Intelligent control terminal for air conditioning system

Abstract

This invention relates to the field of air conditioning system technology and proposes an intelligent control terminal for an air conditioning system. The terminal includes a valve control circuit comprising switching transistors Q1 and Q4, resistors R4 and R2, switching transistors Q3 and Q2, and a solenoid valve coil L1. The control terminal of switching transistor Q1 is connected to the main control unit. The first terminal of switching transistor Q1 is connected to the control terminal of switching transistor Q2 through resistor R4. The first terminal of switching transistor Q1 is also connected to the first terminal of solenoid valve coil L1. The second terminal of switching transistor Q1 is grounded. The second terminal of solenoid valve coil L1 is connected to a 12V power supply. The second terminal of solenoid valve coil L1 is also connected to the first terminal of switching transistor Q2. The second terminal of switching transistor Q2 is connected to a 24V power supply. The control terminal of switching transistor Q2 is connected to the first terminal of switching transistor Q3. The control terminal of switching transistor Q3 is connected to the main control unit, and the second terminal of switching transistor Q3 is grounded. This technical solution solves the problem of high power consumption in existing valve control systems.

Description

Technical Field

[0001] This invention relates to the field of air conditioning system technology, specifically to an intelligent control terminal for an air conditioning system. Background Technology

[0002] A central air conditioning system consists of one or more cold / heat source systems and multiple air conditioning systems. Unlike traditional refrigerant-based air conditioners (such as stand-alone units or VRV systems), this system centrally processes air to achieve comfort requirements. It utilizes the principle of liquid vaporization refrigeration to provide the necessary cooling capacity to the air conditioning system. A central air conditioning system mainly consists of a main unit, refrigerant pipes, branch pipes, indoor units, a water tank, circulating water, and filters. The circulating water system is a crucial component of a central air conditioning system. The control valves used in the circulating water system, also known as regulating valves, are devices that adjust the flow rate of liquids or gases within the piping system. This adjustment is achieved by changing the opening degree of the control valves connected in series in the piping system, thereby altering the fluid resistance. With technological advancements, the opening degree of control valves used in circulating water systems is now mostly automatically controlled. However, existing valve control systems suffer from high power consumption, leading to significant waste of electrical resources. Summary of the Invention

[0003] This invention proposes an intelligent control terminal for air conditioning systems, which solves the problem of high power consumption in existing valve control systems.

[0004] The technical solution of the present invention is as follows:

[0005] An intelligent control terminal for an air conditioning system includes a main control unit and a valve control circuit. The valve control circuit is connected to the main control unit and includes a resistor R1, a switching transistor Q1, a resistor R7, a switching transistor Q4, a resistor R4, a resistor R2, a resistor R3, a switching transistor Q3, a resistor R5, a switching transistor Q2, and a solenoid valve coil L1.

[0006] The first end of resistor R1 is connected to the first output terminal of the main control unit, and the second end of resistor R1 is connected to the control terminal of switch Q1. The first end of switch Q1 is connected to the first end of resistor R3 through resistor R4. The first end of switch Q1 is connected to the first end of solenoid valve coil L1. The second end of switch Q1 is grounded through resistor R7. The second end of switch Q1 is connected to the control terminal of switch Q4. The first end of switch Q4 is connected to the control terminal of switch Q1, and the second end of switch Q4 is grounded.

[0007] The second terminal of the solenoid valve coil L1 is connected to a 12V power supply. The second terminal of the solenoid valve coil L1 is connected to the first terminal of the switching transistor Q2. The second terminal of the switching transistor Q2 is connected to a 24V power supply. The control terminal of the switching transistor Q2 is connected to the second terminal of the resistor R3.

[0008] The control terminal of the switching transistor Q3 is connected to the second output terminal of the main control unit through the resistor R5, the first terminal of the switching transistor Q3 is connected to the first terminal of the resistor R3 through the resistor R2, and the second terminal of the switching transistor Q3 is grounded.

[0009] Furthermore, the present invention also includes two driving circuits with identical circuit structures. Each of the driving circuits includes a driver U2, a resistor R9, a transistor Q5, and a transistor Q6. The first input terminal of the driver U2 is connected to a 15V power supply through the resistor R15. The second input terminal of the driver U2 is connected to the first output terminal of the main control unit. The output terminal of the driving circuit is connected to the base of the transistor Q6. The detection terminal of the driver U2 is connected to the first terminal of the switching transistor Q1. The base of the transistor Q6 is connected to the base of the transistor Q5. The emitter of the transistor Q6 is connected to the emitter of the transistor Q5. The collector of the transistor Q5 is connected to a 15V power supply. The first terminal of the transistor Q6 is connected to the first terminal of the resistor R1. The collector of the transistor Q6 is grounded.

[0010] Furthermore, any of the driving circuits described in this invention further includes a resistor R10, an optocoupler U1, and a resistor R8. The first end of the resistor R10 is connected to the first output terminal of the main control unit, the second end of the resistor R10 is connected to the first input terminal of the optocoupler U1, the second input terminal of the optocoupler U1 is grounded, the first output terminal of the optocoupler U1 is connected to a 15V power supply through the resistor R8, the first output terminal of the optocoupler U1 is connected to the second input terminal of the driver U2, and the second output terminal of the optocoupler U1 is grounded.

[0011] Furthermore, the present invention also includes a valve opening detection circuit, which includes an eddy current displacement sensor, resistors R15 and R16, operational amplifier U4, resistors R17 and R18, operational amplifier U5, and resistor R20. The first end of the eddy current displacement sensor coil L1 is connected to the output terminal of the signal generation circuit, and the second end of the eddy current displacement sensor coil L1 is grounded. The non-inverting input terminal of the operational amplifier U4 is connected to the first end of the eddy current displacement sensor coil L1 through the resistor R15, and the non-inverting input terminal of the operational amplifier U4 is connected to the signal generation circuit. The circuit is grounded through resistor R16. The output terminal of operational amplifier U4 is connected to the inverting input terminal of operational amplifier U4. The output terminal of operational amplifier U4 is connected to the non-inverting input terminal of operational amplifier U5. The inverting input terminal of operational amplifier U5 is grounded through resistor R18. The inverting input terminal of operational amplifier U5 is connected to the first terminal of the eddy current displacement sensor coil L1 through resistor R17. The output terminal of operational amplifier U5 is connected to the inverting input terminal of operational amplifier U5 through resistor R20. The output terminal of operational amplifier U5 is connected to the first input terminal of the main control unit.

[0012] Furthermore, the signal generation circuit described in this invention includes resistors R21 and R22, capacitor C5, resistor R27, capacitor C6, operational amplifier U6, resistor R26, diode D7, diode D8, resistor R23, and resistor R24. The non-inverting input terminal of operational amplifier U6 is connected to the first terminal of resistor R22 through resistor R21, the inverting input terminal of operational amplifier U6 is connected to the second terminal of resistor R22, and the output terminal of operational amplifier U6 is connected to the first terminal of resistor R27 through capacitor C6. The second end of resistor R27 is connected to the non-inverting input of operational amplifier U6. The output of operational amplifier U6 is connected to the first end of resistor R26 through resistor R23. The second end of resistor R26 is connected to the inverting input of operational amplifier U6. Resistor R24 ​​is connected in parallel across resistor R23. Diode D7 is connected in parallel across diode D23. Diode D8 is connected in inverting parallel across diode D7. The output of operational amplifier U6 is connected to the first end of the eddy current displacement sensor coil L1.

[0013] Furthermore, the present invention also includes a filtering and amplification circuit, which includes resistors R28 and R29, capacitors C7 and C8, resistors R30 and R31, operational amplifier U7, resistors R32, R33, and R34, and operational amplifier U8. The first end of resistor R28 is connected to the output terminal of operational amplifier U5. The second end of resistor R28 is connected to the inverting input terminal of operational amplifier U7 through capacitor C8. The second end of resistor R28 is grounded through resistor R29. The non-inverting input terminal of operational amplifier U7 is grounded through resistor R31. The output terminal of operational amplifier U7 is connected to the inverting input terminal of operational amplifier U7 through resistor R30. The output terminal of operational amplifier U7 is connected to the second end of resistor R28 through capacitor C7.

[0014] The output terminal of operational amplifier U7 is connected to the non-inverting input terminal of operational amplifier U8 through resistor R32, the inverting input terminal of operational amplifier U8 is grounded through resistor R33, the output terminal of operational amplifier U8 is connected to the inverting input terminal of operational amplifier U8 through resistor R34, and the output terminal of operational amplifier U8 is connected to the first input terminal of the main control unit.

[0015] Furthermore, the present invention also includes a temperature detection circuit, which includes a resistor R11, a Zener diode D6, a variable resistor RP1, a temperature sensor P1, a resistor R12, an operational amplifier U3, and a resistor R13. The first end of the resistor R11 is connected to a 5V power supply, the second end of the resistor R11 is connected to the cathode of the Zener diode D6, the anode of the Zener diode D6 is grounded, the cathode of the Zener diode D6 is connected to the inverting input terminal of the operational amplifier U3 through the variable resistor RP1, the non-inverting input terminal of the operational amplifier U3 is connected to the first terminal of the temperature sensor P1, the second terminal of the temperature sensor P1 is grounded, the inverting input terminal of the operational amplifier U3 is grounded through the resistor R12, the output terminal of the operational amplifier U3 is connected to the inverting input terminal of the operational amplifier U3 through the resistor R13, and the output terminal of the operational amplifier U3 is connected to the second input terminal of the main control unit.

[0016] The working principle and beneficial effects of this invention are as follows:

[0017] In this invention, the opening degree of the solenoid valve is adjusted by the valve control circuit, thereby realizing the automatic adjustment and control of the liquid flow rate in the pipeline.

[0018] Specifically, the working principle of the valve control circuit is as follows: When the solenoid valve starts, the main control unit outputs two PWM control signals with the same frequency and amplitude, which are applied to the control terminals of switching transistors Q1 and Q3 respectively. When the PWM control signal is low, switching transistors Q1 and Q3 are cut off, and no current flows through the solenoid valve coil L1, so the solenoid valve does not move. When the PWM control signal is high, switching transistors Q1 and Q3 are turned on, and a voltage is generated across resistor R2, so switching transistor Q2 is also turned on. At this time, the 24V power supply and the 12V power supply are simultaneously applied to the solenoid valve coil L1, and the solenoid valve begins to open. After a period of time, the opening degree of the solenoid valve reaches the set value, and the main control unit stops sending PWM control signals to the control terminal of switching transistor Q3. Switching transistor Q3 is cut off, and switching transistor Q2 is also cut off, so the 24V power supply stops supplying power to the solenoid valve coil L1. The main control unit continues to send PWM control signals to the control terminal of switching transistor Q1. At this time, only the 12V power supply supplies power to the solenoid valve coil L1, and the power supply can maintain the solenoid valve in the open state.

[0019] Switch Q4 and resistor R7 form a constant current circuit. Resistor R7 acts as a sampling resistor. When switch Q1 is turned on, current flows through resistor R7, generating a voltage across it. This voltage is applied to the control terminal of switch Q4. If the current flowing through solenoid coil L1 increases while the solenoid valve remains open, the voltage drop across resistor R7 increases, leading to a larger current at the control terminal of switch Q4. This, in turn, increases the current at the first terminal of switch Q4, pulling down the current at the control terminal of switch Q1 and reducing the current flowing through solenoid coil L1. Conversely, if the current flowing through solenoid coil L1 decreases, the voltage drop across resistor R7 decreases, reducing the current at the first terminal of switch Q4. This increases the current at the control terminal of switch Q1, increasing the current flowing through solenoid coil L1. Therefore, the constant current circuit ensures that the current flowing through solenoid coil L1 remains stable.

[0020] In this invention, when the solenoid valve is first started, both 24V and 12V power supplies can simultaneously power the solenoid valve coil L1, ensuring that the solenoid valve can open quickly. When the solenoid valve opens to a certain degree, only the 12V power supply powers the solenoid valve coil L1, allowing the power supply to maintain the solenoid valve in the open state. This avoids the solenoid valve being in a high-voltage state for a long time, reducing the power consumption of the solenoid valve and solving the problem of high power consumption in the valve control system in the prior art. The constant current circuit composed of the switching transistor Q4 and the resistor R7 ensures that the current flowing through the solenoid valve coil L1 remains stable when the solenoid valve is maintained in the open state, thus improving the service life of the solenoid valve coil L1.

[0021] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. Attached Figure Description

[0022] Figure 1This is a circuit diagram of the valve control circuit in this invention;

[0023] Figure 2 This is a circuit diagram of the driving circuit in this invention;

[0024] Figure 3 This is a circuit diagram of the valve opening detection circuit in this invention;

[0025] Figure 4 This is a circuit diagram of the signal generation circuit in this invention;

[0026] Figure 5 This is a circuit diagram of the filter amplifier circuit in this invention;

[0027] Figure 6 This is a circuit diagram of the temperature detection circuit in this invention. Detailed Implementation

[0028] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0029] Example 1

[0030] like Figure 1 As shown, this embodiment proposes an intelligent control terminal for an air conditioning system, including a main control unit and a valve control circuit. The valve control circuit is connected to the main control unit and includes a resistor R1, a switching transistor Q1, a resistor R7, a switching transistor Q4, a resistor R4, a resistor R2, a resistor R3, a switching transistor Q3, a resistor R5, a switching transistor Q2, and a solenoid valve coil L1. The first end of the resistor R1 is connected to the first output terminal of the main control unit, and the second end of the resistor R1 is connected to the control terminal of the switching transistor Q1. The first end of the switching transistor Q1 is connected to the first end of the resistor R3 through the resistor R4. The first end of the switching transistor Q1 is also connected to the first end of the solenoid valve coil L1. The second terminal of Q1 is grounded through resistor R7. The second terminal of switch Q1 is connected to the control terminal of switch Q4. The first terminal of switch Q4 is connected to the control terminal of switch Q1. The second terminal of switch Q4 is grounded. The second terminal of solenoid valve coil L1 is connected to a 12V power supply. The second terminal of solenoid valve coil L1 is connected to the first terminal of switch Q2. The second terminal of switch Q2 is connected to a 24V power supply. The control terminal of switch Q2 is connected to the second terminal of resistor R3. The control terminal of switch Q3 is connected to the second output terminal of the main control unit through resistor R5. The first terminal of switch Q3 is connected to the first terminal of resistor R3 through resistor R2. The second terminal of switch Q3 is grounded.

[0031] In this embodiment, a solenoid valve is used as a regulating valve in the circulating water system of the central air conditioning system. The valve control circuit is used to adjust the opening degree of the solenoid valve, thereby realizing the automatic adjustment and control of the liquid flow rate in the pipeline.

[0032] Specifically, the valve control circuit works as follows: When the solenoid valve starts, the main control unit outputs two PWM control signals with the same frequency and amplitude, which are applied to the control terminals of switching transistors Q1 and Q3 respectively. When the PWM control signal is low, switching transistors Q1 and Q3 are cut off, and no current flows through the solenoid valve coil L1, so the solenoid valve does not move. When the PWM control signal is high, switching transistors Q1 and Q3 are turned on, and a voltage is generated across resistor R2. Therefore, switching transistor Q2 is also turned on. At this time, the 24V and 12V power supplies are simultaneously applied to the solenoid valve coil L1, and then through switching transistors Q1 and resistor R2... Resistor R6 and resistor R7 form a circuit to ground, and the solenoid valve begins to open. After a period of time, the opening degree of the solenoid valve reaches the set value, and the main control unit stops sending PWM control signals to the control terminal of switch Q3. Switch Q3 is turned off, and switch Q2 is also turned off. Therefore, the 24V power supply stops supplying power to the solenoid valve coil L1. The main control unit continues to send PWM control signals to the control terminal of switch Q1. When the PWM control signal is high, the 12V power supply forms a circuit through the solenoid valve coil L1, switch Q1, resistor R6, and resistor R7. At this time, only the 12V power supply supplies power to the solenoid valve coil L1, and the power supply can maintain the solenoid valve in the open state.

[0033] The valve control circuit may age during long-term operation, or the current flowing through the solenoid valve coil L1 may become too large due to other reasons, which may lead to inaccurate control of the opening degree of the solenoid valve and affect the service life of the solenoid valve. Therefore, a constant current circuit is added in this embodiment, which consists of a switching transistor Q4 and a resistor R7.

[0034] In this circuit, resistor R7 serves as a sampling resistor. When switch Q1 is turned on, current flows through resistor R7, generating a voltage across it. This voltage is applied to the control terminal of switch Q4. When the current flowing through switch Q1 is stable, the voltage across resistor R7 remains constant, thus the current at the control terminal of switch Q1 remains constant, meaning the current at the first terminal of switch Q4 remains constant. If the current flowing through solenoid coil L1 increases while the solenoid valve remains open, the voltage drop across resistor R7 increases, leading to an increase in the current at the control terminal of switch Q4. This, in turn, increases the current at the first terminal of switch Q4, thereby lowering the current at the control terminal of switch Q1 and thus reducing the current flowing through solenoid coil L1. Conversely, if the current flowing through solenoid coil L1 decreases, the voltage drop across resistor R7 decreases, reducing the current at the first terminal of switch Q4. This increases the current at the control terminal of switch Q1, leading to an increase in the current flowing through solenoid coil L1. Therefore, the constant current circuit ensures that the current flowing through solenoid coil L1 remains stable, improving the control accuracy and lifespan of the solenoid valve.

[0035] In this embodiment, when the solenoid valve is first started, both the 24V and 12V power supplies can simultaneously power the solenoid valve coil L1, ensuring that the solenoid valve can open quickly. When the solenoid valve opens to a certain degree, only the 12V power supply powers the solenoid valve coil L1, which can keep the solenoid valve in the open state and avoid the solenoid valve being in a high voltage state for a long time, thus reducing the power consumption of the solenoid valve. The constant current circuit composed of the switching transistor Q4 and the resistor R7 ensures that the current flowing through the solenoid valve coil L1 is stable and constant when the solenoid valve is in the open state, thereby improving the service life of the solenoid valve coil L1.

[0036] Among them, capacitors C2 and C1 can improve the switching speed of switching transistors Q1 and Q3.

[0037] In this embodiment, an N-channel enhancement-mode field-effect transistor (EMF) is used as switch Q1, wherein the control terminal of switch Q1 is the gate of the N-channel EMF, the first terminal of switch Q1 is the drain of the N-channel EMF, and the second terminal of switch Q1 is the source of the N-channel EMF. An N-channel EMF is used as switch Q2, wherein the control terminal of switch Q2 is the gate of the N-channel EMF, the first terminal of switch Q2 is the source of the N-channel EMF, and the second terminal of switch Q2 is the drain of the N-channel EMF. An NPN transistor is used as switches Q3 and Q4, wherein the control terminal of switches Q3 and Q4 is the base of the NPN transistor, the first terminal of switches Q3 and Q4 is the collector of the NPN transistor, and the second terminal of switches Q3 and Q4 is the emitter of the NPN transistor.

[0038] like Figure 2As shown, this embodiment also includes two drive circuits with identical circuit structures. Each drive circuit includes a driver U2, a resistor R9, a transistor Q5, and a transistor Q6. The first input terminal of the driver U2 is connected to a 15V power supply through a resistor R15. The second input terminal of the driver U2 is connected to the first output terminal of the main control unit. The output terminal of the drive circuit is connected to the base of the transistor Q6. The detection terminal (VCin pin) of the driver U2 is connected to the first terminal of the switching transistor Q1. The base of the transistor Q6 is connected to the base of the transistor Q5. The emitter of the transistor Q6 is connected to the emitter of the transistor Q5. The collector of the transistor Q5 is connected to the 15V power supply. The first terminal of the transistor Q6 is connected to the first terminal of the resistor R1. The collector of the transistor Q6 is grounded.

[0039] In this embodiment, since the driving capability of the PWM control signal output by the main control unit is weak, it cannot directly drive the switching transistors Q1 and Q3. In order to improve the driving capability of the PWM control signal, this embodiment adds two driving circuits with the same circuit structure to improve the driving capability of the two PWM control signals respectively. Taking the driving circuit of the switching transistor Q1 as an example, the PWM control signal output by the main control unit is applied to the second input terminal of the driver U2. The driver U2 is used to improve the driving capability of the PWM control signal. The PWM control signal output by the driver U2 is sent to the base of transistors Q5 and Q6. Transistors Q5 and Q6 form a push-pull circuit to further improve the driving capability of the PWM control signal. Finally, the PWM control signal with improved driving capability is applied to the control terminal of the switching transistor Q1.

[0040] At the same time, the current at the first terminal of the switching transistor Q1 is sent to the detection terminal (VCin pin) of the driver U2. The detection terminal (VCin pin) of the driver U2 is used to detect the current at the first terminal of the switching transistor Q1. When the current flowing through the first terminal of the switching transistor Q1 is too high, it will cause damage to the switching transistor Q1. When the current at the first terminal of the switching transistor Q1 exceeds the set value, the driver U2 stops outputting the PWM control signal, thereby protecting the switching transistor Q1.

[0041] like Figure 2 As shown, any driving circuit in this embodiment further includes a resistor R10, an optocoupler U1, and a resistor R8. The first end of the resistor R10 is connected to the first output terminal of the main control unit, the second end of the resistor R10 is connected to the first input terminal of the optocoupler U1, the second input terminal of the optocoupler U1 is grounded, the first output terminal of the optocoupler U1 is connected to a 15V power supply through the resistor R8, the first output terminal of the optocoupler U1 is connected to the second input terminal of the driver U2, and the second output terminal of the optocoupler U1 is grounded.

[0042] In this embodiment, the amplitude of the PWM control signal output from the emitter of transistor Q6 is much larger than the amplitude of the PWM control signal output from the main control unit. During the switching process of the solenoid valve, the large amplitude PWM control signal may interfere with the main control unit, which can easily damage the main control unit. Therefore, in this embodiment, an optocoupler U1 is added between the main control unit and the driver U2. The optocoupler U1 can play a role in signal isolation, preventing mutual interference between the signals of the preceding and following stages and ensuring the normal operation of the circuit.

[0043] like Figure 3 As shown, this embodiment also includes a valve opening detection circuit. The valve opening detection circuit includes an eddy current displacement sensor, resistors R15 and R16, operational amplifier U4, resistors R17 and R18, operational amplifier U5, and resistor R20. The first end of the eddy current displacement sensor coil L1 is connected to the output terminal of the signal generation circuit, and the second end of the eddy current displacement sensor coil L1 is grounded. The non-inverting input terminal of operational amplifier U4 is connected to the first end of the eddy current displacement sensor coil L1 through resistor R15, and the non-inverting input terminal of operational amplifier U4 is grounded through resistor R16. The output terminal of operational amplifier U4 is connected to the inverting input terminal of operational amplifier U4, and the output terminal of operational amplifier U4 is connected to the non-inverting input terminal of operational amplifier U5. The inverting input terminal of operational amplifier U5 is grounded through resistor R18, and the inverting input terminal of operational amplifier U5 is connected to the first end of the eddy current displacement sensor coil L1 through resistor R17. The output terminal of operational amplifier U5 is connected to the inverting input terminal of operational amplifier U5 through resistor R20, and the output terminal of operational amplifier U5 is connected to the first input terminal of the main control unit.

[0044] In this embodiment, a valve opening detection circuit is set at the opening of the solenoid valve to detect the opening degree of the solenoid valve so as to accurately control the opening degree of the solenoid valve. An eddy current displacement sensor is used to detect the opening degree of the solenoid valve.

[0045] When detecting the opening degree of the solenoid valve, a high-frequency alternating current is generated by the signal generation circuit to excite the eddy current displacement sensor coil L1, thereby generating a high-frequency alternating magnetic field in the working area of ​​the eddy current displacement sensor. When the relative position between the eddy current displacement sensor and the metal object changes, the magnetic flux through the metal object changes, which induces a current on the surface of the metal object. The current flow lines close on the surface of the metal object on their own, which is called eddy current. The generation of eddy current inevitably consumes some magnetic field energy, thereby changing the impedance of the magnetic field generating coil. Through proper matching of the converter and the sensor, the change in distance is converted into a change in electrical quantity using the eddy current effect, thus completing the conversion between displacement and electrical quantity.

[0046] Specifically, the working principle of the valve opening detection circuit is as follows: The signal generation circuit generates a high-frequency alternating current to excite the eddy current displacement sensor coil L1. When the solenoid valve experiences displacement, the eddy current displacement sensor coil L1 generates an alternating electrical signal, which is sent to the main control unit. Since the main control unit cannot recognize negative voltage signals, it needs to convert the AC signal output by the eddy current displacement sensor coil L1 into a DC signal output. The AC signal generated by the eddy current displacement sensor coil L1 is divided by resistors R15 and R16 and then applied to the non-inverting input of operational amplifier U4. Resistors R15 and R16 have the same resistance. Operational amplifier U4 acts as a follower. When the voltage at the non-inverting input of operational amplifier U4 is greater than 0, the voltage at the output of operational amplifier U4 is half of the voltage at the first terminal of the eddy current displacement sensor coil L1. Operational amplifier U5 acts as a subtractor, ultimately making the output voltage of operational amplifier U5 equal to the voltage at the first terminal of the eddy current displacement sensor coil L1. When the voltage at the non-inverting input of operational amplifier U4 is less than 0, the output of operational amplifier U4 is 0. At this time, operational amplifier U5 acts as an inverter, and the output of operational amplifier U5 is opposite to the electrical signal at the first terminal of the eddy current displacement sensor coil L1. Finally, the DC signal output by operational amplifier U5 is sent to the main control unit.

[0047] like Figure 4 As shown, the signal generation circuit in this embodiment includes resistors R21 and R22, capacitor C5, resistor R27, capacitor C6, operational amplifier U6, resistor R26, diode D7, diode D8, resistor R23, and resistor R24. The non-inverting input of operational amplifier U6 is connected to the first end of resistor R22 through resistor R21, and the inverting input of operational amplifier U6 is connected to the second end of resistor R22. The output of operational amplifier U6 is connected to the first end of resistor R27 through capacitor C6, and the second end of resistor R27 is connected to the non-inverting input of operational amplifier U6. The output of operational amplifier U6 is connected to the first end of resistor R26 through resistor R23, and the second end of resistor R26 is connected to the inverting input of operational amplifier U6. Resistor R24 ​​is connected in parallel across resistor R23, diode D7 is connected in parallel across diode D23, and diode D8 is connected in inverting parallel across diode D7. The output of operational amplifier U6 is connected to the first end of the eddy current displacement sensor coil L1.

[0048] The signal generation circuit is used to generate AC excitation signals. Resistors R21, C5, R27, and C6 form a selection network to determine the oscillation frequency of the circuit, enabling the circuit to generate a single-frequency sinusoidal oscillation. Operational amplifier U6 forms an amplification circuit to ensure that the circuit can have a process from oscillation start-up to dynamic equilibrium, so that the circuit can obtain a certain amplitude output and realize energy control. Diodes D7 and D8 form an amplitude stabilization circuit to stabilize the amplitude of the output signal.

[0049] like Figure 5As shown, this embodiment also includes a filter amplifier circuit, which includes resistors R28 and R29, capacitors C7 and C8, resistors R30 and R31, operational amplifier U7, resistors R32, R33, and R34, and operational amplifier U8. The first end of resistor R28 is connected to the output terminal of operational amplifier U5, and the second end of resistor R28 is connected to the inverting input terminal of operational amplifier U7 through capacitor C8. The second end of resistor R28 is grounded through resistor R29. The non-inverting input terminal of operational amplifier U7 is grounded through resistor R31. The output terminal of operational amplifier U7 is connected to the inverting input terminal of operational amplifier U7 through resistor R30. The output terminal of operational amplifier U7 is connected to the second end of resistor R28 through capacitor C7. The output terminal of operational amplifier U7 is connected to the non-inverting input terminal of operational amplifier U8 through resistor R32. The inverting input terminal of operational amplifier U8 is grounded through resistor R33. The output terminal of operational amplifier U8 is connected to the inverting input terminal of operational amplifier U8 through resistor R34. The output terminal of operational amplifier U8 is connected to the first input terminal of the main control unit.

[0050] In this embodiment, the eddy current displacement sensor introduces some interference signals when detecting the valve opening of the solenoid valve. These signals will affect the detection accuracy of the valve opening. At the same time, the change in the electrical signal output by the eddy current displacement sensor is small and cannot be directly and effectively identified by the main control unit. Therefore, a filter amplification circuit is added between the operational amplifier U5 and the main control unit. Resistors R28 and R29, capacitors C7 and C8, resistors R30 and R31, and operational amplifier U7 constitute a bandpass filter circuit to filter out high-frequency pulses and noise signals in the signal. Resistors R32, R33, and R34, and operational amplifier U8 constitute an amplification circuit to amplify the filtered electrical signal before sending it to the main control unit.

[0051] like Figure 6 As shown, this embodiment also includes a temperature detection circuit, which includes a resistor R11, a Zener diode D6, a variable resistor RP1, a temperature sensor P1, a resistor R12, an operational amplifier U3, and a resistor R13. The first end of the resistor R11 is connected to a 5V power supply, and the second end of the resistor R11 is connected to the cathode of the Zener diode D6. The anode of the Zener diode D6 is grounded. The cathode of the Zener diode D6 is connected to the inverting input terminal of the operational amplifier U3 through the variable resistor RP1. The non-inverting input terminal of the operational amplifier U3 is connected to the first terminal of the temperature sensor P1, and the second terminal of the temperature sensor P1 is grounded. The inverting input terminal of the operational amplifier U3 is grounded through the resistor R12. The output terminal of the operational amplifier U3 is connected to the inverting input terminal of the operational amplifier U3 through the resistor R13. The output terminal of the operational amplifier U3 is connected to the second input terminal of the main control unit.

[0052] In summer, when using air conditioning, we often set the temperature too low. If the indoor temperature is too low, it can easily lead to catching a cold, which can cause joint pain over time and also easily trigger a cold. Therefore, this embodiment adds a temperature detection circuit to automatically adjust the air conditioning temperature according to the indoor temperature, so as to avoid the harm to the body caused by the air conditioning temperature being too low, and at the same time save electricity.

[0053] The working principle of the temperature detection circuit is as follows: Zener diode D6 provides a stable operating voltage for temperature sensor P1. Temperature sensor P1 is used to detect the indoor temperature and convert the temperature value into an electrical signal, which is sent to the non-inverting input of operational amplifier U3. The operational amplifier forms an amplification circuit. The electrical signal output by temperature sensor P1 is relatively weak, so it needs to be amplified by the amplification circuit. The amplified electrical signal is filtered by a low-pass filter circuit composed of resistor R14 and capacitor C4 before being sent to the main control unit.

[0054] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An intelligent control terminal for an air conditioning system, characterized in that, It includes a main control unit and a valve control circuit. The valve control circuit is connected to the main control unit. The valve control circuit includes a resistor R1, a switching transistor Q1, a resistor R7, a switching transistor Q4, a resistor R4, a resistor R2, a resistor R3, a switching transistor Q3, a resistor R5, a switching transistor Q2, and a solenoid valve coil L1. The first end of resistor R1 is connected to the first output terminal of the main control unit, the second end of resistor R1 is connected to the control terminal of switch Q1, the first end of switch Q1 is connected to the first end of resistor R3 through resistor R4, the first end of switch Q1 is connected to the first end of solenoid valve coil L1, the second end of switch Q1 is grounded through resistor R7, the second end of switch Q1 is connected to the control terminal of switch Q4, the first end of switch Q4 is connected to the control terminal of switch Q1, and the second end of switch Q4 is grounded. The constant current circuit formed by switch Q4 and resistor R7 ensures that the current flowing through solenoid valve coil L1 remains stable when the solenoid valve is kept in the open state. The second terminal of the solenoid valve coil L1 is connected to a 12V power supply. The second terminal of the solenoid valve coil L1 is connected to the first terminal of the switching transistor Q2. The second terminal of the switching transistor Q2 is connected to a 24V power supply. The control terminal of the switching transistor Q2 is connected to the second terminal of the resistor R3. The control terminal of the switching transistor Q3 is connected to the second output terminal of the main control unit through the resistor R5, the first terminal of the switching transistor Q3 is connected to the first terminal of the resistor R3 through the resistor R2, and the second terminal of the switching transistor Q3 is grounded. It also includes two drive circuits with the same circuit structure. Each of the drive circuits includes a driver U2, a resistor R9, a transistor Q5, and a transistor Q6. The first input terminal of the driver U2 is connected to a 15V power supply through the resistor R9. The second input terminal of the driver U2 is connected to the first output terminal of the main control unit. The output terminal of the drive circuit is connected to the base of the transistor Q6. The detection terminal of the driver U2 is connected to the first terminal of the switching transistor Q1. The base of the transistor Q6 is connected to the base of the transistor Q5. The emitter of the transistor Q6 is connected to the emitter of the transistor Q5. The collector of the transistor Q5 is connected to a 15V power supply. The first terminal of the transistor Q6 is connected to the first terminal of the resistor R1. The collector of the transistor Q6 is grounded. Any of the aforementioned driving circuits further includes a resistor R10, an optocoupler U1, and a resistor R8. The first end of the resistor R10 is connected to the first output terminal of the main control unit, the second end of the resistor R10 is connected to the first input terminal of the optocoupler U1, the second input terminal of the optocoupler U1 is grounded, the first output terminal of the optocoupler U1 is connected to a 15V power supply through the resistor R8, the first output terminal of the optocoupler U1 is connected to the second input terminal of the driver U2, and the second output terminal of the optocoupler U1 is grounded.

2. The intelligent control terminal for an air conditioning system according to claim 1, characterized in that, It also includes a valve opening detection circuit, which comprises an eddy current displacement sensor, resistors R15 and R16, operational amplifier U4, resistors R17 and R18, operational amplifier U5, and resistor R20. The first end of the eddy current displacement sensor coil L1 is connected to the output terminal of the signal generation circuit, and the second end of the eddy current displacement sensor coil L1 is grounded. The non-inverting input terminal of operational amplifier U4 is connected to the first end of the eddy current displacement sensor coil L1 through resistor R15, and the non-inverting input terminal of operational amplifier U4 is connected to the first end of the eddy current displacement sensor coil L1 through resistor R15. Resistor R16 is grounded. The output terminal of operational amplifier U4 is connected to the inverting input terminal of operational amplifier U4. The output terminal of operational amplifier U4 is connected to the non-inverting input terminal of operational amplifier U5. The inverting input terminal of operational amplifier U5 is grounded through resistor R18. The inverting input terminal of operational amplifier U5 is connected to the first terminal of the eddy current displacement sensor coil L1 through resistor R17. The output terminal of operational amplifier U5 is connected to the inverting input terminal of operational amplifier U5 through resistor R20. The output terminal of operational amplifier U5 is connected to the first input terminal of the main control unit.

3. The intelligent control terminal for an air conditioning system according to claim 2, characterized in that, The signal generation circuit includes resistors R21 and R22, capacitor C5, resistor R27, capacitor C6, operational amplifier U6, resistor R26, diode D7, diode D8, resistors R23, R24, and R25. The non-inverting input of operational amplifier U6 is connected to the first terminal of resistor R22 through resistor R21, and the inverting input of operational amplifier U6 is connected to the second terminal of resistor R22. The output of operational amplifier U6 is connected to the first terminal of resistor R27 through capacitor C6. The second terminal is connected to the non-inverting input terminal of the operational amplifier U6. The output terminal of the operational amplifier U6 is connected to the first terminal of the resistor R26 through the resistor R23. The second terminal of the resistor R26 is connected to the inverting input terminal of the operational amplifier U6. The resistor R24 ​​is connected in parallel across the resistor R23. The diode D7 is connected in series with the resistor R25 and then in parallel across the resistor R23. The diode D8 is connected in reverse parallel across the diode D7. The output terminal of the operational amplifier U6 is connected to the first terminal of the eddy current displacement sensor coil L1.

4. The intelligent control terminal for an air conditioning system according to claim 2, characterized in that, It also includes a filtering and amplification circuit, which comprises resistors R28 and R29, capacitors C7, C8, and C9, resistors R30 and R31, operational amplifier U7, resistors R32, R33, and R34, and operational amplifier U8. The first end of resistor R28 is connected to the output terminal of operational amplifier U5. The second end of resistor R28 is connected to the inverting input terminal of operational amplifier U7 through capacitor C8. The second end of resistor R28 is grounded through resistor R29. The non-inverting input terminal of operational amplifier U7 is grounded through resistor R31. The output terminal of operational amplifier U7 is connected to its inverting input terminal through resistor R30. The output terminal of operational amplifier U7 is connected to the second end of resistor R28 through capacitor C7. The output terminal of operational amplifier U7 is connected to the non-inverting input terminal of operational amplifier U8 through resistor R32. The inverting input terminal of operational amplifier U8 is grounded through resistor R33. The output terminal of operational amplifier U8 is connected to the inverting input terminal of operational amplifier U8 through resistor R34. The capacitor C9 is connected in parallel across resistor R34. The output terminal of operational amplifier U8 is connected to the first input terminal of the main control unit.

5. The intelligent control terminal for an air conditioning system according to claim 1, characterized in that, It also includes a temperature detection circuit, which comprises a resistor R11, a Zener diode D6, a variable resistor RP1, a temperature sensor P1, a resistor R12, an operational amplifier U3, a resistor R13, a resistor R14, and a capacitor C4. The first end of the resistor R11 is connected to a 5V power supply, and the second end of the resistor R11 is connected to the cathode of the Zener diode D6. The anode of the Zener diode D6 is grounded. The cathode of the Zener diode D6 is connected to the inverting input terminal of the operational amplifier U3 through the variable resistor RP1. The non-inverting input terminal of the operational amplifier U3 is connected to the first terminal of the temperature sensor P1, and the second terminal of the temperature sensor P1 is grounded. The inverting input terminal of the operational amplifier U3 is grounded through the resistor R12. The output terminal of the operational amplifier U3 is connected to the inverting input terminal of the operational amplifier U3 through the resistor R13. The output terminal of the operational amplifier U3 is connected to the first end of the resistor R14. The second end of the resistor R14 is connected to the second input terminal of the main control unit, and the second end of the resistor R14 is grounded through the capacitor C4.

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