JPH0963377A - Suspended insulator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a highly reliable suspended insulator having a shock absorbing member which can reliably prevent mechanical damage of porcelain and reduction in electric strength over a long period of time regardless of an assembling condition. SOLUTION: A suspended insulator is provided with a porcelain-made insulator 3 where ceramic quality sand 4 is adhered to an inside surface and an outside surface of a peripheral wall 3a in a hollow cylindrical head part 3, a cap metal fitting 5 and a pin metal fitting 6 joined to an insulator head part 3 by cement 7. The pin metal fitting 6 is positioned in the insulator head part 3, and contains a large diameter end part having a taper surface. A disk-shaped shock absorbing member 8 is arranged between an end surface of the large diameter end part in the pin metal fitting 6 and an inside surface of a head part top wall 3b opposed to this. An outside diameter (d) of the shock absorbing member 8 is set so as to satisfy (d/D=0.92 to 1.0) when an outside diameter of the large diameter end part in the pin metal fitting 6 is denoted by D, and mechanical damage of porcelain and reduction in electric strength of the insulator are prevented over a long period of time regardless of an assembling condition.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a porcelain insulator including a hollow cylindrical head having a top wall and a peripheral wall, and ceramic sand bonded to the inner and outer surfaces of the peripheral wall, and the insulator. A cap fitting and a pin fitting joined to the head of the body by cement, the pin fitting including a large-diameter end portion having a tapered surface and located inside the head of the insulator, and further comprising: The present invention relates to a suspension insulator in which a disk-shaped cushioning member is arranged between an end surface of a large-diameter end portion and an inner surface of a head top wall facing the end surface.

[0002]

2. Description of the Related Art A suspension insulator having the above-mentioned structure is disclosed in, for example, Japanese Patent Laid-Open No. 63-193414 and is conventionally known. In such a suspension insulator, a disk-shaped cushioning member made of an elastic material such as cork is arranged between the end surface of the large-diameter end of the pin fitting and the inner surface of the top wall of the insulator head facing the end fitting. Is intended to prevent direct contact between the pin fitting and the inner surface of the head. That is, since the porcelain of the insulator and the metal material of the pin fitting have different coefficients of thermal expansion, the porcelain may be cracked during long-term use of the suspension insulator under conditions of direct contact between the two. This is because it is necessary to reliably prevent mechanical damage of the.

By the way, in assembling a suspension insulator, after filling cement into the inner space of the insulator head, that is, a so-called pinhole, the pin fitting is inserted into the pinhole together with the buffer member. In this case, since the cement filled in the pinhole has low viscosity, the pin fitting is inserted into the pinhole until the cushioning member reaches the inner surface of the top wall of the head. Since the bottom surface of the pinhole (the inner surface of the top wall) is a curved surface for reasons of porcelain molding technology, if the diameter of the cushioning member is insufficient with respect to the diameter of the large diameter end of the pin fitting,
The essential function of the cushioning member that prevents direct contact between the pin fitting and the inner surface of the head (see FIG. 8) is not fully exerted. In addition, when inserting the pin fitting and the cushioning member into the pin hole, it is inevitable that the pin fitting and / or the cushioning member is eccentric with respect to the center axis of the pin hole depending on the dimensional tolerance or the roundness. It is said that it is desirable to set the diameter of the cushioning member to a large value when the assembling conditions are assumed.

On the other hand, it has been pointed out that if the diameter of the buffer member is excessively large, the electrical strength of the insulator may be significantly reduced. This is because the rounded portion with a relatively small radius of curvature, which continuously connects the cylindrical inner surface of the peripheral wall of the insulator head and the curved surface of the top wall, exhibits the highest potential gradient. This is because the outer peripheral parts of the members come into contact with each other.

Therefore, there is a demand for a suspension insulator having a cushioning member capable of reliably preventing mechanical damage to the porcelain and reduction in electrical strength thereof for a long period of time regardless of the assembly conditions.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to propose a highly reliable suspension insulator having a cushioning member which can sufficiently satisfy the above-mentioned requirements.

[0007]

In order to solve this problem, the present invention includes a hollow cylindrical head having a top wall and a peripheral wall, and ceramic sand is adhered to the inner surface and the outer surface of the peripheral wall. A porcelain insulator, and a cap fitting and a pin fitting joined to the head of the insulator by cement. The pin fitting is located inside the head of the insulator and has a large diameter. In a suspension insulator including a disk-shaped cushioning member including an end portion and further disposed between the end surface of the large-diameter end portion of the pin fitting and the inner surface of the head top wall facing the end surface, It is characterized in that the following relational expression: d / D = 0.92 to 1.0 is satisfied between the outer diameter D of the large diameter end and the outer diameter d of the cushioning member.

According to the present invention, the appropriate range of the outer diameter of the cushioning member with respect to the outer diameter of the large-diameter end portion of the pin fitting is determined, so that the pin fitting and the inner surface of the head are not affected by the assembly condition. The original function of the cushioning member that prevents direct contact is fully exerted, and the contact between the rounded portion on the inner surface of the insulator head and the outer periphery of the cushioning member can be prevented, so that the decrease in electrical strength is accurately avoided. It is also possible to do.

In a preferred embodiment of the present invention, the inner surface of the peripheral wall of the insulator head is a cylindrical surface, and the inner surface of the top wall is a curved surface, and the inner surfaces of the peripheral wall and the top wall are substantially quartered arc-shaped rounded surfaces. And the radiused surface has a smaller radius of curvature than the curved surface of the inner surface of the top wall. In this case, the radius of curvature of the rounded surface can be set to 8 to 10 mm, for example. In addition, the thickness of the cushioning member can be 2 to 3 mm.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below in detail with reference to the preferred embodiments shown in the accompanying drawings. The suspension insulator shown in FIG. 1 comprises an insulator 1 made of porcelain, and the surface of the base body of this insulator 1 is coated with glaze in a known manner. The insulator 1 is composed of a flange-shaped cap portion 2 extending outward in the radial direction, and a substantially cylindrical head portion 3 arranged in the center of the cap portion 2 and protruding upward. The head 3 has a cap 2 at the lower end.
And a top wall 3b continuous with the upper end of the peripheral wall 3a. As shown in FIG.
The inner surface of the peripheral wall 3a in the head portion 3 is a cylindrical surface, the inner surface of the top wall 3b is a curved surface, and the inner surfaces of the peripheral wall 3a and the top wall 3b are continuously connected by the rounded surface 3c, and the radius of curvature Rc of the rounded surface 3c is It is smaller than the radius of curvature Rb of the inner surface of the top wall 3b and is, for example, 8 to 10 mm. Ceramic sand 4 is adhered to the inner and outer surfaces of the peripheral wall 3a. In this case, the upper end of the adhesion region of the sand 4 on the inner surface of the peripheral wall 3a is within the region ΔT below the position 3 mm above the connection position T between the cylindrical inner surface of the peripheral wall 3a and the rounded surface 3c. It is preferable to arrange them.

To the head 3, the cap fitting 5 is joined on the outer surface side, and the pin fitting 6 is joined on the inner surface side by cement 7. The pin fitting 6 is the head 3 of the insulator 1.
It has a large-diameter upper end located inside and has a tapered surface, and a metal plating layer formed by hot dip galvanizing or the like is formed on the surface, and a bituminous paint as an alkali resistant insulating film is formed on this metal plating layer. Has been applied. Further, a buffer member 8 having a thickness of 2 to 3 mm is inserted between the upper end surface of the pin fitting 6 and the inner surface of the top wall 3b of the head 3.

The basic structure itself of the above-mentioned suspension insulator is disclosed in, for example, the above-mentioned Japanese Patent Laid-Open No. 63-193414 and is conventionally known. The sand 4 adhered to the inner surface and the outer surface of the head peripheral wall 3a of the insulator 1 is
It is suitable to manufacture by the following method. That is, first, a sand substrate is prepared in the same manner as in the conventional case, and dehydrated by a filter press to obtain a cake containing an appropriate amount of water. This cake is put into a clay kneader and kneaded, and the pore size is 1.8 to
A noodle-shaped molded body is obtained by extruding from a perforated plate having a large number of through holes of about 2.0 mm. The diameter of this compact is the same as or slightly larger than the maximum grain size of the intended sand. Next, the noodle-shaped molded body is dried,
A coarse crusher and a de-sinter sizing machine are crushed and sized to form a granule having a diameter substantially the same as the diameter of the compact. The de-sinter sizing machine is a device for crushing and sizing while rotating a drum provided with a large number of through holes. It is preferable that the diameter of the through holes in the drum is about 1.6 to 1.8 mm, and the rotation speed of the drum is about 200 rpm, which is much lower than in the usual case. The granules thus obtained are
It is a granular material with few sharp edges, and the upper net is 1.68.
mm, the lower net is 0.84 to 1.0 mm, and the powder is screened and sieved after sieving. After that, the fired product is disentangled through a disintegrating sieve and finished as an insulator sand with few sharp edges. The method for crushing the sand for insulators is described in detail in, for example, Japanese Patent Publication No. 6-53601, so refer to the description in that publication as well.

In the present invention, direct contact between the pin fitting 6 and the inner surface of the top wall 3b of the insulator head 3 is prevented, and contact between the rounded portion 3c on the inner surface of the head and the outer peripheral portion of the buffer member 8 is also prevented. Therefore, the ratio of the outer diameter d of the buffer member 8 to the outer diameter D of the large-diameter end of the pin fitting 6 (outer diameter ratio d
/ D) to determine an appropriate range. That is, when assembling the suspension insulator, the cement 7 is attached to the insulator head 3
After filling the inside of the pinhole of the
While being inserted into the pinhole together, the pin metal fitting 6 may be eccentric to the central axis of the insulator head 3 as shown in FIG. 3 or the cushioning member 8 may be eccentric as shown in FIG. Is inevitable. Even in such a case, it is necessary to ensure that the cushioning member 8 can surely exert its original function of preventing direct contact between the inner surface of the insulator head 3 and the pin fitting 6. Incidentally, the maximum amount of eccentricity of the pin fitting 6 with respect to the central axis of the insulator head 3 is 2.5 mm in a normal suspension insulator.

FIG. 5 is a graph showing the outer diameter ratio d / D with respect to the amount of eccentricity of the pin fitting in relation to the presence or absence of eccentricity of the buffer member 8. This graph is based on IEC standard No. 30
No. 5 U120BS compliant suspension insulator, which is required to prevent direct contact between the inner surface of the insulator head 3 and the pin fitting 6 when the thickness t of the cushion member 8 made of cork is 2 mm. The outer diameter ratio d / D is shown, and the area where direct contact between the inner surface of the insulator head 3 and the pin fitting 6 can be prevented is the right area of each straight line.

FIG. 6 is a graph showing the outer diameter ratio d / D with respect to the eccentricity of the pin fitting in relation to the wall thickness t of the buffer member 8. This graph shows that IEC standard No.
In the suspension insulator conforming to U120BS of 305,
An outer diameter ratio d / D required to prevent direct contact between the inner surface of the insulator head 3 and the pin fitting 6 when the thickness t of the cork cushioning member 8 is changed. The region where direct contact between the inner surface of the insulator head 3 and the pin fitting 6 can be prevented is the right side region of each straight line.

FIG. 7 is a graph showing the outer diameter ratio d / D with respect to the amount of eccentricity of the pin fitting in relation to various suspension insulators having different guaranteed strengths. This graph is for preventing direct contact between the inner surface of the insulator head 3 and the pin fitting 6 when the wall thickness t of the cushioning member 8 is set to 2 mm and each dimension of the suspension insulator is changed according to the guaranteed strength. The outer diameter ratio d / D required for the above is shown, and the area where direct contact between the inner surface of the insulator head 3 and the pin fitting 6 can be prevented is the right side area of each straight line. And it is generally used IEC standard N
Considering that the suspension is less than U300B grade of o.305, and that the maximum eccentricity of the pin fitting 6 is 2.5 mm in a normal suspension insulator, the inner surface of the insulator head 3 and the pin fitting 6 are considered. It is necessary to set the outer diameter ratio d / D to 92% or more in order to prevent direct contact with the porcelain and reliably prevent mechanical damage to the porcelain over a long period of time regardless of the assembly conditions. it is obvious.

On the other hand, when the diameter of the buffer member 8 is excessively large, the outer peripheral portion of the buffer member comes into contact with the rounded portion 3c having the highest potential gradient on the inner surface of the insulator head 3, resulting in the insulator. The electrical strength may decrease. In order to reliably prevent such a decrease in electrical strength, the outer diameter ratio d / D of the cushioning member 8 is set to 100 as shown in Table 1 below.
It must be less than or equal to%.

[0018]

[Table 1]

Table 1 shows the IEC standard No. 305 U12
In the suspension insulator conforming to 0BS, the steep wave strength of the suspension insulator when the outer diameter ratio d / D of the cork cushioning member 8 is changed is shown. When the outer diameter ratio d / D is 110%, Destruction was observed in 3 out of 10 samples, whereas no fracture was observed in any of 10 samples when the outer diameter ratio d / D was 100% and 90%. Is shown.

For this reason, in the present invention, the appropriate range of the ratio (outer diameter ratio d / D) of the outer diameter d of the buffer member 8 to the outer diameter D of the large diameter end of the pin fitting 6 is set to
It is defined as 0.92 to 1.0.

As is apparent from the above description, according to the present invention, the proper range of the outer diameter d of the buffer member 8 with respect to the outer diameter D of the large-diameter end portion of the pin fitting 6 is determined.
Regardless of the assembling conditions, the cushioning member 8 that sufficiently prevents the direct contact between the pin fitting 6 and the inner surface of the insulator head 3 is sufficiently exerted, and the rounded portion 3c on the inner surface of the insulator head 3 is sufficiently exerted. Since it is also possible to prevent contact between the outer peripheral portion of the cushioning member 8 and the outer peripheral portion of the cushioning member 8, it is possible to accurately avoid a decrease in electrical strength.

It should be noted that the above-described embodiments are merely examples and do not limit the present invention. Needless to say, the present invention can be implemented in various modifications within the scope.

[Brief description of drawings]

FIG. 1 is a front view of a suspension insulator to which the present invention can be suitably applied, showing a half portion thereof in cross section.

FIG. 2 is a schematic diagram for explaining the shape of the inner surface of the head of the insulator.

FIG. 3 is a schematic diagram for explaining an eccentric state of the pin fitting and the cushioning member with respect to the central axis of the insulator.

FIG. 4 is a schematic diagram for explaining an eccentric state of a pin fitting and a cushioning member with respect to a central axis of an insulator.

FIG. 5 is a graph showing the outer diameter ratio d / D with respect to the eccentricity of the pin fitting in relation to the eccentricity of the cushioning member.

FIG. 6 is a graph showing the outer diameter ratio d / D with respect to the eccentricity of the pin fitting in relation to the wall thickness of the cushioning member.

FIG. 7 is a graph showing an outer diameter ratio d / D with respect to an eccentric amount of a pin fitting in relation to various suspension insulators having different guaranteed strengths.

FIG. 8 is an explanatory diagram showing a direct contact state between the pin fitting and the inner surface of the head, which occurs when the diameter of the cushioning member is inappropriately set.

[Explanation of symbols]

3 heads, 3a peripheral wall, 3b peripheral wall, 4 sand, 5 cap metal fittings, 6 pin metal fittings, 7 cement, 8 cushioning members

Claims (6)

[Claims] 1. A porcelain insulator including a hollow cylindrical head having a top wall and a peripheral wall, and ceramic sand bonded to the inner and outer surfaces of the peripheral wall, and a cement for the head of the insulator. The cap metal fitting and the pin metal fitting joined by, the pin metal fitting is located in the head of the insulator and includes a large diameter end having a tapered surface, and further, the end surface of the large diameter end of the pin metal fitting. , A suspension insulator provided with a disk-shaped cushioning member arranged between it and the inner surface of the top wall of the head opposite to the outside diameter D of the large diameter end of the pin fitting and the outside diameter d of the cushioning member. The following relationship between: Suspension insulator characterized by satisfying d / D = 0.92-1.0. 2. The inner surface of the peripheral wall of the insulator head is a cylindrical surface, the inner surface of the top wall is a curved surface, and the inner surfaces of the peripheral wall and the top wall are continuously connected by a rounded surface having a substantially quarter arc shape. The suspension insulator according to claim 1, wherein the suspension has a smaller radius of curvature than the curved surface of the inner surface of the top wall. 3. The suspension insulator according to claim 2, wherein the radius of curvature of the rounded surface is 8 to 10 mm. 4. The suspension insulator according to claim 1, wherein the buffer member has a thickness of 2 mm or more. 5. The suspension insulator according to claim 1, wherein the buffer member has a thickness of 3 mm or less. 6. The buffer member has a thickness of 2 mm or more and 3 mm.
The suspension insulator according to any one of claims 1 to 3, characterized in that: