A washing machine water level detection circuit

Abstract

The utility model relates to a washing machine control technical field, concretely provides a kind of washing machine water level detection circuit, including the public end probe being arranged in the interior of washing machine water tank, low water level detection probe and high water level detection probe;The detection circuit further includes switching unit, first path signal acquisition unit, second path signal acquisition unit, switching unit is used to provide detection voltage for the public end probe according to the on-off of control signal, first path signal acquisition unit is used to collect the water flood signal of low water level detection probe, and second path signal acquisition unit is used to collect the water flood signal of high water level detection probe;The utility model adopts probe type detection circuit, completely saves the complex mechanical pressure transmission structure, to have the outstanding advantages of structure simplification, small and exquisite, high reliability;Meanwhile, the circuit is only made of basic electronic components, not only greatly reduces cost, but also realizes faster response speed and more convenient maintenance diagnosis.

Description

Technical Field

[0001] This utility model relates to the field of washing machine control technology, specifically to a washing machine water level detection circuit. Background Technology

[0002] In the 21st century, drum washing machines and top-loading washing machines have become indispensable large appliances in every household. In the field of washing machine control technology, water level detection is a key function to ensure precise water level control during the washing process. Traditional washing machines widely use resonant water level sensors, which rely on water pressure to transmit gas, triggering a rubber diaphragm to control the switch action. This method has the following significant drawbacks: 1. Resonant water level sensors need to transmit pressure through external components such as conduits, involving multiple media including gas and diaphragms, resulting in complex mechanical structures, inconvenient disassembly and assembly, and a high failure rate.

[0003] 2. Resonant water level sensors are relatively large and require additional space to install conduits and diaphragm assemblies, making them difficult to fit into the internal layout of compact washing machines. Utility Model Content

[0004] In view of the shortcomings of the prior art described above, the purpose of this utility model is to provide a washing machine water level detection circuit to solve the problems of complex mechanical structure and large size of the existing resonant water level sensor for water level detection.

[0005] To achieve the above and other related objectives, this utility model provides a washing machine water level detection circuit, including a common terminal probe, a low water level detection probe, and a high water level detection probe disposed inside the water tank of the washing machine. The detection circuit further includes: The switching unit uses a transistor Q1, with the base of transistor Q1 connected to the control signal terminal, the emitter connected to the power supply, and the collector connected to the common terminal probe. The switching unit is used to provide a detection voltage to the common terminal probe according to the on / off state of the control signal. The first signal acquisition unit uses a pull-down resistor R4. One end of the pull-down resistor R4 is connected to the low water level detection probe, and the other end is grounded. A signal output terminal WL1_DET1 is led out from the connection point between the pull-down resistor R4 and the low water level detection probe. The first signal acquisition unit is used to acquire the flooding signal of the low water level detection probe. The second signal acquisition unit uses a pull-down resistor R8. One end of the pull-down resistor R8 is connected to the high water level detection probe, and the other end is grounded. A signal output terminal WL1_DET2 is led out from the connection point between the pull-down resistor R8 and the high water level detection probe. The second signal acquisition unit is used to acquire the flooding signal of the high water level detection probe.

[0006] In one embodiment of the present invention, a resistor R5 is connected to the base of the transistor Q1, and a resistor R3 is connected in parallel between the base and emitter of the transistor Q1.

[0007] In one embodiment of the present invention, a resistor R2 is also connected at the connection point between the pull-down resistor R4 and the low water level detection probe, and the other end of the resistor R2 is connected to the collector of the transistor Q1.

[0008] In one embodiment of this utility model, a resistor R7 is also connected at the connection point between the pull-down resistor R8 and the high water level detection probe 3#, and the other end of the resistor R7 is connected to the collector of the transistor Q1.

[0009] In one embodiment of the present invention, the first signal acquisition unit integrates a first RC low-pass filter module, and the second signal acquisition unit integrates a second RC low-pass filter module. Both the first RC low-pass filter module and the second RC low-pass filter module are composed of a filter resistor and a filter capacitor connected in parallel.

[0010] In one embodiment of the present invention, a first clamping protection module is provided between the signal output terminal WL1_DET1 of the first signal acquisition unit and ground, and a second clamping protection module is provided between the signal output terminal WL1_DET2 of the second signal acquisition unit and ground. Both the first clamping protection module and the second clamping protection module are used to limit the amplitude of the output signal voltage.

[0011] In one embodiment of the present invention, both the first clamping protection module and the second clamping protection module are composed of one or more diodes.

[0012] This invention employs a pure circuit probe detection method, directly detecting water based on its conductivity. The water level is determined by the change in water resistance between a reference probe and high / low level probes. The circuit switching and signal change are almost instantaneous, eliminating the delay of traditional pressure transmission methods. This results in faster water level detection response, more timely control, and improved overall washing efficiency. This invention completely eliminates the complex mechanical pressure transmission structures such as conduits, air chambers, and rubber diaphragms relied upon by traditional resonant water level sensors. This not only greatly simplifies the internal structure of the washing machine and avoids malfunctions caused by aging mechanical parts, air leaks, and diaphragm damage, but also fundamentally improves the reliability and lifespan of the water level detection system. Since it eliminates the need for bulky resonant sensors and conduits, the probe and circuit board structure of this invention is extremely compact, allowing for easy integration into space-constrained washing machine designs. It is particularly suitable for compact, portable, or desktop washing machines with stringent internal space requirements. This invention consists only of common basic electronic components such as transistors, resistors, and capacitors, significantly reducing material costs and circuit board design complexity, making it ideal for mass production and widespread application. Attached Figure Description

[0013] Figure 1 The diagram shows the probe installed inside the water tank of the washing machine in this invention.

[0014] Figure 2 The diagram shown is a circuit schematic of this utility model.

[0015] Component designation explanation Common probe 1#; Low water level detection probe 2#; High water level detection probe 3#; Switch unit 4; First signal acquisition unit 5; Second signal acquisition unit 6; First clamp protection module 7; Second clamp protection module 8; First RC low-pass filter module 9; Second RC low-pass filter module 10. Detailed Implementation

[0016] The following specific embodiments illustrate the implementation of this utility model. Those skilled in the art can easily understand other advantages and effects of this utility model from the content disclosed in this specification.

[0017] Please see Figures 1 to 2 It should be noted that the structures, proportions, sizes, etc., illustrated in the accompanying drawings are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed in the specification, and are not intended to limit the implementation conditions of this utility model. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportional relationships, or adjustments to the size, without affecting the effects and purposes that this utility model can produce, should fall within the scope of the technical content disclosed in this utility model.

[0018] Please see Figures 1-2 This utility model provides a water level detection circuit for a washing machine, including a common terminal probe 1#, a low water level detection probe 2#, and a high water level detection probe 3# located inside the water tank of the washing machine. The detection circuit also includes a switching unit 4, a first signal acquisition unit 5, and a second signal acquisition unit 6. The switching unit 4 uses a transistor Q1, with the base of transistor Q1 connected to the control signal terminal MCU, the emitter connected to the power supply, and the collector connected to the common terminal probe 1#. A resistor R5 is connected to the base of transistor Q1, and a resistor R3 is connected in parallel between the base and emitter of transistor Q1 to stabilize the base current. The switching unit 4 is used to provide a detection voltage to the common terminal probe 1# according to the on / off state of the control signal.

[0019] The first signal acquisition unit 5 uses a pull-down resistor R4. One end of the pull-down resistor R4 is connected to the low water level detection probe 2#, and the other end is grounded. A signal output terminal WL1_DET1 is led out from the connection point of the pull-down resistor R4 and the low water level detection probe 2#. The first signal acquisition unit 5 is used to acquire the flooding signal of the low water level detection probe 2#. Specifically, a resistor R2 is also connected to the connection point of the pull-down resistor R4 and the low water level detection probe 2#. The other end of the resistor R2 is connected to the collector of the transistor Q1. The resistor R2 plays the role of current limiting and voltage division in the first signal acquisition unit 5, further improving the low water level detection accuracy.

[0020] The second signal acquisition unit 6 uses a pull-down resistor R8. One end of the pull-down resistor R8 is connected to the high water level detection probe 3#, and the other end is grounded. A signal output terminal WL1_DET2 is led out from the connection point of the pull-down resistor R8 and the high water level detection probe 3#. The second signal acquisition unit 6 is used to acquire the flooding signal of the high water level detection probe 3#. Specifically, a resistor R7 is also connected to the connection point of the pull-down resistor R8 and the high water level detection probe 3#. The other end of the resistor R7 is connected to the collector of the transistor Q1. The resistor R7 plays the role of current limiting and voltage division in the second signal acquisition unit 6, further improving the high water level detection accuracy.

[0021] This invention employs a pure circuit probe detection method, directly detecting water based on its conductivity. The water level is determined by the change in water resistance between a reference probe and high / low level probes. The circuit switching and signal change are almost instantaneous, eliminating the delay of traditional pressure transmission methods. This results in faster water level detection response, more timely control, and improved overall washing efficiency. This invention completely eliminates the complex mechanical pressure transmission structures such as conduits, air chambers, and rubber diaphragms relied upon by traditional resonant water level sensors. This not only greatly simplifies the internal structure of the washing machine and avoids malfunctions caused by aging mechanical parts, air leaks, and diaphragm damage, but also fundamentally improves the reliability and lifespan of the water level detection system. Since it eliminates the need for bulky resonant sensors and conduits, the probe and circuit board structure of this invention is extremely compact, allowing for easy integration into space-constrained washing machine designs. It is particularly suitable for compact, portable, or desktop washing machines with stringent internal space requirements. This invention consists only of common basic electronic components such as transistors, resistors, and capacitors, significantly reducing material costs and circuit board design complexity, making it ideal for mass production and widespread application.

[0022] The first signal acquisition unit 5 integrates a first RC low-pass filter module 9, and the second signal acquisition unit 6 integrates a second RC low-pass filter module 10. Both the first RC low-pass filter module 9 and the second RC low-pass filter module 10 are composed of a filter resistor and a filter capacitor connected in parallel. In this embodiment, the first RC low-pass filter module 9 is composed of a resistor R1 and a capacitor C1 connected in parallel, and is used to filter out high-frequency noise from the first signal acquisition unit 5 to ensure a smooth output signal. The second RC low-pass filter module 10 is composed of a resistor R6 and a capacitor C2 connected in parallel, and is used to filter out high-frequency noise from the second signal acquisition unit 6 to ensure a smooth output signal.

[0023] A first clamping protection module 7 is provided between the signal output terminal WL1_DET1 of the first signal acquisition unit 5 and ground, and a second clamping protection module 8 is provided between the signal output terminal WL1_DET2 of the second signal acquisition unit 6 and ground. Both the first clamping protection module 7 and the second clamping protection module 8 are used to limit the amplitude of the output signal voltage. Both the first clamping protection module 7 and the second clamping protection module 8 are composed of one or more diodes. In this embodiment, the first clamping protection module 7 is composed of diodes D1 and D2 arranged in series, and the second clamping protection module 8 is composed of diodes D3 and D4 arranged in series.

[0024] The working process of this utility model includes: 1) Initialization: After the computer board is powered on, the control signal M_WL sends a low level, which turns on the transistor Q1, and the +5V power supply voltage is provided to the common terminal probe 1# through Q1.

[0025] 2) Low water level detection: When the water level has not reached the low water level detection probe 2#, the signal output terminal WL1_DET1 is pulled to a low level of 0V through the pull-down resistor R4. The MCU reads the low level signal and determines that the water level has not reached the low water level. When the water level submerges the low water level detection probe 2#, the voltage of the common terminal probe 1# is conducted to the low water level detection probe 2# through the resistance of the water medium, forming a voltage divider circuit with the pull-down resistor R4. The signal output terminal WL1_DET1 outputs an analog voltage value AD. The MCU reads this AD value and determines that the water level has reached the low water level.

[0026] 3) High water level detection: When the water level has not reached the high water level detection probe 3#, the signal output terminal WL1_DET2 is pulled to a low level of 0V through the pull-down resistor R8. The MCU reads the low level signal and determines that the water level has not reached the high water level. When the water level submerges the high water level detection probe 3#, the voltage of the common terminal probe 1# is conducted to the high water level detection probe 3# through the water medium, forming a voltage divider circuit with the pull-down resistor R8. The signal output terminal WL1_DET2 outputs an analog voltage value AD. The MCU reads this AD value and determines that the water level has reached the high water level.

[0027] In summary, this invention employs a probe-type detection circuit, completely eliminating the complex mechanical pressure transmission structure, thus offering significant advantages in terms of simplified structure, compact size, and high reliability. Furthermore, the circuit is composed only of basic electronic components, which not only greatly reduces costs but also achieves faster response speeds and simpler maintenance and diagnostics. Therefore, this invention effectively overcomes the various shortcomings of existing technologies and possesses high industrial applicability.

[0028] The above embodiments are merely illustrative of the principles and effects of this utility model and are not intended to limit the scope of this utility model. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of this utility model. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in this utility model should still be covered by the claims of this utility model.

Claims

1. A water level detection circuit for a washing machine, characterized in that, Including a common end probe (1#), a low water level detection probe (2#), and a high water level detection probe (3#) located inside the water tank of the washing machine; Also includes: The switching unit (4) uses a transistor Q1. The base of the transistor Q1 is connected to the control signal terminal, the emitter is connected to the power supply, and the collector is connected to the common terminal probe (1#). The switching unit (4) is used to provide a detection voltage to the common terminal probe (1#) according to the on / off state of the control signal. The first signal acquisition unit (5) uses a pull-down resistor R4. One end of the pull-down resistor R4 is connected to the low water level detection probe (2#), and the other end is grounded. A signal output terminal WL1_DET1 is led out from the connection point between the pull-down resistor R4 and the low water level detection probe (2#). The first signal acquisition unit (5) is used to acquire the flooding signal of the low water level detection probe (2#). The second signal acquisition unit (6) uses a pull-down resistor R8. One end of the pull-down resistor R8 is connected to the high water level detection probe (3#), and the other end is grounded. A signal output terminal WL1_DET2 is led out from the connection point between the pull-down resistor R8 and the high water level detection probe (3#). The second signal acquisition unit (6) is used to acquire the flooding signal of the high water level detection probe (3#).

2. The washing machine water level detection circuit according to claim 1, characterized in that: A resistor R5 is connected to the base of the transistor Q1, and a resistor R3 is connected in parallel between the base and emitter of the transistor Q1.

3. The washing machine water level detection circuit according to claim 1, characterized in that: A resistor R2 is also connected at the connection point between the pull-down resistor R4 and the low water level detection probe (2#), and the other end of the resistor R2 is connected to the collector of the transistor Q1.

4. The washing machine water level detection circuit according to claim 1, characterized in that: A resistor R7 is also connected at the connection point between the pull-down resistor R8 and the high water level detection probe (3#), and the other end of the resistor R7 is connected to the collector of the transistor Q1.

5. The washing machine water level detection circuit according to claim 1, characterized in that: The first signal acquisition unit (5) integrates a first RC low-pass filter module (9), and the second signal acquisition unit (6) integrates a second RC low-pass filter module (10). Both the first RC low-pass filter module (9) and the second RC low-pass filter module (10) are composed of a filter resistor and a filter capacitor connected in parallel.

6. The washing machine water level detection circuit according to claim 1, characterized in that: The first signal acquisition unit (5) has a first clamping protection module (7) between its signal output terminal WL1_DET1 and ground, and the second signal acquisition unit (6) has a second clamping protection module (8) between its signal output terminal WL1_DET2 and ground. Both the first clamping protection module (7) and the second clamping protection module (8) are used to limit the amplitude of the output signal voltage.

7. The washing machine water level detection circuit according to claim 1, characterized in that: Both the first clamp protection module (7) and the second clamp protection module (8) are composed of one or more diodes.

Images