Bipolar driving circuit for liquid level detection of washing machine

Abstract

The utility model relates to the technical field of washing machine liquid level detection, in particular to a bipolar driving circuit for washing machine liquid level detection, which comprises an H-bridge circuit and a chip U1, M INA on a pin 1 and M INB on a pin 3 of the chip U1 are used as driving square wave output, a detected liquid port is connected with a liquid level detection cylinder, and the liquid level detection cylinder is connected with the H-bridge circuit. A liquid level probe is slidably arranged in the liquid level detection cylinder, a magnetic ring is arranged on the outer side face of the liquid level detection cylinder, and a pressure sensor is arranged at the bottom of the liquid level probe. According to the utility model, the bipolar driving circuit is adopted, and the common end electrode and the detection end electrode are driven by periodic electric signals to alternately serve as a cathode and an anode, so that the problem of electrode polarization is improved to a great extent, the resistance value of detected liquid is not sensitive to change within a certain range, and the water quality difference can be well solved; the sampling deviation caused by the difference of detergents can be well eliminated, and misjudgment caused by foam and residual water on the wall can be well eliminated.

Description

TECHNICAL FIELD

[0001] The utility model relates to a kind of bipolar drive circuit, in particular to a kind of bipolar drive circuit of washing machine liquid level detection, belong to washing machine liquid level detection technical field. BACKGROUND

[0002] For full-automatic washing machine, especially the water level and liquid detergent liquid level detection of desktop type full-automatic (drum) washing machine, the current industry mostly adopts electrode type detection system, its principle mainly includes public end electrode and one or more detection end electrodes arranged at target liquid level, in general, public end electrode is detection negative pole (logic low level), and detection end electrode is pulled to system logic high level by specific resistance sampling resistor. Different from the different voltage signals of sampling detection end electrode and data filtering processing, so that the system can detect the change of liquid level, to realize the monitoring and control of liquid level.

[0003] In the existing various liquid level detection systems, due to the difference of liquid resistance value caused by different components contained in liquid, the anti-interference performance of the voltage signal is poor, and the liquid level detection system is easily affected by environmental noise, electromagnetic interference and impurities mixed in liquid, so that the data is easily distorted, the accuracy of data acquisition of detection end is affected, and the reliability and accuracy of the system are reduced. In addition, this method needs to select electrode materials with excellent conductivity, such as copper electrode and stainless steel electrode. These electrode materials are easily adsorbed by contaminated medium or electrolytic corrosion of electrode itself in liquid with corrosion or high impurity content, which causes certain deviation of detection end signal sampling, and is not reliable in heavily polluted liquid. Therefore, a detection method with strong corrosion resistance and accurate liquid level signal detection is very important. CONTENT OF UTILITY MODEL

[0004] In view of the deficiencies of prior art, the utility model provides a kind of bipolar drive circuit of washing machine liquid level detection, which adopts bipolar drive circuit, public end electrode and detection end electrode are driven by periodic electric signal, and alternately serve as cathode and anode, thereby greatly improving electrode polarization problem, and the resistance value of measured liquid is not sensitive to change within a certain range, so that sampling deviation caused by water quality difference and washing agent difference can be well solved, and false judgment caused by foam and wall residual water can be well excluded.

[0005] The utility model solves the technical problems above, and the technical scheme adopted by the utility model is as follows:

[0006] A bipolar driving circuit for liquid level detection of a washing machine, comprising an H-bridge circuit and a chip U1, wherein MINA on pin 1 and MINB on pin 3 of the chip U1 are used as driving square wave output;

[0007] A measured liquid port is electrically connected to pin 6 and pin 4 of the chip U1, a liquid level detection cylinder is connected to the measured liquid port, a liquid level detection needle is slidably arranged in the liquid level detection cylinder, the liquid level detection cylinder and the liquid level detection needle are made of titanium metal, a magnetic ring is fixedly arranged on the outer side of the liquid level detection cylinder, and a pressure sensor is fixedly arranged on the bottom of the liquid level detection needle.

[0008] Further, pin 3 of the H-bridge circuit is connected with a port AD through a resistor R1, and the port AD and the resistor R1 are grounded through a capacitor C1.

[0009] Further, a resistor R2 is connected between pin 4 of the chip U1 and the measured liquid port.

[0010] Further, a 5V voltage is connected to pin 5 of the chip U1 and grounded through a capacitor C2.

[0011] Further, pin 2 of the chip U1 is grounded.

[0012] Further, a controller is connected to the upper end of the liquid level detection needle, a metal wire is electrically connected to the pressure sensor, and the metal wire is electrically connected to the controller.

[0013] Further, a tetrafluoro insulating material is fixedly connected to the upper end of the liquid level detection needle, a threaded fixing head is fixedly connected to the upper end of the tetrafluoro insulating material, and the threaded fixing head is fixedly connected to the controller.

[0014] Further, a connecting piece is connected to the controller, and a waterproof joint is connected to the connecting piece.

[0015] 1. The bipolar driving circuit is adopted, the common electrode and the detection electrode are alternately used as cathode and anode under the driving of the periodic electric signal, so that the electrode polarization problem is improved to a great extent, the resistance of the measured liquid is not sensitive to the change within a certain range, therefore, the sampling deviation caused by the difference in water quality and the difference in detergent can be well solved, and the misjudgment caused by the foam and the residual water on the wall can be well eliminated.

[0016] 2. The conductivity of the liquid level detection cylinder and liquid level detection needle changes little, which can effectively solve the interference in the presence of water vapor and foam, thus optimizing the water level detection technology. Due to the good corrosion resistance of the liquid level detection cylinder and liquid level detection needle, the service life can be extended and the application range can be expanded. It can remain stable in harsh environments such as acids, alkalis, and salts, and is not easy to corrode and rust. The magnetic ring plays a certain role in magnetic isolation, which greatly improves the system's life cycle and stability. Attached Figure Description

[0017] Figure 1 This is a perspective view of the present utility model;

[0018] Figure 2 This is the circuit diagram of this utility model;

[0019] Figure 3 This is a partial structural diagram of the present invention.

[0020] In the diagram, 1. Liquid level detection cylinder; 2. Liquid level detection needle; 3. PTFE insulation material; 4. Threaded fixing head; 5. Controller; 6. Connector; 7. Waterproof connector; 8. Pressure sensor; 9. Metal wire; 10. Magnetic ring. Detailed Implementation

[0021] The following will describe in detail the implementation of this application with reference to the accompanying drawings and specific embodiments, so that the implementation process of how this application uses technical means to solve technical problems and achieve technical effects can be fully understood and implemented accordingly.

[0022] like Figures 1-3 As shown, the bipolar drive circuit for washing machine liquid level detection provided in this embodiment includes an H-bridge circuit and a chip U1, with MINA on pin 1 and MINA on pin 3 of chip U1. The INB acts as the driver for the square wave output. Pins 6 and 4 of the chip U1 are electrically connected to the liquid being measured port, which is connected to a liquid level detection cylinder 1. A liquid level detection needle 2 is slidably mounted inside the liquid level detection cylinder 1. Both the liquid level detection cylinder 1 and the liquid level detection needle 2 are made of titanium. A magnetic ring 10 is fixedly mounted on the outer surface of the liquid level detection cylinder 1, and a pressure sensor 8 is fixedly mounted on the bottom of the liquid level detection needle 2. The conductivity of the liquid level detection cylinder 1 and the liquid level detection needle 2 changes little, effectively mitigating interference in the presence of water vapor and foam, thus optimizing water level detection technology. Because the liquid level detection cylinder 1 and the liquid level detection needle 2 have good corrosion resistance, their lifespan is extended, expanding their application range. They remain stable in harsh environments such as acids, alkalis, and salts, and are not easily corroded or rusted. The magnetic ring 10 provides a certain degree of magnetic shielding, greatly improving the system's lifespan and stability. The liquid level detection cylinder 1 and the liquid level detection needle 2 have excellent biological stability and will not produce harmful substances when used in a washing machine system, making the washing machine safer.

[0023] On the circuit, compared with the existing single polarity voltage division circuit structure, the liquid level sampling system adopts a bipolar drive circuit. The common electrode and the detection electrode are driven by a periodic electrical signal and alternately serve as cathode and anode, thereby greatly improving the electrode polarization problem. The sampling circuit uses a low-frequency square wave signal for driving. For different liquid levels and measured liquid substances, the frequency of the liquid level signal is the same as that of the driving signal, but the phase and amplitude are uniquely corresponding to the actual conditions. In each driving waveform period, the liquid level signal is sampled by an ADC and subjected to necessary digital filtering processing, thereby obtaining the corresponding sampling waveform. By comparing the driving waveform and the sampling waveform, the liquid level can be accurately determined. Through a large number of experiments, it is found that the improved scheme is not sensitive to the resistance change of the measured liquid within a certain range, and thus can well solve the sampling deviation caused by water quality difference and detergent difference, and can also well eliminate the misjudgment caused by foam and wall-hanging residual water.

[0024] Pin 3 of the H-bridge circuit is connected with port AD through resistor R1. Port AD and resistor R1 are grounded through capacitor C1. The bipolar driving mode of the H-bridge circuit and the chip U1 sampling electrode effectively improves the electrode polarization problem. The phase and amplitude combination method is adopted in the software, which greatly improves the accuracy and stability of the liquid level determination.

[0025] Further, as shown in Figure 2 and Figure 3 , a resistor R2 is connected between pin 4 of the chip U1 and the measured liquid port. In the series circuit, the resistor can distribute the voltage. According to Ohm's law, the voltage across the resistor R2 is proportional to its resistance R2 value. Therefore, by adjusting the resistance of the resistor R2, the voltage across the resistor can be controlled, thereby achieving voltage distribution in the circuit and improving the safety of the circuit.

[0026] Pin 2 of the chip U1 is grounded, and pin 5 of the chip U1 is connected with a 5V voltage and grounded through capacitor C2. Capacitor C2 forms a low-resistance path for alternating current signals, allowing high-frequency alternating current signals to be discharged to ground through the capacitor, thereby playing a filtering role. Capacitor C2 can easily interfere with the surrounding circuit, causing electronic devices to be unstable or even fail, and improving the stability of the circuit.

[0027] The upper end of the liquid level detection needle 2 is connected with a controller 5, and the pressure sensor 8 is electrically connected with a metal wire 9. The metal wire 9 is electrically connected with the controller 5. The pressure sensor 8 is arranged at the bottom of the liquid level detection needle 2 and can detect the depth of the liquid through the change of the depth. The liquid level detection needle 2 and the liquid level detection cylinder 1 are detected at the same time, greatly improving the detection accuracy and flexibility.

[0028] Further, as shown in Figure 1As shown, the upper end of the liquid level detection needle 2 is fixedly connected with a Teflon insulating material 3, the upper end of the Teflon insulating material 3 is fixedly connected with a threaded fixing head 4, the threaded fixing head 4 is fixedly connected with a controller 5, the controller 5 is connected with a connecting piece 6, and the connecting piece 6 is connected with a waterproof joint 7. The Teflon insulating material 3 is used to insulate the liquid level detection cylinder 1 and the liquid level detection needle 2, and the threaded fixing head 4 is used to fix the liquid level detection cylinder 1 and the liquid level detection needle 2. The waterproof joint 7 on the connecting piece 6 is connected, and the structure is simple, improving the convenience of use.

[0029] As shown in the figure, Figures 1-3 The principle of the bipolar driving circuit for the liquid level detection of the washing machine provided by the embodiment is as follows:

[0030] The conductivity of the liquid level detection cylinder 1 and the liquid level detection needle 2 changes little, and interference can be well solved when there is water vapor and foam, and the water level detection technology is optimized. Since the liquid level detection cylinder 1 and the liquid level detection needle 2 have good corrosion resistance and can be extended, the range of use is improved. They can remain stable in harsh environments such as acid, alkali, and salt, and are not prone to corrosion and rust. The magnetic ring 10 plays a certain magnetic shielding role, greatly improving the service life and stability of the system. The liquid level detection cylinder 1 and the liquid level detection needle 2 have excellent biological stability and will not produce harmful substances when used in the washing machine system, making the washing machine more secure.

[0031] On the circuit, compared with the existing unipolar voltage division circuit structure, the liquid level sampling system adopts a bipolar driving circuit. The common electrode and the detection electrode alternately act as the cathode and the anode under the driving of the periodic electric signal, thereby greatly improving the electrode polarization problem. The sampling circuit uses a low-frequency square wave signal for driving. For different liquid levels and measured liquid substances, the frequency of the liquid level signal is the same as that of the driving signal, but the phase and amplitude are uniquely corresponding to the actual conditions. In each driving waveform period, the liquid level signal is sampled by the ADC, and necessary digital filtering processing is performed, so as to obtain the corresponding sampling waveform. By comparing the driving waveform and the sampling waveform, the liquid level can be accurately judged. Through a large number of experiments, it is found that the improved scheme is not sensitive to the change of the resistance of the measured liquid within a certain range, and therefore can well solve the sampling deviation caused by water quality difference and detergent difference, and can also well exclude the misjudgment caused by foam and wall-hanging residual water.

[0032] The pin 3 of the H-bridge circuit is connected with a port AD through a resistor R1, and the port AD and the resistor R1 are grounded through a capacitor C1. The bipolar driving mode of the H-bridge circuit and the chip U1 sampling electrode effectively improves the electrode polarization problem itself. On the software, the phase and amplitude combination mode is adopted, which greatly improves the accuracy and stability of the liquid level judgment.

[0033] The above description shows and describes the preferred embodiments of the present application, it should be understood that the present application is not limited to the forms disclosed herein, and the changes and modifications made by those skilled in the art without departing from the spirit and scope of the present application should be within the scope of protection of the claims of the present application.

Claims

1. A bipolar driving circuit for liquid level detection of a washing machine, comprising an H-bridge circuit and a chip U1, characterized in that, The MINA on the pin 1 of the chip U1 and the MINB on the pin 3 are used as driving square wave output; The pin 6 and the pin 4 of the chip U1 are electrically connected with a measured liquid port, the measured liquid port is connected with a liquid level detection cylinder (1), a liquid level detection needle (2) is slidably arranged in the liquid level detection cylinder (1), the liquid level detection cylinder (1) and the liquid level detection needle (2) are made of titanium metal material, a magnetic ring (10) is fixedly arranged on the outer side of the liquid level detection cylinder (1), and a pressure sensor (8) is fixedly arranged on the bottom of the liquid level detection needle (2).

2. A bipolar drive circuit for liquid level detection in a washing machine as claimed in claim 1, characterized in that: The pin 3 of the H bridge circuit is connected with a port AD through a resistor R1, and the port AD and the resistor R1 are grounded through a capacitor C1.

3. A bipolar drive circuit for liquid level detection in a washing machine as claimed in claim 1, characterized in that: The pin 4 of the chip U1 is connected with the measured liquid port through a resistor R2.

4. The bipolar drive circuit for liquid level detection of a washing machine according to claim 1, characterized in that: The pin 5 of the chip U1 is connected with a 5V voltage and grounded through a capacitor C2.

5. The bipolar drive circuit for liquid level detection of a washing machine according to claim 1, wherein: The pin 2 of the chip U1 is grounded.

6. A bipolar drive circuit for a liquid level probe of a washing machine as claimed in claim 1, characterized in that: The upper end of the liquid level detection needle (2) is connected with a controller (5), the pressure sensor (8) is electrically connected with a metal wire (9), and the metal wire (9) is electrically connected with the controller (5).

7. A bipolar drive circuit for a liquid level probe of a washing machine as claimed in claim 6, characterized in that: The upper end of the liquid level detection needle (2) is fixedly connected with a tetrafluoro insulating material (3), the upper end of the tetrafluoro insulating material (3) is fixedly connected with a threaded fixing head (4), and the threaded fixing head (4) is fixedly connected with the controller (5).

8. A bipolar drive circuit for a liquid level probe of a washing machine as claimed in claim 7, characterized in that: The controller (5) is connected with a connecting piece (6), and the connecting piece (6) is connected with a waterproof joint (7).

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