Patent ID: 6949847

Claim:
A rotary joint including a stator and a rotor rotatably coupled and supported to the stator, an annular space being formed between the stator and the rotor, and an electric signal slip ring provided in the annular space for passing electric signals between the stator and the rotor, the rotary joint characterized in that an air blowing passage is provided which has one end opening into the stator at a first air blowing hole, the other end opening into the rotor at a second air blowing hole, and an intermediate part passing through the annular space in which the electric signal slip ring is provided, and the rotary joint is configured to alternately carry out a first air blowing operation and a second air blowing operation to discharge wear particles produced by the electric signal slip ring to the exterior of the rotary joint, wherein in the first air blowing operation, air is blown into the air blowing passage through one of the first and second air blowing holes while relatively rotating the stator and the rotor, and the air is discharged through the other of the first and second air blowing holes, and wherein in the second air blowing operation, air is blown into the air blowing passage through the other of the first and second air blowing holes while relatively rotating the stator and the rotor, and the air is discharged through said one of the first and second air blowing holes so that direction of air blowing through the air blowing passage is reversed from the first air blowing operation.