U.S. patent application number 16/495866 was filed with the patent office on 2020-04-02 for liquid-feed-type gas compressor.
The applicant listed for this patent is Hitachi Industrial Equipment Systems Co., Ltd.. Invention is credited to Kenji MORITA, Masahiko TAKANO, Shigeyuki YORIKANE.
Application Number | 20200102950 16/495866 |
Document ID | / |
Family ID | 1000004539998 |
Filed Date | 2020-04-02 |
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United States Patent
Application |
20200102950 |
Kind Code |
A1 |
MORITA; Kenji ; et
al. |
April 2, 2020 |
Liquid-Feed-Type Gas Compressor
Abstract
A liquid-feed-type gas compressor that can monitor the liquid
surface height in a gas-liquid separator is provided. An
oil-feed-type air compressor includes: an oil separator that
separates oil from compressed air discharged from a compressor main
body 1 and stores the oil therein; a sampling line whose inlet side
is connected to a predetermined height position of the oil
separator and that allows fluid from the predetermined height
position of the oil separator to flow by the pressure difference
between the inlet side and the outlet side; a pressure sensor that
detects the pressure of the fluid that flows or has flown in the
sampling line; a controller that determines which of air and oil
the fluid that flows in the sampling line is by carrying out
determination of whether the pressure detected by the pressure
sensor exceeds a set value P1 in some cases and determination of
whether the pressure falls below a set value P2 in some cases; and
an informing device that informs a determination result of the
controller.
Inventors: |
MORITA; Kenji; (Tokyo,
JP) ; TAKANO; Masahiko; (Tokyo, JP) ;
YORIKANE; Shigeyuki; (Tokyo, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Hitachi Industrial Equipment Systems Co., Ltd. |
Chiyoda- ku, Tokyo |
|
JP |
|
|
Family ID: |
1000004539998 |
Appl. No.: |
16/495866 |
Filed: |
March 27, 2018 |
PCT Filed: |
March 27, 2018 |
PCT NO: |
PCT/JP2018/012412 |
371 Date: |
September 20, 2019 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F04B 39/02 20130101;
F04B 51/00 20130101 |
International
Class: |
F04B 51/00 20060101
F04B051/00; F04B 39/02 20060101 F04B039/02 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 29, 2017 |
JP |
PCT/JP2017/013105 |
Claims
1. A liquid-feed-type gas compressor including a compressor main
body that compresses a gas while injecting a liquid into a
compression chamber, a gas-liquid separator that separates the
liquid from a compressed gas discharged from the compressor main
body and stores the liquid therein, and a liquid feed system that
feeds the liquid stored in the gas-liquid separator to the
compressor main body, wherein the liquid-feed-type gas compressor
comprises: a sampling line whose inlet side is connected to a
predetermined height position of the gas-liquid separator and that
allows fluid from the predetermined height position of the
gas-liquid separator to flow by pressure difference between the
inlet side and an outlet side; a detector that detects pressure or
temperature of the fluid that flows in the sampling line; a
controller that determines which of the gas and the liquid the
fluid that flows in the sampling line is by carrying out at least
one of determination of whether the pressure or the temperature
detected by the detector exceeds a first set value set in advance
in some cases and determination of whether the pressure or the
temperature detected by the detector falls below a second set value
set to be smaller than the first set value in advance in some
cases; and an informing device that informs a determination result
of the controller.
2. The liquid-feed-type gas compressor according to claim 1,
wherein the controller determines which of the gas and the liquid
the fluid that flows in the sampling line is by carrying out both
the determination of whether the pressure or the temperature
detected by the detector exceeds the first set value set in advance
in some cases and the determination of whether the pressure or the
temperature detected by the detector falls below the second set
value set to be smaller than the first set value in advance in some
cases.
3. The liquid-feed-type gas compressor according to claim 1,
wherein the liquid-feed-type gas compressor includes at least one
of a suction throttle valve that closes an intake side of the
compressor main body and a relief valve that releases the gas on a
discharge side of the compressor main body in order to carry out
switching of the compressor main body from load operation to
no-load operation, and at time of the load operation of the
compressor main body, the controller determines which of the gas
and the liquid the fluid that flows in the sampling line is by
carrying out at least one of the determination of whether the
pressure or the temperature detected by the detector exceeds the
first set value set in advance in some cases and the determination
of whether the pressure or the temperature detected by the detector
falls below the second set value set to be smaller than the first
set value in advance in some cases.
4. The liquid-feed-type gas compressor according to claim 1,
wherein the outlet side of the sampling line is connected to the
liquid feed system.
5. The liquid-feed-type gas compressor according to claim 1,
wherein the compressor main body, the gas-liquid separator, and the
liquid feed system configure a compressor unit disposed on a same
base, and the informing device includes a display that is mounted
on the compressor unit and displays information based on the
determination result of the controller.
6. The liquid-feed-type gas compressor according to claim 1,
wherein the compressor main body, the gas-liquid separator, and the
liquid feed system configure a compressor unit disposed on a same
base, and the informing device includes a communication terminal
that is separated from the compressor unit and displays information
based on the determination result of the controller, the
determination result being received through a communication
channel.
7. A liquid-feed-type gas compressor including a compressor main
body that compresses a gas while injecting a liquid into a
compression chamber, a gas-liquid separator that separates the
liquid from a compressed gas discharged from the compressor main
body and stores the liquid therein, and a liquid feed system that
feeds the liquid stored in the gas-liquid separator to the
compressor main body, wherein the liquid-feed-type gas compressor
comprises: a sampling line whose inlet side is connected to a
predetermined height position of the gas-liquid separator and that
allows fluid from the predetermined height position of the
gas-liquid separator to flow by pressure difference between the
inlet side and an outlet side; a detector that detects pressure or
temperature of the fluid that flows on a system on a downstream
side connected to the outlet side of the sampling line on the
liquid feed system; a controller that determines which of the gas
and the liquid the fluid that flows in the sampling line is by
carrying out at least one of determination of whether the pressure
or the temperature detected by the detector exceeds a first set
value set in advance in some cases and determination of whether the
pressure or the temperature detected by the detector falls below a
second set value set to be smaller than the first set value in
advance in some cases; and an informing device that informs a
determination result of the controller.
8. The liquid-feed-type gas compressor according to claim 7,
wherein the controller determines which of the gas and the liquid
the fluid that flows in the sampling line is by carrying out both
the determination of whether the pressure or the temperature
detected by the detector exceeds the first set value set in advance
in some cases and the determination of whether the pressure or the
temperature detected by the detector falls below the second set
value set to be smaller than the first set value in advance in some
cases.
9. The liquid-feed-type gas compressor according to claim 7,
wherein the liquid-feed-type gas compressor includes at least one
of a suction throttle valve that closes an intake side of the
compressor main body and a relief valve that releases the gas on a
discharge side of the compressor main body in order to carry out
switching of the compressor main body from load operation to
no-load operation, and at time of the load operation of the
compressor main body, the controller determines which of the gas
and the liquid the fluid that flows in the sampling line is by
carrying out at least one of the determination of whether the
pressure or the temperature detected by the detector exceeds the
first set value set in advance in some cases and the determination
of whether the pressure or the temperature detected by the detector
falls below the second set value set to be smaller than the first
set value in advance in some cases.
10. The liquid-feed-type gas compressor according to claim 7,
wherein the outlet side of the sampling line is connected to the
liquid feed system.
11. The liquid-feed-type gas compressor according to claim 7,
wherein the compressor main body, the gas-liquid separator, and the
liquid feed system configure a compressor unit disposed on a same
base, and the informing device includes a display that is mounted
on the compressor unit and displays information based on the
determination result of the controller.
12. The liquid-feed-type gas compressor according to claim 7,
wherein the compressor main body, the gas-liquid separator, and the
liquid feed system configure a compressor unit disposed on a same
base, and the informing device includes a communication terminal
that is separated from the compressor unit and informs information
based on the determination result of the controller, the
determination result being received through a communication
channel.
13. A liquid-feed-type gas compressor including a compressor main
body that compresses a gas while injecting a liquid into a
compression chamber, a gas-liquid separator that separates the
liquid from the compressed gas discharged from the compressor main
body and stores the liquid therein, and a liquid feed system that
feeds the liquid stored in the gas-liquid separator to the
compressor main body, wherein the liquid-feed-type gas compressor
comprises: a sampling line whose inlet side is connected to a
predetermined height position of the gas-liquid separator and that
allows fluid from the predetermined height position of the
gas-liquid separator to flow by pressure difference between the
inlet side and an outlet side; a detector that detects pressure or
temperature of the fluid that flows in the sampling line or has
flown in the sampling line; a controller that determines which of
the gas and the liquid the fluid that flows in the sampling line is
by carrying out at least one of determination of whether frequency
at which the pressure or the temperature detected by the detector
exceeds a first set value set in advance is higher than a
predetermined value and determination of whether frequency at which
the pressure or the temperature detected by the detector falls
below a second set value set to be smaller than the first set value
in advance is higher than a predetermined value; and an informing
device that informs a determination result of the controller.
14. A liquid-feed-type gas compressor including a compressor main
body that compresses a gas while injecting a liquid into a
compression chamber, a gas-liquid separator that separates the
liquid from the compressed gas discharged from the compressor main
body and stores the liquid therein, and a liquid feed system that
feeds the liquid stored in the gas-liquid separator to the
compressor main body, wherein the liquid-feed-type gas compressor
comprises: a sampling line whose inlet side is connected to a
predetermined height position of the gas-liquid separator and that
allows fluid from the predetermined height position of the
gas-liquid separator to flow by pressure difference between the
inlet side and an outlet side; a detector that detects pressure or
temperature of the fluid that flows in the sampling line or has
flown in the sampling line; a controller that determines which of
the gas and the liquid the fluid that flows in the sampling line is
by calculating a change rate in the pressure or the temperature
detected by the detector and carrying out at least one of
determination of whether the change rate exceeds a positive set
value set in advance in some cases and determination of whether the
change rate falls below a negative set value set in advance in some
cases; and an informing device that informs a determination result
of the controller.
Description
TECHNICAL FIELD
[0001] The present invention relates to a liquid-feed-type gas
compressor including a gas-liquid separator and particularly
relates to a liquid-feed-type gas compressor suitable to monitor
the liquid surface height in a gas-liquid separator.
BACKGROUND ART
[0002] An oil-feed-type air compressor that is one of
liquid-feed-type gas compressors and includes a compressor main
body, an oil separator, and an oil feed system (for example refer
to Patent Document 1). The compressor main body compresses air
(gas) while injecting oil (liquid) into compression chambers for
the purpose of cooling of heat of compression, lubrication of
compression members such as rotors and laps, seal of the
compression chambers, and so forth. The oil separator (gas-liquid
separator) separates the oil from the compressed air (compressed
gas) discharged from the compressor main body and stores the oil
therein. The oil feed system (liquid feed system) feeds the oil
stored in the oil separator to the compressor main body.
PRIOR ART DOCUMENT
Patent Document
[0003] Patent Document 1: JP-2009-85045-A
SUMMARY OF THE INVENTION
Problem to be Solved by the Invention
[0004] In the above-described oil-feed-type air compressor, the
compression performance and so forth lower when the amount of
stored oil in the oil separator becomes deficient, i.e. when the
amount of oil fed to the compressor main body becomes deficient.
For this reason, the oil surface height in the oil separator needs
to be monitored.
[0005] So, if the difference between the pressure of air and the
pressure of oil in the oil separator is large, a method in which a
detector that detects the pressure is set at a predetermined height
position in the oil separator is conceivable. Specifically, in this
method, by setting a threshold that is the middle of the pressure
of air and the pressure of oil in the oil separator in advance, for
example, and determining whether the pressure detected by the
detector exceeds the threshold, it is determined which of air and
oil the fluid existing at the predetermined height position in the
oil separator is. Thereby, whether the oil surface in the oil
separator is lower than the predetermined height position is
detected.
[0006] Alternatively, if the difference between the temperature of
air and the temperature of oil in the oil separator is large, a
method in which a detector that detects the temperature is set at a
predetermined height position in the oil separator is conceivable.
Specifically, in this method, by setting a threshold that is the
middle of the temperature of air and the temperature of oil in the
oil separator in advance, for example, and determining whether the
temperature detected by the detector exceeds the threshold, it is
determined which of air and oil the fluid existing at the
predetermined height position in the oil separator is. Thereby,
whether the oil surface in the oil separator is lower than the
predetermined height position is detected.
[0007] However, actually the difference between the pressure of air
and the pressure of oil in the oil separator hardly exists and the
difference between the temperature of air and the temperature of
oil also hardly exists. For this reason, the detection value of the
detector does not vary whether or not the oil surface height in the
oil separator varies. Therefore, the above-described method cannot
be employed.
[0008] As further another method, it is conceivable that a detector
of an optical system that detects whether or not oil exits is set
at a predetermined height position in the oil separator. However,
oil separated from compressed air flows down in the oil separator.
Furthermore, the oil surface in the oil separator often undulates.
For this reason, even when the oil surface in the oil separator is
lower than the predetermined height position, the oil continuously
passes through the detector or adheres thereto, which possibly
leads to erroneous detection of the detector. Therefore, this
method cannot be employed.
[0009] The present invention is made in view of the above-described
matter and one of problems thereof is monitoring the liquid surface
height in a gas-liquid separator.
Means for Solving the Problem
[0010] In order to solve the above-described problem,
configurations described in the scope of claims are applied. The
present invention includes plural means for solving the
above-described problem. To cite one example thereof, a
liquid-feed-type gas compressor includes a compressor main body
that compresses a gas while injecting a liquid into a compression
chamber, a gas-liquid separator that separates the liquid from a
compressed gas discharged from the compressor main body and stores
the liquid therein, a liquid feed system that feeds the liquid
stored in the gas-liquid separator to the compressor main body, a
sampling line whose inlet side is connected to a predetermined
height position of the gas-liquid separator and that allows fluid
from the predetermined height position of the gas-liquid separator
to flow by pressure difference between the inlet side and an outlet
side, a detector that detects pressure or temperature of the fluid
that flows in the sampling line, a controller that determines which
of the gas and the liquid the fluid that flows in the sampling line
is by carrying out at least one of determination of whether the
pressure or the temperature detected by the detector exceeds a
first set value set in advance in some cases and determination of
whether the pressure or the temperature detected by the detector
falls below a second set value set to be smaller than the first set
value in advance in some cases, and an informing device that
informs a determination result of the controller.
[0011] Furthermore, to cite another example, a liquid-feed-type gas
compressor includes a compressor main body that compresses a gas
while injecting a liquid into a compression chamber, a gas-liquid
separator that separates the liquid from a compressed gas
discharged from the compressor main body and stores the liquid
therein, a liquid feed system that feeds the liquid stored in the
gas-liquid separator to the compressor main body, a sampling line
whose inlet side is connected to a predetermined height position of
the gas-liquid separator and that allows fluid from the
predetermined height position of the gas-liquid separator to flow
by pressure difference between the inlet side and an outlet side, a
detector that detects the pressure or the temperature of the fluid
that flows on a system on a downstream side connected to the outlet
side of the sampling line on the liquid feed system, a controller
that determines which of the gas and the liquid the fluid that
flows in the sampling line is by carrying out at least one of
determination of whether the pressure or the temperature detected
by the detector exceeds a first set value set in advance in some
cases and determination of whether the pressure or the temperature
detected by the detector falls below a second set value set to be
smaller than the first set value in advance in some cases, and an
informing device that informs a determination result of the
controller.
Advantages of the Invention
[0012] The present invention is based on knowledge that pulsation
(in other words, large change in which increase and decrease are
cyclically repeated) hardly occurs in the pressure or the
temperature of a liquid when the liquid is caused to flow in the
sampling line whereas pulsation occurs in the pressure or the
temperature of a gas when the gas is caused to flow in the sampling
line, and it can be determined which of the gas and the liquid the
fluid that flows in the sampling line is. Due to this, the liquid
surface height in the gas-liquid separator can be monitored.
[0013] Problems, configurations, and effects other than the above
description will be made apparent by the following description.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1 is a schematic diagram that represents the
configuration of an oil-feed-type air compressor in a first
embodiment of the present invention and shows the state in which
the amount of stored oil in an oil separator is sufficient.
[0015] FIG. 2 is a diagram showing the state in which the amount of
stored oil in the oil separator is insufficient in the first
embodiment of the present invention.
[0016] FIG. 3 is a diagram that represents change in the detection
value of a pressure sensor over time in the first embodiment of the
present invention and shows the case in which oil flows in a
sampling line.
[0017] FIG. 4 is a diagram that represents change in the detection
value of the pressure sensor over time in the first embodiment of
the present invention and shows the case in which air flows in the
sampling line.
[0018] FIG. 5 is a schematic diagram that represents the
configuration of an oil-feed-type air compressor in a second
embodiment of the present invention and shows the state in which
the amount of stored oil in the oil separator is sufficient.
[0019] FIG. 6 is a schematic diagram that represents the
configuration of an oil-feed-type air compressor in a third
embodiment of the present invention and shows the state in which
the amount of stored oil in the oil separator is sufficient.
[0020] FIG. 7 is a diagram showing the state in which the amount of
stored oil in the oil separator is insufficient in the third
embodiment of the present invention.
[0021] FIG. 8 is a diagram that represents change in the detection
value of a temperature sensor over time in the third embodiment of
the present invention and shows the case in which oil flows in the
sampling line.
[0022] FIG. 9 is a diagram that represents change in the detection
value of the temperature sensor over time in the third embodiment
of the present invention and shows the case in which air flows in
the sampling line.
[0023] FIG. 10 is a schematic diagram that represents a
communication terminal in a modification example of the present
invention.
MODES FOR CARRYING OUT THE INVENTION
[0024] A first embodiment of the present invention will be
described with reference to the drawings by taking as an example an
oil-feed-type air compressor as an application target of the
present invention.
[0025] FIG. 1 is a schematic diagram that represents the
configuration of the oil-feed-type air compressor in the present
embodiment and shows the state in which the amount of stored oil in
an oil separator is sufficient. FIG. 2 is a diagram showing the
state in which the amount of stored oil in the oil separator is
insufficient in the present embodiment.
[0026] The oil-feed-type air compressor of the present embodiment
includes a compressor main body 1, an intake system 2 connected to
the intake side of the compressor main body 1, an oil separator 4
(gas-liquid separator) connected to the discharge side of the
compressor main body 1 through a discharge line 3, a compressed air
feed system 5 (compressed gas feed system) connected to the upper
part of the oil separator 4, an oil feed system 6 (liquid feed
system) connected between the lower part of the oil separator 4 and
the compressor main body 1, a controller 7, and a display 8. These
compressor main body 1, intake system 2, discharge line 3, oil
separator 4, compressed air feed system 5, oil feed system 6,
controller 7, and display 8 are disposed on the same pedestal
(base, pallet, or air tank in the case of a tank-mounted type, or
the like) to configure a compressor unit 9. In particular, in the
present embodiment, the compressor unit 9 is configured with a
housing composed of panel plates which surround the circumferential
surface and the upper surface of the unit.
[0027] Although details are not shown in the diagram, the
compressor main body 1 has a pair of male and female screw rotors
that mesh with each other and a casing that houses them, and plural
compression chambers are formed in the tooth spaces of the screw
rotors. When the screw rotors rotate, the compression chambers move
in the axial direction of the rotors. The compression chambers take
in air (gas) from the intake system 2 and compress the air to
discharge the compressed air (compressed gas) to the discharge line
3. The compressor main body 1 injects oil (liquid) into the
compression chambers at any stage in the compression process,
typified by a stage immediately after start of compression, for
example, for the purpose of cooling of heat of compression,
lubrication of the rotors, seal of the compression chambers, and so
forth.
[0028] The intake system 2 has a suction filter 10 that removes
impurities in air and a suction throttle valve 11 that is set on
the downstream side of the suction filter 10 and can close the
intake side of the compressor main body 1.
[0029] The oil separator 4 separates oil from the compressed air
discharged from the compressor main body 1 by using specific
gravity separation and impingement separation, for example, and
stores the separated oil at the lower part. The compressed air
separated by the oil separator 4 is fed to a use destination
outside the unit through the compressed air feed system 5. The
compressed air feed system 5 has a pressure regulating valve (check
valve) 12, an after-cooler 13 that is disposed on the downstream
side of the pressure regulating valve 12 and cools the compressed
air, and a control pressure sensor 14 that is disposed on the
downstream side of the pressure regulating valve 12 and detects the
pressure of the compressed air (i.e. pressure that varies depending
on the amount of use of the compressed air). The control pressure
sensor 14 outputs the detected pressure to the controller 7.
[0030] The oil stored in the oil separator 4 is fed to the
compression chambers through the oil feed system 6 by the pressure
difference between the oil separator 4 and the compression chambers
of the compressor main body 1. The oil feed system 6 has an oil
cooler 15 that cools the oil, a bypass line 16 that bypasses the
oil cooler 15, a temperature regulating valve (three-way valve) 17
set at the inlet (branch point) of the bypass line 16, and an oil
filter 18 that is disposed on the downstream side relative to the
outlet (merging point) of the bypass line 16 and removes impurities
in the oil. The temperature regulating valve 17 detects the
temperature of the oil and regulates the ratio between the flow
rate on the side of the oil cooler 15 and the flow rate on the side
of the bypass line 16 according to the temperature of the oil.
Thereby, the temperature of the oil fed to the compressor main body
1 is regulated.
[0031] The controller 7 has an calculation control section (for
example, CPU) that executes calculation processing and control
processing by cooperation with a program, a storing section (for
example, ROM and RAM) that stores the program and the result of the
calculation processing, and so forth. As an operation control
function, the controller 7 controls the opened/closed state of the
suction throttle valve 11 according to the pressure detected by the
control pressure sensor 14 and switches the operation state of the
compressor main body 1 based on this. It is also possible for all
or part of the controller 7 to have an analog circuit
configuration.
[0032] Specifically, at the time of load operation of the
compressor main body 1 (in other words, when the suction throttle
valve 11 is in the opened state), the controller 7 determines
whether the pressure detected by the control pressure sensor 14 has
risen to become an unloading start pressure Pu set in advance.
Then, if the pressure detected by the control pressure sensor 14
becomes the unloading start pressure Pu, the controller 7 controls
the suction throttle valve 11 to the closed state to cause
switching to no-load operation of the compressor main body 1.
[0033] At the time of no-load operation of the compressor main body
1 (in other words, when the suction throttle valve 11 is in the
closed state), the controller 7 determines whether the pressure
detected by the control pressure sensor 14 has fallen to become a
load return pressure Pd (where Pd<Pu) set in advance. Then, if
the pressure detected by the control pressure sensor 14 becomes the
load return pressure Pd, the controller 7 controls the suction
throttle valve 11 to the opened state to cause switching to load
operation of the compressor main body 1. By the above operation
switching, reduction in the power consumption can be intended when
the amount of use of the compressed air decreases.
[0034] Here, as one of characteristics of the present embodiment,
the oil-feed-type air compressor includes a sampling line 19 whose
inlet side is connected to a predetermined height position H of the
oil separator 4 (specifically, for example, height position of the
oil surface corresponding to the desired amount of stored oil when
the compressor is driven) and whose outlet side is connected to the
upstream side of the oil filter 18 of the oil feed system 6, and a
pressure sensor 20 (detector) that detects the pressure of fluid
that flows in the sampling line 19. In the present embodiment
example, the sectional area of the sampling line 19 is smaller than
that of the line of the oil feed system 6, for example, so that the
flow rate may become lower than that of the oil feed system 6.
However, the sampling line 19 is not limited thereto. The pressure
sensor 20 outputs the detected pressure to the controller 7.
[0035] As an oil surface height detection function, at the time of
load operation of the compressor main body 1 (in other words, when
the oil surface in the oil separator 4 is lower than that at the
time of no-load operation of the compressor main body 1), the
controller 7 determines which of air and oil the fluid that flows
in the sampling line 19 is (or which of them mainly exists) by
carrying out determination of whether the pressure detected by the
pressure sensor 20 gets out of a set range set in advance in some
cases (in other words, determination of whether the pressure
exceeds a set value P1 set in advance in some cases and
determination of whether the pressure falls below a set value P2
(where P2<P1) set in advance in some cases), and outputs the
determination result to the display 8. The display 8 informs the
determination result of the controller 7.
[0036] Specifically, as shown in FIG. 1, if the oil surface in the
oil separator 4 is higher than the predetermined height position H
(in other words, position to which the inlet side of the sampling
line 19 is connected), oil flows in the sampling line 19. In this
case, as shown in FIG. 3, the pressure of oil detected by the
pressure sensor 20 does not involve the occurrence of pulsation and
falls within the set range (in other words, equal to or lower than
the set value P1 and equal to or higher than the set value P2).
Thus, the controller 7 determines that the fluid that flows in the
sampling line 19 is oil. Due to this, it can be detected that the
oil surface in the oil separator 4 is higher than the predetermined
height position H.
[0037] On the other hand, as shown in FIG. 2, if the oil surface in
the oil separator 4 is lower than the predetermined height position
H, air flows in the sampling line 19. In this case, as shown in
FIG. 4, the pressure of air detected by the pressure sensor 20
involves the occurrence of pulsation and gets out of the set range
(in other words, exceeds the set value P1 or falls below the set
value P2) in some cases. Thus, the controller 7 determines that the
fluid that flows in the sampling line 19 is air. Due to this, it
can be detected that the oil surface in the oil separator 4 is
lower than the predetermined height position H.
[0038] If the determination result that the fluid that flows in the
sampling line 19 is air is input to the display 8, the display 8
displays a message of "warning: lubricating oil is insufficient" or
"warning: please replenish lubricating oil," or the like, as
notification information based on the determination result.
Furthermore, the determination result that the fluid that flows in
the sampling line 19 is oil may be input to the display 8 and the
display 8 may display a message of "lubricating oil is sufficient"
or the like as information based on the determination result. These
informing methods may be various forms such as sound, vibration, or
combination of them.
[0039] As above, the present embodiment is based on knowledge that
pulsation hardly occurs in the pressure of oil when the oil
(liquid) flows in the sampling line 19 whereas pulsation occurs in
the pressure of air when the air (gas) flows in the sampling line
19, and it can be determined which of oil and air the fluid that
flows in the sampling line 19 is (or which of them mainly exists).
Due to this, the oil surface height in the oil separator 4 can be
accurately monitored.
[0040] In the first embodiment, the description is made by taking
as an example the case in which the controller 7 determines which
of air and oil the fluid that flows in the sampling line 19 is (or
which of them mainly exists) by carrying out determination of
whether the pressure detected by the pressure sensor 20 gets out of
the set range in some cases (in other words, both determination of
whether the pressure detected by the pressure sensor 20 exceeds the
set value P1 in some cases and determination of whether the
pressure falls below the set value P2 in some cases). However, the
present invention is not limited thereto and modifications are
possible in such a range as not to depart from the gist and
technical idea of the present invention.
[0041] As a first modification example, the controller 7 may
determine which of air and oil the fluid that flows in the sampling
line 19 is (or which of them mainly exists) by carrying out either
one of determination of whether the pressure detected by the
pressure sensor 20 exceeds the set value P1 in some cases and
determination of whether the pressure falls below the set value P2
in some cases. Also in such a modification example, the same
effects as the above description can be obtained.
[0042] As a second modification example, the controller 7 may
determine which of air and oil the fluid that flows in the sampling
line 19 is (or which of them mainly exists) by carrying out one or
both of determination of whether the frequency at which the
pressure detected by the pressure sensor 20 exceeds the set value
P1 is higher than a predetermined value and determination of
whether the frequency at which the pressure detected by the
pressure sensor 20 falls below the set value P2 is higher than a
predetermined value. Also in such a modification example, the same
effects as the above description can be obtained.
[0043] As a third modification example, the controller 7 may
determine which of air and oil the fluid that flows in the sampling
line 19 is (or which of them mainly exists) by calculating a change
rate in the pressure detected by the pressure sensor 20
(specifically, for example, change rate of the pressure obtained at
every interval of the detection time of the pressure sensor 20) and
carrying out one or both of determination of whether this change
rate exceeds a positive set value set in advance in some cases and
determination of whether the change rate falls below a negative set
value set in advance in some cases. Also in such a modification
example, the same effects as the above description can be
obtained.
[0044] A second embodiment of the present invention will be
described with reference to the drawings. In the present
embodiment, the same part as the first embodiment is given the same
character and description thereof is omitted as appropriate.
[0045] FIG. 5 is a schematic diagram that represents the
configuration of an oil-feed-type compressor in the present
embodiment. Main differences from the first embodiment in terms of
the configuration are that a sampling line 19A in the second
embodiment has a configuration in which the outlet side thereof is
connected to the upstream side relative to the temperature
regulating valve 17 on the oil feed system 6 and that the pressure
sensor 20 is disposed on the downstream side relative to the outlet
of the sampling line 19A (in the present embodiment, on the
downstream side relative to the outlet of the bypass line 16) on
the oil feed system 6. In other words, one of characteristics of
the second embodiment is that not pressure pulsation of the
sampling line 19A but pressure pulsation that occurs in the oil
feed system 6 due to the sampling line 19A is detected.
[0046] Specifically, for example, when the compressor is in load
operation, if the oil surface position in the oil separator 4
becomes lower than the position of the inlet side of the sampling
line 19A, air flows to the oil feed system 6 through the sampling
line 19A similarly to the first embodiment. In other words, air or
oil or mixed fluid of them flows to the bypass line 16 and pressure
pulsation occurs. Change in this pulsation is detected by the
pressure sensor 20 and the controller can detect the height of the
oil surface similarly to the first embodiment.
[0047] As long as the pressure sensor 20 exists on the downstream
side relative to the outlet-side connecting part of the sampling
line 19A on the oil feed system 6, a configuration in which the
connection configuration of the sampling line 19A is made same as
the first embodiment may be employed.
[0048] Also in such a second embodiment, the same effects as the
first embodiment and the modification examples thereof can be
obtained. In particular, in the present embodiment, the size of the
sampling line 19A is small and it is also possible to expect
effects of simplification of the line configuration and reduction
in the member cost.
[0049] A third embodiment of the present invention will be
described with reference to the drawings. In the present
embodiment, the same part as the first or second embodiment is
given the same character and description thereof is omitted as
appropriate.
[0050] FIG. 6 is a schematic diagram that represents the
configuration of an oil-feed-type air compressor in the present
embodiment and shows the state in which the amount of stored oil in
the oil separator 4 is sufficient. FIG. 7 is a diagram showing the
state in which the amount of stored oil in the oil separator 4 is
insufficient in the present embodiment.
[0051] The oil-feed-type air compressor of the present embodiment
includes, instead of the pressure sensor 20, a temperature sensor
21 (detector) that detects the temperature of fluid that flows in
the sampling line 19. The temperature sensor 21 outputs the
detected temperature to a controller 7A.
[0052] As an oil surface height detection function, at the time of
load operation of the compressor main body 1, the controller 7A
determines which of air and oil the fluid that flows in the
sampling line 19 is by carrying out determination of whether the
temperature detected by the temperature sensor 21 gets out of a set
range set in advance in some cases (in other words, both
determination of whether the temperature exceeds a set value T1 set
in advance in some cases and determination of whether the
temperature falls below a set value T2 (where T2<T1) set in
advance in some cases), and outputs the determination result to the
display 8.
[0053] Specifically, as shown in FIG. 6, if the oil surface in the
oil separator 4 is higher than the predetermined height position H,
oil flows in the sampling line 19. In this case, as shown in FIG.
8, the temperature of oil detected by the temperature sensor 21
does not involve the occurrence of pulsation and falls within the
set range (in other words, equal to or lower than the set value T1
and equal to or higher than the set value T2). Thus, the controller
7A determines that the fluid that flows in the sampling line 19 is
oil. Due to this, it can be detected that the oil surface in the
oil separator 4 is higher than the predetermined height position
H.
[0054] On the other hand, as shown in FIG. 7, if the oil surface in
the oil separator 4 is lower than the predetermined height position
H, air flows in the sampling line 19. In this case, as shown in
FIG. 9, the temperature of air detected by the temperature sensor
21 involves the occurrence of pulsation and gets out of the set
range (in other words, exceeds the set value T1 or falls below the
set value T2) in some cases. Thus, the controller 7A determines
that the fluid that flows in the sampling line 19 is air. Due to
this, it can be detected that the oil surface in the oil separator
4 is lower than the predetermined height position H.
[0055] If the determination result that the fluid that flows in the
sampling line 19 is air is input to the display 8, the display 8
displays a message of "warning: lubricating oil is insufficient" or
"warning: please replenish lubricating oil," or the like, as
information based on the determination result. Furthermore, the
determination result that the fluid that flows in the sampling line
19 is oil may be input to the display 8 and the display 8 may
display a message of "lubricating oil is sufficient" or the like as
information based on the determination result.
[0056] As above, the present embodiment is based on knowledge that
pulsation hardly occurs in the temperature of oil when the oil
(liquid) is caused to flow in the sampling line 19 whereas
pulsation occurs in the temperature of air when the air (gas) is
caused to flow in the sampling line 19, and it can be determined
which of oil and air the fluid that flows in the sampling line 19
is (or which of them mainly exists). Due to this, the oil surface
height in the oil separator 4 can be monitored.
[0057] In the third embodiment, the description is made by taking
as an example the case in which the controller 7A determines which
of air and oil the fluid that flows in the sampling line 19 is (or
which of them mainly exists) by carrying out determination of
whether the temperature detected by the temperature sensor 21 gets
out of the set range in some cases (in other words, both
determination of whether the temperature detected by the
temperature sensor 21 exceeds the set value T1 in some cases and
determination of whether the temperature falls below the set value
T2 in some cases). However, the present invention is not limited
thereto and modifications are possible in such a range as not to
depart from the gist and technical idea of the present
invention.
[0058] As a fourth modification example, the controller 7A may
determine which of air and oil the fluid that flows in the sampling
line 19 is (or which of them mainly exists) by carrying out either
one of determination of whether the temperature detected by the
temperature sensor 21 exceeds the set value T1 in some cases and
determination of whether the temperature falls below the set value
T2 in some cases. Also in such a modification example, the same
effects as the above description can be obtained.
[0059] As a fifth modification example, the controller 7A may
determine which of air and oil the fluid that flows in the sampling
line 19 is (or which of them mainly exists) by carrying out one or
both of determination of whether the frequency at which the
temperature detected by the temperature sensor 21 exceeds the set
value T1 is higher than a predetermined value and determination of
whether the frequency at which the temperature detected by the
temperature sensor 21 falls below the set value T2 is higher than a
predetermined value. Also in such a modification example, the same
effects as the above description can be obtained.
[0060] As a sixth modification example, the controller 7A may
determine which of air and oil the fluid that flows in the sampling
line 19 is (or which of them mainly exists) by calculating a change
rate in the temperature detected by the temperature sensor 21
(specifically, for example, change rate of the temperature obtained
at every interval of the detection time of the temperature sensor
21) and carrying out one or both of determination of whether this
change rate exceeds a positive set value set in advance in some
cases and determination of whether the change rate falls below a
negative set value set in advance in some cases. Also in such a
modification example, the same effects as the above description can
be obtained.
[0061] Naturally it is also possible to apply the configuration of
the second embodiment (FIG. 5) to the third embodiment. In other
words, the same effects as the third embodiment can be obtained
also when the pressure sensor 20 according to the second embodiment
is replaced by the temperature sensor 21 according to the third
embodiment.
[0062] Furthermore, in the first to third embodiments and the
above-described modification examples, the description is made by
taking as an example the case in which the informing device that
informs the determination result of the controller 7 or 7A is the
display 8 that is mounted on the compressor unit 9 and displays
information based on the determination result of the controller 7
or 7A. However, the present invention is not limited thereto and
modifications are possible in such a range as not to depart from
the gist and technical idea of the present invention. As in a
seventh modification example shown in FIG. 10, the informing device
may be, for example, a communication terminal 23 that is separated
from the compressor unit 9 and displays information (specifically,
a message of, for example, "warning: lubricating oil is
insufficient" or "warning: please replenish lubricating oil," or
the like) based on the determination result of the controller 7 or
7A received through a communication channel 22. The communication
terminal 23 may be a configuration physically in contact with the
compressor unit 9 as long as it is a separated configuration as the
configuration of communication connection. For example, a
configuration may be employed in which the communication terminal
23 is placed or suspended at any place in the compressor unit 9 and
is temporarily fixed in such a manner as to be separatable.
[0063] Furthermore, as another configuration that uses the
communication channel shown in FIG. 10, a configuration may be
employed in which an external calculator (server or the like)
connected through the communication channel 22 is equipped with the
determination function of the controller 7 or 7A and the
determination result thereof is informed from the external
calculator to the communication terminal 23 through the
communication channel 22. Moreover, a configuration in which the
communication terminal 23 has the determination function of the
controller 7 or 7A may be employed.
[0064] Although not shown in the diagram, the informing device may
be a warning lamp or warning buzzer mounted on the compressor unit
9, for example. Furthermore, the controller 7 or 7A may drive the
warning lamp or warning buzzer when determining that the fluid that
flows in the sampling line 19 is air. Also in these modification
examples, the same effects as the above description can be
obtained.
[0065] Furthermore, in the first to third embodiments, the
description is made by taking as an example the case in which the
outlet side of the sampling line 19 (19A) is connected to the
upstream side of the oil filter 18 of the oil feed system 6.
However, the present invention is not limited thereto and
modifications are possible in such a range as not to depart from
the gist and technical idea of the present invention. In other
words, it suffices that the sampling line is configured in such a
manner that the inlet side is connected to the predetermined height
position of the oil separator 4 and the fluid from the
predetermined height position of the oil separator 4 is allowed to
flow by the pressure difference between the inlet side (higher
pressure side) and the outlet side (lower pressure side). For this
reason, it suffices that the pressure at the site to which the
outlet side of the sampling line is connected is lower than the
pressure in the oil separator 4 by at least the pressure loss of
the sampling line.
[0066] Moreover, in the first to third embodiments, the description
is made by taking as an example the case in which, in the
oil-feed-type air compressor, the suction throttle valve 11 that
closes the intake side of the compressor main body 1 is set in
order to switch the compressor main body 1 from load operation to
no-load operation. However, the present invention is not limited
thereto and modifications are possible in such a range as not to
depart from the gist and technical idea of the present
invention.
[0067] The oil-feed-type air compressor may include a relief valve
24 (shown by a dotted line in FIG. 1, FIG. 5, or FIG. 6) that
releases a gas on the discharge side of the compressor main body 1
(specifically, upstream side relative to the pressure regulating
valve 12 of the compressed air feed system 5) instead of the
suction throttle valve 11 in order to switch the compressor main
body 1 from load operation to no-load operation. Furthermore, if
the pressure detected by the control pressure sensor 14 becomes the
unloading start pressure Pu, the controller 7 or 7A controls the
relief valve 24 to the opened state to switch the compressor main
body 1 from load operation to no-load operation. Moreover, if the
pressure detected by the control pressure sensor 14 becomes the
load return pressure Pd, the controller 7 or 7A controls the relief
valve 24 to the closed state to switch the compressor main body 1
from no-load operation to load operation.
[0068] Alternatively, the oil-feed-type air compressor may include
both the suction throttle valve 11 and the relief valve 24.
Furthermore, the oil-feed-type air compressor may be configured in
such a manner as not to switch the compressor main body 1 from load
operation to no-load operation. In other words, the oil-feed-type
air compressor may not include the suction throttle valve 11 or the
relief valve 24 and the controller 7 or 7A may not include the
above-described operation control function. Also in these
modification examples, the same effects as the above description
can be obtained.
[0069] In the above, the description is made by taking as an
example the case in which the present invention is applied to the
oil-feed-type air compressor. However, the present invention is not
limited thereto. For example, the present invention may be applied
to a water-feed-type air compressor including a compressor main
body that compresses air (gas) while injecting water (liquid) into
compression chambers, a water separator (gas-liquid separator) that
separates the water from the compressed air (compressed gas)
discharged from the compressor main body and stores the water
therein, and a water feed system (liquid feed system) that feeds
the water stored in the water separator to the compressor main
body. If the present invention is applied to this water-feed-type
air compressor, the water surface height in the water separator can
be monitored. Furthermore, the present invention may be applied to
a compressor that compresses a gas other than air.
[0070] Moreover, in the above, the description is made by taking as
an example the compression mechanism of a so-called twin-screw
rotor composed of male and female screw rotors. However, the
present invention is not limited thereto. For example, it is also
possible to apply various compression mechanisms such as positive
displacement type and turbo type. The positive displacement type
includes rotary type, reciprocating type, and so forth. As the
rotary type, single screw rotor, twin screw rotor, and multi screw
rotor, single scroll lap and multi scroll lap, vane type, craw
type, and so forth are included. As the reciprocating type, single
reciprocating type and multi reciprocating type and so forth are
included. Moreover, the compressor main body is also not limited to
the one-compressor configuration and even a multi-stage
configuration formed of a combination based on the same forms or
different forms can be applied.
DESCRIPTION OF REFERENCE CHARACTERS
[0071] 1: Compressor main body [0072] 4: Oil separator (gas-liquid
separator) [0073] 6: Oil feed system (liquid feed system) [0074] 7,
7A: Controller [0075] 8: Display (informing device) [0076] 9:
Compressor unit [0077] 11: Suction throttle valve [0078] 19, 19A:
Sampling line [0079] 20: Pressure sensor (detector) [0080] 21:
Temperature sensor (detector) [0081] 22: Communication channel
[0082] 23: Communication terminal (informing device) [0083] 24:
Relief valve
* * * * *