JP2021001831A - Current sensor and manufacturing method therefor - Google Patents

Abstract

To provide a current sensor having such a structure that a magnetic sensor is hardly saturated.SOLUTION: A current sensor 1 comprises a bus bar 10, and a magnetic sensor 20 for detecting a magnetic field generated by a current flowing in the bus bar 10. The bus bar 10 includes bent parts A1, A2 extending in a direction z, a sensing part 13, a bypass part 11 covering the sensing part 13 from a direction +y, and a bypass part 11 covering the sensing part 13 from a direction -y. The bypass parts 11, 12 constitute a cylindrical structure for accommodating the sensing part 13, and the magnetic sensor 20 is arranged in a hollow area 10a of the cylindrical structure. According to this, a null-magnetic-field area is formed in the hollow area 10a. Thus, as the sensing part 13 and the magnetic sensor 20 are arranged in this hollow area 10a, the magnetic sensor 20 is capable of measuring correctly without being saturated even when the current flowing in the bus bar 10 is a large current.SELECTED DRAWING: Figure 1

Description

The present invention relates to a current sensor and a method for manufacturing the same, and more particularly to a current sensor using a magnetic sensor and a method for manufacturing the same.

As a current sensor using a magnetic sensor, the current sensors described in Patent Documents 1 and 2 are known. The current sensor described in Patent Document 1 discloses a configuration in which a bus bar is provided with a current path in which a current to be measured flows in one direction and a current path in which the current flows in the opposite direction, and a magnetic sensor is arranged between them. .. Further, Patent Document 2 discloses a current sensor in which a bus bar is branched into two and a magnetic sensor is assigned to each current path.

Japanese Patent No. 5971398 International Publication No. 2017/018306 Pamphlet

However, in the current sensor described in Patent Document 1, since the magnetic field generated from one current path and the magnetic field generated from the other current path strengthen each other, the magnetic sensor is saturated when the current amount of the current to be measured is large. There was a problem of doing it. Further, since the current sensor described in Patent Document 2 has the bus bar branched into two, the strength of the magnetic field applied to each magnetic sensor is suppressed to 1/2. However, even in this case, if the amount of current to be measured is very large, the magnetic sensor is easily saturated.

Therefore, an object of the present invention is to provide a current sensor having a structure in which the magnetic sensor is less likely to be saturated even when the amount of current flowing through the bus bar is very large, and a method for manufacturing the same.

The current sensor according to the present invention includes a bus bar through which a current to be measured flows and a magnetic sensor that detects a magnetic field generated by the current flowing through the bus bar, and the bus bar extends in the first direction in which the current flows. A second bent portion, a sensing portion located between the first and second bent portions, a first bypass portion connected to the sensing portion via the first bent portion, and a second bent portion. The first bypass portion covers the sensing portion from one side in the second direction orthogonal to the first direction, and includes the second bypass portion connected to the sensing portion via the second bypass portion. Covers the sensing section from the other side in the second direction, whereby the first and second bypass sections form a tubular structure that houses the sensing section, and the magnetic sensor is a hollow region of the tubular structure. It is characterized by being arranged in.

According to the present invention, since the first and second bypass portions have a tubular structure, a region having a zero magnetic field is formed in the hollow region. Since the sensing unit and the magnetic sensor are arranged in this hollow region, even if the current flowing through the bus bar is a large current, the magnetic sensor can be accurately measured without being saturated. Moreover, since the sensing portion is connected to the first and second bypass portions via the first and second bent portions, the bus bar is manufactured by bending one flat metal plate. It becomes possible to do.

In the present invention, the cross-sectional shape of the inner wall of the tubular structure may be circular. According to this, it is possible to make almost the entire hollow region a zero magnetic field.

In the present invention, the bus bar may be provided with slits along the first and second bent portions. According to this, the bending process becomes easy, and the diversion ratio between the sensing portion and the first and second bypass portions can be fixed to a desired value.

In the present invention, the sensing unit is divided in the first direction, and the magnetic sensor may be integrated in a detection module that electrically connects the divided portions of the sensing unit. According to this, the diversion ratio between the sensing unit and the first and second bypass units can be adjusted by the detection module.

The method for manufacturing a current sensor according to the present invention is a sensing unit located between the first and second bent portions extending in the first direction in which the current to be measured flows and the first and second bent portions. And the first bypass portion located on the side opposite to the sensing portion with respect to the first bent portion, and the second bypass portion located on the side opposite to the sensing portion with reference to the second bent portion. A step of preparing a flat plate-shaped bus bar to have, a step of mounting a magnetic sensor for detecting a magnetic field generated by a current flowing through the bus bar on the sensing section, and a tubular structure in which the first and second bypass sections accommodate the sensing section. By bending the bus bar along the first bent portion so as to form the above, the first bypass portion covers the sensing portion from one side in the second direction orthogonal to the first direction, and the second bent portion. It is characterized by comprising a step of covering the sensing portion from the other side in the second direction by the second bypass portion by bending the bus bar along the above.

According to the present invention, the sensing portion and the magnetic sensor can be arranged in the hollow region of the tubular structure including the first and second bypass portions by bending one flat metal plate. It will be possible.

As described above, according to the present invention, it is possible to provide a current sensor having a structure in which the magnetic sensor is less likely to be saturated even when the amount of current flowing through the bus bar is very large, and a method for manufacturing the same.

FIG. 1 is a schematic perspective view showing the appearance of the current sensor 1 according to the first embodiment of the present invention. FIG. 2 is a schematic side view of the current sensor 1 as viewed from the z direction. FIG. 3 is a schematic plan view of the sensing unit 13. FIG. 4 is a schematic cross-sectional view taken along the line BB shown in FIG. FIG. 5 is a schematic plan view of the bus bar 10 before the bending process. FIG. 6 is a schematic cross-sectional view taken along the line CC shown in FIG. FIG. 7 is a schematic perspective view showing a state of the current sensor 2 before bending according to the second embodiment of the present invention. FIG. 8 is a schematic cross-sectional view for explaining the structure of the detection module M.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a schematic perspective view showing the appearance of the current sensor 1 according to the first embodiment of the present invention. Further, FIG. 2 is a schematic side view of the current sensor 1 as viewed from the z direction.

As shown in FIGS. 1 and 2, the current sensor 1 according to the first embodiment has a bus bar 10 through which a current I to be measured flows and a magnetic sensor 20. The bus bar 10 includes bypass portions 11 and 12 constituting a tubular structure, and sensing portions 13 arranged in a hollow region 10a surrounded by the bypass portions 11 and 12. The bypass unit 11 covers the sensing unit 13 from the + y direction, and the bypass unit 12 covers the sensing unit 13 from the −y direction.

The bus bar 10 is composed of a good conductor such as copper or aluminum and an insulating film covering the surface thereof. In the present embodiment, the inner and outer diameters of the tubular structure including the bypass portions 11 and 12 are substantially perfect circles. The bypass units 11 and 12 and the sensing unit 13 are integrated, the bypass unit 11 and the sensing unit 13 are connected via a bent portion A1 extending in the z direction, and the bypass unit 12 and the sensing unit 13 extend in the z direction. It is connected via the existing bent portion A2. As a result, a part of the current I flowing through the bus bar 10 flows through the bypass portions 11 and 12, and the remaining portion of the current I flows through the sensing unit 13. In the present embodiment, the cross-sectional area of the bypass portions 11 and 12 is sufficiently larger than the cross-sectional area of the sensing portion 13, whereby most of the current I flowing through the bus bar 10 flows through the bypass portions 11 and 12.

FIG. 3 is a schematic plan view of the sensing unit 13, and FIG. 4 is a schematic cross-sectional view taken along the line BB shown in FIG.

As shown in FIGS. 3 and 4, the sensing unit 13 is provided with a slit 13a extending in the x direction, and the magnetic sensor 20 is mounted so as to overlap the slit 13a. The type of the magnetic sensor 20 is not particularly limited, but a Hall element, a magnetoresistive element, or the like can be used. Further, the sensing unit 13 is provided with a plurality of (four in this example) wirings 30 via an insulating film, and each wiring 30 is connected to the magnetic sensor 20. As an example, two of the four wires 30 are power supply wires, and the remaining two wires are signal wires.

The width of the sensing unit 13 in the x direction is narrowed at the portion where the slit 13a is provided, and the magnetic field generated by the current flowing through the narrow portion 13b is applied to the magnetic sensor 20. That is, when a part of the current I to be measured flows in the narrow portion 13b in the z direction, a magnetic field φ is generated around the narrow portion 13b according to the right-handed screw rule. Since the magnetic field φ has a y-direction component with respect to the magnetic sensor 20, the strength of the magnetic field φ can be detected by setting the magnetic sensing direction of the magnetic sensor 20 in the y direction. The signal obtained by detecting the magnetic field φ is output to the outside via the wiring 30 and converted into the current value of the current I. Here, the ratio of the current I to be measured that flows through the narrow portion 13b can be adjusted by the width of the slit 13a in the x direction.

In the present embodiment, the inner and outer diameters of the tubular structure composed of the bypass portions 11 and 12 are substantially perfect circles, and the wall thickness thereof is also substantially constant in the circumferential direction. Therefore, the current densities of the currents flowing in the tubular structure including the bypass portions 11 and 12 in the z direction are substantially equal in the circumferential direction. As a result, in the hollow region 10a surrounded by the tubular structure, the magnetic field generated by the current flowing through the bypass portions 11 and 12 is almost completely canceled. That is, the hollow region 10a is a zero magnetic field region in which there is almost no magnetic field caused by the current flowing through the bypass portions 11 and 12.

In the current sensor 1 according to the present embodiment, since the sensing unit 13 and the magnetic sensor 20 are arranged in such a hollow region 10a, the magnetic field applied to the magnetic sensor 20 is substantially the sensing unit. Only the magnetic field caused by the current flowing through 13. As a result, the magnetic sensor 20 can selectively detect the magnetic field generated by the current flowing through the sensing unit 13.

FIG. 5 is a schematic plan view of the bus bar 10 before bending, and FIG. 6 is a schematic cross-sectional view taken along the line CC shown in FIG.

As shown in FIGS. 5 and 6, the bus bar 10 before the bending process is composed of a flat metal plate 14 and an insulating film 15 formed on the surface thereof. A plurality of wirings 30 are formed on the surface of the insulating film 15. Bending portions A1 and A2 extending in the z direction are defined in the bus bar 10 before the bending process, and the region sandwiched between the bending portions A1 and A2 is the sensing portion 13, and the sensing portion A1 is used as a reference for sensing. The portion located on the opposite side of the portion 13 is the bypass portion 11, and the portion located on the opposite side of the sensing portion 13 with respect to the bent portion A2 is the bypass portion 12.

In the present embodiment, slits SL1 and SL2 are provided along the bent portions A1 and A2. In the present invention, it is not essential to provide such slits SL1 and SL2, but by providing the slits SL1 and SL2, the bus bar 10 can be easily bent and the distribution ratio of the sensing portion 13 and the bypass portions 11 and 12 is divided. Can be fixed at a desired value.

The bus bar 10 having such a structure can be produced by processing a plate-like body having a structure in which the insulating film 15 and the metal film 16 are laminated on the surface of the metal plate 14. For example, it can be produced by forming a plurality of wirings 30 by patterning the metal film 16 and then processing the bus bar 10 into a planar shape shown in FIG. 5 by punching. Then, after mounting the magnetic sensor 20 at a predetermined position of the sensing unit 13, the bus bar 10 is bent along the bent portion A1 to cover the sensing portion 13 from the + y direction by the bypass portion 11 and the bent portion A2. By bending the bus bar 10 along the line and covering the sensing unit 13 from the −y direction with the bypass unit 12, the current sensor 1 according to the present embodiment is completed.

As described above, in the current sensor 1 according to the present embodiment, since the sensing unit 13 and the magnetic sensor 20 are arranged in the hollow region 10a of the tubular structure including the bypass units 11 and 12, the magnetic sensor 20 Can selectively detect only the magnetic field generated by the sensing unit 13. As a result, even if the current I flowing through the bus bar 10 is a large current, the magnetic field strength applied to the magnetic sensor 20 is significantly suppressed, so that saturation of the magnetic sensor 20 can be prevented.

Moreover, in the present embodiment, since the bus bar 10 can be manufactured by bending a flat metal plate, the number of parts can be reduced and the measurement error due to manufacturing variation can be reduced.

FIG. 7 is a schematic perspective view showing a state of the current sensor 2 before bending according to the second embodiment of the present invention.

As shown in FIG. 7, the current sensor 2 according to the second embodiment is different from the current sensor 1 according to the first embodiment in that the sensing unit 13 is divided in the z direction by the slit 13c. In the present embodiment, since the sensing unit 13 is divided in the z direction, no current flows through the sensing unit 13 as it is, but by mounting the detection module M so as to straddle the slit 13c, the sensing unit 13 Current flows through. As shown in FIG. 8, the detection module M has a metal layer 21 for electrically connecting the divided portions of the sensing unit 13 and a circuit board 22 fixed to the metal layer 21, and a magnetic sensor is attached to the circuit board 22. 20 are accumulated.

In the present embodiment, the distribution ratio of the sensing unit 13 and the bypass units 11 and 12 can be adjusted by the detection module M. That is, since the ratio of the current flowing through the sensing unit 13 changes according to the thickness and width of the metal layer 21, the distribution ratio can be adjusted without changing the design of the bus bar 10.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the gist of the present invention, and these are also the present invention. It goes without saying that it is included in the range.

For example, in the current sensor 1 according to the above embodiment, the inner diameter and outer diameter of the tubular structure including the bypass portions 11 and 12 are substantially perfect circles, but the inner diameter and outer diameter of the tubular structure are substantially perfect circles. Some points are not essential and may be elliptical or polygonal. Further, the hollow region 10a does not have to be completely closed in the xy direction, and may be partially opened.

1, 2 Current sensor 10 Bus bar 10a Hollow region 11, 12 Bypass 13 Sensing 13a Slit 13b Narrow 13c Slit 14 Metal plate 15 Insulation film 16 Metal film 20 Magnetic sensor 21 Metal layer 22 Circuit board 30 Wiring A1, A2 Bending Part I Current M Detection module SL1, SL2 Slit φ Magnetic field

Claims (5)

The bus bar through which the current to be measured flows,
A magnetic sensor for detecting a magnetic field generated by a current flowing through the bus bar is provided.
The bus bar has a first and second bent portion extending in the first direction in which the current flows, a sensing portion located between the first and second bent portions, and the first bent portion. A first bypass portion connected to the sensing portion via the above, and a second bypass portion connected to the sensing portion via the second bent portion.
The first bypass section covers the sensing section from one side in a second direction orthogonal to the first direction, and the second bypass section covers the sensing section from the other side in the second direction. The first and second bypass portions form a tubular structure that accommodates the sensing portion.
The magnetic sensor is a current sensor characterized in that it is arranged in a hollow region of the tubular structure. The current sensor according to claim 1, wherein the cross-sectional shape of the inner wall of the tubular structure is circular. The current sensor according to claim 1 or 2, wherein the bus bar is provided with slits along the first and second bent portions. The sensing unit is divided in the first direction, and the sensing unit is divided in the first direction.
The current sensor according to any one of claims 1 to 3, wherein the magnetic sensor is integrated in a detection module that electrically connects a divided portion of the sensing unit. The first and second bent portions extending in the first direction in which the current to be measured flows, the sensing portion located between the first and second bent portions, and the first bent portion. A flat plate-shaped bus bar having a first bypass portion located on the side opposite to the sensing portion as a reference and a second bypass portion located on the side opposite to the sensing portion with reference to the second bent portion. And the process of preparing
A process of mounting a magnetic sensor on the sensing unit that detects a magnetic field generated by a current flowing through the bus bar, and
By bending the bus bar along the first bent portion so that the first and second bypass portions form a tubular structure accommodating the sensing portion, the sensing is performed by the first bypass portion. By covering the portion from one side in the second direction orthogonal to the first direction and bending the bus bar along the second bent portion, the sensing portion is caused by the second bypass portion. A method for manufacturing a current sensor, which comprises a step of covering from the other side in the direction of the above.

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