fan

Abstract

The application discloses a fan, comprising a casing, an impeller and a motor, the casing is provided with an air inlet and an air outlet, and an impeller cavity is formed in the casing; the impeller is assembled in the impeller cavity, is configured to take in air in an axial direction and discharge air in a radial direction, and is driven by the motor to rotate around an axis; the impeller cavity is provided with an annular throat air duct, the throat air duct is located below an outlet of the impeller; an effective flow area of the impeller outlet is S1, a minimum flow area of the throat air duct is S2, and 0.6S1

Description

Technical Field

[0001] This application relates to a fan, and more particularly to a fan that reduces turbulence noise by optimizing the air duct. Background Technology

[0002] A ventilator is an external respiratory air supply device used for respiratory therapy or assisted ventilation. The turbine fan is one of the core components of a ventilator; the required flow rate and pressure come from the turbine fan, and its operating pressure, flow rate, and noise level directly affect the ventilator's performance. Medical emergency ventilators primarily focus on maintaining and restoring respiratory physiological characteristics and have a relatively high tolerance for noise. Home ventilators are often used in non-emergency situations, such as improving sleep apnea (commonly known as snoring), where users have a more stringent noise tolerance, hoping the ventilator will not cause noise interference and will ensure a quiet sleep environment. The main source of turbine fan noise is aerodynamic noise; the high-speed impact of airflow against the wall during impeller rotation and the turbulence created by the airflow itself all generate noise. Current low-noise fan products mainly improve noise performance by optimizing the impeller shape; however, noise generation is not only related to the impeller but also closely related to the volute, requiring comprehensive consideration to achieve optimal noise reduction. Summary of the Invention

[0003] This application provides a fan that ensures the fan's flow rate while also achieving lower turbulence noise and improving noise reduction.

[0004] A fan includes a casing, an impeller, and a motor. The casing has an air inlet and an air outlet, and an impeller cavity is formed inside it. The impeller is assembled in the impeller cavity and is configured to axially inlet and radially outlet, and is driven by the motor to rotate around an axis. The impeller cavity is provided with an annular throat duct, and the position of the throat duct is lower than the outlet of the impeller.

[0005] The effective flow area at the impeller outlet is S1, and the minimum flow area at the throat duct is S2, both satisfying: 0.6S1 <S2<1.5S1。

[0006] Several alternative methods are provided below, but they are not intended as additional limitations on the overall solution above. They are merely further additions or optimizations. Provided there are no technical or logical contradictions, each alternative method can be combined individually with respect to the overall solution above, or multiple alternative methods can be combined with each other.

[0007] Optional, 0.6S1 < S2 < S1.

[0008] Optionally, 0.6S1 < S2 < 0.8S1.

[0009] Optionally, the interior of the housing forms an annular cavity surrounding the motor, and the impeller cavity and the annular cavity are arranged adjacent to each other in the axial direction.

[0010] Optionally, the annular cavity is defined by the inner wall surface of the housing; or the annular cavity is defined by the inner wall surface of the housing and the motor housing together.

[0011] Optionally, the annular cavity includes an inner annular wall and an outer annular wall arranged coaxially, the inner annular wall having a plurality of first partitions, each of the first partitions forming a first gap with the outer annular wall; and / or, the outer annular wall having a plurality of second partitions, each of the second partitions forming a second gap with the inner annular wall.

[0012] Optionally, the flow area of ​​the first gap and the flow area of ​​the second gap are both greater than the effective flow area S1 of the impeller outlet.

[0013] Optionally, the first partition and the second partition are arranged alternately along the axial direction to form a deflection path within the annular cavity.

[0014] Optionally, the number of the first partitions is two, the number of the second partitions is one, and the second partition is located between the two first partitions.

[0015] Optionally, each of the first partitions and the second partitions is arranged to extend continuously in the circumferential direction.

[0016] Optionally, the impeller includes a lower cover plate and a plurality of blades extending radially, with flow channels formed between adjacent blades. The gap between the lower cover plate and the inner wall of the housing is defined as the throat air duct, and the minimum flow area of ​​the gap is S2.

[0017] Optionally, the housing includes an upper housing and a lower housing stacked along the axial direction. The upper housing is provided with the air inlet, and the center of the lower housing is provided with a motor mounting cavity for accommodating the motor. The upper housing and the lower housing together form the air outlet.

[0018] Optionally, the air inlet is directly opposite the center inlet of the impeller, and the air outlet is located on the radial outer wall of the annular cavity.

[0019] After the airflow of the fan in this application is discharged from the impeller outlet, it is reflected by the inner wall of the impeller cavity and then passes through the throat duct. By controlling the relationship between S1 and S2, the flow rate of the fan is guaranteed, while the turbulence noise is reduced, thus achieving a better noise reduction effect. Attached Figure Description

[0020] Figure 1 This is a perspective view of a fan according to an embodiment of this application;

[0021] Figure 2 for Figure 1 Front view of the fan;

[0022] Figure 3 for Figure 2 A cross-sectional view along the AA direction;

[0023] Figure 4 for Figure 2 A cross-sectional view along the AA direction;

[0024] Figure 5 This is a perspective view of the impeller in a fan according to an embodiment of this application;

[0025] Figure 6 for Figure 2 A cross-sectional view along the AA direction;

[0026] Figure 7 This is a front view of an impeller according to an embodiment of this application;

[0027] Figure 8 for Figure 7 Enlarged view of section E in the middle;

[0028] Figure 9 for Figure 3 Cross-sectional view along the BB direction;

[0029] Figure 10 for Figure 3 A cross-sectional view along the CC direction;

[0030] Figure 11 for Figure 3 A cross-sectional view along the DD direction;

[0031] Figure 12 for Figure 2 A cross-sectional view of another embodiment in the AA direction;

[0032] Figure 13 This is an exploded view of a fan according to an embodiment of this application.

[0033] The annotations in the figure are explained as follows:

[0034] 11. Axis; 100. Housing; 101. Air inlet; 102. Air outlet; 103. Flow channel; 104. Third gap; 105. Throat duct; 110. Upper housing; 120. Lower housing; 131. Impeller cavity; 132. Motor mounting cavity; 133. Annular cavity; 1331. Inner annular wall; 1332. Outer annular wall; 141a. First partition; 141b. First partition; 142. Second partition; 151. First gap; 152. Second gap; 160. Baffle section; 170. Guide section; 171. Upper section; 172. Middle section; 173. Lower section; 174. Protrusion;

[0035] 200, Impeller; 210, Lower cover plate; 211, Upper surface; 220, Blade; 300, Motor. Detailed Implementation

[0036] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0037] It should be noted that when a component is said to be "connected" to another component, it can be directly connected to the other component or it can be connected to a component in between. When a component is said to be "set on" another component, it can be directly set on the other component or it may be set to a component in between.

[0038] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0039] In this application, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number or order of the indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0040] like Figures 1-3 As shown, this application provides a fan, including a casing 100, an impeller 200 disposed inside the casing 100, and a motor 300 (shown by thick dashed lines in the figures) driving the impeller 200. The casing 100, impeller 200, and motor 300 are coaxially arranged. For ease of understanding and description, the airflow path is indicated by dashed lines with arrows in the figures of this application. The casing 100 has the illustrated axis 11 and the opposite radial direction.

[0041] The housing 100 is provided with an air inlet 101 and an air outlet 102, and an air duct extending between the air inlet 101 and the air outlet 102 is formed inside the housing 100. In some embodiments, such as Figure 1 As shown, the air inlet 101 is located at the center of the top surface of the housing 100, and the air outlet 102 is located on the side of the housing 100.

[0042] The impeller 200 of this application is a centrifugal structure, employing axial air inlet and radial air outlet. In some embodiments, such as Figure 5 As shown, the impeller 200 includes a lower cover plate 210 and a plurality of blades 220 extending radially along the lower cover plate 210, with flow channels 103 formed between adjacent blades 220. Obviously, the impeller 200 may also be provided with an upper cover plate opposite to the lower cover plate.

[0043] The impeller 200 has an inlet in its central region and an outlet on its outer peripheral side. The flow channel 103 between the blades 220 extends between the inlet and the outlet. In this embodiment, the inlet of the impeller 200 is aligned with the air inlet 101, and the outlet is aligned with the inner wall of the casing 100.

[0044] Motor 300 includes a motor housing and an output shaft, in some embodiments, such as Figure 3 As shown, a motor mounting cavity 132 is provided at the center of the bottom surface of the housing 100. The shape and size of the motor housing are adapted to the motor mounting cavity 132 and engage with the housing 100 to close the opening at the bottom of the housing 100. The output shaft extends into the housing 100 and connects to the impeller 200, driving the impeller 200 to rotate around the axis 11.

[0045] like Figures 3-5 As shown, the interior of the housing 100 forms an impeller cavity 131 and an annular cavity 133 that are axially adjacent. The annular cavity 133 is arranged around the motor 300 and can be defined by the inner wall surface of the housing 100 or by both the inner wall surface of the housing 100 and the motor housing.

[0046] Impeller cavity 131 is used to assemble impeller 200. There is a certain space between the outlet of impeller 200 and annular cavity 133. An annular throat duct 105 is provided in this space. The position of throat duct 105 is lower than the outlet of impeller 200. The airflow reflected by the inner wall of casing 100 first passes through throat duct 105 and then is conveyed downward.

[0047] In some embodiments, the throat duct 105 is defined as a third gap 104 between the lower cover plate 210 and the inner wall surface of the housing 100. It is evident that the throat duct 105 can be formed by providing a partition inside the housing 100. It should be noted that the height of the throat duct 105 is comparable to the height of the output shaft, which is lower than the outlet of the impeller 200 but higher than the annular cavity 133.

[0048] When the fan is working, the airflow enters through the air inlet 101, flows through the impeller 200, the throat duct 105 and the annular cavity 133 in sequence, and then exits through the air outlet 102. The highest point of the annular cavity 133 should be higher than the air outlet 102, but partial overlap between the annular cavity 133 and the air outlet 102 in the axial direction is allowed.

[0049] As can be seen from the above working process, the airflow discharged from the impeller 200 outlet first impacts the inner wall of the casing 100, which is the main cause of turbulent noise in the fan. Tests have shown that adjusting the minimum flow area of ​​the throat duct 105 can significantly reduce turbulent noise. A larger flow area can achieve a larger flow rate, but will bring greater turbulent noise, while an excessively small flow area will affect the fan's flow rate.

[0050] For ease of description, this application defines the effective flow area at the impeller outlet as S1, and the minimum flow area at the throat duct as S2. The effective flow area S1 at the centrifugal impeller outlet is an inherent parameter of the impeller and can be calculated using the following formula:

[0051] S1=(π×d2×b2-z×t2×b2 / sinβ 2b )×σ

[0052] Where d2 represents the impeller outlet diameter, b2 represents the axial height of the blade outlet, z represents the number of blades, t2 represents the normal thickness of the blade at the outlet edge, and β 2b Let σ represent the blade outlet structure angle, and let σ represent the blockage coefficient, which is generally very close to 1. For ease of calculation, let σ = 1.

[0053] The minimum flow area S2 of the throat duct 105 refers to the minimum cross-sectional area of ​​the throat duct 105. In this embodiment, it refers to the minimum cross-sectional area of ​​the third gap 104 between the lower cover plate 210 and the inner wall of the housing 100. More specifically, it refers to the gap area between the upper surface 211 of the lower cover plate 210 and the inner wall of the housing.

[0054] like Figure 5 In this embodiment, the blade 220 is substantially perpendicular to the lower cover plate 210, and the outer edge of the blade 220 is substantially flush with the edge of the lower cover plate 210. The lower cover plate 210 is a disc-shaped structure with neat edges. Therefore, the effective flow area S1 of the impeller outlet can be simplified to the following formula:

[0055] S1=2πr1×HN×D×H

[0056] Where r1 represents the radius of the lower cover plate, H represents the axial height of the blade exit position, N represents the number of blades, and D represents the thickness at the blade exit.

[0057] like Figure 6 ,as well as Figure 9 As shown in the shaded area of ​​the particles, the flow area of ​​the throat duct 105 can be simplified to the following formula:

[0058] S2=πr2 2 -πr12

[0059] Among them, r1 represents the radius of the lower cover plate, and r2 represents the distance from the center of the lower cover plate (i.e., the axis) to the inner wall surface of the casing.

[0060] In the case where the effective flow area S1 at the impeller outlet of this application remains unchanged, as Figure 12 shown, by changing the thickness of the casing 100 at the lower cover plate 210, the minimum flow area S2 of the throat air duct 105 is adjusted. Among them, the inner wall surface of the casing 100 locally has a radially protruding convex part 174, and by changing the convex height and convex shape of the convex part 174, the thickness of the casing 100 at the lower cover plate 210 is changed.

[0061] The noise and flow rate of the fan are tested, and the specific results are shown in the following table:

[0062] <![CDATA[S2 / mm 2 (Approximate value) <![CDATA[S1 / mm 2 (Approximate value) Noise value / dBA Traffic / lpm Sample 1 640 360 46 424 Sample 2 540 360 44 422 Sample 3 430 360 43.2 416 Sample 4 360 360 42.6 412 Sample 5 290 360 41.5 405 Sample 6 220 360 41.2 402 Sample 7 180 360 40.9 380

[0063] It can be found by observing the above table that when S1 and S2 satisfy the relationship: 0.6S1 < S2 < 1.5S1, the fan noise is significantly reduced, but the flow rate does not decrease significantly. Further, S1 and S2 satisfy the relationship: 0.6S1 < S2 < S1. Further still, S1 and S2 satisfy the relationship: 0.6S1 < S2 < 0.8S1.

[0064] In order to further improve the noise reduction effect, in some embodiments, the annular cavity 133 includes opposite inner ring walls 1331 and outer ring walls 1332. The inner ring wall 1331 is provided with a plurality of first partitions 141, and there is a first gap 151 between the first partitions 141 and the outer ring wall 1332; and / or, the outer ring wall 1332 is provided with a plurality of second partitions 142, and a second gap 152 is provided between the second partitions 142 and the inner ring wall 1331. The air flow passes through the first gap 151 and / or the second gap 152 after passing through the third gap 104. The arrangement of the partitions includes but is not limited to the following several schemes in the table, and the corresponding test noise and flow rate data are attached:

[0065] plan Partition Layout Scheme Noise / dBA Traffic / Lpm 1 2 first partitions + 1 second partition 41.2 402 2 Without partitions 47 435 3 1 first partition 45.2 428 4 1 second partition 44.8 425 5 1 first partition + 1 second partition 43.3 421 6 1 first partition + 2 second partitions 41.4 394 7 2 first partitions + 2 second partitions 41.1 387

[0066] In the above table schemes, the partitions are arranged almost equidistantly in the axial direction, and the gap areas between each partition and the inner wall of the casing are basically the same. The number of partitions is changed by adding partitions one by one from top to bottom to meet the test requirements. In the above schemes, the first partitions and the second partitions are arranged alternately at intervals.

[0067] It can be found by observing the above table that compared with Scheme 2, after the partitions are provided, the noise of the fan has decreased significantly. Among them, in each scheme with partitions provided, Scheme 1 has significantly reduced the noise, and at the same time, the flow rate has decreased less, which is the best scheme.

[0068] In some embodiments, the annular cavity 133 is provided with a first partition 141 and a second partition 142, which are arranged alternately at axial intervals to create a baffle section 160 within the annular cavity 133, through which the airflow flows along a baffle path. Taking embodiment 1 as an example... Figure 4 and Figure 6 As shown, from top to bottom along the axial direction, the first partition 141a, the second partition 142 and the first partition 141b are arranged in sequence. Each partition extends continuously around the axis 11 in the circumferential direction, so that all airflows are deflected.

[0069] The outer diameter of the first partition 141a is D1, the inner diameter of the second partition 142 is D2, and the outer diameter of the first partition 141b is D3. D1, D2, and D3 are close to each other and simultaneously satisfy D1 < D2 < D3.

[0070] like Figure 4 , Figures 10-11 As shown, the flow area S3 of the first gap 151 is defined, and it can be calculated using the following formula:

[0071] S3=πr 32 2 -πr 31 2

[0072] Wherein, S3 is as follows Figure 10 As shown by the grain shadow, r 31 The position of the outer edge of the corresponding first partition 141 from the axis; r 32 S1 is the distance between the axis and the outer ring wall 1332, with the axial position of the first partition 141 as the reference. As mentioned above, S1 and S3 must satisfy the relationship: S3 > S1. In this example, S3 is S3 = 1.2S1.

[0073] Define the flow area of ​​the second gap 152 as S4, which can be calculated using the following gap:

[0074] S4=πr 42 2 -πr 41 2

[0075] Wherein, S4 is as follows Figure 11 As shown by the grain shadow, r 42 The position of the inner edge of the corresponding second partition 142 from the axis; r 41 S1 is the distance between the axis and the inner ring wall 1331, with the axial position of the second partition 141 as the reference. As mentioned above, S1 and S4 must satisfy the relationship: S4 > S1. In this example, S4 is set to S4 = 1.2S1.

[0076] The area of ​​the gaps where the other partitions are located is calculated using the formula above, and the flow area of ​​the gaps must be greater than the effective flow area of ​​the impeller outlet.

[0077] In some embodiments, the inner ring wall 1331 and the first partition 141 are circularly transitioned, and the outer ring wall 1332 and the second partition 142 are circularly transitioned, making the airflow smoother.

[0078] In some embodiments, the inner wall of the housing 100 has a guide section 170 whose radial dimension gradually increases from the location of the impeller 200 to the location of the second partition 142. The guide section 170 generally has a tendency to expand outward from top to bottom, such as... Figure 4 As shown, the guide section 170 includes an upper section 171, a middle section 172, and a lower section 173 arranged sequentially along the axial direction. The upper section 171 smoothly transitions to the upper cover of the housing 100, and the bottom end of the lower section 173 smoothly transitions to the second partition 142. The aforementioned protrusion 174 is provided on the guide section 170.

[0079] like Figure 13 As shown, in one embodiment, the housing 100 includes an upper housing 110 and a lower housing 120 stacked axially. The upper housing 110 is provided with an air inlet 101 and an impeller cavity 131 for mounting the impeller 200. The air inlet 101 is located at the center of the upper end face of the upper housing 110, aligned with the center inlet of the impeller. The lower end face of the lower housing 120 is recessed to form a motor mounting cavity 132 for accommodating the motor 300. After the upper housing 110 and the lower housing 120 are fastened together, they enclose an air outlet 102 and an annular cavity 133.

[0080] The upper housing 110 is provided with a second partition 142, and the lower housing 120 is provided with a motor mounting cavity 132 and first partitions 141a and 141b. The upper housing 110 and the lower housing 120 are closed together to form a partition. The first partition 141 is separately connected to the lower housing 120 or integrally formed, and the second partition 142 is separately connected to the upper housing 110 or integrally formed. Each partition is a plate-like structure of uniform thickness.

[0081] The flow path and direction of the airflow are described in further detail below:

[0082] When the impeller 200 is working, the airflow enters the impeller 200 from the air inlet 101 in a roughly axial direction. The airflow is discharged from the radial outlet of the impeller along the flow channel 103. After colliding with the inner wall of the casing 100, it enters the throat air duct 105. Due to the flow control of the throat air duct 105, the turbulence noise can be greatly reduced.

[0083] The airflow through the throat duct 105 then enters the annular cavity 133, which has a baffle section. Due to the obstruction of the baffle, noise can be prevented from propagating outward, further reducing the turbulent noise of the fan. Since the minimum flow area of ​​the baffle section is greater than the effective flow area of ​​the impeller outlet, the fan flow loss is small.

[0084] The airflow through the annular cavity 133 is then discharged from the air outlet 102 from the casing 100.

[0085] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as the combination of these technical features does not contradict each other, it should be considered to be within the scope of this specification. When technical features of different embodiments are embodied in the same drawing, it can be regarded as the drawing also disclosing examples of combinations of the various embodiments involved.

[0086] The above embodiments are merely illustrative of several implementation methods of this application, and their descriptions are quite specific and detailed. However, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these modifications and improvements all fall within the protection scope of this application.

Claims

1. A fan, comprising a casing, an impeller, and a motor, wherein the casing has an air inlet and an air outlet, and an impeller cavity is formed therein; the impeller is assembled in the impeller cavity, configured for axial air intake and radial air exhaust, and is driven by the motor to rotate around an axis; the impeller cavity is provided with an annular throat duct, the position of which is lower than the outlet of the impeller; characterized in that: The effective flow area at the impeller outlet is S1, and the minimum flow area at the throat duct is S2, both satisfying: 0.6S1 <S2<1.5S1。 2. The fan of claim 1, wherein 0.6S1<S2<S1.

3. The fan according to claim 1, characterized in that, 0.6S1 < S2 < 0.8S1.

4. The fan according to claim 1, characterized in that, The interior of the housing forms an annular cavity surrounding the motor, and the impeller cavity and the annular cavity are arranged adjacent to each other in the axial direction.

5. The fan according to claim 4, characterized in that, The annular cavity is defined by the inner wall surface of the housing; or the annular cavity is defined by the inner wall surface of the housing and the motor housing together.

6. The fan according to claim 4, characterized in that, The annular cavity includes an inner annular wall and an outer annular wall arranged coaxially. The inner annular wall is provided with a plurality of first partitions, and each first partition forms a first gap with the outer annular wall; and / or, the outer annular wall is provided with a plurality of second partitions, and each second partition forms a second gap with the inner annular wall.

7. The fan according to claim 6, characterized in that, The flow area of ​​both the first gap and the second gap is greater than the effective flow area S1 of the impeller outlet.

8. The fan according to claim 6, characterized in that, The first partition and the second partition are arranged alternately along the axial direction to form a deflection path within the annular cavity.

9. The fan according to claim 8, characterized in that, The number of first partitions is two, the number of second partitions is one, and the second partition is located between the two first partitions.

10. The fan according to claim 6, characterized in that, The first partition and the second partition are arranged to extend continuously along the circumference.

11. The fan according to claim 1, characterized in that, The impeller includes a lower cover plate and a plurality of blades extending radially. A flow channel is formed between adjacent blades. The gap between the lower cover plate and the inner wall of the housing is defined as the throat air duct, and the minimum flow area of ​​the gap is S2.

12. The fan according to claim 1, characterized in that, The housing includes an upper housing and a lower housing stacked along the axial direction. The upper housing is provided with the air inlet, and the center of the lower housing is provided with a motor mounting cavity for accommodating the motor. The upper housing and the lower housing together form the air outlet.

13. The fan according to claim 1, characterized in that, The air inlet is directly opposite the center inlet of the impeller, and the air outlet is located on the radial outer wall of the annular cavity.

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