Device and method for cleaning glass surface by adopting ultrasonic wave to drive liquid drops

Abstract

The invention discloses a device and a method for cleaning a glass surface by adopting ultrasonic wave to drive liquid drops, the device comprises piezoelectric ceramics, and a corresponding resonant frequency is selected according to the geometric dimension and acoustic parameters of a to-be-cleaned glass plate and the type of stains covering the surface of the to-be-cleaned glass plate; the bonding layer is used for fixing the piezoelectric ceramic on the surface of the glass plate to be cleaned; the impedance analyzer is used for measuring the resonant frequency of the piezoelectric ceramic, the bonding layer and the whole to-be-cleaned glass plate; and the signal generator is connected with the piezoelectric ceramic through the power amplifier, selects an alternating current voltage signal for exciting the piezoelectric ceramic according to the resonant frequency and impedance characteristics measured by the impedance analyzer, and performs cleaning work by using liquid drops generated on the surface of the to-be-cleaned glass plate. The liquid drops can directionally collect dust on the surface of the glass plate to be cleaned in the propagation direction of ultrasonic waves generated by the piezoelectric ceramics and leave the surface. The cleaning agent has the advantages of short cleaning time, suitability for glass surfaces in different occasions, low energy consumption, low water consumption and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field of surface dust removal, and particularly relates to a device and method for cleaning a glass surface by using ultrasonic-driven droplets. Background Art

[0002] Dust in the environment gradually deposits on the surface of objects over time, changing the original heat transfer characteristics and optical characteristics of the objects, and having a negative impact on heat exchange devices such as fins, optical devices such as lenses, and new energy devices such as photovoltaic panels. For the fins of a heat exchanger, the dust accumulated between the fins increases the flow resistance and thermal resistance during the heat transfer process. For a camera lens, the dust in the picture reduces the image quality and affects the work of autonomous driving and safety monitoring. For a photovoltaic power generation panel and a solar thermal collector panel, the dust layer covering the glass surface affects the transmission of sunlight, reducing the power generation efficiency and the heat collection efficiency of the two respectively. Taking the research of Dhaouadi et al. and Adinoyi et al. as an example, for a photovoltaic power generation device in Saudi Arabia, when the photovoltaic glass deposits dust outdoors for 15 weeks, its ultraviolet-visible light transmittance is reduced by 30% compared with when it is clean. If the photovoltaic glass is not cleaned for more than six months, the power output may be reduced by more than 50%. The surface cleaning work of the above devices is crucial for their efficient and sustainable operation. Therefore, how to efficiently clean the surface covered with dust is a current research hotspot.

[0003] The existing surface cleaning methods mainly include water spraying dust removal, air jet dust removal, brush sweeping dust removal, vibration dust removal, electrostatic dust removal, and self-cleaning surfaces. Water spraying dust removal uses a pressurized water jet or spray to clean the surface. This is a common and reliable method, but it consumes a large amount of water resources. Research reports show that the water consumption for surface cleaning in a photovoltaic power station can reach one million to five million gallons per 100 megawatts per year. The flat-fan nozzle proposed by Majeed et al. can form a spray above the photovoltaic panel to provide cleaning, reducing the water consumption to 1.8 L per square meter. Air jet dust removal uses compressed air to blow away the dust on the surface. Li et al. studied and tested a compressed air conditioning method that can clean and cool photovoltaic panels simultaneously, with a dust removal rate of up to 86.4%. However, the energy consumption of the compressed air process is relatively high, and the airflow carrying dust during the cleaning process is likely to cause secondary pollution on the surface. Brush sweeping dust removal uses a rolling brush of a handheld, vehicle-mounted, or dust removal robot to scrape and remove dust from the surface. The photovoltaic ash removal robot developed by Fan et al., composed of a rolling brush and negative pressure, has an average dust removal rate of 92.46% and can effectively prevent secondary pollution during the cleaning process. However, when there are hard particles on the surface, the mechanical scraping process will wear the surface and reduce the service life of the surface. Vibration dust removal uses high-amplitude vibration to separate the dust on the surface, and electrostatic dust removal generates an electric field force to separate the dust by applying an electric charge to the dust. Both methods can remove dust in a very short time. However, they are both more effective for dry dust particles and less effective for removing dust with more water content and stronger adhesion. Self-cleaning coatings include superhydrophobic surfaces, hydrophobic surfaces with a microstructural gradient, and surfaces with a wettability gradient, etc. The contact angle of water droplets on the self-cleaning coating is generally large, so they can roll quickly or roll along a specific route to carry away the dust. However, the coating needs to consider durability and environmental friendliness, which limits its large-scale application. Summary of the Invention

[0004] The purpose of the present invention is to provide a device and method for cleaning the glass surface by driving droplets with ultrasonic waves in view of the above problems in the existing technology. Piezoelectric ceramics are used to excite ultrasonic waves on the glass plate, and the droplets on the glass surface are excited to generate internal flow and overall movement to achieve the work of surface dust removal. It has the advantages of simple device structure, fast driving speed, water and energy saving, and is suitable for cleaning various surface stains.

[0005] To achieve the above purpose, the present invention has the following technical solutions:

[0006] In the first aspect, a device for cleaning the glass surface by driving droplets with ultrasonic waves is provided, including:

[0007] Piezoelectric ceramics, selecting the corresponding resonant frequency according to the geometric dimensions, acoustic parameters of the glass plate to be cleaned, and the type of stains covering the surface;

[0008] An adhesive layer for fixing the piezoelectric ceramic on the surface of the glass plate to be cleaned;

[0009] An impedance analyzer for measuring the resonant frequency of the piezoelectric ceramic, the adhesive layer, and the entire glass plate to be cleaned;

[0010] A signal generator is connected to the piezoelectric ceramic through a power amplifier. It selects an AC voltage signal to excite the piezoelectric ceramic according to the resonant frequency and impedance characteristics measured by the impedance analyzer, and uses the droplets generated on the surface of the glass plate to be cleaned for cleaning work, so that the droplets can collect the dust on the surface of the glass plate to be cleaned in the direction of the ultrasonic wave generated by the piezoelectric ceramic and leave the surface.

[0011] As a preferred solution, the glass plate to be cleaned is soda-lime glass or tempered glass, and the order of magnitude of the wavelength of the ultrasonic wave generated by the piezoelectric ceramic matches the thickness of the glass plate to be cleaned; if the glass plate to be cleaned is curved, the radius of curvature of the glass plate to be cleaned is greater than the wavelength of the ultrasonic wave generated by the piezoelectric ceramic.

[0012] As a preferred solution, the dust on the surface of the glass plate to be cleaned is dry dust or dust containing water, mud, stains remaining after evaporation of muddy water, and organic matter, and the coverage density of dust particles is 0.1g / mm 2 ~50g / mm 2 .

[0013] As a preferred solution, the piezoelectric ceramic uses lead zirconate titanate PZT piezoelectric ceramic, and the models include PZT-4, PZT-5H, PZT-5A, and PZT-8.

[0014] As a preferred solution, the bonding position of the piezoelectric ceramic and the glass plate to be cleaned is at the edge of the front or back of the glass plate. The adhesive layer is formed by ultraviolet curing glue or AB glue, and the thickness of the adhesive layer is less than 0.1mm.

[0015] As a preferred solution, the impedance analyzer selects the frequency with resonance meeting the requirements in the range of 20kHz to 1MHz as the resonant frequency, and the signal generator selects the amplitude of the AC voltage signal to excite the piezoelectric ceramic through the power amplifier to be 10V to 380V.

[0016] As a preferred solution, after the adhesive layer fixes the piezoelectric ceramic on the surface of the glass plate to be cleaned, the glass plate to be cleaned is inclined at an angle of -90° to 90° with the horizontal plane or placed horizontally; the volume of the droplets generated on the surface of the glass plate (13) is 5μL to 200μL, and is formed by spraying, water spraying or natural condensation.

[0017] In a second aspect, a method for cleaning a glass surface by driving droplets using ultrasonic waves is provided, including:

[0018] Obtain the geometric dimensions, acoustic parameters, and types of stains covering the surface of the glass plate to be cleaned, and select the resonant frequency of the piezoelectric ceramic according to the geometric dimensions, acoustic parameters, and types of stains covering the surface of the glass plate to be cleaned;

[0019] Fix the selected piezoelectric ceramic on the surface of the glass plate to be cleaned according to the corresponding resonant frequency;

[0020] Use an impedance analyzer to measure the overall resonant frequency of the glass plate to be cleaned, and select an AC voltage signal for exciting the piezoelectric ceramic according to the resonant frequency and impedance characteristics measured by the impedance analyzer;

[0021] Make the piezoelectric ceramic work, and use the droplets generated on the surface of the glass plate to be cleaned for cleaning, so that the droplets can collect the surface dust of the glass plate to be cleaned along the direction of ultrasonic wave propagation generated by the piezoelectric ceramic and leave the surface.

[0022] As a preferred solution, the piezoelectric ceramic adopts a cuboid structure with a length of 1 mm to 200 mm, a width of 1 mm to 100 mm, and a thickness of 1 mm to 10 mm; the piezoelectric ceramic is welded with wires by using a flanged electrode or a double-sided electrode method.

[0023] As a preferred solution, the surface dust particles of the glass plate to be cleaned are simultaneously subjected to the gravity acting vertically downward on themselves, the buoyancy acting vertically upward on the droplets, the acoustic radiation force along the direction of the sound pressure gradient, and the acoustic streaming drag force along the direction of acoustic flow.

[0024] Compared with the prior art, the present invention has at least the following beneficial effects:

[0025] Compared with other existing cleaning methods, cleaning the dust on the glass plate surface using droplets is a water-saving and energy-saving method. Among them, the droplets generated on the surface of the glass plate to be cleaned can be sprayed by a mechanical device, or can be rainwater or dew formed by air condensation. The cleaning solution using droplets can reduce the water resource consumption by more than 98% compared with high-pressure water jet cleaning. On the basis of using droplets to remove dust, the present invention introduces ultrasonic waves to drive the droplets on the glass plate surface to carry away the dust, so that the droplets can collect dust in the direction of ultrasonic wave propagation and leave the surface. The device for generating ultrasonic waves uses piezoelectric ceramics fixed on the surface of the glass plate to be cleaned, which can effectively improve the electromechanical conversion efficiency of the device and greatly reduce the device cost. When performing the cleaning work, the amplitude of the ultrasonic wave on the glass plate is less than 50 nm, and the frequency is less than 1 MHz, which is a safe and non-destructive mechanical wave for the glass plate surface. The method of the present invention also has the advantages of short cleaning time, being applicable to glass surfaces in different occasions, low energy consumption and low water consumption, and solves the problems existing in the prior art such as the glass surface being easily scratched, the cleaning process consuming energy, water and time, the floating dust after cleaning causing secondary pollution, and the single type of pollutants to be cleaned. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention, and those of ordinary skill in the art can obtain other relevant drawings based on these drawings without creative efforts.

[0027] Figure 1 Schematic structural diagram of the device for cleaning the glass surface by driving droplets with ultrasonic waves in Embodiment 1 of the present invention;

[0028] Figure 2 Schematic diagram of the principle of cleaning the dust on the glass surface by driving droplets with ultrasonic waves in Embodiment 1 of the present invention;

[0029] Figure 3 Schematic diagram of the force on the dust particles inside the droplets when driving the droplets with ultrasonic waves in Embodiment 1 of the present invention;

[0030] Figure 4 Schematic diagram of the device for cleaning the cover glass of a photovoltaic panel by driving droplets with ultrasonic waves in Embodiment 2 of the present invention;

[0031] Figure 5 Curve diagram showing the influence of different voltages on the movement characteristics of droplets on the glass surface under different embodiment conditions;

[0032] Figure 6 Curve diagram showing the influence of different droplet volumes on the movement characteristics of droplets on the glass surface under different embodiment conditions;

[0033] In the drawings: 11 - piezoelectric ceramic, 12 - adhesive layer, 13 - glass plate to be cleaned, 14 - droplet, 15 - stain adhesion layer, 16 - dust particle, 21 - power amplifier, 22 - signal generator, 23 - impedance analyzer, 31 - photovoltaic glass cover plate, 32 - electrode lead, 33 - insulating photovoltaic plate frame, 34 - solar cell. Detailed implementation manners

[0034] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, those of ordinary skill in the art can also obtain other embodiments without creative efforts.

[0035] Please refer to Figure 1 , an apparatus for cleaning the glass surface by driving droplets with ultrasonic waves is proposed in the embodiments of the present invention. The droplets are used to clean the dust surface. Compared with high-pressure water jet cleaning, it can reduce the water resource consumption by more than 98%. On the basis of using droplets for dust removal, ultrasonic waves can drive the droplets collecting dust away from the surface along its propagation direction to complete the cleaning work of the polluted surface. The apparatus for cleaning the glass surface by driving droplets with ultrasonic waves in the embodiments of the present invention specifically includes:

[0036] The piezoelectric ceramic 11 selects the corresponding resonance frequency according to the geometric dimensions, acoustic parameters of the glass plate 13 to be cleaned and the type of stains covering the surface;

[0037] The adhesive layer 12 is used to fix the piezoelectric ceramic 11 on the surface of the glass plate 13 to be cleaned;

[0038] The impedance analyzer 23 is used to measure the resonance frequency of the piezoelectric ceramic 11, the adhesive layer 12 and the glass plate 13 to be cleaned as a whole;

[0039] The signal generator 22 is connected to the piezoelectric ceramic 11 through the power amplifier 21, selects the AC voltage signal for exciting the piezoelectric ceramic 11 according to the resonance frequency and impedance characteristics measured by the impedance analyzer 23, and uses the droplets 14 generated on the surface of the glass plate 13 to be cleaned for the cleaning work, so that the droplets 14 can collect the dust on the surface of the glass plate 13 to be cleaned and leave the surface along the propagation direction of the ultrasonic waves generated by the piezoelectric ceramic 11, as shown in Figure 2 、 Figure 3 .

[0040] In a possible implementation manner, the glass plate 13 to be cleaned in the embodiment of the present invention is soda-lime glass, tempered glass, etc. The order of magnitude of the wavelength of the ultrasonic wave generated by the piezoelectric ceramic 11 matches the thickness of the glass plate 13 to be cleaned, that is, the thickness of the glass plate 13 to be cleaned is close to the order of magnitude of the wavelength of the ultrasonic wave. If the glass plate 13 to be cleaned is a curved surface, the radius of curvature of the glass plate 13 to be cleaned should be much larger than the wavelength of the ultrasonic wave generated by the piezoelectric ceramic 11.

[0041] In a possible implementation manner, the surface dust of the glass plate 13 to be cleaned in the embodiment of the present invention is dry dust, or dust containing water, mud, stains remaining after evaporation of muddy water, and organic substances. The coverage density of the dust particles 16 is 0.1 g / mm 2 ~50 g / mm 2 .

[0042] In a possible implementation manner, the piezoelectric ceramic 11 in the embodiment of the present invention uses lead zirconate titanate PZT piezoelectric ceramic, and the models include PZT-4, PZT-5H, PZT-5A, and PZT-8, etc. The piezoelectric ceramic 11 can adopt a cuboid structure with a length of 1 mm to 200 mm, a width of 1 mm to 100 mm, and a thickness of 1 mm to 10 mm; in addition, the piezoelectric ceramic 11 is welded with wires by the method of flanged electrodes or double-sided electrodes.

[0043] In a possible implementation manner, the bonding position of the piezoelectric ceramic 11 and the glass plate 13 to be cleaned in the embodiment of the present invention is at the edge of the front or back surface of the glass plate. The bonding layer 12 is formed by thinly coating ultraviolet curing glue or AB glue. After the glue is cured, it needs to ensure a certain hardness, and the thickness of the bonding layer 12 is less than 0.1 mm.

[0044] In a possible implementation manner, the impedance analyzer 23 in the embodiment of the present invention selects the frequency with stronger resonance in the range of 20 kHz to 1 MHz as the resonance frequency, and the signal generator 22 selects the amplitude of the AC voltage signal for exciting the piezoelectric ceramic 11 to be 10 V to 380 V through the power amplifier 21. After the bonding layer 12 fixes the piezoelectric ceramic 11 on the surface of the glass plate 13 to be cleaned, the glass plate 13 to be cleaned is inclined at an angle of -90° to 90° or placed horizontally with respect to the horizontal plane; the volume of the liquid droplets 14 generated on the surface of the glass plate 13 to be cleaned is 5 μL to 200 μL, and is formed by spraying, spraying water, or natural condensation.

[0045] The device for cleaning the glass surface by driving liquid droplets with ultrasonic waves in the embodiment of the present invention can complete the cleaning work on the surface of the glass plate 13 to be cleaned within 2 s to 300 s.

[0046] In the embodiments of the present invention, since the method of ultrasonic excitation of droplet cleaning is adopted to clean the glass surface, the amplitude of the ultrasonic wave on the flat plate is less than 50 nm and the frequency is less than 1 MHz, which is a safe and non-destructive mechanical wave for the glass surface. Compared with other existing methods, the embodiments of the present invention also have the advantages of short cleaning time, being applicable to glass surfaces in different scenarios, low energy consumption, and less water consumption, and solve the problems existing in the prior art such as the glass surface being easily scratched, the cleaning process consuming energy, water, and time, secondary pollution caused by floating dust after cleaning, and the single type of pollutants to be cleaned.

[0047] The device for cleaning the glass surface by ultrasonic driving droplets in the embodiments of the present invention enables the droplets to collect dust in a directional manner along the ultrasonic propagation direction and leave the surface. Among them, the device for generating ultrasonic waves adopts a PZT-type piezoelectric ceramic bonded to the glass plate, which can effectively improve the electromechanical conversion efficiency of the device and greatly reduce the device cost.

[0048] Another embodiment of the present invention also proposes a method for cleaning the glass surface by ultrasonic driving droplets, including:

[0049] Obtain the geometric dimensions, acoustic parameters, and types of stains covering the surface of the glass plate 13 to be cleaned, and select the resonant frequency of the piezoelectric ceramic 11 according to the geometric dimensions, acoustic parameters, and types of stains covering the surface of the glass plate 13 to be cleaned;

[0050] Fix the selected piezoelectric ceramic 11 on the surface of the glass plate 13 to be cleaned according to the corresponding resonant frequency;

[0051] Use an impedance analyzer 23 to measure the overall resonant frequency of the glass plate 13 to be cleaned, and select the AC voltage signal for exciting the piezoelectric ceramic 11 according to the resonant frequency and impedance characteristics measured by the impedance analyzer 23;

[0052] Make the piezoelectric ceramic 11 work, and use the droplets 14 generated on the surface of the glass plate 13 to be cleaned for cleaning, so that the droplets 14 can collect the dust on the surface of the glass plate 13 to be cleaned in a directional manner along the ultrasonic propagation direction generated by the piezoelectric ceramic 11 and leave the surface.

[0053] Example 1:

[0054] 1) The glass plate 13 to be cleaned is ordinary soda-lime glass. The glass plate 13 to be cleaned is a square glass sheet with a length of 100 mm, a width of 100 mm, and a thickness of 2 mm. The glass sheet is cleaned successively with clean water, acetone, and absolute ethanol.

[0055] 2) The stains on the surface of the glass plate 13 to be cleaned are dry dust, and the dust particles come from the deposition of dust in the air. They are obtained by placing the glass plate 13 to be cleaned in the outdoor environment for natural deposition for 15 days. The particle size distribution is in the range of 2μm to 100μm, and the coverage density of the dust particles is about 20g / mm 2 。

[0056] 3) The selected ultrasonic transducer element is a PZT-5H type piezoelectric ceramic. The piezoelectric ceramic 11 is a rectangular strip with a length of 40mm, a width of 6mm, and a thickness of 2mm. The piezoelectric ceramic 11 is welded with wires by the method of flanging electrodes.

[0057] 4) At the central position on one side edge of the glass plate 13 to be cleaned, a thin layer of ultraviolet curable glue is applied on the piezoelectric ceramic 11 and bonded to the glass plate 13 to be cleaned. Then, it is irradiated with an ultraviolet curing lamp for 30 minutes so that the thickness of the cured glue is less than 0.1mm, obtaining a cleaning device.

[0058] 5) An impedance analyzer 23 is used to measure the resonant frequency of the prepared cleaning device. 650kHz is selected as its resonant frequency. An AC voltage signal with a frequency of 650kHz generated by a signal generator 22 and further modulated by a power amplifier 21 with an amplitude of 80V is connected to both ends of the piezoelectric ceramic 11. The glass plate 13 to be cleaned is placed horizontally, and 4 150μL water droplets are placed side by side in front of the piezoelectric ceramic 11. It is measured that the cleaning device completes the cleaning work on the glass surface in 15s.

[0059] Please refer to Figure 2 ,the droplet 14 moves along the direction of ultrasonic wave propagation on the glass plate 13 to be cleaned. The ultrasonic wave refracts into the droplet 14 at a specific angle and forms a vortex inside it. At the same time, the dust particles 16 inside the droplet 14 are collected.

[0060] Please refer to Figure 3 ,the dust particles 16 inside the droplet 14 are simultaneously subjected to the gravity acting vertically downward on itself, the buoyancy of the droplet 14 acting vertically upward, the acoustic radiation force along the direction of the sound pressure gradient, and the acoustic streaming drag force along the direction of the acoustic flow.

[0061] Example 2:

[0062] 1) The glass plate 13 to be cleaned is a photovoltaic glass cover plate 31, with a length of 600mm, a width of 400mm, and a thickness of 8mm. The surface of the photovoltaic glass cover plate 31 is cleaned successively with clean water, acetone, and absolute ethanol.

[0063] 2) The stains on the surface of the photovoltaic glass cover plate 31 are the residues deposited after the evaporation of muddy water. After mixing the dust particles collected near the photovoltaic power station and pure water evenly at a mass ratio of 1:10, it is evenly coated on the surface of the photovoltaic glass cover plate 31 and placed in a drying oven at 80° for 24 hours to obtain the photovoltaic glass cover plate 31 covered with the residual stains after the evaporation of muddy water. The coverage density of the stains is about 10 g / mm 2 .

[0064] 3) The selected ultrasonic transducer element is a PZT-5H type piezoelectric ceramic. The piezoelectric ceramic 11 is a rectangular strip with a length of 80 mm, a width of 12 mm, and a thickness of 2 mm. The piezoelectric ceramic 11 is welded with wires by the method of flanging electrodes.

[0065] 4) At the long-edge of the photovoltaic glass cover plate 31, 6 piezoelectric ceramics 11 are arranged linearly along the long-edge at uniform intervals. A thin layer of ultraviolet-curing glue is applied on the piezoelectric ceramics 11 and then bonded to the glass plate 13 to be cleaned. Then, it is irradiated with an ultraviolet-curing lamp for 30 minutes to make the thickness of the cured glue less than 0.1 mm, thus obtaining the cleaning device.

[0066] 5) An impedance analyzer 23 is used to measure the resonant frequency of the prepared cleaning device. 270 kHz is selected as its resonant frequency. An AC voltage signal with a frequency of 270 kHz and an amplitude of 100 V is applied across the piezoelectric ceramic 11. The photovoltaic glass cover plate 31 is placed at an inclination of 30°. Six 100 μL water droplets are placed side by side in front of the piezoelectric ceramic 11. It is measured that the cleaning device completes the cleaning of the glass surface in 30 s.

[0067] Please refer to Figure 4 , the device for cleaning the photovoltaic panel cover glass by ultrasonic driving droplets in Embodiment 2 of the present invention is composed of a piezoelectric ceramic 11, a photovoltaic glass cover plate 31, electrode leads 32, an insulating photovoltaic panel frame 33, and a solar cell 34.

[0068] Figure 5 is the influence curve of different voltages on the movement characteristics of droplets on the glass surface under different embodiment conditions. It can be seen from the figure that as the excitation voltage signal increases, the movement speed of the droplets increases and the cleaning speed gradually becomes faster.

[0069] Figure 6 is the influence curve of different droplet volumes on the movement characteristics of droplets on the glass surface under different embodiment conditions. It can be seen from the figure that as the droplet volume increases, the movement speed of the droplets first increases and then decreases, and the change trend of the cleaning speed is the same.

[0070] Embodiment 3:

[0071] 1) The surface of the glass plate 13 to be cleaned is a curved glass plate serving as a condenser mirror. Its length is 1700 mm, width is 1500 mm, and thickness is 4 mm. The surface of the curved glass plate is cleaned successively with clean water, acetone, and absolute ethanol.

[0072] 2) The stains on the surface of the curved glass plate are mud, and the dust particles come from the dust deposition in the air. They are obtained by naturally depositing on the glass surface in the outdoor environment for 15 days. The particle size distribution is in the range of 2 μm - 100 μm, and the coverage density of the dust particles is about 20 g / mm 2 .

[0073] 3) The selected ultrasonic transducer element is a PZT - 4 type piezoelectric ceramic. The piezoelectric ceramic 11 is a rectangular strip with a length of 70 mm, width of 10 mm, and height of 1.5 mm. The piezoelectric ceramic 11 is welded with wires by the method of flanging electrodes.

[0074] 4) At the long - side edge of the curved glass plate, AB glue is thinly coated on the piezoelectric ceramic 11 and bonded to the glass plate, and then placed at room temperature for 120 min, so that the thickness of the cured glue is less than 0.1 mm, obtaining a cleaning device.

[0075] 5) An impedance analyzer 23 is used to measure the resonant frequency of the prepared cleaning device. 400 kHz is selected as its resonant frequency, and an AC voltage signal with a frequency of 400 kHz and an amplitude of 180 V is applied across the piezoelectric ceramic 11. The curved glass plate is placed horizontally, and 5 water droplets of 90 μL are placed side by side in front of the piezoelectric ceramic 11. It is measured that the cleaning device completes the cleaning work of the glass surface in 15 s.

[0076] In the above - mentioned embodiments, the descriptions of each embodiment have their own focuses. For the parts not detailed or recorded in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0077] The above - mentioned embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of each embodiment of the present application, and should all be included within the protection scope of the present application.

Claims

1. A device for cleaning glass surfaces using ultrasonically driven droplets, characterized in that: include: The piezoelectric ceramic (11) selects a corresponding resonance frequency according to the geometric dimensions, acoustic parameters and the type of stains covering the surface of the glass plate (13) to be cleaned; An adhesive layer (12) for fixing the piezoelectric ceramic (11) on the surface of the glass plate (13) to be cleaned; An impedance analyzer (23) is used to measure the overall resonant frequency of the piezoelectric ceramic (11), the adhesive layer (12) and the glass plate to be cleaned (13); The signal generator (22) is connected to the piezoelectric ceramic (11) via the power amplifier (21), and selects an AC voltage signal for exciting the piezoelectric ceramic (11) according to the resonant frequency and impedance characteristics measured by the impedance analyzer (23), and performs cleaning by using the droplets (14) generated on the surface of the glass plate (13) to be cleaned, so that the droplets (14) can collect dust on the surface of the glass plate (13) to be cleaned in a direction along the propagation direction of the ultrasonic wave generated by the piezoelectric ceramic (11) and leave the surface.

2. The device for cleaning glass surface by using ultrasonic driven droplets according to claim 1, characterized in that: The glass plate (13) to be cleaned is soda-lime glass or tempered glass, and the wavelength of the ultrasonic wave generated by the piezoelectric ceramic (11) matches the thickness of the glass plate (13) to be cleaned; if the glass plate (13) to be cleaned is a curved surface, the radius of curvature of the glass plate (13) to be cleaned is greater than the wavelength of the ultrasonic wave generated by the piezoelectric ceramic (11).

3. The device for cleaning glass surface by using ultrasonic driven droplets according to claim 1, characterized in that: The dust on the surface of the glass plate (13) to be cleaned is dry dust or dust containing water, mud, stains remaining after the evaporation of mud and water, and organic matter, and the coverage density of the dust particles (16) is 0.1 g / mm 2 ~50g / mm 2 .

4. The device for cleaning glass surface by using ultrasonic driven droplets according to claim 1, characterized in that: The piezoelectric ceramic (11) is lead zirconate titanate PZT piezoelectric ceramic, and its models include PZT-4, PZT-5H, PZT-5A and PZT-8.

5. The device for cleaning glass surface by using ultrasonic driven droplets according to claim 1, characterized in that: The piezoelectric ceramic (11) is bonded to the glass plate (13) to be cleaned at the edge of the front or back side of the glass plate. The bonding layer (12) is formed by ultraviolet curing glue or AB glue. The thickness of the bonding layer (12) is less than 0.1 mm.

6. The device for cleaning glass surface by using ultrasonic driven droplets according to claim 1, characterized in that: The impedance analyzer (23) selects a frequency that meets the resonance requirements in the range of 20kHz to 1MHz as the resonance frequency, and the signal generator (22) selects an AC voltage signal amplitude of 10V to 380V to excite the piezoelectric ceramic (11) through the power amplifier (21).

7. The device for cleaning glass surface by using ultrasonic driven droplets according to claim 1, characterized in that: After the adhesive layer (12) fixes the piezoelectric ceramic (11) on the surface of the glass plate (13) to be cleaned, the glass plate (13) to be cleaned is inclined at an angle of -90° to 90° with the horizontal plane or is placed horizontally; the volume of the droplets (14) generated on the surface of the glass plate (13) to be cleaned is 5 μL to 200 μL, and is formed by spraying, water spraying or natural condensation.

8. A method for cleaning a glass surface by using ultrasonically driven droplets, characterized in that: include: Acquiring the geometrical dimensions, acoustic parameters and the type of stains covering the surface of the glass plate (13) to be cleaned, and selecting the resonant frequency of the piezoelectric ceramic (11) according to the geometrical dimensions, acoustic parameters and the type of stains covering the surface of the glass plate (13) to be cleaned; Fixing the selected piezoelectric ceramic (11) on the surface of the glass plate (13) to be cleaned according to the corresponding resonance frequency; An impedance analyzer (23) is used to measure the overall resonance frequency of the glass plate (13) to be cleaned, and an AC voltage signal for exciting the piezoelectric ceramic (11) is selected based on the resonance frequency and impedance characteristics measured by the impedance analyzer (23); The piezoelectric ceramic (11) is operated, and the liquid droplets (14) generated on the surface of the glass plate (13) to be cleaned are used for cleaning, so that the liquid droplets (14) can collect dust on the surface of the glass plate (13) to be cleaned in a direction along the propagation direction of the ultrasonic wave generated by the piezoelectric ceramic (11) and leave the surface.

9. The method for cleaning glass surface by using ultrasonically driven droplets according to claim 8, characterized in that: The piezoelectric ceramic (11) has a rectangular parallelepiped structure with a length of 1 mm to 200 mm, a width of 1 mm to 100 mm, and a thickness of 1 mm to 10 mm; the piezoelectric ceramic (11) is welded with a wire by a flanging electrode or a double-sided electrode method.

10. The method for cleaning glass surface by using ultrasonically driven droplets according to claim 8, characterized in that: The dust particles (16) on the surface of the glass plate (13) to be cleaned are simultaneously subjected to their own vertical downward gravity, the vertical upward buoyancy of the droplets (14), the acoustic radiation force along the direction of the acoustic pressure gradient, and the acoustic flow drag force along the direction of the acoustic flow.

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