Induction hand warmer circuit

Abstract

The utility model specifically relates to an induction hand warmer circuit, including a power supply circuit, the power supply circuit is respectively connected with a detection comparison output circuit and a control circuit, the detection comparison output circuit includes a thermistor NTC and a comparator U1, the power supply circuit includes a bridge stack DB1, a VCC terminal and a VDD terminal, the control circuit includes a first transistor Q1, a second transistor Q2, a relay JQ and a heating element RL, the U1-4 terminal of the detection comparison output circuit is connected to the U1-4 terminal of the control circuit, and the base of the first transistor Q1 is connected to the U1-4 terminal. The beneficial effect of the utility model is that through the detection comparison output circuit, one more temperature detection is implemented, thereby controlling the relay to be attracted or disconnected, thereby controlling the working state of the heating element RL, playing an additional temperature protection, thereby improving safety.

Description

Technical Field

[0001] The utility model specifically relates to an induction hand warmer circuit. Background Art

[0002] Electric hand warmers are also called "electric heating bags" or "electric hot water bags". They are small in size, heat up quickly, store heat for a long time, have a soft appearance and feel comfortable. As an ideal heating product in winter, they are very popular among people.

[0003] The flexible hand warmer structure includes a power plug and a bag body. The bag body has a protective cavity to accommodate the socket and the electrical component control circuit assembled under the socket. The control circuit is connected to the heating element, and the water injection hole is installed elsewhere in the bag body and separated from the protective cavity.

[0004] The power supply plug is provided with a mechanical explosion-proof device (commonly known as an explosion-proof clip). When the mechanical explosion-proof device (commonly known as an explosion-proof clip) is replaced by electronic control, a position for installing a sensing element needs to be provided on the bag body to meet safety standards while having a simple structure and being easy to install.

[0005] A patent document has been published in China. The application number of the patent document is 202021430039.4. The name of the utility model is a flexible hand warmer. The published structure is: it includes a protective cavity and a bag body, and the protective cavity is installed in the bag body, wherein: the protective cavity is provided with a probe position, the probe position has a slot, one end of the probe is connected to the signal line, the signal line is connected to the PCB board, one end of the probe is installed in the circular slot, the first epoxy resin is encapsulated in the probe position, and the other end of the probe is exposed outside the protective cavity and in contact with the heat storage liquid in the bag body.

[0006] In the face of complex usage environments, users and merchants hope to further enhance security based on the above structure. In order to meet the needs, this structure is further improved on the above structure. Summary of the invention

[0007] The utility model aims to solve at least one of the technical problems existing in the prior art. To this end, one purpose of the utility model is to provide an induction hand warmer circuit that can provide an additional temperature protection to improve safety.

[0008] According to the induction hand warmer circuit of the utility model, it includes a power supply circuit, the power supply circuit is respectively connected to a detection comparison output circuit and a control circuit, the detection comparison output circuit includes a thermistor NTC and a comparator U1, the thermistor NTC is connected to the 1st pin of the comparator U1, the 4th pin of the comparator U1 is connected to the U1-4 terminal, the 3rd pin of the comparator U1 is connected to the fourth resistor R4 and the fifth resistor R5, the power supply circuit includes a bridge stack DB1, a VCC terminal and a VDD terminal, and the output terminal of the bridge stack DB1 is respectively connected to the VCC terminal and the VDD terminal The VDD end of the power supply circuit is connected to the VDD end of the detection comparison output circuit, the control circuit includes a first transistor Q1, a second transistor Q2, a relay JQ and a heating element RL, the connector K2 of the relay JQ is connected to the heating element RL, the collector of the second transistor Q2 is connected to the relay JQ, the collector of the first transistor Q1 is connected to the base of the second transistor Q2, the U1-4 end of the detection comparison output circuit is connected to the U1-4 end of the control circuit, and the base of the first transistor Q1 is connected to the U1-4 end.

[0009] Specifically, the control circuit also includes a circuit breaker K3, a temperature controller K4, a control chip U2 and an induction probe. The base of the second transistor Q2 is connected to pin 7 of the control chip U2, pin 5 of the control chip U2 is connected to the induction probe, the circuit breaker K3 and the temperature controller K4 are connected in series, and one end of the circuit breaker K3 is connected to the heating element RL.

[0010] Specifically, the base of the second transistor Q2 is connected to the pin 7 of the control chip U2 via a seventh resistor R7, and a fourth capacitor C4 is provided between the collector and the emitter of the first transistor Q1.

[0011] Specifically, the pin 3 of the control chip U2 is connected to a VDD terminal, and the VDD terminal is connected to a fifth capacitor C5.

[0012] Specifically, the base of the first transistor Q1 is connected to the U1 - 4 terminal via an eighth resistor R8 .

[0013] Specifically, the output end of the bridge stack DB1 is also provided with a second filter capacitor C2, a third overcapacitor C3, a discharge resistor R3 and a Zener diode D1. The second filter capacitor C2 and the third overcapacitor C3 are connected in series, one end of the discharge resistor R3 is connected to one end of the second filter capacitor C2, the other end of the discharge resistor R3 is connected to the other end of the third overcapacitor C3, the common end between the discharge resistor R3 and the third overcapacitor C3 is connected to the Zener diode D1, the Zener diode D1 is connected to the VDD end, and the VCC end and the VDD end are connected through the second resistor R2.

[0014] Specifically, the base of the first transistor Q1 is also connected to a dump switch K1, and the dump switch K1 is also connected to a relay JQ.

[0015] Specifically, the relay JQ is further connected in parallel with a second diode D2 and a light emitting diode LED, and the second diode D2 is also connected to a VCC terminal.

[0016] The beneficial effect of the utility model is that the circuit implements an additional temperature detection by detecting and comparing the output circuit, thereby controlling the relay to be attracted or disconnected, thereby controlling the working state of the heating element RL, playing an additional temperature protection, and thus improving safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings.

[0018] Figure 1 It is a control circuit diagram of the utility model.

[0019] Figure 2 It is a power supply circuit diagram of the utility model.

[0020] Figure 3 The utility model is a detection comparison output circuit diagram. DETAILED DESCRIPTION

[0021] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0022] Reference below Figures 1 to 3Description According to the induction hand warmer circuit of the embodiment of the utility model, the power supply circuit includes a power supply circuit, the power supply circuit is respectively connected to the detection comparison output circuit and the control circuit, the detection comparison output circuit includes a thermistor NTC and a comparator U1, the thermistor NTC is connected to the 1st pin of the comparator U1, the 4th pin of the comparator U1 is connected to the U1-4 terminal, the 3rd pin of the comparator U1 is connected to the fourth resistor R4 and the fifth resistor R5, the power supply circuit includes a bridge stack DB1, a VCC terminal and a VDD terminal, the output terminal of the bridge stack DB1 is respectively connected to the VCC terminal and the VDD terminal The ends are connected, the VDD end of the power supply circuit is connected to the VDD end of the detection comparison output circuit, the control circuit includes a first transistor Q1, a second transistor Q2, a relay JQ and a heating element RL, the connector K2 of the relay JQ is connected to the heating element RL, the collector of the second transistor Q2 is connected to the relay JQ, the collector of the first transistor Q1 is connected to the base of the second transistor Q2, the U1-4 end of the detection comparison output circuit is connected to the U1-4 end of the control circuit, and the base of the first transistor Q1 is connected to the U1-4 end.

[0023] The bridge device DB1, the first filter capacitor C1 and the second capacitor C2, the discharge resistor R3, the voltage-stabilizing diode D1, the first resistor R1 and the first capacitor C1 form a resistance-capacitance function. The capacitive reactance generated under a certain AC signal frequency is used to limit the maximum operating current. The output voltage through the voltage-stabilizing diode D1 is input to the detection comparison output circuit through the VDD terminal, and the VCC terminal is used to supply power to the relay JQ.

[0024] The thermistor NTC is used to detect the temperature change of the hand warmer. When the thermistor NTC detects that the temperature in the hand warmer reaches a specified value, the resistance value of the thermistor NTC is at its maximum, and the voltage of the input comparator U1's pin 1 is lower than the voltage of the comparator U1's pin 3, and the voltage value is limited by the resistance value of the fourth resistor R4 and the third resistor R3; the voltage value is 6V; the comparator U1's pin 4 stops outputting voltage, making the base of the first transistor Q1 and the base of the second transistor Q2 in the disconnected state, making the relay JQ disconnected, and making the heating element RL power off and stop heating, which plays a role in preventing dry burning and provides an additional protection. In addition, the heating element RL can be an electric heating tube or a PTC heating sheet, etc., not limited to the examples given.

[0025] When the temperature in the hand warmer detected by the thermistor NTC is lower than the specified value, the resistance value of the thermistor NTC is at the minimum, and the voltage of the input comparator U1's pin 1 is higher than the voltage of the comparator U1's pin 3. At this time, the voltage value of the input comparator U1's pin 1 is greater than 6V, and the comparator U1's pin 4 outputs a voltage to the U1-4 terminal. The voltage is input to the base of the first transistor Q1 and is turned on, so that the base of the second transistor Q2 is also energized and turned on, so that the relay JQ is closed, and the heating element RL is energized and heated. The heating element RL heats the liquid in the hand warmer. In addition, the second transistor Q2 controls the working state of the relay JQ, for example, on or off.

[0026] The control circuit described in this circuit also includes a circuit breaker K3, a thermostat K4, a control chip U2 and a sensing probe. The base of the second transistor Q2 is connected to pin 7 of the control chip U2, and pin 5 of the control chip U2 is connected to the sensing probe. The circuit breaker K3 and the thermostat K4 are connected in series, and one end of the circuit breaker K3 is connected to the heating element RL. The circuit breaker K3 and the thermostat K4 are used to prevent dry burning, and the circuit breaker K3 can disconnect the voltage to stop heating the heating element RL. The combination of the control chip U2 and the sensing probe can sense the temperature of the liquid in the hand warmer. When the liquid temperature does not reach the specified value, the pin 7 of the control chip U2 outputs a voltage to turn on the base of the second transistor Q2, close the relay JQ, and close the K2 end of the relay JQ to implement power-on.

[0027] The base of the second transistor Q2 of the present circuit is connected to the 7th pin of the control chip U2 through the seventh resistor R7, and a fourth capacitor C4 is provided between the collector and the emitter of the first transistor Q1. The 3rd pin of the control chip U2 of the present circuit is connected to the VDD terminal, and the VDD terminal is connected to the fifth capacitor C5. The base of the first transistor Q1 of the present circuit is connected to the U1-4 terminal through the eighth resistor R8.

[0028] The output end of the bridge stack DB1 described in this circuit is also provided with a second filter capacitor C2, a third overcapacitor C3, a discharge resistor R3 and a voltage-stabilizing diode D1. The second filter capacitor C2 and the third overcapacitor C3 are connected in series, one end of the discharge resistor R3 is connected to one end of the second filter capacitor C2, the other end of the discharge resistor R3 is connected to the other end of the third overcapacitor C3, the common end between the discharge resistor R3 and the third overcapacitor C3 is connected to the voltage-stabilizing diode D1, the voltage-stabilizing diode D1 is connected to the VDD end, and the VCC end is connected to the VDD end through the second resistor R2. The voltage-stabilizing diode D1 plays a role in voltage stabilization, and the second filter capacitor C2 and the third overcapacitor C3 are combined to play a filtering role.

[0029] The base of the first transistor Q1 in this circuit is also connected to a tipping switch K1, which is also connected to a relay JQ. The tipping switch K1 prevents the hand warmer from tipping over. In the tipping state, the heating element RL is exposed to the liquid surface, which may cause the heating element RL to dry burn.

[0030] The relay JQ of the circuit is also connected in parallel with a second diode D2 and a light emitting diode LED, and the second diode D2 is also connected to a VCC terminal. The light emitting diode LED displays the working state of the relay JQ.

[0031] Although the embodiments of the present invention have been shown and described, those skilled in the art will appreciate that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

Claims

1. An induction hand warmer circuit, including a power supply circuit, characterized in that: The power supply circuit is respectively connected with a detection comparison output circuit and a control circuit. The detection comparison output circuit includes a thermistor NTC and a comparator U1. The thermistor NTC is connected to the 1st pin of the comparator U1. The 4th pin of the comparator U1 is connected to the U1-4 terminal. The 3rd pin of the comparator U1 is connected to the fourth resistor R4 and the fifth resistor R5. The power supply circuit includes a bridge stack DB1, a VCC terminal and a VDD terminal. The output terminal of the bridge stack DB1 is respectively connected to the VCC terminal and the VDD terminal. The VDD terminal of the power supply circuit is connected to Connected to the VDD end of the detection comparison output circuit, the control circuit includes a first transistor Q1, a second transistor Q2, a relay JQ and a heating element RL, the connector K2 of the relay JQ is connected to the heating element RL, the collector of the second transistor Q2 is connected to the relay JQ, the collector of the first transistor Q1 is connected to the base of the second transistor Q2, the U1-4 end of the detection comparison output circuit is connected to the U1-4 end of the control circuit, and the base of the first transistor Q1 is connected to the U1-4 end.

2. The induction hand warmer circuit according to claim 1, characterized in that: The control circuit also includes a circuit breaker K3, a temperature controller K4, a control chip U2 and a sensing probe. The base of the second transistor Q2 is connected to pin 7 of the control chip U2, pin 5 of the control chip U2 is connected to the sensing probe, the circuit breaker K3 and the temperature controller K4 are connected in series, and one end of the circuit breaker K3 is connected to the heating element RL.

3. The induction hand warmer circuit according to claim 2, characterized in that: The base of the second transistor Q2 is connected to the pin 7 of the control chip U2 via a seventh resistor R7, and a fourth capacitor C4 is provided between the collector and the emitter of the first transistor Q1.

4. The induction hand warmer circuit according to claim 2, characterized in that: Pin 3 of the control chip U2 is connected to a VDD terminal, and the VDD terminal is connected to a fifth capacitor C5.

5. The induction hand warmer circuit according to claim 1, characterized in that: The base of the first transistor Q1 is connected to the U1 - 4 terminal via an eighth resistor R8 .

6. The induction hand warmer circuit according to claim 1, characterized in that: The output end of the bridge stack DB1 is also provided with a second filter capacitor C2, a third overcapacitor C3, a discharge resistor R3 and a voltage-stabilizing diode D1. The second filter capacitor C2 and the third overcapacitor C3 are connected in series, one end of the discharge resistor R3 is connected to one end of the second filter capacitor C2, the other end of the discharge resistor R3 is connected to the other end of the third overcapacitor C3, the common end between the discharge resistor R3 and the third overcapacitor C3 is connected to the voltage-stabilizing diode D1, the voltage-stabilizing diode D1 is connected to the VDD end, and the VCC end and the VDD end are connected through the second resistor R2.

7. The induction hand warmer circuit according to claim 1, characterized in that: The base of the first transistor Q1 is also connected to a dump switch K1, and the dump switch K1 is also connected to a relay JQ.

8. The induction hand warmer circuit according to claim 1, characterized in that: The relay JQ is also connected in parallel with a second diode D2 and a light emitting diode LED, and the second diode D2 is also connected to a VCC terminal.

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