JPH0725704Y2 - 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 effective for equalizing the temperature characteristics of a clamp-type ammeter in relation to linear expansion. .

[Prior Art] A clamp-type ammeter is configured to include a splittable clamp sensor formed so as to be able to enclose a measured electric wire in a live state.

FIG. 4 shows an example of a conventional type of the clamp sensor.

According to this, a clamp sensor of this type is housed in a pair of shield cases 1 and 2 that can be opened and closed and a casting resin material 5 and 6 in the shield cases 1 and 2. It is formed with the fixed magnetic cores 3 and 4, and when the measured electric wire in a live state is introduced and externally wrapped,
The magnetic cores 3 and 4 are capable of forming a magnetic circuit having a substantially rectangular shape by bringing their abutting end faces into close contact with each other.

In this case, the clamp sensor has a positional relationship such that the shield cases 1 and 2, the magnetic cores 3 and 4, the casting resins 5 and 6, and the core holders 7 and 8 come into contact with each other when the clamp sensor is closed. Is formed. By the way, the materials that make up each of these members have a linear expansion coefficient (cm / cm °
C) is different, and the details are as shown in the table below.

In other words, the linear expansion coefficient of each component differs greatly depending on the material used, and due to changes in the ambient temperature, the components such as the shield cases 1 and 2 also have different expansion coefficients. There is a problem that the characteristics are deteriorated due to the deformation due to the deformation, resulting in the formation of minute voids on the respective contact surfaces. FIG. 5 shows the measurement result obtained by the conventional type clamp sensor shown in FIG. 4, and it is found that the measurement value has a negative error in relation to the temperature at the time of measurement.

On the other hand, FIG. 6 is a vertical cross-sectional view showing the structure of another clamp sensor provided in order to solve the above-described inconvenience that may occur in the clamp sensor of the type shown in FIG.

According to this, regarding the casting resin materials 5 and 6 having the highest linear expansion coefficient among the constituent members such as the shield cases 1 and 2,
From the viewpoint of reducing the contact surface as much as possible, the concave portions 9 and 10 are provided and arranged so as to be able to cope with the above-mentioned inconvenience caused by a change in ambient temperature.

[Problems to be Solved by the Invention] By the way, as shown in FIG. 6, by providing concave portions 9 and 10 in the casting resin materials 5 and 6, respectively, as far as the contact surface is concerned, It is possible to temporarily eliminate the factor that causes a gap between the abutting end surfaces of the magnetic cores 3 and 4.

However, since the core holders 7 and 8 themselves are still in contact with each other, there is an inconvenience that the core holders 7 and 8 are deformed according to the change in ambient temperature, which deteriorates the characteristics as shown in FIG. Has arrived. Moreover, forming the recesses 9 and 10 in the casting resin material 5 and 6 makes it difficult to control the casting amount, which not only deteriorates workability but also affects the temperature characteristics thereof. Was also a major factor causing variations.

The present invention has been made in view of the above-described inconveniences that exist in conventional clamp sensors, and its purpose is to eliminate as much as possible a factor that causes a magnetic gap between the abutting end faces of the magnetic core. To provide a sensor.

[Means for Solving the Problems] This invention is intended to achieve the above object,
Its structural feature is that each of the magnetic cores housed separately in a shield case that is openably and closably divided to form a substantially rectangular magnetic circuit by a pair of magnetic cores has an exposed side of these magnetic cores. Is a clamp sensor that is fixed by a casting resin material filled in a space formed between the shield case and the core holder disposed in the recessed portion as a dam plate, wherein each of the core holders is ,
The height of the top surface of the magnetic core is lower than the height of the abutting end surface of the magnetic core.

[Operation] For this reason, the casting resin material forms a recessed portion under the surface height regulated by the height of the top end surface of the core holder, and the casting amount in each shield case. It can be easily filled while controlling.
Further, it is possible to prevent inconvenience that the core holder is deformed due to the change of the ambient temperature and a portion protruding from the abutting end surface of the magnetic core is generated. It is possible to reduce the factors that cause it, and as a result it is possible to make the temperature characteristics of the measured values uniform.

[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 constitutes the clamp-type ammeter has a pair of U-shaped magnetic cores 13 and 14 that are individually accommodated and fixed to form a substantially rectangular magnetic circuit when closed.
In addition, it has a pair of shield cases 11 and 12 that can be opened and closed with respect to each other, and is provided so as to be able to enclose the measured electric wire in a live state. 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.

Further, the pair of magnetic cores 13 and 14 themselves have a substantially U shape in which the height of the magnetic core 13 located on one side, that is, on the upper side in the illustrated example is lowered (shallow), and on the other side, in the illustrated example. According to this, the magnetic core 14 located on the lower side is formed in a substantially U-shape with its height increased, and the magnetic cores 14 can be brought into close contact with each other through the butt end surfaces 15 and 16, respectively.

Further, the core holders 17 and 18 made of an insulating resin material, which are disposed in the recesses on the exposed side of the magnetic cores 13 and 14, respectively, have the heights of the abutting end surfaces 15 and 16 of the magnetic cores 13 and 14, respectively. On the other hand, it is arranged so as to function also as a weir plate having a reduced top surface height. Therefore, the shield case on one side,
In the illustrated example, the casting resin material 19 filled in the space formed between the shield case 11 located on the upper side and the corresponding core holder 13 has a concave portion 27 formed on the top surface thereof. Moreover, the magnetic core 13 can be arranged in the shield case 11 without protruding from the abutting end surface 15 of the magnetic core 13.

On the other hand, in the shield case on the other side, that is, in the illustrated example, the magnetic core 14 on the side of the shield case 12 located on the lower side has a core bobbin 22 in which the vertical portion 20 is inserted and retained.
And a coil 21 formed of a winding wire 23 wound around the core bobbin 22. From this coil 21, the lead wire is taken out through the base material 24,
It is connected to the connector 26 attached to the shield case 12. In this case, the core holder 18 disposed in the concave portion on the exposed side of the magnetic core 14 functions as a dam plate whose top surface height is lower than that of the abutting end surface 16 of the magnetic core 14. So this core holder 18 and shield case
Resin material for casting filled in the space formed between 12 and
Similarly to the one shield case 11, the 25 can be disposed in the shield case 12 without forming a recess 28 and protruding from the abutting end face 16 of the magnetic core 14.

Since the present invention is configured as described above, both of the casting resin materials 19 and 25 filled to fix the magnetic cores 13 and 14 in the respective shield cases 11 and 12 are The core holders 17 and 18 can be used as barrier plates and can be arranged very easily under the condition that the surface height thereof is lower than the height of the abutting end surfaces 15 and 16 of the magnetic cores 13 and 14.

Therefore, due to the change of the ambient temperature, the core holder 17 having a different linear expansion coefficient than the butt end surfaces 15, 16 of the magnetic cores 13, 14,
It is possible to prevent the occurrence of the inconvenient situation that the 18 and the casting resin material 19,25 are projected, and the magnetic core 13,1
The butt end surfaces 19 and 25 of 4 can be closely contacted. Therefore, it is possible to reduce the factors that cause an undesired air gap in the magnetic circuit formed by the magnetic cores 13 and 14, and suppress the generation of the magnetic resistance, so that the temperature characteristics shown in FIG. Uniform measurement accuracy can be obtained.

[Effects of the Invention] As described above, according to the present invention, even if deformation such as distortion may occur between members having different linear expansion coefficients due to changes in ambient temperature, the core holder and the casting resin material Since it can be arranged without protruding from the abutting end faces of the magnetic core, it is possible to obtain a more preferable close contact state by reducing the factors that cause a gap between the abutting end faces of the magnetic core. it can. Therefore,
The temperature characteristics of the clamp sensor itself can be made uniform, which can contribute to improving the reliability of measurement accuracy.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of the present invention, FIG. 2 is a transverse sectional view of the same, and FIG. 3 is a graph showing temperature characteristics obtained by the embodiment shown in FIG. 4 is a vertical sectional view showing a conventional example, FIG. 5 is a graph showing temperature characteristics obtained by the conventional example of FIG. 4, FIG. 6 is a vertical sectional view showing another conventional example, and FIG. The figure is a graph showing the temperature characteristics obtained by the conventional example of FIG. 11,12… Shield case, 13,14… Magnetic core, 15,16… Butt end face, 17,18… Core holder, 19… Casting resin material, 20
… Vertical part, 21… Coil, 22… Core bobbin, 23… Winding, 24
… Base material, 25… Casting resin material, 26… Connector, 27, 28
... recess

Claims (1)

[Scope of utility model registration request] 1. A magnetic core housed separately in a shield case that is openably and closably divided so as to form a substantially rectangular magnetic circuit by a pair of magnetic cores, which are exposed sides of these magnetic cores. In a clamp sensor in which a core holder disposed in a recess is used as a barrier plate and fixed by a casting resin material filled in a space formed between the shield case and the shield case, each of the core holders includes the magnetic core. The clamp sensor is characterized in that the height of the top surface of the clamp sensor is lower than the height of the butting end surface of the clamp sensor.