Pipe coupler with retaining ring structure

A pipe coupler with retaining ring structure, comprising:

• a tubular member having two open ends, which are defined as a front opening and a rear pipe connector;
• and the tubular member internally defining a tubular passage extending between and communicating with the front opening and the rear pipe connector, and being internally provided near the rear pipe connector with a circumferentially extended annular groove;
• a movable valve head being movably set in the tubular passage to openably seal the front opening;
• a retaining ring being fitted in the tubular passage and located adjacent to the rear pipe connector;
• the retaining ring including a hollow cylindrical section extended axially by an axial length and having two circumferentially opposite free ends and an outer contact surface corresponding to an inner side of the tubular member;
• the contact surface being provided with a circumferentially extended and radially protruded flange for engaging with the annular groove;
• the two circumferentially opposed free ends defining an elastically compressible gap between them;
• and the retaining ring internally defining a through bore, which is located at a radially inner side of the rear pipe connector;
• and
• a return spring being set in the tubular passage between the movable valve head and the retaining ring.