Rotary joint

Abstract

Provided is a rotary joint capable of preventing the backflow of a fluid.　A negative pressure flow path R1 comprises a rotation shaft-side negative pressure flow path 21 formed in a rotation shaft 2, a housing-side negative pressure flow path 31 formed in a housing 3, and a negative pressure-side gap S1 formed between the rotation shaft-side negative pressure flow path 21 and the housing-side negative pressure flow path 31. A positive pressure flow path R2 comprises a rotation shaft-side positive pressure flow path 22 formed in the rotation shaft 2, a housing-side positive pressure flow path 32 formed in the housing 3, and a positive pressure-side gap S2 formed between the rotation shaft-side positive pressure flow path 22 and the housing-side positive pressure flow path 32. The rotary joint comprises negative pressure-side sealing members 4, 4 that seal the negative pressure-side gap S1, and positive pressure-side sealing members 5, 5 that seal the positive pressure-side gap S2.

Claims

1. A rotary joint comprising: a rotating shaft; a housing that rotatably supports the rotating shaft; a negative pressure passage having one end communicating with a suction port formed on the rotating shaft and the other end communicating with a negative pressure supply source connected to the housing; a positive pressure passage having one end communicating with a discharge port formed on the rotating shaft and the other end communicating with a positive pressure supply source connected to the housing; the negative pressure passage being composed of a rotating shaft-side negative pressure passage formed on the rotating shaft, a housing-side negative pressure passage formed on the housing, and a negative pressure gap formed between the rotating shaft-side negative pressure passage and the housing-side negative pressure passage; and a negative pressure-side sealing member for sealing the negative pressure gap and a positive pressure-side sealing member for sealing the positive pressure gap.

2. The rotary joint according to claim 1, wherein the negative pressure side sealing member is a contact type seal.

3. The rotary joint according to claim 2, wherein the contact seal is a lip seal.

4. The rotary joint according to claim 1, wherein the positive pressure side sealing member is a non-contact type seal.

5. The rotary joint according to claim 4, wherein the non-contact seal is a magnetic fluid seal.

6. The rotary joint according to claim 1, wherein the positive pressure side sealing member is positioned closer to the suction port than the negative pressure side sealing member.

7. The rotary joint according to claim 1, wherein the negative pressure side sealing member is positioned closer to the suction port than the positive pressure side sealing member.

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