CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Patent Application No. 63/041,438 filed on June 19, 2020. The entire contents of this application are hereby incorporated by reference.

[0002] In addition, the entire contents of U.S. Provisional Patent Application No. 63/041,299 filed on June 19, 2020 and U.S. Provisional Patent Application No. 63/041,499 filed on June 19, 2020 are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

[0003] The present invention relates to an enclosure that isolates a transformer core from windings of the transformer. More specifically, the present invention relates to a cup and a lid that enclose the transformer core.

2. Description of the Related Art

[0004] Figs. 13A to 13E show a known transformer assembly 500 and a known electrical assembly 590. The transformer assembly 500 shown in Figs. 13A to 13E provides isolation of a transformer core 510 from transformer windings 520 by keeping the transformer core 510 at a neutral potential or a substantially neutral potential.

[0005] As shown in Figs. 13A to 13E, the transformer core 510 may be isolated from the transformer windings 520 by placing the transformer core 510 inside a cup 502. After placing the transformer core 510 inside the cup 502, as shown in Fig. 13A, the transformer core 510 is encapsulated or potted with an epoxy or a silicon material to secure the transformer core 510 within the cup 502, and a lid 503 is placed on the cup 502, as shown in Figs. 13B and 13C. Subsequently, as shown in Fig. 13D, the transformer windings 520 are wound around the cup 502 and lid 503. The transformer windings 520 must be wound by hand. As shown in Fig. 13E, the transformer windings 520 are then soldered to corresponding pads 552 on a substrate 550. The transformer windings 520 must be hand soldered to the substrate 550.

[0006] The transformer windings 520 shown in Figs. 13A to 13E may include, for example, two primary transformer windings 520P (including one feedback winding), and one or two secondary transformer windings 520S. Each of the transformer windings 520 shown in Figs.

13A to 13E requires at least two separate connections to the substrate 550: a start connection and a finish connection. A center tap may also be provided for each of the transformer windings.

[0007] In order to meet requirements set by the UL standards for creepage from the transformer core 510 to the transformer windings 520 and from the primary transformer winding 520P to the secondary transformer winding 520S, a center isolation barrier 501 is provided in the cup 502 shown in Figs. 13A to 13E. In addition, a center diameter of a hole through the cup 502 and the lid 503 that includes the center isolation barrier 501 shown in Figs. 13A to 13E is about 2 mm, and the center isolation barrier 501 fills a majority of the space defined by the center hole through the cup 502 and the lid 503. Accordingly, hand winding is required for the transformer windings 520 shown in Figs. 13A to 13E, which is costlier and slower than machine winding. In addition, manufacturing efficiency is limited due to the requirement that the transformer core 510 be encapsulated or potted prior to the transformer windings 520 being wound around the cup 502 and the lid 503.

[0008] Furthermore, since the transformer core 510 is encapsulated or potted only inside the cup 502, and before the transformer windings 520 are wound around the cup 502 and lid 503, voids can be created in the encapsulant or potting. Accordingly, there is a risk that the transformer core 510 may break due to thermal expansion or the like. Although a second encapsulating or potting process may be performed after winding the transformer windings 520 or after the transformer assembly 500 is mounted to the substrate 550, performing additional encapsulating or potting processes reduces manufacturing efficiency and increases cost.

SUMMARY OF THE INVENTION

[0009] To overcome the problems described above, preferred embodiments of the present invention provide transformer assemblies each with transformer windings that are able to be machine wound and with a cup and a lid that provide isolation between primary and secondary transformer windings.

[0010] According to a preferred embodiment of the present invention, a transformer assembly includes a transformer core, a cup that receives the transformer core, and a lid that engages with the cup and covers the transformer core. The cup includes an interior wall and an exterior wall, and the lid includes an interior wall that at least partially overlaps with the interior wall of the cup and an exterior wall that at least partially overlaps with the exterior wall of the cup.

[0011] The exterior wall of the cup and the exterior wall of the lid may include openings that at least partially overlap with one another. The transformer assembly may further include a first transformer winding wound around the transformer core and a second transformer winding wound around the cup and the lid. The first transformer winding may be exposed to an exterior of the cup and the lid via the openings in the exterior wall of the cup and in the exterior wall of the lid.

[0012] Each of the cup and the lid may include a center hole H with a diameter of about 4 mm or greater.

[0013] A bottom surface of the cup may include one or more mounting feet that locate the transformer assembly with respect to a substrate.

[0014] According to a preferred embodiment of the present invention, the transformer assembly is included in an electrical assembly. The electrical assembly further includes a substrate and a casing that at least partially surrounds the transformer assembly and the substrate.

[0015] The transformer assembly may be mounted to the substrate, and the casing may be filled with an epoxy to encapsulate the transformer assembly.

[0016] According to a preferred embodiment of the present invention, the transformer assembly is included in an electrical assembly. The electrical assembly further includes a substrate, the transformer assembly is mounted to the substrate, and the first and second transformer windings are electrically connected to corresponding pins on the substrate. [0017] A method of assembling and mounting a transformer according to a preferred embodiment of the present invention includes winding a primary winding around a transformer core, placing the transformer core inside a cup, covering the transformer core with a lid, and winding a secondary transformer winding around the cup and the lid. The cup includes an interior wall and an exterior wall. The lid includes an interior wall that at least partially overlaps with the interior wall of the cup and an exterior wall that at least partially overlaps with the exterior wall of the cup.

[0018] The above and other features, elements, steps, configurations, characteristics, and advantages of the present invention will become more apparent from the following detailed description of preferred embodiments of the present invention with reference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS [0019] Fig. 1 is a front perspective view of a transformer assembly.

[0020] Fig. 2 is a bottom perspective view of the transformer assembly shown in Fig. 1.

[0021] Figs. 3 and 4 are exploded perspective views of the transformer assembly shown in Fig. 1.

[0022] Fig. 5 is a cross-sectional view of the transformer assembly shown in Fig. 1.

[0023] Fig. 6 is a perspective view of a substrate to which the transformer assembly shown in Fig. 1 can be mounted.

[0024] Fig. 7 is a perspective view of an electrical assembly that includes the transformer assembly shown in Fig. 1 mounted to the substrate shown in Fig. 6.

[0025] Figs. 8 and 9 are a perspective view and a side view of the electrical assembly shown in Fig. 7 inserted to a casing.

[0026] Fig. 10 is a perspective view of the electrical assembly and casing shown in Fig. 8 with alternative pins provided on the substrate.

[0027] Figs. 11A and 11B show transformer windings and possible connections between the transformer assembly shown in Fig. 1 and a substrate.

[0028] Fig. 12 shows primary and secondary transformer windings of the transformer assembly shown in Fig. 1. [0029] Figs. 13A to 13E show a known transformer assembly and a known electrical assembly.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS [0030] The following description is in all aspects illustrative and not restrictive and should not be construed to restrict the applications or uses of preferred embodiments of the present invention in any manner.

[0031] Fig. 1 is a front perspective view of a transformer assembly 100. Fig. 2 is a bottom perspective view of the transformer assembly 100 shown in Fig. 1. Figs. 3 and 4 are exploded perspective views of the transformer assembly 100 shown in Fig. 1. Fig. 5 is a cross-sectional view of the transformer assembly 100 shown in Fig. 1. Fig. 12 shows primary transformer windings 111 and secondary transformer windings 112 of the transformer assembly 100 shown in Fig. 1.

[0032] As shown in Figs. 1-5 and 12, a primary transformer winding 111 is wound around a transformer core 110, and the transformer core 110 is placed inside a cup 120. The primary transformer winding 111 may be machine wound or hand wound around the transformer core 110. After placing the transformer core 110 inside the cup 120, a lid 130 is placed over the cup 120. Each of the transformer core 110, the cup 120, and the lid 130 may have a toroidal or substantially toroidal shape, for example. A diameter of the cup 120 and lid 130 may be about 10 mm, for example. The cup 120 includes an inner wall 121 and an outer wall 122, and the lid 130 similarly includes an inner wall 131 and an outer wall 132. Accordingly, a double-walled enclosure is provided for the primary transformer winding 111 and the transformer core 110, thereby providing isolation from a secondary transformer winding 112 that is wound around an exterior of the lid 130 and cup 120, as shown in Figs. 11A, 11B, and 12. The locations of the primary transformer winding 111 and the secondary transformer winding 112 can be reversed, i.e., the primary transformer winding 111 can be wound around the exterior of the lid 130 and cup 120, and the secondary transformer winding 112 can be wound around the transformer core 110.

[0033] The lid 130 may be interference-fit to the cup 120. Alternatively, the cup 120 may include fasteners or the like that at least partially engage with an upper surface of the lid 130 to secure the lid 130 to the cup 120. The lid 130 and the cup 120 may include corresponding recesses and pips that interlock, or a bayonet locking element of the lid 130 may be inserted into a recess provided in the inner wall 121 or the outer wall 122 of the cup 120. As an example, the cup 120 and the lid 130 may be made of an injection-molded plastic, for example, CRASTIN, diallyl phthalate (DAP), RYNITE, or the like.

[0034] As shown in Figs. 3-5, 7, and 12, the outer wall 132 of the lid 130 includes a lid opening 133 that is aligned with a cup opening 123 of the outer wall 122 of the cup 120 when the lid 130 is placed onto the cup 120. The cup opening 123 and the lid opening 133 provide a path for the primary transformer winding 111 to be electrically connected to another element, for example, a contact, pin, or other suitable element provided on a substrate.

[0035] After placing the lid 130 onto the cup 120, the secondary transformer winding 112 is wound around the cup 120 and the lid 130. Both the cup 120 and the lid 130 include a center hole H that accommodates the secondary transformer winding 112. For example, a center diameter of the center hole H through the cup 120 and the lid 130 can be about 2 mm or greater so that the secondary transformer winding 112 is able to be machine wound. However, the secondary transformer winding 112 may also be hand wound. In addition to considering if the secondary transformer winding 112 can be machine wound, other considerations, including, for example, product size, core size, etc., can be considered when determining the center diameter of the center hole H.

[0036] The transformer windings may include, for example, two primary transformer windings 111 (including one feedback or auxiliary winding), and one or two secondary transformer windings 112. Each of the transformer windings requires at least two separate connections to a substrate: a start connection and a finish connection. A center tap may also be provided for each of the transformer windings.

[0037] By winding the primary transformer winding 111 around the transformer core 110 and winding the secondary transformer winding 112 around the cup 120 and the lid 130, the primary and secondary transformer windings 112 are physically separated from one another. Furthermore, the double-walled enclosure provided by the cup 120 and the lid 130, particularly the inner wall 121 and the outer wall 122 of the cup 120 and the inner wall 131 and the outer wall 132 of the lid 130, electrically isolate the primary transformer winding 111 and the secondary transformer winding 112. Accordingly, even if the transformer assembly 100 is not fully encapsulated or potted, and voids are present in the center hole H of the transformer assembly 100, sufficient electrical isolation is still provided between the primary and secondary transformer windings 112.

[0038] As shown in Figs. 2 and 4, a bottom of the cup 120 includes a pair of mounting feet

125 and a mounting peg 126 to locate and stabilize the transformer assembly 100 during mounting onto a substrate. However, the number of mounting feet 125 and mounting pegs

126 is not limited to the numbers shown in the drawings.

[0039] Fig. 6 is a perspective view of a substrate 150 to which the transformer assembly 100 shown in Fig. 1 is mounted. Fig. 7 is a perspective view of an electrical assembly 200 that includes the transformer assembly 100 shown in Fig. 1 mounted on the substrate 150 shown in Fig. 6. Figs. 11A and 11B show transformer windings and connections between the transformer assembly 100 shown in Fig. 1 and the substrate 150 shown in Fig. 6.

[0040] As shown in Fig. 6, the substrate 150 includes through holes 155 that receive the mounting feet 125 of the transformer assembly 100 to locate the transformer assembly 100 with respect to the substrate 150. The transformer assembly 100 can be mounted to the substrate 150 in any suitable manner. For example, double-sided tape or the like may be provided to secure the transformer assembly 100 to the substrate 150. After the transformer assembly 100 is located and secured to the substrate 150, the transformer windings are wound around winding pins 151 connected to the substrate 150 by machine winding or hand winding, as shown in Figs. 11A and 11B. The transformer windings are then soldered to the corresponding winding pins 151 or to corresponding pads 152 on the substrate 150 by machine soldering or hand soldering, and an electrical assembly 200 is provided. The transformer windings can be soldered by any suitable method, including, for example, laser soldering, wave soldering, solder-dipping, and the like. The transformer windings can be connected to the winding pins 151 without any tension in the windings.

[0041] The winding pins 151 are not limited in their design and/or shape. For example, Figs. 6 and 7 show examples of z-shaped or s-shaped winding pins that are surface mounted, which are similar to the pins disclosed in Lee Francis, "SURFACE-MOUNT-ASSEMBLY Z-SHAPED PIN," U.S. Provisional Patent Application No. 63/041,299, filed on Jun 19, 2020, and Figs. 11A and 11B show examples of edge fit winding pins that are pressed onto sides of the substrate 150, which are similar to the pins disclosed in Lee Francis, "EDGE-FIT PINS," U.S. Provisional Patent Application No. 63/041,499, filed on Jun 19, 2020. Other types of winding pins may also be used. In addition, the transformer windings may be soldered or welded to corresponding pads 152 on the substrate 150. Furthermore, machine soldering or welding is preferred to hand soldering, as hand soldering may cause mechanical weaknesses, for example, thinning or fracturing of the wires included in the transformer windings.

[0042] As shown in Figs. 6 and 7, the substrate 150 also includes mounting pins 159 to electrically connect and mount the transformer assembly 100 and substrate 150 to another electrical component, another substrate, an electrical connector, or the like, for example.

[0043] Figs. 8 and 9 are a perspective view and a side view of the electrical assembly 200 shown in Fig. 7 inserted into a casing 210. Fig. 10 is a perspective view of the electrical assembly 200 and casing 210 shown in Fig. 8 with the edge fit pins shown in Figs. 11A and 11B. [0044] After the electrical assembly 200 is provided by mounting the transformer assembly 100 to the substrate 150 with the transformer windings connected to the corresponding pins on the substrate 150, the electrical assembly 200 is placed into a casing 210, as shown in Figs. 8 10

[0045] The casing 210 may then be filled with a material, for example, with an epoxy or a silicon material, to encapsulate or pot the transformer assembly 100. Accordingly, not only is the transformer assembly 100 able to be mechanically secured to the substrate 150, a space in the center of the transformer core 110 is also able to be filled with the material to further isolate the primary transformer windings 111 from the secondary transformer windings 112. The material can fully fill the space in the center of the cup 120, and no void space is present in the center of the transformer core 110. However, as explained above, the double-walled enclosure provided by the cup 120 and the lid 130 electrically isolates the primary transformer winding 111 and the secondary transformer winding 112. Accordingly, it is not necessary to fully encapsulate or pot the transformer assembly 100, because sufficient isolation can be provided between the primary and secondary transformer windings 112, even if voids are present in the center hole H of the transformer assembly 100.

[0046] As shown in Figs. 3-5, 7, and 12, the outer wall 132 of the lid 130 includes a lid opening 133 that is aligned with a cup opening 123 of the outer wall 122 of the cup 120 when the lid 130 is placed onto the cup 120. The cup opening 123 and the lid opening 133 enable an encapsulating or potting material to easily flow into an interior of the transformer assembly 100 to secure the transformer core 110 and the primary transformer winding 111. However, additional openings may also be provided in the cup 120 and lid 130, for example, in an upper surface of the lid 130, provided that the additional openings do not compromise creepage and clearance distances from the primary transformer winding 111 to the secondary transformer winding 112.

[0047] The secondary transformer windings 112 are able to be easily wound around the cup 120 and lid 130 by machine winding or hand winding due to the increased space provided by the center hole H of the cup 120 and the center hole H of the lid 130. Physical separation and further electrical isolation of the primary and secondary transformer windings 112 can be provided by the double walled structure of the cup 120 and the lid 130. In contrast, the transformer assembly 500 shown in Figs. 13A-13E includes an isolation barrier that is molded into the cup, which makes winding the transformer windings difficult and necessitates hand winding.

[0048] The transformer core 110 may be encapsulated or potted after the transformer windings have been wound. Accordingly, a single encapsulating or potting process may be implemented to secure the transformer core 110 inside the cup 120, to fill any voids in the center holes H of the cup 120 and lid 130, and to further secure the transformer assembly 100 to the substrate 150. Thus, manufacturing efficiency is able to be significantly increased while also significantly reducing cost.

[0049] It should be understood that the foregoing description is only illustrative of the present invention. Various alternatives and modifications can be devised by those skilled in the art without departing from the present invention. Accordingly, the present invention is intended to embrace all such alternatives, modifications, and variances that fall within the scope of the appended claims.