Fan and ventilation treatment equipment

Abstract

The fan comprises a volute, an air inlet and an air outlet are formed in the volute, the air outlet extends outwards to form an air outlet channel, the air inlet and the air outlet are communicated with a cavity in the volute, the cavity is provided with a ventilation section, the ventilation area of the ventilation section changes in the circumferential direction, and the ventilation section is communicated with the air outlet channel. The area of the longitudinal section of the ventilation section tends to be increased in the direction that airflow flows to the air outlet, and the longitudinal section passes through the rotating axis of an impeller in the fan. Compared with an existing fan, the fan provided by the invention has the advantage that the noise reduction effect is remarkably improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of fan, in particular to a fan and ventilation therapy equipment. BACKGROUND

[0002] The fan is widely used in industrial production, household appliances, medical treatment and other fields, but the noise problem generated in the running process of the fan has been an important problem that troubles users and equipment manufacturers. Especially in the field of breathing machine, the existence of noise affects the sleep of users, and becomes one of the important performances that users pay close attention to, so the research on noise reduction technology is increasingly valued.

[0003] The existing noise reduction means includes improvement of blade, optimization of airflow channel and use of noise reduction material, etc., wherein the improvement of blade is complex and may cause the decrease of air volume or the increase of energy consumption, the optimization of flow channel mainly through setting guide plate or diffuser, which will cause the problems of complex structure and difficult maintenance, and the use of noise reduction material can absorb part of noise, but may affect heat dissipation or increase volume.

[0004] In view of the problem that the existing noise reduction technology is difficult to balance the noise reduction effect and the performance of fan, and part of the technology will significantly increase the cost or structural complexity, it is difficult to meet the actual application requirements. SUMMARY

[0005] Therefore, the present application provides a fan and ventilation therapy equipment, wherein the cavity in the volute of the fan is designed to have a specific speed reduction structure, so that the flow rate of airflow is reduced during the outflow process, thereby eliminating the turbulent flow to reduce the noise.

[0006] To achieve the above-mentioned purpose, the first aspect of the present application provides a fan, wherein the fan comprises a volute, the volute is provided with an air inlet and an air outlet, the air outlet extends outward to form an air outlet channel, and the air inlet and the air outlet are respectively communicated with a cavity inside the volute.

[0007] The cavity has a ventilation section with a variable ventilation area along the circumference, and the longitudinal cross-sectional area of the ventilation section has a trend of increasing along the direction of airflow to the air outlet, and the longitudinal cross section passes through the rotation axis of the impeller in the fan.

[0008] The fan provided by the embodiments of the present application has a ventilation section in the cavity of the volute, which has an increasing trend in the longitudinal cross-sectional area along the airflow direction to the air outlet. Thus, the flow rate of the airflow is reduced during the process of the fluid entering the cavity from the air inlet and flowing through the ventilation section to the air outlet, which helps to eliminate turbulence and reduce noise. In addition, when the airflow flows to the air outlet through the ventilation section, the flow rate of the airflow is reduced, and the flow rate is proportional to the dynamic pressure, so the dynamic pressure of the airflow is also reduced. Since the airflow dynamic pressure and noise are proportional, the noise is also reduced accordingly.

[0009] In some embodiments, the fan further comprises an inner housing, which is at least partially arranged in the volute, and an outer wall of the inner housing is spaced apart from the inner side wall of the volute to form an airflow channel, the airflow channel comprising the ventilation section; wherein,

[0010] The inner housing comprises an outer shell of the motor assembly; or the inner housing comprises an air guide arranged at least partially outside the outer shell of the motor assembly, the air guide being configured to guide the airflow flowing out of the outlet of the impeller.

[0011] In some embodiments, the air guide is a plate structure to divide the cavity into a first cavity and a second cavity in communication with each other, and the impeller is arranged in the first cavity, wherein the ventilation section comprises at least a portion of the first cavity and / or the second cavity.

[0012] The air guide can comb and guide the airflow to make the airflow laminar into the second cavity. In addition, the cavity is divided by the plate-shaped air guide, which can reduce the mutual influence of the airflow between the two cavities.

[0013] In some embodiments, the volute comprises an expansion section, and the corresponding longitudinal cross-sectional area of the expansion section has an increasing trend along the airflow direction to the air outlet.

[0014] In some embodiments, the inner wall of the expansion section has a normal projection on a set plane, which comprises a spiral line section and / or an involute section, and the set plane is perpendicular to the rotation axis.

[0015] In some embodiments, the spiral line of the spiral line section comprises an Archimedes spiral line and / or a logarithmic spiral line.

[0016] In some embodiments, the expansion section protrudes outwardly away from the central axis of the volute compared to the remaining volute portion of the same circumferential direction in the volute; and / or, along the circumferential direction close to the air outlet, the width of the expansion section in the axial direction gradually increases.

[0017] Due to the outward bulging of the expansion section, the radial distance (corresponding to the bottom of the longitudinal section) between the expansion section and the central axis of the volute gradually increases, and / or the axial width (corresponding to the height of the longitudinal section) of the expansion section gradually increases, the area of the longitudinal section of the corresponding ventilation section of the expansion section gradually increases in the direction close to the air outlet, thereby further reducing the wind speed in the direction close to the air outlet on the basis of the constant air volume in the volute. In addition, since the wind speed is proportional to the dynamic pressure, the wind speed decreases when the dynamic pressure decreases, and since the total pressure is basically unchanged, when the dynamic pressure decreases, the static pressure will increase, that is, when the wind speed decreases, the static pressure will increase to a certain extent, thereby helping to maintain the flow or even increase the flow; and the higher the wind speed, the higher the loss, so after the wind speed is reduced, the loss is also reduced, thereby the design of the expansion section can effectively reduce the wind speed to reduce noise, increase the static pressure to maintain the flow, and reduce the loss.

[0018] In some embodiments, the outer edge of the ventilation section in the orthographic projection on the set plane includes a first section and a second section connected smoothly, wherein the first section is in a circular arc shape, and the second section is in a spiral line shape and / or an involute shape.

[0019] In some embodiments, the orthographic projection of the outer edge of the ventilation section on the set plane does not include a first section in a circular arc shape. Instead, by designing a circular arc section at the starting end of the spiral line section and / or the involute section, the circular arc section can provide a gentle turning and diffusion channel for the incoming airflow in the case that the incoming airflow has a large included angle with the spiral flow direction provided by the ventilation section, thereby allowing the airflow to gradually and smoothly change the flow direction under the guidance of a larger circular arc radius and finally enter the cavity section corresponding to the spiral line section and / or the involute section, further reducing the turbulent noise, especially the broadband noise, and the more uniform and stable airflow also reduces the blade passing frequency noise excited by unstable flow, thereby more kinetic energy is effectively converted into useful static pressure energy, reducing the loss.

[0020] In some embodiments, one side of the orthographic projection of the air outlet channel on the set plane is connected tangentially to the end of the second section away from the first section.

[0021] In some embodiments, the inner shell includes a deformation section, and the cavity forms the ventilation section by the deformation section corresponding to the longitudinal section with a circumferential area variation.

[0022] In some embodiments, the orthographic projection of the outer edge of the inner shell on the set plane includes a spiral line section and / or an involute section, and the set plane is perpendicular to the rotation axis.

[0023] In some embodiments, the axis of the inner shell is eccentrically arranged with the axis of the volute to form the ventilation section with a circumferential area variation.

[0024] In some embodiments, the main body portion of the volute and the inner housing are both cylindrical, and the inner housing is offset away from the air outlet.

[0025] In some embodiments, the air guide is spaced apart from the inner wall of the volute, and the first cavity and the second cavity are in communication through a gap between the air guide and the volute, wherein the gap width is less than the gap width between the impeller outer edge and the volute.

[0026] In some embodiments, the gap is an annular gap.

[0027] In some embodiments, the annular gap ranges from 0.2mm to 3mm, such as 0.2mm, 0.5mm, 1mm, 1.5mm, 2mm, 2.5mm, 3mm, and any value between any two of them. When the annular gap exceeds the defined range, the air guiding effect of the air guide fails, which can cause noise to rise; when the annular gap is too small, it can affect the ventilation at the gap, thereby affecting the efficiency of the fan.

[0028] In some embodiments, the air guide is provided with air holes, and the first cavity and the second cavity are in communication through the air holes.

[0029] In some embodiments, the opening rate of the air guide is 20-60%, such as 20%, 30%, 40%, 50%, 60%, and any value between any two of them.

[0030] In some embodiments, the air hole has a hole diameter of 0.3mm-1mm, such as 0.3mm, 0.5mm, 0.7mm, 1mm, and any value between any two of them.

[0031] In some embodiments, a baffle is arranged in the air outlet, and the baffle blocks a portion of the air outlet. The baffle can effectively prevent air flow from flowing back into the cavity through the air outlet, thereby further reducing noise, such as further reducing noise by about 0.5-1dB.

[0032] The present application also provides a fan, wherein the fan comprises a volute, the volute has an internal cavity, and the volute is provided with an air inlet and an air outlet, the air outlet extends outward to form an air outlet passage, and external air flow enters the cavity through the air inlet and then flows out through the air outlet passage.

[0033] The volute has an expansion section extending away from a central axis thereof, the expansion section causes the cavity to form a ventilation section with a circumferential variation in ventilation area, a longitudinal cross-sectional area of the ventilation section has a tendency to increase in a direction of airflow to the air outlet, the longitudinal cross-section passing through an axis of rotation of an impeller in the fan.

[0034] The present application also provides another fan, wherein the fan comprises a volute and an inner housing;

[0035] The volute is provided with an air inlet and an air outlet, the air inlet and the air outlet are respectively in communication with a cavity inside the volute;

[0036] The inner housing is arranged in the volute, and an outer wall of the inner housing is spaced apart from an inner side wall of the volute to form an airflow passage;

[0037] The inner housing is arranged eccentrically relative to the volute, so that the airflow passage has a ventilation section with a circumferential variation in ventilation area, wherein a longitudinal cross-sectional area of the ventilation section has a tendency to increase in a direction of airflow to the air outlet, the longitudinal cross-section passing through an axis of rotation of an impeller in the fan.

[0038] The present application provides a ventilation therapy device, wherein the ventilation therapy device comprises the fan according to the first aspect of the present application.

[0039] The fan provided by the present application designs the cavity of the volute to have a ventilation section with a circumferential variation in ventilation area, and causes the longitudinal cross-sectional area of the ventilation section to have a tendency to increase in a direction of airflow to the air outlet, so that the velocity of the airflow has a tendency to decrease in the process of flowing to the air outlet, so that the turbulent flow in the frequency band of 500-1.6 kHz is basically eliminated, thereby greatly reducing the noise in this frequency band. Compared with the existing fan, the noise reduction amplitude of the fan provided by the present application is as high as 6-8 dB. BRIEF DESCRIPTION OF DRAWINGS

[0040] Figure 1 A first cross-sectional structure diagram of a fan provided by an embodiment of the present application, wherein the driving part of the motor assembly is omitted;

[0041] Figure 2 A first perspective view of a fan provided by an embodiment of the present application;

[0042] Figure 3 A second cross-sectional structure diagram of a fan provided by an embodiment of the present application; Figure 2 A cross-sectional view along line A-A of the fan, wherein the cross-section passes through the axis of rotation of the impeller;

[0043] Figure 4 A second cross-sectional structure diagram of a fan provided by an embodiment of the present application;

[0044] Figure 5 A cross-sectional view of the volute casing in a wind turbine is provided as an embodiment of this application.

[0045] Figure 6 A third cross-sectional view of a fan provided in an embodiment of this application;

[0046] Figure 7 A front view of a fan provided for an embodiment of this application;

[0047] Figure 8 for Figure 7 A sectional view along line BB, in which the internal structure of the fan, such as the motor assembly, is omitted;

[0048] Figure 9 A second perspective view of a fan provided in an embodiment of this application;

[0049] Figure 10 A third perspective view of a fan provided for an embodiment of this application;

[0050] Figure 11 This is a fourth cross-sectional view of a fan provided in an embodiment of this application, wherein the dashed lines are reference auxiliary lines;

[0051] Figure 12 This is a schematic diagram of a first structure for the cooperation between the volute and the air guide in a fan, provided in an embodiment of this application.

[0052] Figure 13 A fifth cross-sectional view of a fan provided in an embodiment of this application;

[0053] Figure 14 The sixth cross-sectional view of a fan provided in this application embodiment shows that the inner casing is eccentrically disposed relative to the volute.

[0054] Figure 15 This is a seventh cross-sectional view of a fan provided in an embodiment of this application, in which the motor assembly is omitted and the air guide is eccentrically arranged relative to the volute.

[0055] Figure 16 A top view of a fan provided in an embodiment of this application;

[0056] Figure 17 for Figure 16 A cross-sectional view along line CC, in which the drive portion of the motor assembly is omitted;

[0057] Figure 18 This is a schematic diagram of a second structure for the cooperation between the volute and the air guide in a fan, provided in an embodiment of this application.

[0058] Figure 19A CFD streamline diagram of a fan provided by an embodiment of the present application;

[0059] Figure 20 A noise reduction test result diagram of a fan provided by an embodiment of the present application.

[0060] Reference signs

[0061] 1-volute; 1a-side plate; 1b-top plate; 2-cavity; 2a-first cavity; 2b-second cavity; 3-air inlet; 4-air outlet; 4a-outer side; 4b-inner side; 5-air guide; 5a-ventilation groove; 6-gap; 7-air hole; 8-impeller; 8a-impeller outlet; 9-motor assembly; 9a-outer shell; 10-baffle; 11-outlet; 12-recessed area; 13-inner shell; 13a-deformation section; 14-expansion section; 14a-starting end of expansion section; 14b-end of expansion section; 15-bottom cover; 16-ventilation section; 16a-circular arc section; 16b-variable diameter section; 17-curved surface. DETAILED DESCRIPTION

[0062] The present application is further described below in conjunction with embodiments and drawings.

[0063] The terms "first", "second", and the like are used to distinguish similar objects, and are not used to describe a particular order or sequence, and it should be understood that the data thus used can be interchanged under appropriate circumstances, so that the embodiments of the present application can be implemented in an order other than that illustrated or described here, and the objects distinguished by "first", "second", etc. are generally of a kind and are not limited in number, for example, the first object can be one or more.

[0064] In addition, the term "and / or" in the specification and claims is used to describe the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B can represent the three cases of A alone, A and B together, and B alone. The character " / " generally represents an "or" relationship between the associated objects before and after it.

[0065] In the description of the present application, unless otherwise specified, the meaning of "multiple" is two or more.

[0066] In the description of the present application, it should be understood that the terms "upper", "lower", "vertical", "horizontal", "top", "bottom", etc. indicate the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In terms of the present application, the top / upper refers to the air inlet direction, and the opposite side is the bottom / lower.

[0067] In the description of the specification, the description of the terms "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any suitable manner in any one or more embodiments or examples. In addition, the person skilled in the art can combine and combine the different embodiments or examples described in the specification and the features of the different embodiments or examples without contradiction.

[0068] As shown in Figure 1 and Figure 2 , the embodiment of the present application provides a fan, which comprises a volute 1, and the volute 1 is provided with an air inlet 3 and an air outlet 4, and the air inlet 3 and the air outlet 4 are respectively communicated with a cavity 2 inside the volute 1.

[0069] In some embodiments, the air outlet 4 extends outward to form an air outlet channel, and after the external airflow enters the cavity 2 from the air inlet 3, it flows out through the air outlet channel. Exemplarily, as shown in Figure 1 and Figure 2 , the main part of the volute 1 can be generally cylindrical or cylindrical, and the side part of the main part is provided with an outlet, and the outlet can extend outward with a certain length to form an air outlet channel relative to the main part of the volute 1, so the air outlet channel can also be called "tangential air outlet". In some embodiments, the air outlet channel can be a circular pipe with uniform inner diameter along its length direction, or the air outlet channel can be a horn-shaped shape with gradually increasing inner diameter size along its length direction.

[0070] In some embodiments, as shown in Figure 3 , the volute 1 can include a side plate la and a top plate lb, wherein the side plate la is enclosed to form a shell with both ends open, and has a cavity 2 inside, and the top part of the cavity 2 is partially closed by the top plate lb to reserve the air inlet 3 to communicate with the outside. The side plate la is provided with an outlet 11 (as shown in Figure 8 ), and the volute wall at the outlet 11 extends outward along the tangential direction of the volute 1 to form an air outlet channel (tangential air outlet 4). The external airflow enters the cavity 2 from the air inlet 3, and flows out from the outlet 11 and the air outlet channel extended therefrom after flowing through the cavity 2.

[0071] In some embodiments, as shown in Figure 3As shown, the fan can further include an impeller 8 and a motor assembly 9, wherein the impeller 8 can be connected to an output shaft of the motor assembly 9 so that the motor can drive the impeller 8 to rotate. The impeller 8 can be disposed entirely within the cavity 2; a portion or the entirety of the motor assembly 9 can be disposed within the cavity 2, or the motor assembly 9 can be disposed outside the volute 1. In some embodiments, as shown in Figure 1 and Figure 2 As shown, the air inlet 3 can be formed at the top of the volute 1, and the air outlet 4 can be formed at the side of the volute 1. The impeller 8 can be disposed below the air inlet 3 so as to draw air from the air inlet 3 and direct the air flow to the cavity of the volute 1 via the impeller outlet 8a, and then out of the air outlet 4.

[0072] In some embodiments, as shown in Figure 3 When the motor assembly 9 is disposed within the cavity 2, the bottom of the volute 1 can be sealingly connected to the motor assembly 9. In some embodiments, the fan can further include a bottom cover 15 connected to the side of the output shaft of the motor assembly 9 away from the air inlet 3. The bottom cover 15 can be part of the housing of the motor assembly 9, or it can be a plate-like structure disposed separately from the housing of the motor assembly 9.

[0073] In some embodiments, the volute 1 can be a one-piece component, or the volute 1 can be composed of multiple parts made of different materials. For example, the volute body can be made of plastic, and the motor mounting portion of the volute 1 (e.g., the motor mounting seat at the lower part of the volute or the bottom cover 15) can be made of metal.

[0074] As shown in Figure 1 and Figure 3 The cavity 2 has a ventilation section 16 with a circumferentially varying ventilation area, and the longitudinal cross-sectional area of the ventilation section 16 has a tendency to increase in the direction of the air flow towards the air outlet 4, wherein the longitudinal cross-section passes through the rotation axis of the impeller 8 in the fan.

[0075] In some embodiments, the ventilation section 16 can be a section of the cavity of the volute 1 having a certain width in the axial direction. In some embodiments, the ventilation section 16 can be a section of the cavity enclosed by the volute 1, such as a cylindrical cavity section with a circumferentially varying shape. The longitudinal cross-sectional area of the ventilation section 16 can be the longitudinal cross-sectional area of the cavity section enclosed by the volute 1. In some embodiments, the cavity of the volute 1 contains a motor assembly or the like structure (similar structures can be referred to as "inner housing" as described below), and the air flow in the volute 1 is actually between the volute 1 and the inner housing 13, so that the ventilation section 16 can be an annular cavity section. The longitudinal cross-sectional area of the ventilation section 16 can be the cross-sectional area of the gap between the volute 1 and the inner housing 13. In some embodiments, the longitudinal cross-section of the ventilation section 16 passing through the rotation axis of the impeller 8 can also be referred to as the ventilation cross-section.

[0076] In some embodiments, the "increasing trend" can be manifested as a cross-sectional area of a longitudinal section of the air passage 16 near one side (e.g. the right side in Figure 3 ) of the air outlet 4 being larger than a cross-sectional area of the longitudinal section of the air passage 16 far from the other side (e.g. the left side in Figure 3 ) of the air outlet 4.

[0077] In some embodiments, the air passage 16 also has a transverse section with a radial dimension varying in the circumferential direction, which is perpendicular to the rotation axis of the impeller 8. In a specific or any transverse section of the air passage 16, there are at least two positions on the outer peripheral edge (e.g. the inner wall of the volute 1) that satisfy: a first position has a radial distance to the central axis of the volute 1 larger than a radial distance of a second position to the central axis, where the first position is closer to the air outlet 4 in the circumferential direction than the second position; and / or, in the specific or any transverse section of the air passage 16, there are at least two positions on the inner peripheral edge (e.g. the outer wall of the inner housing 13) that satisfy: a third position has a radial distance to the central axis of the volute 1 smaller than a radial distance of a fourth position to the central axis, where the third position is closer to the air outlet 4 in the circumferential direction than the fourth position, so that the radial dimension of the transverse section of the air passage 16 also has an increasing trend in the direction of the air flow to the air outlet 4.

[0078] In some embodiments, the rotation axis of the impeller 8 can be substantially parallel to the axial direction of the volute 1. In some embodiments, the rotation axis of the impeller 8 at least partially coincides with the central axis of the volute 1. The air flow direction can be considered consistent with the rotation direction of the impeller 8. For example, the impeller 8 rotates in the clockwise direction, and the air flow direction in the air passage 16 can be clockwise as shown in Figure 8 The extension direction of the air outlet 4 is adapted to the air flow direction, so that the air flow can flow out along the air outlet smoothly.

[0079] In some embodiments, the air outlet 4 is connected tangentially to the outer side of the main body portion of the volute 1, as shown in Figure 2 , and connected to the inner side of the main body portion of the volute 1 at an angle, as shown in Figure 5 . In the embodiments of the present application, the direction along the air flow direction to the air outlet 4 or the direction along the circumferential direction to the air outlet 4 can be understood as the direction pointing to the outer side (i.e. the tangential side to the main body portion of the volute) of the air outlet 4 in the circumferential direction. For example Figure 8 , the direction from the inner side of the air outlet 1, across the portion of the volute 1 opposite to the air outlet 4, to the outer side of the air outlet 4 in the clockwise direction. In some embodiments, the air outlet 4 can be connected tangentially to the air passage 16, or the air outlet 4 can be arranged above or below the air passage 16.

[0080] In some embodiments, as shown in Figure 1 and Figure 3 , the ventilation section 16 can include a variable-diameter section 16b, which has a gradually increasing longitudinal cross-sectional area along the direction of the air flow to the air outlet 4. In some embodiments, in the circumferential direction, the outer edge of the variable-diameter section 16b gradually increases in radial distance from the rotational axis of the impeller 8 (or the central axis of the volute 1) as it gets closer to the air outlet 4; and / or, in the circumferential direction, the inner edge of the variable-diameter section 16b gradually decreases in radial distance from the rotational axis of the impeller 8 (or the central axis of the volute 1) as it gets closer to the air outlet 4, thereby providing a circumferential area variation of the longitudinal cross-section and / or a radial dimension variation of the transverse cross-section of the ventilation section 16 through the variable-diameter section 16b.

[0081] In some embodiments, as shown in Figure 3 and Figure 6 , for the longitudinal cross-section of the ventilation section 16 that passes through the rotational axis of the impeller 8, in the axial direction, the outer edge of the longitudinal cross-section can have a convex section that expands outward away from the rotational axis (e.g., which can be provided by the expansion section 14 in the following volute 1); and / or, the inner edge of the longitudinal cross-section can have a concave section that expands inward toward the rotational axis (e.g., which can be provided by the deformation section 13a in the following inner housing 13).

[0082] In some embodiments, as shown in Figure 3 , Figure 5 and Figure 6 , in the direction closer to the air outlet 4 (pointing outward from the air outlet 4), the variable-diameter section 16b gradually increases in axial width. Exemplarily, the longitudinal cross-section of the ventilation section 16 that is closer to the air outlet 4 side (e.g., the right side cross-section in Figure 3 ) has a larger axial width of the outward expanding convex section and / or the inward expanding concave section; the longitudinal cross-section of the ventilation section 16 that is farther from the air outlet 4 side (e.g., the left side cross-section in Figure 3 ) has a smaller axial width of the outward expanding convex section and / or the inward expanding concave section, or does not have the outward expanding convex section and concave section. In some embodiments, as shown in Figure 6 , the starting end of the variable-diameter section 16b can be tapered, with the tapered tip pointing toward the inner side of the air outlet 4, and in the direction closer to the air outlet 4 (pointing outward from the air outlet 4), the variable-diameter section 16b gradually increases in axial width.

[0083] In some embodiments, the ending end of the variable-diameter section 16b is directly connected to the air outlet 4. In some embodiments, the starting end and the ending end of the variable-diameter section 16b can be directly connected to the inner side and the outer side of the air outlet 4, respectively, so that the variable-diameter section 16b can extend along the circumference of the volute 1 for one turn; or as shown in Figure 6As shown, the variable diameter section 16b can be spaced apart from the inner side of the outlet 4 at the starting end. In some embodiments, the axial width of the variable diameter section 16b at the ending end can be substantially equal to the axial width of the outlet 4 near the one end of the variable diameter section 16b. In some embodiments, the axial width of the outlet 4 can gradually increase as the outlet 4 extends outwardly away from the body of the volute 1.

[0084] In some embodiments, the axial width of the vent section 16 can be substantially equal to the axial width of the variable diameter section 16b. In some embodiments, the vent section 16 can be located entirely on the side of the impeller 8 away from the inlet 3, such that the vent section 16 (or the variable diameter section 16b) is no higher than the lower surface of the side of the impeller 8 away from the inlet 3.

[0085] In some embodiments, the variable diameter section 16b can extend horizontally in the circumferential direction, or the variable diameter section 16b can extend helically towards the inlet 3 or away from the inlet 3. In some embodiments, the ending end of the variable diameter section 16b near the outlet 4 is closer to the top inlet 3 than the starting end, such that the variable diameter section 16b extends gradually upward in the axial direction. In this way, the outlet 4 connected to the ending end of the variable diameter section 16b can be designed to be located closer to the top inlet 3, thereby reducing the size of the fan and the noise reduction box in which the fan is located in the axial direction. In other embodiments, the ending end of the variable diameter section 16b is farther away from the top inlet 3 than the starting end. In some embodiments, the variable diameter section 16b can extend gradually outward in the circumferential direction away from the rotational axis of the impeller 8 as the variable diameter section 16b extends upward or downward.

[0086] In some embodiments, the starting end of the variable diameter section 16b passes through or is located on the center plane of the outlet 4. In some embodiments, the variable diameter section 16b can be symmetric about a set plane. The plane can serve as the center plane of the variable diameter section 16b. In some embodiments, the center plane is perpendicular to the axial direction of the volute 1 (or perpendicular to the rotational axis of the impeller 8), and the center plane of the variable diameter section 16b can coincide with the center plane of the outlet 4. In other embodiments, the center plane of the variable diameter section 16b can intersect the axial direction of the volute 1, such that the variable diameter section 16b can extend upward or downward.

[0087] In some embodiments, as shown in Figs. 1A and 1B, the variable diameter section 16b can be located entirely on the side of the impeller 8 away from the inlet 3, such that the variable diameter section 16b is no higher than the lower surface of the side of the impeller 8 away from the inlet 3. Figure 5 and Figure 6 In some embodiments, as shown in Figs. 1A and 1B, the variable diameter section 16b can be located entirely on the side of the impeller 8 away from the inlet 3, such that the variable diameter section 16b is no higher than the lower surface of the side of the impeller 8 away from the inlet 3. Figure 3The air passage section 16 can be overall face-symmetric about a plane perpendicular to the rotation axis of the impeller 8 and varies in axial direction, and the cross-sectional dimension of the air passage section 16 perpendicular to the axial direction can be varied. That is, the areas of different cross-sections of the air passage section 16 are different. Exemplarily, along the direction from bottom to top (towards the air inlet 3), the areas of the cross-sections of the air passage section 16 can first increase and then decrease. Such face-symmetric structure can make the cross-sectional area of the air passage section 16 at the plane of symmetry maximum, and gradually decrease in the axial direction from the plane of symmetry towards the air inlet 3 and the direction away from the air inlet 3, respectively. In some embodiments, the plane of symmetry of the air passage section 16 or the variable-diameter section 16b passes through the center plane of the air outlet 4, or coincides with the center plane of the air outlet 4.

[0088] In other embodiments, the air passage section 16 is a face-symmetric structure about a plane perpendicular to the axial direction and varies in axial direction, and the cross-sectional dimension of the air passage section 16 perpendicular to the axial direction can be uniform. In other embodiments, the variable-diameter section 16b can be a non-face-symmetric structure. Exemplarily, the bottom of the variable-diameter section 16b away from the air inlet 3 can extend substantially flush with the bottom of the volute 1, and the top of the variable-diameter section 16b can gradually extend upwards below the impeller 8.

[0089] In some embodiments, the circumferential direction of the air passage section 16 or the entire cavity 2 is smoothly transitioned to avoid sudden changes in airflow direction. In some embodiments, the longitudinal cross-sectional area of the air passage section 16 can always increase in the direction of the airflow flowing out of the air outlet 4. In some embodiments, the orthographic projection of the variable-diameter section 16b on a given plane perpendicular to the axial direction can include a spiral line section and / or an involute section. Exemplarily, the outer edge of the variable-diameter section 16b can include a spiral line section and / or an involute section (e.g. provided by the expansion section 14 on the volute 1 described below); and / or, the inner edge of the variable-diameter section 16b can include a spiral line section and / or an involute section (e.g. provided by the deformation section 13a on the inner shell 13 described below).

[0090] In some embodiments, in the circumferential direction of the volute 1, the air passage section 16 can include at least one circular arc section with a constant longitudinal cross-sectional area (or a constant radial distance between the inner and / or outer edge of the section and the rotation axis of the impeller 8). In some embodiments, the air passage section 16 can be smoothly connected by at least one longitudinal cross-sectional area increasing section and at least one longitudinal cross-sectional area constant section. Among them, the longitudinal cross-sectional area increasing section and the longitudinal cross-sectional area constant section can be alternately and spaced apart, or a plurality of longitudinal cross-sectional area increasing sections are sequentially connected and then connected with a longitudinal cross-sectional area constant section, and so on. In some embodiments, as shown in FIG. 2, the air passage section 16 can include a plurality of circular arc sections with a constant longitudinal cross-sectional area, and the circular arc sections with a constant longitudinal cross-sectional area are alternately and spaced apart. Figure 6 and Figure 8As shown, the ventilation section 16 can include a circular arc section 16a which is smoothly connected with the starting end of the variable-diameter section 16b. The circular arc section 16a can guide the air flow to enter the variable-diameter section 16b gently, thereby reducing the turbulence in the cavity 2 and lowering the turbulence noise. In some embodiments, the circular arc section 16a is connected with the inner side of the air outlet 4 at one end away from the variable-diameter section 16b, and the variable-diameter section 16b is connected with the outer side of the air outlet 4 at the other end.

[0091] In some embodiments, the ventilation section 16 can include at least one diameter-reducing section with a longitudinal cross-sectional area decreasing in the direction of the air flow to the air outlet 4, which can be combined with the circular arc section 16a and the variable-diameter section 16b, and satisfy the trend that the longitudinal cross-sectional area of the ventilation section 16 increases in the direction of the air flow to the air outlet 4.

[0092] As described above, the fan can include an inner housing 13 at least partially disposed in the volute 1, an outer wall of the inner housing 13 being spaced apart from the inner side wall of the volute 1 to form an air flow passage including the ventilation section 16 described above. In some embodiments, the inner housing 13 can be the outer shell 9a of the motor assembly 9; or the inner housing 13 can be the air guide 5 at least partially disposed outside the outer shell 9a of the motor assembly 9, which is used to guide the air flow from the impeller outlet 8a. In some embodiments, the air guide 5 can be disposed entirely outside the outer shell 9a, or only a part of the air guide 5 can extend outside the outer shell 9a.

[0093] In some embodiments, the inner housing 13 (e.g., the outer shell 9a of the motor assembly 9) can be partially disposed in the cavity 2. In other embodiments, the inner housing 13 (e.g., the air guide 5) can be entirely disposed in the cavity 2. The axial width of the ventilation section 16 can be limited by the axial width of the inner housing 13 in the cavity 2. Exemplarily, the ventilation section 16 can be a part of the cavity 2 or the entire cavity 2 below the impeller 8 in the cavity 2. In some embodiments, the outer shell 9a of the motor assembly 9 can be provided in a cylindrical structure; the air guide 5 can be provided in a cylindrical structure or a plate structure.

[0094] In some embodiments, the air guide 5 can be directly sleeved outside the outer shell 9a. In other embodiments, the air guide 5 can be indirectly sleeved outside the outer shell 9a. Exemplarily, as shown in Figure 4 As shown, the bottom of the volute 1 can be curved inwardly and towards the air inlet 3, so that a cavity 2 for air flow is formed between the curved portion and the side wall of the volute 1. The air guide 5 is disposed in the cavity 2 and sleeved on the curved portion. The motor assembly 9 (not shown in the figure) can be disposed on the side of the curved portion away from the air guide 5, so as to be accommodated in the recessed area enclosed by the curved volute 1.

[0095] In some embodiments, asFigure 4 As shown, at least one ventilation slot 5a can be provided on the air guide 5 to guide the airflow flowing out of the impeller outlet 8a. Figure 4 As shown, the venting groove 5a can be an annular groove perpendicular to the rotation axis of the impeller 8. In other embodiments, the venting groove 5a can also be a longitudinal groove (such as the air hole 7 described below), which can be parallel to the rotation axis of the impeller 8 or at a certain angle to the rotation axis.

[0096] In some embodiments, such as Figure 1 and Figure 3 As shown, the air guide 5 can be a plate-like structure to divide the cavity 2 in the volute 1 into a first cavity 2a and a second cavity 2b that are interconnected. In this case, the air guide 5 can also be called a "partition". The impeller 8 can be disposed in the first cavity 2a, thus the air guide 5 can separate the impeller 8 from the second cavity 2b. To facilitate the impeller 8 drawing air from the outside, the first cavity 2a can be directly connected to the air inlet 3, and the second cavity 2b can be directly connected to the air outlet 4. Thus, the first cavity 2a can also be called the air inlet cavity, and correspondingly, the second cavity 2b can be called the air outlet cavity. In some embodiments, such as... Figure 1 As shown, the plate-shaped air guide 5 can be arranged perpendicular to the axial direction of the volute 1 so that the first cavity 2a and the second cavity 2b are arranged vertically.

[0097] In some embodiments, the air guide 5 may be fixedly connected to the motor assembly 9. For example, as shown... Figure 1 and Figure 3 As shown, the air guide 5 can be fixed to the top of the housing 9a in the motor assembly 9, positioned between the impeller 8 and the housing 9a. The outer edge of the air guide 5 extends to the outer side of the housing 9a to guide the airflow exiting from the impeller outlet 8a. In some embodiments, the air guide 5 can be a plate-shaped annular structure, directly fitted onto the outer side of the housing 9a. In some embodiments, the air guide 5 can be fixed to the volute 1 by a fixing structure such as a connecting piece or screws, without being directly fixed to the motor assembly 9.

[0098] With the air guide 5 present, at least one ventilation section 16 can be independently formed in the regions corresponding to the first cavity 2a and / or the second cavity 2b, so that each ventilation section 16 can be part of the first cavity 2a or the second cavity 2b. Alternatively, the ventilation section 16 can extend from the region corresponding to the first cavity 2a to the region corresponding to the second cavity 2b, so that when the air guide 5 is spaced apart from the sidewall of the volute 1, the ventilation section 16 includes not only a part of the first cavity 2a and the second cavity 2b, but also the region corresponding to the air guide 5. That is, the ventilation section 16 can include at least a part of the first cavity 2a and / or the second cavity 2b. In some embodiments, such asFigure 1 and Figure 3 As shown in FIG. 1, the air passage section 16 can be located on the side of the air guide 5 away from the impeller 8, in the second cavity 2b, so that the air flow from the impeller outlet 8a can be combed by the air guide 5 before entering the air passage section 16.

[0099] In some embodiments, the first cavity 2a can have a transverse cross-sectional shape of a central symmetric shape, such as a circular shape, for example, the first cavity 2a can be designed as a cylindrical cavity with the rotation axis of the impeller 8 as the center of symmetry. In other embodiments, the first cavity 2a can also be designed as a non-central symmetric shape, such as an elliptical shape. The impeller 8 accommodated in the first cavity 2a is generally designed as a circular shape. When the impeller 8 rotates, the air flow from the impeller outlet 8a at the edge of the impeller 8 forms a circular air flow, which is guided by the air guide 5 and enters the second cavity 2b below. Compared with the first cavity 2a designed as an elliptical cavity, the cylindrical first cavity 2a can homogenize the air flow entering the second cavity 2b, and has less impact on the symmetry of the incoming air flow, thereby achieving better noise reduction effect.

[0100] In other embodiments, the fan can also not include the air guide 5 described above. The part of the cavity 2 for accommodating the impeller 8 is designed as a cylindrical cavity, and the part below the impeller 8 can be designed as an air passage section 16 with a variable circumferential air passage area.

[0101] Since the shape of the air passage section 16 is defined by the volute 1 and the inner housing 13, the air passage section 16 with a variable circumferential air passage area can be formed by the shape change of either the volute 1 or the inner housing 13, or by the shape change or positional relationship change of the volute 1 and the inner housing 13. The specific embodiments of the air passage section 16 with a variable circumferential air passage area will be described below.

[0102] In some embodiments, the air passage section 16 with a variable circumferential air passage area can be formed by the shape change of the volute 1. As shown in FIG. 2, the volute 1 can be designed as a cylindrical cavity with the rotation axis of the impeller 8 as the center of symmetry. The air passage section 16 with a variable circumferential air passage area can be formed by the shape change of the volute 1. Figure 2 、 Figure 7 and Figure 8 In some embodiments, the volute 1 can include an expansion section 14, and the corresponding longitudinal cross-sectional area of the expansion section 14 has a trend of increasing in the direction of the air flow flowing to the air outlet. In some embodiments, the expansion section 14 can be spaced apart from the inner housing 13, so that the air flow passage between the two forms the air passage section 16; or at least the part of the volute 1 where the expansion section 14 is located does not accommodate the inner housing 13, and the cavity part corresponding to the expansion section 14 forms the air passage section 16.

[0103] In some embodiments, the radial distance between the inner wall of the expansion section 14 and the rotation axis of the impeller 8 (or the central axis of the volute 1) tends to increase along the direction of airflow toward the outlet 4. In some embodiments, the radial distance between the inner wall of the expansion section 14 and the central axis of the volute 1 can monotonically increase with the angle along the direction closer to the outlet 4, so that the longitudinal cross-sectional area corresponding to the expansion section 14 gradually increases along the direction of airflow toward the outlet 4, achieving continuous diffusion. Thus, the cavity portion corresponding to the expansion section 14 can serve as a variable diameter section 16b with a gradually increasing longitudinal cross-sectional area in the ventilation section 16. In some embodiments, the longitudinal cross-sectional area corresponding to the expansion section 14 can be understood as the longitudinal cross-sectional area of ​​the cavity segment in which the expansion section 14 is located, which can be at least one segment of the ventilation section 16 in the axial direction.

[0104] In some embodiments, the inner wall of at least a portion of the first cavity 2a and / or the second cavity 2b in the volute 1 can be designed as a spiral, an involute, or a smooth curve composed of multiple broken lines when projected onto a set plane. It can also be a diffusion curve of other shapes (e.g., an eccentric circle, a sawtooth guide groove, etc.) or any combination of two or more of them, as long as the ventilation cross section as defined in this application increases along the airflow direction. The set plane is perpendicular to the rotation axis of the impeller 8.

[0105] like Figure 7 and 8 As shown, in some embodiments, the orthographic projection of the inner wall of the expansion section 16 onto a set plane includes a helical segment and / or an involute segment, wherein the set plane is perpendicular to the rotation axis of the impeller 8.

[0106] In some embodiments, the helix of the helical segment includes an Archimedean spiral and / or a logarithmic spiral.

[0107] This application does not have special requirements for the specific pitch, base circle radius, rotation angle, etc. of the Archimedean spiral or logarithmic spiral, as long as the ventilation cross section tends to increase along the airflow direction, thereby causing the airflow velocity to decrease in the corresponding part of the cavity. For example, when the spiral is an Archimedean spiral, the pitch can be 1mm-5mm, etc., and its base circle radius can be adaptively matched according to the size of the impeller diameter. In some embodiments, along the direction close to the air outlet 4, the radial distance between the inner wall of the expansion section 14 and the central axis of the volute 1 can expand by 1.5mm-2mm per radian angular displacement (i.e., the pitch is 1.5mm-2mm). The pitch within this range balances the airflow expansion efficiency and noise suppression performance. Too large a pitch can easily lead to airflow separation, while too small a pitch can easily increase wind resistance.

[0108] In some embodiments, the expansion section 14 may extend circumferentially around the volute 1. In this case, the starting end and the ending end of the expansion section 14 may connect to the inner and outer sides of the air outlet 4, respectively. In some embodiments, the expansion section 14 may extend only a short distance circumferentially around the volute 1 and smoothly connect with the remaining volute portion in the same circumferential direction. In some embodiments, the expansion section 14 protrudes outward from the central axis of the volute 1 (or the rotation axis of the impeller 8) compared to the remaining volute portion in the same circumferential direction. In some embodiments, the remaining volute portion connected to the expansion section 14 may be part of a cylindrical volute whose orthographic projection on a given plane is an arc segment.

[0109] In some embodiments, such as Figure 8 As shown, the orthographic projection of the outer edge of the ventilation section 16 onto the set plane may include a smoothly connected first section ( Figure 8 (Middle red line segment) and the second segment ( Figure 8 (The blue line segment in the middle) wherein the first segment is arc-shaped, and the second segment is a spiral segment and / or an involute segment. Thus, the ventilation section 16 may include a smoothly connected arc segment 16a and a variable diameter segment 16b, wherein the outer edge shape of the variable diameter segment 16b may be defined by the inner wall of the expansion section 14 in the volute 1. In some embodiments, the second segment adopts an Archimedean spiral, and the starting point of the Archimedean spiral coincides with the center of the arc-shaped first segment. The rotation axis of the impeller 8 passes through the center of the first segment.

[0110] In some embodiments, such as Figure 8 As shown, the air outlet 4 is tangentially connected to the end of the second section (corresponding to the variable diameter section 16b) away from the first section (corresponding to the arc section 16a) on one side of the orthographic projection of the set plane. In this way, the air outlet 4 is directly connected to the ventilation section 16, which has an increasing circumferential ventilation area, so that the airflow in the cavity 2 is slowed down and reduced in noise by the ventilation section 16 before flowing out from the air outlet 4, thus ensuring the noise reduction effect.

[0111] In some embodiments, such as Figure 2 and Figure 9 As shown, the expansion section 14 can protrude outward away from the central axis of the volute 1, thereby increasing the ventilation area of ​​the cavity corresponding to the expansion section 14. Furthermore, the expansion section 14 can also extend a certain distance in the axial direction to ensure the axial width of the ventilation section 16. In some embodiments, such as... Figure 9 and Figure 10As shown, from the starting end 14a to the ending end 14b of the expansion section, the width of the expansion section 14 gradually increases in the axial direction, wherein the ending end 14b is closer to the air outlet 4 in the circumferential direction than the starting end 14a. That is, along the circumferential direction close to the air outlet 4, the width of the expansion section 14 gradually increases in the axial direction. In some embodiments, the axial width of the expansion section 14 may be less than the overall axial width of the volute 1, so that the expansion section 14 may bulge outward relative to its upper and / or lower volute portion, and the remaining portion of the volute may be a cylindrical volute. In some embodiments, the inner and outer walls of the volute circumferentially containing the expansion section 14 may each extend smoothly as a whole.

[0112] In some embodiments, such as Figure 9 As shown, the starting end 14a of the expansion section 14 can be conical, and the two sides of the cone gradually expand and extend in the circumferential direction near the air outlet 4, thereby continuously increasing the axial width of the expansion section 14. Correspondingly, the axial width of the variable diameter section 16b in the ventilation section 16 can also continuously increase due to the conical expansion. In some embodiments, the two sides of the expansion section 14 can extend symmetrically about a plane perpendicular to the axial direction, so as to allow the ventilation section 16 to be designed as a face-symmetrical structure; or, the expansion section 14 can extend spirally upward from the starting end 14a to the ending end 14b in the direction near the air inlet 3, so that the air outlet 4 can be set closer to the air inlet 3, thereby reducing the axial dimensions of the fan and the noise reduction box in which the fan is located. In other embodiments, the expansion section 14 can extend spirally downward from the starting end 14a to the ending end 14b in the direction away from the air inlet 3.

[0113] like Figure 9 and 10 As shown, in some embodiments, the axial width of the expansion section end 14b is not less than the axial width of the air outlet 4, such as being the same as or slightly larger than the axial width of the air outlet 4. In other embodiments, the axial width of the expansion section end 14b may be less than the axial width of the air outlet 4. In some embodiments, the highest point of the air outlet 4 near the air inlet 3 is not lower than the starting end 14a of the expansion section, and / or the lowest point of the air outlet 4 away from the air inlet 3 is not higher than the starting end 14a of the expansion section. In some embodiments, the starting end 14a of the expansion section 14 may be located on the central plane of the air outlet 14. In other embodiments, the expansion section 14 extends upward along the direction near the air inlet 3 and connects to the air outlet 4, so that the starting end 14a of the expansion section 14 may be located below the central plane of the air outlet 14, thus the starting end 14a is lower than the highest point of the air outlet 4 near the air inlet 3, and may even be lower than the lowest point of the air outlet 4 away from the air inlet 3.

[0114] Based on the above, one side edge (e.g. the outer side edge 4a) of the air outlet 4 in the planar projection is tangentially connected to the volute 1. In some embodiments, as shown in Figure 5 and Figure 8 the other side edge (e.g. the inner side edge 4b) of the air outlet 4, for example the top portion of the air outlet 4 near the air inlet 3, can be connected to the volute 1 through a smooth curved surface 17. In some embodiments, the curved surface 17 in the planar projection of the setting plane is in the shape of a circular arc, the radius of the circular arc is r, the radius of the impeller 8 is D, and the ratio of r / D is in the range of 0.03-0.06. Such arrangement can prevent the air flow in the air outlet 4 from flowing back to the upper portion of the cavity.

[0115] In the above embodiments, the expansion section 14 is provided in the volute 1 to form the air passage section 16 with varying circumferential air passage area through the change of the shape of the volute 1. In this case, the cavity section in the volute 1 corresponding to the expansion section 14 can or can not contain the inner housing 13. In the case of containing the inner housing 13, the shape of the inner housing 13 can adopt a regular cylindrical structure, or the shape of the inner housing 13 can be similarly modified to form the air passage section 16 with varying circumferential air passage area through the change of the shape of the inner housing 13.

[0116] In some embodiments, as shown in Figure 11 the inner housing 13 can include a deformation section 13a corresponding to the air passage section 16, and the longitudinal cross-sectional area of the deformation section 13a varies along the circumference, so that the cavity 2 forms the air passage section 16. In some embodiments, the outer edge shape of the deformation section 13a varies along the circumference, so that the radial distance between the outer edge of the deformation section 13a and the rotation axis of the impeller 8 (or the central axis of the volute 1) varies along the circumference. In some embodiments, the deformation section 13a can be an axial section of the inner housing 13 with a certain height, so that the deformation section 13a extends along the circumference of the inner housing 13 for one turn; or the deformation section 13a can be only a part of the axial section, so that the deformation section 13a only extends along the circumference of the inner housing 13 for a certain distance. The deformation section 13a can be provided on the outer shell 9a of the motor assembly 9 or on the air guide 5. In some embodiments, the deformation section 16 can have a similar structure as the expansion section 14 in the volute 1, such as forming a protrusion or a recess at least partially on the outer surface of the inner housing 13, for example, forming a shape similar to a cam structure. For example, the deformation section 16 can be located on the side of the inner housing 13 close to the air outlet 4, and recessed or contracted towards the rotation axis of the impeller 8 (or the central axis of the volute 1).

[0117] In some embodiments, the radial distance between the outer edge of the inner housing 13 or the deformable section 16 and the rotation axis of the impeller 8 tends to decrease along the direction of airflow towards the outlet 4, for example, it may decrease monotonically or decrease first and then increase. In some embodiments, the orthographic projection of the outer edge of the inner housing 13 onto a set plane perpendicular to the rotation axis of the impeller 8 may include a helical segment and / or an involute segment. Thus, the shape of the outer edge of the inner housing 13 changes circumferentially, so that the airflow channel formed by the outer edge of the inner housing 13 and the inner wall of the volute 1 may include a ventilation section 16 with a circumferentially varying ventilation area. In this structure, there are no particular requirements for the specific form of the helical segment or the involute segment; for example, it may be an Archimedean spiral or a logarithmic spiral. The orthographic projection of the outer edge of the inner shell 13 onto the set plane can be a spiral or involute segment or other shape of diffusion curve, or a combination of two or more shapes. It can also be an arc segment with an unchanged inner diameter on the basis of a spiral segment and / or an involute segment, as long as the ventilation cross section tends to increase along the airflow direction.

[0118] In some embodiments, such as Figure 11 As shown, the deformable section 13a in the inner shell 13 may include a large-diameter side portion ( Figure 11 The left side of the deformed segment 13a) and the small-diameter side ( Figure 11 The right side portion of the deformation section 13a has a large-diameter side and a small-diameter side arranged circumferentially opposite each other along the inner casing 13, wherein the radial distance from the large-diameter side to the rotation axis of the impeller 8 (or the central axis of the volute 1) is greater than the radial distance from the small-diameter side to that axis. The small-diameter side can be considered as the portion of the inner casing 13 or the deformation section 13a that is recessed inward relative to the rotation axis of the impeller 8.

[0119] In some embodiments, the central axis of the inner housing 13 coincides with the central axis of the volute 1, or their central axes may be offset relative to each other. In some embodiments, the large-diameter side and the small-diameter side may be connected substantially smoothly. The orthographic projection of the large-diameter side onto the set plane may be a circular arc segment, and the orthographic projection of the small-diameter side onto the set plane may be an elliptical arc segment. In some embodiments, the major axis of the elliptical arc segment containing the small-diameter side is the same as the diameter of the circular arc segment containing the large-diameter side (the circle containing the circular arc segment can be seen, for example, in [reference needed]). Figure 11 (the dashed part in the middle), thus based on Figure 11 As can be seen, the larger diameter side protrudes away from the central axis of the inner shell 13 relative to the smaller diameter side, or the smaller diameter side (e.g., the portion corresponding to the minor axis) is concave towards the central axis of the inner shell 13 relative to the larger diameter side. In the region near the minor axis of the elliptical arc segment containing the smaller diameter side, there exists an arc segment with a gradually increasing distance around a fixed point (see, for example, [reference needed]). Figure 11The arc segment can be approximately regarded as a helix segment, for example, a logarithmic helix.

[0120] In some embodiments, the large-diameter side of the shape-changing segment 13a can be located on the side away from the air outlet 4, and the small-diameter side can be located on the side close to the air outlet 4. For example, the large-diameter side can be located on the opposite side of the reference plane relative to the air outlet 4, and the small-diameter side can be located on the same side of the reference plane relative to the air outlet 4, the reference plane passing through the central axis of the inner housing 13 (or the rotation axis of the impeller 8), so that in the air passage 16 formed between the shape-changing segment 13a and the inner wall of the volute 1, the longitudinal cross-sectional area on the side away from the air outlet 4 is smaller than the longitudinal cross-sectional area on the side close to the air outlet 4. The shape-changing segment 13a or the cavity portion corresponding to the small-diameter side thereof can serve as a variable-diameter segment 16b in which the longitudinal cross-sectional area gradually increases. In some embodiments, the minor-axis corresponding portion in the small-diameter side is opposite to the outlet 11 on the volute 1, so that in the air passage 16 formed between the shape-changing segment 13a and the inner wall of the volute 1, the longitudinal cross-sectional area on the side away from the air outlet 4 is smaller than the longitudinal cross-sectional area on the side close to the air outlet 4. Figure 11 In the air flow direction shown, the minor-axis corresponding portion in the small-diameter side is located more forward relative to the connecting region between the outer side of the air outlet 4 and the volute 1, so that the air passage cross section between the inner housing 13 and the volute 1 has a tendency to increase in the direction of the air flow to the air outlet 4.

[0121] In some embodiments, the shape-changing segment 16 can be concave inward relative to the remaining portion of the inner housing 13 in the same circumferential direction and toward the rotation axis of the impeller 8. In some embodiments, as shown in Figure 12 In some embodiments, as shown, a concave region 12 can be provided at the outer edge of the inner housing 13 (for example, the air guide 5), and through the design of the shape of the concave region 12, the air flow passage between the concave region 12 and the volute 1 can form an air passage segment 16 in which the circumferential air passage area changes. In the case where the concave region 12 provides the air flow passage, the remaining portion of the inner housing 13 and the inner wall of the volute 1 can be spaced apart or connected to each other. In the case where the inner housing 13 is a plate-shaped air guide 5, the first cavity 2a and the second cavity 2b on both sides of the air guide 5 can be communicated through the concave region 12 (for example, a notch). In some embodiments, the concave region 12 can be provided as a sector-shaped notch, for example.

[0122] In the embodiments of the present application, the shape-changing inner housing 13 can be implemented independently of the shape-changing volute 1, or the two can be combined to jointly define an air passage segment 16 in which the longitudinal cross-sectional area has a tendency to increase in the direction of the air flow to the air outlet 4.

[0123] In some embodiments, in the case where the shape changes of the volute 1 and / or the inner housing 13 described above are retained or not retained, the air passage segment 16 in which the circumferential air passage area changes can be formed through the positional relationship change between the volute 1 and the inner housing 13.

[0124] In some embodiments, as shown inFigure 13 As shown, the axis of the inner housing 13 can be arranged eccentrically to the axis of the volute 1 to form the air passage section 16 with varying circumferential air passage area. Exemplarily, the main body portion of the volute 1 (or the volute portion corresponding to the second cavity 2b) and the inner housing 13 can both be cylindrical, and the inner housing 13 is arranged eccentrically to the inner wall of the volute 1 in a direction away from the air outlet 4, so that the longitudinal cross-sectional area of the air passage section 16 formed between the inner housing 13 and the inner wall of the volute 1 is smaller on the side away from the air outlet 4 than on the side close to the air outlet 4. In some embodiments, the radial distance between the outer edge of the inner housing 13 and the rotation axis of the impeller 8 can have a decreasing trend after the inner housing 13 is arranged eccentrically to the volute 1, for example, can monotonously decrease.

[0125] In some embodiments, as shown in Figure 14 and Figure 15 the side plate la of the volute 1 is enclosed into a cylindrical structure, and the outer shell 9a of the motor assembly 9 also adopts a cylindrical structure and is arranged eccentrically to the central axis of the volute 1. Correspondingly, the air guide 5 arranged outside the outer shell 9a is also arranged eccentrically to the central axis of the volute 1. Thus, the portion from the top of the air guide 5 to the cavity portion corresponding to the outer shell 9a can be formed into the air passage section 16 with varying circumferential air passage area.

[0126] As shown in Figure 3 and Figure 15 in some embodiments, the air guide 5 is spaced apart from the inner wall of the volute 1, and the first cavity 2a and the second cavity 2b are communicated through the gap 6 between the air guide 5 and the volute 1. The airflow flowing out of the impeller outlet 8a contacts the air guide 5 and enters the second cavity 2b through the gap between the air guide 5 and the volute 1. In some embodiments, as shown in Figure 3 the outer side edge of the air guide 5 can be curved into an arc shape in a direction away from the air inlet 3 to enhance the air guiding effect.

[0127] In some embodiments, as shown in Figure 3 the width of the gap 6 can be smaller than the gap width between the outer edge of the impeller 8 (for example, the impeller outlet 8a) and the volute 1. Thus, the outer side edge of the air guide 5 is closer to the inner wall of the volute 1 than the outer edge of the impeller 8, so that the airflow flowing out of the impeller outlet 8a can blow onto the air guide 5 and be guided by the air guide 5. In some embodiments, the distance between the outer edge of the impeller 8 (for example, the impeller outlet 8a) and the inner wall of the first cavity 2a is not more than 5 mm, for example, can be not more than 3 mm to optimize the laminarization effect on the airflow. In some embodiments, the gap 6 between the air guide 5 and the volute 1 is an annular gap, and the range of the annular gap is 0.2 mm-3 mm. In other embodiments, the size of the annular gap in the circumferential direction is not uniform, for example, in the direction along the airflow flowing to the air outlet 4, the annular gap has an increasing trend. For example, referenceFigure 12 and Figure 15 The size of the annular gap increases on the side close to the air outlet 4. In this way, the annular gap can serve as part of the venting section 16.

[0128] In some embodiments, as shown in Figure 16 and Figure 17 , the air guide 5 is provided with air holes 7, and the first cavity 2a and the second cavity 2b are in communication through the air holes 7. In this case, the outer edge of the air guide 5 can be in close contact with the inner wall of the corresponding cavity 2, and the first cavity 2a and the second cavity 2b are in communication only through the air holes 7; or the air guide 5 can be spaced apart from the volute 1. The air guide 5 can be uniformly covered with an array of air holes, or air holes can be provided only in a certain area of the air guide 5.

[0129] In some embodiments, the opening rate of the air guide 5 is in the range of 20-60%. In some embodiments, as shown in Figure 18 , the air holes 7 are provided only at the effective air guiding part of the air guide 5. The opening rate refers to the total area of all air holes 7 accounting for 20-60% of the effective air guiding area of the air guide 5. The effective air guiding part can refer to the part of the air guide 5 corresponding to the gap between the outer shell 9a of the motor assembly 9 and the inner wall of the second cavity 2b.

[0130] In some embodiments, the diameter of the air holes 7 is 0.3mm-1mm. When the airflow from the impeller outlet 8a enters the second cavity 2b through the air holes 7, the air holes 7 can achieve a certain laminar flow effect.

[0131] As shown in Figure 6 and Figure 8 , in some embodiments, a baffle 10 is provided in the outlet 11 of the air outlet, and the baffle 10 blocks part of the air outlet 4 to prevent the airflow from flowing back into the cavity 2 through the air outlet 4. In some embodiments, the baffle 10 is close to the inner side of the air outlet 4 and connected to the inner wall of the volute 1, thereby covering the side port (i.e. the outlet 11) of the air outlet 4 that is in communication with the inner cavity 2.

[0132] In some embodiments, as shown in Figure 8 , the baffle 10 is in the shape of a circular arc, smoothly connected to the part of the volute connected to the inner side of the air outlet 4, and curved towards the central axis of the volute 1. In some embodiments, the center of the normal projection of the baffle 10 coincides with the center of the circular arc section 16a in the venting section 16. In some embodiments, as shown in Figure 6As shown, the baffle 10 can be arranged at the side of the air outlet 4 close to the air inlet 3, so that the baffle 10 can be used to block the air flow in the volute 1 from flowing out directly through the air outlet 4 without being sufficiently de-noised after flowing out from the impeller outlet 8a, so as to reduce the pulse noise of the fan. In some embodiments, the baffle 10 can block not more than one third of the cross-sectional area of the inner diameter of the air outlet 4; and / or, the baffle 10 can block not more than one half of the width of the inner diameter of the air outlet 4; and / or, the baffle 10 can extend downward from the side of the air outlet 4 close to the air inlet 3 to cover the top of the air outlet 4, and the baffle 10 can block not more than one half of the height of the air outlet 4. In some embodiments, the baffle 10 can be installed at the lower part of the outlet 11, and the baffle 10 can block less than the maximum width of the expanded section end 14b in the axial direction, so that the baffle 10 can effectively prevent the air flow in the air outlet 4 from flowing back into the air passage 16.

[0133] In this application, a fan with an air passage 16 having a circumferential air passage area varying along the length direction is simulated, and the CFD streamline diagram thereof is shown as follows. Figure 19 CFD (Computational Fluid Dynamics) is a numerical simulation technology for analyzing the flow characteristics of fluids (such as gases and liquids). Streamline diagram is a common visualization method in CFD post-processing, which is used to show the motion trajectory and velocity distribution of the fluid. The test fan includes a volute 1 having an internal cavity 2, and the volute 1 is provided with an air inlet 3 and an air outlet 4, and the air outlet 4 extends outward to form an air outlet passage. The volute 1 has an expanded section 14 extending away from the central axis thereof, and the expanded section 14 causes the cavity 2 to form an air passage 16 having a circumferential air passage area varying along the length direction, and the longitudinal cross-sectional area of the air passage 16 has a tendency to increase along the direction of the air flow flowing out of the air outlet 4, and the longitudinal cross-section passes through the rotation axis of the impeller 8 in the fan.

[0134] In addition, the cavity 2 of the test fan is provided with a plate-shaped air guide 5, which divides the cavity 2 into first and second cavities 2a and 2b opposite to each other, wherein the first cavity 2a is a circular cavity, and the second cavity 2b corresponds to the expanded section 14 of the volute side wall, and the air guide 5 and the inner wall of the corresponding volute 1 form a gap 6 therebetween, the first and second cavities 2a and 2b are communicated through the gap 6, and the impeller 8 is arranged in the first cavity 2a.

[0135] The above fan, through the circular first cavity 2a, plays a homogenizing role on the entering airflow, and then the airflow enters the second cavity 2b below the air guide 5 through the air gap 6, in the process, the air gap 6 plays a role of laminarization to the airflow passing through it, and after entering the second cavity 2b, along the direction of the airflow flowing to the air outlet 4, the airflow passes through the radially expanded cavity section provided by the expansion section 14, the flow rate of the airflow decreases along the flow direction, eliminating turbulence and reducing dynamic pressure to achieve the purpose of noise reduction. In addition, the airflow between the two parts above and below the air guide 5 is not interfered with each other by the blocking of the air guide 5, effectively avoiding the interference of the second cavity 2b with the impeller, which is beneficial to further improve the noise reduction effect.

[0136] From Figure 19 it can be seen that the flow trajectory of the airflow in the fan presents a specific spiral, surrounding and other forms, wherein the airflow in the first cavity 2a presents a surrounding form, and the airflow in the second cavity 2b presents a spiral form, and the airflow in the cavity is relatively stable in smooth flow state, and there is basically no turbulence. In addition, as shown in Figure 19 , due to the blocking effect of the baffle 10, the pressure of the top area of the air outlet is further reduced, which helps to improve the noise reduction effect.

[0137] The same test method is used to analyze the noise level and air volume efficiency of the fan provided in the embodiment of the application (which can be referred to as a target fan) and a reference fan, wherein the fan provided in the embodiment of the application has a ventilation section with a circumferential ventilation area change. In the test, four parallel test samples are provided, namely target fans 1-4; the reference fan is a traditional circular single air cavity fan. The structure, size and other parameters of the reference fan and the target fan are basically the same. In this test method, the test distance is set to 1m, and the fan with a standard air resistance is set to 1000pa, and the test results are shown in Figure 20 .

[0138] From Figure 20 it can be seen that the noise value of the target fan at all frequency bands except 315Hz is basically lower than that of the reference fan. In the test, 315Hz is the rotational speed base frequency of the target fan, and 250Hz is the rotational speed base frequency of the reference fan, so excluding the rotational speed base frequency, the noise of the target fan at all frequency bands is optimized compared with the reference fan. Further, from Figure 20 it can be seen that the noise of the fan is mainly concentrated in the high frequency turbulent noise (500-1.6kHz), and compared with the reference fan, the fan provided in the embodiment of the application eliminates turbulence through the ventilation section with a circumferential ventilation area change, and reduces the noise in this frequency band by 6-8dB.

[0139] The fan provided by the embodiments of the present application is a small-size fan, usually with a diameter of several centimeters to tens of centimeters, and is usually applied in compact and lightweight devices. The embodiments of the present application also provide a ventilation therapy device, which comprises the above-mentioned fan provided by the embodiments of the present application. In some embodiments, the ventilation therapy device may, for example, be a breathing machine, an oxygen generator, a high-flow oxygen therapy instrument, etc.

[0140] Finally, it should be noted that the above description is merely preferred embodiments of the present application, and those of ordinary skill in the art can make various similar modifications under the inspiration of the present application without departing from the purpose and scope of the present application, and such modifications shall fall within the protection scope of the present application.

Claims

1. A fan, characterized in that, The fan includes a volute, on which an air inlet and an air outlet are provided. The air outlet extends outward to form an air outlet channel. The air inlet and the air outlet are respectively connected to the cavity inside the volute. The cavity has a ventilation section with a varying circumferential ventilation area, wherein the longitudinal cross-sectional area of ​​the ventilation section tends to increase along the direction of airflow toward the air outlet, and the longitudinal cross-section passes through the rotation axis of the impeller in the fan.

2. The fan according to claim 1, characterized in that, The fan further includes an inner housing, which is at least partially disposed within the volute, and the outer wall of the inner housing is spaced apart from the inner wall of the volute to form an airflow channel, the airflow channel including the ventilation section; wherein, The inner housing includes the housing of the motor assembly; or, the inner housing includes an air guide at least partially disposed outside the housing of the motor assembly, the air guide being used to guide the airflow flowing out from the impeller outlet.

3. The fan according to claim 2, characterized in that, The air guide is a plate-shaped structure that divides the cavity into a first cavity and a second cavity that are interconnected. The impeller is disposed in the first cavity. The ventilation section includes at least a portion of the first cavity and / or the second cavity.

4. The fan according to any one of claims 1-3, characterized in that, The volute includes an expansion section, and the longitudinal cross-sectional area corresponding to the expansion section tends to increase along the direction of airflow towards the air outlet.

5. The fan according to claim 4, characterized in that, The orthographic projection of the inner wall of the expansion section onto the set plane includes a helical segment and / or an involute segment, and the set plane is perpendicular to the axis of rotation.

6. The fan according to claim 5, characterized in that, The helical segment includes an Archimedean spiral and / or a logarithmic spiral.

7. The fan according to claim 4, characterized in that, The expanded section protrudes outward from the central axis of the volute relative to the remaining circumferential portions of the volute; and / or, Along the circumferential direction near the air outlet, the width of the expansion section gradually increases in the axial direction.

8. The fan according to claim 5, characterized in that, The outer edge of the ventilation section, when projected onto the set plane, comprises a first segment and a second segment that are smoothly connected, wherein the first segment is arc-shaped and the second segment is a spiral segment and / or an involute segment.

9. The fan according to claim 8, characterized in that, The air outlet channel is tangentially connected to the end of the second segment away from the first segment on one side of the orthographic projection of the set plane.

10. The fan according to any one of claims 2-3, characterized in that, The inner shell includes a deformation section, the longitudinal cross-sectional area of ​​which varies circumferentially, so that the cavity forms the ventilation section.

11. The fan according to claim 10, characterized in that, The orthographic projection of the outer edge of the inner shell onto the set plane includes a helical segment and / or an involute segment, and the set plane is perpendicular to the axis of rotation.

12. The fan according to any one of claims 2-3, characterized in that, The axis of the inner shell is eccentrically positioned relative to the axis of the volute to form the ventilation section with varying circumferential ventilation area.

13. The fan according to claim 12, characterized in that, Both the main body of the volute and the inner shell are cylindrical, with the inner shell offset away from the air outlet.

14. The fan according to any one of claims 2-3, characterized in that, The air guide is spaced apart from the inner wall of the volute, and the first cavity and the second cavity are connected through the gap between the air guide and the volute, wherein the width of the gap is smaller than the width of the gap between the outer edge of the impeller and the volute.

15. The fan according to any one of claims 14, characterized in that, The gap is an annular gap, and the range of the annular gap is 0.2mm-3mm.

16. The fan according to any one of claims 2-3, characterized in that, The air guide is provided with air holes, and the first cavity and the second cavity are connected through the air holes.

17. The fan according to claim 16, characterized in that, The opening ratio of the air guide is 20-60%; and / or the diameter of the air pore is 0.3mm-1mm.

18. The fan according to claim 1, characterized in that, A baffle is provided inside the air outlet, and the baffle blocks part of the air outlet.

19. A fan, characterized in that, The fan includes a volute, which has an internal cavity and an air inlet and an air outlet. The air outlet extends outward to form an air outlet channel. External airflow enters the cavity through the air inlet and then flows out through the air outlet channel. The volute has an expansion section extending away from its central axis, which causes the cavity to form an air passage with a varying circumferential air area. The longitudinal cross-sectional area of ​​the air passage tends to increase along the direction of airflow toward the air outlet, and the longitudinal cross-section passes through the rotation axis of the impeller in the fan.

20. A fan, characterized in that, The fan includes a volute and an inner casing; The volute is provided with an air inlet and an air outlet, which are respectively connected to the cavity inside the volute. The inner shell is disposed in the volute, and the outer wall of the inner shell is spaced apart from the inner wall of the volute to form an airflow channel; The inner shell is eccentrically positioned relative to the volute so that the airflow channel has an air passage with a varying circumferential airflow area, wherein the longitudinal cross-sectional area of ​​the air passage tends to increase along the direction of airflow toward the air outlet, and the longitudinal cross-section passes through the rotation axis of the impeller in the fan.

21. A ventilation therapy device, characterized in that, The ventilation therapy device includes the fan as described in any one of claims 1-20.

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