JPH0745022Y2 - Clamp sensor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a clamp sensor, and more particularly to a clamp sensor that can effectively contribute to improvement of measurement accuracy by a clamp type ammeter.

[Prior Art] A clamp-type ammeter has a clamp sensor formed so as to be able to enclose an electric wire to be measured.

FIG. 2 shows an example of a conventional type of the clamp sensor.

According to this, the clamp sensor of this type is housed and fixed in a pair of shield cases 1 and 2 that can be opened and closed, and in the shield cases 1 and 2 via the casting resins 3 and 4. Formed with the magnetic cores 5 and 6, and when the measured electric wire is introduced and closed, the magnetic cores 5,
6, the magnetic circuit having a substantially rectangular shape can be formed by bringing the butt end surfaces 7 and 8 into close contact with each other.

[Problems to be Solved by the Invention] By the way, since the magnetic cores 5 and 6 need to be firmly fixed at predetermined positions in the shield cases 1 and 2, respectively, the hardness is high and the stress is high. It is necessary to fix with casting resin 3, 4 which is easy to apply. On the other hand, the magnetic cores 5 and 6 formed using a high magnetic permeability magnetic material such as permalloy or ferrite are inevitably reduced in magnetic permeability due to contraction stress when the casting resins 3 and 4 cure. There is a dilemma. At this time, in order to suppress the decrease in magnetic permeability of the magnetic core, when fixing the magnetic core using a soft resin material with a small stress instead of the casting resin, the resin material shrinks due to temperature change. However, there is a disadvantage in that it easily expands or expands, resulting in a magnetic gap between the abutting end faces of the magnetic core, increasing the magnetic resistance, and deteriorating its characteristics.

The present invention has been made in view of the above-described inconveniences of the conventional type clamp sensor, and an object thereof is to provide a clamp sensor capable of press contact for preventing a magnetic gap from being generated between the abutting end faces of the magnetic core. To provide.

[Means for Solving the Problems] This invention is intended to achieve the above object,
Its structural feature is that each of a pair of shield cases that are formed so as to be openable and closable is housed and fixed separately through a resin material so that the abutting end faces of the magnetic cores that are approximately U-shaped are in close contact when closed. And a butt end face formed to have a larger area than the butt end face of the magnetic core that is firmly fixed in the shield case on the other side by the casting resin material. The magnetic core has a spring material interposed between the magnetic core and the shield case on one side in order to apply a pressing force to the other magnetic core in the butt direction, and is a soft rubber-based or urethane-based soft material with low hardness. It is fixed in the shield case via a resin material.

[Operation] Therefore, with respect to the magnetic core having the spring material interposed between the shield case and the shield case, the resin material fixing the magnetic core may have low hardness. It is possible to apply a pressing force to the magnetic core of the magnetic core, so that the butt end surfaces of the magnetic core can be kept in pressure contact with each other when the electric wire to be measured is packaged and measured. The magnetic resistance of the magnetic circuit can be reduced, and highly accurate measurement can be performed.

[Embodiment] An embodiment of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a vertical sectional view showing an embodiment of the present invention,
The clamp sensor that composes the clamp type ammeter contains a pair of U-shaped magnetic cores 13 and 14 that can be opened and closed in order to form a substantially rectangular magnetic circuit when closed. It has a pair of shield cases 11 and 12 formed as described above, and is provided so as to be able to cover the electric wire to be measured. In this case, each of the shield cases 11 and 12 and the magnetic cores 13 and 14 housed therein are made of an appropriate magnetic material having high magnetic permeability such as permalloy or ferrite. Also, a pair of magnetic cores
The magnetic cores 13 and 14 themselves have a substantially U shape in which the height of the magnetic core 13 located on one side, the upper side in the illustrated example, is lowered, and the magnetic core 13 located on the other side, the lower side in the illustrated example. The core 14 is formed in a substantially U-shape with its height increased, and the core 14 can be brought into close contact with each other through the respective butt end surfaces 15 and 16 which are mirror-finished. Moreover, as clearly shown in the drawing, the magnetic core 13 on one side has the abutting end surface 15 of the abutting end surface 15 on the other side.
It is made wider than the area of 16.

Further, the magnetic core 13 on one side, that is, the side of the shield case 11 located on the upper side in the illustrated example, is a shield case.
It is housed in an inner case 17 made of a non-magnetic or magnetic material arranged between the inner bottom surface 18 and the back surface 19 of the magnetic core 13. , A leaf spring or the like for biasing a relative pressing force in the abutting direction with respect to the magnetic core 14 housed in the shield case 12 located on the other side, which is the lower side in the illustrated example. The spring member 20 is disposed. In addition, the magnetic core 13 and the spring material
20 is fixed at a predetermined position by filling the inner case 17 with a soft resin material 21 made of rubber or urethane. Further, a core cover 22 made of an appropriate insulating material such as glass fiber reinforced polycarbonate is provided in the recess of the magnetic core 13.

On the other hand, on the other side, the magnetic core 14 on the side of the shield case 12 located on the lower side in the illustrated example, the core bobbin 25 in a state where the vertical portion 23 is inserted and held, and this core bobbin 25 A coil 24 formed by a winding 26 wound through the coil 24 is disposed. From this coil 24, the base material
The lead wire is taken out through 27 and is connected to the connector 30 attached to the shield case 12. In this way, the casting resin material 29 such as epoxy resin is poured into the shield case 12 in which the magnetic core 14, the coil 24, the base material 27 and the like are arranged at predetermined positions, and is fixed by being cured. It Also, this shield case 12
A core cover 28 made of an appropriate insulating material such as glass fiber reinforced polycarbonate is provided in the recess of the magnetic core 14 fixed inside.

Since the present invention is configured as described above, the magnetic core 13 formed by interposing the spring material 20 between the shield case 11 and the shield case 11 has a soft resin material 21 provided for fixing the magnetic core 13. Because of the low hardness, the pressing force in the abutting direction can be constantly applied to the magnetic core 14 on the other side. For this reason, when attempting to measure the electric wire to be measured in a live state by enclosing it with the magnetic cores 13 and 14, the butt end surfaces 15 and 16 of the magnetic cores 13 and 14 are always in a relative pressure contact state. You can keep them in close contact with each other. Moreover, the butt end surface 15 of the magnetic core 13 on one side is
Since it is formed so as to be larger than the area of the abutting end surface 16 of the magnetic core 14 on the other side, even if the position of one magnetic core 13 is slightly deviated from the position of the other magnetic core 14, the other For the entire butting end surface 16 of the magnetic core 14, the magnetic core 13
The butt end surface 15 on the side of can be intimately contacted. Therefore, the magnetic cores 13 and 14 in a state where the abutting end faces 15 and 16 are abutted against each other can form a magnetic circuit with a low magnetic resistance by reducing the magnetic gap, and can perform an accurate measurement. it can.

[Advantages of the Invention] As described above, according to the present invention, the magnetic core housed in the shield case on one side has a spring material interposed between the magnetic core and the shield case, and has a low hardness. The whole is fixed by using a soft resin material of urethane type or urethane type, and the abutting end face is formed wider than the abutting end face of the other magnetic core, so the shield on the other side when closed Even if there is a slight misalignment with the magnetic core that is firmly fixed by the casting resin material in the case, the butt end face of the other magnetic core should be They can always be brought into close contact with each other, and therefore, magnetic resistance can be reduced and precise measurement can be performed.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing an embodiment of the present invention, and FIG. 2 is a vertical sectional view showing a conventional example. 11,12 …… Shield case, 13,14 …… Magnetic core, 15,16
…… Mating end face, 17 …… Inner case, 18 …… Inner bottom face, 19…
… Back surface, 20 …… Spring material, 21 …… Soft resin material, 22 …… Core cover, 23 …… Vertical part, 24 …… Coil, 25 …… Core bobbin, 26 …… Winding, 27 …… Base material, 28 …… Core cover,
29 …… Casting resin material, 30 …… Connector

Claims (1)

[Scope of utility model registration request] 1. A pair of shield cases, which are formed so as to be openable and closable, respectively, and each of which has a substantially U-shaped magnetic core is separately accommodated and fixed via a resin material so that the abutting end surfaces of the magnetic cores come into close contact with each other when the shield is closed. In the clamp sensor, the one magnetic core having the abutting end face formed to have a larger area than the abutting end face of the magnetic core firmly fixed in the shield case on the other side by the casting resin material is It has a spring material interposed between the other magnetic core and a shield case on one side in order to apply a pressing force in the abutting direction, and through a low hardness rubber-based or urethane-based soft resin material. Clamp sensor characterized by being fixed inside the shield case.