| 摘要 |
A fluid swivel is described, of the type which includes a ring-shaped outer structure (12, FIG. 2 ) that rotates about a ring-shaped inner structure (14), and which form an annular chamber (18) between them and a pair of gap passages (24, 26) between them which are sealed by pressure seals (30, 32). The outer structure includes a body (70) forming part of the annular chamber and a seal ring (72) mounted on an end of the body and abutting one side of the pressure seal. The seal ring is axially shiftable on the end of the body, so that when the body expands radially as a result of high pressure fluid being introduced into the annular chamber, the seal ring does not have to expand a similar amount and therefore does not have to cause a large increase in the width of the extrusion gap (62) at the downstream end of the pressure seal. A centering mechanism (110) urges the seal ring to remain substantially centered on the body, and can be formed by a ring of compressible material lying between shoulders (120, 122, FIG. 3 ) respectively on the body and on the seal ring, or can be formed by leaf spring portions (154, FIG. 5 ) of one of the parts. Registers (180, 182) on the seal ring and on the body can engage each other to assure concentricity when the body has expanded a predetermined amount under a predetermined high pressure of at least 50 atmospheres in the annular chamber.
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