Overheating protection circuit of intelligent water dispenser

Abstract

The utility model discloses an intelligent water dispenser overheat protection circuit, which comprises a heating tube installed on the intelligent water dispenser, the heating tube comprises a thermistor NTC and an overheat protection switch, the thermistor NTC is electrically connected with an over-current protection circuit and an MCU control circuit, the MCU control circuit is electrically connected with the over-current protection circuit, and the overheat protection switch is electrically connected with the MCU control circuit. The MCU control circuit is electrically connected with a driving control circuit, the driving control circuit is electrically connected with a relay, and the relay is electrically connected with the overheat protection switch; the overcurrent protection circuit is electrically connected with a leakage protector, the leakage protector is electrically connected with the heating tube, and the MCU controller comprises a main control chip MCU. According to the utility model, the leakage protector and the overcurrent protection circuit are arranged to carry out leakage and overcurrent protection in the overheating protection process of the heating tube, so that the stability in the detection process is improved, and the risks of short circuit and electric shock in the overheating protection process are reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of water dispensers, in particular to an overheat protection circuit for an intelligent water dispenser. Background Technique

[0002] Traditional water dispensers use hot water bags for heating, with slow heating speed. When the hot water is not taken in time after heating, the water temperature will drop and then the water will be reheated repeatedly to form the so-called "thousand-boiled water", which is not good for health. Moreover, the equipment is in a working state for a long time, consuming a lot of electricity and being not environmentally friendly. To solve the drawbacks of traditional water dispensers, intelligent water dispensers came into being. They adopt thick-film heating technology, with fast heating. There is no need for an inner tank to store water for heating. The normal temperature water can be heated to the required temperature as it flows through the thick-film tube. If the heating tube in the water dispenser lacks water or dries out, it is easy to cause the heating tube of the water dispenser or even the circuit of the water dispenser to be burned out, which not only affects the working life of the water dispenser but also poses a safety hazard. To solve this problem, the application number: 201920099399.1 discloses a dual overheat protection circuit applied to a water dispenser. The dual overheat protection circuit includes an MCU control circuit, a drive control circuit, and a relay connected in sequence. The dual overheat protection circuit also includes a thermistor and a mechanical reset overheat protector switch arranged on the heating tube of the water dispenser. The thermistor is connected to the MCU control circuit, the drive control circuit is connected to the coil of the relay, the moving contact of the relay is connected to one input end of the power supply of the heating tube, and the static contact of the relay is connected to the other input end of the power supply of the heating tube through the mechanical reset overheat protector switch; it can effectively prevent the heating tube of the water dispenser from drying out, with advantages such as high safety and good reliability, and can effectively protect the water dispenser and eliminate potential safety hazards;

[0003] The above-mentioned dual overheat protection circuit applied to a water dispenser can automatically cut off the power when the heating tube is overheated, effectively preventing the heating tube of the water dispenser from drying out and improving the use safety. However, it still has the following deficiencies: 1. It lacks the function of overcurrent protection during the overheat detection process. When the current is too large during the detection process, it is easy to cause the situation of short circuit and damage to components; 2. Its overheat protection circuit lacks the function of leakage protection. When leakage occurs during the detection process, it is easy to cause electric shock hazards; Considering the above situation, the above patent is improved, so we propose an overheat protection circuit for an intelligent water dispenser. Summary of the Utility Model

[0004] The purpose of the utility model is to solve the shortcomings existing in the prior art and propose an overheat protection circuit for an intelligent water dispenser.

[0005] To achieve the above purpose, the utility model adopts the following technical solutions:

[0006] An overheat protection circuit for an intelligent water dispenser, including a heating tube installed on the intelligent water dispenser. The heating tube includes a thermistor NTC and an overheat protection switch. The thermistor NTC is electrically connected to an overcurrent protection circuit and an MCU control circuit. The MCU control circuit is electrically connected to the overcurrent protection circuit. The MCU control circuit is electrically connected to a drive control circuit. The drive control circuit is electrically connected to a relay. The relay is electrically connected to the overheat protection switch;

[0007] The overcurrent protection circuit is electrically connected to a leakage protector. The leakage protector is electrically connected to the heating tube. The MCU controller includes a main control chip MCU.

[0008] Preferably, the overcurrent protection circuit includes a triode Q1. One end of a resistor R2 and one end of a capacitor C2 are electrically connected to the base of the triode Q1. The other end of the capacitor C2 is electrically connected to one end of a resistor R1. The other end of the resistor R2 is electrically connected to the positive electrode of a diode D1 and one end of a capacitor C1. One end of the capacitor C1 is also electrically connected to the positive electrode of the diode D1. The other end of the capacitor C1 is electrically connected to the other end of the resistor R1. One end of a resistor R3 is electrically connected to the collector of the triode Q1. The other end of the resistor R3 is grounded. One end of a resistor R6 and one end of a resistor R5 are electrically connected to the emitter of the triode Q1. The other end of the resistor R6 is electrically connected to the other end of the resistor R1 and the other end of the capacitor C1. The other end of the resistor R5 is electrically connected to the emitter of a triode Q2. One end of a resistor R4 is electrically connected to the base of the triode Q2. The other end of the resistor R4 is electrically connected to the other end of the resistor R6, the other end of the resistor R1, and the other end of the capacitor C1. One end of a resistor R7 is electrically connected to the collector of the triode Q2. The other end of the resistor R7 is grounded. The other end of the resistor R7 is also electrically connected to pin 1 of the main control chip MCU.

[0009] Preferably, the leakage protector includes a comparator U1. Pin 2 of the comparator U1 is electrically connected to a supply voltage VCC and one end of a current transformer CT. The other end of the current transformer CT is electrically connected to one end of an adjustable resistor RL. The other end of the adjustable resistor RL is electrically connected to pin 3 of the comparator U1. Pin 4 of the comparator U1 is electrically connected to one end of an automatic power-off switch L1. The other end of the automatic power-off switch L1 is electrically connected to the negative electrode of the diode D1 and the base of the triode Q2.

[0010] Preferably, the same automatic power-off switch L2 is electrically connected between pin 4 of the comparator U1 and the heating tube. The automatic power-off switch L2 is used to control the connection between the heating tube and the leakage protector.

[0011] Preferably, the leakage protector is used to monitor the incoming and outgoing state of the current and judge its leakage situation.

[0012] Preferably, the overcurrent protection circuit is used to monitor the current flowing through the circuit. When the current exceeds the set value, it automatically cuts off the power supply to prevent component damage caused by overload.

[0013] Compared with the existing technology, the beneficial effects of the present utility model are as follows:

[0014] By providing a leakage protector and an overcurrent protection circuit, the present utility model can perform leakage and overcurrent protection during the overheat protection of the heating tube, improve the stability during the detection process, and reduce the risks of short circuit and electric shock during the overheat protection process. Description of the Drawings

[0015] Figure 1 It is a connection block diagram of an overheat protection circuit for an intelligent water dispenser proposed by the present utility model;

[0016] Figure 2 It is a circuit diagram of the connection between the overcurrent protection circuit and the MUC main control chip of the overheat protection circuit for an intelligent water dispenser proposed by the present utility model;

[0017] Figure 3 It is a circuit diagram of the connection between the leakage protector, diode D1, triode Q2 and the heating tube of the overheat protection circuit for an intelligent water dispenser proposed by the present utility model. Detailed Embodiment

[0018] Next, the technical solutions in the embodiments of the present utility model will be clearly and completely described in conjunction with the drawings in the embodiments of the present utility model. Obviously, the described embodiments are only a part of the embodiments of the present utility model, rather than all of the embodiments.

[0019] Refer to Figures 1-3 , an overheat protection circuit for an intelligent water dispenser, including a heating tube installed on the intelligent water dispenser. The heating tube includes a thermistor NTC and an overheat protection switch. The thermistor NTC is electrically connected to an overcurrent protection circuit and an MCU control circuit. The MCU control circuit is electrically connected to the overcurrent protection circuit. The MCU control circuit is electrically connected to a drive control circuit. The drive control circuit is electrically connected to a relay. The relay is electrically connected to the overheat protection switch;

[0020] The overcurrent protection circuit is electrically connected to a leakage protector. The leakage protector is electrically connected to the heating tube. The leakage protector is used to monitor the incoming and outgoing states of the current, judge its leakage situation, and turn off the power when leakage is detected to reduce the risk of electric shock;

[0021] The MCU controller includes a main control chip MCU;

[0022] Among them, the overcurrent protection circuit is used to monitor the current flowing through the circuit. When the current exceeds the set value, it automatically cuts off the power supply to prevent component damage caused by overload. The overcurrent protection circuit includes a triode Q1. One end of a resistor R2 and one end of a capacitor C2 are electrically connected to the base of the triode Q1. The other end of the capacitor C2 is electrically connected to one end of a resistor R1. The other end of the resistor R2 is electrically connected to the positive electrode of a diode D1 and one end of a capacitor C1. One end of the capacitor C1 is also electrically connected to the positive electrode of the diode D1. The other end of the capacitor C1 is electrically connected to the other end of the resistor R1. One end of a resistor R3 is electrically connected to the collector of the triode Q1. The other end of the resistor R3 is grounded. One end of a resistor R6 and one end of a resistor R5 are electrically connected to the emitter of the triode Q1. The other end of the resistor R6 is electrically connected to the other end of the resistor R1 and the other end of the capacitor C1. The other end of the resistor R5 is electrically connected to the emitter of a triode Q2. One end of a resistor R4 is electrically connected to the base of the triode Q2. The other end of the resistor R4 is electrically connected to the other end of the resistor R6, the other end of the resistor R1, and the other end of the capacitor C1. One end of a resistor R7 is electrically connected to the collector of the triode Q2. The other end of the resistor R7 is grounded. The other end of the resistor R7 is also electrically connected to pin 1 of the main control chip MCU. The leakage protector includes a comparator U1. Pin 2 of the comparator U1 is electrically connected to the supply voltage VCC and one end of a current transformer CT. The other end of the current transformer CT is electrically connected to one end of an adjustable resistor RL. The other end of the adjustable resistor RL is electrically connected to pin 3 of the comparator U1. Pin 4 of the comparator U1 is electrically connected to one end of an automatic power-off switch L1. The other end of the automatic power-off switch L1 is electrically connected to the negative electrode of the diode D1 and the base of the triode Q2;

[0023] An automatic power-off switch L2 is electrically connected between pin 4 of the comparator U1 and the heating tube. The automatic power-off switch L2 is used to control the connection between the heating tube and the leakage protector. Through the leakage protector and overcurrent protection circuit provided in the present utility model, leakage and overcurrent protection can be carried out during the overheat protection of the heating tube, improving the stability during the detection process and reducing the risks of short circuit and electric shock during the overheat protection process.

[0024] Working principle: When in use, when the thermistor NTC is working, a large amount of heat will be generated. At the same time, the MCU control circuit detects and calculates the resistance value of the thermistor NTC. When the MCU control circuit detects and calculates that the thermistor NTC is at the resistance value during normal operation, the MCU control circuit outputs a corresponding control signal, enabling the drive control circuit to drive and output a corresponding drive signal, and the moving contact of the relay is connected to the static contact, so that the heating tube works normally; when the heating tube has a water shortage or dry burning phenomenon, the temperature of the thermistor NTC exceeds the set normal operating temperature range. When the MCU control circuit detects and calculates that the resistance value of the thermistor NTC is abnormal, the MCU control circuit disconnects the drive signal through the drive control circuit, causing the relay to lose power. At the same time, the overheat protection switch disconnects the power supply, causing the heating tube to stop heating and dry burning. The specific overheat power-off principle has been mentioned in the patent with the application number: 201920099399.1, and will not be elaborated here;

[0025] During the overheat detection process, the leakage protector cooperates with the comparator U1 and the current transformer CT to detect the input current situation. When a leakage situation is detected, the automatic power-off switches L1 and L2 are disconnected, stopping the supply of voltage to the overcurrent protection circuit and the heating tube, thus achieving the effect of leakage protection;

[0026] When the voltage is normal and there is no leakage, the automatic power-off switches L1 and L2 are closed, and the leakage protector is connected to the heating tube and the overcurrent protection circuit. The current of the leakage protector is transmitted to the overcurrent protection circuit. The diode D1 rectifies the current. The rectified current is sequentially transmitted to the resistor R2, the capacitor C1, the capacitor C2, and the resistor R2 for discharging. At the same time, the triode Q1 conducts, and the triode Q2 cuts off. After the discharging is completed, both the diode D1 and the triode Q1 cut off, and the triode Q2 obtains a bias to conduct and supply power to the MCU control circuit. When the current is too large, the base voltage of the triode Q2 exceeds the voltage of the diode D1, causing the triode Q2 to conduct and making Q1 conduct. The base of the triode Q2 is reversely biased and cut off, stopping the output voltage, thus achieving the effect of automatic power-off protection when the current is too large, effectively avoiding the risk of short circuit caused by excessive current, improving the stability during the overheat detection process. By performing overcurrent and leakage protection during the overheat protection process, the stability during the detection process is improved, and the risks of short circuit and electric shock during the overheat protection process are reduced.

[0027] The above is only the preferred specific implementation manner of the present utility model, but the protection scope of the present utility model is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present utility model, according to the technical solution and the inventive concept of the present utility model, makes equivalent substitutions or changes, and all should be covered within the protection scope of the present utility model.

Claims

1. An overheat protection circuit for an intelligent water dispenser, including a heating tube installed on the intelligent water dispenser, the heating tube comprising a thermistor NTC and an overheat protection switch, characterized in that, The thermistor NTC is electrically connected to an overcurrent protection circuit and an MCU control circuit. The MCU control circuit is electrically connected to the overcurrent protection circuit. The MCU control circuit is electrically connected to a drive control circuit. The drive control circuit is electrically connected to a relay. The relay is electrically connected to an overheat protection switch. The overcurrent protection circuit is electrically connected to a leakage protector. The leakage protector is electrically connected to a heating tube. The MCU controller includes a main control chip MCU. The overcurrent protection circuit includes a triode Q1. One end of a resistor R2 and one end of a capacitor C2 are electrically connected to the base of the triode Q1. The other end of the capacitor C2 is electrically connected to one end of a resistor R1. The other end of the resistor R2 is electrically connected to the positive electrode of a diode D1 and one end of a capacitor C1. One end of the capacitor C1 is also electrically connected to the positive electrode of the diode D1. The other end of the capacitor C1 is electrically connected to the other end of the resistor R1. One end of a resistor R3 is electrically connected to the collector of the triode Q1. The other end of the resistor R3 is grounded. One end of a resistor R6 and one end of a resistor R5 are electrically connected to the emitter of the triode Q1. The other end of the resistor R6 is electrically connected to the other end of the resistor R1 and the other end of the capacitor C1. The other end of the resistor R5 is electrically connected to the emitter of a triode Q2. One end of a resistor R4 is electrically connected to the base of the triode Q2. The other end of the resistor R4 is electrically connected to the other end of the resistor R6, the other end of the resistor R1 and the other end of the capacitor C1. One end of a resistor R7 is electrically connected to the collector of the triode Q2. The other end of the resistor R7 is grounded. The other end of the resistor R7 is also electrically connected to pin 1 of the main control chip MCU.

2. The overheat protection circuit of an intelligent water dispenser according to claim 1, wherein The leakage protector includes a comparator U1. Pin 2 of the comparator U1 is electrically connected to a supply voltage VCC and one end of a current transformer CT. The other end of the current transformer CT is electrically connected to one end of an adjustable resistor RL. The other end of the adjustable resistor RL is electrically connected to pin 3 of the comparator U1. Pin 4 of the comparator U1 is electrically connected to one end of an automatic power-off switch L1. The other end of the automatic power-off switch L1 is electrically connected to the negative electrode of the diode D1 and the base of the triode Q2.

3. The overheat protection circuit of an intelligent water dispenser according to claim 2, characterized in that, An automatic power-off switch L2 is electrically connected between pin 4 of the comparator U1 and the heating tube. The automatic power-off switch L2 is used to control the connection between the heating tube and the leakage protector.

4. The overheat protection circuit of an intelligent water dispenser according to claim 1, characterized in that, The leakage protector is used to monitor the incoming and outgoing states of the current and judge its leakage situation.

5. The overheat protection circuit of an intelligent water dispenser according to claim 1, characterized in that, The overcurrent protection circuit is used to monitor the current flowing through the circuit. When the current exceeds the set value, the power supply is automatically cut off to prevent damage to components due to overload.

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