Patent Application
20160061220
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.
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.
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.
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.
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.
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.
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.
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.
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.
The housing and opening or openings may have any suitable configuration. In the example of
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
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.
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.
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.
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.
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.
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.
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.
