Counter-rotating fan

Abstract

The present invention discloses a counter-rotating fan, comprising a first-stage impeller and a second-stage impeller with opposite rotation directions, the first-stage impeller and the second-stage impeller are driven by two independent driving mechanisms, the first-stage impeller comprises a plurality of first blades, the second-stage impeller comprises a plurality of second blades, the pressure surface of the first blade is arranged opposite to the suction surface of the second blade, and the bending directions of the first blade and the second blade are opposite. According to the counter-rotating fan of the present invention, since the two-stage impellers rotate in opposite directions and the blades are bent in opposite directions, the airflows generated by the two-stage impellers rotate in opposite directions, and the two airflows may de-rotate and continue to run when they meet, so under the condition of a reasonable speed ratio, the fan can output a high-pressure, high-force wind field, and can also output a large-flow, long-distance wind field. In addition, since the driving mechanisms of the two-stage impellers are independent of each other, the counter-rotating fan can obtain an adjustable and controllable wind field, which improves user satisfaction.

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 wind field of traditional fans is generally a rotating vortex annular wind field, which has large energy loss, insufficient wind force, short air supply distance, large wind field pulsation, and poor user satisfaction. Since traditional fans are mostly single-stage axial flow fans, the air supply field of such fans is single and cannot be adjusted or changed. Summary of the invention

[0003] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention provides a counter-rotating fan.

[0004] According to an embodiment of the present invention, a counter-rotating fan includes a first-stage impeller and a second-stage impeller with opposite rotation directions, the first-stage impeller and the second-stage impeller are driven by two independent driving mechanisms, the first-stage impeller includes a plurality of circumferentially spaced first blades, the second-stage impeller includes a plurality of circumferentially spaced second blades, the pressure surface of the first blade is arranged opposite to the suction surface of the second blade, and the bending directions of the first blade and the second blade are opposite.

[0005] According to the counter-rotating fan of the embodiment of the present invention, since the two-stage impellers rotate in opposite directions and the blades bend in opposite directions, the airflows generated by the two-stage impellers rotate in opposite directions, and the two airflows can meet and de-rotate and continue to run. Therefore, under the condition of a reasonable speed ratio, the fan can output a high-pressure, strong-force wind field, and can also output a large-flow, long-distance wind field. In addition, since the driving mechanisms of the two-stage impellers are independent of each other, the counter-rotating fan can obtain an adjustable and controllable wind field, which improves user satisfaction.

[0006] In some embodiments, the inlet angle of the first blade is W1, the inlet angle of the second blade is W3, and the outlet angle of the second blade is W4, W1 and W4 satisfy the relationship: W1-10°≤W4≤W1+10°, W3t-5°≤W3≤W3t+5°, where: W3t=arctan{Fi*tan(W1) / [Fi+tan(W1)]}, Fi is the flow coefficient.

[0007] In some embodiments, the axial width of the first blade is B1, the axial width of the second blade is B2, and B1 and B2 satisfy the relationship: 0.9*B2≤B1≤1.5*B2.

[0008] In some embodiments, the minimum axial gap between the first blade and the second blade is Bg, the axial width of the first blade is B1, and Bg and B1 satisfy the relationship: 0.1*B1≤Bg≤0.8*B1.

[0009] In some embodiments, the hub diameter of the first-stage impeller is D01, the hub diameter of the second-stage impeller is D02, and D01 and D02 satisfy the relationship: 0.8≤D01 / D02≤1.1.

[0010] In some embodiments, the rim diameter of the first-stage impeller is D1, the rim diameter of the second-stage impeller is D2, and D1 and D2 satisfy the relationship: 0.9*D2≤D1≤1.2*D2.

[0011] In some embodiments, the two side edges of the first blade in the circumferential direction are respectively a first leading edge and a first trailing edge, a central angle between the tip end and the root end of the first leading edge is W5, a central angle between the tip end and the root end of the first trailing edge is W6, and W5 and W6 satisfy the relationship: 1.5*W5≤W6≤2.2*W5.

[0012] In some embodiments, the two side edges of the second blade in the circumferential direction are respectively a second leading edge and a second trailing edge, a central angle between the tip end and the root end of the second leading edge is W7, a central angle between the tip end and the root end of the second trailing edge is W8, and W7 and W8 satisfy the relationship: 1.4*W7≤W8≤2.1*W7.

[0013] In some embodiments, the number of the first blades is BN1, the number of the second blades is BN2, and BN1 and BN2 satisfy the relationship: BN2-2≤BN1≤2*BN2.

[0014] In some embodiments, the rotation speed of the first-stage impeller is equal to the rotation speed of the second-stage impeller, so that the wind field formed by the counter-rotating fans is a straight wind field.

[0015] In some embodiments, the rotational speed of the first-stage impeller is N1 and the rotational speed of the second-stage impeller is N2. When 0.2≤N1 / N2, when N1 and N2 are not equal, the wind field formed by the counter-rotating fan is an annular vortex wind field with a diffusion cone angle.

[0016] In some embodiments, the first-stage impeller and the second-stage impeller form a wind wheel group, and the counter-rotating fan includes a plurality of the wind wheel groups distributed along the axial direction.

[0017] In some embodiments, a blade profile of the first blade is different from a blade profile of the second blade.

[0018] In some embodiments, the rim diameter of the first blade is equal to the rim diameter of the second blade, or the rim diameter of the first blade is not equal to the rim diameter of the second blade.

[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 Schematic diagram of the structure of the first-stage impeller and the second-stage impeller of an embodiment of the present invention.

[0023] Figure 3 Schematic diagram of the wind field when the two-stage impellers of the counter-rotating fan of the embodiment of the present invention rotate at the same speed.

[0024] Figure 4 It is a schematic diagram of the wind field when the rotation speeds of the two-stage impellers of the counter-rotating fan of the embodiment of the present invention are unequal.

[0025] Figure 5 It is a schematic diagram of the outlet diffusion cone angle when the rotation speeds of the two-stage impellers of the counter-rotating fan of the embodiment of the present invention are approximately equal.

[0026] Figure 6 It is a schematic diagram of the outlet diffusion cone angle when the rotation speed difference between the two-stage impellers of the counter-rotating fan in an embodiment of the present invention is relatively large.

[0027] Figure 7 It is a line graph of the PIV axial plane velocity field test results when the two-stage impeller rotation speeds of the counter-rotating fan of the embodiment of the present invention are equal.

[0028] Figure 8 It is a line graph of the PIV axial plane velocity field test results when the speed ratio of the two-stage impellers of the counter-rotating fan of the embodiment of the present invention is greater than 1.

[0029] Fig. 9 It is a line graph of the PIV axial plane velocity field test results when the speed ratio of the two-stage impellers of the counter-rotating fan of the embodiment of the present invention is less than 1.

[0030] Fig.10 The figure is a diagram for explaining the parameter definition of the first blade and the second blade of the counter-rotating fan according to the embodiment of the present invention.

[0031] Fig.11It is a schematic diagram of blade profile parameter definition of a first blade of a counter-rotating fan according to an embodiment of the present invention.

[0032] Fig.12 Schematic diagram of blade profile parameter definition of a second blade of a counter-rotating fan according to an embodiment of the present invention.

[0033] Fig.13 It is a schematic structural diagram of a first-stage impeller and a second-stage impeller according to another embodiment of the present invention.

[0034] Fig.14 This is the corresponding relationship diagram between the minimum axial clearance and rotation noise of the first-stage impeller and the second-stage impeller.

[0035] Reference numerals:

[0036] The counter-rotating fan 100, the air inlet grille 1, the first-stage impeller 2, the first blade 21, the first hub 22, the first drive assembly 3, the motor bracket 4, the second-stage impeller 5, the second blade 51, the second hub 52, the second drive assembly 6, the air outlet grille 7, the first-stage air guide ring 8, the second-stage air guide ring 9,

[0037] The first blade type is BS1, the second blade type is BS2,

[0038] first leading edge LE1, first trailing edge TE1, second leading edge LE2, second trailing edge TE2,

[0039] Pressure surface Ps, suction surface Ss. DETAILED DESCRIPTION

[0040] 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.

[0041] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate positions or positional relationships based on the positions 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, "multiple" means two or more.

[0042] 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.

[0043] Reference below Figure 1-Figure 13 A counter-rotating fan 100 according to an embodiment of the present invention is described.

[0044] like Figure 1-Figure 2 ,like Fig.13 As shown, the counter-rotating fan 100 according to the embodiment of the present invention includes a first-stage impeller 2 and a second-stage impeller 5 with opposite rotation directions. The first-stage impeller 2 and the second-stage impeller 5 are driven by two independent driving mechanisms. The first-stage impeller 2 includes a plurality of circumferentially spaced first blades 21, and the second-stage impeller 5 includes a plurality of circumferentially spaced second blades 51. The pressure surface Ps (i.e., Fig.10 The inner concave surface shown in FIG. 1 and the suction surface Ss of the second blade 51 (ie Fig.10 The outer convex surfaces shown in the figure are arranged opposite to each other, and the bending directions of the first blade 21 and the second blade 51 are opposite.

[0045] 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.

[0046] It can be understood that, since the counter-rotating fan 100 of the embodiment of the present invention includes two-stage impellers, the rotation of the first-stage impeller 2 will form an annular vortex wind flow. When the second-stage impeller 5 rotates simultaneously with the first-stage impeller 2, under the influence of the wind field of the second-stage impeller 5, the annular vortex wind flow formed by the rotation of the first-stage impeller 2 will de-rotate and continue. The difference in structural parameters and rotation speed of the first-stage impeller 2 and the second-stage impeller 5 will lead to different results of wind flow de-rotation and continuation. In some cases, the fan will output a high-pressure, strong-force wind field, and in some cases, the fan will output a large-flow, long-distance wind field.

[0047] At the same time, since the first-stage impeller 2 and the second-stage impeller 5 are driven by two independent driving mechanisms, the speed ratio of the first-stage impeller 2 and the second-stage impeller 5 can be adjusted, so that at different speed ratios, the counter-rotating fan 100 can output wind fields with different characteristics, thereby enriching the output wind field types of the counter-rotating fan 100 and improving user satisfaction.

[0048] According to the counter-rotating fan 100 of the embodiment of the present invention, since the counter-rotating fan 100 includes two-stage impellers with opposite rotation directions and blade bending directions, under different parameter conditions, the fan can output a high-pressure, strong-force wind field, or a large-flow, long-distance wind field. Since the driving mechanisms of the two-stage impellers are independent of each other, the counter-rotating fan 100 can obtain an adjustable and controllable wind field, thereby improving user satisfaction.

[0049] In some embodiments, Fig.10 As shown, the inlet angle of the first blade 21 is W1, the inlet angle of the second blade 51 is W3, and the outlet angle of the second blade 51 is W4. W1 and W4 satisfy the relationship: W1-10°≤W4≤W1+10°, W3t-5°≤W3≤W3t+5°, where: W3t=arctan{Fi*tan(W1) / [Fi+tan(W1)]}, Fi is the flow coefficient.

[0050] It can be understood that the size of the inlet angle W1 of the first blade 21, the inlet angle W3 of the second blade 51, and the outlet angle W4 affect the air outlet characteristics of the first-stage impeller 2 and the second-stage impeller 5 to a certain extent. It has been proved through many tests that when the inlet angle W1 of the first blade 21, the inlet angle W3 of the second blade 51, and the outlet angle W4 of the second blade 51 satisfy the above relationship, the air outlet characteristics of the first-stage impeller 2 and the second-stage impeller 5 are better, the air volume is larger, and the air supply distance is longer.

[0051] In some embodiments, Fig.10 As shown, the axial width of the first blade 21 is B1, and the axial width of the second blade 51 is B2, and B1 and B2 satisfy the relationship: 0.9*B2≤B1≤1.5*B2. It can be understood that, in general, the total axial width of the counter-rotating fan 100 is limited, and the reasonably distributed axial widths of the first blade 21 and the second blade 51 are conducive to ensuring the air outlet characteristics of the counter-rotating fan 100. According to multiple tests, when B1 / B2 is within the range of 0.9-1.5, the counter-rotating fan 100 has better air outlet characteristics. At this time, the air outlet of the counter-rotating fan 100 is larger and the air supply distance is longer.

[0052] Advantageously, B1 and B2 satisfy the relationship: 1.2*B2≤B1≤1.4*B2. Of course, it should be noted that the values ​​of B1 and B2 are not limited to the above ranges, and in practical applications, B1 and B2 can be adaptively adjusted according to actual needs.

[0053] In some embodiments, Fig.10 As shown, the minimum axial gap between the first blade 21 and the second blade 51 is Bg, the axial width of the first blade 21 is B1, and Bg and B1 satisfy the relationship: 0.1*B1≤Bg≤0.8*B1. It can be understood that the size of the axial gap between the first blade 21 and the second blade 51 can directly affect the output wind field performance of the counter-rotating fan 100. When Bg / B1 is in the range of 0.1-0.8, the counter-rotating fan 100 can have better wind output characteristics.

[0054] Advantageously, Bg satisfies the relationship: 10 mm ≤ Bg ≤ 20 mm. Of course, it should be noted that the value of Bg is not limited to the above range, and in practical applications, Bg can be adaptively adjusted according to actual needs.

[0055] In some embodiments, Fig.11 -like Fig.12 As shown, the hub diameter of the first-stage impeller 2 is D01, the hub diameter of the second-stage impeller 5 is D02, and D01 and D02 satisfy the relationship: 0.8≤D01 / D02≤1.1. It can be understood that the size of D01 / D02 directly affects the superposition relationship between the wind field output by the first-stage impeller 2 and the wind field output by the second-stage impeller 5. According to multiple tests, when D01 / D02 is in the range of 0.8-1.1, the wind field output by the first-stage impeller 2 and the wind field output by the second-stage impeller 5 have a stronger mutual influence, thereby ensuring that the counter-rotating fan 100 can output a wind field with a larger output pressure and a longer air supply distance. Of course, it should be noted here that the specific ratio of D01 and D02 can be adjusted according to actual needs and is not limited to the above range.

[0056] In some embodiments, Fig.11 -like Fig.12As shown, the rim diameter of the first-stage impeller 2 is D1, and the rim diameter of the second-stage impeller 5 is D2, and D1 and D2 satisfy the relationship: 0.9*D2≤D1≤1.2*D2. The size of D1 / D2 directly affects the superposition relationship between the wind field output by the first-stage impeller 2 and the wind field output by the second-stage impeller 5. According to multiple tests, when D1 / D2 is in the range of 0.9-1.2, the wind field output by the first-stage impeller 2 and the wind field output by the second-stage impeller 5 have a stronger mutual influence, thereby ensuring that the counter-rotating fan 100 can output a wind field with a larger output pressure and a longer air supply distance. Advantageously, D1 / D2=1, that is, D1=D2. Of course, it should be noted here that the specific ratio of D1 and D2 can be adjusted according to actual needs and is not limited to the above range.

[0057] In some embodiments, Fig.11 As shown, the two side edges of the first blade 21 in the circumferential direction are respectively the first leading edge LE1 and the first trailing edge TE1, the center angle between the tip and the root of the first leading edge LE1 is W5, the center angle between the tip and the root of the first trailing edge TE1 is W6, and W5 and W6 satisfy the relationship: 1.5*W5≤W6≤2.2*W5. It can be understood that the shapes of the first leading edge LE1 and the first trailing edge TE1 of the first blade 21 have a great influence on the output wind field of the first-stage impeller 2, and W5 and W6 determine the degree of curvature of the first leading edge LE1 and the first trailing edge TE1 to a certain extent, respectively. A large number of experiments have proved that W6 / W5 in the range of 1.5-2.2 can ensure that the first-stage impeller 2 has good wind outlet characteristics, and can also reduce the noise generated when the first-stage impeller 2 rotates to a certain extent. Of course, it should be noted here that the ratio of W6 / W5 can be adaptively adjusted according to the requirements of the wind field, and is not limited to the above range.

[0058] In some embodiments, Fig.12As shown, the two side edges of the second blade 51 in the circumferential direction are the second leading edge LE2 and the second trailing edge TE2, respectively. The central angle between the tip and the root of the second leading edge LE2 is W7, and the central angle between the tip and the root of the second trailing edge TE2 is W8. W7 and W8 satisfy the relationship: 1.4*W7≤W8≤2.1*W7. It can be understood that the shapes of the second leading edge LE2 and the second trailing edge TE2 of the second blade 51 have a great influence on the output wind field of the second-stage impeller 5, and W7 and W8 determine the curvature of the second leading edge LE2 and the second trailing edge TE2 to a certain extent. A large number of experiments have proved that W8 / W7 in the range of 1.4-2.1 can ensure that the second-stage impeller 5 has good wind outlet characteristics, and can also reduce the noise generated when the second-stage impeller 5 rotates to a certain extent. Of course, it should be noted here that the ratio of W8 / W7 can be adaptively adjusted according to the requirements of the wind field, and is not limited to the above range. Advantageously, the first leading edge LE1 is curved toward the direction in which the first-stage impeller 2 rotates, and the second leading edge LE2 is curved toward the direction in which the second-stage impeller 5 rotates.

[0059] like Fig.11 As shown, the first-stage impeller 2 includes a first hub 22 and a first blade 21 disposed on the first hub 22. The cylindrical diameter of the first hub 22 is D01, the cylindrical diameter of the rim is D1, and the first blade 21 is composed of first blade profiles BS1 stacked at positions with different diameters Dx1 (D01≤Dx1≤D1). The shape of the first blade profile BS1 is as shown in FIG. Fig.11 shown.

[0060] like Fig.12 As shown, the second-stage impeller 5 includes a second hub 52 and a second blade 51 disposed on the second hub 52. The cylindrical diameter of the second hub 52 is D02, the cylindrical diameter of the rim is D2, and the second blade 51 is composed of second blade profiles BS2 stacked at positions with different diameters Dx2 (D02≤Dx2≤D2). The shape of the second blade profile BS2 is as follows: Fig.12 shown.

[0061] In some embodiments, the number of first blades 21 is BN1, the number of second blades 51 is BN2, and BN1 and BN2 satisfy the relationship: BN2-2≤BN1≤2*BN2. It can be understood that the values ​​of BN1 and BN2 will directly affect the wind field superposition result of the first-stage impeller 2 and the second-stage impeller 5. According to actual experiments, when BN1 and BN2 satisfy the relationship: BN2-2≤BN1≤2*BN2, the wind field superposition effect of the first-stage impeller 2 and the second-stage impeller 5 is the best, and the wind outlet characteristics of the counter-rotating fan 100 are better guaranteed. Of course, in other embodiments of the present invention, the values ​​of BN1 and BN2 can be specifically selected according to actual conditions and are not limited to the above range.

[0062] After a fan leaves the factory, usually the structural parameters cannot be changed, and the wind field formed by the operation of the fan is also relatively simple. Although the structural parameters of the counter-rotating fan 100 of the embodiment of the present invention cannot be changed after leaving the factory, the speed ratio of the two-stage impeller can be adjusted, and the fan can obtain different wind fields at different speed ratios. The following will describe the wind field conditions at different fan speed ratios when the structural parameters are fixed. Of course, the changes in the wind field conditions obtained at a certain speed ratio are all based on the premise that the fan structural parameters are fixed, relative to the wind fields obtained at other speed ratios.

[0063] like Figure 3 As shown, the rotation speed of the first-stage impeller 2 is equal to the rotation speed of the second-stage impeller 5. At this time, the wind field formed by the counter-rotating fan 100 can be regarded as a straight wind field. It can be understood that the wind field output by the traditional fan is an annular vortex wind field, which has a large energy loss, small wind force and a short air supply distance. For the counter-rotating wind wheel of the embodiment of the present invention, when the rotation speeds of the first-stage impeller 2 and the second-stage impeller 5 are equal, the wind field of the second-stage impeller 5 will have a derotation and endurance effect on the wind field of the first-stage impeller 2, so that the wind field input by the counter-rotating fan 100 forms a focused straight wind field. This wind field has a long air supply distance, a more uniform wind pressure and better wind field characteristics. Of course, it should be noted here that, Figure 5 As shown, in actual application, there will inevitably be a deviation between the rotation speed of the first-stage impeller 2 and the rotation speed of the second-stage impeller 5, but the difference is very small. Due to the existence of the speed deviation of the two-stage impellers, even if the deviation angle is small, the output wind field will have a certain outlet cone angle. At this time, the outlet cone angle is generally small, and such an output wind sound can also be approximated as a straight wind field.

[0064] like Figure 4 As shown, the speed of the first-stage impeller 2 is N1 and the speed of the second-stage impeller 5 is N2. When N1 and N2 are not equal, the wind field formed by the counter-rotating fan 100 is an annular vortex wind field with a diffusion cone angle. Due to the certain diffusion cone angle, the counter-rotating fan 100 has a larger air outlet range and a softer air outlet. Although the air supply distance is short, the convection effect of the airflow is better than the wind field output by the traditional fan. Specifically, Figure 6 As shown in the figure, it is assumed that the diffusion cone angle of the annular vortex wind field generated by the rotation of a single impeller is A 00 , when 1.6≥N1 / N2>1, the diffusion cone angle of the annular vortex wind field generated by the counter-rotating impeller of the embodiment of the present invention is 0≤A 03 ≤1.3*A 00 ; When 0.2≤N1 / N2<1, the diffusion cone angle of the wind field generated by the counter-rotating impeller of the embodiment of the present invention is 0.8*A 00 ≤A 03 ≤2*A 00, when 0<N1 / N2≤0.2, the diffusion cone angle of the wind field generated by the counter-rotating impeller of the embodiment of the present invention is approximately equal to A 00 .

[0065] To sum up, the counter-rotating fan 100 of the embodiment of the present invention can obtain an adjustable and controllable wind field by adjusting the speed difference between the first-stage impeller 2 and the second-stage impeller 5, so that the counter-rotating fan 100 can generate both a conventional fan rotating circular air supply wind field and a differentiated air supply wind field with a straight beam focus.

[0066] Therefore, the wind outlet of the counter-rotating fan 100 can be adjusted to wide-angle diffuse soft wind, straight beam-like strong wind, or any wind between wide-angle diffuse soft wind and straight beam-like strong wind. It should be additionally explained here that the wide-angle soft diffuse wind has a larger diffusion angle and the wind outlet is relatively soft, which is suitable for occasions where the air convection requirement is relatively slow. The straight beam-like strong wind has a smaller diffusion angle, a larger wind pressure at the outlet, and a longer air supply distance, which is suitable for occasions where the convection speed requirement is relatively fast. In addition, the arbitrary wind between the two mentioned above refers to the wind outlet with a diffusion angle between the wide-angle diffuse soft wind and the straight beam-like strong wind, and the wind pressure at the outlet is also between the two.

[0067] In some embodiments, the first-stage impeller 2 and the second-stage impeller 5 form a wind wheel group, and the counter-rotating fan 100 includes multiple wind wheel groups distributed at intervals along the axial direction. In this way, multiple wind wheel groups are combined to form more wind field types, and the counter-rotating fan 100 includes multiple wind wheel groups, which can better adapt to various airflow convection requirements, thereby improving customer satisfaction of the counter-rotating fan 100.

[0068] In some embodiments, the blade shape of the first blade 21 and the blade shape of the second blade 51 may be the same, and in other embodiments, the blade shape of the first blade 21 and the blade shape of the second blade 51 may be different. It can be understood that the different blade shapes of the first blade 21 and the second blade 51 can increase the types of the wind field of the counter-rotating fan 100, so that the counter-rotating fan 100 can better meet the use requirements.

[0069] The rim diameter of the first blade 21 may be equal to the rim diameter of the second blade 51, or may not be equal to the rim diameter of the second blade 51. In both cases, the counter-rotating fan 100 can obtain a high wind pressure, large flow, long-distance and powerful wind field as required.

[0070] Reference below Figure 1-Figure 12 A counter-rotating fan 100 according to a specific embodiment of the present invention is described.

[0071] Embodiment 1:

[0072] The counter-rotating fan 100 of the embodiment of the present invention comprises an air inlet grille 1, a first-stage impeller 2, a first drive assembly 3, a motor bracket 4, a second-stage impeller 5, a second drive assembly 6, an air outlet grille 7, a first-stage air guide ring 8 and a second-stage air guide ring 9. The first-stage impeller 2 comprises five circumferentially spaced first blades 21, the second-stage impeller 5 comprises five circumferentially spaced second blades 51, the pressure surface Ps of the first blade 21 is arranged opposite to the suction surface Ss of the second blade 51, and the bending directions of the first blade 21 and the second blade 51 are opposite.

[0073] This embodiment is a counter-rotating fan 100 with an outer cover diameter of 200 mm. The PIV axial plane velocity field test results of the two-stage impellers rotating at the same speed are as follows: Figure 7 As shown; the PIV axial plane velocity field test results when the two-stage impeller speed ratio is greater than 1 are shown in Figure 8 As shown; the PIV axial plane velocity field test results when the two-stage impeller speed ratio is less than 1 are shown in Fig. 9 shown.

[0074] It should be noted here that Figure 7-Figure 9 In FIG. 1 , the X-axis direction is the axial direction of the counter-rotating fan 100, and the Y-axis direction is the radial direction of the counter-rotating fan 100. Figure 7 As shown, when the two-stage impellers rotate at the same speed, the airflow remains substantially horizontal in the positive direction of X. At this time, the counter-rotating fan 100 outputs a straight wind field, which has a longer air supply distance and a higher wind pressure. Figure 8 As shown, when the speed ratio of the two-stage impeller is greater than 1, the airflow is significantly offset in the positive direction of X. At this time, the wind field output by the counter-rotating fan 100 has a certain diffusion angle. Such a wind field has a shorter air supply distance, but the air output is relatively soft. Fig. 9 As shown, when the speed ratio of the two-stage impeller is less than 1, a rotating vortex ring appears in the airflow closer to the counter-rotating fan. Such a wind field has a shorter air supply distance and a softer air output, which is very suitable for some occasions with lower requirements for airflow convection speed.

[0075] For example, when the indoor air conditioner is just turned on, the two-stage impellers can be set to rotate at the same speed, so that the counter-rotating fan 100 can deliver air over a long distance, which can enhance the air supply function of the air conditioner, blow the hot air or cold air blown by the air conditioner to every corner of the room, and accelerate indoor air convection. When there are a large number of people in the room, the speed ratio of the two-stage impeller can be adjusted to be greater than 1, so that the air supply area is increased and the comfort is improved. When the user wants to enter a resting state, the speed ratio of the two-stage impeller can be adjusted to less than 1, so that it is not easy to catch a cold when using it in a sleeping state.

[0076] In summary, the user can adjust the rotation speeds of the first-stage impeller 2 and the second-stage impeller to achieve different wind fields output by the counter-rotating fan 100 to adapt to different usage scenarios, thereby further improving the practicality of the counter-rotating fan 100.

[0077] Assume that the diffusion cone angle of the annular vortex wind field generated by the rotation of a single impeller is A 00 , when 1.6≥N1 / N2>1, the diffusion cone angle of the annular vortex wind field generated by the counter-rotating impeller of this embodiment is 0≤A 03 ≤1.3*A 00 ; When 0.2≤N1 / N2<1, the diffusion cone angle of the wind field generated by the counter-rotating impeller of this embodiment is 0.8*A 00 ≤A 03 ≤2*A 00 , when 0<N1 / N2≤0.2, the diffusion cone angle of the wind field generated by the counter-rotating impeller of the embodiment of the present invention is approximately equal to A 00 .

[0078] like Fig.10 As shown, the inlet angle of the first blade 21 is W1, the outlet angle of the first blade 21 is W2, the inlet angle of the second blade 51 is W3, the outlet angle of the second blade 51 is W4, W1 and W4 satisfy the relationship: W1-10°≤W4≤W1+10°, W3t-5°≤W3≤W3t+5°, W2=W3, where: W3t=arctan{Fi*tan(W1) / [Fi+tan(W1)]}, Fi is the flow coefficient. The axial width of the first blade 21 is B1, the axial width of the second blade 51 is B2, B1 and B2 satisfy the relationship: B1=1.4*B2, and the minimum axial clearance between the first blade 21 and the second blade 51 is Bg=30mm. The hub diameter D1 of the first-stage impeller 2 is equal to the hub diameter D2 of the second-stage impeller 5. The rim diameter D01 of the first-stage impeller 2 is equal to the rim diameter D02 of the second-stage impeller 5. The two side edges of the first blade 21 in the circumferential direction are respectively the first leading edge LE1 and the first trailing edge TE1, the center angle between the tip and the root of the first leading edge LE1 is W5, and the center angle between the tip and the root of the first trailing edge TE1 is W6. The two side edges of the second blade 51 in the circumferential direction are respectively the second leading edge LE2 and the second trailing edge TE2, the center angle between the tip and the root of the second leading edge LE2 is W7, and the center angle between the tip and the root of the second trailing edge TE2 is W8. W5, W6, W7, and W8 satisfy the relationship: W6=2W5, W8=2W7, W5=W7=20°.

[0079] Example 2

[0080] The structure of the counter-rotating fan 100 of this embodiment is substantially the same as that of the embodiment 1. Only the features that are different between the embodiment 2 and the embodiment 1 are described below. This embodiment is a counter-rotating fan 100 with an outer cover diameter of 200 mm. When 1.3 ≥ N1 / N2 > 1, the diffusion cone angle 0 ≤ A of the annular vortex wind field generated by the counter-rotating impeller of this embodiment 03 ≤1.2*A00 ; When 0.2≤N1 / N2<1, the diffusion cone angle of the wind field generated by the counter-rotating impeller of this embodiment is 0.8*A 00 ≤A03≤2*A 00 .

[0081] In this embodiment, W4=W1, B1=B2, Bg=15mm, D01=D02, D1=D2, BN1=9, BN2=7, and the experimental curve of noise changing with the distance Bg between the two blades is as follows: Fig.14 shown.

[0082] 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.

[0083] 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: The invention comprises a first-stage impeller and a second-stage impeller with opposite rotation directions, wherein the first-stage impeller and the second-stage impeller are driven by two independent driving mechanisms, wherein the first-stage impeller comprises a plurality of circumferentially spaced first blades, and the second-stage impeller comprises a plurality of circumferentially spaced second blades, wherein the pressure surface of the first blade is arranged opposite to the suction surface of the second blade, and the bending directions of the first blade and the second blade are opposite; The inlet angle of the first blade is W1, the inlet angle of the second blade is W3, and the outlet angle of the second blade is W4. W1 and W4 satisfy the relationship: W1-10°≤W4≤W1+10°, W3t-5°≤W3≤W3t+5°, where: W3t=arctan{Fi*tan(W1) / [Fi+tan(W1)]}, Fi is the flow coefficient.

2. The counter-rotating fan according to claim 1, characterized in that: The axial width of the first blade is B1, the axial width of the second blade is B2, and B1 and B2 satisfy the relationship: 0.9*B2≤B1≤1.5*B2.

3. The counter-rotating fan according to claim 1, characterized in that: The minimum axial gap between the first blade and the second blade is Bg, the axial width of the first blade is B1, and Bg and B1 satisfy the relationship: 0.1*B1≤Bg≤0.8*B1.

4. The counter-rotating fan according to claim 1, characterized in that: The hub diameter of the first-stage impeller is D01, the hub diameter of the second-stage impeller is D02, and D01 and D02 satisfy the relationship: 0.8≤D01 / D02≤1.

1.

5. The counter-rotating fan according to claim 1, characterized in that: The rim diameter of the first-stage impeller is D1, and the rim diameter of the second-stage impeller is D2. D1 and D2 satisfy the relationship: 0.9*D2≤D1≤1.2*D2.

6. The counter-rotating fan according to claim 1, characterized in that: The two side edges of the first blade in the circumferential direction are respectively the first leading edge and the first trailing edge, the central angle between the tip end and the root end of the first leading edge is W5, the central angle between the tip end and the root end of the first trailing edge is W6, and W5 and W6 satisfy the relationship: 1.5*W5≤W6≤2.2*W5.

7. The counter-rotating fan according to claim 1, characterized in that: The two side edges of the second blade in the circumferential direction are respectively the second leading edge and the second trailing edge, the central angle between the tip end and the root end of the second leading edge is W7, the central angle between the tip end and the root end of the second trailing edge is W8, and W7 and W8 satisfy the relationship: 1.4*W7≤W8≤2.1*W7.

8. The counter-rotating fan according to claim 1, characterized in that: The number of the first blades is BN1, the number of the second blades is BN2, and BN1 and BN2 satisfy the relationship: BN2-2≤BN1≤2*BN2.

9. The counter-rotating fan according to any one of claims 1 to 8, characterized in that: The rotation speed of the first-stage impeller is equal to the rotation speed of the second-stage impeller, so that the wind field formed by the counter-rotating fans is a straight wind field.

10. The counter-rotating fan according to any one of claims 1 to 8, characterized in that: The rotation speed of the first-stage impeller is N1 and the rotation speed of the second-stage impeller is N2. When N1 and N2 are not equal, the wind field formed by the counter-rotating fans is an annular vortex wind field with a diffusion cone angle.

11. The counter-rotating fan according to claim 1, characterized in that: The first-stage impeller and the second-stage impeller form a wind wheel group, and the counter-rotating fan includes a plurality of the wind wheel groups distributed along the axial direction.

12. The counter-rotating fan according to claim 1, characterized in that: The blade profile of the first blade is different from the blade profile of the second blade.

13. The counter-rotating fan according to claim 1, characterized in that: The rim diameter of the first blade is equal to the rim diameter of the second blade, or the rim diameter of the first blade is not equal to the rim diameter of the second blade.

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