Shaft sealing device for sliding portion of needle valve in paint spray gun

摘要

A shaft sealing device is disposed on the sliding portion of a needle valve stem in a spray gun for spraying a compressed fluid (paints), particularly in an airless paint spray gun, and is capable of enhancing the durability of the portion to be sealed. The shaft sealing device comprises a main packing for the needle valve which permits the needle valve stem to be pierced therethrough and slid in the center thereof. The shaft sealing device has a concave portion formed therein in the axial direction, a ring-shaped auxiliary packing of an elastic rubber body fitted in the concave portion, a packing rest provided with a convex portion, and a packing gland for tightening the main packing from behind. The packing gland tightens the ring-shaped auxiliary packing which is elastically deformed. The elastic deformation of the auxiliary packing extends to the main packing, whereby the needle valve stem can be uniformly sealed with the main packing and stable durability can be obtained even by a small tightening force.