Counter-rotating fan

Abstract

The present invention discloses a counter-rotating fan, the counter-rotating fan comprises a first-stage impeller and a second-stage impeller which are coaxial and spaced apart, the first-stage impeller and the second-stage impeller have opposite rotation directions, the first-stage impeller comprises a plurality of first blades arranged circumferentially, the edges of both sides of each first blade in the circumferential direction are respectively a first leading edge and a first trailing edge, the first leading edge and the first trailing edge are both bent in the radial direction from inside to outside toward the rotation direction, the second-stage impeller comprises a plurality of second blades arranged circumferentially, the edges of both sides of each second blade in the circumferential direction are respectively a second leading edge and a second trailing edge, the second leading edge and the second trailing edge are both bent in the radial direction from inside to outside toward the rotation direction. The counter-rotating fan according to the embodiment of the present invention improves the efficiency of the counter-rotating fan, and reduces the rotation noise of the second blade while ensuring the aerodynamic performance of the second blade.

Description

Technical Field

[0001] The invention relates to the field of fan equipment, and in particular to a counter-rotating fan. Background Art

[0002] The counter-rotating blade technology was developed to overcome high static pressure and provide pressure equivalent to that of a two-stage fan. Since the counter-rotating fan structure has no guide vanes, it also has the characteristics of a compact structure. Initially, it was widely used in axial flow fans in the mining industry, and later gradually expanded to military fields such as helicopters and civilian fields such as cooling fans.

[0003] The counter-rotating fans in the related art generally have the following disadvantages:

[0004] 1) In the related art, since the angle between the front and rear blades of the counter-rotating fan is 0, although the front and rear blades rotate in different directions, they will still overlap periodically. The loss flow field flowing out from the trailing edge of the front blade will pass through the leading edge of the rear blade, causing the change of its inflow angle, thereby causing periodic pulsation of the pressure distribution on the surface of the second blade, which will cause greater noise.

[0005] 2) In the related art, when the front and rear blades of a counter-rotating fan overlap, the loss flow field flowing out from the trailing edge of the front blade will pass through the leading edge of the rear blade, causing the inflow angle to change, thereby reducing the aerodynamic performance of the rear blade.

[0006] 3) In the related art, the blades of the counter-rotating fan are designed to be stacked in the radial direction, and the fluid near the blades has a considerable radial motion speed. This speed cannot be used in open fan products, resulting in considerable radial energy loss. Summary of the invention

[0007] The present invention aims to solve at least one of the technical problems existing in the related art. To this end, the present invention provides a counter-rotating fan, wherein the two-stage blades of the counter-rotating fan have good aerodynamic performance and high efficiency.

[0008] According to an embodiment of the present invention, a counter-rotating fan includes a first-stage impeller and a second-stage impeller that are coaxially and spaced apart, the first-stage impeller and the second-stage impeller having opposite rotation directions, the first-stage impeller including a plurality of first blades arranged circumferentially, both side edges of each first blade being a first leading edge and a first trailing edge in the circumferential direction, the first leading edge and the first trailing edge being both bent toward the rotation direction in a radial direction from the inside to the outside, and the curved protrusion of the first leading edge being toward the first trailing edge on the corresponding first blade; the second-stage impeller includes a plurality of second blades arranged circumferentially, both side edges of each second blade being a second leading edge and a second trailing edge in the circumferential direction, the second leading edge and the second trailing edge being both bent toward the rotation direction in a radial direction from the inside to the outside, and the curved protrusion of the second leading edge being toward the second trailing edge on the corresponding second blade.

[0009] According to the counter-rotating fan of the embodiment of the present invention, since the rotation directions of the first-stage impeller and the second-stage impeller are opposite, and the bending direction of the first blade and the bending direction of the second blade are opposite, the radial component of the fluid on the blade surface of the first blade and the second blade is effectively weakened, thereby improving the efficiency of the counter-rotating fan. In addition, the phenomenon of periodic overlap between the first blade and the second-stage impeller during the rotation of the counter-rotating fan is reduced, and the rotation noise of the second blade is reduced while ensuring the aerodynamic performance of the second blade.

[0010] In some embodiments, each of the first blades has a first center line, which is a reference line located on a layer of equal thickness of the first blade, and the first center line is equidistant from the first leading edge and the first trailing edge; each of the second blades has a second center line, which is a reference line located on a layer of equal thickness of the second blade, and the second center line is equidistant from the second leading edge and the second trailing edge; when the projections of any of the first center lines and any of the second center lines on the same radial section intersect, at the intersection point, the angle between the projected tangent of the first center line and the projected tangent of the second center line is Λ 12 , Λ 12 Satisfying conditions: 40°<Λ 12 <140°, the radial cross section is a plane perpendicular to the rotation axis of the counter-rotating fan.

[0011] In some embodiments, the leading edge bend angles Γ of the first blade and the second blade le All conditions are met: 15°<Γ le<75°; wherein, the projection of the first leading edge on the radial section is the first leading edge line, and the angle between the tangent line and the radial line at any point on the first leading edge line is the leading edge bending angle of the first blade; the projection of the second leading edge on the radial section is the second leading edge line, and the angle between the tangent line and the radial line at any point on the second leading edge line is the leading edge bending angle of the second blade; wherein, the radial section is a plane perpendicular to the rotation axis of the counter-rotating fan, and the radial line is a straight line passing through the rotation axis in the radial section.

[0012] In some embodiments, the trailing edge angles Γ of the first blade and the second blade te All conditions are met: 0°<Γ te <60°; wherein, the projection of the first trailing edge on the radial section is the first trailing edge line, and the angle between the tangent line and the radial line at any point on the first trailing edge line is the trailing edge bend angle of the first blade; the projection of the second trailing edge on the radial section is the second trailing edge line, and the angle between the tangent line and the radial line at any point on the second trailing edge line is the trailing edge bend angle of the second blade; wherein, the radial section is a plane perpendicular to the rotation axis of the counter-rotating fan, and the radial line is a straight line passing through the rotation axis in the radial section.

[0013] In some embodiments, the number of the first blades and the number of the second blades are not equal.

[0014] In some embodiments, the first-stage impeller and the second-stage impeller are driven to rotate by two motors respectively.

[0015] In some embodiments, the first-stage impeller is connected to the motor shaft of the first drive motor through a first locking nut, and the second-stage impeller is connected to the motor shaft of the second drive motor through a second locking nut.

[0016] In some specific embodiments, the first drive motor and the second drive motor are both located between the first stage impeller and the second stage impeller.

[0017] In some embodiments, the first-stage impeller and the second-stage impeller are driven to rotate by the same motor.

[0018] In some embodiments, the counter-rotating fan further includes two protective covers, and the two protective covers are respectively disposed on opposite sides of the first-stage impeller and the second-stage impeller.

[0019] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0021] Figure 1 1 is an overall structural diagram of a counter-rotating fan according to an embodiment of the present invention.

[0022] Figure 2 4 is a diagram showing the relative positions of the first impeller and the second impeller in an embodiment of the present invention.

[0023] Figure 3 Schematic diagram of the structure of the first impeller of an embodiment of the present invention.

[0024] Figure 4 Schematic diagram of the structure of the second impeller of the embodiment of the present invention.

[0025] Figure 5 1 is a schematic structural diagram of a counter-rotating fan according to another embodiment of the present invention.

[0026] Reference numerals:

[0027] Counter-rotating fan 100,

[0028] The first-stage impeller 10 , the first blades 110 , the second-stage impeller 20 , the second blades 210 , the first locking nut 30 , the second locking nut 40 , the first drive motor 50 , the second drive motor 60 , and the protective cover 70 .

[0029] first leading edge Le1, first trailing edge Te1, first center line Lo1,

[0030] The second leading edge Le2, the first trailing edge Te2, the second center line Lo2,

[0031] Radial line Ld. DETAILED DESCRIPTION

[0032] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0033] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0034] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0035] Reference below Figure 1-Figure 5 The specific structure of the counter-rotating fan 100 according to the embodiment of the present invention is described.

[0036] like Figure 1 , Figure 3-Figure 4 As shown, a counter-rotating fan 100 according to an embodiment of the present invention includes a first-stage impeller 10 and a second-stage impeller 20 that are coaxial and spaced apart. The first-stage impeller 10 and the second-stage impeller 20 rotate in opposite directions. The first-stage impeller 10 includes a plurality of first blades 110 arranged circumferentially, and the two side edges of each first blade 110 in the circumferential direction are respectively a first leading edge Le1 and a first trailing edge Te1, and the first leading edge Le1 and the first trailing edge Te1 are both bent in the radial direction from the inside to the outside toward the rotation direction, and the bending protrusion of the first leading edge Le1 faces the first trailing edge Te1 on the corresponding first blade 110; the second-stage impeller 20 includes a plurality of second blades 210 arranged circumferentially, and the two side edges of each second blade 210 in the circumferential direction are respectively a second leading edge Le2 and a second trailing edge Te2, and the second leading edge Le2 and the second trailing edge Te2 are both bent in the radial direction from the inside to the outside toward the rotation direction, and the bending protrusion of the second leading edge Le2 faces the second trailing edge Te2 on the corresponding second blade 210.

[0037] It should be noted that the counter-rotating fan 100 of the embodiment of the present invention can be applied to electric fans, circulation fans, ventilation fans, air-conditioning fans and other equipment that need to deliver air. The counter-rotating fan 100 of the embodiment of the present invention is mainly used to promote air flow rather than heat exchange.

[0038] It can be understood that since the first leading edge Le1 and the first trailing edge Te1 of the first blade 110 are both bent radially from the inside to the outside toward the direction of rotation, and the second leading edge Le2 and the second trailing edge Te2 of the second blade 210 are both bent radially from the inside to the outside toward the direction of rotation, this can effectively weaken the radial component of the fluid on the blade surface of the first blade 110 and the second blade 210, so that the energy is concentrated axially as much as possible, reducing the radial loss of the first blade 110 and the second blade 210, improving the working efficiency of the fan, and increasing the output wind pressure and air volume of the counter-rotating fan 100 to a certain extent.

[0039] In addition, the rotation directions of the first-stage impeller 10 and the second blade 210 are opposite, while the bending direction of the first blade 110 is the same as the rotation direction of the first-stage impeller 10, and the bending direction of the second blade 210 is the same as the rotation direction of the second-stage impeller 20, that is, the bending direction of the first blade 110 is opposite to the bending direction of the second blade 210. This structure can reduce the periodic overlap of the first blade 110 and the second-stage impeller 20 during the rotation of the counter-rotating fan 100, so that the loss flow field from the first blade 110 always enters the middle flow channel away from the surface of the second blade 210, and the airflow passing through the surface of the second blade 210 is more uniform. Therefore, not only the aerodynamic performance of the second blade 210 is guaranteed, but also the rotation noise of the second blade 210 is reduced to a certain extent.

[0040] According to the counter-rotating fan 100 of the embodiment of the present invention, since the first-stage impeller 10 and the second-stage impeller 20 rotate in opposite directions, and the bending direction of the first blade 110 and the bending direction of the second blade 210 are opposite, the radial component of the fluid on the blade surface of the first blade 110 and the second blade 210 is effectively weakened, thereby improving the efficiency of the counter-rotating fan 100. In addition, the phenomenon of periodic overlap between the first blade 110 and the second-stage impeller 20 during the rotation of the counter-rotating fan 100 is reduced, and the rotation noise of the second blade 210 is reduced while ensuring the aerodynamic performance of the second blade 210.

[0041] In some embodiments, Figure 2As shown, each first blade 110 has a first center line Lo1, which is a reference line located on the equal thickness layer of the first blade 110, and the first center line Lo1 is equidistant from the first leading edge Le1 and the first trailing edge Te1; ​​each second blade 210 has a second center line Lo2, which is a reference line located on the equal thickness layer of the second blade 210, and the second center line Lo2 is equidistant from the second leading edge Le2 and the second trailing edge Te2; when the projections of any first center line Lo1 and any second center line Lo2 on the same radial section intersect, at the intersection point, the angle between the projected tangent of the first center line Lo1 and the projected tangent of the second center line Lo2 is Λ 12 , Λ 12 Satisfying conditions: 40°<Λ 12 <140°, the radial cross section is a plane perpendicular to the rotation axis of the counter-rotating fan 100 .

[0042] It is understandable that there is an angle between the projected tangent of the first center line Lo1 and the projected tangent of the second center line Lo2, which means that the first blade 110 and the second blade 210 are at least partially staggered in the circumferential direction. In addition, since the bending directions of the first blade 110 and the second blade 210 are opposite, the periodic overlap of the first blade 110 and the second-stage impeller 20 during the rotation of the counter-rotating fan 100 is avoided to a great extent, so that the loss flow field from the first blade 110 always enters the middle flow channel away from the surface of the second blade 210, and the airflow passing through the surface of the second blade 210 is more uniform. Therefore, not only the aerodynamic performance of the second blade 210 is guaranteed, but also the rotation noise of the second blade 210 is reduced to a certain extent.

[0043] In addition, according to experiments, it is proved that when the angle Λ between the projection tangent line of the first center line Lo1 and the projection tangent line of the second center line Lo2 is 12 In the range of 40°-140°, the aerodynamic performance of the second blade 210 is better, and the working noise of the counter-rotating fan 100 is lower. 12 Satisfying conditions: 70°<Λ 12 <110°. Of course, it should be noted that in the embodiment of the present invention, Λ 12 The size of is not limited to the above range, 12 The size can be adjusted according to actual conditions.

[0044] In some embodiments, Figure 3-Figure 4 As shown, the leading edge bending angle Γ of the first blade 110 and the second blade 210 le All conditions are met: 15°<Γ le<75°. The projection of the first leading edge Le1 on the radial section is the first leading edge line, and the angle between the tangent line at any point on the first leading edge line and the radial line Ld is the leading edge bending angle of the first blade 110. The projection of the second leading edge Le2 on the radial section is the second leading edge line, and the angle between the tangent line at any point on the second leading edge line and the radial line Ld is the leading edge bending angle of the second blade 210. The radial section is a plane perpendicular to the rotation axis of the counter-rotating fan 100, and the radial line Ld is a straight line passing through the rotation axis in the radial section.

[0045] It can be understood that the first blade 110 and the second blade 210 are respectively bent in the circumferential direction toward the rotation direction thereof, and such a blade shape can weaken the radial motion component of the airflow when the first blade 110 and the second blade 210 rotate, thereby increasing the axial motion component of the airflow. In other words, such a blade shape can improve the efficiency of the first blade 110 and the second blade 210. Preferably, Γ le Satisfy the conditions: 35°<Γ le <55°. Of course, it should be noted that in the embodiment of the present invention, Γ le The size of is not limited to the above range, le The size of can be adjusted according to the actual situation. In addition, in the embodiment of the present invention, the leading edge bend angle of the first blade 110 and the leading edge bend angle of the second blade 210 can be the same or different.

[0046] In some embodiments, Figure 3-Figure 4 As shown, the trailing edge angles Γ of the first blade 110 and the second blade 210 are te All conditions are met: 0°<Γ te <60°. The projection of the first trailing edge Te1 on the radial section is the first trailing edge line, and the angle between the tangent at any point on the first trailing edge line and the radial line Ld is the trailing edge bending angle of the first blade 110; the projection of the second trailing edge Te2 on the radial section is the second trailing edge line, and the angle between the tangent at any point on the second trailing edge line and the radial line Ld is the trailing edge bending angle of the second blade 210. The radial section is a plane perpendicular to the axis of rotation of the counter-rotating fan 100, and the radial line Ld is a straight line passing through the axis of rotation in the radial section. It can be understood that the first blade 110 and the second blade 210 are respectively bent in the circumferential direction toward their rotation directions. Such a blade shape can weaken the radial motion component of the airflow when the first blade 110 and the second blade 210 rotate, thereby increasing the axial motion component of the airflow. In other words, such a blade shape can improve the efficiency of the first blade 110 and the second blade 210. Preferably, Γ te Satisfying conditions: 20°<Γ te <40°. Of course, it should be noted that in the embodiment of the present invention, Γ te The size of is not limited to the above range,te The size of can be adjusted according to the actual situation. In addition, in the embodiment of the present invention, the trailing edge bend angle of the first blade 110 and the trailing edge bend angle of the second blade 210 can be the same or different.

[0047] It should be noted that when the leading edge angle and the trailing edge angle of the first blade 110 are not equal to the leading edge angle and the trailing edge angle of the second blade 210, the periodic overlap between the first blade 110 and the second blade 210 can be better avoided when they rotate, and by optimizing the above-mentioned angle distribution, the flow field structure can be optimized and the flow field loss can be reduced.

[0048] In some embodiments, the number of the first blades 110 and the second blades 210 are not equal. It is understood that the number of the first blades 110 and the number of the second blades 210 are not equal, which can avoid the overlap of the wake frequency of the first blade 110 and the blade frequency doubling of the second blade 210, thereby avoiding the superposition of the noise spectrum and avoiding the resonance of the first blade 110 and the second blade 210. Of course, in other embodiments of the present invention, the number of the first blades 110 and the second blades 210 can also be the same.

[0049] In some embodiments, the first-stage impeller 10 and the second-stage impeller 20 are driven to rotate by two motors respectively. It is understandable that the first-stage impeller 10 and the second-stage impeller 20 are driven to rotate by two motors respectively, so that the first-stage impeller 10 and the second-stage impeller 20 can rotate at any speed ratio, which greatly avoids the resonance phenomenon between the first-stage impeller 10 and the second-stage impeller 20, thereby greatly reducing the working noise of the counter-rotating fan 100. Of course, in other embodiments of the present invention, the first-stage impeller 10 and the second-stage impeller 20 are driven to rotate by the same motor.

[0050] In some embodiments, Figure 1 As shown, the first-stage impeller 10 is connected to the motor shaft of the first drive motor 50 through the first locking nut 30, and the second-stage impeller 20 is connected to the motor shaft of the second drive motor 60 through the second locking nut 40. As a result, the first-stage impeller 10 and the second-stage impeller 20 can be relatively stable, reducing the possibility of shaking of the first-stage impeller 10 and the second-stage impeller 20 during the operation of the counter-rotating fan 100. Of course, the first-stage impeller 10 and the second-stage impeller 20 can also be connected to the first drive motor 50 and the second drive motor 60 in other ways, which will not be repeated here.

[0051] In some specific embodiments, Figure 1As shown, the first drive motor 40 and the second drive motor 60 are both located between the first stage impeller 10 and the second stage impeller 30. Thus, the damage probability of the first drive motor 40 and the second drive motor 60 is reduced, and the service life of the counter-rotating fan 100 is extended.

[0052] In some embodiments, Figure 5 As shown, the counter-rotating fan 100 further includes two protective covers 70, which are respectively arranged on opposite sides of the first-stage impeller 10 and the second-stage impeller 20. Thus, the occurrence of cutting injuries to users during the rotation of the first-stage impeller 10 and the second-stage impeller 20 is reduced, and the existence of the protective covers 70 improves the safety of the counter-rotating fan.

[0053] Reference below Figure 1-Figure 4 A counter-rotating fan 100 according to a specific embodiment of the present invention is described.

[0054] Example:

[0055] The counter-rotating fan 100 of this embodiment includes a first-stage impeller 10, a second-stage impeller 20, a first locking nut 30, a second locking nut 40, a first drive motor 50, and a second drive motor 60. The first-stage impeller 10 and the second-stage impeller 20 are coaxially arranged and spaced apart, the first locking nut 30 locks the first-stage impeller 10 on the first drive motor 50, and the second locking nut 40 locks the second-stage impeller 20 on the second drive motor 60. The first-stage impeller 10 and the second-stage impeller 20 rotate in opposite directions. The first-stage impeller 10 includes a plurality of first blades 110 arranged circumferentially. The edges on both sides of each first blade 110 in the circumferential direction are respectively a first leading edge Le1 and a first trailing edge Te1. Both the first leading edge Le1 and the first trailing edge Te1 are curved in the radial direction from the inside to the outside toward the direction of rotation. The curved protrusion of the first leading edge Le1 faces the first trailing edge Te1 on the corresponding first blade 110. The second-stage impeller 20 includes a plurality of second blades 210 arranged circumferentially. Both the edges on both sides of each second blade 210 in the circumferential direction are respectively a second leading edge Le2 and a second trailing edge Te2. Both the second leading edge Le2 and the second trailing edge Te2 are curved in the radial direction from the inside to the outside toward the direction of rotation. The curved protrusion of the second leading edge Le2 faces the second trailing edge Te2 on the corresponding second blade 210. The number of the first blades 110 and the second blades 210 is not equal.

[0056] Each first blade 110 has a first center line Lo1, which is a reference line located on the equal thickness layer of the first blade 110, and the first center line Lo1 is equidistant from the first leading edge Le1 and the first trailing edge Te1; ​​each second blade 210 has a second center line Lo2, which is a reference line located on the equal thickness layer of the second blade 210, and the second center line Lo2 is equidistant from the second leading edge Le2 and the second trailing edge Te2; when the projections of any first center line Lo1 and any second center line Lo2 on the same radial section intersect, at the intersection point, the angle between the projected tangent of the first center line Lo1 and the projected tangent of the second center line Lo2 is Λ 12 , Λ 12 Satisfying conditions: 40°<Λ 12 <140°, the radial cross section is a plane perpendicular to the rotation axis of the counter-rotating fan 100 .

[0057] The leading edge bending angle Γ of the first blade 110 and the second blade 210 le All conditions are met: 15°<Γ le <75°; wherein the projection of the first leading edge Le1 on the radial section is the first leading edge line, and the angle between the tangent line at any point on the first leading edge line and the radial line Ld is the leading edge bending angle of the first blade 110. The projection of the second leading edge Le2 on the radial section is the second leading edge line, and the angle between the tangent line at any point on the second leading edge line and the radial line Ld is the leading edge bending angle of the second blade 210. The trailing edge bending angle Γ of the first blade 110 and the second blade 210 te All conditions are met: 0°<Γ te <60°. The projection of the first trailing edge Te1 on the radial section is the first trailing edge line, and the angle between the tangent line at any point on the first trailing edge line and the radial line Ld is the trailing edge bending angle of the first blade 110; the projection of the second trailing edge Te2 on the radial section is the second trailing edge line, and the angle between the tangent line at any point on the second trailing edge line and the radial line Ld is the trailing edge bending angle of the second blade 210. The radial section is a plane perpendicular to the rotation axis of the counter-rotating fan 100, and the radial line Ld is a straight line passing through the rotation axis in the radial section.

[0058] The counter-rotating fan 100 of this embodiment has the following advantages:

[0059] 1) The use of the forward curved blade profile in the design of the counter-rotating fan 100 can form a larger angle between the first blade 110 and the second blade 210, avoiding the periodic overlap of the two-stage blades, thereby reducing the noise of the entire counter-rotating fan 100 and improving the aerodynamic performance of the second blade 210;

[0060] 2) The forward curved blade shape can effectively suppress the radial movement of the fluid near the blade, so that more energy is transmitted axially, thereby improving the efficiency of the counter-rotating fan 100;

[0061] 3) The first blade 110 and the second blade 210 have different numbers of blades, thereby avoiding resonance.

[0062] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0063] Although the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A counter-rotating fan, characterized in that: include: The first-stage impeller and the second-stage impeller are coaxially and spaced apart, and the first-stage impeller and the second-stage impeller rotate in opposite directions. The first-stage impeller comprises a plurality of first blades arranged circumferentially, and the edges on both sides of each first blade in the circumferential direction are respectively a first leading edge and a first trailing edge, and the first leading edge and the first trailing edge are both curved in the radial direction from inside to outside toward the rotation direction, and the curved protrusion of the first leading edge faces the first trailing edge on the corresponding first blade; The second-stage impeller comprises a plurality of second blades arranged circumferentially, and each of the second blades has two side edges in the circumferential direction respectively comprising a second leading edge and a second trailing edge, and the second leading edge and the second trailing edge are both curved in a radial direction from inside to outside toward the direction of rotation, and a curved protrusion of the second leading edge faces the second trailing edge on the corresponding second blade; Each of the first blades has a first centerline, the first centerline is a reference line located on a layer of equal thickness of the first blade, and the first centerline is equidistant from the first leading edge and the first trailing edge; Each of the second blades has a second centerline, the second centerline being a reference line located on a layer of equal thickness of the second blade, and the second centerline being equidistant from the second leading edge and the second trailing edge; When the projections of any of the first center lines and any of the second center lines on the same radial section intersect, at the intersection point, the angle between the projected tangent of the first center line and the projected tangent of the second center line is Λ12, and Λ12 satisfies the condition: 40°<Λ12<140°, and the radial section is a plane perpendicular to the rotation axis of the counter-rotating fan.

2. The counter-rotating fan according to claim 1, characterized in that: The leading edge bend angles Γ of the first blade and the second blade le All conditions are met: 15°<Γ le <75°; among which, The projection of the first leading edge on the radial section is the first leading edge line, and the angle between the tangent line and the radial line at any point on the first leading edge line is the leading edge bending angle of the first blade; The projection of the second leading edge on the radial section is the second leading edge line, and the angle between the tangent line and the radial line at any point on the second leading edge line is the leading edge bend angle of the second blade; wherein, The radial cross section is a plane perpendicular to the rotation axis of the counter-rotating fan, and the radial line is a straight line passing through the rotation axis in the radial cross section.

3. The counter-rotating fan according to claim 1, characterized in that: The trailing edge bend angles Γ of the first blade and the second blade te All conditions are met: 0°<Γ te <60°; among which, The projection of the first trailing edge on the radial section is the first trailing edge line, and the angle between the tangent line and the radial line at any point on the first trailing edge line is the trailing edge bending angle of the first blade; The projection of the second trailing edge on the radial section is the second trailing edge line, and the angle between the tangent line and the radial line at any point on the second trailing edge line is the trailing edge bend angle of the second blade; wherein, The radial cross section is a plane perpendicular to the rotation axis of the counter-rotating fan, and the radial line is a straight line passing through the rotation axis in the radial cross section.

4. The counter-rotating fan according to claim 1, characterized in that: The number of the first blades and the number of the second blades are not equal.

5. The counter-rotating fan according to claim 1, characterized in that: The first-stage impeller and the second-stage impeller are driven to rotate respectively by two motors.

6. The counter-rotating fan according to claim 5, characterized in that: The first-stage impeller is connected to the motor shaft of the first drive motor through a first locking nut, and the second-stage impeller is connected to the motor shaft of the second drive motor through a second locking nut.

7. The counter-rotating fan according to claim 6, characterized in that: The first drive motor and the second drive motor are both located between the first stage impeller and the second stage impeller.

8. The counter-rotating fan according to claim 1, characterized in that: The first-stage impeller and the second-stage impeller are driven to rotate by the same motor.

9. The counter-rotating fan according to any one of claims 1 to 8, characterized in that: The counter-rotating fan further comprises two protective covers, and the two protective covers are respectively arranged on opposite sides of the first-stage impeller and the second-stage impeller.

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