WO2016017333A1

WO2016017333A1 - Magnetic shield and method of producing same

Info

Publication number: WO2016017333A1
Application number: PCT/JP2015/068425
Authority: WO
Inventors: 達之山口
Original assignee: 株式会社東海理化電機製作所
Priority date: 2014-07-29
Filing date: 2015-06-25
Publication date: 2016-02-04
Also published as: JP2016031293A

Abstract

Provided are a low-cost magnetic shield having excellent dimensional accuracy and a method of producing the same. A magnetic shield (40) is provided with a shield part (42, 43) surrounding a current path (20) through which current flows and a magnetic detection element (30) for detecting the current flowing through the current path (20). The shield part (42, 43) has at least two laminated magnetic plate members (41), a bent portion (44) at which the laminated magnetic plate members (41) are bent, and a crimped portion (45) where a prescribed location of the bent portion (44) is crimped as a whole through plastic deformation.

Description

Magnetic shield and manufacturing method thereof

The present invention relates to a magnetic shield and a manufacturing method thereof, and more particularly, to a magnetic shield used in a current sensor for detecting a current flowing in a conductor and a manufacturing method thereof.

2. Description of the Related Art A current sensor that detects a current flowing through a conductor by measuring a magnetic flux generated by a current flowing through the conductor is known (see, for example, Patent Documents 1 and 2).

The current sensors disclosed in Patent Documents 1 and 2 include an annular core (magnetic shield) having a gap on one side. The core is made of a grain-oriented electrical steel sheet having an easy axis of magnetization in a certain direction. A conductor such as a conductive wire or a bus bar is inserted in the hollow portion of the core, and the detection element is arranged in the gap of the core, thereby detecting a magnetic flux change generated in the core as a current. Yes.

The core (magnetic shield) used in the current sensor disclosed in Patent Document 1 is manufactured by the following manufacturing processes (1) to (4).

(1) A step of extracting the first core member having concave and convex attachment portions at four corners by pressing,
(2) A step of extracting the second core member having uneven mounting portions at four corners by pressing,
(3) By pressing the second core member into the previously extracted first core member, the convex portion of the mounting portion of the second core member is press-fitted into the concave portion of the mounting portion of the first core member. A step of joining the first core member and the second core member, and (4) repeating the steps (1) to (3) above, thereby combining the first core member and the second core member. Lamination process.

On the other hand, the core (magnetic shield) used in the current sensor disclosed in Patent Document 2 is manufactured by the following manufacturing processes (5) to (10).

(5) A step of laminating a core-shaped sheet-like directional electrical steel sheet by winding it in an annular shape,
(6) a step of spot welding to a predetermined portion of the laminated grain-oriented electrical steel sheet;
(7) A step of forming a laminated core wound in an annular shape by taking out the core rod,
(8) Annealing the annular laminated core,
(9) impregnating the annular laminated core with an adhesive and fixing it by drying; and (10) dividing the fixed annular laminated core into two.

JP 2011-43422 A JP 2013-148513 A

The manufacturing method of the core used for the current sensor disclosed in Patent Document 1 is formed by forming a concave and convex mounting portion on each of the directional electromagnetic steel sheets, and superimposing multiple directional electromagnetic steel sheets. Unless the steps (1) to (3) for forming the core shape are repeated, the core cannot be mass-produced. Therefore, production efficiency is low.

On the other hand, in the manufacturing method of the core used for the current sensor disclosed in Patent Document 2, the dimensional accuracy of the inner and outer diameters of the laminated core wound in an annular shape varies, and the amount of product obtained in a single process is also large. Few. Therefore, the dimensional accuracy is low and the production efficiency is low.

An object of the present invention is to provide a magnetic shield that is low in cost and excellent in dimensional accuracy, and a method for manufacturing the same.

[1] A magnetic shield according to an embodiment of the present invention includes a shield part that surrounds a current path through which a current flows and a magnetic detection element that detects a current flowing through the current path, and the shield part includes at least two magnetic elements. A plate material is laminated, a bending portion where the laminated magnetic plate material is bent, and a caulking portion that is caulked together by plastic deformation of predetermined portions of the bending portion.

[2] The bending portion according to [1] includes two opposing side wall portions and a connecting wall portion that connects the two side wall portions.

[3] The caulking portion according to [1] or [2] is caulked in a lump by plastically deforming predetermined portions of both edge portions of the bent portion.
[4] The caulking portion according to [2] is formed at at least three locations including two locations on the two sidewall portions and one location on the connecting wall portion at one end in the width direction of the sidewall portion. .
[5] The caulking portion according to [1] to [4] includes a plastic deformation structure formed in a direction orthogonal to the stacking direction of the magnetic plate members.
[6] The caulking portion according to [1] to [4] includes a plastic deformation structure formed in a direction along the stacking direction of the magnetic plate members.

[7] A method of manufacturing a magnetic shield according to an embodiment of the present invention includes a step of laminating at least two long belt-like magnetic plates, and bending a plurality of bent portions along the longitudinal direction of the laminated magnetic plates. And a step of collectively caulking predetermined portions of the plurality of bent portions, and a step of cutting the plurality of bent portions into a predetermined length.

According to an embodiment of the present invention, it is possible to provide a magnetic shield with excellent dimensional accuracy at low cost and a method for manufacturing the magnetic shield.

FIG. 1 is an explanatory diagram showing a current sensor including a magnetic shield according to a first embodiment suitable for the present invention. FIG. 2 is a perspective view showing the magnetic shield according to the first embodiment. FIG. 3A is an explanatory diagram illustrating the method of manufacturing the magnetic shield according to the first embodiment. FIG. 3B is an explanatory diagram illustrating the method of manufacturing the magnetic shield according to the first embodiment. FIG. 3C is an explanatory view showing the method of manufacturing the magnetic shield according to the first embodiment. FIG. 3D is an explanatory view showing the method of manufacturing the magnetic shield according to the first embodiment. FIG. 3E is an explanatory view showing the method of manufacturing the magnetic shield according to the first embodiment. FIG. 4A is a perspective view showing a magnetic shield according to the second embodiment. FIG. 4B is an enlarged perspective view showing a caulking portion of the magnetic shield. FIG. 5 is a perspective view showing a magnetic shield according to the third embodiment. FIG. 6 is a perspective view showing a magnetic shield according to the fourth embodiment.

Preferred embodiments of the present invention will be specifically described below with reference to the accompanying drawings.

[First Embodiment]
(Configuration of current sensor)
In FIG. 1, reference numeral 10 generally indicates a current sensor having a typical magnetic shield in the first embodiment. The current sensor 10 is used to detect the magnitude of a current flowing through a drive motor and an external device such as a battery in a hybrid vehicle or an electric vehicle, for example.

As shown in FIG. 1, the current sensor 10 includes a current path 20 such as a bus bar or a cable through which a current flows, a magnetic detection element 30 that detects a magnetic field generated by a current flowing through the current path 20, and the current path 20 and the magnetic detection. And a magnetic shield 40 surrounding the element 30.

As the magnetic detection element 30, for example, a Hall IC in which electronic components such as an amplifier are packaged as an integrated circuit, a packaged magnetoresistive IC, or the like is used. As a material of the magnetic shield 40, for example, a magnetic plate material (hereinafter referred to as “electromagnetic steel plate”) such as a directional electromagnetic steel plate or a non-oriented electromagnetic steel plate made of a silicon steel plate is used.

The magnetic detection element 30 is mounted on a substrate (not shown). The board is provided with a connector having connection terminals electrically connected to a processing circuit for processing the output from the magnetic detection element 30. The connector is electrically connected to an external device such as a control unit (not shown).

As shown in FIGS. 1 and 2, the magnetic shield 40 is used to reduce the influence of a disturbance magnetic field other than a magnetic field due to an electric current. The magnetic shield 40 is formed by stacking at least two electromagnetic steel plates 41 and bending them.

As shown in FIGS. 1 and 2, the magnetic shield 40 includes a substantially U-shaped bent portion 44 in which one side ends of the opposed long strip-like

side wall portions

42, 42 are bent with a connecting wall portion 43. Have. The bending portion 44 is configured as a shield portion of the magnetic shield 40. A caulking portion 45 is formed at a predetermined portion of the edge portion of the bending portion 44, and the electromagnetic steel plates 41 are fixed by the caulking portion 45 so as not to be relatively displaced.

The caulking portion 45 according to the illustrated example is not a caulking portion that fits and press-fits an uneven caulking portion processed on each electromagnetic steel sheet itself. In the first embodiment, the caulking portion 45 is formed by plastically deforming predetermined portions of the edge portions of the laminated electromagnetic steel plates 41 and caulking them together.

As the caulking portion 45, it is preferable that the caulking portion 45 is caulked in a lump by plastically deforming a position closer to the tip of both end edges of the side wall portion 42 of the magnetic shield 40 and an intermediate position between both end edges of the connecting wall portion 43. is there. Predetermined portions of these edge portions have a substantially wedge-shaped cross-sectional shape that narrows toward the inside of the plate thickness.

(Magnetic shield manufacturing method)
The magnetic shield 40 configured as described above is efficiently manufactured by the following manufacturing method. As shown in FIGS. 3A to 3E, the method of manufacturing the magnetic shield 40 includes a step of laminating the three long belt-like electromagnetic steel plates 41,..., 41, and bending the laminated electromagnetic steel plates 41 into a wave shape. This is effectively achieved by a series of steps including a step, a step of caulking each of the bent electromagnetic steel plates 41, and a step of cutting each of the bent electromagnetic steel plates 41.

(Lamination process)
In manufacturing the magnetic shield 40, first, as shown in FIG. 3A, three long strip-shaped electromagnetic steel plates 41 having a predetermined length and width are overlapped and stacked. The thickness of the magnetic plate made of the three electromagnetic steel plates 41 is, for example, about 1 mm.

(Bending process)
In FIG. 3B, the laminated long strip-shaped electromagnetic steel plates 41 are bent into a wave shape over the longitudinal direction by an upper mold and a lower mold (not shown). As a result, a plurality of substantially U-shaped bent portions 44 are formed in which one side ends of the opposed long belt-like side wall portions 42 are bent by the connecting wall portions 43.

(Caulking process)
In FIG. 3C, by pressing the positions closer to the tips of both end edges of the side wall part 42 and the intermediate positions of both end edges of the connecting wall part 43 in each bending part 44 and plastically deforming, Three electromagnetic steel plates 41 are fixed integrally. Thereby, the three electromagnetic steel plates 41 ensure an integral shape.

In the caulking process, as shown in FIG. 3D, the steel plate lamination end surface of each bending portion 44 is pressed from a substantially horizontal direction by the pressing surface 51 of the caulking jig 50. By making the pressing surface 51 corresponding to the connecting wall portion 43 in the caulking jig 50 into an oblique structure, the steel plate end face is plastically deformed inward in the vertical direction by pressing the caulking jig 50 from the horizontal direction. A crimped caulking portion 45 is formed.

(Cutting process)
In FIG. 3E, the electromagnetic steel sheet 41 is separated into a large number of bending parts 44 by cutting the side wall part 42 of each bending part 44 into a predetermined length along the cutting line CL. As necessary, the cut bending portion 44 is subjected to an annealing treatment. By annealing, the distortion in the electromagnetic steel sheet 41 is removed, the magnetic characteristics are stabilized, and the shape of the bending portion 44 is corrected.

When the laminated long strip-shaped electromagnetic steel sheet 41 is bent into a wave shape, a position closer to the tip of both end edges of the side wall 42 in the bent portion 44 and an intermediate position between both end edges of the connecting wall 43 are set. Of course, they can be caulked together. Since the laminated bending portions 44 are caulked together, the electromagnetic steel plates 41 are not separated from each other when the laminated long strip-like electromagnetic steel plates 41 are folded back. It can prevent that a clearance gap arises in a steel plate lamination | stacking end surface.

Through the above steps, a large number of bending portions 44 of the electromagnetic steel sheet 41 can be obtained in a single manufacturing process. Accordingly, a large number of independent magnetic shields 40 can be efficiently manufactured.

(Effects of the first embodiment)
By adopting the magnetic shield 40 configured as described above, the following effects can be obtained in addition to the above effects.

(1) Since a predetermined portion of a large number of laminated electromagnetic steel sheets 41 is plastically deformed and caulked, it is magnetic compared to a magnetic shield that caulks an ordinary uneven caulking portion formed on each of the electromagnetic steel sheets. The magnetic shield 40 with excellent performance can be provided.
(2) The arrangement position of the caulking portion 45 is set at the edge of the electromagnetic steel plate 41, and the caulking portion 45 is not arranged on the shortest path forming the magnetic circuit, thereby reducing the influence on the magnetic performance. be able to.
(3) Compared with the case where it fixes by welding, welding, etc., many electromagnetic steel plates 41 can be firmly fixed at low cost with few man-hours.
(4) Since the effect of correcting the shield shape is also obtained by plastically deforming predetermined portions of the electromagnetic steel sheet 41 and collectively caulking, the magnetic shield 40 with good dimensional accuracy can be obtained.
(5) An inexpensive magnetic shield 40 can be obtained that can be manufactured in the process of conveying the electromagnetic steel sheet 41.

[Second Embodiment]
4A and 4B schematically illustrate a configuration example of the magnetic shield 40 according to the second embodiment.

(Magnetic shield structure)
In the first embodiment, the caulking portion 45 is formed on the edge portion of the magnetic shield 40. In the second embodiment, the inner surface of the edge portion of the magnetic shield 40 is used. This is different from the first embodiment in that the caulking portion 45 is formed. Therefore, by using the same member code as the member code used in the first embodiment, detailed description about the member is omitted.

The caulking portion 45 formed on the inner surface of the edge portion of the magnetic shield 40 can be formed at the same time as the laminated strip-shaped electromagnetic steel sheet 41 is bent into a wave shape over the longitudinal direction. The caulking portion 45 is formed at a position closer to the tip of the inner surface of both ends of the side wall portion 42 of the magnetic shield 40 and an intermediate position of the inner surface of both ends of the connecting wall portion 43. It has a concave cross-sectional shape toward the thickness direction.

(Effect of the second embodiment)
Even in the magnetic shield 40 according to the second embodiment, a large number of electromagnetic steel plates 41 can be closely joined by caulking by plastic deformation.

[Third Embodiment]
FIG. 5 schematically illustrates a configuration example of the magnetic shield 40 according to the third embodiment.

(Magnetic shield structure)
In the third embodiment, except for the configuration in which the caulking pieces 46 are formed at both end edges of the magnetic shield 40, the other configurations have substantially the same configurations as the above embodiments. Yes. Therefore, by using the same member code as the member code used in each of the above embodiments, a detailed description of the member is omitted.

The caulking pieces 46 are formed at both end edges near the tip of the side wall 42 of the magnetic shield 40 corresponding to the innermost electromagnetic steel plate 41 and both end edges of the connecting wall 43. The caulking piece 46 is formed by punching out the electromagnetic steel plates 41 laminated and arranged at the bottom of the three electromagnetic steel plates 41. A jig is applied to the caulking piece 46, and the caulking piece 46 is pressed inward so as to be plastically deformed, and the magnetic shield 40 is caulked and fixed together.

(Effect of the third embodiment)
Even in the magnetic shield 40 according to the third embodiment, a large number of electromagnetic steel plates 41 can be closely joined by caulking by plastic deformation.

[Fourth Embodiment]
FIG. 6 schematically illustrates a configuration example of the magnetic shield 40 according to the fourth embodiment.

(Magnetic shield structure)
In the fourth embodiment, except for the configuration in which the caulking holes 47 are formed through the inner surfaces of both ends of the magnetic shield 40, the other configurations are substantially the same as those in the above embodiments. It has the composition of. Therefore, by using the same member code as the member code used in each of the above embodiments, a detailed description of the member is omitted.

In the fourth embodiment, the caulking hole 47 and the rivet 48 are configured as caulking portions. In the magnetic shield 40, caulking holes 47 are formed penetrating at positions closer to the tips of the inner surfaces of both end edges of the side wall 42 and intermediate positions of the inner surfaces of both end edges of the connecting wall 43. Three electromagnetic steel plates 41 each having a caulking hole 47 are stacked on top of each other, a shaft portion of a rivet 48 is inserted into each caulking hole 47, and a tip portion of the shaft portion is crushed to form three sheets. The electromagnetic steel plates 41 are fixed together by rivet caulking.

(Effect of the fourth embodiment)
Even in the magnetic shield 40 according to the fourth embodiment, a large number of electromagnetic steel plates 41 can be closely joined by caulking by plastic deformation.

[Modification]
The magnetic shield 40 according to the present invention can be modified as follows.

The magnetic shield 40 can be applied to a core that collects magnetic flux generated by the current flowing through the current path 20.

What is necessary is just to select suitably the board | plate space | interval of the side wall part 42 of the magnetic shield 40, the space | interval of the magnetic detection element 30 and the magnetic shield 40, etc. according to the specification of the magnetic detection element 30.

The arrangement position, the arrangement number, the shape, and the like of the caulking portion of the magnetic shield 40 can be appropriately selected according to the magnetic performance, strength, and the like of the magnetic shield 40.

The present invention can be applied to electric circuits other than electric circuits connected to vehicle motors and batteries.

As is clear from the above description, each of the exemplary embodiments, modifications, and illustrations according to the present invention has been illustrated. However, the above-described embodiments, modifications, and illustrations relate to the claims. The invention is not limited. Therefore, it should be noted that not all the combinations of features described in the above embodiments, modifications, and illustrated examples are essential to the means for solving the problems of the present invention.

The present invention can be applied to a drive motor used in a hybrid vehicle or an electric vehicle, and a current sensor having a magnetic detection element for detecting a current flowing in a battery.

DESCRIPTION OF SYMBOLS 10 Current sensor 20 Current path 30 Magnetic detection element 40 Magnetic shield 41 Electrical steel plate 42 Side wall part 43 Connection wall part 44 Bending part 45 Caulking part

Claims

A shield portion surrounding a current path through which a current flows and a magnetic detection element that detects a current flowing through the current path;
The shield portion is formed by laminating at least two magnetic plate materials, and bending the laminated magnetic plate material and bending the predetermined portions of the bent portion by plastic deformation. A magnetic shield having a caulking portion.
2. The magnetic shield according to claim 1, wherein the bending portion includes two opposing side wall portions and a connecting wall portion connecting the two side wall portions.
3. The magnetic shield according to claim 1, wherein the caulking portion is caulked in a lump by plastically deforming predetermined portions of both end edges of the bending portion.
3. The magnetism according to claim 2, wherein the caulking portion is formed at at least three locations including two locations on the two sidewall portions and one location on the connecting wall portion at one end in the width direction of the sidewall portion. shield.
The magnetic shield according to any one of claims 1 to 4, wherein the caulking portion includes a plastic deformation structure formed in a direction orthogonal to a stacking direction of the magnetic plate members.
The magnetic shield according to any one of claims 1 to 4, wherein the caulking portion includes a plastic deformation structure formed in a direction along a stacking direction of the magnetic plate members.
Laminating at least two long strip-shaped magnetic plates; and
A step of bending a plurality of bent portions along the longitudinal direction of the laminated magnetic plates; and
A step of collectively caulking predetermined portions of the plurality of bent portions;
Cutting the plurality of bent portions into a predetermined length.