Heat-dissipating electromagnetic device arrangement and electrical device

Abstract

Electromagnetic device arrangement (10, 10') comprising: an electromagnetic device (14, 14') comprising a core (16, 16'), a plurality of windings (18, 20) and a housing (28, 28') arranged around at least a section of the core (16, 16') and the windings (18, 20); wherein the core (16, 16') comprises first and second sections (22, 22', 24, 24') which are joined to each other by means of an adhesive material (26, 26'), and an enclosure (30, 30') which at least partially encompasses the electromagnetic device (14, 14'), wherein the electromagnetic device (14, 14') is mounted on a first section (32) of the enclosure (30, 30') such that heat is transferred from the electromagnetic device (14, 14') to the first section (32) of the enclosure (30, 30'), wherein a projection (40, 40') extends from a second section (34) of the enclosure (30, 30'), wherein the projection (40,40') is brought into indirect physical thermal contact with the electromagnetic device (14, 14') such that heat is transferred from the electromagnetic device (14, 14') to the extension (40, 40'), wherein the electromagnetic device (14, 14') is arranged relative to the enclosure (30, 30') such that heat is transferred from the first section (22, 22') of the core (16, 16') substantially to the first section (32) of the enclosure (30, 30') and heat is transferred from the second section (24, 24') of the core (16, 16') substantially to the extension (40, 40'), characterized in that a thermally conductive material (42, 42') is arranged between the extension (40, 40') and the housing (28, 28') of the electromagnetic device (14, 14').

Description

Technical Field of MatterThe present invention relates to a heat-dissipating electromagnetic device assembly.BackgroundElectromagnetic devices, such as inductors and electrical transformers, may be constructed in a variety of different ways. A common way is to have windings at least partially surrounded by a core, which may be made of a ferrite material, for example. The core may be formed of one or two pieces bonded together by an adhesive material such as epoxy resin. The windings and the core may be covered by a potting material and surrounded by a housing that allows the transformer to be mounted to another structure, such as a base plate or mounting pad.Electromagnetic devices are increasingly used in electronic devices, for example, a transformer having a transformer housing may be placed within a larger enclosure. Thus, problems may arise, for example, with regard to heat dissipation, in that there is no convection air flow over the transformer within the enclosure. In fact, although there is some amount of heat transfer between the transformer and the base plate or mounting pad, this can cause other problems.In particular, if one portion of the core dissipates a large portion of its heat to the base plate, while the other portion of the core does not do so, a temperature gradient may form between different portions of the transformer core. If different portions of the transformer core are at significantly different temperatures, the temperature gradient between the portions of the core may cause a heat-induced stress, which may then break or otherwise damage the core. Therefore, there is a need for a transformer arrangement that is configured to effectively dissipate heat to prevent the formation of temperature gradients within the transformer even when the transformer is disposed within a larger enclosure that promotes heat buildup.WO 2011 / 089 941 A1 discloses a reactor having an upwardly open reactor housing configured to selectively direct a heat dissipation to a bottom surface of the reactor mounted on a water cooled surface. JP 2010-225 840 A likewise discloses a reactor having heat-dissipating means.The invention is based on the object of providing an electromagnetic device arrangement which is designed by means of simple constructive technical means of reduced heat-induced stress.This object is achieved by means of a device according to claim 1, the independent claim 7 or the independent claim 10.OverviewEmbodiments of the invention include an electromagnetic device assembly including an electromagnetic device having a core, a plurality of windings, and a housing disposed about at least a portion of the core and the windings. A enclosure at least partially comprises the electromagnetic device. The electromagnetic device is mounted to a first portion of the enclosure such that heat is transferred from the electromagnetic device to the first portion of the enclosure. A boss extends from a second portion of the enclosure such that the boss is placed in thermal contact with the electromagnetic device such that heat is transferred from the electromagnetic device to the boss.Embodiments of the invention include an electrical device including an electromagnetic device including a plurality of windings, a split core bonded together by an adhesive material, and a housing disposed at least partially around the windings and the core. The electromagnetic device is mounted on a base member or a base plate, and the former is in thermal contact with the electromagnetic device such that heat is substantially transferred from a first portion of the core to the base plate. A cover may be attached to the base plate to form a surround that at least partially includes the electromagnetic device. The cover has a boss extending therefrom that is in thermal contact with the electromagnetic device when the cover is attached to the base plate. The thermal contact between the boss and the electromagnetic device is configured such that heat from a second portion of the core is substantially transferred to the boss.Embodiments of the invention include an electromagnetic device assembly having a perimeter with a first portion and a second portion. An electromagnetic device includes a core, a plurality of windings, and a housing disposed around at least a portion of the core and the windings. The electromagnetic device is mounted to and in thermal contact with the first portion of the enclosure, and the second portion of the enclosure is configured to be in thermal contact with the electromagnetic device when the first and second portions of the enclosure are attached to each other.Brief Description of the DrawingsFIG. 1 shows an electromagnet device assembly according to embodiments of the present invention; and FIG. 2 shows another electromagnet device assembly according to embodiments of the present invention.Detailed DescriptionAs required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention that may be embodied in various and alternative forms. The figures are not necessarily drawn to scale; some portions may be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a characteristic basis for teaching one skilled in the art to variously employ the present invention.FIG. 1 shows an electromagnet device assembly or transformer assembly 10 according to embodiments of the present invention. In the embodiment shown in FIG. 1, the transformer assembly 10 includes an electrical device or battery charger 12. Other types of electrical devices utilizing electromagnetic devices according to embodiments of the present invention include such electrical devices as a switched mode power supply used in various electronic devices and photovoltaic cells or wind power generators that generate low voltage direct current (DC) energy that must be inverted into high voltage alternating current (AC) energy for general consumption. It should be appreciated that although the electromagnetic devices shown in FIGS. 1 and 2 are transformers, embodiments of the invention may include other electromagnetic devices, such as inductors and other electromagnetic devices.The transformer assembly 10 includes an electromagnetic device or transformer unit 14 formed from a core 16 and windings 18, 20. The core 16 is a split core having a first or lower portion 22 and a second or upper portion 24. A core, such as core 16, may be made of a ferrite material which, while very strong under a compressive load, may not be as strong when subjected to a tensile load. Bonding of the lower and upper portions 22, 24 is accomplished by an adhesive 26, which may be, for example, a material having a high Young's modulus that does not allow significant differential thermal expansion and shrinkage to occur between the lower and upper portions 22, 24 of the core 16. In other embodiments, metallic C-shaped brackets or U-shaped brackets may be used to hold portions of the core together. The transformer unit 14 further includes a housing 28 disposed around at least a portion of the core 16 and the windings 18, 20. A potting material 29 surrounds the core 16 and the windings 18, 20 and generally fills the space between them and the housing 28.A enclosure 30 comprises the transformer unit 14. the enclosure 30 has a first portion or base plate 32 to which the housing 28 of the transformer unit 14 is / is mounted. Although not shown in FIG. 1, the housing 28 may be attached to the base plate 32 by screws, other fasteners, or any suitable method by which the transformer unit 14 is brought into thermal contact with the base plate 32. Although a housing such as the housing 28 may generally surround a core and windings of a transformer, such a housing may also be in the form of brackets or other attachment means that serve to attach the core and windings to another structure such as the base plate 32.As described above, the transformer unit 14 is in "thermal contact" with the base plate 32. As used herein, the term thermal contact implies direct or indirect physical contact between the structures, and in particular that there is either direct contact between the two structures or that there is indirect contact with another fixed structure or structures disposed therebetween. For example, the core 16 is in thermal contact with the housing 28 via the thermally conductive potting material 29 disposed between the core 16 and the housing 28. Further, as shown in FIG. 1, a lower portion of the housing 28 is in direct contact with the base plate 32 and thus provides thermal contact between the transformer unit 14 and the base plate 32.The enclosure 30 further includes a second portion or cover, which in the embodiment shown in FIG. 1 includes a top portion 34 and side portions 36, 38. In some embodiments of a transformer utilizing device, the side portions 36, 38 may be considered a part of the device housing, while the top portion 34 itself is referred to as the "cover.". As shown in FIG. 1, the upper portion 34 has a boss 40 extending inwardly therefrom. The boss 40 may be integrally formed with the upper portion 34 -- i.e., the upper portion 34 and the boss 40 may be made of a single piece of material. Alternatively, the boss 40 may be attached to the upper portion 34 such that the two structures 34, 40 are in thermal contact with each other. As will be explained in more detail below, this allows heat to be dissipated from an upper portion of the transformer unit 14 through the boss 40 and ultimately through the upper portion 34 of the enclosure 30.To effectively dissipate heat from an upper portion of the transformer unit 14, and more specifically from the upper portion 24 of the core 16, the boss 40 is placed in thermal contact with the housing 28. To facilitate heat transfer, the boss 40 may be manufactured to maximize a contact area between it and the housing 28. It is also made of a material having good thermal conductivity and its surface may be made to be particularly smooth and coplanar with the top of the housing 28 to further facilitate good heat transfer.Disposed between the housing 28 and the boss 40 is a sheet of thermally conductive material 42. Although in some non-inventive embodiments, a lip of a skirt, such as lip 40, may be configured to directly contact housing 28, the provision of a thermally conductive material, such as material 42, disposed between lip 40 and a housing 28 makes the manufacturing and assembly process easier. If the boss 40 is configured to directly contact the housing 28, extremely close tolerances are required during manufacture and assembly.To reduce or eliminate potential tolerance accumulation problems, a thermally conductive material, such as material 42, may be selected to be formed from a substantially compliant solid that may fill a gap between the boss 40 and the housing 28 when the battery charger 12 is assembled. More specifically, when the transformer unit 14 is attached to the base plate 32 and the first and second portions of the enclosure 30 are joined together - i.e., the side portions 36, 38 are attached to the base plate 32 and the top portion 34 is attached to the side portions 36, 38 - the material 42 contacts the boss 40 and the housing 28, thereby bringing the two structures into thermal contact with each other. This configuration is particularly advantageous since the base plate 32 is arranged on an opposite side of the transformer unit 14 relative to the shoulder 40. This helps to solve the above-described problem of uneven cooling between the upper and lower portions 22, 24 of the core 16.The formation of a temperature gradient between different portions of a core, e.g., lower and upper portions 22, 24 of the core 16, may be reduced by using (above) metal clips instead of an adhesive to hold the portions together; however, packaging or other design considerations may result in an adhesive material, such as the adhesive 26, being used, the temperature gradient between the core portions may be unacceptably large. Even if metal clips are used, there may still not be sufficient heat dissipation from the warmer portion of the core to the cooler portion to avoid a large temperature gradient. Thus, in the embodiment shown in FIG. 1, each portion of the core 16 has its own heat sink - i.e., heat from the lower portion 22 of the core 16 is substantially transferred to the base plate 32 while heat from the upper portion 24 of the core 16 is substantially transferred to the boss 40, thereby reducing the temperature gradient between the two portions. The base plate 32 may conduct heat through cooling channels as described above, and when the upper portion 34 is connected to the base plate 32 in a heat efficient manner, for example, through the side portions 36, 38, the base plate 32 may also serve to conduct heat away from the upper portion 34. Additionally or alternatively, the upper portion 34 may conduct heat by convection into the ambient air.FIG. 2 shows a transformer arrangement 10' according to a further embodiment of the present invention. As shown in FIG. 2, at certain reference numerals, the apostrophe (') is used to indicate features corresponding to similar features shown in FIG. 1. In the embodiment shown in Figure 2, the tab 40' has two portions 44, 46. As in the case of the tab 40 shown in Figure 1, the tab 40' may be integrally formed with an upper portion 34' of the enclosure 30', or it may be separately attached. Further, the two sections 44, 46 may be made from a single piece, or they may be separate pieces that are joined together.The housing 28' of the transformer unit 14' has an opening 48 in an upper portion just above the upper portion 24' of the core 16'. The lower portion 46 of the boss 40' is configured to pass through the opening 48 to be in thermal contact with the upper portion 24' of the core 16', without the housing 28' being interposed therebetween. In other embodiments, a tab or portion thereof may be configured to contact the windings of a transformer unit instead of the core. The upper portion 44 of the boss 40' is in thermal contact with the housing 28' similar to the embodiment shown in Figure 1.A thermally conductive material 50, which may or may not be the same material as material 42, 42', is disposed between the lower portion 46 of the boss 40' and the upper portion 24' of the core 16'. A material, such as material 50, may also be disposed between a transformer core and a transformer housing, such as the upper portion 24 of the core 16 and the housing 28 shown in FIG. 1. In addition to facilitating thermal conduction, a material such as material 50 may serve as a dielectric for electrically insulating a transformer core from its housing. As shown in Figure 2, a portion of the thermally conductive material 50 is also disposed between the upper portion 24' of the core 16' and the housing 28'. This may be provided in addition to or may replace potting material 29' which would otherwise be disposed about an upper surface of upper portion 24' of core 16'.The opening 50 may be configured to maximize the area of contact between the lower portion 46 of the ledge 40' and the upper portion 24' of the core 16', it being understood that manufacturing and assembly considerations may limit the size or shape of the opening 50 and the lower portion 46 of the boss 40'. The area of the lower portion 46 that comes into thermal contact with the upper portion 24' of the core 16' can be determined, for example, based on the cooling requirement of the upper portion 24' and the structural requirements of the transformer unit 14'. As described above, embodiments of the invention may be particularly advantageous for ferrite core electromagnetic devices having low tensile strength; however, for metal core devices having higher tensile strength, embodiments of the invention may also be advantageous in that the heat is dissipated from the windings, which may be significant.

Claims

An electromagnetic device assembly (10, 10') comprising: an electromagnetic device (14, 14') comprising a core (16, 16'), a plurality of windings (18, 20), and a housing (28, 28') disposed about at least a portion of the core (16, 16') and the windings (18, 20); wherein the core (16, 16') comprises first and second portions (22, 22', 24, 24') joined together by an adhesive material (26, 26'), and a enclosure (30, 30') at least partially comprising the electromagnetic device (14, 14'), wherein a first portion (32) of the enclosure (30, 30') mounts the electromagnetic device (14, 14') such that heat from the electromagnetic device (14, 14'), 14') is transferred to the first portion (32) of the enclosure (30, 30'), a tab (40, 40') extending from a second portion (34) of the enclosure (30, 30'), the tab (40, 40') being placed in indirect physical thermal contact with the electromagnetic device (14, 14'), heat being transferred from the electromagnetic device (14, 14') to the tab (40, 40'), the electromagnetic device (14, 14') being disposed relative to the enclosure (30, 30') such that heat is transferred from the first portion (22, 22') of the core (16, 16') substantially to the first portion (32) of the enclosure (30, 30') and heat is transferred from the second portion (24, 24') of the core (16, 16'), 16') is substantially transferred to the shoulder (40, 40'), characterized in that a thermally conductive material (42, 42') is arranged between the shoulder (40, 40') and the housing (28, 28') of the electromagnetic device (14, 14').The electromagnetic device assembly of claim 1, wherein the first portion (32) of the enclosure (30, 30') is a base part and the second portion (34, 34') of the enclosure (30, 30') is a cover connected to the base part to form the enclosure (30, 30').The electromagnetic device assembly of claim 2, wherein the tab (40, 40') is brought into thermal contact with the electromagnetic device (14, 14') on a side of the electromagnetic device (14, 14') opposite the base portion.The electromagnetic device assembly of any preceding claim, wherein the tab (40, 40') is placed in thermal contact with the electromagnetic device (14, 14') such that the tab (40, 40') is in thermal contact with the housing (28, 28').The electromagnetic device assembly of any preceding claim, wherein the housing (28') has an opening (48) formed therein and the boss (40') is configured to pass through the opening (48) such that at least a portion of the boss (40) is in thermal contact with the core (16') without the housing (28') being interposed therebetween.The electromagnetic device assembly of claim 5, wherein the tab (40') is placed in thermal contact with the electromagnetic device (14') such that a first portion (44) of the tab (40') is in thermal contact with the housing (28') and a second portion (46) of the tab (40') is in thermal contact with the core (16) without the housing (28') being interposed therebetween.An electrical device comprising: an electromagnetic device (14, 14') comprising a plurality of windings (18, 20), a split core (16, 16') bonded together by an adhesive material (26, 26'), and a housing (28, 28') disposed at least partially around the windings (18, 20) and the core (16, 16'); a base plate to which the electromagnetic device (14, 14') is mounted and which is in thermal contact therewith such that heat is transferred from a first portion (22, 22') of the core (16, 16') substantially to the base plate; and a cover attachable to the base plate to form a enclosure (30, 30') at least partially comprising the electromagnetic device (14, 14'), the cover including a boss (40, 22'), 40') extending therefrom, the boss (40, 40') being in indirect physical thermal contact with the electromagnetic device (14, 14') when the cover is attached to the base plate, the thermal contact between the boss (40, 40') and the electromagnetic device (14, 14') being configured such that heat is transferred from a second portion (24, 24') of the core (16, 16') substantially to the boss (40, 40'), characterized in that a thermally conductive material (42, 42') is disposed between the boss (40, 40') and the housing (28, 28') of the electromagnetic device (14, 14').The electrical device of claim 7, wherein the tab (40, 40') is placed in thermal contact with the electromagnetic device (14, 14') such that heat transferred from the second portion (24, 24') of the core (16, 16') to the tab (40, 40') prevents a temperature gradient between the first and second portions (22, 22', 24, 24') of the core (16, 16').The electrical device of claim 7 or 8, wherein the tab (40') is placed in thermal contact with the electromagnetic device (14') such that the tab (40') is in thermal contact with the housing (28') and / or the core (16') without the housing (28') being interposed therebetween.An electromagnetic device assembly (10, 10') comprising: a casing (30, 30') comprising a first portion (32) and a second portion (34, 34'); and an electromagnetic device (14, 14') comprising a core (16, 16'), a plurality of windings (18, 20), and a housing (28, 28') disposed about at least a portion (22, 22') of the core (16, 16') and the windings (18, 20) and mounted to and in thermal contact with the first portion (32) of the casing (30, 30'), the core (16, 16') comprising first and second portions (22, 22', 24, 24') joined together by an adhesive material (26, 26'), the second portion (34, 34') of the casing (30, 30, 30') configured to be in indirect physical thermal contact with the electromagnetic device (14, 14') when the first and second portions (32, 34, 34') of the enclosure (30, 30') are attached to each other, wherein the electromagnetic device (14, 14') is arranged relative to the enclosure (30, 30') such that heat is transferred from the first portion (22, 22') of the core (16, 16') substantially to the base-formed first portion (32) of the enclosure (30, 30') and heat is transferred from the second portion (24, 24') of the core (16, 16') substantially to the hub (40, 40'), wherein the enclosure (30, 30') at least partially comprises the electromagnetic device (14, 14'), and wherein the second portion (34, 34, 24'), 34') of the enclosure (30, 30') has a boss (40, 40') projecting therefrom such that the boss (40, 40') is in thermal contact with the electromagnetic device (14, 14') when the first and second portions (32, 34, 34') of the enclosure (30, 30') are attached to one another, characterized in that a thermally conductive material (42, 42') is disposed between the boss (40, 40') and the housing (28, 28') of the electromagnetic device (14, 14').The electromagnetic device assembly of claim 10, wherein the housing (28) has an opening (48) formed therein and the boss (40') is configured to pass through the opening (48) such that at least a portion of the boss (40') is in thermal contact with the core (16') without the housing (28') being interposed therebetween.The electromagnetic device assembly of claim 11, wherein the tab (40') is brought into thermal contact with the electromagnetic device (14') such that a first portion (44) of the tab (40') is in thermal contact with the housing (28') and a second portion (46) of the tab (40') is in thermal contact with the core (16') without the housing (28') being interposed therebetween.The electromagnetic device assembly of claim 10, wherein the second portion (34, 34') of the enclosure includes a cover connected to the base portion to form the enclosure (30, 30').The electromagnetic device assembly of claim 13, wherein the tab (40, 40') is brought into thermal contact with the electromagnetic device (14, 14') on a side of the electromagnetic device (14, 14') opposite the base portion.

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