US Patent 7455324 Pipe joint

A pipe joint provided with a joint main body having an insertion cylinder portion inserted to an end portion of a pipe to be connected, a clamp ring having a slit to fasten the end portion of the pipe inserted to the insertion cylinder portion by elastic fastening force, a diameter-expansion piece, releasable as to jump outward, held within the slit to expand the clamp ring against elastic force of the clamp ring, and a restriction sleeve covering the clamp ring as to restrict the outward jump of the diameter-expansion piece. And, a pipe-insertion detector, detecting the insertion of the pipe to a predetermined depth to release the restriction, is provided.