Medical port

1. A medical port comprising:

a disc-shaped valve in which an insertion hole is formed in a central portion;

a base seat that supports the valve from a lower surface side and has a hole; and

a cover that has a fitting hole exposing an upper surface of the central portion of the valve and covers at least a peripheral edge of the valve from the upper surface side,

the fitting hole being formed so that when an inserting body has been inserted into the insertion hole and the hole of the base seat, a fit between the inserting body and the fitting hole can cause the inserting body to be locked against the cover,

wherein an annular protrusion is formed in the valve,

the annular protrusion being formed in a stepped surface that is formed by forming an annular groove around the central portion of the valve so that in a state in which the inserting body is locked against the cover, the annular protrusion is in contact with an outer circumferential surface of a leading end portion of the inserting body,

wherein the cover has an annular hook portion that can engage with the annular groove,

wherein the base seat has an annular projection that is formed along a peripheral edge portion of the hole provided in the base seat and that is positioned outwardly from the annular hook portion in a radial direction,

wherein a portion of the valve that is located outside the annular projection is compressed by the cover and the base seat,

wherein a ring-shaped protrusion located at a radially inner side of the annular projection and surrounding the insertion hole is formed on the lower surface of the valve so that portions of the ring-shaped protrusion are disposed on a straight line extending in the same direction as a longitudinal direction of the insertion hole and in the vicinity of both ends of the insertion hole in the longitudinal direction,

wherein the ring-shaped protrusion is spaced away from the insertion hole by a non-zero distance,

wherein the ring-shaped protrusion and an opening wall surface of the base seat are spaced apart by a distance forming a gap, so that the ring-shaped protrusion is not in contact with the annular projection, in a state in which the inserting body is not inserted in the insertion hole, wherein the open wall surface forms a wall surface of the hole, and

wherein the ring-shaped protrusion has a first radiused surface on a radially inner side of the ring-shaped protrusion, and a second radiused surface on a radially outer side of the ring-shaped protrusion, a height of the ring-shaped protrusion gradually increasing from the radially inner and outer sides toward a middle portion of the ring-shaped protrusion.

2. The medical port according to claim 1 , wherein the annular protrusion is formed from a position in the stepped surface that is below the upper surface of the central portion of the valve.

3. The medical port according to claim 2 , wherein the annular protrusion is formed from a position that is 0.2 mm to 0.6 mm below the upper surface of the central portion of the valve in a vertical direction.

4. The medical port according to claim 1 , wherein the annular protrusion satisfies a relationship below:

0.2≦( W 2− W 1)/2≦0.6

where W 1 is an outer diameter (mm) of the central portion as seen when the valve is viewed from above from its upper surface side, and

W 2 is an outer diameter (mm) of the annular protrusion as seen when the valve is viewed from above from its upper surface side.

5. The medical port according to claim 1 , wherein the annular protrusion has a radiused surface having a radius of curvature of more than 0 mm and not more than 0.4 mm.

6. The medical port according to claim 1 , wherein in the lower surface of the valve, a minimum distance between each of the portions of the ring-shaped protrusion disposed in the vicinity of both ends of the insertion hole in the longitudinal direction and the end of the insertion hole near that portion is more than 0 mm and not more than 0.15 mm.

7. The medical port according to claim 1 , wherein a maximum height of each of the portions of the ring-shaped protrusion disposed in the vicinity of both ends of the insertion hole in the longitudinal direction is 0.2 mm to 0.5 mm.

8. The medical port according to claim 1 , wherein an inner circumference of the ring-shaped protrusion as seen when the valve is viewed from above from its lower surface side has a circular shape.

9. The medical port according to claim 1 , wherein the shape of a cutting plane as seen when the ring-shaped protrusion is cut in a radial direction is the same whichever radial direction the ring-shaped protrusion is cut.

10. The medical port according to claim 1 , wherein the ring-shaped protrusion is located on a radially inner side of the opening wall surface of the base seat.