CN114498555A - Prevent dry combustion method protection circuit - Google Patents

Abstract

The application provides a prevent dry combustion method protection circuit, the circuit includes heating circuit, first control circuit, second control circuit and third control circuit, heating circuit is including the heating element that is used for the heating, first control circuit is used for acquireing the heating temperature of heating element, and control the second control circuit and switch on when heating temperature satisfies the protection condition of preventing dry combustion method of presetting, second control circuit is used for controlling the unit that opens circuit and is in the conducting state, third control circuit is including the unit that opens circuit, the unit that should open circuit is used for the heating state of interruption heating element when being in the conducting state, still be used for keeping the conducting state of the unit that opens circuit, with the validity of the unit that opens circuit to the operation that opens circuit of guarantee heating circuit, make the heating element break away from the heating state, the safety of heating circuit and surrounding environment has been ensured, the security of heating circuit has been improved.

Description

Anti-dry burn protection circuit

technical field

The present application relates to the technical field of circuits, and in particular, to an anti-dry burning protection circuit.

Background technique

The horizontal line drying section is an important equipment for drying the board surface in the PCB production line. During the drying process, the horizontal line drying section needs to keep the drying temperature within the preset temperature range to ensure the working efficiency of the horizontal line drying section or Safety at Work.

FIG. 1 is a schematic structural diagram of the heating circuit of the drying section of the horizontal line. As shown in FIG. 1 , the heating circuit of the drying section of the horizontal line includes an AC power supply 101, a circuit breaker 102, a heating contact 103, a heating unit 104, a control unit 105 and The temperature sensor 106, wherein the AC power supply 101, the circuit breaker 102, the heating contact 103 and the heating unit 104 are connected to form a heating circuit, the control unit 105 is connected with the heating contact 103, and the control unit 105 controls the heating contact according to the obtained heating instruction 103 is turned on to turn on the heating circuit, and the heating unit 104 obtains the electric energy of the AC power source 101 to perform the corresponding heating operation. The heating unit 104 is provided with a temperature sensor 106 for acquiring the temperature of the heating unit 104 , and the control unit 105 is connected to the temperature sensor 106 for acquiring the temperature data acquired by the temperature sensor 106 . When the above-mentioned temperature data exceeds the preset temperature threshold, the control unit 105 controls the heating contact 103 to turn off to interrupt the heating circuit, stop the heating operation of the heating unit 104, and prevent the heating temperature exceeding the preset temperature threshold from affecting the horizontal line drying section and the damage to the PCB. However, the heating contact 103 in an over-temperature environment is prone to melting, and the melted heating contact 103 cannot perform the turn-off operation, so that the heating circuit is always in an on state, and the temperature generated by the drying section of the horizontal line continues to rise. cause a safety hazard.

Therefore, how to improve the safety of the heating circuit has become an urgent problem to be solved.

SUMMARY OF THE INVENTION

The present application provides an anti-dry-burning protection circuit to solve the technical problem of improving the safety of a heating circuit.

The application provides an anti-dry burning protection circuit, the circuit includes a heating loop, a first control loop, a second control loop and a third control loop;

The heating circuit includes a heating unit, and the heating unit is used for heating; the third control loop includes a circuit breaker unit, and the circuit breaker unit is used to interrupt the heating state of the heating unit when it is in an on state; the third control loop is used to maintain the on state of the circuit breaker unit , so that the heating unit is in an unheated state;

The first control loop is used to obtain the heating temperature of the heating unit, and when the heating temperature satisfies the preset dry-burning protection condition, the second control loop is controlled to be turned on; the second control loop is used to control the disconnection unit to be turned on.

In the above technical solution, the anti-dry burning protection circuit controls the conduction state of the first control loop according to the heating state of the heating unit, so as to control the second control loop to control the disconnection unit to be in the conduction state. After the second control loop is turned on, The third control loop maintains the conduction operation of the circuit breaker unit, and performs a forced circuit breaker operation on the heating circuit through the circuit breaker unit, so that after the heating temperature of the heating unit exceeds the temperature, it is cooled by forced circuit breaker, which ensures the safety of the heating circuit and the surrounding environment, and improves the performance of the heating circuit. Safety of heating circuits.

Optionally, the heating circuit further includes a heating control unit, the heating control unit is used to control the heating state of the heating unit, and the heating control unit and the heating unit are connected to form a heating circuit.

Optionally, the heating control unit includes a heating contact and a circuit breaker, the first end of the circuit breaker is connected to the AC power source, the second end of the circuit breaker is connected to the first end of the heating contact, and the second end of the heating contact is connected to the AC power supply. The first end of the heating unit is connected, and the second end of the heating unit is grounded.

Optionally, the first control loop includes a mechanical temperature control unit and an intermediate relay coil, and the mechanical temperature control unit and the intermediate relay coil are connected;

The mechanical temperature control unit is used to obtain the heating temperature of the heating unit, and change the conduction state of the mechanical temperature control unit according to the heating state of the heating unit.

Optionally, the mechanical temperature control unit includes a mechanical temperature control switch, the first end of the intermediate relay coil is connected to the positive pole of the first DC power supply, the second end of the intermediate relay coil is connected to the first end of the mechanical temperature control switch, and the mechanical The second end of the temperature control switch is connected to the negative pole of the first DC power supply.

Optionally, the circuit further includes a control unit;

Wherein, the control unit is connected with the heating contact, and the control unit is used to control the heating contact to be in a conducting state;

The control unit is also connected with the mechanical temperature control switch, and the control unit is used to generate a heating contact control command when the mechanical temperature control switch is in a conductive state, and the heating contact control command is used to control the first control module to make the heating contact in a conductive state .

Optionally, the second control loop includes a second control unit, and the heating control unit in the heating loop and the second control unit are connected to form the second control loop.

Optionally, the second control unit includes an intermediate relay contact and a release coil, the first end of the intermediate relay contact is connected to the second end of the heating contact, and the second end of the intermediate relay contact is connected to the release coil. The first end of the trip unit is connected, and the second end of the release coil is grounded.

Optionally, when the heating temperature satisfies the preset dry-burning protection condition, the second control loop is controlled to be turned on, which specifically includes:

When the heating temperature is greater than the preset temperature threshold of the mechanical temperature control unit, the mechanical temperature control unit is controlled to be turned on and the first control loop is turned on;

According to the conduction state of the intermediate relay coil in the first control loop, the contact of the intermediate relay in the second control loop is controlled to be closed.

Optionally, the third control loop includes a tripper disconnection control unit, and the tripper coil is connected to the tripper disconnection control unit to form the third control loop.

Optionally, the release circuit breaker control unit includes a release contact, and the release contact is used to control the release to perform a tripping operation;

The first end of the release contact is connected to the positive pole of the second DC power supply, the second end of the release contact is connected to the first end of the release coil, and the second end of the release coil is connected to the first end of the release coil. The negative terminal of the two DC power supplies is connected.

The application provides an anti-dry-burning protection circuit. The circuit includes a heating loop, a first control loop, a second control loop and a third control loop. The heating loop includes a heating unit for heating, and the first control loop is used to obtain the heating unit. When the heating temperature meets the preset anti-dry-burning protection conditions, the second control loop is controlled to be turned on, the second control loop is used to control the circuit breaker unit to be in a conducting state, and the third control loop includes a circuit breaker unit, the circuit breaker unit It is used to interrupt the heating state of the heating unit when it is in the on state, and it is also used to maintain the on state of the circuit breaker unit, so as to ensure the effectiveness of the circuit breaker unit for the circuit breaking operation of the heating circuit, so that the heating unit can be separated from the heating state and ensure the heating The safety of the loop and the surrounding environment improves the safety of the heating circuit.

Description of drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the application and together with the description serve to explain the principles of the application.

Fig. 1 is the structural representation of the heating circuit of the horizontal line drying section;

2 is a schematic structural diagram of an anti-dry burning protection circuit provided by an embodiment of the present application;

3 is a schematic structural diagram of an anti-dry burning protection circuit provided by another embodiment of the present application;

FIG. 4 is a schematic structural diagram of an anti-dry burning protection circuit provided by another embodiment of the present application.

Specific embodiments of the present application have been shown by the above-mentioned drawings, and will be described in more detail hereinafter. These drawings and written descriptions are not intended to limit the scope of the concepts of the present application in any way, but to illustrate the concepts of the present application to those skilled in the art by referring to specific embodiments.

Detailed ways

Exemplary embodiments will be described in detail herein, examples of which are illustrated in the accompanying drawings. Where the following description refers to the drawings, the same numerals in different drawings refer to the same or similar elements unless otherwise indicated. The implementations described in the illustrative examples below are not intended to represent all implementations consistent with this application. Rather, they are merely examples of apparatus and methods consistent with some aspects of the present application as recited in the appended claims.

It should be noted that, herein, the terms "comprising", "comprising" or any other variation thereof are intended to encompass non-exclusive inclusion, such that a process, method, article or device comprising a series of elements includes not only those elements, It also includes other elements not expressly listed or inherent to such a process, method, article or apparatus. Without further limitation, an element defined by the phrase "comprises a..." does not preclude the presence of additional identical elements in the process, method, article, or device that includes the element, and further, different implementations of the present application Components, features and elements with the same names in the examples may have the same meaning or may have different meanings, and their specific meanings need to be determined by their explanations in this specific embodiment or further combined with the context in this specific embodiment.

It should be understood that although the terms first, second, third, etc. may be used herein to describe various information, such information should not be limited by these terms. These terms are only used to distinguish the same type of information from each other. For example, first information may also be referred to as second information, and similarly, second information may also be referred to as first information, without departing from the scope of this document. The word "if" as used herein can be interpreted as "at the time of" or "when" or "in response to determining", depending on the context. Also, as used herein, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context dictates otherwise. It should be further understood that the terms "comprising" and "comprising" indicate the presence of features, steps, operations, elements, components, items, kinds, and/or groups, but do not exclude one or more other features, steps, operations, elements, The existence, appearance or addition of components, items, categories, and/or groups. As used herein, the terms "or", "and/or", "including at least one of the following" and the like may be construed to be inclusive or to mean any one or any combination. For example, "comprising at least one of the following: A, B, C" means "any of the following: A; B; C; A and B; A and C; B and C; A and B and C", for example, " A, B or C" or "A, B and/or C" means "any of the following: A; B; C; A and B; A and C; B and C; A and B and C". Exceptions to this definition arise only when combinations of elements, functions, steps, or operations are inherently mutually exclusive in some way.

It should be understood that, although the steps in the flowcharts in the embodiments of the present application are displayed in sequence according to the arrows, these steps are not necessarily executed in the sequence indicated by the arrows. Unless explicitly stated herein, the execution of these steps is not strictly limited to the order and may be performed in other orders. Moreover, at least a part of the steps in the figure may include multiple sub-steps or multiple stages. These sub-steps or stages are not necessarily executed at the same time, but may be executed at different times, and the execution order is not necessarily sequential. Instead, it may be performed in turn or alternately with other steps or at least a portion of sub-steps or stages of other steps.

Depending on the context, the words "if", "if" as used herein may be interpreted as "at" or "when" or "in response to determining" or "in response to detecting". Similarly, the phrases "if determined" or "if detected (the stated condition or event)" can be interpreted as "when determined" or "in response to determining" or "when detected (the stated condition or event)," depending on the context )" or "in response to detection (a stated condition or event)".

It should be understood that the specific embodiments described herein are only used to explain the present application, but not to limit the present application.

The horizontal line drying section is an important equipment for drying the board surface in the PCB production line. During the drying process, the horizontal line drying section needs to keep the drying temperature within the preset temperature range to ensure the working efficiency of the horizontal line drying section or Safety at Work.

FIG. 1 is a schematic structural diagram of the heating circuit of the drying section of the horizontal line. As shown in FIG. 1 , the heating circuit of the drying section of the horizontal line includes an AC power supply 101, a circuit breaker 102, a heating contact 103, a heating unit 104, a control unit 105 and The temperature sensor 106, wherein the AC power supply 101, the circuit breaker 102, the heating contact 103 and the heating unit 104 are connected to form a heating circuit, the control unit 105 is connected with the heating contact 103, and the control unit 105 controls the heating contact according to the obtained heating instruction 103 is turned on to turn on the heating circuit, and the heating unit 104 obtains the electric energy of the AC power source 101 to perform the corresponding heating operation. The heating unit 104 is provided with a temperature sensor 106 for acquiring the temperature of the heating unit 104 , and the control unit 105 is connected to the temperature sensor 106 for acquiring the temperature data acquired by the temperature sensor 106 . When the above-mentioned temperature data exceeds the preset temperature threshold, the control unit 105 controls the heating contact 103 to turn off to interrupt the heating circuit, stop the heating operation of the heating unit 104, and prevent the heating temperature exceeding the preset temperature threshold from affecting the horizontal line drying section and the damage to the PCB. However, the heating contact 103 in an over-temperature environment is prone to melting, and the melted heating contact 103 cannot perform the turn-off operation, so that the heating circuit is always in an on state, and the temperature generated by the drying section of the horizontal line continues to rise. cause a safety hazard.

Therefore, how to improve the safety of the heating circuit has become an urgent problem to be solved.

In view of the above technical problems, the embodiments of the present application provide an anti-dry-burning protection circuit, which aims to solve the problem of improving the safety of the heating circuit. The technical idea of the present application is to obtain the heating temperature through a mechanical temperature control unit disposed beside the heating circuit, and control and maintain the circuit breaker unit in a conducting state through an intermediate relay when the heating temperature meets the anti-dry burning protection conditions, so as to realize the circuit breaker unit. Perform and maintain an open circuit to the heating circuit.

FIG. 2 is a schematic structural diagram of an anti-dry-burning protection circuit provided by an embodiment of the application. As shown in FIG. 2 , it includes a heating circuit 201 , a first control circuit 202 , a second control circuit 203 and a third control circuit 204 , wherein, The heating circuit 201 includes a heating unit 205, and the heating unit 205 is used for heating. In one embodiment, the heating unit 205 is a heating pipe of the drying section of the horizontal line. The third control loop 204 includes a circuit breaker unit 206 for interrupting the heating state of the heating unit 205 when in the on state, ie by interrupting the heating circuit 201 to stop the heating unit 205 from converting the received electrical energy into process of thermal energy.

During the operation of the anti-dry-burning protection circuit, the first control loop 202 continuously obtains the heating temperature of the heating unit 205, and when the heating temperature generated by the heating unit 205 in the heating circuit 201 satisfies the preset anti-dry-burning protection condition, the second control loop 202 is controlled. The control loop 203 is turned on. After the second control loop is turned on, the disconnecting unit 206 in the third control loop 204 performs a turn-on operation and is in a turn-on state after the turn-on operation is completed. The third control unit 204 maintains the conduction state of the circuit breaker unit 206, and controls the circuit breaker unit 206 to perform and maintain the circuit breaker operation on the heating circuit 201, so that the heating unit 205 is in an unheated state.

In the above technical solution, the anti-dry burning protection circuit controls the conduction state of the first control loop according to the heating state of the heating unit, so as to control the second control loop to control the disconnection unit to be in the conduction state. After the second control loop is turned on, The third control loop maintains the conduction operation of the circuit breaker unit, and performs a forced circuit breaker operation on the heating circuit through the circuit breaker unit, so that after the heating temperature of the heating unit exceeds the temperature, it is cooled by forced circuit breaker, which ensures the safety of the heating circuit and the surrounding environment, and improves the performance of the heating circuit. Safety of heating circuits.

FIG. 3 is a schematic structural diagram of an anti-dry burning protection circuit provided by another embodiment of the application. As shown in FIG. 3 , the anti-dry burning protection circuit includes a heating loop 201 , a first control loop 202 , a second control loop 203 , and a third Control the control loop 204 and the control unit 211, wherein the control unit 211 is connected with the heating loop 201 and the first control loop 202, and is used to control the heating loop 201 to be turned on and off according to the relevant information of the heating loop 201 obtained by the first control loop 202. break.

The heating circuit 201 includes a heating unit 205 and a heating control unit 207. The heating unit 205 and the heating control unit 207 are connected to form a heating circuit, wherein the heating control unit 207 is used to control the heating state of the heating unit 205, that is, the heating control unit 207 is in conduction. In the ON state, the heating circuit 201 is in the ON state, the heating control unit 207 is in the OFF state, and the heating circuit 201 is in the OFF state.

The first control loop 202 includes an intermediate relay coil 208 and a mechanical temperature control unit 209 , and the intermediate relay coil 208 and the mechanical temperature control unit 209 are connected to form the first control loop 202 . The mechanical temperature control unit 209 is placed next to the heating unit 205 in the heating circuit 201 to obtain the heating temperature of the heating unit 205 . When the heating temperature satisfies the preset dry-burn protection condition, the mechanical temperature control unit 209 is turned on. In the first aspect, the control unit 211 is connected to the mechanical temperature control unit 209. When the mechanical temperature control unit 209 is turned on, the control unit 211 obtains an over-temperature signal, and the control unit 211 controls the heating control unit 207 in the heating circuit 201 to be disconnected to The heating circuit 201 is disconnected, and the heating unit 205 is in an unheated state. In the second aspect, the mechanical temperature control unit 209 is turned on, the first control loop 202 is turned on, and the intermediate relay coil 208 is turned on.

The second control loop 203 includes a heating control unit 207 and a second control unit 210 , and the heating control unit 207 and the second control unit 210 are connected to form the second control loop 203 . The heating control unit 207 in the second control loop 203 is the same as the heating control unit 207 in the heating loop 201 . The conduction state of the second control unit 210 is controlled according to the conduction state of the intermediate relay coil 208 in the first control loop 202 , that is, the intermediate relay coil 208 is turned on, the second control unit 210 is turned on, and the second control loop 203 is turned on Pass.

The third control loop 204 includes a circuit breaker unit 206 including a trip unit circuit breaker control unit 212 . When the second control unit 210 in the second control loop 203 is turned on, the breaking unit 206 in the third control loop 204 is turned on, and the tripper breaking control unit 212 is turned on. After the tripper disconnection control unit 212 is turned on, the tripper controlled by the tripper disconnection control unit 212 acts, and the heating control unit 207 connected to the tripper is forcibly disconnected by the tripper, interrupting the heating process of the heating unit 205 .

In the above technical solution, according to the heating temperature generated by the heating unit obtained by the mechanical temperature control unit, the control unit controls the heating control unit to disconnect to stop the heating state of the heating unit. If the heating unit does not change the state, the first control loop passes through the intermediate relay. The conduction state of the coil controls the conduction state of the second control unit in the second control loop. After the second control loop is turned on, the circuit breaker unit of the third control loop is turned on, and the release circuit breaker control unit executes the heating control unit. In the circuit breaking operation, at the same time, the third control loop maintains the conduction state of the circuit breaking unit to ensure the effectiveness of the circuit breaking operation, and the safety of the heating circuit is improved by the double circuit breaking operation.

FIG. 4 is a schematic structural diagram of an anti-dry burning protection circuit provided by another embodiment of the application. As shown in FIG. 4 , a heating circuit 305 of the anti-dry burning protection circuit includes a heating control unit 303 and a heating unit 304, wherein the heating control unit 303 includes a circuit breaker 301 and a heating contact 302, a heating unit 304 includes a heating tube, a three-phase AC power supply, a circuit breaker 301, a heating contact 302, a heating unit 304 and a ground wire connected to form a heating circuit 305, that is, a three-phase AC power supply It is connected to the first end of the circuit breaker 301, the second end of the circuit breaker 301 is connected to the first end of the heating contact 302, the second end of the heating contact 302 is connected to the first end of the heating unit 304, and the The second terminal is grounded. Wherein, the heating contact 302 is connected with the control unit 309, and the control unit 309 controls the on state and the off state of the heating contact 302. In one embodiment, the control unit 309 is a programmable control device (Programmable Logic Controller, referred to as: PLC).

The first control loop 308 includes a mechanical temperature control unit and an intermediate relay coil 306, wherein the mechanical temperature control unit includes a mechanical temperature control switch 307, and the mechanical temperature control switch 307, the intermediate relay coil 306 and the first DC power supply are connected to form the first DC power supply. Control loop 308 . The mechanical temperature control switch 307 is a normally open contact, that is, when the temperature of the heating unit 304 is not greater than the preset temperature threshold, the mechanical temperature control switch 307 is in an off state, and when the temperature of the heating unit 307 is greater than the preset temperature threshold, the The mechanical temperature switch 307 is in an on state. More specifically, the positive pole of the first DC power supply is connected to the first end of the intermediate relay coil 306 , the second end of the intermediate relay coil 306 is connected to the first end of the mechanical temperature control switch 307 , and the second end of the mechanical temperature control switch 307 The terminal is connected to the negative pole of the first DC power supply. In one embodiment, the positive pole of the first DC power supply is 24V, and the negative pole of the first DC power supply is -24V.

The second control loop includes a heating control unit 303 and a second control unit, the second control unit includes an intermediate relay contact 310 and a tripper coil 311, a three-phase AC power supply, a heating control unit 303, an intermediate relay contact 310, a trip The second control loop is formed after the coil 311 is connected to the ground wire. More specifically, the three-phase AC power supply includes L1, L2, and L3 three-phase power supplies, the heating control unit 303 includes a circuit breaker 301 and a heating contact 302, and the circuit breaker 301 includes three sub-breakers, which are the first sub-breaker, In the second sub-breaker and the third sub-breaker, the heating contact 302 includes three sub-heating contacts, which are respectively the first sub-heating contact, the second sub-heating contact and the third sub-heating contact. The first end of the AC power supply of each phase is respectively connected with the first end of a sub-breaker, and the second end of the sub-breaker is connected with the first end of a sub-heating contact. More specifically, the L1 AC power supply is connected to the first sub-breaker, and the first sub-breaker is connected to the first sub-heating contact; the L2 AC power supply is connected to the second sub-breaker, and the second sub-breaker is connected to the second sub-heating contact. Contact connection; L3 AC power supply is connected with the third sub-breaker, and the third sub-breaker is connected with the third sub-heating contact. The second end of any sub-heating contact among the heating contacts can be connected to the first end of the intermediate relay contact 310, that is, the second end of the first sub-breaker or the second sub-breaker or the third sub-breaker Connect to the first end of the intermediate relay contact 310 . The second end of the intermediate relay contact 310 is connected to the first end of the trip coil 311 , and the second end of the trip coil 311 is connected to the ground wire N to form a second control loop.

The third control loop 315 includes a second DC power supply, a tripper coil 311 and a tripper tripping control unit 314, wherein the tripper tripping control unit 314 includes a tripper contact 313 and a tripping device 312. The tripper The first end of the contact 313 is connected to the positive pole of the second DC power supply, the second end of the release contact 313 is connected to the first end of the release coil 311, and the second end of the release coil 311 is connected to the second end of the release coil 311. The negative pole of the DC power supply is connected to form the third control loop 314 . In one embodiment, the positive pole of the second DC power supply is 24V, and the negative pole of the second DC power supply is -24V.

When the horizontal line drying section is working, the PLC controls the heating contact 302 to close according to the obtained heating instruction. When the circuit breaker 301 is turned on, the heating circuit 305 is turned on, and the heating unit 304 starts heating. When the heating temperature of the heating unit 304 exceeds the preset temperature threshold, the mechanical temperature control switch 307 is closed, and the PLC 309 controls the state of the heating contact 302 according to the obtained conduction signal, that is, it switches from the on state to the off state. If the heating contact 302 is disconnected, the heating circuit 305 is disconnected, and the heating unit 304 is in an unheated state. If the heating contact 302 is not disconnected due to a hardware failure, the heating control unit 303 is still turned on, and the heating unit 304 is still performing the heating operation. In this case, the mechanical temperature control switch 307 is turned on, the first control loop is turned on, the intermediate relay coil 306 is turned on, the intermediate relay contact 310 in the second control loop is closed, the second control loop is turned on, and the release The coil 311 is turned on, the contact 313 of the release is closed, and the third control circuit 315 is turned on, and the conduction of the circuit is used to maintain the closed state of the contact 313 of the release. When the tripper contact 313 is closed, the tripping device 312 performs the tripping action, and the tripping device 312 is connected to the circuit breaker 301. When the tripping device 312 performs the tripping action, the circuit breaker 301 is disconnected, and the heating control unit 303 When disconnected, the heating unit 304 stops heating, the second control circuit is disconnected, and at the same time, the third control circuit 315 remains on, so as to maintain the tripping operation of the tripping device 312 and ensure the effectiveness of the circuit breaker disconnection. In addition, the PLC 309 also performs an alarm operation according to the closed state of the mechanical temperature control switch 307 to remind the staff to monitor the conduction state of the heating control unit 303 and the heating state of the heating unit 304 .

In the above technical solution, the PLC controls the disconnection of the heating contact according to the heating temperature of the heating unit to stop the heating process of the heating unit. If the disconnection of the heating contact is not realized, the second control loop is controlled by the conducting intermediate relay coil. Conduction, after the release coil in the second control loop is turned on, the closure of the release contact ensures the conduction of the third control loop, thereby ensuring the tripping operation of the circuit breaker to achieve double breaking operation, to prevent the safety hazard caused by the continuous heating of the heating unit, and to improve the safety of the heating circuit.

Other embodiments of the present application will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses or adaptations of this application that follow the general principles of this application and include common knowledge or conventional techniques in the technical field not disclosed in this application . The specification and examples are to be regarded as exemplary only, with the true scope and spirit of the application being indicated by the following claims.

It is to be understood that the present application is not limited to the precise structures described above and illustrated in the accompanying drawings and that various modifications and changes may be made without departing from the scope thereof. The scope of the application is limited only by the appended claims.

Claims (11)

1. An anti-dry-burning protection circuit, characterized in that the circuit comprises a heating loop, a first control loop, a second control loop and a third control loop; The heating circuit includes a heating unit for heating; the third control loop includes a circuit breaker unit for interrupting the heating state of the heating unit when it is in an on state; the third control circuit includes Three control loops are used to maintain the conduction state of the circuit breaker unit, so that the heating unit is in an unheated state; The first control loop is used to obtain the heating temperature of the heating unit, and when the heating temperature meets the preset dry-burning protection condition, the second control loop is controlled to be turned on; the second control loop is used to control the circuit breaker to be in On state. 2 . The circuit according to claim 1 , wherein the heating circuit further comprises a heating control unit, the heating control unit is used to control the heating state of the heating unit, and the heating control unit is connected to the heating unit. 3 . Then a heating circuit is formed. 3. The circuit according to claim 2, wherein the heating control unit comprises a heating contact and a circuit breaker, the first end of the circuit breaker is connected to the AC power source, and the second end of the circuit breaker is connected to the AC power source. The first end of the heating contact is connected, the second end of the heating contact is connected with the first end of the heating unit, and the second end of the heating unit is grounded. 4. The circuit according to claim 1, wherein the first control loop comprises a mechanical temperature control unit and an intermediate relay coil, and the mechanical temperature control unit is connected to the intermediate relay coil; The mechanical temperature control unit is used for acquiring the heating temperature of the heating unit, and changing the conduction state of the mechanical temperature control unit according to the heating state of the heating unit. 5. The circuit according to claim 4, wherein the mechanical temperature control unit comprises a mechanical temperature control switch, the first end of the intermediate relay coil is connected to the positive pole of the first DC power supply, and the intermediate relay The second end of the coil is connected to the first end of the mechanical temperature control switch, and the second end of the mechanical temperature control switch is connected to the negative electrode of the first DC power supply. 6. The circuit according to any one of claims 1 to 5, wherein the circuit further comprises a control unit; Wherein, the control unit is connected to the heating contact, and the control unit is used to control the heating contact to be in a conducting state; The control unit is also connected with a mechanical temperature control switch, and the control unit is used to generate a heating contact control instruction when the mechanical temperature control switch is in a conducting state, and the heating contact control instruction is used to control the first The control module keeps the heating contacts in a conductive state. 7. The circuit according to claim 2 or 3, wherein the second control loop comprises a second control unit, and the heating control unit and the second control unit in the heating loop are connected to form a second control loop . 8 . The circuit according to claim 7 , wherein the second control unit comprises an intermediate relay contact and a tripper coil, and the first end of the intermediate relay contact is connected to the first end of the heating contact. 9 . The two ends are connected, the second end of the intermediate relay contact is connected with the first end of the trip coil, and the second end of the trip coil is grounded. 9. The circuit according to claim 8, wherein when the heating temperature satisfies a preset dry-burning protection condition, controlling the second control loop to conduct, specifically comprising: When the heating temperature is greater than the preset temperature threshold of the mechanical temperature control unit, controlling the mechanical temperature control unit to be turned on and the first control loop to be turned on; According to the conduction state of the intermediate relay coil in the first control loop, the contact of the intermediate relay in the second control loop is controlled to be closed. 10 . The circuit according to claim 8 , wherein the third control loop comprises a tripper disconnection control unit, and the tripper coil is connected to the tripper disconnection control unit to form a third control circuit. 11 . loop. 11. The circuit according to claim 10, wherein the tripper circuit breaker control unit comprises a tripper contact, and the tripper contact is used to control the tripper to perform a tripping operation; Wherein, the first end of the release contact is connected to the positive pole of the second DC power supply, the second end of the release contact is connected to the first end of the release coil, and the release The second end of the generator coil is connected to the negative pole of the second DC power supply.

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