Exhaust fan control circuit and microwave oven

Abstract

The utility model provides an exhaust fan control circuit and a microwave oven. The exhaust fan control circuit comprises an exhaust fan module, a thermal cutter, an adapter, a relay control module and a single-chip microcomputer controller. One end of the exhaust fan module and one end of the thermal cutter are both connected with the power interface, the other end of the exhaust fan module and the other end of the thermal cutter are both connected with the single-chip microcomputer controller through the adapter and the relay control module in sequence, and the single-chip microcomputer controller is connected with the key module. According to the exhaust fan control circuit and the microwave oven, the structural arrangement of the exhaust fan control circuit can be optimized, the flexibility and the stability of an exhaust fan control mode are improved, the reliability of the exhaust fan control circuit is enhanced, the problem that a motor in the exhaust fan is seriously heated after working for a long time is solved, and the service life of the exhaust fan is prolonged.

Description

Technical Field

[0001] The utility model relates to the field of microwave ovens, and more specifically, to an exhaust fan control circuit and a microwave oven. Background Art

[0002] Ordinary microwave ovens can heat, thaw, and cook food through microwaves. However, due to their relatively single functions, they cannot remove the oil fumes and odors generated during the food heating process. Moreover, ordinary microwave ovens are usually placed as independent kitchen appliances in kitchen cabinets or on countertops, thus occupying a large amount of space in the kitchen.

[0003] In the existing OTR microwave ovens, by integrating an exhaust fan inside the microwave oven, the oil fumes and odors generated during food heating can be avoided. In addition, OTR microwave ovens are generally installed above the stove. On the basis of facilitating ventilation in the kitchen and inside the microwave oven, it is also beneficial to save kitchen space.

[0004] However, since the exhaust fan in the existing OTR microwave ovens has a self-start function in addition to manual control, that is, when the temperature at the bottom of the microwave oven is too high, the thermal cut-off connected to one end of the exhaust fan will close. At this time, one set of windings of the exhaust fan will be energized and self-start for heat dissipation. However, since the exhaust fan generally has 4 gears, with one set of coils for each gear, when the exhaust fan is manually started by pressing a button at this time, when the started gear is inconsistent with the selected gear, it is easy to cause two sets of coils to conduct electricity simultaneously, and the motor generates too much heat, which easily accelerates the aging of the exhaust fan. Therefore, it is of great significance to study how to improve the control methods of the self-start and manual control of the exhaust fan and improve the safety of the exhaust fan operation.

[0005] In Patent CN109028187B, a method for judging and controlling the direction of the exhaust fan of an OTR product is proposed, including the relevant gear settings of the exhaust fan of the OTR product, as well as the method for judging and controlling the direction of the exhaust fan. However, through the settings of the exhaust fan, the influence on the operation between the self-start and manual control cannot be solved, and the problem of excessive motor heating and accelerated aging speed of the exhaust fan still easily occurs. Summary of the Utility Model

[0006] In view of this, the utility model aims to provide an exhaust fan control circuit and a microwave oven to solve the problem in the existing technology that when the self-start control circuit and the manual control circuit of the exhaust fan work simultaneously but the selected gears are inconsistent, it is easy to cause two sets of coils in the microwave oven to conduct electricity simultaneously, the motor generates too much heat, and thus accelerates the aging of the exhaust fan. By doing so, the structural setting of the exhaust fan control circuit is optimized, the flexibility and stability of the exhaust fan control method are improved, the reliability of the exhaust fan control circuit is enhanced, the problem of serious heat generation of the motor in the exhaust fan during long-term operation is prevented, and the service life of the exhaust fan is extended.

[0007] To achieve the above object, the technical solution of the present utility model is realized as follows:

[0008] A kind of exhaust fan control circuit and a microwave oven related to the present utility model, the exhaust fan control circuit includes an exhaust fan module, a thermal cut-off, an adapter, a relay control module and a single-chip microcomputer controller; one end of the exhaust fan module and the thermal cut-off are both connected to the power interface, and the other ends of the exhaust fan module and the thermal cut-off are both connected to the single-chip microcomputer controller through the adapter and the relay control module in sequence, and the single-chip microcomputer controller is connected to the key module.

[0009] Further, the single-chip microcomputer controller is communicatively connected to the relay control module in a self-startable manner, and / or the key module is communicatively connected to the relay control module in a manually adjustable manner through the single-chip microcomputer controller.

[0010] Further, the power interface includes a live wire L interface and a neutral wire N interface, the live wire L interface and the neutral wire N interface are both integrally arranged on the power interface, and the live wire L interface and the neutral wire N interface are both connected to the alternating current AC power supply.

[0011] Further, the exhaust fan module includes an exhaust fan and a starting capacitor C25, and the exhaust fan is respectively connected to the starting capacitor C25, the power interface and the adapter.

[0012] Further, the exhaust fan includes a capacitor pin, a gear pin, and an off-gear pin N, the capacitor pin, the gear pin, and the off-gear pin N are all arranged on the exhaust fan, the exhaust fan is connected to both ends of the starting capacitor C25 through the capacitor pin, the exhaust fan is connected to the adapter through the gear pin, and the exhaust fan is connected to the neutral wire N interface through the off-gear pin N.

[0013] Further, n gear pins are provided, and n is a positive integer.

[0014] Further, n = 4, the gear pins include a highest gear pin T, a high gear pin H, a medium gear pin M, and a low gear pin L, and the exhaust fan is respectively connected to pins 5, 7, 9, and 11 of the adapter through the highest gear pin T, the high gear pin H, the medium gear pin M, and the low gear pin L.

[0015] Further, pin 1 of the thermal cut-off is respectively connected to the live wire L interface and pin 1 of the adapter, and pin 2 of the thermal cut-off is connected to pin 3 of the adapter.

[0016] Further, the relay control module includes a relay and a driver chip IC1; the relay and the driver chip IC1 are both integrally arranged on the relay control module; one end of the relay is connected to the single-chip microcomputer controller through the driver chip IC1, and the other end of the relay is connected to the adapter.

[0017] A microwave oven, which includes the described exhaust fan control circuit, and the exhaust fan control circuit is arranged inside the microwave oven.

[0018] Compared with the prior art, the exhaust fan control circuit and the microwave oven of the present utility model have the following beneficial effects:

[0019] Through the setting of the control circuit, the structural setting of the exhaust fan control circuit can be optimized, the flexibility and stability of the exhaust fan control method can be improved, the reliability of the exhaust fan control circuit can be enhanced, the problem that the motor in the exhaust fan works for a long time and generates serious heat can be prevented, the service life of the exhaust fan can be extended, and the cost of optimizing the exhaust fan control circuit in the microwave oven can be reduced. Description of the Drawings

[0020] The drawings forming a part of the present utility model are used to provide a further understanding of the present utility model. The schematic embodiments and descriptions thereof of the present utility model are used to explain the present utility model and do not constitute an improper limitation to the present utility model. In the drawings:

[0021] Figure 1 It is a schematic diagram of the exhaust fan control circuit.

[0022] Description of the reference numerals in the drawings: 1. Power supply interface; 2. Exhaust fan module; 3. Thermal cut-off; 4. Adapter; 5. Relay control module; 51. Relay one; 52. Relay two; 53. Relay three; 54. Relay four; 6. Single-chip microcomputer controller; 7. Button module. Detailed Embodiment

[0023] In the following, the inventive concepts of the present disclosure will be described using the terms that those skilled in the art would typically use to convey the substance of their work to other skilled artisans in the art. However, these inventive concepts may be embodied in many different forms and should not be considered limited to the embodiments described herein.

[0024] It should be noted that, without conflict, the embodiments in the present utility model and the features in the embodiments may be combined with each other.

[0025] The present utility model will be described in detail below with reference to the drawings and in conjunction with the embodiments.

[0026] This embodiment is for a microwave oven. The same as a conventional microwave oven, the overall structure is composed of a magnetron, a turntable, and a furnace door.

[0027] In order to solve the problem in the prior art that when the self-start control circuit and the manual control circuit of the exhaust fan work simultaneously, but the selected gears are inconsistent, it is easy to make the two groups of coils in the microwave oven conduct electricity at the same time, the motor generates too much heat, and then accelerates the aging of the exhaust fan; this embodiment proposes an exhaust fan control circuit and a microwave oven. The exhaust fan control circuit includes an exhaust fan module 2, a thermal cut-off 3, an adapter 4, a relay control module 5, and a single-chip microcomputer controller 6. One end of the exhaust fan module 2 and the thermal cut-off 3 are both connected to the power supply interface 1, and the other ends of the exhaust fan module 2 and the thermal cut-off 3 are sequentially connected to the single-chip microcomputer controller 6 through the adapter 4 and the relay control module 5. The single-chip microcomputer controller 6 is connected to the button module 7. Among them, the single-chip microcomputer controller 6 is communicatively connected to the relay control module 5 in a self-startable manner, and / or the button module 7 is communicatively connected to the relay control module 5 in a manually selectable control manner through the single-chip microcomputer controller 6. That is, the single-chip microcomputer controller 6 controls the relay control module 5 to operate in a self-startable manner, and / or the single-chip microcomputer controller 6 controls the relay control module 5 to operate by receiving a manual input signal from the button module 7. In this embodiment, the button module 7 is a button operation module for manually inputting a gear adjustment signal.

[0028] By setting each component in the control circuit, the structural setting of the exhaust fan control circuit can be optimized, the flexibility and stability of the exhaust fan control method can be improved, the reliability of the exhaust fan control circuit can be enhanced, the problem of serious heat generation of the motor in the exhaust fan during long-term operation can be prevented, the service life of the exhaust fan can be extended, and the cost of optimizing the exhaust fan control circuit in the microwave oven can be reduced. By setting the button module 7, a signal for selecting the exhaust fan gear can be manually input to the single-chip microcomputer controller 6.

[0029] The power supply interface 1 includes a live wire L interface and a neutral wire N interface. The live wire L interface and the neutral wire N interface are both integrally arranged on the power supply interface 1. The live wire L interface and the neutral wire N interface are both connected to the alternating current AC for facilitating the input of the alternating current AC.

[0030] The exhaust fan module 2 includes an exhaust fan and a starting capacitor C25. The exhaust fan is respectively connected to the starting capacitor C25, the power supply interface 1, and the adapter 4. The exhaust fan includes a capacitor pin, a gear pin, and a shut-off pin N. The capacitor pin, the gear pin, and the shut-off pin N are all arranged on the exhaust fan. The exhaust fan is connected to both ends of the starting capacitor C25 through the capacitor pin, the exhaust fan is connected to the adapter 4 through the gear pin, and the exhaust fan is connected to the neutral wire N interface through the shut-off pin N. n gear pins are provided, and n is a positive integer. Windings corresponding to the positions of the gear pins and the shut-off pin N are arranged. For realizing the regulation of the exhaust fan at different gear speeds through different winding configurations. It is also beneficial to improve the operation efficiency and stability of the exhaust fan through different winding settings.

[0031] Specifically, the capacitor pins include the first capacitor pin C1 and the second capacitor pin C2. The exhaust fan is connected to the positive electrode of the starting capacitor C25 through the first capacitor pin C1, and the exhaust fan is connected to the negative electrode of the starting capacitor C25 through the second capacitor pin C2. When n = 4, that is, 4 gear pins are set. The gear pins include the highest gear pin T, the high gear pin H, the medium gear pin M, and the low gear pin L. The exhaust fan is connected to pins 5, 7, 9, and 11 of the adapter 4 through the highest gear pin T, the high gear pin H, the medium gear pin M, and the low gear pin L respectively. In this embodiment, the exhaust fan is an AC exhaust fan.

[0032] Through the coordinated setting of the exhaust fan and the starting capacitor C25, it is beneficial to provide additional starting energy for the exhaust fan under the action of the starting capacitor C25, so as to enable the motor to overcome the static friction and the inertia of the rotor, and thus start smoothly. It is also beneficial to improve the operation efficiency and real-time performance of the exhaust fan control circuit.

[0033] Working principle:

[0034] When the temperature at the bottom of the microwave oven is too high and the exhaust fan starts automatically due to the conduction of the thermal cut-off 3, at this time, by manually selecting the exhaust fan gear, assuming the highest gear is selected, the highest gear winding of the exhaust fan is energized alone and runs at the highest gear speed. When the high gear is selected, the high gear winding of the exhaust fan is energized alone and runs at the high gear speed. When the medium gear is selected, the medium gear winding of the exhaust fan is energized alone and runs at the medium gear speed. When the low gear is selected, the low gear winding of the exhaust fan is energized alone and runs at the low gear speed. When the off position is selected, the self-start default gear needs to be maintained, so that through the setting of each gear, on the one hand, the heat dissipation can be continuously maintained through self-start and / or manual control, and on the other hand, the exhaust fan can be protected by the thermal cut-off 3 hardware.

[0035] Pin 1 of the thermal cut-off 3 is respectively connected to the live wire L interface and pin 1 of the adapter 4, and pin 2 of the thermal cut-off 3 is connected to pin 3 of the adapter 4. The thermal cut-off 3 is used to keep the normally open state when the temperature inside the microwave oven is normal. After the temperature inside the microwave oven reaches the self-start preset temperature, the thermal cut-off 3 keeps the closed state, so that the self-start circuit of the exhaust fan inside the microwave oven is automatically conducted, so as to improve the automatic heat dissipation ability inside the microwave oven and ensure the safe and reliable operation of the microwave oven.

[0036] The relay control module 5 includes a relay and a drive chip IC1. The relay and the drive chip IC1 are both integrally arranged on the relay control module 5. One end of the relay is connected to the single-chip microcomputer controller 6 through the drive chip IC1, and the other end of the relay is connected to the adapter 4. In this embodiment, the drive chip IC1 is an inverting controller.

[0037] Among them, at least four relays are provided. The relays include relay 51, relay 52, relay 53, and relay 54. One end of relay 51, relay 52, relay 53, and relay 54 is connected to the single-chip microcomputer controller 6 through the driving chip IC1. The other ends of relay 51, relay 52, and relay 54 are all connected to the adapter 4. Relay 53 is respectively connected to relay 51, relay 52, and relay 54. Relay 51, relay 52, relay 53, and relay 54 are all connected to the power supply VDD. In this embodiment, relay 51 is a single-pole single-throw relay, and relay 52, relay 53, and relay 54 are single-pole double-throw relays.

[0038] Through the setting of the relays and the driving chip IC1, it is beneficial to control different relays through one-to-many control components. On the one hand, it can simplify the setting of the control circuit structure. On the other hand, it can reduce the signal transmission delay time, improve the rapidity and real-time performance of the gear adjustment in the control circuit, and enhance the operation safety and reliability of the manual or automatic control of the exhaust fan. Furthermore, it is beneficial to extend the service life of the microwave oven and reduce the generation of peculiar smell or oil fume during the use of the microwave oven. And it can timely adjust the change of the temperature in the microwave oven in real time, improving the safety of using the microwave oven.

[0039] Preferably, at least one driving chip IC1 is provided, and different driving chips IC1 are set in one-to-one correspondence with different relays, that is, the control of the relays can adopt discrete component control. It is beneficial to control the on-off of the corresponding relays one by one through the discrete driving chips IC1, improving the flexibility of replacement between control circuits and the efficiency of circuit maintenance.

[0040] Specifically, a single-pole single-throw switch is provided between pin 2 and pin 1 of relay 51. Single-pole double-throw switches are provided between pins 1, 2, and 3 of relay 52, relay 53, and relay 54. Among them, pin 3 is connected to the common end of the single-pole double-throw switch, pin 2 is connected to the normally open end NO of the single-pole double-throw switch, and pin 1 is connected to the normally closed end NC of the single-pole double-throw switch. The pin 3 of relay 52, relay 53, and relay 54 is connected to its pin 1 or pin 2 in a movable manner.

[0041] By using the combination of single-pole single-throw switches and single-pole double-throw switches in different relays, it is possible to achieve the control of different gears of the exhaust fan by the driving chip IC1 through different relays. This is also beneficial to enhancing the flexibility of the control circuit, as well as enhancing the stability and safety of the control circuit. It is also conducive to improving the efficiency of different state switches within the relay control module 5. Through the combined use of single-pole single-throw switches and single-pole double-throw switches, it is also beneficial to reducing the cost of the control circuit. Under the condition of using as few relays as possible, the control of exhaust fans with multiple gears can be achieved, which is conducive to greatly simplifying the structure of the control circuit.

[0042] In addition, the pin 4 of relay 51, relay 52, relay 53, and relay 54 are respectively connected to the pins 13, 14, 15, and 16 of the driving chip IC1. The pin 3 of relay 51, the pins 5 of relay 52, relay 53, and relay 54 are evenly connected to the power supply VDD. The pin 2 of relay 51 is connected to the pin 1 of the adapter 4. The pin 1 of relay 51 is respectively connected to the pin 3 of the adapter 4 and the pin 3 of relay 53. The pin 1 of relay 53 is connected to the pin 3 of relay 54. The pins 1 and 2 of relay 54 are respectively connected to the pins 9 and 11 of the adapter 4. The pin 2 of relay 53 is connected to the pin 3 of relay 52. The pins 1 and 2 of relay 52 are respectively connected to the pins 5 and 7 of the adapter 4. The pins 8 and 9 of the driving chip IC1 are respectively connected to the ground and the power supply VDD. The pins 1, 2, 3, and 4 of the driving chip IC1 are respectively connected to the corresponding pins on the microcontroller 6. The pins 1, 2, 3, and 4 of the driving chip IC1 are respectively used to receive the command signals corresponding to relay 54, relay 53, relay 52, and relay 51.

[0043] Through the connection between the pins of relay 51, relay 52, relay 53, and relay 54, it is possible to effectively prevent interference between manual control and self-start, which is beneficial to improving the independence of operation between manual control and self-start, and enhancing the operational reliability of the control circuit.

[0044] The working process is as follows:

[0045] Suppose there is a five - speed exhaust fan, and the five speeds are the highest gear T, high gear H, medium gear M, low gear L, and off gear N in sequence. After the whole machine is powered on, the temperature at the bottom inside the microwave oven is monitored in real - time. When the temperature inside the microwave oven does not reach the closing temperature of the thermal cut - off 3, that is, the thermal cut - off 3 remains open - circuited, and the relay remains in an unoperated state; at this time, the exhaust fan is default off. If a low - gear signal is selected through the key module 7 and input to the single - chip microcomputer controller 6, the single - chip microcomputer controller 6 sends signals Relay4_CTL, Relay3_CTL, Relay1_CTL to output high, and Relay2_CTL to output low. Since the driving chip IC1 of the relay control module 5 is an inverting controller, that is, when the input is high, the output is low; when the input is low and there is a pull - up load, the output is high. Then at this time, the pins 16, 15, 13 of the driving chip IC1 output low - level, and the pin 14 of the driving chip IC1 remains high - level. The single - pole double - throw relays Relay3, Relay4 (i.e., relay three 53, relay four 54) and the single - pole single - throw relay Relay1 (i.e., relay one 51) of the relay control module 5 act because there is a pressure difference approximately equal to the voltage value of the power supply VDD across the coil ends. Then the pins 1 and 3 of the relays Relay3, Relay4 (i.e., relay three 53, relay four 54) are connected, the pins 2 and 3 are open - circuited, the pins 1 and 2 of the relay Relay1 (i.e., relay one 51) are connected, and the single - pole double - throw relay Relay2 (i.e., relay two 52) does not act because the pressure difference across the coil ends is approximately 0, that is, the pins 2 and 3 of the relay Relay2 (i.e., relay two 52) remain normally closed and the pins 1 and 3 remain normally open. At this time, the live - wire signal L output from the live - wire L interface of the power supply interface 1 passes through the pin 1 of the exhaust - fan socket interface CN1 in the adapter 4, then through the pins 1 and 2 of the relay Relay1 (i.e., relay one 51), then through the pins 1 and 3 of the relay Relay3 (i.e., relay three 53), further through the pins 1 and 3 of the relay Relay4 (i.e., relay four 54), further through the pin 11 of the socket CN1 in the adapter 4, and further into the LOW end of the exhaust - fan winding of the exhaust - fan module 2. At this time, since the neutral - wire end of the exhaust fan is always connected to the power - supply N wire, then after the LOW end of the exhaust - fan winding is selected by the live - wire L, a current is formed and the exhaust fan can operate at a low - speed. At this time, only the LOW end of the winding is selected by the live - wire L, which meets the application requirements. Similarly, when selecting the wind speed of other gears, the corresponding winding of the exhaust fan will also be selected separately, meeting the application requirements, and there will be no phenomenon that two windings are conducted simultaneously. Among them, when the thermal cut - off is not conducted, the control logic of the exhaust fan for manually selecting the wind speed is shown in Table 3 - 1 as follows:

[0046] Table 3 - 1 Control logic of the exhaust fan when the thermal cut - off 3 is not conducted

[0047]

[0048] After the whole machine is powered on, when the thermal cut-off 3 reaches the temperature and closes, that is, the pins 1 and 2 of the thermal cut-off 3 are connected. The specific analysis process is the same as that of the unclosed state of the thermal cut-off 3 above. When the thermal cut-off 3 is conducting, the control logic of the exhaust fan with manually selected wind speed is shown in Table 3-2 below:

[0049] Table 3-2 Control logic of the exhaust fan when the thermal cut-off 3 is conducting

[0050]

[0051]

[0052] In summary, through the circuit arrangement in this application, the function of automatically starting the exhaust fan can be achieved, and different gear wind speeds can be manually selected. At the same time, the situation where two windings in the existing exhaust fan are simultaneously selected and connected can be avoided, which is beneficial to preventing the motor from overheating seriously during long-term operation and has the effect of extending the service life of the exhaust fan. In addition, compared with the number of relays and the number of single-chip microcomputer control pins in the existing microwave oven, the number of relays and the number of single-chip microcomputer control pins in this application do not increase additionally, which is beneficial to quickly and efficiently optimizing and upgrading the existing microwave oven. Furthermore, the accuracy of gear control in the microwave oven is improved, and the service life of the microwave oven is extended.

[0053] A microwave oven, which includes the above-mentioned exhaust fan control circuit, and the exhaust fan control circuit is arranged inside the microwave oven.

[0054] In the present utility model, for any microwave oven, it may include the structure of the exhaust fan control circuit described in this embodiment. On the basis of the relevant structures and assembly relationships of the thermal cut-off and relay provided in this embodiment, the microwave oven further includes conventional components such as a magnetron, a turntable, and a furnace door. Since they are all prior arts, no further description will be given here.

[0055] The above are only the preferred embodiments of the present utility model and are not intended to limit the present utility model. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present utility model shall be included within the protection scope of the present utility model.

Claims

1. A fan control circuit, characterized in that: The device comprises an exhaust fan module (2), a thermal cut-off device (3), an adapter (4), a relay control module (5) and a single-chip microcomputer controller (6); one end of the exhaust fan module (2) and the thermal cut-off device (3) are connected to a power interface (1), and the other ends of the exhaust fan module (2) and the thermal cut-off device (3) are connected to the single-chip microcomputer controller (6) through the adapter (4) and the relay control module (5) in sequence, and the single-chip microcomputer controller (6) is connected to a key module (7).

2. The exhaust fan control circuit according to claim 1, characterized in that: The single-chip microcomputer controller (6) is connected to the relay control module (5) in a self-starting manner, and / or the key module (7) is connected to the relay control module (5) in a manually controlled manner via the single-chip microcomputer controller (6).

3. The exhaust fan control circuit according to claim 2, characterized in that: The power interface (1) comprises a live wire L interface and a neutral wire N interface, both of which are integrated on the power interface (1), and both of which are electrically connected to alternating current AC.

4. The exhaust fan control circuit according to claim 2, characterized in that: The exhaust fan module (2) comprises an exhaust fan and a starting capacitor C25, and the exhaust fan is connected to the starting capacitor C25, the power interface (1), and the adapter (4) respectively.

5. The exhaust fan control circuit according to claim 4, characterized in that: The exhaust fan comprises a capacitor pin, a gear pin, and a gear-off pin N. The capacitor pin, the gear pin, and the gear-off pin N are all arranged on the exhaust fan. The exhaust fan is connected to both ends of the starting capacitor C25 via the capacitor pin, the exhaust fan is connected to the adapter (4) via the gear pin, and the exhaust fan is connected to the neutral line N interface via the gear-off pin N.

6. The exhaust fan control circuit according to claim 5, characterized in that: The number of the gear position pins is n, where n is a positive integer.

7. The exhaust fan control circuit according to claim 6, characterized in that: The n=4, the gear pins include a highest gear pin T, a high gear pin H, a middle gear pin M, and a low gear pin L, and the exhaust fan is connected to pins 5, 7, 9, and 11 of the adapter (4) via the highest gear pin T, the high gear pin H, the middle gear pin M, and the low gear pin L, respectively.

8. The exhaust fan control circuit according to claim 3, characterized in that: Pin 1 of the thermal cut-off device (3) is respectively connected to the live wire L interface and pin 1 of the adapter (4), and pin 2 of the thermal cut-off device (3) is connected to pin 3 of the adapter (4).

9. The exhaust fan control circuit according to claim 3, characterized in that: The relay control module (5) comprises a relay and a drive chip IC1; the relay and the drive chip IC1 are both integrated on the relay control module (5); one end of the relay is connected to the single-chip microcomputer controller (6) through the drive chip IC1, and the other end of the relay is connected to the adapter (4).

10. A microwave oven, characterized in that: The microwave oven comprises an exhaust fan control circuit according to any one of claims 1 to 9, and the exhaust fan control circuit is arranged inside the microwave oven.

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