A protection circuit

Abstract

The application discloses a protection circuit for protecting an electric heating element, which comprises an air movement switch, which is closed when the ambient wind speed is greater than a set wind speed; and a processor, which is configured to control at least one control module to adjust the operating state of the electric heating element according to the relationship between the ambient temperature around the electric heating element and a target temperature when the air movement switch is closed. The protection circuit can avoid over-temperature of the electric heating element and improve the operating safety.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of electric heating temperature control, in particular to a protection circuit. BACKGROUND

[0002] At present, the temperature control field has relatively high requirements for temperature control precision. In order to achieve high-precision temperature control, the refrigeration module of the temperature control equipment is prone to overcooling during operation. Therefore, an electric heating element is often configured inside the temperature control equipment to compensate for the temperature fluctuation caused by overcooling, so that the temperature control precision meets the predetermined requirements. In order to avoid overtemperature of the electric heating element, corresponding protection measures need to be taken for the electric heating element to avoid safety accidents caused by burning of the electric heating pipe. Therefore, how to control the safe operation of the electric heating element is a technical problem to be solved by those skilled in the art. SUMMARY

[0003] The purpose of the present application is to provide a protection circuit for protecting an electric heating element, which can avoid overtemperature of the electric heating element and improve operation safety.

[0004] To achieve the above purpose, the present application provides a protection circuit, comprising:

[0005] an air movement switch, which is closed when the ambient wind speed is greater than a set wind speed;

[0006] a processor, configured to control at least one control module to adjust the operating state of the electric heating element according to the relationship between the ambient temperature around the electric heating element and the target temperature when the air movement switch is closed.

[0007] Optionally, the protection circuit further comprises a temperature detection module for detecting the ambient temperature around the electric heating element, wherein the temperature detection module is connected to the processor.

[0008] Optionally, the control module comprises a control output circuit, wherein the input end of the control output circuit is connected to the processor, the output end of the control output circuit is configured to be connected to the electric heating element, and the output end of the control output circuit is powered off when the ambient temperature reaches the target temperature.

[0009] Optionally, the control module comprises a voltage regulating module, wherein the voltage regulating module is connected to the output end of the control output circuit and configured to be connected to the electric heating element, and the processor controls the voltage regulating module to reduce the working voltage of the electric heating element through the control output circuit when the difference between the ambient temperature and the target temperature is less than a set threshold.

[0010] Optionally, the protection circuit comprises a contactor coil and a contactor normally open contact, wherein the contactor coil is connected to the output end of the control output circuit, and the contactor normally open contact is configured to be connected to the electric heating element.

[0011] Optionally, the wind switch is opened when the ambient wind speed is less than a set wind speed, and the electric heating element is powered off when the wind switch is opened.

[0012] Optionally, a fuse is further included for being connected in series with the electric heating element, and the fuse has a fuse temperature greater than the target temperature.

[0013] The wind switch is connected in series with a relay coil and a temperature limiter, and a first normally open contact of the relay is connected in series with the contactor coil, and the relay coil attracts the first normally open contact of the relay when the relay coil is powered on.

[0014] Optionally, a second normally open contact of the relay and a feedback detection circuit are further included, one end of the feedback detection circuit is connected with the second normally open contact, and the other end of the feedback detection circuit is connected with the processor, and the relay coil attracts the second normally open contact of the relay when the relay coil is powered on.

[0015] Optionally, a wireless mobile terminal is further included and connected with the processor.

[0016] Optionally, the processor is connected with / has a fault output module.

[0017] When the ambient temperature is less than the target temperature, the fault output module outputs a fuse fault when the processor receives a signal from the feedback detection circuit confirming that the second normally open contact of the relay is closed and the electric heating element stops working.

[0018] When the ambient temperature is less than the target temperature, the fault detection module outputs a temperature limiter fault when the processor receives a signal from the feedback detection circuit confirming that the second normally open contact of the relay is opened and the wind switch is closed.

[0019] When the ambient temperature is greater than the opening temperature of the temperature limiter, the fault output module outputs a temperature limiter fault when the processor receives a signal from the feedback detection circuit confirming that the second normally open contact of the relay is closed.

[0020] Compared with the prior art, the protection circuit provided by the embodiments of the present application has at least the following effects:

[0021] The processor realizes the control of the running state of the electric heating element according to the relationship between the target temperature and the ambient temperature through at least one control module, and the pre-logic of the ambient wind speed is introduced. When the ambient wind speed is greater than the set wind speed, that is, when the refrigeration equipment is running, the wind-driven switch is closed, the control logic of the target temperature of the processor and the control module is effective, the refrigeration module of the temperature control equipment is confirmed to be running through the wind-driven switch, so that the electric heating element is started when the refrigeration module of the temperature control equipment is running, the safety of the electric heating element is improved, and the wind-driven switch cooperates with the processor and at least one control module to control the on-off of the electric heating element or adjust the voltage of the electric heating element, so as to avoid over-temperature of the electric heating element and improve the safety of the electric heating element. BRIEF DESCRIPTION OF DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor on the basis of the provided drawings.

[0023] Figure 1 The schematic diagram of the protection circuit provided by the embodiments of the present application.

[0024] Among them:

[0025] 1-wind-driven switch, 2-temperature limiter, 3-relay, 4-contactor, 5-voltage regulating module, 6-fuse, 7-electric heating element, 8-control output circuit, 9-processor, 10-wireless mobile terminal, 11-temperature detection module, 12-feedback detection circuit. DETAILED DESCRIPTION

[0026] The technical solutions in the embodiments of the present application will be described clearly and completely in the following with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0027] In order to make those skilled in the art better understand the present application, the present application will be further described in detail below with reference to the drawings and specific embodiments.

[0028] Please refer to Figure 1 , Figure 1 The schematic diagram of the protection circuit provided by the embodiments of the present application, Figure 1In the figure, K1 represents the relay coil of the relay 3, K2 represents the first normally open contact of the relay, and K3 represents the second normally open contact of the relay 3; KM1 represents the coil of the contactor 4, and KM2 represents the normally open contact of the contactor.

[0029] The embodiment of the present application provides a protection circuit for realizing electric heating temperature control of a temperature control device and protecting an electric heating element 7, and improving the safety and temperature control precision of the electric heating element 7. The protection circuit comprises the electric heating element 7, an air switch 1, a processor 9 and at least one control module. The air switch 1 is closed when the ambient wind speed is greater than the set wind speed, and is opened when the ambient wind speed is less than the set wind speed. When the air switch 1 is opened, the electric heating element 7 is also powered off synchronously, that is, the air switch 1 can directly or indirectly control the on-off of the electric heating element 7. The at least one control module can realize comparison between the ambient temperature and the target temperature of the electric heating element 7 under the control of the processor 9, adjust the running state (on-off and running voltage adjustment, etc.) of the electric heating element 7, and realize safe running of the electric heating element 7.

[0030] The protection circuit further comprises a temperature detection module 11 for detecting the ambient temperature around the electric heating element. The at least one control module comprises a control output circuit 8. The electric heating circuit is connected in series with the electric heating element 7 for heating to adjust the ambient temperature. The temperature detection module 11 is connected with the processor 9. The input end or control end of the control output circuit 8 is connected with the processor 9 for receiving the control signal of the processor 9. The output end of the control output circuit 8 is connected with the electric heating circuit for supplying power to the electric heating circuit under the control of the processor 9. The processor 9 can obtain the temperature of the ambient environment around the electric heating element 7 through the temperature detection module 11, or can obtain the temperature value through manual detection and wireless mobile terminal 10.

[0031] The air switch 1 can be connected with the processor 9, and the processor 9 can control the on-off of the electric heating element 7 according to the state information of the air switch 1 or the state information of the loop where the air switch 1 is located through the control module. Alternatively, the air switch 1 can be connected in series with a relay assembly to realize power-off of the electric heating element 7 when the air switch 1 is opened. When the air switch 1 is closed, the control logic of the processor 9 and the at least one control module based on the ambient temperature and the target temperature, that is, the protection logic of the electric heating element 7 exceeding the target temperature is effective.

[0032] When the wind switch 1 is in the closed state, in order to improve the temperature regulation accuracy and avoid the electric heating element 7 from working continuously beyond the target temperature, the temperature detection module 11 detects the ambient temperature and feeds back the ambient temperature to the processor 9, the processor 9 compares the ambient temperature with the set target temperature, so as to command the control output circuit 8 to stop supplying power to the electric heating circuit when the target temperature is reached, thereby improving the temperature regulation accuracy. In addition, the target temperature stored in the processor 9 can be changed remotely through the wireless mobile terminal 10, thereby improving the flexibility of the temperature regulation of the protection circuit.

[0033] In a preferred embodiment provided by the application, a voltage regulating module 5 is further arranged between the control output circuit 8 and the electric heating circuit, when the difference between the ambient temperature detected by the temperature detection module 11 and the target temperature is less than the set threshold, the processor 9 is used to control the voltage regulating module 5 and the control output circuit 8 to reduce the working voltage of the electric heating circuit, so as to realize stepless adjustment of the power of the electric heating element 7, reduce the heating power and the temperature rising speed, and improve the accuracy of temperature regulation. The control output circuit 8 can be controlled by the processor 9 to realize the presence or absence of output current, or a voltage regulating component can be arranged in the control output circuit 8 according to the control requirement, which will not be described here.

[0034] For example, the target temperature is set to 60℃, and the temperature difference threshold is set to 5℃, that is, when the temperature detection module 11 detects that the ambient temperature reaches 55℃, the processor 9 controls the voltage regulating module 5 and the control output circuit 8 to reduce the working voltage of the electric heating element 7.

[0035] Further, the electric heating circuit is provided with a fuse 6, and the fuse 6 is connected in series with the electric heating element 7. The melting temperature of the fuse 6 is greater than the target temperature but less than the damage temperature of the electric heating element 7. By arranging the fuse 6, it is avoided that the electric heating circuit cannot be disconnected in time when any one of the temperature detection module 11, the processor 9 or the control output circuit 8 fails, thereby forming multiple protections.

[0036] On the basis of the above-mentioned embodiments, the control module of the protection circuit provided by the application further comprises a protection circuit, which is connected to the output end of the control output circuit 8 and is powered by the control output circuit 8. The protection circuit is connected in series with the contactor coil of the contactor 4, and the electric heating circuit is connected in series with the normally open contact of the contactor 4. When the protection circuit is powered, the contactor coil is powered to generate magnetism, and the normally open contact of the contactor is attracted, so that the electric heating circuit is closed. That is, the control output circuit 8 can not only stop heating by stopping supplying power to the electric heating circuit, but also stop heating by stopping supplying power to the protection circuit.

[0037] As preferred, the protection circuit further comprises a temperature limiter 2 and a coil of a relay 3 connected in series to the AC power supply, and a relay first normally open contact of the relay 3 connected in series to the protection circuit and cooperating with the relay coil of the relay 3. When the ambient temperature exceeds the disconnection temperature of the temperature limiter 2, the temperature limiter 2 is disconnected to cause the relay coil to lose power, and the relay first normally open contact is disconnected to cause the protection circuit to be disconnected, and in turn the contactor coil to lose power, and the contactor normally open contact to be disconnected, and the electric heating circuit to lose power and stop heating. That is, another protection of the protection circuit is realized by the temperature limiter 2. The target temperature can be flexibly set within a range lower than the disconnection temperature of the temperature limiter 2, and the disconnection temperature of the temperature limiter 2 is lower than the melting temperature of the fuse 6. The multiple protections are realized by the temperature limiter 2, the protection logic of the temperature detection module 11 and the processor 9, and the melting temperature of the fuse 6.

[0038] As optional, the wind switch 1 is connected in series to the circuit of the temperature limiter 2, and the ambient wind speed is detected by the wind switch 1 to determine whether the refrigeration module of the temperature control device is in operation to determine the operation state of the temperature control device. When the ambient wind speed is greater than a set threshold value, i.e., the closing threshold value of the wind switch 1, it indicates that the refrigeration module is in operation, the wind switch 1 is closed, and the electric heating circuit indirectly protected by the temperature limiter 2 can be normally started and stopped. The wind speed threshold value can be flexibly set according to requirements, and then a suitable wind switch 1 can be matched according to the wind speed threshold value, which will not be described herein.

[0039] In an embodiment, the processor 9 is connected to a feedback detection circuit 12 provided with a detection circuit connected in series to a relay second normally open contact of the relay 3. When the temperature limiter 2 is closed, the relay coil is powered and at the same time attracts the relay first normally open contact and the relay second normally open contact. The feedback detection circuit 12 obtains the state information of the detection circuit and feeds back to the processor 9. The processor 9 can compare the current temperature with the disconnection temperature of the temperature limiter 2, and determine whether the temperature limiter 2 fails according to the state information of the detection circuit.

[0040] In a normal working state, when the temperature control device needs to be over-cooled or the ambient temperature detected by the temperature detection module 11 is lower than the set temperature and needs to be precisely controlled by electric heating, the temperature limiter 2 remains closed, the relay coil is powered, and the relay first normally open contact and the relay second normally open contact are attracted. The feedback detection circuit 12 receives a signal that the detection circuit is turned on and sends it to the processor 9. The processor 9 issues a control instruction to the control output circuit 8 according to the detection result of the temperature detection module 11 and the signal. The control output circuit 8 supplies power to the protection circuit and the electric heating circuit. When the protection circuit is turned on, the contactor coil is powered and attracts the contactor normally open contact, the electric heating circuit is closed, and the electric heating element 7 is powered to control the temperature.

[0041] It should be noted that the temperature limiter 2 is in a normally closed state below the trip temperature, and will automatically open when the temperature exceeds the trip temperature of the temperature limiter 2, and will close again when the temperature returns to below the trip temperature of the temperature limiter 2. If the temperature detection module 11 detects that the ambient temperature is below the trip temperature of the temperature limiter 2, and the feedback detection circuit 12 does not receive the closing signal of the detection loop, it indicates that the temperature limiter 2 is faulty; similarly, if the temperature detection module 11 detects that the ambient temperature is higher than the trip temperature of the temperature limiter 2, and the feedback detection circuit 12 does not receive the opening signal of the detection loop, it also indicates that the temperature limiter 2 is faulty.

[0042] When the temperature limiter 2 is normally closed, and the ambient temperature detected by the temperature detection module 11 meets the power supply requirements of the control output circuit 8 to the protection circuit and the electric heating circuit, if the electric heating element 7 is still not powered on, it indicates that the fuse 6 has failed, causing the electric heating circuit to be open. The protection circuit provided in the embodiment of the application includes a fault output module connected to the processor 9, which is used to output the fault of the temperature limiter 2 or the fault of the fuse 6 according to the above logic. The fault output module can specifically use a display module connected to the processor 9.

[0043] The temperature detection module 11 can use temperature sensors, temperature measuring thermocouples, etc., and the temperature measurement results are transmitted to the processor 9. Through the feedback detection circuit 12 and its detection loop, the temperature detection module 11, and the setting of the relay 3 and the contactor 4, not only can the electric heating circuit be protected and the temperature be adjusted accurately, but also can the fault state of the temperature limiter 2 and the fuse 6 in the electric heating circuit be detected and confirmed during operation, ensuring normal operation.

[0044] In addition, the processor 9 is connected to the cloud platform control and the wireless mobile terminal 10, which can conveniently monitor the working state of the protection circuit through the wireless mobile terminal 10 such as a mobile phone or a tablet, and can also conveniently modify the target temperature.

[0045] The application uses the temperature detection module 11 to directly protect and control the temperature, which is more direct, and can adaptively adjust the heating power of the electric heating element 7 for different temperatures, shorten the time to reach the preset temperature, and improve the temperature control accuracy. The temperature limiter 2, the air-operated switch 1, the temperature detection module 11, the control output circuit 8, and the fuse 6 form multiple protections. By adding the wireless mobile terminal 10, the wireless mobile terminal 10 is connected to the processor 9, which not only can monitor the current working state of the electric heating circuit, but also can modify the protection temperature of the electric heating element 7 and the trip temperature of the temperature limiter 2, making the protection circuit more flexible and friendly in use and interaction.

[0046] It should be noted that the relative terms, such as first and second, are used herein only to distinguish one entity from another, and do not necessarily require or imply any such actual relationship or order between such entities.

[0047] The above has introduced the protection circuit provided by the present application in detail. The principle and implementation mode of the present application are described by applying specific examples in the present article, and the above example description is only for helping to understand the method of the present application and its core idea. It should be pointed out that, for the ordinary skilled in the art, some improvements and modifications can be made to the present application without departing from the principle of the present application, and these improvements and modifications also fall within the protection scope of the present application claims.

Claims

1. A protection circuit for protecting an electric heating element, characterized in that, The application relates to an electric heating device, which comprises: a wind switch, which is closed when the ambient wind speed is greater than a set wind speed; a processor, which is used for controlling at least one control module to adjust the operating state of an electric heating element according to the relationship between the ambient temperature around the electric heating element and a target temperature when the wind switch is closed; the control module comprises a control output circuit, the output end of the control output circuit is used for being connected with the electric heating element, and the output end of the control output circuit is powered off when the ambient temperature reaches the target temperature; the electric heating element is further connected with a contactor coil and a contactor normally-open contact, the contactor coil is connected with the output end of the control output circuit, and the contactor normally-open contact is used for being connected with the electric heating element; the wind switch is connected with a relay coil in series; the relay coil is further connected with a relay first normally-open contact in series; the input end of the control output circuit is connected with the processor; the control module comprises a voltage regulating module, the voltage regulating module is connected with the output end of the control output circuit and is used for being connected with the electric heating element, and the processor controls the voltage regulating module to reduce the working voltage of the electric heating element through the control output circuit when the difference between the ambient temperature and the target temperature is less than a set threshold value; a fuse is further connected with the electric heating element in series, the fusing temperature of the fuse is greater than the target temperature, and the wind switch is further connected with a temperature limiter in series; a fault output module is further included; when the ambient temperature is less than the target temperature, the processor outputs the fuse fault through the fault output module when receiving the signal that the feedback detection circuit confirms that the relay second normally-open contact is closed and the electric heating element stops working; when the ambient temperature is less than the target temperature, the processor outputs the temperature limiter fault through the fault output module when the wind switch is closed and receiving the signal that the feedback detection circuit confirms that the relay second normally-open contact is opened; when the ambient temperature is greater than the opening temperature of the temperature limiter, the processor outputs the temperature limiter fault through the fault output module when receiving the signal that the feedback detection circuit confirms that the relay second normally-open contact is closed; a wireless mobile terminal is further connected with the processor, and the wireless mobile terminal remotely changes the target temperature stored in the processor.

2. The protection circuit of claim 1, wherein a temperature detection module is further included for detecting the ambient temperature around the electric heating element, and the temperature detection module is connected with the processor.

3. The protection circuit of claim 1, wherein the wind switch is opened when the ambient wind speed is less than a set wind speed, and the electric heating element is powered off when the wind switch is opened.

4. The protection circuit of claim 1, wherein, a relay second normally-open contact and a feedback detection circuit are further included, one end of the feedback detection circuit is connected with the second normally-open contact, the other end of the feedback detection circuit is connected with the processor, and the relay second normally-open contact is attracted by the relay coil when the relay coil is powered on.

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