Abstract: A head-mountable device can include a fan that effectively manages heat while also mitigating the intrusion of particles and other debris. Fans can include a protrusion that creates a tortuous pathway to direct incoming particles away from sensitive regions. Fans can include openings to allow particles to exit the fan enclosure and avoid interaction with the impeller. Fans can include a variable spacing between the impeller and the base plate to avoid collection of particles. Fans can include an adhesive pad that collects and retains particles at a location that does not interfere with rotation of the impeller.

Abstract: A head-mounted device can effectively manage heat while also managing noise output in a manner that reduces the user's perception thereof. For example, a support member extending across a flow channel can provide multiple sections with different profiles and/or cross-sectional dimensions within the flow channel. Each of the profiles and/or cross-sectional dimensions can generate tonal noises at different frequencies, so that the tonal noises generated are distributed across multiple frequencies to mask such tonal noises among broadband noises that are generated by the head-mounted device. Such a support member can be moveably positioned within the flow channel and rigidly coupled to other components of the head-mounted device. Such a support member can also be used to draw heat away from other components of the head-mounted device to be dissipated by the flow of air within the flow channel.

Abstract: A head-mounted device can effectively manage heat while also managing noise output in a manner that reduces the user's perception thereof. For example, a support member extending across a flow channel can provide multiple sections with different profiles and/or cross-sectional dimensions within the flow channel. Each of the profiles and/or cross-sectional dimensions can generate tonal noises at different frequencies, so that the tonal noises generated are distributed across multiple frequencies to mask such tonal noises among broadband noises that are generated by the head-mounted device. Such a support member can be moveably positioned within the flow channel and rigidly coupled to other components of the head-mounted device. Such a support member can also be used to draw heat away from other components of the head-mounted device to be dissipated by the flow of air within the flow channel.

Abstract: Fan assemblies are disclosed. Fan assemblies include an impeller with asymmetric design. For example, an impeller may include a first set of blades with one geometry and second set of fan blades with another geometry. This enables a dual-inlet centrifugal fan to generate different air flow performance characteristics for the air entering one fan inlet compared to the air entering the other fan inlet. The impeller, with different fan blade configurations, can better handle air flow entering the fan assembly through different inlets, particularly when the air flow conditions differ through the inlets due to impeding structures (e.g., motor, struts, etc.). As a result, air flow distribution from air leaving the impeller, including the locations associated with the different fan blade configurations, is relatively uniform. Beneficially, when air flow distribution uniformity increases, the fan assembly operates more efficiently, as air flow pressure losses due to flow separation are mitigated.

Abstract: A head-mounted device can effectively manage heat while also managing noise output in a manner that reduces the user's perception thereof. For example, a support member extending across a flow channel can provide multiple sections with different profiles and/or cross-sectional dimensions within the flow channel. Each of the profiles and/or cross-sectional dimensions can generate tonal noises at different frequencies, so that the tonal noises generated are distributed across multiple frequencies to mask such tonal noises among broadband noises that are generated by the head-mounted device. Such a support member can be moveably positioned within the flow channel and rigidly coupled to other components of the head-mounted device. Such a support member can also be used to draw heat away from other components of the head-mounted device to be dissipated by the flow of air within the flow channel.

Abstract: Fan assemblies are disclosed. Fan assemblies include an impeller with asymmetric design. For example, an impeller may include a first set of blades with one geometry and second set of fan blades with another geometry. This enables a dual-inlet centrifugal fan to generate different air flow performance characteristics for the air entering one fan inlet compared to the air entering the other fan inlet. The impeller, with different fan blade configurations, can better handle air flow entering the fan assembly through different inlets, particularly when the air flow conditions differ through the inlets due to impeding structures (e.g., motor, struts, etc.). As a result, air flow distribution from air leaving the impeller, including the locations associated with the different fan blade configurations, is relatively uniform. Beneficially, when air flow distribution uniformity increases, the fan assembly operates more efficiently, as air flow pressure losses due to flow separation are mitigated.

Abstract: An electronic device includes a fan assembly that draws air (including heated air) away from components and forces the air out of the electronic device. The fan assembly includes a guide vane located in the fan housing. Subsequent to air entering the fan assembly via the fan inlets, the guide vane is designed to direct the air to a fan outlet. Further, the guide vane is designed and positioned in the fan assembly to limit or prevent flow separation that may cause the heated air to recirculate and may also cause increased turbulence leading to elevated acoustic noise. Furthermore, the guide vane may include a tapered region to allow the heated air to readily flow over the guide vane to limit or prevent a vortex from occurring within the fan assembly. Using the guide vane, the fan assembly drives more air at the same fan speed and lowers noise generation.

Abstract: Systems and methods are provided for mitigating recirculation of backflow fluid through a fan. The fan includes a housing having a channel that extends from an inlet to an outlet of the housing. A rotor assembly is positioned within the channel and is configured to direct a fluid flow from the inlet to the outlet. The rotor assembly includes a hub, a plurality of fan blades, and a shroud disposed about a circumference of the fan blades, where a radial gap extends between the shroud and the housing. The radial gap is configured to receive a portion of the fluid flow from the outlet as backflow fluid. The rotor assembly also includes an inlet flange that is configured receive the backflow fluid from the radial gap and to direct the backflow fluid in a direction away from the inlet prior to discharge of the backflow fluid from the radial gap.

Abstract: An electronic device with a fan assembly is disclosed. The fan assembly includes an impeller and an insert separated from the impeller by a gap. The fan assembly increases airflow by rotationally driving the impeller. For a sufficient rotational speed of the impeller, the airflow reaches a level that provides a force that displaces the insert. The displacement may include movement and/or compression of the insert. As a result of the displacement, the gap between the impeller and the insert increases. The increased gap reduces the pressure and associated noise that is otherwise caused by the airflow. When the rotational speed of the impeller reduces or ceases, the insert returns to its initial position. In this manner, the fan assembly includes a self-adjusting gap that changes based on the airflow.

Abstract: An electronic device with a fan assembly is disclosed. The fan assembly includes an impeller and an insert separated from the impeller by a gap. The fan assembly increases airflow by rotationally driving the impeller. For a sufficient rotational speed of the impeller, the airflow reaches a level that provides a force that displaces the insert. The displacement may include movement and/or compression of the insert. As a result of the displacement, the gap between the impeller and the insert increases. The increased gap reduces the pressure and associated noise that is otherwise caused by the airflow. When the rotational speed of the impeller reduces or ceases, the insert returns to its initial position. In this manner, the fan assembly includes a self-adjusting gap that changes based on the airflow.

Abstract: An electronic device includes a fan assembly that draws air (including heated air) away from components and forces the air out of the electronic device. The fan assembly includes a guide vane located in the fan housing. Subsequent to air entering the fan assembly via the fan inlets, the guide vane is designed to direct the air to a fan outlet. Further, the guide vane is designed and positioned in the fan assembly to limit or prevent flow separation that may cause the heated air to recirculate and may also cause increased turbulence leading to elevated acoustic noise. Furthermore, the guide vane may include a tapered region to allow the heated air to readily flow over the guide vane to limit or prevent a vortex from occurring within the fan assembly. Using the guide vane, the fan assembly drives more air at the same fan speed and lowers noise generation.

Abstract: The described embodiments relate to improving efficiency of a low-profile cooling fan. In one embodiment, an impeller of the cooling fan includes a shroud which covers a central portion of the impeller, thereby allowing a central inlet portion of the blades to have an increased fan blade height when compared to a cooling fan constrained by minimum part tolerances between the fan blades and a portion of the fan housing. In some embodiments, the impeller includes splitter blades that can improve performance of the low-profile cooling fan.

Abstract: Systems and methods are provided for mitigating recirculation of backflow fluid through a fan. The fan includes a housing having a channel that extends from an inlet to an outlet of the housing. A rotor assembly is positioned within the channel and is configured to direct a fluid flow from the inlet to the outlet. The rotor assembly includes a hub, a plurality of fan blades, and a shroud disposed about a circumference of the fan blades, where a radial gap extends between the shroud and the housing. The radial gap is configured to receive a portion of the fluid flow from the outlet as backflow fluid. The rotor assembly also includes an inlet flange that is configured receive the backflow fluid from the radial gap and to direct the backflow fluid in a direction away from the inlet prior to discharge of the backflow fluid from the radial gap.

Abstract: A thermal management system that includes a fan assembly, a heat exchanger, and an insulating box is described. The fan assembly can have two impellers and a housing that includes two scroll portions. An internal portion of the scroll wall can be truncated. A motor housing can be connected to the fan housing via multiple struts. The struts can be oriented angularly with a tangential component and can slope inward to increase the effective inlet area. The heat exchanger can be formed of a fin stack that has a curved body that defines an airflow path that turns radially from the inlet to the exhaust. The heat exchanger can have an inlet that is smaller than the exhaust. The heat exchanger can be connected to one or more heat pipes. The insulating box can have a grid that directs air to certain specific directions.

Abstract: In an exemplary electronic device with a cooling fan, a fan assembly is attached to a keyboard assembly of the electronic device. The fan assembly includes an impeller at least partially inside a fan enclosure. The fan enclosure has, on a surface, an inlet opening and an external protrusion. The electronic device further includes a bottom case. The fan assembly is positioned between the keyboard assembly and the bottom case and oriented such that the inlet opening and the external protrusion face the bottom case. The external protrusion maintains a passage between the fan enclosure and the bottom case that allows air to enter the inlet opening and also resists interference between the rotating impeller and the stationary bottom case.

Abstract: A thermal management system that includes a fan assembly, a heat exchanger, and an insulating box is described. The fan assembly can have two impellers and a housing that includes two scroll portions. An internal portion of the scroll wall can be truncated. A motor housing can be connected to the fan housing via multiple struts. The struts can be oriented angularly with a tangential component and can slope inward to increase the effective inlet area. The heat exchanger can be formed of a fin stack that has a curved body that defines an airflow path that turns radially from the inlet to the exhaust. The heat exchanger can have an inlet that is smaller than the exhaust. The heat exchanger can be connected to one or more heat pipes. The insulating box can have a grid that directs air to certain specific directions.

Abstract: In an exemplary electronic device with a cooling fan, a fan assembly is attached to a keyboard assembly of the electronic device. The fan assembly includes an impeller at least partially inside a fan enclosure. The fan enclosure has, on a surface, an inlet opening and an external protrusion. The electronic device further includes a bottom case. The fan assembly is positioned between the keyboard assembly and the bottom case and oriented such that the inlet opening and the external protrusion face the bottom case. The external protrusion maintains a passage between the fan enclosure and the bottom case that allows air to enter the inlet opening and also resists interference between the rotating impeller and the stationary bottom case.

Abstract: The described embodiments relate to improving efficiency of a low-profile cooling fan. In one embodiment, an impeller of the cooling fan includes a shroud which covers a central portion of the impeller, thereby allowing a central inlet portion of the blades to have an increased fan blade height when compared to a cooling fan constrained by minimum part tolerances between the fan blades and a portion of the fan housing. In some embodiments, the impeller includes splitter blades that can improve performance of the low-profile cooling fan.

Abstract: The described embodiments relate to improving efficiency of a low-profile cooling fan. In one embodiment, an impeller of the cooling fan includes a shroud which covers a central portion of the impeller, thereby allowing a central inlet portion of the blades to have an increased fan blade height when compared to a cooling fan constrained by minimum part tolerances between the fan blades and a portion of the fan housing. In some embodiments, the impeller includes splitter blades that can improve performance of the low-profile cooling fan.

Abstract: The described embodiments relate to improving efficiency of a low-profile cooling fan. In one embodiment, an impeller of the cooling fan includes a shroud which covers a central portion of the impeller, thereby allowing a central inlet portion of the blades to have an increased fan blade height when compared to a cooling fan constrained by minimum part tolerances between the fan blades and a portion of the fan housing. In some embodiments, the impeller includes splitter blades that can improve performance of the low-profile cooling fan.