JPH0687067B2 - Magnetic detection device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic detection device such as a distribution line current monitoring sensor, and a sensor for detecting the strength of a circular magnetic field has a minimum magnetic field strength distribution that minimizes a magnetic field strength error. Alternatively, the present invention provides a magnetic detection device that can be installed accurately and efficiently at the maximum point.

2. Description of the Related Art A conventional magnetic detection device has a C-shaped core 5 as shown in FIG.
A magnetic field (not shown) is installed in the gap 50 to detect the magnetic flux in the core 5, that is, the magnetic field. When locating the position of the sensor, there is a method of measuring the magnetic field intensity distribution and observing the point where the intensity change is the minimum, and then installing the sensor. However, this method is extremely cumbersome and impractical to install the sensor. l ₂ is the center line of the core and l ₃ is the center line of the end face. Therefore, there is a method in which the setting position of the sensor is set to the center 40 of the gap 50 where the magnetic field strength distribution does not maximize in the radial direction of the core 5, and the sensor is installed here. This is prepared by fitting the sensor case 2 with the sensor attached in advance to the gap 50, and installing the case 2 in the gap 50 between the flat end faces 20 and 21. The latter method is usually the center of the gap 40
Does not become the maximum point of the magnetic field strength distribution, resulting in a detection error. It is considered that the above-mentioned center 40 does not coincide with the maximum point because the end faces 20 and 21 of the core are parallel to each other.

According to the conventional method, since the maximum value of the magnetic field strength distribution in the radial direction on the gap center line l _{1 of the} core does not come to the gap center 4 as shown in FIG. It is necessary to know the position where the error due to the change of the magnetic field strength is minimum. Also, even if the position is known, it is a halfway position unlike the center of the gap, which is very inefficient in the sensor installation work.

On the contrary, in order to efficiently proceed the sensor installation work as described above, if the sensor installation position is set to the center of the gap and the case 2 is installed, the gap center 40 has a large magnetic field strength change as shown in FIG. Even if the sensor positioning accuracy is increased, the error due to the change in magnetic field strength cannot be ignored.

The present invention solves the above-mentioned problems of the conventional one, and provides a maximum magnetic field strength at the center of the core gap to provide a magnetic detection device capable of accurately and efficiently installing the sensor at the center of the gap. The purpose is to

Means for Solving the Problems To achieve the above object, in the radial direction on the gap centerline of the core, the maximum magnetic field strength is located at the midpoint between the outer diameter and the inner diameter of the core of the gap, The magnetic sensor is installed in the vicinity of the midpoint, and the device can be easily formed by using a sensor case that matches the shape of the gap.

In a preferred example of the present invention, the C-shaped core consists of two non-parallel gap faces. The two gap planes are symmetrical with respect to the gap centerline. Regarding the angle formed by the gap surfaces, the two gap surfaces are slightly widened so that the maximum magnetic field strength is located at the center of the gap in the radial direction on the gap center line.

On the other hand, the sensor case has the same shape as the core gap, the head of the case is located on the core inner diameter, and has a unique position in the radial direction. The sensor is
In the sensor case, the position at the specific position is fixed to the position that is the center of the core gap.

Action When using the C-shaped core as described above, there is always a point of maximum magnetic field strength at the center of the gap in the radial direction on the gap centerline, so it is necessary to measure the magnetic field strength distribution in the gap before installing the sensor. Disappear. Also, since there is always a point with the smallest rate of change in magnetic field strength in the center of the gap,
The error due to the rate of change of the magnetic field strength can be minimized by placing the sensor at the center of the gap where positioning is easy.

Furthermore, the sensor case has the same shape as the core gap,
Since it has a unique position in the gap, it is possible to easily and efficiently install the sensor while maintaining high accuracy and high reproducibility.

Embodiment An embodiment of the present invention will be described with reference to FIG. 1, FIG. 2, and FIG. In the present embodiment, as shown in FIG. 1, the end faces 10 and 20 of the core ₁ are symmetrical with respect to the gap center line l ₁ and non-parallel to each other, and are slightly spread outward.
A gap 15 is formed between 0 and 20. Face of gap 15
The angle formed by 10, 20 depends on the width of the gap 15, and can be determined by calculation or simple experiment. That is, by appropriately selecting the angles of the surfaces 10 and 20, the center of the gap and the point of the minimum magnetic field strength change rate can be matched. FIG. 2 shows the magnetic field strength distribution in the radial direction on the gap center line l _{1 of the} core shown in FIG. FIG. 2 shows that the magnetic field strength is maximum and the magnetic field strength change rate is minimum at the gap center 4. This can be realized by making the end faces 10 and 20 non-parallel at an appropriate angle as described above. Therefore, the gap
The sensor case 2 may be prepared in accordance with 15, and the sensor 3 may be installed in the case 2 so as to come to the center 4 or the vicinity thereof. For example, the sensor case 2 has a trapezoidal shape having the same shape as the core gap 15, and the center side thereof may be matched with the inner diameter, and the magnetic sensor 3 occupies a proper position (center 4) in the gap 15. As described above, the sensor 3 is fixed in advance within the sensor case 2 at a position where its unique position is the core gap center 4. If the sides 21 and 22 of the case 2 are aligned with the end faces 10 and 20 and the side 23 is aligned with the inner diameter of the core 1, the assembly is easy.

EFFECTS OF THE INVENTION As is apparent from the above description, according to the present invention, it is possible to provide the gap surface so that the maximum magnetic field strength is located at the center of the gap in the radial direction on the gap centerline of the core, and the sensor is fixed inside. By giving a unique position to the sensor case in the gap, it is possible to easily and efficiently install the sensor at a position where the error due to the magnetic field strength change rate is minimized while maintaining high accuracy and high reproducibility.

[Brief description of drawings]

1 (a) and 1 (b) are a side view and a front view of a C-shaped core portion in an embodiment of the present invention, and FIG. 2 is a radial magnetic field strength distribution diagram on a gap center line in the embodiment, 3 (a) and 3 (b) are a side view and a front view of a conventional gap surface parallel C-shaped core, and FIG. 4 is a radial magnetic field strength distribution diagram on the gap center line of the conventional C-shaped core. 1 ... C-shaped core, 2 ... sensor case, 3 ... sensor, 4 ... gap center, 10, 11 ... end face.

Claims (2)

[Claims] 1. A maximum magnetic field strength is located at a midpoint between the outer diameter and the inner diameter of the core in the radial direction on the center line of the gap of the core, and a magnetic sensor is installed in the vicinity of the midpoint. Magnetic detection device characterized by. 2. The magnetic detection device according to claim 1, wherein a sensor case having a shape of a gap is used.