Electricity: conductors and insulators – Insulators – Special application
Reexamination Certificate
2001-03-09
2002-10-29
Reichard, Dean A. (Department: 2831)
Electricity: conductors and insulators
Insulators
Special application
C174S174000, C174S176000, C174S189000
Reexamination Certificate
active
06472604
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a seal construction of a polymer insulator having a core member, an outer cover member including a sheath portion and sheds, which is arranged on an outer surface of the core member, and securing metal fittings arranged on both ends of the core member, and particularly relates to a seal construction between the outer cover member and the securing metal fitting.
2. Description of Related Art
Generally, a polymer insulator having a core member, an outer cover member including a sheath portion and sheds, which is arranged on an outer surface of the core member, and securing metal fittings arranged on both ends of the core member is known. Moreover, various seal constructions between the outer cover member and the securing metal fitting are also known.
FIG. 4
is a schematic view showing one embodiment of a known seal construction of the polymer insulator. In
FIG. 4
, a polymer insulator
51
comprises an FRP core
52
as the core member, an outer cover member
55
having a sheath portion
53
and sheds
54
, which is arranged on an outer surface of the FRP core
52
, and securing metal fittings
56
arranged at both ends of the FRP core
52
. In
FIG. 4
, only one side of the polymer insulator is shown. The securing metal fitting
56
comprises a small diameter portion
61
for securing the FRP core
52
and a large diameter portion
62
arranged continuously from the small diameter portion
61
and having an open end portion
63
. A tip portion
71
of the sheath portion
53
is arranged between the large diameter portion
62
and the FRP core
52
. Between an inner surface
62
a
of the large diameter portion
62
and an outer surface
71
a
of the tip portion
71
, a silicon sealant of a room temperature vulcanizing (RTV) type
72
is arranged as a sealant.
Moreover, a protruding portion
72
a
of the silicon sealant of RTV type
72
is protruded from an end of a portion at which the inner surface
62
a
of the large diameter portion
62
and the outer surface
71
a
of the tip portion
71
are connected. In addition, in order to improve a seal property between the inner surface
62
a
of the large diameter portion
62
and the outer surface
71
a
of the tip portion
71
of the sheath portion
53
, two ring portions
73
-
1
and
73
-
2
projected from the outer surface
71
a
of the tip portion
71
of the sheath portion
53
are arranged.
As mentioned above, in the polymer insulator
51
, a connection portion between the outer cover member
55
and the securing metal fitting
56
is very important for preventing in intrusion of rain water which causes a deterioration of the FRP core
52
. Therefore, it is necessary to seal such a connection portion, and the connection portion requires a high reliability. In the known seal construction mentioned above, the protruded portion
72
a
of the sealant
72
is exposed at the open end portion
63
i.e. the sealant
72
is exposed to a natural environment.
Recently, a property of the sealant
72
is improved and it is possible to use the sealant
72
for a use of the polymer insulator
51
. However, a property of the sealant
72
is not always equal to that of the outer cover member
55
. Therefore, In order to further improve reliability, a seal construction, which does not depend on a property of the sealant
72
even when exposed to a severe natural environment, is desired.
In the known seal construction mentioned above in which the sealant
72
has the protruded portion
72
a
, if a dimension of the protruded portion
72
a
is made larger so as to improve a water immersion resistivity by keeping a long seal length, an exposed area of the sealant
72
becomes larger. Therefore, deteriorations due to rain water and ultraviolet rays become more severe, and also an anti-erosion property of the sealant becomes worse. On the other hand, if a dimension of the protruded portion
72
a
is made smaller so as to improve the problems due to the above deteriorations and antierosion property, it is not possible to maintain a seal reliability.
SUMMARY OF THE INVENTION
An object of the invention is to eliminate the drawbacks mentioned above and to provide a seal construction of a polymer insulator which can improve a water intrusion resistivity and prevent an erosion.
According to the invention, a seal construction of a polymer insulator has a core member, an outer cover member including a sheath portion and sheds, which is arranged on an outer surface of the core member, and securing metal fittings arranged on both ends of the core member, wherein a tip portion of the sheath portion is arranged between the securing metal fitting and the core member and a sealant is arranged between an inner surface of the securing metal fitting and an outer surface of the tip portion of the sheath portion. The seal construction includes be following:
(1) a small rib radially projects from the sheath portion of the outer cover member;
(2) a side surface of the small rib is connected to the open end portion of the securing metal fitting via the sealant; and
(3) the sealant does not protrude from a portion between the side surface of the small rib and the open end portion of the securing metal fitting.
In the present invention, by realizing the constructions: a small rib projected from the sheath portion of the outer cover member is arranged; a side surface of the small rib is connected to an open end portion of the securing metal fitting via the sealant; and the sealant is not protruded from a portion between the side surface of the small rib and the open end portion of the securing metal fitting, it is possible to suppress an affect for the sealant due to a rain water, an ultraviolet ray and so on. Therefore, it is possible to obtain an excellent connection life of the sealant and improve a water intrusion resistivity. In addition, it is possible to eliminate a generation of erosion at the protruded portion of the sealant and thus prevent an erosion of the outer cover member.
REFERENCES:
patent: 4435615 (1984-03-01), Kaczerginski et al.
patent: 5363266 (1994-11-01), Wiseman et al.
patent: 5563379 (1996-10-01), Kunieda et al.
patent: 5915761 (1999-06-01), Moriya et al.
patent: 6140573 (2000-10-01), Smith et al.
patent: 6282783 (2001-09-01), Abe
Imakoma Takashi
Nakamura Itsushi
Burr & Brown
Lee Jinhee J
NGK Insulators Ltd.
Reichard Dean A.
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