JPH08241821A - Current transformer - Google Patents

Abstract

PURPOSE: To enable a current detecting section to be easily formed and mounted by a method wherein the current detecting section is formed by blanking and bending a thin-plate magnetic material, wherein a magnetic sensor is arranged at the center of a magnetic air gap provided to a U-shaped yoke, and a ferromagnetic core is provided on both sides of the magnetic sensor in the air gap to form a current transformer. CONSTITUTION: A thin plate magnetic material is formed into nearly a C-shaped yoke 1 by blanking and bending. A magnetic sensor 4 such as a Hall element or the like is sandwiched in between two ferromagnetic cores 5 formed by blanking a thin-plate magnetic material and fixed on a board 6 to form a current detecting section. The ferromagnetic core 5 is easily formed by blanking a thin-plate magnetic material, and the output terminal of the ferromagnetic core 5 is can be easily polished. When the current detecting section is mounted out a board, the output terminal of the ferromagnetic core 5 can be easily aligned with the magnetic sensor 4.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art Various types of current transformers used in watt-hour meters and current detectors have been put to practical use in the past, but in recent years, as shown in FIG. The magnetic element 11 is arranged between the ferromagnetic cores 12 to form a current detection unit, which is connected to the yoke 13
Current transformers have been developed which are located in the magnetic air gap 14 of. In this type of current transformer, a current proportional to a magnetic field generated in a magnetic circuit of the current transformer by a current flowing in an electric circuit to be measured is applied to a magnetic gap forming the magnetic circuit. The amount of current flowing in the electric circuit is measured by electrically taking out by the semiconductor magneto-sensitive element 11 which is a current detecting means inserted in 14.

Further, the applicant of the present invention, in this type of current transformer, fixedly accommodates a current detecting portion composed of a ferromagnetic core and a magnetic sensitive element in a housing, and the housing is used as a magnetic air gap of a yoke. It proposes a fixed placement. (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 magnetic 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 whose yoke is easy to manufacture.

A second object of the present invention is to provide a current transformer in which a current detecting section composed of a ferromagnetic core and a magnetic sensing element can be easily manufactured and mounted.

[0007]

In order to achieve the above first object, the present invention according to claim 1 is characterized in that the central portion of a magnetic air gap provided in a part of a circular yoke forming a magnetic circuit. In a current transformer in which magnetic elements are arranged, and ferromagnetic cores are respectively arranged in the magnetic gaps on both sides of the magnetic sensitive element,
The yoke is formed by punching and bending a thin magnetic material.

In order to achieve the second object, the present invention according to claim 2 forms a ferromagnetic core by punching a thin plate magnetic material, and the ferromagnetic core is used as a magnetic sensing element. At the same time, the housing is fixed on the substrate, and the housing for fixedly housing the substrate is fixedly arranged in the magnetic gap of the yoke.

[0009]

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
A thin magnetic material having a thickness of mm is punched and bent to be formed into a substantially C-shaped winding shape. The yoke 1 has an upper surface portion 1a and a lower surface portion 1b.
Has four yoke end pieces 1c extending in the vertical direction, 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.

The magnetic 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 0.2 to 0.5 mm, for example. Placed and they are fixed on the substrate 6 as shown in FIG. The substrate 6 is fixed in the insulative housing 7 by a bonding process or a molding process. The magnetic sensing element 4 and the ferromagnetic core 5 form a current detecting section.

The casing 7 is arranged in the magnetic gap 2 of the yoke 1, and at that time, the end edge of the casing 7 is positioned so as to be slightly inserted between the pair of yoke end pieces 1c arranged in the lateral direction. Therefore, the ferromagnetic core 5 in the housing 7 is composed of the pair of yoke end pieces 1
The magnetic flux from the yoke end piece 1c is concentrated on the ferromagnetic core 5 so as to face the tips of c.

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

By separating the yoke 1 constituting the magnetic circuit from the ferromagnetic core 5, the magnetic gap 2 of the yoke 1 is separated.
Can be widely used. As a result, the coil can be mounted by winding the current wire around the yoke 1 in advance. An example of this case is shown in FIG. Reference numeral 8 is a coil formed of a thin current wire that is wound around the yoke 1 in advance. Further, since the yoke 1 and the ferromagnetic core 5 are separated, 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 becomes possible to adjust so as to prevent the saturation of the magnetic field.

Since the ferromagnetic core 5 and the magnetic sensitive element 4 are fixed on one substrate 6 and housed in the housing 7, the position and inclination of the magnetic sensitive element 4 with respect to the ferromagnetic core 5 can be adjusted. Variations can be suppressed. Also, the ferromagnetic core 5
Since the magnetic sensitive element 4 and the magnetic sensitive element 4 can be brought into close contact with each other to make the gap between them zero, the magnetic flux passing through the ferromagnetic core 5 always passes through the magnetic sensitive 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 substrate must be thinned when arranged perpendicularly to the direction of the magnetic flux, whereas the thickness is not limited.

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. Figure 4 (c)
In the case of, the coil 3 and the housing 7 as shown in FIG.
Is inserted into the yoke 1, and its position is fixed by an appropriate means. In the case of FIG. 4F, since the yoke end piece 1c is separated from the yoke 1, it is housed in the housing 7 and fixed by filling with an insulating material, as shown in FIG.

Regarding the magnetism collecting effect of the yoke 1, it is possible to obtain a result equal to or higher than that of a magnetic material having a large cross-sectional area. 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 plate magnetic material, the ferromagnetic core 5 can be easily manufactured and its output end can be easily polished. Also,
When mounted on a substrate, the output end of the ferromagnetic core 5 and the magnetic sensitive element 4 can be easily aligned.

[0019]

As described above, according to the first aspect of the present invention, the yoke is formed by punching and bending the thin plate magnetic material, which facilitates the manufacture of the yoke. it can. Further, the yokes having various magnetic circuit configurations can be easily manufactured.

According to the second aspect of the present invention, a thin plate magnetic material is punched to form a ferromagnetic core, and the ferromagnetic core is fixed on a substrate together with the magnetic sensing element. Since the housing for fixedly accommodating the substrate is fixedly arranged in the magnetic gap of the yoke, the current detecting portion including the ferromagnetic core and the magnetic sensitive element can be easily manufactured and mounted.

[Brief description of drawings]

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

2 is a perspective view showing an internal configuration example of a housing of the current transformer shown in FIG. 1. FIG.

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

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

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

FIG. 6 is a view showing a fixing means of 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]

 1 yoke 1c yoke end piece 2 magnetic gap 3 coil 4 magnetic sensitive element 5 ferromagnetic core 6 substrate 7 housing 8 coil

Claims (2)

[Claims] 1. A magnetic sensing element is arranged at the center of a magnetic gap provided in a part of a circular yoke forming a magnetic circuit,
In a current transformer in which ferromagnetic cores are arranged in the magnetic gaps on both sides of the magnetic sensing element, the yoke is formed by punching and bending a thin plate magnetic material. . 2. A case in which a ferromagnetic core is formed by stamping a thin magnetic material, the ferromagnetic core is fixed on a substrate together with a magnetic sensing element, and the substrate is fixedly accommodated. The current transformer according to claim 1, wherein the current transformer is fixedly arranged in the magnetic gap of the yoke.