WO2016036626A1

WO2016036626A1 - Cooling fan and device comprising the same

Info

Publication number: WO2016036626A1
Application number: PCT/US2015/047632
Authority: WO
Inventors: Gavin D. Stanley
Original assignee: Microsoft Technology Licensing, Llc
Priority date: 2014-09-03
Filing date: 2015-08-31
Publication date: 2016-03-10
Also published as: US20160061220A1

Abstract

Examples are disclosed herein that relate to fans for cooling systems. One example provides a device including an impingement surface, and a fan positioned to direct a flow of air onto the impingement surface. The fan comprises an impeller and motor assembly, and a housing comprising an inlet end, an outlet end, and a side extending at least partially between the inlet end and the outlet end. The fan further comprises a strut located to position the impeller and motor assembly relative to the housing, and an opening formed in the side of the housing, the opening comprising an upstream edge located farther from the impingement surface than a downstream edge of the housing along an axial direction of the fan.

Description

COOLING FAN AND DEVICE COMPRISING THE SAME

BACKGROUND

[0001] Cooling fans may be used in many different types of devices, including but not limited to electronic systems such as computing devices. Cooling fans may help to dissipate heat produced by a device and thus to maintain temperatures of device components.

SUMMARY

[0002] Examples are disclosed herein that relate to fans for cooling systems. One example provides a device including an impingement surface, and a fan positioned to direct a flow of air onto the impingement surface. The fan comprises an impeller and motor assembly, and a housing comprising an inlet end, an outlet end, and a side extending at least partially between the inlet end and the outlet end. The fan further comprises a strut located to position the impeller and motor assembly relative to the housing, and an opening formed in the side of the housing, the opening comprising an upstream edge located farther from the impingement surface than a downstream edge of the housing along an axial direction of the fan.

[0003] This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. Furthermore, the claimed subject matter is not limited to implementations that solve any or all disadvantages noted in any part of this disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

[0004] FIG. 1 shows a block diagram of an example device including a fan positioned to direct a flow of air onto an impingement surface.

[0005] FIG. 2 shows a perspective view of an example fan.

[0006] FIG. 3 shows a side view of the example fan of FIG. 2.

[0007] FIG. 4 shows a view of an outlet end of the example fan of FIG. 2 along an axial direction of the fan.

[0008] FIG. 5 shows a perspective view of another example fan.

[0009] FIG. 6 shows a perspective view of another example fan.

[0010] FIG. 7 shows a perspective view of another example fan.

[0011] FIG. 8 shows a schematic view of another example fan. DETAILED DESCRIPTION

[0012] Cooling fans may be located near an impingement surface of a heat transfer component (e.g. a heat sink) of a device to help move air across the impingement surface and thus dissipate heat produced by the device, as mentioned above. Cooling fans for electronic devices may be implemented in various forms, such as axial fans and centrifugal blowers. An axial fan moves air in a direction from an inlet to an outlet along an axis of rotation of the impeller of the fan, while a blower moves air in a radial and/or tangential direction relative to this axis. Blowers and axial fans may offer different performance characteristics. For example, blowers may create a higher pressure head at the same volume of airflow compared to a comparable axial fan, but also may create more acoustic noise and may occupy more space.

[0013] An axial fan may occupy less space and operate more quietly than a blower, and thus may be more suitable for use than a blower in systems where less acoustic noise is desired, such as a system with microphones. Some axial fan may take the form of box fans, where a housing encloses and supports the motor and impeller. When an axial box fan is placed into a system with limited space in an axial direction (e.g. in a direction along an axis of rotation of the fan impeller), the fan intake may be restricted by near field vent patterns, which may impede the ability of the fan to supply flow. In such a fan, the struts that connect an impeller and motor assembly of the fan to the housing may be located approximately flush with a downstream edge of the housing. This may allow the struts to be positioned within the housing such that the axial fan may be mounted flush to a wall, plenum, and/or vent without airflow recirculating from the fan outtake to the fan intake.

[0014] Instead of box fans, some axial fans may be implemented as housingless fans.

A housingless fan may reduce system impedance associated with the restriction of airflow into a housing, and thus allow more airflow compared to a comparable box fan in some use environments. However, the use of a housingless axial fan also may involve the use of fan support structures that occupy additional space compared to an axial box fan. Further, a housingless fan may generate undesired recirculation of air from the downstream to the upstream side of the fan.

[0015] Accordingly, examples are disclosed that relate to an axial fan housing with one or more openings formed in the housing that may facilitate air flow through a cooling system relative to a comparable axial fan lacking such openings. The disclosed examples may provide for convenient mounting in an electronic device compared to a housingless fan, yet also provide for lower impedance in spatially limited systems than a comparable box fan without such openings. As described in more detail below, the openings in the housing may be formed such that an upstream edge (upstream with reference to the direction of airflow, e.g. closer to an inlet than an outlet of the fan) of an opening is located farther from an impingement surface than at least a portion of a downstream edge (downstream with reference to the direction of airflow, closer to the outlet than the inlet of the fan) of the housing. Further, in some examples, the upstream edge of an opening may be located farther from an impingement surface than a downstream edge of a fan impeller, while in other examples, an opening may have any other suitable spatial relationship with a downstream edge of an impeller. The use of openings as described herein may help to achieve a larger hydraulic diameter for the flow path exiting an axial fan compared to a similar fan without such openings. Such openings also may help to utilize the swirl (tangential) and radial components of the airflow exiting the fan blades, which may be otherwise restricted by a housing without such openings.

[0016] FIG. 1 shows a block diagram of an example device 100 comprising an axial fan 102 and an impingement surface 104 located to receive a flow of air from the axial fan 102. Air, indicated by arrows, 106 flows from the inlet side 108 of axial fan 102, through the fan, and toward impingement surface 104. Air then flows across impingement surface 104, thereby removing heat from the impingement surface. The impingement surface may have fins or other geometrical features that increases the surface area, which may increase a rate of heat transfer compared to the use of an impingement surface lacking such features. It will be understood that device 100 may represent any suitable device. Examples include, but are not limited to, computing devices such as mobile computing systems (e.g. laptop computers), desktop computers, entertainment computers (e.g. video game consoles), and sensor systems (e.g. imaging and/or acoustic sensing systems, including but not limited to depth imaging and/or microphone array systems).

[0017] Axial fan 102 comprises a housing having an opening 112 formed in a side of the housing. As mentioned above, such a configuration may help to lower flow impedance of the cooling system of device 100 relative to a similar axial fan lacking such an opening. FIGS. 2 and 3 show one non-limiting example of an axial fan 200 suitable for use as axial fan 102. Axial fan 200 comprises a housing 202 including an outlet end 204, an inlet end 206, and a plurality of sides (one of which is shown as side 208) extending at least partially between the inlet end 206 and the outlet end 204. Axial fan 200 further includes an impeller and motor assembly 209 comprising an impeller 210 with a plurality of blades and a motor configured to drive movement of the impeller 210. Each impeller blade has an upstream edge 214 (upstream along a direction of airflow) and a downstream edge 216 (downstream along a direction of airflow). The upstream edge and downstream edge of the impeller blades may be referred to herein as the upstream and downstream edge of the impeller, respectively. Axial fan 200 further includes a plurality of struts 218 located to position the impeller and motor assembly relative to the housing 202. While the depicted embodiment includes three struts, it will be understood that any suitable number of struts having any suitable configuration may be used.

[0018] The axial fan 200 also includes an opening 222 formed in a side of the housing 202. The opening 222 comprises an upstream edge 224 located farther from the outlet end 204 of the axial fan 200 than a downstream edge 220 of the housing 202. In some examples, struts or other structures of an axial fan may extend farther downstream along the axial direction (along axis 229) than the downstream edge of the housing, while in other examples the downstream edges of the struts or other structures may be approximately flush with, or upstream of, the downstream edge of the housing, such that the downstream edge of the housing is the most downstream portion of the fan.

[0019] The housing and opening or openings may have any suitable configuration.

In the example of FIG. 2, housing 202 has a generally square cross-sectional shape in a direction transverse to the axial direction. In other examples, a housing may have a different cross-sectional shape, such as another polygonal shape, an elliptical shape (e.g. circular), etc. It will be understood that a shape of a fan may be designed or otherwise selected based upon a configuration of a device in which the fan is to be used and how the fan is to be secured within the device.

[0020] The depicted openings take the form of cutaway portions of the downstream portion of the housing that extend fully to a downstream edge of the housing along an axial direction, as shown at 230 in FIG. 3, wherein the term "cutaway" does not imply any particular method of forming the openings in the housing. In other examples, an opening may take the form of a hole formed in a side of the housing, such that the opening does not extend fully to the downstream edge of the housing.

[0021] Each opening may extend any suitable length along the axial direction of the fan. As a non-limiting example, an opening may have a depth of 20-30% of the housing depth in the axial direction from the downstream edge of the housing. Such an opening may allow a 10-90% increase in operating flow in some use environments. In other examples, an opening may extend up to 50% of the axial depth of the housing from the downstream edge of the housing, or even farther. An axial depth of an opening may be constrained by unwanted recirculation of air and/or acoustic noise, which may be system-specific parameters. It will be understood that these specific examples are presented for the purpose of illustration, and are not intended to be limiting in any manner, as any suitable number and configuration of openings may be used to achieve desired flow characteristics in a system.

[0022] An opening may have any suitable depth relative to an impeller. For example, an opening may be configured such that the upstream edge of the opening is located farther from a downstream edge of a housing than at least a portion of a downstream edges of an impeller. In other implementations, an upstream edge of an opening may be located at approximately a same distance from an outlet end of the housing as a downstream edge of an impeller, or closer to a downstream edge of a housing than a downstream edge of an impeller.

[0023] As mentioned above, in an electronic device, an axial fan may be placed to direct a flow of air against an impingement surface to cool an electronic component. As such, when located in a device, the upstream edge of the opening of the housing is located farther from the impingement surface than the downstream edge of the housing, and may be farther from the impingement surface than at least a portion of the downstream edge of the impeller in some examples.

[0024] FIG. 4 shows a view of the outlet end of the example axial fan of FIG. 2 as viewed along an axial direction of the fan, and illustrates example configurations of the struts and impeller. In this example, the struts extend from the housing 202 to a support 226 for the impeller and motor assembly 209 in a curved shape. The shape and contour of the struts may be designed to help reduce flow impedance, and allow air to flow into the impingement surface with a suitably low pressure drop across the fan. The shape and contour of the struts may also be designed to lessen any acoustic noise generated due to the interaction of the struts with the impeller and/or the downstream edge of the impeller. As examples, the struts may be designed to have a suitably low effect on impedance (e.g. not be a bluff body), to shape and/or turn airflow in a suitable direction for an intended end use, and/or limit an acoustic interaction between the blades and struts as the blades pass the struts. Further, the strut shape may be configured to increase an effectiveness of directing the airflow to and along the impingement surface, such as by directing airflow along a channel direction of any fins on the impingement surface. A strut may meet the housing at any suitable location, including at a corner or along an edge of the housing. Three struts are shown in the example of FIG. 4, but any suitable number of struts may be used. [0025] FIG. 5 shows another example axial fan 500. Like fan 200, fan 500 comprises a housing 502 having a square cross section transverse to an axial direction. However, fan 500 comprises four struts 518 that connect to the housing 502 at corners of the housing. Further, struts 518 have a straight, rather than curved, configuration. Additionally, fan 500 includes four openings 522 (e.g. an opening on each side of the fan housing), whereas fan 200 includes two openings.

[0026] FIG. 6 shows yet another example implementation of an axial fan 600. Like fan 500, fan 600 has a square cross-sectional shape transverse to an axial direction, but has openings 622 formed in a first subset of sides (e.g. side 608 plus the opposite side) and not formed in a second subset of sides (e.g. side 618 plus the opposite side. In yet other examples, openings may be on adjacent sides, rather than opposite sides, and on any other suitable subset of sides than that shown.

[0027] FIG. 7 shows another example implementation of an axial fan 700. Unlike fans 200, 500, and 600, fan 700 comprises a housing 702 having an elliptical cross-section transverse to an axial direction of the fan. Fan 700 also includes a plurality of openings 722 formed in the side 708.

[0028] FIG. 8 shows another example implementation of an axial fan 800. Unlike fans 200, 500, 600, and 700, fan 800 omits struts that position an impeller and motor assembly relative to a housing. Instead, fan 800 includes a housing with one or more walls 802 that may be mounted to other structures within a device incorporating the fan. Further, the motor and impeller assembly 808 of fan 800 may be mounted to an impingement surface 806. The walls 802 and motor and impeller assembly 808 may be positioned such that walls 802 do not extend fully to the downstream edge 804 of the fan.

[0029] Another example provides a device comprising an impingement surface, and a fan positioned to direct a flow of air onto the impingement surface, the fan comprising an impeller and motor assembly, a housing comprising an inlet end, an outlet end, and a side extending at least partially between the inlet end and the outlet end, a strut located to position the impeller and motor assembly relative to the housing, and an opening formed in the side of the housing, the opening comprising an upstream edge located farther from the impingement surface than a downstream edge of the housing along an axial direction of the fan. The device may alternatively or additionally include the upstream edge of the opening being located farther from the impingement surface than a downstream edge of the impeller. The device also may alternatively or additionally include a housing comprising a polygonal transverse cross-section and a plurality of sides, wherein the opening in the side is a first opening in a first side, and wherein the housing comprises one or more other openings formed in one or more sides other than the first side. The device also may alternatively or additionally include a housing comprising openings formed in a first subset of sides and not formed in a second subset of sides. The device also may alternatively or additionally include a housing comprising an elliptical cross-section transverse to the axial direction. The device also may comprise an axial fan. Any or all of the above-described examples may be combined in any suitable manner in various implementations.

[0030] Another example provides a fan comprising an impeller and motor assembly, a housing comprising an inlet end, an outlet end, and a side extending at least partially between the inlet end and the outlet end, a strut located to position the impeller and motor assembly relative to the housing, and an opening formed in the side of the housing, the opening comprising an upstream edge located farther from the outlet end of the fan along an axial direction of the fan than a downstream edge of the housing. The fan may alternatively or additionally include the upstream edge of the opening being located farther from the outlet end than a downstream edge of the impeller. The fan may alternatively or additionally include a housing comprising a polygonal transverse cross-section and a plurality of sides, wherein the opening in the side is a first opening in a first side, and wherein the housing comprises one or more other openings formed in one or more sides other than the first side. The fan also may alternatively or additionally include a housing comprising openings formed in a first subset of sides and not formed in a second subset of sides. The fan also may alternatively or additionally include a housing comprising an elliptical cross-section transverse to the axial direction. The fan also may alternatively or additionally comprise an axial fan. Any or all of the above-described examples may be combined in any suitable manner in various implementations.

[0031] Another example provides a computing device, comprising an impingement surface, and a fan positioned to direct a flow of air onto the impingement surface, the fan comprising an impeller and motor assembly including an impeller having a downstream edge, a housing comprising an inlet end, an outlet end, and a side extending at least partially between the inlet end and the outlet end, a strut located to position the impeller and motor assembly relative to the housing, and an opening formed in the side of the housing, the opening comprising an upstream edge located farther from an impingement surface than a downstream edge of the impeller along an axial direction of fan. The computing device may alternatively or additionally include a housing comprising a polygonal transverse cross- section and a plurality of sides, wherein the opening in the side is a first opening in a first side, and wherein the housing comprises one or more other openings formed in one or more sides other than the first side. The computing device also may alternatively or additionally include a housing comprising openings formed in a first subset of sides and not formed in a second subset of sides. The computing device also may alternatively or additionally include a housing comprising an elliptical cross-section transverse to the axial direction. The computing device also may alternatively or additionally include a fan comprising an axial fan. Any or all of the above-described examples may be combined in any suitable manner in various implementations.

[0032] It will be understood that the configurations and/or approaches described herein are exemplary in nature, and that these specific embodiments or examples are not to be considered in a limiting sense, because numerous variations are possible. The subject matter of the present disclosure includes all novel and nonobvious combinations and subcombinations of the various processes, systems and configurations, and other features, functions, acts, and/or properties disclosed herein, as well as any and all equivalents thereof.

Claims

1. A device comprising:

an impingement surface; and

a fan positioned to direct a flow of air onto the impingement surface, the fan comprising

an impeller and motor assembly,

a housing comprising an inlet end, an outlet end, and a side extending at least partially between the inlet end and the outlet end,

a strut located to position the impeller and motor assembly relative to the housing, and

an opening formed in the side of the housing, the opening comprising an upstream edge located farther from the impingement surface than a downstream edge of the housing along an axial direction of the fan.

2. The device of claim 1, wherein the upstream edge of the opening is located farther from the impingement surface than a downstream edge of the impeller.

3. The device of claim 1, wherein the housing comprises a polygonal transverse cross- section and a plurality of sides.

4. The device of claim 3, wherein the opening in the side is a first opening in a first side, and wherein the housing comprises one or more other openings formed in one or more sides other than the first side.

5. The device of claim 3, wherein the housing comprises openings formed in a first subset of sides and not formed in a second subset of sides.

6. The device of claim 1, wherein the housing comprises an elliptical cross-section transverse to the axial direction.

7. The device of claim 1, wherein the fan comprises an axial fan.

8. A fan, comprising:

an impeller and motor assembly; a housing comprising an inlet end, an outlet end, and a side extending at least partially between the inlet end and the outlet end;

a strut located to position the impeller and motor assembly relative to the housing; and

an opening formed in the side of the housing, the opening comprising an upstream edge located farther from the outlet end of the fan along an axial direction of the fan than a downstream edge of the housing.

9. The fan of claim 8, wherein the upstream edge of the opening is farther from the outlet end than a downstream edge of the impeller.

10. The fan of claim 8, wherein the housing comprises a polygonal transverse cross- section and a plurality of sides.

11. The fan of claim 10, wherein the opening in the side is a first opening in a first side, and wherein the housing comprises one or more other openings formed in one or more sides other than the first side.

12. The fan of claim 10, wherein the housing comprises openings formed in a first subset of sides and not formed in a second subset of sides.

13. The fan of claim 8, wherein the housing comprises an elliptical transverse cross- section.

14. The fan of claim 8, wherein the fan comprises an axial fan.