Quick connector

1. A quick connector for connecting a flexible tube to a mating pipe, comprising:

a connector body which is formed in a tubular shape as a whole, the connector body having on its one axial side a retainer holding portion for insertion of the mating pipe therein, on its other axial side a tube connecting portion to be press fitted into the tube, and a housing between the retainer holding portion and the tube connecting portion, the tube connecting portion being formed with a plurality of annular projections having surfaces whose diameters linearly increase towards the housing at one or more rates and that serve as detents for the tube by biting into an inner surface of the tube, the annular projections being formed in such a way as to be axially spaced apart from each other;

a retainer which is held in an axially fixed state by the retainer holding portion and serves as a detent for the mating pipe by axially engaging an engaging portion on an inner peripheral side thereof with an engageable portion of an outer peripheral surface of the mating pipe; and

a seal member which is fitted in the connector body and located in a seal holding portion of the housing, and serves as a seal by coming into contact with an outer peripheral surface of the inserted mating pipe;

wherein a portion of an outer surface of the tube connecting portion extending from the annular projection, which is closest to the housing, all the way to the housing is formed into a tapered surface whose diameter continuously, gradually and linearly enlarges toward the housing at a rate less than the one or more rates of any of the surfaces of the plurality of annual projections, and a diameter of an annular projection side of the tapered surface is set to be larger than a diameter of the outer surface of the tube connecting portion between the annular projections.

2. The quick connector according to claim 1 , wherein a flat surface which is parallel to an axial direction is provided between the annular projections in the tube connecting portion, and the diameter of the annular projection side of the tapered surface is set to be larger than a diameter of the flat surface.

3. The quick connector according to claim 1 , wherein a wall for causing a distal end face of the tube to abut against the wall rises radially outwardly from a jointing point between the tube connecting portion and the housing.

4. The quick connector according to claim 3 , wherein a maximum diameter of the tapered surface on a side of the jointing point and each annular projection is set to be substantially the same.

5. The quick connector according to claim 1 , wherein a diameter of the annular projection that is closest to the housing is set to be larger than a diameter of any other annular projection.

6. The quick connector according to claim 3 , wherein the wall rises substantially orthogonally from the jointing point.

7. The quick connector according to claim 1 wherein a seal member is located on the tube connecting portion side away from the retainer holding portion, and serves as a seal by coming into contact with an inner peripheral surface of the flexible tube.

8. The quick connector according to claim 1 wherein the length of the entire tube connecting portion divided by the outer diameter of the tube connecting portion from a jointing point between the tube connecting portion and the housing to an annular projection furthest along the tube connecting portion at any individual point is within the range of approximately 3.2 to 4.5.