Range hood and cleaning control method

Abstract

The invention discloses an extractor hood and a cleaning control method, the extractor hood comprises a centrifugal fan, the centrifugal fan comprises a volute and an impeller arranged in the volute, and the impeller comprises blades; the capacitance detection module can be used for measuring capacitance between the capacitance detection module and blades of the impeller; and the processing assembly is electrically connected with the capacitance detection module and can judge the thickness of grease accumulated on the leaf according to the capacitance received by the capacitance detection module.

Description

Technical Field

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

[0002] Range hoods have become an indispensable kitchen appliance in modern homes. They operate on the principles of fluid dynamics, using a centrifugal fan inside to draw in and exhaust cooking fumes, and a filter to remove some of the grease particles.

[0003] After prolonged use, a large amount of oil and dust accumulates inside the casing of a range hood, especially in centrifugal fans where oil and dust buildup is severe. For example, a range hood disclosed in Chinese patent application number 202310919004.9 has a vertically arranged fan. When the impeller stops rotating, one side is at its lowest point. Accumulated grease gathers along the blade structure and drips down to this lowest position, resulting in more grease accumulation at this point than in other areas. This also means that the impeller's dynamic balance is disrupted, causing the entire unit to vibrate and requiring cleaning and maintenance (similar problems exist with other fan arrangements).

[0004] Most range hoods currently use accumulated impeller running time to remind users to maintain their appliances. However, firstly, different users have different cooking habits, resulting in significant differences in grease buildup on the impeller blades. In areas like Sichuan and Chongqing, grease may have accumulated heavily before the maintenance reminder time is due, while in areas with lighter diets, no obvious contamination may be visible even after several cycles. Therefore, relying solely on accumulated time for reminders is prone to misjudgment. If users find no obvious dirt after in-home cleaning or automatic cleaning, they may feel that the reminders are unpredictable, leading to a poor user experience.

[0005] Secondly, the position of the impeller during operation and after it stops results in different areas having varying levels of oil contact and accumulation. Some areas have thicker oil, while others have thinner oil. Time-based reminders cannot account for the actual oil accumulation in different areas. In some areas, the coating has peeled off, while in others, it is not cleaned properly.

[0006] Furthermore, relying solely on time-based reminders is prone to misjudgment. This can easily lead to situations where users find no obvious dirt after on-site or automatic cleaning, resulting in feelings that the manufacturer's judgment is uncontrollable, unintelligent, overcharged, and provides a poor user experience.

[0007] Finally, some companies use current detection or simple differential pressure detection to determine whether the impeller is contaminated and whether the fan is working properly. However, using current monitoring alone is easily affected by grid voltage fluctuations, motor efficiency, and motor heating, which can cause attenuation interference. On the other hand, single differential pressure monitoring cannot distinguish between impeller contamination and front-end filter blockage or rear-end flue blockage. Summary of the Invention

[0008] The first technical problem to be solved by the present invention is to provide a range hood that improves the accuracy of pollution detection, in order to address the shortcomings of the prior art.

[0009] The second technical problem to be solved by the present invention is to provide a cleaning control method for range hoods that addresses the shortcomings of the prior art and improves cleaning efficiency and effectiveness.

[0010] The first technical solution adopted by the present invention to solve the first technical problem mentioned above is: a range hood, comprising a centrifugal fan, wherein the centrifugal fan comprises a volute and an impeller disposed within the volute, and the impeller comprises blades; characterized in that:

[0011] The range hood also includes:

[0012] The capacitance detection module is capable of measuring the capacitance between the impeller blades and the impeller blades; and

[0013] The processing component is electrically connected to the capacitance detection module and can determine the thickness of grease accumulated on the blade based on the capacitance received by the capacitance detection module.

[0014] By utilizing the characteristic that the accumulation of grease may change the capacitance value between the impeller and the capacitance sensor, a capacitance detection module is set up close to the impeller in the fan casing. Combined with the active rotation of the impeller, a single sensor can measure the degree of dirtiness of different blades of the entire multi-blade impeller. Moreover, the measurement is non-contact, which can further eliminate the interference of the test module to the system itself.

[0015] Furthermore, the volute includes an annular wall, and the capacitance detection module is disposed on the annular wall, the shape of which is integrated with the profile of the annular wall of the volute. This prevents the capacitance detection module from disrupting the volute profile and thus avoiding any impact on the centrifugal fan's start-up performance.

[0016] The first technical solution adopted by the present invention to solve the second technical problem mentioned above is: a cleaning control method for a range hood, using the range hood as described above, wherein the range hood further includes a cleaning device for cleaning a centrifugal fan, characterized in that: the control method includes the following steps:

[0017] 1) Turn on the range hood;

[0018] 2) Load the currently stored capacitance reference value C0;

[0019] 3) Start the centrifugal fan to make the impeller rotate at a low speed;

[0020] 4) The capacitance detection module acquires the capacitance value c(t) in real time, where t is the acquisition time;

[0021] 5) Determine if the centrifugal fan has rotated a certain number of revolutions. If not, return to step 4). If yes, apply the dynamic compensation formula: C 修正 =K d (θ)×C 原始 Perform dynamic compensation calculation to obtain the corrected C. 修正 Calculate ΔC = C 修正 -C0; where K d (θ) is the compensation coefficient for the bending shape of the capacitor;

[0022] 6) Calculate the grease thickness δ as follows: d0 is the plate spacing corresponding to the middle position of the capacitance detection module, ε 油 The dielectric constant of the grease is used to select the blade angle position corresponding to the thickest grease.

[0023] 7) The processing component obtains the first grease thickness threshold δ1 and the second grease thickness threshold δ2, and δ1>δ2, and determines whether δ≥δ1 is true. If not, proceed to step 8); if yes, proceed to step 10.

[0024] 8) Determine whether δ2≤δ<δ1 is true. If yes, prompt the user to clean and proceed to step 10); if no, do not clean for now and proceed to step 10.

[0025] 9) Control the cleaning device to perform self-cleaning, and after completion, proceed to step 10);

[0026] 10) Hibernation / Standby.

[0027] Furthermore, the compensation coefficient is, in step 5), The profile of the volute is a logarithmic spiral, and its equation is: r(θ)=r0·e bθ Where r0 is the base circle radius, b is the expansion control parameter, θ is the angle corresponding to the polar radius, and the dynamic distance between the capacitance detection module and the blade is d(θ) = r(θ) - R2, where R2 is the outer diameter of the impeller.

[0028] The second technical solution adopted by the present invention to solve the above-mentioned second technical problem is: a cleaning control method for a range hood, using the range hood as described above, wherein the range hood further includes a cleaning device for cleaning a centrifugal fan, characterized in that: the control method includes the following steps:

[0029] 1) Turn on the range hood;

[0030] 2) Load the currently stored capacitance reference value C0;

[0031] 3) Start the centrifugal fan to make the impeller rotate at a low speed;

[0032] 4) The capacitance detection module acquires the capacitance value c(t) in real time, where t is the acquisition time;

[0033] 5) According to the dynamic compensation formula: C 修正 =K d (θ)×C 原始 Perform dynamic compensation calculation to obtain the corrected C. 修正 And obtain the maximum value C among the correction values ​​obtained after the impeller rotates one revolution. _corr Calculate ΔC = C _corr -C0; where K d (θ) is the compensation coefficient for the bending shape of the capacitor;

[0034] 6) Judge ΔC≥C 01 Whether it is true or not, where C 01 If the preset capacitance difference threshold is met, proceed to step 7); otherwise, record the trend data and proceed to step 9.

[0035] 7) Initiate depth detection: The impeller continues to rotate, performing multi-point sampling verification; the processing component acquires the capacitance value detected in real time by the capacitance detection module, calculates the difference between the corrected capacitance and the capacitance reference value C0 at each point according to the dynamic compensation formula, and determines whether it exceeds the capacitance difference threshold C. 01 If yes, proceed to step 8); if no, mark it as a false alarm and proceed to step 9.

[0036] 8) Control the cleaning device to perform self-cleaning. After cleaning, proceed to steps 3) to 5) to obtain the maximum value C among the correction values ​​of each capacitor. _new Determine C _new If ≤1.1C0 is true, update the capacitor reference value C0 = C. _new If not, remind the user to perform maintenance, and then proceed to step 9);

[0037] 9) Hibernation / Standby;

[0038] 10) Power off.

[0039] Furthermore, the compensation coefficient is, in step 5), The profile of the volute is a logarithmic spiral, and its equation is: r(θ)=r0·e bθ Where r0 is the base circle radius, b is the expansion control parameter, θ is the angle corresponding to the polar radius, and the dynamic distance between the capacitance detection module and the blade is d(θ) = r(θ) - R2, where R2 is the outer diameter of the impeller.

[0040] The second technical solution adopted by the present invention to solve the first technical problem mentioned above is: a range hood, comprising a centrifugal fan, wherein the centrifugal fan includes a volute and an impeller disposed within the volute, and the impeller includes blades; characterized in that:

[0041] The range hood also includes:

[0042] The capacitance detection module is capable of measuring the capacitance between the impeller blades and the impeller blades.

[0043] The temperature detection module can detect the temperature of the impeller; and

[0044] The processing component, electrically connected to the capacitance detection module and the temperature detection module, can determine the thickness of grease accumulated on the blades based on the capacitance received by the capacitance detection module and the temperature received by the temperature detection module.

[0045] Furthermore, the volute includes an annular wall, and the capacitance detection module is disposed on the annular wall, the shape of which is integrated with the profile of the annular wall of the volute. This prevents the capacitance detection module from disrupting the volute profile and thus avoiding any impact on the centrifugal fan's start-up performance.

[0046] The third technical solution adopted by the present invention to solve the second technical problem mentioned above is: a cleaning control method for a range hood, using the range hood as described above, wherein the range hood further includes a cleaning device for cleaning a centrifugal fan, characterized in that: the control method includes the following steps:

[0047] 1) The user presses the power button and sends a power-off command;

[0048] 2) Determine if the impeller speed is ≥200rpm. If yes, enter inertial detection mode and proceed to step 3); if no, shut down normally.

[0049] 3) Activate the capacitance detection module;

[0050] 4) Begin cyclic detection;

[0051] 5) Read the current speed n of the impeller and determine whether n≥200rpm is true. If yes, proceed to step 6); if no, proceed to step 7.

[0052] 6) Collect the current capacitance C meas Given temperature T, perform temperature compensation calculation to obtain ΔC, then return to step 4): According to the dynamic compensation formula: C 修正1 =K d (θ)×C meas Perform dynamic compensation calculation to obtain the corrected C. 修正1 K d (θ) is the compensation coefficient for the bending shape of the capacitor;

[0053] Temperature correction value ΔC T for:

[0054] ΔC T ≈C 修正1 [(k1-k2)ΔT-k1×k2×ΔT 2 ];

[0055] Where k1 is the correction coefficient for the dielectric constant of grease, k2 is the linear expansion coefficient of the distance between the plates of the capacitor, and ΔT is the temperature rise.

[0056] The final corrected capacitance is C. 修正 :C 修正 =C 修正1 +ΔC T ; Calculate ΔC = C 修正 -C0;

[0057] 7) Exit the detection loop, analyze the existing ΔC dataset, and determine the maximum value ΔC among the various ΔC values. _max If ≤C1 is true, shut down normally; otherwise, check ΔC. _max If ≤C2 is true, proceed to step 8); otherwise, check ΔC. _max If ≤C3 is true, proceed to step 9); otherwise, proceed to step 10. C1, C2, and C3 are preset thresholds for different levels of pollution, and satisfy C1 < C2 < C3.

[0058] 8) Control the oil slinging of the centrifugal fan, and proceed to step 11) after completion;

[0059] 9) Control the cleaning device to perform self-cleaning, and after completion, proceed to step 11);

[0060] 10) In case of a severe maintenance alarm, disable the centrifugal fan, send an alarm to the user, upload the severe maintenance log, and then proceed to step 11);

[0061] 11) Disconnect the system power supply.

[0062] The fourth technical solution adopted by the present invention to solve the second technical problem mentioned above is: a cleaning control method for a range hood, using the range hood described above, wherein the range hood further includes a cleaning device for cleaning a centrifugal fan, characterized in that: the control method includes the following steps:

[0063] 1) User triggers shutdown;

[0064] 2) The impeller position is self-checked, and after the bottom of the impeller is aligned and locked, proceed to step 3);

[0065] 3) Perform a capacitance scan on the top of the impeller, then rotate the impeller and perform a capacitance scan on the bottom of the impeller;

[0066] 4) Apply capacitance and temperature corrections to the capacitance values ​​obtained from the top and bottom. The correction methods are as follows:

[0067] According to the dynamic compensation formula: C 修正1 =K d (θ)×C meas Perform dynamic compensation calculation to obtain the corrected C. 修正1 C meas K represents the original capacitance value acquired by the capacitance detection module. d (θ) is the compensation coefficient for the bending shape of the capacitor;

[0068] Temperature correction value ΔC T for:

[0069] ΔC T ≈C 修正1 [(k1-k2)Δt-k1×k2×ΔT 2 ];

[0070] Where k1 is the correction coefficient for the dielectric constant of grease, k2 is the linear expansion coefficient of the distance between the plates of the capacitor, and ΔT is the temperature rise detected by the temperature detection module.

[0071] The final corrected capacitance is C. 修正 :C 修正 =C 修正1 +ΔC T ;

[0072] Then the grease thickness δ is calculated as follows: d0 is the plate spacing at the middle position of the capacitance detection module, ε 油 Let be the dielectric constant of the grease, and then obtain the thickness δ of the grease at the bottom. _b and top grease thickness δ _t Calculate δ _b / δ _t ,judge If the condition is met, then shut down normally; otherwise, proceed to step 5.

[0073] 5) Judgment Is it true? If yes, proceed to step 6); if no, proceed to step 7.

[0074] 6) Control the centrifugal fan to sling oil, and after completion, proceed to step 8);

[0075] 7) Control the cleaning device to perform self-cleaning, and after completion, proceed to step 8);

[0076] 8) Cloud-based recording of distribution characteristics;

[0077] 9) Power off safely.

[0078] Compared with the prior art, the advantages of the present invention are as follows: by utilizing the characteristic that the accumulation of grease may change the capacitance value between the impeller and the capacitance sensor, by setting the capacitance detection module at a position close to the impeller of the fan casing, and combining it with the active rotation of the impeller, a single sensor can be used to measure the degree of dirtiness of different blades of the entire multi-blade impeller, and the measurement is non-contact, which can further eliminate the interference of the test module to the system itself. Attached Figure Description

[0079] Figure 1 This is a side view of the range hood according to the first embodiment of the present invention.

[0080] Figure 2 This is a cross-sectional view (left-right cross-section) of the range hood according to the first embodiment of the present invention;

[0081] Figure 3 This is a cross-sectional view (front and back section) of the range hood according to the first embodiment of the present invention;

[0082] Figure 4 This is a schematic diagram of the centrifugal fan and its cleaning device of the range hood according to the first embodiment of the present invention;

[0083] Figure 5 This is a schematic diagram of the centrifugal fan and its cleaning device of the range hood according to the first embodiment of the present invention (and...). Figure 4 (Different perspectives);

[0084] Figure 6 This is a schematic diagram of part of the electrical box and cleaning device of the range hood according to the first embodiment of the present invention;

[0085] Figure 7 This is a cross-sectional view of the centrifugal fan of the range hood according to the first embodiment of the present invention;

[0086] Figure 8-1 , Figure 8-2 and Figure 8-3 This is a graph showing the relationship between the capacitance value detected by the detection module and the impeller rotation angle under different levels of impeller contamination, according to the first embodiment of the present invention.

[0087] Figure 9 This is a control principle diagram of the range hood according to the first embodiment of the present invention;

[0088] Figure 10 This is a control flowchart of the range hood according to the first embodiment of the present invention;

[0089] Figure 11This is a control flowchart of an alternative embodiment of the range hood according to the first embodiment of the present invention;

[0090] Figure 12 This is a cross-sectional view of a centrifugal fan according to a second embodiment of the present invention;

[0091] Figure 13 This is a control principle diagram of the range hood according to the second embodiment of the present invention;

[0092] Figure 14 This is a control flowchart of the range hood according to the second embodiment of the present invention;

[0093] Figure 15 This is a control flowchart of an alternative embodiment of the range hood according to the second embodiment of the present invention. Detailed Implementation

[0094] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0095] 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.

[0096] Example 1

[0097] See Figures 1 to 7 A range hood includes a centrifugal fan 1, which comprises a volute 11, an impeller 12 disposed within the volute 11, and a motor 13 for driving the impeller 12 to rotate. The centrifugal fan 1 can be housed within a fan frame 2. In this embodiment, the range hood is a top-mounted type, and also includes a smoke collection hood 3 located below the fan frame 2. Alternatively, it can be a side-mounted, low-mounted, or other existing types of range hoods. The centrifugal fan 1 includes a volute 11, an impeller 12 disposed within the volute 11, and a motor 13 for driving the impeller 12 to rotate.

[0098] After long-term use, grease will accumulate on the blades 121 of the impeller 12.

[0099] Therefore, the range hood also includes a capacitance detection module 4, which is disposed on the annular wall 112 of the volute 11. The capacitance detection module 4 is disposed on the outer side of the annular wall 112, and the annular wall 112 of the volute 11 can have an opening at the position corresponding to the capacitance detection module 4 so that the capacitance detection module 4 can detect the capacitance.

[0100] The capacitance detection module 4 is positioned 5-15 mm from the edge of the impeller 12, avoiding areas prone to oil dripping and accumulation, such as the high-speed airflow zone and the volute tongue 111 of the volute 11. Therefore, on the projection along the axis X of the impeller 12, the projection point of the axis X is O, the projection point at the end of the volute tongue 111 is M1, and the projection point M2 is the center of the contact point between the capacitance detection module 4 and the volute 11 (the center along the spiral line of the volute 11). For ease of measurement, all projection points are located on the same plane, and the angle formed by the line connecting M1 and O relative to the line connecting M2 and O is α, with α ranging from 20-60°. Since oil easily accumulates at the volute tongue 111, the capacitance detection module 4 is offset from the volute tongue 111 by a certain angle. This allows for detection at the smallest possible distance and avoids oil contamination of the capacitance detection module 4. A larger angle would increase the distance, hindering detection.

[0101] The blades 121 of the impeller 12 are generally metal blades. The accumulation of grease may change the capacitance value between the impeller 12 and the capacitance detection module 4. The capacitance detection module 4 is a capacitance sensor, and its curve is integrated with that of the volute 11 (compared to ordinary parallel plate capacitance sensors, it is less prone to aerodynamic performance degradation due to inconsistent profile curvature after installation). Integration means that the capacitance detection module 4 is an arc-shaped electrode, which can be a flexible FPC board or an arc-shaped metal electrode plate. Its curvature matches the annular wall 112 of the volute 11. An insulating layer 41 is set around it to separate it from the volute 11 (which may be metal). The insulating layer 41 can be a typical 0.5mm thick aluminum nitride ceramic (temperature resistant to 300℃), or others.

[0102] Combined with the active rotation of motor 13, a capacitance detection module 4 can be used to measure the degree of dirtiness of different blades in the entire multi-blade impeller. Moreover, the measurement is non-contact, which can further eliminate the interference of the test module on the system itself (the arc-shaped test module is integrated into the volute profile, unlike ordinary probes that would damage the volute profile), thus avoiding various defects caused by mechanical or other contact measurements.

[0103] The range hood also includes a cleaning device for cleaning the centrifugal fan 1, see also Figures 2-6The cleaning device includes a water tank 51 for storing cleaning media, which can be water or cleaning agent. The water tank 51 can be connected to tap water or other containers. The cleaning device also includes a heating or steam generating module 52, a water pump or water valve 53, a three-way valve 54, a first conduit 551, a second conduit 552, a third conduit 553, a spray arm 56, and a drive mechanism 57.

[0104] The first conduit 551 connects the heating or steam generating module 52 and the spray arm 56 to enable fluid communication between them. The spray arm 56 extends within the volute 11 of the centrifugal fan 1, located between the wall of the volute 11 and the impeller 12, and preferably extends in a direction parallel to the axial direction of the centrifugal fan 1. The spray arm 56 is provided with nozzles 561, which can be used to spray heated or steam-state cleaning media onto the blades 121 of the impeller 12 (or partially onto the volute 11). The spray arm 56 may also be provided with brush heads 562, which can be used to remove grease from the blades 121. A drive mechanism 57 is located outside the volute 11 and is used to drive the spray arm 56 to rotate about its own axis (in a direction parallel to the axial direction of the centrifugal fan 1). It can be any existing rotary drive module, such as a motor. This allows the direction of the nozzle 561 and / or brush head 562 to be changed by driving the spray arm 56 to achieve thorough cleaning, or to rotate the nozzle 561 and / or brush head 562 toward the wall of the volute 11 when cleaning is not required, reducing the risk of grease blockage and grease accumulation.

[0105] The range hood also includes an electrical box 6, which includes a power board 61 and a radiator 62 for heat dissipation of the power board 61. The radiator 62 can be in the form of heat dissipation fins. The three-way valve 54 is a valve body with one inlet and two outlets. The water tank 51 is connected to one inlet of the three-way valve 54 via a water pump or water valve 53 through a second conduit 552 (the water pump or water valve 53 is located at the connection between the water tank 51 and the second conduit 552 to control whether cleaning medium is supplied). One outlet of the three-way valve 54 is connected to the heating or steam generation module 52, and the other outlet is connected to the water tank 51 via a third conduit 553. The second conduit 552 can bend through the heat dissipation fins of the radiator 62, through which the cleaning medium in the water tank 51 enters the second conduit 552 via a water pump or water valve 53. The cleaning medium in the second conduit 552 exchanges heat with the radiator 62. After being preheated, the cleaning medium enters the three-way valve 54 and then enters the heating or steam generation module 52 to be heated or vaporized, thereby spraying and cleaning through the nozzles 561 on the spray arm 56. Unused cleaning medium can enter the third conduit 553 through the three-way valve 54 and then return to the water tank 51.

[0106] See Figure 9The range hood of this embodiment further includes a processing component 7, which has a processor. The motor 13 (and its drive module) of the centrifugal fan 1, the heating or steam generating module 52 of the cleaning device, the water pump or water valve 53, the drive mechanism 57, and the capacitance detection module 4 are all electrically connected to the processing component 7. In addition, the processing component 7 may also be electrically connected to a switch module 71, a storage module 72, and a lamp module 73, which are the same as in the prior art.

[0107] The detection principle of the capacitance detection module 4 is as follows: the dielectric constant ε of grease is generally 3 to 5, while the dielectric constant of air is generally 1. Therefore, for impeller 12, which is generally made of metal blades, the accumulation of grease may change the capacitance value between impeller 12 and capacitance detection module 4.

[0108] For a typical parallel-plate capacitor, its capacitance value is... The dielectric constant is ε, the effective area of ​​the plates is A, and the distance between the plates is d. When grease (dielectric constant of about 3 to 5) adheres to the surface of the impeller 12, the original medium between the plates changes from air to a mixture of grease and air, and the overall dielectric constant increases significantly, resulting in a proportional increase in capacitance.

[0109] Since this embodiment uses an arc-shaped capacitor, it is necessary to correct the capacitance value detected by the capacitance detection module 4 based on the profile of the volute 11. Generally, the profile of the volute 11 adopts a logarithmic spiral or a similar logarithmic spiral structure. The conventional logarithmic spiral equation is: r(θ)=r0·e bθ Where r0 is the base circle, generally the outer diameter of impeller 12 or a design reference value slightly larger than the outer diameter of impeller 12; while b is the expansion control parameter; θ is generally in [0, 2π], and is the angle corresponding to the polar radius. The dynamic distance d(θ) between capacitor detection module 4 and blade 121 is d(θ) = r(θ) - R2, where R2 is the outer diameter of impeller 12. Assuming the distance between the plates of a normal parallel plate capacitor is d0 (corresponding to the plate spacing at the middle position of capacitor detection module 4), then this type of arc capacitor needs to be converted using the compensation coefficient Kd(θ). For arc capacitors with fixed installation position or angle θ, the compensation coefficient is fixed:

[0110]

[0111] Corrected capacitor C 修正 and the original measurement value C 原始 The relationship between them is: C 修正 =K d (θ)×C 原始 .

[0112] The grease thickness δ is: C0 is the baseline value when impeller 12 is clean, ε 油The dielectric constant of the grease is known, typically 3 to 5.

[0113] In actual use, after the user stops the machine, the low speed at the moment of near-stop, or the machine can be actively rotated at a low speed, to dynamically detect the change in capacitance value of the impeller 12 after one revolution. The deviation from the value when the impeller is clean can be calculated, or the capacitance change at different positions of the blades 121 when the impeller is dirty can be calculated to determine the degree of contamination (because the impeller is generally installed vertically, the difference in grease accumulation between the highest and lowest points is significant; even after the machine stops, the lowest point will still be the lowest point after accumulation). See [link / reference]. Figure 8-1 The graph shows the relationship between the impeller rotation angle and the received capacitance value when there is no pollution. (See Figure 1) Figure 8-2 The graph shows the relationship between the impeller rotation angle and the received capacitance value under slight contamination. (See Figure 1) Figure 8-3 The graph shows the relationship between the impeller rotation angle and the received capacitance value under heavy pollution conditions.

[0114] See Figure 10 In this invention, the judgment and calculation are completed by the processing component 7. The control method of the range hood of this invention includes the following steps:

[0115] 1) Turn on the range hood; at this time, the system can perform a self-test.

[0116] 2) Load the reference value of the capacitor C0, which is the reference value of the capacitor when it is clean;

[0117] 3) Start the impeller 12 (motor 13) of the centrifugal fan 1 to rotate at a low speed, such as 200 rpm;

[0118] 4) The capacitance detection module 4 collects the capacitance value c(t) in real time, where t is the collection time;

[0119] 5) Determine if centrifugal fan 1 has rotated a certain number of revolutions, such as 3 revolutions. If not, return to step 4). If yes, apply the dynamic compensation formula: C 修正 =K d (θ)×C 原始 Perform dynamic compensation calculation to obtain the corrected C. 修正 Calculate ΔC = C 修正 -C0;

[0120] 6) Calculate the grease thickness δ as follows: And select the blade 121 angle position corresponding to the thickest grease (which can be obtained according to the rotation angle of impeller 12);

[0121] 7) Obtain the grease judgment benchmark, namely the first grease thickness threshold δ1 and the second grease thickness threshold δ2, and δ1 > δ2. In this embodiment, the first grease thickness threshold δ1 is 100 μm and the second grease thickness threshold δ2 is 50 μm; determine whether δ ≥ δ1 is true. If not, proceed to step 8); if yes, proceed to step 10.

[0122] 8) Determine whether δ2≤δ<δ1 is true. If yes, prompt the user to clean and proceed to step 10); if no, do not clean for now and proceed to step 10.

[0123] 9) Trigger intelligent cleaning, that is, the processing component 7 controls the above-mentioned cleaning device to automatically clean according to the set mode, and after completion, proceed to step 10).

[0124] 10) Hibernation / Standby.

[0125] See Figure 11 An alternative embodiment of the control method for the range hood of the present invention includes the following steps:

[0126] 1) Turn on the range hood. At this time, the system can perform a self-test. If the self-test passes, proceed to step 2). If the self-test fails, a fault alarm will sound, and proceed to step 9.

[0127] 2) Load the reference value of the capacitor C0, which is the reference value of the capacitor when it is clean;

[0128] 3) Start the low-speed scanning mode, that is, the impeller 12 (motor 13) of the centrifugal fan 1 rotates at a low speed, such as 200 RPM;

[0129] 4) The capacitance detection module 4 collects the capacitance value c(t) in real time, where t is the collection time;

[0130] 5) According to the dynamic compensation formula: C 修正 =K d (θ)×C 原始 Perform dynamic compensation calculation to obtain the corrected C. 修正 And obtain the maximum value C obtained after the impeller 12 rotates one revolution. _corr Calculate ΔC = C _corr -C0;

[0131] 6) Determine whether ΔC ≥ C 01 C 01 The preset capacitance difference threshold can be determined in advance through multiple experiments. A possible value is 10-50pF. If so, proceed to step 7); otherwise, record the trend data and proceed to step 9.

[0132] 7) Initiate depth detection, impeller 12 continues to rotate, and multi-point (i.e., multiple positions of blade 121) sampling verification is performed; processing component 7 obtains the capacitance value detected in real time by capacitance detection module 4, calculates the difference between the corrected capacitance and the capacitance reference value C0 at each point, and determines whether it exceeds the capacitance difference threshold C. 01 If yes, proceed to step 8); if no, mark it as a false alarm and proceed to step 9.

[0133] 8) Trigger a level 3 alarm and control the cleaning device to perform cleaning. If high-voltage pulse cleaning is possible, proceed to steps 3) to 5) after cleaning to obtain the maximum value C among the correction values ​​of each capacitor. _new Determine C _new If ≤1.1C0 is true, update the capacitor reference value C0 = C. _new If not, remind the user to perform maintenance, and then proceed to step 9);

[0134] 9) Hibernation / Standby;

[0135] 10) Power off.

[0136] Example 2

[0137] See Figure 12 and Figure 13 In this embodiment, the difference from the first embodiment is that a temperature detection module 8 is also included. When the range hood is working, the area below is the cooking zone. Temperatures vary significantly depending on the cooking scenario (it may be 60-70 degrees Celsius after cooking in summer, and below zero in winter when only ventilation is used). This causes the airflow to be heated before passing through the impeller 12. To improve accuracy, a temperature detection module is added for correction.

[0138] To facilitate the setup of the temperature detection module 8, the value of α is set to [20-50°]. The temperature detection module 8 is positioned near the capacitance detection module 4, with an angular deviation between them within [-10°, 10°].

[0139] For a typical parallel-plate capacitor, its capacitance value is... Wherein, the dielectric constant ε, the effective area of ​​the plate A, and the distance between the plates d are all represented. When grease (with a dielectric constant of about 3-5) adheres to the surface of the impeller 12, the original medium between the plates changes from air to a mixture of grease and air, and the overall dielectric constant increases significantly, resulting in a proportional increase in capacitance.

[0140] Since this embodiment uses an arc-shaped capacitor, it is necessary to correct the capacitance value based on the volute profile. Generally, the volute profile uses a logarithmic spiral or a similar logarithmic spiral structure. The conventional logarithmic spiral equation is: r(θ)=r0·e bθWhere r0 is the base circle, generally the outer diameter of impeller 12 or a design reference value slightly larger than the outer diameter of impeller 12; and b is also the expansion control parameter; θ is generally in [0, 2π], which is the angle corresponding to the polar radius. The dynamic distance d(θ) between capacitor detection module 4 and blade 121 is d(θ) = r(θ) - R2, where R2 is the outer diameter of impeller. Assuming the distance between the plates of a normal parallel plate capacitor is d0, then this type of arc capacitor needs to be converted using the compensation coefficient Kd(θ). For arc capacitors with fixed installation position or angle θ, the compensation coefficient is fixed:

[0141]

[0142] Corrected capacitor C 修正1 and the original measurement value C meas The relationship between them is: C 修正1 =K d (θ)×C meas .

[0143] The dielectric constant of grease increases with increasing temperature. The correction factor k1 for the dielectric constant is approximately k1 = 0.002 / ℃ (observed experimentally). Plate spacing: Thermal expansion of metals (blades, plates, etc. are all metals) may cause changes in d. The measured linear expansion coefficient k2 is k2 = 23 × 10⁻⁶ / ℃.

[0144] Establishing the temperature drift relationship, the total drift of the capacitor is:

[0145]

[0146] Expanding it and keeping the quadratic terms while discarding the higher-order terms, we get:

[0147] ΔC T ≈C 修正1 [(k1-k2)ΔT-k1×k2×ΔT 2 ].

[0148] k1 and k2 can be measured in advance in the laboratory and stored in the memory for later use in calculations, where ΔT is the temperature rise.

[0149] The previously obtained C 修正1 Substituting this into the formula as a baseline, we can obtain the temperature drift ΔC. T After adding curvature and temperature corrections, the final capacitance C can be obtained. 修正 =C 修正1 +ΔC T At this point, the capacitance change ΔC = C can be obtained. 修正 -C0, and then judge the degree of cleanliness based on the deviation.

[0150] See Figure 14The control method for the range hood in this embodiment includes the following steps:

[0151] 1) The user presses the power button and sends a power-off command;

[0152] 2) Determine if the speed of impeller 12 is ≥200rpm? If yes, enter inertial detection mode and proceed to step 3); if no, shut down normally; the speed of impeller 12 can be obtained from the speed of motor 13, which can be obtained using existing technology;

[0153] 3) Activate capacitive sensor 4 and start the detection timer (the regular timer in the processor of processing component 7);

[0154] 4) Begin cyclic detection;

[0155] 5) Read the current rotational speed n of impeller 12 and determine whether n≥200rpm is true. If yes, proceed to step 6); if no, proceed to step 7.

[0156] 6) Collect the current capacitance C meas Given temperature T, perform temperature compensation calculation to obtain ΔC, then return to step 4);

[0157] 7) Exit the detection loop and analyze the existing ΔC dataset. The previous data collected showed changes in the blade 121 capacitance due to varying degrees of dirt at different locations, while ΔC... _max This is the value with the greatest difference in capacitance among different blades (usually due to the top and bottom blades), therefore ΔC can be used. _max To assess the difference in oil accumulation at the top and bottom of blade 121, both positions on a new or clean impeller 121 are clean and oil-free, with minimal difference. However, as usage time increases, the difference in oil accumulation becomes increasingly significant, therefore ΔC... _max The value increases positively with usage time and oil accumulation. Therefore, the degree of oil accumulation can be determined by setting different threshold values ​​as follows: The maximum value ΔC is then selected. _max If ≤C1 is true, shut down normally; otherwise, check ΔC. _max If ≤C2 is true, proceed to step 8); otherwise, check ΔC. _max If ≤C3 is true, proceed to step 9); otherwise, proceed to step 10. C1, C2, and C3 are preset thresholds for different levels of pollution, and satisfy C1 < C2 < C3. C1 is the threshold for mild accumulation: when ΔC... _max ≤C1 means a small amount of accumulation, which does not affect performance and has not yet reached the state where it needs to be cleaned up. The recommended value range is C1∈[10pf, 20pf]; C2 is the moderate accumulation threshold: when ΔC _maxA value ≤C2 indicates some oil buildup, but simple cleaning methods like oil-spinning can be used to reduce or remove the oil. ΔC... _max When C2 is greater than the required value, the oil buildup is thicker, often requiring water washing or heavy maintenance. The recommended value range for C2 is [25pf, 40pf]. C3 is the threshold for heavy buildup: when ΔC... _max ≤C3 means that the oil stains are severely accumulated, often requiring heavy maintenance, such as manual disassembly and soaking cleaning or mechanical removal of oil stains. The recommended value range for C3 is [45pf, 50pf].

[0158] 8) Triggering the oil-slinging mode: The impeller 12 (motor 13) can be raised to, for example, 3000 rpm and then stopped suddenly. Then, the power is reversed to make the impeller 12 rotate in reverse at 500 rpm for a certain period of time, such as 5 seconds. This step mainly utilizes centrifugal force F=mω 2 r, the critical grease peeling force F_c=η·σ (η is the adhesion coefficient, σ is the oil film cohesion), when ω≥√(F_c / mr) it will automatically detach (the experimentally measured ω_min=40rad / s); the indicator light on the range hood (if it is blue) flashes, upload the light maintenance log, and then proceed to step 11);

[0159] 9) Start water washing and cleaning: Water pressure requirement: ≥0.2MPa (micro water pump flow rate ≥200ml / min), the treatment component 7 controls the cleaning device to start hot water spray, the impeller 12 alternates forward and reverse rotation for 30 seconds, and then spins dry at high speed; the indicator light on the range hood (if it is yellow) stays on, upload the medium maintenance log, and then proceed to step 11);

[0160] 10) Heavy maintenance alarm, disable motor 13 operation, the indicator light on the range hood (if red) flashes rapidly, push alarm to user, upload heavy maintenance log, and then proceed to step 11);

[0161] 11) Disconnect the system power supply.

[0162] See Figure 15 An alternative control method includes the following steps:

[0163] 1) When the user triggers the shutdown, motor 13 decelerates until it stops;

[0164] 2) Self-check the position of impeller 12. If the bottom is not aligned, adjust the alignment with a micro-pulse. If the bottom is aligned, lock impeller 12 and proceed to step 3).

[0165] 3) Perform a capacitance scan on the top of the impeller 12, and rotate the impeller 12 to perform a capacitance scan on the bottom of the impeller 12;

[0166] 4) Perform temperature compensation calculations separately to obtain the bottom grease thickness δ. _b and top grease thickness δ _tCalculate δ _b / δ _t ,judge If the condition is met, then shut down normally; otherwise, proceed to step 5.

[0167] 5) Judgment Is it true? If yes, proceed to step 6); if no, proceed to step 7.

[0168] 6) Start vibrating to remove oil: Impeller 12 (motor 13) rotates in both directions at high speed, mechanically vibrating to remove grease, indicating slight deposition, and then proceed to step 8);

[0169] 7) Control the cleaning device to spray the bottom of the impeller 12 in a directional manner. For example, the bottom nozzle 561 can rotate 60° to spray in a fan shape, and then rinse with hot water. For example, rinse with 60° hot water. Finally, spin the impeller 12 at high speed to dry it. The deep cleaning is indicated to be complete. Proceed to step 8.

[0170] 8) Cloud-based recording of distribution characteristics;

[0171] 9) Power off safely.

[0172] The term "fluid connectivity" as used in this invention refers to the spatial relationship between two components or parts (hereinafter referred to as the first part and the second part, respectively), that is, a fluid (gas, liquid, or a mixture of both) can flow from the first part along a flow path and / or be transported to the second part. This can be a direct connection between the first part and the second part, or an indirect connection between the first part and the second part through at least one third party. This third party can be a fluid channel such as a pipe, channel, conduit, guide, hole, or groove, or a chamber or combination thereof that allows fluid to flow through.

Claims

1. A range hood, comprising a centrifugal fan (1), the centrifugal fan (1) comprising a volute (11) and an impeller (12) disposed within the volute (11), the impeller (12) comprising blades (121); characterized in that: The range hood also includes: The capacitance detection module (4) is capable of measuring the capacitance between the impeller (12) blades (121) and the blades (121). The processing component (7) is electrically connected to the capacitance detection module (4) and can determine the thickness of grease accumulated on the blade (121) based on the capacitance received by the capacitance detection module (4).

2. The range hood according to claim 1, characterized in that: The volute (11) includes an annular wall (112), and the capacitance detection module (4) is disposed on the annular wall (112). The shape of the capacitance detection module (4) is integrated with the profile of the annular wall (112) of the volute (11).

3. A cleaning control method for a range hood, employing the range hood according to claim 2, wherein the range hood further includes a cleaning device for cleaning the centrifugal fan (1), characterized in that: The control method includes the following steps: 1) Turn on the range hood; 2) Load the currently stored capacitance reference value C0; 3) Start the centrifugal fan (1) so that the impeller (12) rotates at a low speed; 4) The capacitance detection module (4) collects the capacitance value c(t) in real time, where t is the collection time; 5) Determine if the centrifugal fan (1) has rotated a certain number of revolutions. If not, return to step 4). If yes, follow the dynamic compensation formula: C 修正 =K d (θ)×C 原始 Perform dynamic compensation calculation to obtain the corrected C. 修正 Calculate ΔC = C 修正 -C0; where K d (θ) is the compensation coefficient for the bending shape of the capacitor; 6) Calculate the grease thickness δ as follows: d0 is the plate spacing corresponding to the middle position of the capacitance detection module (4), ε 油 Let be the dielectric constant of the grease, and select the blade (121) angle position corresponding to the thickest grease; 7) The processing component (7) obtains the first grease thickness threshold δ1 and the second grease thickness threshold δ2, and δ1>δ2, and determines whether δ≥δ1 is true. If not, proceed to step 8); if yes, proceed to step 10. 8) Determine whether δ2≤δ<δ1 is true. If yes, prompt the user to clean and proceed to step 10); if no, do not clean for now and proceed to step 10. 9) Control the cleaning device to perform self-cleaning, and after completion, proceed to step 10); 10) Hibernation / Standby.

4. The cleaning control method for a range hood according to claim 3, characterized in that: In step 5), The profile of the volute (11) is a logarithmic spiral, and the equation of the profile is: r(θ)=r0·e bθ , where r0 is the base circle radius, b is the expansion control parameter; θ is the angle corresponding to the polar radius, and the dynamic distance d(θ) between the capacitor detection module (4) and the blade (121) is r(θ)-R2, where R2 is the outer diameter of the impeller (12).

5. A cleaning control method for a range hood, employing the range hood according to claim 2, wherein the range hood further includes a cleaning device for cleaning the centrifugal fan (1), characterized in that: The control method includes the following steps: 1) Turn on the range hood; 2) Load the currently stored capacitance reference value C0; 3) Start the centrifugal fan (1) so that the impeller (12) rotates at a low speed; 4) The capacitance detection module (4) collects the capacitance value c(t) in real time, where t is the collection time; 5) According to the dynamic compensation formula: C 修正 =K d (θ)×C 原始 Perform dynamic compensation calculation to obtain the corrected C. 修正 And obtain the maximum value C among the correction values ​​obtained after the impeller (12) rotates one revolution. _corr Calculate ΔC = C _corr -C0; where K d (θ) is the compensation coefficient for the bending shape of the capacitor; 6) Judge ΔC≥C 01 Whether it is true or not, where C 01 If the preset capacitance difference threshold is met, proceed to step 7); otherwise, record the trend data and proceed to step 9. 7) Start depth detection: The impeller (12) continues to rotate and performs multi-point sampling verification; the processing component (7) obtains the capacitance value detected in real time by the capacitance detection module (4), calculates the difference between the correction capacitance and the capacitance reference value C0 at each point according to the dynamic compensation formula, and determines whether it exceeds the capacitance difference threshold C. 01 If yes, proceed to step 8); if no, mark it as a false alarm and proceed to step 9. 8) Control the cleaning device to perform self-cleaning. After cleaning, proceed to steps 3) to 5) to obtain the maximum value C among the correction values ​​of each capacitor. _new Determine C _new If ≤1.1C0 is true, update the capacitor reference value C0 = C. _new If not, remind the user to perform maintenance, and then proceed to step 9); 9) Hibernation / Standby; 10) Power off.

6. The cleaning control method for a range hood according to claim 5, characterized in that: In step 5), The profile of the volute (11) is a logarithmic spiral, and the equation of the profile is: r(θ)=r0·e bθ , where r0 is the base circle radius, b is the expansion control parameter; θ is the angle corresponding to the polar radius, and the dynamic distance d(θ) between the capacitor detection module (4) and the blade (121) is r(θ)-R2, where R2 is the outer diameter of the impeller (12).

7. A range hood, comprising a centrifugal fan (1), the centrifugal fan (1) comprising a volute (11) and an impeller (12) disposed within the volute (11), the impeller (12) comprising blades (121); characterized in that: The range hood also includes: The capacitance detection module (4) is capable of measuring the capacitance between the blades (121) of the impeller (12); The temperature detection module (8) is capable of detecting the temperature of the impeller (12); and The processing component (7) is electrically connected to the capacitance detection module (4) and the temperature detection module (8), and can determine the thickness of grease accumulated on the blade (121) based on the capacitance received by the capacitance detection module (4) and the temperature received by the temperature detection module (8).

8. The range hood according to claim 7, characterized in that: The volute (11) includes an annular wall (112), and the capacitance detection module (4) is disposed on the annular wall (112). The shape of the capacitance detection module (4) is integrated with the profile of the annular wall (112) of the volute (11).

9. A cleaning control method for a range hood, employing the range hood according to claim 8, wherein the range hood further includes a cleaning device for cleaning the centrifugal fan (1), characterized in that: The control method includes the following steps: 1) The user presses the power button and sends a power-off command; 2) Determine if the impeller (12) speed is ≥200rpm? If yes, enter inertial detection mode and proceed to step 3); if no, shut down normally. 3) Activate the capacitance detection module (4); 4) Start the loop detection; 5) Read the current speed n of the impeller (12), and determine whether n≥200rpm is true. If yes, proceed to step 6); if no, proceed to step 7. 6) Collect the current capacitance C meas Given temperature T, perform temperature compensation calculation to obtain ΔC, then return to step 4): According to the dynamic compensation formula: C 修正1 =K d (θ)×C meas Perform dynamic compensation calculation to obtain the corrected C. 修正1 K d (θ) is the compensation coefficient for the bending shape of the capacitor; Temperature correction value ΔC T for: ΔC T ≈C 修正1 [(k1-k2)ΔT-k1×k2×ΔT 2 ]; Where k1 is the correction coefficient for the dielectric constant of grease, k2 is the linear expansion coefficient of the distance between the plates of the capacitor, and ΔT is the temperature rise. The final corrected capacitance is C. 修正 :C 修正 =C 修正1 +ΔC T ; Calculate ΔC = C 修正 -C0; 7) Exit the detection loop, analyze the existing ΔC dataset, and determine the maximum value ΔC among the various ΔC values. _max If ≤C1 is true, shut down normally; otherwise, check ΔC. _max If ≤C2 is true, proceed to step 8); otherwise, check ΔC. _max If ≤C3 is true, proceed to step 9); otherwise, proceed to step 10. C1, C2, and C3 are preset thresholds for different levels of pollution, and satisfy C1 < C2 < C3. 8) Control the oil slinging of the centrifugal fan (1), and after completion, proceed to step 11); 9) Control the cleaning device to perform self-cleaning, and after completion, proceed to step 11); 10) Heavy maintenance alarm, disable the centrifugal fan (1), push alarm to the user, and upload heavy maintenance log, then proceed to step 11); 11) Disconnect the system power supply.

10. A cleaning control method for a range hood, employing the range hood according to claim 8, wherein the range hood further includes a cleaning device for cleaning the centrifugal fan (1), characterized in that: The control method includes the following steps: 1) User triggers shutdown; 2) The position of the impeller (12) is self-checked. After the bottom of the impeller (12) is aligned and locked, proceed to step 3); 3) Perform a capacitance scan on the top of the impeller (12), then rotate the impeller (12) and perform a capacitance scan on the bottom of the impeller (12); 4) Apply capacitance and temperature corrections to the capacitance values ​​obtained from the top and bottom. The correction methods are as follows: According to the dynamic compensation formula: C 修正1 =K d (θ)×C meas Perform dynamic compensation calculation to obtain the corrected C. 修正1 C meas K represents the original capacitance value acquired by the capacitance detection module (4). d (θ) is the compensation coefficient for the bending shape of the capacitor; Temperature correction value ΔC T for: ΔC T ≈C 修正1 [(k1-k2)ΔT-k1×k2×ΔT 2 ]; Where k1 is the correction coefficient of the dielectric constant of grease, k2 is the linear expansion coefficient of the distance between the plates of the capacitor, and ΔT is the temperature rise value detected by the temperature detection module (8). The final corrected capacitance is C. 修正 :C 修正 =C 修正1 +ΔC T ; Then the grease thickness δ is calculated as follows: d0 is the plate spacing at the middle position of the capacitance detection module (4), ε 油 Let be the dielectric constant of the grease, and then obtain the thickness δ of the grease at the bottom. _b and top grease thickness δ _t Calculate δ _b / δ _t ,judge If the condition is met, then shut down normally; otherwise, proceed to step 5. 5) Judgment Is it true? If yes, proceed to step 6); if no, proceed to step 7. 6) Control the centrifugal fan (1) to spit out oil, and after completion, proceed to step 8); 7) Control the cleaning device to perform self-cleaning, and after completion, proceed to step 8); 8) Cloud-based recording of distribution characteristics; 9) Power off safely.

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