JPH0869922A - Laminated iron core for transformer - Google Patents

Abstract

PURPOSE: To obtain a laminated iron core for transformer which can suitably reduce clamping noise by clamping the entire body of the yoke section of a transformer, can prevent its characteristic from being deteriorated by an iron loss, and can be more efficiently cooled. CONSTITUTION: A laminated core for transformer is constituted by clamping the yoke section 1a of a transformer with clamping fittings 3 by using studs 4 and nuts 5 so that the central part of the yoke section 1a can be made thicker than both end leg parts 1b of the section 1a by respectively putting iron core plate layers 2 between the section 1a and fittings 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transformer, and more particularly to a transformer using an iron core formed by laminating silicon steel sheets.

[0002]

2. Description of the Related Art Conventional transformer cores are fastened with uniform pressure to fasten the yoke parts of the cores with fasteners.
After drilling the iron core, tighten it with stud bolts and nuts. In addition, the technique disclosed in Japanese Patent Laid-Open No. 47-28419 uses a pre-bent fastener, and an insulating plate is interposed between the iron core and the fastener. Regarding the iron core, JP-A-2-117111 discloses a structure in which a part of the iron core is thickened to reduce the magnetic flux density. Further, Japanese Utility Model Application Laid-Open No. 53-98916 discloses that an insulating material spacer is sandwiched and clamped between a central portion of a laminated core yoke portion and a fastener. These prior arts aim to reduce noise and prevent deterioration of characteristics due to iron loss by tightening the iron yoke part of the iron core with a uniform pressure. The technique disclosed in Japanese Patent Laid-Open No. 51-110621 has spacers provided between the iron core clamps, but it was made in expectation of a cooling effect.

[0003]

Although the above-mentioned prior art is partially effective, it simultaneously satisfies the uniform tightening of the yoke portion and the improvement of the laminated structure of the iron core, thereby reducing noise and reducing iron loss. It was not possible to say that a sufficient effect was obtained as a whole in terms of preventing the deterioration of properties due to, and expecting the cooling effect of the iron core if necessary. The purpose of the present invention is to improve the loss characteristics by reducing the magnetic flux density of the yoke portion, which is said to have the largest iron loss and magnetostriction amount in the transformer core, and to improve the loss characteristics of the entire yoke portion of the transformer with a uniform pressure. The purpose of this is to reduce tightening and noise, prevent deterioration of characteristics due to iron loss, and if necessary, improve cooling performance of the laminated core.

[0004]

In order to achieve the above object, the first invention is to use the same iron core material to make the product thickness of the central portion of the yoke portion of the transformer product iron core thicker than both end portions. do it,
The cross section of the yoke portion orthogonal to the axis of the coil attached to the leg iron portion is configured to have a central height, and then the yoke portion is fastened by using fasteners. According to a second aspect of the present invention, a duct that penetrates along the coil axis direction is provided in the iron core yoke portion, and the cross section of the yoke portion is formed to have a central height. Third
The invention of No. 1 has a configuration in which a damping steel plate is interposed in place of the penetrating duct.

[0005]

With the above structure, that is, the yoke portion of the transformer core is thicker than the both ends, when the both ends are tightened by using the fasteners, the central part becomes loose. It is possible to uniformly fasten the yoke portion of the laminated core without causing FIG. 4 is a diagram showing an iron loss ratio of a three-phase three-leg portion of a laminated iron core according to the present invention. In FIG. 4, assuming that the iron loss in the straight line portion 6 is 100%, it is known that 120% in the corner portion 7 and 190% in the joint portion 8 between the yoke portion and the central leg occur. ing. This is to make the iron core,
Since an iron plate for an iron core cut into a predetermined shape and dimensions is assembled with its cut surfaces abutting, a complicated magnetic circuit is formed in the portions of reference numerals 7 and 8, so that many losses such as eddy current loss occur. It can be considered as a cause. Similarly, regarding noise, it is known that the amount of magnetostriction in the portions denoted by reference numerals 7 and 8 is larger than that in the portion denoted by reference numeral 6. Therefore, by reducing the magnetic flux density at the joint between the yoke portion and the central leg of reference numeral 8, it is possible to expect a reduction effect on iron loss and noise. In the case of three or more laminated cores using a yoke part where the laminated thickness of the central part is thicker than both ends, increase the laminated thickness of the joint part of the yoke part and the central leg with the largest iron loss and magnetostriction amount. Since the cross-sectional area is increased, the magnetic flux density at this portion is reduced, and iron loss and noise are reduced.
Unlike the conventional iron core, the central part is not loosely tightened. Further, when a duct is used, air flows in the duct to cool the iron core, and when a damping steel plate is used instead of the duct, vibration energy can be exchanged for heat energy and noise can be reduced.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a transformer core according to the present invention will be described below with reference to the drawings. The following examples are each 1000 KVA
It is a transformer, and the actual size of the iron core is about 1300 mm wide,
Height about 1300mm, thickness about 200mm, weight about 1700kg
The example applied to is described. <Embodiment 1> FIG. 1 is a perspective view of Embodiment 1 showing a fastening state of a transformer core according to the present invention, FIG. 2 is a top view thereof, and FIG. 3 is a perspective view of the core core. Example 1 is a yoke portion 1 of a laminated core 1.
The core plate layer 2 is provided in order to increase the stack thickness of the central portion of a. As a result, when the pair of fasteners 3 and 3 are fastened by the stud bolt 4 and the nut 5, the entire iron core can be fastened with a uniform pressure.
Here, it is preferable to use the grain-oriented silicon steel plate of the same material as the core 1 as the material of the iron-core plate layer 2, but a non-oriented silicon steel plate may be used, and it is also conceivable to use an amorphous magnetic material.

<Second Embodiment> FIG. 5 is a perspective view of a transformer core according to a second embodiment of the present invention, and FIG. 6 is a top view showing the same fastening state. As shown in FIG. 5, in the second embodiment, only the central leg has an increased stacking thickness. Also in this case, the first embodiment
Although the effect similar to that is obtained and the work is simplified, as is clear from FIG. 6, there is a gap S between the laminated core 1 and the fastener 3.
Therefore, it is sometimes preferable to insert an iron core plate or an insulator in the S portion. In this case, since the magnetic flux flows in a direction perpendicular to the rolling direction of the silicon steel sheet with respect to the product increment of the yoke portion 1a, it is preferable to add the non-oriented silicon steel sheet.

<Embodiment 3> FIG. 7 is a perspective view showing a fastened state of a transformer core according to Embodiment 3, and FIG. 8 is a top view of the same. As shown in the drawing, the third embodiment is an embodiment in which an iron core plate layer 2 is inserted in a sandwich shape in the middle of the iron core layer of the yoke portion 1a. FIG. 9 is a front view of the same transformer core. In this embodiment, the same effect as in the first and second embodiments can be obtained.
As shown in FIG. 9, the magnetic flux is the most difficult to flow at the moment when it flows in the yoke portion 1a in the direction of the arrow A, and causes a noise and an increase in loss. As is clear from FIG. 3, the iron plate constituting the yoke portion 1a has a V-shaped notch portion 10 at the joint portion with the central leg portion 1c, which is a cross-section of silicon steel plates having different rolling directions. Since it is caused by the above, it becomes difficult for the magnetic flux to flow in the cutout portion 10 at the moment when the magnetic flux passes as shown by the arrow A, which causes noise and iron loss.
In the embodiment of FIGS. 1 and 7, a rectangular iron core plate layer 2 is added to the notch portion 10, and by passing the iron core plate layer 2, magnetic flux can easily pass through the notch portion 10. It is effective in reducing noise and iron loss. Particularly in the third embodiment, as compared with the first embodiment, the outer iron plate that constitutes the yoke portion 1a is not provided with a notch, and a single plate that directly connects the both leg portions 1b and 1b to the central leg portion 1c. It is effective in reducing noise and iron loss. As an application of this embodiment, the iron core plate layer 2 may be formed between the laminated iron cores as shown in FIG. 10, but the resonance of the iron core must be avoided in any addition.

<Fourth Embodiment> Next, a fourth embodiment will be described with reference to FIGS. The present embodiment is the first to third embodiments.
In this embodiment, a pipe-shaped duct 10 or a corrugated duct 11 is provided in place of the iron core plate layer 2, and a laminated iron core is provided with a space in which air flows. The duct may be provided between the laminated iron cores or between the laminated iron cores and the fasteners, and the duct may have a pipe shape as shown in FIG. 11 or a corrugated shape as shown in FIG. Although not limited to the shape, the material and the structure need to have the strength to withstand the pressure when fastening the iron core. Further, in order not to increase iron loss, it is preferable to use a non-magnetic material. In addition, when the duct is inserted between the core laminations, both leg portions 1b and central leg portion 1c
The cross section is separated into two layers of laminated core. As a result, the entire yoke portion 1a of the laminated core can be tightened with a uniform pressure, and a cooling effect of the laminated core can be obtained.

<Fifth Embodiment> FIG. 13 is a top view showing a fastened state of a transformer core according to a fifth embodiment. Example 5 is
This is an example of increasing the thickness of the iron core by using a damping steel plate.
As shown in FIG. 15, the damping steel plate 12 has a thickness of 0.05 mm to 0.
It is a sandwich type steel plate in which a damping resin 14 having a thickness of 2 mm is sandwiched between two steel plates 13, and is a material suitable for damping vibration and reducing noise of equipment. FIG. 14 is a diagram showing an example of a relational characteristic between the use temperature of the damping steel plate and the loss coefficient η, and the damping property of the damping steel plate is usually represented by the loss coefficient. As shown in the figure, at the vibration frequency to be applied, depending on the temperature rise of the iron core and the usage environment, for example,
Since there are differences in characteristics such as product number C20 or C60, it is necessary to select a suitable product number depending on the usage conditions. In addition, it is effective to select the product number of the damping steel plate that adapts to the frequency used and minimizes the loss coefficient after considering the noise and frequency characteristics of the transformer. Also, the damping steel plate 12
The application may be performed between the laminated iron core 1 and the fastener 3 as in the first embodiment of FIG. 2 or between the laminated layers of the laminated iron core as in the third embodiment of FIG. In order to utilize the performance of the vibration damping steel plate 12 more effectively, it is preferable to disperse the vibration damping steel plate 12 as shown in FIG. In this case, by using a silicon steel plate instead of the ordinary steel plate 13 shown in FIG. 15, it is possible to obtain a transformer core having a structure capable of enhancing both magnetic properties and soundproof properties, which is extremely convenient. .
Further, by using the damping steel plate as the duct material in the fourth embodiment, it is possible to obtain a transformer core having excellent cooling effect and noise prevention effect by the duct.

The effect of the present invention is not restricted by the size and weight of the iron core as shown in the above embodiment, but when applied to the iron core having the above size and weight, for example, there is a noise reduction effect of 3 dB to 4 dB. , Also, because the noise is reduced,
If the magnetic flux density is increased so as to be equal to the noise value before reduction, the iron core weight can be reduced by about 3%. Furthermore, although each of the above-mentioned embodiments has been described with respect to a three-legged iron core, it is needless to say that the same effect can be obtained with three or more iron cores, and the present invention can also be used in the case of two legs.

[0012]

As a result of implementing the present invention, it is possible to increase the product thickness of the joint portion between the yoke portion and the central leg portion, which has the largest iron loss and is not pierced in the iron core to be assembled as in the prior art. By doing so, it is possible to realize a transformer structure that is extremely effective in reducing noise and reducing loss because the magnetic flux density is reduced due to the effect of tightening the entire core yoke part with uniform pressure and the part where the product thickness increases. You can In addition, a structure in which a part having an increased product thickness is formed through a duct, or a structure using a damping steel plate for the part having an increased product thickness, and a structure using a damping steel plate for the duct are used. By providing various combinations and changes in the formation of the increased portion, the cooling effect of the iron core is added, and it is possible to provide a transformer iron core that is extremely effective in reducing noise, reducing loss, and improving temperature characteristics. You can

[Brief description of drawings]

FIG. 1 is a perspective view of a first embodiment showing a fastening state of a transformer core according to the present invention.

FIG. 2 is a top view of FIG.

FIG. 3 is a perspective view of a first embodiment of a transformer core according to the present invention.

FIG. 4 is a diagram showing a three-phase three-leg iron loss ratio of a laminated iron core.

FIG. 5 is a perspective view of a transformer core according to a second embodiment of the present invention.

FIG. 6 is a top view of a second embodiment showing a fastening state of the transformer core according to the present invention.

FIG. 7 is a perspective view of a third embodiment showing a fastening state of a transformer core according to the present invention.

FIG. 8 is a top view (a) and a leg cross-sectional view (b) of FIG. 7.

FIG. 9 is a diagram showing a direction in which magnetic flux of the transformer laminated core of the present invention is hard to flow.

FIG. 10 is a top view (a) and a leg sectional view (b) of an application example of the third embodiment showing a fastening state of the transformer laminated core of the present invention.

FIG. 11 is a top view (a) and a leg cross-sectional view (b) of Example 4 showing a tightened state of the transformer core according to the present invention.

FIG. 12 is another top view (a) and a leg cross-sectional view (b) of the fourth embodiment showing the fastening state of the transformer core according to the present invention.

FIG. 13 is a top view (a) and a leg section cross-sectional view (b) of Example 5 showing a fastening state of a transformer core according to the present invention.

FIG. 14 is a characteristic diagram showing the relationship between the operating temperature of the damping steel sheet and the loss coefficient.

FIG. 15 is a cross-sectional view showing the structure of a vibration damping steel plate.

[Explanation of symbols]

1 ... Laminated core 2 ... Iron core plate layer 1a ... Yoke part 1b ... Both leg parts 1c ... Central leg part 3 ... Tightening metal fitting 4 ... Stud 5 ... Nut 6 ... Straight part 7 ... Corner part 8 ... Joining part 9 ... Cut Notch 10 ... Pipe-shaped duct 11 ... Corrugated duct 12 ... Damping steel plate 13 ... Steel plate 14 ... Damping resin

Claims (3)

[Claims] Claim: What is claimed is: 1. A transformer laminated core comprising a stack of steel plates, comprising a yoke portion having a central product thickness dimension at least larger than both end legs of the transformer, and pressing the yoke portion using fastening means. A transformer laminated iron core, which is characterized by being fastened to each other. 2. The transformer product according to claim 1, wherein the yoke portion having a large central product thickness dimension has a duct penetrating the yoke portion along a coil axis direction of the transformer. Iron core. 3. The central laminated thickness dimension is increased by interposing a damping steel plate in the yoke portion.
The listed transformer core.