JP7239870B2 - Electromagnetic wave shielding device - Google Patents

Description

The present invention relates to an electromagnetic wave shielding device.

In this technical field, for example, by covering an electronic device such as a control board of a home electric appliance and an ECU (electronic control unit) of an automobile with a shielding member containing a conductive layer made of a conductor such as metal, It is known to reduce the propagation of electromagnetic waves to the electronic device from the outside and/or from the outside (see, for example, Patent Document 1). In addition, shielding electromagnetic waves radiated from units such as battery packs mounted in electric vehicles such as electric vehicles (EV), hybrid vehicles (HV), and plug-in hybrid vehicles (PHV) for occupants and other electronic devices Various techniques have been developed to reduce the effects of electromagnetic waves on the like.

FIG. 1 is a schematic perspective view showing an example of the configuration of a conventional electromagnetic wave shielding device (hereinafter sometimes referred to as "conventional device"). Conventional device 100 blocks electromagnetic waves radiated from unit 1, which is the source of electromagnetic waves, by shielding member 3 including a conductive layer. The shielding member 3 is disposed so as to face the top surface of the unit 1 (the surface on the positive side of the Z axis) across the high-voltage wiring 2, which is the portion of the unit 1 that generates electromagnetic waves.

As a result, due to the electromagnetic waves radiated from the high-voltage wiring 2 provided in the unit 1, the direction of the current 5 (hereinafter sometimes referred to as "high-voltage wiring current") (thick black arrow) flowing through the high-voltage wiring 2 An induced current 6 (white arrow) is generated in the shielding member 3 in the opposite direction (positive direction of the X axis) to (negative direction of the X axis). The magnetic field generated by the induced current 6 cancels the electromagnetic waves radiated from the high-voltage wiring 2 and reduces the electromagnetic waves propagating above the shielding member 3 (positive direction of the Z axis).

However, the region where the induced current 6 can flow is narrow at the ends of the shielding member 3 , and the induced current 6 tends to stray in a direction different from that in the central portion of the shielding member 3 . Such a current 7 (hereinafter sometimes referred to as "stray current") (solid arrow) generates a new magnetic field (hereinafter referred to as "stray magnetic field ). As a result, for example, problems such as deterioration of shielding performance against electromagnetic waves radiated from the high-voltage wiring 2 and generation of secondary radiation of electromagnetic waves corresponding to stray magnetic fields may occur.

Japanese Patent Application Laid-Open No. 2010-098006

As described above, the electromagnetic wave shielding device according to the prior art still has problems to be solved, such as deterioration of shielding performance against electromagnetic waves radiated from the unit and occurrence of secondary radiation of electromagnetic waves. That is, in the technical field, there is a demand for an electromagnetic wave shielding device capable of improving the shielding performance of electromagnetic waves emitted from a unit while reducing the influence of secondary radiation of electromagnetic waves.

Therefore, as a result of intensive research, the present inventors have found that the secondary radiation of electromagnetic waves caused by stray currents can be reduced and secondary radiation of electromagnetic waves caused by stray currents can be reduced by electrically connecting both ends of a conductive layer that constitutes a shielding member to form a ring circuit. It was found that the shielding performance of electromagnetic waves emitted from the unit can be improved.

More specifically, the electromagnetic wave shielding device according to the present invention (hereinafter sometimes referred to as the "device of the present invention") is a shielding member including a conductive layer that emits electromagnetic waves from a unit that is a source of electromagnetic waves. It is an electromagnetic wave shielding device that blocks electromagnetic waves. The device of the invention further comprises at least one current return zone comprising a conductive path formed by a line or strip of conductor. The conductive layer is disposed at least in a region facing the unit with an electromagnetic wave generating portion, which is a portion of the unit generating an electromagnetic wave, interposed therebetween. A conductive path is connected in electrical communication with the two ends of the conductive layer via the opposite side of the unit from the conductive layer to form a circular circuit.

According to the device of the present invention, it is possible to reduce the secondary radiation of electromagnetic waves caused by stray currents and improve the shielding performance of electromagnetic waves emitted from the unit.

Other objects, features and attendant advantages of the present invention will be readily understood from the description of each embodiment of the present invention described with reference to the following drawings.

1 is a schematic perspective view showing an example of a configuration of an electromagnetic wave shielding device (conventional device) according to a conventional technique; FIG. 1 is a schematic perspective view showing an example of the configuration of an electromagnetic wave shielding device (first device) according to a first embodiment of the present invention; FIG. FIG. 2 is a schematic diagram showing one example in which the first device is applied to a battery pack included in an electric vehicle; FIG. 10 is a schematic perspective view showing an example of the configuration of an electromagnetic wave shielding device (second device) according to a second embodiment of the present invention; 8A and 8B are schematic (a) plan view and (b) cross-sectional view showing an example of the configuration of a current return band provided in an electromagnetic wave shielding device (third device) according to a third embodiment of the present invention; FIG. FIG. 4 is a schematic diagram for explaining the effect achieved by the third device; FIG. 10 is a schematic diagram showing an example of the configuration around the branching member in the third device provided with the branching member. FIG. 11 is a schematic perspective view showing an example of the configuration of an electromagnetic wave shielding device (fourth device) according to a fourth embodiment of the present invention; FIG. 11 is a schematic perspective view showing an example of a connection form between a conductive layer that constitutes a shielding member provided in the fourth device and a conductive path included in a current return band; (a) is a schematic perspective view showing an example of the configuration of an electromagnetic wave shielding device (fifth device) according to a fifth embodiment of the present invention, and (b) is an example of arrangement of monitor wiring provided in the fifth device. FIG. 2 is a schematic front view showing the . FIG. 11 is a schematic perspective view showing an example of an arrangement state of boosters provided in the fifth device; FIG. 11 is a circuit diagram showing an example of a configuration of a booster included in the fifth device; (a) is a block diagram showing an example of the process of passing a current signal _I0 corresponding to the monitor wiring current through a band-pass filter to extract a current signal _I1 in the target frequency band; 1 is a graph illustrating waveforms of ₀ and current signal _I1 ; FIG. 4 is a block diagram showing an example of arithmetic logic for calculating a suitable canceling current _I2 by applying different amplification factors to the current signal _I1 depending on the frequency;

<<1st Embodiment>>
An electromagnetic wave shielding device (hereinafter sometimes referred to as "first device") according to a first embodiment of the present invention will be described below.

<composition>
FIG. 2 is a schematic perspective view showing an example of the configuration of the first device. The first device 101 is an electromagnetic wave shielding device that blocks electromagnetic waves radiated from the unit 1 that is the source of the electromagnetic waves by means of the shielding member 3 including a conductive layer. The unit 1 is not particularly limited as long as it is a device or the like that is a source of electromagnetic waves. Specific examples of such a unit 1 include, for example, battery packs mounted on electric vehicles such as electric vehicles (EV), hybrid vehicles (HV), and plug-in hybrid vehicles (PHV).

The conductive layer is made of a conductor such as metal, and at least a part of the surface thereof excluding a connection portion with a conductive path to be described later may be covered with an insulator such as resin. As a result, even if the shielding member 3 comes into contact with another member disposed near the shielding member 3 that is made of a conductor, current leakage to the member can be prevented. . Moreover, since most of the conductive layer is covered and protected by the insulator, the work of laying the shield member 3 on the unit 1 can be made easier.

The first device 101 further comprises at least one current return strip 4 comprising a conductive path formed by a wire or strip of conductor. In the example shown in FIG. 2 the first device 101 comprises three current return bands 4 . Typically, the conductive paths are made of wire or strip of metal. At least a part of the surface of the conductive path, excluding the connecting portion with the conductive layer, may be covered with an insulator such as resin. As a result, even if the current feedback band 4 comes into contact with another member disposed in the vicinity of the current feedback band 4 which is made of a conductor, current leakage to the member can be prevented. can be done. Moreover, since most of the conductive path is covered and protected by the insulator, the work of laying the current return belt 4 to the unit 1 can be made easier. If the surface of the unit 1 is made of an insulator, the current feedback belt 4 may be formed by printing a conductive path using conductive paint, for example.

The conductive layer includes or covers at least an area facing the unit 1 across the electromagnetic wave generating section 2, which is the part of the unit 1 that generates electromagnetic waves (hereinafter sometimes referred to as a "shielding target area"). are arranged as follows. In the example shown in FIG. 2, the top surface of the battery pack as the unit 1 (the surface on the positive side of the Z axis) faces the top surface of the battery pack with the high-voltage wiring as the electromagnetic wave generator 2 interposed therebetween. The area is a shielding target area, and the shielding member 3 is arranged so that the conductive layer includes or covers the shielding target area. Thereby, the electromagnetic waves radiated from the electromagnetic wave generator 2 can be effectively shielded. As a result, for example, the influence of electromagnetic waves on other electronic devices and/or the human body existing near the unit 1 can be effectively reduced.

The conductive layer may be disposed so as to include or cover only the area to be shielded, or may be disposed so as to include or cover a wider area including the area to be shielded. In addition, the shape and size of the conductive layer are not particularly limited as long as at least part of the conductive layer can be arranged to include or cover the area to be shielded. It can have a shape such as a plate shape that can be covered or a shape such as a tubular shape that allows the electromagnetic wave generator 2 (for example, high-voltage wiring) to be inserted therein.

The conductive path is connected in electrical communication with the two ends of the conductive layer via the opposite side of the conductive layer of the unit 1 to form a circular circuit. In the example shown in FIG. 2, two ends of the conductive layer included in the shielding member 3 (both ends in the X-axis direction The conductive paths included in the three current return bands 4 are connected to the two ends of the conductive layer so as to electrically communicate the ends located at the . In other words, the unit 1 is surrounded by an annular circuit formed by the conductive layers and the conductive paths. As a result, the induced current 6 (white arrow) generated in the conductive layer by the electromagnetic waves radiated from the electromagnetic wave generator 2 is converted into a feedback current 8 (broken arrow) that flows circularly through the conductive path of the current feedback band 4. Since it can flow, stray currents such as those described with respect to conventional devices can be reduced. As a result, it is possible to reduce problems such as deterioration of shielding performance against electromagnetic waves radiated from high-voltage wiring and generation of secondary radiation of electromagnetic waves corresponding to stray magnetic fields (such as those observed in the conventional device described above).

Electromagnetic waves are also radiated from the feedback current 8, but the feedback current 8 flows in the Z-axis direction in the conductive path on the side surface of the unit 1 (the surface parallel to the Z-axis). It is difficult for the magnetic lines of force generated by the shielding member 3 to propagate upward (toward the positive direction of the Z axis). On the other hand, since the feedback current 8 flows in the XY plane in the conductive path on the bottom side of the unit 1 , the lines of magnetic force caused by this feedback current 8 can be directed upward from the shielding member 3 . However, this feedback current 8 is farther from the shielding member 3 than the high-voltage wiring current 5, and the unit 1 exists between this feedback current 8 and the shielding member 3. As a result, this feedback current 8 causes It is also difficult for the magnetic lines of force generated above the shielding member 3 to propagate. That is, magnetic field irradiation (secondary radiation from the current feedback band 4) above the shielding member 3 due to radiation of electromagnetic waves caused by the feedback current 8 flowing through the conductive path of the current feedback band 4 is small.

<effect>
As described above, according to the first device, it is possible to reduce the secondary radiation of electromagnetic waves caused by stray currents and improve the shielding performance of electromagnetic waves emitted from the unit.

FIG. 3 is a schematic diagram showing one example in which the first device is applied to a battery pack included in an electric vehicle. In the electric vehicle 30, a battery pack 34 as a unit 1 that is a source of electromagnetic waves is mounted under the floor of a cabin 33 in which passengers 31 and 32 ride. A high-voltage wiring 36 for supplying electric power to an electric motor 35 as a drive source of the electric vehicle 30 is arranged on the top surface of the battery pack 34 (the surface on the positive side of the Z-axis). A high-voltage wiring current flows through the high-voltage wiring 36, and an electromagnetic wave is generated accordingly. That is, the high-voltage wiring 36 corresponds to the electromagnetic wave generator 2 .

However, the first device is applied to the electric vehicle 30 . Specifically, the shielding member 3 is formed so that the conductive layer includes or covers a region (shielding target region) facing the battery pack 34 across the high-voltage wiring 36 (electromagnetic wave generator 2) of the battery pack 34 (unit 1). (dotted line) is provided. Specifically, the shielding member 3 is interposed between the passenger compartment 33 and the high-voltage wiring 36 . Further, the conductive path included in the current return band 4 connects the two ends of the conductive layer included in the shield member 3 through the opposite side of the battery pack 34 to the shield member 3 so as to be in electrical communication. to form a circular circuit. Specifically, the conductive path included in the current feedback band 4 is arranged along the bottom surface (the surface on the negative side of the Z axis) of the battery pack 34, and the conductive layer included in the shielding member 3 and the battery pack 34 to form an annular circuit.

With the above configuration, the induced current (dotted line arrow) generated in the conductive layer included in the shielding member 3 by the electromagnetic wave radiated from the high-voltage wiring 36 is returned to the current return band 4 by the return current (solid line arrow) that flows in a ring. , the stray current generated in the conductive layer can be reduced. As a result, shielding performance against electromagnetic waves radiated from the high-voltage wiring 36 can be improved, secondary radiation of electromagnetic waves caused by stray magnetic fields can be reduced, and the influence of the electromagnetic waves on the passengers 31 and 32 can be reduced.

<<Second embodiment>>
An electromagnetic wave shielding device (hereinafter sometimes referred to as a "second device") according to a second embodiment of the present invention will be described below. As described above, in the first device, the conductive path is connected so as to electrically connect the two ends of the conductive layer via the side opposite to the conductive layer of the unit serving as the electromagnetic wave generating source. It forms a circular circuit. This reduces the radiation of electromagnetic waves to the upper side of the shielding member (secondary radiation from the current feedback band) caused by the feedback current flowing through the conductive path of the current feedback band. However, from the viewpoint of further reducing secondary radiation from current return bands, it is preferred that the device of the present invention comprise a plurality of current return bands.

<composition>
Therefore, the second device is the first device described above, which is an electromagnetic wave shielding device having a plurality of current return bands.

FIG. 4 is a schematic perspective view showing an example of the configuration of the second device. The battery pack as the unit 1 to which the second device 102 is applied has an inverted L-shaped high-voltage wiring as the electromagnetic wave generator 2 on its top surface (the surface on the positive side of the Z axis). However, since most of the high-voltage wiring (electromagnetic wave generator 2) is covered with the shielding member 3 including the conductive layer, only the front end of the high-voltage wiring (positive direction of the Y-axis) is shown in FIG. Drawn.

The second device 102 has five current feedback zones 4, and each of the conductive paths included in these five current feedback zones 4 passes through the bottom surface of the unit 1 (the surface on the negative direction side of the Z axis). are electrically connected to the two ends S1 and S2 of the conductive layer included in the shielding member 3 . That is, five loop circuits are formed in parallel by the conductive paths included in the five current return belts 4 and the conductive layers included in the shield member 3, and each of these five loop circuits is connected to the unit 1. surrounds the perimeter.

In addition, in the example shown in FIG. 4, the second device 102 further includes a branch member 9 which is a member made of a conductor. Each of the conductive paths included in the five current return bands 4 and the two ends S1 and S2 of the conductive layer included in the shielding member 3 are electrically connected via the branch member 9, respectively. That is, the branch member 9 is interposed between each of the plurality of conductive paths and the two ends of the conductive layer.

<effect>
In the second device, similarly to the first device described above, the induced current generated in the conductive layer by the electromagnetic wave emitted from the electromagnetic wave generating section can be passed as the looped feedback current through the conductive path of the current feedback band. can. Therefore, it is possible to reduce problems such as deterioration of shielding performance against electromagnetic waves and generation of secondary radiation of electromagnetic waves caused by stray currents, which are observed in the above-described conventional devices.

In addition, according to the second device, the induced current can be distributed to the conductive paths of the plurality of current feedback zones, so that the feedback current flowing through each current feedback zone can be made smaller. As a result, secondary radiation from the current feedback band can be reduced.

From the viewpoint of reducing the feedback current flowing through each current feedback band, it is preferable that the number of current feedback bands provided in the second device is as large as possible. Therefore, the second device preferably has three or more current return bands. On the other hand, from the viewpoint of facilitating the work of laying the current return belts to the unit, it is preferable that the number of current return belts is as small as possible. Therefore, it is preferable that the number of current feedback bands provided in the second device is 10 or less.

In addition, in the second device shown in FIG. 4, as described above, each of the conductive paths included in the five current return bands 4 and the two ends S1 and S2 of the conductive layer included in the shielding member 3 are electrically connected via the branch member 9 . However, the branch member is not an essential component of the second device, and each of the conductive paths included in the plurality of current return zones and the two ends of the conductive layer included in the shield member are directly connected without the branch member. may be physically connected.

<<Third embodiment>>
An electromagnetic wave shielding device (hereinafter sometimes referred to as "third device") according to a third embodiment of the present invention will be described below. As noted above, the second device reduces secondary radiation from the current return bands by distributing the induced currents over the conductive paths of the multiple current return bands, resulting in smaller return currents flowing through individual current return bands. configured to reduce However, for example, eddy currents are generated in the conductive paths included in the individual current return bands due to unintended magnetic fields (disturbance magnetic fields) radiated from other devices, etc., that exist around the unit to which the second device is applied. However, there is a risk that the flow of feedback current will be hindered.

<composition>
Thus, the third device is an electromagnetic shielding device, such as the first or second device described above, in which the individual current return bands include a plurality of conductive paths arranged in parallel with one another.

5A and 5B are schematic (a) plan view and (b) cross-sectional view showing an example of the configuration of the current feedback band provided in the third device. The current return band 4 illustrated in FIG. 5 has four conductive paths 4a covered with a base material 4b (for example, resin) whose surface is an insulator except for the connection portion (right end portion) with the conductive layer (not shown). It is composed by Each conductive path 4a is formed of a strip-shaped conductor.

<effect>
FIG. 6 is a schematic diagram for explaining the effect achieved by the third device. In FIG. 6, for the sake of convenience, the outline of the portion of the conductive path 4a embedded in the base material 4b is also drawn with a solid line.

FIG. 6(a) is a schematic diagram showing the effect of a disturbing magnetic field on the return current assumed when each current feedback band includes only one conductive path formed by a strip-shaped conductor. As shown in (a), an eddy current 8e is generated in the conductive path 4a by the disturbing magnetic field M, and the flow of the return current 8 is impeded.

On the other hand, (b) of FIG. 6 shows the return current due to the disturbing magnetic field assumed when each current feedback band includes four conductive paths formed by strip-shaped conductors as shown in FIG. It is a schematic diagram which shows an influence. As shown in (b), even if the current feedback band 4 is exposed to the disturbing magnetic field M, no eddy current 8e is generated in the conductive path 4a, and the influence on the flow of the feedback current 8 is reduced.

That is, according to the third device, even if the current feedback band 4 is exposed to the disturbing magnetic field M, the return current 8 can flow smoothly, so that the occurrence of stray current in the conductive layer included in the shielding member can be effectively reduced. can do. As a result, problems such as deterioration of shielding performance against electromagnetic waves emitted from the electromagnetic wave generator 2 caused by stray currents and generation of secondary radiation of electromagnetic waves corresponding to stray magnetic fields can be reduced more reliably.

In the examples shown in FIGS. 5 and 6, the conductive paths included in the individual current return bands of the third device are formed by strip-shaped conductors. However, the shape of the conductor forming the conductive path is not limited to a strip shape, and the conductive path may be formed by a linear (columnar) conductor, for example.

In addition, from the viewpoint of reducing the impedance of the current feedback band and facilitating the flow of the feedback current, it is preferable that the number of conductive paths included in each current feedback band included in the third device is as large as possible. Therefore, each current return band provided by the third device preferably includes four or more conductive paths. On the other hand, from the viewpoint of simplifying the manufacturing process of the current feedback band, the smaller the number of conductive paths included in each current feedback band, the better. Therefore, it is preferable that the number of conductive paths included in each current return band of the third device is 10 or less.

Furthermore, from the viewpoint of reducing impedance as a current return band and reducing eddy currents caused by disturbing magnetic fields, the ratio of the length L to the width W (in the case of a strip) or the diameter D (in the case of a line) of the conductive path is preferably 200 or more. In addition, from the viewpoint of improving the flexibility of the current return band and facilitating the installation work, the diameter D or thickness T of the conductive path is preferably 0.5 mm or less.

By the way, even in the third device including a plurality of conductive paths in which the individual current return bands are arranged in parallel as described above, both ends of each conductive path are separated from the conductive layer of the unit that is the source of electromagnetic waves. The two ends of the conductive layer are electrically connected to form a circular circuit via opposite sides. When the third device includes the branch member described above, each of the plurality of conductive paths included in the current return band and the two ends of the conductive layer included in the shield member are electrically connected via the branch member. be. This facilitates the connection work between (the conductive layer included in) the shielding member 3 and (the conductive path included in) the current return band 4 .

FIG. 7 is a schematic diagram showing an example of the configuration around the branching member in the third device provided with the branching member. The third device shown in this example comprises five current return strips 4, each current return strip 4 comprising four conductive paths 4a covered by a base material 4b. On the other hand, the branching member 9 is electrically connected to the end of the conductive layer 3a included in the shielding member, and the individual conductive paths 4a and the branching member 9 are electrically connected via the conductors 4c. .

<<Fourth embodiment>>
An electromagnetic wave shielding device (hereinafter sometimes referred to as a "fourth device") according to a fourth embodiment of the present invention will be described below. As described above, the shape and size of the conductive layer included in the shielding member are not particularly limited as long as at least part of the conductive layer can be arranged to include or cover the area to be shielded. For example, the conductive layer can have a tubular shape or the like into which the electromagnetic wave generator (for example, high-voltage wiring or the like) can be inserted.

<composition>
Therefore, the fourth device is a device of the present invention according to any one of the various embodiments including the above-described first to third devices, and is a tubular shape through which the electromagnetic wave generating section can be inserted. The electromagnetic wave shielding device has a conductive layer having a structure of

FIG. 8 is a schematic perspective view showing an example of the configuration of the fourth device. The battery pack as the unit 1 to which the fourth device 104 is applied has an inverted L-shaped high-voltage wiring as the electromagnetic wave generator 2 on its top surface (the surface on the positive side of the Z axis). However, since most of the high-voltage wiring (electromagnetic wave generator 2) is covered with the shielding member 3 including the conductive layer, only the front end of the high-voltage wiring (positive direction of the Y-axis) is shown in FIG. Drawn.

The conductive layer forming the shielding member 3 provided in the fourth device 104 has a tubular structure into which the high-voltage wiring (the electromagnetic wave generator 2) can be inserted. Typically, the shielding member 3 is composed of a metal tube. At least a part of the surface of the metal tube, excluding the connecting portion with the conductive path included in the current return band 4, may be covered with an insulator such as resin.

In the example shown in FIG. 8, since the surface of the battery pack (unit 1) is made of an insulator, the conductive path included in the current return band 4 is printed on the surface of the battery pack using conductive paint. It is composed of linear patterns. When the surface of the battery pack is made of a conductor, an insulating film (for example, a resin film, etc.) having a linear pattern printed on the surface using a conductive paint is applied to the surface of the battery pack or the outer surface of the battery box. It may be affixed to the inner surface or the like.

In addition, when the battery pack or battery box needs to be opened and closed for reasons such as maintenance of the battery pack, as shown in FIG. A connecting portion 4d (for example, an FPC connector or the like) may be provided. This facilitates opening and closing of the battery pack or battery box.

<effect>
As described above, the conductive layer included in the shielding member of the fourth device has a tubular structure into which the electromagnetic wave generator can be inserted. Therefore, almost the entire surface of the electromagnetic wave generator such as the high-voltage wiring can be covered with the conductive layer, so that the electromagnetic waves generated from the electromagnetic wave generator can be shielded more effectively.

Since the conductive layer forming the shielding member 3 provided in the fourth device 104 has a tubular structure, the connection configuration with the conductive path included in the current return band 4 is shown in FIGS. A connection configuration other than the conductive layer having a planar structure as shown may be employed. For example, as exemplified in FIG. 9, a plurality of conductive paths 4a included in the current return band 4 are arranged along the entire periphery of the end portion of the tubular conductive layer 3a that constitutes the shielding member 3. may be connected to the By adopting such a connection form, the induced current generated in the conductive layer 3a can smoothly flow into each of the conductive paths 4a and smoothly flow through the conductive paths 4a as a return current.

<<Fifth Embodiment>>
An electromagnetic wave shielding device (hereinafter sometimes referred to as a "fifth device") according to a fifth embodiment of the present invention will be described below.

As described above, in the devices of the present invention including the first device to the fourth device, the two ends of the conductive layer of the unit serving as the source of electromagnetic waves are electrically connected via the side opposite to the conductive layer. A conductive path is connected to form an annular circuit. As a result, the induced current generated in the conductive layer by the electromagnetic waves emitted from the electromagnetic wave generator can be passed through the conductive path as a feedback current that flows in a loop, thereby effectively reducing the stray current generated in the conductive layer. can be done. As a result, it is possible to improve shielding performance against electromagnetic waves radiated from the electromagnetic wave generator and to reduce secondary radiation of electromagnetic waves caused by stray magnetic fields.

However, when the frequency of the electromagnetic wave emitted from the electromagnetic wave generator is low, the induced current generated in the conductive layer is weak, and it may be difficult to sufficiently cancel the electromagnetic wave. In addition, even if the frequency of the electromagnetic wave emitted from the electromagnetic wave generator is high, the return current is difficult to flow due to impedance mismatch between the conductive layer and the conductive path, etc., so the stray current should be sufficiently reduced. As a result, the induced current generated in the conductive layer is weakened, and it may be difficult to sufficiently cancel the electromagnetic wave.

<composition>
Therefore, the fifth device is a device of the present invention according to any one of the various embodiments including the above-described first to fourth devices, and further includes a booster interposed in the conductive path. It is a shielding device. The booster is configured to amplify the induced current flowing through the conductive layer.

FIG. 10(a) is a schematic perspective view showing an example of the configuration of the fifth device, and FIG. 10(b) is a schematic front view showing an example of the arrangement of monitor wiring provided in the fifth device. The fifth device 105 has four current return bands 4 that pass through the bottom side of the unit 1 that is the source of electromagnetic waves. are in electrical communication by the included conductive paths.

Further, as shown in (b), a monitor wiring 14 for monitoring the magnetic field generated from the high-voltage wiring is disposed below the high-voltage wiring as the electromagnetic wave generator 2 (on the negative direction side of the Z-axis). ing. By keeping the monitor wiring 14 away from the conductive layer in this manner, the magnetic field generated from the high-voltage wiring can be accurately monitored even when the induced current flowing in the conductive layer 3a is amplified by the booster 13.

A monitor wiring current 17, which is an induced current in the monitor wiring 14 due to the magnetic field generated from the high-voltage wiring, flows through the current feedback arranged at the left end (the end on the negative direction side of the X axis) of the four current feedback bands 4. It is input to the current signal processor terminal 15 (see FIG. 11) provided in the booster 13 via the belt 4'. A booster 13 is interposed in the middle of the three current feedback bands 4 other than the current feedback band 4'. Induced current is amplified. A power source 16 is connected to the booster 13 for operating various devices (described later in detail) that constitute the booster 13 .

As described above, in the example shown in FIG. 10, the current generated in the monitor wiring 14 is input to the current signal processor terminal 15 of the booster 13 via the current feedback band 4'. However, the monitor wiring 14 may be connected to the current signal processor terminal 15 via a wiring provided separately from the current feedback band 4 without passing through the current feedback band 4'.

Next, the configuration and function of the booster 13 will be described below. FIG. 12 is a circuit diagram showing an example of the configuration of the booster 13. As shown in FIG. The booster 13 is composed of a current signal processor 13a, a canceling current waveform calculator 13b and an amplifier 13c, and is connected to a power source 16 for operating them.

The current signal processor 13a extracts a signal in the target frequency band from the monitor wiring current 17 input from the monitor wiring 14 via the current signal processor terminal 15, and outputs it as the current signal 18 to the cancellation current waveform calculator 13b. do. A canceling current waveform calculator 13b obtains a canceling current waveform signal 19 required to cancel the electromagnetic wave (magnetic field) radiated from the unit 1 based on the current signal 18, and outputs the canceling current waveform signal 19 to the amplifier 13c. Amplifier 13 c generates counter current 20 based on counter current waveform signal 19 and causes it to flow through conductive paths included in current feedback band 4 .

<effect>
As a result of the above, according to the fifth device, even when the induced current itself generated in the conductive layer by the electromagnetic waves radiated from the electromagnetic wave generator (high-voltage wiring) is weak as described above, by flowing the canceling current through the conductive path, The current flowing through the conductive layer can be increased, that is, according to the fifth device, the induced current flowing through the conductive layer can be amplified. Therefore, the electromagnetic waves radiated from the electromagnetic wave generator can be effectively shielded.

When a booster is interposed in each of the plurality of current feedback bands as in the fifth device 105 shown in FIG. may shield electromagnetic waves in a plurality of frequency bands.

By the way, the current signal flowing through the monitor wiring is generated by the electromagnetic induction phenomenon, and its strength is roughly proportional to the frequency. Different amplification factors need to be applied depending on the The algorithm executed in this case is described below.

FIG. 13(a) is a block diagram showing an example of the process of passing the current signal _I0 corresponding to the monitor wiring current through a band-pass filter to extract the current signal _I1 in the target frequency band, and (b) is a block diagram showing an example of the process. 4 is a graph illustrating waveforms of a current signal _I0 and a current signal _I1 ; As shown in (b), the current signal I ₀ (thin curve) corresponding to the monitor wiring current may contain unnecessary frequency components such as high frequencies caused by noise or the like. Therefore, the current signal _I0 is passed through a band-pass filter that selectively passes frequencies in a range corresponding to the frequencies of electromagnetic waves radiated from a target electromagnetic wave generator (for example, high-voltage wiring of a battery pack), and unwanted frequency components are detected. to remove As a result, the current signal I ₁ (thick curve) in the target frequency band can be extracted.

Next, by applying different amplification factors depending on the frequency to the current signal _I1 extracted as described above, a canceling current suitable for shielding the electromagnetic waves radiated from the electromagnetic wave generator is generated. FIG. 14 is a block diagram showing an example of arithmetic logic for calculating a suitable canceling current _I2 by applying different amplification factors to the current signal _I1 depending on the frequency. Such arithmetic logic can be realized, for example, by causing a CPU constituting an ECU provided in the booster to execute a program stored in a storage device such as a ROM.

First, in step S01, the current signal _I1 that has passed through the bandpass filter is converted into a frequency signal and a phase signal. Although FIG. 14 shows an example in which the current signal _I1 is converted into three frequency signals and three phase signals, the number of frequency signals and phase signals can be changed according to the purpose. Next, in step S02, an amplification factor corresponding to each frequency signal is specified based on the data indicating the correspondence between the frequency and the amplification factor (gain), and is output as an amplification factor signal. The data indicating the correspondence relationship between the frequency and the amplification factor (gain) is stored in advance in a storage device such as a ROM constituting an ECU provided in the booster in the form of a map or table, for example, and stored in the CPU. can be referenced.

Furthermore, in step S03, the final waveform of the cancellation current _I2 is calculated based on the frequency signal, phase signal, amplification factor signal, and distance correction coefficient K described above. In this way, it is possible to increase the current flowing through the conductive layer and obtain a canceling current more suitable for effectively shielding the electromagnetic waves radiated from the electromagnetic wave generating section.

Although several embodiments having specific configurations have been described, at times with reference to the accompanying drawings, for the purpose of illustrating the present invention, the scope of the present invention is not limited to these exemplary embodiments. It should not be construed as limiting, and it goes without saying that modifications can be made as appropriate within the scope of the claims and the matters described in the specification.

DESCRIPTION OF SYMBOLS 1... Unit (battery pack), 2... Electromagnetic wave generator (high-voltage wiring), 3... Shielding member, 3a... Conductive layer, 4 and 4'... Current return band, 4a... Conductive path, 4b... Base material (insulator) , 4c... conductor, 4d... connection part, 5... high-voltage wiring current, 6... induced current, 7... stray current, 8... return current, 8e... eddy current, 9... branch member, 13... booster, 13a... current signal processing Device 13b Canceling current waveform calculator 13c Amplifier 14 Monitor wiring 15 Current signal processor terminal 16 Power supply 17 Monitor wiring current 18 Current signal 19 Canceling current waveform signal 20 101, 102, 104, and 105 . . electromagnetic wave shielding device (present invention), K .. distance correction coefficient, M .. disturbing magnetic field, S1 and S2 .

Claims (3)

An electromagnetic wave shielding device that blocks electromagnetic waves radiated from a unit serving as a source of electromagnetic waves by a shielding member including a conductive layer,
further comprising a plurality of current return zones including conductive paths formed by linear or strip-shaped conductors;
The conductive layer is disposed in at least a shielding target region, which is a region facing the unit with an electromagnetic wave generating portion, which is a portion of the unit that generates the electromagnetic wave, interposed therebetween,
The conductive path is a ring-shaped circuit formed by connecting two ends of the conductive layer via a side opposite to the conductive layer of the unit in a region other than the shielding target region so as to electrically connect the two ends of the conductive layer. forming a
Electromagnetic shielding device. The electromagnetic wave shielding device according to claim 1,
each said current return band comprising a plurality of said conductive paths arranged in parallel with each other;
Electromagnetic shielding device. The electromagnetic wave shielding device according to claim 2,
The aspect ratio, which is the ratio of the length to the width or diameter of the conductive path, is 200 or more.
Electromagnetic shielding device.

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