JP2018036111A - Current measurement device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique with which it is possible to downsize a current measurement device and simplify an assembly process.SOLUTION: This current measurement device comprises: a busbar 2 elongated in one direction (extension direction); a substrate 3 extending in parallel to the busbar 2 at a position distant from the busbar 2; a magnetoelectric transducer 4 fixed to the surface 3a of the substrate 3 and parallel to the surface 3a, for detecting a magnetic field in a direction (orthogonal direction) orthogonal to the extension direction of the busbar 2; and a tabular shield member 5 arranged in parallel to the substrate 3. The tabular shield member 5 includes a pair of lateral shield parts 52a, 52b located on both sides of the magnetoelectric transducer in the orthogonal direction, and a connection part for connecting the pair of lateral shield parts together at a position that does not overlap the magnetoelectric transducer in the extension direction. In a plan view of the substrate 3, the busbar 2 is located in space between the pair of lateral shield parts 52a, 52b, and the magnetoelectric transducer 4 is accommodated within the thickness T1 of the shield member 5.SELECTED DRAWING: Figure 2

Description

  The present specification discloses a current measuring device that measures a current flowing through a conductive member.

  When a current flows through a conductive member that extends long in one direction, a magnetic field is generated around the conductive member. By measuring the strength of the magnetic field, the strength of the current flowing through the conductive member can be known. Patent Documents 1 and 2 disclose techniques for measuring a current by arranging a magnetoelectric conversion element in the vicinity of a conductive member.

  In the above current measurement technique, only the magnetic field caused by the current flowing in the conductive member is detected by the magnetoelectric transducer, and other magnetic fields (magnetic fields that cause noise in the measurement result), for example, other conductive members located in the vicinity are detected. It is necessary not to detect a magnetic field caused by a flowing current or a magnetic field caused by a magnetic field generator such as a reactor arranged in the vicinity. In the techniques of Patent Documents 1 and 2, a member (shield member) that shields a magnetic field that becomes noise is disposed so as to surround the magnetic field generated around the conductive member. That is, when observed from the longitudinal direction of the conductive member, the shield member surrounds the conductive member and the magnetoelectric conversion element.

Japanese Patent Laid-Open No. 2006-6399 JP-A-2015-79012

  The conventional shield member extends in a certain distance along the extending direction of the conductive member, and has a shape that makes a round around the conductive member, and has a three-dimensional shape. When this shield member is used, the outer shape of the current measuring device is increased. In practice, a plurality of conductive members often extend in parallel. If it is going to arrange | position the conventional shield member to each electrically-conductive member, it is necessary to make the space | interval between adjacent electrically-conductive members wide, and to prevent the shield members with respect to each electrically-conductive member from interfering.

  In the technique described in this specification, the shield member is flattened. If flattened, the current measuring device can be miniaturized and the assembly process can be simplified. When the plurality of conductive members extend in parallel, the interval between adjacent conductive members can be reduced.

  In the technique described in this specification, a magnetoelectric conversion element having a limited magnetosensitive direction is used to flatten the shield member. That is, a magnetoelectric transducer is used that senses a magnetic field in a specific direction (magnetic direction) but does not sense a magnetic field in a direction orthogonal thereto. In the present technology, the magnetoelectric conversion element is mounted on a substrate. At that time, the magnetoelectric conversion element is mounted in a posture in which the magnetosensitive direction is parallel to the surface of the substrate. Furthermore, a pair of side shielding portions are arranged on both sides of the magnetoelectric conversion element in the magnetic sensitive direction. The conductive member is positioned within the space between the pair of side shields when the substrate is viewed in plan. In addition, the magnetoelectric conversion element is accommodated in the thickness of the side shielding portion. In such a relationship, the magnetic field caused by the current flowing through the conductive member extends the position of the magnetoelectric conversion element in the direction of magnetic sensing, and a magnetic field that needs to be measured by the magnetoelectric conversion element can be measured. On the other hand, with respect to the magnetic field that the magnetoelectric transducer does not want to measure (the magnetic field other than the magnetic sensitive direction is not magnetic sensitive, the noise magnetic field is limited to the magnetic sensitive magnetic field) Since it is shielded by the side shield part, a relationship that is not measured by the magnetoelectric conversion element can be obtained.

  The current measuring device described in this specification includes a conductive member extending long in one direction (which direction is referred to as an extending direction), a substrate extending in parallel with the conductive member at a position spaced from the conductive member, A magneto-electric transducer that is fixed to the surface side of the conductive member and that is parallel to the surface and detects a magnetic field in a direction orthogonal to the extending direction of the conductive member (the direction is referred to as an orthogonal direction); A flat shield member is provided. The flat shield member connects the pair of side shielding portions located on both sides of the magnetoelectric conversion element in the orthogonal direction and the pair of side shielding portions in a position not overlapping with the magnetoelectric conversion element in the extending direction. It has a connecting part. When the substrate is viewed in plan, the conductive member is located within the interval between the pair of side shield portions, and the magnetosensitive surface of the magnetoelectric conversion element is accommodated in the thickness of the shield member. The magnetosensitive surface is a surface on the magnetoelectric transducer that is orthogonal to the magnetosensitive direction. The magnetoelectric transducer senses a magnetic field that passes through the magnetosensitive surface.

  With the above configuration, (1) the magnetic field caused by the current flowing through the conductive member for which the current is to be measured measures the current flowing through the conductive member in order to extend the position of the magnetoelectric conversion element in the direction of magnetic sensing. (2) Of the other magnetic fields (magnetic fields that cause noise), the magnetic field that faces the magnetosensitive direction is shielded by the pair of side shields, and thus does not reach the magnetoelectric conversion element. (3) Since no shielding member is arranged in the vertical direction, the magnetic field that becomes noise may pass through the magnetoelectric transducer, but the magnetic field that is not directed in the magnetic sensitive direction can detect the magnetic field that becomes noise. Absent. Necessary functions can be realized by a single flat shield member.

  In the technique described in this specification, the idea of shielding the magnetic field generated around the conductive member from the surroundings is abandoned, and the necessary magnetic field is moved to the magnetosensitive direction by the shielding member disposed around the magnetoelectric conversion element. The unnecessary magnetic field does not pass through the magnetoelectric conversion element in the magnetic sensitive direction (the unnecessary magnetic field in the magnetic sensitive direction (noise magnetic field) does not reach the magnetoelectric conversion element and passes through the magnetoelectric conversion element). Adopting a technology that the required magnetic field does not face the direction of magnetic sensing). Thereby, the shield member can be flattened. If it has the above-mentioned composition, a flat shield member can be fixed to a substrate, and the assembly process of an apparatus will be simplified. Further, it is possible to cope with a case where a plurality of conductive members extend in parallel with a narrow interval. Details and further improvements of the technology disclosed in this specification will be described in the following “DETAILED DESCRIPTION”.

It is a top view of the current measuring device of the 1st example. It is sectional drawing in the II-II line of FIG. It is a top view of the shield member of the 1st example. It is a top view of the shield member of the 2nd example. It is sectional drawing of the current measuring device of 3rd Example. It is sectional drawing in the VI-VI line of FIG. It is sectional drawing of the current measuring device of 4th Example. It is sectional drawing of the electric current measurement apparatus of 5th Example. It is sectional drawing of the current measuring device of 6th Example. It is a top view of the shield member of the 6th example. It is a top view of the shield member of the 7th example. It is a top view of the shield member of the 8th example.

(First embodiment)
A current measuring apparatus 100 according to the first embodiment will be described with reference to FIGS. 1 and 2. 1 is a plan view of the current measuring device 100, and FIG. 2 is a cross-sectional view of the current measuring device 100 taken along the line II-II in FIG. The current measuring device 100 is a device for measuring the current flowing through the bus bar 2. The current measuring device 100 is provided in a power conversion device (not shown) mounted on an electric vehicle (not shown). The power conversion device is a device for converting DC power supplied from a vehicle-mounted battery into AC power and supplying the AC power to a traveling AC motor (not shown). The current measuring device 100 is connected between a circuit in the power converter and an output terminal connected to the AC motor. That is, the current measuring device 100 measures the current flowing from the power converter to the AC motor. 1 and 2 describe an XYZ coordinate system. In the following description, the XYZ coordinate system is used to describe the configuration.

  The current measuring device 100 includes a bus bar 2, a substrate 3, a magnetoelectric conversion element 4, a shield member 5, bolts 6 a and 6 b, and a mold body 7. The bus bar 2 is a conductive member that extends in the Y-axis direction. In other words, the Y-axis direction coincides with the extending direction of the bus bar 2. The bus bar 2 is made of a conductive metal such as copper and has a rectangular cross section that is long in the Z-axis direction. The bus bar 2 is a part of a current path between a circuit in the power converter and an output terminal to the AC motor.

  The substrate 3 is a substrate for converting the output voltage of the magnetoelectric conversion element 4 into a current value indicating a current intensity. The board 3 extends in parallel with the bus bar 2 at a position spaced from the bus bar 2 in the Z-axis direction. In other words, the substrate 3 extends in parallel with the XY plane.

  The magnetoelectric conversion element 4 is an element for measuring the strength of the magnetic field (that is, the magnetic flux density) caused by the current flowing through the bus bar 2. The magnetoelectric conversion element 4 outputs an output voltage proportional to the strength of the magnetic field. The magnetoelectric conversion element 4 has a magnetosensitive surface 4a parallel to the YZ plane. The magnetoelectric conversion element 4 detects a magnetic field penetrating the magnetosensitive surface 4a of the magnetoelectric conversion element 4 along a specific direction, but magnetoelectric conversion along a direction orthogonal to the specific direction (that is, parallel to the magnetosensitive surface 4a). The magnetic field penetrating the element 4 is not detected. Specifically, the magnetoelectric conversion element 4 outputs an output voltage proportional to a component along a specific direction component of a magnetic flux line penetrating the magnetosensitive surface of the magnetoelectric conversion element. This specific direction is called a magnetosensitive direction.

  The magnetoelectric conversion element 4 is fixed to the surface 3 a on the bus bar 2 side of the substrate 3. The magnetoelectric conversion element 4 is disposed so as to face the side surface of the bus bar 2 facing the substrate 3. The magnetoelectric conversion element 4 is arranged so that the magnetic sensing direction SD1 is parallel to the surface 3a and parallel to the direction orthogonal to the extending direction (that is, the X-axis direction).

  The current flows through the bus bar 2 in the positive Y-axis direction (that is, the extending direction). The magnetic field caused by the current flowing through the bus bar 2 is generated so as to surround the cross section of the bus bar 2 when viewed from the extending direction. FIG. 2 schematically shows the magnetic flux line FL1 of this magnetic field. As shown in FIG. 2, the magnetic flux line FL <b> 1 becomes an oval along the outer shape of the cross section of the bus bar 2, and penetrates the magnetoelectric transducer 4 along the X-axis direction (that is, the magnetosensitive direction SD <b> 1). Thereby, the magnetoelectric conversion element 4 outputs an output voltage proportional to the strength of the magnetic field caused by the current flowing through the bus bar 2.

  The shield member 5 is a flat plate-like member, and is made of a material (for example, iron) having a magnetic permeability higher than that of air. The shield member 5 is disposed in parallel with the substrate 3. The shield member 5 is sandwiched between the substrate 3 and the bus bar 2 and faces the surface 3 a of the substrate 3. The shield member 5 is provided with a rectangular through hole 51 that penetrates in the thickness direction (that is, the Z-axis direction). When the shield member 5 is viewed in plan (see FIG. 1), the bus bar 2 is located inside the width L2 of the through hole 51 in the X-axis direction. In other words, the width L2 of the through hole 51 in the X-axis direction is larger than the width L1 of the bus bar 2 in the same direction.

  Here, the relationship between the through hole 51 and the magnetoelectric transducer 4 will be described. The magnetoelectric conversion element 4 is disposed inside the through hole 51 and is accommodated in the thickness T <b> 1 of the shield member 5. The magnetic sensitive surface 4a is also accommodated in the thickness T1. Due to this relationship, as shown in FIG. 2, the magnetic flux line FL1 passes through the magnetoelectric transducer 4 along the magnetosensitive direction SD1 without passing through the shield member 5. That is, the magnetoelectric conversion element 4 can detect the strength of the magnetic field caused by the current flowing through the bus bar 2.

  The opening on the substrate 3 side of the through hole 51 is closed by the substrate 3, and the opening on the bus bar 2 side is closed by the mold body 7. That is, the magnetoelectric conversion element 4 is sealed from the outside of the current measuring device 100 by being accommodated in the through hole 51. Thereby, the magnetoelectric conversion element 4 can be protected from foreign matters (for example, water, dust, etc.) from the outside of the current measuring device 100.

  A part of the bus bar 2 in the extending direction is covered with the mold body 7. The mold body 7 is made of an insulating resin. The bus bar 2 is insulated from other members (substrate 3, shield member 5, etc.) by the mold body 7. The substrate 3 and the shield member 5 are fixed to the surface of the mold body 7 on the substrate 3 side by bolts 6a and 6b.

  The shield member 5 will be described with reference to FIG. FIG. 3 is a plan view of the shield member 5, in which the magnetoelectric conversion element 4 disposed inside the through hole 51 of the shield member 5 is also drawn. In FIG. 3, illustration of through holes through which the bolts 6a and 6b penetrate is omitted. In FIG. 4 and FIGS. 9 to 11 to be described later, the illustration of the through holes is omitted.

  The shield member 5 includes a pair of side shielding portions 52a and 52b positioned on both sides of the magnetoelectric conversion element 4 in the magnetic sensing direction SD1 (ie, the X-axis direction), and magnetoelectric conversion in the extending direction (ie, the Y-axis direction). A pair of connection portions 53a and 53b that connect the side shielding portions 52a and 52b at positions that do not overlap with the element 4 are provided. The through hole 51 is a space surrounded by the pair of side shielding portions 52a and 52b and the pair of connection portions 53a and 53b. And the width L2 of said through-hole 51 is corresponded to the space | interval of a pair of side shielding part 52a, 52b.

  The effect of the present embodiment will be described. A magnetic field caused by another device (for example, a reactor of the power conversion device) located in the vicinity of the current measuring device 100 can become noise in the output of the magnetoelectric conversion element 4. As described above, the magnetoelectric conversion element 4 detects the magnetic field facing the magnetic sensing direction, but does not detect the magnetic field facing the direction orthogonal to the magnetic sensing direction SD1. FIG. 3 schematically shows a magnetic flux line NF1 of a magnetic field that faces a magnetic sensing direction (X-axis direction) among magnetic fields caused by other devices. Since the magnetic permeability of the shield member 5 is higher than that of air, the magnetic flux line NF1 passes through one of the pair of connection portions 53a and 53b from the side shielding portion 52b and reaches the side shielding portion 52a. In other words, the magnetic flux line NF1 is blocked by the side shielding part 52b and does not reach the magnetoelectric conversion element 4 positioned between the pair of side shielding parts 52a and 52b. As a result, the magnetoelectric conversion element 4 does not detect a magnetic field that becomes noise that faces the magnetic sensing direction. On the other hand, since the through-hole 51 penetrates the shield member 5 in the Z-axis direction, a magnetic field directed to the Z-axis direction among magnetic fields caused by other devices can reach the magnetoelectric conversion element 4. However, since the magnetoelectric conversion element 4 does not detect a magnetic field directed in the Z-axis direction (that is, a direction orthogonal to the magnetic sensing direction SD1), the magnetic field does not become noise of the magnetoelectric conversion element 4. As described above, the flat shield member 5 can realize the function of blocking the magnetoelectric conversion element 4 from the magnetic field that becomes noise.

  As shown in FIG. 2, the current measuring device 100 is assembled by fixing the flat shield member 5 together with the substrate 3 to the mold body 7. The assembly process of the current measuring device 100 can be simplified.

(Second embodiment)
A current measuring apparatus (reference numeral omitted) of the second embodiment will be described. The current measuring device of the present embodiment is the same as the current measuring device 100 of the first embodiment, except that the shape of the shield member is different. FIG. 4 is a plan view of the shield member 205 of the second embodiment. In addition, the same code | symbol as 1st Example is attached | subjected about the member with the same structure as 1st Example. The same applies to the embodiments described later.

  The shield member 205 is provided with a U-shaped notch 251 that opens in the Y-axis direction (that is, the extending direction of the bus bar 2). The magnetoelectric conversion element 4 is disposed inside the notch 251. In other words, the shield member 205 includes a pair of side shielding portions 252a and 252b positioned on both sides of the magnetoelectric conversion element 4 in the magnetosensitive direction SD1 (ie, the X-axis direction), and an extending direction (ie, the Y-axis). In the direction), one connecting portion 253 that connects the side shielding portions 52a and 52b at a position that does not overlap with the magnetoelectric conversion element 4 is provided. That is, of the inner surfaces constituting the U-shape of the notch 251, a pair of inner surfaces facing each other is configured by a pair of side shielding portions 252 a and 252 b, and the remaining inner surfaces are the connection portions 253. It is comprised by.

  Even in such a configuration, similarly to the shield member 5 of the first embodiment, the magnetic flux line NF1 of the magnetic field that becomes noise passes through the connecting portion 253 from the side shielding portion 252b and reaches the side shielding portion 252a. . That is, the magnetic flux line NF1 does not reach the magnetoelectric conversion element 4. As a result, the same effect as the first embodiment can be obtained.

(Third embodiment)
A current measuring apparatus 300 according to the third embodiment will be described. 5 shows a cross-sectional view of the current measuring device 300 viewed from the same direction as FIG. 2, and FIG. 6 shows a cross-sectional view taken along the line VI-VI in FIG. The current measuring device 300 is the same as that of the first embodiment except that the shapes of the bus bar 302, the shield member 305, and the mold body 307 are different from those of the first embodiment.

  The shield member 305 is the same as the shield member 5 of the first embodiment except that the thickness is different. That is, the shape of the shield member 305 in plan view is the same as that in FIG. That is, the shield member 305 includes a pair of side shielding portions 352a and 352b and a pair of connection portions 353a and 353b. The thickness T2 of the shield member 305 is larger than the thickness T1 of the shield member 5 of the first embodiment. A part of the bus bar 302 in the positive direction of the Z-axis (that is, the upper part of the bus bar 302 in the drawing) is located inside the thickness T2 of the shield member 305. In other words, the shield member 305 overlaps a part of the bus bar 302 in the positive Z-axis direction when viewed from the X-axis direction.

  As shown in FIG. 6, two grooves 321a and 321b are provided on the surface of the bus bar 302 on the substrate 3 side. The pair of connection portions 353a and 353b of the shield member 305 are accommodated in the grooves 321a and 321b, respectively. Thereby, interference with the connection parts 353a and 353b and the bus bar 302 is avoided.

  Two grooves 372a and 372b are also provided on the surface of the mold body 307 on the substrate 3 side, following the shape of the grooves 321a and 321b of the bus bar 302. The pair of connection portions 353a and 353b are accommodated in the grooves 372a and 372b, respectively. Further, on the surface of the mold body 307 on the substrate 3 side, a pair of steps 371a and 371b are provided on both sides in the X-axis direction (that is, both sides sandwiching the bus bar 302) (see FIG. 5). Each step extends in the extending direction (that is, the Y-axis direction) and connects the pair of grooves 372a and 372b. The bottom surfaces of the steps 371a and 371b are flush with the bottom surfaces of the grooves 372a and 372b. The pair of side shielding portions 352a and 352b of the shield member 305 are disposed at the steps 371a and 371b, respectively. Thereby, interference with the side shielding parts 352a and 352b and the mold body 307 is avoided.

  According to such a configuration, the thickness of the shield member 305 can be increased while maintaining the external dimensions of the current measuring device 300 in the Z-axis direction. The shield member 5 of the first embodiment can also block a magnetic field tilted in the Z-axis direction from the magnetic sensing direction (X-axis direction), but when the tilt increases, the magnetic field can pass through the magnetoelectric conversion element 4. In this embodiment, by increasing the thickness of the shield member 305, a magnetic field having a large inclination in the Z-axis direction can be blocked.

(Fourth embodiment)
A current measuring apparatus 400 according to the fourth embodiment will be described. FIG. 7 shows a cross-sectional view of the current measuring device 400 as seen from the same direction as FIG. The current measuring device 400 is obtained by adding shield members 408 and 409 to the current measuring device 100 of the first embodiment.

  The shield members 408 and 409 are flat members and are made of the same material as the shield member 5 of the first embodiment. In the modified example, the material may be different from that of the shield member 5, and the magnetic permeability of the shield members 408 and 409 may be different from the magnetic permeability of the shield member 5. The shield members 408 and 409 are arranged in parallel to each other so as to sandwich the substrate 3, the shield member 5, and the mold body 7. The shield member 408 is disposed in parallel with the substrate 3 on the back surface of the substrate 3 opposite to the surface 3a on the bus bar 2 side. The shield member 408 is fixed to the surface of the mold body 7 together with the substrate 3 and the shield member 5 by bolts 406a and 406b. The shield member 409 is disposed in parallel with the substrate 3 on the back surface of the mold body 7 opposite to the surface on the substrate 3 side. The shield member 409 is fixed to the back surface of the mold body 7 with bolts (not shown).

  According to such a configuration, not only the magnetic field directed in the magnetosensitive direction (X-axis direction) among the magnetic fields caused by other devices but also the magnetic field directed in the Z-axis direction is blocked by the shield members 408 and 409, It does not reach the conversion element 4. For example, a magnetic field tilted in the magnetic sensing direction from the Z-axis direction has a magnetic sensing direction component. In the present embodiment, such a magnetic field can also be blocked from the magnetoelectric conversion element 4. The magnetic flux line FL1 due to the current flowing through the bus bar 2 passes through a part of the shield member 409, but the shield member 409 is located on the opposite side of the bus bar 2 from the magnetoelectric conversion element 4 side. The shield member 409 does not prevent the magnetic flux line FL1 from passing through the magnetoelectric conversion element 4.

  Further, since the shield members 408 and 409 are flat members, the assembly process of the current measuring device 400 can be simplified.

(5th Example)
A current measuring apparatus 500 according to the fifth embodiment will be described. FIG. 8 shows a cross-sectional view of the current measuring device 500 viewed from the same direction as FIG. The current measuring apparatus 500 is the same as that of the first embodiment except that the configuration of the substrate 503 is different from that of the first embodiment.

  The substrate 503 also extends in parallel with the bus bar 2 at a position spaced from the bus bar 2 in the Z-axis direction. The substrate 503 is accommodated inside the through hole 51 of the shield member 5. The magnetoelectric conversion element 4 is fixed to the surface 503 a on the bus bar 2 side of the substrate 503. The substrate 503 is fixed to a flat fixing member 510. The fixing member 510 extends in parallel with the substrate 503 and the shield member 5. The fixing member 510 together with the shield member 5 is fixed to the surface of the mold body 7 on the substrate 503 side by bolts 6a and 6b. Even with such a configuration, the same effects as in the first embodiment can be obtained. Moreover, since the board | substrate 503 is covered with the fixing member 510, the shield member 5, and the mold body 7, the board | substrate 503 can be protected from the foreign material from the outside.

(Sixth embodiment)
A current measuring apparatus 600 according to the sixth embodiment will be described. FIG. 9 shows a cross-sectional view of the current measuring device 600 viewed from the same direction as FIG. The current measuring device 600 is a device for measuring the current flowing through each of the two bus bars 602a and 602b extending in the Y-axis direction in parallel with each other at a narrow interval. The current measuring device 600 includes two bus bars 602a and 602b, a substrate 603, two magnetoelectric conversion elements 604a and 604b, a shield member 605, bolts 606a to 606c, and a molded body 607. .

  The substrate 603 extends in parallel with each bus bar at a position spaced from the two bus bars 602a and 602b in the Z-axis direction. The magnetoelectric conversion elements 604a and 604b are fixed to the surface 603a of the substrate 603 on the bus bar 602a and 602b side. The magnetoelectric conversion elements 604a and 604b are arranged so that the magnetic sensing directions SD1a and SD1b are parallel to the X-axis direction. The magnetoelectric conversion elements 604a and 604b also have magnetic sensitive surfaces 604c and 604d parallel to the YZ plane, respectively, similarly to the magnetoelectric conversion element 4 of the first embodiment.

  The shield member 605 is a flat member and is made of the same material as the shield member 5 of the first embodiment. The shield member 605 is disposed in parallel with the substrate 603. The shield member 605 is provided with two through holes 651a and 651b penetrating in the thickness direction (that is, the Z-axis direction). When the shield member 605 is viewed in plan, the bus bar 602a is located inside the width L2 of the through hole 651a in the X-axis direction, and similarly, the bus bar 602b is located inside the width L2 of the through hole 651a.

  Each of the magnetoelectric conversion elements 604a and 604b is disposed inside each of the through holes 651a and 651b, and is accommodated in the thickness T1 of the shield member 605. The magnetosensitive surfaces 604c and 604d are also accommodated in the thickness T1. That is, the relationship between the magnetoelectric conversion element 604a, the bus bar 602a, and the through hole 651a of the shield member 605 is the same as that in the first embodiment, and the magnetoelectric conversion element 604a has a magnetic field strength caused by the current flowing through the bus bar 602a. Can be detected. Similarly, the magnetoelectric conversion element 604b can detect the strength of the magnetic field caused by the current flowing through the bus bar 602b.

  Part of the bus bars 602a and 602b in the extending direction is covered with a mold body 607. A substrate 603 and a shield member 605 are fixed to the surface of the mold body 607 on the substrate 603 side by bolts 606a to 606c.

  The shield member 605 will be described with reference to FIG. FIG. 10 is a plan view of the shield member 605. The shield member 605 includes three side shield portions 652a to 652c that are parallel to each other, and four connection portions 653a to 653d. The connection parts 653a and 653b connect the side shielding parts 652a and 652b to each other. The through hole 651a is a space surrounded by the side shielding portions 652a and 652b and the connection portions 653a and 653b. On the other hand, the connection parts 653c and 653d connect the side shielding parts 652b and 652c to each other. The through hole 651b is a space surrounded by the side shielding portions 652b and 652c and the connection portions 653c and 653d. Although the detailed description is omitted, the functions of the side shielding portions and the connecting portions are the same as those of the first embodiment, and the magnetic field caused by other devices faces the magnetic sensing direction (that is, the X-axis direction). The magnetic field is blocked by the shield member 605 and does not reach the magnetoelectric conversion elements 604a and 604b.

  Further, as shown in FIG. 9, magnetic field magnetic flux lines FL3 caused by the current flowing in the bus bar 602b that is not the measurement target of the magnetoelectric conversion element 604a can pass through the magnetoelectric conversion element 604a. In FIG. 9, a part of the magnetic flux line FL3 is omitted. As shown in FIG. 9, the magnetic flux line FL3 is oval along the shape of a rectangular cross section that is long in the Z-axis direction of the bus bar 602b, and therefore passes through the magnetoelectric conversion element 604a substantially along the Z-axis direction. For this reason, the magnetic flux line FL3 does not become noise of the magnetoelectric conversion element 604a.

  Also in the present embodiment, as in the first embodiment, the flat shield member 605 can be fixed to the mold body 607 together with the substrate 603, and the assembly process of the current measuring device 600 can be simplified. In particular, the shield from the magnetic field that becomes the noise of the plurality of magnetoelectric transducers can be realized by a single flat shield member, and the assembly process of the current measuring device 600 can be simplified.

(Seventh embodiment)
A current measuring apparatus (reference numeral omitted) of the seventh embodiment will be described. The current measuring device according to the present embodiment is the same as the current measuring device 600 according to the sixth embodiment except that the shape of the shield member is different. FIG. 11 is a plan view of the shield member 705 of the seventh embodiment.

  The shield member 705 is provided with two notches 751a and 751b. The notches 751a and 751b are both U-shaped and both open in the positive Y-axis direction. Each of the magnetoelectric conversion elements 604a and 604b is disposed inside each of the notches 751a and 751b. In other words, the shield member 705 includes three side shield portions 752a to 752c that are parallel to each other and two connection portions 753a and 753d. A pair of inner surfaces facing each other among the inner surfaces constituting the U-shape of the notch 751a are configured by side shielding portions 752a and 752b, and the remaining inner surfaces are configured by a connection portion 753a. Yes. Similarly, the inner side surface constituting the U-shape of the notch 751b is also composed of side shielding portions 752b and 752c and a connection portion 753d.

  Although the detailed description is omitted, the functions of the side shielding portions and the connecting portions are the same as those of the second embodiment, and the magnetic field caused by other devices faces the magnetic sensing direction (that is, the X-axis direction). The magnetic field is blocked by the shield member 705 and does not reach the magnetoelectric conversion elements 604a and 604b. In this embodiment, the same effects as in the sixth embodiment can be obtained.

(Eighth embodiment)
A current measuring apparatus (reference numeral omitted) of the eighth embodiment will be described. The current measuring device according to the present embodiment is the same as the current measuring device 600 according to the sixth embodiment except that the shape of the shield member is different. FIG. 12 is a plan view of the shield member 805 of the eighth embodiment.

  As in the seventh embodiment, the shield member 805 is provided with two notches 851a and 851b. However, the directions of the openings of the notches 851a and 851b are opposite to each other, unlike the seventh embodiment. Specifically, the opening of the notch 851a faces the Y axis positive direction, and the opening of the notch 851b faces the Y axis negative direction. In other words, the shield member 805 includes three side shield portions 852a to 852c that are parallel to each other and two connection portions 853a and 853d. The connecting portion 853a that connects the side shielding portions 852a and 852b is located on the opposite side to the opening of the notch 851a, that is, in the Y-axis negative direction. The connection portion 853d that connects the side shielding portions 852b and 852c is located on the opposite side to the opening of the notch 851b, that is, in the Y-axis positive direction. Also in this embodiment, the same effects as in the sixth and seventh embodiments can be obtained.

  Hereinafter, points to be noted regarding the technology shown in the embodiments will be described. The technology described in each of the above embodiments is not limited to two bus bars, but can be applied to three or more bus bars extending in parallel to each other. In the above embodiment, the bus bar 2 is an example of the “conductive member”. As another example, for example, a cable (that is, an electric wire) covered with a protective coating of an insulator may be used.

  Further, the shape of the through hole 51 of the shield member 5 is not limited to a rectangle. As another example, a polygon or a circle may be used.

  Further, the magnetoelectric conversion element 4 may not be fixed to the surface 3 a of the substrate 3 on the bus bar 2 side. For example, the magnetoelectric conversion element 4 is fixed to one end of a lead wire penetrating the substrate 3, the one end is located on the surface 3 a side of the substrate 3, and the other end is opposite to the surface 3 a of the substrate 3. It may be fixed to the back side. Generally speaking, the magnetoelectric conversion element only needs to be fixed to the surface side of the substrate on the conductive member side.

  Moreover, the thickness of the shield member 5 may not be uniform. For example, the thickness of the pair of side shielding portions 52a and 52b may be larger than the thickness of the pair of connection portions 53a and 53b.

  The magnetoelectric conversion element 4 may be accommodated in a housing. In this case, the width of the casing in the Z-axis direction may be larger than the thickness T1 of the shield member 5, and the casing may be exposed from the shield member 5. The magnetosensitive surface 4 a of the magnetoelectric conversion element 4 only needs to be accommodated in the thickness T <b> 1 of the shield member 5.

  Specific examples of the present invention have been described in detail above, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above. The technical elements described in this specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology exemplified in this specification or the drawings can achieve a plurality of objects at the same time, and has technical usefulness by achieving one of the objects.

2, 302, 602a, 602b: Bus bar 3, 503, 603: Substrate 4, 604a, 604b: Magnetoelectric conversion element SD1, SD1a, SD1b: Magnetosensitive direction 5, 205, 305, 605, 705, 805: Shield member T1, T2: Thickness 52a, 52b, 252a, 252b, 352a, 352b, 652a, 652b, 652c, 752a, 752b, 752c, 852a, 852b, 852c: Side shield part 53a, 53b, 253a, 353a, 353b, 653a, 653b , 653c, 653d, 753a, 753d, 853a, 853d: connection portion 6a, 6b, 406a, 406b, 606a: bolt 7, 307, 607: mold body 100, 300, 400, 500, 600, 800: current measuring device

Claims (1)

Current measuring device,
A conductive member extending in one direction (extending direction);
A substrate extending parallel to the conductive member at a distance from the conductive member;
A magnetoelectric conversion element that is fixed to the surface side of the substrate on the conductive member side, detects a magnetic field in a direction (orthogonal direction) that is parallel to the surface and orthogonal to the extending direction of the conductive member;
A flat shield member disposed in parallel with the substrate;
The flat shield member includes a pair of side shielding portions located on both sides of the magnetoelectric conversion element in the orthogonal direction, and a pair of side shielding portions located at positions that do not overlap the magnetoelectric conversion element in the extending direction. It has a connection part to connect
When the substrate is viewed in plan, the conductive member is located within the interval between the pair of side shielding portions,
A current measuring device in which a magnetosensitive surface of the magnetoelectric transducer is accommodated in the thickness of the shield member.

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