Motor impeller and axial flow fan

Abstract

The invention relates to a motor movable impeller and an axial flow fan, the motor movable impeller is applied to the axial flow fan, and the axial flow fan comprises a static impeller, an air inlet cover and the motor movable impeller which are coaxially arranged; the motor movable impeller is arranged in the air inlet cover, the motor movable impeller is a centrifugal impeller, air enters the motor movable impeller in the axial direction and exits the motor movable impeller in the radial direction, the air inlet cover is used for guiding radial airflow of the motor movable impeller to turn into axial airflow, and the static impeller is an axial impeller; the air inlet cover comprises an inner bent wall face, the motor movable impeller comprises a front disc, a rear disc and blades arranged between the front disc and the rear disc, the front disc is close to the inner bent wall face, the rear disc is close to a hub of the static impeller, and a flow channel of the motor movable impeller is communicated with the bent flow channel. The front disc comprises a circular ring part and a first expansion part which are integrally formed, and the first expansion part is arranged on the outer edge of the front disc and expands in the direction away from the rear disc. The flow separation in the flow channel can be improved when the movable impeller has axial installation deviation, and the flow loss is reduced.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the technical field of axial flow fan, in particular to a motor moving impeller and an axial flow fan. BACKGROUND

[0002] The high-speed small motor is an axial flow fan applied to small household appliances, which is generally composed of a moving impeller and one or more static impellers, and the moving impeller is located upstream of the static impeller group. At present, in the actual assembly process of the axial flow fan, the installation of the moving impeller is prone to axial position deviation, which causes the outlet of the flow passage of the moving impeller to be misaligned with the inlet of the subsequent flow passage, thereby generating a backflow area in the flow passage, affecting the aerodynamic performance of the axial flow fan. SUMMARY

[0003] In order to solve at least one of the above technical problems, the present disclosure provides a motor moving impeller and an axial flow fan.

[0004] According to some embodiments of the present disclosure, a motor moving impeller is provided, which is applied to an axial flow fan, the axial flow fan comprising a static impeller, an inlet cover and the motor moving impeller arranged coaxially; the motor moving impeller is arranged in the inlet cover, the motor moving impeller is a centrifugal impeller, the motor moving impeller is axially air-in and radially air-out, the inlet cover is used to guide the radial airflow of the motor moving impeller to turn into axial airflow, the static impeller is installed downstream of the airflow direction of the motor moving impeller, and the static impeller is an axial impeller; the inlet cover comprises an inner curved wall surface, a curved flow passage is formed between the inner curved wall surface and the hub side wall of the static impeller, the motor moving impeller comprises a front disc, a rear disc and blades arranged between the front disc and the rear disc, the front disc is close to the inner curved wall surface, the rear disc is close to the hub of the static impeller, and the flow passage of the motor moving impeller is in communication with the curved flow passage; the front disc comprises an integral annular portion and a first expansion portion, the first expansion portion is arranged at the outer edge of the front disc, and the first expansion portion expands away from the rear disc.

[0005] Based on the above scheme, the inlet cover is provided with an inner curved wall surface, and the edge of the front disc of the moving impeller is expanded outward. When there is an axial installation deviation of the moving impeller, the airflow flows out by adhering to the first expansion portion of the front disc, then impacts and adheres to the inner curved wall surface, and completes the turning along the inner curved wall surface, thereby improving the airflow separation and reducing the flow loss, so as to enhance the aerodynamic performance of the axial flow fan.

[0006] In some possible implementation manners, a profile of the inner curved wall surface on a radial section is a spline curve, the spline curve comprises two circular arc segments connected smoothly, a center of the circular arc segment close to the rear disc is located inside the inlet cover, and a center of the circular arc segment close to the front disc is located outside the inlet cover.

[0007] Based on the above scheme, the front end edge of the inlet shroud is extended outward, and the first outward extension part of the front disc can be aligned with the front end edge of the inlet shroud within a certain axial distance range of the moving blade wheel, thereby further reducing the influence of the axial installation deviation of the moving blade wheel on the aerodynamic performance of the axial flow fan.

[0008] In some possible implementations, the end of the inner wall of the annular portion points to the inner curved wall surface, and the extension surface of the inner wall of the annular portion is tangent to the inner curved wall surface.

[0009] Based on the above scheme, by limiting the guidance of the inner wall of the annular portion, the flow direction of the airflow flowing out of the moving blade wheel through the front disc is consistent with the inlet direction of the curved flow passage, so that the airflow has a certain axial velocity, thereby improving the flow separation situation caused by the loss of turning speed of the airflow in the curved flow passage.

[0010] In some possible implementations, the end of the inner wall of the first expansion part points to the inner curved wall surface, and the intersection line of the inner wall of the first expansion part and the inner curved wall surface is close to the start of the inner curved wall surface.

[0011] Based on the above scheme, the pointing direction of the first expansion part is limited, the airflow flowing out of the front disc can be aligned with the inner curved wall surface of the inlet shroud, and the moving blade wheel has a certain axial installation range, thereby reducing the influence of the axial installation deviation.

[0012] In some possible implementations, the hub of the stationary blade wheel is provided with a circular chamfer close to one side of the motor moving blade wheel, the rear disc includes an integrally formed disc portion and a second expansion part, the second expansion part is arranged at the outer edge of the rear disc, the second expansion part expands away from the front disc, and the end of the second expansion part points to the circular chamfer.

[0013] Based on the above scheme, the rear disc is designed to be outwardly expanded, the airflow flowing out of the moving blade wheel has a certain axial velocity component, when the airflow flows to the circular chamfer of the hub of the stationary blade wheel, the included angle between the airflow velocity direction and the hub wall surface is small, and the airflow wall adhesion ability is strong, thereby inhibiting the flow separation of the airflow and reducing the flow loss of the airflow.

[0014] In some possible implementations, the inner wall of the first expansion part is a straight line or a smooth curve in the radial section.

[0015] Based on the above scheme, the structure characteristics of the first expansion part are limited by the shape of the type line projection in the radial section, and the type line design of the straight line or the smooth curve can ensure the smoothness of the airflow flowing along the first expansion part.

[0016] In some possible implementations, the inner wall of the second expansion part is a straight line or a smooth curve in the radial section.

[0017] Based on the above scheme, the structure of the second expansion part is defined by the radial cross-section profile shape, and the straight line or smooth curve profile design can ensure the smoothness of the airflow adhering to the second expansion part.

[0018] In some possible embodiments, the inner wall of the first expansion part has a circular arc profile on the radial cross-section, and the extension plane of the inner wall forms an obtuse angle with the inner curved wall plane.

[0019] Based on the above scheme, the airflow flowing out of the first expansion part has both the wall pressure and the along-wall velocity when impacting the inner curved wall plane, which can enhance the airflow adhesion capacity and improve the airflow flow separation phenomenon.

[0020] In some possible embodiments, the distance from the starting position of the first expansion part to the motor moving vane outlet along the inner wall profile direction of the circular ring part is c1, the minimum axial distance between the front disc and the rear disc is b1, 0.2*b1≤c1≤0.45*b1, the circular arc radius r1 of the first expansion part satisfies 1.3*c1≤r1≤1.8*c1, and the outer expansion angle kf of the first expansion part satisfies 25°≤kf≤58°.

[0021] Based on the above scheme, by limiting the size parameters of the first expansion part, the aerodynamic performance of the airflow can be ensured, so that the airflow can flow along the wall as much as possible to reduce the flow distance, thereby maintaining the flow velocity and further improving the airflow separation phenomenon.

[0022] In some possible embodiments, the inner wall of the second expansion part has a circular arc profile on the radial cross-section, and the extension plane of the inner wall points to the starting position of the circular chamfer.

[0023] Based on the above scheme, the airflow flowing out of the second expansion part can smoothly transition to the static vane wheel side wall, maintain the stability of the airflow, and reduce the possibility of flow separation.

[0024] In some possible embodiments, the distance from the starting position of the second expansion part to the motor moving vane outlet along the inner wall profile direction of the circular disc part is c2, the minimum axial distance between the front disc and the rear disc is b1, 0.2*b1≤c2≤0.4*b1, and the circular arc radius r2 of the second expansion part satisfies 1.8*c2≤r2≤3*c2.

[0025] Based on the above scheme, by limiting the size parameters of the second expansion part, the aerodynamic performance of the airflow can be ensured, so that the airflow can flow along the wall as much as possible to reduce the flow distance, thereby maintaining the flow velocity and further improving the airflow separation phenomenon.

[0026] In some possible implementation manners, an axial distance between the starting position of the inner curved wall surface and the starting position of the hub of the stator vane is greater than an axial distance between the ending position of the first expansion portion and the ending position of the second expansion portion.

[0027] Based on the above scheme, the flow passage outlet of the rotor vane is smaller than the inlet of the curved flow passage, and the rotor vane has a certain axial movement degree of freedom. When there is an axial installation deviation of the rotor vane, the flow passage of the rotor vane can still be aligned with the curved flow passage, so that the influence of the axial installation deviation is reduced.

[0028] According to another embodiment of the present disclosure, a motor rotor vane is provided.

[0029] It should be understood that the above general description and the following detailed description are only exemplary and explanatory, but not limiting the present disclosure.

[0030] Other features and aspects of the present disclosure will become apparent from the following detailed description of exemplary embodiments with reference to the drawings. BRIEF DESCRIPTION OF DRAWINGS

[0031] In order to more clearly illustrate the technical solutions and advantages of the embodiments of the present disclosure or the prior art, the drawings required for use in the embodiments or prior art description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present disclosure, and for those skilled in the art, other drawings can also be obtained without creative labor on the basis of these drawings.

[0032] Figure 1 A schematic diagram showing the axial installation deviation of the rotor vane of the axial flow fan is shown.

[0033] Figure 2 A radial section view of a motor rotor vane according to an embodiment of the present disclosure is shown.

[0034] Figure 3 A partial enlarged view of the radial section of a motor rotor vane according to an embodiment of the present disclosure is shown.

[0035] Figure 4 A diagram showing the flow effect of the front disc of the rotor vane in the related art is shown.

[0036] Figure 5 A diagram showing the flow effect of the front disc of a motor rotor vane according to an embodiment of the present disclosure is shown.

[0037] Figure 6 A diagram showing the flow effect of the rear disc of the rotor vane in the related art is shown.

[0038] Figure 7A rear disc airflow flow effect diagram of a motor moving vane wheel is shown according to an embodiment of the present disclosure.

[0039] Figure 8 A distribution diagram of a moving vane wheel and a static vane wheel of an axial flow fan in the related art is shown.

[0040] In the drawings:

[0041] 1, inner curved wall surface; 2, front disc; 21, circular ring part; 22, first expansion part; 3, rear disc; 31, disc part; 32, second expansion part; 4, hub; 41, circular chamfer. DETAILED DESCRIPTION

[0042] The technical solutions in the embodiments of the present specification will be described clearly and completely below in combination with the drawings in the embodiments of the present specification. Obviously, the described embodiments are only some of the embodiments of the present specification, rather than all the embodiments. Based on the embodiments in the present specification, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of the present invention.

[0043] It should be noted that the terms "first", "second", and the like in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and do not necessarily indicate a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system, product or server including a series of steps or units does not necessarily limit to those steps or units clearly listed, but can include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0044] Various exemplary embodiments, features and aspects of the present disclosure will be described in detail below with reference to the accompanying drawings. The same reference numbers in the drawings represent functionally identical or similar elements. Although various aspects of the embodiments are shown in the drawings, the drawings are not necessarily drawn to scale unless specifically indicated.

[0045] The word "exemplary" is used herein in the sense of being an example, illustration, or demonstration. Any embodiment described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments.

[0046] The term "and / or", merely describes association relationship of associated objects, which means that there can be three relationships, for example, A and / or B, which can represent three cases of A alone, A and B together, and B alone. In addition, the term "at least one" herein means any one of the plurality or any combination of at least two of the plurality, for example, at least one of A, B and C includes any one or more elements selected from the set consisting of A, B and C.

[0047] In addition, in order to better illustrate the present disclosure, numerous specific details are given in the specific embodiments below. Those skilled in the art should understand that the present disclosure can also be implemented without some specific details. In some examples, methods, means, elements and circuits well known to those skilled in the art are not described in detail, in order to highlight the main idea of the present disclosure.

[0048] It is worth noting that, in the absence of special instructions, the direction in the embodiments of the present disclosure is defined according to the flow direction of the airflow, for example, according to the flow direction of the airflow, the upstream is the front, the downstream is the back; or the upstream is the beginning, the downstream is the end, etc.

[0049] High-speed small motor is a kind of axial flow fan applied in small household appliances (such as vacuum cleaner, floor washing machine, floor sweeping robot, etc.), which is generally composed of a moving impeller and one or more static impellers. The moving impeller is located upstream of the static impeller group. The moving impeller adopts backward centrifugal form, and the static impeller adopts axial form. The airflow enters the moving impeller axially and flows out radially. The airflow out of the moving impeller enters the static impeller again. There is a transition section flow passage between the moving impeller and the static impeller, which converts the radial component of the moving impeller outlet air speed into axial direction. The flow loss increases when the airflow turns, which reduces the overall aerodynamic performance of the fan, Figure 8 The distribution diagram of the moving impeller and the static impeller of the axial flow fan is shown.

[0050] At present, in the production and assembly process of the axial flow fan, the installation of the moving impeller is prone to axial position deviation, which makes the moving impeller flow passage outlet unable to align with the transition section flow passage inlet, as shown in Figure 1 When the volume of the axial flow fan is small, even a slight axial installation deviation can have a great impact on the aerodynamic performance of the axial flow fan. For example, if the moving impeller flow passage outlet width is 5mm and the moving impeller axial installation deviation is 0.5mm, the moving impeller flow passage width is occupied by 10%. Due to the axial installation deviation of the moving impeller, part of the airflow is hindered and cannot flow into the transition section flow passage at the first time. The airflow separates due to uneven flow velocity, generates a backflow area near the side wall of the transition section flow passage, changes the airflow velocity distribution at the inlet of the static impeller, generates a backflow area at the hub side wall of the primary static impeller, expands the backflow area at the hub side wall of the secondary static impeller, and finally leads to the decrease of the aerodynamic performance of the axial flow fan.

[0051] To solve the above-mentioned technical problems, this disclosure provides a motor impeller, which is applied in an axial flow fan. This disclosure adjusts the structure of the motor impeller so that the outlet of the motor impeller is expanded outward. The airflow flowing out of the motor impeller has a stronger wall adhesion force in the transition section flow channel, thereby improving the airflow backflow in the transition section flow channel and the stationary impeller hub 4 position.

[0052] Figure 2 An axial cross-sectional view of an axial flow fan is shown. The axial flow fan includes a stationary impeller, an air inlet shroud, and a motor impeller arranged coaxially. The motor impeller is located inside the air inlet shroud and is a centrifugal impeller. The motor impeller allows air to enter axially and exit radially. The stationary impeller is installed downstream of the motor impeller in the airflow direction and is an axial impeller.

[0053] The intake shroud guides the radial airflow of the motor impeller, causing it to turn into axial airflow. The flow channel formed between the intake shroud and the side wall of the impeller hub 4 is the aforementioned transition section flow channel. The intake shroud includes an inner curved wall 1, which forms a curved flow channel with the side wall of the impeller hub 4. The radial airflow from the motor impeller changes into axial airflow along the curved flow channel and flows into the impeller. The intake shroud also includes a front section for intake air. In the axial cross-section, the profile of the front section near the inner curved wall 1 is a straight line, while the profile of the inner curved wall 1 is a smooth curve that curves inward as a whole.

[0054] The motor impeller includes a front disc 2, a rear disc 3, and blades disposed between the front disc 2 and the rear disc 3. The front disc 2 is close to the aforementioned inner curved wall 1, and the rear disc 3 is close to the hub 4 of the stationary impeller. The blades are evenly distributed circumferentially, and the flow channel of the motor impeller is connected to the aforementioned curved flow channel. Figure 2 As shown, the front disc 2 includes an integrally formed annular portion 21 and a first expansion portion 22. The first expansion portion 22 is disposed on the outer edge of the front disc 2 and expands in a direction away from the rear disc 3. Based on the above structure, in the radial airflow of the motor impeller, part of the airflow flows out along the inner wall of the front disc 2, then impacts the inner curved wall surface 1 of the air intake shroud, and continues to flow along the inner curved wall surface 1 until the airflow direction turns axial. It should be understood that the inner wall of the first expansion portion 22 should be smooth and continuous, and the velocity loss is low when the airflow flows along the first expansion portion 22. Therefore, the profile projection of the inner wall of the first expansion portion 22 on the radial section is a straight line or a smooth curve. That is to say, the profile projection of the inner wall of the first expansion portion 22 on the radial section can be a straight line segment, a single circular arc, or a spline curve.

[0055] In this embodiment of the disclosure, please refer to Figure 4 and Figure 5The purpose of the outward expansion design of the front disc 2 of the motor impeller is to enable the airflow adhering to the inner wall of the front disc 2 to have both the wall-pressing speed and the wall-following speed when impacting the inner curved wall surface 1, so that the airflow has strong wall-attaching ability and the speed loss is small, thereby inhibiting the flow separation of the airflow. Since the inlet shroud is provided with the inner curved wall surface 1, when there is a certain axial installation deviation of the motor impeller, the first outward expansion part of the front disc 2 sends the airflow to the inner curved wall surface 1 of the inlet shroud, and the airflow climbs along the inner curved wall surface 1, which can improve the airflow accumulation degree and further reduce and eliminate the backflow area near the side wall surface of the transition section flow passage.

[0056] In the embodiments of the present disclosure, the connection between the front section of the inlet shroud and the inner curved wall surface 1 should be relatively gentle, otherwise the overall inner curved wall surface 1 is relatively steep, which makes it difficult for the airflow to climb along the wall, and the airflow speed loss is large, which is easy to cause flow separation. Please refer to Figure 2 and Figure 3 The profile projection of the inner curved wall surface 1 on the radial section is a spline curve, which includes two circular arc segments connected smoothly, the circular arc segment close to the rear disc 3 is an inner curved circular arc, the center of which is located inside the inlet shroud, and the circular arc segment close to the front disc 2 is an outer curved circular arc, the center of which is located outside the inlet shroud, and the two ends of the outer curved circular arc are connected to the inner curved circular arc and the straight line respectively.

[0057] Based on the structure of the inner curved wall surface 1, the structure of the first expansion part 22 of the front disc 2 needs to be adjusted correspondingly, specifically, the termination of the inner wall of the first expansion part 22 points to the inner curved wall surface 1, and the intersection line between the extension surface of the inner wall of the first expansion part 22 and the inner curved wall surface 1 is close to the starting point of the inner curved wall surface 1. Please refer to Figure 3 On the radial section view, the above structure can be expressed as: the inner wall extension line of the first expansion part 22 intersects with the profile line of the inner curved wall surface 1, and the intersection point is located after the starting point of the profile line of the inner curved wall surface 1, that is, Figure 3 the midpoint T, and the starting point of the profile line of the inner curved wall surface 1 is Figure 3 the midpoint L. It should be understood that the point T moves according to the actual installation position of the motor impeller, and the moving range of the point T is after the point L, when the point T just coincides with the point L, the airflow adhering to the inner wall of the first expansion part 22 can just impact the starting point of the inner curved wall surface 1. When the motor impeller is in the ideal installation position, there is a certain axial distance between the point T and the point L, which is the preset installation error range of the motor impeller, when the axial installation deviation of the motor impeller is less than or equal to the axial distance, the axial installation deviation of the motor impeller will not affect the aerodynamic performance of the axial flow fan.

[0058] According to the above-mentioned embodiments, one reason affecting the aerodynamic performance of the axial flow fan is that the radial outflow of the motor-driven impeller loses too much speed in the process of turning into axial outflow, resulting in flow separation and vortex backflow area. In order to reduce the speed loss of the airflow, the structure of the front disc 2 is adjusted in the embodiments of the present disclosure, so that the outflow of the motor-driven impeller has an axial velocity component. Specifically, the end of the inner wall of the circular ring part 21 points to the inner curved wall surface 1, and the inner wall of the circular ring part 21 is tangent to the inner curved wall surface 1. In the radial cross-sectional view, the extension line of the profile of the circular ring part 21 is tangent to the profile of the inner curved wall surface 1. Based on the above structure, the airflow flowing out of the motor-driven impeller flow passage can smoothly flow into the curved flow passage, the friction energy consumption of the airflow is reduced, thereby reducing the speed loss and improving the aerodynamic performance of the fan.

[0059] In the axial flow fan, since the motor-driven impeller is a centrifugal impeller, the airflow velocity at the outlet of the motor-driven impeller is large due to the influence of the axial velocity inertia of the inlet airflow of the centrifugal impeller. Please refer to Figure 6 , when the airflow flows out along the inner wall of the rear disc 3, it first continues to flow radially, and then slowly turns into axial direction, resulting in low airflow velocity at the side wall of the static impeller hub 4, uneven overall airflow velocity distribution, and gradually forming a low-speed vortex, i.e. a backflow area, at the side wall of the static impeller hub 4. When there is an axial installation deviation of the motor-driven impeller, the rear disc 3 is away from the static impeller hub 4, which will further enlarge the above-mentioned backflow area and reduce the aerodynamic performance of the axial flow fan.

[0060] In order to solve the above-mentioned problems, please refer to Figure 2 , Figure 3 and Figure 7 , the hub 4 of the static impeller is provided with a circular chamfer 41 on the side close to the motor-driven impeller, the rear disc 3 includes an integrally formed disc part 31 and a second expansion part 32, the second expansion part 32 is arranged at the outer edge of the rear disc 3, the second expansion part 32 expands in the direction away from the front disc 2, and the end of the second expansion part 32 points to the circular chamfer 41. Based on the above structure, the airflow flowing out along the inner wall of the rear disc 3 has a certain axial velocity component, the speed loss in the process of turning into axial direction is small, the probability of airflow flow separation is reduced, and thus the aerodynamic performance of the axial flow fan is improved. It should be understood that the inner wall of the second expansion part 32 should be smooth and continuous, the speed loss of the airflow flowing along the second expansion part 32 is low, therefore, the profile of the inner wall of the second expansion part 32 in the radial cross-sectional view is a straight line or a smooth curve, that is, the profile of the inner wall of the second expansion part 32 in the radial cross-sectional view can be a straight line segment, a single circular arc or a spline curve.

[0061] The above-mentioned embodiments have clearly introduced how to adjust the structure of each part of the motor-driven impeller to improve the aerodynamic performance of the axial flow fan. The features of the above-mentioned embodiments can be freely combined to form new schemes without conflict.

[0062] In a specific embodiment, referring to Figure 2 and Figure 3 , the front disc 2 and the rear disc 3 of the motor impeller are designed to be outwardly expanded, and the profile of the inner curved wall 1 on the radial section is a spline curve, which includes two circular arc segments connected smoothly, the circular arc segment close to the rear disc 3 is an inwardly curved circular arc, and the center of the circular arc is located inside the inlet shroud, and the circular arc segment close to the front disc 2 is an outwardly curved circular arc, and the center of the circular arc is located outside the inlet shroud.

[0063] As shown in Figure 3 , the profile of the inner wall of the first expansion part 22 on the radial section is a circular arc, the extension of the inner wall of the first expansion part 22 forms an obtuse angle with the inner curved wall 1, the distance from the starting point (point S in the figure) of the first expansion part 22 to the outlet of the motor impeller along the direction of the profile of the inner wall of the circular ring part 21 is c1, and the axial distance between the starting point of the first expansion part 22 and the starting point of the second expansion part 32 is b1, that is, the minimum axial distance between the front disc 2 and the rear disc 3, and 0.2*b1≤c1≤0.45*b1. In the above parameter setting, the length of c1 affects the flow distance of the airflow adhering to the first expansion part 22, and the length of b1 affects the flow rate of the motor impeller and the flow rate of the airflow flowing out of the motor impeller. In order to ensure the flow guiding effect of the first expansion part 22, the specific parameters of c1 are determined based on the specific parameters of b1. If c1 is too large, the flow distance of the airflow is long, and the airflow will still stall and separate from the first expansion part 22 in the flow distance. On the contrary, if c1 is too small, the flow distance of the airflow is short, and the flow guiding effect of the first expansion part 22 is poor, and the airflow cannot flow to the specified position of the inner curved wall 1 accurately. In some preferred embodiments, the parameter setting relationship of c1 and b1 satisfies: 0.25*b1≤c1≤0.3*b1.

[0064] The radius of the circular arc of the first expansion part 22 is r1, and the parameter setting relationship of r1 satisfies: 1.3*c1≤r1≤1.8*c1. The length of r1 determines the outward expansion degree of the first expansion part 22. The smaller r1 is, the greater the outward expansion degree is, and the greater r1 is, the smaller the outward expansion degree is. In order to ensure the flow guiding effect of the first expansion part 22, the specific parameters of r1 need to be set based on the specific parameters of c1. In some preferred embodiments, the parameter setting relationship of r1 satisfies: 0.25*b1≤c1≤0.3*b1.

[0065] In addition, the outward expansion angle kf of the first expansion part 22 satisfies: 25°≤kf≤58°. The outward expansion angle kf of the first expansion part 22 is another factor that determines the outward expansion degree of the first expansion part 22, and the outward expansion angle kf has a corresponding relationship with r1. In some preferred embodiments, the parameter setting relationship of kf satisfies: 35°≤kf≤45°.

[0066] Based on the above parameter control, when the axial relative position of the motor impeller changes within a certain range, the airflow from the front disc 2 outlet to the inlet of the curved flow passage can have a velocity component that rushes to the outer arc side wall surface of the transition section flow passage due to the flow passage expansion, i.e. a pressure wall velocity component. This part of the gas kinetic energy can make the airflow have a stronger wall sticking tendency, inhibit the flow separation of the curved flow passage, and reduce the flow loss.

[0067] As shown in Figure 3 , the inner wall of the second expansion part 32 projects a circular arc on the radial section, and the extension of the inner wall of the second expansion part 32 points to the starting point of the circular chamfer 41. The distance c2 from the starting point of the second expansion part 32 to the motor impeller outlet along the direction of the inner wall profile of the disc part 31 satisfies: 0.2*b1≤c2≤0.4*b1. In the above parameter setting, the length of c2 affects the flow distance of the airflow sticking to the second expansion part 32, and the length of b1 affects the flow rate of the motor impeller and the flow rate of the airflow out of the motor impeller. In order to ensure the flow guiding effect of the second expansion part 32, the specific parameters of c2 are determined based on the specific parameters of b1. If c2 is too large, the flow distance of the airflow is long, and the airflow will still stall and separate from the second expansion part 32 in the flow distance. On the contrary, if c2 is too small, the flow distance of the airflow is short, the flow guiding effect of the second expansion part 32 is poor, and the airflow cannot accurately flow to the circular chamfer 41 of the hub 4 of the static impeller. In some preferred embodiments, the parameter setting relationship between c2 and b1 satisfies: c2=0.25*b1.

[0068] The radius of the circular arc of the second expansion part 32 is r2, and the parameter setting relationship of r2 satisfies: 1.8*c2≤r2≤3*c2. The length of r2 determines the degree of expansion of the second expansion part 32. The smaller r2 is, the greater the degree of expansion is, and the greater r2 is, the smaller the degree of expansion is. In order to ensure the flow guiding effect of the second expansion part 32, the specific parameters of r2 need to be set based on the specific parameters of c2. In some preferred embodiments, the parameter setting relationship of r2 satisfies: 2*c2≤r2≤2.5*c2.

[0069] Based on the above parameter control, the airflow at the outlet of the rear disc 3 will have a certain axial velocity component due to the expansion structure, rather than purely radially flowing out of the motor impeller. Therefore, when the airflow flows to the side wall of the curved flow passage hub 4, the angle between the airflow velocity direction and the horizontal wall surface of the hub 4 is small, and the airflow has a stronger wall sticking ability. Therefore, the flow separation of the airflow on the side wall of the curved flow passage hub 4 and the rear side wall of the hub 4 is inhibited, and the flow loss is also reduced.

[0070] As shown in Figure 3 , in this embodiment, the axial distance (b) between the starting point of the inner curved wall surface 1 and the starting point of the hub 4 of the static impeller is greater than the axial distance (c) between the termination point of the first expansion part 22 and the termination point of the second expansion part 32. Figure 3 In some preferred embodiments, the axial distance (b) between the starting point of the inner curved wall surface 1 and the starting point of the hub 4 of the static impeller satisfies: 0.2*b1≤b≤0.4*b1.Figure 3 Figure 3 In a further embodiment of b2), 1.05*b2≤b≤1.3*b2, in some preferred embodiments 1.12*b2≤b≤1.17*b2; the axial distance b1 between the start of the first expansion 22 and the start of the second expansion 32 satisfies 0.8*b2≤b1≤0.96*b2, in some preferred embodiments 0.86*b2≤b1≤0.92*b2.

[0071] The present embodiment can greatly reduce the technical problem of performance of the axial flow fan greatly reduced caused by the axial installation deviation by respectively outwardly expanding the front disc 2 and the rear disc 3 of the motor-driven impeller and matching the size parameters, and reduce the sensitivity of the fan assembly process to performance.

[0072] The present disclosure also provides an axial flow fan, comprising the motor-driven impeller according to any one of the above embodiments.

[0073] The above has described the embodiments of the present disclosure, the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes are obvious to those skilled in the art without departing from the scope and spirit of the described embodiments. The selection of the terms used herein is intended to best explain the principles, practical application or technical improvement in the market of the embodiments, or to enable other ordinary skilled in the art to understand the embodiments disclosed herein.

Claims

1. A motor impeller for use in an axial flow fan, characterised in that: The axial flow fan comprises a coaxial static vane wheel, an air inlet cover and the motor moving vane wheel; The motor moving vane wheel is arranged in the air inlet cover, the motor moving vane wheel is a centrifugal vane wheel, the motor moving vane wheel takes in air axially and discharges air radially, the air inlet cover is used for guiding the radial airflow of the motor moving vane wheel to turn into axial airflow, the static vane wheel is installed downstream of the airflow direction of the motor moving vane wheel, and the static vane wheel is an axial vane wheel; The air inlet cover comprises an inner curved wall surface (1), a curved flow channel is formed between the inner curved wall surface (1) and the side wall of the hub (4) of the static vane wheel, the motor moving vane wheel comprises a front disc (2), a rear disc (3) and blades arranged between the front disc (2) and the rear disc (3), the front disc (2) is close to the inner curved wall surface (1), the rear disc (3) is close to the hub (4) of the static vane wheel, and the flow channel of the motor moving vane wheel communicates with the curved flow channel; The front disc (2) comprises an integral annular part (21) and a first expansion part (22), the first expansion part (22) is arranged at the outer edge of the front disc (2), and the first expansion part (22) expands in a direction away from the rear disc (3).

2. The motor impeller of claim 1, wherein: The end of the inner wall of the first expansion part (22) points to the inner curved wall surface (1), and the intersection line between the extension surface of the inner wall of the first expansion part (22) and the inner curved wall surface (1) is close to the starting position of the inner curved wall surface (1).

3. The motor impeller of claim 2, wherein: The profile of the inner wall of the first expansion part (22) on the radial section is a straight line or a smooth curve.

4. The motor impeller of claim 3, wherein: The profile of the inner wall of the first expansion part (22) on the radial section is a circular arc, and the extension surface of the inner wall of the first expansion part (22) forms an obtuse angle with the inner curved wall surface (1).

5. The motor impeller of claim 4, wherein: The distance from the starting position of the first expansion part (22) to the motor moving vane wheel outlet along the direction of the profile of the inner wall of the annular part (21) is c1, the minimum axial distance between the front disc (2) and the rear disc (3) is b1, 0.2*b1≤c1≤0.45*b1, the circular arc radius r1 of the first expansion part (22) satisfies 1.3*c1≤r1≤1.8*c1, and the outer expansion angle kf of the first expansion part (22) satisfies 25°≤kf≤58°.

6. The motor impeller of any one of claims 1-5, wherein: The hub (4) of the static vane wheel is provided with a circular chamfer (41) close to one side of the motor moving vane wheel, the rear disc (3) comprises an integral disc part (31) and a second expansion part (32), the second expansion part (32) is arranged at the outer edge of the rear disc (3), the second expansion part (32) expands in a direction away from the front disc (2), and the end of the second expansion part (32) points to the starting position of the circular chamfer (41).

7. The motor impeller of claim 6, wherein: The profile of the inner wall of the second expansion part (32) on the radial section is a straight line or a smooth curve.

8. The motor impeller of claim 7, wherein: The profile of the inner wall of the second expansion part (32) on the radial section is a circular arc, and the extension surface of the inner wall of the second expansion part (32) points to the starting position of the circular chamfer (41).

9. The motor impeller of claim 8, wherein: The distance from the starting point of the second expansion part (32) to the motor moving impeller outlet along the direction of the inner wall profile of the disc part (31) is c2, the minimum axial distance between the front disc (2) and the rear disc (3) is b1, 0.2*b1≤c2≤0.4*b1, and the radius r2 of the circular arc of the second expansion part (32) satisfies: 1.8*c2≤r2≤3*c2.

10. An axial flow fan characterised in that: A motor moving impeller comprising any one of claims 1-9.

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