Seal ring
The present invention provides a seal ring capable of maintaining excellent low torque generation performance for a long term. A seal ring ( 1 ) is mounted on an annular groove formed on one member consisting of either a housing having a shaft hole or a rotary shaft inserted into the shaft hole, partly projects from the annular groove and contacts a surface of other member consisting of either the housing or the rotary shaft, and slidably contacts a side wall surface of the annular groove at a non-sealed fluid side thereof, thereby sealing an annular gap between the one member and the other member. An outer diameter side ( 2 a ) of the side surface ( 2 ) of the ring to be subjected to at least the side wall surface of the annular groove is formed as an inclined surface having an inclined angle in such a way as to decrease a width of the ring from the outer diameter side of the side surface of the ring to an inner diameter side of the side surface thereof. A concave portion ( 3 ) which does not contact the side wall surface of the annular groove and communicates with an inner circumferential surface ( 1 b ) of the ring is formed on a portion of the inner diameter side ( 2 b ) of the side surface of the ring not projecting from the annular groove.
1. A seal ring which is mounted on an annular groove formed on one member consisting of either a housing having a shaft hole or a rotary shaft inserted into said shaft hole, partly projects from said annular groove and contacts a surface of other member consisting of either said housing or said rotary shaft, and slidably contacts a side wall surface of said annular groove at a non-sealed fluid side thereof, thereby sealing an annular gap between said one member and said other member,
wherein an outer diameter side of said side surface of said ring to be subjected to at least said side wall surface of said annular groove is formed as an inclined surface having an inclined angle in such a way as to decrease a width of said ring from said outer diameter side of said side surface of said ring to an inner diameter side of said side surface thereof;
said inclined angle of said inclined surface with respect to a plane perpendicular to an axial direction of said seal ring is set to a range of 1.5 to 5 degrees;
said inner diameter side of said side surface of said ring is formed as a non-inclined surface;
a concave portion which does not contact said side wall surface of said annular groove and communicates with an inner circumferential surface of said ring is formed on a portion of said inner diameter side of said side surface of said ring not projecting from said annular groove; and
said concave portion is V-shaped along a circumferential direction of said seal ring.
2. A seal ring according to claim 1 , wherein a depth of said concave portion from said sliding contact surface becomes shallower from a deepest portion disposed at a position other than ends of said concave portion in said circumferential direction of said ring toward both ends thereof in said circumferential direction thereof and is constant in a radial direction of said ring.
3. A seal ring according to claim 2 , wherein a boundary portion disposed between said ends of said concave portion in said circumferential direction of said ring and said sliding contact surface is formed at a steep angle with said sliding contact surface.
4. A seal ring according to claim 1 , wherein a plurality of said concave portions is formed by spacing said concave portions at certain intervals in said circumferential direction of said seal ring.
5. A seal ring according to claim 1 , an opening dimension of an outer diameter side of said concave portion is set larger than that of an inner diameter side thereof.