JPH0556091B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to an insulating spacer disposed between adjacent gas insulated equipment in a gas insulated switchgear.

(Prior Art) A gas insulated switchgear is constructed by connecting gas insulated devices such as circuit breakers and disconnectors. This type of gas insulated equipment consists of a conductor and opening/closing part housed in a metal container filled with insulating gas.
Insulating spacers are attached to connections between gas insulated devices to separate gases between the gas insulated devices and to support conductors and opening/closing parts.

Conventionally, as such an insulating spacer, there is one shown in FIG. 3, for example.

In FIG. 3, the insulating spacer 1 is the insulating part 1
A conductor support portion 1b is integrally cast in the center of the conductor support portion 1b. The conductor support portion 1b supports the conductors 5 of the gas insulated devices 3 and 4 on both sides via the contact portions 2. A flange portion 1c is formed around the insulating portion 1a, and metal cylindrical bushes 8 are integrally cast into this flange portion 1c in the number of bolts.
The flange portion 1c is sandwiched between the flange portions 6a and 7a of the metal containers 6 and 7, and is fixed by tightening studs 9 and nuts 10 from both sides of the flange portions 6a and 7a of the metal containers 6 and 7 at the bushing 8 portion. has been done.

Note that FIG. 4 is a developed view of a circumferential cross section of the section AA in FIG. 3.

The insides of the metal containers 6 and 7 on both sides are divided by an insulating spacer 1, and each is filled with an excellent insulating gas such as SF ₆ gas, but the pressure of the filled gas is different on both sides of the insulating spacer 1. In this case, the insulating spacer 1 must bear the differential pressure. When pressure is applied to the insulating spacer 1 from one side, its center deforms mainly in the axial direction of the conductor.
The flange portion 1c deforms in the radial direction. The load due to this radial displacement concentrates around the bush 8 and generates high stress, making it easy for breakage to occur from this area.

The reason why the load due to such radial displacement is concentrated around bush 8 is as shown in Fig. 3.
Of the flange surface 1d of the insulating spacer 1, only the portion remote from the bushing 8 shrinks in the thickness direction due to curing shrinkage during casting, resulting in so-called "sink marks" and the flange portions 6a, 7 of the metal containers 6, 7. This is because the tightening with 7a is not done evenly.

In addition, in the insulating spacer shown in Fig. 3, if the flatness of the flanges 6a, 7a of the metal containers 6, 7 is low, local bending will be applied to the bush 8 by tightening the flanges, There is also the problem that cracks are likely to occur and the flexibility for tightening the flange is low.

In response to this, attempts have been made to improve the flexibility of tightening the flange by avoiding load concentration on the bushing part. For example, as shown in Fig. 5, the thickness H of the flange part 1c is By reducing the axial dimension h of the bush 11, the bush 1
There is an insulating spacer 1 provided with hollow portions 12 at both ends thereof.

In the insulating spacer 1 shown in FIG. 5 having such a configuration, the bushing surface does not come into contact with the flange portions 6a, 7a of the metal containers 6, 7, and the flange surface 1d of the insulating spacer 1 is directly tightened. A perfect tightening is achieved.

Further, since the axial dimension h of the bush 11 is smaller than the thickness H of the flange portion 1c, flexibility with respect to tightening of the flange is improved. That is, there is generally a "play" between the female thread of the bush 11 and the male thread of the stud 9, and this play is magnified by (H/h) times on the flange surface.
Therefore, if the parallelism of the flanges of the metal container is low, or the parallelism between the bushes is low, it can be absorbed by the expanded "backlash", and the insulating spacer shown in Figure 4 can absorb it. In this way, the problem of cracking due to tightening alone does not occur.

Furthermore, since the axial dimension of the bush 11 is smaller than the thickness H of the flange portion 1, "sink" on the flange surface can be reduced, and the tightening pressure can be made uniform. “Sink” during curing and shrinkage is the fourth
As mentioned in connection with the figure, this occurs because the resin around the bushing is restrained from shrinking, and the resin at a distance from the bushing contracts. Therefore,
The smaller (h/H), the smaller the difference in the amount of shrinkage around the bush and the position away from the bush, and the flatness of the flange surface on the resin side increases accordingly.

However, while the insulating spacer shown in FIG. 5 has the above-mentioned advantages, it also has the disadvantage that when the stud 9 is tightened, stress is generated at the end point 11a of the bush 11 that causes peeling. Here, since the structure of the flange portion 1c shown in FIG. 5 is vertically symmetrical, the upper nut 10 will be explained below.
The mechanism of peel stress generation when tightening is explained.

That is, in the insulating spacer 1 of FIG.
When the upper nut 10 is tightened, the bush 11 is pulled upwardly through the stud 9. On the other hand, compressive force is applied downward to the flange surface 1d of the insulating spacer 1 due to contact with the flange portion 6a of the metal container 6. In this case, the force pulling the bush 11 upward and the force pushing the flange surface downward create a clockwise moment with respect to the bush end point 11a, which pulls the insulator around the end point 11a outward from the center of the stud 9. , thus creating a stress that causes the bush interface to peel off.

FIG. 6 shows the distribution of peeling stress along the interface, and as a result of analysis using the finite element method, it can be seen that strong peeling stress occurs at the end points, as shown by the broken line.

Therefore, if the adhesive force at the interface is weak, the bush interface may peel off due to tightening of the flange portion, and this may progress further, reducing the breaking strength of the insulating spacer.

In other words, in the insulating spacer of FIG. 5, the advantage of directly tightening the flange cannot be translated into an improvement in the strength of the spacer.

Furthermore, if the fracture strength of the flange part cannot be improved as described above, the tightening force of the bolt part cannot be increased, which increases the number of bolts and increases the time required to process bolt holes and tighten bolts, which reduces productivity. There are also problems with decline.

(Problems to be Solved by the Invention) As described above, in conventional insulating spacers, even if the technology enables uniform tightening and improves flexibility with respect to tightening, peeling stress is generated at the interface of the bushing. Therefore, a decrease in fracture strength cannot be avoided, and in connection with this, the number of bolts increases, resulting in a decrease in productivity.

The present invention was proposed to solve these problems, and its purpose is to improve the flexibility with respect to tightening and improve the breaking strength, thereby achieving high reliability. An object of the present invention is to provide an insulating spacer with excellent productivity.

[Structure of the Invention] (Means for Solving the Problems) The insulating spacer of the present invention has an axial dimension of the bushing that is shorter than the thickness of the flange portion of the insulating spacer, so that the flange surface of the metal container and both ends of the bushing are connected to each other. A hollow part is provided in between, and the outer diameter of the bush is increased from the axial end toward the center, so that the maximum outer diameter of the bush is larger than the inner diameter of the hollow part. There is. Generally, the shape of the bush is a spindle shape, which is formed by obliquely cutting off the corners of the axial end of a cylindrical shape.

(Function) In the present invention having the above configuration,
The flexibility against tightening can be improved, and since the bushing and the flange overlap inside and outside in the thickness direction of the flange, the tightening force of the flange acts as a compressive force on the bush interface. Therefore,
The bushing surface will not peel off, and the breaking strength of the flange portion can be improved.

In particular, by increasing the outer diameter of the bushing from the axial end toward the center,
Since the same effect as chamfering the corners of the axial end of the bushing can be obtained, no destructive force is applied from the corners of the bushing to the flange part.

(Example) Hereinafter, an example of the insulating spacer according to the present invention will be specifically described with reference to FIGS. 1 and 2. Note that since the basic structure is the same as that of the prior art shown in FIGS. 3 to 5, the same reference numerals are given and the explanation will be omitted. Moreover, FIG. 2 is an enlarged sectional view showing the bushing portion.

As shown in FIG. 2, in this embodiment, the flange portion 21c of the insulating spacer 21 has a thickness H.
Metal cylindrical bushing 2 with smaller axial dimension
2 is integrally cast, and hollow portions 23 are provided at both ends of the bush 22, as in the conventional example shown in FIG.

However, in the insulating spacer 1 of FIG.
Whereas the inner diameter d ₂ of the hollow portion 12 was larger than the outer diameter d ₁ of the bush 11, in this embodiment, the central part of the bush 22 is expanded to increase its maximum outer diameter d _{1 .}
is larger than the inner diameter d ₀ of the hollow portion 23.

That is, in this embodiment, the shape of the bushing is a spindle shape obtained by obliquely cutting off the corner of the axial end of a cylindrical shape, and the outer diameter of the bushing 22 is from the axial end to the center. The area towards the front is enlarged. The outer diameter of the end of the bush 22 is approximately equal to the inner diameter d ₀ of the hollow part 23 , and as a result, the maximum outer diameter d ₁ of the bush 22 is smaller than the inner diameter d ₀ of the hollow part 23 . is also getting bigger. In the figure, 21a and 21b are an insulating part and a conductor support part of the insulating spacer 21, respectively, and 21d is a flange surface.

In this embodiment having such a configuration,
First, the dimension h of the bush 22 is determined by the flange portion 21c.
Since the thickness is smaller than the thickness of the flange portion 21, the bushing surface does not come into contact with the flange portions 6a, 7a of the metal containers 6, 7, as in the conventional example shown in FIG.
Since it is directly tightened, even tightening is performed and flexibility for tightening is improved.

In this embodiment, since the bush 22 and the flange portion 21c overlap in the tightening direction at the interface 22b of the bush 22 from the end point 22a to the maximum outer diameter portion, the tightening force of the flange portion 21c is directly compressed. The breaking strength of the flange portion 21 can be greatly improved compared to the conventional technology in which the tightening force acts as a peeling stress. In particular, in this embodiment, the bush 2
Since the corners of the axial ends of the bushings 22 are substantially chamfered, no destructive force is applied to the flange portions 21 from the corners of the bushings 22. Therefore, the breaking strength of the flange portion 21 can be further improved.

Furthermore, since the breaking strength of the flange portion 21 can be improved in this way, the tightening force of the bolt portion can be increased, which reduces the number of bolts and reduces the time required for machining bolt holes and tightening the bolts. You can improve your sexuality.

The results of analysis using the finite element method of the peeling stress during tightening along the bushing interface in this example are shown in the sixth section.
Shown in the figure as a solid line. In the same figure, it can be seen that the peeling stress in this example is a strong compressive stress, and there is no interfacial peeling due to tightening as in the conventional type.

In addition, in general, the bush 22 is made of a softer material than the stud, and furthermore, the axial dimension h of the bush 22 is smaller than the thickness H of the flange portion 21c. Considering the fact that the flexibility with respect to tightening can be improved as much as possible and the tightening pressure can be made uniform, it is preferable to design the axial dimension h of the bush 22 to be about 1.5 times the diameter dimension d ₀ of the stud 9.

[Effects of the Invention] As explained above, according to the present invention, a hollow portion is provided between the flange surface of the metal container and both ends of the bushing, and the outer diameter of the bushing is changed from the axial end to the center. By simply improving the structure by increasing the maximum outer diameter of the bushing to be larger than the inner diameter of the hollow parts at both ends of the bushing, uniform tightening is possible, and the bushing has high flexibility when tightening. Furthermore, since the tightening force is applied as a bush compression force, it is possible to provide an insulating spacer with improved breaking strength, high reliability, and excellent productivity.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing the installed state of an embodiment of the insulating spacer according to the present invention, FIG. 2 is an enlarged cross-sectional view showing the bushing part of the same embodiment, and FIG. 3 is a cross-sectional view showing the installed state of a conventional insulating spacer. 4 is a developed view of the circumferential cross section of section A-A in FIG. 3, FIG. 5 is an enlarged sectional view showing the improved conventional bushing part, and FIG. 2 is a graph comparing the distribution of normal stress generated on the interface along the interface between the conventional product and the embodiment of FIG. 1; 1, 21... Insulating spacer, 1a, 21a...
Insulating part, 1b, 21b...Conductor support part, 1c, 2
1c...Flange part, 1d, 21d...Flange surface, 2...Contact part, 3, 4...Gas insulated equipment, 5
...Conductor, 6,7...Metal container, 6a,7a...
Flange part, 8, 11, 22...button, 9...
...Stand, 10...Natsuto, 11a, 22a...
...Bushy end point, 12, 23...Empty part, 22b
...butsuyu interface.

Claims (1)

[Scope of Claims] 1. An insulating spacer that is tightened and fixed to a flange portion of a metal container via a metal cylindrical bushing integrally cast within the flange portion, wherein the axial dimension of the bushing is equal to the thickness of the flange portion of the spacer. The metal container is made shorter than the metal container, and a hollow part is provided between the flange surface of the metal container and both ends of the bushing.
An insulating spacer characterized in that the outer diameter of the bushing is increased from the axial end toward the center, and the maximum outer diameter of the bushing is larger than the inner diameter of the hollow portion. 2. The insulating spacer according to claim 1, wherein the bush has a spindle shape obtained by obliquely cutting off a corner of an axial end of a cylindrical shape.