A fan assembly, a range hood and a control method of the range hood

Abstract

The application discloses a fan assembly, a range hood and a control method of the range hood. The fan assembly comprises a centrifugal fan, a noise reduction assembly for absorbing noise in the fan assembly and an air outlet cover arranged at an air outlet of the centrifugal fan. The centrifugal fan comprises a volute and an impeller arranged in the volute. The volute has a volute tongue. The noise reduction assembly comprises sound-absorbing cotton. The fan assembly further comprises a branch system capable of sucking air flow at the volute tongue in the volute into the air outlet cover, thereby widening the frequency band width of noise at the volute tongue. Compared with the prior art, the application has the advantages that by arranging the branch system for sucking air flow near the volute tongue, the periodic flow characteristics at the volute tongue can be destroyed, the noise frequency band is widened, the proportion of noise distribution in the frequency band with poor sound absorption coefficient caused by pressure pulsation or vortex shedding at the volute tongue is reduced, the sound absorption effect of the sound-absorbing cotton is improved, and the overall machine noise is reduced.

Description

Technical Field

[0001] This invention relates to a power device, and more particularly to a fan assembly, a range hood using the fan assembly, and a control method for the range hood. Background Technology

[0002] Multi-blade centrifugal fans are characterized by high pressure and low noise, making them a common power source for many systems. They utilize a high-speed rotating impeller within a volute to perform both work and filtration. For example, they are frequently used in range hoods. A multi-blade centrifugal fan installed inside the hood draws in and exhausts cooking fumes. The fan consists of a volute, an impeller housed within the volute, and a motor that drives the impeller. As the impeller rotates, a negative pressure suction is generated at the center of the fan, drawing the cooking fumes from below into the fan. After being accelerated by the fan, the volute collects the fumes and guides them outdoors.

[0003] Centrifugal fans are the main noise source of range hoods, and they are usually installed inside the fan frame. To reduce noise, a common practice is to install sound-absorbing components inside the fan frame. For example, Chinese Patent Application No. 201610738828.6 discloses a three-dimensional noise reduction system for range hoods that guides airflow and absorbs sound. It includes a main unit housing and an air duct system installed inside the main unit housing. The air duct system includes a fan housing and a fan inlet installed on the fan housing. A main airflow noise reduction body extending vertically is provided on the inner side of the main unit housing opposite to the fan inlet. The main airflow noise reduction body has a first hollow inner cavity, and the first hollow inner cavity contains internal sound-absorbing material.

[0004] The noise reduction frequency band of the sound-absorbing component is designed for the mid-to-high frequency range, but the sound absorption coefficient may not be ideal in some frequency bands. There are periodic flow characteristics such as dynamic and static interference, pressure pulsation, and vortex shedding at the volute tongue, which will eventually lead to a discrete (narrowband) noise. If this noise occurs in the frequency band where the sound-absorbing cotton has poor sound absorption effect, it will lead to an increase in overall noise. Summary of the Invention

[0005] The first technical problem to be solved by the present invention is to address the shortcomings of the prior art by providing a fan assembly that changes the bandwidth of discrete noise near the volute tongue and improves the absorption effect of the sound absorption assembly.

[0006] The second technical problem to be solved by the present invention is to provide a range hood that uses the above-mentioned fan assembly.

[0007] The third technical problem to be solved by the present invention is to provide a control method for the above-mentioned range hood.

[0008] The technical solution adopted by the present invention to solve the first technical problem mentioned above is as follows: a fan assembly, comprising a centrifugal fan, a noise reduction assembly for absorbing noise within the fan assembly, and an air outlet hood disposed at the air outlet of the centrifugal fan, wherein the centrifugal fan comprises a volute and an impeller disposed within the volute, the volute having a volute tongue, and the noise reduction assembly comprising sound-absorbing cotton; characterized in that:

[0009] The fan assembly also includes a branch system that can draw airflow from the volute tongue inside the volute into the exhaust shroud, thereby widening the frequency bandwidth of the noise at the volute tongue.

[0010] Discrete (narrowband) noise is caused by flow characteristics such as periodic pressure pulsation at the volute. By setting up a branch system to draw airflow near the volute tongue, the periodic flow characteristics at the volute tongue can be disrupted, the noise frequency band can be widened, and the proportion of noise caused by pressure pulsation or vortex shedding at the volute tongue in the frequency band with poor sound absorption coefficient can be reduced. This improves the noise absorption effect of the sound-absorbing cotton and reduces the overall noise of the machine.

[0011] Furthermore, to facilitate the suction of airflow at the volute tongue, the volute tongue is a hollow component, and a perforation is provided on the side of the volute tongue facing the inside of the volute shell;

[0012] The branch system includes a suction pump, a first pipe, and a second pipe. The first pipe connects the outlet of the suction pump to the fluid inside the air outlet hood, and the second pipe connects the inlet of the suction pump to the fluid inside the volute tongue, and then to the fluid inside the volute. The suction pump is located outside the volute.

[0013] To prevent noise from the suction pump from propagating downwards, the suction pump is positioned above the sound-absorbing cotton.

[0014] To facilitate airflow guidance, increase the contact time between the airflow and the sound-absorbing cotton, and improve the sound absorption effect, the noise reduction component also includes a guide plate. The guide plate extends from both sides of the volute width direction to above the air inlet of the centrifugal fan. The sound-absorbing cotton is arranged on the upper surface of the guide plate, and noise reduction holes are opened on the guide plate.

[0015] To better guide the airflow along the guide plate, the guide plate includes a first guide section and a second guide section. The outline of the cross-section of the two guide sections is a spline curve. The first guide section extends upward from one side of the volute width direction to above the air inlet, and the second guide section extends upward from the other side of the volute width direction to above the air inlet. The first guide section and the second guide section are connected as one unit above the air inlet.

[0016] Furthermore, the junction of the first and second guide portions corresponds to the volute tongue and protrudes downward, thereby improving the noise reduction capability at the volute tongue.

[0017] Furthermore, a cavity is formed between the sound-absorbing cotton and the two guide sections, and the other parts of the sound-absorbing cotton are in close contact with the guide plate. This changes the sound-absorbing frequency band of the sound-absorbing cotton at the junction, shifting its absorption frequency band to the volute noise frequency band, thus enhancing the targeting and noise reduction effect of the sound-absorbing cotton at that point on volute noise.

[0018] The technical solution adopted by the present invention to solve the second technical problem mentioned above is: a range hood, characterized in that: it uses the fan assembly described above.

[0019] The technical solution adopted by the present invention to solve the third technical problem mentioned above is: a control method for a range hood, characterized in that: the range hood includes the fan assembly as described above, the impeller includes blades, and the control method includes the following steps:

[0020] S1) Detect the relative position of a selected blade of the impeller and the volute tongue;

[0021] S2) When the impeller rotates to the point where the selected blades rotate to the minimum distance from the volute tongue, control the suction pump to operate at the maximum duty cycle.

[0022] S3) Let t = 0 be the time when the suction pump starts working with the maximum duty cycle. During one rotation of the impeller, the duty cycle of the suction pump at any other time t is the maximum duty cycle * cos(2π * z * n * t / 60), where z is the number of blades and n is the rotational speed of the impeller (12).

[0023] During the subsequent rotation of the impeller, the suction pump operates in the aforementioned duty cycle variation manner.

[0024] Preferably, in step S2), the suction pump is controlled by the duty cycle of a sine wave, wherein the wavelength of the sine wave is 1 / n*z.

[0025] Compared with the prior art, the advantages of this invention are as follows: By setting up a branch system to draw airflow near the volute tongue, the periodic flow characteristics at the volute tongue can be disrupted, the noise frequency band can be broadened, and the proportion of noise caused by pressure pulsation or vortex shedding at the volute tongue in the frequency band with poor sound absorption coefficient can be reduced, thereby improving the noise absorption effect of the sound-absorbing cotton and reducing the overall noise of the machine; by using a guide plate formed by two curves connected near the volute tongue, a cavity is formed between the connection point and the sound-absorbing cotton, thereby changing the sound absorption band of the sound-absorbing cotton at the connection point, causing its absorption frequency band to shift to the noise frequency band of the volute tongue, enhancing the targeting and noise reduction effect of the sound-absorbing cotton on the volute tongue noise at this point; by controlling the suction pump with the duty cycle, the maximum duty cycle is when the blade is closest to the volute tongue, and the suction volume of the suction pump changes continuously during the suction process, thereby modulating the discrete noise at the volute tongue, better achieving the disruption of the periodic flow characteristics at the volute tongue, broadening its frequency band, and increasing the absorption effect of the sound-absorbing cotton on it. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of a wind turbine assembly according to an embodiment of the present invention;

[0027] Figure 2 This is a cross-sectional view (viewed from back to front, left and right sections) of the wind turbine assembly according to an embodiment of the present invention;

[0028] Figure 3 This is a cross-sectional view of the wind turbine assembly according to an embodiment of the present invention (viewed from back to front, the cross-section is the same as...). Figure 2 parallel);

[0029] Figure 4 This is a cross-sectional view of the wind turbine assembly with the impeller hidden, according to an embodiment of the present invention (the cross-sections are in the front-to-back direction and the left-to-right direction, respectively);

[0030] Figure 5 This is a schematic diagram of the volute, air outlet shroud, and branch system of the fan assembly according to an embodiment of the present invention. Detailed Implementation

[0031] 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.

[0032] 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.

[0033] See Figures 1-4 A range hood includes a fan assembly comprising a centrifugal fan 1 and an exhaust hood 2 disposed at the exhaust outlet of the centrifugal fan 1. The range hood also includes a fan frame 3, within which the centrifugal fan 1 can be installed. The form of the range hood is not limited and can be applied to any form of range hood in the prior art, preferably to a top-mounted range hood.

[0034] Centrifugal fan 1 includes a volute 11 and an impeller 12 disposed within the volute 11. The volute 11 has an air inlet 111 and an air outlet 112. An air outlet shroud 2 is disposed at the air outlet 112 and can be located on a fan frame 3. The volute 11 also includes a volute tongue 113. The impeller 12 includes multiple blades 121. The above-described structure of centrifugal fan 1 is prior art and will not be described in detail here.

[0035] The volute tongue 113 is a hollow component with a perforation 114 on its side facing inwards from the volute housing 11. Multiple perforations 114 are spaced apart on the volute tongue 113, allowing communication between the outside and inside of the volute housing 11. The fan assembly also includes a branch system comprising a suction pump 41, a first pipe 42, and a second pipe 43. The first pipe 42 connects the outlet of the suction pump 41 to the inside of the exhaust hood 2, and the second pipe 43 connects the inlet of the suction pump 41 to the inside of the volute tongue 113. The suction pump 41 and the first pipe 42 are located outside the volute housing 11, while the second pipe 43 partially extends into the volute tongue 113. Preferably, the suction pump 41 is located in the diffuser section of the volute housing 11 (i.e., the outlet section above the volute tongue 113). This forms a branch system starting from the volute tongue 113 and extending to the exhaust hood 2, distinct from the main channel within the volute housing 11.

[0036] When the suction pump 41 is working, it can draw the airflow from the volute tongue 113 (referring to the space on the surface of the volute tongue 113 and near the volute tongue 113) into the volute tongue 113 and deliver it to the air outlet shroud 2 through the first pipe 42. As a result, the frequency bandwidth of the noise at the volute tongue 113 can be widened.

[0037] The fan assembly also includes a noise reduction component disposed on the outside of the volute 11. This noise reduction component includes a guide vane 51 and sound-absorbing cotton 52. The guide vane 51 is disposed at the corresponding location of the air inlet 111 of the volute 11, extending along the width direction of the volute 11. Figure 2 The air intake 111 is extended to both sides (in the left and right directions). Sound-absorbing cotton 52 is arranged on the upper surface of the air guide plate 51.

[0038] The guide plate 51 includes a first guide section 511 and a second guide section 512. The outlines of the cross-sections of the two guide sections (the outlines are the cross-sectional curves of the lower or upper surface of the guide plate 51; preferably, the guide plate 51 is a plate of equal thickness, and the cross-sectional curves of the two surfaces are the same) are both spline curves. The first guide section 511 extends upward from one side of the volute 11 in the width direction to above the air inlet 111, and the second guide section 512 extends upward from the other side of the volute 11 in the width direction to above the air inlet 111. The first guide section 511 and the second guide section 512 are joined together above the air inlet 111, and this joining position is located near the volute tongue 113 and protrudes downward. Each guide section is provided with a noise reduction hole 513. The diameter d of the noise reduction hole 513 is related to the sound radiation frequency and the characteristics of the sound-absorbing cotton, and is generally 4-5 mm. The center distance between the holes is 2-2.5d. The function of the guide vane 51 is to guide the airflow flowing in from the lower inlet of the fan assembly along the guide vane 51 until it is sucked into the volute 11.

[0039] By attaching the sound-absorbing cotton 52 to the upper surface of the guide plate 51, the direction of the airflow velocity can be tangential to the surface of the sound-absorbing cotton 52 for a longer period of time, thereby achieving the most ideal utilization effect of the sound-absorbing cotton. At the same time, guiding the airflow along the guide plate 51 can increase the contact time between some airflow and the sound-absorbing cotton 52. At the junction of the two guide sections, the sound-absorbing cotton 52 is not tightly attached to the junction, thus forming a cavity 53. This makes the sound-absorbing frequency band of the sound-absorbing cotton 52 at this position closer to the noise frequency band at the volute tongue 113, and also closer to the volute tongue 113, which facilitates timely absorption of noise at the volute tongue 113 and prevents it from diffusing in the air duct.

[0040] The width of the baffle plate 51 and the sound-absorbing cotton 52 should be as large as possible, preferably close to the corresponding walls of the volute 11 and the fan frame 3, respectively, thereby dividing the space of this part of the fan frame 3 into upper and lower parts. The noise reduction component should be installed below the suction pump 41 to prevent the noise generated by the suction pump 41 from being directly transmitted to the lower inlet of the fan component (i.e., the connection with the air intake components such as the smoke hood), thereby reducing the noise of the fan component.

[0041] In summary, considering the difference between the noise frequency band at the volute tongue 113 and other locations inside the fan, the perforated guide plate was changed from the commonly used single arc or single line to a structure composed of at least two curves. Crucially, the two curves connect at the volute tongue 113, and the guide plate 51 protrudes downwards at this connection point, ensuring that the entire guide plate 51 has a cavity 53 only between the volute tongue 113 and the sound-absorbing cotton 52. Based on the principle of sound-absorbing cavities (different cavity sizes result in different sound-absorbing bands, and the sound-absorbing cotton also contains tiny cavities), the sound-absorbing band of the sound-absorbing cotton at this location was altered (or the sound-absorbing band varies at different locations), causing its absorption frequency band to shift to the volute tongue noise frequency band, thus enhancing the targeting and noise reduction effect of the sound-absorbing cotton 52 on the volute tongue 113 noise.

[0042] The control method for a range hood using the above-mentioned fan assembly may specifically include the following steps:

[0043] S1) Detect the relative position of a selected blade 121 of the impeller 12 (one of multiple blades 121 can be selected) and the volute tongue 113. For example, a Hall sensor can be set on the blade 121 and a magnet can be set on the volute tongue 113 for detection. Other methods can also be used, such as laser, infrared, etc.

[0044] S2) The suction pump 41 is controlled by the duty cycle of a sinusoidal waveform with a wavelength of 1 / n*z, where z is the number of blades and n is the impeller speed. When the selected blade 121 rotates to the point where the distance between it and the volute tongue 113 is the smallest, the suction pump 41 is controlled to operate at the maximum duty cycle. That is, the peak of the sinusoidal waveform is the moment when the specific blade 121 is closest to the volute tongue 113. The principle of this control is as follows: Since the flow characteristics such as pressure pulsation at the volute tongue 113 are generated by the mutual interference between the blade 121 and the volute tongue 113 when the centrifugal fan 1 rotates, it will exhibit strong periodicity, and the period frequency is the frequency of the blade 121 passing through the volute tongue 113 (i.e., n*z). Therefore, the branch system needs to periodically change the suction flow rate accordingly. The two periods must be the same, otherwise it may aggravate the narrow band noise characteristics. Similarly, the maximum suction flow rate is at the moment when the blade 121 is closest to the volute tongue 113, which can make the pressure pulsation at the volute tongue 113 tend to be smoother throughout the cycle. Finally, the frequency band of the noise concentrated at the blade frequency is lengthened.

[0045] S3) Taking the moment when the pump starts working with the maximum duty cycle as t=0, within one revolution of the impeller 12, the duty cycle (speed) of the suction pump 41 at any other time t is equal to the maximum duty cycle * cos(2π*z*n*t / 60). During the subsequent revolution of the impeller 12, the duty cycle changes in the same way as above, that is, the distance between a selected blade 121 and the volute tongue 113 is detected in real time. When the distance between the selected blade 121 and the volute tongue 113 is the smallest, the duty cycle of the suction pump 41 is maximized. In the following revolution, the duty cycle of the suction pump 41 adopts the above formula. Thus, the operation of the suction pump 41 exhibits a periodic change, and the period of change corresponds to one revolution of the impeller 12.

[0046] 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 fan assembly comprising a centrifugal fan (1), a noise reduction assembly for absorbing noise in the fan assembly, and an air outlet cover (2) arranged at an air outlet of the centrifugal fan (1), the centrifugal fan (1) comprising a volute (11) and an impeller (12) arranged in the volute (11), the volute (11) having a volute tongue (113), and the noise reduction assembly comprising sound-absorbing cotton (52); characterized in that: the volute tongue (113) is a hollow component, and a plurality of perforations (114) are formed on a side of the volute tongue (113) facing the volute (11); the fan assembly further comprises a bypass system capable of sucking air flow at the volute tongue (113) in the volute (11) into the air outlet cover (2), the bypass system comprising a suction pump (41), a first pipeline (42), and a second pipeline (43), the first pipeline (42) fluidly connecting an outlet of the suction pump (41) and an inside of the air outlet cover (2), and the second pipeline (43) fluidly connecting an inlet of the suction pump (41) and the volute tongue (113), and further fluidly connecting an inside of the volute (11); the suction pump (41) is located outside the volute (11), and when the suction pump (41) is working, air flow at the volute tongue (113) is sucked into the volute tongue (113) to widen a frequency band width of noise at the volute tongue (113). the suction pump (41) is located above the sound-absorbing cotton (52).

2. The fan assembly of claim 1, wherein: the noise reduction assembly further comprises a flow guide plate (51), the flow guide plate (51) extending from both sides of the volute (11) in a width direction to above an air inlet (111) of the centrifugal fan (1), the sound-absorbing cotton (52) is arranged on an upper surface of the flow guide plate (51), and a plurality of noise reduction holes (513) are formed on the flow guide plate (51).

3. The fan assembly of claim 1 or 2, wherein: the flow guide plate (51) comprises a first flow guide part (511) and a second flow guide part (512), a profile line of a cross section of each of the two flow guide parts is a spline curve, the first flow guide part (511) extends upward from one side of the volute (11) in the width direction to above the air inlet (111), the second flow guide part (512) extends upward from the other side of the volute (11) in the width direction to above the air inlet (111), and the first flow guide part (511) and the second flow guide part (512) are connected integrally at a position above the air inlet (111).

4. The fan assembly of claim 3, wherein: the first flow guide part (511) and the second flow guide part (512) are connected integrally at a position corresponding to the volute tongue (113) and protruding downward.

5. The fan assembly of claim 4, wherein: a cavity (53) is formed between the sound-absorbing cotton (52) and a position where the two flow guide parts are connected, and other parts of the sound-absorbing cotton (52) are tightly attached to the flow guide plate (51).

6. The fan assembly of claim 5, wherein: The fan assembly according to any one of claims 1-6 is applied.

7. A range hood characterized by: The range hood comprises the fan assembly according to claim 1, the impeller (12) comprises blades (121), and the control method comprises the following steps:

8. A control method of a range hood, characterized by: S1) detecting a relative position between a selected blade (121) of the impeller (12) and the volute tongue (113). ​ S2) When the impeller (12) rotates to the point where the selected blade (121) rotates to the minimum distance from the volute tongue (113), the suction pump (41) is controlled to operate at the maximum duty cycle. S3) Let t=0 be the time when the suction pump (41) starts working with the maximum duty cycle. Within one revolution of the impeller (12), the duty cycle of the suction pump (41) at any other time t is = maximum duty cycle * cos(2π * z * n * t / 60), where z is the number of blades and n is the rotational speed of the impeller (12). During the subsequent rotation of the impeller (12), the suction pump (41) operates in the manner described above with varying duty cycle.

9. The control method of claim 8, wherein: In step S2), the suction pump (41) is controlled by the duty cycle of the sine wave, the wavelength of which is 1 / n*z.

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