JPH08316653A - Sealing structure for power apparatus - Google Patents

Abstract

PURPOSE: To provide a sealing structure for a power apparatus, which ensures stable sealing for a long term. CONSTITUTION: In a groove 3, which is formed on the sealing face 2 of a power apparatus 1 with a groove capacity V1 , a gasket 4 which has a larger capacity VG than the groove capacity V1 is inserted, and on the gasket surface protruded from the groove 3, a cover or flange 5 is pressed by spring force. Since sealing is not dependent on the rubber elasticity of the gasket, stable sealing effect is provided even at high and low temperatures.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sealing structure for a bushing or other electric power equipment.

[0002]

2. Description of the Related Art Electric power equipment is constantly charged and used, so that it is difficult to constantly maintain the sealed portion like ordinary equipment. For this reason, it is necessary to prevent airtight leaks and oil leaks for a long period of time without performing maintenance. Conventionally, a sealing structure as shown in FIGS. 3 to 5 has been adopted.

That is, in the conventional structure, as shown in FIGS. 3 and 4, a circumferential groove 11 is formed in a sealing surface 10 of a power device, a gasket 12 is inserted into the groove 11, and a lid or a flange is formed.
The structure is such that 13 is tightened with bolts 14 and the seal surface pressure is obtained by the repulsive force generated by the rubber elasticity of the gasket 12 itself. In this case, it was necessary to design with the following points in mind.

Excessive compression ratio (compression allowance /
(Crude thickness) gives severe creep, so gasket 12
Optimum by strictly controlling the thickness of the groove and the depth of the groove 11 during manufacturing
Keeps good compression ratio. Moreover, in order to ensure the accuracy of the compression ratio,
The lid or flange 13 and the sealing surface 10 are metal-touched
It is bolted to the state. Gasket volume V_GAnd groove
Volume V₁Is always the value considering the manufacturing tolerance of each dimension.
To V_G≤V ₁It is necessary to satisfy the relationship. this
Therefore, as shown in FIG. 5, the width dimension of the groove 11 is smaller than that of the gasket 12.
Allow sufficient margin for the width. In the air, in oil,
Depending on the usage conditions such as in gas, the type of gasket used
, Especially when heat resistance or cold resistance is required, use an expensive material.
Use a gasket. Gases that are especially difficult to replace
Ket 12 is supplemented with an adhesive to compensate for the decrease in rubber elasticity.
Use it as a supplement. However, such a conventional electric power machine
Many problems remain in the sealed structure of the vessel, including:
Was.

(A) The conventional structure seals by the rubber elasticity of the gasket itself. However, at a temperature lower than the glass transition point, the gasket hardens and loses rubber elasticity, and the volume shrinks due to heat shrinkage. Lost. In addition, the gasket deteriorates due to oxidation and the like to cause permanent distortion and loses the seal surface pressure even at a high temperature during operation, and at higher temperatures, the gasket softens and the seal surface pressure decreases. Then, once exposed to such a high temperature and then returned to normal temperature, the softened gasket remains deformed to the thickness of the depth dimension of the groove, and the rubber elasticity remains even though it remains.
The sealing performance is lost due to the heat shrinkage of the volume. For this reason,
Expensive gaskets such as those having a low glass transition point at low temperatures and those having good heat resistance at high temperatures must be used.

(B) Since the conventional structure seals with a small surface pressure due to the rubber elasticity of the gasket itself, a slight scratch or unevenness is not allowed on the surface of the groove, the lid, the flange or the like that comes into contact with the gasket. Therefore, for flat gaskets
A high finishing surface precision of 6S is required for 12S and O-rings. (c) Since the width of the groove has a large margin with respect to the width of the gasket, water or the like may enter the gap inside the groove to corrode the groove and reduce the sealing performance. Further, since there is a minute gap in the joint surface (metal touch surface) such as the flange, crevice corrosion occurs. Therefore, in order to prevent these, room temperature-curable silicone rubber is used to seal joints such as flanges and bolts and nuts where water may enter, and to prevent corrosion on the joint surface, special paint is applied. Must be applied. However, this is very time-consuming and its effect is limited by the properties of the gasket itself. (d) Ingress of moisture and gas is particularly harmful to electrical equipment, but in the conventional structure, the entire side surface of the gasket is exposed to moisture-containing atmosphere or gas inside the groove. It is easy to invade into the inside due to concentration diffusion, and oxidative deterioration easily occurs.

[0007]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned conventional problems and can secure a stable sealing property for a long period of time without using an expensive gasket. Does not require a high degree of surface finish accuracy, does not require coating of paint to prevent water from entering the joints such as flanges, and has little diffusion of water or gas into the gasket The purpose of this is to provide a sealed structure of.

[0008]

The sealing structure for electric power equipment of the present invention, which has been made to solve the above-mentioned problems, has a groove volume V ₁ formed in the sealing surface of the electric power equipment. It is characterized in that a gasket having a volume V _G larger than V ₁ is inserted, and a lid or a flange is pressed against the surface of the gasket protruding from the groove by a spring force.

[0009]

According to the present invention, the gasket volume V _G is made larger than the groove volume V _{1 and the} lid or flange is pressed against the surface of the gasket protruding from the groove by the spring force. There is no need to perform a seal depending on the rubber elasticity of. For this reason, the complete sealability can be maintained for a long period of time without using an expensive gasket as in the past and without using a highly finished surface as a contact surface with the gasket. In addition, since the gasket completely fills the inside of the groove, there is little risk of ingress of water or the like, and there is no need to apply paint or the like to prevent intrusion.

[0010]

The present invention will be described in more detail below with reference to the embodiments shown in FIGS. In FIG. 1, 1 is a power device having an opening, 2 is a sealing surface thereof, and 3 is an annular groove formed in this sealing surface. Reference numeral 4 is a gasket made of nitrile rubber or the like inserted in the groove 3, and the volume V _G of the gasket 4 is larger than the groove volume V ₁ of the groove 3, so that the gasket 4 fills the inside of the groove 3. In addition, a part of it protrudes from the groove 3.

Reference numeral 5 denotes a lid or a flange that covers the opening of the power device 1, and is attached to the power device 1 by a bolt 7 with a disc spring 6. The lid or flange 5 contacts the surface of the gasket 4 protruding from the groove 3, and when the bolt 7 is tightened, the lid or flange 5 is pressed against the surface of the gasket 4 by the spring force of the disc spring 6. The surface pressure applied to the gasket 4 is limited by its type and hardness, but with nitrile rubber gaskets, it is 10-30
Good sealing performance was obtained with a surface pressure of 0 kg / cm ² .

At this time, a gap 8 is always formed between the lower surface of the lid or the flange 5 and the sealing surface of the power device 1. The gap size G may be set so that 0 <G is always maintained. However, when used in a place where it is exposed to water such as rain, the gap size is set to about 0.5 to 2 mm to prevent water retention. As shown in FIG. 2, it is preferable to form a large gap 9 between the end of the lid or the flange 5 and the power device 1.

In the sealing structure of the present invention thus constructed, the sealing surface pressure is the spring 6 inserted into the bolt 7 or the like.
Given by For this reason, the gasket 4 only needs to have a function as a filler that blocks passage of the atmosphere or gas containing water, and the temperature characteristic of rubber elasticity of the gasket 4 can be almost ignored.

To confirm this effect, a comparatively inexpensive nitrile rubber gasket was subjected to a deterioration test at 120 ° C., and the results are shown in Table 1. As shown in Table 1, the sealing structure of the present invention has markedly improved sealing performance as compared with the conventional structure, and shows that there is no characteristic deterioration due to creep of the gasket even at high temperatures. Further, even when it was kept at a low temperature of −50 ° C., no leakage occurred, and it was confirmed that the sealing structure of the present invention is effective even at a low temperature at which rubber elasticity does not work. However, at 120 ° C, the gasket was softened and had fluidity, so it was necessary to limit the gap dimension G to 1 mm or less.

[0015]

[Table 1]

[0016]

As described above, since the sealing structure for electric power equipment of the present invention seals without depending on the rubber elasticity of the gasket, an expensive gasket considering the temperature characteristics of rubber elasticity is used. Even without it, it is possible to maintain a perfect sealing property for a long period of time. In addition, since the sealing is performed by the spring force, the gasket also adheres to minute irregularities and scratches. Therefore, normal machined surface accuracy (3
Sealing is possible even with 5S). Furthermore, since the gasket completely fills the inside of the groove and the gap is formed, there is little risk of water and the like entering, and it is not necessary to apply paint or the like for preventing entry. In addition, since the gasket is exposed only to the narrow gap, it is possible to reduce the diffusion of moisture and gas into the inside of the gasket.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a main part showing another embodiment of the present invention for A, B, and C.

FIG. 3 is a cross-sectional view showing a conventional example.

FIG. 4 is a cross-sectional view showing a deformation of a gasket in a conventional example, where A is a natural state and B is a pressurized state.

FIG. 5 is a cross-sectional view of a main part showing a relationship between a groove and a gasket in a conventional example in each of A, B, and C.

[Explanation of symbols]

1 power equipment, 2 sealing surface, 3 groove, 4 gasket, 5 lid or flange 6 spring, 7 bolt, 8 gap, 9 gap

Claims (1)

[Claims] 1. A gasket having a volume V _G larger than the groove volume V ₁ is inserted into a groove having a groove volume V ₁ formed on a sealing surface of an electric power device, and a surface protruding from the groove of the gasket is inserted. A sealing structure for electric power equipment, wherein a lid or a flange is pressed by a spring force.