Fan impeller with turbulance-reducing blades

Abstract

A fan impeller, including: a hub; an annular structure positioned radially outward of the hub and defining a peripheral surface lying in a first plane; and a plurality of blades extending radially between the hub and the annular structure, each blade having a main surface lying in a second plane that is perpendicular to the first plane, wherein each of the plurality of blades includes an edge region proximate the annular structure, the edge region tapering to define an inclination angle between a top edge and a bottom edge of the blade, the inclination angle being configured to reduce turbulence during operation. Each of the plurality of blades may additionally define a slot formed through the main surface of the blade, the slot being configured to interrupt turbulent boundary layer growth towards a trailing edge of the respective blade.

Description

BACKGROUND

[0001] Laptop cooling fans are important components in the thermal management of high-performance notebook computers. As laptops continue to evolve, their cooling requirements have become increasingly demanding due to rising power consumption and more restrictive design constraints. Modern laptops consume more power at both the system-on-chip (SoC) and overall system levels, driven by the need to enhance user experience through improved performance and functionality.

[0002] At the same time, users expect laptops to be thinner, quieter, and cooler. Meeting these expectations requires fan systems capable of delivering improved pressure-flow (P-Q) characteristics while maintaining low acoustic noise and fitting within increasingly slim form factors. In conventional radial blowers, air entering the impeller is directed toward the backplate, with a substantial portion of the airflow exiting near the lower section adjacent to the backplate. This localized outflow contributes to increased turbulence and elevated noise levels in that region.

[0003] Historically, blower blade tips have been designed with surfaces oriented perpendicular to adjoining structures to maximize the airflow sweep area. In some instances, small flanges have been added to the upper and lower surfaces of the blade tips to reduce noise. These features have occasionally been implemented using metal blades; however, blower fans with metal components are not widely adopted due to higher manufacturing costs, lower production yields, and marginal performance benefits, especially in light of recent advancements in thin plastic molding technologies, which now allow for sub-0.1 mm features with comparable or improved aerodynamic performance.BRIEF DESCRIPTION OF THE FIGURES

[0004] FIG. 1A illustrates a conventional fan assembly integrated into an electronic device.

[0005] FIG. 1B illustrates a detailed view of a conventional fan assembly.

[0006] FIG. 2A illustrates a fan impeller with blades including an inclination angle designed to reduce turbulence and noise during operation, in accordance with aspects of the disclosure.

[0007] FIG. 2B is a close-up view of the inclined edge region of the blades in the impeller of FIG. 2A, in accordance with aspects of the disclosure.

[0008] FIGS. 3A-3D illustrate an impeller incorporating a slotted blade profile and a support ring, in accordance with aspects of the disclosure.

[0009] FIG. 4 illustrates an impeller 400 incorporating a slotted blade profile with an extended annular structure, in accordance with aspects of the disclosure.

[0010] FIGS. 5A-5C illustrate simulation and performance results of a fan module incorporating aspects of the disclosure.DETAILED DESCRIPTION

[0011] This disclosure is directed to an impeller that reduces noise generation in the bottom section of a fan assembly and at the trailing edges of its blades, thereby minimizing overall acoustic noise. The aerodynamic characteristics of the impeller design allow the fan assembly to operate at higher rotational speeds without a corresponding increase in noise, resulting in enhanced performance, specifically, higher pressure-flow (P-Q) output, while maintaining the same noise level.I. Conventional Fan Assembly

[0012] FIG. 1A illustrates an electronic device 100 with a conventional fan assembly 10. The fan assembly 10 includes an impeller 11 and a cover 12. The impeller 11 is configured to rotate within the fan assembly 10, generating airflow for cooling purposes. The cover 12 encloses the impeller 11 and directs the airflow generated by the impeller 11 toward specific components of the electronic device 100 that require cooling.

[0013] The fan assembly 10, in this example, is part of a dual-fan cooling system within the electronic device 100. Each fan assembly 10 is positioned to optimize airflow distribution across the internal components of the electronic device 100, such as processors, memory modules, and other heat-generating elements.

[0014] The electronic device 100 may be a laptop, notebook, or other computing device that requires efficient thermal management in a compact form factor. The fan assembly 10 is configured to operate within the constraints of such devices, providing enhanced cooling performance without increasing noise levels or requiring additional space.

[0015] FIG. 1B illustrates a detailed view of a conventional fan assembly 10. The fan assembly 10 includes the impeller 11 surrounded by a volute housing 16. The impeller 11 comprises a plurality of blades 13 that are radially arranged around a central axis. The blades 13 are connected to an annular structure 14 and are positioned above a backplate 15 within a volute housing 16. The backplate 15 is a surface within the fan assembly housing that serves as a structural boundary and influences airflow dynamics during fan operation. The volute housing 16 is the enclosure that surrounds the impeller 11, directing the airflow generated by the impeller 11 toward specific components that require cooling. It includes features such as a cutwater 17 to guide airflow efficiently. The cutwater 17, which is not shown in this figure, is a feature within the volute housing 16 that directs airflow generated by the impeller 11, typically positioned to optimize the distribution of air exiting the impeller 11.

[0016] Airflow through the impeller 11 is directed radially outward, moving from the inner region near the hub to the outer region near the annular structure 14. Air is drawn into the impeller 11 from the top due to the negative pressure created at the center when the impeller rotates, typically in a counterclockwise direction. As the impeller 11 rotates, centrifugal force pushes the air outward through the channels formed between the blades 13. This radial airflow pattern ensures efficient air movement, with the negative pressure at the center facilitating continuous intake and the centrifugal force driving the air outward for effective cooling or ventilation.II. Impeller in Accordance With Aspects of the Disclosure

[0017] The disclosed impeller design enables the fan assembly to deliver improved pressure-flow (P-Q) characteristics while reducing noise, all while maintaining compatibility with existing manufacturing processes and cost constraints. The blades of the impeller include an inclination angle relative to the backplate 15. This inclination angle reduces turbulence and noise generation by directing airflow more smoothly toward the backplate 15 and increasing the air gap between the impeller and the volute housing 16. Each blade may additionally or alternatively include a slot that is configured to interrupt turbulent boundary layer growth, reduce tip vortices, and promote flow reattachment, thereby further reducing noise.III. Impeller with Blades Including Inclination Angles

[0018] FIG. 2A illustrates an impeller 200A with blades 213, each including an inclination angle 220 designed to reduce turbulence and noise during operation, in accordance with aspects of the disclosure. The impeller 200A includes a hub 217 at its center, an annular structure 214 positioned radially outward of the hub 217, and a plurality of blades 213 extending radially between the hub 217 and the annular structure 214. The annular structure 214 defines a peripheral surface that lies in a first plane, while the main surface of each blade 213 lies in a second plane that is substantially perpendicular to the first plane.

[0019] Each blade 213 includes an edge region proximate the annular structure 214, the edge region being tapered to define an inclination angle 220 between the blade's top and bottom edges. Unlike conventional impellers in which the edge region is vertical, forming a 90-degree angle with the backplate or annular structure 214, this tapered configuration forms an acute angle (less than 90 degrees) relative to the horizontal reference plane. The inclination angle 220 reduces the normal component of air velocity (Vn=impeller tip radius×fan speed) near the bottom of the blade 213, thereby decreasing the relative air exit velocity in that region. This reduction in relative velocity minimizes turbulence and, consequently, lowers noise levels during operation. The inclined geometry not only enhances acoustic performance but also improves the overall aerodynamic efficiency of the impeller.

[0020] The inclination angle 220 also increases the air gap between the impeller 200A and the volute housing in the region near the backplate. This increased air gap reduces the interaction between the airflow exiting the impeller and the volute housing, further decreasing turbulence and broadband noise. The edge region of each blade 213 terminates at the peripheral surface of the annular structure 214, ensuring structural integrity and smooth airflow distribution.

[0021] FIG. 2B provides a close-up view of the inclined edge region of the blades 213 in the impeller 200B. The figure highlights the tapering of the edge region, which defines the inclination angle 220. This inclination angle 220 is acute and preferably ranges from approximately 45 to 85 degrees. The inclination angle 220 of the edge region is designed to optimize airflow dynamics by reducing turbulence at the blade tips, a common source of noise in conventional impellers. The annular structure 214 is shown in greater detail, demonstrating its role in supporting the blades 213 and maintaining the overall stability of the impeller 200B during operation.

[0022] The inclination angle 220 of the edge region also disrupts the formation of eddies and local recirculation at the blade tips, which are significant contributors to turbulence and noise in conventional fan designs. By replacing the vertical 90-degree edge with an inclined edge, the impeller 200 achieves smoother airflow and reduced noise levels, reducing the need for additional components or modifications to the manufacturing process.IV. Impeller With Blades Including SlotsA. Slots With Support Structure

[0023] FIGS. 3A-3D illustrate an impeller 300 incorporating blades defining slots 310 configured to reduce turbulence and noise during fan operation. The slots 310 are formed through the main surface of each blade 313. A support structure 330, such as a support ring, maintains the mechanical stability of the impeller 300. The slots 310 and support structure 330 work together to disrupt turbulent boundary layer growth near the trailing edge of the blades 313, thereby improving aerodynamic performance and reducing broadband noise.

[0024] FIG. 3A is an isometric view of the impeller 300A, showing the overall configuration of the blades 313, the annular structure 214, and the slots 310. Each blade 313 defines a slot 310 formed through its main surface, positioned near the trailing edge of the blade. The slots 310 are configured to interrupt turbulent boundary layer growth as air flows along the blade surface. By disrupting the boundary layer, the slots 310 reduce turbulence and promote flow reattachment near the trailing edge, thereby minimizing noise and improving aerodynamic efficiency. The annular structure 214 provides structural support for the blades 313 and ensures uniform airflow distribution.

[0025] FIG. 3B provides a detailed view of the impeller 300B, highlighting the slotted blade profile and the support ring 330. The slots 310 are shown as openings formed through the main surface of each blade 313, positioned proximate to the support ring 330. The support ring 330 is positioned between the hub 217 and the annular structure 214 and is coupled to the blades 313. The support ring 330 is configured to maintain the structural continuity of the blades 313, ensuring that the slotted blade profile does not compromise the mechanical stability of the impeller during high-speed operation. The slots 310, in conjunction with the support ring 330, allow for effective disruption of boundary layer growth while maintaining the overall integrity of the impeller.

[0026] FIG. 3C provides a close-up view of the slotted blade profile in the impeller 300C. The figure shows the slots 310 in greater detail, demonstrating how they are formed through the main surface of each blade 313. The slots 310 are positioned near the trailing edge of the blades 313 and are configured to reduce turbulence by interrupting the low-velocity boundary layer that forms during operation. This configuration ensures that the slots 310 are integrated into the overall structure of the impeller 300C, providing both aerodynamic benefits and mechanical stability. The width of each slot 310 may be designed to fall within a range of approximately 0.4 millimeters to 0.7 millimeters, ensuring optimal disruption of the boundary layer without compromising the structural integrity of the blades 313.

[0027] FIG. 3D provides a back view of the impeller 300D, showing the arrangement of the blades 313, the annular structure 214, and the support ring 330. Again, the support ring 330 provides additional stability to the slotted blade profile.

[0028] The slotted blade profile, as shown in FIGS. 3A-3D, is particularly advantageous for use in compact fan assemblies, such as those found in laptops or other portable electronic devices. By incorporating the slots 310, the support ring 330, and the extended annular structure 214, the impeller 300A-300D achieves improved pressure-flow characteristics, reduced turbulence, and lower noise levels, enabling higher fan speeds and better cooling performance while maintaining compatibility with existing manufacturing techniques.B. Slots With Extended Annular Structure

[0029] FIG. 4 illustrates a detailed perspective view of an impeller 400 incorporating a slotted blade profile with an extended annular structure 420, in accordance with aspects of the disclosure. The impeller 400 includes a plurality of blades 413 extending radially outward from the hub, and an annular structure 214 positioned radially outward of the blades 413. Each blade 413 defines a slot 410 formed through its main surface, positioned near the trailing edge of the blade 413. The slots 410 are configured to interrupt turbulent boundary layer growth along the blade surface, thereby reducing turbulence, tip vortices, and broadband noise during operation.

[0030] A distinctive aspect is the extension of the annular structure 214, that is, the extended annular structure 420, into the slots 410. The extended annular structure 420 partially bounds the slots 410, providing additional structural support and ensuring the slots 410 are securely integrated into the impeller design. This configuration enhances the mechanical stability of the blades 413 while maintaining the aerodynamic benefits of the slotted blade profile. By extending into the slots 410, the extended annular structure 420 also helps guide airflow through the impeller 400, further improving pressure-flow characteristics and reducing noise.

[0031] The slots 410 are designed with a width optimized to balance aerodynamic performance and structural integrity. Specifically, the width of each slot 410 may range from approximately 0.4 millimeters to 0.7 millimeters. This range is sufficient to effectively disrupt the boundary layer while ensuring that the blades 413 remain structurally robust during high-speed operation.

[0032] The slot design illustrated in FIGS. 3A-3D, and / or the slot design illustrated in FIG. 4, operates independently of the inclination angle described with respect to FIGS. 2A-2B, providing a distinct aerodynamic improvement that does not rely on the inclined blade edge. In the slot design, the primary mechanism for reducing turbulence and noise is the interruption of turbulent boundary layer growth near the trailing edge of the blades through the incorporation of slots formed through the main surface of each blade. These slots disrupt the low-velocity boundary layer, reduce tip vortices, and promote flow reattachment, thereby minimizing turbulence and broadband noise. The aerodynamic benefits of the slot design are achieved solely through the placement and configuration of the slots 310 / 410, as well as the structural support provided by the support ring 230 or the extended annular structure 240, along with the annular structure 214. Unlike the inclination angle 220, which modifies the blade geometry to reduce turbulence near the backplate, the slot design focuses on managing airflow along the blade surface itself. As such, the slot design can be implemented independently of the inclination angle 220, allowing for flexibility in impeller configurations while still achieving significant noise reduction.V. Simulation Results

[0033] FIGS. 5A-5C illustrate simulation and performance results of a fan arrangement incorporating aspects of the disclosure. These figures demonstrate the acoustics and acoustic benefits of the inclination angle and slot features, both individually and in combination, as well as their impact on fan noise reduction.

[0034] FIG. 5A shows a comparison 500A of the ⅓rd octave band Fast Fourier Transform (FFT) results at a fan speed of 4500 rpm, with and without the inclination angle 220 of FIGS. 2A-2B. The aeroacoustic simulations indicate that the inclusion of the inclination angle 220 results in up to a 9 dBA reduction in individual frequency bands, leading to an overall reduction of 5.1 dBA in the Overall Sound Pressure Level (OSPL). This significant reduction in broadband noise validates the hypothesis that the inclination angle 220 reduces turbulence near the backplate by decreasing the relative air exit velocity and increasing the air gap between the impeller and the volute housing. The results confirm that the inclination angle 220 is highly effective in minimizing noise.

[0035] FIG. 5B illustrates a comparison 500B of the ⅓rd Octave Band FFT results at 4500 rpm for a fan arrangement incorporating both an impeller with the inclination angle 220 of FIGS. 2A-2B, in addition to the slots 310 of FIGS. 3A-3D or the slots 410 of FIG. 4. The aeroacoustic simulations show that the addition of the slot feature further reduces noise, with up to a 6 dBA reduction in individual frequency bands and an overall reduction of 2.9 dBA in the OSPL. The slot feature disrupts turbulent boundary layer growth near the trailing edge of the blades, reducing tip vortices and promoting flow reattachment. The combined effect of the inclination angle and the slot feature results in a significant reduction in broadband noise, demonstrating the complementary nature of these two features in improving fan acoustic performance.

[0036] FIG. 5C shows test data 500C comparing the ⅓rd octave band FFT results at 3300 rpm for a conventional impeller and the disclosed impeller 200 with inclination angle 220 arrangement. The disclosed impeller 200 achieves a significant reduction in broadband noise, with a lower overall sound pressure level (OSPL) across a wide range of operating conditions. This improvement results from the combined effects of the inclination angle 220, which reduces turbulence near the backplate.

[0037] The techniques described in this disclosure may also be illustrated in the following examples.

[0038] Example 1. A fan impeller, comprising: a hub; an annular structure positioned radially outward of the hub and defining a peripheral surface lying in a first plane; and a plurality of blades extending radially between the hub and the annular structure, each blade having a main surface lying in a second plane that is perpendicular to the first plane, wherein each of the plurality of blades includes an edge region proximate the annular structure, the edge region tapering to define an inclination angle between a top edge and a bottom edge of the blade, the inclination angle being configured to reduce turbulence during operation.

[0039] Example 2. The fan impeller of example 1, wherein the edge region terminates at the peripheral surface of the annular structure.

[0040] Example 3. The fan impeller of any one or more of examples 1-2, wherein the inclination angle is acute.

[0041] Example 4. The fan impeller of any one or more of examples 1-3, wherein the inclination angle is in a range from approximately 45 to 85 degrees.

[0042] Example 5. The fan impeller of any one or more of examples 1-4, wherein each of the plurality of blades defines a slot formed through the main surface of the blade, the slot being configured to interrupt turbulent boundary layer growth towards a trailing edge of the respective blade.

[0043] Example 6. The fan impeller of example 5, further comprising: a support ring extending between the hub and the annular structure and coupled to the plurality of blades, wherein the slots are formed proximate the support ring, and the support ring is configured to maintain structural continuity of the blades.

[0044] Example 7. The fan impeller of example 5, wherein the annular structure extends into the slots such that the slots are at least partially bounded by the annular structure.

[0045] Example 8. The fan impeller of example 5, wherein each of the slots has a width in a range from approximately 0.4 millimeters to 0.7 millimeters.

[0046] Example 9. The fan impeller of any one or more of examples 1-8, wherein the annular structure comprises a peripheral ring and is configured to connect of the plurality of blades.

[0047] Example 10. A fan, comprising: a volute housing including a backplate; and the fan impeller of any one or more of examples 1-9 rotatably mounted within the volute housing, wherein the inclination angle is configured to reduce turbulence near a backplate during rotation of the fan impeller.

[0048] Example 11. An electronic device comprising the fan of example 10.

[0049] Example 12. A fan impeller, comprising: a hub; an annular structure positioned radially outward of the hub and defining a peripheral surface lying in a first plane; and a plurality of blades extending radially between the hub and the annular structure, each blade having a main surface lying in a second plane that is perpendicular to the first plane, wherein each of the plurality of blades defines a slot formed through the main surface of the blade, the slot being configured to interrupt turbulent boundary layer growth towards a trailing edge of the respective blade.

[0050] Example 13. The fan impeller of example 12, further comprising: a support structure positioned between the hub and the annular structure and coupled to the plurality of blades, wherein the slots are formed proximate the support structure, and the support structure is configured to maintain structural continuity of the blades.

[0051] Example 14. The fan impeller of example 13, wherein the support structure comprises a ring.

[0052] Example 15. The fan impeller of any one or more of examples 12-14, wherein the annular structure extends into the slots and the slots are at least partially bounded by the annular structure.

[0053] Example 16. The fan impeller of any one or more of examples 12-15, wherein each of the slots has a width in a range from approximately 0.4 millimeters to 0.7 millimeters.

[0054] Example 17. A fan assembly, comprising: a volute housing including a backplate; and the fan impeller of example 12 rotatably mounted within the volute housing.

[0055] Example 18. An electronic device comprising the fan assembly of example 17.

[0056] While the foregoing has been described in conjunction with exemplary aspects, it is understood that the term “exemplary” is merely meant as an example, rather than the best or optimal. Accordingly, the disclosure is intended to cover alternatives, modifications, and equivalents, which may be included within the scope of the disclosure.

[0057] Although specific aspects have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that a variety of alternate and / or equivalent implementations may be substituted for the specific aspects shown and described without departing from the scope of the present application. This application is intended to cover any adaptations or variations of the specific aspects discussed herein.

Claims

1. A fan impeller, comprising:a hub;an annular structure positioned radially outward of the hub and defining a peripheral surface lying in a first plane; anda plurality of blades extending radially between the hub and the annular structure, each blade having a main surface lying in a second plane that is perpendicular to the first plane,wherein each of the plurality of blades includes an edge region proximate the annular structure, the edge region tapering to define an inclination angle between a top edge and a bottom edge of the blade, the inclination angle being configured to reduce turbulence during operation.

2. The fan impeller of claim 1, wherein the edge region terminates at the peripheral surface of the annular structure.

3. The fan impeller of claim 1, wherein the inclination angle is acute.

4. The fan impeller of claim 1, wherein the inclination angle is in a range from approximately 45 to 85 degrees.

5. The fan impeller of claim 1, wherein each of the plurality of blades defines a slot formed through the main surface of the blade, the slot being configured to interrupt turbulent boundary layer growth towards a trailing edge of the respective blade.

6. The fan impeller of claim 5, further comprising:a support ring extending between the hub and the annular structure and coupled to the plurality of blades,wherein the slots are formed proximate the support ring, and the support ring is configured to maintain structural continuity of the blades.

7. The fan impeller of claim 5, wherein the annular structure extends into the slots such that the slots are at least partially bounded by the annular structure.

8. The fan impeller of claim 5, wherein each of the slots has a width in a range from approximately 0.4 millimeters to 0.7 millimeters.

9. The fan impeller of claim 1, wherein the annular structure comprises a peripheral ring and is configured to connect of the plurality of blades.

10. A fan, comprising:a volute housing including a backplate; andthe fan impeller of claim 1 rotatably mounted within the volute housing,wherein the inclination angle is configured to reduce turbulence near a backplate during rotation of the fan impeller.

11. An electronic device comprising the fan of claim 10.

12. A fan impeller, comprising:a hub;an annular structure positioned radially outward of the hub and defining a peripheral surface lying in a first plane; anda plurality of blades extending radially between the hub and the annular structure, each blade having a main surface lying in a second plane that is perpendicular to the first plane,wherein each of the plurality of blades defines a slot formed through the main surface of the blade, the slot being configured to interrupt turbulent boundary layer growth towards a trailing edge of the respective blade.

13. The fan impeller of claim 12, further comprising:a support structure positioned between the hub and the annular structure and coupled to the plurality of blades,wherein the slots are formed proximate the support structure, and the support structure is configured to maintain structural continuity of the blades.

14. The fan impeller of claim 13, wherein the support structure comprises a ring.

15. The fan impeller of claim 12, wherein the annular structure extends into the slots and the slots are at least partially bounded by the annular structure.

16. The fan impeller of claim 12, wherein each of the slots has a width in a range from approximately 0.4 millimeters to 0.7 millimeters.

17. A fan assembly, comprising:a volute housing including a backplate; andthe fan impeller of claim 12 rotatably mounted within the volute housing.

18. An electronic device comprising the fan assembly of claim 17.

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