JP2000311803A - Shield - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a shield having enhanced rigidity and improved vibration resistance, without increasing the sheet thickness. SOLUTION: A downwardly extending cylindrical bend 12 is provided between a disk 7a and a circular cylinder 7b of a shield 7, and the bend 12 is disposed at a position satisfying 0.3<(c-b)/(a-b)<0.5, where the outer diameter of the shield 7 is (a), the radius of pitch circle of a bolt 8 is b, and the radius of the bend 12 is c.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shield used for substation equipment such as a tank type lightning arrester, and more particularly to a shield having an increased rigidity and improved seismic performance.

[0002]

2. Description of the Related Art Generally, a shield is installed in a tank type lightning arrester to reduce the electric field intensity. here,
A conventional example of a tank type lightning arrester provided with a shield will be specifically described with reference to FIG. As shown in the figure,
The tank-type lightning arrester 1 is provided with a tank 2, a tank lid 3, and a support leg 4, and an insulating cylinder 5 containing a lightning arrester element is provided in the tank 2. A fixing bracket 6 is attached to an upper portion of the insulating tube 5, and a shield 7 is provided on an upper surface thereof.
Is provided. The shield 7 has a disk portion 7 a formed on the inner peripheral side and a cylindrical portion 7 b formed on the outer peripheral side. The disk portion 7 a is fixed to the fixing bracket 6 by a plurality of bolts 8. This shield 7 is for reducing the electric field strength at the end of the insulating cylinder 5 and is usually made of a thin A1 material or SUS.
It is manufactured by drawing materials. A spacer 11 is attached to a side surface of the tank 2, and the connection fitting 10 is supported by the spacer 11. Reference numeral 9 indicates a terminal.

[0003]

The shield 7
In addition to the electric force acting on the
In response to the vibration of the insulating cylinder 5, a bending moment for deforming the shield 7 acts. In order to resist this, the shield 7 needs to have such rigidity that it does not significantly deform. However, in the case of manufacturing a large-sized shield 7, if the diameter and the height are increased with a constant thickness of a thin-walled material in consideration of the manufacturing cost and drawing workability, the rigidity is easily reduced and the seismic performance is reduced. There was a problem.

The present invention has been proposed in consideration of the above points, and an object of the present invention is to provide a shield which increases rigidity without increasing the thickness of a plate and improves seismic performance. .

[0005]

In order to achieve the above-mentioned object, the present invention provides a disk drive having a disk portion formed on an inner peripheral side and a cylindrical portion formed on an outer peripheral side, wherein the disk portion is fixed by bolts. The shield fixed to has the following features.

According to the first aspect of the present invention, a bent portion is provided between the disk portion and the cylindrical portion, and the outer radius of the shield is a,
Assuming that the radius of the pitch circle due to the bolt is b and the radius of the bent portion is c, the bent portion is 0.3 <(c−b) /
(Ab) It is characterized by being disposed at a position satisfying <0.5. According to the first aspect of the present invention, by providing a bent portion at a position where the value of (c−b) / (ab) is 0.3 to 0.5, the rigidity of the shield can be greatly increased. The seismic performance can be improved without increasing the thickness of the shield.

The invention according to claim 2 is characterized in that a plurality of bent portions are provided between the disk portion and the cylindrical portion. According to the second aspect of the present invention, the disk portion is divided into a plurality of parts by the plurality of bent portions, and the ratio of the radius of the circular portion to b /
Since a approaches 1, the rigidity of the shield can be increased.

According to a third aspect of the present invention, a conical portion is provided between the disk portion and the cylindrical portion. According to the third aspect of the present invention, by providing the shield with the conical portion, the apparent outer diameter of the disk portion is reduced, so that the ratio b / a of the radius of the disk approaches 1, and the shield is removed. Can be increased in rigidity.

The invention according to claim 4 is the invention according to claim 1, 2 or 3.
In the above-described shield, the tubular portion is disposed inside a pitch circle formed by bolts. According to the fourth aspect of the present invention, since the cylindrical portion restrains the axial displacement of the shield on the inner peripheral side of the shield fixed to the bolt, even if the number of bolts is small, a reduction in rigidity due to this is prevented. And the shield can maintain excellent rigidity.

According to a fifth aspect of the present invention, in the shield according to the fourth aspect, the tubular portion is fitted to a fixing fitting. According to the fifth aspect of the present invention, it is possible to prevent the rigidity of the shield from being reduced due to the small number of bolts in the cylindrical portion, and at the same time, to reduce the electric field since the distal end portion of the cylindrical portion enters the fixture. There is a working effect.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be specifically described below with reference to the drawings. The embodiments described below are all shields used for a tank type lightning arrester, and the same members as those in the conventional example of FIG.

(1) First Embodiment (corresponding to claim 1) As shown in FIG. 1, a disk portion 7a and a cylindrical portion 7 of a shield 7 are provided.
b, a cylindrical bent portion 12 bent downward.
Is provided. When the radius of the outer periphery of the shield 7 is a, the radius of the pitch circle formed by the bolt 8 is b, and the radius of the bent portion 12 is c, the bent portion 12

It is arranged at a position that satisfies 0.3 <(c−b) / (ab) <0.5.

For example, if the radius a of the outer circumference of the shield 7 is 30
cm, when the radius b of the pitch circle by the bolt 8 is 10 cm,

## EQU00002 ## By rewriting as 0.3 (ab) + b <c <0.5 (ab) + b, the radius c of the bent portion 12 becomes

## EQU3 ## 0.3 × 20 cm + 10 cm <c <0.5 × 2
0 cm + 10 cm, and the bent portion 12 has a radius c of 16 cm to 20 cm.
cm. In FIG. 1, the outer diameter of the shield 7 is shown as 2a, the diameter of the pitch circle formed by the bolts 8 is shown as 2b, and the diameter of the bent portion 12 is shown as 2c.

Next, the rigidity of the shield 7 configured as described above will be described with reference to the characteristic diagrams of FIGS. The disk portion 7 a on the inner peripheral side of the shield 7 is rigidly fixed by a plurality of bolts 8. The outer peripheral side of the shield 7 connected to the cylindrical portion 7b is also substantially rigidly fixed because the axial displacement of the disk portion 7a is restricted. Further, since the axial displacement is also restrained at the bent portion 12, it is almost rigidly fixed.

The ratio between the bending moment M acting on the shield 7 in such a fixed state and the deflection angle θ is k (= M
/ Theta) and then, the flexural rigidity D of the plate ^{(= Eh 3/12 (1} -ν
² ); The value k / D, which is made dimensionless by E Young's modulus, h plate thickness, and ν Poisson's ratio, is referred to as the rigidity of the shield 7. At this time, b / a (the ratio of the outer radius of the shield 7 to the radius of the bolt pitch circle) at which the rigidity of the shield 7 becomes maximum, and c / a
The relationship between a (the ratio of the outer radius of the shield 7 to the radius of the bent portion 12) is as shown in the graph of FIG.

FIG. 3 shows the relationship between the maximum rigidity k / D and b / a when the bent portion 12 is provided, and the relationship between k0 / D and b / a when the bent portion 12 is not provided. As shown in the graph. Furthermore, the rate of increase in the rigidity of the shield 7 (k
The relationship between / D) / (k0 / D) and (c−b) / (ab) is as shown in the graph of FIG.

That is, in the first embodiment, as shown in FIG. 4, the bent portion 12 is arranged at a position where the value of (c−b) / (ab) is 0.3 to 0.5. With this arrangement, the rigidity of the shield 7 can be increased two to three times. Therefore, the rigidity can be increased without increasing the thickness of the shield 7, and the seismic performance is improved.

(2) Second Embodiment: Corresponding to Claims 1 and 4 In the second embodiment, in addition to the configuration of the first embodiment, as shown in FIG. The present invention is characterized in that a cylindrical portion 13 rising upward is disposed inside the pitch circle.

Assuming that the number of bolts 8 fixing the disk portion 7a of the shield 7 is N, the number N of bolts and the
As shown in the graph of FIG. 6, the relationship between the rigidity and the rigidity significantly decreases when the number N of bolts is small. In the graph of FIG. 6, the rigidity of the shield 7 is made dimensionless by the value when N = ∞. Therefore, the axial displacement of the shield can be restrained by providing the cylindrical portion 13 also on the inner peripheral side of the shield 7 fixed by the bolt 8.

According to such a second embodiment,
The bent portion 12 is provided at a position where the value of (c−b) / (ab) is 0.3 to 0.5, and the cylindrical shield 13 is provided inside the bolt pitch circle. Thus, even when the number N of bolts is small, the rigidity of the shield 7 does not decrease, and excellent seismic performance can be maintained.

(3) Third Embodiment: Corresponding to Claims 1 and 5 A third embodiment is a further improved version of the second embodiment. As shown in FIG. The inside of the pitch circle 8 is provided with a cylindrical portion 14 bent downward, which is fitted to the fixing bracket 6.

According to the third embodiment, similarly to the second embodiment, in addition to preventing the rigidity of the shield 7 from being reduced by the action of the cylindrical portion 14, the cylindrical portion 1
Since the fitting 4 is fitted to the fixture 6, the tip of the tubular portion 14 enters the fixture 6 and the electric field can be reduced, thereby improving the electrical characteristics.

(4) Fourth Embodiment Corresponding to Claim 2 In the fourth embodiment, as shown in FIG. 8, three cylindrical members are provided between a disk portion 7a and a cylindrical portion 7b. A feature of the configuration is that a bent portion 15 is provided.

In such a fourth embodiment,
By providing the plurality of bent portions 15, the ratio b / a of the radius of each of the divided disk portions approaches one. Therefore, the rigidity in the case where the bent portion 15 is provided increases as shown in the graph of FIG. 3, and the rigidity of the entire shield 7 increases.

(5) Fifth Embodiment Corresponding to Claim 3 A feature of the fifth embodiment is that, as shown in FIG. 9, a conical portion 7c is provided between a disk portion 7a and a cylindrical portion 7b. It has been provided.

In the fifth embodiment having the above configuration, the apparent outer diameter of the disk portion 7a is reduced by providing the shield 7 with the conical portion 7c. As a result, the ratio b / a of the radius of the disk portion 7a approaches 1, and the rigidity of the shield 7 increases as in the fourth embodiment.

(6) Other Embodiments The present invention is not limited to the above embodiments, and the shape and the number of each member can be appropriately changed. May be tapered.

[0028]

As described above, according to the shield of the present invention, by providing one or a plurality of bent portions in the disk portion on the inner peripheral side of the shield, the rigidity can be increased without increasing the plate thickness. It is possible to improve the seismic performance.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a first embodiment of the present invention.

FIG. 2 is a graph showing characteristics of the shield according to the first embodiment.

FIG. 3 is a graph showing characteristics of the shield according to the first embodiment.

FIG. 4 is a graph showing characteristics of the shield according to the first embodiment.

FIG. 5 is a configuration diagram of a second embodiment of the present invention.

FIG. 6 is a graph showing characteristics of the shield according to the second embodiment.

FIG. 7 is a configuration diagram of a third embodiment of the present invention.

FIG. 8 is a configuration diagram of a fourth embodiment of the present invention.

FIG. 9 is a configuration diagram of a fifth embodiment of the present invention.

FIG. 10 is a configuration diagram of a conventional tank-type lightning arrester provided with a shield.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Tank type lightning arrester 2 ... Tank 3 ... Tank lid 4 ... Leg 5 ... Insulating cylinder which accommodates lightning arrester element 6 ... Fixing metal 7 ... Shield 7a ... Disc part 7b ... Cylinder part 7c ... Conical part 8 ... Bolt 9 ... Terminal 10 ... Connection fittings 11... Spacers 12 and 15. Bent parts 13 and 14... Cylindrical part a...

Claims (5)

[Claims] 1. A shield in which a disk portion is formed on an inner peripheral side and a cylindrical portion is formed on an outer peripheral side, and wherein the disk portion is fixed to a fixing bracket with bolts, wherein the disk portion and the cylindrical portion are When the radius of the outer circumference of the shield is a, the radius of the pitch circle formed by the bolt is b, and the radius of the bent portion is c, the bent portion is 0.3 < (C−b) / (ab) <
A shield which is arranged at a position satisfying 0.5. 2. A shield in which a disk portion is formed on an inner peripheral side and a cylindrical portion is formed on an outer peripheral side, and wherein the disk portion is fixed to a fixing bracket with bolts, wherein the disk portion and the cylindrical portion are A shield, wherein a plurality of bent portions are provided between the shields. 3. A shield in which a disk portion is formed on an inner peripheral side and a cylindrical portion is formed on an outer peripheral side, and wherein the disk portion is fixed to a fixing bracket by bolts, wherein the disk portion and the cylindrical portion are A shield characterized by having a conical portion between them. 4. A cylindrical portion is provided inside a pitch circle formed by said bolts.
The shield described. 5. The shield according to claim 4, wherein the tubular portion is fitted to the fixing bracket.