MEMS-based airflow system

Abstract

A system comprising an orifice plate, a fan element, and at least one channel is disclosed. The orifice plate has at least one orifice therein. The fan element is configured to undergo a vibratory motion to drive a fluid through the orifice(s). In response to the fluid being driven through the at least one orifice, the fluid is drawn through the channel(s).

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to U.S. Provisional Patent Application No. 62 / 928,209, filed on October 30, 2019, entitled MEMS-BASEDPIEZEOELCTRIC FAN, which is incorporated herein by reference for all purposes. Background Art

[0003] As computing devices grow in speed and computing power, the heat generated by them is also increasing. Various mechanisms have been proposed to address heat generation. Active devices, such as fans, can be used to drive air through larger computing devices, such as laptops or desktop computers. However, such active devices may not be usable in the context of mobile devices, such as smartphones, and may be inappropriate for larger devices, such as laptops and desktop computers. Therefore, additional thermal management solutions for computing devices are needed. BRIEF DESCRIPTION OF THE DRAWINGS

[0004] Various embodiments of the invention are disclosed in the following detailed description and accompanying drawings.

[0005] Figures 1A to 1F An embodiment of an active system including a fan element that may be used in a device is depicted.

[0006] Figures 2A to 2C An embodiment of an active system including a fan element that may be used in a device is depicted.

[0007] Figures 3A to 3C is a diagram depicting an embodiment of an active system including a fan element that may be used in an apparatus.

[0008] Figures 4A to 4E An embodiment of an active system using fan elements formed into floor tiles is depicted.

[0009] Figure 5 is a diagram depicting an embodiment of an active system including a fan element that may be used in an apparatus.

[0010] Figure 6 is a diagram depicting an embodiment of a system that may be used as a fan.

[0011] 7A to 7B is a diagram depicting an embodiment of a system that may be used as a fan including a plurality of units.

[0012] Figure 8 is a diagram depicting an embodiment of a system that may be used as a fan.

[0013] Figure 9is a diagram depicting an embodiment of a system that may be used as a fan.

[0014] Figure 10 is a diagram depicting an embodiment of a system that may be used as a fan.

[0015] Figure 11 is a diagram depicting an embodiment of a system that may be used as a fan.

[0016] Figure 12 is a diagram depicting an embodiment of a system that may be used as a fan.

[0017] Figure 13 is a diagram depicting an embodiment of a system that may be used as a fan.

[0018] Figure 14 is a diagram depicting an embodiment of a system that may be used as a fan.

[0019] Figure 15 is a diagram depicting an embodiment of a system that may be used as a fan.

[0020] Figure 16 is a diagram depicting an embodiment of a system that may be used as a fan.

[0021] Figure 17 is a diagram depicting an embodiment of a system that may be used as a fan.

[0022] Figure 18 is a flow chart depicting an embodiment of a method for driving fluid flow. DETAILED DESCRIPTION

[0023] The present invention may be implemented in a variety of ways, including as: a process; an apparatus; a system; a composition of matter; a computer program product embodied on a computer-readable storage medium; and / or a processor, such as a processor configured to execute instructions stored on and / or provided by a memory coupled to the processor. In this specification, these embodiments, or any other form that the invention may take, may be referred to as techniques. In general, the order of the steps of the disclosed processes may be changed within the scope of the present invention. Unless otherwise stated, a component such as a processor or memory described as being configured to perform a task may be implemented as a general-purpose component that is temporarily configured to perform a task at a given time or as a specific component that is manufactured to perform a task. As used herein, the term "processor" refers to one or more devices, circuits, and / or processing cores that are configured to process data, such as computer program instructions.

[0024] Provided below are detailed descriptions of one or more embodiments of the present invention and accompanying drawings illustrating the principles of the present invention. The present invention is described in conjunction with such embodiments, but the present invention is not limited to any embodiment. The scope of the present invention is limited only by the claims, and the present invention encompasses many alternatives, modifications, and equivalents. In order to provide a comprehensive understanding of the present invention, many specific details are set forth in the following description. These details are provided for illustrative purposes, and the present invention can be practiced according to the claims without some or all of these specific details. For the sake of clarity, technical materials known in the technical field related to the present invention are not described in detail so that the present invention is not unnecessarily difficult to understand.

[0025] As components in computing devices such as semiconductor devices become increasingly powerful, the amount of heat generated during operation increases. For example, computing devices such as mobile devices (e.g., smartphones, tablets, notebooks, and virtual reality devices) and network devices (e.g., servers) generate significant amounts of heat. In order to manage the heat generated, the movement of a fluid such as air can be utilized. For larger devices such as laptops or desktop computers, a fan with rotating blades can be used to drive air through the larger device. However, for some devices such as smartphones or tablets, such fans are typically too large. Due to the boundary layer of air present at the surface of the component, the fan may also have limited efficacy, provide limited airspeed for the airflow across the hot surface that needs cooling, and may generate excessive noise. Therefore, additional solutions for driving fluids are needed in computing and other applications.

[0026] A system for driving a fluid is disclosed. The system includes an orifice plate, a fan element, and at least one channel. The orifice plate has at least one orifice therein. The fan element is configured to undergo a vibratory motion to drive a fluid through the orifice(s). In response to the fluid being driven through the at least one orifice, the fluid is drawn through the channel(s). In some embodiments, the vibratory motion of driving the fluid through the orifice creates a low-pressure region proximate the orifice plate. In response to the low-pressure region forming, the fluid is drawn through the channel(s).

[0027] In some embodiments, the system includes a support structure. The fan element has a plurality of edges, at least one of which is anchored to the support structure such that one of the plurality of edges is free to vibrate. In some such embodiments, the channel is bounded by the fan element. Furthermore, the orifice plate is positioned adjacent to the edge of the fan element. The fluid flows substantially parallel to the surface of the fan element.

[0028] In some embodiments, the fan element includes an anchored edge such that a central portion of the fan element experiences a vibratory motion. A jet channel may also be included in the device. Fluid flows through the channel in a direction substantially perpendicular to the jet channel. The edge of the jet channel is formed by a jet channel wall. The jet channel wall has an aperture therein. Thus, the channel and jet channel are configured such that fluid is driven through the aperture.

[0029] The apparatus may include an additional fan element having an additional plurality of anchoring sides such that an additional central portion of the additional fan element experiences an additional vibratory motion. The additional vibratory motion of the additional fan element may be out of phase with the vibratory motion of the fan element.

[0030] In some embodiments, a system comprising multiple units is described. Each unit includes an orifice plate (which may be shared between units), a fan element, and at least one channel. The orifice plate has a plurality of orifices therein. The fan element is configured to undergo a vibratory motion to drive a fluid through the orifice(s). In response to the fluid being driven through the at least one orifice, the fluid is drawn through the channel(s). In some embodiments, the vibratory motion driving the fluid through the orifice creates a low-pressure region near the orifice plate. In response to the formation of the low-pressure region, the fluid is drawn through the channel(s). In some embodiments, the device includes a support structure, and the fan element includes edges. At least one of the edges is anchored to the support structure, allowing the edges of the plurality of edges to vibrate freely. In some such embodiments, the channel is defined by the fan element, with the orifice plate proximate the edge. In such embodiments, the fluid flows substantially parallel to the surface of the fan element. In some embodiments, the fan element includes anchored edges, causing the central portion of the fan element to undergo a vibratory motion. In some embodiments, the device includes a jet channel. The fluid flows through the channel in a direction substantially perpendicular to the jet channel.

[0031] A method for moving a fluid includes driving a fan element and using feedback. The fan element is driven to undergo a vibratory motion to drive a fluid through (multiple) orifices of an orifice plate. In response to the fluid being driven through the (multiple) orifices, the fluid is drawn through (multiple) channels. Feedback is used to control the frequency of the vibratory motion. In some embodiments, driving the fluid through the orifice provides a low-pressure area near the orifice plate. In response to the low-pressure area forming, the fluid is drawn through the at least one channel.

[0032] Figures 1A to 1F is a diagram depicting exemplary embodiments of active systems 100 and 100' that can be used with structure 102. For clarity, only certain components are shown. Figures 1A to 1F Although shown as symmetrical, the system(s) 100 and / or 100' need not be symmetrical. Figures 1A to 1E Various modes of one embodiment of the system are depicted. Figure 1F Another embodiment of a system 100 ′ is depicted.

[0033] System 100 includes fan element 120 and support structure 170. Figures 1A to 1E In the embodiment shown in FIG, support structure 170 includes a top plate 110 having vents 112 therein, an orifice plate 130 having orifices 132 therein, an anchor 160, a base 172, and sidewalls 174. Fan element 120 divides the interior of support structure 170 into a top chamber 140 and a bottom chamber 150. Chambers 140 and 150 (collectively referred to as chambers 140 / 150) are formed within orifice plate or bottom plate 130, top plate 110, and sidewalls 174. Support structure is thermally coupled to structure 102 via base 172. Base 172 also provides a space or jet channel 180 for fluid to flow between orifice plate 130 and structure 102. In some embodiments, base 172 may be replaced or augmented by (a plurality of) bases (not shown) at the edge of unit 100. In addition, structure 102 may be removed or placed at a greater distance from orifice plate 130.

[0034] The fan element 120 is supported at its central region by the anchor 160. When actuated, regions of the fan element 120 that are closer to and include portions of the periphery of the fan element (e.g., the tip 123) vibrate. In some embodiments, the tip 123 of the fan element 120 includes a portion of the periphery that is farthest from the anchor 160 and experiences the greatest deflection during actuation of the fan element 120. For clarity, the fan element 120 is shown in FIG. Figure 1A Only one tip 123 of the fan element 120 is marked.

[0035] Figure 1A The system 100 is depicted in a neutral position. Thus, the fan element 120 is shown as being substantially flat. For in-phase operation, the fan element 120 is driven at Figure 1B and Figure 1C 102. The system 100 is configured to vibrate between the positions shown in FIG. This vibratory motion draws fluid (e.g., air) into the vent 112 at high speed and / or high flow, through the chambers 140 and 150 and out of the orifice 132. For example, the speed at which the fluid impacts the structure 102 may be at least 30 m / s. In some embodiments, the fluid is driven toward the structure 102 by the fan element 120 at a speed of at least 45 m / s. In some embodiments, the fluid is driven toward the structure 102 by the fan element 120 at a speed of at least 60 m / s. In some embodiments, other speeds may be possible. The system 100 is also configured so that little or no fluid is sucked back into the chamber 140 / 150 through the orifice 132 by the vibratory motion of the fan element 120.

[0036] The device in which the system 100 is intended to be used may also have limited space to accommodate the system. For example, the system 100 may be used in a computing device. Such computing devices may include, but are not limited to, smartphones, tablet computers, laptop computers, tablet devices, two-in-one laptop computers, handheld gaming systems, digital cameras, virtual reality headsets, augmented reality headsets, mixed reality headsets, and other thin and lightweight devices. In some embodiments, the computing device in which the system 100 is used need not be thin. For example, servers, desktop computers, and / or other larger computing systems may also use the system 100 for cooling. The system 100 may be a microelectromechanical system (MEMS) system that can reside in a mobile computing device and / or other device with limited space in at least one dimension. For example, the total height of the system 100 (from the top of the structure 130 or the bottom of the orifice plate 130 to the top of the top plate 110) may be less than 2 mm. In some embodiments, the total height of the system 100 does not exceed 1.5 mm. In some embodiments, the total height does not exceed 250 microns. In some embodiments, the total height does not exceed 1.1 mm. In some embodiments, the total height does not exceed 1 micron. Thus, system 100 is useful for computing devices and / or other devices with limited space in at least one dimension. However, nothing prevents system 100 from being used in devices with less limited space and / or for purposes other than cooling or driving airflow. Although one system 100 (e.g., one unit) is shown, multiple units 100 may be used. For example, a one-dimensional or two-dimensional array of units may be utilized.

[0037] In some embodiments, the distance y between the bottom of the orifice plate 130 and the top of the structure 102 may be smaller. In some embodiments, y is at least 200 microns and no more than 1 mm. In some embodiments, y is at least 200 microns and no more than 300 microns. In such embodiments, the structure 102 may be expected to be cooled. However, in other embodiments, y may be larger. In some embodiments, the structure 102 may be significantly further away from the orifice plate 130, as described below. More specifically, when used to entrain fluid, the structure 102 may be further away from the orifice plate 130 or may be omitted.

[0038] System 100 is in communication with a fluid. The fluid can be a gas or a liquid. For example, the fluid can be air. In some embodiments, the fluid includes fluid from outside the device in which system 100 resides (e.g., provided through an external vent in the device). In some embodiments, the fluid circulates within the device in which system 100 resides (e.g., in a closed device).

[0039] The fan element 120 can be considered to divide the interior of the active system 100 into a top chamber 140 and a bottom chamber 150. The top chamber 140 is formed by the fan element 120, the side sections, and the top plate 110. The bottom chamber 150 is formed by the orifice plate 130, the side sections, the fan element 120, and the anchor 160. The top chamber 140 and the bottom chamber 150 are connected at the periphery of the fan element 120 and together form the chamber 140 / 150 (e.g., the interior chamber of the system 100).

[0040] The size and configuration of the top chamber 140 can depend on the unit (system 100) size, the frequency of movement and operation of the fan element 120. The top chamber 140 has a height h1. The height of the top chamber 140 can be selected to provide sufficient pressure to drive the fluid to reach the bottom chamber 140 and pass through the orifice 132 at a desired flow rate and / or speed. The top chamber 140 is also high enough so that the fan element 120 does not contact the top plate 140 when actuated. In some embodiments, the height of the top chamber 140 is at least 50 microns and no more than 500 microns. In some embodiments, the top chamber 140 has a height of at least 200 microns and no more than 300 microns.

[0041] Bottom chamber 150 has a height h2. In some embodiments, the height of bottom chamber 150 is sufficient to accommodate the movement of fan element 120. Thus, during normal operation, no portion of fan element 120 contacts orifice plate 130. Bottom chamber 150 is typically smaller than top chamber 140 and can help reduce fluid backflow into orifice 132. In some embodiments, the height of bottom chamber 150 is the maximum deflection of fan element 120 plus at least 5 microns and no more than 10 microns. In some embodiments, the deflection of fan element 120 (e.g., the deflection of tip 123) has an amplitude of at least 10 microns and no more than 100 microns. In some such embodiments, the amplitude of the deflection of fan element 120 is at least 10 microns and no more than 60 microns. However, the amplitude of the deflection of fan element 120 depends on factors such as the desired flow rate through system 100 and the configuration of system 100. Therefore, the height of bottom chamber 150 generally depends on the flow rate through system 100 and other components of system 100.

[0042] Top plate 110 includes vent 112 through which fluid can be drawn into system 100. Top vent 112 can have a size selected based on the desired acoustic pressure in chamber 140. For example, in some embodiments, the width w of vent 112 is at least 500 microns and no more than 1000 microns. In some embodiments, the width of vent 112 is at least 250 microns and no more than 2000 microns. In the illustrated embodiment, vent 112 is a small hole centrally located in top plate 110. In other embodiments, vent 112 can be located elsewhere. For example, vent 112 can be closer to one of the edges of top plate 110. Vent 112 can have a footprint (sometimes also referred to as a base area) that is circular, rectangular, or other shaped. Although a single vent 112 is shown, multiple vents can also be used. For example, the vent can be offset toward the edge of top chamber 140 or located on the side(s) of top chamber 140. Although top plate 110 is shown as being substantially flat, in some embodiments, grooves and / or other structures may be provided in top plate 110 to modify the area above top plate 110 and / or the configuration of top chamber 140. In some embodiments, vent 112 may be omitted.

[0043] The fan element 120 includes an anchoring region 122 and a cantilevered arm 121. For simplicity, the anchoring region 122 and the cantilevered arm 121 are only shown in FIG. Figure 1A and Figure 1F The anchoring region 122 is supported (eg, held in place) in the system 100 by the anchor 160. The cantilevered arm 121 undergoes vibratory motion in response to the fan element 120 being actuated. Figures 1A to 1F In the embodiment shown in FIG, anchoring region 122 is centrally located. In other embodiments, anchoring region 122 may be at one edge of the actuator, and outer region 128 at the opposite edge. In such embodiments, fan element 120 is edge-anchored. Although depicted as having a uniform thickness, in some embodiments, fan element 120 may have a varying thickness.

[0044] Anchor 160 supports fan element 120 at a central portion of fan element 120. Thus, at least a portion of the periphery of fan element 120 is unfixed and free to vibrate. In some embodiments, anchor 160 extends along the central axis of fan element 120 (e.g., perpendicular to the axis of the fan element 120). Figures 1A to 1FIn such embodiments, the vibrating portion of fan element 120 (e.g., cantilevered arm 121 including tip 123) moves in a cantilevered manner. Thus, cantilevered arm 121 of fan element 120 can move in a manner similar to the wings of a butterfly (i.e., in phase) and / or similar to a seesaw (i.e., out of phase). Thus, the cantilevered arms of fan element 120 vibrating in a cantilevered manner vibrate in phase in some embodiments and out of phase in other embodiments. In some embodiments, anchor 160 does not extend along the axis of fan element 120. In such embodiments, all portions of the periphery of fan element 120 are free to vibrate (e.g., similar to a jellyfish). In the illustrated embodiment, anchor 160 supports fan element 120 from the bottom. In other embodiments, anchor 160 may support fan element 120 in another manner. For example, anchor 160 may support fan element 120 from the top (e.g., fan element 120 is suspended from anchor 160). In some embodiments, the width a of anchor 160 is at least 0.5 mm and no more than 4 mm. In some embodiments, the width of anchor 160 is at least 2 mm and no more than 2.5 mm. Anchor 160 may occupy at least 10% and no more than 50% of fan element 120. In some embodiments, anchor 160 may be omitted. In such embodiments (described below), fan element 120 is supported at one or more of its edges. In such embodiments, fan element 120 operates as a cantilever arm or may be pinned at multiple edges so that the center portion of fan element 120 vibrates.

[0045] The fan element 120 has a first side and a second side. In some embodiments, the first side is away from the structure 102 and the second side is close to the structure 102. Figures 1A to 1F In the embodiment shown in FIG, the first side of the fan element 120 is the top of the fan element 120 (closer to the top plate 110), and the second side is the bottom of the fan element 120 (closer to the aperture plate 130). The fan element 120 is actuated to undergo a vibratory motion, such as Figures 1A to 1F . The vibrating motion of the fan element 120 drives the fluid from a first side of the fan element 120 (e.g., away from the structure 102 / top chamber 140) to a second side of the fan element 120 (e.g., closer to the structure 102 / bottom chamber 150). The vibrating motion of the fan element 120 draws the fluid through the vents 112 and into the top chamber 140; forces the fluid from the top chamber 140 to the bottom chamber 150; and drives the fluid from the bottom chamber 140 through the orifices 132 of the orifice plate 130.

[0046] The fan element 120 has a length L that depends on the frequency at which the fan element 120 is desired to vibrate. In some embodiments, the length of the fan element 120 is at least 4 mm and no more than 10 mm. In some such embodiments, the fan element 120 has a length of at least 6 mm and no more than 8 mm. The depth of the fan element 120 (e.g., perpendicular to the Figures 1A to 1F ) can vary from one-quarter L to twice L. For example, fan element 120 can have a depth that is the same as its length. The thickness t of fan element 120 can vary based on the configuration of fan element 120 and / or the frequency at which fan element 120 is desired to be actuated. In some embodiments, for a fan element 120 having a length of 8 mm and driven at a frequency of at least 20 kHz and no more than 25 kHz, the fan element thickness is at least 200 microns and no more than 350 microns. The length C of chamber 140 / 150 approximates the length L of fan element 120. For example, in some embodiments, the distance d between the edge of fan element 120 and the wall of chamber 140 / 50 is at least 100 microns and no more than 500 microns. In some embodiments, d is at least 200 microns and no more than 300 microns. In the illustrated embodiment, fan element 120 can have a substantially rectangular footprint. Other footprints are possible. For example, fan element 120 may have a substantially circular footprint if all edges of fan element 120 are free to vibrate (e.g., in a manner similar to a jellyfish), or if all edges of fan element 120 are anchored (e.g., so that the center portion experiences vibration).

[0047] The fan element 120 can be driven at a frequency that is equal to or close to both the resonant frequency for the acoustic resonance of the pressure waves of the fluid in the top chamber 140 and the resonant frequency for the structural resonance of the fan element 120. The portion of the fan element 120 that undergoes vibratory motion is driven at or near the resonance of the fan element 120 (structural resonance). In some embodiments, the portion of the fan element 120 that undergoes vibration may be the cantilevered arm(s) 121. The frequency of vibration for structural resonance is referred to as the structural resonance frequency. Using the structural resonance frequency when driving the fan element 112 reduces the power consumption of the system 100. The fan element 120 and the top chamber 140 can also be configured so that the structural resonance frequency corresponds to a resonance in the pressure waves in the fluid driven through the top chamber 140 (the acoustic resonance of the top chamber 140). The frequency of this pressure wave is referred to as the acoustic resonance frequency. During acoustic resonance, a node in pressure occurs near vent 112, and an antinode in pressure occurs near the periphery of system 100 (e.g., near tip 123 of fan element 120 and near the connection between top chamber 140 and bottom chamber 150). The distance between these two regions is equal to or close to C / 2. Therefore, C / 2 = nλ / 4, where λ is the acoustic wavelength for the fluid and n is an odd number (e.g., n=1, 3, 5, etc.). For the lowest-order mode, C = λ / 2. Because the length of chamber 140 (e.g., C) is close to the length of fan element 120, in some embodiments, L / 2 = nλ / 4, where λ is the acoustic wavelength for the fluid and n is an odd number, is also approximately correct. Therefore, the frequency v at which fan element 120 is driven is equal to or close to the structural resonant frequency for fan element 120. Frequency v is also equal to or close to the acoustic resonant frequency for at least top chamber 140. The acoustic resonant frequency of the top chamber 140 generally varies less drastically with parameters such as temperature and size than the structural resonant frequency of the fan element 120. Therefore, in some embodiments, the fan element 120 may be driven at (or closer to) the structural resonant frequency rather than the acoustic resonant frequency.

[0048] The orifice plate 130 has an orifice 132 therein. Although a specific number and distribution of orifices 132 are shown, another number, other (multiple) positions and / or another distribution may be used. A single orifice plate 130 is used for a single system 100. In other embodiments, a plurality of systems 100 may share an orifice plate. For example, a plurality of units 100 may be provided together with a desired configuration. In such an embodiment, the units 100 may be of the same size and configuration or of different (multiple) sizes and / or (multiple) configurations. The orifice 132 is shown as having an axis orthogonal to the surface orientation of the structure 102. In other embodiments, the axis of one or more orifices 132 may be at another angle. For example, the angle of the axis may be selected from substantially zero degrees and non-zero acute angles. The orifice 132 also has a sidewall substantially parallel to the normal of the surface of the orifice plate 130. In some, the orifice may have a sidewall at a non-zero angle to the normal of the surface of the orifice plate 130. For example, the orifice 132 may be conical. Furthermore, while the orifice plate 130 is shown as being substantially flat, in some embodiments, grooves and / or other structures may be provided in the orifice plate 130 to modify the area between the orifice plate 130 and the structure 102 and / or the configuration of the bottom chamber 150 .

[0049] The size, distribution, and location of the orifices 132 are selected to control the flow of fluid driven to the surface of the structure 102. The location and configuration of the orifices 132 can be configured to increase / maximize the flow of fluid from the bottom chamber 150 through the orifices 132 to the injection channel 180. The location and configuration of the orifices 132 can also be selected to reduce / minimize the suction flow (e.g., backflow) from the injection channel 180 through the orifices 132. For example, it is desirable that the orifices be located far enough from the tip 123 so that the suction force during the upward stroke of the fan element 120 (the tip 123 moves away from the orifice plate 13) is reduced, which would pull the fluid into the bottom chamber 150 through the orifices 132. It is also desirable that the orifices be located close enough to the tip 123 so that the suction force during the upward stroke of the fan element 120 also allows the higher pressure from the top chamber 140 to push the fluid from the top chamber 140 into the bottom chamber 150. In some embodiments, during the upward stroke, the ratio of the flow from the top chamber 140 into the bottom chamber 150 to the flow from the jet channel 180 through the orifice 132 (the "net flow ratio") is greater than 2:1. In some embodiments, the net flow ratio is at least 85:15. In some embodiments, the net flow ratio is at least 90:10. To provide the desired pressure, flow, suction, and net flow ratio, it is desirable that the orifice 132 be at least a distance r1 from the tip 123 and no more than a distance r2 from the tip 123 of the fan element 120. In some embodiments, r1 is at least 100 microns (e.g., r1 ≥ 100 μm) and r2 is no more than 1 millimeter (e.g., r2 ≤ 1000 μm). In some embodiments, the orifice 132 is at least 200 microns from the tip 123 of the fan element 120 (e.g., r1 ≥ 200 μm). In some such embodiments, the orifice 132 is at least 300 microns (e.g., r1 ≥ 300 μm) away from the tip 123 of the fan element 120. In some embodiments, the orifice 132 has a width of at least 100 microns and no more than 500 microns. In some embodiments, the orifice 132 has a width of at least 200 microns and no more than 300 microns. In some embodiments, the orifice spacing s is at least 100 microns and no more than 1 mm. In some such embodiments, the orifice spacing s is at least 400 microns and no more than 600 microns. In some embodiments, it is also desirable that the orifice 132 occupy a specific portion of the area of the orifice plate 130. For example, the orifice 132 may cover at least 5% and no more than 15% of the occupied area of the orifice plate 130 to obtain a desired flow rate of the fluid passing through the orifice 132. In some embodiments, the orifice 132 covers at least 8% and no more than 12% of the occupied area of the orifice plate 130.

[0050] In some embodiments, fan element 120 is actuated using a piezoelectric element. Therefore, fan element 120 may be a piezoelectric fan element. Fan element 120 may be driven by a piezoelectric element mounted on or integrated into fan element 120. In some embodiments, fan element 120 is driven in another manner, including but not limited to providing a piezoelectric element on another structure in system 100. Fan element 120 and similar fan elements are hereinafter referred to as piezoelectric fan elements, although it is possible that a mechanism other than a piezoelectric element may be used to drive the fan element. In some embodiments, fan element 120 includes a piezoelectric layer on a substrate. The substrate may be a stainless steel, nickel alloy, and / or Hastelloy substrate. In some embodiments, the piezoelectric layer includes multiple sublayers formed as thin films on the substrate. In other embodiments, the piezoelectric layer may be an intrinsic layer (bulk layer) attached to the substrate. Such a piezoelectric fan element 120 also includes electrodes for activating the piezoelectric element. In some embodiments, the substrate serves as the electrode. In other embodiments, a bottom electrode may be disposed between the substrate and the piezoelectric layer. Other layers may be included in the piezoelectric fan element, including but not limited to a seed layer, a capping layer, a passivation layer, or other layers. Thus, the fan element 120 may be actuated using piezoelectrics.

[0051] The operation of the system 100 is Figures 1A to 1E Although described in the context of specific pressures, gap sizes, and flow timings, the operation of system 100 is not dependent upon the explanations herein. Figures 1B to 1C The in-phase operation of the system 100 is depicted. Figure 1B , the fan element 120 has been actuated so that the cantilevered arm 121 and the tip 123 move away from the top plate 110. Therefore, it can be considered that Figure 1B The end of the downward stroke of the fan element 120 is depicted. Due to the vibratory motion of the fan element 120, the gap 152 to the bottom chamber 150 has decreased in size and is shown as gap 152B. In contrast, the gap 142 to the top chamber 140 has increased in size and is shown as gap 142B. During the downward stroke, when the fan element 120 is in the neutral position, a lower (e.g., minimum) pressure is generated at the periphery. As the downward stroke continues, the bottom chamber 150 decreases in size and the top chamber 140 increases in size, as shown. Figure 1C. Thus, the fluid is driven out of the orifice 132 in a direction perpendicular or nearly perpendicular to the surface of the orifice plate 130 and / or the top surface of the structure 102. The fluid is driven from the orifice 132 (and in the embodiment shown, toward the structure 102) at a high speed, for example, in excess of 30 meters per second. Thus, the fluid leaves the orifice 132 at the high speeds described herein. In some embodiments, the fluid then travels along the surface of the structure 102 and toward the periphery of the structure 102, where the pressure is lower than near the orifice 132. Also in the downward stroke, the top chamber 140 increases in size, and a lower pressure exists in the top chamber 140. As a result, the fluid is drawn into the top chamber 140 through the vent 112. The movement of the fluid into the vent 112, through the orifice 132, and along the surface of the structure 102 is Figure 1C Indicated by unlabeled arrows.

[0052] The fan element 120 is also actuated, causing the cantilevered arm 121 and therefore the tip 123 to move away from the structure 102 and towards the top plate 110. Figure 1C The end of the upward stroke of fan element 120 is depicted. Due to the movement of fan element 120, gap 142 has decreased in size and is shown as gap 142C. Gap 152 has increased in size and is shown as gap 152C. During the upward stroke, when fan element 120 is in the neutral position, a higher (e.g., maximum) pressure is generated at the periphery. As the upward stroke continues, bottom chamber 150 increases in size and top chamber 140 decreases in size, as shown. Figure 1C . Thus, the fluid is driven from the top chamber 140 (e.g., the periphery of the chamber 140 / 150) to the bottom chamber 150. Thus, when the tip 123 of the fan element 120 moves upward, the top chamber 140 acts as a nozzle for the incoming fluid to be accelerated and driven toward the bottom chamber 150. The movement of the fluid into the bottom chamber 150 is determined by Figure 1C The position and configuration of fan element 120 and orifice 132 are selected to reduce suction, and therefore reduce backflow of fluid from jet passage 180 into orifice 132 during the upward stroke. Thus, system 100 is able to drive fluid from top chamber 140 to bottom chamber 150 without excessive backflow of fluid from jet passage 180 into bottom chamber 150.

[0053] repeat Figure 1B and Figure 1C Thus, the fan element 120 undergoes Figures 1A to 1CThe vibratory motion indicated in FIG draws fluid from the distal side of top plate 110 through vent 112 into top chamber 140; transfers fluid from top chamber 140 to bottom chamber 150; and propels the fluid through orifice 132 and toward structure 102. As discussed above, fan element 120 is driven to vibrate at or near the structural resonant frequency of fan element 120. In some embodiments, this corresponds to the structural resonance of cantilevered arm 121. Furthermore, the structural resonant frequency of fan element 120 is configured to coincide with the acoustic resonance of chambers 140 / 150. The structural and acoustic resonant frequencies are generally selected to be within the ultrasonic range. For example, the vibratory motion of fan element 120 may be at a frequency from 15 kHz to 30 kHz. In some embodiments, fan element 120 vibrates at one or more frequencies of at least 20 kHz and no more than 30 kHz. The structural resonant frequency of fan element 120 is within 10% of the acoustic resonant frequency of system 100. In some embodiments, the structural resonant frequency of fan element 120 is within 5% of the acoustic resonant frequency of system 100. In some embodiments, the structural resonant frequency of fan element 120 is within 3% of the acoustic resonant frequency of system 100. Thus, efficiency and flow rate can be improved. However, other frequencies may be used.

[0054] Fluid driven through the orifices 132 in the orifice plate 130 may move substantially normal (perpendicular) to the bottom surface of the orifice plate 130 (e.g., substantially perpendicular to the top surface of the structure 102). In some embodiments, the fluid motion may have a non-zero acute angle relative to the normal to the bottom surface of the orifice plate 130 (e.g., relative to the top surface of the structure 102).

[0055] Figures 1D to 1EAn embodiment of an active system 100 including a centrally anchored fan element 120 is depicted, wherein the fan elements are driven out of phase. More specifically, the cantilevered arms 121 of the fan elements 120 on opposite sides of the anchor 160 (and therefore on opposite sides of the central anchoring region 122 of the fan element 120 supported by the anchor 160) are driven to vibrate out of phase. In some embodiments, the cantilevered arms 121 of the fan elements 120 on opposite sides of the anchor 160 are driven at or near 180 degrees out of phase. Thus, one cantilevered arm 121 of the fan element 120 vibrates toward the top plate 110, while the other cantilevered arm 121 of the fan element 120 vibrates toward the orifice plate 130 / structure 102. The movement of the cantilevered arms 121 of the fan element 120 toward the top plate 110 (upward stroke) drives the fluid in the top chamber 140 into the bottom chamber 150 on that side of the anchor 160. The movement of the segments of the fan element 120 toward the orifice plate 130 drives the fluid through the orifices 132 and toward the structure 102. Thus, fluid traveling at a high velocity (e.g., the velocity described with respect to in-phase operation) is alternately driven out of the orifices 132 on opposite sides of the anchor 160. The movement of the fluid Figure 1D and Figure 1E Indicated by unlabeled arrows.

[0056] repeat Figure 1D and Figure 1E Thus, the fan element 120 undergoes Figure 1A 、 Figure 1D and Figure 1EThe vibratory motion indicated in FIG alternately draws fluid from the distal side of top plate 110 through vents 112 into top chamber 140 for each side of fan element 120; transfers fluid from each side of top chamber 140 to the corresponding side of bottom chamber 150; and pushes fluid through orifices 132 on each side of anchor 160 toward structure 102. As discussed above, fan element 120 is driven to vibrate at or near its structural resonant frequency. Furthermore, the structural resonant frequency of fan element 120 is configured to coincide with the acoustic resonance of chambers 140 / 150. The structural and acoustic resonant frequencies are generally selected to be within the ultrasonic range. For example, the vibratory motion of fan element 120 may be at a frequency described for in-phase vibration. The structural resonant frequency of fan element 120 is within 10% of the acoustic resonant frequency of system 100. In some embodiments, the structural resonant frequency of fan element 120 is within 5% of the acoustic resonant frequency of system 100. In some embodiments, the structural resonant frequency of fan element 120 is within 3% of the acoustic resonant frequency of system 100. Thus, efficiency and flow rate can be improved. However, other frequencies can be used. The fluid driven toward structure 102 for out-of-phase vibration can move substantially orthogonally (perpendicularly) to the bottom surface of the orifice plate in a manner similar to that described above for in-phase operation.

[0057] Using a system 100 actuated for in-phase or out-of-phase vibration, fluid is drawn in through the vent 112 and driven through the orifice 132 at high speed (e.g., at least 30 m / s). Because the fan element 120 can vibrate at a frequency of 15 kHz or higher, the user may not hear any noise associated with the actuation of the fan element. If driven at or near structural and / or acoustic resonance frequencies, the power used in the operating system can be significantly reduced. During vibration, the fan element 120 does not physically contact the top plate 110 or the orifice plate 130. Therefore, the resonance of the fan element 120 can be more easily maintained. More specifically, physical contact between the fan element 120 and other structures disrupts the resonant conditions for the fan element 120. Disrupting these conditions can drive the fan element 120 out of resonance. Therefore, additional power will be required to maintain the actuation of the fan element 120. In addition, the fluid flow driven by the fan element 120 can be reduced. By using the pressure differential and fluid flow discussed above, these problems are avoided. The benefit of improved quiet cooling can be achieved with limited additional power. In addition, the out-of-phase vibration of the fan element 120 allows the position of the center of mass of the fan element 100 to remain more stable. Although torque is applied to the fan element 120, the force generated by the movement of the center of mass is reduced or eliminated. As a result, the vibration caused by the movement of the fan element 120 can be reduced. In addition, by using out-of-phase vibrating motion on both sides of the fan element 120, the efficiency of the system 100 can be improved. For the out-of-phase vibration of the cantilevered arm 121, the vibration through the system 100 can also be reduced. Therefore, the performance of the equipment incorporating the system 100 can be improved. In addition, the system 100 can be used for other applications (e.g., with or without structure 102) that expect high fluid flow and / or speed.

[0058] Figure 1F An embodiment of an active system 100' is depicted that includes a top center anchored fan element. System 100' is similar to system 100. Therefore, similar components have similar references. For example, system 100' can be used in conjunction with a structure 102 that is similar to structure 102.

[0059] System 100' includes a support structure 170', a top plate 110' having vents 112', a fan element 120, a perforated plate 130 including orifices 132, a top chamber 140' having a gap, a bottom chamber 150 having a gap, an anchor 160, and an ejection channel 180, which are similar to Figures 1A to 1E1 and 3. The fan element 120 is provided with a support structure 170, a top plate 110 having vents 112, a fan element 120, a perforated plate 130 including an orifice 132, a top chamber 140 having a gap 142, a bottom chamber 150 having a gap 152, an anchor 160, and a jet channel 180. Thus, the fan element 120 is centrally supported by the anchor 160 such that at least a portion of the periphery of the fan element 120 is free to vibrate. In some embodiments, the anchor 160 extends along the axis of the fan element 120 (e.g., in a manner similar to anchors 360A and / or 360B). In other embodiments, the anchor 160 is only proximate to a central portion of the fan element 120 (e.g., similar to anchors 360C and / or 360D). The fan element 120 includes an anchoring region 122 and a cantilevered arm 121, which are similar to Figures 1A to 1E 1 and 2. Anchoring region 122 and cantilevered arms 121 of fan element 120 are depicted in FIG. The cantilevered arms 121 of fan element 120 may be driven in phase and / or out of phase.

[0060] Anchor 160 supports fan element 120 from above. Thus, fan element 120 is suspended from anchor 160. Anchor 160 is suspended from top plate 110'. Top plate 110' includes vents 113. Vents 112' on the sides of anchor 160 provide a path for fluid to flow into the sides of chamber 140'.

[0061] As discussed above with respect to system 100, fan element 120 can be driven to vibrate at or near the structural resonant frequency of fan element 120. Furthermore, the structural resonant frequency of fan element 120 can be configured to coincide with the acoustic resonance of chamber 140' / 150. Structural and acoustic resonant frequencies are generally selected to be within the ultrasonic range. For example, the vibratory motion of fan element 120 can be at the frequencies described with respect to system 100. Consequently, efficiency and flow rate can be improved. However, other frequencies can be used.

[0062] System 100' operates in a manner similar to system 100. System 100' therefore shares the benefits of system 100. Using a fan element 120 constructed in a manner similar to fan element 120 can improve efficiency and reliability. In addition, suspending fan element 120 on anchor 160 can further enhance performance. In particular, vibrations in system 100' that may affect other units (not shown) can be reduced. For example, due to the movement of fan element 120, smaller vibrations can be caused in top plate 110'. Therefore, crosstalk between system 100' and other systems (e.g., other units) or other parts of the equipment incorporated into system 100' can be reduced. Therefore, performance can be improved.

[0063] Systems 100 and 100' drive fluid so that the fluid leaving orifice 132 has a high velocity of at least 30 meters per second. In some embodiments, the fluid leaving orifice 132 has a velocity of at least 45 meters per second. In some embodiments, the fluid leaves orifice 132 at a velocity of at least 60 meters per second. In some embodiments, other velocities may be possible. The fluid leaving orifice 132 has a high velocity, in part because the fluid traveling through chamber 140 / 150 has a high flow rate. In some embodiments, for example, the flow rate through chamber 140 / 150 may be at least 0.05 cubic feet per minute (cfm). In some embodiments, the flow rate through chamber 140 / 150 is at least 0.1 cfm. Other (i.e., higher or lower) flow rates are possible. The relatively high flow rate that can be driven by (multiple) systems 100 and / or 100' efficiently removes heat from fan element 120 and (multiple) support structures 170 and / or 170'.

[0064] Figures 2A to 2C A system 200 similar to system 100 is depicted. Figure 2A System 200 is depicted in a neutral position. Figure 2B The system 200 is depicted in an inhalation arrangement. Figure 2C The system 200 is depicted in an exhaust configuration. Accordingly, similar components have been labeled similarly. For example, the system 200 may be used in conjunction with a structure 202 similar to the structure 102. The system 200 includes a support structure 270 having a base 272 and sidewalls 274, a fan element 220, an orifice plate 230 including an orifice 232, a chamber 250, and an ejection channel 280, each of which is similar to Figures 1A to 1F 170, including a support structure 170 having a base 172 and sidewalls 174, a top plate 110, a fan element 120, an orifice plate 130 including an orifice 132, a bottom chamber 150, and an injection channel 180. However, in the illustrated embodiment, the support structure 270 does not include a top plate. In addition, the fan element 220 is anchored at its edge to the sidewalls 274. Thus, a chamber 250 is formed between the orifice plate 230 and the fan element 220.

[0065] System 200 operates in a manner similar to system 100 and / or 100'. Figure 2B In the suction arrangement shown in FIG, the fan element 220 vibrates away from the orifice plate 230. This movement expands the chamber 20. The fan element 220 is then in the discharge mode and Figure 2C As shown in the figure, it vibrates in the opposite direction. Figure 2CAs indicated by the unlabeled arrow in FIG, the fluid is driven out of the orifice 232. In some embodiments, the fluid is driven out of the orifice 232 at a speed of at least 30 m / s. In some embodiments, the fluid driven out of the orifice 232 has a speed of at least 45 m / s. In some embodiments, the fluid has a speed of at least 55 m / s. In addition, in some embodiments, a fluid speed of at least 60 m / s and / or 75 m / s can be achieved. However, in some embodiments, higher speeds may be possible.

[0066] Figures 3A to 3C is a diagram depicting an exemplary embodiment of an active system 00 that can be used with structure 302. For clarity, only certain components are shown, and Figures 3A to 3C Not drawn to scale. System 300 is used in conjunction with structure 302. Although shown as symmetrical, cooling system 300 need not be symmetrical.

[0067] System 300 is similar to systems 100 and 200. Therefore, similar components have similar labels. System 300 includes fan elements 310 and 320 that are similar to fan elements 120 and 220. Fan element 310 can be considered to replace top plate 110. System 300 also includes orifice plate 330 having orifice 332 therein, top chamber 340, bottom chamber 350, support structure 370, and injection channel 380, which can be similar to orifice plate 130 and / or 230 having orifice 132 and / or 232 therein, top chamber 140, bottom chamber 150 and / or 250, support structure 170 and / or 270, and injection channel 180 and / or 280. For simplicity, Figure 3C The injection channel 380 is not labeled. The support structure 370 includes a base 372 and sidewalls 374 similar to the base 172 and / or 272 and sidewalls 174 and / or 274. Also shown are optional channels 390 for entrained fluid, as described below.

[0068] The fan element 310 has a first side facing away from the structure 302 and a second side facing closer to the structure 302. The first side of the fan element 310 is the top of the fan element 310, and the second side is the bottom of the fan element 310. The fan element 310 also has a passive vent 312 therein. In the embodiment shown, the passive vent 312 is a small hole centrally located in the fan element 310. In other embodiments, the passive vent 312 may be located elsewhere. For example, the passive vent 312 may be closer to one of the edges of the fan element 310. The passive vent 312 may have a footprint that is circular, rectangular, or other shaped. Although one passive vent 312 is shown, multiple passive vents may also be used.

[0069] The fan element 320 is between the fan element 310 and the structure 302. In the embodiment shown, the fan element 320 is also between the fan element 310 and the orifice plate 330. The fan elements 310 and 320 are separated by a gap 342 and form a top chamber 340. A bottom chamber 350 is formed between the fan element 320 and the orifice plate 330. The fan element 320 also has an active vent 322 therein. In the embodiment shown, the active vent 322 is a small hole located away from the center area of the fan element 320. In other embodiments, the active vent 322 may be located elsewhere. For example, the active vent may be centrally located in the fan element 320. Although two active vents 322 are shown, another number (e.g., one, three, etc.) may exist. In some embodiments, the active vent 322 is positioned so that the active vent 322 is not aligned with the passive vent 312. The active vent 322 may have a footprint that is circular, rectangular, or other shaped. In some embodiments, a single fan element 310 or 320 that does not include vents may be used instead of two fan elements.

[0070] Figure 3A The system 300 is depicted in a neutral position. Thus, the fan elements 310 and 320 are shown as being substantially flat. In operation, the fan elements 310 and 320 are actuated to Figure 3B and Figure 3C Thus, fan elements 310 and 320 may be piezoelectric actuators. The operation of system 300 is Figure 3B and Figure 3C Reference Figure 3B , piezoelectric fan element 310 has been actuated to move away from structure 302 (deformed into a convex shape), while piezoelectric fan element 320 has been actuated to move toward structure 302 (deformed into a concave shape). This configuration is referred to as a suction arrangement. Due to the vibratory motion of piezoelectric fan elements 310 and 320, gap 342 has increased in size and is shown as gap 342A. For example, in some embodiments, gap 342 has a height of at least 10 microns and no more than 20 microns in the neutral position ( Figure 3A In the suction arrangement, the gap 342A may have a height of at least 20 microns and no more than 30 microns ( Figure 3B ). As a result, the top chamber 340 has increased in volume, while the bottom chamber 350 has decreased in volume. In the suction arrangement, the flow resistance of the passive vent 312 (passive suction flow resistance) is low. Therefore, the pressure at the passive vent 312 is low. In contrast, the flow resistance of the active vent 322 (active suction flow resistance) is high. Therefore, the pressure at the active vent 322 is high. Due to the low passive suction flow resistance, fluid is sucked into the top chamber 340 through the passive vent 312. This is caused by Figure 3B . However, due to the high passive suction flow resistance, fluid does not flow out of the active vent 322 (or flows out to a limited extent). However, in this configuration, the active vent 322 is not physically closed. For example, the active vent 322 does not contact the orifice plate 330 in the suction arrangement.

[0071] Figure 3C 3B. The piezoelectric fan element 310 has been actuated to move toward the structure 302 (deformed into a concave shape), while the piezoelectric fan element 320 has been actuated to move away from the structure 302 (deformed into a convex shape). Due to the vibratory motion of the piezoelectric fan elements 310 and 320, the gap 342 has decreased in size and is shown as gap 342B. For example, in some embodiments, the gap 342 has a height of at least 10 microns and no more than 20 microns in the neutral position ( Figure 3A ). The gap 342B has a height of at least 5 microns and no more than 10 microns in the drain arrangement ( Figure 3C ). As a result, the top chamber 340 has decreased in volume, while the bottom chamber 350 has increased in volume. In the exhaust arrangement, the flow resistance of the passive vent 312 (passive exhaust flow resistance) is higher. Therefore, the pressure at the passive vent 312 is higher. In contrast, the flow resistance of the active vent 322 (active exhaust flow resistance) is lower. Therefore, the pressure at the active vent 322 is lower. Due to the low active exhaust flow resistance, the fluid passes from the top chamber 340 through the active vent 322 into the bottom chamber 350 and is exhausted through the orifice 332. This is caused by Figure 3C . However, due to the high passive exhaust flow resistance, fluid does not flow out of the passive vent 312 (or flows out to a limited extent). Therefore, in the exhaust arrangement, the passive vent 312 is considered closed, and the active vent 322 is considered open. However, in this configuration, the passive vent 312 is not physically closed. For example, the passive vent 312 does not contact the fan element 320 in the exhaust arrangement. The gap 342B does not have a zero length.

[0072] Due to the vibratory motion of the fan elements 310 and 320 (and Figures 3B to 3C The fluid is drawn into the top chamber 340 and through the orifice 332 (due to a corresponding decrease in the gap 342A / 442B). The movement of the fluid is shown by the arrows through the orifice 332. The fluid may diffuse as it travels away from the orifice plate 320, as indicated by Figure 3C The fluid may deviate from the structure 302 (if present) and follow the path between the structure 302 and the orifice plate 330 as shown by dashed lines and arrows in FIG.

[0073] Figure 3B and Figure 3C The movement between the positions shown in is repeatable. Thus, the piezoelectric fan elements 310 and 320 vibrate, drawing fluid from the distal side of the fan element 310 into the top chamber 340 through the passive vent 312, exiting the chamber 340 through the active vent 322, and pushing the fluid through the orifice 332 and toward the structure 302. In some embodiments, one or more vibration frequencies of the fan elements 310 and / or 320 are similar to the vibration frequency of the fan element 120. Furthermore, in some embodiments, the fan element(s) 310 and / or 320 may be driven at or near a resonant frequency. It may also be desirable for the resonant frequencies of the piezoelectric fan element(s) 310 and 320 to be close. In some embodiments, it is desirable for the resonant frequencies of the piezoelectric fan element(s) 310 and 320 to be within 100 Hz. In some embodiments, feedback is used to maintain the piezoelectric fan element(s) 310 and / or 320 at or near resonance. The resonant frequency of fan elements 310 and / or 320 may closely match the acoustic resonant frequency of chamber(s) 340 and / or 350. In some embodiments, the velocity at which the fluid impinges on structure 302 is within the ranges described herein for system(s) 100 and / or 200.

[0074] Using system 300, fluid can be drawn in through passive vent 312 (in an intake arrangement) and driven through active vent 322 and orifice 332 (in an exhaust arrangement). Thus, airflow can be driven by system 300. Furthermore, the fluid can efficiently dissipate heat from structure 302 in a manner similar to the fluid driven by system 100. Consequently, the performance of devices utilizing system 300 can be improved. Furthermore, system 300 can be a MEMS device. Thus, system 300 can be smaller (having an overall height similar to that described above) and can be used in similar devices.

[0075] Figures 4A to 4E An embodiment of an active system 400 is depicted that includes multiple units configured as tiles or arrays. Figure 4A A top view is depicted, and Figures 4B to 4E A side view is depicted. Figures 4A to 4ENot drawn to scale. System 400 includes four units 401A, 401B, 401C, and 401D (collectively or generally 401), which are similar to one or more of the systems described herein. More specifically, unit 401 is similar to system 100. In some embodiments, unit(s) 401 may be similar to system 300 and / or another system. Although four units 401 in a 2x2 configuration are shown, in some embodiments, another number and / or another configuration of units 401 may be employed. In the illustrated embodiment, unit 401 includes a common top plate 410 having apertures 412, a fan element 420, a common orifice plate 430 including orifices 432, a top chamber 440, a bottom chamber 450, and an anchor (support structure) 460, which are similar to top plate 110 having apertures 112, fan element 120, orifice plate 130 having orifices 132, top chamber 140, bottom chamber 150, and anchor 160. In some embodiments, the units 401 may be manufactured together and separated, for example, by cutting through the top plate 410 and the aperture plate 430. The fan elements 420 are driven out of phase (i.e., in a seesaw-like manner). Figures 4B to 4C and Figures 4D to 4E As can be seen in FIG, the fan elements 420 in one unit are driven out of phase with the fan elements 420 in the adjacent unit(s). Figures 4B to 4C , the fan elements 420 in a row are driven out of phase. Thus, the fan elements 420 in unit 401A are out of phase with the fan elements 420 in unit 401B. Similarly, the fan elements 420 in unit 401C are out of phase with the fan elements 420 in unit 401D. Figures 4D to 4E , the fan elements 420 in a column are driven out of phase. Thus, the fan elements 420 in unit 401A are out of phase with the fan elements 420 in unit 401C. Similarly, the fan elements 420 in unit 401B are out of phase with the fan elements 420 in unit 401D. By driving the fan elements 420 out of phase, vibrations in the system 400 can be reduced.

[0076] The units 401 of system 400 operate in a manner similar to system(s) 100, 300, and / or similar systems. Thus, the benefits described herein can be shared by system 400. Because fan elements in adjacent units are driven out of phase, vibrations in system 400 can be reduced. Because multiple units 401 are used, system 400 can enjoy enhanced cooling capacity. Furthermore, multiple individual units 401 and / or systems 400 can be combined in various ways to achieve a desired footprint for the units.

[0077] Figure 5 is a diagram depicting an exemplary embodiment of a system 500 that can be used with a structure that generates heat. For clarity, only certain components are shown, and Figure 5 Piezoelectric cooling system 500 is used in conjunction with structure 502. Structure 502 is similar to structure(s) 102, 202, and / or 302.

[0078] The piezoelectric cooling system 500 includes a plurality of units 501, each of which includes a fan element 520. The units 501 may have the same size range as described above, such that S is at least 3 mm and no more than 5 mm. The piezoelectric blade element 520 is at an angle of When actuated, the fan element 520 is oriented at an angle 1 and angle 2. In some embodiments, the vibration angle ( 2- 1) is at least 5 degrees and no more than 20 degrees. The length of the fan element 520 may vary depending on the distance from the structure 502 and the angle of operation. For example, the vibrating portion of the fan element 520 may be at least 1 mm and no more than 5 mm in length. In some embodiments, the frequency of vibration is nominally 300 Hz. Other frequencies are possible. In some embodiments, is nominally 30 degrees, and h is nominally 250 microns. The top of each fan element 520 is at a distance d above the surface of structure 502. In some embodiments, d is at least 300 microns and no more than 500 microns. However, other spacings are possible.

[0079] In operation, the fan element 520 vibrates, drawing fluid from the distal side of one piezoelectric element to the proximal side of the other piezoelectric element. This movement of the fluid can be Figure 5 5. The fluid is driven along the surface of structure 502. In some embodiments, units such as units 100, 200, 300, and / or 401 (rotated 90 degrees) may be used. Furthermore, piezoelectric cooling structure 500 may be combined with one or more of piezoelectric cooling structures 100, 200, 300, and / or 400. In such embodiments, fan element 520 may help draw air along the corresponding heat-generating structure.

[0080] Systems 100, 200, 300, 400, and / or 500 can be used to drive fluids such as air (or other gases) and / or liquids. For example, systems 100, 200, 300, 400, and / or 500 can be used as MEMs-based fans. Such fans contrast with fans with rotating blades, which require significantly more space, have lower back pressure, and provide flow at significantly lower speeds. In some embodiments, MEMs-based fans can provide flow of fluids that is not directly driven by fan elements 120, 220, 320, 420, and / or 520. More specifically, fan elements such as elements 120, 220, 420, and / or 520 can drive fluid through an orifice at a high rate. In some embodiments, the fluid exits the orifice at a speed of at least 30 meters per second. In some embodiments, the fluid is driven by a piezoelectric cooling element at a speed of at least 40 meters per second. In some such embodiments, the fluid has a speed of at least 45 meters per second. In some embodiments, the fluid has a speed of at least 55 meters per second. In addition, in some embodiments, fluid velocities of at least 60 m / s and / or 75 m / s can be achieved. In some embodiments, higher velocities may be possible. Because the fluid leaves the orifice at a high rate, a low pressure is generated outside the orifice plate. This low pressure draws the fluid through the structures in the area of the orifice plate via entrainment. In some embodiments, the volume of the entrained fluid flow is significantly larger than that discharged through the orifice. For example, at least five to ten times the volume of the fluid pushed through the orifice can be entrained. Thus, macroscopic flow of the fluid can be achieved. In some embodiments, any surface (such as for structures 102, 202, 302, and / or 502) is at least 5 to 10 mm from the bottom of the orifice plate to achieve the desired high entrainment. Therefore, the MEMS-based fan described herein can move fluid more efficiently through entrainment.

[0081] For example, Figure 6 is a diagram depicting an embodiment of a system 600 operable as a fan. For clarity, only certain components are shown, and Figure 6 Not drawn to scale. Portions of fan 600 are similar to systems 100, 200, 300, and / or 500. Thus, fan 600 includes a fan element 620, an orifice plate 630 having an orifice 632 therein, a chamber 650, an anchor 660, a support structure 670, a passage 690, and an orifice 692, which are similar to fan element 120, an orifice plate 130 having an orifice 132 therein, a chamber 150, an anchor 160, a support structure 170, and a passage 190. Although only a single orifice 632 is shown, multiple orifices may also be present. Although a single fan element 620 is shown, multiple fan elements may be used. Although vents are not shown, fan element 620 may include vents / small holes.

[0082] Orifice plate 630 is located near the edge (or tip) of fan element 620, rather than underneath fan element 620. Thus, if fan element 620 is in a neutral position (e.g., not driven), orifice plate 630 is substantially perpendicular to the surface of fan element 620. In other embodiments, orifice plate 630 may be oriented at another angle.

[0083] In operation, the fan element 620 undergoes a vibratory motion. In some embodiments, the fan element 620 is driven at or near resonance. In some embodiments, the frequency at which the fan element 620 is driven may be within the ranges described herein (e.g., at least 15 kHz in some embodiments, and at least 20 kHz in some cases). Because the fan element 620 is attached to the anchor 660 at one side (so the fan element 620 can be considered to vibrate in a manner similar to a cantilever beam) or at half of the fan element 120. Thus, the end of the fan element 620 near the orifice 632 vibrates. This may be achieved by Figure 6 See the double-headed arrow in the figure.

[0084] When the fan element 620 moves / bends, the fluid can be driven through the orifice 632 at a high speed (e.g., within the above range). Thus, the fluid can be driven through the orifice 632 at a speed of at least 30 m / s, at least 45 m / s, or higher. Because the fluid leaves the orifice 632 at a high rate, a low pressure is generated on the side of the orifice 632 opposite the fan element 620. This low pressure causes the fluid to be sucked in or entrained through the channel 690. This is shown by the unmarked arrows in the channel 690. The fluid leaves through the orifice 692. In some embodiments, the area near the orifice 690 can be considered a jet channel because some fluid enters this area through the orifice 632. In some embodiments, the volume of the fluid flow through the channel 690 is significantly higher than the fluid flow through the orifice 632. For example, at least five to ten times the volume of the fluid driven through the orifice 632 can be entrained through the channel 690, flowing out of the channel 690 and through the orifice 692. Other relationships between the fluid flows can occur in other embodiments. Therefore, macroscopic flow of fluid through the channel 690 and the pores 692 can be achieved.

[0085] In some embodiments, when in the neutral position, the direction of the macroscopic fluid flow is substantially parallel to the surface of the fan element 620. For example, the fluid may flow in substantially the same direction as the fluid flows through the channel 690 (e.g., as shown in FIG. Figure 6 The flow outflow hole 692 is in the horizontal direction shown in FIG.

[0086] Using system 600, large volumes of fluid can be entrained. For example, in some embodiments, the flow rate of the fluid entrained through channel 690 can be at least three to five times the flow rate of the fluid driven through (multiple) orifices 632. In some embodiments, a higher flow rate can be achieved. Therefore, a high flow rate through channel 690 and orifice 692 can be achieved. In addition, system 600 can be thin. For example, in some embodiments, the height of system 600 in a direction perpendicular to the direction of fluid flow in channel 690 can be no more than 10 mm. In some embodiments, the height of system 600 can be no more than 5 mm. In some embodiments, system 600 can have a height of no more than 3 mm. As a result, system 600 can provide significant fluid flow in a low-profile situation. Therefore, system 600 can move large volumes of fluid in systems with limited space, such as mobile devices. Therefore, the performance of such devices can be improved.

[0087] 7A to 7B is a diagram depicting an embodiment of a fan 700 having multiple units 600 . Figure 7A is a perspective view indicating the entrance to the system 700, and Figure 7B An exit from the system 700 is depicted. The system 700 comprises a plurality of units 600, Figure 7A 6. Only some of these units are labeled. Also indicated are fan elements 620, channels 690, and apertures 692. For simplicity, only some of the fan elements 620, channels 690, and apertures 692 are labeled. Although two layers of units 600 are shown, in other embodiments, another number of layers (e.g., 1, 3, or more) and / or another number of units 600 per layer may be used.

[0088] In operation, system 700 works in a manner similar to system 600. Thus, fluid is entrained through channel 690. The direction of fluid flow is determined by Figure 7A Thus, by employing multiple units 600 in one or more layers, a desired volume of fluid flowing substantially parallel to channel 690 (and the surface of fan element 620) can be achieved. Consequently, the performance of a device utilizing system 700 can be improved.

[0089] Figure 8 is a diagram depicting an embodiment of a system 800 that can be used as a fan. For clarity, only certain components are shown, and Figure 8 Not drawn to scale. System 800 is shown as comprising a single unit. However, multiple systems 800 may be arranged in a one-dimensional array (e.g., a line or line segment(s)) or a two-dimensional array. Thus, system 800 may also be considered a single unit within a larger cooling system that may include multiple systems 800. System 800 may be used in a mobile computing device, a non-mobile device, and / or in conjunction with other devices.

[0090] System 800 includes a top fan element 810 and a bottom fan element 820. Fan elements 810 and 820 can be similar to the fan elements described herein, such as fan elements 120, 220, 310, 320, and / or 420. Fan 800 can have dimensions similar to those described above. Thus, fan elements 810 and 820 can each include a substrate, a piezoelectric layer, and electrodes ( Figure 8 3 ). For simplicity, leads to fan elements and other electronic devices are not shown. The orifice plate 830 having orifice 832 is similar to (multiple) orifice plates 130, 230, 330 and / or 430 having orifices 132, 232, 332 and / or 432, respectively. Although orifices 832 of a specific number, size and distribution are shown, another number (including a single orifice), other (multiple) sizes and another distribution of (multiple) orifices can be used. In the embodiment shown, fan elements 810 and 820 do not include orifices and / or valves. Therefore, system 800 is similar to system 300 depicted in Figure 3. Chambers 840 and 850 similar to chambers 340 and 350 are shown. However, fan elements 810 and 820 do not include vents therein. Therefore, system 800 is also similar to system 200 depicted in Figure 2. In another embodiment, one or both of the fan elements 810 and 820 may include aperture(s), vent(s), and / or valve(s). Figure 8 890 in the support structure 870 for entraining a fluid (e.g., air) in the direction shown by the arrows in FIG. Although surfaces or jets for directing the entrained air from the channels 890 are not shown, such surfaces or jets may be included. Other elements are not shown or labeled.

[0091] In the illustrated embodiment, the top fan element 810 and the bottom fan element 820 vibrate. In some embodiments, the top and bottom fan elements vibrate 180 degrees out of phase. Therefore, when the top fan element 810 moves / bends away from the orifice plate 830, the bottom fan element 820 moves / bends closer to the orifice plate 830. As a result, the bottom chamber 850 decreases in size, forcing fluid to flow through the orifice 832. This can be referred to as the compression stroke. During the suction stroke, the bottom fan element 820 moves / bends away from the orifice plate 830, while the top fan element 810 bends toward the orifice plate 830. As a result, fluid is drawn into the bottom chamber through the orifice 832. Although there is no valve between the top and bottom chambers, the use of two fan elements 810 and 820 can improve the performance of the system 800800. More specifically, the two fan elements 810 and 820 vibrating out of phase can allow for resonant motion between the fan elements 810 and 820. In some embodiments, the resonant motion of the two fan elements 810 and 880 can increase the amplitude of the vibrations for the fan elements 810 and 880. For example, in some embodiments, the amplitude of the vibrations can be increased by up to 50%.

[0092] In operation, during the compression stroke (bottom fan element 820 bends toward orifice plate 830), fluid is driven out of orifice 832 at a high rate. The fluid stream coming out of the orifice is shown by arrows (for simplicity, indicating the fluid stream coming out of only some orifices 832). In some embodiments, the speed at which the fluid leaves the orifice for the bottom chamber is at least 30 meters per second. In some embodiments, the fluid is driven by fan elements 810 and 820 at a speed of at least 40 meters per second. In some such embodiments, the fluid has a speed of at least 45 meters per second. In some embodiments, the fluid has a speed of at least 55 meters per second. In addition, in some embodiments, a fluid speed of at least 60 meters per second and / or 75 meters per second can be achieved. However, in some embodiments, higher speeds may be possible.

[0093] Because the fluid leaves the orifice 832 at a high rate during the compression stroke, a low pressure is generated outside the orifice plate 830. Therefore, fluid is sucked from the channel 890. In some embodiments, a significantly higher volume of fluid flow through the channel is achieved than from the bottom chamber. For example, at least five to ten times the volume of fluid pushed through the orifice 832 during the compression stroke can be entrained through the channel to flow out of the channel 890. Therefore, a macroscopic flow of the fluid can be achieved. In some embodiments, any surface is at least 5 to 10 mm from the bottom of the orifice plate to obtain the desired high entrainment. For system 800, the volume of fluid flow through the channel 890 is relatively large. In some embodiments, the flow rate of the fluid through the channel 890 is at least three to five times the flow rate through the orifice 832. In some embodiments, a higher flow rate can be achieved. In some embodiments, doubling the area of the channel results in a volume of fluid flow per unit time that is at least 6 times the fluid flow rate with a smaller channel (for example, 2× channel area results in ≥6× fluid flow rate). Thus, system 800 may more efficiently move fluid through entrainment.

[0094] During the intake stroke (when bottom fan element 820 moves away from orifice plate 830), fluid is drawn into bottom chamber 850 through orifice 832. Although fluid is drawn back through orifice 832, new fluid is drawn into the bottom chamber from orifice 832 due to the high velocity of the fluid exiting orifice 832 and the large volume of fluid entering through passage 890. Thus, system 800 entrains a large volume (and therefore a relatively large flow rate) of fluid, such as air, through passage 890 and draws (and discharges) a small volume of fluid through orifice 832.

[0095] System 800 shares the benefits of the systems described herein. System 800 can drive entrained fluid. In the illustrated embodiment, the entrained fluid can be driven in a direction substantially perpendicular to the surfaces of fan elements 810 and 820. Because two fan elements 810 and 820 are used and driven out of phase, resonant motion can be achieved. Consequently, the amplitude of vibration of fan elements 810 and 820 can be increased, and fluid flow can be enhanced. Consequently, the performance of equipment utilizing system 800 can be improved.

[0096] Figure 9 is a diagram depicting an embodiment of a system 900 that can be used as a fan. For clarity, only certain components are shown, and Figure 9 Not drawn to scale. System 900 is shown as comprising a single unit. However, multiple systems 800 may be arranged in a one-dimensional array (e.g., a line or line segment(s)) or a two-dimensional array. Thus, system 900 may also be considered a single unit within a larger cooling system that may include multiple systems 900. System 900 may be used in a mobile computing device, a non-mobile device, and / or in conjunction with other devices.

[0097] System 900 includes a bottom fan element 820. Fan element 920 can be similar to the fan elements described herein, such as fan elements 120, 220, 310, 320, 420, and / or 920. Fan 900 can have dimensions similar to those described above. Thus, fan elements 920 can each include a substrate, a piezoelectric layer, and electrodes ( Figure 8 2 ). For simplicity, leads to the fan elements and other electronic devices are not shown. The orifice plate 930 having the orifice 932 is similar to the orifice plate(s) 130, 230, 330, 430 and / or 930 having the orifices 132, 132, 232, 332, 432 and / or 832, respectively. Although a particular number, size and distribution of orifices 932 are shown, another number (including a single orifice), other size(s) and another distribution(s) of orifices may be used. In the embodiment shown, the fan elements 810 and 820 do not include orifices and / or valves. Thus, the system 900 is similar to the system 200 depicted in FIG. Also shown is a circuit for controlling the fan elements 810 and 820 in a manner similar to the system 200 depicted in FIG. Figure 9 990 in the support structure 970 for entraining a fluid (e.g., air) in the direction shown by the arrows in FIG. Although surfaces or jets for directing the entrained air from the channels 990 are not shown, such surfaces or jets may be included. Other elements are not shown or labeled.

[0098] System 900 operates in a manner similar to system 800. Thus, fan element 920 vibrates, causing fluid to be driven from chamber 950 through orifice 932. The fluid driven through orifice 932 can travel at a speed described herein (e.g., at least 30 m / s or more). Thus, a low-pressure region is formed outside of orifice plate 930 (e.g., opposite chamber 950). The low-pressure region entrains a large volume of fluid through channel 990 in a manner similar to that described above. Thus, a flow rate similar to the above-described flow rate can be achieved (e.g., at least three to five times or more of the flow rate through orifice 932).

[0099] Thus, system 900 shares some of the benefits of system 800. However, only one fan element 920 is used. As indicated by the arrows, system 900 can still entrain fluid (e.g., air) through channel 990. Thus, system 900 can be used to move fluid at a desired flow rate. Consequently, the performance of equipment employing system 900 can be improved.

[0100] Figure 10 is a diagram depicting an embodiment of a system 1000 that can be used as a fan. For clarity, only certain components are shown, and Figure 10Not drawn to scale. System 1000 is shown as including a single unit. However, multiple systems 1000 can be arranged in one or two dimensions. Because system 1000 is similar to systems 100, 200, 300, 500, 800 and 900, similar components have similar labels. In the illustrated embodiment, there are two fan elements (top fan element 1010 and bottom fan element 1020), orifice plate 1030 with orifice 1032, top chamber 1040, bottom chamber 1050, support structure 1070 and vent 1012, which are similar to top fan element 310 and bottom fan element 320, orifice plate 330 with orifice 332, top chamber 340, bottom chamber 350, support structure 370 and vent 312 respectively. Therefore, system 1000 is similar to system 300. Optional duct 1094 is also shown, which can be used for guiding fluid to channel 1090.

[0101] In the embodiment shown, fan elements 1010 and 1020 vibrate. In some embodiments, fan elements 1010 and 1020 vibrate 180 degrees out of phase. Therefore, when top fan element 1010 moves / bends away from orifice plate 1032, bottom fan element moves / bends closer to orifice plate 1030. As a result, bottom chamber 1050 is reduced in size, preventing or reducing the flow of fluid through orifice 1032. In addition, gap 1042 widens and fluid (e.g., air) is drawn into top chamber 1040. This may be referred to as a suction stroke. In a compression stroke, bottom fan element 1020 moves / bends away from orifice plate 1030, and top fan element 1010 bends toward orifice plate 1030. Therefore, system 1000 operates in a manner similar to system 300.

[0102] Fluid is driven out of orifice 1032 at a high rate. The fluid stream coming out of the orifice is shown by arrows. In some embodiments, the speed at which fluid leaves the orifice for the bottom chamber is at least 30 meters per second. In some embodiments, fluid is driven by fan elements 1010 and 1020 through orifice 1032 at a speed of at least 40 meters per second. In some such embodiments, fluid has a speed of at least 45 meters per second. In some embodiments, fluid has a speed of at least 55 meters per second. In addition, in some embodiments, a fluid speed of at least 60 meters per second and / or 75 meters per second can be achieved. However, in some embodiments, higher speeds may be possible. Fluid speeds within the range of 30 meters per second or more may be achieved in part due to the judicious selection of the diameter of the orifice in the orifice plate.

[0103] System 1000 operates in a manner similar to the above-described systems. Because the fluid leaves the orifice at a high rate, a low pressure is generated outside the orifice plate 1030. Therefore, the fluid is drawn in through channel 1090. In some embodiments, a significantly higher volume of fluid flow from channel 1090 than from chambers 1040 and 1050 is achieved. For example, at least three to five times the flow rate of the fluid pushed through orifice 1032 is entrained through channel 1090. In some embodiments, high flow rates may be possible. Therefore, macroscopic flow of the fluid may be achieved. In some embodiments, the surface is at least 5 to 10 mm from the bottom of the orifice plate to obtain the desired high entrainment. Therefore, the volume of the fluid flow through channel 1090 is relatively large. In some embodiments, doubling the area of channel 1090 results in a volume of fluid flow per unit time, i.e., the volume of fluid flow per unit time is at least 6 times the fluid flow rate with a smaller channel (e.g., 2× channel area results in ≥6× fluid flow rate). Therefore, system 1000 can move fluid more efficiently.

[0104] Thus, system 1000 shares some of the benefits of system(s) 800 and / or 900. Thus, system 1000 can be used to move fluid at a desired flow rate. Thus, the performance of equipment employing system 1000 can be improved.

[0105] Figure 11 is a diagram depicting an embodiment of a system 1100. For clarity, only certain components are shown, and Figure 11 Not drawn to scale. System 1100 is shown as including a single unit. However, multiple systems 1100 can be arranged in one or two dimensions. Because system 1100 is similar to systems 100, 200, 300, 500, 800, 900 and 1000, similar components have similar labels. In the embodiment shown, there are two fan elements (top fan element 1110 and bottom fan element 1120), orifice plate 1130 with orifice 1132, top chamber 1140, bottom chamber 1150, support structure 1170 and channel 1190, which are similar to top fan element 810 and bottom fan element 820, orifice plate 830 with orifice 832, top chamber 840, bottom chamber 850, support structure 870 and channel 890. Therefore, system 1100 is similar to system 800. Although vents are not shown, one or both of fan elements 1110 and / or 1120 may include vents / apertures.

[0106] System 1100 operates in a manner similar to the systems described above. In the illustrated embodiment, fan element(s) 1110 and / or 1120 vibrate. In some embodiments, the top and bottom fan elements vibrate 180 degrees out of phase. Thus, when the top fan element 1110 moves / bends away from the orifice plate, the bottom fan element 1120 moves / bends closer to the orifice plate 1130. Fluid is forced out of orifice 1132 at a high rate. The fluid flow from orifice 1122 is shown by arrows. In some embodiments, the velocity of the fluid leaving the orifice for the bottom chamber is at least 30 m / s. The fluid velocity achieved can be similar to the fluid velocity described above. Because the fluid leaves orifice 1132 at a high rate, a low pressure is generated outside of orifice plate 1130. Consequently, the fluid passes through channel 1190 and is drawn in through jet channel 1180. Jet channel 1180 can be used to direct the entrained flow out through orifice(s), such as aperture 1182 in jet channel 1180. In the embodiment shown, a single centrally located orifice 1182 is used. However, another number and / or (multiple) other positions of orifices may be selected. The jet channel 1180 may be used to direct entrained fluid. The fluid exiting the jet channel 1130 is indicated by an arrow. In some embodiments, the surface forming the jet channel 1130 is at least 5 to 10 mm from the bottom of the orifice plate 1130 in order to obtain the desired high entrainment. In some embodiments, a significantly higher volume of fluid flow from the channel 1190 and through the jet channel 1180 than from the chamber 1150 is achieved. For example, a flow rate of approximately the above-mentioned flow rate may be obtained. Thus, a macroscopic flow of the fluid may be achieved. Therefore, the MEMS-based fan 1100 may move the fluid more efficiently.

[0107] Thus, system 1100 shares some of the benefits of system(s) 800, 900, and / or 1000. Thus, system 1100 can be used to move fluid at a desired flow rate. Thus, the performance of equipment employing system 1100 can be improved.

[0108] Figure 12 is a diagram depicting an embodiment of system 1200. For clarity, only certain components are shown, and Figure 12Not drawn to scale. System 1200 is shown as including a single unit. However, multiple systems 1200 can be arranged in one or two dimensions. Because system 1200 is similar to systems 100, 200, 300, 500, 800, 900, 1000 and 1100, similar components have similar labels. In the embodiment shown, there are two fan elements (top fan element 1210 and bottom fan element 1220), orifice plate 1230 with orifice 1232, top chamber 1240, bottom chamber 1250, support structure 1270, channel 1290 and injection channel 1280 with aperture 1282, which are similar to top fan element 1110 and bottom fan element 1120, orifice plate 1130 with orifice 1132, top chamber 1140, bottom chamber 1150, support structure 1170, channel 1190 and injection channel 1180. Thus, system 1200 is similar to system 1100. Although vents are not shown, one or both of fan elements 1210 and / or 1220 may include vents / apertures.

[0109] System 1200 is similar to system 1100. Thus, injection channel 1280 is similar to injection channel 1180 and can be used to direct entrained fluid. Fluid exiting injection channel 1280 is shown by arrows. However, in the embodiment shown, injection channel 1280 is tapered.

[0110] System 1200 operates in a manner similar to the systems described above. Thus, entrained fluid is drawn from channel 1290 and through injection channel 1280. The angle of the taper of injection channel 1280 can be adjusted to control the flow from orifice 1232 and / or provide a desired entrained flow through injection channel 1280. Thus, a macroscopic flow of fluid (e.g., approximately the aforementioned flow rate) can be achieved and controlled. Consequently, system 1200 can more efficiently provide a desired fluid flow.

[0111] Thus, system 1200 shares some of the benefits of system(s) 800, 900, 1000, and / or 1100. Thus, system 1200 can be used to move fluids at a desired flow rate. Thus, the performance of equipment employing system 1200 can be improved.

[0112] Figure 13 is a diagram depicting an embodiment of a system 1300. For clarity, only certain components are shown, and Figure 13Not drawn to scale. System 1300 is shown as comprising a single unit. However, multiple systems 1300 may be arranged in one or two dimensions. Because system 1300 is similar to systems 100, 200, 300, 500, 800, 900, 1000, 1100, and 1200, similar components are labeled similarly. In the illustrated embodiment, there are two fan elements (top fan element 1310 and bottom fan element 1320), an orifice plate 1330 having apertures 1332 therein, a top chamber 1340, a bottom chamber 1350, a support structure 1370, a channel 1390, and an ejection channel 1380 having apertures 1382, which are similar to top fan element 1110 and bottom fan element 1120, an orifice plate 1130 having apertures 1132 therein, a top chamber 1140, a bottom chamber 1150, a support structure 1170, a channel 1190, and an ejection channel 1180 having apertures 1182. Thus, system 1300 is similar to system 1100. Although vents are not shown, one or both of fan elements 1310 and / or 1320 may include vents / apertures.

[0113] Also shown is a separator 1384, which can be used to separate the flow in injection channel 1380 into two flows. The first flow is between separator 1384 and orifice plate 1330. This flow can enter bottom chamber 1350 and be pushed out of orifice 1332 to create an entrained flow. The second flow is an entrained flow that travels between separator 1384 and the wall of injection channel 1380 through the bottom portion of injection channel 1380. As shown by the arrows, this flow can exit system 1300.

[0114] System 1300 operates in a manner similar to the systems described above. Thus, just as fan element(s) 1310 and / or 1320 are driven to vibrate (optionally out of phase), fluid is forced out of orifice 1332 at a high rate. In some embodiments, the velocity at which the fluid exits the orifice can be similar to the velocity described above. Because the fluid exits orifice 1332 at a high rate, a low pressure is generated outside of orifice plate 1330. Consequently, fluid is drawn from channel 1390 and through separate jet channels 1380. In some embodiments, a significantly higher volume of fluid flow from channel 1390 than from chamber 1350 is achieved. For example, a flow rate approximately equal to the flow rate described above can be achieved. Thus, macroscopic fluid flow can be achieved. As discussed above, the fluid in jet channels 1380 is split by separator 1384. A portion of the fluid between separator 1384 and fan element 1320 is used to drive entrainment, while the remainder flows out of jet channels 1380 as indicated by the arrows. Consequently, MEMS-based fan 1300 can move fluid more efficiently.

[0115] Thus, system 1300 shares some of the benefits of system(s) 800, 900, 1000, 1100, and / or 1200. Thus, system 1300 can be used to move fluids at a desired flow rate. Thus, the performance of equipment employing system 1300 can be improved.

[0116] Figure 14 is a diagram depicting an embodiment of system 1400. For clarity, only certain components are shown, and Figure 14 Not drawn to scale. System 1400 is shown as comprising a single unit. However, multiple systems 1400 may be arranged in one or two dimensions. Because system 1400 is similar to systems 100, 200, 300, 500, 800, 900, 1000, 1100, 1200, and 1300, similar components are labeled similarly. In the illustrated embodiment, system 1400 includes a top fan element 1410, a bottom fan element 1420, an orifice plate 1430 having apertures 1432 therein, a top chamber 1440, a bottom chamber 1450, a support structure 1470, a channel 1490 having apertures 1482, and an ejection channel 1480, which are similar to top and bottom fan elements 1110, 1120, an orifice plate 1130 having apertures 1132 therein, a top chamber 1140, a bottom chamber 1150, a support structure 1170, a channel 1190, and an ejection channel 1180 having apertures 1182. Thus, system 1400 is similar to system 1100. Although vents are not shown, one or both of fan elements 1410 and / or 1420 may include vents / apertures.

[0117] Thus, system 1400 operates in a manner similar to the systems described above, particularly system 1300. Jet channel 1480 and channel 1490 are further divided than in system 1300. Entrained fluid in channel 1490 can be drawn into chamber 1450 by actuator(s) 1410 and 1420 and forced out of orifice 1432. The fluid is forced out of orifice 1432 at a high rate. The fluid velocity achieved can be similar to the fluid velocity described above. As a result, fluid is entrained in channel 1490 and jet channel 14800. The remaining entrained flow passes through jet channel 1480. Jet channel 1480 can be used to direct the entrained fluid and can be positioned in a manner similar to that described herein. Fluid exiting jet channel 1480 is indicated by arrows. Thus, a macroscopic flow of fluid (e.g., approximately the flow rate described above) can be achieved. Consequently, system 1400 can move fluid more efficiently.

[0118] Thus, system 1400 shares some of the benefits of system(s) 800, 900, 1000, 1100, 1200, and / or 1300. Thus, system 1400 can be used to move fluids at a desired flow rate. Thus, the performance of equipment employing system 1400 can be improved.

[0119] Figure 15 is a diagram depicting an embodiment of system 1500. For clarity, only certain components are shown, and Figure 15 Not drawn to scale. System 1500 is shown as comprising a single unit. However, multiple systems 1500 may be arranged in one or two dimensions. Because system 1500 is similar to systems 100, 200, 300, 500, 800, 900, 1000, 1100, 1200, 1300, and 1400, similar components are labeled similarly. In the illustrated embodiment, system 1500 includes a top fan element 1510, a bottom fan element 1520, an orifice plate 1530 having apertures 1532 therein, a top chamber 1540, a bottom chamber 1550, a support structure 1570, a channel 1590 having apertures 1582, and an ejection channel 1580, which are similar to top and bottom fan elements 1110, 1120, an orifice plate 1130 having apertures 1132 therein, a top chamber 1140, a bottom chamber 1150, a support structure 1170, a channel 1190, and an ejection channel 1180 having apertures 1182. Thus, system 1500 is similar to system 1100. Although vents are not shown, one or both of fan elements 1510 and / or 1520 may include vents / apertures.

[0120] System 1500 is similar to system 1400 and operates in a similar manner. Thus, system 1500 includes separator 15840. In addition, injection channel 1580 includes plug 1586, only one of which is labeled. Plug 1586 can be used to moderate the flow through injection channel 1580. Also shown is a shroud 1594 that can be used to control the direction of the fluid flow to channel 1590. For example, the fluid can be directed across the top of fan element 1510. Thus, a macroscopic flow of the fluid (e.g., approximately the above-described flow rate) can be achieved. Thus, system 1500 can more efficiently move the fluid in the desired direction.

[0121] Thus, system 1500 shares some of the benefits of system(s) 800, 900, 1000, 1100, 1200, 1300, and / or 1400. Thus, system 1500 can be used to move fluids at a desired flow rate. Thus, the performance of equipment employing system 1500 can be improved.

[0122] Figure 16is a diagram depicting an embodiment of system 1600. For clarity, only certain components are shown, and Figure 16 Not drawn to scale. System 1600 is shown as comprising a single unit. However, multiple systems 1600 may be arranged in one or two dimensions. Because system 1600 is similar to systems 100, 200, 300, 500, 800, 900, 1000, 1100, 1200, 1300, 1400, and 1600, similar components are labeled similarly. In the illustrated embodiment, system 1600 includes a top fan element 1610, a bottom fan element 1620, an orifice plate 1630 having an aperture 1632 therein, a top chamber 1640, a bottom chamber 1650, a support structure 1670, a channel 1690, an ejection channel 1680 having apertures 1682, and a separator 1684, which are similar to top fan element 1310 and bottom fan element 1320, an orifice plate 1330 having apertures 1332 therein, a top chamber 1340, a bottom chamber 1350, a support structure 1370, a channel 1390, and an ejection channel 1380 having apertures 1382 and apertures 1384. Thus, system 1600 is similar to system 1300. Although vents are not shown, one or both of fan elements 1510 and / or 1520 may include vents / apertures. System 1600 also includes a cascade unit. Thus, system 1600 includes fan elements 1610A and 1620A, duct 1690A, top chamber 1640A, bottom chamber 1650A, and separator 1684A, which are similar to fan elements 1610 and 1620 , duct 1690 , top chamber 1640 , bottom chamber 1650 , and separator 1684 .

[0123] Fan elements 1610A, 1610B, 1680A, and / or 1680B vibrate. In some embodiments, paired fan elements (1610A and 1620A, 1610 and 1620) vibrate 180 degrees out of phase. Thus, when top actuator 1610 / 1610A moves / bends away from orifice plate 1630, bottom actuator 1620 / 1620A moves / bends closer to orifice plate 1630. As a result, fluid is entrained in channels 1690 and 1690A. Jet channel 1680 can be used to direct the entrained fluid. Fluid exiting jet channel 1680 through aperture 1682 is indicated by arrows.

[0124] System 1600 is a cascade architecture. Each stage in the cascade includes a system similar to system 1300. However, other configurations may be used. In the illustrated embodiment, the fan elements are aligned in the cascade. In some embodiments, the fan elements in the cascade may be offset. System 1600 operates in a manner similar to the above-described systems. However, the use of cascade actuators allows the entrained fluid flow rate and / or pressure to be customized. Thus, a macroscopic flow of fluid (e.g., approximately the aforementioned flow rate) can be achieved. Consequently, system fan 1600 can move fluid more efficiently.

[0125] Thus, system 1600 shares some of the benefits of system(s) 800, 900, 1000, 1100, 1200, 1300, 1400, and / or 1500. Thus, system 1600 can be used to move fluids at a desired flow rate. Thus, the performance of equipment employing system 1600 can be improved.

[0126] Figure 17 is a diagram depicting an embodiment of a system 1700 that can be used as a fan. For clarity, only certain components are shown, and Figure 17 Not drawn to scale. System 1700 is shown as comprising a single unit. However, multiple systems 1700 may be arranged in a one-dimensional array (e.g., a line or line segment(s)) or a two-dimensional array. Thus, system 1700 may also be considered a single unit within a larger cooling system that may include multiple systems 1700. System 1700 may be used in a mobile computing device, a non-mobile device, and / or in conjunction with other devices.

[0127] System 1700 includes a bottom fan element 1720. Fan element 1720 can be similar to the fan elements described herein, such as fan elements 120, 220, 310, 320, 420, 820, 920, 1020, 1120, 1220, 1320, 1420, 1520, and 1620. Fan 1700 can have dimensions similar to those described above. Thus, fan element 1720 can include a substrate, a piezoelectric layer, and electrodes ( Figure 17132, 1332, 1432, 1530, and / or 1630, respectively. Although a particular number, size, and distribution of orifices 1732 are shown, another number (including a single orifice or multiple orifices), another size(s), and another distribution(s) of orifices may be used. System 1700 is similar to system 100 depicted in FIG. 1 and Figure 6 The system 600 is depicted in FIG. The orifice plate 1730 is located near the tip of the fan element 1720. Also shown are the channels 1790 in the support structure 1770 and the channels for Figure 17 Small holes 1792 in the side wall 1774 entrain fluid (e.g., air) in the direction shown by the arrows in FIG.

[0128] System 1700 operates in a manner similar to systems 100 and 600. Thus, fan element 1720 vibrates, as indicated by Figure 17 1732 and enter the injection channel 1780. The fluid driven by the orifice 1732 can travel at the speed described herein (e.g., at least 30 m / s or more). Therefore, a low-pressure area is formed outside the orifice plate 1730 in the injection channel 1780 (e.g., opposite to the chamber 1750). The low-pressure area entrains a large volume of fluid through the channel 1790 in a manner similar to that described above. Therefore, a flow rate similar to the above-mentioned flow rate can be achieved through the channel 1790 (e.g., at least three to five times or more of the flow rate through the orifice 1732). The fluid also travels through the injection channel 1780 and leaves via the orifice 1792.

[0129] Thus, system 1700 shares some of the benefits of system(s) 800, 900, 1000, 1100, 1200, 1300, 1400, 1500, and / or 1600. Thus, system 1700 can be used to move fluids at a desired flow rate. Thus, the performance of equipment employing system 1700 can be improved.

[0130] Figure 181 is a flow chart illustrating an embodiment of a method 1800 for driving an active fan element in a mobile device. Method 1800 may include steps not depicted for simplicity. Method 1800 is described in the context of system 700. However, method 1800 may be used with other systems, including but not limited to the systems and units described herein.

[0131] At 1802, one or more of the fan elements in the system are activated to vibrate. At 1802, an electrical signal having a desired frequency is used to drive the fan element(s). In some embodiments, at 1802, the fan elements are driven at or near their structural and / or acoustic resonance frequencies. For example, for system 700, the drive frequency may be 15 kHz or higher (e.g., at least 20 kHz). If multiple fan elements are driven at 1802, the fan elements may be driven out of phase. In some embodiments, the fan elements are driven substantially 180 degrees out of phase. For example, a fan element may vibrate in a direction opposite to that of an adjacent fan element. In some embodiments, each fan element is driven out of phase. For example, different portions of a fan element may be driven to vibrate in opposite directions. Also at 1802, the fan elements are driven so that the fluid exiting the orifice has a high velocity, for example, within the ranges described herein. This creates a low pressure at the orifice plate, drawing fluid through the channel.

[0132] At 1804, feedback from the piezoelectric fan element(s) is used to adjust the drive current. In some embodiments, the adjustment is used to maintain the frequency at or near the acoustic and / or structural resonant frequency of the fan element(s) and / or system. The resonant frequency of a particular fan element may drift, for example, due to changes in temperature. The adjustment performed at 1804 allows for accounting for drift in the resonant frequency.

[0133] For example, at 1802, the fan element(s) in the system 700 (e.g., unit 600) may be driven at one or more of its structural resonant frequencies. This resonant frequency may also be equal to or close to the acoustic resonant frequency for the chamber 650. At 1804, feedback is used to maintain the fan element(s) of the system 700 at resonance, and in some embodiments where multiple fan elements are driven, 180 degrees out of phase. Thus, the efficiency of the fan element(s) in driving the fluid through the system 700 may be maintained. In some embodiments, 1804 includes sampling the current through the fan element(s) and regulating the current to maintain resonance and low input power. As a result, a high velocity through the orifice 632 may be achieved, and a large volume of fluid may be drawn through the channel 690.

[0134] Thus, systems such as system(s) 600, 700, 800, 900, 1000, 1100, 1200, 1300, 1400, 1500, 1600, and / or 1700 may be operated to drive fluid flow at a desired flow rate. Thus, performance of an apparatus employing method 1800 may be improved.

[0135] Although the foregoing embodiments have been described in some detail for purposes of clarity of understanding, the invention is not limited to the details provided. There are many alternative ways of implementing the invention. The disclosed embodiments are illustrative, not restrictive.

Claims

1. A system comprising: an orifice plate having at least one orifice therein; a fan element configured to undergo a vibratory motion to drive fluid through the at least one orifice; and at least one passage through which the fluid is drawn in response to the fluid being driven through the at least one orifice; wherein the vibratory motion driving the fluid through the orifice provides a low pressure region proximate the orifice plate, and in response to the low pressure region forming, the fluid is drawn through the at least one channel.

2. The system according to claim 1, further comprising: A support structure is provided, the fan element including a plurality of edges, at least one of the plurality of edges being anchored to the support structure such that an edge of the plurality of edges is free to vibrate.

3. The system according to claim 2, wherein: The channel is bounded by the fan element, wherein the orifice plate is adjacent to the edge.

4. The system according to claim 3, wherein: The fluid flows substantially parallel to the surface of the fan element.

5. The system according to claim 1, wherein: The fan element comprises a plurality of anchored edges such that a central portion of the fan element undergoes the vibratory motion.

6. The system according to claim 5, further comprising: A jet channel through which the fluid flows in a direction substantially perpendicular to the jet channel.

7. The system according to claim 6, wherein: The edge of the jet channel is formed by a jet channel wall having an aperture therein, the channel and the jet channel being configured such that the fluid is driven through the aperture.

8. The system according to claim 5, further comprising: An additional fan element comprising an additional plurality of anchoring sides causes an additional central portion of the additional fan element to experience additional vibratory motion.

9. The system according to claim 8, wherein: The additional oscillatory motion of the additional fan element is out of phase with the oscillatory motion of the fan element.

10. A system comprising: a plurality of units, each of the plurality of units comprising an orifice plate having at least one orifice therein, a fan element, and at least one channel, the orifice plate having at least one orifice therein, the fan element being configured to undergo a vibratory motion to drive a fluid through the at least one orifice, the fluid being drawn through the at least one channel in response to the fluid being driven through the at least one orifice, wherein the vibratory motion driving the fluid through the orifice provides a low pressure region proximate the orifice plate, and in response to the low pressure region forming, the fluid is drawn through the at least one channel.

11. The system according to claim 10, wherein: Each of the plurality of units further comprises: A support structure is provided, the fan element including a plurality of edges, at least one of the plurality of edges being anchored to the support structure such that an edge of the plurality of edges is free to vibrate.

12. The system according to claim 11, wherein The channel is bounded by the fan element, wherein the orifice plate is adjacent to the edge.

13. The system according to claim 12, wherein: The fluid flows substantially parallel to the surface of the fan element.

14. The system according to claim 10, wherein: The fan element comprises a plurality of anchored edges such that a central portion of the fan element undergoes the vibratory motion.

15. The system of claim 14, further comprising: A jet channel through which the fluid flows in a direction substantially perpendicular to the jet channel.

16. The system according to claim 10, wherein: The plurality of units share the orifice plate.

17. A method comprising: driving the fan element to undergo vibratory motion to drive a fluid through at least one orifice of the orifice plate, the fluid being drawn through at least one passageway in response to the fluid being driven through the at least one orifice; and Using feedback to control the frequency of the vibratory motion, wherein the vibratory motion driving the fluid through the orifice provides a low pressure region proximate the orifice plate, and in response to the low pressure region forming, the fluid is drawn through the at least one channel.

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