Wireless charger transmitter
Patent Information
- Application Number
- PCT/CN2025/089002
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2025-04-15
- Publication Date
- 2026-10-22
Smart Images
Figure CN2025089002_22102026_PF_FP_ABST
Abstract
Description
Wireless charger transmitterTechnical field
[0001] The present invention relates to wireless charging and, more particularly, to wireless charger transmitters with thermal mitigation.Background of the Invention
[0002] Wireless charging of smartphones is increasingly widespread, mostly for the convenience it offers. In an automotive context, it is particularly advantageous to avoid charging cables with their potential to become entangled with the vehicle controls and as the wireless charger transmitter provides a repository for the driver’s phone, driver distraction can be reduced, thus helping address a safety concern that has led to many countries prohibiting smartphone usage while driving.
[0003] Many vehicle manufacturers are nowadays also considering the wireless charger as a hub for close range interactions between the smartphone and the vehicle, using technologies such as Near Field Communication and the Long Term Evolution coupler.
[0004] However, the proliferation of wireless charging systems is held back by two factors that have resulted in significantly higher manufacturing costs than for alternative corded chargers. The first factor is that wireless charger transmitters are complex, compared to alternatives like USB chargers. The second factor is that, due to wireless charger systems having an efficiency that is significantly lower than USB chargers, measures must be taken to counter the adverse consequences of heating.
[0005] Presently, although several wireless charging methods have been proposed, only the Qi standard from the Wireless Power Consortium (WPC) has seen broad adoption by vehicle manufacturers, as well as acceptance by smartphone makers, making it the de-facto wireless charging standard. The Qi standard was originally engineered for consumer electronics applications, allowing smartphone makers to develop their private charging ecosystem and embedding a Qi standard transmitter application in a vehicle has proved challenging. Most of the designs set out in the Qi standard are unsuited to vehicle integration: by nature, the Qi operating frequency (in the 100～400kHz range) jams the close by AM-Band (560～1600kHz) radio that is still in use in many countries, for example in Germany, where it is used for traffic information broadcasting. To prevent the AM-Band jamming, a MP-A13 antenna transmitter has been certified by the WPC within its Qi standard. This construction in itself increases complexity, while it implements filters that act to increase heat-producing losses.
[0006] Inefficiency in the electrical circuits causes heat generation that in turn causes temperatures in the smartphone repository to rise, undermining the charging operation. This heating up is usually mitigated by embedding a heatsink and an active cooling system in the wireless charging transmitter for cooling both the wireless charging transmitter and the device being charged, which must be maintained at a temperature below 40℃ to protect its battery.
[0007] It is an object of the present invention to address this need for improved thermal mitigation or, more generally, to provide an improved wireless charger transmitter. Disclosure of the Invention
[0008] According to one aspect of the present invention there is provided a wireless charger transmitter, comprising:
[0009] a heat sink made of a metallic material and defining an axis, the heat sink comprising one member having a generally constant cross-section transverse to the axis throughout an axial extent thereof, the one member including a wall integral with a plurality of fin portions, the wall being thin with an outer surface, and an opposing inner surface, the plurality of fin portions extending from the inner surface, such that the wall and fin portions bound one or more hollow or open axially-extending air passageways, and
[0010] a wireless charging coil antenna assembly thermally coupled to, and overlying, the outer surface.
[0011] As used herein, “thermally coupled” includes direct surface-to-surface contact, as well as indirect connections where one or more thin thermally conductive layers is present between the effectively abutting surfaces. The thermally conductive layer may take the form of an adhesive pad or laminate, or a cured adhesive layer perhaps applied as a liquid or paste. More substantial thermal coupling devices like heat pipes are excluded.
[0012] Preferably the wireless charger transmitter further comprises a printed circuit board that carries at least one electrical component for operating the wireless charging coil antenna assembly, the at least one electrical component having an outer face, the printed circuit board disposed in the one or more hollow or open axially-extending air passageways, and wherein the plurality of fin portions comprise at least one component-facing fin portion having a fin face that is complementary to the outer face and wherein fin face is thermally coupled to the outer face for conducting heat away from the electrical component.
[0013] Preferably the heat sink further comprises an other member connected adjacent the one member, the other member having a generally constant cross-section transverse to the axis throughout an axial extent thereof, the other member including a wall integral with a plurality of fin portions, the wall being thin with an outer surface, and an opposing inner surface, the plurality of fin portions extending from the inner surface, wherein respective axes of the one member and the other member are substantially parallel, the inner surfaces face one another with the outer surfaces outermost, such that the walls generally bound opposing major sides of the heat sink with the one or more hollow or open axially-extending air passageways extending therebetween.
[0014] Preferably the plurality of fin portions of the one member and the other member include at least one connector formation which is integral with the respective member, axially-elongated and disposed and the connector formations are mutually engaged to connect the one member to the other member.
[0015] Preferably the connector formations are mutually connected by a resilient snap action following relative transverse movement. The rib and channel could alternatively be mutually connected by following relative axial movement to insert the ribs into the channels.
[0016] Preferably the at least one connector formation comprises a rib and channel which are both axially-elongated, parallel and complementary to one another, and disposed such that channel of the one member receives the rib of the other member, the channel of the other member receives the rib of the one member and the rib projects away from the inner surface.
[0017] Preferably the respective outer surfaces of the one member and the other member are substantially planar and parallel, and the fin face is inclined relative to the outer surfaces at an angle of between 30° and 90°.
[0018] Preferably the heat sink further comprises slots that open into the one or more axially-extending air passageways, wherein the slots are disposed proximate diagonally opposing corners of the heat sink, between an edge of the wall and an adjacent one of the fin portions.
[0019] Preferably the one member and the other member are formed by extrusion and, preferably the one member and the other member have the same profile.
[0020] Preferably the printed circuit board is disposed between the component-facing fin portion and an other one of the fin portions, and the other one of the fin portions is thermally coupled to a face of the printed circuit board adjacent the electrical component on a side of the printed circuit board opposite to that from which the electrical component projects.
[0021] Preferably the at least one electrical component comprises first and second electrical components for operating the wireless charging coil antenna assembly and mounted on opposite sides of the printed circuit board, each of the first and second electrical components thermally coupled to a respective one of the fin portions.
[0022] Preferably the printed circuit board is substantially axially coextensive with the one member, the one member is axially longer than the other member and overlaps the entirety of the axial extent of the other member.
[0023] Preferably the one member and the other member of the heat sink define respective end faces at their opposite axial ends, each end face of each pair extending generally transverse to the axis and wherein both end faces are aligned in a common plane.
[0024] Preferably the wireless charger transmitter further comprises an active cooling device that induces air to flow through the one or more axially-extending air passageways.
[0025] Preferably the heat sink comprises first and second axially opposing ends and the active cooling device comprises a fan mounted in a first block at the first axial end.
[0026] Preferably the second axial end comprises a second block defining openings such that air directed into the first axial end performs a single pass through the one or more axially-extending air passageways and is vented from the openings.
[0027] This invention provides a wireless charger transmitter able to effectively and efficient regulate temperature by maximising heat transfer area exposed to the air, while having an overall simple design which minimizes manufacturing costs. By varying axial length of the heat sink members, cooling is readily adaptable to specific product needs, offering an essentially modular design. Moreover, its manufacture can be readily integrated into existing manufacturing lines with minimal changes.Brief Description of the Drawings
[0028] Fig. 1 is a circuit schematic illustrating the main functional components of a state-of-the-art wireless charger transmitter;
[0029] Fig. 2 is an exploded isometric view of the state-of-the-art wireless charger transmitter with a focus on the heat sink;
[0030] Fig. 3 is a section in a transverse plane through the wireless charger transmitter of Fig. 2 when assembled;
[0031] Fig. 4 is an isometric view of a first embodiment of a wireless charger transmitter of the invention;
[0032] Fig. 5 is a partially-exploded view of the wireless charger transmitter of Fig. 4;
[0033] Fig. 6 is a schematic section in a transverse plane through the heat sink of the wireless charger transmitter of Fig. 4;
[0034] Fig. 7 is an enlarged fragmentary view of feature 7 of Fig. 6;
[0035] Fig. 8 is an isometric view of a second embodiment of a wireless charger transmitter of the invention, and
[0036] Figs. 9 to 14 are schematic sections in transverse planes through the heat sink of the wireless charger transmitters of third through eighth embodiments of the invention. Description of the Preferred Embodiments
[0037] Referring to the drawings, Fig. 1 illustrates the basic circuits of a state-of-the-art wireless charger transmitter 199 certified by the WPC, with a focus on the functional blocks that are significant contributors to inefficiency or losses, and hence to heating. It shows a simplified charging system with only a single charging antenna and with some well-known functions, such as monitoring and multiplexing, also omitted. Also, the DC power source 190 is not considered part of the wireless charging system since it is dependent on the environment, being, for example, a 12V supply in most automotive applications.
[0038] Broadly speaking, the state-of-the-art wireless charger transmitter 199 can be considered to comprise two main functional blocks: a charging controller 100 and a wireless charging antenna 150. The charging controller 100 manages all aspects of the wireless power transfer, as by implementing the Wireless Consortium’s Qi standard. The wireless charging antenna 150 comprises at least one radiating coil 151 coupled serially to a capacitance (not shown) . The serial inductance 151 and coupled capacitance implement a low-pass filter. As such, the wireless charging antenna 150 is a major source of inefficiency and contributes to approximately 30%of the losses made in the transmitter 199.
[0039] The charging controller 100 includes a voltage inverter driver 110 that in turn comprises a microcontroller 115 which executes firmware code implementing the Wireless Consortium’s Qi standard and interfaces to and from the other sub-blocks of the charging controller 100 and the wireless charging antenna 150. The voltage inverter driver 110 is a loss contributor, through the power management functions it includes, though its largest contribution to the inefficiency of the complete charging system is its supply of the active cooling system it usually supplies.
[0040] The charging controller 100 includes a voltage inverter 130 which converts the power supply DC output voltage 125 into an AC square signal 135 used to feed the wireless charging antenna 150. Usually, the voltage inverter 130 is an H-bridge topology inverter made of four switches, typically power MOSFETs, that are controlled by the voltage inverter driver 110. The voltage inverter 130 contributes to the system inefficiency through switching losses.
[0041] The charging controller 100 includes a DC-DC converter 120 which converts a DC input voltage 195 from the DC power source 190 into the DC output voltage 125 needed to provide the requested power by the in-charge device (asmartphone for example) . Like all power supplies, the DC-DC converter 120 contributes losses that are mostly by the internal resistance of its inductor and which represent roughly 20%of the losses of the wireless charging transmitter 199.
[0042] Automotive wireless transmitters usually feature two additional filters, the low-pass filter 140 and the DC power line filter 145, shown here in dotted lines. The low-pass filter 140 disposed between the voltage inverter 130 and the wireless charging antenna 150 is a solution proposed by the Wireless Power Consortium to mitigate AM-Band interference. The low-pass filter 140 is the largest contributor of inefficiency, with a third of the losses, due to its low cut off frequency fc. The DC power line filter 145 is provided upstream of the DC-DC converter 120 to reduce the conduction of interferences from the voltage inverter 130 along the wireless charger transmitter power supply lines. This DC power line filter 145 usually comprises a power choke combined with one or more inductors to create a low-pass filter and is a relatively minor contributor to losses through its resistive characteristic.
[0043] Expressed in losses, the wireless power transmitter has to thermally dissipate about 25%～30%of the transmitted power. In most cases, this represents over 3W, increasing with the output power that cannot be dissipated by the PCBA or by construction without a heatsink.
[0044] Referring to Figs. 2 and 3, the prior art wireless charger transmitter 199 may generally comprise a metal heatsink 197, a printed circuit board assembly (PCBA) 196, a fixture 194, an active cooling device 193 and an antenna assembly 192.
[0045] The heatsink 197 may, for instance, be cast from aluminium or magnesium (as by thixocasting) and may be dish-shaped with continuous, thick and heavy side and base walls that together bound a recess 198 that holds the PCBA 196. In this manner the heatsink 197 serves both as is a passive heat exchanger that transfers the heat generated by the electronics to the ambient air and also as a structural part of an enclosure to which mounting fasteners (not shown) may be fixed.
[0046] The PCBA 196 comprises a printed circuit board that carries the electronic components, including of the charging controller 100. Thermal pads (not shown) between the PCBA 196 and the heatsink 197 facilitate heat transfer to the heatsink 197.
[0047] The fixture plate 194 may be a steel plate that carries the antenna assembly 192 on its outer side and cooperates with the heatsink 197 to close the recess 198 and form the enclosure for the PCBA 196. The fixture plate 194 may provide a structural element by which the wireless charger transmitter 199 is mounted inside the vehicle, and may also serve for carrying an active cooling device 193.
[0048] The active cooling device 193 may generate an air flow to help dissipate heat to ambient air, and may comprise a fan or blower, a MEMs, an ionic thruster or any component capable of generating an air flow.
[0049] The antenna assembly 192 comprises coils of the antenna 150 and a ferrite shield (not shown) that shields the enclosed electrical components and minimizes inductive effects within those components. The ferrite shield overlies the outer face of the housing 2 which it separates from the antenna 150.
[0050] Providing a relatively thin, generally rectangular prismatic overall form factor, this layered construction of relatively thin parts or sub-assemblies, provides space-efficient packaging, however, it suffers from certain drawbacks. One drawback is that electrical connectors between the PCBA 196 and antenna 150 are vulnerable to heating due to the skin and proximity effect. Another is that its manufacture is difficult to automate as this layered construction is unsuited to a direct assembly by direct soldering of terminals of the antenna 150 to the PCBA 196 and it requires a process where PCBA 196, fixture 194 and antenna assembly 192 are placed next to one another for terminal soldering, before relative rotation, or folding, in order to place them into their final positions for assembly into the heatsink 197.
[0051] A first embodiment of the wireless charging transmitter 10 of the invention is shown in Figs 3 and 4, and may comprise a heat sink 11 made of first and second members 11a, 11b assembled together adjacent one another and carrying a wireless charging coil antenna assembly 12. The first and second members 11a, 11b may be extruded from metallic material, such as an aluminium alloy, each with a thin, panel-like wall 13 with an outer surface 14. The antenna assembly 12 abuts the one of the outer surfaces 14 that is shown uppermost in the drawings. Each wall 13 has an inner surface 15 opposing the outer surface 14 and may be planar, with the two outer surfaces 14 defining major external faces of the heat sink 11 that may be generally parallel. By providing this thin, highly conductive wall 13 thermally connected to, and generally coextensive with, the antenna assembly 12 efficient heat dissipation at this crucial interface is ensured.
[0052] The first and second members 11a, 11b each have a longitudinal axis 16 and the same profile, or cross-section transverse to the axis 16, throughout an axial extent thereof. Extending from the inner surface 15, first and second members 11a, 11b include a plurality of fin portions or fins 17 integral with the wall 13. Respective axes 16 of the first and second members 11a, 11b may be substantially parallel, the inner surfaces 15 facing one another, with the outer surfaces 14 outermost, such that the walls 13 generally bound opposing major sides of the heat sink 11 and an axially-extending air passageway 18 extends between the walls 13 and fins 17.
[0053] The first and second members 11a, 11b may have different lengths, as with the first member 11a being longer than the second member 11b according to this embodiment. The first member 11a has an axial length approximately equal to that of the antenna assembly 12, and may overlap axially with the entire axial length of the shorter second member 11b. Longitudinal ends of the first and second members 11a, 11b engaging the block 20 may be generally coplanar in a transverse plane (not shown) . The first member 11a may overlap the entirety of the axial extent of the second member 11b, providing a high degree of thermal coupling between the first and second members 11a, 11b.
[0054] Fixed generally at axially opposing ends of the heat sink 11, the wireless charger transmitter 10 may include blocks 19, 20 which pass air flow that is induced in the passageway 18. The blocks 19, 20 may also serve for the mechanical mounting and attachment of the wireless charger transmitter 10 in the vehicle and may be moulded from polymer, and may be co-moulded with the members of the heat sink. A fan 21 may be mounted in the block 19 to induce the air flow through the passageway 18, as by drawing in ambient air and forcing it through the passageway 18, with cooperating openings 22 in block 20 vent this air.
[0055] The wireless charging coil antenna assembly 12 may comprise flat spiral-wound wireless antennae coils 23a, 23b, 23c on a ferrite sheet 24, such that the ferrite sheet 24 separates the antennae coils 23a, 23b, 23c from the heat sink 11 and shields the electrical components disposed therein.
[0056] Referring to Fig. 5, the electrical components disposed in the passageway 18 in the heat sink 11 are part of a PCBA 28 that is coupled to the antennae coils 23a, 23b, 23c and may include a buck-boost coil 25, inductor 26 and an inverter 130, each carried on a printed circuit board 27. The buck-boost coil 25 may be a part of the DC-DC converter 120, and the inductor 26 a part of the low pass filter 140. The printed circuit board 27 may have about the same axial length as the member 11b, with parallel edges at its axially-opposing ends. Locating features (not shown) in opposing faces of the blocks 19, 20, such as channels, may receive the parallel edges to hold the printed circuit board 27 in position.
[0057] The fins 17 may form a branched, tree-like structure extending inwardly away from the wall 13. For instance, component-facing fins 17a, 17b may comprise respective main branches 29, 30 with proximal ends connected directly to the wall 13 that may themselves bifurcate to form child branches 31-33 and 34-36 and which branches 29, 30, 31-33, 34-36 terminate in free, distal ends. This arrangement is thermally advantageous in its large area exposed to the internal air flow allowing unhindered across the exposed surfaces, as well as allowing child branches 31-33 and 34-36 to effectively reinforce or stiffen the main branches 29, 30. The child branches 31-33 and 34-36 may all project to a common side of the respective main branches 29, 30.
[0058] The component-facing fin 17a has a fin face 37 complementary or conforming to that of the adjacent outer surfaces 25a, 26a of the buck-boost coil 25 and inductor 26, respectively, which may be planar. Any space between the fin face 37 and to the adjacent sides of the buck-boost coil 25 and inductor 26 may be filled with a thermally-conductive layer (not shown) to ensure conductive coupling for conducting heat away from the boost coil 25 and inductor 26, while also compensating for a difference in spacing from the face 37. Likewise, the component-facing fin 17b has a fin face 38 complementary or conforming to that of to the adjacent outer surface 130a of the inverter 130, which may be planar with a respective space filled with a thermally-conductive layer (not shown) .
[0059] The wall 13, being thin and highly thermally conductive, like the component-facing fins 17a, 17b functions to conduct away heat generated by the antennae coils 23a, 23b, 23c and conducted through the ferrite sheet 24 and dissipate it to the air flow.
[0060] The heat sink 11 may comprise axial slots 39, 40 that open into the axially-extending passageway 18 and which are formed by the relative positioning of the first and second members 11a, 11b. The axial slots 39, 40 are disposed adjacent diagonally opposing corners of the heat sink 11 between an edge of the wall 13 of one of the members and the adjacent component-facing fin 17a of the other of the members.
[0061] The slot 39 in the side of the heat sink 11 that caries the wireless charging coil antenna assembly 12 receives the PCBA 28. A plane of the printed circuit board 27, and of the faces 37 and 38, is inclined to a plane of the wall 13, as at an angle of 50°. Advantageously, in this configuration, terminals of the coils of the antennae 23a, 23b, 23c can be connected to the PCBA 28 by soldering when in their final position relative to the antennae 23a, 23b, 23c.
[0062] The fins 17 of the first and second members 11a, 11b may include integral male and female connector formations 41, 42 which are axially-elongated and disposed such that, with the first member 11a reversed axially end-for-end relative to the second member 11b as shown, both pairs of connector formations 41, 42 are mutually engaged to connect the first and second members 11a, 11b. In assembly, two pairs of male and female connector formations 41, 42 are mutually connected by a resilient snap action following relative transverse movement perpendicular to the axis 16 providing a mechanical and thermally-conducting coupling between the members 11a, 11b.
[0063] The male and female connector formations 41, 42 may be formed at the distal ends of respective coupling fins 17c, 17d which may be generally centrally disposed in the heat sink 11 adjacent one another. The male connector formation 41 (on fin 17d of member 11a) may be formed in a main branch 43 as a rib projecting transverse to the axis 16 with an enlarged head 44 at its distal end. The complementary female connector formation 42 (on fin 17c of member 11b) may be formed in a main branch 45 projecting transverse to the axis 16 with a head-receiving channel 46 at its distal end.
[0064] The main branch 43 of the coupling fin 17d has a proximal end connected directly to the wall 13 and may trifurcate at three nodes 47 to form two child branches 48, 49. The child branches 48, 49 extending from each node 47 may be generally coplanar and aligned parallel to a plane of the wall 13 and terminate in free, distal ends equidistant either side of the main branch 43. The nodes 47 and child branches 48, 49 may be equally spaced in the transverse direction. Likewise, the main branch 45 of the coupling fin 17c has a proximal end connected directly to the wall 13 and may trifurcate at three nodes 50 to form two child branches 51, 52. The child branches 51, 52 extending from each node 47 may be generally coplanar and aligned parallel to a plane of the wall 13 and terminate in free, distal ends equidistant either side of the main branch 45. The nodes 50 and child branches 51, 52 may be equally spaced in the transverse direction, and staggered with respect to the nodes 47 and child branches 48, 49.
[0065] Particularly in vehicle applications, weight is a key consideration, and it is very cost-effective to achieve this by employing different lengths of a single profile for the members 11a, 11b, allowing the designer to optimise the weight / performance ratio for different models and applications, thus offering an essentially modular design. Moreover, the flexibility of employing two members 11a, 11b facilitates assembly with the PCBA 28, as one can be fastened to each side of the PCBA 28, as by thermal adhesive pads, before the two members 11a, 11b are connected together. Moreover, the heatsink 11 is not a structural part, and this allows the use of an aluminium alloy, such as AA6063, that offers better thermal properties than stronger alloys that are needed for structural parts.
[0066] As shown in Fig. 8, in a second embodiment of the invention a wireless charger transmitter 210 may include a heat sink 211 comprising a single, elongate member 211a carrying the wireless charging coil antenna assembly 12. The member 211a may be extruded from an aluminium alloy, with a thin, panel-like wall 213 with an outer surface 214 that may be planar and defines a major external face that the antenna assembly 12 abuts and which has an opposing inner surface 215. The antenna assembly 12 may be fastened to the outer surface 214 by a thermally-conductive adhesive. Fin portions 217a, 217b integral with the wall 213 extend away from the inner surface 215 and are joined by a base 53 such that the wall 213, fin portions 217a, 217b and base 53 form four sides of a rectangular hollow duct that encloses an axially-extending air passageway 218. A single block 219 may be fixed generally at one axial end of the member 211a and serve for the mechanical mounting and attachment of the wireless charger transmitter 210 in the vehicle. Active cooling need not be provided, as in the provision of means for directing forced air flow axially through the passageway 218 and, application dependent, adequate cooling may be provided by passive convective cooling alone. Further fin portions (not shown) integral with the wall 213 and projecting inwardly from the inner surface 215 may be provided. This wireless charger transmitter 210 can be made cost-effectively without compromising the space-efficient packaging.
[0067] Referring to Figs 9 to 12, third, fourth, fifth and sixth embodiments of the wireless charger transmitter of the invention 310, 410, 510, 610 are variants of the wireless charger transmitter 210 in which the respective single members 311a, 411a, 511a, 611a comprising the heat sink 311, 411, 511, 611 are extrusions of the different profiles illustrated.
[0068] The member 311a has a rectangular open channel-shape comprising fin portions 317a, 317b integral with the wall 313 which are L-shaped in cross-section, producing a profile that is the equivalent of member 211a with a central slot 54 cut in the base for the complete axial extent of the member 311a. Compared to the rectangular hollow member 211a, this open channel-shaped member 311a may be made with thinner sections, reducing material costs, while dissipating heat more efficiently. The slot 54 can be closed by an adjacent part to minimize air leakage.
[0069] The member 411a is of like form to the member 211a, with fin portions 417a, 417b integral with the wall 413 that extend away from the inner surface 415 and are joined by a base 453 such that the wall 413, fin portions 417a, 417b and base 453 form four sides of a rectangular hollow duct wherein, in addition, two further webs or fin portions 417c, 417d extend between the wall 413 and base 453 so as to define axially-extending air passageways 418a, 418b, 418c separated by these fin portions 417c, 417d. The fin portions 417c, 417d may be parallel with the fin portions 417a, 417b.
[0070] The member 511a has a trapezium-shaped profile that is the equivalent of the rectangular profile of member 411a modified with a bevelled lower corner, whereby to provide a component-facing fin portion on this bevelled edge and reduce the width of the base, while maintaining the width of the wall 513 that carries the antenna assembly 12. The component-facing fin portion 517a extends from one edge of the wall 513 at an angle of about 45° to the plane of the wall 513, while fin portion 517b extends from the opposite edge at 90°. The base 555 is parallel to the plane of the wall 513 and the fin portions 517a, 517b join it at transversely opposing edges. Webs or fin portions 517c, 517d extend between the wall 513 and base 555 so as to define axially-extending air passageways 518a, 518b, 518c. The inclined external face 56 of the component-facing fin portion 517a may, like the faces 37, 38, be complementary to the adjacent sides of electrical components (not shown) of the PCBA 28 and planar and thus performs a like function, to ensure conductive coupling for conducting heat away from the electrical components of the PCBA 28, which is located outside of the air passageways 518a, 518b, 518c.
[0071] The member 611a can be considered as being formed from the member 511a with the trapezium-shaped profile on which a further fin portion 617d axially coextensive with the PCBA 28 is arranged generally parallel to the inclined external face 56. This arrangement provides a second, opposing face 57 generally parallel to, and opposite, the face 56. The face 57 is presented toward an opposing side of the PCBA 28, thus thermally coupling both sides of the PCBA 28 to the heat sink 611. It also provides an axially-extending air passageway 618d having an open mouth 58 in which the PCBA 28 is received.
[0072] While sildingly inserting the PCBA 28 into the passageway 618d, with the fin portion 617d located where shown, is a viable assembly option, thermal coupling of the faces 56, 57 after this sliding insertion cannot be achieved using thermal pads or laminates, meaning that to achieve the required thermal coupling a thermal gap-filler must be applied at the interface in fluid (liquid or paste) form. This has drawbacks as gap-filler application is largely blind, in that the establishment of a complete, continuous filler layer cannot be determined by visual inspection, and an injection hole must also be provided for injection of the gap-filler. To address these drawbacks, the fin portion 617d may be connected to the remainder of the profile via an integral hinge 59 configured as a locally thinned length at the proximate end of the fin portion 617d.
[0073] Of course, the two-member arrangement of the heatsink 11 of the wireless charger transmitter 10 also addresses these same drawbacks, in allowing access to abut electrical components on both sides of the PCBA with a respective heatsink member, optionally with a conductive layer at the interface in the form of a thermal pad / laminate or gap filler. The invention thus provides for high quality thermal coupling, before the two members are assembled.
[0074] Fig. 13 schematically illustrates a seventh embodiment of the wireless charger transmitter of the invention 710 which is a variant of the wireless charger transmitter 10 in which the first and second members 711a, 711b have different profiles that are joined to essentially provide a heatsink 711 with the form of the heatsink 611, but without the hinge 59. As in the first embodiment, the first member 711a has an axial length approximately equal to that of the antenna assembly 12, and may overlap axially with the entire axial length of the shorter second member 711b. Considerable freedom is available to the designer with this configuration to vary the axial length of the second member 711b according to the cooling needs of the PCBA 19 and the location of electrical components on it, perhaps also with a view to employing the second member 711b as an EMC shield.
[0075] An eighth embodiment of the wireless charger transmitter 810 has a heat sink 811 of a generally rectangular prismatic form which, like the heat sink 411, lacks an inclined face for presentation toward the PCBA 28 but includes a plurality of hollow air passageways 818a, 818b, 818c, 818d, 818e. This heat sink 811 is suited to low power transmitters (of less than 15W) due to its lower thermal dissipation capability and comprises members 811a and 811b of the same profile, connected together by six pairs of the male / female couplers described above.
[0076] Aspects of the present invention have been described by way of example only and it should be appreciated that modifications and additions may be made thereto without departing from the scope thereof.
Claims
1.A wireless charger transmitter, comprising:a heat sink made of a metallic material and defining an axis, the heat sink comprising one member having a generally constant cross-section transverse to the axis throughout an axial extent thereof, the one member including a wall integral with a plurality of fin portions, the wall being thin with an outer surface, and an opposing inner surface, the plurality of fin portions extending from the inner surface, such that the wall and fin portions bound one or more hollow or open axially-extending air passageways, anda wireless charging coil antenna assembly overlying and thermally coupled to the outer surface.2.The wireless charger transmitter of claim 1, further comprising:a printed circuit board that carries at least one electrical component for operating the wireless charging coil antenna assembly, the at least one electrical component having an outer face, the printed circuit board disposed in the one or more hollow or open axially-extending air passageways, andwherein the plurality of fin portions comprise at least one component-facing fin portion having a fin face that is complementary to the outer face and that the outer face and wherein the fin face is thermally coupled to the outer face for conducting heat away from the electrical component.3.The wireless charger transmitter of claim 1 or claim 2, wherein the heat sink further comprises an other member connected adjacent the one member, the other member having a generally constant cross-section transverse to the axis throughout an axial extent thereof, the other member including a wall integral with a plurality of fin portions, the wall being thin with an outer surface, and an opposing inner surface, the plurality of fin portions extending from the inner surface, wherein respective axes of the one member and the other member are substantially parallel, the inner surfaces face one another with the outer surfaces outermost, such that the walls generally bound opposing major sides of the heat sink with the one or more hollow or open axially-extending air passageways extending therebetween.4.The wireless charger transmitter of claim 3, wherein the plurality of fin portions of the one member and the other member include at least one connector formation which is integral with the respective member, axially-elongated and disposed and the connector formations are mutually engaged to connect the one member to the other member.5.The wireless charger transmitter of claim 4 wherein the connector formations are mutually connected by a resilient snap action following relative transverse movement.6.The wireless charger transmitter of claim 4 or claim 5, wherein the at least one connector formation comprises a rib and channel which are both axially-elongated, parallel and complementary to one another, and disposed such that channel of the one member receives the rib of the other member, the channel of the other member receives the rib of the one member and the rib projects away from the inner surface.7.The wireless charger transmitter of claim 3, wherein the respective outer surfaces of the one member and the other member are substantially planar and parallel, and the fin face is inclined relative to the outer surfaces at an angle of between 30° and 90°.8.The wireless charger transmitter of any one of claims 3 to 8, wherein the heat sink further comprises slots that open into the one or more axially-extending air passageways, wherein the slots are disposed proximate diagonally opposing corners of the heat sink, between an edge of the wall and an adjacent one of the fin portions.9.The wireless charger transmitter of any one of claims 3 to 8, wherein the one member and the other member are formed by extrusion.10.The wireless charger transmitter of claim 9 wherein the one member and the other member have the same profile.11.The wireless charger transmitter of claim 10 wherein the printed circuit board is disposed between the component-facing fin portion and an other one of the fin portions, and the other one of the fin portions is thermally coupled to a face of the printed circuit board adjacent the electrical component on a side of the printed circuit board opposite to that from which the electrical component projects.12.The wireless charger transmitter of claim 10 or claim 11 wherein the at least one electrical component comprises first and second electrical components for operating the wireless charging coil antenna assembly and mounted on opposite sides of the printed circuit board, each of the first and second electrical components thermally coupled to a respective one of the fin portions.13.The wireless charger transmitter of any one of claims 3 to 12, wherein the printed circuit board is substantially axially coextensive with the one member, the one member is axially longer than the other member and overlaps the entirety of the axial extent of the other member.14.The wireless charger transmitter of claim 12, wherein the one member and the other member of the heat sink define respective end faces at their opposite axial ends, each end face of each pair extending generally transverse to the axis and wherein both end faces are aligned in a common plane.15.The wireless charger transmitter of any of the preceding claims, further comprising an active cooling device that induces air to flow through the one or more axially-extending air passageways.16.The wireless charger transmitter of claim 15, wherein the heat sink comprises first and second axially opposing ends and the active cooling device comprises a fan mounted in a first block at the first axial end.17.The wireless charger transmitter of claim 15, wherein the second axial end comprises a second block defining openings such that air directed into the first axial end performs a single pass through the one or more axially-extending air passageways and is vented from the openings.