JP5927441B2 - Ferrite clamp - Google Patents

Description

  The present invention relates to a ferrite clamp that is externally fitted to an electric wire and absorbs a noise current flowing through the electric wire.

  Conventionally, as this type of ferrite clamp, a pair of split cores that are formed in an open ring shape and form an annular magnetic core having an insertion hole for inserting an electric wire when they are combined with each other, Proposed is provided with a holding case having a pair of case portions to be held, and a fixing mechanism for annularly combining the divided cores held by the case portions by fixing the case portions to each other Has been. In the ferrite clamp configured as described above, the magnetic core is externally fitted to the electric wire, and the magnetic core is held in an annular shape by the holding case, so that the noise current flowing through the electric wire can be absorbed.

  In the past, this type of ferrite clamp has often been used for electric wires that are energized with a current of less than 10 A, such as signal lines for personal computers. However, in recent years, applications of this type of ferrite clamp, such as application to electric vehicles, tend to be widened, and the possibility of being used for electric wires such as bus bars that are energized with a large current of 10 A or more has increased. When a large current is passed through the electric wire inserted into the magnetic core, magnetic saturation may occur in the magnetic core, and the effect of absorbing noise current may be reduced.

  Here, although the field of the toroidal coil is slightly different from the field of the present invention, as a measure for suppressing magnetic saturation of the magnetic core, a gap is provided in a part of the magnetic path constituted by the magnetic core, and the gap It has been proposed to insert a spacer member having a magnetic permeability smaller than that of the magnetic core (for example, see Patent Document 1).

JP 2002-37381 A

  Here, when the concept of Patent Document 1 is applied to a conventional ferrite clamp, a sheet having a magnetic permeability smaller than the magnetic permeability of each divided core is sandwiched between the butted surfaces of the pair of divided cores. In this case, the following problems arise. In an electric vehicle or the like, not only a large current is applied as described above, but also the vibration applied to the ferrite clamp is large. Furthermore, since space is limited in an electric vehicle or the like, three-dimensional wiring is made, and ferrite clamps are arranged in various directions. Then, the sheet | seat pinched | interposed between a pair of division | segmentation cores may slide down to the exterior of a holding | maintenance case, and the characteristic of a ferrite clamp may change.

  It may be possible to stick the sheet to the abutting surface of the split core using an adhesive, but the interior of an electric vehicle or the like may become hot, and the adhesive strength of the adhesive will decrease and the sheet as described above May not be able to be well controlled. Therefore, the present invention stably holds a sheet having a magnetic permeability smaller than the magnetic permeability of the pair of split cores between the butted surfaces of the pair of split cores so that the occurrence of magnetic saturation is good and stable. It was made for the purpose of providing a ferrite clamp that can be suppressed.

  The present invention, which has been made to achieve the above object, includes a pair of split cores that are formed in an open ring shape and form an annular magnetic core having an insertion hole for inserting an electric wire when combined with each other, and each of the split cores A holding case having a pair of case portions for holding each of them, and a fixing mechanism for annularly combining the divided cores held by the case portions by fixing the case portions, A ferrite clamp that externally fits a magnetic core to an electric wire and absorbs noise current flowing through the electric wire has a magnetic permeability smaller than the magnetic permeability of each of the divided cores and is sandwiched between the butted surfaces of the pair of divided cores A sheet is further provided, and the case portion of at least one of the holding cases is further protruded from the same plane as the abutting surface of the split core held by the case portion. The sheet sandwiched between the abutting surface and the abutting surface of the other split core is formed by extending in the surface direction of the mating surface, and both ends of the magnetic core in the axial direction of the electric wire and The gist of the ferrite clamp is characterized by surrounding the magnetic core from the outer peripheral direction.

  In the ferrite clamp of the present invention configured as described above, a sheet having a magnetic permeability smaller than the magnetic permeability of the pair of split cores fitted on the electric wire is sandwiched between the butted surfaces of the pair of split cores. For this reason, it is possible to satisfactorily suppress the occurrence of magnetic saturation in the annular magnetic core formed by combining the pair of split cores.

  In addition, at least one of the pair of case parts constituting the holding case by holding each of the split cores is further provided on the abutting face from the same plane as the abutting face of the split core held by the case part. It is formed extending in the surface direction. With this configuration, the case portion includes the sheet sandwiched between the abutting surface and the abutting surface of the other divided core, and both ends of the magnetic core in the axial direction of the electric wire and the outer peripheral direction of the magnetic core. That is, the magnetic core is surrounded from the outer side when the magnetic core is externally fitted to the electric wire. For this reason, in this invention, it can suppress favorably that the sheet | seat pinched | interposed between said pair of division | segmentation cores slides down to the exterior of a holding case. Therefore, the sheet is stably held between the abutting surfaces, and it is possible to satisfactorily and stably suppress the occurrence of magnetic saturation in the magnetic core.

  In addition, the ferrite clamp of the present invention may further include a cylindrical member that is fitted into the insertion hole to suppress the movement of the sheet toward the insertion hole and that is externally fitted to the electric wire. In this case, since the cylindrical member fitted in the insertion hole of the magnetic core suppresses the movement of the sheet toward the insertion hole, the sheet can be further suppressed from sliding off the holding case. Can do. That is, as a measure for suppressing the sheet from sliding down through the insertion hole, it is possible to suppress the sheet by the outer periphery of the electric wire inserted through the insertion hole, but in this way, the sheet is suppressed by the cylindrical member. In this case, it is possible to satisfactorily prevent the sheet from sliding down regardless of the diameter of the electric wire.

  And in that case, you may further provide the rib formed in the outer periphery of the said cylindrical member, and press-contacting to the inner wall face of the said insertion hole, elastically deforming at the time of the fitting to the said insertion hole of the said cylindrical member. . In that case, when the rib presses the inner wall surface of the insertion hole in each divided core, the positional relationship of the butted surfaces of each divided core is accurately maintained. For this reason, the characteristics of the ferrite clamp can be further stabilized.

  Moreover, the said electric wire is a bus bar, Comprising: The cross-sectional shape perpendicular | vertical to the said axial direction of the internal peripheral surface of the said cylindrical member may correspond with the cross-sectional shape perpendicular | vertical to the said axial direction of the outer peripheral surface of the said bus bar. In many cases, the bus bar is energized with a large current of 10 A or more, and the effects of the present invention appear more remarkably. In this case, the inner peripheral surface of the cylindrical member and the outer peripheral surface of the bus bar come into contact with each other, so that the ferrite clamp can be positioned more satisfactorily.

A bottom view (A), a right side view (B), a front view (C), a left side view (D), a rear view (E), and a plan view showing a configuration in a closed state of a ferrite clamp to which the present invention is applied. (F), upper left front perspective view (G), upper right front perspective view (H), lower left front perspective view (I), lower right front perspective view (J). A bottom view (A), a right side view (B), a front view (C), a left side view (D), a rear view (E), a plan view (F), and an upper left view showing the configuration of the ferrite clamp in an opened state They are a front perspective view (G), an upper right front perspective view (H), a lower left front perspective view (I), and a lower right front perspective view (J). It is the sectional view on the AA line of FIG. They are a front view (A), a bottom view (B), a right side view (C), a left side view (D), and a perspective view (E) showing the configuration of the divided bobbin of the ferrite clamp. It is a graph showing the relationship between the core gap of the said ferrite clamp, and an inductance DC superimposition characteristic. A bottom view (A), a front view (B), a right side view (C), a left side view (D), a rear view (E), showing a configuration in the open state of another ferrite clamp to which the present invention is applied, They are a top view (F), an upper left front perspective view (G), an upper right front perspective view (H), a lower left front perspective view (I), and a lower right front perspective view (J). They are a bottom view (A), a front view (B), a left side view (C), and a perspective view (D) showing the configuration of the divided bobbin of the ferrite clamp.

[Configuration of ferrite clamp]
Embodiments of the present invention will be described below with reference to the drawings. 1A and 1B are diagrams illustrating a configuration of a ferrite clamp 1 to which the present invention is applied in a closed state, in which FIG. 1A is a bottom view, FIG. 1B is a right side view, FIG. 1C is a front view, and FIG. Is a left side view, (E) is a rear view, (F) is a plan view, (G) is an upper left front perspective view, (H) is an upper right front perspective view, (I) is a lower left front perspective view, and (J) is It is a lower right front perspective view. 2 is a diagram showing the configuration of the ferrite clamp 1 in an open state, in which (A) is a bottom view, (B) is a right side view, (C) is a front view, (D) is a left side view, (E) is a rear view, (F) is a plan view, (G) is an upper left front perspective view, (H) is an upper right front perspective view, (I) is a lower left front perspective view, and (J) is a lower right front perspective view. It is. FIG. 3 is a cross-sectional view taken along line AA in FIG. The ferrite clamp 1 of the present embodiment includes a main body 2 having split cores 4A and 4B, which will be described later, and a bobbin 3 as an example of a tubular member that is externally fitted to a strip-shaped bus bar (not shown). Yes. Although the configuration of the bobbin 3 will be described in detail later, as shown in FIG. 2 (G) and the like, the bobbin 3 is used in combination with a rectangular tube having an elongated cross section.

  First, the configuration of the main body 2 will be described. As shown in FIGS. 1 to 3, the main body 2 of the present embodiment includes a magnetic core (for example, a ferrite core) formed in a rectangular tube shape surrounding the bobbin 3 from the outer periphery, and each rectangular cross section of the rectangular tube. A pair of split cores 4A and 4B having a shape divided into two on the plane passing through the center of the short side, the split cores 4A and 4B are held together, and the split cores 4A and 4B are combined in the original rectangular tube shape And a holding case 6 that can be closed together.

  Of these, the holding case 6 has a pair of case portions 6A and 6B that house (hold) the split cores 4A and 4B (FIG. 3) and are connected to each other via a hinge 8 so as to be opened and closed. As shown in FIG. 2, one case portion 6A has a hook-like engagement with the side wall surface of the case portion 6A facing the side wall surface on which the hinge 8 is formed, with the storage space for the split core 4A interposed therebetween. A claw 10 is provided, and the other case portion 6B is engaged with the locking claw 10 on the side wall of the case portion 6B opposite to the side wall on which the hinge 8 is formed, with the storage space of the split core 4B being sandwiched between them. A rectangular frame-like locking frame 12 is provided to hold the case portions 6A and 6B in a closed state. The locking frame 12 is formed so as to protrude from the opening side edge of the case portion 6B, and two locking frames 12 are provided along the central axis direction of the square tube. Two locking claws 10 are provided at positions on the side wall surface of the case portion 6 </ b> A to engage with the respective locking frames 12. The locking claw 10 and the locking frame 12 correspond to a fixing mechanism.

  Further, on the outer peripheral wall constituting the bottom surfaces of the case portions 6A and 6B, tongue-like urging claws 14 whose tip portions protrude toward the storage spaces of the split cores 4A and 4B are provided at the center and four corners of the bottom surfaces. Are formed at four locations respectively. Further, as shown in FIG. 3, the inner surface of the outer peripheral wall constituting both side surfaces (the surface along the central axis direction) of the case portion 6A is engaged with the engaging grooves 42 formed on the outer peripheral surface of the split core 4A. In addition, presser claws 16 are formed to prevent the split core 4A stored in the storage space of the case portion 6A from falling off the case portion 6A.

  Further, as shown in FIG. 2, rectangular cutout portions 20 that are fitted onto the bobbin 3 are formed on the side walls that form both end surfaces of the case portion 6 </ b> A (surfaces positioned at both ends in the central axis direction). ing. Similarly, the presser claw 17 and the notch 21 are also formed in the case portion 6B.

  A pair of fixing portions 25 and 26 projecting in a plate shape along the bottom surface and the central axis are provided at diagonal positions across the center of the bottom surface from the outer peripheral wall constituting the bottom surface of the case portion 6B. Yes. The fixing portions 25 and 26 are provided with rivet holes 25A and 26A penetrating in a direction perpendicular to the bottom surface. Further, in the case portion 6A, when the ferrite clamp 1 is closed, a fixing portion 27 is interposed via a foot 27B at a position overlapping with the fixing portion 25 on the side farther from the hinge 8 among the fixing portions 25 and 26 described above. It is connected. The fixing portion 27 is also provided with a rivet hole 27A similar to the fixing portions 25 and 26. For this reason, by inserting a rivet (not shown) into the rivet holes 27A and 25A and the rivet hole 26A superimposed by closing the ferrite clamp 1, the ferrite clamp 1 is fixed to a support such as a substrate or a sheet metal. Can do. The holding case 6 configured in this manner is integrally formed of synthetic resin, and appropriate elasticity is given to the urging claws 14 and the like.

  The bobbin 3 has an outer periphery slightly smaller than a hole (insertion hole) formed when the divided cores 4A and 4B are combined, and a pair of shapes having a shape divided into two by a plane passing through the center of each long side of the rectangular cross section. It consists of divided bobbins 3A and 3B. 4A and 4B are diagrams illustrating the configuration of one of the divided bobbins 3A. FIG. 4A is a front view, FIG. 4B is a bottom view, FIG. 4C is a right side view, FIG. 4D is a left side view, and FIG. It is a perspective view. The other divided bobbin 3B is configured in exactly the same manner as the divided bobbin 3A.

  As shown in FIG. 4, the divided bobbin 3 </ b> A is made of a synthetic resin as a U-shaped column having a U-shaped section obtained by dividing a rectangular tube having a long and narrow section at the center of the long side of the rectangle. In addition, ribs 31 extending in a direction perpendicular to the central axis direction are provided at equal intervals in three rows on the outer periphery of the short side of the rectangle. The outer periphery of the bobbin 3 including the rib 31 is larger than the hole. When the bobbin 3 combined with the divided bobbins 3A and 3B is mounted in the hole, the rib 31 is elastically deformed and crushed. Installed.

  Further, flanges 32 having outer peripheries larger than the holes are formed at both ends of the rib 31 in the central axis direction. When the bobbin 3 is installed in the hole, the flange 32 is disposed outside the notches 20 and 21 of the case portions 6A and 6B, as shown in FIG. By engaging 21, the bobbin 3 is prevented from falling off between the split cores 4 </ b> A and 4 </ b> B. Furthermore, when the divided bobbins 3A and 3B are combined to form the bobbin 3, a hole having a rectangular cross section is formed at the center. The hole is a bus bar (an example of an electric wire) to which the divided cores 4A and 4B are to be fitted. ) And the cross-sectional shape match.

  Further, in the ferrite clamp 1, a pair of sheets 50 made of PET are sandwiched between the butted surfaces of the split cores 4A and 4B, but the opening side edge of the case portion 6B is as shown in FIG. Further, the split core 4B is held in the case portion 6B and is disposed on the same plane as the surface of the sheet 50 disposed on the surface thereof. In FIG. 3, the split core 4 </ b> A protrudes from the opening side edge of the case portion 6 </ b> A, but this protrusion amount corresponds to the deformation amount of the urging claw 14. That is, when the ferrite clamp 1 is closed and the locking claw 10 and the locking frame 12 are engaged, the split cores 4A and 4B are pressed against each other with the sheet 50 interposed therebetween, and the biasing claw 14 is deformed at that time. The opening side edge of the case portion 6A and the opening side edge of the case portion 6B come into contact with each other.

[Effect of ferrite clamp]
The ferrite clamp 1 configured as described above is used as follows. First, the divided bobbins 3A and 3B are mounted from both sides of the bus bar in the width direction (the direction in which the short sides of the rectangular cross section face each other), thereby surrounding the bus bar with the bobbin 3 from the outer periphery. Subsequently, as shown in FIG. 3, the bobbin 3 is mounted while the rib 31 is elastically deformed and crushed in the concave portion of the split core 4 </ b> B held by the case portion 6 </ b> B. Subsequently, after placing the sheet 50 on the abutting surface of the split core 4B, the case portions 6A and 6B are closed from the thickness direction of the bus bar (the direction in which the long sides of the rectangular cross section face each other) with the hinge 8 as the center. . When the case portions 6A and 6B are closed until the locking claw 10 and the locking frame 12 are engaged (FIG. 1), the split cores 4A and 4B sandwich the sheet 50 by the urging force of the urging claw 14. It is press-contacted with. As a result, the split cores 4A and 4B can be combined in an annular shape fitted around the bus bar, and the noise current passing through the bus bar can be absorbed.

  Further, as described above, the opening side edge of the case portion 6B is formed so as to extend further in the surface direction of the abutting surface than the abutting surface of the split core 4B held by the case portion 6B. The sheet 50 is disposed on the same plane as the surface of the sheet 50. And by this structure, the case part 6B surrounds the sheet | seat 50 pinched | interposed into the abutting surface of a pair of division | segmentation core 4A, 4B from the axial direction both ends and width direction of a bus bar. For this reason, in the ferrite clamp 1, it can suppress satisfactorily that the sheet | seat 50 pinched | interposed between the split cores 4A and 4B slides down outside the holding case 6. In addition, in the present embodiment, since the bobbin 3 is inserted into a hole formed when the split cores 4A and 4B are combined, it is possible to suppress the sheet 50 from slipping out of the holding case 6 through the hole. it can.

  FIG. 5 is a graph showing the relationship between the gap (gap) between the split cores 4A and 4B of the ferrite clamp 1 and the inductance DC superposition characteristics. As shown in FIG. 5, when there is no gap, when a large current of 10A or more (in FIG. 5, the horizontal axis is an ampere turn, the same applies to general amperes) flows through the bus bar, magnetic saturation occurs and the inductance is increased. Decrease significantly. On the other hand, when the gap is 0.1 mm or more, the occurrence of magnetic saturation is suppressed, and the inductance is stable even when a large current of 10 A or more flows through the bus bar. In this embodiment, since the sheet | seat 50 which has a magnetic permeability smaller than the division | segmentation cores 4A and 4B is pinched | interposed between division | segmentation cores 4A and 4B, generation | occurrence | production of magnetic saturation can be suppressed favorably. In addition, in the present embodiment, since the sheet 50 can be satisfactorily suppressed from sliding off the holding case 6 as described above, magnetic saturation is generated in the magnetic core composed of the split cores 4A and 4B. It can be suppressed well and stably.

  For this reason, as in the field of electric vehicles and the like, not only a large current is passed but also the vibration applied to the ferrite clamp 1 is large, and further, three-dimensional wiring is made and the ferrite clamp 1 is arranged in various directions. However, it is possible to stably hold the sheet 50 between the split cores 4A and 4B and stably suppress the occurrence of magnetic saturation. Further, if the surface of the sheet 50 is rough, the frictional force acting between the split cores 4A and 4B is large, and the sheet 50 slips down even if the sheet 50 is simply sandwiched between the split cores 4A and 4B. However, if the surface of the sheet 50 is rough, the gap becomes unstable. On the other hand, in this embodiment, since the slip-down is suppressed by the case portion 6B and the bobbin 3 as described above, even if the surface of the seat 50 is smooth, the slip-down can be stably suppressed. The gap can also be maintained at a stable value. Therefore, in this embodiment, the characteristics of the ferrite clamp 1 can be stabilized very well.

[Other Embodiments of the Present Invention]
In addition, this invention is not limited to the said embodiment at all, It can implement with a various form in the range which does not deviate from the summary of this invention. For example, the rib 31 may be omitted, and the bobbin 3 may be held between the split cores 4A and 4B only by the flange portion 32. However, when the rib 31 is provided as described above, the positional relationship between the butted surfaces of the divided cores 4A and 4B is accurately maintained by pressing the ribs 31 that are elastically deformed on the inner wall surfaces of the divided cores 4A and 4B. Is done. For this reason, the characteristics of the ferrite clamp 1 can be further stabilized.

  Needless to say, the present invention is not limited to the ferrite clamp 1 for bus bars having a rectangular cross section, but also applicable to ferrite clamps for bus bars having a circular cross section and ferrite clamps for general electric wires. 6A and 6B are diagrams illustrating a configuration in a state where the ferrite clamp 101 for a bus bar having a circular cross section is in an open state, where FIG. 6A is a bottom view, FIG. 6B is a front view, FIG. 6C is a right side view, and FIG. (E) is a rear view, (F) is a plan view, (G) is an upper left front perspective view, (H) is an upper right front perspective view, (I) is a lower left front perspective view, and (J) is a right view. It is a lower front perspective view. 7A and 7B are diagrams showing the configuration of the bobbin 103 of the ferrite clamp 101, where FIG. 7A is a bottom view, FIG. 7B is a front view, FIG. 7C is a left side view, and FIG. .

  The ferrite clamp 101 has the same configuration as that of the ferrite clamp 1 except for the shape. Therefore, corresponding parts are denoted by reference numerals obtained by adding 100 to the reference numerals used in FIGS. Therefore, detailed description of the configuration is omitted. That is, in the ferrite clamp 101 of the present embodiment, the bobbin 103 is formed in a cylindrical shape, and the divided cores 104A and 104B also have a shape obtained by dividing the cylindrical magnetic core into two on a plane passing through the axis of the cylinder. In the present embodiment, the bobbin 103 does not have a rib, and the bobbin 103 is held between the split cores 104A and 104B only by the flange 132. However, the rib may be provided in the same manner as the ferrite clamp 1. . In the present embodiment, since the bobbin 103 is cylindrical, the abutting surfaces of the divided bobbins 103A and 103B and the abutting surfaces of the divided cores 104A and 104B are arranged in parallel. The butted surfaces of the divided bobbins 103A and 103B and the butted surfaces of the divided cores 104A and 104B may be orthogonal to each other around the bus bar axis.

  In the ferrite clamp 101 of the present embodiment configured as described above, the divided bobbins 103A and 103B and the divided cores 104A and 104B are externally fitted to a bus bar having a circular cross section, a general electric wire having a circular cross section, or a bundle of loose wires, The magnetic current can be suppressed by absorbing the noise current and the gap formed by the sheet 150.

  Note that the cross-sectional shape of the inner peripheral surface of the bobbins 3 and 103 does not necessarily match the cross-sectional shape of the outer peripheral surface of the bus bar, but if they match, the ferrite clamps 1 and 101 should be positioned better. Can do. In the above embodiments, the sheet 50 or 150 may be provided only on one of the two butted surfaces of the split cores 4A and 4B or 104A and 104B.

DESCRIPTION OF SYMBOLS 1,101 ... Ferrite clamp 2,102 ... Main body 3,103 ... Bobbin 3A, 3B, 103A, 103B ... Divided bobbin 4A, 4B, 104A, 104B ... Divided core 6,106 ... Holding case 6A, 6B, 106A, 106B ... Case part 8, 108 ... Hinge 10, 110 ... Locking claw 12, 112 ... Locking frame 14, 114 ... Energizing claw 31 ... Rib 32, 132 ... Gutter 50, 150 ... Sheet

Claims (2)

A pair of split cores that are formed in an open ring shape and form an annular magnetic core having an insertion hole for inserting an electric wire when combined with each other;
A pair of case parts each holding the respective divided cores, and a holding case provided with a fixing mechanism for annularly combining the divided cores held in the respective case parts by fixing the respective case parts;
In a ferrite clamp that externally fits the magnetic core to an electric wire and absorbs a noise current flowing through the electric wire,
The has a smaller magnetic permeability than the magnetic permeability of the core segments, and the sheet sandwiched between the abutting surfaces of the pair of divided cores,
A cylindrical member that is fitted in the insertion hole and suppresses movement of the sheet to the insertion hole side, and is externally fitted to the electric wire;
A rib formed on the outer periphery of the cylindrical member, and pressed against the inner wall surface of the insertion hole while elastically deforming when the cylindrical member is fitted into the insertion hole;
Further comprising a,
The case part of at least one of the holding cases is formed so as to extend further from the same plane as the abutting surface of the split core held by the case part in the surface direction of the abutting surface. A ferrite characterized in that the sheet sandwiched between a surface and the butting surface of the other split core is surrounded from both ends of the magnetic core in the axial direction of the electric wire and from the outer peripheral direction of the magnetic core. Clamp. A pair of split cores that are formed in an open ring and form an annular magnetic core having an insertion hole for inserting the bus bar when combined with each other;
A pair of case parts each holding the respective divided cores, and a holding case provided with a fixing mechanism for annularly combining the divided cores held in the respective case parts by fixing the respective case parts;
In a ferrite clamp that externally fits the magnetic core to a bus bar and absorbs noise current flowing through the bus bar ,
The has a smaller magnetic permeability than the magnetic permeability of the core segments, and the sheet sandwiched between the abutting surfaces of the pair of divided cores,
A cylindrical member that is fitted in the insertion hole and suppresses movement of the sheet to the insertion hole side, and is fitted over the bus bar;
Further comprising a,
The case part of at least one of the holding cases is formed so as to extend further from the same plane as the abutting surface of the split core held by the case part in the surface direction of the abutting surface. The sheet sandwiched between the surface and the butted surface of the other split core, the axial end of the bus bar of the magnetic core and the outer peripheral direction of the magnetic core ,
The ferrite clamp characterized in that a cross-sectional shape perpendicular to the axial direction of the inner peripheral surface of the cylindrical member coincides with a cross-sectional shape perpendicular to the axial direction of the outer peripheral surface of the bus bar .

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