JPH08250339A - Low-noise grain-oriented electromagnetic steel plate and laminated core - Google Patents

Abstract

PURPOSE: To further lessen a stationary inductive equipment in noise by a method wherein grain-oriented electromagnetic steel plates are laminated into a laminated core interposing a resin intermediate layer of viscoelasticity between them. CONSTITUTION: Directional elecromagnetic steel plates a and c are laminated into an electromagnetic steel plate interposing a viscoelastic resin intermediate layer b between them. It is preferable due to the simplicity of manufacture that the number of grain-oriented electromagnetic steel plates which form the electromagnetic plate is two. A nongrain-oriented electromagnetic plate whose Si content is 3% or so is usually used as the grain-oriented electromagnetic steel plate. The electromagnetic steel plates each provided with an intermediate resin layer are laminated into an iron core used in a stationary inductive equipment. By this setup, a stationary inductive equipment can be lessened in noise.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a grain-oriented electrical steel sheet and a laminated iron core which produce less noise in a static inductor such as a transformer.

[0002]

2. Description of the Related Art Static inductors such as transformers and reactors are
AC excitation of the iron core causes noise. Due to the increasing number of transformers installed in the city along with the increase in power demand, and the recent trend of environmental importance, it is strongly required to reduce this noise. Possible causes of noise include vibration due to electromagnetic force between exciting coils, vibration due to magnetic force between seams of cores and layers, and vibration due to magnetostriction of electromagnetic steel sheets.

Among these, as a method for reducing the noise from the iron core, for example, by lowering the design magnetic flux density of the iron core, the low magnetostrictive property of the electromagnetic steel sheet at a low magnetic flux density is utilized, or the IEEE Transactions
8 (1972) p. 677 to reduce magnetostriction using a highly oriented grain-oriented electrical steel sheet;
It is known that increasing the tension of the surface film is effective. Noise can also be reduced by limiting the method of tightening the iron core as disclosed in JP-A-47-28419.

Further, as disclosed in JP-A-48-83329, the iron core is surrounded by a sound insulation case,
Noise can also be reduced by disposing the transformer on the anti-vibration rubber as disclosed in JP-A-56-40213.

[0005]

However, the noise reduction of the static inductor by the technique described above is insufficient, and further noise reduction is desired.

An object of the present invention is to provide a grain-oriented electrical steel sheet and a laminated core which can further reduce noise in a static inductor.

[0007]

The grain-oriented electrical steel sheet according to the present invention has a laminated structure in which a resin intermediate layer having viscoelastic properties is sandwiched between a plurality of grain-oriented electrical steel sheets.
It reduces noise in stationary inductors such as transformers.
Moreover, the laminated core of the present invention is manufactured by using the grain-oriented electrical steel sheet.

[0008]

As shown in FIG. 1, the present invention is an electromagnetic steel sheet in which a resin intermediate layer having a viscoelastic characteristic shown by a shaded portion b is sandwiched between a plurality of grain-oriented electrical steel sheets a and c. The number of grain-oriented electrical steel sheets that make up this electrical steel sheet is 2 because of the ease of manufacturing.
The number of sheets is desirable, but it may be three or more in view of the efficiency of iron core lamination work.
A so-called unidirectional electrical steel sheet containing about 3% of Si and having a {110} <001> orientation is used. However, even if the Si content is changed, or a so-called two-dimensional electrical steel sheet having a {100} <001> orientation is used. The use of the grain-oriented electrical steel sheet does not impair the operation of the present invention.

The viscoelastic resin constituting the present invention includes, for example, amorphous polyester, amorphous polyamide, polyimide, polyurethane, polyurethane urea,
There are polyurea, acrylic resin, epoxy resin, vinyl acetate resin, amorphous polyolefin resin, and blends of various resins, but there is no particular limitation.

As a method for producing the laminated electromagnetic steel sheet of the present invention, there are a method using a coater, a method using a spray, and the like, but there is no particular limitation. Further, as a method of filling a resin or the like between the steel plates of the iron core, impregnation of the iron core is considered, but applicability to a large iron core,
This technology is excellent because it is easy to mass-produce industrially.

When a laminated structure having a non-magnetic resin intermediate layer is used, the space factor representing the volume of the magnetic material in the apparent volume when laminated is decreased, and the volume of the iron core and the resistance loss of the winding are increased. May lead to However, as shown in Example 2 (FIG. 2), when the thickness of the intermediate layer is 20 μm or less, a space factor of 90% or more, which is practically satisfactory, is obtained.

The space factor s (%) is 30 mm in width and 2 in length.
It is calculated by the following formula from the stacking thickness when rectangular test pieces of 50 to 300 mm are stacked and sandwiched between two metal plates and a pressure of 3.5 kgf / cm ² is applied. s = 100 · m / (b · L · D · h) m: weight of sample [g] D: density of sample [g / cm ³ ] b: stacking thickness measured by applying pressure [cm] L: Length of sample [cm] h: Width of sample [cm]

The magnetic steel sheets having the resin intermediate layer thus manufactured are laminated to form an iron core used in a static inductor. When this iron core is excited by alternating current and the noise is measured, the electrical steel sheet having the resin intermediate layer exhibits a lower noise than the electrical steel sheet having no resin intermediate layer. Although the principle of this low noise is not always clear, it is considered that the vibration induced in the steel sheet is attenuated by the resin layer and dissipated as heat.

In the excited state, the temperature of the iron core rises due to heat generation of the iron core itself and heat generation of the winding. Therefore, it is desirable that the electrical steel sheet of the present invention exhibits low noise characteristics at temperatures above room temperature. As shown in Example 3, 3
It can be seen that in the temperature range of 0 ° C. or higher and 200 ° C. or lower, the electrical steel sheet having the resin intermediate layer according to the present invention exhibits lower noise than the electrical steel sheet having no resin intermediate layer.

[0015]

【Example】

[Example 1] Laminated iron core consisting of an electromagnetic steel sheet A formed by adhering two 0.3 mm thick unidirectional electromagnetic steel sheets containing 3% Si with a polyester resin sandwiched therebetween and an unbonded unidirectional electromagnetic steel sheet B. The results are shown in Table 1. The thickness of the resin intermediate layer is 10 μm. From the table, it can be understood that the electromagnetic steel sheet of the present invention can improve noise by about 2 dB.

[0016]

[Table 1]

Example 2 Two 0.3 mm-thick unidirectional electrical steel sheets were bonded with a polyester resin sandwiched therebetween. The relationship between the thickness of the resin intermediate layer and the space factor is shown in FIG. It can be seen from FIG. 2 that the resin intermediate layer having a thickness of about 20 μm exhibits a space factor of 90% or more.

[Embodiment 3] Steel sheet A in which two 0.23 mm thick unidirectional electrical steel sheets are bonded together by an epoxy resin intermediate layer.
And a unidirectional electrical steel sheet B having a thickness of 0.23 mm were used to produce a laminated iron core, and the results of noise measurement at temperatures from 30 ° C. to 200 ° C. are shown in Tables 2, 3, 4, and 5. From the table, it can be seen that the laminated iron core using the steel sheet A exhibits low noise in the temperature range of 30 ° C or higher and 200 ° C or lower.

[0019]

[Table 2]

[Table 3]

[Table 4]

[Table 5]

[Example 4] Three 0.3% thick 3% Si layers
Table 6 shows the results of measuring the noise by producing a laminated iron core with a magnetic steel sheet A in which a unidirectional magnetic steel sheet containing a is sandwiched between acrylic resins and bonded, and a non-bonded unidirectional magnetic steel sheet B.
The thickness of the resin intermediate layer is 7 μm.

From the table, it can be seen that the electromagnetic steel sheet of the present invention produces noise of 2
It can be seen that it can be improved by about dB.

[0022]

[Table 6]

[0023]

According to the present invention described above, the noise of the static inductor core can be reduced.

[Brief description of drawings]

FIG. 1 is a sectional structure of an electromagnetic steel sheet of the present invention.

FIG. 2 is a diagram showing a relationship between a resin intermediate layer thickness and a space factor.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yasuo Okazaki 20-1 Shintomi, Futtsu City, Chiba Shin Nippon Steel Co., Ltd. Technology Development Division

Claims (2)

[Claims] 1. A magnetic steel sheet having excellent noise characteristics in a static inductor, comprising a laminated structure in which a resin intermediate layer having viscoelasticity is sandwiched and adhered between a plurality of grain-oriented magnetic steel sheets. 2. A laminated core using the electromagnetic steel sheet according to claim 1 and having excellent noise characteristics.