JP3109869B2 - Current sensor and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a current sensor for detecting mainly a direct current, such as an inverter circuit or a motor control circuit, and more particularly to a magnetic sensor in which a magnetic gap is provided in a magnetic path of a magnetic core. The present invention relates to a current sensor in which a magnetic detection element is provided between the coils, a winding is applied to a magnetic circuit, and a current to be measured is passed through the winding, and a method of manufacturing the same.

[0002]

2. Description of the Related Art As shown in FIG. 4, a conventional magnetic sensor of this type has a magnetic joint 11a made of a soft magnetic ferrite core and a core joint 15 at one end of a magnetic core 11b formed in a flat or uneven shape. A magnetic gap 16 is formed at the other end, a magnetic sensing element 14 is arranged between the magnetic gaps 16 and the magnetic core 11
a, a winding 12 for flowing a current to be detected is wound around a magnetic circuit composed of a magnetic core 11b,
Was fixed with an adhesive or the like. In a conventional current sensor having such a configuration, a current to be detected is passed through the winding 12, whereby the magnetic detecting element 1 such as a Hall element is used.
4 detects the output voltage proportional to the magnetic field generated in the magnetic gap 16 and detects the value of the current to be detected. However, in such a conventional current sensor, the core joining portion 15 at the other end of the magnetic gap formed in the magnetic core is a butt joint of the magnetic circuit, and it is difficult to always meet under constant conditions, and the gap is easily formed. , Is easily shifted and fixed from a predetermined mounting position.
The leakage of magnetic flux from the magnetic core to the outside of the magnetic core increases, the variation in the value of the detected current for each current sensor increases, and when joining the core joints, assembly accuracy is required and man-hours are required for assembly There was a disadvantage that.

[0003]

SUMMARY OF THE INVENTION In order to eliminate these drawbacks, the present invention uses an integral magnetic core made of a metallic magnetic material having a high relative magnetic permeability, and applies a winding to a coil bobbin in advance. After assembling the coil bobbin on which the winding is applied into one magnetic leg of the magnetic core having a V-groove on the inside, the magnetic core is bent inward at two V-groove portions provided in advance on the inside of the magnetic core. A magnetic gap is formed, and a stopper provided on the inner diameter side of the coil bobbin is fitted with the V-groove to position the coil bobbin, the magnetic core and the substrate by the substrate support provided inside the magnetic core and the lower surface of the magnetic gap. With no core joint,
An object of the present invention is to provide a current sensor which has excellent current detection accuracy and facilitates assembly of a magnetic core, a coil bobbin, and a substrate, and a method of manufacturing the same.

[0004]

In the current sensor according to the present invention, the magnetic core is made of a metallic magnetic material having high relative magnetic permeability, and a coil bobbin having a winding wound around one magnetic leg is provided in a magnetic gap. After the insertion from the forming portion, a two-stage first V-groove close to the magnetic gap for forming a magnetic gap and for integrally fixing the magnetic core, the coil bobbin, and the substrate on which the magnetic sensing element is mounted; Second near the base
Have two V-grooves . The coil bobbin around which the winding is wound is incorporated into the magnetic leg provided with the V-groove of the magnetic core,
The magnetic core is bent inward from the two V-groove portions to form a magnetic gap, and the substrate on which the magnetic sensing element and the amplification circuit are mounted is incorporated into the magnetic core in the direction of the magnetic gap with the substrate groove first. The magnetic core, the substrate, and the coil bobbin around which the winding is wound are integrated with the substrate supporting portion, the magnetic core protrusion on the lower surface of the magnetic gap, and the stopper of the coil bobbin around which the winding is wound. Therefore, it is possible to prevent the current detection accuracy from being lowered due to the leakage of the magnetic field at the junction, which occurs in the conventional current sensor, and to provide a current sensor that is easy to assemble and a method of manufacturing the same.

That is, the present invention provides: In a current sensor in which a magnetic gap is provided in a part of a magnetic core of a closed magnetic circuit, a winding through which a current to be detected flows is wound in the magnetic circuit, and a magnetic sensing element is provided in the magnetic gap, the magnetic core is made of metal magnetic material. The laminated core is made by stamping and laminating a soft magnetic plate made of material, and the inside of the laminated core is fitted with the stopper of the coil bobbin with the magnetic leg of the laminated core inside and the winding wound around the core. At least two V-grooves to be bent and a substrate support for positioning a substrate on which the magnetic detection element and an amplification circuit for increasing the output of the magnetic detection element are mounted are provided. A magnetic gap is formed by inserting the magnetic leg at the position of the V-groove and bending the magnetic leg at the position of the V-groove, and the substrate supporting portion and the convex portion of the magnetic gap portion formed on the magnetic core are used to form the magnetic gap. Coil bobbin and magnet A core which is a current sensor which is characterized by being configured and positioned together. 2. A metal magnetic plate having a high relative magnetic permeability is formed in a U-shape so as to open the magnetic gap forming portion, and a first V formed in two steps near the magnetic gap forming portion on the inner diameter side of one magnetic leg. 1 at the groove and at the base of the magnetic leg
Forming and punching a substrate support at the second V-groove of the step and at the base of the other magnetic leg facing the magnetic leg, heat-treating and laminating the metal magnetic plate to form a magnetic core, V
A coil bobbin provided with a stopper provided at a position corresponding to the groove and provided with a winding is inserted into the one magnetic leg, and a substrate on which a magnetic detection element and an amplification circuit are mounted is inserted from the magnetic gap forming portion and the substrate is inserted. A support is provided on the lower surface of the magnetic gap, and one of the first V-grooves and the second V-groove are bent to fit the stopper of the coil bobbin into the other of the first V-grooves. A method for manufacturing a current sensor, comprising positioning and fixing a coil bobbin and a substrate.

[0006]

The magnetic core of the current sensor according to the present invention uses a magnetic core made of a metallic magnetic material, and has a plate thickness of about 0.5 mm in a DC or commercial frequency range. Is 0.1 mm in the kHz range
It is made by punching a 78% Ni permalloy plate of a thickness or 45% Ni to 36% Ni permalloy plate. The magnetic core is therefore formed by lamination. Of course, the magnetic core is heat-treated in a high-purity hydrogen gas at a temperature of at least 900 ° C. before mounting the coil bobbin, and the magnetic core has a high relative magnetic permeability. It has properties and mechanical properties are soft and easy to bend. In the magnetic core, the gap between the magnetic gap forming portions is formed in a U-shape in such a size that the coil bobbin can be inserted in advance, and the bending position for forming the magnetic gap is determined inside the magnetic core. V-grooves and a substrate support for positioning are formed at two places for integrally molding the substrate together. A coil bobbin with a winding wound around a magnetic core is inserted from the magnetic gap side, and the magnetic core is bent inward at two V-groove positions along two V-grooves to increase the detection voltage of the magnetic detection element and the magnetic detection element. The substrate on which the amplification circuit to be mounted is mounted is inserted into the magnetic core from the magnetic gap portion with the substrate groove first, and the substrate is placed on the lower surface of the substrate support portion and the magnetic gap, and the first V groove of the magnetic core and the coil bobbin are mounted. The stopper is engaged to bend inside the second V-groove to form a magnetic gap, and the coil bobbin, the magnetic core and the substrate are fixed. After bending the two V-grooves provided inside the magnetic core and forming the magnetic gap, the surface facing the magnetic gap may be mechanically ground before inserting the substrate in order to more accurately determine the distance between the magnetic gaps.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment according to the present invention will be described with reference to FIGS. FIG. 1 is an external perspective view showing the structure of a current sensor according to the present invention. FIG. 2 is a longitudinal sectional view of the current sensor shown in FIG.
FIG. 3 is a front view showing a punched shape of a magnetic core using a metal magnetic material. A 78% Ni permalloy, 45% Ni to 36% Ni permalloy plate is punched into the shape of FIG.
Heat treatment is performed at least at a temperature of 900 ° C. or more in a hydrogen atmosphere for about one hour. The magnetic core subjected to the heat treatment has high relative magnetic permeability characteristics and is mechanically soft, and has a first V-groove 5a formed into a two-stage shape and a second V-groove 5b having only one stage. A substrate supporting portion 6 for positioning the lower surface of the substrate is formed on the magnetic core. The magnetic core is a laminated core in which metal magnetic plates having a thickness of 0.5 mm to 0.1 mm are laminated, and a magnetic leg in which a V-groove of the magnetic core is provided on a coil bobbin 7 around which the winding 2 is wound from the magnetic gap 1a side. Insert into Next, the second V-groove 5b at the base of the magnetic leg of the magnetic core is bent, and the first V-groove 5a near the magnetic gap is bent inward. The V-groove 5a is formed in a V-groove whose angle is cut in two steps, and the first-stage has a recess in which a stopper 8 of a coil bobbin 7 described later is fitted so that the V-groove surfaces coincide with each other. Form. Accordingly, the gap distance of the magnetic gap 1a is formed by bending the two first V-grooves 5a and the second V-groove 5b inward. The substrate 3 shown in FIG. 1 is inserted into the formed magnetic core until the inside of the magnetic core comes into contact with the inner end face of the groove from the substrate groove 9, and the substrate 3 is placed on the substrate support 6 and the lower surface of the magnetic gap, The stopper 8 of the coil bobbin and the first V-groove 5a of the magnetic core are abutted and fitted, and the magnetic core, the substrate, and the coil bobbin are fitted and integrated. The current sensor is then coated with varnish or the like, and the laminated magnetic core, circuit board and coil bobbin are integrated by varnish processing.

[0008]

As described above, the current sensor and the method of manufacturing the same according to the present invention are constituted by an integrated magnetic circuit except for a magnetic gap in which a magnetic detecting element is placed in a magnetic circuit.
After being inserted into the coil bobbin using an integrated magnetic core, the magnetic core is bent inward with two V-grooves provided in advance in the magnetic core as a fulcrum to form a magnetic gap. By adjusting the magnetic gap to the required size, there is little variation in detection characteristics due to a gap loss due to the magnetic gap at the other end of the magnetic gap portion due to the use of the conventional two-divided magnetic core, Also, since there is no need to position and join the magnetic cores, reliability is improved, and a current sensor that can be easily assembled and a method of manufacturing the same can be provided.

[Brief description of the drawings]

FIG. 1 is an external perspective view showing a current sensor according to the present invention.

FIG. 2 is a longitudinal sectional view of the current sensor shown in FIG.

FIG. 3 is a front view showing a shape of a magnetic core used in the present invention before a coil bobbin is inserted.

FIG. 4 is an external perspective view showing a conventional current sensor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Magnetic core 1a Magnetic gap 2 Winding 3 Substrate 4 Magnetic detection element 5a 1st V-groove 5b 2nd V-groove 6 Substrate support part 7 Coil bobbin 8 Stopper 9 Substrate concave groove 10 Widening circuit 11a, 11b Magnetic core 12 winding Line 13 Substrate 14 Magnetic sensing element 15 Core junction 16 Magnetic gap

Claims (2)

(57) [Claims] In a current sensor, a magnetic gap is provided in a part of a magnetic core of a closed magnetic circuit, a winding through which a current to be detected flows is wound around the magnetic circuit, and a magnetic detecting element is provided in the magnetic gap. The magnetic core consists of a laminated core made by stamping and laminating a soft magnetic plate made of metallic magnetic material. Inside the laminated core, the magnetic legs of the laminated core are set inside and fitted to the stopper of the coil bobbin around which the winding is wound. At least two V-grooves for bending the laminated core inward, and a substrate support for positioning the substrate on which the magnetic detection element and a circuit for increasing the output of the magnetic detection element are mounted are provided. The wound coil bobbin is inserted into a magnetic leg provided with a V-groove, the magnetic leg is bent at the position of the V-groove to form a magnetic gap, and the protrusions of the magnetic gap formed on the substrate support and the magnetic core are formed. Part and the substrate An electric current sensor characterized in that an ilbobin and a magnetic core are integrally positioned and configured. 2. A U-shaped metal magnetic plate having a high relative magnetic permeability characteristic so as to open a magnetic gap forming portion.
2 near the magnetic gap forming portion on the inner diameter side of one magnetic leg.
A first V-groove formed in a step, a second V-groove of one step at the base of the magnetic leg, and a substrate supporting portion formed at the base of the other magnetic leg facing the magnetic leg, and punching; A metal magnetic plate is heat-treated and laminated to form a magnetic core, a stopper is provided at a position corresponding to the first V-groove, and a coil bobbin provided with a winding is inserted into the one magnetic leg. And a substrate on which the amplifier circuit is mounted is inserted from the magnetic gap forming portion and supported by the substrate supporting portion and the lower surface of the magnetic gap, and one of the first V-grooves and the second V-groove are bent to form a coil bobbin. The method according to claim 1, wherein the stopper is fitted into the other of the first V-grooves, and the magnetic core, the coil bobbin, and the substrate are positioned and fixed.