# US 2014/0193283 A1 · Gas exhaust pump system and gas exhaust method

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 2014/0193283 A1
- Document ID: US20140193283A1
- Status: Published application
- Kind: A1
- Application number: 14/235,860
- Filed: 2012-06-27
- Published: 2014-07-10
- Earliest claimed: 2011-08-02
- Assignees: Tohoku University
- Inventors: Kenji Ohyama; Isao Akutsu; Masamichi Iwaki; Tadahiro Ohmi
- Web page: https://patentgrep.com/patent/US20140193283A1

## CPC

- F04C 18/12: of other than internal-axis type
- F04C 18/16: with helical teeth, e.g. chevron-shaped, screw type {(for non-parallel axes of movement F04C18/48)}
- F04C 25/02: for producing high vacuum (sealing arrangements F04C27/00; silencing F04C29/06)
- F04C 27/009: {Shaft sealings specially adapted for pumps}
- F04C 29/0007: {Injection of a fluid in the working chamber for sealing, cooling and lubricating (sealing only F04C27/00; lubrication only F04C29/02; cooling F02B47/02, F02D21/00, F02M25/00)}
- F04C 29/023: {Lubricant distribution through a hollow driving shaft (F04C29/025 takes precedence)}
- F04C 2220/30: Use in a chemical vapor deposition [CVD] process or in a similar process
- F04C 2230/91: Coating
- F04C: ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS (engines F03C); ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS

## Abstract

There is provided a gas exhaust pump system capable of suppressing the inclusion of a seal gas into a process gas. The gas exhaust pump system has a main and sub pumps. The main pump has a screw rotor, a rotating shaft, a holding unit, a lubricating oil supply path, a seal housing for covering a periphery of a non-held portion by the holding unit with a predetermined gap formed with an outer periphery of the rotating shaft, a seal member interposed between the rotating shaft and the seal housing, a seal gas supply path for supplying a seal gas to the gap, and a seal gas exhaust path for exhausting the seal gas from the gap to the outside of the main pump. The sub pump is configured to reduce a pressure in the seal gas exhaust path.

## Claims

### Claim 1

A gas exhaust pump system having a main pump and a sub pump, the main pump comprising:
a screw rotor;
a rotating shaft fixed to the screw rotor or formed integrally with the screw rotor and rotatably engaging with a rotation driving unit so as to rotate the screw rotor;
a holding unit configured to rotatably hold the rotating shaft;
a lubricating oil supply path having an oil ejection port for supplying a lubricating oil to the holding unit at one end;
a seal housing configured to cover a periphery of a portion that is not held by the holding unit of the rotating shaft, with a predetermined gap formed with an outer periphery of the rotating shaft;
a seal member interposed between the rotating shaft and the seal housing all around the rotating shaft, for suppressing entry of the lubricating oil supplied to the holding unit into an exhaust system space in the main pump through the gap;
a seal gas supply path having a supply port for supplying a seal gas to the gap; and
a seal gas exhaust path having a seal gas suction port for exhausting the seal gas supplied to the gap from the gap to the outside of the main pump, wherein
the sub pump is configured to reduce a pressure in the seal gas exhaust path, and
at least one of the outer periphery of the rotating shaft and an inner periphery of the seal housing is provided with a film of perfluoro alkoxy alkane of the formula:
where Rf is a perfluoro alkyl group and m and n are both positive integers.

### Claim 2

(canceled)

### Claim 3

A gas exhaust pump system having a main pump and a sub pump, the main pump comprising:
a rotor;
a rotating shaft fixed to the rotor or formed integrally with the rotor and rotatably engaging with a rotation driving unit so as to rotate the rotor;
a holding unit configured to rotatably hold the rotating shaft;
a lubricating oil supply path having an oil ejection port for supplying a lubricating oil to the holding unit at one end;
a seal housing configured to cover a periphery of a portion that is not held by the holding unit of the rotating shaft, with a predetermined gap formed with an outer periphery of the rotating shaft;
a seal member interposed between the rotating shaft and the seal housing all around the rotating shaft, for suppressing entry of the lubricating oil supplied to the holding unit into an exhaust system space in the main pump through the gap;
a seal gas supply path having a supply port for supplying a seal gas to the gap; and
a seal gas exhaust path having a seal gas suction port for exhausting the seal gas supplied to the gap from the gap to the outside of the main pump, wherein
the sub pump is configured to reduce a pressure in the seal gas exhaust path, and
at least one of the outer periphery of the rotating shaft and an inner periphery of the seal housing is provided with a film of perfluoro alkoxy alkane of the formula:
where Rf is a perfluoro alkyl group and m and n are both positive integers.

### Claim 4

(canceled)

### Claim 5

A gas exhaust method using a gas exhaust pump system having a main pump and a sub pump, the main pump being in connection relation with a process chamber so as to reduce a pressure in the process chamber to a pressure equal to or less than atmospheric pressure and comprising:
a screw rotor;
a rotating shaft fixed to the screw rotor or formed integrally with the screw rotor and rotatably engaging with a rotation driving unit so as to rotate the screw rotor;
a holding unit configured to rotatably hold the rotating shaft;
a lubricating oil supply path having an oil ejection port for supplying a lubricating oil to the holding unit at one end;
a seal housing configured to cover a periphery of a portion that is not held by the holding unit of the rotating shaft, with a predetermined gap formed with an outer periphery of the rotating shaft;
a seal member interposed between the rotating shaft and the seal housing all around the rotating shaft, for suppressing entry of the lubricating oil supplied to the holding unit into an exhaust system space in the main pump through the gap;
a seal gas supply path having a supply port for supplying a seal gas to the gap, upstream from the seal member; and
a seal gas exhaust path having a seal gas suction port for exhausting the seal gas supplied to the gap from the gap to the outside of the main pump, downstream from the seal member, wherein
the sub pump is in connection relation with the seal gas exhaust path so as to reduce a pressure in the seal gas exhaust path,
at least one of the outer periphery of the rotating shaft and an inner periphery of the seal housing is provided with a film of perfluoro alkoxy alkane of the formula:
where Rf is a perfluoro alkyl group and m and n are both positive integers, and
the gas exhaust method comprises associating an exhaust operation of the main pump with a pressure reducing operation of the sub pump in operating the gas exhaust pump system.

### Claim 6

(canceled)