Piezoelectric fan and electronic device

Abstract

The application relates to the technical field of piezoelectric fans, in particular to a piezoelectric fan and electronic equipment. The piezoelectric fan comprises a shell, a piezoelectric vibration assembly, a deformation piece and a first piezoelectric piece, the deformation piece is connected with the shell and cooperates with the shell to form a gas chamber, one of the deformation piece and the shell is provided with a gas passage hole communicating with the gas chamber, the first piezoelectric piece is arranged on the deformation piece, the first piezoelectric piece can drive the deformation piece to vibrate, so that the gas chamber inhales or exhales through the gas passage hole; the gas passage hole comprises an inner transition part, a throat part and an outer transition part which are sequentially distributed and connected from the inside to the outside of the gas chamber, the flow area of the inner transition part gradually decreases from the inside to the outside, the flow area of the throat part remains unchanged, and the flow area of the outer transition part gradually increases from the inside to the outside, so as to form a Venturi flow channel. The piezoelectric fan and the electronic equipment disclosed by the application can improve the heat dissipation effect of a heat source.

Description

Technical Field

[0001] This application relates to the field of piezoelectric fan technology, and more particularly to a piezoelectric fan and electronic device. Background Technology

[0002] A piezoelectric fan is an active heat dissipation device that drives airflow based on the inverse piezoelectric effect. Its core driving element is a piezoelectric oscillator made of materials such as piezoelectric ceramics or piezoelectric films. When an alternating voltage is applied to the piezoelectric oscillator, the oscillator will generate high-frequency reciprocating deformation, disturbing the surrounding air to form a directional convective airflow, thereby carrying away heat from the surface of the heat source and achieving the functions of heat dissipation and ventilation.

[0003] However, existing piezoelectric fans are not ideal for cooling heat sources. Summary of the Invention

[0004] This application discloses a piezoelectric fan and electronic device that can improve the heat dissipation effect on heat sources.

[0005] To achieve the above objectives, in a first aspect, embodiments of this application disclose a piezoelectric fan, comprising: case; A piezoelectric vibration assembly includes a deformable element and a first piezoelectric element. The deformable element is connected to the housing and cooperates with the housing to form a gas chamber. One of the deformable element and the housing is provided with a vent hole communicating with the gas chamber. The first piezoelectric element is disposed on the deformable element and can drive the deformable element to vibrate so that the gas chamber can draw in or exhaust air through the vent hole. The vent includes an inner transition section, a throat, and an outer transition section that are sequentially distributed and connected relative to the gas chamber from the inside to the outside. The flow area of ​​the inner transition section gradually decreases from the inside to the outside, the flow area of ​​the throat remains unchanged from the inside to the outside, and the flow area of ​​the outer transition section gradually increases from the inside to the outside to form a Venturi channel.

[0006] In one optional embodiment, the length of the throat is 0.03 mm to 0.13 mm; and / or, The ratio of the length of the inner transition portion to the length of the throat is 1.5 to 3, and the ratio of the length of the outer transition portion to the length of the throat is 1.5 to 3.

[0007] In one optional embodiment, the ratio of the flow area of ​​the inner opening of the inner transition portion to the flow area of ​​the throat is 2 to 6; and / or, The ratio of the flow area of ​​the outer opening of the outer transition section to the flow area of ​​the throat is 2 to 6.

[0008] In one optional embodiment, the piezoelectric fan further includes a heat spreader connected to the housing, the heat spreader being disposed opposite to the vent along the axial direction of the vent, and the heat spreader being used to fit against a heat source.

[0009] In one alternative embodiment, the piezoelectric fan further includes a heat sink disposed on the side of the heat spreader facing the vent.

[0010] In one optional embodiment, a heat exchange channel is formed within the heat sink, the heat exchange channel having an air inlet and an air outlet, the air inlet being located at the end of the heat sink away from the heat spreader, and the air outlet being located at the end of the heat sink close to the heat spreader.

[0011] In one alternative embodiment, the heat exchange channel is provided with a flow guiding structure configured to suppress the backflow of gas entering the heat exchange channel from the air inlet.

[0012] In one optional embodiment, the flow guiding structure includes a main flow channel and a bypass flow channel. The bypass flow channel has a first connection port and a second connection port, both of which are connected to the main flow channel. Along the return direction of the main flow channel, the first connection port is located upstream of the second connection port. The direction of the return gas in the bypass channel at the first connection port is the first direction, and the direction of the return gas in the bypass channel at the second connection port is the second direction. The return flow direction of the portion of the main channel connected to the first connecting port is a third direction, and the return flow direction of the portion of the main channel connected to the second connecting port is a fourth direction. The angle between the first direction and the third direction is less than 90 degrees, and the angle between the second direction and the fourth direction is greater than 90 degrees.

[0013] In one optional embodiment, the outer peripheral surface of the heat sink is provided with a plurality of spaced grooves.

[0014] In one optional embodiment, the air outlet is located on the side wall of the heat sink, and the air outlet penetrates the end face of the heat sink near the heat spreader; and / or, The heat exchange channel extends through the end face of the heat sink away from the heat spreader to form the air inlet.

[0015] In one optional embodiment, the number of heat dissipation components includes a plurality of heat dissipation components, which are spaced apart on the side of the heat spreader facing the vent, and the area enclosed by the outermost heat dissipation component is a first area. The number of vent holes includes multiple vent holes, which are distributed at intervals on the deformable part or the housing. The area enclosed by the outermost vent hole among the multiple vent holes is the second area. The first region and the second region are arranged opposite each other along the axial direction of the vent hole, and the outer edge of the first region extends beyond the outer edge of the second region in a direction perpendicular to the axial direction of the vent hole.

[0016] In one optional embodiment, the piezoelectric fan further includes a connector, through which the heat spreader and the housing are connected. The connector is a telescopic structure to adjust the distance between the heat spreader and the housing.

[0017] In one optional embodiment, the housing has a deformable portion that forms part of the gas chamber, and the piezoelectric fan further includes a second piezoelectric element disposed on the deformable portion for driving the deformable portion to vibrate; and / or, The vent is located in the housing and is positioned opposite to the deformable part along its own axial direction.

[0018] Secondly, this application provides an electronic device including the piezoelectric fan described in any of the above embodiments.

[0019] Compared with related technologies, the beneficial effects of this application are: When the piezoelectric fan of this application exhausts gas, the gas is squeezed into the vent. The airflow first passes through the inner transition section. Since the flow area of ​​the inner transition section gradually decreases from the inside to the outside, the airflow is accelerated and initially converged and rectified here. Then the airflow enters the throat, where it reaches the highest flow velocity. After that, it enters the outer transition section, where static pressure is restored, reducing energy loss. This allows the exhaust airflow to be directed to the core heating area of ​​the heat source in a highly concentrated, high-speed bundle shape, avoiding the dissipation of a large amount of airflow to the surrounding non-target space, improving the heat exchange efficiency between the airflow and the heat source, and thus improving the overall heat dissipation performance of the piezoelectric fan.

[0020] During inhalation, gas is drawn into the vent. The airflow first passes through the outer transition section. As the flow area of ​​the outer transition section gradually decreases from the outside to the inside, the airflow is accelerated and initially converged and rectified. Then the airflow enters the throat, where the negative pressure is the lowest, which produces a suction effect, thereby drawing in additional surrounding still air and increasing the intake volume. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a schematic diagram of the structure of the piezoelectric fan disclosed in the embodiments of this application, and an enlarged schematic diagram of point A therein; Figure 2 This is an explosion diagram of the piezoelectric fan disclosed in an embodiment of this application; Figure 3 This is a schematic diagram of the fluid flow during air intake of the piezoelectric fan disclosed in the embodiments of this application; Figure 4 This is a schematic diagram of the fluid flow during exhaust of a piezoelectric fan disclosed in an embodiment of this application; Figure 5 This is a schematic diagram of the structure of a piezoelectric fan disclosed in another embodiment of this application; Figure 6 This is a schematic diagram of the structure of a piezoelectric fan disclosed in another embodiment of this application; Figure 7 This is a schematic diagram of the heat exchange channel structure disclosed in the embodiments of this application; Figure 8 This is a velocity cloud diagram of the gas in the heat exchange channel disclosed in the embodiments of this application during forward flow; Figure 9 This is a velocity cloud diagram of the gas in the heat exchange channel during reflux, as disclosed in the embodiments of this application.

[0023] Explanation of reference numerals in the attached figures: 100. Shell; 110. Frame; 120. Sealing plate; 121. Deformation part; 200, piezoelectric vibration assembly; 201, gas chamber; 202, vent; 203, inner transition section; 204, throat; 205, outer transition section; 210, deformable element; 220, first piezoelectric element; 300, Heat exchanger; 301, First connection port; 302, Second connection port; 310, Heat exchange channel; 320, Main flow channel; 330, Bypass flow channel; 400. Heat sink components; 500, Second piezoelectric element; 510, Clearance hole; 600. Connectors; 710. Fixing plate; 720. Pad. Detailed Implementation

[0024] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0025] In this application, the terms "upper," "lower," "left," "right," "front," "rear," "top," "bottom," "inner," "outer," "vertical," "horizontal," "lateral," and "longitudinal" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are primarily for the purpose of better describing this application and its embodiments, and are not intended to limit the indicated device, element, or component to having a specific orientation, or to be constructed and operated in a specific orientation.

[0026] Furthermore, in addition to indicating location or positional relationship, some of the aforementioned terms may also have other meanings. For example, the term "above" may also be used in some cases to indicate a certain dependency or connection relationship. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0027] Furthermore, the terms "installation," "setup," "equipped with," "connection," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral structure; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium, or an internal connection between two devices, components, or parts. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0028] Furthermore, the terms "first," "second," etc., are primarily used to distinguish different devices, components, or parts (which may be the same or different in specific type and construction), and are not intended to indicate or imply the relative importance or quantity of the indicated devices, components, or parts. Unless otherwise stated, "a plurality of" means two or more.

[0029] A piezoelectric fan is an active heat dissipation device that drives airflow based on the inverse piezoelectric effect. Its core driving element is a piezoelectric oscillator made of materials such as piezoelectric ceramics or piezoelectric films. When an alternating voltage is applied to the piezoelectric oscillator, the oscillator will generate high-frequency reciprocating deformation, disturbing the surrounding air to form a directional convective airflow, thereby carrying away heat from the surface of the heat source and achieving the functions of heat dissipation and ventilation.

[0030] However, existing piezoelectric fans are not ideal for cooling heat sources.

[0031] The inventors discovered that this type of piezoelectric fan is equipped with a gas chamber. When the piezoelectric oscillator deforms, it can periodically expand or contract the volume of the gas chamber, thereby completing the intake and exhaust of gas through the vent of the gas chamber. The vents of existing piezoelectric fans mostly adopt a straight through-hole structure with equal diameter. The airflow jet emitted through the vent has a large divergence angle and insufficient concentration, and cannot be directed to the core heating area of ​​the heat source. A large amount of airflow escapes to the surrounding non-target space, and only a small amount of high-speed airflow acts on the surface of the heat source. As a result, the heat of the heat source cannot be carried away by the airflow quickly, ultimately resulting in poor heat dissipation performance.

[0032] The piezoelectric fan and electronic device provided in this application will be described in detail below with reference to the accompanying drawings and through specific embodiments and application scenarios.

[0033] like Figures 1 to 4 As shown in the figure, this application discloses a piezoelectric fan, including a housing 100 and a piezoelectric vibration assembly 200. The housing 100 is the basic support structure of the piezoelectric fan. For example, the length and width of the piezoelectric fan can be 5mm to 15mm. Different length and width dimensions of the piezoelectric fan can be selected. For example, the length and width of the piezoelectric fan can be 5mm×5mm or 6mm×8mm, respectively, for use in portable chip heat dissipation and camera heat dissipation; another example is that the length and width of the piezoelectric fan can be 8mm×10mm or 10mm×12mm, respectively, for use in mobile phone SOC heat dissipation and micro power amplifier heat dissipation; yet another example is that the length and width of the piezoelectric fan can be 12mm×15mm, respectively, for use in industrial micro MCU heat dissipation and power device heat dissipation.

[0034] The height of the piezoelectric fan can range from 5mm to 20mm. Depending on the height of the piezoelectric fan selected, for example, a height of 5-8mm can be used for side heat dissipation of curved screens or under-screen heat dissipation; another example is a height of 9-14mm, which is used for side heat dissipation of the motherboard; and yet another example is a height of 15-20mm, which is used for heat dissipation of high-power micro power chips.

[0035] For example, the piezoelectric fan may also include a pad 720 and a mounting plate 710, with the housing 100 mounted on the mounting plate 710 via the pad 720. The mounting plate 710 can be installed in a preset mounting position, thereby realizing the installation of the piezoelectric fan.

[0036] The piezoelectric vibration assembly 200 includes a deformable element 210 and a first piezoelectric element 220. The deformable element 210 is connected to the housing 100 and cooperates with the housing 100 to form a gas chamber 201. For example, a cavity can be formed inside the housing 100, and the deformable element 210 closes the cavity to form the gas chamber 201. The deformable element 210 is a thin plate-like or membrane-like component that can be elastically deformed, and its material can be metal, resin, or composite material, etc. The connection method between the deformable element 210 and the housing 100 can be bonding, welding, snap-fitting, or screw fastening, etc.

[0037] One of the deformable element 210 and the housing 100 is provided with a vent 202 that communicates with the gas chamber 201. A first piezoelectric element 220 is provided on the deformable element 210. The first piezoelectric element 220 can drive the deformable element 210 to vibrate, causing the volume of the gas chamber 201 to expand and contract periodically, so that the gas chamber 201 can draw in or exhaust air through the vent 202, forming a stable heat dissipation airflow.

[0038] Specifically, the first piezoelectric element 220 is made of inverse piezoelectric material such as piezoelectric ceramic or piezoelectric film. When an alternating voltage is applied to the first piezoelectric element 220, it undergoes expansion and contraction deformation based on the inverse piezoelectric effect. Since the first piezoelectric element 220 and the deformation element 210 are integrated, their composite structure will generate macroscopic bending vibration, i.e., drive the deformation element 210 to generate high-frequency reciprocating deformation. For example, the first piezoelectric element 220 may include a piezoelectric ceramic layer and electrode layers disposed on both sides of the piezoelectric ceramic layer. The thickness of the piezoelectric ceramic layer of the first piezoelectric element 220 can be 0.08 mm to 0.20 mm, for example, the thickness of the piezoelectric ceramic layer of the first piezoelectric element 220 can be selected as 0.12 to 0.15 mm, and the material is PZT-5A; or the thickness of the piezoelectric ceramic layer of the first piezoelectric element 220 can be selected as 0.08 to 0.11 mm, and the material is PZT5. The electrode layer can be a thin film made of materials such as aluminum, titanium, copper, and gold, with a thickness of 0.005~0.015mm, fully covering both sides of the piezoelectric ceramic layer, with a 0.2mm insulating seal left at the edge.

[0039] The reciprocating deformation of the deformable element 210 causes the volume of the gas chamber 201 to periodically expand and contract. When the deformable element 210 deforms away from the gas chamber 201, the volume of the gas chamber 201 expands, the internal air pressure decreases, and external gas is drawn into the gas chamber 201 through the vent 202. When the deformable element 210 deforms towards the gas chamber 201, the volume of the gas chamber 201 shrinks, the internal air pressure increases, and the gas in the gas chamber 201 is discharged through the vent 202. This cycle repeats, with the vent 202 alternately performing the actions of intake and exhaust.

[0040] To address the problem of airflow divergence and insufficient concentration caused by uniform diameter straight through-holes in existing technologies, the vent 202 of this application has a special Venturi flow channel configuration. Specifically, the vent 202 includes an inner transition portion 203, a throat 204, and an outer transition portion 205, which are sequentially distributed and connected relative to the gas chamber 201 from the inside out. The direction from the inside out is: starting from the inside of the gas chamber 201 and pointing towards the outside of the gas chamber 201. For example, the cross-sectional shape of the vent 202 can be circular, square, hexagonal, etc.

[0041] The flow area of ​​the inner transition section 203 gradually decreases from the inside to the outside. The large end of the inner transition section 203 faces the inside of the gas chamber 201, and the small end of the inner transition section 203 is connected to the throat 204. The inner transition section 203 forms a contracting flow channel from the inside to the outside. The flow area of ​​the throat 204 remains unchanged from the inside to the outside, that is, the throat 204 is a flow channel section with a constant cross section, which constitutes the area with the smallest flow area in the vent 202 and forms the highest flow velocity area in the entire Venturi flow channel. The airflow is constrained here into a high-speed, concentrated jet core, which can suppress the disorderly diffusion of airflow inside the channel. The flow area of ​​the outer transition section 205 gradually increases from the inside to the outside to form a Venturi flow channel.

[0042] When the piezoelectric fan of this application exhausts gas, the gas is squeezed into the vent 202. The airflow first passes through the inner transition section 203. Since the flow area of ​​the inner transition section 203 gradually decreases from the inside to the outside, the airflow is accelerated and initially converged and rectified. Then the airflow enters the throat 204, where it reaches the highest flow velocity. After that, it enters the outer transition section 205, where static pressure is restored, reducing energy loss. This allows the exhaust airflow to converge in a highly concentrated, high-speed bundle shape to the core heating area of ​​the heat source, preventing a large amount of airflow from escaping to the surrounding non-target space. This improves the heat exchange efficiency between the airflow and the heat source, thereby enhancing the overall heat dissipation performance of the piezoelectric fan.

[0043] During inhalation, gas is drawn into the vent 202. The airflow first passes through the outer transition section 205. As the flow area of ​​the outer transition section 205 gradually decreases from the outside to the inside, the airflow is accelerated and initially converged and rectified. Subsequently, the airflow enters the throat 204. The negative pressure in the throat 204 is minimal, which will produce a suction effect, thereby drawing in additional surrounding still air and increasing the intake volume.

[0044] It should be noted that the throat 204 in this application is crucial for maintaining airflow stability. If the throat 204 is omitted and only the inner transition section 203 and the outer transition section 205 are provided, the flow channel cross-section will change abruptly. During exhaust, the airflow will directly rush from the smallest cross-section of the inner transition section 203 into the wide flow channel of the outer transition section 205, causing the airflow to spread rapidly and form violent vortices. Most of the dynamic pressure will be converted into heat energy dissipation, resulting in serious kinetic energy loss. Similarly, during intake, the airflow will directly rush from the smallest cross-section of the outer transition section 205 into the wide flow channel of the inner transition section 203, which will also generate violent vortices and energy dissipation due to the abrupt change in cross-section. In other words, the throat 204 in this application can provide a stable flow channel with a constant flow area for high-speed airflow, so as to avoid flow field distortion and kinetic energy waste caused by abrupt changes in cross-section.

[0045] In summary, this application not only increases the air intake volume of the piezoelectric fan and improves its overall heat dissipation performance, but also provides a stable flow channel with a constant flow area for high-speed airflow, effectively avoiding flow field distortion and kinetic energy waste caused by abrupt changes in cross-section.

[0046] In one optional embodiment, the length of the throat 204 is 0.03 mm to 0.13 mm. For example, the length of the throat 204 can be 0.04 mm, 0.06 mm, 0.07 mm, 0.08 mm, 0.09 mm, 0.11 mm, 0.12 mm, etc., and this application does not limit it.

[0047] If the length of the throat 204 is less than 0.03 mm, the airflow may not be able to form a stable high-speed jet when passing through, and flow field oscillation may occur; if the length of the throat 204 is greater than 0.13 mm, although the airflow can be sufficiently accelerated, the airflow will generate strong viscous friction with the wall when flowing in the narrow channel, resulting in friction loss along the way.

[0048] Therefore, in this embodiment, the length of the throat 204 is controlled between 0.03 mm and 0.13 mm, which not only forms a stable high-speed jet in the throat 204, but also reduces the friction loss of the airflow.

[0049] For example, the length of the inner transition portion 203 can be 0.09 mm to 0.21 mm, and the length of the outer transition portion 205 can be 0.09 mm to 0.21 mm. Specifically, the length of the inner transition portion 203 can be 0.12 mm, 0.15 mm, 0.18 mm, 0.2 mm, etc., and the length of the outer transition portion 205 can be 0.12 mm, 0.15 mm, 0.18 mm, 0.2 mm, etc.

[0050] In one optional embodiment, the ratio of the length of the inner transition portion 203 to the length of the throat 204 is 1.5 to 3, and the ratio of the length of the outer transition portion 205 to the length of the throat 204 is 1.5 to 3. For example, the ratio of the length of the inner transition portion 203 to the length of the throat 204 can be 1.6, 1.8, 2.0, 2.1, 2.5, 2.8, 2.9, etc.; and the ratio of the length of the outer transition portion 205 to the length of the throat 204 can be 1.6, 1.8, 2.0, 2.1, 2.5, 2.8, 2.9, etc.

[0051] If the ratio of the length of the inner transition section 203 to the length of the throat 204 is less than 1.5, the inner transition section 203 is relatively short, and the change in the flow area of ​​the channel is too drastic. When the airflow contracts or expands rapidly, boundary layer separation is very likely to occur, generating local eddies and adverse pressure gradients, leading to kinetic energy dissipation and airflow blockage. If the ratio of the length of the inner transition section 203 to the length of the throat 204 is greater than 3, the inner transition section 203 will be relatively long. Although the cross-sectional change is gradual, the contact area between the airflow and the wall increases significantly, increasing the friction loss of the gas.

[0052] Therefore, controlling the ratio of the length of the inner transition section 203 to the length of the throat 204 to 1.5~3 can not only prevent kinetic energy loss, but also reduce the gas friction loss.

[0053] Similarly, by controlling the ratio of the length of the outer transition portion 205 to the length of the throat 204 to 1.5~3, not only can internal kinetic energy loss be prevented, but also the gas friction loss can be reduced.

[0054] In one optional embodiment, the ratio of the flow area of ​​the inner opening of the inner transition portion 203 to the flow area of ​​the throat 204 is 2 to 6. For example, the ratio of the flow area of ​​the inner opening of the inner transition portion 203 to the flow area of ​​the throat 204 can be 3, 4, 5, etc., and this application does not limit it to this.

[0055] If the ratio is less than 2, the difference in cross-sectional area between the inner opening and the throat 204 is not large enough, the pressure difference formed by the gas flowing through the inner transition section 203 is small, the effect of driving the airflow to accelerate is not ideal, and the conversion efficiency of pressure energy to kinetic energy is low; if the ratio is greater than 6, the cross-sectional contraction of the inner transition section 203 is too drastic, the effect of the airflow adhering to the wall when converging rapidly is poor, and boundary layer separation and local eddies are easily generated before the throat 204 inlet, resulting in energy dissipation.

[0056] Therefore, in this embodiment, the ratio of the flow area of ​​the inner opening of the inner transition section 203 to the flow area of ​​the throat 204 is controlled at 2 to 6, which can increase the conversion efficiency of pressure energy to kinetic energy and reduce the energy dissipation when the airflow passes through the inner transition section 203.

[0057] In one optional embodiment, the ratio of the flow area of ​​the outer opening of the outer transition portion 205 to the flow area of ​​the throat 204 is 2 to 6. For example, the ratio of the flow area of ​​the outer opening of the outer transition portion 205 to the flow area of ​​the throat 204 can be 3, 4, 5, etc., and this application does not limit it to this.

[0058] If the ratio is less than 2, the outer opening is not wide enough, the back pressure on the airflow is large when it is discharged, the flow velocity decays quickly, and the penetration of the concentrated gas beam is insufficient. If the ratio is greater than 6, the cross-section expands rapidly over a short distance, and the high-speed airflow may undergo flow separation at the expansion wall, generating turbulence and backflow vortices, which will weaken the flow velocity of the gas and generate airflow noise.

[0059] Therefore, in this embodiment, the ratio of the flow area of ​​the outer opening of the outer transition portion 205 to the flow area of ​​the throat 204 is controlled at 2 to 6, which not only ensures the concentration and penetration of the airflow, but also ensures the flow speed of the gas and prevents the generation of airflow noise.

[0060] In one alternative embodiment, please refer to Figure 1 The piezoelectric fan also includes a heat spreader 300, which is connected to the housing 100. For example, the heat spreader 300 can be connected to the housing 100 via a connector 600 such as a spring screw. The heat spreader 300 and the vent 202 are arranged opposite each other along the axial direction of the vent 202, and the heat spreader 300 is used to fit in contact with the heat source. For example, the heat spreader 300 can be plate-shaped, such as a vacuum chamber heat spreader, a graphene heat spreader, or a phase change material heat spreader.

[0061] In this embodiment, the piezoelectric fan includes a heat spreader 300. In practical applications, the heat spreader 300 is in contact with the heat source. The heat generated by the heat source is first conducted to the heat spreader 300, which is in close contact with it. The heat spreader 300 can quickly and evenly diffuse the concentrated heat of the heat source to the entire surface of the heat spreader 300, thereby playing a role in temperature equalization and effectively preventing the formation of hot spots due to heat accumulation in the heat source.

[0062] Meanwhile, since the heat spreader 300 and the vent 202 are arranged axially opposite each other, the high-concentration, high-speed airflow discharged by the piezoelectric fan through the vent 202 can directly and comprehensively act on the surface of the heat spreader 300. The high-speed airflow exchanges heat on the surface of the heat spreader 300, carrying away a large area of ​​uniform heat, thereby further improving the heat dissipation efficiency of the heat source.

[0063] In one alternative embodiment, please refer to Figure 1The piezoelectric fan also includes a heat sink 400, which is disposed on the side of the heat spreader 300 facing the vent 202, i.e., the heat sink 400 is located on the windward side of the heat spreader 300. For example, the heat sink 400 can be made of a high thermal conductivity material, and the heat sink 400 can be a plurality of spaced heat dissipation fins, heat dissipation columns, or microchannel structures, etc.

[0064] In practical applications, the heat generated by the heat source is first conducted to the heat spreader 300. After the heat spreader 300 evenly diffuses the concentrated heat, it is further conducted to the heat dissipation component 400 located on its surface. Since the heat dissipation component 400 has a structure that extends to the vent 202, it can increase the contact area with the surrounding air, thereby expanding the effective heat dissipation area. Combined with the high-speed airflow ejected from the vent 202, it can further improve the heat dissipation efficiency of the heat source.

[0065] In one alternative embodiment, please refer to Figure 4 and Figure 7 The heat exchanger 400 has a heat exchange channel 310, which has an air inlet and an air outlet. The air inlet is located at the end of the heat exchanger 400 away from the heat spreader 300, that is, at the front end of the heat exchanger 400 in the airflow jet direction. The air outlet is located at the end of the heat exchanger 400 close to the heat spreader 300, that is, at the root region where the heat exchanger 400 and the heat spreader 300 meet.

[0066] In this embodiment, when the highly concentrated, high-speed airflow discharged by the piezoelectric fan through the vent 202 impacts the heat sink 400, the airflow naturally splits: one part of the airflow flows along the outer surface of the heat sink 400, forming an external heat exchange path; the other part of the airflow rushes into the heat exchange channel 310 from the front air inlet and is discharged from the air outlet near the root of the heat spreader 300, forming an internal heat exchange path. The dual internal and external heat exchange paths allow the inner and outer surfaces of the heat sink 400 to be simultaneously subjected to the high-speed airflow, providing enveloping cooling for the heat sink 400 and significantly increasing the effective heat dissipation area of ​​the heat sink 400 to improve the heat dissipation effect on the heat source.

[0067] Secondly, if the heat sink 400 is a solid structure, high-speed airflow is prone to airflow blockage and rebound on the windward side, resulting in some dynamic pressure dissipation and ineffective utilization. However, in this embodiment, a heat exchange channel 310 is provided inside the heat sink 400, which can provide an additional flow path for the airflow, thereby effectively guiding the accumulated airflow on the windward side, reducing airflow resistance, and allowing more high-speed airflow to participate in heat exchange smoothly, thus improving the utilization rate of airflow.

[0068] Since the piezoelectric fan drives the airflow through the high-frequency reciprocating deformation of the piezoelectric oscillator, the exhaust airflow has periodic pulsating characteristics. During the exhaust phase, the high-speed airflow rushes into the heat exchange channel 310 from the air inlet and flows towards the air outlet. However, during the intake phase, the volume of the gas chamber 201 expands and generates negative pressure, which may cause the airflow that has already entered the heat exchange channel 310 to backflow and recirculate.

[0069] To prevent backflow and reverse flow of air, in one optional embodiment, the heat exchange channel 310 is provided with a flow guiding structure configured to suppress the backflow of gas entering the heat exchange channel 310 from the air inlet. Exemplarily, the flow guiding structure can be a guide ramp, a tapered curved wall, or a flexible baffle with unidirectional conduction characteristics, etc., disposed within the channel.

[0070] During the piezoelectric fan's exhaust cycle, airflow enters the heat exchange channel 310 from the inlet. The flow guiding structure directs the airflow in the direction of the airflow, reducing local flow resistance and allowing the airflow to smoothly move towards the outlet. During the piezoelectric fan's intake cycle, the flow guiding structure prevents reverse airflow, preventing backflow and recirculation of the airflow entering the heat exchange channel 310. Since the airflow in the heat exchange channel 310 will increase in temperature after heat exchange with the heat sink 400, limiting the backflow or recirculation of gas in the heat exchange channel 310 prevents the hot air from mixing with subsequently entering cold air, thus preventing the temperature of the heat exchange airflow from rising and ensuring effective heat dissipation for the heat sink 400.

[0071] In addition, the airflow in the heat exchange channel 310 is restricted from backflow and recirculation. The forward-flowing airflow does not need to overcome and counteract the reverse-flowing vortex, thereby ensuring the flow rate of the forward-flowing airflow and ensuring the heat dissipation effect on the heat sink 400.

[0072] In one alternative embodiment, please refer to Figures 7 to 9 The flow guiding structure includes a main flow channel 320 and a bypass flow channel 330. The bypass flow channel 330 has a first connecting port 301 and a second connecting port 302. Both the first connecting port 301 and the second connecting port 302 are connected to the main flow channel 320. Along the return flow direction of the main flow channel 320 (i.e., the direction opposite to the normal exhaust direction, the direction of reverse flow from the outlet to the inlet), the first connecting port 301 is located upstream of the second connecting port 302. That is to say, when gas recirculation occurs, the gas first passes through the location of the first connecting port 301 and then passes through the location of the second connecting port 302. It should be noted that both the main flow channel 320 and the bypass flow channel 330 are part of the heat exchange channel 310.

[0073] The return gas in the bypass channel 330 enters at the first connecting port 301 in the first direction ( Figure 7The direction indicated by the arrow in the middle (m), and the outlet direction of the return gas in the bypass channel 330 at the second connecting port 302 is the second direction (m). Figure 7 (The direction indicated by the arrow in the middle).

[0074] The return flow direction of the part connecting the main channel 320 and the first connecting port 301 is third-direction ( Figure 7 (As indicated by the arrow in the middle p), the return flow direction of the part connecting the main channel 320 and the second connecting port 302 is the fourth direction. Figure 7 (The direction indicated by the arrow in the middle q).

[0075] The angle between the first and third directions is less than 90 degrees, i.e., an acute angle; the angle between the second and fourth directions is greater than 90 degrees, i.e., an obtuse angle, thus forming a Tesla flow channel.

[0076] The specific recirculation process is as follows: Since the angle between the first direction and the third direction is less than 90 degrees, when the recirculated gas flows through the first connecting port 301, it can be introduced into the bypass channel 330 in a very smooth acute-angle path. That is to say, a part of the recirculated gas is diverted from the main channel 320 into the bypass channel 330 to weaken the overall flow rate and kinetic energy of the recirculated gas in the main channel 320. The direction in which the recirculated gas in the main channel 320 enters the bypass channel 330 through the first connecting port 301 is the first direction.

[0077] The gas introduced into the bypass channel 330 travels along the bypass channel 330 and is finally discharged from the second connecting port 302 located downstream. Since the angle between the second direction (the discharge direction of the bypass airflow) and the fourth direction (the return direction in the main channel 320 at this point) is greater than 90 degrees, meaning the bypass airflow enters the main channel 320 against the return direction of the main channel 320 or at a large counter-current angle, it counter-currents the return gas in the main channel 320, generating significant local flow resistance. This prevents the return gas from continuing to flow back towards the inlet, thus suppressing the backflow of gas entering the heat exchange channel 310 from the inlet. For details, please refer to [reference needed]. Figure 9 , Figure 9 This is a velocity contour map of the gas in the heat exchange channel during reflux, as disclosed in the embodiments of this application. Figure 9 The "V" in the vertical color bar on the right represents the flow rate, and the shade of gray corresponds to the flow rate value.

[0078] When the gas flows in the forward direction, the airflow first passes through the second connecting port 302 and then through the first connecting port 301. The airflow hardly enters the bypass channel 330, and the guiding structure does not obstruct the forward flow of the airflow. See details for further information. Figure 8 , Figure 8 This is a velocity contour map of the gas in the heat exchange channel during forward flow, as disclosed in the embodiments of this application. Figure 8 The "V" in the vertical color bar on the right represents the flow rate, and the shade of gray corresponds to the flow rate value.

[0079] As can be seen, this embodiment designs the shape of the heat exchange channel 310 to form a flow guiding structure that combines the main flow channel 320 and the bypass flow channel 330. This eliminates the need to install flexible baffles, check valves, or other components in the heat exchange channel 310, thereby simplifying the structure of the piezoelectric fan.

[0080] In some embodiments, the number of flow guiding structures includes multiple flow guiding structures, the main flow channels 320 of the multiple flow guiding structures are connected in sequence, the bypass flow channels 330 of two adjacent flow guiding structures are located on different sides, and the included angle between the return flow directions of two adjacent flow guiding structures can be an acute angle.

[0081] In one alternative embodiment, the outer peripheral surface of the heat sink 400 is provided with a plurality of spaced grooves.

[0082] In this embodiment, by providing a groove on the outer peripheral surface of the heat sink 400, the surface area of ​​the heat sink 400 can be increased, thereby increasing the heat exchange area between the heat sink 400 and the air, so that heat can come into contact with the air through a larger surface, thus improving the heat dissipation effect of the heat sink 400.

[0083] Secondly, when the high-speed airflow passes through the groove, the groove can disrupt the laminar boundary layer formed by the airflow on the surface of the heat sink 400, causing the airflow to generate local micro eddies and disturbances inside and at the edge of the groove. The eddies can continuously entrain and peel off the hot air from the wall of the heat sink 400 and replenish fresh cold air, thereby improving the convective heat transfer effect of the outer surface of the heat sink 400.

[0084] In one optional embodiment, the multiple grooves are arranged in a honeycomb pattern. Of course, the grooves can also be arranged in a rectangular array or in a random order. This application does not limit this.

[0085] In one optional embodiment, the air outlet is located on the side wall of the heat sink 400 and penetrates the end face of the heat sink 400 near the heat spreader 300. That is, the surface of the heat spreader 300 facing the heat sink 400 cooperates with the heat sink 400 to form an air outlet.

[0086] In this embodiment, since the air outlet extends to the end face of the heat sink 400 near the heat spreader 300, when the airflow flows out from the air outlet, it will be directly guided and blown to the windward side of the heat spreader 300, and flow along the windward side of the heat spreader 300. This can peel off the thick thermal boundary layer originally formed on the surface of the heat spreader 300 due to heat accumulation, and quickly draw in and carry away the high-temperature air on the surface of the heat spreader 300, thereby improving the heat dissipation effect of the heat spreader 300.

[0087] In an alternative embodiment, the heat exchange channel 310 extends through the end face of the heat sink 400 away from the heat spreader 300 to form an air inlet.

[0088] In this embodiment, the end face of the heat sink 400 away from the heat exchanger 300 is the end face of the heat sink 400 facing the gas chamber 201. Setting the air inlet as an opening penetrating this end face of the heat sink 400 allows the highly concentrated, high-speed airflow from the piezoelectric fan to easily enter the interior of the heat exchange channel 310 upon contact with the heat sink 400, reducing airflow circling and kinetic energy loss outside the heat sink 400 and ensuring the cooling effect of the airflow on the heat sink 400. Of course, the air inlet can also be located on the side wall of the heat sink 400; this application does not limit this.

[0089] In one alternative embodiment, please refer to Figure 1 The number of heat sinks 400 includes multiple heat sinks 400, which are distributed at intervals on the side of the heat spreader 300 facing the vent 202. The area enclosed by the outermost heat sink 400 among the multiple heat sinks 400 is the first area.

[0090] The number of vents 202 includes multiple vents 202, which are spaced apart on the deformable part 210 or the housing 100. The area enclosed by the outermost vent 202 is the second region. For example, the multiple vents 202 can be arranged in a matrix or circular array, with a center-to-center spacing of 0.6~1.2mm.

[0091] The first region and the second region are arranged opposite each other along the axial direction of the vent 202, and the outer edge of the first region extends beyond the outer edge of the second region in a direction perpendicular to the axial direction of the vent 202. That is to say, the coverage area of ​​the heat sink 400 array is larger than the coverage area of ​​the vent 202 array.

[0092] The airflow discharged by the piezoelectric fan through multiple vents 202 has a certain tendency to diffuse laterally after leaving the opening of the outer transition part 205, and the airflow closer to the edge of the array of vents 202 diffuses to a greater extent in all directions.

[0093] In this embodiment, the outer edge of the first region extends beyond the outer edge of the second region in a direction perpendicular to the axial direction of the vent 202. When airflow is ejected outward from the second region, even if the airflow at the edge of the vent 202 array diffuses laterally, the heat sink 400 extending beyond the edge of the second region can still receive the laterally diffused airflow, preventing the edge airflow from escaping and wasting kinetic energy, and improving the utilization rate of the piezoelectric fan's exhaust airflow. Of course, the coverage area of ​​the first region can also be less than or equal to the coverage area of ​​the second region, and this application does not limit this.

[0094] In one optional embodiment, the piezoelectric fan further includes a connector 600, through which the heat-spreading element 300 and the housing 100 are connected. The connector 600 is a telescopic structure to adjust the distance between the heat-spreading element 300 and the housing 100. For example, the connector 600 can employ various mechanical structures to achieve telescopic movement, such as a threaded adjusting pair, a multi-stage sleeve snap-fit ​​structure, or a telescopic rod with an elastic locking element.

[0095] In different types or models of electronic devices, the installation height for piezoelectric fans often varies. Therefore, this embodiment uses a retractable connector 600 to enable the piezoelectric fan to have adaptive adjustment capability in the height direction, allowing the piezoelectric fan to be installed in spaces of different thicknesses, thereby expanding the applicability of the piezoelectric fan.

[0096] In one alternative embodiment, please refer to Figure 5 The housing 100 has a deformable part 121, which forms part of the gas chamber 201. The piezoelectric fan also includes a second piezoelectric element 500, which is disposed on the deformable part 121 and is used to drive the deformable part 121 to vibrate.

[0097] The specific working process is as follows: During intake, the first piezoelectric element 220 drives the deformation element 210 to vibrate in a direction away from the gas chamber 201, and the second piezoelectric element 500 drives the deformation part 121 to vibrate in a direction away from the gas chamber 201, thereby increasing the volume of the gas chamber 201 and drawing gas from the external environment; During exhaust, the first piezoelectric element 220 drives the deformation element 210 to vibrate in a direction closer to the gas chamber 201, and the second piezoelectric element 500 drives the deformation part 121 to vibrate in a direction closer to the gas chamber 201, thereby decreasing the volume of the gas chamber 201 and discharging gas into the external environment.

[0098] It can be seen that in addition to the first piezoelectric element 220 and the deformation element 210, this embodiment can also be used in conjunction with the second piezoelectric element 500 and the deformation part 121 to adjust the volume of the gas chamber 201, thereby increasing the range of change in the volume of the gas chamber 201, increasing the intake and exhaust volume of the gas chamber 201, and improving the heat dissipation effect on the heat source.

[0099] In one optional embodiment, the vent 202 is provided on the housing 100, and the vent 202 is arranged opposite to the deformable member 210 along its own axial direction. It should be noted that when this embodiment is combined with the previous embodiment, the vent 202 can be provided on the deformable part 121. In this case, an avoidance hole 510 can be provided on the second piezoelectric member 500 at the position corresponding to the vent 202. Of course, it can also be provided on the part of the housing 100 located outside the deformable part 121.

[0100] In this embodiment, when the deformable element 210 vibrates, the gas in the area directly in front of it is excited to the highest degree and the pressure change is the greatest. By setting the vent 202 directly opposite the deformable element 210, the high-pressure airflow generated by the deformable element 210 can directly rush into the vent 202 and be discharged with the shortest path and the least flow resistance, thereby improving the concentration of the airflow.

[0101] Please see Figure 1 The housing 100 may include a frame 110 and a sealing plate 120. Deformable elements 210 and 120 are located on opposite sides of the frame 110. The deformable elements 210, 120, and frame 110 surround each other to form a gas chamber 201. The frame 110 and 120 may be separately disposed or integrally formed (e.g., Figure 6 (Structure shown). When this embodiment is combined with the embodiment where the housing 100 has a deformable portion 121, the sealing plate 120 includes the deformable portion 121.

[0102] This application also discloses an electronic device, including the piezoelectric fan of any of the above embodiments, thus enabling the electronic device to possess the aforementioned beneficial effects of the piezoelectric fan, which will not be elaborated further here. For example, the electronic device can be a mobile phone, tablet computer, e-book reader, etc.

[0103] The foregoing embodiments of this application focus on describing the differences between various embodiments. As long as the different optimization features between embodiments are not contradictory, they can be combined to form better embodiments. For the sake of brevity, these differences will not be elaborated upon here. The embodiments of this application have been described above with reference to the accompanying drawings. However, this application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art, under the guidance of this application, can make many modifications without departing from the spirit and scope of the claims, all of which fall within the protection scope of this application.

Claims

1. A piezoelectric fan, characterized in that, include: Casing (100); A piezoelectric vibration assembly (200) includes a deformable element (210) and a first piezoelectric element (220). The deformable element (210) is connected to the housing (100) and cooperates with the housing (100) to form a gas chamber (201). One of the deformable element (210) and the housing (100) is provided with a vent (202) communicating with the gas chamber (201). The first piezoelectric element (220) is disposed on the deformable element (210) and can drive the deformable element (210) to vibrate so that the gas chamber (201) can draw in or vent through the vent (202). The vent (202) includes an inner transition section (203), a throat (204), and an outer transition section (205) that are sequentially distributed and connected from the inside to the outside relative to the gas chamber (201). The flow area of ​​the inner transition section (203) gradually decreases from the inside to the outside, the flow area of ​​the throat (204) remains unchanged from the inside to the outside, and the flow area of ​​the outer transition section (205) gradually increases from the inside to the outside to form a Venturi channel.

2. The piezoelectric fan according to claim 1, characterized in that, The length of the throat (204) is 0.03 mm to 0.13 mm; and / or, The ratio of the length of the inner transition portion (203) to the length of the throat (204) is 1.5 to 3, and the ratio of the length of the outer transition portion (205) to the length of the throat (204) is 1.5 to 3; and / or, The ratio of the flow area of ​​the inner opening of the inner transition portion (203) to the flow area of ​​the throat (204) is 2 to 6; and / or, The ratio of the flow area of ​​the outer opening of the outer transition portion (205) to the flow area of ​​the throat (204) is 2 to 6.

3. The piezoelectric fan according to claim 1, characterized in that, The piezoelectric fan also includes a heat spreader (300), which is connected to the housing (100). The heat spreader (300) and the vent (202) are arranged opposite to each other along the axial direction of the vent (202). The heat spreader (300) is used to fit against the heat source. The piezoelectric fan also includes a heat sink (400), which is disposed on the side of the heat spreader (300) facing the vent (202); A heat exchange channel (310) is formed inside the heat sink (400). The heat exchange channel (310) has an air inlet and an air outlet. The air inlet is located at the end of the heat sink (400) away from the heat spreader (300), and the air outlet is located at the end of the heat sink (400) close to the heat spreader (300).

4. The piezoelectric fan according to claim 3, characterized in that, The heat exchange channel (310) is provided with a flow guiding structure, which is configured to suppress the backflow of gas entering the heat exchange channel (310) from the air inlet.

5. The piezoelectric fan according to claim 4, characterized in that, The flow guiding structure includes a main flow channel (320) and a bypass flow channel (330). The bypass flow channel (330) has a first connection port (301) and a second connection port (302). Both the first connection port (301) and the second connection port (302) are connected to the main flow channel (320). Along the return direction of the main flow channel (320), the first connection port (301) is located upstream of the second connection port (302). The return gas in the bypass channel (330) enters in the first connecting port (301) in the first direction, and the return gas in the bypass channel (330) exits in the second connecting port (302) in the second direction. The return flow direction of the part of the main channel (320) connected to the first connecting port (301) is a third direction, and the return flow direction of the part of the main channel (320) connected to the second connecting port (302) is a fourth direction. The angle between the first direction and the third direction is less than 90 degrees, and the angle between the second direction and the fourth direction is greater than 90 degrees.

6. The piezoelectric fan according to claim 3, characterized in that, The outer peripheral surface of the heat sink (400) is provided with a plurality of spaced grooves; and / or, The air outlet is located on the side wall of the heat sink (400), and the air outlet penetrates the end face of the heat sink (400) near the heat spreader (300); and / or, The heat exchange channel (310) extends through the end face of the heat sink (400) away from the heat spreader (300) to form the air inlet.

7. The piezoelectric fan according to claim 3, characterized in that, The number of heat sinks (400) includes a plurality of heat sinks (400) that are spaced apart on the side of the heat spreader (300) facing the vent (202). The area enclosed by the outermost heat sink (400) among the plurality of heat sinks (400) is the first area. The number of vents (202) includes a plurality of vents (202), which are spaced apart on the deformable part (210) or the housing (100). The area enclosed by the outermost vent (202) among the plurality of vents (202) is the second area. The first region and the second region are arranged opposite each other along the axial direction of the vent (202), and the outer edge of the first region extends beyond the outer edge of the second region in a direction perpendicular to the axial direction of the vent (202).

8. The piezoelectric fan according to claim 3, characterized in that, The piezoelectric fan also includes a connector (600), the heat spreader (300) and the housing (100) are connected by the connector (600), and the connector (600) is a telescopic structure to adjust the distance between the heat spreader (300) and the housing (100).

9. The piezoelectric fan according to claim 1, characterized in that, The housing (100) has a deformable portion (121) that forms part of the gas chamber (201). The piezoelectric fan further includes a second piezoelectric element (500) disposed on the deformable portion (121) and used to drive the deformable portion (121) to vibrate; and / or, The vent (202) is provided on the housing (100), and the vent (202) is arranged opposite to the deformable member (210) along its own axial direction.

10. An electronic device, characterized in that, Including the piezoelectric fan as described in any one of claims 1 to 9.

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