Oil Supply Type Compressor

Patent metadata

Field	Value
Publication number	US-2016245289-A1
Application number	US-201415027836-A
Country	US
Kind code	A1
Filing date	Aug 5, 2014
Priority date	Oct 10, 2013
Publication date	Aug 25, 2016
Grant date	—

Abstract

The objective of the present invention is to reduce the pressure reduction time while preventing foaming in an oil separation device during capacity control of a compressor, and to avoid startup congestion and thus enable normal starting even when a portion provided in an air release pipe and having a small flow path cross-sectional area becomes clogged. This oil supply type compressor is equipped with a compressor main body, an oil separation device, and an air discharge passage for discharging compressed air during capacity control of the compressor. Furthermore, the air discharge passage is equipped with a passage having a large flow volume and a passage having a small flow volume, and when compressed air is discharged from the air discharge passage to the atmosphere during capacity control, the pressure in the oil separation device is discharged using the passage having a large flow volume, until the pressure reaches or falls below a restarting-possible pressure, which is the pressure at which startup congestion does not occur when the compressor main body is restarted. When the pressure in the oil separation device reaches a prescribed pressure, which is less than or equal to the restarting-possible pressure and is higher than a foaming pressure, which is the pressure at which foaming occurs when the pressure in the oil separation device is discharged quickly, the pressure is discharged using the passage having a small flow volume.

First claim

1 . An oil supply type compressor, comprising:
a compressor body compressing air; an oil separation device separating lubricating oil from the compressed air compressed by the compressor body; piping for supplying, to a user side, the compressed air after flowing through the oil separation device; and an air release path for releasing the compressed air after flowing through the oil separation device in capacity control for the compressor, wherein: the air release path includes a high flow-rate flow path and a low flow-rate flow path; in the capacity control for the compressor, when the compressed air in the oil separation device is released through the air release path into the atmosphere, the high flow-rate flow path is used for air release until a pressure in the oil separation device becomes equal to or less than a restarting-possible pressure at which startup stall is not caused when the compressor body is restarted; and the low flow-rate flow path is used for air release when a pressure in the oil separation device reaches a predetermined pressure which is equal to or less than the restarting-possible pressure and also exceeds a foaming pressure at which foaming occurs due to a fast reduction in pressure in the oil separation device.

2 . The oil supply type compressor according to claim 1 , wherein the low flow-rate flow path has a flow-passage cross-sectional area determined to cause a slope of pressure drop to be plotted to prevent foaming, and the high flow-rate flow path has a flow-passage cross-sectional area determined to be larger than the flow-passage cross-sectional area of the low flow-rate flow path.

3 . The oil supply type compressor according to claim 2 , further comprising:
an intake throttle valve adjusting the amount of intake air into the compressor body; a check valve installed in the piping for supplying to the user side the compressed air after passing through the oil separation device to prevent backflow of the compressed air from the user side; and an on/off valve installed in the air release path, wherein, when the compressed air in the oil separation device is released through the air release path into the atmosphere, the on/off valve is controlled to be open and also the intake throttle valve is controlled to be closed.

4 . The oil supply type compressor according to claim 3 , wherein a pressure sensor detecting a compressed air pressure on the user side is installed and the on/off valve installed in the air release path includes a solenoid valve, the solenoid valve being opened/closed in response to a pressure detected by the pressure sensor.

5 . The oil supply compressor according to claim 2 , wherein the low flow-rate flow path includes a path having a small-diameter orifice, and the high flow-rate flow path includes a path having a large-diameter orifice having a flow-passage cross-sectional area larger than that of the small-diameter orifice.

6 . The oil supply compressor according to claim 5 , wherein, when the compressed air in the oil separation device is released through the air release path into the atmosphere, the path having the large-diameter orifice and the path having the small-diameter orifice are both used to air-release until a pressure in the oil separation device becomes equal to or less than the restarting-possible pressure at which startup stall is not caused when the compressor body is restarted.

7 . The oil supply type compressor according to claim 4 , wherein: the oil separation device includes an oil tank achieving primary separation of the lubricating oil from the compressed air discharged from the compressed body and storing the lubricating oil thus separated, and an oil separator having a filtering element to achieve secondary separation of the lubricating oil from the compressed air flowing out of the oil tank; and the air release path is arranged to release the compressed air after passing through the oil separator.

8 . The oil supply type compressor according to claim 7 , wherein the air release path includes air release piping branching off from between the oil separator and the check valve;
the solenoid valve is placed in the air release piping; and a quick air release valve including a large-diameter orifice allowing for a flow at high flow rate and a small-diameter orifice allowing for a flow at low flow rate is installed downstream of the solenoid valve.

9 . The oil supply type compressor according to claim 8 , wherein the quick air release valve is configured to cause air-release from the large-diameter orifice at air-release initiation, and to close the large-diameter orifice to cause air-release from only the small-diameter orifice when an internal pressure of the oil separator reaches a pressure equal to or less than the restarting-possible pressure and also exceeding the foaming pressure.

10 . The oil supply type compressor according to claim 7 , wherein the oil tank and the oil separator are formed integrally.

11 . The oil supply type compressor according to claim 7 , wherein: the air release path includes air release piping branching off from between the oil separator and the check valve; the air release piping is connected to the intake throttle valve in the compressor body; and
the compressed air inside the oil separator is released into an area upstream of the intake throttle valve.

12 . An oil supply type compressor, comprising:
a compressor body compressing air; an oil separation device separating lubricating oil from the compressed air compressed by the compressor body; piping for supplying, to a user side, the compressed air after flowing through the oil separation device; and an air release path for releasing the compressed air after flowing through the oil separation device in capacity control for the compressor, wherein: the air release path has a flow-passage cross-sectional area determined to allow for a flow at high flow rate causing a slope of pressure drop at which foaming occurs due to a fast reduction in pressure in the oil separation device; and in the capacity control for the compressor, when the compressed air in the oil separation device is released through the air release path into the atmosphere, the air release path is closed when a pressure in the oil separation device reaches a predetermined pressure that is equal to or less than a restarting-possible pressure at which startup stall is not caused when the compressor body is restarted, and also that exceeds a foaming pressure at which foaming occurs due to a fast reduction in pressure in the oil separation device.

13 . The oil supply compressor according to claim 1 , wherein the compressor is a screw compressor.

Assignees

• Hitachi Industry Equipment Systems Co Ltd

Inventors

• Kado Tomoyuki
• Oshiro Ryusuke

Classifications

• F04C29/12

  Arrangements for admission or discharge of the working fluid, e.g. constructional features of the inlet or outlet · CPC title

• F04C18/16

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

• F04C29/026 Primary

  Lubricant separation · CPC title