Shaft sealing structure
A shaft sealing structure includes a V-packing; a first guide bush attached to an inner circumference of the holder; and a scraper arranged at an end of the holder. The V-packing is formed of a thick-walled top portion, a thin-walled inner side skirt portion extending diagonally inward from the top portion, and a thin-walled outer side skirt portion extending diagonally outward from the top portion. The inner side skirt portion slidably contacts an outer surface of the rod at a distal end of the inner side skirt portion, and the outer side skirt portion abuts against an inner surface of the holder at a distal end of the outer side skirt portion. The top portion is sandwiched between the scraper and the first guide bush, and the inner and outer side skirt portions are freely deformable inside a space formed between the first guide bush and the scraper.
1. A shaft sealing structure arranged between a rod configured to be driven within a predetermined fluid and move in an axial direction, and a holder in which the rod is accommodated, the shaft sealing structure comprising:
a V-packing;
a first guide bush attached to an inner circumference of the holder; and
a scraper arranged at an end of the holder, wherein the V-packing is formed of a top portion formed to be thick-walled, an inner side skirt portion formed to be thin-walled and extending diagonally inward from the top portion, and an outer side skirt portion formed to be thin-walled and extending diagonally outward from the top portion,
the inner side skirt portion slidably contacts an outer surface of the rod at a distal end of the inner side skirt portion, and the outer side skirt portion abuts against an inner surface of the holder at a distal end of the outer side skirt portion, and
the top portion is sandwiched between the scraper and the first guide bush, and the inner side skirt portion and the outer side skirt portion are freely deformable inside a space formed between the first guide bush and the scraper.
2. The shaft sealing structure according to claim 1 , wherein
the top portion includes a convex portion configured to protrude to a side opposite to the inner side skirt portion and the outer side skirt portion,
the first guide bush is equipped with a recessed portion in which the upper V-packing is accommodated, and abuts against the convex portion of the V-packing on a bottom surface of the recessed portion, and
an end of the scraper abuts against a rear surface of the top portion of the V-packing.
3. The shaft sealing structure according to claim 2 , wherein the first guide bush includes a first grease reservoir that opens on the bottom surface of the recessed portion.
4. The shaft sealing structure according to claim 1 , further comprising a second guide bush attached to the inner circumference of the holder, wherein
a rubber seal packing is mounted between the first guide bush and the second guide bush.
5. The shaft sealing structure according to claim 4 , wherein
the rubber seal packing includes an annular plate portion, an inner side cylindrical portion that extends from an inner circumferential portion of the annular plate portion, and an outer side cylindrical portion that extends from an outer circumferential portion of the annular plate portion, and
an inner circumference of the inner side cylindrical portion slidably contacts the outer surface of the rod, and an outer circumference of the outer side cylindrical portion slidably contacts the inner surface of the holder.
6. The shaft sealing structure according to claim 4 , wherein the first guide bush includes a grease reservoir that opens toward the rubber seal packing.
7. The shaft sealing structure according to claim 4 , wherein the second guide bush includes a grease reservoir on an inner circumferential surface thereof that faces the rod.
8. The shaft sealing structure according to claim 1 , wherein the V-packing is made of a fluorine resin.
9. A valve adopting the shaft sealing structure according to claim 1 .