JP2010044025A - Current sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a current sensor that can be miniaturized and prevents leakage of a magnetic field to the outside. <P>SOLUTION: In the current sensor 1, a bus bar 4 and a magnetic sensor 5 provided on a substrate 4 are inserted into an opening 21 of a magnetic shield 2. When current 9 flows in a bus bar 3, a magnetic path 7 is formed through a body 20 and an uneven section 22. Further, in the current sensor 1, a magnetic field 6 having nearly uniform magnetic flux density is formed by the uneven section 22, and the magnetic sensor 5 is disposed in the magnetic field 6 having nearly uniform magnetic flux density, thus measuring an accurate current 9. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a current sensor.

  As a conventional technique, a current sensor including a conductor through which a current flows, a ferromagnetic core formed of a ferromagnetic material and having a gap in a part of a ring, and a Hall element provided in the gap is known. (For example, refer to Patent Document 1).

According to this current sensor, a conductor is inserted in the center of the ring, and a magnetic field due to the current flowing through the conductor acts on the Hall element via the ferromagnetic core, and the Hall element has a Hall voltage based on the strength of the magnetic field. Is output.
JP-A-64-83154

  However, the conventional current sensor requires a large ferromagnetic core in order to obtain a magnetic field having a uniform magnetic flux density, and thus it has been difficult to reduce the size.

  Accordingly, an object of the present invention is to provide a current sensor that can be miniaturized and prevents leakage of a magnetic field to the outside.

(1) In order to achieve the above object, the present invention provides a magnetic path change that is formed in a cylindrical shape and is provided so as to surround a conductor that generates a magnetic field based on a flowing current and changes a magnetic path that is a path of the magnetic field. And the inner wall facing the magnetic path changing portion with a gap, and the changed magnetic path propagates from one end portion to the other end portion formed in a staircase shape. There is provided a current sensor comprising: a magnetic field forming unit that forms a magnetic field having a substantially uniform magnetic flux density; and a magnetic sensor that is provided in the substantially uniform magnetic field and outputs an output signal based on the substantially uniform magnetic field. .

(2) In order to achieve the above object, the present invention provides the current sensor according to (1), wherein the magnetic path changing unit and the magnetic field forming unit are formed of a soft magnetic material.

(3) In order to achieve the above-described object, the magnetic field forming unit according to (1), wherein the distance between the one end and the other end is narrowed as the distance from the conductor increases. A current sensor is provided.

(4) In order to achieve the above object, the present invention provides the current sensor according to (1), wherein the magnetic field forming unit has a gap between the magnetic path conversion unit and the main body.

(5) In order to achieve the above object, the present invention changes the magnetic path that is formed in a cylindrical shape by a soft magnetic material and is provided so as to surround a conductor that generates a magnetic field based on a flowing current, and is a path of the magnetic field. And the magnetic path changing portion that is provided with an interval between the opposing inner walls of the magnetic path changing portion, and the changed magnetic path propagates from one end portion to the other end portion formed in a stepped shape. A magnetic field having a substantially uniform magnetic flux density is formed in the gap, and the gap between the one end and the other end is formed narrower as the magnetic field becomes weaker, and a gap is formed between the main body of the magnetic path conversion section. There is provided a current sensor comprising: a magnetic field forming unit including: a magnetic sensor that is disposed in the substantially uniform magnetic field and outputs an output signal based on the substantially uniform magnetic field.

  According to such an invention, it is possible to reduce the size and prevent leakage of the magnetic field to the outside.

  Hereinafter, embodiments of a current sensor of the present invention will be described in detail with reference to the drawings.

[Embodiment]
(Configuration of current sensor)
FIG. 1 is a schematic diagram of a current sensor according to an embodiment of the present invention. The current sensor 1 detects the intensity of a magnetic field generated by a current flowing through the bus bar 3 with a magnetic sensor, which will be described later, and measures the magnitude of the current by an ECU (Electronic Control Unit) (not shown) based on the output of the magnetic sensor. As shown in FIG. 1, a magnetic shield (magnetic path changing unit) 2, a bus bar (conductor) 3, and a magnetic sensor described later are schematically configured.

  The current is not limited to that flowing through the bus bar 3, and may be configured to measure a current flowing through a conductor such as an electric wire.

(Configuration of magnetic shield)
2 is a cross-sectional view taken along line AA in FIG. 1 according to the embodiment of the present invention. As shown in FIG. 2, the magnetic shield 2 is provided on a main body 20 formed of a soft magnetic material in a cylindrical shape, an opening 21 formed in the main body 20 into which the bus bar 3 is inserted, and an inner wall facing the opening 21. The concavo-convex portion (magnetic field forming portion) 22 and the gap portion 26 formed between the concavo-convex portion 22 and the main body 20 are schematically configured.

  Since the main body 20 has a cylindrical shape as shown in FIGS. 1 and 2, the magnetic field 6 generated by the current 9 flowing through the bus bar 3 can be prevented from leaking to the outside. The main body 20 is configured to be hard to be magnetized by being formed of a soft magnetic material, so that the magnetic path 7 can easily pass through the main body 20.

  The concavo-convex portion 22 is formed of a soft magnetic material similarly to the main body 20, and as shown in FIG. 2, as an example, the first convex portion 23, the second convex portion 24, and the third convex portion 25 Are formed in a step shape so as to be symmetrical, and the distance between the left and right is narrowed in order of increasing distance from the bus bar 3, in other words, in order of increasing strength of the magnetic field 6.

  The concavo-convex portion 22 can form a magnetic field 6 having a substantially uniform magnetic flux density in the region 8 by the first to third convex portions 23 to 25, and can improve the strength of the magnetic field 6 in the region 8. . In addition, the number of the convex parts formed in the uneven | corrugated | grooved part 22 and an interval are not limited above, It can change according to a use.

  The uneven portion 22 has a gap portion 26 between the main body 20. This is provided in order to ensure that the magnetic path 7 of the magnetic field 6 formed by the current 9 flowing through the bus bar 3 passes through the uneven portion 22.

(Bus bar configuration)
As shown in FIG. 1, the bus bar 3 has, for example, a U-shaped portion formed at the center portion by a metal material made of copper or a copper alloy, and attachment portions 30 are formed at both ends thereof.

  As an example, the mounting portion 30 is provided with a screw hole 31 into which a screw (not shown) is inserted, and is fixed to the substrate (not shown) having an electronic circuit through which the current 9 to be measured flows through the screw. The

  As an example, the bus bar 3 is configured such that a current 9 flows through the bus bar 3 via an electronic circuit of the substrate and a screw when the bus bar 3 is attached to the substrate or the like.

  The current 9 flowing through the bus bar 3 generates a magnetic field 6 in the direction of the right-handed screw in the traveling direction, that is, the direction from the front side to the back side in FIG. 2, and forms the magnetic path 7 shown in FIG.

(Configuration of magnetic sensor)
As shown in FIG. 2, the magnetic sensor 5 is provided on a substrate 4 having an electronic circuit (not shown). Further, the magnetic sensor 5 is inserted into the opening 21 in the main body 20 together with the bus bar 3 and the substrate 4, and as an example, the opening 21 is sealed with a resin member. Further, the magnetic sensor 5 is arranged such that a surface for sensing the magnetic field 6 is inserted in an interval formed by the first to third convex portions 23 to 25 of the left and right concave and convex portions 22.

  3 is a cross-sectional view taken along line AA of FIG. 1 when the arrangement of the magnetic sensor according to the embodiment of the present invention is changed.

  The magnetic sensor 5 is, for example, a magnetic field sensitive sensor configured using a Hall element, a magnetoresistive element, a giant magnetoresistive effect element, or the like, and outputs an output signal based on a change in the magnetic field 6 from the parallel direction. The magnetic sensor 5 that is arranged on the substrate 4 so that the surface that senses the magnetic field 6 is parallel to the magnetic field 6, and outputs an output signal based on the change of the magnetic field 6 from the vertical direction. As shown in FIG. 3, the surface for sensing 6 is arranged upright on the substrate 4 so as to be perpendicular to the magnetic field 6. For example, as shown in FIG. 3, the magnetic sensor 5 configured by a Hall element needs to have a surface that senses the magnetic field 6 perpendicular to the magnetic field 6 that leaks from the uneven portion 22. It is arranged to stand.

(Operation)
Hereinafter, the operation of the current sensor in the present embodiment will be described in detail with reference to the drawings.

  When the current 9 to be measured flows through the bus bar 3, the current sensor 1 generates the magnetic field 6 shown in FIG.

  As shown in FIG. 2, the magnetic field 6 generated around the bus bar 3 leaks from the right uneven portion 22 through the inside of the main body 20, is sucked into the left uneven portion 22, and returns to the inside of the main body 20. A magnetic path 7 is formed.

  Specifically, the magnetic field 6 leaking from the first convex portion 23 on the left side is sucked into the first convex portion 23 on the right side and leaked from the second convex portion 24 on the left side. Is sucked into the second convex portion 24 on the right side, and the magnetic field 6 leaking from the third convex portion 25 on the left side is sucked into the third convex portion 25 on the right side.

  Since the uneven portion 22 changes the interval between the convex portions by the strength of the magnetic field 6, the magnetic field 6 in the region 8 shown in FIG. 2 is a magnetic field having a substantially uniform magnetic flux density.

  The magnetic sensor 5 is disposed in a magnetic field having a substantially uniform magnetic flux density, that is, the magnetic sensor 5 is disposed so that the detection region is a region 8 in which a magnetic field having a substantially uniform magnetic flux density is formed. The output signal can be output to the ECU, and the ECU can measure the magnitude of the current 9 based on the output signal.

(effect)
(1) According to the current sensor 1 in the above-described embodiment, the magnetic field 6 having a substantially uniform magnetic flux density can be formed in the detection region of the magnetic sensor 5 by the uneven portion 22, so that an accurate current 9 is measured. be able to.

(2) According to the current sensor 1 in the above-described embodiment, the main body 20 and the uneven portion 22 are formed of a soft magnetic material and are not easily magnetized by the magnetic field 6 formed by the bus bar 3. A magnetic path 7 via 22 is formed.

(3) According to the current sensor 1 in the above-described embodiment, the concave and convex portion 22 changes the interval between the convex portion and the convex portion according to the place where the strength of the magnetic field 6 is weakened. A magnetic field 6 having a substantially uniform density can be formed.

(4) According to the current sensor 1 in the above-described embodiment, since the gap portion 26 is provided between the concavo-convex portion 22 and the main body 20, the concavo-convex portion is surely secured without the magnetic path 7 being closed inside the main body 20. As a result, the magnetic field 6 having a substantially uniform magnetic flux density can be formed in the region 8.

(5) According to the current sensor 1 in the above-described embodiment, since the conventional core is not required, the size can be reduced.

(6) According to the current sensor 1 in the above-described embodiment, leakage of the magnetic field 6 to the outside can be prevented, so that a plurality of current sensors 1 can be disposed adjacent to each other.

(7) According to the current sensor 1 in the above-described embodiment, the intensity of the magnetic field 6 in the region 8 is also improved by the concavo-convex portion 22, so that a more accurate current 9 can be measured.

(8) According to the current sensor 1 in the above-described embodiment, the magnetic field 6 having a substantially uniform magnetic flux density can be freely formed by the concavo-convex portion 22, so the degree of freedom increases in the arrangement of the magnetic sensor 5 and the design. Becomes easier.

  The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from or changing the technical idea of the present invention.

It is the schematic of the current sensor which concerns on embodiment of this invention. It is the sectional view on the AA line in FIG. 1 which concerns on embodiment of this invention. It is the sectional view on the AA line of FIG. 1 at the time of changing arrangement | positioning of the magnetic sensor which concerns on embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Current sensor, 2 ... Magnetic shield, 3 ... Bus bar, 4 ... Board | substrate, 5 ... Magnetic sensor, 6 ... Magnetic field, 7 ... Magnetic path, 8 ... Area | region, 9 ... Current, 20 ... Main body, 21 ... Opening, 22 ... Concavity and convexity, 23 ... first convex part, 24 ... second convex part, 25 ... third convex part, 26 ... gap part, 30 ... attachment part, 31 ... screw hole

Claims (5)

A magnetic path changing unit that is formed in a cylindrical shape and is provided so as to surround a conductor that generates a magnetic field based on a flowing current, and changes a magnetic path that is a path of the magnetic field;
A magnetic flux density is provided in the interval by providing an interval between the opposite inner walls of the magnetic path changing portion and propagating the changed magnetic path from one end portion to the other end portion formed stepwise. A magnetic field forming part for forming a substantially uniform magnetic field;
A magnetic sensor provided in the substantially uniform magnetic field and outputting an output signal based on the substantially uniform magnetic field;
With current sensor.   The current sensor according to claim 1, wherein the magnetic path changing unit and the magnetic field forming unit are formed of a soft magnetic material.   The current sensor according to claim 1, wherein the magnetic field forming portion is formed such that the distance between the one end portion and the other end portion is narrowed as the distance from the conductor increases.   The current sensor according to claim 1, wherein the magnetic field forming unit has a gap between itself and a main body of the magnetic path conversion unit. A magnetic path changing unit that is formed in a cylindrical shape by a soft magnetic material, is provided so as to surround a conductor that generates a magnetic field based on a flowing current, and changes a magnetic path that is a path of the magnetic field;
A magnetic flux density is provided in the interval by providing an interval between the opposite inner walls of the magnetic path changing portion and propagating the changed magnetic path from one end portion to the other end portion formed stepwise. Forming a substantially uniform magnetic field, and as the magnetic field weakens, the gap between the one end and the other end is formed narrow, and a magnetic field forming unit having a gap between the magnetic path conversion unit and the main body;
A magnetic sensor disposed in the substantially uniform magnetic field and outputting an output signal based on the substantially uniform magnetic field;
With current sensor.

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