Quick connect fitting

1. A quick connect fitting comprising:

a coupling assembly having

a coupling unit having

a main body having

a longitudinal direction;

a first end; and

a second end being longitudinally opposite the first end of the main body;

a containing hole longitudinally defined inside the main body and having a bottom;

a seal being annular and abutting against the first end of the main body;

a socket connected to the coupling unit and having

a surrounding wall having

a longitudinal direction;

a first end;

a second end being longitudinally opposite the first end of the surrounding wall; and

a peripheral surface;

a chamber formed inside the surrounding wall;

multiple elongated holes being adjacent to the first end of the surrounding wall, arranged at equiangular intervals, defined through the surrounding wall, and communicating with the chamber, and each of the multiple elongated holes extending toward the second end of the surrounding wall;

multiple retaining holes disposed between the second end of the surrounding wall and the multiple elongated holes, arranged at equiangular intervals, defined through the surrounding wall, and communicating with the chamber; and

an inserting hole longitudinally defined through an end of the socket distal from the coupling unit and communicating with the chamber;

a selection assembly mounted inside the socket and having

a selection valve movably mounted in the chamber and having at least one vent;

a receiving unit having

a receiving section having

a surface;

a longitudinal direction;

a first end facing to the inserting hole; and

a second end longitudinally opposite the first end of the receiving section;

a receiving hole longitudinally defined in the receiving section and communicating with the at least one vent;

multiple first through holes being adjacent to the first end of the receiving section, arranged at equiangular intervals, and respectively aligned with the multiple elongated holes, and each one of the multiple first through holes defined in the surface of the receiving section and communicating with the receiving hole;

multiple second through holes arranged at equiangular intervals, and respectively aligned with the multiple elongated holes, and each one of the multiple second through holes defined in the surface of the receiving section and communicating with the receiving hole;

a restoring elastic unit elongating along the longitudinal direction of the main body, mounted in the containing hole and having

two opposite ends disposed in the longitudinal direction of the main body;

one of the two opposite ends of the restoring elastic unit abutting against the bottom of the containing hole; and

the other end of the restoring elastic unit abutting against the selection valve; and

an abutting elastic unit elongating along the longitudinal direction of the surrounding wall and having

two opposite ends disposed in the longitudinal direction of the surrounding wall;

one of the two opposite ends of the abutting elastic unit abutting against a spacer;

a blocking component mounted inside the receiving unit, elongating along the longitudinal direction of the receiving section, and abutted by the end of the abutting elastic unit that is opposite the bottom of the containing hole;

multiple blocking balls respectively contained in the multiple elongated holes and abutted by the blocking component;

multiple locking balls respectively contained in the multiple retaining holes and abutted by the surface of the receiving section of the receiving unit;

an operating assembly assembled on the socket and having

a first operating sleeve mounted around the socket and blocked by the multiple locking balls;

a first compression spring mounted on the socket, mounted around the socket, and having

two opposite ends;

one of the two opposite ends of the first compression spring abutting against the coupling unit socket; and

the other end of the first compression spring abutting against the first operating sleeve;

a second operating sleeve mounted around the socket and blocked by the multiple blocking balls; and

a second compression spring being in a compressed status, encircling the socket, and having

two opposite ends;

one of the two opposite ends of the second compression spring abutting against the first operating sleeve;

the other end of the second compression spring abutting against the second operating sleeve.

2. The quick connect fitting as claimed in claim 1 , wherein

the spacer is mounted inside the coupling unit, is annular, and has a receiving recess; and

the receiving recess and the first end of the main body face to a same direction.

3. The quick connect fitting as claimed in claim 2 , wherein the

restoring elastic unit is a conical compression spring.