A control method of a range hood

Abstract

The application discloses a control method of an oil fume extractor, the oil fume extractor comprising a power device installed on a ceiling, the power device being installed with an external installation base through a suspension structure; the power device comprising a fan frame and a fan; the control method comprising the following steps: 1) turning on the oil fume extractor; 2) monitoring the rotating speed N of the motor of the fan; 3) calculating the rotating speed change AN within a certain time t; 4) entering step 5) when the motor reaches a steady state; 5) calculating the current motor rotating speed base frequency 6) corresponding to the resonance suspension height L(f0) of the power device; 7) judging whether L-L(f0)≤ΔL is established or not, if yes, entering step 8), if not, returning to step 3); 8) monitoring the vibration amplitude A of the current suspension structure and the fan frame connection, judging whether A≥A0 is established or not, if yes, entering step 9), if not, returning to step 3); 9) adjusting the suspension structure so that the power device moves a unit distance upwards from the current position.

Description

Technical Field

[0001] This invention relates to an oil fume purification device, and more particularly to a control method for a 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 cooking fumes and a filter to remove some grease particles. The centrifugal fan consists of a casing, an impeller housed within the casing, and a motor that drives the impeller. As the impeller rotates, a negative pressure is generated at the center of the fan, drawing in the cooking fumes from below. After being accelerated by the fan, the fumes are collected by the casing and guided outdoors.

[0003] The fan is the core power system of a range hood, typically fixed to the top and rear panel of the casing or the fan frame assembly. The aerodynamic noise of the fan, as the main noise source of the range hood, significantly impacts the user experience depending on its distance from the user. To reduce noise, some split-type range hoods place the fan on top or within the exhaust duct section. For example, Chinese Patent Application No. 201821517326.1 discloses a range hood comprising a smoke collection hood, a centrifugal fan, and a guide channel located between the two. The centrifugal fan is located at the top of the range hood, with its impeller axis vertically positioned above the ceiling. The inlet of the guide channel is connected to the smoke collection hood, and its outlet is opposite to the fan inlet of the centrifugal fan, which faces downwards.

[0004] This design, which places the fan above the ceiling, keeps the fan, the main noise source, away from the user, thus reducing noise impact. However, due to the complex operating conditions and wide speed range of range hoods, their fans vibrate at a wide frequency range. If the fan system is placed above the ceiling, excessive vibration can significantly affect the ceiling or the support frame (the structure used to suspend the fan). Therefore, reducing vibration is a crucial problem that needs to be solved for this type of ceiling-mounted range hood. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a control method for a range hood that reduces the vibration of the range hood when it is suspended, in order to address the shortcomings of the prior art.

[0006] The technical solution adopted by the present invention to solve the above-mentioned technical problem is as follows: a control method for a range hood, the range hood including a power device for installation on a kitchen ceiling, the power device being installed on an external mounting base via a suspension structure; the power device including a fan frame and a fan placed within the fan frame, the fan including an impeller and a motor for driving the impeller to rotate; characterized in that: the control method includes the following steps:

[0007] 1) Turn on the range hood;

[0008] 2) After the fan has been running for a certain period of time, the speed N of the fan motor is monitored.

[0009] 3) Calculate the change in motor speed ΔN within a certain time t;

[0010] 4) Determine whether ΔN≤ΔN0 is true. If yes, it means the motor is working under stable conditions and proceed to step 5). If no, it means the motor is not yet stable and return to step 3. ΔN0 is the preset speed change threshold.

[0011] 5) Calculate the base frequency of the current motor speed N.

[0012] 6) Based on the preset mapping relationship between the suspension height of the power unit and the first-order rigid body mode frequency of the wind turbine frame L→f(L), determine the suspension height L(f0) of the power unit corresponding to f0, where L(f0) is the resonant suspension height of the power unit.

[0013] 7) Determine whether LL(f0)≤ΔL is true. If yes, proceed to step 8). If no, it means that the suspension is at a safe height and return to step 3. L is the current suspension height of the power unit, and ΔL is the preset threshold difference between the actual suspension height of the power unit and the resonant suspension height.

[0014] 8) Monitor the vibration amplitude A at the connection between the current suspension structure and the wind turbine frame, and determine whether A≥A0 is true. If yes, proceed to step 9); otherwise, return to step 3. A0 is the preset threshold for vibration amplitude.

[0015] 9) Adjust the suspension structure to move the power unit upward a unit distance Δh from the current position, and then return to step 3).

[0016] By comparing the relationship between the current suspension height and the resonant suspension height corresponding to the fundamental frequency of the current vibration excitation source (motor), the actual suspension height of the power unit is avoided to be the same as or close to the resonant suspension height. The optimal installation height is intelligently matched under different working conditions, thereby avoiding resonance between the fan and fan frame of the power unit, reducing vibration transmission to the installation foundation and ceiling, reducing noise, ensuring the stable operation of the range hood, and reducing the impact on the installation foundation and ceiling.

[0017] Preferably, in step 6), the mapping relationship L→f(L) is obtained in advance as follows: when the suspension height of the power unit is L n Under the constraint conditions, the first-order rigid body modal frequency f(L) at this suspension height was obtained by modal testing using the hammer test method. n), where n is a natural number used to distinguish different suspension height parameters L. n .

[0018] Furthermore, to facilitate height adjustment during range hood operation, the suspension structure includes a linear drive module.

[0019] Furthermore, the suspension structure includes a hanging lug, a winding rope, and a drive mechanism. The hanging lug is fixed to the wind turbine frame, and the drive mechanism includes an output shaft capable of outputting torque. The lower end of the winding rope is connected to the hanging lug, and the upper end is connected to the output shaft. The winding rope can be wound around the output shaft, thereby changing the distance between the winding rope and the hanging lug by winding and unwinding the winding rope on the output shaft, thus conveniently adjusting the suspension height of the power unit.

[0020] Furthermore, the suspension structure also includes a pulley mechanism, which comprises a pulley and a bracket. The bracket is fixed to the lower surface of the mounting base, and the pulley is rotatably mounted on the bracket. The axis of rotation of the pulley is parallel to the axis of the output shaft. The winding rope extends outward from the output shaft, passes over the pulley, and extends downward until it is fixed to the lug. This makes the suspension more stable and reduces the driving force required by the drive mechanism.

[0021] Preferably, the suspension structure has four sets, which are respectively installed at the four corners of the top of the wind turbine frame, thereby allowing the power unit to be suspended smoothly.

[0022] Compared with the prior art, the advantages of the present invention are as follows: by comparing the relationship between the current suspension height and the resonant suspension height corresponding to the fundamental frequency of the current vibration excitation source (motor), the actual suspension height of the power unit is avoided to be the same as or close to the resonant suspension height. The optimal installation height under different working conditions is intelligently matched, thereby avoiding resonance between the fan and fan frame of the power unit, reducing the vibration transmission to the installation foundation and ceiling, reducing noise, ensuring the stable operation of the range hood, and reducing the impact on the installation foundation and ceiling. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of a range hood according to an embodiment of the present invention;

[0024] Figure 2 This is a partial schematic diagram of a range hood according to an embodiment of the present invention;

[0025] Figure 3 This is a schematic diagram of the suspension structure and mounting foundation of the range hood according to an embodiment of the present invention;

[0026] Figure 4 This is a cross-sectional view of the suspension structure and mounting base of the range hood according to an embodiment of the present invention;

[0027] Figure 5 This is a control flowchart of a range hood according to an embodiment of the present invention. Detailed Implementation

[0028] The embodiments of the present invention are described in detail below. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions.

[0029] 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.

[0030] See Figures 1-4 A range hood includes a power unit 1, a connecting pipe 2, and an air intake component 3. The power unit 1 is installed on the kitchen ceiling (not shown). The air intake component 3 is used to draw in cooking fumes, and its specific air intake form is not limited. The connecting pipe 2 connects the power unit 1 and the air intake component 3. The connecting pipe 2 is preferably a flexible hose.

[0031] The power unit 1 includes a fan frame 11 and a fan 12 disposed within the fan frame 11. The fan 12 can be an existing conventional centrifugal fan, as described in the background art, including a volute 121, an impeller 122 disposed within the volute 121, and a motor 123 for driving the impeller 122 to rotate.

[0032] The power unit 1 is suspended from an external mounting base 100, such as a ceiling, via a suspension structure. The suspension structure includes a hanging lug 41, a winding rope 42, a drive mechanism 43, and a pulley mechanism 44. The pulley mechanism 44 includes a pulley 441 and a bracket 442. The bracket 442 is fixed to the lower surface of the mounting base 100. The pulley 441 is rotatably mounted on the bracket 442, and its rotation axis extends horizontally, or in the front-rear direction as shown in this embodiment. The drive mechanism 43 is a motor in this embodiment, but it can also be any other torque-output mechanism, as long as it has an output shaft 431 whose axis is parallel to the rotation axis of the pulley 441. The winding rope 42, such as a wire rope, has one end fixed to the output shaft 431 and can be wound around it, while the other end passes over the pulley 441 and extends downwards until it is fixed to the hanging lug 41. The hanging lug 41 is fixed to the fan frame 11, such as the side of the fan frame 11. Pulley 441 serves to turn the rope 42, which is equivalent to a fixed pulley.

[0033] To ensure stable suspension of the power unit, the suspension structure has four sets, each located at one of the four corners of the top of the fan frame 11. By varying the rotation angle of the drive mechanism 43, the number of turns of the winding rope 42 around the output shaft 431 can be changed, thereby altering the length of the winding rope 42 between the output shaft 431 and the hanging lug 41. This, in turn, changes the distance between the power unit 1 and the mounting base 100, i.e., changes the installation height of the power unit 1 (range hood).

[0034] Alternatively, other suspension structures that can change the installation height of the power unit 1 can be used, such as a linear drive module that directly drives the power unit 1, specifically such as an electric actuator, a motor lead screw and nut pair, etc.

[0035] See Figure 5 To reduce the vibration of the aforementioned range hood, the control method includes the following steps:

[0036] 1) Turn on the range hood;

[0037] 2) After the motor 123 of the fan 12 has been running for a certain period of time, such as 10 seconds, the speed N of the motor 123 is monitored. The unit of speed is r / min. The speed can be detected using existing methods, such as by detecting the current.

[0038] 3) Calculate the change in speed ΔN of motor 123 within a certain time t. t generally does not exceed 7s. The acceleration or deceleration of motor 123 will be completed within a few seconds.

[0039] 4) Determine if ΔN≤ΔN0 is true. If yes, it means that motor 123 is operating under stable conditions and the operating range of motor 123 speed is determined, proceed to step 5). If no, it means that the operating condition of motor 123 is not yet stable, return to step 3). ΔN0 is set when there is resistance at the outlet of the whole machine. It refers to the preset speed change threshold, which can generally be 30 r / min. ΔN below 30 r / min can be considered as steady state. If motor 123 has not reached steady state, no further logic judgment and adjustment are required.

[0040] 5) Based on the current speed N of motors 1, 2, and 3, calculate the base frequency of the motor speed at this time. The unit of f0 is Hz;

[0041] 6) Based on the preset mapping relationship, the mapping relationship between the suspension height and the first-order rigid body modal frequency of the wind turbine frame 11 is L→f(L). Determine the resonance (resonance between the wind turbine 12 and the wind turbine frame 11) suspension height L(f0) corresponding to f0 at this time; where L refers to the suspension height of the power unit 1, i.e., the distance between the upper surface of the hanging lug 41 and the mounting base 100, and f(L... n () refers to a suspension height of L n The first-order rigid body modal frequency values ​​are obtained in advance based on modal testing, with the mapping relationship being L at the suspension height of the power unit 1. n Under the constraints, the first-order rigid body modal frequency f(L) at this height can be obtained by modal testing using the hammer test method. n (i.e., natural frequency), such as L n When = 30mm, f(L) n ) = 12 Hz; n is a natural number used to distinguish different suspension height parameters L n After obtaining the one-to-one correspondence between different suspension heights and first-order rigid body modal frequencies, the corresponding suspension height can be found by reverse calculation based on the fundamental frequency of the motor speed.

[0042] 7) Determine whether LL(f0)≤ΔL is true. If yes, it means that the current suspension height may cause resonance, and proceed to step 8). If no, it means that the suspension height is safe, and return to step 3). Δ is the current suspension height of the power unit 1, and its value can be obtained by detecting the stroke of the drive mechanism 43, such as by using a Hall element and a magnet. Δ is the preset threshold value for the difference between the actual suspension height and the resonance suspension height. Preferably, its range is between 5mm and 10mm. For example, if Δ = 50mm, and L(f0) = 45mm, then ΔL = 10mm, it means that resonance will occur at this time.

[0043] 8) Monitor the vibration amplitude A at the connection between the current suspension structure and the fan frame 11 (at the lug 41), and determine whether A≥A0 is true. If yes, it indicates that the vibration is too large and the suspension height needs to be adjusted, proceed to step 9). If no, it indicates that the vibration does not affect the user experience at this time, so there is no need to adjust the suspension height, return to step 3). The vibration amplitude can be monitored by setting a vibration sensor. A0 is a preset threshold for the vibration amplitude, preferably A0≤2m / s. 2 ;

[0044] 9) Activate the drive mechanism 43 of the suspension structure to drive the lug 41 (power unit 1) to move upward a unit distance Δh from the current position, preferably not exceeding 5mm, and then return to step 3).

Claims

1. A control method for a range hood, said range hood comprising a power device (1) for being installed above a kitchen ceiling, said power device (1) being installed with a suspension structure with an external installation base (100); said power device (1) comprising a fan frame (11) and a fan (12) disposed in the fan frame (11), said fan (12) comprising an impeller (122) and a motor (123) for driving the impeller (122) to rotate; characterized in that: The control method comprises the following steps: 1) starting the range hood; 2) after the fan (12) is started for a certain time, the rotation speed N of the motor (123) of the fan (12) is monitored; 3) the rotation speed change AN of the motor (123) in a certain time t is calculated; 4) it is judged whether AN≤ΔN0 is true or not, if yes, it indicates that the motor (123) works in a stable working condition, and step 5) is entered, if not, it indicates that the working condition of the motor (123) is not stable, and step 3) is returned to; ΔN0 is a preset threshold value of the rotation speed change; 5) Calculate the current motor speed fundamental frequency based on the current motor speed N 6) According to the mapping relationship L→f(L) between the suspension height of the power device (1) and the first-order rigid modal frequency of the fan stand (11), the suspension height L(L0) of the power device (1) corresponding to f0 is determined, and L(f0) is the resonance suspension height of the power device (1); in this step, the mapping relationship L→f(L) is obtained in advance according to the following method: under the constraint condition that the suspension height of the power device (1) is L n , the first-order rigid modal frequency f(L n ) at this suspension height is obtained by modal test hammering method, and n is a natural number used to distinguish different suspension height parameters L n ; 7) it is judged whether L-L(f0)≤ΔL is true or not, if yes, step 8) is entered, if not, it indicates that the safe suspension height is reached, and step 3) is returned to; L is the current suspension height of the power device (1), and ΔL is a preset difference threshold value between the actual suspension height and the resonance suspension height of the power device (1); 8) the vibration amplitude A of the connection part between the current suspension structure and the fan frame (11) is monitored, and it is judged whether A≥A0 is true or not, if yes, step 9) is entered, if not, step 3) is returned to; A0 is a preset threshold value of the vibration amplitude; 9) the power device (1) is moved by a unit distance Δh from the current position upwards by adjusting the suspension structure, and then step 3) is returned to.

2. The control method of the range hood according to claim 1, characterized in that: The suspension structure comprises a linear drive module.

3. The control method of claim 2, wherein: The suspension structure comprises an ear (41), a rope (42) and a driving mechanism (43), the ear (41) is fixed on the fan frame (11), the driving mechanism (43) comprises an output shaft (431) capable of outputting torque, the lower end of the rope (42) is connected with the ear (41) and the upper end is connected with the output shaft (431), and the rope (42) can be wound on the output shaft (431).

4. The control method of claim 3, wherein: The suspension structure further comprises a pulley mechanism (44), the pulley mechanism (44) comprises a pulley (441) and a support (442), the support (442) is fixed on the lower surface of the installation base (100), the pulley (441) is rotationally arranged on the support (442), the rotation axis of the pulley (441) is parallel to the axis of the output shaft (431), the rope (42) extends outwardly from the output shaft (431) and extends downwardly after passing through the pulley (441) until being fixed with the ear (41).

5. The control method of claim 3, wherein: The suspension structure has four groups, and the suspension structures are respectively arranged at the four corner portions of the top of the fan frame (11).

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