A sensor for integrated capacitive liquid level and contamination monitoring

Abstract

The application relates to a sensor integrating capacitive liquid level and dirt monitoring, which comprises a transparent shell, a PCB substrate, a liquid level detection assembly and a dirt detection assembly; the PCB substrate is installed in the transparent shell; the liquid level detection assembly comprises first and second capacitor plates, one end of the first and second capacitor plates is connected with the PCB substrate, and the other end of the first and second capacitor plates respectively extends into two grooves; the dirt detection assembly comprises an infrared emitter tube and an infrared receiver tube connected with the PCB substrate, and the infrared emitter tube and the infrared receiver tube are respectively arranged on the opposite side of the first and second capacitor plates; the first and second capacitor plates are arranged on the PCB substrate as inner electrodes, a measured conductive liquid is used as a common outer electrode, and non-contact water level detection is realized; meanwhile, the infrared emitter tube and the infrared receiver tube are installed on the PCB substrate, infrared light passes through the transparent shell and the measured conductive liquid, and non-contact turbidity detection is realized.

Description

Technical Field

[0001] This invention relates to the field of sensor technology, and in particular to a sensor that integrates capacitive liquid level and dirt monitoring. Background Technology

[0002] The condensate pans of commercial central air conditioning systems, data center precision air conditioning systems, and multi-split systems are the most common locations for building leaks. According to HVAC industry statistics, air conditioning leaks account for more than 35% of building electromechanical failures. The average cost of a single leak repair and ceiling rework exceeds 20,000 yuan. Leaks in data center server rooms can also cause server downtime, resulting in economic losses of millions of yuan.

[0003] Currently, water level monitoring systems commonly use exposed electrode level switches and float level switches. Some high-end products attempt to use independent turbidity sensors to detect water quality, but all of these have insurmountable drawbacks, specifically: (1) Contact electrode corrosion and scaling failure: When the metal electrode is directly immersed in condensate, minerals and microorganisms in the water quickly form algae and scale on the electrode surface, leading to abnormal electrode conduction and frequent false alarms or water blockage without alarm. In the high humidity environment of the plum rain season, the average service life of electrode switches is only 3-6 months. Commercial air conditioners run continuously throughout the year, resulting in a large amount of maintenance and replacement and extremely high labor costs.

[0004] (2) The float switch is prone to jamming and failure: silt, flocculent matter and dust in the water collection pan are very easy to entangle the float, causing the float to get stuck at the upper or lower limit position, resulting in uncontrolled water overflow. In addition, the float structure is large in size and cannot be adapted to the narrow water collection pan space of multi-split air conditioners, ultra-thin duct air conditioners and other similar systems.

[0005] (3) Only fixed-point alarm, no continuous liquid level monitoring: The existing switch only has a single-point signal of "full water shutdown", which cannot predict the gradual blockage trend of the drainage pipe in advance. When the drainage pipe gradually narrows due to algae and mud accumulation, the rate of water rise will accelerate, but the traditional switch cannot recognize this process and can only be passively repaired after the overflow failure occurs.

[0006] (4) Unable to identify the root cause of water pollution: The main cause of drainage pipe blockage is the growth of algae and sludge accumulation in the water. However, the existing sensors cannot detect the cleanliness of the water body and cannot trigger the self-cleaning program of the pipeline in advance. They can only stop the machine for maintenance after the pipeline is completely blocked.

[0007] (5) The separate layout is costly and has a high risk of sealing: If it is necessary to monitor the liquid level and water quality at the same time, the liquid level probe and the independent turbidity probe need to be installed separately, which not only increases the product cost and wiring complexity, but also requires opening holes in the water collection pan, which poses a risk of water leakage due to poor sealing.

[0008] (6) Insufficient sensitivity of traditional fully sealed capacitive sensors: In order to solve the corrosion problem, some products use capacitive sensors with fully injection-molded plates. However, the space between the two electrodes is filled with plastic and the medium is fixed. The capacitance change caused by the liquid level change is very small (usually less than 1pF). It can only be used as a fixed-point switch and cannot achieve continuous linear liquid level detection. Summary of the Invention

[0009] In view of this, it is necessary to provide a sensor that integrates capacitive liquid level and dirt monitoring to solve the above problems.

[0010] This invention provides a sensor integrating capacitive liquid level and dirt detection, including a transparent shell, a PCB substrate, a liquid level detection component, and a dirt detection component. The transparent shell has two opposing grooves inside. The PCB substrate is mounted inside the transparent shell. The liquid level detection component includes a first capacitor plate and a second capacitor plate, one end of which is connected to the PCB substrate, and the other ends of which extend into the two grooves respectively. The opposite sides of the first and second capacitor plates are spaced apart from the transparent shell. The dirt detection component includes an infrared emitting tube and an infrared receiving tube connected to the PCB substrate. The infrared emitting tube and the infrared receiving tube are respectively located on opposite sides of the first and second capacitor plates, with the emitting end of the infrared emitting tube pointing towards the receiving end of the infrared receiving tube.

[0011] Furthermore, the transparent housing includes a transparent shell and a socket, the top of the transparent shell is provided with an opening, the socket is detachably connected to the opening of the transparent shell, and the socket is electrically connected to the PCB substrate.

[0012] Furthermore, the bottom of the transparent shell protrudes downward to form two detection sections, and the grooves are formed inside the two detection sections.

[0013] Furthermore, the transparent housing also includes a first sealing ring and a second sealing ring. The first sealing ring is disposed at the connection between the transparent housing and the socket, and the second sealing ring is sleeved on the outer wall of the transparent housing for contacting the air conditioner drip tray.

[0014] Furthermore, it also includes a microcontroller, a high-precision capacitor-to-digital converter chip, an antenna spring, and a pin header mounted on the PCB substrate.

[0015] Furthermore, it also includes a first lens and a second lens, which are respectively disposed on opposite sides of the infrared emitting tube and the infrared receiving tube. The first lens covers the infrared emitting tube, and the second lens covers the infrared receiving tube.

[0016] Furthermore, it also includes a first nF DC blocking capacitor connected in series between the first capacitor plate and the input terminal of the PCB substrate; and a second nF DC blocking capacitor connected in series between the second capacitor plate and the input terminal of the PCB substrate.

[0017] Furthermore, it also includes two drive shielding rings, which are respectively disposed on the first capacitor plate and the second capacitor plate. The two drive shielding rings are electrically connected to the PCB substrate to eliminate stray capacitance between the first capacitor plate and the second capacitor plate and ground.

[0018] Furthermore, the PCB substrate also includes an infrared constant current driving circuit, which is a transistor constant current source topology, and is electrically connected to the infrared emitting tube.

[0019] Furthermore, it also includes a copper foil layer disposed on the outer wall of the transparent housing.

[0020] Compared with existing technologies: This method utilizes a PCB substrate as a carrier, on which a first capacitor plate and a second capacitor plate are arranged as internal electrodes, and the conductive liquid being measured is used as a common external electrode, forming a series composite capacitor structure of "first capacitor plate - air - transparent shell - conductive liquid being measured - transparent shell - air - second capacitor plate", thus realizing non-contact water level detection; at the same time, an infrared emitting tube and an infrared receiving tube are installed on the PCB substrate, and infrared light passes through the transparent shell and the conductive liquid being measured, thus realizing non-contact turbidity detection. Attached Figure Description

[0021] Figure 1 This is a cross-sectional schematic diagram of the integrated capacitive liquid level and dirt monitoring sensor provided in an embodiment of the present invention; Figure 2 for Figure 1 A schematic diagram of the overall explosion. Figure 3 for Figure 2 A schematic diagram of the front structure of the PCB substrate; Figure 4 for Figure 2 A schematic diagram of the back structure of the PCB substrate; Figure 5 for Figure 1 Enlarged diagram of section A in the middle; Figure 6 for Figure 1 Enlarged diagram of section B; Figure 7 This is a schematic diagram of the overall structure of the sensor for integrated capacitive liquid level and dirt monitoring provided in an embodiment of the present invention. Figure 8 This is a schematic diagram of the structure of the integrated capacitor liquid level and dirt monitoring sensor installed in the air conditioner water collection pan, as provided in an embodiment of the present invention.

[0022] Figure label: Transparent shell 100, groove 101, transparent shell 110, socket 120, first sealing ring 130, second sealing ring 140; PCB substrate 200, connecting screw 201, microcontroller 210, high-precision capacitor-to-digital converter chip 220, antenna spring 230, pin header 240; Liquid level detection component 300, first capacitor plate 310, second capacitor plate 320; Dirt detection component 400, infrared emitting tube 410, infrared receiving tube 420, first lens 430, second lens 440; Air conditioner water collection tray 500; Drainage pipe 600; Drainage pump 700. Detailed Implementation

[0023] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention.

[0024] like Figure 1 and Figure 2As shown in the figure, an embodiment of the present invention provides a sensor integrating capacitive liquid level and dirt monitoring, including a transparent shell 100, a PCB substrate 200, a liquid level detection component 300, and a dirt detection component 400; the transparent shell 100 has two oppositely arranged grooves 101 inside; the PCB substrate 200 is installed inside the transparent shell 100; the liquid level detection component 300 includes a first capacitor plate 310 and a second capacitor plate 320, one end of the first capacitor plate 310 and the second capacitor plate 320 being connected to the PCB substrate 200, the first capacitor... The other ends of the electrode plate 310 and the second capacitor electrode plate 320 extend into the two grooves 101 respectively. The opposite sides of the first capacitor electrode plate 310 and the second capacitor electrode plate 320 are spaced apart from the transparent shell 100. The dirt detection component 400 includes an infrared emitting tube 410 and an infrared receiving tube 420 connected to the PCB substrate 200. The infrared emitting tube 410 and the infrared receiving tube 420 are respectively disposed on the opposite sides of the first capacitor electrode plate 310 and the second capacitor electrode plate 320. The emitting end of the infrared emitting tube 410 is positioned pointing towards the receiving end of the infrared receiving tube 420.

[0025] In this system, a PCB substrate 200 is used as a carrier, on which a first capacitor plate 310 and a second capacitor plate 320 are arranged as internal electrodes, and the conductive liquid being tested is used as a common external electrode, forming a series composite capacitor structure of "first capacitor plate 310-air-transparent shell 100-conductive liquid being tested-transparent shell 100-air-second capacitor plate 320", thus realizing non-contact water level detection. At the same time, an infrared emitting tube 410 and an infrared receiving tube 420 are installed on the PCB substrate 200. Infrared light passes through the transparent shell 100 and the conductive liquid being tested, thus realizing non-contact turbidity detection.

[0026] The capacitance detection circuit converts the change in capacitance value into a digital signal. The main control unit calculates the real-time liquid level height based on the pre-calibrated capacitance-water level correspondence, with a resolution of up to 0.1 mm.

[0027] In this embodiment, the transparent outer shell 100 has two oppositely arranged grooves 101 inside. The transparent outer shell 100 provides a closed mounting structure for the PCB substrate 200, the liquid level detection component 300, and the dirt detection component 400, avoiding contact with external liquids and affecting their lifespan. The two grooves 101 are mounting cavities for the first capacitor plate 310, the second capacitor clamping plate, the infrared emitting tube 410, and the infrared receiving tube 420.

[0028] In one embodiment, the transparent housing 100 includes a transparent housing 110 and a socket 120. The top of the transparent housing 110 has an opening, and the socket 120 is detachably connected to the opening of the transparent housing 110. The socket 120 is electrically connected to the PCB substrate 200. The pins of the socket 120 are integrally injection molded to prevent liquid from entering the interior of the transparent housing 110.

[0029] In this embodiment, the bottom of the transparent shell 110 protrudes downward to form two detection parts, and the interior of the two detection parts forms a groove 101.

[0030] In one embodiment, the transparent housing 100 further includes a first sealing ring 130 and a second sealing ring 140. The first sealing ring 130 is disposed at the connection between the transparent housing 110 and the socket 120, and the second sealing ring 140 is sleeved on the outer wall of the transparent housing 110 for contacting the air conditioner water receiving tray.

[0031] For example, the transparent shell 100 is integrally injection molded from high-transparency PC / PPS material, and has a cuboid structure with parallel cavities inside (i.e., two grooves 101). The cavity size matches the integrated PCB substrate 200, and after the PCB electrode is inserted, a uniform air gap of 0.4-0.5mm is left between it and the inner wall of the transparent shell 100. The shell wall thickness is 0.8-1.5mm to ensure effective penetration of infrared light and effective coupling of capacitive signals.

[0032] In this embodiment, the PCB substrate 200 is mounted inside the transparent housing 100. The PCB substrate 200 serves as the carrier structure for the liquid level detection component 300 and the dirt detection component 400.

[0033] like Figure 3 and Figure 4 As shown, in one embodiment, the system further includes a microcontroller 210, a high-precision capacitive digital converter chip 220, an antenna spring 230, and a pin header 240 mounted on the PCB substrate 200. The PCB substrate 200 is connected to the transparent housing 100 via connecting screws 201.

[0034] For example, the PCB substrate 200 is a rectangular FR-4 rigid PCB board with a thickness of 1.6mm. Two parallel rectangular copper foil capacitor plates (i.e., the first capacitor plate 310 and the second capacitor plate 320) are arranged on the front side, extending in a direction perpendicular to the PCB plates, and covered with a green solder resist layer to further enhance insulation performance. An infrared emitting diode 410 and an infrared receiving diode 420 are mounted on the lower back of the capacitor plates, with their optical axes parallel to each other and parallel to the PCB plane, spaced 8-12mm apart. Electrical connection pads are provided at the top for connecting to external electrical control systems.

[0035] In one embodiment, a capacitance detection circuit is also included. Exemplarily, the capacitance detection circuit employs an FDC2214 4-channel high-precision capacitance-to-digital converter (CDC) chip. The excitation signal is a high-frequency AC signal with a frequency of 100kHz-1MHz and a peak-to-peak value of less than 1V, with no DC component, thus eliminating electrolytic polarization at its source. For hardware compensation, a built-in programmable CAPDAC automatically cancels out the fixed substrate capacitance caused by air and plastic, extracting only the capacitance increment caused by liquid level changes. With a 12-bit resolution, it can detect capacitance changes as small as 0.1pF, corresponding to a liquid level resolution of up to 0.1mm.

[0036] In this embodiment, a first nF DC blocking capacitor is connected in series between the first capacitor plate 310 and the input terminal of the PCB substrate 200; and a second nF DC blocking capacitor is connected in series between the second capacitor plate 320 and the input terminal of the PCB substrate 200. This completely blocks leakage current from the PCB substrate 200 and stray DC current from entering the electrodes, further eliminating the risk of electrolysis. This design, as an important detail of the circuit design in this invention application, can effectively improve the reliability and safety of the sensor during long-term operation.

[0037] In this embodiment, two driving shielding rings are also included. These two driving shielding rings are respectively disposed on the first capacitor plate 310 and the second capacitor plate 320. The two driving shielding rings are electrically connected to the PCB substrate 200 and are used to eliminate stray capacitance between the first capacitor plate 310, the second capacitor plate 320, and ground. Eliminating stray capacitance between the plates and ground improves detection sensitivity and anti-interference capability. This shielding structure can effectively suppress the influence of external electromagnetic interference on the accuracy of capacitance detection.

[0038] In one embodiment, an infrared detection circuit is also included. Exemplarily, the infrared detection circuit includes a constant current drive circuit, a signal amplification circuit, and a filtering circuit. The constant current drive circuit provides a constant drive current of 18-20mA to the infrared emitting diode 410, ensuring stable emitted light intensity unaffected by power supply voltage fluctuations. The signal amplification circuit uses an operational amplifier to convert the weak current signal output by the infrared receiving diode 420 into a voltage signal and amplifies it by 100-200 times. The filtering circuit uses an RC low-pass filter circuit to filter out ambient stray light and electromagnetic interference. The infrared wavelength is 940nm near-infrared light to avoid visible light interference.

[0039] In this embodiment, the infrared constant current driving circuit is a transistor constant current source topology, and is electrically connected to the infrared emitting diode 410. It provides a stable driving current to the infrared emitting diode 410. This circuit can maintain stable emitted light intensity even when the power supply voltage fluctuates, ensuring the accuracy and repeatability of turbidity detection.

[0040] In this embodiment, the filtering circuit is an LC power supply filter circuit to suppress electromagnetic interference from the air conditioning electronic control system and improve the stability of the sensor. Regarding PCB layout, the capacitor plates are kept away from power and signal lines, and analog and digital grounds are separated using a single-point grounding method. The infrared detection circuit uses pulse modulation to drive the infrared emitting diode 410, and uses software algorithms to filter out ambient stray light interference.

[0041] In one embodiment, a main control unit is also included. For example, the main control unit is an STM32F030F4P6 32-bit microcontroller 210 with a built-in 12-bit AD converter.

[0042] In terms of data processing, the system receives the capacitance signal output from the capacitance detection circuit and the light intensity signal output from the infrared detection circuit, and calculates the real-time liquid level and water turbidity based on the pre-calibrated correspondence.

[0043] In terms of automatic control, multi-level control signals are output according to preset thresholds, including low liquid level warning, start of drainage pump 700 at medium liquid level, unit shutdown protection at high liquid level, and start of self-cleaning when turbidity exceeds the standard.

[0044] For calibration storage, a built-in Flash memory is used to store calibration parameters and corresponding tables. The communication interface supports UART / RS485 communication, which can upload test data to the air conditioning central control system.

[0045] In one embodiment, the sampling frequency is reduced in standby mode to decrease energy consumption and meet the requirements of long-term uninterrupted operation of commercial air conditioners. Simultaneously, a fault self-diagnosis circuit is set up to detect faults such as open / short circuits in capacitor plates and infrared diode failures, and report these faults to the central control system for timely maintenance by operations and maintenance personnel.

[0046] Understandably, for insulating liquids such as engine oil and refrigerant, a copper foil layer can be vertically pasted on the outer wall of the transparent shell 100 as an external electrode, and the same series composite capacitor architecture can still be used to realize liquid level detection.

[0047] The liquid level detection component 300 in this embodiment includes a first capacitor plate 310 and a second capacitor plate 320. One end of the first capacitor plate 310 and the second capacitor plate 320 is connected to the PCB substrate 200, and the other end of the first capacitor plate 310 and the second capacitor plate 320 extends into two grooves 101 respectively. The opposite sides of the first capacitor plate 310 and the second capacitor plate 320 are spaced apart from the transparent shell 100.

[0048] The dirt detection component 400 in this embodiment includes an infrared emitting tube 410 and an infrared receiving tube 420 connected to the PCB substrate 200. The infrared emitting tube 410 and the infrared receiving tube 420 are respectively disposed on opposite sides of the first capacitor plate 310 and the second capacitor plate 320, with the emitting end of the infrared emitting tube 410 pointing towards the receiving end of the infrared receiving tube 420. like Figure 5 and Figure 6 As shown, in one embodiment, it further includes a first lens 430 and a second lens 440. The first lens 430 and the second lens 440 are respectively disposed on opposite sides of the infrared emitting tube 410 and the infrared receiving tube 420. The first lens 430 covers the infrared emitting tube 410, and the second lens 440 covers the infrared receiving tube 420.

[0049] The principle of liquid level detection is as follows: When the sensor is inserted into the area to be detected, the outer wall of the transparent housing 100 comes into contact with the conductive liquid, which is equivalent to a large-area common external electrode, forming the following series composite capacitor structure: first capacitor plate 310 → air gap → side wall of transparent housing 100 → conductive liquid → side wall of transparent housing 100 → air gap → second capacitor plate 320. (The air gap mentioned above is the gap between the first capacitor plate 310 and the second capacitor plate 320 and the transparent housing 100).

[0050] When the water level rises, the area of ​​the transparent outer shell 100 covered by the conductive liquid increases. For example, the dielectric constant of water (ε≈80) is much greater than that of air (ε≈1), causing the equivalent capacitance between the first capacitor plate 310 and the second capacitor plate 320 to increase linearly. When the liquid level falls, the equivalent capacitance decreases linearly. Therefore, the liquid level can be determined based on the equivalent capacitance between the first capacitor plate 310 and the second capacitor plate 320.

[0051] By continuously monitoring changes in the liquid level, the rate of water rise can also be calculated. When the rate of rise exceeds a preset threshold, it indicates a gradual blockage. The system will issue an early warning signal to notify maintenance personnel to carry out repairs and prevent overflow accidents.

[0052] Turbidity detection principle: Near-infrared light emitted by infrared emitter 410 passes sequentially through one side of the transparent outer shell 100, the conductive liquid, and the other side of the transparent outer shell 100 before being received by infrared receiver 420. When the water is clean, the liquid absorbs and scatters less infrared light, resulting in a higher received light intensity. When the water contains impurities such as algae, silt, and suspended solids, the liquid absorbs and scatters infrared light more, resulting in a lower received light intensity. The main control unit determines the turbidity level of the water body based on the attenuation ratio of the received light intensity.

[0053] To facilitate understanding of the intent of this invention application, a detailed description and explanation will be provided below using an application to an air conditioner water collection pan 500 as an example.

[0054] like Figure 7 and 8 As shown, the sensor is installed at the opening at the top of the air conditioning condensate pan 500. The bottom of the sensor's transparent housing 100100 extends into the air conditioning condensate pan 500. Depending on the water level and degree of dirt in the air conditioning condensate pan 500, the sensor has a warning mode, a drainage mode, a protection mode, and a cleaning linkage mode, as detailed below: Warning level (low water accumulation): The liquid level rises slightly (e.g., 5mm). The system reports to the central control room, prompting maintenance personnel to inspect the drainage pipes for minor blockages.

[0055] Drainage setting (medium level): When the water reaches the set height (e.g., 20mm), the drain pump 700 will automatically start and the water will be forced to drain through the drain pipe 600.

[0056] Protection setting (high warning level): If abnormal drainage causes the liquid level to rise continuously (e.g., 30mm, close to the overflow threshold), the system will immediately cut off the power to the air conditioning compressor to prevent overflow and water from soaking the ceiling.

[0057] Cleaning linkage: When the turbidity exceeds the standard, the system first starts the spray self-cleaning program of the air conditioner water collection pan 500 to flush out algae and mud impurities in the pan. After cleaning is completed, the drain pump 700 is automatically turned on to drain the sewage.

[0058] Compared with existing technologies: (1) Completely solves the problem of corrosion and scaling, and the maintenance-free period is up to 5 years: The first capacitor plate 310, the second capacitor plate 320, the infrared emitting tube 410 and the infrared receiving tube 420 are completely sealed in the transparent shell 100 and do not come into direct contact with condensate. This physically eliminates the problem of scale and algae adhering and causing electrode failure, and greatly reduces the maintenance cost of commercial air conditioners.

[0059] (2) A unique series composite capacitor structure is used to achieve high-sensitivity non-contact liquid level detection: The liquid being measured is used as a common external electrode, which not only ensures the non-contact design of the first capacitor plate 310 and the second capacitor plate 320, but also obtains a sufficiently large capacitance change (the full-scale change can reach 10-50pF), solving the industry problem of insufficient sensitivity of traditional fully enclosed capacitor sensors and realizing continuous linear liquid level detection.

[0060] (3) Single device two-in-one design, greatly reducing installation space and cost: The sensor realizes liquid level and turbidity detection at the same time, replacing the original liquid level switch + independent turbidity probe two sets of accessories. There is no need to open the hole in the water collection pan, which completely eliminates the hidden danger of water leakage due to hole sealing. It is especially suitable for small water collection pan space such as multi-split air conditioners and ultra-thin duct air conditioners.

[0061] (4) Continuous liquid level + pipe blockage prediction, from passive maintenance to active prevention: say goodbye to the drawback of traditional switches that only have overflow alarms, monitor the rate of water accumulation in real time, and can predict the gradual blockage of drainage pipes in advance, avoiding large-area water damage to commercial ceilings.

[0062] (5) Source prevention and automatic self-cleaning to reduce faults: Relying on the infrared turbidity detection function, it can identify the accumulation of water, algae and mud in advance and automatically start the cleaning program to reduce the probability of drainage pipe blockage from the source and greatly reduce the air conditioner leakage repair rate.

[0063] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A sensor integrating capacitive liquid level and dirt monitoring, characterized in that, include: A transparent outer shell, wherein two oppositely arranged grooves are formed inside the transparent outer shell; A PCB substrate, which is mounted inside the transparent housing; A liquid level detection component, comprising a first capacitor plate and a second capacitor plate, one end of the first capacitor plate and the second capacitor plate being connected to the PCB substrate, the other end of the first capacitor plate and the second capacitor plate extending into the two grooves respectively, and the opposite sides of the first capacitor plate and the second capacitor plate being spaced apart from the transparent shell. A dirt detection component includes an infrared emitting tube and an infrared receiving tube connected to the PCB substrate. The infrared emitting tube and the infrared receiving tube are respectively disposed on opposite sides of the first capacitor plate and the second capacitor plate, and the emitting end of the infrared emitting tube is positioned to point towards the receiving end of the infrared receiving tube.

2. The sensor for integrated capacitive liquid level and contamination monitoring according to claim 1, characterized in that, The transparent housing includes a transparent housing and a socket. The top of the transparent housing is provided with an opening. The socket is detachably connected to the opening of the transparent housing and is electrically connected to the PCB substrate.

3. The sensor for integrated capacitive liquid level and contamination monitoring according to claim 2, characterized in that, The bottom of the transparent shell protrudes downward to form two detection sections, and the grooves are formed inside the two detection sections.

4. The sensor for integrated capacitive liquid level and contamination monitoring according to claim 2, characterized in that, The transparent housing also includes a first sealing ring and a second sealing ring. The first sealing ring is disposed at the connection between the transparent housing and the socket, and the second sealing ring is sleeved on the outer wall of the transparent housing for contacting the air conditioner drip tray.

5. The sensor for integrated capacitive liquid level and contamination monitoring according to claim 1, characterized in that, It also includes a microcontroller, a high-precision capacitor-to-digital converter chip, an antenna spring, and a pin header mounted on the PCB substrate.

6. The sensor for integrated capacitive liquid level and contamination monitoring according to claim 1, characterized in that, It also includes a first lens and a second lens, which are respectively disposed on opposite sides of the infrared emitting tube and the infrared receiving tube. The first lens covers the infrared emitting tube, and the second lens covers the infrared receiving tube.

7. The sensor for integrated capacitive liquid level and contamination monitoring according to claim 1, characterized in that, It also includes a first nF DC blocking capacitor connected in series between the first capacitor plate and the input terminal of the PCB substrate; and a second nF DC blocking capacitor connected in series between the second capacitor plate and the input terminal of the PCB substrate.

8. The sensor for integrated capacitive liquid level and contamination monitoring according to claim 1, characterized in that, It also includes two drive shielding rings, which are respectively disposed on the first capacitor plate and the second capacitor plate. The two drive shielding rings are electrically connected to the PCB substrate to eliminate stray capacitance between the first capacitor plate and the second capacitor plate and ground.

9. The sensor for integrated capacitive liquid level and contamination monitoring according to claim 1, characterized in that, The PCB substrate also includes an infrared constant current driving circuit, which is a transistor constant current source topology and is electrically connected to the infrared emitting tube.

10. The sensor for integrated capacitive liquid level and contamination monitoring according to claim 1, characterized in that, It also includes a copper foil layer disposed on the outer wall of the transparent housing.

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