A bidirectional fan

Abstract

This utility model relates to a bidirectional fan, belonging to the field of air conditioning technology. It includes fan blades and a motor. The motor includes a drive shaft capable of outputting forward and reverse rotational drive. The fan blades include a hub connected to the drive shaft and multiple blades evenly distributed around the hub. Each blade has an inner end fixedly connected to the hub and an outer end away from the hub. The blade is an integrally formed plate-like structure with a cross-sectional profile having an S-shaped bidirectional twisted surface symmetrical about the vertical axis where the midpoint is located. The blade has an inclined angle α relative to the front end face of the hub, where 39° ≤ α ≤ 45°. The inner chord length of the blade is smaller than its outer chord length, and the overall shape gradually expands radially along the hub. The leading edge line of the blade extends in an upward-sloping arc from the inner end to the outer end along the spanwise direction, and the trailing edge line extends in a downward-sloping arc from the inner end to the outer end along the spanwise direction. Using the above technical solution, airflow separation is effectively suppressed, aerodynamic efficiency and airflow balance are improved, and vortex noise is reduced.

Description

Technical Field

[0001] This utility model belongs to the field of air conditioning technology, and in particular relates to a bidirectional fan. Background Technology

[0002] Two-way fans, as a type of ventilation device that can switch the direction of air intake and exhaust according to usage needs, are widely used in indoor fresh air exchange, bathroom and kitchen exhaust, industrial ventilation, and electronic equipment heat dissipation.

[0003] Currently, most existing bidirectional fan blades are designed for unidirectional air output, employing a conventional arc-shaped blade structure, typically only suitable for unidirectional motor operation. When bidirectional operation is required on the same motor, the existing unidirectional fan blades exhibit a significant decrease in airflow and a marked increase in noise during reverse operation. This is because the airfoil of conventional fan blades is optimized for aerodynamic characteristics in a single direction of rotation; under reverse operation, the blade angle of attack deviates significantly from its optimal value, resulting in a substantial reduction in aerodynamic efficiency.

[0004] To address this issue, existing technologies have developed bidirectional fans employing S-shaped blades, such as the bidirectional fan blade disclosed in CN2658440Y, whose blades consist of an S-shaped structure composed of two symmetrical arcs of opposite directions. While these S-shaped blades improve the imbalance of airflow between forward and reverse directions to some extent, their design is relatively simple, merely combining two arcs in opposite directions without refined aerodynamic design. For example, key aerodynamic parameters such as the blade cross-sectional profile, the sweep direction of the leading and trailing edges, the chord length distribution of the blades in the spanwise direction, and the blade tilt angle lack optimization. This results in poor airflow matching between the airflow and the blades under both forward and reverse rotation conditions, limited airflow improvement, and the airflow easily separates and forms vortices on the blade surface, leading to still significant wind noise. Furthermore, existing S-shaped blades have a relatively simple spanwise structure; the orientation of their leading and trailing edges is not specially designed, causing drastic changes in the angle of attack of the airflow at various cross-sections along the spanwise direction during blade rotation, further exacerbating energy loss and noise. Utility Model Content

[0005] In summary, to overcome the shortcomings of the prior art, this utility model provides a bidirectional fan to solve the technical problems of unbalanced airflow and high noise when bidirectional fans run in both forward and reverse directions, and achieves the technical effect of high airflow and low noise when running in both forward and reverse directions.

[0006] To achieve the above objectives, this utility model provides the following technical solution: a bidirectional fan, comprising fan blades and a motor, the motor comprising a drive shaft capable of outputting forward and reverse rotation drive, the fan blade comprising a hub connected to the drive shaft and a plurality of blades evenly distributed around the hub, the blade comprising an inner end fixedly connected to the hub and an outer end away from the hub, the blade being an integrally formed plate-like structure, its cross-sectional profile having an S-shaped bidirectional twisted surface with the vertical axis at the midpoint as the center of symmetry, the blade having an inclined angle α relative to the front end face of the hub, wherein 39°≤ α ≤ 45°; the inner end chord length of the blade is less than its outer end chord length, and the overall shape is radially expanding along the hub; the leading edge line of the blade extends in an upward inclined arc from the inner end to the outer end along the spanwise direction, and the trailing edge line of the blade extends in a downward inclined arc from the inner end to the outer end along the spanwise direction.

[0007] By adopting the above technical solution, and by setting an S-shaped bidirectional twisted surface symmetrical about the vertical axis at the midpoint on the blade cross-section profile, combined with an inclination angle α of 39° to 45°, the blade can maintain a near-optimal angle of attack for both forward and reverse rotation, effectively suppressing airflow separation and significantly improving aerodynamic efficiency and airflow balance. The blade adopts a radially expanding configuration with a short inner chord and a long outer chord, combined with a specific spatial orientation where the leading edge convexes upward and the trailing edge convex downward, optimizing the flow field distribution along the spanwise direction and significantly reducing vortex noise. This integrated plate structure not only takes into account the stability and quietness of forward and reverse operation, but also has a simple molding process, making it easy to mass-produce.

[0008] The present invention further specifies that the range of the included tilt angle α is 42°≤a≤43°.

[0009] By adopting the above technical solution, precise matching of airflow angle of attack under forward and reverse operating conditions is achieved. When the included angle is adjusted to 42°-43°, the wind speed in both forward and reverse directions is significantly improved, and the wind noise is only "slight", which is significantly better than other angles. This angle range effectively balances the lift and drag of the blades, so that the airflow can maintain efficient adhesion flow in both directions, reducing eddy shedding and boundary layer separation. Thus, while ensuring a large air volume, the operating noise is suppressed to the greatest extent, improving the overall performance and user experience of the bidirectional fan.

[0010] The present invention further comprises: the S-shaped bidirectional twisted surface is composed of an upper wing section and a lower wing section, and the airfoil spanwise of the upper wing section and the lower wing section are symmetrically distributed along the central axis of the central section.

[0011] By adopting the above technical solution, the aerodynamic differences under forward and reverse rotation conditions are eliminated geometrically. This symmetrical structure ensures that the relative velocity, pressure distribution, and angle of attack of the airflow over the upper and lower blade surfaces are highly consistent when the blade rotates forward and backward. This spanwise symmetrical design ensures that the leading edge of the blade always maintains the optimal windward attitude when rotating in both directions, effectively suppressing the separation of airflow on the suction and pressure surfaces and reducing vibration and vortex noise caused by asymmetrical forces. This structure is easy to mold and ensure precision during manufacturing, improving product consistency and significantly enhancing the operational stability and quietness of the bidirectional fan under different rotation directions.

[0012] The present invention is further configured such that: the leading edge of the upper wing sweeps forward relative to its trailing edge, and the leading edge of the lower wing sweeps backward relative to its trailing edge, and the upper wing and the lower wing form a continuous and smooth curved surface.

[0013] By adopting the above technical solutions, this sweeping design can effectively guide the airflow to adhere and flow orderly along the blade surface during both forward and reverse rotation, avoiding local airflow impact and separation, and significantly reducing pressure drag and vortex intensity. During forward rotation, the upper section sweeps forward to guide the airflow to accelerate smoothly, while during reverse rotation, the lower section sweeps backward to maintain the stability of the suction surface, thus achieving efficient aerodynamic conversion in both rotational directions. The continuous and smooth curved surface transition eliminates the flow interference caused by structural abrupt changes, further suppressing boundary layer separation and wake vortex shedding, effectively reducing wind noise and improving wind pressure stability. This structure results in a more gradual change in the angle of attack at each cross section along the span, reducing energy loss along the path, enabling the fan to obtain a more balanced airflow and lower operating noise under both forward and reverse rotation conditions.

[0014] The present invention further comprises: an inner end inclined line at the inner end of the blade, the inner end inclined line being a connecting line from the leading edge to the trailing edge of the inner end of the blade; an outer end inclined line at the outer end of the blade, the outer end inclined line being a connecting line from the leading edge to the trailing edge of the outer end of the blade; and an included angle b between the inner end inclined line and the outer end inclined line, wherein 8° ≤ b ≤ 11°.

[0015] By adopting the above technical solution, fine-grained torsional control of the blades along the span is achieved. This angle design creates a reasonable phase difference between the inner and outer ends of the blade in the circumferential projection, ensuring that each section from the blade root to the blade tip can maintain a near-optimal airflow angle of attack during both forward and reverse rotation of the motor. This effectively suppresses flow separation caused by differences in the spanwise velocity gradient. Compared with traditional fan blades without torsional control, this specific angle range can ensure airflow adhesion in the low tangential velocity zone at the root and optimize the aerodynamic load distribution in the high linear velocity zone at the tip, significantly reducing the tip vortex intensity and secondary flow loss. The torsional gradient of 8° to 11° avoids severe deflection of the airflow between the leading and trailing edges, further reducing turbulent noise and enabling the fan to achieve higher total pressure efficiency and better quiet performance in both forward and reverse operation.

[0016] The present invention further comprises: the leading edge line of the blade is inclined in an outward arc shape from the inner end to the outer end along the span, and its curvature gradually increases along the span; the trailing edge line of the blade is inclined in an outward arc shape from the inner end to the outer end along the span, and its curvature gradually increases along the span.

[0017] By adopting the above technical solution, both the leading and trailing edges of the blade are designed as outwardly convex arcs oriented along the spanwise direction from the inner end to the outer end, with the curvature gradually increasing from the root to the tip, thus achieving progressive guidance of the spanwise airflow. This variable curvature design conforms to the linear increase in linear velocity from the inside to the outside during blade rotation, ensuring that the leading edge maintains an approximately orthogonal inflow attitude at each radius position, effectively reducing airflow impact losses. The synchronous increase in trailing edge curvature optimizes the airflow convergence angle between the pressure and suction surfaces, reducing the size and intensity of the wake vortex. This coordinated bending of the leading and trailing edges not only suppresses airflow leakage and vortex shedding at the blade tip but also significantly reduces high-frequency noise caused by flow separation. Combined with the S-shaped bidirectional twisted surface and the tilt angle, this structure further enhances the aerodynamic symmetry under both forward and reverse rotation conditions, enabling the fan to maintain stable operation characteristics of high airflow and low wind noise across the entire speed range.

[0018] The present invention further includes an outer cover and a base. The base includes a hollow outer shell and a base disposed within the outer shell. The outer shell forms a working cavity for accommodating the blades and the motor. The base is disposed at the rear end of the working cavity and has a receiving cavity with a front opening. The motor is disposed within the receiving cavity and is detachably connected to the base via a connector. The outer shell and the base are connected by two or more connecting parts.

[0019] By adopting the above technical solution, a base with a receiving cavity is integrated into the outer shell, and the motor is placed in this cavity and detachably connected to the base. This achieves precise axial positioning and stable support for the motor, effectively suppressing radial runout and axial movement during forward and reverse switching. The outer shell and the base are connected by two or more equidistant connecting parts, which not only form a stable cage-like support frame, ensuring the structural strength and concentricity of the working chamber, but also act as guide ribs when airflow passes through, reducing turbulence.

[0020] The present invention is further provided that the connecting part is perpendicular to the rear end face of the outer shell at a 90° angle.

[0021] By adopting the above technical solution, the connecting part is set perpendicularly to the rear end face of the outer shell at 90°, so that the inner sidewall of the connecting part forms a guide surface that extends straight along the axis. Under the conditions of forward exhaust or reverse air intake, this vertical guide surface can effectively constrain the airflow trajectory flowing through the rear end of the outer shell, avoiding the generation of radial velocity due to the tilt of the connecting part, thereby reducing the deflection and vortex generation of airflow in the cavity. This smooth axial guide effect significantly reduces the flow separation phenomenon of airflow around the motor and base, so that both forward and reverse airflow are discharged or drawn in through a low-resistance, low-disturbance path. At the same time, the vertical structure is subjected to symmetrical force under the action of bidirectional airflow, and is not prone to the generation of local high-pressure areas or backflow areas caused by asymmetrical guide flow, further suppressing turbulent noise and ensuring that the fan has excellent aeroacoustic performance and airflow stability when running in both forward and reverse directions.

[0022] The present invention further includes: the base also includes a base plate disposed at the front end of the outer shell, a louvered fan assembly and a wax motor that is activated and deactivated by an electric current induction are disposed between the base plate and the outer cover, the base plate includes a mounting frame for mounting the louvered fan assembly, the mounting frame is provided with a gas channel communicating with the working chamber, the louvered fan assembly includes a plurality of louvers arranged in parallel and spaced within the mounting frame, the two sides of the louvers are respectively provided with a rotating shaft rotatably connected to the mounting frame, the wax motor includes an output rod that can extend and retract axially, the output rod is connected to a pull rod, the pull rod is connected to the rotating shaft of each louver through a linkage, so as to convert the axial linear motion of the output rod into the synchronous oscillation of the louvers, thereby adjusting the opening and closing angle.

[0023] By adopting the above technical solution, the louver fan assembly and wax motor are integrated between the base plate and the outer cover. The wax motor automatically drives the output rod to extend and retract axially when heated, and the linear motion is synchronously transmitted to the rotation axis of each louver through the pull rod and linkage, realizing intelligent and automated control of louver opening and closing. In this structure, the gas channel in the mounting frame is directly connected to the working chamber, ensuring smooth airflow in both forward and reverse operation modes, avoiding increased wind resistance caused by structural obstruction. Multiple louvers are arranged in parallel and spaced apart, and can achieve synchronous and uniform swing in conjunction with the linkage mechanism. They can be fully opened in high-volume mode to reduce flow resistance, and can be completely closed in shutdown or anti-backflow mode to improve sealing performance. The wax motor is driven by the thermal effect of current, without the need for a complex electronic control system. It has a stable and reliable response and has an automatic reset function after power failure, which significantly improves the safety of use. The overall structure is compact and the transmission is simple, reducing the number of parts and assembly complexity, effectively reducing manufacturing costs, while taking into account the ventilation efficiency, dust and insect prevention, and quiet operation requirements of bidirectional fans.

[0024] The specific embodiments of this utility model are described below with reference to the accompanying drawings and examples. Attached Figure Description

[0025] Figure 1 This is a partial side view of an embodiment of the present utility model.

[0026] Figure 2 This is a partial cross-sectional view of the fan blade according to an embodiment of the present utility model.

[0027] Figure 3 This is a perspective view of the fan blades according to an embodiment of the present utility model.

[0028] Figure 4 This is a front view of the fan blade according to an embodiment of the present utility model.

[0029] Figure 5 Side view of the fan blade in an embodiment of this utility model Figure 1 .

[0030] Figure 6 Side view of the fan blade in an embodiment of this utility model Figure 2 .

[0031] Figure 7 This is a partial three-dimensional structure of an embodiment of the present utility model. Figure 1 .

[0032] Figure 8 This is a partial structural front view of an embodiment of the present utility model.

[0033] Figure 9 This is a partial three-dimensional structure of an embodiment of the present utility model. Figure 2 .

[0034] Figure 10 This is a perspective view of an embodiment of the present utility model.

[0035] Reference numerals: 1. Fan blade, 11. Hub, 12. Blade, 121. Inner end, 122. Outer end, 123. Upper wing section, 124. Lower wing section, 125. Inner end inclined line, 126. Outer end inclined line, 2. Motor, 21. Drive shaft, 3. Outer cover, 4. Base, 41. Housing, 411. Working chamber, 42. Base, 421. Receiving chamber, 43. Connecting part, 44. Base plate, 441. Mounting frame, 442. Gas passage, 5. Louvered fan assembly, 51. Louvered part, 511. Rotating shaft, 52. Linkage component, 6. Wax motor, 61. Output rod, 7. Pull rod. Detailed Implementation

[0036] This specific embodiment is merely an explanation of the present utility model and is not intended to limit the present utility model. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but as long as they are within the scope of the claims of the present utility model, they are protected by patent law.

[0037] See appendix Figure 1-6 This application discloses a bidirectional fan, including fan blades 1 and a motor 2. The motor 2 includes a drive shaft 21 capable of outputting forward and reverse rotational drive. The fan blades 1 include a hub 11 connected to the drive shaft 21 and a plurality of blades 12 evenly distributed around the hub 11. Each blade 12 includes an inner end 121 fixedly connected to the hub 11 and an outer end 122 away from the hub 11. Each blade 12 is an integrally formed plate-like structure with a cross-sectional profile having an S-shaped bidirectional twisted surface centered on the vertical axis where the midpoint is located. The blade 12 has an inclined angle α relative to the front end face of the hub 11, where 39° ≤ α ≤ 1. 45°; the inner end 121 of the blade 12 has a chord length that is less than that of its outer end 122, and the blade as a whole is radially expanding along the hub 11; the leading edge line of the blade 12 extends in an upwardly inclined arc from the inner end 121 to the outer end 122 along the spanwise direction, and the trailing edge line of the blade 12 extends in a downwardly inclined arc from the inner end 121 to the outer end 122 along the spanwise direction.

[0038] In some embodiments, the leading edge of the blade 12 has an inclined angle θ1 with the front end face of the hub 11, wherein 2°≤θ1≤ 8°, preferably 3°≤θ1≤ 6°; the trailing edge of the blade 12 has an inclined angle θ2 with the rear end face of the hub 11, wherein 2°≤θ2≤ 8°, preferably 3°≤θ2≤ 6°.

[0039] In this utility model, the working principle of the bidirectional fan is as follows: the motor 2 drives the hub 11 and its multiple blades 12 to rotate through the drive shaft 21. When motor 2 rotates in the forward direction, the upper part of the S-shaped bidirectional twisted surface of blade 12 acts as the main action surface to propel the air. When motor 2 rotates in the reverse direction, the lower part of the S-shaped surface of the same blade 12 becomes the main action surface. Since the S-shaped surface is symmetrical about the vertical axis at the midpoint, the angle of attack and separation characteristics of the airflow acting on blade 12 in both directions of rotation are highly similar, thus achieving a basic balance of airflow in both directions. At the same time, the setting of the tilt angle α allows blade 12 to cut into the airflow at a better angle when rotating, reducing flow loss. The gradually expanding chord design from the inner end 121 to the outer end 122 of blade 12, together with the specific upward and downward convex arc extensions of the leading edge and trailing edge, guides the airflow to flow more smoothly and stably along the spanwise direction of blade 12, effectively suppressing the generation of vortices and spanwise secondary flows at the blade tip of blade 12. Thus, while increasing bidirectional airflow, aerodynamic noise is significantly reduced.

[0040] In one embodiment, for the aforementioned blade 12, the tilt angle α can be 39°, 40°, 41°, 42°, 43°, 44°, or 45°, with the preferred value range being 42° ≤ α ≤ 43°. This angle range is the optimal angle of attack range obtained through fluid simulation and experimental optimization. Within this range, the aerodynamic efficiency of the blade 12 reaches its peak during both forward and reverse rotation, allowing the airflow to adhere more tightly to the surface of the blade 12, reducing flow separation and energy dissipation caused by improper angle of attack. This further optimizes the noise spectrum while ensuring high airflow, resulting in a lower and smoother operating sound.

[0041] In one embodiment, the aforementioned S-shaped bidirectional twisted surface is composed of an upper wing section 123 and a lower wing section 124. The spanwise directions of the upper wing section 123 and the lower wing section 124 are symmetrically distributed along the central axis of the central section. This symmetrical distribution is the core of ensuring bidirectional wind force balance. It allows the blade 12 to form two "aerodynamic surfaces" with opposite directions but equal efficiency in space. Regardless of the rotation direction of the drive shaft 21 of the motor 2, the airflow can be effectively accelerated and guided by an optimized surface, thereby fundamentally solving the problem of large performance differences between forward and reverse rotation of the traditional fan blade 1. As a specific implementation, the upper wing section 123 and the lower wing section 124 have opposite bending characteristics of equal size and opposite direction, together constituting the S-shaped bidirectional twisted surface.

[0042] In one embodiment, regarding the aforementioned upper wing section 123 and lower wing section 124, the leading edge of the upper wing section 123 sweeps forward relative to its trailing edge, and the leading edge of the lower wing section 124 sweeps backward relative to its trailing edge. The upper wing section 123 and the lower wing section 124 form a continuous and smooth curved surface. The forward sweep of the upper wing section 123 and the backward sweep of the lower wing section 124 conform to the different mainstream directions during forward and reverse rotation. This "forward-sweep-backward" combination allows the airflow to be more smoothly introduced when impacting the leading edge of the blade 12 and to remain attached as it flows over the curved surface, greatly reducing the flow separation zone. The continuous and smooth curved surface transition ensures that the airflow does not undergo a drastic change in direction when flowing from one wing section to another, thereby reducing the intensity of local turbulence and the resulting howling sound.

[0043] In one embodiment, the inner end 121 of the blade 12 is provided with an inner end tilt line 125, which is a connecting line from the leading edge to the trailing edge of the inner end 121 of the blade 12; the outer end 122 of the blade 12 is provided with an outer end tilt line 126, which is a connecting line from the leading edge to the trailing edge of the outer end 122 of the blade 12; there is an included angle b between the inner end tilt line 125 and the outer end tilt line 126, where 8° ≤ b ≤ 11°, preferably 9° or 10°, and the included angle b defines the overall torsional angle of the blade 12 from the inner end 121 to the outer end 122. A reasonable torsional angle allows each section of the blade 12 along the spanwise direction to operate under conditions close to the design angle of attack, thereby optimizing the load distribution of the entire blade 12, improving aerodynamic efficiency, and effectively reducing blade flutter and broadband noise caused by uneven spanwise stress.

[0044] In some embodiments, the leading edge of the blade 12 is inclined in an outwardly convex arc shape from the inner end 121 to the outer end 122 along the spanwise direction, with its curvature gradually increasing along the spanwise direction; the trailing edge of the blade 12 is also inclined in an outwardly convex arc shape from the inner end 121 to the outer end 122 along the spanwise direction, with its curvature gradually increasing along the spanwise direction. The gradual increase in curvature of the leading and trailing edges along the spanwise direction means that the blade 12 is more curved in the outer end 122 region. This design enables the outer end 122 of the high-speed rotating blade 12 to generate stronger guiding and centrifugal ejection effects, compensating for the insufficient pressurization capacity in the inner end 121 region. At the same time, the gradual curvature provides a smooth transition from gentle to abrupt, guiding the airflow velocity to increase gradually, avoiding drastic changes in flow velocity and airflow separation caused by abrupt changes in geometry, thereby effectively suppressing the generation of high-frequency vortex shedding noise while improving overall wind pressure and airflow.

[0045] As a specific implementation, the leading edge and trailing edge form a smooth transition structure from the inner end 121, which curves more gently towards the outer end 122.

[0046] See appendix Figure 7-10 In one embodiment, the bidirectional fan further includes an outer cover 3 and a base 4. The base 4 includes a hollow outer shell 41 and a base 42 disposed within the outer shell 41. The outer shell 41 forms a working cavity 411 for accommodating the blades 12 and the motor 2. The base 42 is disposed at the rear end of the working cavity 411 and has a receiving cavity 421 with a front opening. The motor 2 is disposed within the receiving cavity 421 and detachably connected to the base 42 via a connector. The outer shell 41 and the base 42 are connected by two or more equidistant connecting parts 43. (The connectors are not shown in the figure.) In this utility model, the outer shell 41 forms the outer shell and duct boundary of the whole machine. Its inner wall plays a role in regulating and guiding the airflow, reducing turbulence and air volume loss. The base 42, as the core load-bearing structure, provides a stable and centered mounting base for the motor 2, ensuring the stability of the rotation axis of the drive shaft 21, thereby ensuring the dynamic balance of the blade 12 rotation and further reducing the noise generated by mechanical vibration transmitted to the outer shell 41. The equidistantly distributed connecting parts 43 uniformly bear the connection force and vibration between the outer shell 41 and the base 42 in the circumferential direction, ensuring the uniformity of the overall structural rigidity and preventing abnormal noise caused by deformation of the outer shell 41 under negative pressure due to insufficient local rigidity. At the same time, the gap between the connecting parts 43 can serve as an auxiliary airflow channel, which helps to balance the air pressure in the front and rear parts of the working chamber 411 and promotes smooth airflow transition.

[0047] As a specific implementation, the bottom of the base 42 is provided with a connection hole for fixing the motor 2. The motor 2 is set in the receiving cavity 421 and is detachably connected to the base 42 by bolts or other connecting parts, which facilitates maintenance and replacement.

[0048] In one embodiment, the aforementioned connecting portion 43 is arranged perpendicularly to the rear end face of the housing 41 at a 90° angle. The perpendicularly arranged connecting portion 43 provides the most direct force transmission path, has a simple structure and high rigidity. This arrangement can most effectively resist the axial thrust generated by the rotation of the blade 12 and evenly transmit the load to the housing 41, avoiding unnecessary bending moments and stress concentrations that may be caused by the diagonal bracing, thus improving the long-term reliability of the structure.

[0049] In one embodiment, the base 4 further includes a base plate 44 disposed at the front end of the outer casing 41. A louvered fan assembly 5 and a wax motor 6 that is activated and deactivated by an electric current sensor are disposed between the base plate 44 and the outer cover 3. The base plate 44 includes a mounting frame 441 for mounting the louvered fan assembly 5. A gas channel 442 communicating with the working chamber 411 is disposed in the mounting frame 441. The louvered fan assembly 5 includes a plurality of louvered elements 51 arranged in parallel and spaced apart in the mounting frame 441. Rotating shafts 511 rotatably connected to the mounting frame 441 are respectively disposed on both sides of the louvered elements 51. The wax motor 6 includes an output rod 61 that can extend and retract along the axial direction. The output rod 61 is connected to a pull rod 7. The pull rod 7 is connected to the rotating shafts 511 of each louvered element 51 through a linkage 52 to convert the axial linear motion of the output rod 61 into the synchronous oscillation of the louvered elements 51, thereby adjusting the opening and closing angle.

[0050] In this utility model, the substrate 44 constitutes the air inlet or outlet panel of the fan. The gas channel 442 on it defines the effective flow area of ​​the airflow, which can guide the airflow to concentrate and reduce the scattering and backflow loss of the airflow at the inlet or outlet, thereby improving the ventilation efficiency of the whole machine. The louvered fan assembly 5 plays the roles of air guiding, dust prevention and decoration. When the fan starts to work and the wax motor 6 is heated by power, the output rod 61 extends or retracts, and drives all the louvers 51 to rotate synchronously to the opening angle through the pull rod 7 and the linkage 52 (such as the linkage mechanism). When the fan stops working and the temperature drops, the output rod 61 moves in the opposite direction and drives the louvers 51 to close. This process realizes the automatic temperature control opening and closing of the louvered fan assembly 5.

[0051] In one embodiment, the motor 2 is a bidirectional motor 2. The motor 2, which is specifically designed for bidirectional operation, has its electromagnetic characteristics, bearing structure, and control circuit optimized for frequent forward and reverse rotation. It can achieve fast, smooth, and low-loss direction switching, and has good consistency in output characteristics in both forward and reverse rotation, as well as a longer lifespan, perfectly matching the application requirements of this bidirectional fan.

[0052] To further demonstrate the improvement of the fan blades designed in this application compared to traditional fan blades, comparative tests on airflow and wind noise were conducted. The environmental conditions for this test were: ambient temperature 22℃, ambient humidity 60%, atmospheric pressure 102 kPa, and a constant test voltage of 220.0V. The testing equipment used was a SMART SENSOR brand digital anemometer / split impeller anemometer (model: AS836), and the diameter of the air duct used was 100mm. To ensure the accuracy and reliability of the experimental data, the experiment strictly followed the single variable principle: except for the shape and tilt angle α of the fan blades under test, all other accessories remained uniform, and the fan blades were only replaced during the test. The airflow was calculated by measuring the wind speed. The airflow calculation formula is: Q = V × A × 3600, where Q is the airflow (unit: m³ / s). 3 / h), V is the wind speed (unit: m / s), and A is the effective cross-sectional area of ​​the duct.

[0053] Under the unified experimental conditions described above, items 1-4 represent different embodiments of the technical solution of this application, while items 5-6 use existing S-shaped fan blades as comparative examples. The specific test data are shown in the table below. In the description of this utility model, it should be noted that the terms "center", "front", "rear", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. The term "between" mentioned above does not only refer to the orientation or position, but also includes the interaction between different parts.

[0054] To facilitate clear understanding, the following explanations are provided for some key terms used in this application: S-shaped bidirectional twisted surface: refers to the cross-sectional profile of each blade 12 exhibiting a continuous curved shape resembling the letter "S," with the vertical axis containing the midpoint of the cross-section as the center of symmetry, resulting in highly symmetrical aerodynamic surfaces for the blade 12 during forward and reverse rotation; Upper section 123 and lower section 124: for ease of description, the portion of the S-shaped surface above the central axis of the blade 12's central cross-section is referred to as the upper section 123, and the portion below the central axis is referred to as the lower section 124. In the preferred embodiment, both are mirror-symmetrical along the central axis; Leading edge and trailing edge: the edge curve of the blade 12 that first faces the airflow in the rotational direction is called the leading edge; the edge curve of the airflow leaving the blade 12 is called the trailing edge; Inclination angle α: refers to the gap formed between the plane of the blade 12 or its centerline (such as a chord) and the front end face of the hub 11 (the plane perpendicular to the axis of rotation). Including angle; Angle b: refers to the spatial angle between the inner end inclined line 125 and the outer end inclined line 126 of the blade 12, reflecting the overall degree of twist of the blade 12 from the inner end 121 to the outer end 122; Chord length: refers to the vertical distance from a point on the leading edge line of the blade 12 to the trailing edge line, used to describe the width of the blade 12 in the direction perpendicular to the leading edge line; Span: refers to the direction from the inner end 121 of the blade 12 (near the hub 11) to the outer end 122 of the blade 12 (away from the hub 11); Inner end 121 and outer end 122 of the blade 12: the end of the blade 12 that is fixedly connected to the hub 11 is the inner end 121; the free end of the blade 12, that is, the end away from the hub 11, is the outer end 122; Connecting part 43: refers to the supporting structure that connects the outer shell 41 and the base 42, used to transmit loads and maintain the relative position between the two; Wax motor 6: refers to a temperature-controlled drive device that uses the thermal expansion and contraction characteristics of wax material to drive the output rod 61 to perform linear motion.

[0055] Although this document frequently uses terms such as fan blade 1, hub 11, blade 12, inner end 121, outer end 122, upper wing section 123, lower wing section 124, inner end inclined line 125, outer end inclined line 126, motor 2, drive shaft 21, outer cover 3, base 4, outer shell 41, working chamber 411, base 42, receiving chamber 421, connecting part 43, base plate 44, mounting frame part 441, gas channel 442, louvered fan assembly 5, louvered part 51, rotating shaft 511, linkage part 52, wax motor 6, output rod 61, and pull rod 7, the possibility of using other terms is not excluded. The use of these terms is merely for the convenience of describing and explaining the essence of this utility model; interpreting them as any kind of additional limitation would contradict the spirit of this utility model.

Claims

1. A bidirectional fan, comprising fan blades and a motor, characterized in that: The motor includes a drive shaft capable of outputting forward and reverse rotational drive. The fan blades include a hub connected to the drive shaft and a plurality of blades evenly distributed around the hub. Each blade includes an inner end fixedly connected to the hub and an outer end away from the hub. Each blade is an integrally formed plate-like structure with a cross-sectional profile having an S-shaped bidirectional twisted surface symmetrical about the vertical axis where the midpoint is located. The blade has an inclined angle α relative to the front end face of the hub, where 39° ≤ α ≤ 45°. The inner chord length of the blade is less than the outer chord length, and the blade is radially expanding along the hub. The leading edge line of the blade extends in an upward sloping arc from the inner end to the outer end along the spanwise direction, and the trailing edge line of the blade extends in a downward sloping arc from the inner end to the outer end along the spanwise direction.

2. A bidirectional fan according to claim 1, characterized in that: The range of the included tilt angle α is 42°≤a≤43°.

3. A bidirectional fan as claimed in claim 1, characterized in that: The S-shaped bidirectional twisted surface is composed of an upper wing section and a lower wing section, and the airfoil spanwise of the upper wing section and the lower wing section are symmetrically distributed along the central axis of the central section.

4. A reversible fan as claimed in claim 3, wherein: The leading edge of the upper wing sweeps forward relative to its trailing edge, and the leading edge of the lower wing sweeps backward relative to its trailing edge, forming a continuous and smooth curved surface between the upper and lower wing sections.

5. A bidirectional fan according to claim 1, characterized in that: The inner end of the blade is provided with an inner end inclined line, which is a connecting line from the leading edge to the trailing edge of the inner end of the blade; the outer end of the blade is provided with an outer end inclined line, which is a connecting line from the leading edge to the trailing edge of the outer end of the blade; there is an included angle b between the inner end inclined line and the outer end inclined line, where 8° ≤ b ≤ 11°.

6. A bidirectional fan according to claim 1, characterized in that: The leading edge of the blade is inclined in an outward arc shape from the inner end to the outer end along the span, and its curvature gradually increases along the span. The trailing edge of the blade is inclined in an outward arc shape from the inner end to the outer end along the span, and its curvature gradually increases along the span.

7. A bidirectional fan as claimed in claim 1, characterized in that: It also includes an outer cover and a base. The base includes a hollow outer shell and a base disposed within the outer shell. The outer shell forms a working cavity for accommodating the blades and the motor. The base is disposed at the rear end of the working cavity and has a receiving cavity with a front opening. The motor is disposed within the receiving cavity and is detachably connected to the base via a connector. The outer shell and the base are connected by two or more connecting parts.

8. A bidirectional fan according to claim 7, characterized in that: The connecting part is perpendicular to the rear end face of the outer shell at a 90° angle.

9. A bidirectional fan according to claim 7, characterized in that: The base also includes a base plate disposed at the front end of the outer casing. A louvered fan assembly and a wax motor that is activated and deactivated by an electric current are disposed between the base plate and the outer cover. The base plate includes a mounting frame for mounting the louvered fan assembly. A gas channel communicating with the working chamber is disposed within the mounting frame. The louvered fan assembly includes multiple louvers that are parallel and spaced apart within the mounting frame. Rotating shafts that are rotatably connected to the mounting frame are respectively disposed on both sides of each louver. The wax motor includes an output rod that can extend and retract axially. The output rod is connected to a pull rod. The pull rod is connected to the rotating shaft of each louver through a linkage to convert the axial linear motion of the output rod into the synchronous oscillation of the louvers, thereby adjusting the opening and closing angle.

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