CN102693879A - Thermal actuator and relay - Google Patents

Abstract

The invention discloses a thermal actuator, which comprises a magnetic force control unit, a magnetic flux control unit, a thermal detection unit and a first soft magnetic element. The magnetic force control unit includes a permanent magnet and a second soft magnetic element, the magnetic flux control unit includes a magnetostrictive element and a shape memory alloy element; the shape memory alloy element is attached to the outside of the magnetostrictive element; the magnetic flux control unit and the magnetic force control unit form a second A magnetic circuit; the first soft magnetic element and the magnetic control unit form a second magnetic circuit; the thermal detection unit obtains heat from the outside, and heats the shape memory alloy element; The stretching element exerts pressure to make the magnetic flux of the first magnetic circuit smaller than the magnetic flux of the second magnetic circuit, and the first soft magnetic element is attracted to the second soft magnetic element. In addition, the invention also discloses a relay. The thermal actuator and relay provided by the embodiments of the present invention can provide reliable overload protection for electrical equipment in various industrial environments.

Description

A thermal actuator and relay

technical field

The invention relates to the technical field of electrical control, in particular to a thermal actuator and a relay. the

Background technique

Overload relay (overload relay) is an electrical switch, mainly used to protect electrical equipment and prevent overheating caused by overcurrent from damaging electrical equipment. For example, when the motor is overloaded, the current in the winding of the motor will increase, which will increase the temperature of the winding of the motor. By using the overload relay, the power supply of the motor can be disconnected in time to prevent the motor winding from being burned due to overheating. the

At present, overload relays commonly used in practical applications include bimetallic-based relays and circuit-based relays. the

The bimetallic relay includes two kinds of metal sheets with different expansion coefficients. When the current passing through the heating element is too large, the heat generated by the heating causes the bimetal sheet to be heated and bent, thereby pushing the driving mechanism to make the contacts move and disconnect the circuit. However, due to the low rigidity of the bimetallic strip, mechanical vibrations during actual transportation or application can easily cause the bimetallic strip to resonate, eventually destroying the bimetallic relay. Also, bimetallic relays cannot sense the magnitude of current or heat, so bimetallic relays cannot precisely determine when to break a circuit. the

Circuit-based relays include a microprocessor capable of monitoring current through phase conductors attached to the motor and estimating temperature based on samples of the current. When the estimated temperature is greater than the predetermined value, the microprocessor controls the contact action to disconnect the circuit. However, since the electrical components in the circuit-based relay are susceptible to electromagnetic interference (Electro Magnetic Interference, EMI), the reliability of the circuit-based relay is reduced. In addition, circuit-based relays often include power circuits, so disturbances to the power circuits can also affect the reliability of circuit-based relays. the

It can be seen that the existing relays, such as bimetallic relays and circuit-based relays, have the above-mentioned disadvantages, so in practical industrial applications, especially in harsh industrial environments, the reliability of the existing relays is not high enough. the

Contents of the invention

The embodiment of the present invention provides a thermal actuator and a relay to provide reliable overload protection for electrical equipment in various industrial environments. the

In order to solve the above technical problems, embodiments of the present invention provide the following technical solutions. the

An implementation method of the present invention provides a thermal actuator, comprising:

A magnetic control unit, a magnetic flux control unit, a thermal detection unit and a first soft magnetic element; wherein, the magnetic control unit includes a permanent magnet and a second soft magnetic element, and the magnetic flux control unit includes a magnetostrictive element and a shape memory alloy element; the shape memory alloy element is attached to the outside of the magnetostrictive element; the flux control unit and the magnetic force control unit form a first magnetic circuit; the first soft magnetic element and the magnetic force control unit The unit forms a second magnetic circuit;

The heat detection unit is used to obtain heat from the outside, and heat the shape memory alloy element;

When the shape memory alloy element's own temperature is greater than the transition temperature, it applies pressure to the magnetostrictive element, so that the magnetic flux of the first magnetic circuit is smaller than the magnetic flux of the second magnetic circuit;

When the magnetic flux of the first magnetic circuit is smaller than the magnetic flux of the second magnetic circuit, the first soft magnetic element is attracted to the second soft magnetic element. the

In one embodiment of the present invention, the thermal detection unit includes:

a first heat detection module for capturing heat from an external circuit; and/or

The second heat detection module is used to obtain heat from the external environment. the

In one embodiment of the present invention, the thermal detection unit includes a heating coil, and the heating coil is wound on the shape memory alloy element; or, the thermal detection unit includes a thermal resistor; the thermal resistor is attached to the on the shape memory alloy element. the

In one embodiment of the present invention, the permanent magnet forms a groove, the second soft magnetic element includes a first part and a second part, one end of the permanent magnet is connected with one end of the first part, and the The other end of the permanent magnet is connected to one end of the second part, and the two ends of the magnetostrictive element are respectively connected to the first part and the second part. the

In one embodiment of the present invention, the second soft magnetic element is attached to the periphery of the permanent magnet, and forms a groove with the permanent magnet, and the hysteresis stretching element is located in the groove, and is in contact with the permanent magnet. The second soft magnetic element is connected. the

In one embodiment of the present invention, the permanent magnet is divided into two parts, the second soft magnetic element includes a first part, a second part and a third part, and the two parts of the first part of the second soft magnetic element The ends are respectively connected to the first ends of the two parts of the permanent magnet, the second part of the second soft magnetic element is connected to the second end of one part of the permanent magnet, and the first end of the second soft magnetic element The three parts are connected with the second end of the other part of the permanent magnet, and the hysteresis stretch element is connected with the second part and the third part of the second soft magnetic element. the

In one embodiment of the present invention, the shape memory alloy element surrounds the magnetostrictive element. the

An embodiment of the present invention provides a relay, including: the above-mentioned thermal actuator, a buckle element, an insulating element, a conductive element and at least two circuit contacts, the buckle element and the first contact of the thermal actuator A soft magnetic element is in contact with the second soft magnetic element, and the conductive element is connected to the first soft magnetic element through the insulating element;

The at least two circuit contacts are connected to an external circuit;

When the first soft magnetic element is separated from the second soft magnetic element, the conductive element is in contact with the at least two circuit contacts, and when the first soft magnetic element is separated from the second soft magnetic element When the element is attracted, the conductive element is separated from the at least two circuit contacts. the

In one embodiment of the present invention, at least one circuit contact of the at least two circuit contacts is connected to the power supply of the external circuit, and at least another circuit contact of the at least two circuit contacts Connected to the electrical equipment of the external circuit. the

In one embodiment of the present invention, the thermal detection unit is connected in series with the external circuit. the

In one embodiment of the present invention, the relay further includes: a reset unit, configured to separate the first soft magnetic element and the second soft magnetic element that are in the attracted state. the

In one embodiment of the present invention, the reset unit includes a reset button and a reset mechanism rigidly connected to the reset button,

The reset button is used to provide a mechanical driving force for the reset mechanism when pressed;

The reset mechanism is used to separate the first soft magnetic element and the second soft magnetic element in the suction state by using the mechanical driving force from the reset button. the

The thermal actuator and relay provided by the embodiments of the present invention have the following advantages. the

First, in the thermal actuator and relay provided by the embodiments of the present invention, when the shape memory alloy element is heated to a temperature higher than the transition temperature, pressure is applied to the hysteretic element, and the first soft magnetic element It is attracted to the second soft magnetic element without a microprocessor or a power circuit, so it will not be affected by EMI from the outside and interference from the power circuit. the

Secondly, the rigidity of each component in the thermal actuator and the relay in the embodiment of the present invention is relatively high, which can well resist external mechanical vibration. the

Further, the shape memory alloy element in the embodiment of the present invention will only deform when its own temperature is higher than the transition temperature, thereby exerting pressure on the magnetostrictive element. Therefore, shape memory alloy elements with different transition temperatures can be selected according to needs, so as to determine the temperature value or current value when the circuit is disconnected, and accurately determine when to disconnect the circuit. the

Further, the mechanical structure of the thermal actuator and the relay in the embodiment of the present invention is simpler, and the stroke of the second soft magnetic element is longer, so that the contact can be actuated without using a special driving mechanism to amplify the stroke, and the circuit can be disconnected. Open, further avoiding the generation of mechanical fatigue, improving the reliability of thermal actuators and relays. the

In addition, using the thermal actuators and relays in the embodiments of the present invention can not only avoid damage caused by electrical equipment overload, but also not release heat to the outside, reducing the impact on external equipment and the environment. Moreover, when the external environment is too high, the circuit can also be cut off, thereby avoiding the occurrence of fire. the

Description of drawings

Fig. 1 is a schematic diagram of the structure of a thermal actuator in an embodiment of the present invention. the

Fig. 2 is a schematic diagram of the magnetic flux distribution of the thermal actuator in the on state in the embodiment of the present invention. the

Fig. 3 is a schematic diagram of the magnetic flux distribution at a certain moment in the process of entering the closed state of the thermal actuator in the embodiment of the present invention. the

Fig. 4 is a schematic diagram of the structure of the relay in the on state in the embodiment of the present invention. the

Fig. 5 is a schematic diagram of the structure of the relay in the off state in the embodiment of the present invention. the

FIG. 6 is a schematic diagram of the structure of a relay including a reset unit in an embodiment of the present invention. the

Detailed ways

In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the following examples are given to further describe the embodiments of the present invention in detail. the

The thermal actuator provided by the embodiment of the present invention includes a magnetic force control unit, a magnetic flux control unit, a thermal detection unit and a first soft magnetic element. Wherein, the magnetic force control unit includes a permanent magnet and a second soft magnetic element, and the magnetic flux control unit includes a hysteresis stretch element and a shape memory alloy element. Wherein, the shape memory alloy element is attached to the outside of the magnetostrictive element; the flux control unit and the magnetic force control unit form a first magnetic circuit, and the first soft magnetic element and the magnetic force control unit form a second magnetic circuit. The thermal detection unit is used to obtain heat from the outside and heat the shape memory alloy element; when the shape memory alloy element itself is higher than the transition temperature, it applies pressure to the magnetostrictive element, increasing the magnetic resistance of the magnetostrictive element , when the magnetic flux of the first magnetic circuit is smaller than the magnetic flux of the second magnetic circuit, the first soft magnetic element is attracted to the second soft magnetic element, thereby providing a driving action. the

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. the

Fig. 1 shows a schematic diagram of the structure of a thermal actuator in an embodiment of the present invention. As shown in FIG. 1 , the thermal actuator includes a magnetic force control unit 10 , a magnetic flux control unit 11 , a thermal detection unit 12 and a first soft magnetic element 13 . Wherein, the magnetic force control unit 10 includes a permanent magnet 101 and a second soft magnetic element 102 , and the magnetic flux control unit 11 includes a hysteretic stretch element 111 and a shape memory alloy element 112 . the

In this embodiment, the permanent magnet 101 may be a cuboid or a cylinder, and correspondingly, the cross section of the second soft magnetic element 102 is a cuboid or a cylinder. As shown in Figure 1, the shape of the magnetic force control unit 10 is U-shaped, the second soft magnetic element 102 is attached to the periphery of the permanent magnet 101, and forms a groove with the permanent magnet 101, and the magnetostrictive element 111 is located in the groove and It is connected with the second soft magnetic element 102 . Preferably, the permanent magnet 101 is divided into two parts, and the second soft magnetic element 102 is divided into three parts, which are respectively attached to the peripheries of the two parts of the permanent magnet 101 . Specifically, the two ends of the first part of the second soft magnetic element 102 are respectively connected to the first ends of the two parts of the permanent magnet 101, and the second part of the second soft magnetic element 102 is connected to the second end of one part of the permanent magnet 101. The ends are connected, and the third part of the second soft magnetic element 102 is connected with the second end of the other part of the permanent magnet 101 . The magnetic flux control unit 11 is located in the groove formed by the magnetic force control unit 10, wherein the hysteresis stretching element 111 is connected with the second soft magnetic element 102, preferably, the hysteresis stretching element 111 is respectively connected with the first soft magnetic element 102 of the second soft magnetic element 102. The second part is connected to the third part. the

The magnetic force control unit 10 shown in Fig. 1 is only a preferred example of the present invention, in practical application, the magnetic force control unit 10 also can adopt other structures, as the first part of above-mentioned second soft magnetic element 102 also can be permanent magnet, namely The magnetic force control unit 10 includes a permanent magnet 101 whose shape forms a groove and second soft magnetic elements 102 attached to both ends of the permanent magnet. the

The shape memory alloy element 112 surrounds the hysteresis element 111, and the thermal detection unit 12 is connected to the shape memory alloy element 112 to heat it. It can be seen that in this embodiment, the magnetic flux control unit 11 and the magnetic force control unit 10 form a first magnetic circuit; the first soft magnetic element 13 and the magnetic force control unit 10 form a second magnetic circuit. the

Specifically, the first soft magnetic element 13 and the second soft magnetic element 102 in this embodiment do not generate a magnetic field themselves, but only play the role of magnetic force line transmission in the magnetic circuit. In practical applications, the second soft magnetic element 102 may be a yoke. the

The heat detection unit 12 can acquire heat from the outside. Specifically, the heat detection unit 12 may include a first heat detection module for obtaining heat from an external circuit. For example, when connected in series with an external circuit, the temperature of the thermal detection unit 12 is proportional to the current flowing through the thermal detection unit 12, so that the thermal detection unit 12 can obtain heat from the external circuit. In practical applications, the thermal detection unit 12 may be a heating coil wound on the shape memory alloy element 112 ; or the thermal detection unit 12 may be a thermal resistor attached to the shape memory alloy element 112 . In addition, the heat detection unit 12 may also include a second heat detection module, which is used to directly obtain heat from the external environment. For example, the heat detection unit 12 can directly obtain heat from the surrounding environment through heat conduction. the

In the embodiment, the magnetic permeability of the hysteretic element 111 is much larger than the air gap, and according to the reverse magnetostrictive effect, when the pressure is applied on the hysteretic element 111, the magnetic permeability of the hysteretic element 111 varies with As the pressure increases, it decreases, that is, the reluctance increases, so that the magnetic force lines of the first magnetic circuit decrease, and the magnetic flux decreases. When the applied pressure is released, the magnetic permeability of the magnetostrictive element 111 increases, that is, the magnetic resistance decreases, so that the magnetic field lines of the first magnetic circuit increase and the magnetic flux increases. the

As shown in Figure 1, the magnetostrictive element 111 in this embodiment is a cuboid, and the shape memory alloy element 112 can be attached to at least one side of the magnetostrictive element 111. Preferably, in order to apply a uniform contraction force to the magnetostrictive element 111 , the shape memory alloy element 112 surrounds the magnetostrictive element 111 , that is, is attached to four surfaces of the magnetostrictive element 111 . In this embodiment, the shape memory alloy 140 can be attached around the magnetostrictive element 111 . In addition, the magnetostrictive element 111 in this embodiment may also be a cylinder, and the shape memory alloy element 112 surrounds the magnetostrictive element 111, that is, the cross section of the shape memory alloy element 112 is circular. the

In practical applications, the magnetostrictive element 111 may be a giant magnetostrictive material (TERFENOL-D). The above is just an example of the present invention, and other materials can also be used as the hysteresis element 111 when implementing the present invention. the

Since the shape memory alloy element 112 has a shape memory function, it is used to provide pressure applied to the magnetostrictive element 111 . When heated to the transition temperature, the shape memory alloy element 112 can quickly return to its original shape, and before being heated to the transition temperature, the shape memory alloy element 112 will not expand due to heat, so it will not Applying pressure to the hysteretic element 111 will not cause misoperation. In practical applications, the shape memory alloy element 112 may be a copper-zinc-aluminum-nickel alloy, a copper-aluminum-nickel alloy, or a nickel-titanium alloy. The above is just an example of the present invention, and other materials can also be used as the shape memory alloy element 112 when implementing the present invention. the

Those skilled in the art can understand that in the embodiment of the present invention, the force applied to the magnetostrictive element 111 by the shape memory alloy element 112 causes the magnetic permeability of the magnetostrictive element 111 to change, thereby changing the first magnetic circuit and the second magnetic circuit. Magnetic flux in the second magnetic circuit. Therefore, when implementing the embodiments of the present invention, other construction methods capable of realizing the above functions are also within the protection scope of the present invention. the

The working process of the thermal actuator in the embodiment of the present invention will be described below based on the thermal actuator shown in FIG. 1 . the

Fig. 2 shows a schematic diagram of the magnetic flux distribution of the thermal actuator in the on state in the embodiment of the present invention. In this embodiment, the state before the shape memory alloy element 112 is heated to the transition temperature, that is, the state when the first soft magnetic element 13 is separated from the second soft magnetic element 102 is taken as the on state of the thermal actuator. the

As shown in FIG. 2 , the magnetic flux control unit 11 and the magnetic force control unit 10 form a first magnetic circuit; the first soft magnetic element 13 forms a second magnetic circuit with the magnetic force control unit 10 through a gap. When the thermal actuator is turned on, if the heat obtained from the outside by the thermal detection unit 12 cannot heat the shape memory alloy element 112 to its transition temperature, the shape memory alloy element 112 will not exert pressure on the magnetostrictive element 111 . At this time, since the magnetic permeability of the hysteretic element 111 is much higher than that of the air gap, the magnetic flux of the first magnetic circuit is much larger than that of the second magnetic circuit. In this way, the magnetic force between the permanent magnet 101 and the first soft magnetic element 13 is very small, so that the first soft magnetic element 13 and the second soft magnetic element 102 are kept separated. the

Fig. 3 shows a schematic diagram of the magnetic flux distribution at a certain moment in the process of entering the closed state of the thermal actuator in the embodiment of the present invention. the

In this embodiment, the state after the shape memory alloy element 112 is heated to the transition temperature, that is, the state when the first soft magnetic element 13 is attracted to the second soft magnetic element 102 is taken as the closed state of the thermal actuator. the

As shown in Figure 3, when the heat obtained from the outside by the thermal detection unit 12 heats the shape memory alloy element 112 to its transition temperature, the shape memory alloy element 112 is deformed, and pressure is applied to the magnetostrictive element 111 to make the hysteresis The magnetic permeability of the telescoping element 111 is reduced. Accordingly, the reluctance of the first magnetic circuit increases, and the magnetic flux of the second magnetic circuit increases. In this way, the magnetic force between the permanent magnet 101 and the first soft magnetic element 13 increases, and the first soft magnetic element 13 moves toward the permanent magnet 101 . What Fig. 3 shows is the schematic diagram of a certain moment in the process that the first soft magnetic element 13 moves to the permanent magnet 101, along with the reduction of the space between the first soft magnetic element 13 and the second soft magnetic element 102, the first soft magnetic element 13 and the second soft magnetic element 102 reduce, The magnetic flux of the two magnetic circuits increases continuously until the first soft magnetic element 13 and the second soft magnetic element 102 attract. the

It can be seen that the thermal actuator provided by the embodiment of the present invention does not need a microprocessor or a power supply circuit while providing driving action, so it will not be affected by external EMI and interference from the power supply circuit; and the thermal actuator in the embodiment of the present invention The hardness of each component in the actuator is relatively high, which can resist external mechanical shocks; further, in the application, the transition temperature of the shape memory alloy component can be selected according to the needs, so as to determine the timing of providing driving action; at the same time , the mechanical structure of the thermal actuator in the embodiment of the present invention is simpler, and can avoid the generation of mechanical fatigue, and improves the reliability of the thermal actuator and the relay; The release of heat reduces the impact on external equipment and the environment; and, when the temperature of the external environment reaches the transition temperature of the shape memory alloy, the thermal actuator provided by the embodiment of the present invention can also provide driving action to avoid the occurrence of fire. the

Based on the driving action of the thermal actuator in the embodiment of the present invention, the function of the relay can be realized. Connecting the first soft magnetic element 13 to the contact of the circuit can utilize the driving action of the thermal actuator to disconnect the circuit. the

The embodiment of the present invention also provides a relay, including the above-mentioned thermal actuator, a buckle element, an insulating element, a conductive element and at least two circuit contacts. The buckle element is in contact with the first soft magnetic element and the second soft magnetic element of the thermal actuator. The conductive element is connected with the first soft magnetic element through the insulating element. At least two circuit contacts are connected, eg in series, to the circuit to be protected. Specifically, at least one circuit contact of the at least two circuit contacts is connected to a power source of the external circuit, and at least another circuit contact of the at least two circuit contacts is connected to an electrical device of the external circuit. When the first soft magnetic element is separated from the second soft magnetic element, the conductive element contacts the at least two circuit contacts, and when the first soft magnetic element is attracted to the second soft magnetic element, the conductive element is in contact with the at least two circuit contacts. At least two circuit contacts are separated. In practical applications, the number of circuit contacts can be set according to the needs of the actual circuit. the

The working process of the relay provided by the embodiment of the present invention will be described in detail below with reference to the accompanying drawings. the

Fig. 4 shows the structure of the relay in the on state in the embodiment of the present invention. In this embodiment, the number of circuit contacts is two, and the state when the conductive element is connected to the two circuit contacts is the on state of the relay. the

As shown in FIG. 4 , the relay includes a thermal actuator, a buckle element 14 , an insulating element 15 , a conductive element 16 and two circuit contacts 17 . the

In the embodiment of the present invention, the buckle element 14 includes at least a spring 141 and a slider 142 . When the first soft magnetic element is separated from the second soft magnetic element, the spring 141 applies pressure to the first soft magnetic element through the slider 142, not only keeping the first soft magnetic element and the second soft magnetic element separated, but also making the The conductive element 16 is in intimate contact with the two circuit contacts 17 . During the movement of the first soft magnetic element to the second soft magnetic element, the pressure applied by the spring 141 to the first soft magnetic element is less than the magnetic force between the permanent magnet and the first soft magnetic element, so the spring 141 is compressed, and the slider 142 moves to the outside of the first soft magnetic element, and the first soft magnetic element slides toward the second soft magnetic element. FIG. 4 only shows an example of the buckle element 14 in the embodiment of the present invention. When applying this embodiment, buckles with other structures can also be used, which does not affect the implementation of the present invention. the

In this embodiment, the two circuit contacts 17 are located between the power supply of the external circuit and the electrical equipment, so that when the external circuit is overloaded, the two circuit contacts 17 can disconnect the power supply and the electrical equipment in the external circuit The connection plays the role of overload protection. In practical applications, the two circuit contacts 17 can also be connected in series in other positions of the external circuit, which does not affect the implementation of the present invention. the

In this embodiment, the thermal detector is connected in series with the external circuit, so that when the external circuit is not overloaded, that is, when the current value in the external circuit is not greater than a predetermined value, the heat generated by the current flowing through the thermal detector is insufficient Make the temperature of the shape memory alloy element reach its transition temperature, so the magnetic flux of the first magnetic circuit is greater than the magnetic flux of the second magnetic circuit, the first soft magnetic element and the second soft magnetic element are kept separated, and the conductive element contacts the two circuits. Point connection, the power supply in the external circuit is connected with the electrical equipment, so that the external circuit works normally, and the relay is in the open state. the

Fig. 5 shows the structure of the relay in the off state in the embodiment of the present invention. In this embodiment, the state when the conductive element 16 is disconnected from the circuit contact 17 is the closed state of the relay. the

When the external circuit is overloaded, that is, the current value in the external circuit is greater than a predetermined value, the heat generated by the current flowing through the thermal detector makes the temperature of the shape memory alloy element reach its transition temperature, thereby causing the shape memory alloy element to deform. Apply pressure to the magnetostrictive element. According to the working principle of the thermal actuator described above, since the magnetic resistance of the magnetostrictive element decreases, the magnetic flux of the second magnetic circuit increases. When the magnetic force between the permanent magnet and the first soft magnetic element is greater than the pressure of the buckle element 14, the first soft magnetic element moves toward the second soft magnetic element. As the gap decreases, the reluctance of the second magnetic circuit decreases, the magnetic flux of the second magnetic circuit further increases, and the magnetic force between the permanent magnet and the first soft magnetic component further increases until the first soft magnetic component and the first soft magnetic component The two soft magnetic elements are sucked together. Figure 5 shows the structure and flux distribution of the relay in the off state. As shown in Figure 5, the first soft magnetic element is attracted to the second soft magnetic element, and the conductive element 16 is separated from the two circuit contacts 17, so that the power supply and electrical equipment in the external circuit are disconnected, thereby achieving overload The role of protection. the

It can be seen from the above embodiments that the relay provided by the embodiment of the present invention does not include a microprocessor or a power circuit, so it will not be affected by external EMI and interference from the power circuit. Moreover, in the embodiment of the present invention, the hardness of each component in the relay is relatively high, which can highly resist external mechanical shock. In addition, the shape memory alloy element in the relay will only deform when its own temperature is higher than the transition temperature, so the transition temperature of the shape memory alloy element can be selected according to needs, so as to determine the temperature value or current value when the circuit is disconnected , to determine precisely when to break the circuit. Furthermore, the mechanical structure of the relay in the embodiment of the present invention is simpler, and the stroke of the second soft magnetic element is longer, and the contact can be moved without using a special driving mechanism to amplify the stroke, and the circuit is disconnected, further avoiding The generation of mechanical fatigue improves the reliability of thermal actuators and relays. In addition, the use of the relay in the embodiment of the present invention not only avoids damage caused by electrical equipment overload, but also does not release heat to the outside, reducing the impact on external equipment and the environment. When the temperature of the external environment is too high and reaches the transition temperature of the shape memory alloy, the relay provided by the embodiment of the present invention can also disconnect the circuit, thereby avoiding the occurrence of fire. the

In order to enable the relay to be used repeatedly, the relay in the embodiment of the present invention further includes a reset unit 60 . As shown in FIG. 6 , the reset unit 60 includes a reset button 610 and a reset mechanism 620 connected with the reset button 610 . The reset button 610 can provide a mechanical driving force for the reset mechanism after being pressed, and the reset mechanism 620 utilizes the mechanical driving force from the reset button 610 to connect the first soft magnetic element and the second soft magnetic element in the suction state to each other. The separation of the components returns the relay to the on state and continues to protect the circuit. The reset unit 60 provided in this embodiment has the advantages of simple structure and convenient operation. FIG. 6 only shows an example of the reset unit, and other structures of the reset unit 60 may also be used in practical applications, which does not affect the implementation of the present invention. the

The invention discloses a thermal actuator, which comprises a magnetic force control unit, a magnetic flux control unit, a thermal detection unit and a first soft magnetic element. The magnetic force control unit includes a permanent magnet and a second soft magnetic element, and the magnetic flux control unit includes a magnetostrictive element and a shape memory alloy element; the shape memory alloy element is attached to the outside of the magnetostrictive element; the magnetic flux control unit and the magnetic force control unit form a second A magnetic circuit; the first soft magnetic element and the magnetic control unit form a second magnetic circuit; the thermal detection unit obtains heat from the outside, and heats the shape memory alloy element; The stretching element exerts pressure to make the magnetic flux of the first magnetic circuit smaller than the magnetic flux of the second magnetic circuit, and the first soft magnetic element is attracted to the second soft magnetic element. In addition, the invention also discloses a relay. The thermal actuator and relay provided by the embodiments of the present invention can provide reliable overload protection for electrical equipment in various industrial environments. the

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the protection scope of the present invention. Appropriate improvements can be made to the preferred embodiments according to the present invention in the specific implementation process, so as to meet the specific needs of specific situations. Therefore, it can be understood that the specific implementation manners of the present invention described herein are only exemplary, and are not intended to limit the protection scope of the present invention. the

Claims (12)

1. A thermal actuator comprising: A magnetic force control unit (10), a magnetic flux control unit (11), a thermal detection unit (12) and a first soft magnetic element (13); wherein, the magnetic force control unit (10) includes a permanent magnet (101) and a second The soft magnetic element (102), the magnetic flux control unit (11) includes a magnetostrictive element (111) and a shape memory alloy element (112); the shape memory alloy element (112) is attached to the magnetostrictive element The outer side of (111); the magnetic flux control unit (11) forms a first magnetic circuit with the magnetic force control unit (10); the first soft magnetic element (13) forms a magnetic force control unit (10) second magnetic circuit; The heat detection unit (12) is used to obtain heat from the outside, and heat the shape memory alloy element (112); The shape memory alloy element (112) applies pressure to the magnetostrictive element (111) when its own temperature is higher than the transition temperature, so that the magnetic flux of the first magnetic circuit is smaller than the magnetic flux of the second magnetic circuit. Pass; When the magnetic flux of the first magnetic circuit is smaller than the magnetic flux of the second magnetic circuit, the first soft magnetic element (13) is attracted to the second soft magnetic element (102). 2. The thermal actuator according to claim 1, wherein the thermal detection unit comprises: A first heat detection module for capturing heat from an external circuit; and/or The second heat detection module is used to obtain heat from the external environment. 3. The thermal actuator according to claim 1, wherein, The thermal detection unit (12) includes a heating coil wound on the shape memory alloy element (112); or The thermal detection unit (12) includes a thermal resistor; the thermal resistor is attached to the shape memory alloy element (112). 4. The thermal actuator according to claim 1, wherein the permanent magnet (101) forms a groove, the second soft magnetic element (102) includes a first part and a second part, and the permanent magnet ( One end of 101) is connected with one end of the first part, the other end of the permanent magnet (101) is connected with one end of the second part, and the two ends of the magnetostrictive element (111) are connected with the first part respectively. A part is connected to the second part. 5. The thermal actuator according to claim 1, wherein the second soft magnetic element (102) is attached to the periphery of the permanent magnet (101) and forms a groove with the permanent magnet (101), The hysteresis stretch element (111) is located in the groove and connected with the second soft magnetic element (102). 6. The thermal actuator according to claim 5, wherein the permanent magnet (101) is divided into two parts, and the second soft magnetic element (102) comprises a first part, a second part and a third part, The two ends of the first part of the second soft magnetic element (102) are respectively connected to the first ends of the two parts of the permanent magnet (101), and the second part of the second soft magnetic element (102) is connected to the The second end of one part of the permanent magnet (101) is connected, the third part of the second soft magnetic element (102) is connected with the second end of the other part of the permanent magnet (101), and the hysteresis The telescopic element (111) is connected with the second part and the third part of the second soft magnetic element (102). 7. The thermal actuator according to claim 1, wherein the shape memory alloy element (112) surrounds the magnetostrictive element (111). 8. A relay, said relay comprising: the thermal actuator as claimed in any one of claims 1 to 7, a buckle element (14), an insulating element (15), a conductive element (16) and at least two A circuit contact (17), the buckle element (14) is in contact with the first soft magnetic element (13) and the second soft magnetic element (102) of the thermal actuator, and the conductive element (16) passes through the The insulating element (15) is connected to the first soft magnetic element (13); The at least two circuit contacts (17) are connected to an external circuit; When the first soft magnetic element (13) is separated from the second soft magnetic element (102), the conductive element (16) is in contact with the at least two circuit contacts (17), and when the When the first soft magnetic element (13) is attracted to the second soft magnetic element (102), the conductive element (16) is separated from the at least two circuit contacts (17). 9. The relay according to claim 8, wherein at least one circuit contact (17) in the at least two circuit contacts (17) is connected to the power supply of the external circuit, and the at least two circuit contacts At least one other circuit contact (17) of the contacts (17) is connected to an electrical device of said external circuit. 10. The relay according to claim 8, wherein the thermal detection unit (12) is connected in series with the external circuit. 11. The relay according to claim 8, wherein the relay further comprises: a reset unit (60), which is used to separate the first soft magnetic element (13) and the second soft magnetic element in the pull-in state (102). 12. The relay according to claim 11, wherein the reset unit comprises a reset button (610) and a reset mechanism (620) rigidly connected with the reset button, the reset button (610), configured to provide a mechanical driving force for the reset mechanism when pressed; The reset mechanism (620) is used to use the mechanical driving force from the reset button (610) to place the first soft magnetic element (13) and the second soft magnetic element (102) in the engaged state separate.

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