Dry burning prevention gas stove and dry burning prevention circuit thereof

Abstract

The application relates to a dry-burning prevention gas stove and a dry-burning prevention circuit thereof, the dry-burning prevention circuit comprising a control chip, a power supply control circuit, a voltage detection circuit and a protection current selection circuit; the power supply control circuit is connected with a power supply; the control chip is connected with a dry-burning prevention temperature sensing bag, the power supply control circuit and the voltage detection circuit; the protection current selection circuit is connected with the power supply control circuit, the control chip and a solenoid valve; the control chip is used for controlling the power supply control circuit to be turned on when the temperature detected by the dry-burning prevention temperature sensing bag exceeds a preset temperature threshold; the control chip is also used for detecting the output voltage of the power supply control circuit through the voltage detection circuit, and when the output voltage of the power supply control circuit is less than a first preset voltage, reducing the total resistance value of the protection current selection circuit to increase the solenoid current output to the solenoid valve. The above dry-burning prevention circuit can reduce the risk of insufficient solenoid current caused by insufficient power supply, and improve the control reliability of the dry-burning prevention gas stove.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of gas stove safety control, in particular to a dry burning prevention gas stove and a dry burning prevention circuit thereof. BACKGROUND

[0002] With the popularization of fire safety knowledge, people pay more and more attention to electrical safety in daily life. Dry burning prevention gas stoves emerge as the times require. Dry burning prevention gas stoves have the function of dry burning prevention, which can avoid accidents caused by dry burning and improve electrical safety.

[0003] The traditional dry burning prevention gas stove sends a valve current to the electromagnetic valve to make the electromagnetic valve open when the dry burning prevention protection of the gas stove is triggered, so as to achieve the purpose of dry burning prevention. However, due to the influence of the front-stage circuit, the traditional dry burning prevention gas stove has the problem of unstable valve current. When the valve current is insufficient, the electromagnetic valve cannot be opened. Therefore, the traditional dry burning prevention gas stove and its dry burning prevention circuit have the disadvantage of low control reliability. SUMMARY

[0004] Therefore, it is necessary to provide a dry burning prevention gas stove and a dry burning prevention circuit thereof to effectively improve the control reliability in view of the low control reliability of the traditional dry burning prevention gas stove.

[0005] In a first aspect, the present application provides a dry burning prevention circuit, comprising a control chip, a power supply control circuit, a voltage detection circuit and a protection current selection circuit.

[0006] The power supply control circuit is connected with a power supply; the control chip is connected with a dry burning prevention temperature sensing bag, the power supply control circuit and the voltage detection circuit; the protection current selection circuit is connected with the power supply control circuit, the control chip and an electromagnetic valve; the control chip is configured to control the power supply control circuit to be turned on when the temperature detected by the dry burning prevention temperature sensing bag exceeds a preset temperature threshold; the control chip is further configured to detect the output voltage of the power supply control circuit through the voltage detection circuit, and reduce the total resistance value of the protection current selection circuit when the output voltage of the power supply control circuit is less than a first preset voltage.

[0007] In one embodiment, the control chip is further configured to output an alarm information when the output voltage of the power supply control circuit is less than a second preset voltage, and the second preset voltage is less than the first preset voltage.

[0008] In one embodiment, the control chip is an MCU chip.

[0009] In one of the embodiments, the power supply control circuit comprises a first switch unit and a second switch unit; the first switch unit is connected to the power supply and the protection current selection circuit; the second switch unit is connected to the first switch unit and the control chip.

[0010] In one of the embodiments, the first switch unit comprises a transistor Q1 and a resistor R1; the second switch unit comprises a transistor Q2, a resistor R2 and a resistor R3.

[0011] The emitter of the transistor Q1 is connected to the power supply, the collector of the transistor Q1 is connected to the protection current selection circuit, and the base of the transistor Q1 is connected to the collector of the transistor Q2 through the resistor R1.

[0012] The base of the transistor Q2 is connected to the control chip through the resistor R2, the base of the transistor Q2 is grounded through the resistor R3, and the emitter of the transistor Q2 is grounded.

[0013] In one of the embodiments, the voltage detection circuit comprises a resistor R4, a resistor R5 and a capacitor C1; the control chip is connected to the power supply control circuit through the resistor R4, and the resistor R5 and the capacitor C1 are connected in parallel, one end of which is connected to the common end of the resistor R4 and the control chip, and the other end is grounded.

[0014] In one of the embodiments, the protection current selection circuit comprises a resistor R7, a resistor R8 and a third switch unit.

[0015] One end of the resistor R7 is connected to the power supply control circuit and the third switch unit, and the other end of the resistor R7 is connected to the electromagnetic valve and the third switch unit through the resistor R8; the third switch unit is connected to the control chip.

[0016] In one of the embodiments, the third switch unit comprises a transistor Q3 and a resistor R6.

[0017] The emitter of the transistor Q3 is connected to the resistor R7, the base of the transistor Q3 is connected to the control chip, and the collector of the transistor Q3 is connected to the resistor R8; the resistor R6 is connected to the emitter and the base of the transistor Q3.

[0018] In one of the embodiments, the protection current selection circuit further comprises a protection unit, one end of which is connected to the common end of the resistor R7 and the electromagnetic valve, and the other end of which is grounded.

[0019] In one of the embodiments, the protection unit is a TVS diode.

[0020] In a second aspect, the application provides a dry burning prevention gas stove, comprising a dry burning prevention temperature sensor, a power supply, a solenoid valve and the dry burning prevention circuit in any of the above embodiments.

[0021] The dry burning prevention circuit, when the temperature detected by the dry burning prevention temperature sensor exceeds the preset temperature threshold, the control chip controls the power control circuit to be turned on to take power from the power supply. Then the control chip detects the output voltage of the power control circuit through the voltage detection circuit, and when the output voltage of the power control circuit is less than the first preset voltage, the total resistance value of the protection current selection circuit is reduced to increase the solenoid current output to the solenoid valve through the protection current selection circuit. In this way, the risk of insufficient solenoid current caused by insufficient power of the power supply can be reduced, and the control reliability of the dry burning prevention gas stove can be improved. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 The block diagram of the dry burning prevention circuit of an embodiment;

[0023] Figure 2 The structural schematic diagram of the dry burning prevention circuit of an embodiment. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical scheme and advantages of the application more clear, the application will be further described in detail below in combination with the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the application and not to limit the application.

[0025] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0026] It can be understood that the terms "first", "second", etc. used in the application can be used herein to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish the first element from another element. For example, without departing from the scope of the application, the first resistor can be called the second resistor, and similarly, the second resistor can be called the first resistor. The first resistor and the second resistor are both resistors, but they are not the same resistor.

[0027] It can be understood that "connection" in the following embodiments means that the connected circuits, modules, units, etc. have electrical signal or data transmission between each other, which should be understood as "electrical connection", "communication connection" and the like.

[0028] As used herein, the singular forms "a", "an" and "the" include plural referents unless the context clearly dictates otherwise. It will be further understood that the terms "comprises", "comprising", "includes" and / or "including", or the like, when used in this specification, specify the presence of stated features, integers, steps, operations, components, parts, or combinations thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, components, parts, or combinations thereof. Also, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0029] In a first aspect, the application provides a dry-burn prevention circuit, which comprises a control chip 10, a power control circuit 20, a voltage detection circuit 30 and a protection current selection circuit 40. Figure 1 The power control circuit 20 is connected to a power supply VFF; the control chip 10 is connected to a dry-burn prevention temperature sensing bag, the power control circuit 20 and the voltage detection circuit 30; the protection current selection circuit 40 is connected to the power control circuit 20, the control chip 10 and a gas electromagnetic valve. The control chip 10 is configured to control the power control circuit 20 to be turned on when the temperature detected by the dry-burn prevention temperature sensing bag exceeds a preset temperature threshold; the control chip 10 is further configured to detect the output voltage of the power control circuit 20 through the voltage detection circuit 30, and reduce the total resistance value of the protection current selection circuit 40 when the output voltage of the power control circuit 20 is less than a first preset voltage.

[0030] The gas electromagnetic valve is a safety emergency shut-off device of a gas pipeline, which comprises a coil, a core, a spring, a connecting rod and a piston, and is connected to a main board circuit through inter-plate connection. The electromagnetic valve can be divided into a normally closed gas valve and a normally open gas valve. For the convenience of understanding, the working principle of the normally open electromagnetic valve will be briefly described below. In normal operation, the electromagnetic valve is in an open state and the coil is de-energized; when an accident occurs, current is input to the coil of the electromagnetic valve, the core is attracted, the connecting rod loses support, and under the action of the spring and the piston gravity, the main valve port is quickly closed to cut off the gas source.

[0031] Specifically, the dry-burn prevention temperature sensing bag is arranged at an intermediate position of the burner in contact with the bottom of the cooking utensil, and the electromagnetic valve is arranged at the gas supply port. The control chip 10 is used for connecting the dry-burn prevention temperature sensing bag, the protection current selection circuit 40 is used for connecting one end of the electromagnetic valve, and the other end of the electromagnetic valve can be arranged in a grounded manner. When the temperature detected by the dry-burn prevention temperature sensing bag exceeds the preset temperature threshold, a control signal is output by the control chip 10, so that the detection power supply control circuit 20 is turned on, and the electric energy provided by the power supply VFF is output to the electromagnetic valve through the power supply control circuit 20 and the protection current selection circuit 40. At the same time, the control chip 10 detects the output voltage of the power supply control circuit 20 through the voltage detection circuit 30, and when the output voltage of the power supply control circuit 20 is less than the first preset voltage, the total resistance value of the protection current selection circuit 40 is reduced to increase the input current of the electromagnetic valve and reduce the risk of insufficient valve current caused by insufficient electric energy of the power supply VFF. The control chip 10 can be an MCU chip, a DSP chip or other types of chips. In summary, the specific type of the control chip 10 is not limited in the embodiment of the application.

[0032] Further, after the control chip 10 outputs the control signal to make the power supply control circuit 20 conductive and inputs the current to the electromagnetic valve through the protection current selection circuit 40, after a preset time, the control chip 10 stops outputting the control signal to make the power supply control circuit 20 conductive, and the power supply control circuit 20 is disconnected to restore normal gas supply. In an embodiment, the preset time is 30S. It can be understood that according to the actual situation of the electromagnetic valve and the dry-burn prevention circuit, other lengths of preset time can also be set. For example, the preset time can be set to 20S, 30S or 50S.

[0033] Further, when the output voltage of the power supply control circuit 20 is greater than or equal to the first preset voltage, it can be considered that even if the total resistance value of the protection current selection circuit 40 remains unchanged, the current output to the electromagnetic valve through the protection current selection circuit 40 can also make the electromagnetic valve quickly close the main valve port to cut off the gas source. At this time, the control chip 10 does not output the control signal to the protection current selection circuit 40, which is beneficial to reduce the burden of the control chip 10 and improve the running speed of the circuit.

[0034] The dry-burning prevention circuit controls the control chip 10 to control the power control circuit 20 to be turned on when the temperature detected by the dry-burning prevention temperature sensor exceeds the preset temperature threshold, to obtain power from the power supply VFF. Then the control chip 10 detects the output voltage of the power control circuit 20 through the voltage detection circuit 30, and reduces the total resistance value of the protection current selection circuit 40 when the output voltage of the power control circuit 20 is less than the first preset voltage, to increase the solenoid valve current output to the solenoid valve through the protection current selection circuit 40. In this way, the risk of insufficient solenoid valve current caused by insufficient power of the power supply VFF can be reduced, and the control reliability of the dry-burning prevention gas stove can be improved.

[0035] In one embodiment, the control chip 10 is further configured to output an alarm information when the output voltage of the power control circuit 20 is less than a second preset voltage.

[0036] The second preset voltage is less than the first preset voltage. According to the device composition of the protection current selection circuit 40, the minimum total resistance value of the protection current selection circuit 40 can be calculated, and the second preset voltage can be calculated in combination with the minimum solenoid valve current required by the solenoid valve. When the output voltage of the power control circuit 20 is less than the second preset voltage, it means that even if the control chip 10 controls the protection current selection circuit 40 to input the total resistance value in the circuit to the minimum total resistance value, the input current of the solenoid valve is still less than the minimum solenoid valve current, and the gas source cannot be cut off. At this time, it means that the power supply or the dry-burning prevention circuit of the gas stove has failed, and the control chip 10 outputs an alarm information to remind the user to manually cut off the gas source.

[0037] Specifically, the control chip 10 can send the alarm information to the signal lamp and / or the buzzer, and the signal lamp and / or the buzzer generate an alarm signal to alarm. The alarm signal can be sound, light or a combination of sound and light. The control chip 10 can also send the alarm information to the display, and the display displays the alarm information. The control chip 10 can send the alarm information to the terminal, which can be a mobile terminal such as a mobile phone or a tablet computer, or an upper computer. The present embodiment does not limit the way the control chip 10 outputs the alarm information and the specific content of the alarm information.

[0038] In the above embodiment, when the output voltage of the power control circuit 20 is less than the second preset voltage, the control chip 10 outputs an alarm information, which can remind the user to manually cut off the gas source and repair the gas stove, and can further reduce the risk of insufficient solenoid valve current caused by insufficient power of the power supply VFF, and improve the control reliability of the dry-burning prevention gas stove.

[0039] In one embodiment, please refer to Figure 2The control chip 10 is an MCU (Single Chip Microcomputer) chip. The MCU chip is a chip-level computer in which a central processor is reduced in frequency and specification, and memory, counters, a USB (Universal Serial Bus), an A / D converter, a UART (Universal Asynchronous Receiver / Transmitter), and other peripheral interfaces are integrated on a single chip. The MCU chip has the advantages of high speed and strong versatility, and is beneficial to improving the control reliability of the dry-burning prevention circuit.

[0040] In one embodiment, referring to Figure 2 The power control circuit 20 includes a first switching unit 21 and a second switching unit 22. The first switching unit 21 is connected to the power supply VFF and the protection current selection circuit 40; and the second switching unit 22 is connected to the first switching unit 21 and the control chip 10.

[0041] The first switching unit 21 and the second switching unit 22 each include a switching device, which can be a triode, a relay, or a MOS (Metal-Oxide-Semiconductor Field-Effect Transistor) tube. In general, the specific device structure of the first switching unit 21 and the second switching unit 22 is not limited in the embodiments of the present application. It can be understood that the device structures of the first switching unit 21 and the second switching unit 22 are different, and the control signals output by the control chip 10 to turn on the first switching unit 21 and the second switching unit 22 are also different.

[0042] Specifically, when the temperature detected by the dry-burning prevention temperature sensing bag exceeds the preset temperature threshold, the control chip 10 outputs a control signal to turn on the first switching unit 21 and the second switching unit 22, and the power provided by the power supply VFF is output to the electromagnetic valve through the power control circuit 20 and the protection current selection circuit 40.

[0043] In one embodiment, referring to Figure 2 The first switching unit 21 includes a triode Q1 and a resistor R1; and the second switching unit 22 includes a triode Q2, a resistor R2, and a resistor R3. The emitter of the triode Q1 is connected to the power supply VFF, the collector of the triode Q1 is connected to the protection current selection circuit 40, and the base of the triode Q1 is connected to the collector of the triode Q2 through the resistor R1. The base of the triode Q2 is connected to the control chip 10 through the resistor R2, the base of the triode Q2 is grounded through the resistor R3, and the emitter of the triode Q2 is grounded.

[0044] Wherein, the triode Q1 and the triode Q2 are both PNP type triodes. Specifically, when the temperature detected by the dry burning protection temperature bag exceeds the preset temperature threshold, a high level signal is output by the control chip 10, so that the triode Q2 and the triode Q1 are turned on, and the power provided by the power supply VFF is output to the electromagnetic valve through the triode Q1 and the protection current selection circuit 40.

[0045] In the above embodiment, the triode is used as the switching device in the first switching unit 21 and the second switching unit 22. Since the switching triode has the characteristics of long service life, safe and reliable, no mechanical wear, fast switching speed, small size, etc., it is beneficial to improve the circuit performance.

[0046] In one embodiment, please continue to refer to Figure 2 The voltage detection circuit 30 includes a resistor R4, a resistor R5 and a capacitor C1; the control chip 10 is connected to the power supply control circuit 20 through the resistor R4, and the resistor R5 and the capacitor C1 are connected in parallel, one end of which is connected to the common end of the resistor R4 and the control chip 10, and the other end is grounded.

[0047] Wherein, the capacitor C1 can be a polar capacitor or a non-polar capacitor. When the capacitor C1 is a polar capacitor, the positive electrode is connected to the common end of the resistor R4 and the control chip 10, and the negative electrode is grounded. Specifically, the power provided by the power supply VFF passes through the triode Q1 and is divided by the resistor R4 and the resistor R5 to reach the control chip 10. The voltage measured by the control chip 10 is the voltage divided by the resistor R4, and according to the resistance values of the resistor R4 and the resistor R5, the output voltage of the power supply control circuit 20 can be calculated. When the output voltage of the power supply control circuit 20 is less than the first preset voltage, the control chip 10 outputs a control signal to reduce the total resistance value of the protection current selection circuit 40; when the output voltage of the power supply control circuit 20 is less than the second preset voltage, an alarm information is output.

[0048] In the above embodiment, the output voltage of the power supply control circuit 20 is monitored by setting the voltage dividing resistor, the circuit is simple and reliable, and the capacitor C1 and the resistor R5 are connected in parallel, which has a filtering function, can reduce the external interference to the voltage detection, and is beneficial to improve the accuracy of the voltage detection.

[0049] In one embodiment, please continue to refer to Figure 2 The protection current selection circuit 40 includes a resistor R7, a resistor R8 and a third switching unit 41. One end of the resistor R7 is connected to the power supply control circuit 10 and the third switching unit 41, the other end of the resistor R7 is connected to the electromagnetic valve, and the third switching unit 41 is connected through the resistor R8. The third switching unit 41 is connected to the control chip 10.

[0050] The third switch unit 41 comprises a switching device, which can be a transistor, a relay or a MOS tube. In summary, the specific device of the third switch unit 41 is not limited in the embodiment. It can be understood that the device in the third switch unit 41 is different, and the control signal output by the control chip 10 to make the third switch unit 41 conductive is also different.

[0051] Specifically, when the output voltage of the power control circuit 20 is greater than or equal to the first preset voltage, the control chip 10 controls the third switch unit 41 to be disconnected, the resistance R8 is disconnected, and the output current of the power control circuit 20 reaches the electromagnetic valve through the resistance R7, so that the electromagnetic valve quickly closes the main valve port to cut off the gas source.

[0052] When the output voltage of the power control circuit 20 is less than the first preset voltage, the control chip 10 controls the third switch unit 41 to be conductive, the resistance R8 is connected, the total resistance value of the protection current selection circuit 40 is reduced, the input current of the electromagnetic valve is increased, the minimum valve current of the electromagnetic valve is reached, the electromagnetic valve quickly closes the main valve port to cut off the gas source.

[0053] In the above embodiment, by setting the third switch unit 41 and the resistance R8, the control chip 10 controls the on-off of the third switch unit 41 according to the size of the output voltage of the power control circuit 20, and further controls whether the resistance R8 is connected or not. The effect of changing the total resistance value of the protection current selection circuit 40 and further changing the valve current size can be achieved, and the circuit is simple and reliable.

[0054] In one embodiment, please continue to refer to Figure 2 The third switch unit 41 comprises a transistor Q3 and a resistance R6. The emitter of the transistor Q3 is connected to the resistance R7, the base of the transistor Q3 is connected to the control chip 10, and the collector of the transistor Q3 is connected to the resistance R8. The resistance R6 is connected to the emitter and the base of the transistor Q3.

[0055] The transistor Q3 is a PNP type transistor. Specifically, when the output voltage of the power control circuit 20 is less than the first preset voltage, the control chip 10 controls the transistor Q3 to be conductive, the resistance R8 is connected in parallel with the resistance R7, the total resistance value of the protection current selection circuit 40 is reduced, the input current of the electromagnetic valve is increased, the minimum valve current of the electromagnetic valve is reached, the electromagnetic valve quickly closes the main valve port to cut off the gas source.

[0056] In the above embodiment, the transistor is used as the switching device in the third switch unit 41. Since the switching transistor has the characteristics of long service life, safety and reliability, no mechanical wear, fast switching speed and small size, it is beneficial to improve the performance of the circuit.

[0057] In one embodiment, please continue to refer toFigure 2 The protection current selection circuit 40 further comprises a protection unit 42, one end of the protection unit 42 being connected to the common end of the resistor R7 and the electromagnetic valve, and the other end of the protection unit 42 being grounded.

[0058] Specifically, the protection unit 42 comprises a protection device, which can be an overcurrent protection device or an overvoltage protection device. When the protection unit 42 comprises an overvoltage protection device, the overvoltage protection device can be a TVS diode or a varistor. In general, the circuit type and specific device composition of the protection unit 42 are not limited in the embodiments of the present application. The protection unit 42 can protect the electromagnetic valve from sudden changes in electrical signals and prevent the electromagnetic valve from being damaged when a circuit fault occurs.

[0059] In an embodiment, please continue to refer to Figure 2 The protection unit 42 is a TVS diode D1.

[0060] The TVS diode is an electronic component used for protection, which can protect electrical equipment from voltage spikes introduced by wires. Specifically, the negative electrode of the TVS diode is connected to the common end of the resistor R7 and the electromagnetic valve, and the positive electrode is grounded. When a large transient voltage is generated in the circuit, the TVS diode D1 uses the avalanche principle to change the impedance value between the two ends from high impedance to low impedance at a very high speed, to absorb the instantaneous large current and clamp the voltage between the two ends to a predetermined value, thereby protecting the electromagnetic valve from the impact of transient high voltage spikes. When the overvoltage disappears, the TVS diode D1 will automatically return. In an embodiment, the TVS diode is a bidirectional TVS diode. Specifically, the bidirectional TVS diode can absorb transient large pulse power in both positive and negative directions and clamp the voltage to a predetermined level, achieving the effect of protecting the electromagnetic valve.

[0061] In the above embodiment, the TVS diode D1 is used as the protection device for the electromagnetic valve. Since the overvoltage response speed of the TVS diode D1 is faster than that of other overvoltage protection elements, the protection capability of the protection unit 42 can be improved.

[0062] In an embodiment, please continue to refer to Figure 2, the control chip 10 is an MCU chip; the power supply control circuit 20 comprises a transistor Q1, a resistor R1, a transistor Q2, a resistor R2 and a resistor R3; the voltage detection circuit 30 comprises a resistor R4, a resistor R5 and a capacitor C1; the protection current selection circuit 40 comprises a resistor R7, a resistor R8, a transistor Q3, a resistor R6 and a TVS diode D1. Among them, the MCU chip is used for connecting the dry burning prevention temperature sensing bag. The emitter of the transistor Q1 is used for connecting the power supply VFF, the collector of the transistor Q1 is connected with the resistor R7, and the base of the transistor Q1 is connected with the collector of the transistor Q2 through the resistor R1. The base of the transistor Q2 is connected with the MCU chip through the resistor R2, the base of the transistor Q2 is grounded through the resistor R3, and the emitter of the transistor Q2 is grounded. The MCU chip is connected with the collector of the transistor Q1 through the resistor R4, the resistor R5 and the capacitor C1 are connected in parallel, one end of which is connected with the resistor R4 and the common terminal of the MCU chip, and the other end is grounded. The emitter of the transistor Q3 is connected with the resistor R7, the other end of the resistor R7 is connected with the electromagnetic valve, and the collector of the transistor Q3 is connected with the electromagnetic valve through the resistor R8. The base of the transistor Q3 is connected with the MCU chip. The resistor R6 is connected with the emitter and the base of the transistor Q3. One end of the bidirectional TVS diode D1 is connected with the common terminal of the resistor R7 and the electromagnetic valve, and the other end of the bidirectional TVS diode D1 is grounded.

[0063] Specifically, when the temperature detected by the dry burning prevention temperature sensing bag exceeds the preset temperature threshold, a high level signal is output by the control chip 10, so that the transistor Q2 and the transistor Q1 are turned on, and the power provided by the power supply VFF reaches the resistor R4 through the transistor Q1, and reaches the control chip through the resistor R4 and the resistor R5. The voltage measured by the control chip 10 is the voltage drop value of the resistor R4, and according to the resistance values of the resistor R4 and the resistor R5, the output voltage of the power supply control circuit 20 can be calculated.

[0064] When the output voltage of the power supply control circuit 20 is greater than or equal to the first preset voltage, the control chip 10 controls the transistor Q3 to be turned off, the resistor R8 is disconnected, and the power provided by the power supply VFF reaches the electromagnetic valve through the transistor Q1 and the resistor R7, so that the electromagnetic valve quickly closes the main valve port to cut off the gas source.

[0065] When the output voltage of the power supply control circuit 20 is greater than or equal to the second preset voltage and less than the first preset voltage, the control chip 10 controls the transistor Q3 to be turned on, the resistor R8 is connected in parallel with the resistor R7, the total resistance value of the protection current selection circuit 40 is reduced, the input current of the electromagnetic valve is increased, the minimum valve opening current of the electromagnetic valve is reached, and the electromagnetic valve quickly closes the main valve port to cut off the gas source.

[0066] When the output voltage of the power control circuit 20 is less than the second preset voltage, even if the control chip 10 controls the triode Q3 to be turned on, so that the resistor R8 and the resistor R7 are connected in parallel, the input current of the electromagnetic valve is still less than the minimum valve current, and the gas source cannot be cut off. At this time, it indicates that the power supply of the gas stove or the anti-dry burning circuit has failed, and the control chip 10 outputs an alarm information to remind the user to manually cut off the gas source.

[0067] In the above embodiment, when the temperature detected by the anti-dry burning temperature sensing bag exceeds the preset temperature threshold, the control chip 10 controls the triode Q2 and the triode Q1 to be turned on to obtain power from the power supply VFF. Then, the control chip 10 calculates the output voltage of the power control circuit 20 through the voltage division value of the resistor R4, and when the output voltage of the power control circuit 20 is less than the first preset voltage, the control chip 10 controls the triode Q3 to be turned on to connect the resistor R8 and the resistor R7 in parallel, so as to reduce the total resistance value and increase the valve current output to the electromagnetic valve. In this way, the risk of insufficient valve current caused by insufficient power of the power supply VFF can be reduced, and the control reliability of the anti-dry burning gas stove can be improved. Further, when the output voltage of the power control circuit 20 is less than the second preset voltage, the control chip 10 outputs an alarm information, which can remind the user to manually cut off the gas source and perform repair processing of the gas stove, so as to further reduce the risk of insufficient valve current caused by insufficient power of the power supply VFF and improve the control reliability of the anti-dry burning gas stove. In addition, the bidirectional TVS diode D1 can absorb transient large pulse power in both positive and negative directions, and clamp the voltage to a predetermined level, thereby achieving the effect of protecting the electromagnetic valve.

[0068] In a second aspect, the present application provides an anti-dry burning gas stove, which comprises an anti-dry burning temperature sensing bag, a power supply, an electromagnetic valve and an anti-dry burning circuit according to any of the above embodiments.

[0069] The anti-dry burning circuit is connected to the anti-dry burning temperature sensing bag, the power supply and the electromagnetic valve. The specific limitations of the anti-dry burning circuit can be referred to the above, which will not be repeated here. Specifically, the anti-dry burning temperature sensing bag is arranged at the middle position of the burner which contacts the bottom of the cooking utensil, and is used to detect the temperature of the bottom of the cooking utensil. When dry burning occurs, the temperature of the bottom of the cooking utensil will continue to increase. When the temperature detected by the anti-dry burning temperature sensing bag exceeds the preset temperature threshold, the anti-dry burning circuit obtains power from the power supply and outputs a valve current to the electromagnetic valve, so that the electromagnetic valve quickly closes the main valve port to cut off the gas source, thereby avoiding fire accidents caused by dry burning.

[0070] The technical features of the above embodiments can be combined in any manner. To make the description concise, not all possible combinations of the technical features in the above embodiments are described, but as long as the combinations of the technical features do not exist contradictions, they should be considered as the scope of the present application.

[0071] The above embodiment only expresses several implementation manners of the application, and the description is more specific and detailed, but it cannot be understood as a limitation on the scope of the patent. It should be pointed out that for ordinary skilled persons in the art, several modifications and improvements can be made without departing from the concept of the application, and these all belong to the protection scope of the application. Therefore, the protection scope of the patent of the application should be subject to the appended claims.

Claims

1. A dry-burn prevention circuit, characterized by comprising: The control chip, the power supply control circuit, the voltage detection circuit and the protection current selection circuit are included. The power supply control circuit is connected with a power supply; the control chip is connected with an anti-dry burning temperature sensing bag, the power supply control circuit and the voltage detection circuit; the protection current selection circuit is connected with the power supply control circuit, the control chip and an electromagnetic valve; the control chip is used for controlling the power supply control circuit to be turned on when the temperature detected by the anti-dry burning temperature sensing bag exceeds a preset temperature threshold; the control chip is also used for detecting the output voltage of the power supply control circuit through the voltage detection circuit, and reducing the total resistance value of the protection current selection circuit when the output voltage of the power supply control circuit is less than a first preset voltage. The protection current selection circuit is used for outputting a valve opening current to the electromagnetic valve, so that the electromagnetic valve closes a main valve port and cuts off a gas source.

2. The anti-burnout circuit of claim 1, wherein, The control chip is also used for outputting alarm information when the output voltage of the power supply control circuit is less than a second preset voltage, and the second preset voltage is less than the first preset voltage.

3. The anti-burnout circuit of claim 1, wherein, The control chip is an MCU chip.

4. The anti-burnout circuit of claim 1, wherein, The power supply control circuit includes a first switching unit and a second switching unit; the first switching unit is connected with the power supply and the protection current selection circuit; and the second switching unit is connected with the first switching unit and the control chip.

5. The anti-burnout circuit of claim 4, wherein, The first switching unit includes a transistor Q1 and a resistor R1; and the second switching unit includes a transistor Q2, a resistor R2 and a resistor R3. The emitter of the transistor Q1 is connected with the power supply, the collector of the transistor Q1 is connected with the protection current selection circuit, and the base of the transistor Q1 is connected with the collector of the transistor Q2 through the resistor R1. The base of the transistor Q2 is connected with the control chip through the resistor R2, the base of the transistor Q2 is grounded through the resistor R3, and the emitter of the transistor Q2 is grounded.

6. The anti-burnout circuit of claim 1, wherein, The voltage detection circuit includes a resistor R4, a resistor R5 and a capacitor C1; the control chip is connected with the power supply control circuit through the resistor R4, and the resistor R5 and the capacitor C1 are connected in parallel, one end of which is connected with the resistor R4 and the control chip, and the other end is grounded.

7. The anti-burnout circuit of claim 1, wherein, The protection current selection circuit includes a resistor R7, a resistor R8 and a third switching unit. One end of the resistor R7 is connected with the power supply control circuit and the third switching unit, the other end of the resistor R7 is connected with the electromagnetic valve, and the third switching unit is connected with the control chip through the resistor R8.

8. The anti-burnout circuit of claim 7, wherein, The third switching unit includes a transistor Q3 and a resistor R6. The emitter of the transistor Q3 is connected with the resistor R7, the base of the transistor Q3 is connected with the control chip, and the collector of the transistor Q3 is connected with the resistor R8; and the resistor R6 is connected with the emitter and the base of the transistor Q3.

9. The anti-burnout circuit of claim 7, wherein, The protection current selection circuit further includes a protection unit, one end of which is connected with the resistor R7 and the electromagnetic valve, and the other end of which is grounded.

10. The anti-burnout circuit of claim 9, wherein, The protection unit is a TVS diode.

11. A dry-burn prevention gas stove, characterized in that, The dry-burning prevention circuit comprises a dry-burning prevention temperature sensor, a power supply, a solenoid valve and the dry-burning prevention circuit as claimed in any one of claims 1 to 10.

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