JPH06267759A - Method and structure for fastening gap core - Google Patents

Abstract

PURPOSE:To realize compactness of a frame by making a compression Young's modulus of a spacer interposed to a gap of a central core leg larger than that of a spacer interposed to a gap of core legs of both sides. CONSTITUTION:A gap core 2 wherein yokes 2C, 2D are joined to both sides of three core legs 2A, 2B, 2B with a gap ensured by insulating spacers 4A, 4B is fastened through a connection bolt 3 provided to both ends of a pair of frames 1 holding the core 2. A compression Young's mudulus of the spacer 4A interposed to a gap of the central core leg 2A is made larger than that of the spacer 4B interposed to a gap of the core legs 2B, 2B of both ends. In this constitution, a compression Young's modulus of the spacer 4A is acquired by multiplying a compression Young's rate of the spacer 4B by a ratio of a strain of the spacer 4B to a strain of the spacer 4A. Thereby, a fastening stress applied to each core leg can be made uniform.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and a structure for tightening an iron core with a gap used for a power reactor, a transformer for a reactive power compensator and the like.

[0002]

2. Description of the Related Art FIG. 2 is a diagram showing a conventional structure for tightening a gap core. The iron core legs consisted of three return legs 2B on both sides of the central core 2A, and lower yokes 2C on both sides of this leg,
The upper yoke 2D is joined to form the gap core 2. Insulating gap material 40 for the center leg 2A and the return leg 2B
There is a gap secured in. The gap iron core 2 is sandwiched by the frame 1 and is fastened at both ends of the frame 1 via connecting bolts 3.

In FIG. 2, a gap (not shown) is wound around a center leg 2A which is a main leg of the gap iron core 2, and the magnetic characteristics of the iron core are saturated in the gaps provided in the legs 2A and 2B. Is to prevent. The gap iron core 2 may be wound around each leg 2A and 2B with windings of each phase to form a three-phase three-leg iron core including three main legs.

[0004]

However, the conventional device as described above has a problem that the frame must be thickened. Since both ends of the frame are tightened by the connecting bolts, the central part of the frame tends to be curved. For this reason, the tightening stress applied to the central core leg becomes insufficient as compared with that of the core legs on both sides. If this tightening stress is not tightened to the set value for each leg, vibration and noise of the iron core will increase. Also, vibrations can lead to equipment failure. In order to make the tightening stress of the central core leg the same as that of the core legs on both sides,
In the past, the frame was made thick and large so that it would not bend as much as possible. Therefore, the apparatus becomes heavy and the cost for manufacturing the frame is great.

An object of the present invention is to reduce the size of the frame by using an appropriate gap material for the gap.

[0006]

In order to achieve the above object, according to the method of the present invention, yokes are joined to both ends of three iron core legs having a gap secured by an insulating gap material. A method of tightening a gap iron core formed by a pair of frames holding the iron core with bolts connecting both ends of the frame, wherein the compressive Young's modulus of the gap material interposed in the gap of the central iron core leg is set on both sides of the core. It should be larger than that of the gap material inserted in the leg gap.

Further, according to the present invention, a pair of frames for sandwiching a gap core formed by joining yokes to both ends of three core legs having a gap secured by an insulating gap material. In the tightening structure for tightening via the connecting bolts provided at both ends of the gap material, the compressive Young's modulus of the gap material inserted in the gap of the central core leg is set to that of the gap material inserted in the gap of the core legs on both sides. In such a configuration, the compressive Young's modulus of the interstitial material inserted in the gap of the central core leg is set to be equal to the compressive Young's modulus of the interstitial material inserted in the gaps of the iron core legs on both sides. It is assumed that it is obtained by multiplying the ratio of the strain of the gap material of the core leg to the strain of the gap material of the central core leg.

[0008]

According to the structure of the present invention, the compressive Young's modulus of the gap material interposed in the gap of the central core leg is made larger than that of the gap material of the core legs on both sides. As a result, the central portion of the frame is curved, and even if the amount of compression strain of the gap material of the central core leg is less than that of the gap material of the iron cores on both sides, the tightening stress commensurate with their Young's modulus ratio is It can be added to the iron core leg to increase the tightening stress of the central iron core leg.

In such a construction, the Young's modulus of the interstitial material of the central core leg is set to the compressive Young's modulus of the interstitial material of the core legs on both sides by the strain of the interstitial material of the core legs on both sides and the strain of the interstitial material of the central core leg. Multiplied by the ratio. Thereby, the stress applied to each iron core leg can be made the same.

[0010]

Embodiments will be described below based on embodiments of the present invention.
FIG. 1 is a sectional view showing a structure for tightening a gap core according to an embodiment of the present invention. The compressive Young's modulus of the gap member 4A inserted in the gap of the central leg 2A is made larger than that of the gap member 4B inserted in the gap of the return legs 2B on both sides. The other structure is the same as the conventional one shown in FIG.
The same parts are designated by the same reference numerals, and detailed description thereof will be omitted.

When compressive stress σ is applied to the iron core legs 2A and 2B from the frame 1, the gap members 4A and 4B are respectively subjected to strain of ε (ratio of reduced size to original size). The following equation holds for σ and ε according to Hooke's law.

[0012]

## EQU1 ## σ = Eε where E is the compressive Young's modulus and is a constant that is unique to the gap material. In Equation 1, σ, E, and ε corresponding to the central leg 2A and the return leg 2B are represented by subscript suffixes A and B, respectively,

[0013]

[Equation 2] σ _A = Ε _A · ε _A

[0014]

Mathematical Expression 3 σ _B = Ε _B · ε _B. When the frame 1 bends when the return leg 2B side is tightened by the connecting bolt 3, the strain ε _A of the gap member 4A becomes smaller than the strain ε _{B of the} gap member 4B. Even in that state, if σ _A = σ _B is set in Equations 2 and 3 in order to make the compressive stress on each core leg uniform,

[0015]

## EQU4 ## Ε _A = (ε _B / ε _A ) Ε _B. That is, to the compressive stress applied to each core leg in the same may be assumed that the compressive Young's modulus E _A gap material 4A and multiplying ε _B / ε _A to E _B of the gap material 4B. Increase the tightening stress of the central leg 2A by making Ε _{A of the} interstitial material 4A larger than Ε _{B so} that the characteristics of the interstitial materials 4A and 4B do not strictly satisfy the relationship of the numerical expression 4 and approaching the relationship of the numerical expression 4 as much as possible. You can

Table 1 shows the compressive Young's modulus of the insulating material. As the gap material, one having various compressive Young's moduli can be selected.

[0017]

[Table 1] Although the strain of the gap members 4A and 4B varies depending on the length and size of the frame 1, the frame 1 can be downsized by making each compressive Young's modulus of the gap members 4A and 4B appropriate. Although the embodiment of FIG. 1 is a case where the iron core legs on both sides are return legs, the present invention can be similarly applied to a three-phase three-leg gap iron core.

[0018]

As described above, according to the present invention, the frame can be downsized by increasing the compressive Young's modulus of the gap material of the central iron core leg, and the weight and cost of the device can be reduced. In such a configuration, the compressive Young's modulus of the gap material of the central core leg is multiplied by the compressive Young's modulus of the gap material of the core legs on both sides, and the strain ratio of each gap material is applied to each core leg. The tightening stress can be made uniform, and the optimum design for making the frame as small as possible is possible.

[Brief description of drawings]

FIG. 1 is a sectional view showing a structure for tightening a gap core according to an embodiment of the present invention.

FIG. 2 is a sectional view showing a conventional structure for tightening a gap core.

[Explanation of symbols]

1: Frame, 2: Gap iron core, 2A: Central leg, 2
B: Return leg, 2C: Lower yoke, 2D: Upper yoke, 3: Connection bolt

Claims (3)

[Claims] 1. A bolt for connecting a gap core formed by joining yokes to both ends of three core legs having a gap secured by an insulating gap material, and connecting both ends of a pair of frames sandwiching the iron core. A method of tightening through the gap, wherein the compressive Young's modulus of the gap material provided in the gap of the central core leg is made larger than that of the gap material provided in the gap of the core legs on both sides. How to tighten the gap core. 2. A gap core, in which yokes are joined to both ends of three core legs having a gap secured by an insulating gap material, is provided at both ends of a pair of frames that sandwich the iron core. In a tightening structure for tightening via a connecting bolt, the compressive Young's modulus of the gap material inserted in the gap of the central core leg is made larger than that of the gap material inserted in the gap of the core legs on both sides. Gap iron core tightening structure characterized by. 3. The compression Young's modulus of the interstitial material inserted in the gap of the central core leg is set to the compression Young's modulus of the interstitial material inserted in the gap of the iron core legs on both sides. A tightening structure for a gap core, which is obtained by multiplying the ratio of the strain of the gap material of the core legs on both sides and the strain of the gap material of the central core legs.