An extractor hood and an intelligent control method thereof

Abstract

The application discloses an extractor hood and an intelligent control method thereof. The extractor hood comprises an air inlet assembly and a fan arranged above a ceiling of a kitchen. The fan comprises a volute and an impeller arranged in the volute. The impeller comprises blades. The blades are embedded with a piezoelectric fiber composite layer. The piezoelectric fiber composite layer comprises a sensing electrode area for detecting deformation of the blades and a driving electrode area for changing rigidity of the blades according to signals collected by the sensing electrode area.

Description

Technical Field

[0001] This invention relates to an oil fume purification device, and more particularly to a range hood and an intelligent control method for the range hood. Background Technology

[0002] Range hoods have become an indispensable kitchen appliance in modern homes. Installed above the stove, they quickly remove and exhaust the waste from the stove and the harmful fumes produced during cooking.

[0003] As users become increasingly focused on user experience, range hoods and cooktops are now paying more attention to noise reduction and concealed design during cooking, leading to the popularity of products with ceiling-mounted fan housings in recent years. On one hand, users of ceiling-mounted (split-type) products are generally more sensitive to noise. While these products reduce noise by housing the fan housing within the kitchen ceiling, making the perceived noise level slightly lower than that of a standard integrated range hood, the ceiling primarily isolates high-frequency noise (because higher frequencies have weaker penetration through obstacles), leaving mid-to-low frequencies unisolated. This alters the overall frequency response, resulting in a slightly strange sound compared to standard products. Therefore, some of these products are incorporating active noise cancellation measures to reduce low-frequency noise and further improve the user experience, as disclosed in Chinese patent applications 202220778031.X and 202220778038.1.

[0004] However, range hoods typically use multi-blade centrifugal fans with 48-80 blades, resulting in two key characteristics: 1) a higher blade passing frequency (BPF) compared to ordinary fans (5-18 blades); and 2) noise energy radiated by the impeller shifts towards mid-to-high frequencies, falling within the range most sensitive to human hearing (rather than the low-frequency band below 500Hz, which is easier to reduce with traditional active noise cancellation). Furthermore, traditional broadband noise reduction algorithms cannot accurately capture the harmonic groups generated by these densely packed blades, and the distance between the noise source of a traditional range hood and the human ear is too close, making it difficult for the reverse sound waves to cancel out slightly higher frequency noise. Therefore, ordinary active noise cancellation solutions are often ineffective in kitchen environments.

[0005] Furthermore, the actuators (microphones) used in traditional active noise cancellation are large and occupy valuable fluid channel space. Moreover, as diaphragm structures, they are easily contaminated by oil and require frequent maintenance or cleaning, further increasing the after-sales costs for users.

[0006] To address this, the applicant has developed a method to reduce vibration and thus noise by altering blade stiffness, as disclosed in Chinese Patent Application No. 201910703313.6. However, this method requires an external air supply pipe and air source, making it unsuitable for the confined space of ceiling-mounted range hoods. Furthermore, the through-hole structure of the blades is easily clogged by grease in oily fume environments, leading to failure. In addition, the air stiffness adjustment response is slow (due to gas flow inertia), and it can only suppress low-frequency vibrations of <500Hz, while offering no solution for high-frequency resonance.

[0007] Therefore, further improvements are needed. Summary of the Invention

[0008] The technical problem to be solved by the present invention is to address the shortcomings of the prior art by providing a range hood that improves noise reduction, provides a more comfortable and convenient cooking experience, and enhances adaptability to different scenarios.

[0009] The second technical problem to be solved by the present invention is to provide an intelligent control method for the above-mentioned range hood.

[0010] The technical solution adopted by the present invention to solve the first technical problem mentioned above is: a range hood, including an air intake assembly and a fan installed on the ceiling of the kitchen, the fan including a volute and an impeller installed in the volute, the impeller including blades; The blade is embedded with a piezoelectric fiber composite layer, which includes a sensing electrode region for detecting blade deformation and a driving electrode region for changing blade stiffness based on the signal collected by the sensing electrode region.

[0011] By embedding a piezoelectric fiber composite layer into the impeller blades of the ceiling-mounted range hood, the blade strain energy spectrum can be monitored in real time. The voltage applied to the piezoelectric fiber can be dynamically adjusted to actively regulate or change the equivalent stiffness of the blade. This can reduce the high-frequency resonance caused by the high-frequency harmonic groups that disrupt the passing frequency of the multi-blade fan blades due to slight local deformation under high-resistance conditions, thus achieving dominant vibration control. The reduced vibration also provides a certain degree of noise reduction. Moreover, the piezoelectric variable stiffness enables microsecond-level response, which can precisely disrupt the 1200-3000Hz high-frequency resonance (the core noise frequency band of multi-blade centrifugal fans). It also facilitates independent control of a single blade, directly sensing local strain through the piezoelectric fiber, eliminating the limitations of sensor installation space.

[0012] Furthermore, the piezoelectric fiber composite layer is installed at a location that is more prone to deformation, and the piezoelectric fiber composite layer is embedded in the leading and trailing edges of the blade, respectively.

[0013] Preferably, the piezoelectric fiber composite layer is a PZT fiber / SMA filament mixed woven layer, which automatically compensates for the influence of oil stains through the change of SMA resistance (without manual cleaning), and the performance degradation under oil stain conditions is <0.7dB.

[0014] Furthermore, an insulating strip is provided between the sensing electrode area and the driving electrode area.

[0015] Furthermore, the range hood also includes a main controller capable of receiving signals from the sensing electrode area and controlling the voltage applied to the driving electrode area.

[0016] The technical solution adopted by the present invention to solve the second technical problem mentioned above is: an intelligent control method for a range hood, using the range hood described above, characterized in that: the intelligent control method includes the following steps: 1) Power on, the fan starts at the preset speed, proceed to step 2); 2) Rotational speed signal acquisition: Acquire the fan's rotational speed signal (RPM); 3) Acquisition of piezoelectric raw signal: The charge quantity is acquired in the sensing electrode area of ​​the piezoelectric fiber composite layer. ; 4) Piezoelectric signal preprocessing: 4.1) First, a charge amplifier is used to convert the charge value into a voltage value: 4.2) Filter the voltage value obtained in 4.1): 5) Perform FFT processing on the voltage signal from step 4) to obtain the power spectrum. ; 6) Feature frequency extraction and risk assessment: 6.1) Based on the power spectrum Search for local maxima in the power spectrum ; 6.2) Calculate the theoretical blade fundamental frequency :

[0017] in, The number of leaves; 6.3) Setting the detection zone: , For a pre-set threshold; 6.4) If detected If a resonance risk is detected, control measures need to be triggered to change the blade stiffness and record the peak frequency. Proceed to step 7), if detected If no resonance risk is detected, no adjustment is needed, and the current voltage of the driving electrode region of the piezoelectric fiber composite layer is maintained. 7) Stiffness adjustment: 7.1) Target stiffness offset calculate:

[0018] 7.2) Perform zone control voltage mapping: The drive electrode region of the piezoelectric fiber composite layer is applied; in, The gain coefficient is pre-calibrated and is determined based on the system's dynamic response. The preferred value range is 0.3 to 1.0. If it is less than 0.3, the response will be slow; if it is greater than 1.0, it will cause the system to oscillate. The first natural frequency of the blade. This represents the initial stiffness of the blade. and The determination was made after blade 321 was manufactured. The Young's modulus of the piezoelectric fiber composite layer. The piezoelectric constant of the piezoelectric fiber composite layer is... and The determination is made after the piezoelectric limiting composite layer 34 is fabricated. for Cross-sectional area (the cross-sectional area perpendicular to the axis of the piezoelectric fiber), for thickness.

[0019] By embedding a piezoelectric fiber composite layer into the impeller blades of the ceiling-mounted range hood, the blade strain energy spectrum can be monitored in real time, and the voltage applied to the piezoelectric fiber can be dynamically adjusted to actively regulate or change the equivalent stiffness of the blade. This can reduce the high-frequency resonance caused by the high-frequency harmonic groups that disrupt the passing frequency of the multi-blade fan blade due to slight local deformation under high-resistance conditions, thus achieving dominant vibration control. The reduced vibration also provides a certain degree of noise reduction. Moreover, the piezoelectric variable stiffness achieves microsecond-level response, which can precisely disrupt the 1200-3000Hz high-frequency resonance (the core noise frequency band of multi-blade centrifugal fans). Experiments show that the BPF noise peak is reduced by 8.5dB.

[0020] Preferably, step 5) includes the following steps: 5.1) Sampling discretization: 5.2) Window addition treatment:

[0021] in, The length of the Hanning window; 5.3) FFT calculation: 5.4) Power Spectrum estimate: Preferably, in step 3.2), the passband of the filter is .

[0022] Preferred, The maximum value is .

[0023] Compared with existing technologies, the advantages of this invention are as follows: By embedding a piezoelectric fiber composite layer into the impeller blades of the ceiling-mounted range hood, the blade strain energy spectrum can be monitored in real time, and the voltage applied to the piezoelectric fiber can be dynamically adjusted to actively regulate or change the equivalent stiffness of the blade. This can reduce the high-frequency resonance caused by the high-frequency harmonic groups disrupting the passing frequency of the multi-blade fan blade due to slight local deformation under high-resistance conditions, thus achieving dominant vibration control. The reduced vibration also provides a certain degree of noise reduction. Moreover, the piezoelectric variable stiffness achieves microsecond-level response, which can precisely disrupt the 1200-3000Hz high-frequency resonance (the core noise frequency band of multi-blade centrifugal fans). Experiments show that the BPF noise peak is reduced by 8.5dB. It also facilitates independent control of a single blade, directly sensing local strain through the piezoelectric fiber, eliminating the limitations of sensor installation space. Attached Figure Description

[0024] Figure 1 This is a front view of the range hood in use after installation, according to an embodiment of the present invention.

[0025] Figure 2 This is a side view of the range hood in its installed and usable state according to an embodiment of the present invention;

[0026] Figure 3 This is a cross-sectional side view of a range hood according to an embodiment of the present invention;

[0027] Figure 4 This is a cross-sectional view of the impeller blades of the range hood according to an embodiment of the present invention;

[0028] Figure 5 This is a schematic diagram of the power supply of the piezoelectric fiber composite layer of the impeller of the range hood according to an embodiment of the present invention;

[0029] Figure 6 This is a hardware principle block diagram of a range hood according to an embodiment of the present invention;

[0030] Figure 7 This is a flowchart of the active noise reduction control method for a range hood according to an embodiment of the present invention;

[0031] Figure 8 This is a flowchart illustrating the risk assessment process in the active noise reduction control method for a range hood according to an embodiment of the present invention. Detailed Implementation

[0032] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0033] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Since the embodiments disclosed in this invention can be arranged in different directions, these terms indicating direction are only for illustration and should not be regarded as limitations. For example, "upper" and "lower" are not necessarily limited to directions opposite to or consistent with the direction of gravity. In addition, features defined with "first" and "second" may explicitly or implicitly include one or more of such features.

[0034] See Figures 1-4 A range hood includes an air inlet assembly 1, a fan housing 2 mounted above a suspended ceiling 100 in the kitchen, a fan 3 housed within the fan housing 2, a connecting duct 4 connecting the air inlet assembly 1 and the fan housing 2, and an air outlet mask 5 mounted at the air outlet of the fan 3. The air inlet assembly 1 includes a smoke inlet 11. The air inlet assembly 1 can be flush with a wall cabinet 200 below the suspended ceiling 100, can be exposed below the wall cabinet 200, or can only be exposed below the wall cabinet 200 during operation. The connecting duct 4 can be a flexible hose to allow adjustment of the position of the fan housing 2 and the air inlet assembly 1 during installation.

[0035] The fan housing 2 is hung on the floor slab 300 at the top of the room. It can be fixed to the fan housing 2 and the floor slab 300 respectively by hooks to achieve the hanging. How to hoist it is the prior art in this field and will not be described in detail here. For reference, please refer to the applicant's Chinese patent application number 202221537478.4.

[0036] The fan 3 includes a volute 31, an impeller 32 disposed within the volute 31, and a motor 33 for driving the impeller 32. The impeller 32 includes multiple blades 321, each blade 321 having a piezoelectric fiber composite layer 34 embedded in its leading edge at the air inlet and its trailing edge at the air outlet (these two positions are subject to greater stress and are prone to deformation), enabling sensing and actuation. The piezoelectric fiber composite layer 34 can optionally be a PZT fiber / SMA filament hybrid braided layer, with the PZT fiber (lead zirconate titanate fiber) having a diameter of 100 μm (e.g., piezoelectric constant d33 = 650 pC / N) and the SMA (nickel-titanium alloy) filament having a diameter of 50 μm (phase transition temperature 90°C), and then externally encapsulated with epoxy resin.

[0037] The piezoelectric fiber composite layer 34 exhibits the following piezoelectric effects: mechanical strain → charge output → used as a sensor; and the inverse piezoelectric effect: driving voltage input → mechanical deformation → used as an actuator, which can change the equivalent stiffness of the blade. In other words, the piezoelectric fiber composite layer 34 is used to monitor the strain energy spectrum of the blade 321 in real time (sensor). By dynamically adjusting the voltage applied to the piezoelectric fiber composite layer 34, the equivalent stiffness of the blade 321 can be actively adjusted or changed (actuator). This can reduce the high-frequency resonance caused by the high-frequency harmonic groups disrupting the passing frequency (BPF) of the multi-blade wind turbine blade due to slight local deformation of the blade 321 under high drag conditions. Details will be provided below.

[0038] Considering that piezoelectric materials cannot operate simultaneously in power supply and charge acquisition modes, a zoned arrangement is necessary. The piezoelectric fiber composite layer 34 can be divided into a sensing electrode region 341 and a driving electrode region 342. The sensing electrode region 341 can occupy approximately 30% of the entire piezoelectric fiber composite layer 34, preferably near the center. It monitors the strain energy spectrum of the blade 321 and can have a charge amplification circuit to improve detection sensitivity and accuracy. The remaining 70% of the area serves as the driving electrode region 342, which can have a high-voltage driving circuit for input and voltage adjustment. The sensing electrode region 341 and the driving electrode region 342 are controlled separately, and an insulating strip 343 needs to be placed between them.

[0039] See Figure 6 The range hood of this embodiment also includes a main controller 6, which has a processor. The fan drive module 61 and the array formed by the piezoelectric fiber composite layers 34 of each blade 321 are electrically connected to the main controller 6. Furthermore, the main controller 6 may also be electrically connected to a switch module 62 and a storage module 63, which are identical to those in the prior art. The main controller 6 can also connect to other optional modules, such as a lighting module and a communication module connected to the Internet of Things.

[0040] The driving electrode region 342 of the piezoelectric fiber composite layer 34 is powered, and can employ common rotating component power supply methods, such as contact slip rings or non-contact methods such as electromagnetic induction power supply / magnetic resonance coupling. See [link to relevant documentation] Figure 5 In this embodiment, a non-contact method is adopted, that is, a wireless transmitting coil and a wireless receiving coil are used. The output of the main controller 6 is output to the wireless transmitting coil (which can be set on the inner wall of the volute 31) after passing through a high-frequency inverter. The wireless receiving coil (which can be set on the rotating shaft of the impeller 32) receives the electromagnetic induction signal sent by the wireless transmitting coil, and then sends it to the drive electrode area 342 after passing through a frequency doubling rectifier circuit, an energy storage capacitor, and a high-voltage switch distributor.

[0041] See Figure 7 The active noise reduction intelligent control method of the present invention includes the following steps:

[0042] 1) Turn on the machine and the fan will start at the preset speed. Select either smart mode or manual mode for the range hood. If you select smart mode, proceed to step 2). If you select manual mode, you will then operate the machine manually. Alternatively, you can skip this step and proceed directly to step 2 after turning on the machine.

[0043] 2) Speed ​​signal acquisition: Acquire the speed signal RPM of fan 3. The PSMS or BLDC motor drive module commonly used in range hoods has speed information itself, so this speed information can be directly acquired. This signal provides the characteristics of the aerodynamic noise fundamental frequency source of the range hood. If the motor itself does not have this information, some existing methods can be used to detect the motor speed, such as the back EMF method or using an encoder. These are conventional techniques and will not be elaborated here.

[0044] 3) Acquisition of piezoelectric raw signal: The sensing electrode region 341 of the piezoelectric fiber composite layer 34 acquires the charge signal. The principle of the aforementioned sensing electrode region 341 is as follows: under high-drag conditions, the slight local deformation of the blade 321 causes high-frequency harmonic groups to disrupt the passing frequency (BPF) of the multi-blade wind turbine blade, resulting in high-frequency resonance. The micro-strain ε caused by the aerodynamic load on the blade 321 is detected by the piezoelectric fiber in the sensing electrode region 341, and the electrode charge of the sensing electrode region 341 is obtained according to the piezoelectric equation. (That is, this value is the directly acquired value. The piezoelectric equation is intended to explain the principle. t is the real-time running time of the system, in seconds. It represents the continuous time axis of signal generation.)

[0045] The meanings of the parameters in the above equations are shown in Table 1 below:

[0046]

[0047] Table 1: Meaning of parameters in the piezoelectric equation

[0048] 4) Piezoelectric signal preprocessing:

[0049] 4.1) First, a charge amplifier is used to convert the charge value into a voltage value (converting a picocoometer-level charge into a millivolt-level voltage):

[0050] 4.2) Filter the voltage value obtained in 4.1):

[0051] Therefore, by using bandpass filtering The 321 resonant frequency band of the blades is retained, and electromagnetic interference from the motor is eliminated;

[0052] 5) Time-frequency conversion (FFT analysis):

[0053] 5.1) Sampling discretization:

[0054] 5.2) Window addition treatment:

[0055] in, The length of the Hanning window is 1024 in this embodiment, thereby reducing spectral leakage by adding the Hanning window;

[0056] 5.3) FFT calculation:

[0057] 5.4) Power Spectrum estimate: This yields the one-sided power spectrum;

[0058] 6) Feature frequency extraction (peak detection) and risk assessment:

[0059] In this step, combined Figure 8 It includes the following steps:

[0060] 6.1) Based on the power spectrum Search for local maxima in the power spectrum ;

[0061] 6.2) Calculate the theoretical blade fundamental frequency :

[0062]

[0063] in This refers to the number of blades 321;

[0064] 6.3) Setting the detection zone: , For a pre-set threshold, calibration is performed in advance through experiments, and its maximum value can be as follows: ;

[0065] 6.4) If detected If a resonance risk is detected, control measures need to be triggered to change the blade stiffness and record the peak frequency. Proceed to step 7), if detected If there is no risk of resonance, no adjustment is needed, and the current voltage of the driving electrode region 342 of the piezoelectric fiber composite layer 34 is maintained.

[0066] 7) Stiffness adjustment:

[0067] 7.1) Stiffness offset calculation: Based on the frequency response characteristics of the spring-mass system, the target stiffness offset is obtained. :

[0068]

[0069] Physical meaning: Based on the frequency response characteristics of the spring-mass system

[0070] 7.2) Perform zone control voltage mapping:

[0071] The drive electrode region 342 of the piezoelectric fiber composite layer 34 is applied;

[0072] In this step, the meanings of the parameters in the two formulas above are shown in Table 2 below:

[0073]

[0074] Table 2: Meaning of each parameter for stiffness adjustment.

Claims

1. A range hood, comprising an air intake assembly (1) and a fan (3) mounted on a ceiling (100) in a kitchen, the fan (3) comprising a volute (31) and an impeller (32) disposed within the volute (31), the impeller (32) comprising blades (321); Its features are: The blade (321) is embedded with a piezoelectric fiber composite layer (34), which includes a sensing electrode region (341) for detecting the deformation of the blade (321) and a driving electrode region (342) for changing the stiffness of the blade (321) according to the signal collected by the sensing electrode region (341).

2. The range hood according to claim 1, characterized in that: The piezoelectric fiber composite layer (34) is embedded in the leading and trailing edges of the blade (321).

3. The range hood according to claim 1, characterized in that: The piezoelectric fiber composite layer (34) is a PZT fiber / SMA filament mixed braided layer.

4. The range hood according to any one of claims 1 to 3, characterized in that: An insulating strip (343) is provided between the sensing electrode region (341) and the driving electrode region (342).

5. The range hood according to any one of claims 1 to 3, characterized in that: The range hood also includes a main controller (6) capable of receiving signals from the sensing electrode area (341) and controlling the voltage applied to the driving electrode area (342).

6. A smart control method for a range hood, employing the range hood as described in claim 5, characterized in that: The intelligent control method includes the following steps: 1) Power on, the fan (3) starts at the preset speed, proceed to step 2); 2) Speed ​​signal acquisition: Acquire the speed signal RPM of the fan (3); 3) Acquisition of piezoelectric raw signal: The sensing electrode area (341) of the piezoelectric fiber composite layer (34) collects the charge quantity. ; 4) Piezoelectric signal preprocessing: 4.1) First, a charge amplifier is used to convert the charge value into a voltage value: 4.2) Filter the voltage value obtained in 4.1): 5) Perform FFT processing on the voltage signal from step 4) to obtain the power spectrum. ; 6) Feature frequency extraction and risk assessment: 6.1) Based on the power spectrum Search for local maxima in the power spectrum ; 6.2) Calculate the theoretical blade fundamental frequency : in, The number of leaves (321); 6.3) Setting the detection zone: , For a pre-set threshold; 6.4) If detected If a resonance risk is detected, control measures need to be triggered to change the blade stiffness and record the peak frequency. Proceed to step 7), if detected If there is no risk of resonance, no adjustment is needed, and the current voltage of the driving electrode region (342) of the piezoelectric fiber composite layer (34) is maintained. 7) Stiffness adjustment: 7.1) Target stiffness offset calculate: 7.2) Perform zone control voltage mapping: The driving electrode region (342) of the piezoelectric fiber composite layer (34) is applied; in, For the pre-calibrated gain coefficient, The first natural frequency of the blade (321) is... The initial stiffness of the blade (321) is... The Young's modulus of the piezoelectric fiber composite layer (34) is... The piezoelectric constant of the piezoelectric fiber composite layer (34) is... for Cross-sectional area for thickness.

7. The intelligent control method for a range hood according to claim 6, characterized in that: step 5) includes the following steps: 5.1) Sampling discretization: 5.2) Window addition treatment: in, The length of the Hanning window; 5.3) FFT calculation: 5.4) Power Spectrum estimate:

8. The intelligent control method for a range hood according to claim 6, characterized in that: In step 3.2), the passband of the filter is .

9. The intelligent control method for a range hood according to claim 6, characterized in that: The maximum value is .

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