Water temperature detection circuit of washing machine

Abstract

The utility model discloses a water temperature detection circuit of a washing machine, which comprises a temperature sensor connected with a water sump of the washing machine in a matching way, an MCU microcontroller, an analog converter ADC and a display, the temperature sensor is electrically connected with a signal conditioning circuit, the signal conditioning circuit is electrically connected with the analog converter ADC, and the display is electrically connected with the MCU microcontroller. The MCU microcontroller is electrically connected with the analog converter ADC and the display; the temperature sensor comprises a thermistor NTC connected with a washing machine water sump in a matched mode. And the MCU microcontroller comprises a control chip MCU (Microprogrammed Control Unit). According to the water temperature detection circuit, the burden of the analog converter ADC can be reduced by performing secondary amplification and multiple denoising on the signal transmitted by the thermistor NTC, so that the sampling frequency of the analog converter ADC is improved, the temperature value can be read more frequently, and the response time and the water temperature detection effect of the water temperature detection circuit can be remarkably improved.

Description

Technical Field

[0001] The utility model relates to the technical field of water temperature detection circuits, in particular to a water temperature detection circuit for a washing machine. Background Art

[0002] With the development of technology, users have put forward higher requirements for intelligent washing machines. In order to improve the use safety of washing machines, it is necessary for the water temperature detection circuit of the washing machine to detect the water temperature in the washing tub of the washing machine to reduce the impact caused by too high water temperature. The water temperature detection circuit in the prior art mainly consists of an MCU microcontroller, an analog-to-digital converter ADC, and a temperature sensor. The water temperature in the washing machine is detected by the temperature sensor and collected through the analog-to-digital converter ADC and transmitted to the MCU microcontroller for the control work of the washing machine;

[0003] In the water temperature detection circuit of the washing machine in the prior art, when detecting the water temperature, the method of directly converting the information collected by the temperature sensor through the analog-to-digital converter ADC may result in a relatively slow response time. In the case of rapid water temperature changes, the real-time water temperature may not be reflected in time, thereby affecting the water temperature detection effect and not meeting the use requirements. Considering the above situation, we have proposed a water temperature detection circuit for a washing machine. Summary of the Utility Model

[0004] The purpose of the utility model is to solve the disadvantages existing in the prior art, and a water temperature detection circuit for a washing machine is proposed.

[0005] In order to achieve the above purpose, the utility model adopts the following technical scheme:

[0006] A water temperature detection circuit for a washing machine includes a temperature sensor, an MCU microcontroller, an analog-to-digital converter ADC, and a display, which are cooperatively connected with the water storage bin of the washing machine. The temperature sensor is electrically connected to a signal conditioning circuit, the signal conditioning circuit is electrically connected to the analog-to-digital converter ADC, and the MCU microcontroller is electrically connected to the analog-to-digital converter ADC and the display;

[0007] The temperature sensor includes a thermistor NTC cooperatively connected with the water storage bin of the washing machine;

[0008] The MCU microcontroller includes a control chip MCU. One end of an indicator lamp LED is electrically connected to pin 4 of the control chip MCU, the other end of the indicator lamp LED is grounded, pin 4 of the control chip MCU is also electrically connected to the receiving end of the display, and pin 1 of the control chip MCU is electrically connected to a supply voltage VCC.

[0009] Preferably, the signal conditioning circuit includes an amplifier A1 and an amplifier A2. Pin 1 of the amplifier A1 is electrically connected to one end of a thermistor NTC. Pin 2 of the amplifier A1 and pin 2 of the amplifier A2 are both grounded. One end of the thermistor NTC is electrically connected to one end of a diode D1 and one end of a resistor R1. The other end of the diode D1 is grounded. One end of the resistor R1 is electrically connected to one end of an inductor L1. The other end of the resistor R1 is electrically connected to one end of a capacitor C1. The other end of the capacitor C1 is electrically connected to the other end of the inductor L1. The other end of the capacitor C1 is electrically connected to pin 3 of the amplifier A1 and pin 1 of the amplifier A2. Pin 3 of the amplifier A1 and pin 1 of the amplifier A2 are electrically connected. Pin 1 of the amplifier A2 is electrically connected to one end of a capacitor C2 and one end of a resistor R2. The other end of the capacitor C2 is electrically connected to one end of an inductor L2. The other end of the resistor R2 is electrically connected to the other end of the inductor L2 and pin 3 of the amplifier A2. Pin 3 of the amplifier A2 is electrically connected to one end of a resistor R4 and one end of a capacitor C3. The other end of the resistor R4 is grounded. The other end of the capacitor C3 is electrically connected to one end of a resistor R3. The other end of the resistor R3 is electrically connected to the input end of an analog-to-digital converter ADC. The output end of the analog-to-digital converter ADC is electrically connected to pin 3 of a control chip MCU.

[0010] Preferably, pin 2 of the control chip MCU is grounded, and the model of the control chip MCU is STM32.

[0011] Preferably, the resistor R1, the capacitor C1, and the inductor L1 form a first filter, and the resistor R2, the capacitor C2, and the inductor L2 form a second filter.

[0012] Preferably, the capacitor C3 is a decoupling capacitor for reducing noise in the circuit.

[0013] Preferably, both the amplifier A1 and the amplifier A2 are used to amplify the electrical signal output by the thermistor NTC, and the models of both the amplifier A1 and the amplifier A2 are LM358.

[0014] Preferably, the analog-to-digital converter ADC is used to convert an analog signal into a digital signal for processing by the MCU microcontroller.

[0015] Compared with the existing technology, the beneficial effects of the present utility model are as follows:

[0016] By means of secondary amplification and multiple noise reduction of the signal transmitted by the thermistor NTC, the present utility model can reduce the burden on the analog-to-digital converter ADC, thereby increasing the sampling frequency of the analog-to-digital converter ADC, enabling the temperature value to be read more frequently, and thus significantly improving the response time and the water temperature detection effect of the water temperature detection circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 The connection block diagram of a water temperature detection circuit for a washing machine proposed by the present utility model;

[0018] Figure 2 The circuit diagram of a water temperature detection circuit for a washing machine proposed by the present utility model. Specific embodiments

[0019] Next, the technical solutions in the embodiments of the present utility model will be clearly and completely described in conjunction with the accompanying 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 the embodiments.

[0020] Refer to Figure 1-2 , a water temperature detection circuit for a washing machine, including a temperature sensor, an MCU microcontroller, an analog-to-digital converter ADC, and a display, which are cooperatively connected with a water storage tank of the washing machine. The display is used to display the detected temperature value. The temperature sensor is electrically connected to a signal conditioning circuit, the signal conditioning circuit is electrically connected to the analog-to-digital converter ADC, and the MCU microcontroller is electrically connected to the analog-to-digital converter ADC and the display. The analog-to-digital converter ADC is used to convert an analog signal into a digital signal for the MCU microcontroller to process;

[0021] The temperature sensor includes a thermistor NTC cooperatively connected with the water storage tank of the washing machine;

[0022] The MCU microcontroller includes a control chip MCU. One end of pin 2 of the control chip MCU is grounded, the model of the control chip MCU is STM32. One end of pin 4 of the control chip MCU is electrically connected to an indicator LED, and the other end of the indicator LED is grounded. Pin 4 of the control chip MCU is also electrically connected to the receiving end of the display. The indicator LED is used to indicate and remind personnel. One end of pin 1 of the control chip MCU is electrically connected to a supply voltage VCC;

[0023] Among them, the signal conditioning circuit includes amplifier A1 and amplifier A2. Pin 1 of amplifier A1 is electrically connected to one end of the thermistor NTC. Pin 2 of amplifier A1 and pin 2 of amplifier A2 are both grounded. One end of the thermistor NTC is electrically connected to one end of diode D1 and one end of resistor R1. The other end of diode D1 is grounded. One end of resistor R1 is electrically connected to one end of inductor L1. The other end of resistor R1 is electrically connected to one end of capacitor C1. The other end of capacitor C1 is electrically connected to the other end of inductor L1. The other end of capacitor C1 is electrically connected to pin 3 of amplifier A1 and pin 1 of amplifier A2. Pin 3 of amplifier A1 and pin 1 of amplifier A2 are electrically connected. Pin 1 of amplifier A2 is electrically connected to one end of capacitor C2 and one end of resistor R2. The other end of capacitor C2 is electrically connected to one end of inductor L2. The other end of resistor R2 is electrically connected to the other end of inductor L2 and pin 3 of amplifier A2. Pin 3 of amplifier A2 is electrically connected to one end of resistor R4 and one end of capacitor C3. Capacitor C3 is a decoupling capacitor used to reduce noise in the circuit. The other end of resistor R4 is grounded. The other end of capacitor C3 is electrically connected to one end of resistor R3. Among them, resistor R1, capacitor C1 and inductor L1 form a first filter. Resistor R2, capacitor C2 and inductor L2 form a second filter. The other end of resistor R3 is electrically connected to the input end of the analog-to-digital converter ADC. The output end of the analog-to-digital converter ADC is electrically connected to pin 3 of the control chip MCU;

[0024] Among them, both amplifier A1 and amplifier A2 are used to amplify the electrical signal output by the thermistor NTC. The models of amplifier A1 and amplifier A2 are both LM358. By means of secondary amplification and multiple noise reduction of the signal transmitted by the thermistor NTC, the present invention can reduce the burden on the analog-to-digital converter ADC, thereby increasing the sampling frequency of the analog-to-digital converter ADC, enabling the temperature value to be read more frequently, and further significantly improving the response time and water temperature detection effect of the water temperature detection circuit.

[0025] Working principle: When in use, connect the thermistor NTC to the water sump of the washing machine. Detect the water temperature through the thermistor NTC and output a signal to be transmitted to the amplifier A1. The amplifier A1 amplifies the signal. At the same time, the signal passes through the first filter composed of the resistor R1, the capacitor C1, and the inductor L1. The first filter filters the signal to initially remove the noise in the signal. The initially amplified signal with noise removed passes through the amplifier A2. The amplifier A2 amplifies the signal for the second time. At the same time, the second filter composed of the capacitor C2, the inductor L2, and the resistor R2 further removes the noise from the signal. The signal after the second noise removal and amplification passes through the capacitor C3. The capacitor C3 removes the high-frequency noise in the signal. The noise-removed signal enters the analog-to-digital converter ADC. The analog-to-digital converter ADC collects the signal and converts it into a digital signal to be transmitted to the control chip MCU. The MCU microcontroller receives the digital signal, calculates according to the built-in thermometer, and judges the water temperature. If the water temperature is lower than the set value, the control chip MCU controls the indicator LED to light up to remind the person. By amplifying the signal detected by the thermistor NTC twice and removing the noise multiple times, the burden on the analog-to-digital converter ADC can be reduced, thereby increasing the sampling frequency of the analog-to-digital converter ADC, enabling the temperature value to be read more frequently, and thus significantly improving the response time of the water temperature detection circuit, thereby enhancing the water temperature detection effect.

[0026] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution of the present invention and its inventive concept, makes equivalent substitutions or changes, and all should be covered within the protection scope of the present invention.

Claims

1. A water temperature detection circuit for a washing machine, comprising a temperature sensor connected to a water tank of the washing machine, an MCU microcontroller, an analog converter ADC and a display, characterized in that: The temperature sensor is electrically connected to a signal conditioning circuit, the signal conditioning circuit is electrically connected to an analog converter ADC, and the MCU microcontroller is electrically connected to the analog converter ADC and a display; The temperature sensor includes a thermistor NTC connected to the washing machine water tank; The MCU microcontroller includes a control chip MCU, wherein pin 4 of the control chip MCU is electrically connected to one end of an indicator light LED, and the other end of the indicator light LED is grounded. Pin 4 of the control chip MCU is also electrically connected to a receiving end of the display, and pin 1 of the control chip MCU is electrically connected to a power supply voltage VCC.

2. A water temperature detection circuit for a washing machine according to claim 1, characterized in that: The signal conditioning circuit includes an amplifier A1 and an amplifier A2, wherein a pin 1 of the amplifier A1 is electrically connected to one end of a thermistor NTC, a pin 2 of the amplifier A1 and a pin 2 of the amplifier A2 are both grounded, one end of the thermistor NTC is electrically connected to one end of a diode D1 and one end of a resistor R1, the other end of the diode D1 is grounded, one end of the resistor R1 is electrically connected to one end of an inductor L1, the other end of the resistor R1 is electrically connected to one end of a capacitor C1, the other end of the capacitor C1 is electrically connected to the other end of the inductor L1, the other end of the capacitor C1 is electrically connected to a pin 3 of the amplifier A1 and a pin 1 of the amplifier A2, and the pin 2 of the amplifier A1 is electrically connected to the pin 3 of the amplifier A1 and the pin 1 of the amplifier A2. Pin 3 is electrically connected to pin 1 of amplifier A2, pin 1 of amplifier A2 is electrically connected to one end of capacitor C2 and one end of resistor R2, the other end of capacitor C2 is electrically connected to one end of inductor L2, the other end of resistor R2 and the other end of inductor L2 are electrically connected to pin 3 of amplifier A2, pin 3 of amplifier A2 is electrically connected to one end of resistor R4 and one end of capacitor C3, the other end of resistor R4 is grounded, the other end of capacitor C3 is electrically connected to one end of resistor R3, the other end of resistor R3 is electrically connected to the input end of analog converter ADC, and the output end of analog converter ADC is electrically connected to pin 3 of control chip MCU.

3. A water temperature detection circuit for a washing machine according to claim 1, characterized in that: Pin 2 of the control chip MCU is grounded, and the model of the control chip MCU is STM32.

4. A water temperature detection circuit for a washing machine according to claim 2, characterized in that: The resistor R1, the capacitor C1 and the inductor L1 form a first filter, and the resistor R2, the capacitor C2 and the inductor L2 form a second filter.

5. A water temperature detection circuit for a washing machine according to claim 2, characterized in that: The capacitor C3 is a decoupling capacitor used to reduce noise in the circuit.

6. A water temperature detection circuit for a washing machine according to claim 2, characterized in that: The amplifier A1 and the amplifier A2 are both used to amplify the electrical signal output by the thermistor NTC, and the models of the amplifier A1 and the amplifier A2 are both LM358.

7. A water temperature detection circuit for a washing machine according to claim 1, characterized in that: The analog converter ADC is used to convert analog signals into digital signals for processing by the MCU microcontroller.

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