the first conductor and the second conductor outside the shell is arranged on the outside of the shell in a patch type, a bent flat type, or a straight out quick plug type as a connection end of a heat-sensitive switch.

[0017] Preferably, the expansion bag includes a bag with elasticity and a gas, a liquid or a solid with a high thermal expansion coefficient filled in the bag; when the solid with a high thermal expansion coefficient is an integral structure and still an integral structure after expansion, the expansion bag is composed of the solid with a high thermal expansion coefficient; or the expansion bag includes a bag capable of stretching and deforming and a gas, a liquid or a solid with a high thermal expansion coefficient filled in the bag; when the expansion bag is not expanded, the expansion bag is in a compressed state; when the expansion bag is expanded, the expansion energy changes from the compressed state to a stretched state.

[0018] Preferably, the outer periphery of the expansion bladder, perpendicular to the direction of the force exerted by the expansion bladder on the first conductor, is configured as a retractable serrated structure.

[0019] Preferably, one end of the first conductor located inside the housing is configured as an arc-shaped structure protruding toward the second conductor.

[0020] Preferably, the housing includes a cover and a base, the base being located at the open end of the cover and closing the open end; a rib is provided on the base, the inner surface of the base, the rib and the side wall of the cover cooperate to form an accommodating space, the first conductor cantilevered over the accommodating space, and the expansion bladder is disposed in the accommodating space and contacts the first conductor.

[0021] Preferably, the cover and the base are connected and fixed by a snap-fit ​​mechanism.

[0022] This invention employs an expansion bladder that can expand under heating. The driving force generated when the expansion bladder expands causes the first and second conductors of the normally open thermal switch to make conductive contact, thereby closing the thermal switch. The response is rapid. Furthermore, the normally open thermal switch is a simple single device with a simple structure, which does not require the design of complex circuits to realize the conduction connection of the branch where the cooling fan and cooling system are located.

[0023] Therefore, the normally open thermal switch of the present invention is low in cost, can effectively protect power devices, and improve the service life of power devices. Attached Figure Description

[0024] Figure 1 This is a cross-sectional view of a normally open thermal switch in its initial state.

[0025] Figure 2 yes Figure 1 A side view structural diagram.

[0026] Figure 3 yes Figure 1 A schematic diagram of the structure after the action.

[0027] Figure 4 This is a schematic diagram of a normally open thermal switch with a serrated structure in the initial state.

[0028] Figure 5 yes Figure 4 A schematic diagram of the structure after the action.

[0029] Figure 6 This is a cross-sectional view of a normally open thermal switch in its initial state, equipped with a heating resistor.

[0030] Figure 7 yes Figure 6Structure schematic diagram after the action of the present application.

[0031] Figure 8 Structure schematic diagram of the connecting end of the normally open thermal switch as a bent flat-out structure.

[0032] Figure 9 Structure schematic diagram of the connecting end of the normally open thermal switch as a straight-out quick plug structure.

[0033] Reference signs:

[0034] Cover 1, base 2, first conductor 3, one end 31 of the first conductor outside the shell, one end 32 of the first conductor inside the shell, second conductor 4, one end 41 of the second conductor outside the shell, one end 42 of the second conductor inside the shell, protruding rib 5, expansion capsule 6, expansion capsule 6a, sawtooth structure 61, limit indicator 7, limit piece 71, heating resistor 8. DETAILED DESCRIPTION

[0035] The normally open thermal switch of the present application comprises a shell with a cavity, a first conductor and a second conductor are arranged in the cavity of the shell, one end of the first conductor and the second conductor outside the shell are respectively used as the connecting end of the normally open thermal switch, and the first conductor and the second conductor inside the shell are insulated; one end of the first conductor inside the shell is arranged in a cantilevered manner, an expansion capsule is arranged between the cantilevered first conductor and the shell, a limit indicator and one end of the second conductor inside the shell are respectively arranged on the displacement path of the cantilevered first conductor; one end of the limit indicator is arranged to be limited on the shell wall, and the other end is arranged on the first conductor; when the temperature of the expansion capsule reaches the set temperature threshold, the expansion capsule expands towards the first conductor, which drives the first conductor to displace and make conductive contact with the second conductor, so that the first conductor and the second conductor are directly conductive, and at the same time, the limit indicator is driven to extend out of the shell.

[0036] The preferred embodiments will be described in detail below with reference to the drawings. The orientation words involved are only based on the orientation shown in the drawings, and do not constitute a limitation on the technical solutions of the present application.

[0037] Reference Figures 1 to 3The application discloses a normally open type heat-sensitive switch which mainly comprises a shell, a first conductor, a second conductor and an expansion capsule. The shell is made of insulating material and comprises a cover and a base. The cover is in a cap structure with one end being open and the other end being closed. The base is arranged at the open end of the cover and closes the open end of the cover, thereby forming a relatively sealed shell with a cavity. The side walls of the base and the cover are provided with buckle structures, and the base is connected and fixed with the cover in a buckling mode, for example, a protruding buckle block is arranged on the side wall of the base matched with the cover, a buckle hole is formed on the corresponding side wall of the cover, and the buckle block of the base is arranged in the buckle hole of the cover during assembly, thereby forming fixed connection. The cover and the base can also be connected and fixed through bolt connection, rivet connection, laser welding or glue joint.

[0038] The first conductor and the second conductor pass through the contact surface between the cover and the base on opposite sides of the shell, so that one end of the first conductor and the second conductor is located in the cavity in the shell, and the other end (31, 41) is located outside the shell and is arranged on the outer surface of the base in a patch mode. The end of the second conductor located in the shell is fixedly arranged on the top of the cover opposite to the base in the shell and is fixedly arranged on the inner surface of the top of the cover in a horizontal mode. The first conductor is bent after being arranged on the inner wall of the cover and being away from the base by a certain distance, so that the first conductor located in the shell is arranged in a cantilever mode in the shell. The end of the first conductor located in the shell is away from the end of the second conductor arranged on the top of the cover and is arranged close to the inner surface of the base, so that the first conductor and the second conductor are arranged in a mutual insulation mode. The part of the first conductor located in the shell arranged in a cantilever mode has a certain elasticity. The end (32) of the first conductor located in the shell is arranged in an arc structure protruding towards the end of the second conductor, so that when the end of the first conductor is displaced towards the end of the second conductor, the arc structure of the end of the first conductor can be in conductive contact with the second conductor at the first time, thereby shortening the response time of the conductive contact between the first conductor and the second conductor.

[0039] The structure of the connecting end of the normally open type heat-sensitive switch is shown in FIG. 1, wherein the end (31, 41) of the first conductor and the second conductor located outside the shell is arranged in a patch structure. In other embodiments, the end of the first conductor and the second conductor located outside the shell can also be arranged in other structures, for example, as shown in FIG. 2, the end of the first conductor and the second conductor located outside the shell is arranged in a bending and extending structure at the end face of the open end of the cover. Figure 1 Figure 8 Figure 9 ​​As shown, the first conductor 3 and the second conductor 4 do not need to be bent at one end outside the shell, but directly extend outside the shell from between the cover and the base to form a straight-out quick plug structure on the same side of the shell outside. The connection end of the normally open thermal switch of the structure is convenient for quick plug installation with the external mounting seat.

[0040] A protruding rib 5 is arranged on the inner surface of the inner side wall of the cover 1 close to the first conductor 3 in the base 2. The protruding rib 5, the inner surface of the base 2, and the side wall of the cover 1 form an open-end accommodation space. The accommodation space is located on one side of the shell inside the bending of the first conductor 3. The first conductor 3 located inside the shell is bent to form a cantilever structure above the open end of the accommodation space and above the protruding rib 5, that is, the open end of the accommodation space is arranged towards the direction of the cantilevered first conductor, and one end of the first conductor 3 is arranged towards the direction of the base 2. A positioning groove (not shown) can also be formed on the upper surface of the protruding rib 5 towards the top of the cover, and the first conductor 3 is located in the positioning groove above the protruding rib 5.

[0041] The expansion capsule 6 is arranged in the accommodation space between the first conductor 3 and the base 2. The expansion direction of the expansion capsule is limited by the accommodation space, so that it can only expand in the direction from the base 2 towards the top of the cover 1, that is, only in the direction of the open end of the accommodation space. In this way, when the temperature rises to the designed threshold range, the expansion degree of the expansion capsule 6 can only drive the part of the cantilevered first conductor 3 to move towards the direction of one end of the second conductor 4, so that one end of the first conductor 3 and one end of the second conductor 4 are in conductive contact, the normally open thermal switch is closed, and the circuit in which the thermal switch is located is turned on.

[0042] In this scheme, the expansion capsule is limited inside the shell, preferably, only one free end can be limited, and the expansion direction of the expansion capsule is limited, so that when the expansion capsule reaches the temperature threshold, it can expand in the direction of pushing the one end of the first conductor away from its initial position inside the shell, so that the first conductor and the second conductor are in contact. Different limiting methods can be used, for example, the material of the capsule bag of the expansion capsule can be used in combination with the internal structure of the shell to limit the position to achieve the limitation of only one free end, or the internal structure of the shell can be set to form, for example, the expansion capsule can only expand or extend in one direction in the accommodation space. When the expansion capsule has only one free end, the expansion direction is determined when it expands, the product is more reliable, and the energy is more effectively utilized.

[0043] The inflation bag 6 comprises a bag with elasticity and a filler with high inflation coefficient filled in the bag, the filler is a gas, liquid or solid with high inflation coefficient. The liquid is kerosene or the like. When the solid with high inflation coefficient is used as the filler, if the solid is a whole structure and the solid still maintains the whole structure after inflation, the bag can be omitted and the solid can be directly used as the inflation bag. Generally, the outer peripheral shape of the inflation bag is a regular shape, such as a smooth columnar structure. When the bag has elasticity, the inflation bag 6 is in a contracted state when not inflated. When the inflation bag 6 is inflated, the bag of the inflation bag 6 is elastically deformed under the action of the inflation of the filler and is inflated toward the opening end of the accommodating space under the constraint of the accommodating space.

[0044] The bag of the inflation bag 6 can also be a bag that can be elastically deformed without elasticity. When the inflation bag is not inflated, the bag is in a compressed state. When the inflation bag is inflated, the inflated filler drives the bag to change from the compressed state to the stretched state. For example, the bag is a columnar steel structure, and the outer circumferential surface of the columnar structure is in a wavy structure or a sawtooth structure, so that the bag can be compressed and stretched. When the filler in the inflation bag is not inflated, that is, when the inflation bag 6 is in an initial position, the bag is in a compressed state. When inflated, the filler with high inflation coefficient is inflated, which drives the bag of the inflation bag 6 to change from the compressed state to the stretched state, thereby driving the first conductor to displace.

[0045] For example Figure 4 and Figure 5 The inflation bag 6a shown in the sawtooth structure is provided with a sawtooth structure 61 on the outer circumferential surface of the inflation bag perpendicular to the inflation direction of the inflation bag from the base 2 toward the top of the cover 1. When the inflation bag 6 is not inflated, as shown in Figure 4 , the inflation bag 6 is in a compressed state. When the inflation bag 6 is inflated, as shown in Figure 5 , the filler with high inflation coefficient is inflated, which drives the inflation bag 6 to change from the compressed state to the stretched state toward the opening end of the accommodating cavity, through Figure 4 and Figure 5 The bag that can be elastically deformed without elasticity is shown. The inflation direction of the inflation bag is only in the direction toward the opening end of the accommodating space, which can further constrain the inflation direction of the inflation bag 6.

[0046] The limit indicator 7 is located on one side of the convex rib 5, i.e. outside the accommodating space where the expansion bag is located. An installation hole is formed on the top of the cover 1 corresponding to the position of the first conductor 3, and the limit indicator 7 is installed in the installation hole. One end of the limit indicator 7 is inserted into the installation hole on the top of the cover 1, and the other end is located in the cavity of the shell. The outer periphery of the limit indicator 7 in the shell is provided with a limiting piece 71, a limiting hole is formed on the first conductor 3, and one end of the limit indicator 7 in the shell is inserted into the limiting hole of the first conductor 3. The limiting piece 71 is located on the upper surface of the first conductor 3 and presses the first conductor 3 tightly. The limiting piece 71 is a horizontal rod structure vertically arranged on the opposite two outer sides of the limit indicator 7. The limiting piece 71 on each side of the limit indicator 7 is provided with a slope surface facing the surface of the first conductor 3. The slope surface of the limiting piece 71 on one side of the limit indicator 7 is in contact with the surface of the first conductor 3 in the initial position, and the slope surface of the limiting piece 71 on the other side of the limit indicator 7 is in contact with the surface of the first conductor 3 in the terminal position. This ensures that the limiting piece 71 and the first conductor always remain in contact during the displacement of the first conductor 3 driving the limit indicator 7.

[0047] In order to further limit the initial position of the limit indicator 7, a limiting structure is arranged on the limit indicator 7. A flexible barb structure (not shown) is arranged on the outer periphery of one end of the limit indicator 7 as a limiting structure, and the flexible barb structure is in interference fit with the installation hole to limit the initial position of the limit indicator 7. When the expansion bag 6 drives the first conductor 3 to displace, the first conductor 3 contacts the limiting piece 71, drives the limit indicator 7 to displace in the direction of the outside of the shell, and the limit indicator 7 overcomes the limitation of the barb structure. The end of the limit indicator 7 facing the outside of the shell protrudes out of the outer surface of the shell wall, prompting the staff that the normally open thermal switch has worked and the circuit where the power device is located has failed. After the limit indicator 7 operates, the flexible barb structure is displaced to the outside of the shell, forming a terminal position limitation to avoid the limit indicator 7 re-entering the shell.

[0048] The initial position of the limit indicator can also be limited by the following ways: the limit indicator is assembled in the installation hole in an interference manner to form a limiting structure to limit the initial position of the limit indicator; or a limiting spring is arranged between the limiting piece of the limit indicator and the inner wall of the cover on the outer periphery of the installation hole to form a limiting structure to limit the initial position of the limit indicator.

[0049] The limit indicator 7 is located on the displacement path of the first conductor 3 arranged in a cantilevered manner. When the expansion bag expands to drive the first conductor 3 to displace in a cantilevered manner, the first conductor 3 drives the limit indicator 7 to displace towards the outside of the shell, overcoming the limitation of the initial position, and warning.

[0050] Figures 1 to 3 Working principle:

[0051] The normally open thermal switch is connected in series in a circuit where a heat dissipation fan, a radiator or a cooling system is located, and the thermal switch is arranged close to the power device.

[0052] When a fault current occurs, the power device generates heat, and the thermal energy generated by the power device and the thermal energy generated by the normally open thermal switch itself cause the expansion capsule 6 to expand. When the temperature of the expansion capsule 6 reaches or exceeds the designed temperature threshold, the expansion capsule 6 expands, drives the one end of the first conductor 3 arranged in suspension to displace towards the one end of the second conductor 4, and makes the protruding side of the arc-shaped structure of the one end of the first conductor 3 conductively contact the one end of the second conductor 4, so as to make the normally open thermal switch close, make the circuit where the heat dissipation fan, the radiator or the cooling system is located conductive, and make the heat dissipation fan, the radiator or the cooling system work to dissipate heat for the power device, so as to realize the heat dissipation protection of the power device. At the same time, the first conductor 3 abuts against the limiting member 71 on the limiting indicator 7, drives the limiting indicator 7 to displace towards the outside of the shell, and makes the one end of the limiting indicator 7 extending out of the outer surface of the shell wall of the shell, so as to remind the operator that the thermal switch has worked and the circuit has failed.

[0053] The normally open thermal switch has the advantages that it is a single device, the structure is simple, and only when the fault circuit current occurs and the power of the device cannot rely on normal heat dissipation by itself, the heat dissipation fan, the radiator or the cooling system is connected through the thermal switch, so that the power loss is reduced.

[0054] In other embodiments, in order to improve the response speed of the normally open thermal switch, a heating resistor 8 is arranged at the expansion capsule 6 as a current limiting component. Referring to Figures 6 to 7 The heating resistor 8 is arranged on the base 2 at the bottom of the accommodating space in the shell, one end of the heating resistor 8 is conductively connected with the first conductor 3, the connection mode can be connected through welding, conductive contact or other conductive connection modes, the other end of the heating resistor 8 passes through the base 2 and is conductively connected with the one end of the second conductor 4 located outside the shell, and the heating resistor 8 is conductively connected between the first conductor 3 and the second conductor 4 to form a current limiting circuit. Since the resistance of the heating resistor 8 is much larger than the resistance of the first conductor and the second conductor, the current flowing through the heating resistor is very small, and the small current flowing through the heating resistor cannot make the heat dissipation fan, the radiator or the cooling system work, which is equivalent to that the circuit where the heat dissipation fan, the radiator or the cooling system is located is not conductive in the normal working state.

[0055] Figures 6 to 7 Working principle:

[0056] In the normal working state, the current on the current limiting circuit with the heating resistor connected in series on the thermal switch is very small and can be ignored.

[0057] When the fault current occurs, the current flowing through the heating resistor increases, the temperature of the heating resistor rises, the expansion capsule is heated rapidly, and the expansion capsule expands rapidly in combination with the heat energy generated by the power device, so that the first conductor 3 is displaced to make contact with the second conductor 4. Since the resistance of the first conductor and the second conductor is very small, the current almost entirely flows through the first conductor 3 and the second conductor 4, and the current is almost the normal current. Therefore, the cooling fan, the radiator or the cooling system works normally to dissipate heat for the power device, and the heat dissipation protection of the power device is realized. The access of the heating resistor can improve the response speed of the thermal switch, but in the normal working state, the thermal switch has a certain power loss due to the existence of the heating resistor.

[0058] In the above embodiments, the limiting indicator is clamped on the first conductor to limit the initial position thereof. However, when the first conductor, which is arranged in a cantilevered manner after being bent, has a certain rigidity, even if the limiting of the limiting indicator is not performed, the first conductor will not be displaced to make contact with the second conductor in the direction of the second conductor due to the rigidity of the first conductor itself. Therefore, when the first conductor, which is arranged in the shell after being bent, has sufficient rigidity, even if the end of the first conductor arranged in a cantilevered manner is shaken, the first conductor will not make contact with the second conductor. At this time, the limiting indicator only needs to be arranged on the displacement path of the first conductor, and the position of the first conductor does not need to be limited. When the first conductor has sufficient rigidity, the driving force generated by the expansion of the expansion capsule should be relatively increased to overcome the rigidity of the first conductor, so that the first conductor is displaced to make contact with the second conductor.

Claims

1. A normally open thermoswitch characterized in that, The application relates to a constant-open thermal sensitive switch, which comprises a shell with a cavity, a first conductor and a second conductor are arranged in the shell cavity, one end of the first conductor and the second conductor outside the shell is respectively used as a connecting end of the constant-open thermal sensitive switch, and the first conductor and the second conductor inside the shell are insulated; one end of the first conductor inside the shell is arranged in a cantilever mode, an expansion capsule is arranged between the cantilevered first conductor and the shell, a limiting indicator and one end of the second conductor inside the shell are respectively arranged on the displacement path of the cantilevered first conductor; one end of the limiting indicator is limited on the shell wall of the shell, and the other end is arranged on the first conductor; when the temperature of the expansion capsule reaches a set temperature threshold, the expansion capsule expands towards the first conductor, drives the first conductor to displace and conductively contact the second conductor, directly conducts the first conductor and the second conductor, and simultaneously drives the limiting indicator to extend out of the shell.

2. The normally open thermoswitch according to claim 1, wherein An accommodating space is arranged in the shell, the opening end of the accommodating space faces the cantilevered first conductor, the expansion capsule is arranged in the accommodating space, the expansion capsule can only expand towards the opening end of the accommodating space through the accommodating space, the first conductor crosses the opening end of the accommodating space in a cantilever mode and is arranged on the expansion direction path of the expansion capsule and in contact with the expansion capsule; and the limiting indicator is arranged outside the accommodating space.

3. The normally open thermoswitch according to claim 2, wherein, A convex rib is arranged on one side of the accommodating space, and the first conductor is arranged on the convex rib.

4. The normally open thermoswitch according to claim 3, wherein A positioning groove is arranged on the convex rib, and the first conductor is arranged in the positioning groove.

5. The normally open thermoswitch according to claim 2, wherein, A heating resistor is further arranged in the shell cavity as a current-limiting component, the expansion capsule is arranged on the heating resistor, two ends of the heating resistor are respectively conductively connected with the first conductor and the second conductor in the shell to form a current-limiting circuit, and after the first conductor and the second conductor are directly conductively contacted, current flows through a series circuit formed by the first conductor and the second conductor in series.

6. The normally open thermoswitch according to claim 1, wherein, The limiting indicator is clamped on the first conductor to limit the initial position of the first conductor.

7. The normally open thermoswitch according to claim 6, wherein A limiting member is arranged on the outer circumferential surface of the limiting indicator inside the shell, a limiting hole is arranged on the first conductor, one end of the limiting indicator inside the shell is inserted into the limiting hole, and the limiting member is pressed on the first conductor to limit the initial position of the first conductor.

8. The normally open thermoswitch according to claim 7, wherein, The limiting member is a horizontal rod-shaped structure arranged on the opposite two outer sides of the limiting indicator, one side of the limiting member facing the first conductor is arranged as an inclined surface, and the first conductor keeps in contact with the limiting member in the initial position and the terminal position.

9. The normally open thermoswitch according to claim 7, wherein, An installation hole penetrating the shell wall is arranged on the shell wall of the shell, and the limiting indicator is installed in the installation hole.

10. The normally open thermoswitch according to claim 9, wherein, The limiting indicator is limited in its initial position by a limiting structure, which is a barb structure with elasticity arranged on the outer periphery of the limiting indicator, and the barb structure elastically contacts the mounting hole to form the limiting structure, or the limiting indicator is assembled in the mounting hole in an interference manner to form the limiting structure, or a limiting spring is arranged between the limiting member and the shell wall of the shell to form the limiting structure.

11. The normally open thermoswitch according to claim 1, wherein, One end of the first conductor and the second conductor located outside the shell is arranged outside the shell as a connecting end of the thermal sensitive switch in a patch type, a bent flat type or a straight out quick plug type.

12. The normally open thermoswitch according to claim 1, wherein, The expansion capsule includes a capsule bag with elasticity and a gas, liquid or solid with a high thermal expansion coefficient filled in the capsule bag, when the solid with a high thermal expansion coefficient is an integral structure and still an integral structure after expansion, the expansion capsule is composed of the solid with a high thermal expansion coefficient; or the expansion capsule includes a capsule bag with extensible deformation and a gas, liquid or solid with a high thermal expansion coefficient filled in the capsule bag, when the expansion capsule is not expanded, the expansion capsule is in a compressed state, when the expansion capsule is expanded, the expansion energy is deformed from the compressed state to the stretched state.

13. The normally open thermoswitch according to claim 12, wherein, The outer periphery of the expansion capsule in the direction of the force acting on the first conductor perpendicularly to the expansion capsule is arranged as an extensible zigzag structure.

14. The normally open thermoswitch according to claim 1, wherein, One end of the first conductor located in the shell is arranged as an arc structure protruding towards the second conductor.

15. The normally open thermoswitch according to any one of claims 1 to 14, wherein The shell includes a cover and a base, the base is located at and closes the open end of the cover; a convex rib is arranged on the base, the inner surface of the base, the convex rib and the side wall of the cover cooperate to form a containing space, the first conductor is cantilevered over the containing space, and the expansion capsule is arranged in the containing space and in contact with the first conductor.

16. The normally open thermoswitch according to claim 15, wherein, The cover and the base are connected and fixed in a buckle manner.

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