Counter-rotating fans and air conditioners

Abstract

The present application relates to a counter-rotating fan, which includes a casing and a hub disposed inside the casing, wherein a first blade and a second blade are sequentially disposed along the axial direction of the hub, and the length of the second blade is shorter than that of the first blade. The first blade and the second blade are sequentially disposed along the axial direction of the hub, and the lengths of the first and second blades are different. The inner cylinder is disposed outside the second blade. When the airflow passes through the first blade, it passes through the flow channel surrounded by the casing. When the airflow passes through the second blade, the airflow is divided by the inner cylinder, with one part passing through the inside of the inner cylinder and the other part passing through the flow channel between the inner cylinder and the casing. The airflow sent out from the inner cylinder has a longer air supply distance, and the airflow sent out between the casing and the inner cylinder has a shorter air supply distance, so that the counter-rotating fan can take into account both long-distance and short-distance air supply. The present application also discloses an air conditioner.

Description

Technical Field

[0001] The present application relates to the field of fan technology, for example, to counter-rotating fans and air conditioners. Background Art

[0002] A counter-rotating fan generally refers to a two-stage fan arranged along the same axis, and a drive device is provided to drive the fan to rotate. A counter-rotating fan can provide pressure equivalent to that of a two-stage fan. The two-stage fan can rotate at the same / different speeds / directions, thereby achieving multiple air supply modes such as forward, reverse, long-distance, and non-sensing, thereby improving the flexibility of air supply. When the two-stage fans rotate in opposite directions, long-distance air supply can be achieved; when the two fans rotate in the same direction, airflow divergence and non-sensing air supply can be achieved. Counter-rotating fans were previously mainly used in the engine field, and in recent years have gradually been used in household appliances such as air conditioners, dehumidifiers, and electric fans.

[0003] In the process of implementing the embodiments of the present disclosure, it was found that at least the following problems exist in the related art: the air supply characteristic of the counter-rotating fan is axial long-distance air supply, and the effect of short-distance air supply is not ideal. Summary of the Invention

[0004] In order to provide a basic understanding of some aspects of the disclosed embodiments, a brief summary is given below. The summary is not an extensive review, nor is it intended to identify key / critical elements or delineate the scope of protection of these embodiments, but rather serves as a prelude to the detailed description that follows.

[0005] The embodiments of the present disclosure provide a counter-rotating fan and an air conditioner to solve the technical problem that the short-range air supply effect of the counter-rotating fan is not ideal.

[0006] In some embodiments, the counter-rotating fan includes a casing and a hub disposed inside the casing, wherein a first blade and a second blade are sequentially disposed along the axial direction of the hub, and a blade length of the second blade is shorter than a blade length of the first blade.

[0007] An embodiment of the present disclosure further provides an air conditioner, comprising the counter-rotating fan provided by any of the aforementioned embodiments.

[0008] The counter-rotating fan and air conditioner provided by the embodiments of the present disclosure can achieve the following technical effects: the first blade and the second blade are arranged in sequence in the axial direction of the hub, and the lengths of the first and second blades are different. The inner cylinder is arranged on the outside of the second blade. When the airflow passes through the first blade, it passes through the flow channel surrounded by the casing. When the airflow passes through the second blade, the airflow is divided by the inner cylinder, one part passes through the inside of the inner cylinder, and the other part passes through the flow channel between the inner cylinder and the casing. The airflow sent out from the inner cylinder has a longer air supply distance, and the airflow sent out between the casing and the inner cylinder has a shorter air supply distance, so that the counter-rotating fan can take into account both long-distance air supply and short-distance air supply.

[0009] The above general description and the following description are exemplary and explanatory only and are not intended to limit the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] One or more embodiments are exemplarily described by corresponding drawings. These exemplary descriptions and drawings do not limit the embodiments. Elements with the same reference numerals in the drawings are shown as similar elements. The drawings do not constitute a scale limitation. In addition,

[0011] Figure 1 is a cross-sectional schematic diagram of a counter-rotating fan provided by an embodiment of the present disclosure;

[0012] Figure 2 yes Figure 1 A partial enlarged schematic diagram of point A in the middle;

[0013] Figure 3 is another structural schematic diagram of the casing provided by an embodiment of the present disclosure;

[0014] Figure 4 is a structural schematic diagram of a counter-rotating fan provided by an embodiment of the present disclosure;

[0015] Figure 5 is another structural schematic diagram of the counter-rotating fan provided in an embodiment of the present disclosure;

[0016] Figure 6 is a structural schematic diagram of a first air guide portion of a counter-rotating fan provided by an embodiment of the present disclosure;

[0017] Figure 7 is another structural schematic diagram of a counter-rotating fan provided by an embodiment of the present disclosure;

[0018] Figure 8 is another structural schematic diagram of a counter-rotating fan provided by an embodiment of the present disclosure;

[0019] Figure 9 2 is another structural schematic diagram of the counter-rotating fan provided in an embodiment of the present disclosure.

[0020] Reference numerals:

[0021] 10. Casing; 101. Groove; 20. Hub; 30. First blade; 40. Second blade; 50. Inner cylinder; 501. First guide portion; 60. Cap; 70. Guide blade. DETAILED DESCRIPTION

[0022] In order to be able to understand the features and technical content of the embodiments of the present disclosure in more detail, the implementation of the embodiments of the present disclosure is described in detail below in conjunction with the accompanying drawings. The accompanying drawings are for reference only and are not used to limit the embodiments of the present disclosure. In the following technical description, for the sake of convenience of explanation, a full understanding of the disclosed embodiments is provided through multiple details. However, one or more embodiments can still be implemented without these details. In other cases, to simplify the drawings, well-known structures and devices can be simplified for display.

[0023] like Figure 1 and Figure 2 As shown, an embodiment of the present disclosure provides a counter-rotating fan, comprising a hub 20, provided with a first blade 30, and a casing 10, which is covered by a cover and has a groove 101 provided on its inner wall at a position corresponding to the tip of the first blade 30. The tip of the first blade 30 is the radial edge or top edge of the first blade 30 when rotating, and the outer portion of the first blade 30 is the space outside the rotational coverage area of the first blade 30. The formation of noise is related to the degree of compression of the air in the gap between the blade tip and the casing. When the first blade 30 rotates, the vortex velocity of the airflow in the gap between the blade tip and the casing is too high, thereby generating a relatively sharp noise. The groove 101 provided on the inner wall of the casing 10 corresponds to the position of the tip of the first blade 30. When the first blade 30 rotates, due to the presence of the groove, the vortex velocity of the airflow in the gap between the blade tip and the casing is reduced to a certain extent when passing through the groove. Furthermore, the provision of the groove helps alleviate the blockage problem of the gap between the blade tip and the casing, increasing the flow area of the airflow in the gap, thereby reducing the noise during the operation of the counter-rotating fan.

[0024] Among them, when the vortex airflow passes through the groove 101, the airflow flows in and out of the groove 101. When the airflow flows into the groove 101, the vortex airflow impacts the inner wall of the groove 101. The inner wall of the groove 101 absorbs part of the impact force brought by the airflow, thereby reducing the flow rate of the vortex airflow, and then reducing the noise generated by the airflow; the airflow flows out under the guidance of the inner wall of the groove 101. At this time, the uniformity of the outflowing airflow is significantly improved compared to the inflowing airflow. After the vortex airflow continuously flows through multiple grooves 101, the impact force carried by the airflow due to the vortex is buffered and absorbed by the groove 101.

[0025] In some embodiments, the grooves 101 are distributed along the inner circumference of the casing 10. When airflow passing through the blade tips generates a vortex, the vortex airflow can flow directly into the grooves 101 on the inner wall of the casing 10. The grooves 101 absorb and buffer the impact of the airflow, thereby reducing the aerodynamic noise generated by the airflow directly hitting the inner wall of the casing 10.

[0026] In some embodiments, the groove 101 is a continuous annular structure along the inner circumference of the casing 10. The continuous annular groove 101 is easy to process. Secondly, when the airflow is buffered in the groove 101, the airflow in the annular groove 101 can maintain a certain uniformity, which is beneficial to improving the stability of the casing 10.

[0027] In some embodiments, the grooves 101 are discontinuous annular structures along the inner circumference of the casing 10. That is, a plurality of grooves 101 are arranged at intervals to form an annular structure, which helps to improve the mechanical strength of the casing 10 when the grooves 101 buffer the impact of airflow.

[0028] The grooves 101 can be parallel to the radial direction of the inner circumference of the casing 10, or can form a certain angle with the radial direction of the inner circumference of the casing 10. The airflow forming the vortex has a wide range of flow directions and flows in multiple directions. The grooves 101 are arranged at multiple angles on the inner wall of the casing 10 to help maximize the buffering of the vortex airflow and reduce aerodynamic noise.

[0029] In some embodiments, the grooves 101 are arranged in multiple rows and spaced apart along the length of the casing 10, such as Figure 2 As shown, multiple rows of grooves 101 are evenly distributed on the inner circumferential surface of the casing 10. The rows of grooves 101 are arranged along the longitudinal direction of the casing 10, i.e., the axial direction of the hub 20. Thus, when airflow passes between the casing 10 and the blade tips, it sequentially passes through the multiple rows of grooves 101, with vortices in the airflow continuously flowing into and out of the grooves 101. After being buffered by the multiple rows of grooves 101, the vortices in the airflow are buffered and diluted, reducing the vibration caused by the vortices and the resulting aerodynamic noise.

[0030] In some embodiments, the greater the distance D between the blade tip and the inner wall of the casing 10, the greater the spacing L between the grooves 101. When the distance D between the blade tip and the inner wall of the casing 10 is greater, increasing the spacing between the grooves 101 not only absorbs the buffer airflow, but also reduces the number of grooves, thereby ensuring the mechanical strength of the casing 10.

[0031] In some embodiments, the spacing of the grooves 101 satisfies the following relationship: D≤L≤2D, where L represents the spacing between the grooves 101, and D represents the distance between the blade tip and the inner wall of the casing 10. By requiring D≤L≤2D, it is ensured that the airflow of the first blade 30 is buffered by the grooves 101, and the purpose of the grooves 101 absorbing the buffered airflow is achieved to the greatest extent possible. While ensuring the mechanical strength of the casing 10, the vortex generated by the first blade 30 and the inner wall of the casing 10 is absorbed by the grooves 101, effectively reducing the aerodynamic noise when the first blade 30 rotates. If the spacing L of the grooves 101 is greater than 2D, that is, the spacing between adjacent grooves 101 is relatively too large, when the vortex airflow flows through the gap between the blade tip and the inner wall of the casing 10, there is a defect that the airflow does not pass through the grooves 101 for buffering, but directly acts on the inner wall of the casing 10, thereby generating aerodynamic noise. If the spacing L of the grooves 101 is less than D, although the vortex airflow is fully buffered by the grooves 101, providing more grooves 101 within the same distance on the inner wall of the casing 10 is not conducive to maintaining the mechanical strength of the casing 10, thereby affecting the overall performance of the counter-rotating fan.

[0032] In some embodiments, the cross-section of the groove 101 is semicircular. The semicircular shape of the groove 101 maximizes its opening area to receive the vortex airflow generated by the rotation of the first blade 30. The depth of the semicircular shape ensures that the groove 101 absorbs and buffers the vortex airflow. The semicircular shape of the groove 101 facilitates machining and helps ensure the mechanical strength of the casing 10.

[0033] In some embodiments, the cross section of the groove 101 may also be square, triangular or in the shape of a minor arc. Grooves 101 of these shapes can also absorb vortices to a certain extent and reduce the aerodynamic noise of the counter-rotating fan. Among them, when the cross section of the groove 101 is square, the square groove can be tilted, and the side wall of the groove forms a certain angle with the inner wall of the casing. This helps to smooth the in and out of the airflow. Figure 3 shown

[0034] In some embodiments, the larger the distance D between the blade tip and the inner wall of the casing 10, the larger the radius of the groove 101. A larger distance between the blade tip and the inner wall of the casing 10 increases the amount of airflow passing through, and a larger radius of the groove 101 helps the groove 101 absorb and buffer vortices.

[0035] In some embodiments, the radius of the groove 101 satisfies the following relationship: 3D≤R≤5D, where R represents the radius of the groove 101 and D represents the distance between the blade tip and the inner wall of the casing 10. The requirement of 3D≤R≤5D ensures that the groove 101 can absorb and buffer the airflow as the distance between the blade tip and the inner wall of the casing 10 increases, thereby increasing the amount of airflow passing through.

[0036] In some embodiments, the distance between the furthest-spaced grooves 101 is less than the blade width. Airflow flowing through the grooves 101 is absorbed and buffered by the grooves 101, reducing the airflow rate. By configuring the blade width to be greater than the distance between the furthest-spaced grooves 101, a portion of the airflow generated by the first blade 30 merges with the airflow buffered by the grooves 101 and is discharged, resolving the issue of reduced airflow and insufficient air delivery distance. The first blade 30 generates a portion of the airflow, i.e., the airflow that is not buffered by the grooves 101.

[0037] In some embodiments, as Figure 4 and Figure 5 As shown, the counter-rotating fan further includes: a second blade 40, which is arranged on the hub 20 and on one side of the first blade 30, and the blade length is shorter than the blade length of the first blade 30; an inner cylinder 50, which is arranged between the casing 10 and the hub 20, and is covered on the outside of the second blade 40.

[0038] The first blade 30 and the second blade 40 are sequentially arranged in the axial direction of the hub 20, and the lengths of the first and second blades 40 are different. The inner cylinder 50 is arranged outside the second blade 40. When the airflow passes through the first blade 30, it passes through the flow channel surrounded by the casing 10. When the airflow passes through the second blade 40, the airflow is divided by the inner cylinder 50, one part passes through the inside of the inner cylinder 50, and the other part passes through the flow channel between the inner cylinder 50 and the casing 10. The airflow sent out from the inner cylinder 50 has a longer air supply distance, and the airflow sent out between the casing 10 and the inner cylinder 50 has a shorter air supply distance, so that the counter-rotating fan can take into account both long-distance air supply and short-distance air supply.

[0039] In some embodiments, the outlet side of the casing 10 includes a converging section with a contraction angle α, where 0°≤α≤30°. The converging section on the outlet side of the casing 10 helps converge the airflow, enhancing the airflow concentration and quality of the outlet air. By varying the contraction angle, the counter-rotating fan can achieve different air delivery distances to meet various needs. Furthermore, by varying the inclination angle of the converging section on the outlet side of the casing 10, air delivery at different angles can also be achieved.

[0040] The disclosed embodiment also provides another structure of a counter-rotating fan.

[0041] The counter-rotating fan includes a casing 10 and a hub 20 disposed inside the casing 10. A first blade 30 and a second blade 40 are sequentially disposed along the axial direction of the hub 20. The length of the second blade 40 is shorter than that of the first blade 30. Figure 4 shown.

[0042] Regarding the embodiments of the first blade 30 and the second blade 40 , reference may be made to the above description and will not be repeated here.

[0043] In some embodiments, the counter-rotating fan further includes an inner cylinder 50 disposed inside the casing 10 and covered outside the second blades 40. Figure 5 shown.

[0044] The inner barrel 50 is coaxially arranged with the casing 10 .

[0045] The diameter of the inner cylinder 50 is larger than the diameter of the area enclosed by the rotation of the second blades 40 , and smaller than the diameter of the area enclosed by the rotation of the first blades 30 .

[0046] Regarding the embodiment of the inner cylinder 50 , reference may be made to the above description and will not be repeated here.

[0047] In some embodiments, a recessed groove (not shown) is provided on the inner wall of the inner cylinder 50 at a position corresponding to the tip of the second blade 40. The tip of the second blade 40 is the radial edge or top edge of the second blade 40 as it rotates. The recessed groove, provided on the inner wall of the inner cylinder 50, corresponds to the tip of the second blade 40. When the second blade 40 rotates, airflow passing over the tip of the second blade 40 generates a vortex, which is absorbed and buffered by the recessed groove, thereby reducing aerodynamic noise generated by the counter-rotating fan.

[0048] Among them, when the vortex airflow passes through the sink trough, the airflow flows in and out of the sink trough. When the airflow flows into the sink trough, the vortex airflow hits the inner wall of the sink trough, and the inner wall of the sink trough absorbs part of the impact force brought by the airflow, thereby reducing the noise caused by the vibration generated when the vortex airflow directly acts on the inner wall of the inner cylinder 50; the airflow flows out under the guidance of the inner wall of the sink trough, and the uniformity of the outflowing airflow at this time is significantly improved compared to the inflowing airflow. After the vortex airflow continuously flows through multiple sinks, the impact force carried by the airflow due to the vortex is buffered and absorbed by the sink, eliminating the aerodynamic noise generated by the operation of the counter-rotating fan.

[0049] In some embodiments, the grooves are distributed along the inner circumference of the inner barrel 50. When airflow passing through the tips of the second blades 40 generates a vortex, the vortex airflow can flow directly into the grooves on the inner wall of the inner barrel 50. The grooves absorb and buffer the impact of the airflow, reducing the aerodynamic noise generated by the airflow directly hitting the inner wall of the inner barrel 50.

[0050] In some embodiments, multiple rows of grooves are arranged at intervals along the length of the inner barrel 50. The rows of grooves are evenly distributed along the inner circumferential surface of the inner barrel 50; along the length of the inner barrel 50, i.e., the axial direction of the hub 20, the rows of grooves are arranged along the axial direction of the hub 20. Thus, when airflow passes between the inner barrel 50 and the tip of the second blade 40, it sequentially passes through the multiple rows of grooves, with vortices in the airflow continuously flowing in and out of the grooves. After being buffered by the multiple rows of grooves, the vortices in the airflow are buffered and diluted, reducing the vibration caused by the vortices and the resulting aerodynamic noise.

[0051] In some embodiments, the dimensions of the casing 10, the inner barrel 50, and the hub 20 satisfy the following relationship: k = (D1 2 -D2 2 ) / (d1 2 -d2 2 ), wherein D1 is the inner diameter of the casing 10, D2 is the outer diameter of the inner tube 50, d1 is the inner diameter of the inner tube 50, d2 is the outer diameter of the hub 20, and 0.5≤k≤1.

[0052] The dimensional relationship between the casing 10, inner barrel 50, and hub 20 helps ensure a certain airflow rate. Secondly, during the airflow process, the overall pressure is maintained appropriately, reducing aerodynamic noise during operation and ensuring the mechanical strength of the counter-rotating fan. If k < 0.5, the airflow rate decreases; if k > 1, the airflow rate increases, but the overall pressure increases, which is detrimental to the stability of the counter-rotating fan.

[0053] In some embodiments, as Figure 5 and Figure 6 As shown, a first air guide portion 501 is provided on the windward side of the outer wall of the inner tube 50 , and the first air guide portion 501 is arc-shaped.

[0054] When the airflow on the windward side acts perpendicularly on the outer wall of the inner cylinder 50, backflow will be generated, which will cause airflow turbulence and flow separation, and have an adverse effect on the performance of the counter-rotating fan; by providing a first guide portion 501 on the windward side of the outer wall of the inner cylinder 50, and the first guide portion 501 is an arc-shaped structure, it helps to avoid the airflow on the windward side acting perpendicularly on the outer wall of the inner cylinder 50, and the airflow is guided by the arc-shaped first guide portion 501 to make the airflow transition smoothly.

[0055] In some embodiments, the greater the height h1 of the first air guide portion 501 , the greater the width b1 .

[0056] The greater the height and width of the first air guide portion 501 , the greater the guide angle is, which helps to make the airflow transition smoother and avoid backflow as much as possible.

[0057] In some embodiments, the height and width of the first guide portion 501 satisfy the following relationship: 1 / 3≤h1 / b1≤1 / 2, where h1 is the height of the first guide portion 501 and b1 is the width of the first guide portion 501 .

[0058] When 1 / 3≤h1 / b1≤1 / 2, the first air guide portion 501 can guide the airflow to transition smoothly to the greatest extent possible, thereby avoiding the backflow problem.

[0059] Optionally, the height h1 of the first air guide portion 501 ranges from 8 mm to 12 mm.

[0060] When the height h1 of the first air guide portion 501 is in the range of 8 mm to 12 mm, the stability of the inner cylinder 50 is ensured on the one hand, and the airflow guiding effect is ensured on the other hand.

[0061] In some embodiments, the inner wall of the air outlet of the casing 10 is provided with a second air guide portion (not shown in the figure), and the second air guide portion is arc-shaped.

[0062] The second guide portion provided on the inner wall of the air outlet of the casing 10 helps guide the direction of the outgoing airflow, expands the radiation range of the airflow, improves the quality of the outgoing air, and enhances the comfort of the air supply. The curved structure of the second guide portion helps to smoothly transition the airflow and avoid aerodynamic noise.

[0063] In some embodiments, the greater the height h2 of the second air guide portion, the greater the width b2.

[0064] The greater the height and width of the second air guide portion, the greater the guide angle is, which helps to make the airflow transition smoother and improve the air quality.

[0065] In some embodiments, the height and width of the second guide portion satisfy the following relationship: 1 / 3≤h2 / b2≤1 / 2, where h2 is the height of the second guide portion, and b2 is the width of the second guide portion.

[0066] When 1 / 3≤h2 / b2≤1 / 2, the second air guide portion can guide the airflow to transition smoothly to the maximum extent, expand the radiation range of the airflow, and reduce the impact force of the airflow.

[0067] In some embodiments, the first blade 30 is closer to the air inlet of the casing 10 than the second blade 40 .

[0068] The length of the first blade 30 is greater than that of the second blade 40. A larger airflow is generated by the first blade 30 and transferred to the second blade 40. The second blade 40 further utilizes the airflow generated by the first blade 30, thereby achieving the purpose of a two-stage fan. If the second blade 40 is closer to the air inlet of the casing 10, there is a risk that the large airflow generated by the rotation of the first blade 30 and the airflow generated by the rotation of the second blade 40 will be turbulent, or the large airflow generated by the rotation of the first blade 30 will directly cover the airflow generated by the rotation of the second blade 40, resulting in a waste of the second blade 40, and thus failing to achieve the purpose of a counter-rotating fan.

[0069] The disclosed embodiment also provides another structure of a counter-rotating fan.

[0070] like Figure 7 and Figure 8 As shown, the counter-rotating fan includes a hub 20 and first blades 30 , and further includes a cap 60 , which is conical and disposed on the windward end surface of the hub 20 to guide the airflow to the first blades 30 .

[0071] The airflow at the inlet of the counter-rotating fan is guided by the cap 60 to ensure the uniformity of the airflow at the inlet of the counter-rotating fan, reduce the anti-separation ability of the airflow in the counter-rotating fan, thereby increasing the flow rate and pressure of the counter-rotating fan and improving the overall performance of the counter-rotating fan.

[0072] The cap 60 is coaxially arranged with the wheel hub 20 .

[0073] In some embodiments, the cap 60 is curved and disposed on the windward end surface of the hub 20 to guide the airflow toward the first blades 30. The curved outer surface of the cap 60 improves the uniformity of the airflow entering the counter-rotating fan inlet, making the airflow more uniform upon entering the counter-rotating fan and reducing unusual noise.

[0074] In some embodiments, as Figure 9 As shown, a guide vane 70 is provided on the windward end surface, and the rotation direction of the guide vane 70 is the same as the rotation direction of the first blade 30 .

[0075] By providing the guide blades 70, the uniformity of the airflow entering the counter-rotating fan is further improved; the rotation direction of the guide blades 70 is the same as the rotation direction of the first blades 30, avoiding the occurrence of airflow turbulence while ensuring that the airflow flow is not lost.

[0076] The guide vanes 70 are positioned on the conical surface of the cap 60. The vertical distance between the apex of the cap 60 and the nearest point of the guide vanes 70 is greater than 0.3 times the height of the cap 60, and the vertical distance between the apex of the cap 60 and the farthest point of the guide vanes 70 is less than 0.8 times the height of the cap 60. This distance between the guide vanes 70 and the apex of the cap 60 helps maintain the stability of the counter-rotating fan as airflow enters it, while also improving airflow uniformity.

[0077] In some embodiments, two sets of guide blades 70 are provided on the windward end surface. The two sets of guide blades 70 rotate in the same direction, and the diameters of the areas enclosed by the two sets of guide blades 70 are different. The set of guide blades 70 with the smaller diameter is closer to the air inlet side of the cap 60. The two sets of guide blades 70 further reduce the impact of the airflow entering the counter-rotating fan, thereby improving the overall performance of the counter-rotating fan.

[0078] In some embodiments, the trailing edge of the guide vane 70 is disposed corresponding to the leading edge of the first vane 30 .

[0079] The trailing edge of the guide vane 70 is the windward end surface of the guide vane 70 , and the leading edge of the first blade 30 is the windward end surface of the first blade 30 .

[0080] The trailing edge of the guide vane 70 corresponds to the leading edge of the first blade 30, so that the airflow transitions directly from the guide vane 70 to the first blade 30, reducing airflow loss, avoiding airflow vibration between the guide vane 70 and the first blade 30, and reducing noise.

[0081] In some embodiments, the trailing edge of the guide vane 70 may correspond to the front half of the windward side of the first blade 30. In this way, the airflow, guided by the trailing edge of the guide vane 70, directly enters the windward side of the first blade 30, eliminating the step of guiding the airflow by the leading edge of the first blade 30. This prevents the trailing edge of the guide vane 70 from misaligning with the leading edge of the first blade 30, preventing the airflow from being guided to the leeward side of the first blade 30 by the guide vane 70, resulting in an uneven airflow transition.

[0082] In some embodiments, the outlet airflow angle of the guide vane 70 and the inlet airflow angle of the first blade 30 satisfy the following relationship: 0°≤|β1-β2|≤10°, where β1 represents the outlet airflow angle of the guide vane 70 and β2 represents the inlet airflow angle of the first blade 30 .

[0083] By meeting the requirement of 0°≤|β1-β2|≤10°, on the one hand, the stability and uniformity of the airflow from the guide vane 70 to the first blade 30 are ensured, and on the other hand, the airflow loss is reduced, and the airflow is prevented from impacting the first blade 30 and generating aerodynamic noise.

[0084] In some embodiments, the inlet airflow angle of the guide vane 70 ranges from 10° to 15°.

[0085] By setting the inlet guide angle of the guide blade 70 within 10° to 15°, it is ensured that the guide blade 70 guides the external airflow smoothly into the counter-rotating fan, and then guides the airflow to the first blade 30 through the guide blade 70, preventing the external airflow from being turbulent when entering the counter-rotating fan, thereby improving the uniformity of the airflow entering the counter-rotating fan.

[0086] In some embodiments, the diameter of the area enclosed by the guide vanes 70 is smaller than the diameter of the hub 20 .

[0087] The diameter of the area enclosed by the guide blades 70 is smaller than the diameter of the hub 20, that is, the highest point of the guide blades 70 is lower than the lowest point of the first blades 30. This helps to fully utilize the surface of the first blades 30, allowing the airflow to flow from the guide blades 70 into the first blades 30, ensuring a smooth transition of airflow. If the diameter of the area enclosed by the guide blades 70 is larger than the diameter of the hub 20, that is, there is an overlapping gap between the area enclosed by the rotation of the guide blades 70 and the area enclosed by the rotation of the first blades 30, when the airflow guided by the guide blades 70 overflows into the overlapping gap, it will cause airflow turbulence and may also cause aerodynamic noise, affecting the performance of the counter-rotating fan.

[0088] In some embodiments, the number of blades of the guide vanes 70 is the same as the number of blades of the first blades 30 .

[0089] The number of blades of the guide blades 70 is the same as the number of blades of the first blades 30 , which further ensures that the airflow transitions smoothly and evenly from the guide blades 70 to the first blades 30 .

[0090] In some embodiments, the radius and height of the cap 60 satisfy the following relationship: 0.86≤r3 / h3≤1.15, where r3 represents the radius of the cap 60 and h3 represents the height of the cap 60.

[0091] By satisfying the condition of 0.86≤r3 / h3≤1.15, the uniformity of the airflow at the inlet of the counter-rotating fan is improved, thereby improving the performance of the counter-rotating fan and improving the air supply quality of the counter-rotating fan.

[0092] The radius of the cap 60 is consistent with the radius of the hub 20, and the height of the cap 60 depends on the size of other equipment in the counter-rotating fan. Under the condition of ensuring that the conditions are met, the greater the height of the cap 60, the more uniform the inlet wind.

[0093] In some embodiments, the counter-rotating fan further includes a second blade 40 disposed on one side of the first blade 30 and having a width smaller than that of the first blade 30 .

[0094] The rotation of the first blade 30 and the second blade 40 generates a pressure equivalent to that of a two-stage fan. The first blade 30 and the second blade 40 can rotate at the same / different speeds / directions, thereby realizing multiple air supply modes such as forward, reverse, long-distance, and non-sensing, thereby improving the flexibility of air supply.

[0095] The disclosed embodiments further provide an air conditioner comprising the counter-rotating fan provided by any of the aforementioned embodiments. During cooling or heating, the air conditioner has the advantage of low aerodynamic noise, increasing user comfort, and providing both long-range and short-range air delivery options, ensuring effective air delivery and enhancing air delivery comfort, thereby improving overall air conditioner performance.

[0096] The above description and accompanying drawings sufficiently illustrate the embodiments of the present disclosure to enable those skilled in the art to practice them. Other embodiments may include structural and other changes. The embodiments represent only possible variations. Unless expressly required, individual components and functions are optional, and the order of operation may vary. Portions and features of some embodiments may be included in or substituted for portions and features of other embodiments. The scope of the embodiments of the present disclosure includes the entire scope of the claims and all available equivalents of the claims. When used in this application, although the terms "first," "second," etc. may be used in this application to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element can be called a second element, and similarly, a second element can be called a first element, without changing the meaning of the description, as long as all occurrences of "first element" are consistently renamed and all occurrences of "second element" are consistently renamed. The first element and the second element are both elements, but they may not be the same element. Furthermore, the terms used in this application are only used to describe the embodiments and are not used to limit the claims. As used in the description of the embodiments and claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include the plural forms as well. Similarly, the term "and / or" as used in this application refers to any and all possible combinations of one or more of the associated listings. In addition, when used in this application, the term "comprise" and its variations "comprises" and / or comprising refer to the presence of stated features, wholes, and / or components, but do not exclude the presence or addition of one or more other features, wholes, components and / or groups of these. Without further restriction, an element defined by the sentence "comprising a..." does not exclude the presence of other identical elements in the process, method or apparatus that includes the element. In this article, each embodiment may focus on the differences from other embodiments, and the same and similar parts between the embodiments can be referred to each other. For the methods, products, etc. disclosed in the embodiments, if they correspond to the method part disclosed in the embodiments, then the relevant parts can be referred to the description of the method part.

[0097] The terms "longitudinal", "transverse", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like used herein to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings are intended only for the convenience of describing this document and simplifying the description, and are not intended to indicate or imply that the devices or components referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as limiting the present invention. In the description herein, unless otherwise specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, they can refer to mechanical or electrical connections, or to the internal communication between two components, or to direct connection or indirect connection through an intermediate medium. A person of ordinary skill in the art can understand the specific meanings of the above terms according to the specific circumstances. In this document, unless otherwise specified, the term "plurality" means two or more. In this document, the term "and / or" is a description of an association relationship between objects, indicating that three relationships can exist. For example, A and / or B means: A or B, or A and B.

Claims

1. A counter-rotating fan comprising a casing and a hub disposed inside the casing, characterized in that: A first blade and a second blade are sequentially arranged along the axial direction of the hub, wherein the length of the second blade is shorter than that of the first blade; An inner cylinder is arranged inside the casing and covered on the outside of the second blade; The dimensions of the casing, the inner barrel, and the hub satisfy the following relationship: k=(D1 2 -D2 2 ) / (d1 2 -d2 2 ), Wherein, D1 is the inner diameter of the casing, D2 is the outer diameter of the inner cylinder, d1 is the inner diameter of the inner cylinder, d2 is the outer diameter of the hub, and 0.5≤k≤1.

2. The counter-rotating fan according to claim 1, wherein A first air guide portion is provided on the windward side of the outer wall of the inner cylinder, and the first air guide portion is arc-shaped.

3. The counter-rotating fan according to claim 2, wherein: The larger the height h1 of the first air guide portion is, the larger the width b1 is.

4. The counter-rotating fan according to any one of claims 1 to 3, characterized in that: The inner wall of the air outlet of the casing is provided with a second air guide portion, and the second air guide portion is arc-shaped.

5. The counter-rotating fan according to claim 4, wherein: The larger the height h2 of the second air guide portion is, the larger the width b2 is.

6. The counter-rotating fan according to any one of claims 1 to 5, characterized in that: The first blade is closer to the air inlet of the casing than the second blade.

7. An air conditioner, characterized in that: It comprises the counter-rotating fan according to any one of claims 1 to 6.

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