Gasket for electrical junction box of railcar and electrical junction box of railcar

1. A gasket for an electrical junction box of a railcar,

the electrical junction box including: a box main body including a side peripheral wall portion defining an opening communicating with an outer space of the box main body; and a cover closing the opening,

the gasket being fitted in a groove portion formed on a contact surface of the side peripheral wall portion or a contact surface of the cover,

the gasket comprising:

small width portions, a width of each of the small width portions being smaller than a width of the groove portion; and

large width portions each having projections projecting toward both respective sides of the small width portion in a width direction and having a larger width than the width of the small width portions,

the small width portions and the large width portions being alternately provided.

2. The gasket according to claim 1 , wherein:

the gasket has a loop shape and is fitted in the groove portion, the groove portion including straight portions and corner portions;

the gasket includes first regions fitted in the corner portions and second regions fitted in the straight portions; and

a length of each of the small width portions in a circumferential direction at one of the first regions is shorter than a length of each of the small width portions in the circumferential direction at the second region.

3. The gasket according to claim 1 , wherein:

the gasket has a loop shape and is fitted in the groove portion, the groove portion including straight portions and corner portions, each of the corner portions having at least one inflection point; and

each of the projections of the large width portions fitted in the corner portion has such a shape that a length of the projection of the large width portions in the circumferential direction of the gasket decreases as the projection extends toward an outer side of the small width portions in the width direction.

4. The gasket according to claim 1 , wherein an end surface of the projection of each of the large width portions is inclined toward a bottom surface of the groove portion, the end surface being located on the same side of the groove portion as the opening.

5. An electrical junction box of a railcar, the electrical junction box comprising:

a box main body including a side peripheral wall portion defining an opening communicating with an outer space of the box main body;

a cover closing the opening;

a gasket fitted in a groove portion formed on a contact surface of the side peripheral wall portion or a contact surface of the cover; and

an elastic member accommodated in the box main body so as to be located adjacent to one of the side wall portions,

the gasket including

a plurality of small width portions, a width of each of the small width portions being smaller than a width of the groove portion, and

a plurality of large width portions, each of the large width portions having projections projecting toward both respective sides of the small width portions in a width direction and having a larger width than the small width portions,

the small width portions and the large width portions being alternately provided, and

one of the projections of the large width portion located adjacent to the elastic member among the plurality of large width portions overlapping the elastic member.

6. An electrical junction box of a railcar, the electrical junction box comprising:

a box main body including a side peripheral wall portion defining an opening communicating with an outer space of the box main body;

a cover closing the opening; and

a loop-shaped gasket fitted in a groove portion formed on a contact surface of the side peripheral wall portion or a contact surface of the cover,

the groove portion including straight portions and corner portions, each of the corner portions including at least one inflection point,

the gasket including

small width portions, a width of each of the small width portions being smaller than a width of the groove portion, and

large width portions each having projections projecting toward both respective sides of the small width portions in a width direction and having a larger width than the small width portions,

the small width portions and the large width portions being alternately provided, and

each of the projections of the large width portions fitted in the corner portion having such a shape that a length of the projections of the large width portions in the circumferential direction of the gasket decreases as the projections extend toward an outer side of the small width portions in the width direction.

7. The electrical junction box according to claim 6 , wherein:

the box main body includes holes, fasteners being inserted through the holes, the fasteners fastening the cover to the box main body;

the holes are located on extended lines of the straight portions; and

the corner portions curve so as to bypass the holes.

8. The electrical junction box according to claim 6 , wherein:

the contact surface is inclined from a horizontal plane in a state where the electrical junction box is attached to the railcar; and

a drain passage is formed at a portion of the inclined contact surface, the portion being located at a vertically lower side, the groove portion being open to an outside through the drain passage.