JP2954500B2 - Current transformer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a current transformer in which a magnetic sensing element such as a Hall element or a magnetoresistive element is inserted into a magnetic gap of a magnetic circuit as current detecting means.

[0002]

2. Description of the Related Art Various types of current transformers used in watt-hour meters and current detection devices have been put into practical use, but in recent years, as shown in FIG. A current detecting unit is formed by disposing the magnetic element 11 between the ferromagnetic cores 12 and
A current transformer arranged in the magnetic air gap 14 has been developed. This type of current transformer applies a voltage proportional to a magnetic field generated in a magnetic circuit of the current transformer by a current flowing through an electric circuit to be measured, to a magnetic air gap constituting the magnetic circuit. The amount of current flowing in the electric circuit is measured by electrically extracting the electric current by the semiconductor magneto-sensitive element 11 which is a current detecting means inserted into the electric circuit 14.

[0003] Further, in the current transformer of this type, the present applicant fixedly accommodates a current detecting portion composed of a ferromagnetic core and a magnetic sensing element in a housing, and places the housing in a magnetic gap of a yoke. It proposes a fixed arrangement. (JP-A-5-135974)

[0004]

In the current transformer of the above type, there are various difficulties in manufacturing the yoke and the ferromagnetic core, and the position of the magneto-sensitive element and the output end of the ferromagnetic core is different. It may be difficult in terms of board mounting such as alignment.

A first object of the present invention is to provide a current transformer in which a yoke can be easily manufactured.

A second object of the present invention is to provide a current transformer which is easy to manufacture and mount a current detecting section comprising a ferromagnetic core and a magnetic sensing element.

[0007]

Means for Solving the Problems In order to achieve the first object, according to the present invention, the present invention is characterized in that a center of a magnetic gap provided in a part of a circular yoke constituting a magnetic circuit is provided. In a current transformer in which a magnetic sensing element is arranged and a ferromagnetic core is arranged in each of the magnetic gaps on both sides of the magnetic sensing element, a thin plate magnetic material is substantially formed so that the magnetic gap is formed.
The yoke is laminated with the thin magnetic material by punching and bending into a C-shaped circular shape .
Without forming.

According to a second aspect of the present invention, a ferromagnetic core is formed by punching a thin plate of a magnetic material, and the ferromagnetic core is mounted on a magneto-sensitive element. In addition, a housing fixed to the substrate and fixedly accommodating the substrate is fixedly arranged in the magnetic gap of the yoke.

[0009]

FIG. 1 is a perspective view of a current transformer according to an embodiment of the present invention. 1 is a yoke, for example, 0.2 to 0.5
It is formed into a substantially C-shaped orbit by punching and bending a thin magnetic material having a thickness of mm. The yoke 1 has an upper surface 1a and a lower surface 1b.
And four yoke end pieces 1c extending in the vertical direction from each other, and a magnetic gap 2 is formed between the yoke end pieces 1c in the vertical direction.
The coil 3 penetrates the space between the vertical surface portion 1d of the yoke 1 and the yoke end piece 1c.

A magneto-sensitive element 4 such as a Hall element is sandwiched between two ferromagnetic cores 5 formed by punching a thin magnetic material having a thickness of, for example, 0.2 to 0.5 mm. And they are fixed on a substrate 6 as shown in FIG. The substrate 6 is fixed in the insulating casing 7 by an adhesive treatment or a molding treatment. The magnetic sensing element 4 and the ferromagnetic core 5 constitute a current detecting unit.

The housing 7 is arranged in the magnetic gap 2 of the yoke 1 and, at this time, is positioned so that the edges of the housing 7 slightly enter between a pair of yoke end pieces 1c arranged in the horizontal direction. Therefore, the ferromagnetic core 5 in the housing 7 is a pair of the yoke end pieces 1.
The magnetic flux from the yoke end piece 1c is respectively concentrated on the ferromagnetic core 5 so as to oppose the tip of the ferromagnetic core 5c.

The operation of the current transformer will be described. As in the conventional case, the magnetic flux generated around the coil 3 by the current flowing through the coil 3 which is a part of the electric circuit to be measured is generated in the yoke 1 and the housing 7. A magnetic flux proportional to the amount of current flowing through the electric circuit to be measured circulates around a magnetic circuit composed of the magnetic sensing element 4 and the ferromagnetic core 5 and is converted into a voltage by the magnetic sensing element 4 and detected.

By separating the yoke 1 and the ferromagnetic core 5 constituting the magnetic circuit, the magnetic gap 2 of the yoke 1 is separated.
Can be widened. This makes it possible to mount the coil by winding the current wire around the yoke 1 in advance. FIG. 3 shows an embodiment in this case. Reference numeral 8 denotes a coil composed of a thin current wire wound on the yoke 1 in advance. Further, since the yoke 1 and the ferromagnetic core 5 are separated from each other, the shapes and materials of the yoke 1 and the ferromagnetic core 5 can be separately considered, and the degree of freedom in design can be increased. Furthermore, by adjusting the gap length between the yoke 1 and the ferromagnetic core 5, it is possible to adjust so as to prevent saturation of the magnetic field.

The ferromagnetic core 5 and the magneto-sensitive element 4 are fixed on one substrate 6 and housed in the housing 7, so that the position and inclination of the magneto-sensitive element 4 with respect to the ferromagnetic core 5 can be adjusted. Variation can be suppressed. The ferromagnetic core 5
Therefore, the magnetic flux passing through the ferromagnetic core 5 always passes through the magnetic sensing element 4 and the leakage magnetic flux can be eliminated. Then, the mechanical strength can be increased. Since the substrate 6 is arranged parallel to the direction of the magnetic flux, the thickness of the substrate is not limited, while the substrate must be thinner when arranged perpendicular to the direction of the magnetic flux.

Since the yoke 1 is formed by punching and bending a thin magnetic material, the yoke 1 can be easily manufactured. Then, the bonding process as in the case of the conventional cut core becomes unnecessary.

Further, various magnetic circuit configurations as shown in FIGS. 4A to 4G can be easily manufactured. FIG. 4 (c)
In the case of, as shown in FIG.
Is inserted into the yoke 1 and its position is fixed by appropriate means. In the case of FIG. 4 (f), since the yoke end piece 1c is separated from the yoke 1, as shown in FIG. 6, the yoke end piece 1c is accommodated in the housing 7 and fixed by filling with an insulating material.

As for the magnetism collecting effect of the yoke 1, a result equal to or higher than that of a magnetic material having a large sectional area can be obtained. Since the yoke 1 is made of a thin magnetic material, eddy current loss can be reduced.

Since the ferromagnetic core 5 is formed by punching a thin magnetic material, the ferromagnetic core 5 can be easily manufactured and its output end can be easily polished. Also,
The positioning of the output end of the ferromagnetic core 5 and the magneto-sensitive element 4 is facilitated on the substrate.

[0019]

As described above, according to the first aspect of the present invention, a thin plate magnetic material is used for a magneto-sensitive element and a ferromagnetic element.
Substantially C-shaped so that a magnetic gap for body core placement is formed
The yoke is not laminated with the thin magnetic material by punching and bending into a circular shape.
Since it is formed well, the yoke can be easily manufactured. Further, yokes having various magnetic circuit configurations can be easily manufactured.

According to the second aspect of the present invention, a ferromagnetic core is formed by punching a thin magnetic material, and the ferromagnetic core is fixed on a substrate together with a magneto-sensitive element. Since the housing for fixedly accommodating the substrate is fixedly arranged in the magnetic gap of the yoke, the current detecting section including the ferromagnetic core and the magneto-sensitive element can be easily manufactured and mounted.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a current transformer according to an embodiment of the present invention.

FIG. 2 is a perspective view showing an example of an internal configuration of a housing of the current transformer shown in FIG.

FIG. 3 is a perspective view when the coil of the current transformer shown in FIG. 1 is wound.

FIG. 4 is a diagram showing yokes having various magnetic circuit configurations.

FIG. 5 is a diagram showing a positional relationship between a coil and a housing with respect to a yoke in FIG. 4 (c).

FIG. 6 is a view showing a means for fixing a yoke end piece when the yoke of FIG. 4 (g) is used.

FIG. 7 is a perspective view showing a conventional current transformer using a semiconductor magneto-sensitive element.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Yoke 1c Yoke end piece 2 Magnetic gap 3 Coil 4 Magnetic sensing element 5 Ferromagnetic core 6 Substrate 7 Housing 8 Coil

────────────────────────────────────────────────── (5) References JP-A-5-135974 (JP, A) JP-A-59-181602 (JP, A) JP-A-58-58712 (JP, A) (58) Investigation Field (Int.Cl. ⁶ , DB name) H01F 27/24-27/26

Claims (2)

(57) [Claims] 1. A magnetic sensing element is disposed at the center of a magnetic gap provided in a part of a circular yoke constituting a magnetic circuit,
In the current transformer to the magnetic gap of the both sides of the sensitive magnetosensitive and the ferromagnetic core is arranged, wherein the thin magnetic material
The yoke is formed without laminating the thin magnetic material by punching and bending into a substantially C-shaped orbit so that a magnetic gap is formed. Current transformer. 2. A housing for accommodating a ferromagnetic core by punching a thin magnetic material, fixing the ferromagnetic core together with a magneto-sensitive element on a substrate, and accommodating the substrate in a fixed manner. 2. The current transformer according to claim 1, wherein the current transformer is fixedly disposed in a magnetic gap of the yoke.