JP2014202480A - Magnetic shield body for current sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic shield body that is able to hinder entry of disturbance magnetic field from all six directions.SOLUTION: In a first magnetic shield part 20, second side faces 28a, 28b of a second plate part 22 are arranged perpendicular to first side faces 25a, 25b of a first plate part 21. Thus, the first magnetic shield part 20 hinders entry of disturbance magnetic fields from the total of five directions: one direction from a first upper face 24 and four directions from the first side faces 25a, 25b and from the second side faces 28a, 28b. On the other hand, in a second magnetic field part 30, a third upper face 33 of a third plate part 31 hinders entry of a disturbance of magnetic field from the third upper face 33. Also, third side faces 34a, 34b intercept disturbance magnetic fields from two directions that are the same as the first side faces 25a, 25b. Accordingly, in a magnetic shield body 1, entry of disturbance magnetic fields from all the six directions can be hindered.

Description

  The present invention relates to a magnetic shield body for a current sensor.

  Conventionally, a configuration of a current sensor including a magnetic shield body has been proposed in Patent Document 1, for example. The magnetic shield body is a component that surrounds the outer side of the annular outer shell portion in which the current detection unit is accommodated and shields a disturbance magnetic field from the outside. Patent Document 1 proposes a magnetic shield body that is assembled to an annular outer shell portion so that two semi-square cylinders, that is, U-shaped magnetic shield members are square cylinders.

  A current sensor provided with such a magnetic shield body detects a current flowing so as to penetrate an annular outer shell portion located in a hollow portion of the magnetic shield body. The rectangular cylindrical magnetic shield body has four surfaces in a direction perpendicular to the direction penetrating the hollow portion of the magnetic shield body. For this reason, the magnetic shield body functions to shield disturbance magnetic fields from four directions perpendicular to these four surfaces.

JP 2010-14477 A

  However, in the above-described conventional technology, the magnetic shield body has a rectangular tube shape in which two magnetic shield members are combined, and therefore there are two openings in the direction penetrating the hollow portion of the magnetic shield body. For this reason, there exists a problem that a disturbance magnetic field will penetrate | invade into the hollow part of a magnetic shield body from two directions through two openings of a magnetic shield body. Therefore, the direction in which the current sensor is affected by the disturbance magnetic field must be taken into account, and the mounting of the current sensor on the object to be measured occurs. Alternatively, the current sensor is limited to use in an environment where the disturbance magnetic field is weak.

  Here, in order to ensure the magnetic shield effect of the magnetic shield body in an environment where a strong disturbance magnetic field is received, it is conceivable to increase the thickness of the plate material constituting the magnetic shield member. However, since the resistance value of the plate material decreases with the thickness of the plate material, there is a problem that heat generation due to the eddy current loss generated in the magnetic shield body subjected to the disturbance magnetic field increases. Therefore, heat generated by eddy current loss adversely affects the current detection characteristics of the current sensor. Therefore, it is not preferable to thicken the plate material constituting the magnetic shield member.

  An object of this invention is to provide the magnetic shield body which can suppress the penetration | invasion of the disturbance magnetic field from all six directions in view of the said point.

  In order to achieve the above object, according to the first aspect of the present invention, a current sensor that forms a housing space (4) in which a current sensor including a magnetoresistive element (12) for detecting a current to be measured is housed is housed. This is a magnetic shield body for use with the following features.

  First, a pair of first side surfaces (25a, 25b) facing each other is formed on both sides of the first upper surface (24) by bending the first flat plate member (23) that suppresses intrusion of electromagnetic waves. A pair of second side surfaces (28a, 28b) facing each other on both sides of the second upper surface (27) by bending the one plate portion (21) and the second flat plate member (26) that suppresses intrusion of electromagnetic waves. And a second plate part (22) formed with a first magnetic shield part (20).

  In addition, the third flat plate member (32) that suppresses intrusion of electromagnetic waves is bent to form a pair of third side surfaces (34a, 34b) facing each other on both sides of the third upper surface (33). A second magnetic shield part (30) having a plurality of three plate parts (31) is provided.

  The first magnetic shield part (20) has the first upper surface (24) and the second upper surface (27) in contact with each other, and the first side surface (25a, 25b) and the second side surface (28a, 28b). Are overlapped with each other so that the first plate portion (21) and the second plate portion (22) overlap each other.

  The second magnetic shield part (30) has a plurality of third plates such that the third upper surfaces (33) of the plurality of third plate parts (31) are in contact with each other and the third side surfaces (34a, 34b) are in contact with each other. The plate part (31) is overlaid.

  Further, in the accommodation space (4), the third upper surface (33) faces the third upper surface (33) side of the first upper surface (24) and the second upper surface (27), and the third side surfaces (34a, 34b). ) Is adjacent to one of the first side surface (25a, 25b) and the second side surface (28a, 28b), the first magnetic shield part (20) and the second magnetic shield part (30) are It is characterized by being formed in combination.

  According to this, since the second side surface (28a, 28b) of the second plate portion (22) is arranged adjacent to the first side surface (25a, 25b) of the first plate portion (21), Intrusion of a disturbance magnetic field from five directions can be suppressed in the first magnetic shield part (20). In addition, the third upper surface (33) of the third plate portion (31) can suppress the intrusion of a disturbance magnetic field from the side opposite to the first upper surface (24) of the first magnetic shield portion (20). Therefore, in the magnetic seal body, it is possible to suppress the penetration of the disturbance magnetic field from all six directions.

  In addition, the code | symbol in the bracket | parenthesis of each means described in this column and the claim shows the correspondence with the specific means as described in embodiment mentioned later.

It is the schematic diagram by which the magnetic shield body which concerns on one Embodiment of this invention was installed in the bus-bar. It is a figure for demonstrating the current measurement principle of a current sensor. It is a schematic diagram of a magnetic shield body. FIG. 4 is an exploded view of the magnetic shield body shown in FIG. 3. It is X sectional drawing of FIG. It is Y sectional drawing of FIG. (A) is the figure which showed a mode that an eddy current loss was divided | segmented when a some thin plate was used, (b) showed a mode that an eddy current loss generate | occur | produced when one thin plate was used. FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. As shown in FIGS. 1 and 2, the magnetic shield body 1 according to the present invention is disposed around a current sensor 10 for detecting the magnitude of the current to be measured flowing through the bus bar 2.

  The bus bar 2 is fixed to the holding member 3 as shown in FIG. The holding member 3 has grooves and protrusions for positioning, and is a part for positioning the bus bar 2, the current sensor 10, and the magnetic shield body 1 in a self-aligned manner.

  As shown in FIG. 2, the current sensor 10 includes a bias magnet 11 and a magnetoresistive element 12. Among them, the bias magnet 11 is a magnetic field generating unit that generates a bias magnetic field in a direction perpendicular to a signal magnetic field generated when a current to be measured flows through the bus bar 2. That is, the bias magnet 11 is disposed above the bus bar 2 so that the N pole and the S pole are aligned in the direction in which the current to be measured flows, that is, the longitudinal direction of the bus bar 2. As a result, the bias magnet 11 applies a bias magnetic field to the magnetoresistive element 12.

  The magnetoresistive element 12 has a sensing unit whose resistance value changes when affected by an external magnetic field. For example, the magnetoresistive element 12 is disposed in the vicinity of the bus bar 2, that is, between the bus bar 2 and the bias magnet 11.

  In addition, the current sensor 10 is disposed in a housing space that is a hollow portion of the magnetic shield body 1 so that the current direction of the current to be measured flowing through the bus bar 2, that is, the longitudinal direction of the bus bar 2 is parallel to the bias magnetic field. In other words, the current sensor 10 is housed in the magnetic shield body 1 so that the signal magnetic field generated by the current to be measured flowing through the bus bar 2 and the bias magnetic field are perpendicular to each other. Therefore, a synthetic magnetic field composed of a bias magnetic field and a signal magnetic field is applied to the magnetoresistive element 12.

  Then, a signal magnetic field is generated when the current to be measured flows through the bus bar 2, and the magnetic field angle θ is changed by changing the combined magnetic field composed of the signal magnetic field and the bias magnetic field according to the magnitude of the current to be measured. . Therefore, the magnetoresistive element 12 detects that the resistance value of the sensing unit has changed due to the change in angle.

  The magnetic shield body 1 shown in FIG. 3 has a housing space 4 for housing a part of the bus bar 2 and the current sensor 10, and serves to shield a magnetic field from the outside. The magnetic shield body 1 includes a first magnetic shield part 20 and a second magnetic shield part 30.

  As shown in FIG. 4, the first magnetic shield part 20 is configured by stacking a first plate part 21 and a plurality of second plate parts 22. In the present embodiment, the first magnetic shield part 20 has two second plate parts 22.

  The first plate portion 21 is formed with a pair of first side surfaces 25 a and 25 b that are opposed to each other in parallel on both sides of the first upper surface 24 by bending the first flat plate-like member 23 that suppresses intrusion of electromagnetic waves. It is configured. Further, the second plate portion 22 is formed with a pair of second side surfaces 28a and 28b facing each other in parallel on both sides of the second upper surface 27 by bending the second flat plate-like member 26 that suppresses intrusion of electromagnetic waves. Has been configured. The two second plate portions 22 are overlapped so that the second upper surfaces 27 are in contact with each other, and one second side surface 28a and the other second side surface 28b are in contact with each other.

  Here, the second side surfaces 28 a and 28 b of the second plate portion 22 have a protruding portion 29 in which a part of the end portion on the opposite side to the second upper surface 27 extends in a direction away from the second upper surface 27. . In the present embodiment, the protruding portion 29 is formed by extending both end portions of the second side surfaces 28 a and 28 b in the direction perpendicular to the extending direction of the second side surfaces 28 a and 28 b away from the second upper surface 27. Is provided. In other words, a part of the second side surface 28a, 28b opposite to the second upper surface 27 is recessed toward the second upper surface 27, so that the portion constituting the recessed portion becomes the protruding portion 29. . It can be said that the surface of the second side surfaces 28a and 28b is a divided surface in which a part of the second side surfaces 28a and 28b is divided by the dent portion and the protruding portion 29.

  And the 1st upper surface 24 of the 1st board part 21 and the 2nd upper surface 27 of one 2nd board part 22 are piled up so that it may mutually contact in parallel. In addition, the second upper surface 27 of one second plate portion 22 and the second upper surface 27 of the other second plate portion 22 are overlapped so as to contact each other in parallel. Thereby, the 1st board part 21 is located in the outer side, and one 2nd board part 22 is located inside, ie, the accommodation space 4 side.

  The first side surfaces 25 a and 25 b of the first plate portion 21 are sandwiched between the second side surfaces 28 a and 28 b of the second plate portions 22. Specifically, the first plate portion 21 and the second plates are arranged such that the first side surfaces 25a and 25b of the first plate portion 21 and the second side surfaces 28a and 28b of the second plate portions 22 are perpendicular to each other. The part 22 is overlapped. Thus, the first magnetic shield part 20 is configured.

  On the other hand, the second magnetic shield part 30 is configured by overlapping a plurality of third plate parts 31. In the present embodiment, the second magnetic shield part 30 has three third plate parts 31. The third plate portion 31 is formed with a pair of third side surfaces 34a and 34b facing each other in parallel on both sides of the third upper surface 33 by bending the third flat plate member 32 that suppresses intrusion of electromagnetic waves. It is configured. The three third plate portions 31 are stacked such that the third upper surfaces 33 of the plurality of third plate portions 31 are in contact with each other in parallel and the third side surfaces 34a and 34b are in contact with each other in parallel. In this way, the second magnetic shield part 30 is configured.

  Each of the flat plate members 23, 26, 32 is formed of a thin plate. As each flat member 23, 26, 32, for example, a 0.5 mm electromagnetic steel plate is employed. An insulating film is formed on the surface of the electromagnetic steel sheet. Moreover, each said board part 21,22,31 is bend | folded by the shape shown by FIG. 3 by pressing the thin plate processed into the predetermined shape. As a result, the shape is generally “U” as described above. The dimensions of the first flat plate member 23 and the second flat plate member 26 are set so that the first plate portion 21 and the two second plate portions 22 are stacked in close contact. Similarly, the dimensions of the respective third flat plate members 32 are set so that the three third flat plate members 32 are stacked in close contact.

  As shown in FIG. 3, the first magnetic shield is arranged such that the third upper surface 33 of the second magnetic shield unit 30 is parallel to the first upper surface 24 and the second upper surface 27 of the first magnetic shield unit 20. The part 20 and the second magnetic shield part 30 are combined. Further, the first magnetic shield part 20 and the second magnetic shield part 30 are arranged such that the third side faces 34a and 34b of the second magnetic shield part 30 are parallel to the first side faces 25a and 25b of the first magnetic shield part 20. Are combined. Thereby, the accommodation space 4 is formed between the first magnetic shield part 20 and the second magnetic shield part 30. The first magnetic shield part 20 and the second magnetic shield part 30 are assembled to the holding member 3 so as to form the accommodation space 4.

  The first magnetic shield part 20 and the second magnetic shield part 30 are fixed to the holding member 3 by screwing the holding member 3 or by molding the magnetic shield body 1 with resin.

  In addition, the protruding portion 29 of the second side surfaces 28a and 28b described above is on the opposite side of the second upper surface 24 and the second upper surface 27 of the second side surfaces 28a and 28b arranged perpendicular to the third side surfaces 34a and 34b. It can be said that a part of the end portion extends in a direction away from the first upper surface 24 and the second upper surface 27.

  Further, the third upper surface 33 of the second magnetic shield part 30 has a protruding portion 35 from which a part of the third upper surface 33 protrudes. The protruding portion 35 is provided in a portion corresponding to the recessed portion formed by the protruding portion 29 in the second side surfaces 28 a and 28 b of the first magnetic shield portion 20. With this protrusion 35, the shielding area of the third upper surface 33 can be increased.

  According to the configuration of the magnetic shield body 1 as described above, the first upper surface 24 of the first magnetic shield portion 20 shields a disturbance magnetic field from one direction on the first upper surface 24 side of the bus bar 2. Further, the first side surfaces 25 a and 25 b of the first magnetic shield part 20 shield a disturbance magnetic field from two directions perpendicular to the longitudinal direction of the bus bar 2 in a plane parallel to the flat part of the bus bar 2. Further, the second side surfaces 28 a and 28 b of the second magnetic shield part 30 shield a disturbance magnetic field from two directions parallel to the longitudinal direction of the bus bar 2 in a plane parallel to the flat part of the bus bar 2.

  On the other hand, the third upper surface 33 of the second magnetic shield part 30 shields a disturbance magnetic field from one direction on the third upper surface 33 side of the bus bar 2. Further, the third side surfaces 34a and 34b of the second magnetic shield part 30 are disturbed from two directions perpendicular to the longitudinal direction of the bus bar 2 in a plane parallel to the plane part of the bus bar 2 in the same manner as the first side surfaces 25a and 25b. Shield the magnetic field. Therefore, the magnetic shield body 1 has a surface or a part of a surface that shields disturbance magnetic fields from all six directions.

  Next, the current sensor 10 disposed in the accommodation space 4 of the magnetic shield body 1 will be described. 5 and 6, the current sensor 10 includes a lead 13, a circuit chip 14, and a resin package 15 in addition to the bias magnet 11 and the magnetoresistive element 12 described above. 5 and 6, the holding member 3 is omitted.

  The lead 13 has one surface 13a on which the bias magnet 11 is mounted and the other surface 13b on which the magnetoresistive element 12 and the circuit chip 14 are mounted. The circuit chip 14 outputs a signal corresponding to the current to be measured to the outside by performing a preset operation on the signal input from the magnetoresistive element 12. Bonding wires 16 are electrically connected between the magnetoresistive element 12 and the circuit chip 14 and between the circuit chip 14 and the leads 13. The resin package 15 is a sealing member that seals the bias magnet 11, the magnetoresistive element 12, the lead 13, the circuit chip 14, and a part of the lead 13 so that a part of the lead 13 is exposed.

  Here, when the current sensor 10 is accommodated in the accommodating space 4 of the magnetic shield body 1, the first magnetic shield part 20 and the second magnetic shield part 30 are arranged with each other through the gap 40. In the present embodiment, the first side surfaces 25a and 25b, the second side surfaces 28a and 28b, and the third side surfaces 34a and 34b are arranged with a gap 40 therebetween. The air gap 40 plays a role of passing the bus bar 2, a role of taking out a signal from the accommodation space 4 of the magnetic shield body 1, and a role of resistance to weaken the disturbance magnetic field by the air located in the air gap 40. The air gap 40 is formed in a self-aligned manner by assembling the first magnetic shield part 20 and the second magnetic shield part 30 to the holding member 3.

  The magnetoresistive element 12 has a detection surface 12 a for detecting a change in the magnetic field generated in the accommodation space 4 when the current to be measured flows through the bus bar 2. The sensing surface for detecting a change in magnetic field is provided on the detection surface 12a.

  Then, as shown in FIG. 6, a signal magnetic field generated from the bus bar 2 is generated in the accommodation space 4 and re-emitted in the gap 40 between the first magnetic shield part 20 and the second magnetic shield part 30. At this time, it is necessary to suppress the influence of the magnetoresistive element 12 on the detection surface 12a. Therefore, in the magnetic shield body 1, the central portion of the accommodation space 4 is least affected by the disturbance magnetic field, so that the detection surface 12 a of the magnetoresistive element 12 is disposed in the central portion of the magnetic shield body 1.

  Specifically, if the height of the accommodation space 4 in the direction perpendicular to the first upper surface 24 is defined as h, the detection surface 12 a of the magnetoresistive element 12 is parallel to the first upper surface 24 of the first magnetic shield part 20. And at a height of h / 2. Further, the center position 12 b of the detection surface 12 a of the magnetoresistive element 12 is a center position 41 of a surface parallel to the first upper surface 24 in the accommodation space 4 in a direction perpendicular to the first upper surface 24 of the first magnetic shield part 20. The first magnetic shield part 20 and the second magnetic shield part 30 are combined so as to be arranged to match. That is, the magnetoresistive element 12 is arranged so that the detection surface 12a is symmetrical at the position h / 2 in the accommodation space 4 of the magnetic shield body 1.

  The position of the detection surface 12a of the magnetoresistive element 12 in the accommodation space 4 is determined in a self-aligning manner by arranging the current sensor 10 on the holding member 3 and assembling the magnetic shield body 1 on the holding member 3. Designed in advance. By defining the position of the detection surface 12a of the magnetoresistive element 12 in this way, the detection surface 12a of the magnetoresistive element 12 can be positioned at a position farthest from the outside of the magnetic shield body. For this reason, it becomes difficult for the magnetoresistive element 12 to receive the influence of the exterior of the magnetic shield body 1, and it can reduce the influence on the detection characteristic of the magnetoresistive element 12.

  On the other hand, as shown in FIG. 5, it is not necessary to consider the signal magnetic field of the bus bar 2 in the longitudinal direction of the bus bar 2. Therefore, emphasis is placed on the suppression of the disturbance magnetic field that enters the housing space 4 of the magnetic shield body 1 from the outside, so that the disturbance magnetic field is not directly applied to the magnetoresistive element 12. 40 is provided.

  Next, effects of the magnetic shield body 1 according to this embodiment will be described. The present embodiment is characterized in that the magnetic shield body 1 shown in FIGS. 3 and 4 is configured. In particular, in the first magnetic shield part 20, the second side faces 28 a and 28 b of the second plate part 22 are arranged perpendicular to the first side faces 25 a and 25 b of the first plate part 21. For this reason, the first magnetic shield part 20 can suppress the intrusion of a disturbance magnetic field from five directions including the two directions of the second side surfaces 28a and 28b.

  Further, in the second magnetic shield part 30, the third upper surface 33 of the third plate part 31 is opposite to the direction that cannot be shielded by the first magnetic shield part 20, that is, the first upper surface 24 of the first magnetic shield part 20. Intrusion of a disturbance magnetic field from the side can be suppressed. Of course, the third side surfaces 34a and 34b can shield the disturbance magnetic field from the same two directions as the first side surfaces 25a and 25b. Therefore, in the magnetic shield body 1, it is possible to suppress the intrusion of a disturbance magnetic field from all six directions. In this embodiment, it can be used in a magnetic field of 10 mT practically.

  In particular, when the bus bar 2 handles a strong disturbance magnetic field and a high-frequency AC current, for example, when the bus bar 2 passes a current that drives a three-phase AC motor, the influence of the disturbance magnetic field generated in the adjacent bus bar 2 by the current sensor 10. Can be considered. However, since the disturbance magnetic field from all six directions can be shielded by the magnetic shield body 1 according to the present embodiment, the shielding effect against the disturbance magnetic field can be exhibited even in a situation where a high-frequency alternating current is handled.

  In the present embodiment, the first side surfaces 25a, 25b and the second side surfaces 28a, 28b are arranged vertically, and the first side surfaces 25a, 25b and the third side surfaces 34a, 34b are arranged in parallel. The overall shape of the magnetic shield body 1 can be a cubic shape. For this reason, the whole size of the magnetic shield body 1 can be minimized.

  Here, in the present embodiment, the second side surfaces 28a and 28b are provided with the protruding portions 29 in which a part of the second side surfaces 28a and 28b protrudes. Therefore, a disturbance magnetic field is generated on the second side surfaces 28a and 28b. The shielding part for shielding can be increased. Therefore, it is possible to improve the magnetic shield effect against the disturbance magnetic field.

  Moreover, the magnetic shield body 1 has a gap 40 between the side surfaces. The air gap 40 cannot be completely eliminated for reasons such as signal extraction, but the air located in the air gap 40 functions as a resistance to weaken the disturbance magnetic field as described above. For this reason, the plate | board thickness of the 1st flat plate member 23, the 2nd flat plate member 26, and the 3rd flat plate member 32 which comprise the 1st magnetic shield part 20 and the 2nd magnetic shield part 30 can be made thin, respectively. There is a merit.

  Further, in the present embodiment, the first magnetic shield part 20 and the second magnetic shield part 30 are characterized in that a plurality of thin plates (flat plate members 23, 26, 32) are laminated while being insulated from each other. . Thereby, as shown in FIG. 7A, the eddy current loss generated in proportion to the square of the plate thickness of each flat plate member 23, 26, 32 is divided into small plates. Therefore, as shown in FIG. 7B, the heat generation of the first magnetic shield part 20 and the second magnetic shield part 30 is suppressed as compared with the use of one flat plate member having a plate thickness of three sheets. Can do.

  As described above, when the bus bar 2 handles high-frequency alternating current, the influence of the disturbance magnetic field from the adjacent bus bar 2 is large. However, the magnetic shield body 1 is composed of a plurality of thin plates, thereby generating heat due to eddy current loss. Can be suppressed. For this reason, it is possible to prevent the characteristics of the current sensor 10 and the magnetoresistive element 12 from being affected by the heat generated by the magnetic shield body 1.

(Other embodiments)
The configuration of the magnetic shield body 1 shown in each of the above embodiments is an example, and is not limited to the configuration shown above, and may be another configuration that can realize the present invention. For example, in the above embodiment, the magnetic shield body 1 has a cubic shape, but this is an example of the shape of the magnetic shield body 1. Therefore, each surface does not need to be parallel or perpendicular to each other.

  Specifically, the first side surfaces 25a and 25b only need to face each other. The same applies to the second side surfaces 28a and 28b and the third side surfaces 34a and 34b. In addition, the first magnetic shield part 20 has the first upper surface 24 and the second upper surface 27 in contact with each other, and the first side surfaces 25a and 25b and the second side surfaces 28a and 28b are adjacent to each other. The board part 21 and the 2nd board part 22 should just be piled up. Regarding the second magnetic shield part 30, the plurality of third plate parts 31 are stacked such that the third upper surfaces 33 of the plurality of third plate parts 31 are in contact with each other and the third side surfaces 34a, 34b are in contact with each other. Just do it. In this case, for the accommodation space 4, the third upper surface 33 faces the third upper surface 33 side of the first upper surface 24 and the second upper surface 27, and the third side surfaces 34 a and 34 b are the first side surfaces 25 a and 25 b and the second upper surface 27. The first magnetic shield part 20 and the second magnetic shield part 30 are combined and formed so as to be adjacent to one of the two side surfaces 28a and 28b.

  Here, when combining the first magnetic shield part 20 and the second magnetic shield part 30, not only the first side faces 25a and 25b and the third side faces 34a and 34b are adjacent to each other, but also the second side faces 28a and 28b. And the third side surfaces 34a and 34b may be adjacent to each other.

  Moreover, the shape of the protrusion part 29 provided in the 2nd side surfaces 28a and 28b and the protrusion part 35 provided in the 3rd upper surface 33 is not restricted to the shape shown by FIG.3 and FIG.4, It can set suitably. That is, if a part of the second side surfaces 28a and 28b and a part of the third upper surface 33 are projected, a shielding effect against a disturbance magnetic field can be generated in the projected part.

  The air gap 40 may be set in any way. In the above embodiment, the gap 40 is provided between the side surfaces, but this is an example in which the gap 40 is provided. For example, the first side surfaces 25a and 25b may be in contact with the second side surfaces 28a and 28b, and the third side surfaces 34a and 34b may be in contact with one of the first side surfaces 25a and 25b and the second side surfaces 28a and 28b. You may do it.

  Furthermore, in the above embodiment, the first magnetic shield part 20 and the second magnetic shield part 30 are each composed of three thin plates, but the first magnetic shield part 20 and the second magnetic shield part 30 are thin plates. It is not necessary to have the same number of sheets. Further, the number of the first plate portion 21 and the second plate portion 22 of the first magnetic shield portion 20 and the number of the third plate portion 31 of the second magnetic shield portion 30 according to the strength of the magnetic field received by the magnetoresistive element 12. May be determined.

4 accommodating space 12 magnetoresistive element 20, 30 first, second magnetic shield part 21, 22, 31 first to third plate part 23, 26, 32 first to third flat plate member 24, 27, 33 first -3rd upper surface 25a, 25b 1st side surface 28a, 28b 2nd side surface 34a, 34b 3rd side surface

Claims (8)

A magnetic shield for a current sensor that forms a housing space (4) in which a current sensor including a magnetoresistive element (12) for detecting a current to be measured is housed,
A first plate in which a pair of first side surfaces (25a, 25b) facing each other is formed on both sides of the first upper surface (24) by bending the first flat plate member (23) that suppresses the intrusion of electromagnetic waves. A pair of second side surfaces (28a, 28b) facing each other on both sides of the second upper surface (27) by bending the portion (21) and the second flat plate-like member (26) that suppresses intrusion of electromagnetic waves. A first magnetic shield part (20) having a formed second plate part (22);
A third plate in which a pair of third side surfaces (34a, 34b) facing each other is formed on both sides of the third upper surface (33) by bending the third flat plate-like member (32) that suppresses intrusion of electromagnetic waves. A second magnetic shield part (30) having a plurality of parts (31);
With
The first magnetic shield part (20) has the first upper surface (24) and the second upper surface (27) in contact with each other, and the first side surface (25a, 25b) and the second side surface (28a, 28b) are adjacent to each other, the first plate portion (21) and the second plate portion (22) are overlapped,
The second magnetic shield part (30) is configured such that the third upper surfaces (33) of the plurality of third plate parts (31) are in contact with each other and the third side surfaces (34a, 34b) are in contact with each other. The plurality of third plate portions (31) are stacked,
Further, in the accommodation space (4), the third upper surface (33) faces the third upper surface (33) side of the first upper surface (24) and the second upper surface (27), and The first magnetic shield part (20) and the three side surfaces (34a, 34b) are adjacent to one of the first side surface (25a, 25b) and the second side surface (28a, 28b). A magnetic shield for a current sensor, wherein the magnetic shield is formed in combination with a second magnetic shield (30). The pair of first side surfaces (25a, 25b) face each other in parallel on both sides of the first upper surface (24),
The pair of second side surfaces (28a, 28b) face each other in parallel on both sides of the second upper surface (27),
The pair of third side surfaces (34a, 34b) face each other in parallel on both sides of the third upper surface (33),
The first magnetic shield part (20) has the first upper surface (24) and the second upper surface (27) in parallel contact with each other, and the first side surface (25a, 25b) and the second side surface ( 28a, 28b) and the first plate portion (21) and the second plate portion (22) are overlapped so that they are perpendicular to each other,
In the second magnetic shield part (30), the third upper surfaces (33) of the plurality of third plate parts (31) contact each other in parallel and the third side surfaces (34a, 34b) contact each other in parallel. The plurality of third plate portions (31) are stacked,
Further, the accommodation space (4) has the third upper surface (33) parallel to the first upper surface (24) and the second upper surface (27), and the third side surfaces (34a, 34b). The first magnetic shield part (20) and the second magnetic shield part (30) are parallel to any one of the first side face (25a, 25b) and the second side face (28a, 28b). And the magnetic shield body for a current sensor according to claim 1. The magnetoresistive element (12) has a detection surface (12a) for detecting a change in a magnetic field generated in the accommodation space (4) when the current to be measured flows.
The first magnetic shield part (20) and the second magnetic shield part (30) have the magnetoresistance when the height of the accommodating space (4) in the direction perpendicular to the first upper surface (24) is h. The detection surface (12a) of the element (12) is parallel to the first upper surface (24) and is disposed at a height of h / 2, and further the center of the detection surface (12a) of the magnetoresistive element (12). The position (12b) is arranged so as to coincide with the center position (41) of the plane parallel to the first upper surface (24) in the accommodation space (4) in the direction perpendicular to the first upper surface (24). The magnetic shield for a current sensor according to claim 1 or 2, wherein the magnetic shield is combined.   The said 1st flat member (23), the said 2nd flat plate member (26), and the said 3rd flat plate member (32) are each comprised by the thin plate, The any one of Claim 1 thru | or 3 characterized by the above-mentioned. The magnetic shield body for current sensors as described in any one.   Of the first side surface (25a, 25b) and the second side surface (28a, 28b), the side surface adjacent to the third upper surface (33) is the first upper surface (24) and the second upper surface (27). A part of the opposite end has a protrusion (29) extending in a direction away from the first upper surface (24) and the second upper surface (27). 5. A magnetic shield for a current sensor according to any one of items 4 to 4.   The said 1st magnetic shield part (20) and the said 2nd magnetic shield part (30) are mutually arrange | positioned through the space | gap (40), The one of Claim 1 thru | or 5 characterized by the above-mentioned. Magnetic shield for current sensors.   The first side surface (25a, 25b), the second side surface (28a, 28b), and the third side surface (34a, 34b) are arranged with the gap (40) therebetween. The magnetic shield for a current sensor according to claim 6. In the first magnetic shield part (20), the number of the first plate parts (21) is determined according to the strength of the magnetic field received by the magnetoresistive element (12), and the second plate part (22). ) Is determined,
The number of the third plate portions (31) of the second magnetic shield portion (30) is determined according to the strength of the magnetic field received by the magnetoresistive element (12). 8. A magnetic shield for a current sensor according to any one of 7 above.

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