A cross-flow fan blade and a cross-flow impeller using the same.

Abstract

This invention relates to the field of cross-flow fan technology, and more particularly to a cross-flow fan blade and a cross-flow impeller using the same, comprising a blade body; the blade body is a solid structure, and the outer surface of the blade body includes a pressure surface, a suction surface, and two side surfaces; the two ends of the pressure surface respectively enclose the two ends of the suction surface to form a leading edge and a trailing edge of the blade, both of which have rounded ends; the pressure surface gradually concaves towards the suction surface from one end of the leading edge to one end of the trailing edge, and the size of the leading edge is larger than that of the trailing edge; the cross-sectional thickness of the blade body gradually decreases from one end of the leading edge to one end of the trailing edge; the suction surface has a recessed cut that does not penetrate the pressure surface but penetrates both side surfaces. This invention can solve the problems of severe airflow separation, large inlet air impact, high vortex noise, and low fan efficiency existing in the prior art of cross-flow fan blades.

Description

Technical Field

[0001] This invention relates to the field of cross-flow fan technology, and more particularly to a cross-flow fan blade and a cross-flow impeller using the same. Background Technology

[0002] Cross-flow fans are widely used in household air conditioners, indoor fresh air systems, HVAC equipment, and various air handling units due to their compact structure, uniform airflow, and moderate static pressure. Their core aerodynamic components are the cross-flow blades and impellers. Currently, conventional cross-flow fan blades are generally formed using simple circular arcs or single curves, resulting in insufficient matching between the pressure and suction surfaces. This leads to airflow impact upon entering the blade channel, causing a large inlet angle of attack and significant flow losses. Simultaneously, the suction surface of the blades is prone to boundary layer separation under high flow velocity conditions, forming a large-scale flow separation region; large-scale vortices are easily generated at the blade trailing edge, significantly increasing turbulent noise. Furthermore, most existing blades lack vortex-breaking structures, resulting in large and strong eccentric vortex regions, further reducing aerodynamic efficiency and increasing operating noise. To address common problems such as airflow separation, inlet impact, vortex noise, and low efficiency, a systematic optimization of the blade cross-sectional profile, suction surface structure, notch arrangement, and key dimensional parameters is urgently needed to improve overall fan performance. Summary of the Invention

[0003] One objective of this invention is to propose a cross-flow fan blade to solve the problems of severe airflow separation, large air intake impact, high vortex noise, and low fan efficiency in existing cross-flow fan blades.

[0004] Another objective of this invention is to provide a cross-flow impeller, including a hub and multiple cross-flow fan blades as described above, to achieve stable aerodynamic operation with low noise and high efficiency.

[0005] To achieve this objective, the present invention adopts the following technical solution: A cross-flow fan blade, comprising a blade body; The blade body is a solid structure. The outer surface of the blade body includes a pressure surface, a suction surface, and two side surfaces. The pressure surface and the suction surface are arranged opposite to each other, and the two side surfaces are arranged opposite to each other. The two ends of the pressure surface are respectively enclosed by the two ends of the suction surface to form the leading edge and trailing edge of the blade, and both the leading edge and trailing edge of the blade have a rounded structure. The pressure surface gradually approaches the suction surface from one end of the leading edge of the blade to one end of the trailing edge of the blade. The suction surface is convex, and the size of the leading edge of the blade is larger than the size of the trailing edge of the blade. The cross-sectional thickness of the blade body gradually decreases from one end of the leading edge of the blade to one end of the trailing edge of the blade. The suction surface is recessed and has a cut, which does not penetrate the pressure surface but penetrates both sides.

[0006] Preferably, the cross-sectional profile of the blade body has a pressure profile, a trailing edge profile, a suction profile, and a leading edge profile that are connected in sequence, and the pressure profile, trailing edge profile, suction profile, and leading edge profile are all arranged in an arc. The connection points between the pressure profile, the trailing edge profile, the suction profile, and the leading edge profile are defined as design point A1, design point B1, design point B2, and design point A2, respectively. Two points on the suction line are defined as design point B3 and design point B4, with design point B3 located close to design point B2 and design point B4 located close to design point B1. Design points B3 and B4 divide the suction profile into a first arc segment, a second arc segment, and a third arc segment. The first arc segment is located near the leading edge profile of the blade, and the third arc segment is located near the trailing edge profile of the blade. The two ends of the first arc segment are controlled by design point B2 and design point B3, the two ends of the second arc segment are controlled by design point B3 and design point B4, and the two ends of the third arc segment are controlled by design point B4 and design point B1. The opening of the cut is located in the second arc segment, and the number of cuts is N, where N is a positive integer and N≤6.

[0007] Preferably, an offset arc is formed by equidistant offset of the suction profile towards the pressure profile, and the offset distance between the offset arc and the suction profile is defined as H; The depth of the incision is defined as h; The maximum distance between the suction profile and the pressure profile is defined as Hmax; The minimum distance between the suction profile and the pressure profile is defined as Hmin; Where Hmin≤h≤H≤0.5Hmax.

[0008] Preferably, the chord length of the pressure profile is defined as L, the opening width of the cut is defined as l, and the spacing between adjacent cuts is defined as a; Among them, 3%L≤l≤6%L, 6%L≤a≤13%L.

[0009] Preferably, the cuts are defined to be arranged sequentially from the design point B3 to the design point B4; Define the ratio of the depth h of the nth cut to the opening width l as βn; When N=1, 0.45≤β1≤0.6; When N > 1, βn = h / l = β1 - k × (n - 1) / (N - 1), where N represents the number of cuts, N is a positive integer and N ≤ 6; β1 represents the ratio of the depth to the width of the first cut; and k represents the gradient coefficient, 0 ≤ k ≤ 0.6.

[0010] Preferably, the arc length of the first arc segment is defined as la, the arc length of the second arc segment is defined as lb, and the arc length of the third arc segment is defined as lc; Among them, la=(0.2~0.3)×(la+lb+lc), lb=(0.22~0.35)×(la+lb+lc).

[0011] Preferably, la:lb:lc = 1:1.04:2.11.

[0012] Preferably, the radius of the leading edge profile of the blade is defined as the dimension R1 of the leading edge portion of the blade, and the radius of the trailing edge profile of the blade is defined as the dimension R2 of the trailing edge portion of the blade; Where 1.5≤R1 / R2≤3.

[0013] A cross-flow impeller includes a hub and a plurality of cross-flow blades as described above; Multiple cross-flow fan blades are evenly arranged along the circumference of the hub; The rotation center of the hub is defined as center O, the leading edge of the blade is located close to center O, and the trailing edge of the blade is located away from center O; Define the included angle formed by the center O, design point A1, and design point A2 as the blade installation angle ∠OA1A2; Where 21°≤∠OA1A2≤31°.

[0014] Preferably, an inlet circle tangent to the pressure profile of the adjacent blade is drawn through the design point B2, and the diameter of the inlet circle is defined as the inlet width D1; Draw an exit circle tangent to the third arc segment of the adjacent blade through the design point A1, and define the diameter of the exit circle as the exit width D2; The range of D1 / D2 is 1.1 to 1.35.

[0015] One of the above technical solutions has the following beneficial effects: (1) The blade adopts a solid non-flow structure, which greatly improves the overall strength, rigidity and structural stability. It is not easy to deform, break or produce a whistling sound during operation, and its service life and reliability are significantly improved. (2) The blade has a large leading edge and a small trailing edge. The cross-sectional thickness gradually decreases from the leading edge to the trailing edge. Together with the adjacent blades, they form a composite flow channel with "leading edge contraction and trailing edge expansion". This perfectly matches the real flow field inside the cross-flow fan, ensuring stable airflow and uniform acceleration, as well as smooth airflow and low diffusion loss. This suppresses airflow separation and reduces the intensity of eccentric vortex from the geometric level of the flow channel. (3) The rounded leading edge and trailing edge structure further reduces the inlet angle of attack and the exhaust wake loss, eliminates airflow impact and sharp corner vortex, and reduces aerodynamic noise from the source; (4) The cut does not penetrate the pressure surface, completely preserving the main flow channel, with no airflow leakage, no pressure loss, and no impact on fan efficiency; the cut penetrates both sides, achieving continuous and uniform disturbance along the entire axis, and the vortex breaking and boundary layer control effects are stable and without blind spots. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of a cross-flow fan blade; Figure 2 This is a schematic diagram of a cross-sectional view of a cross-flow fan blade; Figure 3 A schematic diagram of some parameters of a cross-flow fan blade. Figure 1 ; Figure 4 A schematic diagram of some parameters of a cross-flow fan blade. Figure 2 ; Figure 5 This is a top view schematic diagram of a cross-flow impeller using the cross-flow fan blades described above; In the attached diagram: blade body 1, pressure surface 2, suction surface 3, side surface 4, blade leading edge 5, blade trailing edge 6, notch 7, pressure profile 11, blade trailing edge profile 12, suction profile 13, blade leading edge profile 14, offset arc 15, first arc segment 131, second arc segment 132, third arc segment 133, hub 100, cross-flow fan blade 200. Detailed Implementation

[0017] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0018] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "left," "right," "vertical," "level," "top," "bottom," "inner," "outer," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0019] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0020] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0021] A cross-flow fan blade, comprising a blade body 1; The blade body 1 is a solid structure. The outer surface of the blade body 1 includes a pressure surface 2, a suction surface 3, and two side surfaces 4. The pressure surface 2 and the suction surface 3 are arranged opposite to each other, and the two side surfaces 4 are arranged opposite to each other. The two ends of the pressure surface 2 are respectively enclosed by the two ends of the suction surface 3 to form the leading edge 5 and the trailing edge 6 of the blade, and both the leading edge 5 and the trailing edge 6 of the blade have a rounded head structure. The pressure surface 2 gradually approaches the suction surface 3 from one end of the leading edge portion 5 of the blade to one end of the trailing edge portion 6 of the blade. The suction surface 3 is convex, and the size of the leading edge portion 5 of the blade is larger than the size of the trailing edge portion 6 of the blade. The cross-sectional thickness of the blade body 1 gradually decreases from one end of the leading edge 5 to one end of the trailing edge 6. The suction surface 3 is recessed and has a cut 7. The cut 7 does not penetrate the pressure surface 2, but penetrates both sides 4.

[0022] like Figure 1 As shown, the blade body 1 of this technical solution is a solid structure with high overall rigidity, no deformation, and no internal flow channels. The airflow only flows along the pressure surface 2 and suction surface 3 on the outer surface. The outer surface of the blade body 1 is a complete closed curved surface formed by the pressure surface 2, suction surface 3, and two side surfaces 4, which makes the structure stable and easy to injection mold and assemble.

[0023] Because the leading edge 5 of the blade is larger than the trailing edge 6, the cross-sectional thickness of the blade body 1 gradually decreases from the leading edge 5 to the trailing edge 6. Combined with the concave pressure surface 2 and convex suction surface 3 configuration, the blade's profile smoothly narrows from the leading edge 5 to the trailing edge 6. Therefore, when this technical solution is applied to a cross-flow impeller, the flow channel between two adjacent blade bodies 1 gradually expands from the leading edge 5 to the trailing edge 6, thus forming a composite flow channel structure of "leading edge contraction and trailing edge expansion" that is highly adapted to the internal flow field of the cross-flow fan. The flow channel contraction in the leading edge 5 region can pre-compress and stabilize the inlet airflow, reduce the inlet angle of attack, and lower the inlet impact loss, allowing the airflow to smoothly enter the blade passage area. The flow channel expansion in the trailing edge 6 region can conform to the flow law of the eccentric vortex inside the cross-flow fan, effectively guiding the airflow, reducing local diffusion loss, suppressing boundary layer separation on the suction surface 3, and simultaneously weakening the generation intensity of large-scale vortices in the trailing edge 6 region.

[0024] Furthermore, both the leading edge 5 and trailing edge 6 of the blade adopt a rounded structure, which can further smooth the airflow inlet and outlet angles and avoid sharp-angle vortices and airflow impact noise. The incision 7 set in the concave part of the suction surface 3 does not penetrate the pressure surface 2, but penetrates both sides 4. The incision 7 only forms a groove-like disturbance structure on the suction surface 3 of the solid blade body 1. It can not only completely preserve the aerodynamic profile of the pressure surface 2, but also generate airflow short-circuiting and pressure loss. At the same time, it can form a continuous and stable disturbance area in the blade axis, accurately break up the large-scale vortex at the trailing edge, suppress boundary layer separation, and achieve precise aerodynamic control that "only disturbs the boundary layer, does not interfere with the mainstream, and does not damage the solid structure".

[0025] To further explain, the cross-sectional profile of the blade body 1 has a pressure profile 11, a trailing edge profile 12, a suction profile 13, and a leading edge profile 14 that are connected in sequence, and the pressure profile 11, the trailing edge profile 12, the suction profile 13, and the leading edge profile 14 are all arranged in an arc. The connection points between the pressure profile 11, the blade trailing edge profile 12, the suction profile 13, and the blade leading edge profile 14 are defined as design point A1, design point B1, design point B2, and design point A2, respectively. Two points on the suction line 13 are defined as design point B3 and design point B4, with design point B3 located close to design point B2 and design point B4 located close to design point B1. Design points B3 and B4 divide the suction profile 13 into a first arc segment 131, a second arc segment 132, and a third arc segment 133. The first arc segment 131 is located near the leading edge profile 14 of the blade, and the third arc segment 133 is located near the trailing edge profile 12 of the blade. The two ends of the first arc segment 131 are controlled by the design points B2 and B3, the two ends of the second arc segment 132 are controlled by the design points B3 and B4, and the two ends of the third arc segment 133 are controlled by the design points B4 and B1. The opening of the cut 7 is located in the second arc segment 132, and the number of cuts 7 is N, where N is a positive integer and N≤6.

[0026] like Figure 2 As shown, the cross-sectional profile of the blade body 1 is formed by four circular arcs sequentially enclosing the pressure profile 11, the trailing edge profile 12, the suction profile 13, and the leading edge profile 14, creating a continuous, smooth, closed profile. All four segments are circular arcs, ensuring the profile is continuous without sharp angles or abrupt changes, preventing localized eddies, drag, and high-frequency noise from occurring as the airflow moves along the wall. The connection points of the four profile segments are, in sequence, design point A1, design point B1, design point B2, and design point A2, forming a stable and controllable cross-sectional parameter system. The suction profile 13 is divided into three arc segments by design points B3 and B4: the first arc segment 131 is close to the leading edge profile 14 of the blade and is mainly responsible for smoothly guiding the airflow entering the blade passage to the suction surface 3, improving initial adhesion; the second arc segment 132 is located in the middle of the suction surface 3, which is the core area where the boundary layer is most fully developed and vortices are most easily generated, and serves as the area for the placement of the notch 7 to achieve targeted disturbance; the third arc segment 133 is close to the trailing edge profile 12 of the blade and is used to guide the boundary layer airflow to converge smoothly and flow out towards the trailing edge, reducing airflow accumulation and flow separation. The three arc segments have a smooth transition and continuous curvature, forming a uniformly contracting flow channel in conjunction with the pressure profile 11.

[0027] Furthermore, the cuts 7 are concentrated in the second arc segment 132, and the number is controlled to no more than 6. This ensures that the disturbance area completely covers the eddy current sensitive area, while avoiding too many cuts 7 that would reduce the flow channel area and increase resistance, thus achieving the optimal balance between eddy current breaking effect and flow loss.

[0028] To further explain, an offset arc line 15 is formed by equidistant offset of the suction line 13 towards the pressure line 11, and the offset distance between the offset arc line 15 and the suction line 13 is defined as H. The depth of the cut 7 is defined as h; The maximum distance between the suction profile 13 and the pressure profile 11 is defined as Hmax; The minimum distance between the suction profile 13 and the pressure profile 11 is defined as Hmin; Where Hmin≤h≤H≤0.5Hmax.

[0029] like Figure 2-4As shown, the depth of notch 7 employs multi-level constraints to adapt to the solid blade structure and boundary layer disturbance requirements: the minimum depth of notch 7 is not less than the minimum blade thickness, i.e., the minimum distance Hmin between the suction profile 13 and the pressure profile 11, ensuring that notch 7 can act entirely within the boundary layer to achieve stable and effective disturbance breaking; the depth of notch 7 does not exceed the equidistant offset H and is not greater than half of the maximum blade thickness Hmax, preventing notch 7 from intruding into the mainstream region and causing interference, increased drag, and pressure loss. The offset arc line 15 serves as the depth control line, ensuring that the depth of all notches 7 is synchronously adapted to the curved surface shape of the suction surface 3, and that the sidewalls of notches 7 maintain a rounded transition without sharp corners or abrupt changes, thus avoiding the generation of secondary vortices. This constraint ensures that notch 7 acts only within the boundary layer, without interfering with the mainstream airflow, achieving precise, efficient, and low-loss aerodynamic control.

[0030] To further explain, the chord length of the pressure line 11 is defined as L, the opening width of the cut 7 is defined as l, and the spacing between adjacent cuts 7 is defined as a. Among them, 3%L≤l≤6%L, 6%L≤a≤13%L.

[0031] like Figure 3 As shown, the opening width l and spacing a of the notch 7 are proportionally constrained based on the blade chord length L, ensuring that blades of different sizes can achieve standardized and universal design. The opening width l of the notch 7 is controlled between 3% and 6% L to ensure that the notch 7 has sufficient disturbance space to effectively separate the boundary layer and broken vortices, while avoiding the reduction of blade passage strength and airflow short-circuiting caused by excessively wide notches 7. The spacing a of the notches 7 is controlled between 6% and 13% L, so that the notches 7 are evenly distributed along the suction surface 3, and the disturbance areas of adjacent notches 7 are connected to each other without overlapping or interfering with each other, forming a continuous and stable disturbance zone that covers the entire vortex-sensitive area.

[0032] To further explain, the cuts 7 are defined as being arranged sequentially from design point B3 to design point B4; Define the ratio of the depth h of the nth cut 7 to the opening width l as βn; When N=1, 0.45≤β1≤0.6; When N > 1, βn = h / l = β1 - k × (n - 1) / (N - 1), where N represents the number of cuts 7, N is a positive integer and N ≤ 6; β1 represents the ratio of the depth to the width of the first cut; k represents the gradient coefficient, 0 ≤ k ≤ 0.6.

[0033] like Figure 2-3 As shown, the slits 7 are arranged sequentially from design point B3 to B4, corresponding to the airflow direction from the leading edge 5 of the blade to the trailing edge 6. This scheme limits the parameters for single slits and multiple slits separately, ensuring that optimal disturbance effects can be achieved with different numbers of slits. When only a single notch is set (N=1), the depth-to-width ratio of notch 7 is directly limited to 0.45≤β1≤0.6, so that the shape of notch 7 matches the boundary layer thickness, ensuring sufficient eddy current breaking capacity without generating excessive disturbance. When multiple cuts are set (N>1), the linear gradient formula βn=β1-k×(n-1) / (N-1) is used. Taking the ratio of the first cut β1 as the reference, the gradient decreases linearly along the airflow direction. The gradient coefficient k is adjustable in the range of 0~0.6. The change in disturbance intensity can be flexibly adjusted according to the fan air volume, speed and noise requirements.

[0034] This design is highly consistent with the principle that the boundary layer of the suction surface 3 gradually thickens from the leading edge 5 to the trailing edge 6 of the blade, and the vortex intensity gradually increases: the cut ratio is larger and the disturbance is stronger near the leading edge 5, which can suppress airflow separation in advance; the cut ratio is smaller and the disturbance is gentler near the trailing edge 6, avoiding excessive disturbance in the trailing edge region that causes secondary vortices and increased drag, thus achieving precise, gentle and uniform boundary layer control throughout the entire length.

[0035] To further explain, the arc length of the first arc segment 131 is defined as la, the arc length of the second arc segment 132 is defined as lb, and the arc length of the third arc segment 133 is defined as lc; Among them, la=(0.2~0.3)×(la+lb+lc), lb=(0.22~0.35)×(la+lb+lc).

[0036] To elaborate further, la:lb:lc = 1:1.04:2.11.

[0037] like Figure 4 As shown, the lengths of the three arc segments are allocated in a fixed ratio to match the entire process of airflow introduction, development, and shedding on the suction surface 3. The first arc segment 131 accounts for 20%~30% and is responsible for guiding and accelerating the airflow in the leading edge region 5 of the blade; the second arc segment 132 accounts for 22%~35% and serves as the core area of ​​the cut 7, precisely controlling the location and range of disturbances; the third arc segment 133 has the largest proportion and is responsible for guiding and stabilizing the flow in the trailing edge region 6 of the blade. Through fluid simulation and experimental iteration, the optimal ratio of 1:1.04:2.11 was determined, making the curvature distribution of the suction surface 3, the channel contraction ratio, and the boundary layer development length globally optimal.

[0038] To further explain, the radius of the leading edge profile 14 of the blade is defined as the dimension R1 of the leading edge portion 5 of the blade, and the radius of the trailing edge profile 12 of the blade is defined as the dimension R2 of the trailing edge portion 6 of the blade. Where 1.5≤R1 / R2≤3.

[0039] A cross-flow impeller includes a hub 100 and a plurality of cross-flow fan blades 200 as described above; Multiple cross-flow fan blades 200 are evenly arranged along the circumference of the hub 100; The rotation center of the hub 100 is defined as center O, the leading edge 5 of the blade is located close to center O, and the trailing edge 6 of the blade is located away from center O; Define the included angle formed by the center O, design point A1, and design point A2 as the blade installation angle ∠OA1A2; Where 21°≤∠OA1A2≤31°.

[0040] like Figure 5 As shown, multiple cross-flow fan blades 200 are evenly arranged around the hub 100 to form a continuous and symmetrical annular flow channel. The limited blade installation angle ∠OA1A2 ensures that the airflow enters, accelerates and exits stably when the impeller rotates, and the eccentric vortex is confined to a small range and low intensity.

[0041] To further explain, an inlet circle tangent to the pressure profile 11 of the adjacent blade is drawn through the design point B2, and the diameter of the inlet circle is defined as the inlet width D1; Draw an exit circle tangent to the third arc segment 133 of the adjacent blade through the design point A1, and define the diameter of the exit circle as the exit width D2; The range of D1 / D2 is 1.1 to 1.35.

[0042] If the inlet width / outlet width is too large, the diffusion will be too intense, and the airflow will be unable to overcome the reverse pressure gradient, causing it to detach from the blade surface, resulting in backflow and vortices, and causing huge energy loss. Conversely, if the inlet width / outlet width is too small, it will restrict the airflow area, forming "flow blockage," causing the flow rate to fail to meet design requirements, which will also reduce the overall performance of the machine.

[0043] To further verify the performance advantages of this invention, simulation tests were conducted on cross-flow impellers, including those with no notch on the suction surface of the blades and those with notch on the suction surface of the blades of this invention. The test data are shown in the table below. It should be noted that this simulation test is based on a two-dimensional calculation model, and the obtained volumetric flow rate data is derived based on the baseline assumption that the axial length of the impeller is 1m. In practical applications, a linear conversion based on the axial length can be performed. This flow rate value can also be directly used to evaluate the relative performance of the two schemes, thereby quantifying the airflow improvement of the superior scheme.

[0044] As shown in the table below, the volumetric flow rate of the fan increased significantly after the notch was added to the suction surface, with an increase of approximately 4.4%. This indicates that the notch structure effectively improved the aerodynamic performance of the fan and enhanced its air delivery capacity.

[0045]

[0046] The technical principles of the present invention have been described above with reference to specific embodiments. These descriptions are merely for explaining the principles of the invention and should not be construed as limiting the scope of protection of the invention in any way. Based on this explanation, those skilled in the art can readily conceive of other specific embodiments of the invention without inventive effort, and these equivalent variations or substitutions are all included within the scope defined by the claims of this application.

Claims

1. A cross-flow fan blade, characterized in that, Including the blade body (1); The blade body (1) is a solid structure. The outer surface of the blade body (1) includes a pressure surface (2), a suction surface (3) and two side surfaces (4). The pressure surface (2) and the suction surface (3) are arranged opposite to each other, and the two side surfaces (4) are arranged opposite to each other. The two ends of the pressure surface (2) are respectively enclosed by the two ends of the suction surface (3) to form the leading edge (5) and trailing edge (6) of the blade, and the leading edge (5) and trailing edge (6) of the blade are both rounded. The pressure surface (2) gradually moves from one end of the leading edge (5) of the blade to one end of the trailing edge (6) of the blade towards the suction surface (3), the suction surface (3) is convex, and the size of the leading edge (5) of the blade is larger than the size of the trailing edge (6) of the blade. The cross-sectional thickness of the blade body (1) gradually decreases from one end of the leading edge (5) of the blade to one end of the trailing edge (6) of the blade; The suction surface (3) is recessed and has a cut (7). The cut (7) does not penetrate the pressure surface (2), but penetrates both sides (4). The cross-sectional profile of the blade body (1) has a pressure profile (11), a trailing edge profile (12), a suction profile (13) and a leading edge profile (14) that are connected in sequence. The pressure profile (11), the trailing edge profile (12), the suction profile (13) and the leading edge profile (14) are all arranged in an arc. The connection points between the pressure profile (11), the blade trailing edge profile (12), the suction profile (13), and the blade leading edge profile (14) are defined as design point A1, design point B1, design point B2, and design point A2, respectively. Two points on the suction line (13) are defined as design point B3 and design point B4, respectively. Design point B3 is set close to design point B2, and design point B4 is set close to design point B1. Design points B3 and B4 divide the suction profile (13) into a first arc segment (131), a second arc segment (132), and a third arc segment (133). The first arc segment (131) is located near the leading edge profile (14) of the blade, and the third arc segment (133) is located near the trailing edge profile (12) of the blade. The two ends of the first arc segment (131) are controlled by the design points B2 and B3, the two ends of the second arc segment (132) are controlled by the design points B3 and B4, and the two ends of the third arc segment (133) are controlled by the design points B4 and B1. The opening of the cut (7) is located in the second arc segment (132), and the number of cuts (7) is N, where N is a positive integer and N≤6; An offset arc (15) is formed by equidistant offset of the suction line (13) towards the pressure line (11), and the offset distance between the offset arc (15) and the suction line (13) is defined as H; The depth of the cut (7) is defined as h; The maximum distance between the suction profile (13) and the pressure profile (11) is defined as Hmax; The minimum distance between the suction profile (13) and the pressure profile (11) is defined as Hmin; Where Hmin≤h≤H≤0.5Hmax; The chord length of the pressure line (11) is defined as L, the opening width of the cut (7) is defined as l, and the spacing between adjacent cuts (7) is defined as a. Among them, 3%L≤l≤6%L, 6%L≤a≤13%L; The cuts (7) are defined to be arranged sequentially from the design point B3 to the design point B4; Define the ratio of the depth h of the nth cut (7) to the opening width l as βn; When N=1, 0.45≤β1≤0.6; When N > 1, βn = h / l = β1 - k × (n - 1) / (N - 1), where N represents the number of cuts (7), N is a positive integer and N ≤ 6; β1 represents the ratio of the depth of the first cut to the width of the opening; k represents the gradient coefficient, 0 ≤ k ≤ 0.

6.

2. The cross-flow fan blade according to claim 1, characterized in that, The arc length of the first arc segment (131) is defined as la, the arc length of the second arc segment (132) is defined as lb, and the arc length of the third arc segment (133) is defined as lc; Among them, la=(0.2~0.3)×(la+lb+lc), lb=(0.22~0.35)×(la+lb+lc).

3. The cross-flow fan blade according to claim 2, characterized in that, la:lb:lc=1:1.04:2.

11.

4. The cross-flow fan blade according to claim 1, characterized in that, The radius of the leading edge profile (14) of the blade is defined as the size R1 of the leading edge portion (5) of the blade, and the radius of the trailing edge profile (12) of the blade is defined as the size R2 of the trailing edge portion (6) of the blade. Where 1.5≤R1 / R2≤3.

5. A cross-flow impeller, characterized in that, Includes a hub (100) and a plurality of cross-flow fan blades (200) as described in any one of claims 2-4; The plurality of the cross-flow fan blades (200) are evenly arranged along the circumference of the hub (100); The rotation center of the hub (100) is defined as center O, the leading edge of the blade (5) is located close to center O, and the trailing edge of the blade (6) is located away from center O; Define the included angle formed by the center O, design point A1, and design point A2 as the blade installation angle ∠OA1A2; Where 21°≤∠OA1A2≤31°.

6. A cross-flow impeller according to claim 5, characterized in that, Draw an inlet circle tangent to the pressure profile (11) of the adjacent blade through the design point B2, and define the diameter of the inlet circle as the inlet width D1; Draw an exit circle through the design point A1 that is tangent to the third arc segment (133) of the adjacent blade, and define the diameter of the exit circle as the exit width D2; The range of D1 / D2 is 1.1 to 1.35.

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