Anti-impact circuit protection element

Abstract

The invention discloses an anti-impact circuit protection element, which comprises a shell, a movable arm, a fixed arm, a PTC (Positive Temperature Coefficient) thermistor and a shape memory alloy sheet, and is characterized in that one end of the movable arm is provided with a movable contact; a fixed contact is arranged on the fixed arm, the movable contact is in contact with the fixed contact, and the PTC thermistor is attached to and fixedly connected with the fixed arm; the upper surface and the lower surface of the shape memory alloy sheet are attached to the movable arm and the PTC thermistor respectively, the shape memory alloy sheet comprises a plane part and a bent part, and the plane part is fixedly connected with the PTC thermistor; the movable arm is fixedly connected with one part of the plane part or the bent part; in a low-temperature phase state, the shape memory alloy sheet is in a plane state; and in a high-temperature phase state, the bending part generates angle change relative to the plane part to generate mechanical thrust to upwards jack up the movable arm so as to separate the movable contact from the fixed contact. The circuit protection element can bear large current, has over-current and over-temperature dual protection and automatic reset functions, and is excellent in anti-impact performance and compact in structure.

Description

Technical Field

[0001] The invention belongs to the field of circuit protection, and in particular relates to an anti-shock circuit protection element. Background Art

[0002] In modern electronic and electrical systems, circuit protection is a key link to ensure the safe operation of equipment, extend service life and protect user safety. With the advancement of science and technology and the diversification of market demand, circuit protection technology is also developing continuously. The commonly used circuit protection components mainly include three types: positive temperature coefficient (PTC) thermistors, fuses and circuit breakers. For PTC thermistors, their resistance is low at room temperature, but when the temperature reaches the Curie point, the resistance increases sharply, thereby effectively reducing the current and protecting the circuit and equipment; fuses have built-in alloy melts. When the current flowing through increases abnormally, the alloy melt heats up. When the temperature rises to its melting point or melting range, the alloy melt melts and disconnects, thereby cutting off the current; circuit breakers usually have built-in temperature-sensitive metal elements (such as thermal bimetallic strips, etc.). When the temperature rises to the set value, the thermal thrust generated by the temperature-sensitive metal element pushes the separation between the internal contacts of the device to cut off the circuit.

[0003] However, the above-mentioned circuit protection components all have their own defects. For example, the PTC thermistor has a resistance greater than the contact resistance of the contact in normal working state. When used in high-current equipment, the power loss is large. The fuse is a disposable product without self-recovery function. After it is blown, it needs to be replaced with a new fuse, which increases the cost of use and causes waste of resources. For the circuit breaker, taking the Chinese patent CN109314013A as an example, the PTC element and the temperature control element (i.e., the thermal bimetallic strip) in the circuit breaker structure disclosed therein are arranged separately, which obviously takes up more space. At the same time, since the thermal bimetallic strip is a curved surface before and after flipping, the contact area between it and other components such as the PTC element and the movable arm is limited, which is not conducive to the effective conduction of heat and may reduce the sensitivity of temperature sensing. In addition, the thermal bimetallic strip is inserted between the movable arm and the PTC component, and it is not tightly connected to the two. Its position is fixed only by the pressure exerted on it by the movable arm and the space setting inside the device. At the same time, in order to allow the movable arm to deform and the bimetallic strip to suddenly jump and reverse, a certain amount of movable space must be reserved. Therefore, when the component encounters severe shock (such as falling) or strong external force impact, the above-mentioned components are prone to momentary poor contact due to vibration, thereby causing momentary interruption of the circuit. In extreme cases, it may also cause the thermal bimetallic strip to move out of its original position, causing the component to fail.

[0004] Therefore, there is an urgent need for an anti-shock circuit protection element to solve the deficiencies of the prior art. Summary of the invention

[0005] In view of the above problems, the purpose of the present invention is to provide an anti-shock circuit protection element, which can withstand large currents, integrate over-current and over-temperature dual protection, have automatic reset function and excellent anti-shock performance, and at the same time conform to the development trend of miniaturization and micro-miniaturization of electronic components.

[0006] To achieve the above objectives, the present invention provides an anti-shock circuit protection element, comprising: a housing; a movable arm, one end of the movable arm is provided with a movable contact and extends into the housing, and the other end extends from one side of the housing; a fixed arm, one end of the fixed arm extends into the housing, and the other end extends from the other side of the housing, a fixed contact is provided on the fixed arm, the movable contact and the fixed contact are in contact, the movable arm and the fixed arm are independently made of a copper-based alloy or a nickel-based alloy, and the movable contact and the fixed contact are both made of a conductive precious metal; a PTC thermistor; the PTC thermistor is located inside the housing, and the PTC thermistor The PTC thermistor is fitted with and fixedly connected to the fixed arm; the shape memory alloy sheet is in a planar state in a low-temperature phase state, the upper surface of the shape memory alloy sheet is fitted with the movable arm, and the lower surface of the shape memory alloy sheet is fitted with the PTC thermistor, the shape memory alloy sheet includes a planar portion and a curved portion, and the planar portion is fixedly connected to the PTC thermistor; the movable arm is fixedly connected to a part of the curved portion or the planar portion; when the shape memory alloy sheet is in a high-temperature phase state, the curved portion changes angle relative to the planar portion to generate a mechanical thrust to push the movable arm upward, so that the movable contact is separated from the fixed contact.

[0007] Compared with the prior art, the anti-shock circuit protection element of the present invention has the following beneficial effects:

[0008] 1. In the anti-shock circuit protection element provided by the present invention, the movable arm and the fixed arm are made of highly conductive copper-based alloy or nickel-based alloy, and the movable contact and the fixed contact are made of conductive precious metal, which ensures that under normal working conditions, most of the current flows through the movable arm, movable contact, fixed contact and fixed arm, and only a very small amount of current passes through the PTC thermistor; at the same time, since these alloys have low resistance characteristics, they can provide efficient current conduction under high current conditions and reduce heat generation caused by resistance, thereby meeting the needs of high current operation.

[0009] 2. When the anti-shock circuit protection element device provided by the present invention is in a normal working state, the movable contact is in contact with the fixed contact, and the current flows in from an external port, most of which flows through the movable arm, the movable contact, the fixed contact and the fixed arm, and then flows out from another external port. When the current increases abnormally and causes the movable arm to heat up sharply, the temperature of the shape memory alloy sheet also rises accordingly, until the transition temperature is reached, the angle of the bent portion changes relative to the flat portion, and a mechanical thrust is generated to push the movable arm upward, so that the movable contact is separated from the fixed contact. At this time, the current is directed to the PTC thermistor to activate the secondary protection mechanism. Since the internal resistance of the PTC thermistor is significantly higher than that of the movable arm and the fixed arm, the abnormal current can be suppressed to a certain extent, and the PTC thermistor can heat the shape memory alloy after being energized to maintain its high-temperature phase shape; if the current exceeds the set value, the PTC thermistor will be activated, thereby effectively reducing the current and protecting the circuit and equipment. Therefore, the circuit protection element of the present invention has an overcurrent protection function.

[0010] 3. The upper and lower surfaces of the shape memory alloy sheet in the anti-shock circuit protection element provided by the present invention are respectively attached to the movable arm and the PTC thermistor, and the shape memory alloy sheet is in a planar state in the low temperature phase state, which enables the shape memory alloy sheet to be closely attached to the adjacent movable arm and the PTC thermistor, making the overall structure more compact, thus saving more space, and more in line with the current requirements for miniaturization and micro-miniaturization of electronic components. In addition, this can also enable the PTC thermistor to form good thermal contact with the shape memory alloy sheet and the movable arm, thereby improving the heat conduction efficiency and helping to improve the response sensitivity to the temperature change of the surrounding environment (such as the movable arm).

[0011] 4. When the external environment temperature rises abnormally, it will cause the temperature inside the circuit protection element to rise, which will also trigger the angle change of the curved part relative to the flat part to separate the movable contact from the fixed contact. At this time, the current is directed to the PTC thermistor to activate the secondary protection mechanism to prevent the equipment from being damaged by high temperature. Therefore, the anti-shock circuit protection element provided by the present invention can not only provide protection when the current is overloaded, but also once the external environment temperature is too high, even if the current flowing through the anti-shock circuit protection element remains within the normal working range, it can also activate the secondary protection mechanism to ensure the safety of the system, thereby realizing the over-temperature protection function.

[0012] 5. The shape memory alloy sheet in the anti-shock circuit protection element provided by the present invention includes a flat portion and a curved portion, the flat portion is fixedly connected to the PTC thermistor; the movable arm is fixedly connected to a part of the curved portion or the flat portion, so that the shape memory alloy sheet can still maintain a large area contact with the PTC thermistor in the high-temperature phase state, so that heat conduction can be more efficient, so that in the secondary protection mode, the PTC thermistor can more effectively heat the shape memory alloy sheet and maintain its specific shape in the high-temperature phase state. This ensures that the anti-shock circuit protection element can respond quickly and stably perform the secondary protection function when encountering overcurrent or overtemperature conditions, thereby ensuring the safety and reliability of the circuit.

[0013] 6. When the circuit fault is eliminated and the current returns to normal levels or when the ambient temperature drops to a normal range, the shape memory alloy changes from a bent state in a high-temperature phase to a planar state in a low-temperature phase, prompting the movable arm to reset, thereby re-contacting the movable contact with the fixed contact, and the circuit automatically returns to normal working state. This automatic reset feature reduces the need to replace the fuse, so the anti-shock circuit protection element of the present invention can reduce resource consumption.

[0014] 7. In the anti-shock circuit protection element provided by the present invention, the PTC thermistor is fixedly connected to the fixed arm and the planar portion of the shape memory alloy, respectively, and the movable arm is fixedly connected to a part of the curved portion or the planar portion, so that the movable arm, the shape memory alloy sheet, the PTC thermistor and the fixed arm are firmly connected as a whole, ensuring that the heat and electrical conduction paths are firm and smooth, thereby ensuring that even in the event of severe vibration or external force impact, the various components can maintain stable contact, avoiding the risk of instantaneous poor contact or component failure.

[0015] Furthermore, one end of the plane portion of the present invention close to the movable contact is bent upward to form a bent portion, and the plane portion is fixedly connected to the movable arm and the PTC thermistor respectively.

[0016] Furthermore, the bending portion of the present invention includes a first bending portion and a second bending portion, the first bending portion is formed by bending one end of the planar portion close to the movable contact upward, and the second bending portion is formed by bending one end of the first bending portion close to the movable contact downward, the planar portion is fixedly connected to the PTC thermistor, and the second bending portion is fixedly connected to the movable arm.

[0017] Furthermore, the bending portion of the present invention includes a first bending portion, a connecting portion, and a second bending portion. The first bending portion is formed by bending upward one end of the planar portion close to the movable contact, the connecting portion is formed by bending horizontally one end of the first bending portion close to the movable contact, and the second bending portion is formed by bending downward one end of the connecting portion close to the movable contact. The planar portion is fixedly connected to the PTC thermistor, and the connecting portion is fixedly connected to the movable arm.

[0018] Furthermore, the material of the shape memory alloy sheet of the present invention is at least one of a nickel-titanium alloy, a copper alloy and an iron alloy.

[0019] Furthermore, the material of the shape memory alloy sheet of the present invention is at least one of Ni-Ti alloy, Ni-Ti-Cu alloy, Ni-Ti-Co alloy, Ni-Ti-Fe alloy, Ni-Ti-Nb alloy, Cu-Zn alloy, Cu-Zn-Al alloy, Cu-Zn-Sn alloy, Cu-Zn-Si alloy, Cu-Zn-Ga alloy, Cu-Sn alloy, Fe-Pt alloy, Fe-Mn-Si alloy, Fe-Ni-Co-Ti alloy, Fe-Mn-Al-Ni alloy, and Fe-C-Mn-Si-Cr-Ni alloy.

[0020] Furthermore, the materials of the movable arm and the fixed arm of the present invention are independently selected from at least one of Cu-Ni-Si-Mg alloy, Cu-Ni-Si-P alloy, Cu-Ni-Sn-P alloy, Cu-Ni-Co-Si alloy, Cu-Ni-Si alloy, Cu-Zr alloy, Cu-Be alloy, Cu-Ni-Be alloy, Cu-Sn alloy, Cu-Mg-P alloy, Cu-Zn-Sn alloy, Cu-Fe-P alloy, Cu-Fe-Mg-P alloy, and Ni-Be alloy.

[0021] Furthermore, the PTC thermistor of the present invention is a polymer PTC thermistor or a ceramic PTC thermistor.

[0022] Furthermore, the thickness of the movable arm and the fixed arm of the present invention are each independently 50 to 500 μm.

[0023] Furthermore, the material of the movable contact and the fixed contact of the present invention is independently at least one of gold, silver, and a gold-silver alloy. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the structure of the circuit protection element of the present invention under normal working state.

[0025] Figure 2 for Figure 1 Circuit diagram of the circuit protection component in normal working condition.

[0026] Figure 3 for Figure 1 Schematic diagram of the structure of the circuit protection element in an abnormal working state.

[0027] Figure 4 for Figure 1Circuit diagram of the circuit protection element in abnormal working state.

[0028] Figure 5 FIG. 4 is another schematic diagram of the structure of the circuit protection element of the present invention in a normal working state.

[0029] Figure 6 for Figure 5 Schematic diagram of the structure of the circuit protection element in an abnormal working state.

[0030] Figure 7 It is another structural schematic diagram of the circuit protection element of the present invention in a normal working state.

[0031] Figure 8 for Figure 7 Schematic diagram of the structure of the circuit protection element in an abnormal working state. DETAILED DESCRIPTION

[0032] In order to better illustrate the purpose, technical solution and beneficial effects of the present invention, the present invention will be further described below in conjunction with specific embodiments and drawings. It should be noted that the following implementation method is a further explanation of the present invention and should not be used as a limitation of the present invention.

[0033] Please see Figure 1 to Figure 4 The present invention provides an anti-shock circuit protection element 100, which can withstand large current, integrates dual protection of overcurrent and overtemperature, has an automatic reset function and excellent anti-shock performance, and is small in size. Therefore, the anti-shock circuit protection element 100 of the present invention can be used as a circuit protection component in electronic devices such as mobile communication devices, laptop computers and battery management systems.

[0034] Please continue to see Figure 1 to Figure 4The anti-shock circuit protection element 100 of the present invention includes a movable arm 11, a fixed arm 12, a PTC thermistor 13, a shape memory alloy sheet 14, and a housing 15. The housing 15 is made of plastic and can be prepared by conventional injection molding, gluing, ultrasonic welding, and the like. Specifically, the movable arm 11, the fixed arm 12, the PTC thermistor 13, and the shape memory alloy sheet 14 are encapsulated and fixed in the housing 15 to ensure the stability of the structure of the anti-shock circuit protection element 100. A movable contact 111 is provided at one end of the movable arm 11 and extends into the housing 15, and the other end of the movable arm 11 extends from one side of the housing 15; one end of the fixed arm 12 extends into the housing 15, and the other end of the fixed arm 12 extends from the other side of the housing 15, and a fixed contact 121 is provided on the fixed arm 12, and the movable contact 111 and the fixed contact 121 are in contact; the PTC thermistor 13 is located in the housing 15, and the PTC thermistor 13 is attached to and fixedly connected with the fixed arm 12, and the shape memory alloy sheet 14 is located in the housing 15, and the upper surface of the shape memory alloy sheet 14 is attached to the movable arm 11. The lower surface of the shape memory alloy sheet 14 is attached to the PTC thermistor 13. The shape memory alloy sheet 14 includes a flat portion 141 and a bent portion 142. The flat portion 141 is fixedly connected to the PTC thermistor 13; the movable arm 11 is fixedly connected to the flat portion 141 or a part of the bent portion 142. The shape memory alloy sheet 14 is in a flat state in a low-temperature phase state; when the shape memory alloy sheet 14 is in a high-temperature phase state, the bent portion 142 changes its angle relative to the flat portion 141 and generates a mechanical thrust to push the movable arm 11 upward, so that the movable contact 111 is separated from the fixed contact 121. Among them, the materials of the movable arm 11 and the fixed arm 12 are independently highly conductive copper-based alloys or nickel-based alloys, and the materials of the movable contact 111 and the fixed contact 121 are both conductive precious metals, which ensures that under normal working conditions, most of the current flows through the movable arm 11, the movable contact 111, the fixed contact 121 and the fixed arm 12, and only a very small amount of current passes through the PTC thermistor 13; at the same time, since these alloys have low resistance characteristics, they can provide efficient current conduction under high current conditions and reduce heat generation caused by resistance, thereby meeting the needs of high current operation. In addition, the PTC thermistor 13 is fixedly connected to the fixed arm 12 and the flat portion 141 of the shape memory alloy, respectively, and the movable arm 11 is fixedly connected to a part of the curved portion 142 or the flat portion 141, so that the movable arm 11, the shape memory alloy sheet 14, the PTC thermistor 13 and the fixed arm 12 are firmly connected as a whole, ensuring that the heat and electrical conduction paths are firm and smooth, thereby ensuring that even in the event of severe vibration or external impact, the various components can maintain stable contact, avoiding the risk of instantaneous poor contact or component failure.

[0035] Please continue to see Figure 1 to Figure 4When the anti-shock circuit protection element 100 of the present invention is in a normal working state, the movable contact 111 contacts the fixed contact 121, and the current flows in from an external port T1, most of which flows through the movable arm 11, the movable contact 111, the fixed contact 121 and the fixed arm 12, and then flows out from another external port T2. When the current increases abnormally and causes the movable arm 11 to heat up sharply, the temperature of the shape memory alloy sheet 14 also rises accordingly, until the transition temperature is reached, the angle of the bent portion 142 changes relative to the flat portion 141 to generate a mechanical thrust. Since the movable arm 11 is made of a copper-based alloy or a nickel-based alloy material with high elasticity, The mechanical thrust thus generated can effectively lift the movable arm 11 upward, so that the movable contact 111 is separated from the fixed contact 121. At this time, the current is directed to the PTC thermistor 13, thereby starting the secondary protection mechanism. Since the internal resistance of the PTC thermistor 13 is significantly higher than that of the movable arm 11 and the fixed arm 12, the abnormal current can be suppressed to a certain extent. Moreover, after the PTC thermistor 13 is energized, the memory alloy can be heated to maintain its high-temperature phase shape; if the current exceeds the set value, the PTC thermistor 13 will be activated, thereby effectively reducing the current and protecting the circuit and equipment. Therefore, the circuit protection element of the present invention has an overcurrent protection function.

[0036] Please continue to see Figure 1 to Figure 4 In the anti-shock circuit protection element 100 provided by the present invention, the upper and lower surfaces of the shape memory alloy sheet 14 are respectively attached to the movable arm 11 and the PTC thermistor 13, and the shape memory alloy sheet 14 is in a planar state in the low temperature phase state, which enables the shape memory alloy sheet 14 to be closely attached to the adjacent movable arm 11 and the PTC thermistor 13, making the overall structure more compact, thus saving more space, and more in line with the current requirements for miniaturization and micro-miniaturization of electronic components. In addition, the PTC thermistor 13 can form good thermal contact with the shape memory alloy sheet 14 and the movable arm 11, respectively, thereby improving the heat conduction efficiency and helping to improve the response sensitivity to the temperature change of the surrounding environment (such as the movable arm 11).

[0037] It is worth noting that when the external environment temperature rises abnormally, it will cause the temperature inside the circuit protection element 100 to rise, which will also trigger the angle change of the curved portion 142 relative to the flat portion 141 to separate the movable contact 111 from the fixed contact 121. At this time, the current is directed to the PTC thermistor 13 to activate the secondary protection mechanism to prevent the device from being damaged by high temperature. Therefore, the anti-shock circuit protection element 100 provided by the present invention can not only provide protection when the current is overloaded, but also once the external environment temperature is too high, even if the current flowing through the anti-shock circuit protection element 100 remains within the normal working range, it can also activate the secondary protection mechanism to ensure the safety of the system, thereby realizing the over-temperature protection function.

[0038] Please continue to see Figure 1 to Figure 4 In the anti-shock circuit protection element 100 provided by the present invention, the shape memory alloy sheet 14 includes a flat portion 141 and a curved portion 142, and the flat portion 141 is fixedly connected to the PTC thermistor 13; the movable arm 11 is fixedly connected to a part of the curved portion 142 or the flat portion 141, so that the shape memory alloy sheet 14 can still maintain a large area contact with the PTC thermistor 13 in the high temperature phase state, so that heat conduction can be more efficiently performed, so that in the secondary protection mode, the PTC thermistor 13 can more effectively heat the shape memory alloy sheet 14 and maintain its specific shape in the high temperature phase state, which ensures that the anti-shock circuit protection element 100 can respond quickly and stably perform the secondary protection function when encountering overcurrent or overtemperature conditions, thereby ensuring the safety and reliability of the circuit.

[0039] Specifically, when the circuit fault is eliminated and the current returns to normal levels or when the ambient temperature drops to a normal range, the shape memory alloy sheet 14 changes from a bent state in a high-temperature phase to a planar state in a low-temperature phase, prompting the movable arm 11 to reset, thereby re-contacting the movable contact 111 with the fixed contact 121, and the circuit automatically returns to normal working state. This automatic reset feature reduces the need to replace the fuse, so the anti-shock circuit protection element 100 of the present invention can reduce resource consumption.

[0040] Specifically, the shape memory alloy sheet 14 of the present invention as a temperature-sensitive element has a double-layer shape memory effect. For example, through alloy shape training, the shape memory alloy sheet 14 can be flat when the temperature is lower than the transition temperature, and partially bent or twisted when the temperature is higher than the transition temperature. More specifically, when the temperature rises to a specific transition temperature, the shape memory alloy sheet 14 will change from Figure 1 The martensite phase at low temperature is transformed into Figure 3 The austenite phase at high temperature is shown. During this phase transformation process, the shape memory alloy sheet 14 will deform and form a certain degree of bending or twisting. The specific degree of deformation and bending can be designed and processed according to the actual application requirements. On the contrary, when the temperature drops below the transformation temperature, the shape memory alloy sheet 14 can recover from the austenite phase to the original martensite phase. This two-way phase transformation characteristic enables the shape memory alloy sheet 14 to reversibly change its shape when the temperature changes.

[0041] Please continue to refer to Figure 1 and Figure 3, through alloy shape training, the end of the plane part 141 close to the movable contact 111 can be bent upward to form a bent part 142, and the plane part 141 is fixedly connected to the movable arm 11 and the PTC thermistor 13 respectively. When the temperature rises to a specific transformation temperature, the shape memory alloy sheet 14 transforms from the martensite phase in the low temperature state to the austenite phase in the high temperature state. During this phase transformation process, the angle of the bent part 142 relative to the plane part 141 changes, thereby generating a mechanical thrust to push the movable arm 11 upward, so that the movable contact 111 is separated from the fixed contact 121. At this time, the current is directed to the PTC thermistor 13 to start the secondary protection mechanism. Therefore, the shape memory alloy sheet 14 can effectively cause the movable contact 111 to separate from the fixed contact 121 in the high temperature phase state, realize the over-temperature and over-current protection function and can automatically reset, providing a reliable protection mechanism for the circuit.

[0042] Also, see Figure 5-6 , the alloy shape training can be used to make the bending portion 142 include a first bending portion 1421 and a second bending portion 1422. The first bending portion 1421 is formed by bending one end of the plane portion 141 close to the movable contact 111 upward, and the second bending portion 1422 is formed by bending one end of the first bending portion 1421 close to the movable contact 111 downward. The plane portion 141 is fixedly connected to the PTC thermistor 13, and the second bending portion 1422 is fixedly connected to the movable arm 11. When the temperature rises to a specific transformation temperature, the shape memory alloy sheet 14 transforms from the martensite phase at a low temperature to the austenite phase at a high temperature. During this phase transformation process, the angle of the bending portion 142 changes relative to the plane portion 141, thereby generating a mechanical thrust to lift the movable arm 11 upward, so that the movable contact 111 is separated from the fixed contact 121. At this time, the current is directed to the PTC thermistor 13, thereby starting the secondary protection mechanism. Therefore, if Figure 5-6 The shape memory alloy sheet 14 shown can also effectively separate the movable contact 111 from the fixed contact 121 in the high temperature phase state, realize the over-temperature and over-current protection function and can automatically reset, providing a reliable protection mechanism for the circuit.

[0043] In addition, see Figure 7-8Through alloy shape training, the bending portion 142 includes a first bending portion 1421, a connecting portion 1423, and a second bending portion 1422. The first bending portion 1421 is formed by bending upward one end of the planar portion 141 close to the movable contact 111, the connecting portion 1423 is formed by bending horizontally one end of the first bending portion 1421 close to the movable contact 111, and the second bending portion 1422 is formed by bending downward one end of the connecting portion 1423 close to the movable contact 111. The planar portion 141 is fixedly connected to the PTC thermistor 13, and the connecting portion 1423 is fixedly connected to the movable arm 11. When the temperature rises to a specific transition temperature, the shape memory alloy sheet 14 transforms from the martensite phase at a low temperature to the austenite phase at a high temperature. During this phase transformation process, the angle of the curved portion 142 relative to the flat portion 141 changes, thereby generating a mechanical thrust to push the movable arm 11 upward, so that the movable contact 111 is separated from the fixed contact 121. At this time, the current is directed to the PTC thermistor 13, thereby starting the secondary protection mechanism. Figure 7-8 The shape memory alloy sheet 14 shown can also effectively separate the movable contact 111 from the fixed contact 121 in the high temperature phase state, realize the over-temperature and over-current protection function and can automatically reset, providing a reliable protection mechanism for the circuit.

[0044] It is necessary to explain that in the description of the embodiments of the present invention, the orientation or position relationship indicated by the terms "upper", "lower", "horizontal", "upper surface", "lower surface", etc. is defined according to the layout shown in the drawings. Figure 1 When the fixed arm 12 is shown at the bottom and the movable arm 11 is shown at the top, "upward" refers to the direction from the fixed arm 12 toward the movable arm 11, the "upper surface" of the shape memory alloy sheet 14 refers to the side of the shape memory alloy sheet 14 adjacent to the movable arm 11, and "horizontal" is defined as a direction parallel to the surface of the fixed arm 12. Therefore, these terms do not indicate or imply that the elements referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limitations on the present invention.

[0045] Copper-based or nickel-based alloys have high electrical conductivity, high thermal conductivity and high elasticity, so copper-based or nickel-based alloys are ideal materials for manufacturing the movable arm 11 and the fixed arm 12. Specifically, the movable arm 11 and the fixed arm 12 can be made of copper-based alloys or nickel-based alloys by conventional methods such as cutting and stamping, wherein the materials of the movable arm 11 and the fixed arm 12 are independently selected from Cu-Ni-Si-Mg alloys, Cu-Ni-Si-P alloys, Cu-Ni-Sn-P alloys, Cu-Ni-Co-Si alloys, Cu-Ni-Si alloys, Cu-Zr alloys, Cu-Be alloys, Cu-Ni-Be alloys, Cu-Sn alloys, Cu -Mg-P alloy, Cu-Zn-Sn alloy, Cu-Fe-P alloy, Cu-Fe-Mg-P alloy, Ni-Be alloy; in particular, when Cu-Ni-Si-Mg alloy is selected as the material of the movable arm 11 and the fixed arm 12, this alloy exhibits the most excellent comprehensive performance; the chemical composition of the Cu-Ni-Si-Mg alloy is calculated by mass percentage: 3.0% Ni, 0.65% Si, 0.15% Mg, and the balance is Cu. In addition, in order to meet design and functional requirements, the movable arm 11 and the fixed arm 12 can be made into a thin sheet with a thickness between 50 and 500 microns.

[0046] Specifically, chemical plating or electroplating technology can be used to attach a noble metal with excellent conductivity to the movable arm 11 and the fixed arm 12 to prepare the movable contact 111 and the fixed contact 121. The material of the movable contact 111 and the fixed contact 121 is independently at least one of gold, silver, and a gold-silver alloy; preferably, the material of the movable contact 111 and the fixed contact 121 is silver.

[0047] Specifically, the PTC thermistor 13 can be fixedly connected to the fixed arm 12 and the plane portion 141 by welding or conductive adhesive bonding; similarly, the movable arm 11 can be fixedly connected to a part of the curved portion 142 or the plane portion 141 by welding or conductive adhesive bonding. It is worth noting that the fixed connection here can be selected to cover the entire surface to ensure that the entire contact surface is firmly connected; or it can be selected to be partially connected in a specific area, that is, only fixed at a key position. In addition, welding or conductive adhesive bonding technology is well known to those skilled in the art, so it will not be repeated here.

[0048] Among them, the material of the shape memory alloy sheet 14 is at least one of nickel-titanium alloy, copper alloy and iron alloy. More specifically, the material of the shape memory alloy sheet 14 is at least one of Ni-Ti alloy, Ni-Ti-Cu alloy, Ni-Ti-Co alloy, Ni-Ti-Fe alloy, Ni-Ti-Nb alloy, Cu-Zn alloy, Cu-Zn-Al alloy, Cu-Zn-Sn alloy, Cu-Zn-Si alloy, Cu-Zn-Ga alloy, Cu-Sn alloy, Fe-Pt alloy, Fe-Mn-Si alloy, Fe-Ni-Co-Ti alloy, Fe-Mn-Al-Ni alloy, Fe-C-Mn-Si-Cr-Ni alloy. In addition, the PTC thermistor 13 is a polymer PTC (PPTC) thermistor or a ceramic PTC (CPTC) thermistor, and both the PPTC thermistor and the CPTC thermistor are commercially available.

[0049] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention is described in detail with reference to the preferred embodiments, it is not limited to those listed in the embodiments. Those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. An anti-shock circuit protection element, characterized in that: include: case; A movable arm, one end of which is provided with a movable contact and extends into the interior of the shell, and the other end of which extends from one side of the shell; A fixed arm, one end of which extends into the interior of the housing, and the other end of which extends from the other side of the housing, a fixed contact is provided on the fixed arm, the movable contact is in contact with the fixed contact, the movable arm and the fixed arm are independently made of a copper-based alloy or a nickel-based alloy, and the movable contact and the fixed contact are both made of conductive precious metals; PTC thermistor; the PTC thermistor is located inside the housing, and the PTC thermistor is fitted and fixedly connected to the fixed arm; A shape memory alloy sheet, wherein the shape memory alloy sheet is in a planar state in a low temperature phase state, the upper surface of the shape memory alloy sheet is in contact with the movable arm, the lower surface of the shape memory alloy sheet is in contact with the PTC thermistor, the shape memory alloy sheet comprises a planar portion and a curved portion, the planar portion is fixedly connected to the PTC thermistor; the movable arm is fixedly connected to a portion of the planar portion or the curved portion; When the shape memory alloy sheet is in a high temperature phase state, the angle of the curved portion relative to the planar portion changes, thereby generating a mechanical thrust to push up the movable arm, so that the movable contact is separated from the fixed contact.

2. The anti-surge circuit protection element according to claim 1, characterized in that: One end of the planar portion close to the movable contact is bent upward to form the bent portion, and the planar portion is fixedly connected to the movable arm and the PTC thermistor respectively.

3. The anti-surge circuit protection element according to claim 1, characterized in that: The bending portion includes a first bending portion and a second bending portion, the first bending portion is formed by bending upward one end of the planar portion close to the movable contact, and the second bending portion is formed by bending downward one end of the first bending portion close to the movable contact, the planar portion is fixedly connected to the PTC thermistor, and the second bending portion is fixedly connected to the movable arm.

4. The anti-surge circuit protection element according to claim 1, characterized in that: The bending portion includes a first bending portion, a connecting portion, and a second bending portion. The first bending portion is formed by bending one end of the planar portion close to the movable contact upward, the connecting portion is formed by bending one end of the first bending portion close to the movable contact horizontally, and the second bending portion is formed by bending one end of the connecting portion close to the movable contact downward. The planar portion is fixedly connected to the PTC thermistor, and the connecting portion is fixedly connected to the movable arm.

5. The anti-surge circuit protection element according to claim 1, characterized in that: The shape memory alloy sheet is made of at least one of a nickel-titanium alloy, a copper alloy and an iron alloy.

6. The anti-surge circuit protection element according to claim 1, characterized in that: The material of the shape memory alloy sheet is at least one of Ni-Ti alloy, Ni-Ti-Cu alloy, Ni-Ti-Co alloy, Ni-Ti-Fe alloy, Ni-Ti-Nb alloy, Cu-Zn alloy, Cu-Zn-Al alloy, Cu-Zn-Sn alloy, Cu-Zn-Si alloy, Cu-Zn-Ga alloy, Cu-Sn alloy, Fe-Pt alloy, Fe-Mn-Si alloy, Fe-Ni-Co-Ti alloy, Fe-Mn-Al-Ni alloy, and Fe-C-Mn-Si-Cr-Ni alloy.

7. The anti-surge circuit protection element according to claim 1, characterized in that: The materials of the movable arm and the fixed arm are independently selected from at least one of Cu-Ni-Si-Mg alloy, Cu-Ni-Si-P alloy, Cu-Ni-Sn-P alloy, Cu-Ni-Co-Si alloy, Cu-Ni-Si alloy, Cu-Zr alloy, Cu-Be alloy, Cu-Ni-Be alloy, Cu-Sn alloy, Cu-Mg-P alloy, Cu-Zn-Sn alloy, Cu-Fe-P alloy, Cu-Fe-Mg-P alloy, and Ni-Be alloy.

8. The anti-surge circuit protection element according to claim 1, characterized in that: The PTC thermistor is a polymer PTC thermistor or a ceramic PTC thermistor.

9. The anti-surge circuit protection element according to claim 1, characterized in that: The movable arm and the fixed arm each independently have a thickness of 50 to 500 μm.

10. The anti-surge circuit protection component according to claim 1, characterized in that: The movable contact and the fixed contact are each independently made of at least one of gold, silver, and a gold-silver alloy.

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