Leakproof ball valve structure

A leakproof ball valve structure, comprising:

• a valve body (10) having a center defining a through hole (11);
• a ball (30) received in said through hole (11) of said valve body (10);
• a central shaft (50) mounted on said valve body (10) for rotating said ball (30);
• two side covers (20) each secured on one of two sides of said valve body (10) respectively;
• two leakproof assemblies (40) each mounted between said valve body (10) and a respective one of said two side covers (20) and each includes:
• a retaining ring (42) having a first end and a second end, said first end facing said ball (30) and formed with a flange (422) having an outer periphery closely fit in an inner wall of said through hole (11) of said valve body (10), said second end formed with a fitting portion (424) rested on a respective one of said two side covers (20), said fitting portion (424) having an outer diameter smaller than that of said flange (422);
• a seal ring (41) secured in said first end of said retaining ring (42) and urged on an outer wall of said ball (30);
• a leakproof ring (43) mounted on an outer periphery of said fitting portion (424) of said retaining ring (42) and rested on said flange (422) of said retaining ring (42);
• a washer (44) mounted on said outer periphery of said fitting portion (424) of said retaining ring (42) and rested on said leakproof ring (43);
• and
• an elastic member (45) mounted on said outer periphery of said fitting portion (424) of said retaining ring (42) and urged between said washer (44) and said respective side cover (20);
• wherein, said ball (30) is floating ball mounted in said through hole (11) of said valve body (10) in a floating manner, so that said ball (30) is driven to float by an upstream pressure to displace in said valve body (10), and a gap is defined between said ball (30) and said valve body (10).