Centrifugal fan blade structure, motor and air conditioner applying same

Abstract

This invention discloses a centrifugal fan structure, a motor, and an air conditioner using the same. The centrifugal fan structure, used in an air conditioner, includes a first mounting plate, a second mounting plate, fan blades, and a hub. One end of the fan blades is mounted on the first mounting plate, and the other end is mounted on the second mounting plate. The hub is located on the second mounting plate and forms a cavity between it and the bottom plate of the air conditioner housing. A silencing hole is provided on the hub, and the silencing hole communicates with the cavity. First, this invention uses the silencing hole to disrupt the nearly sealed cavity formed by the hub and the second mounting plate, reducing cavity resonance noise. Second, the silencing hole on the hub can improve the cavity mode of the enclosed space, avoiding resonance excitation in low-speed spaces, thereby solving the vibration and noise problem of the centrifugal fan structure.

Description

Technical Field

[0001] This invention belongs to the field of motor technology and relates to a centrifugal fan structure, a motor, and an air conditioner using the same. Background Technology

[0002] Built-in air conditioners, also known as ceiling-mounted or recessed units, are increasingly favored by consumers due to their long air delivery distance, aesthetically pleasing appearance, and space-saving design. Their working principle is as follows: the airflow is organized by a backward-facing centrifugal fan blade, undergoing a 90° turn before exiting from the blade outlet. After passing through the heat exchanger, it is further deflected 90° by the outlet airflow channel and blown out. Due to the airflow pattern and the influence of internal damping components such as the heat exchanger and electric auxiliary heating, the internal airflow is complex, containing numerous vortices, affecting the aerodynamic performance and noise of the built-in air conditioner. Furthermore, the large size and complex structure of the centrifugal fan blades in built-in air conditioners result in poor dynamic balance, leading to an imbalance in the reaction force between the fan blades and the motor, making the motor prone to vibration and noise. Therefore, both in principle and in structure, the centrifugal fan blades of built-in air conditioners present a problem of high noise levels. Summary of the Invention

[0003] In view of this, the present invention provides a centrifugal fan blade structure, a motor, and an air conditioner using the same, which solves the vibration and noise problems existing in the existing centrifugal fan blade structure.

[0004] To address the aforementioned problems, according to one aspect of this application, an embodiment of the present invention provides a centrifugal fan structure for an air conditioner. The centrifugal fan structure includes a first mounting plate, a second mounting plate, fan blades, and a hub. One end of the fan blades is mounted on the first mounting plate, and the other end of the fan blades is mounted on the second mounting plate. The hub is disposed on the second mounting plate and forms a cavity between it and the bottom plate of the air conditioner housing. A sound-absorbing hole is provided on the hub, and the sound-absorbing hole communicates with the cavity.

[0005] In some embodiments, multiple noise reduction holes are provided, and the multiple noise reduction holes are evenly distributed along the circumference of the hub.

[0006] In some embodiments, the centrifugal fan structure is capable of eliminating noise at a target attenuation frequency, and the size of the attenuation orifice satisfies the following relationship with the target attenuation frequency:

[0007]

[0008] Where f is the target silencing frequency in Hz; C is the speed of sound in air in m / s; n is the number of silencing holes in units; L is the depth of the cavity in m; t is the thickness of the hub at the silencing hole in m; r is the radius of the silencing hole in m; and R is the radius of the circle containing the silencing hole in m.

[0009] In some embodiments, the thickness t of the wheel hub at the silencing hole is in the range of [0.002, 0.005].

[0010] And / or the radius r of the silencing hole is between [0.002, 0.025];

[0011] And / or the depth L of the cavity is between [0.05, 0.15];

[0012] The number of silencing holes, n, is between [3, 8].

[0013] In some embodiments, the first mounting plate, the second mounting plate, the fan blades, and the wheel hub are integrally formed.

[0014] According to another aspect of this application, embodiments of the present invention also provide an electric motor, the electric motor including the above-described centrifugal fan structure and an electric motor body, the electric motor body being connected to the centrifugal fan structure.

[0015] In some embodiments, the motor further includes a mounting nest, which is fixed to the hub and connected to the motor body.

[0016] In some embodiments, the first mounting plate, the second mounting plate, the fan blade, the hub, and the mounting nest are integrally formed.

[0017] In some embodiments, the motor is an 8-slot 4-pole motor, and the radius r of the silencing hole is 0.0125m.

[0018] According to another aspect of this application, embodiments of the present invention also provide an air conditioner, which includes the motor described above.

[0019] Compared with the prior art, the centrifugal fan blade structure of the present invention has at least the following beneficial effects:

[0020] The centrifugal fan structure provided by the present invention includes a first mounting plate, a second mounting plate, a fan blade, and a hub. One end of the fan blade is mounted on the first mounting plate, and the other end of the fan blade is mounted on the second mounting plate. The hub is disposed on the second mounting plate and forms a cavity between it and the bottom plate of the air conditioner housing. A sound-absorbing hole is provided on the hub and the sound-absorbing hole communicates with the cavity.

[0021] First, the present invention uses silencing holes to disrupt the nearly sealed cavity formed by the hub and the bottom plate of the housing, thereby reducing the resonance noise of the acoustic cavity. Second, the silencing holes opened on the hub can improve the cavity mode of the enclosed space, avoid resonance excitation in the low-speed space, and thus solve the vibration noise problem of the centrifugal fan structure.

[0022] The motor provided by this invention is designed based on the above-described centrifugal fan blade structure. Its beneficial effects are the same as those of the above-described centrifugal fan blade structure, and will not be repeated here.

[0023] The air conditioner provided by this invention is designed based on the above-mentioned motor, and its beneficial effects are the same as those of the above-mentioned motor, which will not be repeated here.

[0024] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, the preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings. Attached Figure Description

[0025] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This is a schematic diagram of a centrifugal fan blade structure provided in an embodiment of the present invention;

[0027] Figure 2 This is a top view of the hub in a centrifugal fan blade structure provided in an embodiment of the present invention;

[0028] Figure 3 This is a front view of a centrifugal fan blade structure provided in an embodiment of the present invention;

[0029] Figure 4 This is a noise comparison diagram between a centrifugal fan blade structure provided by an embodiment of the present invention and a centrifugal fan blade structure of conventional technology.

[0030] in:

[0031] 1. First mounting plate; 2. Second mounting plate; 3. Fan blade; 4. Hub; 5. Cavity; 6. Silencing hole; 7. Mounting nest. Detailed Implementation

[0032] To further illustrate the technical means and effects adopted by the present invention to achieve the intended purpose, the specific embodiments, structures, features, and effects according to the present invention will be described in detail below with reference to the accompanying drawings and preferred embodiments. In the following description, different "an embodiment" or "an embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0033] In the description of this invention, it should be clearly stated that the terms "first," "second," etc., in the specification, claims, and accompanying drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence; the terms "vertical," "lateral," "longitudinal," "front," "rear," "left," "right," "up," "down," "horizontal," etc., indicate orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, and are merely for the convenience of describing this invention, and do not mean that the device or element referred to must have a specific orientation or position, and therefore should not be construed as a limitation of this invention.

[0034] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0035] Example 1

[0036] This embodiment provides a centrifugal fan blade structure, such as Figure 1-3 As shown, for use in an air conditioner, the centrifugal fan structure includes a first mounting plate 1, a second mounting plate 2, fan blades 3, and a hub 4. One end of the fan blades 3 is mounted on the first mounting plate 1, and the other end of the fan blades 3 is mounted on the second mounting plate 2. The hub 4 is disposed on the second mounting plate 2 and forms a cavity 5 between it and the bottom plate of the air conditioner housing. The hub 4 has a sound-absorbing hole 6, and the sound-absorbing hole 6 communicates with the cavity 5.

[0037] Specifically, the overall outline of the first mounting plate 1 and the second mounting plate 2 is circular, with the first mounting plate 1 located above and the second mounting plate 2 located below. The bottom surface of the fan blade 3 is fixed on the second mounting plate 2, and the top surface of the fan blade 3 is fixed on the first mounting plate 1. Generally, 5-9 fan blades 3 are provided and evenly distributed on the circumference between the first mounting plate 1 and the second mounting plate 2. The hub 4 is set on the second mounting plate 2 and forms a nearly sealed cavity 5 between it and the bottom plate of the air conditioner housing. A sound-absorbing hole 6 is opened on the surface of the hub 4. The sound-absorbing hole 6 can be opened at any position of the hub 4 and is connected to the cavity 5.

[0038] When the centrifugal fan structure is working, external air enters the silencer hole 6. When the air column in the silencer hole 6 vibrates under the excitation of external sound waves, the friction between the air column and the hole wall of the silencer hole 6 acts as a damped air spring system. The air column is treated as a mass block, similar to a piston, and the air in the cavity 5 acts as an air spring. Due to the damping effect, the vibration energy of the air column is converted into heat energy and dissipated, i.e., sound energy is absorbed due to friction loss. In other words, the centrifugal fan structure provided in this embodiment uses the silencer hole 6 to break the nearly sealed cavity 5 formed between the hub 4 and the bottom plate of the air conditioner housing, reducing the acoustic cavity resonance noise. The silencer hole 6 opened on the hub 4 can improve the cavity mode of the enclosed space, avoid resonance excitation in the low-speed space, and thus solve the vibration noise problem of the centrifugal fan structure.

[0039] In a specific embodiment, multiple noise-absorbing holes 6 are provided, and the multiple noise-absorbing holes 6 are evenly distributed along the circumference of the wheel hub 4. The number of noise-absorbing holes 6 is preferably 5 or 6.

[0040] In a specific embodiment, the centrifugal fan structure can eliminate noise at the target noise reduction frequency, and the size of the noise reduction hole 6 satisfies the following relationship with the target noise reduction frequency:

[0041]

[0042] Where f is the target noise reduction frequency in Hz; C is the speed of sound in air in m / s; n is the number of noise reduction holes 6 in units; L is the depth of the cavity 5 in m; t is the thickness of the hub 4 at the noise reduction hole 6 in m; r is the radius of the noise reduction hole 6 in m; and R is the radius of the circle containing the noise reduction hole 6 in m.

[0043] When the frequency of the target silencing sound wave matches the system's resonant frequency, the air at the aperture of the silencing hole 6 undergoes intense vibration and friction, converting sound energy into heat energy and forming an absorption peak, thus significantly attenuating the sound energy. The relationship between the target silencing frequency and the design of the centrifugal fan blade silencing structure is shown in the formula above.

[0044] In a specific embodiment, the thickness t of the hub 4 at the sound-absorbing hole 6 is located in the range of [0.002, 0.005].

[0045] And / or the radius r of the silencing hole 6 is between [0.002, 0.025];

[0046] And / or the depth L of the cavity 5 is between [0.05, 0.15];

[0047] And / or the number n of the silencing holes 6 is between [3, 8].

[0048] The thickness t of the hub 4 at the muffler hole 6 is generally determined by design and production, and its value is in the range of [0.002, 0.005]. The radius R of the circle containing the muffler hole 6 mainly meets the motor installation requirements and is confirmed by the motor dimensions. The parameters that need to be calculated are the depth L of the cavity 5, the radius r of the muffler hole 6, and the perforation rate, where the perforation rate is determined by the radius r of the muffler hole 6, the number n of the muffler holes 6, and the area of ​​the cavity 5.

[0049] Based on the above formula, in order to solve the discrete noise in a certain frequency range [f1,f2], structural parameters such as the depth L of the cavity 5 and the radius r of the silencing hole 6 can be calculated.

[0050] The centrifugal fan structure provided in this embodiment has different radii r of the silencing holes 6 for different noise reduction frequency requirements. In this embodiment, to ensure the optimal noise reduction effect and strength requirements, it is recommended that the hub perforation radius r be in the range of [0.002, 0.025]. The perforation rate is determined by the perforation radius r and the number of perforations n. Considering the heat exchange effect of the motor, it is recommended that the number of openings be 3-8, evenly distributed on a circle with a radius of R, where R is determined by the motor size.

[0051] In a specific embodiment, the first mounting plate 1, the second mounting plate 2, the wind blade 3, and the wheel hub 4 are integrally formed.

[0052] Traditional centrifugal fan blades often employ gas-assisted molding combined with ultrasonic welding or separate mold opening combined with ultrasonic welding, requiring investment in production equipment and the establishment of production lines. In contrast, this embodiment adopts an integrated injection molding technology, which can save on equipment and production line investment, significantly reduce production and R&D costs, and shorten the production cycle.

[0053] Example 2

[0054] This embodiment provides a motor, which includes the centrifugal fan blade structure described in Embodiment 1 and a motor body, wherein the motor body is connected to the centrifugal fan blade structure.

[0055] The motor provided in this embodiment uses the centrifugal fan structure in Embodiment 1, and therefore includes all the beneficial effects produced by the centrifugal fan structure in Embodiment 1; at the same time, the motor provided in this embodiment uses a porous hub, which can ensure the heat dissipation of the motor; and reduces the cost of product design while ensuring structural strength.

[0056] In a specific embodiment, the motor further includes a mounting nest 7, which is fixed to the hub 4 and connected to the motor body. More specifically, the mounting nest 7 is a columnar structure located in the cavity 5, with one end extending out of the hub 4, the extended portion being used for connection to the motor body.

[0057] In a specific embodiment, the first mounting plate 1, the second mounting plate 2, the wind blade 3, the hub 4, and the mounting nest 7 are integrally formed.

[0058] In a specific embodiment, the motor is an 8-slot 4-pole motor, and the radius r of the silencing hole 6 is 0.0125m.

[0059] The rotational speed of a typical backward centrifugal fan used in air conditioning is below 1000 RPM. The commutation noise of a DC motor driven fan is calculated as follows:

[0060]

[0061] f1 is the commutation noise frequency, P is the number of pole pairs, and N is the motor speed. For a commonly used 8-slot, 4-pole motor, the commutation noise frequency is between 100-400Hz.

[0062] The centrifugal fan structure described in Example 1 is used to solve the motor's rotation noise problem, specifically as follows:

[0063] In a certain case, the centrifugal fan operates at a speed of 660 RPM, using an 8-slot, 4-pole motor with a fundamental frequency of 264 Hz rotational noise. The fan blade diameter is 0.46 m, the cavity depth is L = 0.1 m, the cavity radius is R = 0.133 m, the number of openings is 5, and the fan blade thickness is t = 0.002 m. Based on the above calculations, the hub opening radius is r = 0.0125 m. A prototype fan blade was designed based on the above specifications, and specific noise testing was conducted as follows... Figure 4 As shown.

[0064] As can be clearly seen from the figure, the total noise level of the motor designed using the scheme in this embodiment is reduced by 2-4 dB(A) under the same air volume, achieving a better noise reduction effect.

[0065] Example 3

[0066] This embodiment provides an air conditioner, which includes the motor described in Embodiment 2.

[0067] The air conditioner provided in this embodiment uses the motor in embodiment 2, and therefore includes all the beneficial effects produced by the motor in embodiment 2 and all the beneficial effects produced by the centrifugal fan structure in embodiment 1.

[0068] In summary, it is readily understood by those skilled in the art that, without conflict, the aforementioned advantageous technical features can be freely combined and superimposed.

[0069] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any way. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A centrifugal fan blade structure, characterized in that, The centrifugal fan structure is used in an air conditioner. The centrifugal fan structure includes a first mounting plate, a second mounting plate, fan blades, and a hub. One end of the fan blades is mounted on the first mounting plate, and the other end of the fan blades is mounted on the second mounting plate. The hub is disposed on the second mounting plate and forms a cavity between it and the bottom plate of the air conditioner housing. The hub has a sound-absorbing hole, and the sound-absorbing hole communicates with the cavity. The centrifugal fan structure can eliminate noise at the target noise reduction frequency, and the size of the noise reduction hole satisfies the following relationship with the target noise reduction frequency: Where f is the target noise reduction frequency in Hz; C is the speed of sound in air in m / s; n is the number of noise reduction holes in units; L is the depth of the cavity in m; t is the thickness of the hub at the noise reduction hole in m; r is the radius of the noise reduction hole in m; and R is the radius of the circle containing the noise reduction hole in m.

2. The centrifugal fan blade structure according to claim 1, characterized in that, The silencing holes are provided in multiple ways, and the multiple silencing holes are evenly distributed along the circumference of the wheel hub.

3. The centrifugal fan blade structure according to claim 2, characterized in that, The thickness t of the wheel hub at the silencing hole is in the range of [0.002, 0.005]. And / or the radius r of the silencing hole is between [0.002, 0.025]; And / or the depth L of the cavity is between [0.05, 0.15]; And / or the number of the silencing holes n is between [3, 8].

4. The centrifugal fan blade structure according to any one of claims 1-3, characterized in that, The first mounting plate, the second mounting plate, the wind blade, and the wheel hub are integrally formed.

5. An electric motor, characterized in that, The motor includes the centrifugal fan blade structure as described in any one of claims 1-4 and a motor body, wherein the motor body is connected to the centrifugal fan blade structure.

6. The motor according to claim 5, characterized in that, The motor also includes a mounting nest, which is fixed on the hub and connected to the motor body.

7. The motor according to claim 6, characterized in that, The first mounting plate, the second mounting plate, the wind blade, the hub, and the mounting nest are integrally formed.

8. The motor according to claim 7, characterized in that, The motor is an 8-slot, 4-pole motor, and the radius r of the silencing hole is 0.0125m.

9. An air conditioner, characterized in that, The air conditioner includes the motor as described in any one of claims 5-8.

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