JP2980460B2 - Current detector - 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 detector in which a current flows through a ferromagnetic core and a magnetic flux generated at this time is detected by using a magneto-sensitive element. It relates to a detector.

[0002]

2. Description of the Related Art The configuration of a conventional current detector will be described with reference to FIG. FIG. 5 shows, for example,
FIG. 1 is a diagram illustrating an external side surface of a conventional current detector disclosed in Japanese Patent No. 8668.

In FIG. 5, 1 is a magnetic gap, 2 is a ferromagnetic core, 3 is a magneto-sensitive element such as a Hall element,
4 is a magnetic flux, 5 is a primary conductor through which a current to be detected flows, 6 is an electronic circuit board, 7 is an output terminal, and 8 is a circuit component.

Next, the operation of the above-described conventional current detector will be described. When the primary conductor 5 through which the detected current If flows is passed through the ferromagnetic core 2, a magnetic flux 4 proportional to the detected current If is generated in the magnetic gap 1 provided in the magnetic path of the ferromagnetic core 2. , Through the magneto-sensitive element 3 arranged in the magnetic gap 1.

Since the magnetic sensing element 3 converts the magnetic flux 4 into an electric output proportional to the strength of the magnetic flux, if the magnetic output is taken out to the output terminal 7 by the electronic circuit board 6, as a result, the current to be detected If A proportional output is obtained.

[0006]

In the conventional current detector as described above, a conductor (including a conductor through which a current to be detected) or a magnet is disposed near the current detector. In addition, there is a problem that the electronic circuit board 6 outputs an unnecessary output to the outside under the influence of the magnetic field.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and can reduce the influence of an external magnetic field on an electronic circuit board, and can thereby achieve a highly accurate current detection. The aim is to obtain a detector.

[0008]

According to a first aspect of the present invention, there is provided a current detector, comprising: a ferromagnetic core having a magnetic gap provided in a part of an annular magnetic path; and a magneto-sensitive core disposed in the magnetic gap. An element, a primary conductor through which a current to be detected flows, and an electronic circuit board having means for processing an output from the magneto-sensitive element, based on an output of the magneto-sensitive element in response to a magnetic flux generated in the magnetic gap. In a current detector for detecting a value of a current flowing through the primary conductor, the electronic circuit board may include a first
Disposed in a first electrically closed loop having an opening of
And the electronic circuit board and the first electrically closed loop
A second opening having a different opening direction from the first opening;
In a second electrically closed loop .

[0009]

[0010]

In the current detector according to the first aspect of the present invention, an electronic circuit board portion arranged in an electrically closed loop is provided.
Is placed in yet another electrically closed loop,
The opening directions of these electrically closed loops are different from each other.
To the outside so that it can be effectively shielded
The direction of the magnetic field expands, and the shielding effect can be enhanced
You .

[0011]

[0012]

【Example】

Embodiment 1 FIG. The configuration of Embodiment 1 of the present invention will be described with reference to FIG. FIG. 1 is a diagram showing Embodiment 1 of the present invention.

In FIG. 1, 1 is a magnetic gap, 2 is a ferromagnetic core, 3 is a magnetic sensing element such as a Hall element, 4 is a magnetic flux, and 5 is a primary conductor through which a current to be detected flows. Also, 6
Is an electronic circuit board, 7 is an output terminal, and 8 is an electronic circuit component.

Reference numeral 9 denotes an electric closed loop, whose constituent materials include a metal plate, an electric wire, a conductive paint and the like.
In the first embodiment, a metal plate is used as an electrically closed loop, and almost the entire electronic circuit board 6 is covered.

The operating principle of the current detector constructed as described above is exactly the same as that of the prior art.

The principle of shielding an external magnetic field will be described with reference to FIG. FIG. 2 is a detailed view of the electronic circuit board 6 and the metal plate in FIG. 1. In FIG. 2, reference numerals 10a and 10b denote magnetic fluxes penetrating the metal plate by an external magnetic field, and 11a and 11b denote induced currents.

Now, when a magnetic flux is applied to the metal plate in the direction of 10a, this metal plate is in a closed loop, so that an induced electromotive force is generated in a direction to hinder the change of the magnetic flux in the metal plate by the electromagnetic induction action. , 11a. The magnetic flux in the metal plate is canceled by the induced current, and the influence of the external magnetic field on the portion of the electronic circuit board 6 shielded by the metal plate can be improved.

Similarly, when a magnetic flux is applied in the direction of 10b, an induced current flows in the direction of 11b, and the magnetic flux in the metal plate is canceled, so that the influence of the external magnetic field on the electronic circuit board 6 is improved. Can be.

As shown in FIG. 2, the direction of the external magnetic field that can be effectively shielded by the electrically closed loop 9 is a direction perpendicular to the opening of the electrically closed loop 9. Therefore, the effect of the external magnetic field can be more efficiently improved by considering the arrangement of the electronic closed circuit 9 including the arrangement of the electronic circuit board 6 depending on the installation conditions of the current detector, the surrounding state, and the like.

The first embodiment of the present invention, as described above,
The electronic circuit board 6 is surrounded by an electrically closed loop 9 of a metal plate. Now, when a magnetic flux is applied to the metal plate 9 in the downward direction in the figure, since the metal plate 9 is in a closed loop, the induced electromotive force is generated in a direction in which the change of the magnetic flux in the metal plate 9 is prevented by the electromagnetic induction action. Occurs, and an induced current flows to the right in the figure. Therefore, the magnetic flux in the metal plate 9 is canceled, and the influence of the external magnetic field on the portion of the electronic circuit board 6 shielded by the metal plate can be improved. Similarly, when a magnetic flux is applied upward in the drawing, an induced current flows to the left in the drawing, and the effect of an external magnetic field can be improved.

Embodiment 2 FIG. In the first embodiment, the electronic circuit board 6 is provided with the electric closed loop 9 substantially over the entirety. However, as shown in FIG. 3, only the portion of the electronic circuit board 6 which is easily affected by an external magnetic field is provided. It goes without saying that the same effect can be expected even if the electrically closed loop 9A is provided.

Embodiment 3 FIG. FIG. 4 is a diagram showing a third embodiment of the present invention. In the third embodiment, the electric closed loop 9 configured as in the first embodiment is disposed in another electric closed loop 9B, and two electric closed loops 9 and
9B are arranged so that the opening directions are different from each other, and the electronic circuit board 6 is arranged therein. With such a configuration, the direction of the external magnetic field that can be effectively shielded by the electric closed loops 9 and 9B is widened, and the shielding effect can be further enhanced.

[0023]

As described above, according to the present invention, a ferromagnetic core having a magnetic gap provided in a part of an annular magnetic path, a magneto-sensitive element disposed in the magnetic gap, and a current to be detected flow. A primary conductor, and an electronic circuit board having means for processing an output from the magneto-sensitive element, wherein a value of a current flowing through the primary conductor is determined based on an output of the magneto-sensitive element in response to a magnetic flux generated in the magnetic gap. In the current detector for detecting, the electronic circuit board has a first opening having a first opening.
An electronic circuit board disposed in an electrically closed loop, and
And the first electrically closed loop is configured to open the first opening.
A second electrical closure having a second opening with a different mouth direction
Since it is arranged in the loop, the effect of being able to eliminate the influence of the external magnetic field over a wide range is achieved.

[0024]

[Brief description of the drawings]

FIG. 1 is a perspective view showing a first embodiment of the present invention.

FIG. 2 is a diagram illustrating an operation state of the first embodiment of the present invention.

FIG. 3 is a perspective view showing Embodiment 2 of the present invention.

FIG. 4 is a diagram showing a third embodiment of the present invention.

FIG. 5 is a diagram showing a conventional current detector.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Magnetic gap 2 Ferromagnetic core 3 Magnetic sensing element 5 Primary conductor 6 Electronic circuit board 9 Electrically closed loop of a metal plate 9A Electrically closed loop of a metal plate 9B Electrically closed loop of a metal plate

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-259577 (JP, A) JP-A 62-141766 (JP, U) JP-A 4-71177 (JP, U) (58) Investigation Field (Int.Cl. ⁶ , DB name) G01R 15/20 G01R 33/06-33/09

Claims (1)

(57) [Claims] 1. A ferromagnetic core having a magnetic gap provided in a part of an annular magnetic path, a magnetic sensing element disposed in the magnetic gap, a primary conductor through which a current to be detected flows, and An electronic circuit board having means for processing the output of the magnetic sensor, wherein a current detector that detects a value of a current flowing through the primary conductor based on an output of the magneto-sensitive element in response to a magnetic flux generated in the magnetic gap; The circuit board has a first electrical closure having a first opening.
Disposed in a loop, and wherein the electronic circuit board and the
A first electrically closed loop is directed toward the opening of the first opening.
In a second electrically closed loop having a different second opening
A current detector, wherein the current detector is arranged in a current detector.