JP5886546B2 - Current sensor - Google Patents

Description

  The present invention relates to a current sensor that includes an annular core around which a coil is wound, and that detects a current flowing in a primary conductor inserted through the core.

  2. Description of the Related Art Conventionally, a current sensor that includes an annular core around which a coil is wound and that detects a change in current flowing through a primary conductor inserted through the core has been provided (see, for example, Patent Document 1).

  As shown in FIG. 7, the current sensor described in Patent Document 1 includes an annular core 20 and a case 80 in which a coil wound around the core 20 is housed. For example, a toroidal core or the like is used as the core 20. A terminal block 60 is provided along the outer peripheral surface of the core 20. Two connection lines 70 that are electrically connected to both ends of the coil are attached to the terminal block 60.

Japanese Patent Laid-Open No. 11-121259

  By the way, a circuit such as a measurement circuit is connected between both terminals of the coil of the current sensor as described above. Depending on the change in the current flowing through the primary conductor, a voltage exceeding the allowable voltage of the circuit is generated between both ends of the coil and applied to the circuit. In this case, the circuit may break down or malfunction. Therefore, in order to prevent a voltage exceeding the allowable voltage from being applied to the circuit, a voltage limiting element for limiting the output voltage between the two terminals of the coil to be equal to or lower than the allowable voltage of the circuit is connected between the two terminals of the coil. It is possible. For example, a Zener diode 40 is used as the voltage limiting element.

  However, as shown in FIG. 7, when the Zener diode 40 is disposed so as to overlap the core 20 along a center line orthogonal to the opening surface of the core 20 and passing through the center of the opening surface, the thickness of the entire current sensor increases. . Further, when such a current sensor is housed in the case 80, the thickness of the case 80 also increases.

  The present invention has been made in view of the above-described reasons, and an object thereof is to provide a current sensor that includes a voltage limiting element but does not affect the thickness of the voltage limiting element.

The current sensor of the present invention is connected to an annular core made of a magnetic material, a coil wound around the core, and both terminals of the coil, and limits an output voltage between both terminals of the coil to a predetermined voltage. A voltage limiting element that is disposed within a dimension of the core in a direction along a center line that is orthogonal to the opening surface of the core and that passes through a center of the opening surface, and the core is within a plane that is orthogonal to the center line of the core. and a terminal block opposite to the terminal block has a pair of protruding pieces, wherein a pair of projecting pieces central mount Metropolitan provided between the respectively said pair of projecting pieces center between the base, the gap respectively are formed, said voltage limiting element, wherein attached to the central mount, the connecting lines are connected to respective both ends of the coil, characterized in Tei Rukoto is inserted into the gap And

  This current sensor includes a case for housing the core, and it is more desirable that the housing is provided with a housing portion for housing the terminal block in a plane perpendicular to the center line of the core.

  According to the configuration of the present invention, although the voltage limiting element is provided, there is an advantage that the voltage limiting element does not affect the thickness of the current sensor.

It is a perspective view which shows embodiment. It is a front view same as the above. It is a side view same as the above. It is a top view which shows the principal part same as the above. It is a circuit diagram same as the above. It is a perspective view after potting same as the above. It is a side view of a prior art example.

  In the current sensor described below, a coil is wound around an annular core made of a magnetic material, and is configured to detect a change in current flowing through a primary conductor inserted through the core. In this current sensor, when a current flows through a primary conductor, the coil becomes a secondary conductor, and an induced electromotive force is generated between both ends of the coil.

  As shown in FIGS. 1 to 4, in the current sensor of this embodiment, a cylindrical case 81 houses a core 21 made of a magnetic material and a coil 31 (see FIG. 5) wound around the core 21. . In this embodiment, the core 21 uses a toroidal core, for example. Both terminals of the coil 31 are electrically connected to the connection line 71, and the other end of the connection line 71 is electrically connected to the connector 72. The connector 72 is connected to, for example, a measurement circuit 92 (see FIG. 5) that measures a current flowing through the primary conductor 91 inserted through the core 21.

  The core 21 has a rectangular cross section. In addition, a coil 31 is wound around the core 21 so as to alternately pass through the outer side and the inner side of the core 21.

  The current sensor is provided with a disk-shaped core arrangement plate 51. The core arrangement plate 51 has an outer diameter substantially equal to the outer diameter of the core 21, and a circular through hole 52 having a diameter substantially equal to the inner diameter of the core 21 is provided at the center of the core arrangement plate 51. On the core arrangement plate 51, the core 21 is arranged. In addition, a terminal block 61 that electrically connects the connecting wire 71 and the coil 31 is formed continuously and integrally on a part of the periphery of the core arrangement plate 51. The core arrangement plate 51 and the terminal block 61 are made of an insulating material.

  The terminal block 61 is disposed along the outer peripheral surface of the core 21 within the dimension of the core 21 in a direction along the center line perpendicular to the opening surface of the core 21 and passing through the center of the opening surface. It faces the core 21 in a plane perpendicular to it. The terminal block 61 is provided with two Zener diodes 41 and 42 that are voltage limiting elements that limit the output voltage between the two terminals of the coil to a predetermined voltage or less. In the terminal block 61, each connection line 71 connected to both terminals of the coil 31 is also electrically connected to the Zener diodes 41 and 42, respectively. The attachment of the Zener diodes 41 and 42 to the terminal block 61 will be described later.

  At the tip end portion (upper end portion in FIG. 2) of the terminal block 61 in the direction along the center line of the core 21, hooking bases 62 and 63 projecting away from the core 21 are formed at both ends in the circumferential direction of the core 21. Is done. The hooks 62 and 63 have a U-shape in which a cross section perpendicular to the direction along the center line of the core 21 opens in a direction away from each other in the circumferential direction of the core 21. That is, the hooks 62 and 63 have holding grooves 64 and 65 through which the connection line 71 is inserted, respectively. The connection line 71 is drawn out of the terminal block 61 from the holding grooves 64 and 65.

  In the terminal block 61, a protruding piece 66 that protrudes away from the core 21 is formed on the inner side of the hook 21 in the circumferential direction of the core 21. A gap is formed between the hook base 62 and the protruding piece 66 in a direction along the center line of the core 21, and the connection line 71 is inserted through the gap. Similarly, a protruding piece 67 protruding in a direction away from the core 21 is formed on the inner side in the circumferential direction of the core 21 of the hook base 63. A gap is formed between the hook base 63 and the protruding piece 67 in a direction along the center line of the core 21, and the connection line 71 is inserted through the gap.

  In addition, a central stand 68 that protrudes away from the core 21 is formed between the protruding piece 66 and the protruding piece 67. A gap is formed between each of the protruding piece 66 and the protruding piece 67 and the central base 68, and the connection line 71 is inserted through the gap.

  The connection line 71 is electrically connected to the coil 31 and the Zener diodes 41 and 42 in the vicinity of the core placement plate 51 in the terminal block 61 (the lower end portion in FIG. 2). Further, the connection line 71 drawn into the terminal block 61 from the holding groove 64 of the hook base 62 is bent in the circumferential direction of the core 21 at a portion inserted from the holding groove 64 into the gap between the hook base 62 and the protruding piece 66. . Similarly, the connection line 71 drawn into the terminal block 61 from the holding groove 65 of the hook base 63 is bent in the circumferential direction of the core 21 at a portion inserted from the holding groove 65 into the gap between the hook base 63 and the protruding piece 67. The As a result, the terminal block 61 becomes a tension stopper that receives the tension applied to the connection wire 71, and the force is hardly applied to the connection portion of the connection wire 71 to the coil 31 and the Zener diodes 41 and 42.

  The zener diodes 41 and 42 are attached to the central base 68 side by side along the circumferential direction of the core 21. Further, from the Zener diodes 41 and 42, lead wires are drawn out in the direction along the center line of the core 21. One lead wire of the Zener diodes 41 and 42 is drawn out from the center base 68 to one side (upper side in FIG. 2) in the direction along the center line of the core 21, and is electrically connected to each other. The other lead wires of the Zener diodes 41 and 42 are led out from the center base 68 to the other side (the lower side in FIG. 2) in the direction along the center line of the core 21. The other lead wire is overlapped with the connection wire 71 so as to fit on the terminal block 61 in a continuous portion of the terminal block 61 with the core arrangement plate 51 and is electrically connected to the connection wire 71 and the coil 31. Is done.

  The Zener diodes 41 and 42 are attached to the center base 68 of the terminal base 61, and are thus arranged along the outer peripheral surface of the core 21 within the dimension of the core 21 in the direction along the center line of the core 21. Thus, the Zener diodes 41 and 42 do not affect the thickness of the entire current sensor (the dimension in the direction along the center line of the core 21).

  Further, as shown in FIG. 5, the Zener diodes 41 and 42 are connected in series with the polarities opposite to each other. Thereby, even when the change in the current flowing through the primary conductor 91 is large, the circuit connected between both ends of the coil 31 (measurement circuit 92 in FIG. 5) is defined by the breakdown voltage of the Zener diodes 41 and 42. This prevents a voltage exceeding a predetermined voltage from being applied.

  As shown in FIG. 1, the core 21 and the core arrangement plate 51 are accommodated in a case 81 as a unit. The case 81 includes a main body portion 82 whose outer shape is formed in a cylindrical shape and one of the bottom surfaces is open. A part of the outer peripheral wall of the main body portion 82 includes a storage portion 83 that protrudes outward from the main body portion 82 and is formed in a convex shape. The main body portion 82 accommodates the core 21 and the core arrangement plate 51 so that the core arrangement plate 51 faces the bottom wall of the main body portion 82. The terminal block 61 is stored in the storage portion 83, and the connection line 71 is drawn from the opening portion of the storage portion 83.

  As shown in FIG. 6, the inside of the case 81 is potted with an insulating synthetic resin 84 that is filled until it reaches the open bottom surface of the case 81 in order to protect it from external force and moisture. As the synthetic resin 84, for example, an epoxy resin or the like is used.

21 Core 31 Coil 61 Terminal block 81 Case 83 Housing

Claims (2)

An annular core made of a magnetic material;
A coil wound around the core;
A voltage limiting element that is connected to both terminals of the coil and limits an output voltage between the terminals of the coil to a predetermined voltage;
A terminal block that is disposed within the dimension of the core in a direction along a center line that is orthogonal to the opening surface of the core and that passes through the center of the opening surface, and that faces the core in a plane orthogonal to the center line of the core; With
The terminal block has a pair of projecting pieces, the central mount Prefecture provided between the pair of protruding pieces,
A gap is formed between each of the pair of protruding pieces and the central base,
The voltage limiting element is attached to the central platform,
The connecting lines are connected to respective both ends of the coil, a current sensor, wherein the Ru Tei is inserted into the gap. A case for storing the core;
In the case, a storage portion for storing the terminal block protrudes in a plane perpendicular to the center line of the core.
The current sensor according to claim 1.

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