Patent ID: 6851728

Claim:
A pipe-coupling device comprising: a joint body ( 2 ) having an opening ( 2 h ) for receiving one end of a pipe (P) to be coupled and having external threads ( 2 d ) formed in its outer periphery around said opening ( 2 h ); a locknut member ( 5 ) having a first end portion and a second end portion, the first end portion including internal threads ( 5 a ) in its inner periphery to engage with said external threads ( 2 d ) of said joint body ( 2 ), the second end portion including an internal conical surface ( 5 c ) which increases in diameter in an axial direction toward said first end portion; an annular core member ( 6 ) disposed within said locknut member ( 5 ), said core member ( 6 ) having a guide portion ( 6 c ) at one end thereof and having a plurality of separate apertures ( 6 d ) formed in said guide portion ( 6 c ) spaced circumferentially from each other; a plurality of locking members ( 7 ) received in said apertures ( 6 d ) of said core member ( 6 ), each of said locking members ( 7 ) having a gripping portion ( 7 b ) in its inner surface for contacting with an outer periphery of the pipe (P) when received in said opening ( 2 h ) of said joint body ( 2 ), and having a contact portion ( 7 a ) in its outer surface for contacting with said internal conical surface ( 5 c ) of said locknut member ( 5 ); a substantially annular wire ( 8 ) arranged on the outer periphery of said core member ( 6 ); and a through path ( 7 d , 7 e ) formed in each of said locking members ( 7 ) extending in the widthwise direction, said through path ( 7 d , 7 e ) being formed by a through hole or an inner groove such that said wire ( 8 ) passes through said through path ( 7 d , 7 e ) so as to prevent the locking members ( 7 ) from being dropped out of said core member ( 6 ) inwardly in a radial direction; wherein upon rotation of said locknut member ( 5 ) onto said joint body ( 2 ) in a tightening direction, said internal conical surface ( 5 c ) of said locknut member ( 5 ) slidably contacts with the contact portions ( 7 a ) of said locking members ( 7 ) so as to press the locking members ( 7 ) radially inwardly to cause the gripping portions ( 7 b ) of said locking members ( 7 ) to grip said outer periphery of the pipe (P) received in said opening ( 2 h ).