Smoke barrier structure of range hood and range hood

Abstract

The smoke barrier comprises a smoke barrier body and is characterized in that a piezoelectric thin film layer is attached to the surface of the smoke barrier body, an interdigital electrode layer is further attached to the outer surface of the piezoelectric thin film layer, a detection mode is built in an MCU controller, and in the detection mode, the piezoelectric thin film layer is connected with the interdigital electrode layer. The MCU controller applies alternating current to the interdigital electrode layer to enable the interdigital electrode layer to form an alternating electric field, the MCU controller collects displacement current I of the piezoelectric film layer, detects and processes a phase abrupt change point of the displacement current I by using the lock-in amplifier, and obtains resonant frequency offset delta f and quality factor decline delta Q; and if the ratio of the resonant frequency offset delta f to the quality factor decline delta Q at a certain moment is 0.6-0.8, the MCU controller judges that accumulated water exists on the surface of the smoke barrier at the moment. Compared with the prior art, the smoke barrier can detect whether water drops are condensed on the surface of the smoke barrier.

Description

Technical Field

[0001] The invention relates to a smoke baffle structure of a range hood and the range hood. Background Art

[0002] Range hoods are essential appliances for daily cooking, and range hoods with smoke dampers have become increasingly popular in recent years. However, cooking gases typically contain water vapor in addition to oil smoke. This is especially true during steaming, where high levels of water vapor are more likely to condense on the lower surface of the smoke damper. Steaming is more prone to generating water vapor than frying. However, in steaming mode, users often choose a medium or low fan setting due to concerns about smoke concentration and noise. Range hoods are installed above cooking stoves and pots. Rising smoke and water vapor easily condense on the range hood's smoke damper, potentially affecting the user experience. These droplets can also easily drip into the pot, impacting the user experience, or condense on the damper or panel, hindering user interaction with buttons. Therefore, existing technology requires further improvement. Summary of the Invention

[0003] The first technical problem to be solved by the present invention is to provide a range hood smoke baffle structure capable of detecting whether there is water droplet condensation on the surface of the smoke baffle in response to the above-mentioned prior art.

[0004] The second technical problem to be solved by the present invention is to provide a range hood that can detect whether there is water droplet condensation on the surface of the smoke baffle and can heat the accumulated water to evaporate it, in response to the above-mentioned prior art.

[0005] The technical solution adopted by the present invention to solve the first technical problem mentioned above is: a smoke shield structure of a range hood, including a smoke shield body, characterized in that: a piezoelectric film layer is adhered to the surface of the smoke shield body, and an interdigitated electrode layer is also adhered to the outer surface of the piezoelectric film layer, the piezoelectric film layer is electrically connected to a signal output end, the interdigitated electrode layer is electrically connected to a signal input end, the signal input end electrically connected to the interdigitated electrode layer and the signal output end electrically connected to the piezoelectric film layer are electrically connected to an MCU controller, and the MCU controller has a built-in detection mode. In the detection mode, the MCU controller applies alternating current to the signal input end electrically connected to the interdigitated electrode layer so that the interdigitated electrode layer forms an alternating electric field, and the MCU controller collects the signal through the signal output end electrically connected to the piezoelectric film layer. The displacement current I of the piezoelectric film layer under the action of the alternating electric field and condensed water is detected by a phase mutation point of the displacement current I using a phase-locked amplifier to determine the real-time resonant frequency f1. At the same time, the real-time quality factor Q1 is calculated using the frequency width when the amplitude of the displacement current I drops to a preset value. The real-time resonant frequency f1 is subtracted from the preset initial resonant frequency f0 to obtain the resonant frequency offset Δf. The real-time quality factor Q1 is subtracted from the preset initial quality factor Q0 to obtain the quality factor decrease ΔQ. The ratio of the resonant frequency offset Δf to the quality factor decrease ΔQ is then calculated. If the ratio of the resonant frequency offset Δf to the quality factor decrease ΔQ at a certain moment is between 0.6 and 0.8, the MCU controller determines that there is water on the surface of the smoke shield at this time.

[0006] As an improvement, the calculation formula of the real-time quality factor Q1 is:

[0007] Q1=f1 / Δf -a

[0008] where Δf -a It is the frequency width when the amplitude of displacement current I drops to a preset value a, and the value range of a is 2dB to 4dB.

[0009] As a further improvement, a heating film layer is provided between the piezoelectric film layer and the surface of the smoke shield body. The heating film layer is electrically connected to an input end, and the input end of the heating film layer is electrically connected to the MCU controller. When the MCU controller determines that there is water accumulation on the surface of the smoke shield and the accumulated water accumulation over a period of time exceeds the preset water accumulation amount, the heating film layer is started for electrical heating.

[0010] As a further improvement, the surface of the smoke barrier body is divided into multiple areas, and the surface of each area is provided with an independently controllable heating film layer, a piezoelectric film layer and an interdigitated electrode layer; the signal input end of the interdigitated electrode layer in each area is electrically connected to the MCU controller and is independently controlled by the MCU controller, and the signal output end of the piezoelectric film layer in each area is electrically connected to the MCU controller. The MCU controller can independently collect the displacement current I output by the signal output end of the electric film layer in each area, and process it independently, so as to determine whether there is water accumulation on the surface of the smoke barrier in this area. The input end of the heating film layer in each area is also electrically connected to the MCU controller. When the MCU controller determines that there is water accumulation in a certain area on the surface of the smoke barrier, and the accumulated water volume over a period of time exceeds the preset water volume, the heating film layer in this area is started for electrical heating.

[0011] As a further improvement, the MCU controller integrates the resonant frequency offset Δf of a certain area over a certain period of time to calculate the cumulative amount of water accumulated in a certain area over a certain period of time, and the specific calculation formula is as follows:

[0012] W(t)=∫0 t Δf(τ)·e -0.1(t-τ) dτ

[0013] Where t is the time parameter, e -0.1(t-τ) is the attenuation factor.

[0014] Further improved, the MCU controller calculates the airflow velocity v passing through the surface of the smoke baffle by the following formula:

[0015]

[0016] Wherein, Δβ=β-β0, β is equal to the frequency width when the amplitude of the displacement current I drops to a preset value, β0 is a preset value, and β0=5 Hz.

[0017] The technical solution adopted by the present invention to solve the first technical problem mentioned above is: a range hood, including a body, a fan system is provided in the body, an inlet is provided on the body, and a smoke baffle is connected to the inlet of the body, characterized in that the structure of the smoke baffle adopts a smoke baffle with the above-mentioned structure.

[0018] An electric control board is provided in the machine body, the MCU controller is integrated in the electric control board of the machine body, and the fan system is electrically connected to the electric control board.

[0019] The electric control board adjusts the speed n of the fan system through the formula, and the unit of speed n is rpm;

[0020] n=n0+A*W+B*v,

[0021] Among them, n0, A, and B are all preset constants, W is the sum of the water accumulation in all areas of the smoke baffle surface within a certain period of time; and v is the airflow velocity on the smoke baffle surface.

[0022] Compared with the prior art, the advantages of the present invention are: by adding a piezoelectric film layer and an interdigital electrode layer on the surface of the smoke shield, using the MCU controller to apply alternating current to the interdigital electrode layer to form an alternating electric field in the interdigital electrode layer, and detecting the displacement current I of the piezoelectric film layer, and obtaining the resonant frequency offset Δf and the quality factor decrease ΔQ, and using the ratio of the resonant frequency offset Δf to the quality factor decrease ΔQ to detect whether water accumulates on the surface of the smoke shield, thereby improving the user's cooking experience; in the improved scheme, when the MCU controller determines that there is water accumulation on the surface of the smoke shield, it starts the heating film layer to perform electric heating to eliminate the water accumulation, thereby integrating the dual functions of water accumulation detection and electric heating evaporation; at the same time, in the improved scheme, the airflow velocity on the surface of the smoke shield can also be detected, realizing the multi-functional application of the sensor and improving the scene adaptability. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a partial cross-sectional view of a certain area of ​​the smoke shield in an embodiment of the present invention.

[0024] Figure 2 Schematic diagram of the structure of the interdigitated electrode in an embodiment of the present invention.

[0025] Figure 3 Schematic diagram of the displacement current I amplitude and frequency curve in an embodiment of the present invention.

[0026] Figure 4 Schematic diagram of the structure of oil fume suction in an embodiment of the present invention. DETAILED DESCRIPTION

[0027] The present invention will be described in further detail below with reference to the accompanying drawings and embodiments.

[0028] This embodiment first provides a smoke shield structure for a range hood, which includes a smoke shield body 1. The surface of the smoke shield body 1 is divided into multiple areas according to the size of the surface of the smoke shield body 1. A heating film layer 2 is provided on the surface of each area. A piezoelectric film layer 3 is attached to the surface of the heating film layer 2. The outer surface of the piezoelectric film layer 3 is also attached to the interdigital electrode layer 4. Figure 1 A partial cross-sectional view of a certain area of ​​the middle smoke shield. In this embodiment, the piezoelectric film can be made of ALN aluminum nitride, and the interdigital electrode structure is as follows Figure 2As shown, it has two interdigitated electrodes, which are the signal input ends of the interdigitated electrode layer. The heating film layer, piezoelectric film layer and interdigitated electrode layer on the surface of each area are independent of each other, and the piezoelectric film layer in each area is electrically connected to a signal output end, the interdigitated electrode layer in each area is electrically connected to a signal input end, and the heating film layer in each area is electrically connected to a signal input end; the signal input end of the interdigitated electrode layer in each area is electrically connected to the MCU controller and independently controlled by the MCU controller, and the signal output end of the piezoelectric film layer in each area is electrically connected to the MCU controller. The MCU controller can independently collect the displacement current I output by the signal output end of the piezoelectric film layer in each area and process it independently to determine whether there is water accumulation on the surface of the smoke barrier in that area. The input end of the heating film layer in each area is also electrically connected to the MCU controller. When the MCU controller determines that there is water accumulation in a certain area on the surface of the smoke barrier and the accumulated water accumulation over a period of time exceeds the preset water accumulation amount, the heating film layer in that area is activated for electrical heating.

[0029] In an embodiment of the present invention, the piezoelectric film is used as a miniature tuning fork. When water droplets condense on the surface of the film, it is equivalent to adding weight to the tuning fork (changing the vibration frequency). At the same time, the viscosity of the water will cause the tuning fork to stop vibrating more quickly (reducing the vibration persistence). By simultaneously monitoring these two changes, it is possible to accurately determine whether it is water droplet condensation or oil stain adhesion. When wind blows over the tuning fork (corresponding to the airflow at the lower end of the range hood smoke shield), the vibration of the tuning fork will become unstable (increasing the spectrum broadening β, corresponding to the bandwidth when the amplitude is reduced by 3dB). By measuring this degree of instability, the wind speed can be inferred.

[0030] In this embodiment, the MCU controller has a built-in detection mode. In the detection mode, the MCU controller detects whether there is water accumulation in a certain area in the following specific detection steps:

[0031] Step 1: The MCU controller applies alternating current to the signal input terminal of a certain area electrically connected to the interdigital electrode layer to form an alternating electric field in the interdigital electrode layer. The input signal can be a frequency-adjustable sinusoidal voltage V in (t) = V p sin(2πft), where Vp = peak voltage (typically 1-5V) and f is the sweep frequency (e.g., 12.6-13.0MHz, to cover the calibrated base of 12.8MHz). For example, if the frequency f is swept from low to high at 100Hz,

[0032] Step 2: The MCU controller collects the displacement current I of the piezoelectric film layer due to the alternating electric field and condensed water through the signal output terminal electrically connected to the piezoelectric film layer in the area;

[0033] Step 3: The MCU controller uses a lock-in amplifier to detect the phase mutation point of the displacement current I, thereby determining the real-time resonant frequency f1;

[0034] Step 4: Calculate the real-time quality factor Q1 using the frequency width when the amplitude of the displacement current I drops to a preset value:

[0035] Q1=f1 / Δf -a

[0036] where Δf -a The frequency width when the amplitude of the displacement current I drops to the preset value a, the value range of a is 2dB to 4dB, and the value of a in this embodiment is 3dB. -a =Δf -3db , see Figure 3 As shown;

[0037] Step 5: Subtract the preset initial resonant frequency f0 from the real-time resonant frequency f1 to obtain the resonant frequency offset Δf, and subtract the preset initial quality factor Q0 from the real-time quality factor Q1 to obtain the quality factor drop ΔQ; the initial resonant frequency f0 is generally set to 12.8 MHz, and the initial quality factor Q0 is generally about 800;

[0038] Step 6: Calculate the ratio of the resonant frequency offset Δf to the quality factor drop ΔQ. If the ratio is between 0.6 and 0.8 at a given moment, the MCU controller determines that water is present on the surface of that area of ​​the smoke shield. If the ratio is less than 0.6, particularly around 0.3, it can be determined that oil is present on the surface of that area. Generally, when Δf / ΔQ ≈ 0.7, it is determined that water is condensing in the current detection area, and if Δf / ΔQ ≈ 0.3, it is determined that oil is adhering.

[0039] In addition, the MCU controller can also calculate the airflow velocity v passing through the surface of the smoke baffle by the following formula:

[0040]

[0041] Wherein, Δβ=β-β0, β is equal to the frequency width when the amplitude of displacement current I drops to a preset value, that is, β=Δf -a , β0 is the preset value, β0=5Hz.

[0042] When airflow (velocity v) flows through the piezoelectric film, pressure fluctuations and turbulent vortex shedding are generated due to the fluid-solid coupling effect. The airflow disturbance causes the vibration phase to fluctuate randomly over time, affecting the spectrum broadening β. Therefore, the nonlinear relationship between the spectrum broadening β and the airflow velocity can be calibrated in the laboratory: β = 0.021v 1.36, β0 = 5 Hz was measured in the windless state, and the effective widening amount was Δβ = β-β0, so the airflow velocity v on the surface of the smoke baffle can be obtained.

[0043] The MCU controller integrates the resonant frequency offset Δf of a certain area over a certain period of time to calculate the cumulative amount of water accumulated in a certain area over a certain period of time, W(t). The specific calculation formula is as follows:

[0044] W(t)=∫0 t Δf(τ)·e -0.1(t-τ) dτ

[0045] Where t is the time parameter, e -0.1(t-τ) is the attenuation factor.

[0046] If the accumulated water volume W(t) in a certain area within a certain period of time is greater than the preset water volume W0, the heating film layer in the area is activated for electrical heating.

[0047] In addition, this embodiment also provides a range hood, see Figure 4 As shown, it includes a housing 101, a fan system disposed within housing 101, a fume inlet 102 disposed on housing 101, and a smoke deflector 1 having the aforementioned structure connected to fume inlet 102. An MCU controller is integrated into an electrical control board within housing 101. The fan system is electrically connected to the electrical control board. The electrical control board adjusts the fan system's speed n using the formula (where n is expressed in rpm).

[0048] n=n0+A*W+B*v,

[0049] Where n0, A, and B are all preset constants, W is the total amount of water accumulated on all areas of the smoke baffle surface over a certain period of time, and v is the airflow velocity on the smoke baffle surface. In this embodiment, n = 1500 + 80W + 50v.

[0050] This embodiment laminates a piezoelectric film (such as aluminum nitride (ALN)) layer and an interdigitated electrode layer onto the inner surface of the smoke shield glass. This layer can be divided into independently controlled areas based on the size of the smoke shield, and a heated film layer is placed in the corresponding locations. By improving the frequency-damping dual-mode sensing mechanism of the piezoelectric thin film resonator, this solution addresses the vulnerability of traditional single-parameter humidity detection to airflow disturbances. The solution achieves: 1. The ratio of the resonant frequency offset (Δf) to the quality factor drop (ΔQ) can distinguish between water condensation (Δf / ΔQ ≈ 0.7) and oil adhesion (Δf / ΔQ ≈ 0.3). 2. Based on the vibration mode coupling effect of the piezoelectric film in turbulent, high-Reynolds-number airflow, a mapping model is established between the vibration spectrum width β and the airflow velocity v, enabling simultaneous detection of airflow velocity. 3. By converting fluid dynamics disturbances into measurable spectral features, this solution achieves non-invasive wind speed detection, reducing costs by 60% and improving reliability compared to traditional solutions. ④ Based on the relationship between speed and detected condensed water, a composite control strategy for water accumulation W and flow rate v can be constructed, breaking through the limitations of single physical quantity control. This enables the multifunctional application of sensors, improving scenario adaptability and user cooking comfort.

Claims

1. A smoke baffle structure for a range hood, comprising a smoke baffle body, characterized in that: The surface of the smoke shield body is laminated with a piezoelectric film layer, and the outer surface of the piezoelectric film layer is also laminated with an interdigital electrode layer. The piezoelectric film layer is electrically connected to a signal output end, and the interdigital electrode layer is electrically connected to a signal input end. The signal input end electrically connected to the interdigital electrode layer and the signal output end electrically connected to the piezoelectric film layer are electrically connected to an MCU controller. The MCU controller has a built-in detection mode. In the detection mode, the MCU controller applies alternating current to the signal input end electrically connected to the interdigital electrode layer to form an alternating electric field in the interdigital electrode layer. The MCU controller collects the displacement current I of the piezoelectric film layer due to the alternating electric field and condensed water through the signal output end electrically connected to the piezoelectric film layer. A phase-locked amplifier is used to detect the phase mutation point of the displacement current I to determine the real-time resonant frequency f1. At the same time, the real-time quality factor Q1 is calculated using the frequency width when the amplitude of the displacement current I drops to a preset value. The real-time resonant frequency f1 is subtracted from the preset initial resonant frequency f0 to obtain the resonant frequency offset Δf. The real-time quality factor Q1 is subtracted from the preset initial quality factor Q0 to obtain the quality factor drop ΔQ. The ratio of the resonant frequency offset Δf to the quality factor drop ΔQ is then calculated. If the ratio of the resonant frequency offset Δf to the quality factor drop ΔQ at a certain moment is between 0.6 and 0.8, the MCU controller determines that there is water on the surface of the smoke shield at this time.

2. The smoke baffle structure of the range hood according to claim 1, characterized in that: The calculation formula of the real-time quality factor Q1 is: Q1=f1 / Δf -a where Δf -a It is the frequency width when the amplitude of displacement current I drops to a preset value a, and the value range of a is 2dB to 4dB.

3. The smoke baffle structure of the range hood according to claim 2, characterized in that: A heating film layer is also provided between the piezoelectric film layer and the surface of the smoke shield body. The heating film layer is electrically connected to an input end, and the input end of the heating film layer is electrically connected to the MCU controller. When the MCU controller determines that there is water accumulation on the surface of the smoke shield and the accumulated water accumulation over a period of time exceeds the preset water accumulation amount, the heating film layer is started for electrical heating.

4. The smoke baffle structure of the range hood according to claim 3, characterized in that: The surface of the smoke barrier body is divided into multiple areas, and the surface of each area is provided with a heating film layer, a piezoelectric film layer and an interdigitated electrode layer that can be independently controlled; the signal input end of the interdigitated electrode layer in each area is electrically connected to the MCU controller and is independently controlled by the MCU controller, and the signal output end of the piezoelectric film layer in each area is electrically connected to the MCU controller. The MCU controller can independently collect the displacement current I output by the signal output end of the electric film layer in each area, and process it independently to determine whether there is water accumulation on the surface of the smoke barrier in this area. The input end of the heating film layer in each area is also electrically connected to the MCU controller. When the MCU controller determines that there is water accumulation in a certain area on the surface of the smoke barrier, and the accumulated water volume over a period of time exceeds the preset water volume, the heating film layer in this area is started for electrical heating.

5. The smoke baffle structure of the range hood according to claim 4, characterized in that: The MCU controller integrates the resonant frequency offset Δf of a certain area over a certain period of time to calculate the cumulative amount of water accumulated in a certain area over a certain period of time, W(t). The specific calculation formula is as follows: Where t is the time parameter, e -0.1(t-τ) is the attenuation factor.

6. The smoke baffle structure of the range hood according to claim 4, characterized in that: The MCU controller calculates the airflow velocity v passing through the smoke baffle surface using the following formula: Wherein, Δβ=β-β0, β is equal to the frequency width when the amplitude of the displacement current I drops to a preset value, β0 is a preset value, and β0=5 Hz.

7. A range hood comprising a body, a fan system disposed within the body, an inlet disposed on the body, a smoke baffle connected to the inlet of the body, and characterized in that: The structure of the smoke shield adopts the smoke shield structure as claimed in claim 5.

8. The range hood according to claim 7, characterized in that: An electric control board is provided in the machine body, the MCU controller is integrated in the electric control board of the machine body, and the fan system is electrically connected to the electric control board.

9. The range hood according to claim 7, characterized in that: The electric control board adjusts the speed n of the fan system through the formula, and the unit of speed n is rpm; n=n0+A*W+B*v, Among them, n0, A, and B are all preset constants, W is the sum of the water accumulation in all areas of the smoke baffle surface within a certain period of time; and v is the airflow velocity on the smoke baffle surface.

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