초록 ▼

A stern tube sealing assembly and a seal ring thereof has a key part having an inverted V-shape, a front step part on the front side, and a back step part on the back side thereof. The seal ring width in a propulsion-shaft axis direction becomes thinner in the transition area from the key part towar

A stern tube sealing assembly and a seal ring thereof has a key part having an inverted V-shape, a front step part on the front side, and a back step part on the back side thereof. The seal ring width in a propulsion-shaft axis direction becomes thinner in the transition area from the key part toward a heel part. The inner diameter of the key part at the back step part is greater than that of the key part at the front step part. The ring has a lip part having a V-shaped lip tip protruding inwardly in the radial direction and a spring groove having a semicircular cross-section. The center of the spring groove is nearer to the inboard side than the lip tip, by an offset in the axis direction, the offset being within approximately 10% of the orthogonal projection length of the width of the lip back.

대표청구항 ▼

1. A seal ring assembly comprising: a seal ring for sealing between a casing member provided on an outboard side of a stern tube and a ship propulsion shaft that penetrates an inner space of the casing member for preventing seawater from entering an inboard side of the stern tube, the seal ring comp

1. A seal ring assembly comprising: a seal ring for sealing between a casing member provided on an outboard side of a stern tube and a ship propulsion shaft that penetrates an inner space of the casing member for preventing seawater from entering an inboard side of the stern tube, the seal ring comprising:a key part fitted in an annular groove formed in the casing member;a heel part radially extending inwardly from the key part toward a center axis of the ship propulsion shaft;an arm part extending at a predetermined incline angle from an inner end part of the heel part toward a front surface side of the seal ring, an inner periphery side of the arm part being supported by a back-up member provided with the casing member;a lip part extending from a front end part of the arm part, the lip part engaging at a contacting point, with an outer periphery surface of a liner that is fitted around or on an outer periphery surface of the ship propulsion shaft,wherein the key part has an apex part having an inverted V-shaped cross-sectional profile, with an apex of the inverted V-shaped cross-sectional profile extending radially outwardly so that the apex lies in a plane that equally divides a width of the key part, which extends along an axis direction of the ship propulsion shaft,wherein the key part has a front step part on the front surface side of the seal ring and a back step part on a back surface side of the seal ring, so that the width of the seal ring becomes thinner in a transition area from the key part toward the heel part,wherein an inner diameter of the key part at the back step part is greater than an inner diameter of the key part at the front step part, to allow a space to be formed along the radial direction between an inner periphery of the back step part and the casing member,wherein the lip part has a V-shaped lip tip protruding radially inwardly and a spring groove having a semicircular cross-section configured to receive a ringed spring that allows the lip part to be thrustable radially inwardly toward the ship propulsion shaft,wherein a center of the spring groove is positioned more inwardly toward the front end part of the arm part than an apex of the V-shaped lip tip, by an offset extending along the ship propulsion shaft axis direction,wherein the lip part has a lip back face extending from the apex of the V-shaped lip tip toward the front end part of the arm part, and a lip front face extending from the apex of the V-shaped lip tip away from the front end part of the arm part,wherein the offset is within approximately 10% of an orthogonal projection length of a width of the lip back face, the orthogonal projection being a projection extending axially along the ship propulsion shaft axis direction,wherein the lip front face has an angle β, which is an incline angle at which the lip front face forms relative to the ship propulsion shaft axis direction toward the front surface side and the lip back face side has an angle α, which is an incline angle relative to the ship propulsion shaft axis direction toward the back surface side, andwherein the angles α and β have following relationships: β>α, β=45 to 55°, and α=25 to 30°. 2. The seal ring assembly according to claim 1, wherein: the arm part has a thickness H, which is a thickness of the arm part at an arm contacting point where the arm part is configured to contact with the back-up member,the lip portion and the arm has a length L that extends between the apex of the V-shaped lip tip to the arm contacting point, andthe thickness H and the length L have a following relationship: H3/L4=(10 to 30)×10−4(in mm−1). 3. The seal ring assembly according to claim 1, wherein the arm part and the lip part have stiffness that allows the lip part to have a contacting surface configured to contact with the outer periphery of the liner and have a width of 2 to 3 mm, when pressure on the front surface side of the seal ring is higher than pressure on the back surface side of the seal ring, by 0.15 MPa, while the key part is seated in the annular groove, the liner is installed and the lip part is in contact with the outer periphery of the liner. 4. A stern tube sealing assembly comprising: a casing member provided on an outboard side of a stern tube;a ship propulsion shaft that penetrates an inner space of the casing member;a liner fitted around or on an outer periphery surface of the ship propulsion shaft; anda seal ring provided between the casing member and the ship propulsion shaft that prevents seawater from entering an inboard side of the stern tube,wherein the casing member has an annular groove and a back-up member, andwherein the seal ring comprising:a key part fitted in the annular groove of the casing member;a heel part radially extending inwardly from the key part toward the ship propulsion shaft;an arm part extending at a predetermined incline angle from an inner end part of the heel part toward a front surface side of the seal ring, an inner periphery side of the arm part being supportable by the back-up member; a lip part extending from a front end part of the arm part, the lip part engaged, at a contacting point, with an outer periphery surface of the liner,wherein the key part has an apex part having an inverted V-shaped cross-sectional profile, with an apex of the inverted V-shaped cross-sectional profile extending radially outwardly so that the apex lies in a plane that equally divides a width of the key part, which extends along an axis direction of the ship propulsion shaft,wherein the key part has a front step part on the front surface side of the seal ring and a back step part on a back surface side of the seal ring, so that the width of the seal ring becomes thinner in a transition area from the key part toward the heel part,wherein an inner diameter of the key part at the back step part is greater than an inner diameter of the key part at the front step part, so that a space is formed in the radial direction between an inner periphery of the back step part and the casing member,wherein the lip part has a V-shaped lip tip protruding radially inwardly and a spring groove having a semicircular cross-section configured to receive a ringed spring that thrusts the lip part radially inwardly toward the ship propulsion shaft,wherein a center of the spring groove is positioned more inwardly toward the front end part of the arm part than an apex of the V-shaped lip tip, by an offset extending along the ship propulsion shaft axis direction,wherein the lip part has a lip back face extending from the apex of the V-shaped lip tip toward the front end part of the arm part, and a lip front face extending from the apex of the V-shaped lip tip away from the front end part of the arm part,wherein the offset is within approximately 10% of an orthogonal projection length of a width of the lip back face, the orthogonal projection being a projection extending axially along the ship propulsion shaft axis direction,wherein the lip front face has an angle β, which is an incline angle at which the lip front face forms relative to the ship propulsion shaft axis direction toward the front surface side and the lip back face has an angle α, which is an incline angle relative to the ship propulsion shaft axis direction toward the back surface side, andwherein the angles α and β have following relationships: β>α, β=45 to 55°, and α=25 to 30°. 5. The stern tube sealing assembly according to claim 4, wherein: the arm has a thickness H, which is a thickness of the arm part at an arm contacting point where the arm part contacts with the back-up member,the lip portion and the arm has a length L that extends between the apex of the V-shaped lip tip to the arm contacting point, andthe thickness H and the length L have a following relationship: H3/L4=(10 to 30)×10−4 (in mm−1). 6. The stern tube sealing assembly according to claim 4, wherein the arm part and the lip part have stiffness that allows the lip part to have a contacting surface configured to contact with the outer periphery of the liner and have a width of 2 to 3 mm, when pressure on the front surface side of the seal ring is higher than pressure on the back surface side of the seal ring, by 0.15 MPa, while the key part is seated in the annular groove, the liner is installed and the lip part is in contact with the outer periphery of the liner. 7. The stern tube sealing assembly according to claim 4, wherein the annular groove has opposing walls each with a relief groove near a middle position of the respective wall along the radial direction.