JPS5939888B2 - Tank for oil-filled electrical equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a tank for oil-filled electrical equipment such as a transformer, and more particularly to a corrugated radiator.

In general, oil-filled electrical equipment such as transformers consists of a tank part that houses the main body of the electrical equipment, and a radiator that releases heat generated by operating the transformer to the outside. Wave-shaped heat dissipation has good heat dissipation effect as a container, has excellent productivity such as the wave height and pitch of the wave-shaped heat dissipation ribs can be freely selected, and has advantages such as being able to obtain a free heat dissipation area in the heat dissipation design of transformers, etc. Many instruments are used.

FIG. 1 is a perspective view of a tank for oil-filled electrical equipment using the above-mentioned corrugated radiator. Generally, the tank has an upper frame 1, a corrugated heat-radiating rib, and a corrugated radiator 2 which also serves as the side wall of the tank. , consists of a lower frame 3 integrated with the bottom plate, supports, legs, etc. (not shown).

FIG. 2 is a perspective view of the above-mentioned corrugated heat sink 2. The corrugated heat sink 2 is made by sequentially bending a thin steel plate into a corrugated shape, and the upper and lower ends 2b of the corrugated rib peaks 2a are formed into corrugated ribs at regular intervals.
The ribs 2a are pressed together by drawing and sealed by arc welding, for example, to form a necessary number of consecutive rib ridges 2a each having a bag-shaped oil passage 2c formed in the center. 3 shows a cross section of the rib peak 2a in FIG. 2 on the y-2 plane, and FIG. 4 is a partial perspective view of the corrugated heat sink 2, including a partial cross section of the rib peak 2a in FIG. 2. . By the way, when both ends 2b of the rib ridge 2a are simply pressed with a mold, the material is greatly expanded at both ends 2d of the bottom surface of the rib ridge shown in FIG.

In other words, if we assume that the R dimension of the rising corner of the rib crest does not change even after pressing with a mold as shown in Fig. 4, the average amount of strain ε due to elongation of the material will be ε at both ends 2d of the bottom surface of the rib crest.
= is. Here, w■(p-w) oil road width, p: road distance between adjacent mountains.

Furthermore, due to product or manufacturing reasons, the R dimension of the rising corner of the rib crest cannot usually be made very large, so when pressing with a mold, the surface pressure near the rising corner of the rib crest becomes extremely high.
It becomes impossible for the material to be stretched uniformly. FIG. 5 shows this state. Before pressing both ends 2b of the rib ridge 2a with a mold, ``baseline grating lines are placed in advance at equal intervals vertically and horizontally near the rising corners of the rib ridge. After that, it is pressed with a mold and if you look at the condition of the ruled lines, it is clearly seen that the material is largely loosed in the y direction, especially near the rising corners of the rib peaks. Of course, this local elongation leads to a decrease in the plate thickness in this area, and as shown in Figure 5, it is often accompanied by cracks of 2g, which can cause oil leaks from directly oil-filled electrical equipment tanks, and reduce the resistance. This is a factor that leads to a decline in corrosion performance, and to prevent this, it is necessary to use expensive materials such as deep drawing steel plates. Next, as shown in Figure 6, the flow of insulating oil in an oil-filled electrical equipment tank is generally warmed by the heat generated from the contents of the electrical equipment, becomes lighter, rises to the top of the tank, and eventually forms a waveform. It flows into the oil pipe 2c of the radiator 2, moves down the oil pipe 2c while being cooled, and flows to the bottom of the tank, repeating natural convection.

In this case, when the warmed insulating oil flows from the top of the tank to the oil pipe 2c of the corrugated radiator 2, as shown in FIG.
Since the joint portion between the tank upper frame 1 and the corrugated heat radiator 2 does not form a smooth continuous surface, large flow separation areas 4 occur at the interrupted portions of the natural convection of the insulating oil.
Therefore, there is a drawback that the flow efficiency of the insulating oil is reduced and the heat dissipation effect is deteriorated. In view of these points, the present invention prevents local elongation and cracking of the base material near the rising corners of the corrugated rib peaks, and prevents natural convection of insulating oil.
An object of the present invention is to provide a tank for oil-filled electrical equipment equipped with a corrugated radiator that reduces flow separation areas.

An embodiment of the present invention will be described below with reference to FIGS. 7 to 10.

Note that the same parts as in FIGS. 1 to 6 are designated by the same reference numerals, and the explanation thereof will be omitted. FIG. 7 is a front view showing a part of the corrugated radiator 2 according to the present invention, in which the oil pipe 2c portion shows a cross-sectional shape, and FIG. 8 is a partial side view of the corrugated radiator 2 shown in FIG. FIG. 9 is a partial perspective view of the corrugated heat sink 2. As shown in FIG.

As shown in FIGS. 7 to 9, the vicinity of the pressing portion of both ends 2b of the corrugated rib crest 2a consists of a close contact portion 211, an inclined oilway portion 2m1, a parallel oilway portion 2n, and a close contact portion 2
1(7) The length in the z-axis direction is L. Wave-shaped rib mountain 2a
As described above, a thin steel plate is sequentially bent into a wave shape, and its upper and lower ends 2b are pressed by drawing and sealed by welding so as to form a circulation path for insulating oil.

Here, in the pressing portion of both ends 2b of the rib mount, the close contact portion 21<7)L dimension is small near the bottom surface of the rib mount, x
In the height direction of the rib ridge 2a in the axial direction, the L dimension is formed so as to increase continuously up to a certain value as the distance from the bottom surface increases. In other words, when viewed from the 2m slope of the oilway, as you get closer to the bottom of the rib mountain, both ends 2 of the rib mountain
It is formed close to the welded part b. However, to explain the formability of the wave-shaped rib peaks 2a formed as described above, plate-shaped metal materials such as steel plates are generally made into products by being subjected to various deformations such as bending, stretching, and drawing due to their plastic workability. In the processing method generally called drawing, as the drawing process progresses, material is drawn from the surrounding area to form the part to be drawn, but when drawing the center part of a material that is too large, the part to be drawn is , the material tries to be pulled in from its surroundings, but the resistance force of the material itself to maintain its shape becomes stronger, and if this resistance force becomes greater than the tensile strength of the material itself, it becomes so-called overhang processing. The material will be stretched and eventually break.

In other words, this is the reason why there is a numerical value called the drawing ratio or drawing rate, and the closer the free end of the material is to the part to be processed, the easier it is for the material to be drawn into the part to be processed, and the change in material thickness will be smaller and smoother. It will be processed. Therefore, in the pressing process of both ends 2b of the rib crest as in the present embodiment, the close contact portion 21 of both ends 2b of the rib crest is small near the bottom surface of the rib crest, and increases to a certain value as the distance from the bottom surface of the rib mount increases. In other words, by continuously increasing the degree of machining to By drawing the material from the free end of the material, creating a so-called sink in the material, the elongation of the material caused by pressing can be largely suppressed.

In this way, by improving the flowability of the material in the pressing process of both ends 2b of the rib mount and reducing the so-called overhang processability, it is possible to prevent a decrease in the thickness of the material due to local elongation of the material, and Of course, cracks 2g of the material caused by local elongation can also be prevented, and stable pressing becomes possible. By the way, FIG. 10 is a partial sectional view of the oil-filled electrical equipment tank of this embodiment, showing the flow of insulating oil.

As shown in the figure, as the sloped oilway portion 2m approaches the tank upper frame 1, the welded portion of both ends 2b of the rib mount approaches, that is, the joining line between the close contact portion 21 and the sloped oilway portion 2m approaches the tank upper frame. An inclination angle of θ is formed near 1, and this part becomes a guide part for the flow of insulating oil to the oil pipe 2c of the corrugated radiator, and does not interfere with the natural convection of the insulating oil, and also allows separation away from natural convection. The area becomes smaller and the flow efficiency of the insulating oil also improves. In the above embodiment, both ends 2 of the rib mountain
The joining line formed between the close contact part 21 near the pressing part b and the inclined oilway part 2m was composed of two straight lines, but in another embodiment of the present invention shown in FIG. , shows the case where the above-mentioned joining line near the tank upper frame 1 consists of a curved line with a constant curvature, and in this case, the joining line has a circular shape,
Various shapes such as an ellipse are possible, but as shown in Fig. 11, if the central part of the oil pipe 2c is set on the z-x plane, the X-axis and the z-axis are set, and the joining line is expressed in coordinates. ,z
−Fn(x).

Here, z is expressed by a function Fn with X as a variable. This function can take any desired relationship, such as z=F1(x) in the range of X<X1 and z-F2(x) in the range of x>X1. As mentioned above, regarding this joining line, the possibility of differentiation on the line, presence or absence of inflection points or their number, and the form and number of the function Fn can be freely chosen. As explained above, according to the tank for oil-filled electrical equipment according to the present invention, the width of the pressed contact portion from the edge of both ends of the corrugated rib crests is set such that the width of the pressed contact portion from the edge of both ends of the wavy rib ridges is set as By forming the corrugated radiator so that it continuously decreases from a certain width, it is possible to prevent local elongation and cracking of the base material near the rising corners of the rib peaks, which in turn improves the productivity of the corrugated heat sink. Furthermore, it is possible to reduce the separation area of the flow of insulating oil, contributing to improvement of heat dissipation characteristics.

[Brief explanation of drawings]

Figure 1 is a perspective view of a tank for oil-filled electrical equipment using a corrugated radiator, Figure 2 is a perspective view of the corrugated radiator, and Figure 3 is a perspective view of a tank for oil-filled electrical equipment that uses a corrugated radiator.
FIG. 4 is a partial perspective view of the corrugated radiator including a partial cross section of the corrugated rib crest, FIG. 5 is a partial perspective view of the corrugated radiator, and FIG. 6 is a partial perspective view of the corrugated radiator. Partial cross-sectional view of the tank for oil-filled electrical equipment in the x-z plane in Figure 1, No. 7
FIG. 8 is a partial front view of a corrugated heat sink including a partial cross section of the corrugated rib crest according to the present invention, FIG. 8 is a partial side view of the corrugated heat sink according to the present invention, and FIG. 9 is a partial perspective view of the corrugated heat sink according to the present invention. 10 is a partial side sectional view of a tank for oil-filled electrical equipment according to the present invention, and FIG. 11 is a partial perspective view of a corrugated radiator according to another embodiment of the present invention. 1...Top frame, 2...Corrugated heat sink, 2a
...Rib mountain, 2b...Both ends of the rib mountain, 2c...Oil pipe, 2d...Both ends of the bottom of the rib mountain, 2g... ...Crack, 21...Tight part, 2m...Gradient oilway part, 2n...
・・Parallel oil pipe part, 3・・・・Lower frame, 4・・・・
- Peeling area.

Claims (1)

[Claims] 1. In a tank for oil-filled electrical equipment using a corrugated radiator formed by continuously forming a thin steel plate into a corrugated shape, the width of the press-fitting portion from the edge of both ends of the corrugated rib crest of the corrugated radiator is measured. A tank for oil-filled electrical equipment, characterized in that the tank is formed near the bottom surface of the rib ridge so that the width becomes smaller continuously from a constant width as one approaches the bottom surface of the rib ridge.