Oil-free screw compressor

Patent metadata

Field	Value
Publication number	US-10954941-B2
Application number	US-201716087510-A
Country	US
Kind code	B2
Filing date	Mar 21, 2017
Priority date	Mar 25, 2016
Publication date	Mar 23, 2021
Grant date	Mar 23, 2021

Abstract

The oil-free screw compressor includes: a screw rotor including a screw and a shaft; a bearing; a first shaft seal device disposed between the screw and the bearing, the first shaft seal device including: a first seal and a first communication section; a second shaft seal device disposed between the first shaft seal device and the bearing, the second shaft seal device including: a second seal and a second communication section; and a first seal member including a seal between the first communication section and the second communication section. The casing includes an atmosphere communication section configured to communicate the first communication section and the second communication section with an atmosphere. A sectional area in the first communication section is larger than a sectional area between the seal of the first seal member and the shaft.

First claim

The invention claimed is:

1. An oil-free screw compressor comprising:
a screw rotor including a screw and a shaft;
a bearing supporting the shaft;
a first shaft seal device fitted on the shaft, the first shaft seal device disposed between the screw and the bearing, the first shaft seal device including:
a first seal opposite to the shaft, and
a first communication section configured to communicate between an inner peripheral face of the first shaft seal device on a bearing side and an outer peripheral face of the first shaft seal device on the bearing side;

a second shaft seal device fitted on the shaft, the second shaft seal device disposed between the first shaft seal device and the bearing, the second shaft seal device including:
a second seal opposite to the shaft, and
a second communication section configured to communicate between an inner peripheral face of the second shaft seal device on a screw side and an outer peripheral face of the second shaft seal device on the screw side;

a casing including a rotor chamber accommodating the screw, and a shaft accommodation space accommodating the shaft, the bearing, the first shaft seal device, and the second shaft seal device; and
a first seal member fitted on the shaft, the first seal member including an annular seal configured to be opposite to the shaft between the first communication section and the second communication section and separate the first communication section and the second communication section,
wherein the casing includes an atmosphere communication section connected to both of the first communication section and the second communication section on the inner peripheral face of the shaft accommodation space, the atmosphere communication section configured to communicate the first communication section and the second communication section with an atmosphere,
wherein a flow passage sectional area in the first communication section is larger than a flow passage sectional area between the annular seal of the first seal member and the shaft, and
wherein an angular position of the first communication section with respect to a rotation center of the shaft is different from an angular position of the second communication section, and
wherein the atmosphere communication section includes a connection space formed in a recess shape on the inner peripheral face of the shaft accommodation space so that the connection space is connected to both of the first communication section and the second communication section whose angular positions are different.

2. The oil-free screw compressor according to claim 1 , wherein the first communication section is provided in a higher position than the second communication section when the oil-free screw compressor is situated on a ground.

3. The oil-free screw compressor according to claim 1 , wherein the atmosphere communication section includes an external communication section communicating a lower portion of the connection space with the atmosphere outside the casing, and an oil collection section provided between the external communication section and the connection space.

4. The oil-free screw compressor according to claim 1 ,
wherein a connection space of the atmosphere communication section is sectioned into a first sectioning region and a second sectioning region with a partitioning wall,
wherein the first communication section communicates with the first sectioning region,
wherein the second communication section communicates with the second sectioning region, and
wherein each of the first sectioning region and the second sectioning region includes an external communication section configured to communicate with the atmosphere outside the casing.

5. The oil-free screw compressor according to claim 4 , wherein an external communication section corresponding to the second sectioning region is positioned at lower level than an external communication section corresponding to the first sectioning region when the oil-free screw compressor is situated on a ground.

6. The oil-free screw compressor according to claim 1 ,
wherein the second communication section includes a plurality of second communication sections, and
wherein angular positions of the respective plurality of second communication sections with respect to a rotation center of the shaft are different.

7. The oil-free screw compressor according to claim 1 , wherein the first shaft seal device and the second shaft seal device engage with each other so as to partially overlap with each other when seen in a diameter direction of the screw rotor.

8. The oil-free screw compressor according to claim 1 , wherein the first seal member is a seal ring forming a floating-type seal and is provided displaceably in a diameter direction of the shaft.

9. The oil-free screw compressor according to claim 8 , further comprising a second seal member fitted on the shaft, the second seal member including an annular seal opposed to the shaft between the first seal of the first shaft seal device and the rotor chamber.

10. The oil-free screw compressor according to claim 9 , wherein the second seal member is a seal ring forming a floating-type seal and is provided displaceably in a diameter direction of the shaft.

11. The oil-free screw compressor according to claim 1 , wherein the first seal member overlaps at least one of the first shaft seal device and the second shaft seal device at least partially when seen in a diameter direction of the screw rotor.

Assignees

• Kobe Steel Ltd

Inventors

• Miyatake Toshiyuki

Classifications

• F04C18/16 Primary

  with helical teeth, e.g. chevron-shaped, screw type {(for non-parallel axes of movement F04C18/48)} · CPC title

• F04C27/00

  Sealing arrangements in rotary-piston pumps specially adapted for elastic fluids · CPC title

• F16J15/34

  with slip-ring pressed against a more or less radial face on one member · CPC title

• F01C19/005

  Structure and composition of sealing elements such as sealing strips, sealing rings and the like; Coating of these elements (vane construction F01C21/0809; piston rings and ring sealings of similar construction in general F16J9/00) · CPC title

• F04C2240/601

  Shaft flexion · CPC title