Connector

1. A connector comprising a first member and a second member, the first member and the second member being coupled to each other in a coupling portion,

wherein the first member includes, on a side opposite to the coupling portion, a main portion that can be connected to and disconnected from a counterpart connector other than the connector,

a flow channel via which the main portion and the second member are in communication with each other extends along a central axis of the connector,

one of the first member and the second member includes an outer cylindrical portion that has a hollow cylindrical shape and is coaxial with the central axis,

the other of the first member and the second member includes an inner cylindrical portion that has a hollow cylindrical shape and is coaxial with the central axis,

in the coupling portion, the inner cylindrical portion is fitted in the outer cylindrical portion,

the outer cylindrical portion includes a first engagement portion and an abutment portion,

the inner cylindrical portion includes a second engagement portion that engages the first engagement portion, and a leading end that is a front end of the inner cylindrical portion in a direction in which the inner cylindrical portion is fitted into the outer cylindrical portion,

as a result of the first engagement portion and the second engagement portion engaging each other, the leading end of the inner cylindrical portion abuts against the abutment portion of the outer cylindrical portion along the central axis, and

the abutment portion is an annular rib having a substantially circular cylindrical shape and protruding in such a manner that an inner circumferential surface of the flow channel of the one of the first member and the second member is extended toward the inner cylindrical portion.

2. The connector according to claim 1 , wherein at least one of the first engagement portion and the second engagement portion has an inclined surface that is inclined relative to the central axis, and

the inclined surface is inclined such that the leading end of the inner cylindrical portion abuts against the abutment portion of the outer cylindrical portion along the central axis.

3. The connector according to claim 1 , wherein the leading end of the inner cylindrical portion annularly abuts against the abutment portion so as to surround the flow channel.

4. The connector according to claim 1 , wherein an inner circumferential surface of the outer cylindrical portion has a first fitting surface, and

an outer circumferential surface of the inner cylindrical portion has a second fitting surface that is fitted to the first fitting surface.

5. The connector according to claim 4 , wherein, as a result of the first fitting surface and the second fitting surface being fitted to each other, the outer cylindrical portion and the inner cylindrical portion are coaxially positioned.

6. The connector according to claim 4 , wherein a liquid-tight seal is formed between the first fitting surface and the second fitting surface.

7. The connector according to claim 4 , wherein a lubricant is added between the first fitting surface and the second fitting surface.

8. The connector according to claim 1 , wherein an inner circumferential surface of the flow channel is continuous without a level difference and a gap between the first member and the second member.

9. The connector according to claim 1 , wherein the first member is rotatable relative to the second member.

10. The connector according to claim 1 , wherein the first member is unrotatable relative to the second member.

11. The connector according to claim 1 , wherein the main portion includes a male member or a female member.

12. The connector according to claim 1 , wherein the second member is connectable to an end of a flexible tube.

13. The connector according to claim 1 , wherein the second member is provided on a bypass injection port.

14. The connector according to claim 1 , wherein the first member and the second member are made of different materials.