Gas valve control circuit

Abstract

The utility model discloses a gas valve control circuit which comprises a power supply, a single-chip microcomputer I / O, an NPN triode, a PNP triode, a field effect transistor and an electrolytic capacitor. The output end of the power supply is connected with an emitting electrode of the PNP triode, a base electrode of the PNP triode is connected with a collecting electrode of the NPN triode, and the collecting electrode of the PNP triode is connected with a grid electrode of the field effect transistor and the ground; the base electrode of the NPN triode is connected with the single-chip microcomputer I / O, and the emitter electrode of the NPN triode is connected with the ground. The source electrode of the field effect transistor is connected with the ground, and the drain electrode of the field effect transistor is connected with the electrolytic capacitor.

Description

A gas valve control circuit Technical Field

[0001] This utility model relates to the field of intelligent control technology in the home appliance industry, and in particular to a gas valve control circuit. Background Technology

[0002] With the rapid advancement of technology, smart home appliances are emerging in an endless stream. For example, integrated stoves require intelligent control of the natural gas valve to achieve a timed automatic shut-off function. Currently, the common method is DC power supply positive terminal → MOSFET → valve switch → DC power supply negative terminal, controlling the valve's on / off state by controlling the MOSFET's switching on and off. However, this method consumes a large amount of current from the DC power supply when the valve switch is on, affecting the stability of the DC power supply.

[0003] This utility model patent proposes a valve switch control circuit based on low cost and market demand. A small current from a DC power supply continuously charges an electrolytic capacitor until it is fully charged, at which point the charging stops. When needed, the electrolytic capacitor releases a large current to activate the valve switch, functioning similarly to a battery. It features reliability, low power supply impact, and high output current. Summary of the Invention

[0004] The purpose of this invention is to provide a gas valve control circuit to overcome the shortcomings of the prior art.

[0005] To achieve the above objectives, this utility model provides the following technical solution:

[0006] This application discloses a gas valve control circuit, including a power supply, a microcontroller I / O, an NPN transistor, a PNP transistor, a field-effect transistor, and an electrolytic capacitor; the output terminal of the power supply is connected to the emitter of the PNP transistor, the base of the PNP transistor is connected to the collector of the NPN transistor, and the collector of the PNP transistor is connected to the gate of the field-effect transistor and ground; the base of the NPN transistor is connected to the microcontroller I / O, and the emitter of the NPN transistor is connected to ground; the source of the field-effect transistor is connected to ground, and the drain of the field-effect transistor is connected to the electrolytic capacitor.

[0007] Preferably, a resistor R1 is connected between the emitter and base of the PNP transistor; a resistor R3 is provided between the base of the PNP transistor and the collector of the NPN transistor.

[0008] Preferably, resistor R1 is 10kΩ; resistor R3 is 10kΩ.

[0009] Preferably, the base of the NPN transistor is connected to the microcontroller I / O via resistor R5, resistor R6, and capacitor C1; the other end of resistor R6 and capacitor C1 is connected to ground.

[0010] Preferably, resistor R5 is 1kΩ, resistor R6 is 10KΩ, and capacitor C1 is 100nF.

[0011] Preferably, resistors R4 and R7 are connected between the collector of the PNP transistor and ground.

[0012] Preferably, resistor R4 is 1kΩ and resistor R7 is 10kΩ.

[0013] Preferably, a diode and a resistor R2 are connected between the power supply and the drain of the field-effect transistor, and a valve switch is provided between the source of the field-effect transistor and the ground.

[0014] Preferably, the resistor R2 is 1kΩ.

[0015] Preferably, the electrolytic capacitor is 2000uF.

[0016] The beneficial effects of this utility model are:

[0017] 1. By controlling the switching of the NPN transistor through the microcontroller's I / O, the switching of the PNP transistor can be indirectly controlled. This method can amplify the microcontroller's I / O voltage from 5V to 12V and has a stronger current driving capability.

[0018] 2. The switching on and off of a PNP transistor can control the switching on and off of a field-effect transistor. By increasing the driving voltage, the on-resistance of the field-effect transistor can be reduced, and the loss can be minimized.

[0019] 3. When the field-effect transistor is turned on, the electrolytic capacitor will release a large current through the valve switch. The electrolytic capacitor acts like a battery, reducing the impact on the DC power supply.

[0020] The features and advantages of this utility model will be described in detail through embodiments and accompanying drawings. Attached Figure Description

[0021] Figure 1 is a circuit diagram of a gas valve control circuit according to the present invention;

[0022] Figure 2 is a circuit state simulation diagram of Embodiment 1 of this utility model;

[0023] Figure 3 is a circuit state simulation diagram of Embodiment 2 of this utility model;

[0024] Figure 4 is a simulation diagram of the current through the valve switch of this utility model. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. However, it should be understood that the specific embodiments described herein are merely illustrative of the present utility model and are not intended to limit its scope. Furthermore, descriptions of well-known structures and technologies are omitted in the following description to avoid unnecessarily obscuring the concept of the present utility model.

[0026] Referring to Figure 1, this embodiment of the present invention provides a gas valve control circuit, including a power supply, a microcontroller I / O, an NPN transistor, a PNP transistor, a field-effect transistor (FET), and an electrolytic capacitor. The output terminal of the power supply is connected to the emitter of the PNP transistor, the base of the PNP transistor is connected to the collector of the NNP transistor, and the collector of the PNP transistor is connected to the gate of the FET and ground. The base of the NPN transistor is connected to the microcontroller I / O, and the emitter of the NPN transistor is connected to ground. The source of the FET is connected to ground, and the drain of the FET is connected to the electrolytic capacitor. The electrolytic capacitor is selected as 2000uF.

[0027] A resistor R1 is connected between the emitter and base of the PNP transistor; a resistor R3 is provided between the base of the PNP transistor and the collector of the NPN transistor. Specifically, resistor R1 is 10kΩ; resistor R3 is 10kΩ.

[0028] The base of the NPN transistor is connected to the microcontroller I / O via resistors R5 and R6, and capacitor C1; the other ends of resistors R6 and C1 are connected to ground. Specifically, resistor R5 is 1kΩ, resistor R6 is 10kΩ, and capacitor C1 is 100nF.

[0029] The collector of the PNP transistor is connected to ground by resistors R4 and R7. Specifically, resistor R4 is 1kΩ and resistor R7 is 10kΩ.

[0030] A diode and resistor R2 are connected between the power supply and the drain of the field-effect transistor; a valve switch is provided between the source of the field-effect transistor and ground. Specifically, resistor R2 is selected as 1kΩ.

[0031] The working principle is as follows:

[0032] When switch S1 is open, the voltage at point A is pulled down to a low level by resistors R5 and R6, and the base of NPN transistor Q1 is also at a low level, so Q1 cannot conduct. The base of PNP transistor Q2 is pulled up to 12V by resistor R1, so Q2 also cannot conduct. The voltage at point C is pulled down to a low level by resistor R7, so N-channel MOSFET Q3 also cannot conduct. That is, when point A is at a low level, Q1, Q2, and Q3 cannot conduct.

[0033] Referring to Figure 2, the current from the 12V power supply charges the electrolytic capacitor C2 through diode D1 and resistor R2. Diode D1 has a voltage drop of 0.7V, so the electrolytic capacitor C2 can be charged up to 11.3V.

[0034] When switch S1 is closed, the voltage at point A is pulled up to a high level of 5V, the base of NPN transistor Q1 is at a high level, and Q1 conducts. The voltage at point B is pulled down to a low level by transistor Q1, so PNP transistor Q2 also conducts. At this time, the current from the 12V power supply flows to ground through Q2, R4, and R7. Resistors R4 and R7 divide the voltage, so the voltage at point C is high. Since the voltage at point C is higher than the Vgs of MOSFET Q3, MOSFET Q3 conducts. That is, when point A is high, Q1, Q2, and Q3 can all conduct.

[0035] Referring to Figures 3 and 4, when the field-effect transistor Q3 is turned on, the electrolytic capacitor C2 releases current through Q3, the valve switch, and to ground, allowing the valve switch to operate.

[0036] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions or improvements made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A gas valve control circuit, characterized in that: The system includes a power supply, a microcontroller I / O pin, an NPN transistor, a PNP transistor, a field-effect transistor (FET), and an electrolytic capacitor. The output of the power supply is connected to the emitter of the PNP transistor, the base of the PNP transistor is connected to the collector of the NPN transistor, and the collector of the PNP transistor is connected to the gate of the FET and ground. The base of the NPN transistor is connected to the microcontroller I / O pin, and the emitter of the NPN transistor is connected to ground. The source of the FET is connected to ground, and the drain of the FET is connected to the electrolytic capacitor.

2. The gas valve control circuit as described in claim 1, characterized in that: A resistor R1 is connected between the emitter and base of the PNP transistor; a resistor R3 is provided between the base of the PNP transistor and the collector of the NPN transistor.

3. A gas valve control circuit as described in claim 2, characterized in that: The resistor R1 is selected as 10kΩ; the resistor R3 is selected as 10kΩ.

4. A gas valve control circuit as described in claim 1, characterized in that: The base of the NPN transistor is connected to the microcontroller I / O via resistors R5 and R6 and capacitor C1; the other ends of resistor R6 and capacitor C1 are connected to ground.

5. A gas valve control circuit as described in claim 4, characterized in that: The resistor R5 is 1kΩ, the resistor R6 is 10KΩ, and the capacitor C1 is 100nF.

6. A gas valve control circuit as described in claim 1, characterized in that: The collector of the PNP transistor is connected to ground by resistors R4 and R7.

7. A gas valve control circuit as described in claim 6, characterized in that: The R4 resistor is selected as 1kΩ and the R7 resistor is selected as 10kΩ.

8. A gas valve control circuit as described in claim 1, characterized in that: A diode and resistor R2 are connected between the power supply and the drain of the field-effect transistor; a valve switch is provided between the source of the field-effect transistor and the ground.

9. A gas valve control circuit as described in claim 8, characterized in that: The resistor R2 is selected as 1kΩ.

10. A gas valve control circuit as described in claim 1, characterized in that: The electrolytic capacitor used is 2000uF.

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