JP2013164288A - Current sensor - Google Patents

Abstract

The present invention provides a current sensor that is less susceptible to an external magnetic field by positioning a magnetic detection element stably and accurately at the center of a gap portion of a magnetic core.
In a current sensor according to the present invention, a support 30 includes an accommodating portion 31 that accommodates a magnetic detection element 11 in an internal space, an abutting portion 32 that abuts on a peripheral surface of a magnetic core 20, and a protrusion at a tip portion. The support portion 30 includes an arm portion 37 that is engaged with the groove portion 22 formed on both side surfaces of the magnetic core 20 at the portion 33, and the support 30 is in contact with the peripheral surface of the magnetic core 20. The protrusion 3 is engaged with the groove portion 22 of the magnetic core 20 to be positioned with respect to the magnetic core 20, and the magnetic detection element 11 is brought into contact with the wall portion of the internal space of the housing portion 31 to be prevented from being displaced. In this state, the gap portion 21 is disposed at the center.
[Selection] Figure 1

Description

  The present invention relates to a current sensor that measures, for example, a battery current, a motor driving current of a hybrid car or an electric vehicle, and a current flowing through a motor of a machine tool using a magnetic detection element such as a Hall element.

2. Description of the Related Art Conventionally, a magnetic proportional sensor is known as a current sensor that detects a current (current to be measured) flowing through a bus bar in a non-contact state using a magnetic detection element such as a Hall element.
This current sensor includes a ring-shaped magnetic core that surrounds a path of a current to be measured and has a gap portion having a predetermined width, and a magnetic detection element positioned in the gap portion, and a magnetic field in the gap portion is generated by a current flowing through the bus bar. And this magnetic field is applied to the magnetosensitive surface of the magnetic sensing element. Since the strength of the magnetic field is proportional to the current to be measured, the value of the current to be measured is obtained from the output voltage of the magnetic detection element.

Patent Document 1 below discloses a current detector in which the sensitivity is improved by reducing the gap of the magnetic core. Here, the magnetic core is fixed in close contact with one side surface of the printed circuit board, and the magnetic detection element is disposed at substantially the center point of the gap with the magnetic sensitive surface parallel to the side surface of the gap.
Moreover, in the current sensor shown in Patent Document 2, the magnetic core and the magnetic detection element are arranged in this order from the bottom side in the component housing chamber (housing portion) of the resin member in that order. The magnetic detection element is disposed in the gap portion of the magnetic core.
Therefore, when the current sensor is viewed from the back side (upper side) of the substrate, the magnetic detection element disposed in the gap portion is covered with the substrate and cannot be viewed from above.

Japanese Utility Model Publication No. 6-4679 Japanese Patent No. 4459011

For example, “battery current monitoring current sensors” and “inverter three-phase AC monitoring current sensors” used in hybrid vehicles and EVs (electric vehicles) are used in an environment where extremely large electromagnetic noise from outside is constantly applied. used.
For this reason, the magnetic detection element of the current sensor should sense only the magnetic field generated by the current to be measured, but also senses an external magnetic field (noise), and sensor output accuracy may deteriorate.

In the current detector disclosed in Patent Document 1, the magnetic detection element is merely soldered to the printed circuit board, and the position of the magnetic detection element in the gap portion cannot be accurately determined. ).
In the current sensor disclosed in Patent Document 2, since the magnetic detection element disposed in the gap portion of the magnetic core in the component housing chamber is covered with the substrate, the positional relationship between the gap portion and the magnetic detection element is determined by a camera or the like. It cannot be confirmed by the optical method.
Therefore, in this current sensor, the magnetic detection device is arranged so as to be shifted toward one end surface with respect to the center position between the both end surfaces of the core forming the gap portion (center position of the gap portion), and the larger the shift amount is, There has been a problem that the characteristic variation due to the disturbance magnetic field becomes large.

  An object of the present invention is to solve such a problem. The magnetic detection element is stably and accurately positioned at the central portion in the gap portion of the magnetic core, so that it is hardly affected by an external magnetic field. An object is to provide a current sensor.

A current sensor according to the present invention surrounds the path of a current to be measured and is provided so as to cover a ring-shaped magnetic core having a gap portion with a predetermined width, a magnetic detection element positioned in the gap portion, and the magnetic core. And a current sensor provided with a support for holding the magnetic detection element,
The support is formed in an intermediate portion thereof, and a housing portion that houses the magnetic detection element in an internal space;
An abutting portion that is formed on the inner wall of the peripheral edge and abuts on the circumferential surface of the magnetic core;
A pair of arms extending to the side of the magnetic core on both sides thereof, and arm portions for locking to locked portions formed on both side surfaces of the magnetic core at the locking portion of the tip portion,
The support is in contact with the magnetic core by the contact portion being in contact with the peripheral surface of the magnetic core and the locking portion of the arm portion being locked to the locked portion of the magnetic core. Positioned,
The magnetic detection element is disposed at the center of the gap portion in a state where the displacement is restricted by contacting the wall portion of the internal space of the housing portion.

  According to the current sensor of the present invention, the support is configured such that the contact portion is in contact with the peripheral surface of the magnetic core, and the locking portion of the arm portion is locked to the locked portion of the magnetic core. The magnetic detection element is disposed at the center of the gap portion in a state where the displacement is regulated by contacting the wall portion of the internal space of the support accommodating portion. Stable and accurate positioning at the center of the gap portion of the magnetic core and less susceptible to external magnetic fields.

It is a disassembled perspective view which shows the current sensor which concerns on Embodiment 1 of this invention. It is a front sectional view showing the current sensor of FIG. It is a top view which shows the current sensor of FIG. It is a front view which shows the support of FIG. It is a perspective view when the support of FIG. 1 is seen from the back side. FIG. 3 is an enlarged view of a main part of FIG. 2. It is a disassembled perspective view which shows the current sensor which concerns on Embodiment 2 of this invention. FIG. 8 is a front sectional view showing the current sensor of FIG. 7. It is a sectional side view which shows the current sensor of FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, the same or equivalent members and parts will be described with the same reference numerals.

Embodiment 1 FIG.
1 is an exploded perspective view showing a current sensor according to Embodiment 1 of the present invention, FIG. 2 is a front sectional view showing the current sensor of FIG. 1, and FIG. 3 is a plan view showing the current sensor of FIG.
This current sensor includes a ring-shaped magnetic core 20 (such as a silicon steel plate or a permalloy core with high permeability and low residual magnetism) having a gap portion 21 surrounding the periphery of the bus bar 12, which is a path of a current to be measured. A support 30 provided on the magnetic core 20 and a magnetic detection element 11 mounted on the printed circuit board 13 disposed above the support 30 and disposed in the gap portion 21 are provided.

The bus bar 12 has a flat plate shape (for example, a copper plate), and is attached so as to form a path of a current to be measured by, for example, screws or rivets through attachment holes (not shown) located at both ends in the longitudinal direction.
The magnetic detection element 11 has its terminal pin 10 inserted through a through hole of the printed board 13 and is electrically connected to the printed board 13 by, for example, soldering. In addition, the positional relationship between the printed circuit board 13 and the magnetic core 20 and the support 30 is fixed by a resin member (not shown), for example.

The support 30 shown in FIGS. 4 and 5 is provided with a receiving portion 31 that protrudes into the gap portion 21 at the center thereof.
The accommodating portion 31 accommodates the magnetic detection element 11 in its internal space.
Of the wall portions defining the internal space, an opening 35 for accommodating the magnetic detection element 11 in the internal space of the accommodating portion 31 is formed in the wall portion in the direction along the axial direction of the bus bar 12. Yes. The end surface of the opening 35 is an inclined surface 36 that is enlarged from the inside toward the outside in order to facilitate the insertion of the magnetic detection element 11 into the internal space of the housing portion 31. Further, an introduction hole 38 for introducing the terminal pin 10 is formed in the ceiling portion of the wall portion. An upper projection 34 is formed in the introduction hole 38.
Further, the support 30 is an inner wall portion of the peripheral portion thereof, and at its four corners, contact portions 32 that protrude inward and come into contact with the four corners of the peripheral surface of the magnetic core 20 are provided. In addition, on both sides, arm portions 37 are provided that extend toward the magnetic core 20 and have protrusions 33 serving as locking portions at the tip portions.

The magnetic core 20 is formed with groove portions 22 which are locked portions extending in the ± Y directions on both side surfaces thereof. The support 30 is positioned in the ± Z direction and the ± X direction by the protrusion 33 engaging with the groove 22, and the abutment portion 32 abuts on the peripheral surface of the magnetic core 20. The position in the ± Y direction is determined.
When the magnetic detection element 11 is accommodated and held in the internal space of the support 30, the magnetic detection element 11 comes into contact with the opposite side walls of the internal space so that the ± X of the element inside the magnetic detection element 11 is ± X. The center of the direction is formed so as to be located at the center of the gap portion 21.
Thereby, the magnetic detection element 11 accommodated in the internal space of the accommodating portion 31 is automatically positioned at the center of the gap portion 21 in the ± X direction. Further, in the internal space of the accommodating portion 31, the magnetic detection element 11 is in contact with the back wall portion of the magnetic detection element 11, and the + Y positional deviation is restricted. The positional deviation is regulated, and the positional deviation in the + Z direction is regulated by contacting the upper convex portion 34.
Thus, the dimension of the internal space of the accommodating part 31 is set according to the size of the magnetic detection element 11 so that the magnetic detection element 11 can be held without positional deviation.

Since the support 30 is made of resin or the like so as to have a certain degree of elasticity, even if the distance between the protrusions 33 at the tip of the arm part 37 is shorter than the length of the magnetic core 20 in the ± X direction, the protrusions 33 can be locked to the groove 22.
The protrusion 33 has a tapered shape in which the width in the ± X direction is reduced toward the −Z direction, and is easily locked in the groove 22.

In the current sensor of this embodiment, when a current to be measured flows through the bus bar 12, a magnetic field is generated in the gap portion 21 of the magnetic core 20, and this magnetic field causes the magnetic detection element 11 to be proportional to the magnitude of the magnetic field. An output voltage is applied.
Therefore, since the strength of the magnetic field is proportional to the magnitude of the current to be measured, the magnitude of the current to be measured flowing to the bus bar 12 from the output voltage of the magnetic detection element 11 is obtained.

  According to the current sensor of this embodiment, since the accommodating portion 31 in which the magnetic detection element 11 is accommodated is located at the center of the gap portion 21, the magnetic detection element 11 is at the center of the gap portion 21 of the magnetic core 20. Positioning is performed stably and accurately, and a highly reliable current sensor that is hardly affected by an external magnetic field can be realized.

  Also, the magnetic detection element 11 is restricted in positional deviation in the ± X, + Y, and ± Z directions by both sides of the internal space of the accommodating portion 31, the bottom wall portion, and the upper convex portion 34. Less susceptible to external magnetic fields.

  Moreover, in this embodiment, since the magnetic detection element 11 can be arrange | positioned in the center of the gap part 21 of the magnetic core 20, the positional relationship of the magnetic detection element 11 and the gap part 21 can be confirmed from the outside, and magnetic The output characteristics of the current sensor can be adjusted before the detection element 11 is mounted on the printed circuit board 13 via the terminal pins 10.

  Further, when the terminal pin 10 of the magnetic detection element 11 is soldered to the printed circuit board 13, the ± Z direction may be reversed, that is, the terminal pin 10 may be directed downward to undergo a reflow soldering process. Since the positional deviation in the ± Z direction is restricted by the bottom side wall portion and the upper convex portion 34 of the internal space 31, it is possible to realize a highly reliable current sensor that is hardly affected by the external magnetic field.

Embodiment 2. FIG.
7 is an exploded perspective view showing a current sensor according to Embodiment 2 of the present invention, FIG. 8 is a front sectional view of FIG. 7, and FIG. 9 is a side sectional view of FIG.
In the current sensor of this embodiment, a part of the magnetic core 20 is exposed to the outside and is integrally formed with the resin member 40. The resin member 40 is formed with a concave portion 41 into which the accommodating portion 31 of the support 30 is fitted.
Other configurations are the same as those of the magnetic sensor of the first embodiment.

In this embodiment, since the magnetic core 20 is integrally formed with the resin member 40, the positional deviation of the magnetic core 20 can be suppressed.
Moreover, since the upper surface of the magnetic core 20 and the upper side of both side surfaces are exposed to the outside, the magnetic core 20 can be provided by being covered with the support 30, and the protruding portion 33 can be locked to the groove portion 22.
Furthermore, in the first embodiment, the opening 35 side of the housing portion 31 is open, and the positional deviation in the −Y direction of the magnetic detection element 11 cannot be regulated. When the 30 accommodating portions 31 are inserted into the recess 41, the magnetic detection element 11 is in contact with the inner wall surface A of the recess 41 on the −Y direction side. The positional deviation in the −Y direction is also restricted.
Other effects are the same as those of the current sensor of the first embodiment.

  In the first and second embodiments, an example is shown in which the groove portion 22 is formed as a locked portion in the magnetic core 20 and the arm portion 37 of the support 30 is snap-fit, and is elastically locked to the groove portion 22. However, a protrusion may be formed on the magnetic core 20, and a recess or a hole that engages with the protrusion may be formed at the tip of the arm 37.

  10 terminal pin, 11 magnetic detection element, 12 bus bar (path), 13 printed circuit board, 20 magnetic core, 21 gap part, 22 groove part (locked part) 30 support, 31 receiving part, 32 contact part, 33 protrusion part (Locking part), 34 upper convex part, 35 opening part, 36 inclined surface, 37 arm part, 38 introduction hole, 40 resin member, 41 concave part.

Claims (5)

A ring-shaped magnetic core surrounding the path of the current to be measured and having a gap portion of a predetermined width; a magnetic detection element positioned in the gap portion; and the magnetic detection element provided over the magnetic core A current sensor with a support for holding
The support is formed in an intermediate portion thereof, and a housing portion that houses the magnetic detection element in an internal space;
An abutting portion that is formed on the inner wall of the peripheral edge and abuts on the circumferential surface of the magnetic core;
A pair of arms extending to the side of the magnetic core on both sides thereof, and arm portions for locking to locked portions formed on both side surfaces of the magnetic core at the locking portion of the tip portion,
The support is in contact with the magnetic core by the contact portion being in contact with the peripheral surface of the magnetic core and the locking portion of the arm portion being locked to the locked portion of the magnetic core. Positioned,
The current sensor, wherein the magnetic detection element is disposed at a central portion of the gap portion in a state in which displacement is restricted by contacting a wall portion of the internal space of the housing portion.   In the housing portion, an opening for inserting the magnetic detection element into the internal space of the housing portion is formed in the wall portion in a direction along the axial direction of the path, and an end surface of the opening portion is formed from the inside. The current sensor according to claim 1, wherein the current sensor is an inclined surface that expands outward.   The current sensor according to claim 1, wherein the magnetic core is integral with a resin member with the locked portion exposed to the outside.   The current sensor according to claim 3, wherein the resin member has a recess into which the housing portion is inserted.   The said arm part has elasticity, The said latching | locking part is latched elastically to the said to-be-latched part of the said magnetic core, The any one of Claims 1-4 characterized by the above-mentioned. The current sensor described in 1.

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