Electromagnetic shielding device and wire harness

An electromagnetic shielding device, where the electromagnetic shielding device includes a metal sheet; and a pair of brackets that are formed of a conductive material, and that annularly retain a first outer edge out of four outer edges of the metal sheet, and a second outer edge located opposite to the first outer edge.

This application is the U.S. National Phase of PCT/JP2017/016033 filed Apr. 21, 2017, which claims priority from JP 2016-090490 filed Apr. 28, 2016, the entire disclosure of which is incorporated herein by reference.

BACKGROUND

The present disclosure relates to an electromagnetic shielding device that shields noise electromagnetic waves, and a wire harness including the same.

JP 2013-176279A discloses an electromagnetic shielding device that shields electromagnetic noise by surrounding a plurality of wires with a metal cloth. The electromagnetic shielding device includes two brackets that annularly retain a first outer edge portion of the metal cloth and a second outer edge portion located opposite thereto.

SUMMARY

Meanwhile, for the electromagnetic shielding device of JP 2013-176279A, the metal cloth is joined to two long portions included in the brackets by crimping or welding. However, the two long portions may not be able to provide sufficient joining strength. For this reason, it may be difficult to maintain the shape of the metal cloth, thus possibly reducing the noise absorption performance.

An exemplary aspect of the disclosure provides a technique for facilitating the maintenance of the shape of a metal sheet in an electromagnetic shielding device.

In order to solve the above-described problems, a first aspect is directed to an electromagnetic shielding device including: a metal sheet; and a pair of brackets that are formed of a conductive material, and that annularly retain a first outer edge out of four outer edges of the metal sheet, and a second outer edge located opposite to the first outer edge, wherein each bracket of the pair of brackets includes a first long portion, a first short portion, a second long portion, and a second short portion that are arranged in series along each of the first outer edge and the second outer edge, the first long portion, the first short portion, and the second long portion are joined to the metal sheet, each of the first short portion and the second short portion is shorter than each of the first long portion and the second long portion, opposite ends of the first short portion are continuous with the first long portion and the second long portion, respectively, via bending portions, one of the opposite ends of the second short portion is continuous with the second long portion via a bending portion, and the other end is coupled to the first long portion via a coupler, the coupler is a portion extending outwardly from the other end of the second short portion, and the other end of the second short portion is eccentrically located at a position closer to the first long portion than to the second long portion.

A second aspect is directed to the electromagnetic shielding device according to the first aspect, wherein the coupler includes: a first coupling piece that is continuous with the first long portion, and that is formed in a plate shape expanding parallel to a principal surface of the first long portion; and a second coupling piece that is continuous with the second short portion, and that is formed in a plate shape expanding perpendicularly to the second short portion.

A third aspect is directed to the electromagnetic shielding device according to the first or second aspect, wherein the second short portion is connected to the metal sheet.

A fourth aspect is directed to an electromagnetic shielding device including: a metal sheet; and a pair of brackets that are formed of a conductive material, and that annularly retain a first outer edge out of four outer edges of the metal sheet, and a second outer edge located opposite to the first outer edge, wherein each bracket of the pair of brackets includes a first long portion, a first short portion, a second long portion, a second short portion, and a third short portion that are arranged in series along each of the first outer edge and the second outer edge of the metal sheet, the first long portion, the first short portion, and the second long portion are joined to the metal sheet, each of the first short portion, the second short portion, and the third short portion is shorter than each of the first long portion and the second long portion, opposite ends of the first short portion are continuous with the first long portion and the second long portion, respectively, via bending portions, one of opposite ends of the second short portion is continuous with the second long portion via a first bending portion, and the other end is coupled to one end of the third short portion via a coupler and another end of the third short portion is continuous with the first long portion via a second bending portion.

A fifth aspect is directed to the electromagnetic shielding device according to any one of the first to fourth aspects, wherein each of the bending portions between the first and second long portions and the first short portion is a portion that is not joined to the metal sheet.

A sixth aspect is directed to the electromagnetic shielding device according to any one of the first to fifth aspects, wherein the first long portion, the second long portion, and the first short portion each have a base and a folded-back portion that is continuous with the base, and the metal sheet is sandwiched and retained between the base and the folded-back portion.

A seventh aspect is directed to a wire hireness including the electromagnetic shielding device according to any one of the first to sixth aspects, and a wire inserted through the electromagnetic shielding device.

An eighth aspect is directed to the wire harness according to the seventh aspect, wherein the number of the wires inserted through the electromagnetic shielding device is a multiple of 3.

With the electromagnetic shielding device according to the first aspect, in addition to the first long portion and the second long portion, the first short portion connecting these portions is also joined to the metal sheet. This makes it possible to firmly attach the brackets to the metal sheet. Accordingly, the shape maintenance of the metal sheet is facilitated, thus making it possible to prevent the reduction of the noise absorption performance. Then, by elongating a portion extending from one end to the other end of the second short portion such that the other end of the second short portion is eccentrically located at a position closer to the first long portion, it is possible to elongate the region that is to be joined to the metal sheet. This allows the second short portion to be stably joined to the metal sheet.

With the electromagnetic shielding device according to the second aspect, by bending each of the bending portions located between the first long portion, the first short portion, the second long portion, and the second short portion so as to cause the first coupling piece and the second coupling piece to overlap substantially parallel to each other, the first outer edge or the second outer edge of the metal sheet can be formed into an annular shape.

With the electromagnetic shielding device according to the third aspect, by joining another short portion, which is the second short portion connecting the first long portion and the second long portion, to the metal sheet, it is possible to firmly attach the brackets to the metal sheet.

With the electromagnetic shielding device according to the fourth aspect, in addition to the first long portion and the second long portion, the first short portion connecting these portions is also joined to the metal sheet. This allows the brackets to be firmly attached to the metal sheet. Accordingly, the shape maintenance of the metal sheet is facilitated, thus making it possible to prevent the reduction of the noise absorption performance.

With the electromagnetic shielding device according to the fifth aspect, the metal sheet is not joined to each of the bending portions, and, therefore, the metal sheet joined to the brackets can be suppressed from receiving a stress from the bending portions during bending of the brackets. Accordingly, it is possible to reduce a damage such as peeling or tearing of the metal sheet.

With the electromagnetic shielding device according to the sixth aspect, the metal sheet can be clamped by bending the folded-back portions such that the folded-back portions approach the base portion. Accordingly, it is possible to easily join the metal sheet to the first long portion, the second long portion, and the first short portion.

With the wire harness according to the second aspect, in addition to the first long portion and the second long portion, the first short portion connecting these portions is also joined to the metal sheet. This allows the brackets to be firmly attached to the metal sheet. Accordingly, the shape maintenance of the metal sheet is facilitated, thus making it possible to prevent the reduction of the noise absorption performance. Therefore, it is possible to suitably shield the electromagnetic noise from the wire.

DETAILED DESCRIPTION OF EMBODIMENTS

FIG. 1is a plan view of an electromagnetic shielding device10according to Embodiment 1.FIG. 2is a front view of the electromagnetic shielding device10according to Embodiment 1.FIG. 3is a cross-sectional view of a joining portion (crimping portion) where a long portion221is joined to a metal sheet30in the electromagnetic shielding device10.FIG. 4is a plan view of a wire harness100according to Embodiment 1.FIG. 5is a front view of the wire harness100according to Embodiment 1. The electromagnetic shielding device10shown inFIGS. 1 and 2is in a developed state, and the electromagnetic shielding device10shown inFIGS. 4 and 5is in an annually retained state.

The electromagnetic shielding device10is a component that is to be attached to the wires of a wire harness mounted to a vehicle, and that shields noise electromagnetic waves by using a conductive metal sheet (metal sheet30) surrounding the wires.

The electromagnetic shielding device10includes a pair of main bracket portions21and22, a metal sheet30, and a pair of screws40serving as fixing devices. The metal sheet30is joined to each of the main bracket portions21and22. The pair of screws40are fixing devices for annularly retaining the respective corresponding main bracket portions21and22.

The pair of brackets body portions21and22and the pair of screws40constitute a pair of brackets2A and2B. That is, the electromagnetic shielding device10includes the pair of brackets2A and2B.

As shown inFIG. 5, the bracket2A is fixed to a metal casing (casing8) of a device to which one end of a wire9is to be connected, and the bracket2B is fixed to a casing of a device to which the other end of the wire9is to be connected.

As shown inFIGS. 4 and 5, the wire harness100includes a plurality of (here, three) wires9, and an electromagnetic shielding device10that collectively covers around the plurality of wires9. The wire harness100includes a tubular electromagnetic shielding device10, and a plurality of wires9inserted through the tubular electromagnetic shielding device10. Note that it is also conceivable that the electromagnetic shielding device10of the wire harness100covers only one wire9. It is also conceivable that the electromagnetic shielding device10covers the number of wires that is a multiple of 3 (3, 6, 9 . . . ).

Each wire9is an insulated wire composed of a core wire made of a conductive material, and an insulating coating made of an insulating material and covering around the core wire. Ordinarily, a metal terminal (not shown) is connected to the core wire at an end portion of the wire9. Note that the wire9may be retained by a wire retaining member (not shown). It is conceivable that such a wire retaining member is a thermoplastic resin member molded by insert molding with the wire9as an insert portion.

Metal Sheet

The metal sheet30of the electromagnetic shielding device10is a sheet-like member that is a woven fabric of metal yarns. The metal sheet30is a metal cloth having a stich structure formed, for example, by weaving yarns of a metal composed mainly of a conductive metal (e.g., copper) such that the yarns intersect longitudinally and transversely. Note that it is preferable that the metal sheet30has flexibility attributed to a resin material attached to the metal cloth. The electromagnetic shielding device10may include a metal foil in place of the metal cloth as the metal sheet30. The metal sheet30has conductivity and flexibility.

In the following description, four outer edges of the metal sheet30are referred to as a first outer edge portion31, a second outer edge portion32, a third outer edge portion33, and a fourth outer edge portion34(i.e., outer edges), respectively.

The first outer edge portion31is a portion occupying a predetermined range extending inwardly from an outer edge constituting one end in the longitudinal direction (axial direction) of a wire9to which it is to be attached, among the four outer edges of the metal sheet30. The second outer edge portion32is a portion occupying a predetermined range extending inwardly from the outer edge located opposite to the first outer edge portion31, among the four outer edges of the metal sheet30.

The third outer edge portion33and the fourth outer edge portion34are the other outer edge portions of the metal sheet30that are not the first outer edge portion31or the second outer edge portion32. The third outer edge portion33and the fourth outer edge portion34are outer edge portions at the other ends, surrounding the wire9of the metal sheet30.

In the electromagnetic shielding device10, the metal sheet30is joined to the main bracket portion21at the first outer edge portion31. The metal sheet30is joined to the main bracket portion22at the second outer edge portion32. The metal sheet30is electrically connected to a casing8of another device via the pair of brackets2A and2B, thus providing a casing ground.

Bracket

The main bracket portions21and22are plate-shaped members formed of a conductive material. The main bracket portions21and22are formed in an annular shape as shown inFIGS. 4 and 5by bending.

The main bracket portions21and22are members made of, for example, a metal such as a copper alloy, iron, or stainless steel, and have a plated layer formed on the surface thereof as needed. The main bracket portions21and22are members that are to be fixed to a metal casing8, and that relay electrical connection between the metal sheet30and the casing8.

The shapes of the main bracket portions21and22are mirror images of each other, and, therefore, the structure of only the main bracket portion21will be described in the following.

The main bracket portion21includes a plate-shaped base portion201extending along the first outer edge portion31of the metal sheet30. By folding over the base portion201at three locations (bending portions241,242, and243), the main bracket portion21is formed to an annular shape (a substantially quadrangular tubular shape) (seeFIG. 5). The base portion201is divided into a pair of long portions221and222and a pair of short portions231and232by the three bending portions241,242, and243.

Long Portion

The pair of long portions221and222are portions that are to be placed so as to span across a plurality of wires9to be shielded. Here, the pair of long portions221and222have substantially the same length. In the annular main bracket portions21and22, the pair of long portions221and222are opposed and extend parallel to each other. However, the shape and the length of the pair of long portions221and222are not limited thereto, and vary depending on the arrangement status of the plurality of wires9, the shape of the wire retaining member, or the like. For example, the long portion221and222may have a nonlinear shape, such as a shape having a portion that can be bent in an arc shape.

The pair of long portions221and222are joined to the metal sheet30in a state in which they are arranged in series along the first outer edge portion31. The metal sheet30and the pair of long portions221and222are joined together, for example, by crimping or welding, or both. As will be described later, joining by crimping is used here. The pair of long portions221and222of the body portion21are joined to the first outer edge portion31, and the pair of long portions221and222of the main bracket portion22are joined to the second outer edge portion32.

The pair of long portions221and222respectively include plate-shaped folded-back portions41and42each of which is coupled to the base portion201at one end. By crimping the folded-back portions41and42to the base portion20with the metal sheet30sandwiched therebetween, the metal sheet30is clamped by the base portion201and the folded-back portions41and42(seeFIG. 3).

Short Portion

The pair of short portions231and232are joined to the metal sheet30in a state in which they are arranged in series along the first outer edge portion31. Each of the pair of short portions231and232is shorter than each of the pair of long portions221and222. A first end of the short portion231is continuous with a second end of the long portion221via the bending portion241, and a second end of the short portion231is continuous with a first end of the long portion222via the bending portion242. A first end of the short portion232is continuous with a second end of the long portion222via the bending portion243. Here, the pair of short portions231and232have the substantially the same length. In the annular main bracket portion21, the pair of short portions231and232are opposed so as to extend parallel to each other. However, the shape and the length of the pair of short portions231and232are not limited thereto, and vary depending on the arrangement status of the plurality of wires9, the shape of the wire retaining member, or the like.

The pair of short portions231and232respectively include plate-shaped folded-back portions43and44each of which is coupled to the base portion201at one end. By crimping the folded-back portions43and44to the base portion201with the metal sheet30sandwiched therebetween, the metal sheet30is clamped by the base portion201and the folded-back portions43and44.

When the metal sheet30is joined to the pair of brackets2A and2B by welding, breakage or the like may occur in the metal sheet30during welding. Therefore, it is preferable that the metal sheet30is joined by crimping the folded-back portions41and44.

Bending Portion

As described above, the three bending portions241to243are portions that are to be bent in a valley shape at the time of shaping the main bracket portions21and22into an annular shape. Note that the bending portions241to243are not necessarily bent so as to be crooked, and also may be bent in an arc shape.

As shown inFIGS. 1, 2, and 5, the bending portions241to243are positioned so as not to overlap the folded-back portions41and44. In other words, the bending portions241,242, and243are unjoined portions that are not to be joined to the metal sheet30. The thickness of the bending portions241to243is set to be equal to the thickness of the base portion201, and, therefore, bending can be more easily performed at these portions than at the joined portions (the portions overlapping the bending portions241to243of the base portion201).

Here, “join” means attaching or fixing an object to another object by means of crimping, welding, or the like. That is, an unjoined portion is a portion where the metal sheet30can be easily separated from the main bracket portions21and22.

By forming the bending portions241to243as unjointed portions, it is possible to suppress the bending portions241to243from exerting a stress on the metal sheet30when they are bent at these portions. Accordingly, the metal sheet30can be annularly retained in a suitable manner by the main bracket portions21and22that have been bent.

Note that as described above, joining between the main bracket portions21and22and the metal sheet30may be performed by welding. In this case, the folded-back portions41and44can be omitted. For joining by welding as well, it is preferable that the bending portions241to243are unjoined portions that are not to be welded. This can suppress the bending portions241to243from exerting a stress on the metal sheet30when they are bent at the bending portions241to243. Accordingly, for example, by bending the main bracket portions21and22, it is possible to suppress the occurrence of a damage such as peeling or tearing at the welded portion (the portion of the metal sheet30to which the metal sheet30or the main bracket portions21and22have been bonded by being melted and solidified) of the metal sheet30.

Coupling Portion

The coupling portion25(i.e., coupler) includes coupling pieces251and252that are formed in plate shapes being continuous with opposite end portions, respectively, of the base portion201. The coupling piece251is continuous with the first end side of the long portion221in the base portion201, and the coupling piece252is continuous with the second end side of the short portion232of the base portion201.

As shown inFIGS. 1 and 2, the coupling piece251is a plate-shaped portion expanding parallel to a principal surface (a surface that is the widest, and is to be joined to the metal sheet30) of the base portion201, and the coupling piece252is a plate-shaped portion expanding in a direction perpendicular to the principal surface of the base portion201. That is, in the main bracket portions21and22in the developed state, the coupling pieces251and252are plate-shaped portions that are orthogonal to each other. When the base portion201has been bent at the three bending portions241to243, the coupling piece252becomes substantially parallel to the coupling piece251, and overlaps therewith, as shown inFIG. 5. Consequently, the main bracket portions21and22are formed into an annular shape, thus forming the first outer edge portion31and the second outer edge portion32of the metal sheet30into an annular shape.

Screw holes251H and252H as through holes are formed in the coupling pieces251and252. In the main bracket portions21and22in the annular state, the coupling pieces251and252are caused to overlap with each other, and, thereby, the screw holes251H and252H vertically overlap. By fitting a screw40to screw holes251H and252H in this state, the coupling pieces251and252are coupled. Consequently, the opposite ends (i.e., the first end of the long portion221and the second end of the short portion232) of the base portion201are coupled via the coupling portion25, and the main bracket portions21and22are annularly retained.

In the brackets2A and2B, the coupling portion25including the coupling pieces251and252and the screw40are an example of the coupling portion. Note, however, that the coupling portion is not limited to the configuration including the coupling pieces251and252and the screw40, and design modification may be made thereto as necessary. For example, the coupling pieces251and252may not be necessarily coupled using the screw40, and may be coupled by another method (e.g., fitting, welding, an adhesive, tape, or crimping).

In the pair of brackets2A and2B in the annular state, the coupling portion25may not necessarily extend parallel to the base portion201, and the coupling portion25may extend in a direction inclined relative to the base portion201.

When the brackets2A and2B have been annularly retained, the metal sheet30that has been joined to the main bracket portion21and the main bracket portion22is retained in a tubular shape surrounding the wires9.

In the annular brackets2A and2B, the coupling piece252of the coupling portion25is a portion extending outwardly from the second end of the short portion232(the second short portion). Then, the second end (i.e., the bending portion that is continuous with the coupling piece252) of the short portion232is eccentrically located at a position closer to the long portion221(first long portion) than to the long portion222(second long portion). Thus, by elongating a portion extending from the first end to the second end of the short portion232, the region (joining surface) of the short portion232that is to be joined to the metal sheet30can be made as long as possible. This can increase the length of the folded-back portion44, thus making it possible to more firmly join the metal sheet30to the brackets2A and2B.

With the electromagnetic shielding device10, in addition to the pair of long portions221and222, the short portion231connecting these portions is also joined to the metal sheet30, thus making it possible to firmly attach the pair of brackets2A and2B to the metal sheet30.

Furthermore, the short portion232that couples the pair of long portions221and222via the coupling portion25is also joined to the metal sheet30, thus making it possible to firmly attach the pair of brackets2A and2B to the metal sheet30.

By firmly attaching the metal sheet30to the pair of brackets2A and2B, it is possible to suppress the metal sheet30from losing its shape. This can prevent the reduction of the noise absorption performance of the electromagnetic shielding device10.

Note that in the above-described embodiment, each of the main bracket portions21and22is constituted by one plate-shaped member. However, it is conceivable that they are constituted by a combination of a plurality of members. For example, it is conceivable that the long portion221and the short portion231are included in one member, the long portion222and the short portion232are included in one member, and these members are combined. It is also conceivable that the long portion221, the long portion222, the short portion231, and the short portion232are formed as members separate from each other, and these members are combined.

Next, Embodiment 2 will be described. Note that in the following description, elements having the same functions as the elements already described are denoted by the same reference numerals or reference numerals with letters of alphabets added thereto, and the detailed description thereof may be omitted.

FIG. 6is a front view of a wire harness100A including an electromagnetic shielding device10A according to Embodiment 2. The electromagnetic shielding device10A includes a bracket2C including a main bracket portion21A. The main bracket portion21A has a configuration similar to that of the main bracket portion21, but its portion corresponding to the short portion232is formed as a short portion232a(second short portion). The second end side of the short portion232ais coupled to the long portion221via the coupling portion25and a short portion232b(third short portion). The short portion232bis continuous with the first end side of the long portion221via a bending portion244.

For the present example, the second end of the short portion232ais set at substantially the center between the long portion221and the long portion222, so that the short portion232ais shorter than the short portion232, and the bending portion for being joined to the metal sheet30is omitted. Accordingly, the bracket2C is inferior in joining strength to the bracket2A in that it is not joined to the metal sheet30at the short portion232a. However, in addition to the pair of long portions221and222, the short portion231is also joined to the metal sheet30, thus making it possible to firmly attach the bracket2C to the metal sheet30.

While the present disclosure has been described in detail, the foregoing description is in all aspects illustrative and the disclosure is not limited thereto. It will be appreciated that numerous modifications not illustrated herein can be made without departing from the scope of the present disclosure. In addition, the configurations described in the embodiments and modifications may be combined or omitted as appropriate as long as there are no mutual inconsistencies.