U.S. patent application number 13/254250 was filed with the patent office on 2011-12-29 for gas compressor and method for controlling flow rate thereof.
This patent application is currently assigned to AIRZEN CO.,LTD. Invention is credited to Hyun-Wook Jeong, Jin-Wook Jeong, Kyu-Ok Jeong.
Application Number | 20110318182 13/254250 |
Document ID | / |
Family ID | 42710129 |
Filed Date | 2011-12-29 |
![](/patent/app/20110318182/US20110318182A1-20111229-D00000.png)
![](/patent/app/20110318182/US20110318182A1-20111229-D00001.png)
![](/patent/app/20110318182/US20110318182A1-20111229-D00002.png)
![](/patent/app/20110318182/US20110318182A1-20111229-D00003.png)
![](/patent/app/20110318182/US20110318182A1-20111229-D00004.png)
![](/patent/app/20110318182/US20110318182A1-20111229-D00005.png)
![](/patent/app/20110318182/US20110318182A1-20111229-D00006.png)
![](/patent/app/20110318182/US20110318182A1-20111229-D00007.png)
![](/patent/app/20110318182/US20110318182A1-20111229-D00008.png)
![](/patent/app/20110318182/US20110318182A1-20111229-D00009.png)
![](/patent/app/20110318182/US20110318182A1-20111229-D00010.png)
View All Diagrams
United States Patent
Application |
20110318182 |
Kind Code |
A1 |
Jeong; Kyu-Ok ; et
al. |
December 29, 2011 |
GAS COMPRESSOR AND METHOD FOR CONTROLLING FLOW RATE THEREOF
Abstract
Provided is a gas compressor with a variable diffuser system
capable of suppressing stall and surge. The gas compressor includes
i) an impeller fixed to a rotation shaft and having a plurality of
blades each including a wing surface and an edge surface on an
outer circumferential surface thereof; ii) a shroud surrounding the
wing surface; iii) a ring valve installed on a diffuser passage
connected with an outlet of the impeller and moving in a direction
parallel to the rotation shaft to open and close the diffuser
passage; iv) a plurality of veins installed in a circumferential
direction of the diffuser passage outside the ring valve in the
diffuser passage; and v) an actuator coupled with the ring valve
and the plurality of veins to sequentially control movement of the
ring valve and rotational angles of the veins.
Inventors: |
Jeong; Kyu-Ok;
(Kyungsangnam-do, KR) ; Jeong; Hyun-Wook;
(Kyungsangnam-do, KR) ; Jeong; Jin-Wook;
(Kyungsangnam-do, KR) |
Assignee: |
AIRZEN CO.,LTD
Kimhae-city
KR
|
Family ID: |
42710129 |
Appl. No.: |
13/254250 |
Filed: |
March 4, 2010 |
PCT Filed: |
March 4, 2010 |
PCT NO: |
PCT/KR2010/001361 |
371 Date: |
September 1, 2011 |
Current U.S.
Class: |
416/183 ;
417/53 |
Current CPC
Class: |
F04D 29/462
20130101 |
Class at
Publication: |
416/183 ;
417/53 |
International
Class: |
F01D 5/22 20060101
F01D005/22; F04B 49/06 20060101 F04B049/06 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 5, 2009 |
KR |
KR10-2009-0019011 |
Mar 5, 2009 |
KR |
KR10-2009-0019013 |
Claims
1. A gas compressor, comprising: an impeller fixed to a rotation
shaft and having a plurality of blades each including a wing
surface and an edge surface on an outer circumferential surface
thereof; a shroud surrounding the wing surface and having an outer
wall parallel to the edge surface; and a ring valve installed on a
diffuser passage connected with an outlet of the impeller to open
and close the diffuser passage and maintaining a gap from the end
of the impeller in a radial direction of the impeller, wherein the
ring valve slidably moves on the outer wall of the shroud while
contacting the outer wall of the shroud.
2. The gas compressor of claim 1, wherein: the ring valve maintains
a gap G of a condition described below from the end of the impeller
in the radial direction of the impeller,
0.002D.ltoreq.G.ltoreq.0.0080D wherein, D represents a diameter
(mm) at the outlet of the impeller.
3. The gas compressor of claim 2, further comprising: a plurality
of veins installed in a circumferential direction of the diffuser
passage outside the ring valve in the diffuser passage.
4. A gas compressor, comprising: an impeller fixed to a rotation
shaft and having a plurality of blades each including a wing
surface and an edge surface on an outer circumferential surface
thereof; a shroud surrounding the wing surface; a ring valve
installed on a diffuser passage connected with an outlet of the
impeller and moving in a direction parallel to the rotation shaft
to open and close the diffuser passage; a plurality of veins
installed in a circumferential direction of the diffuser passage
outside the ring valve in the diffuser passage and each having a
vein shaft; and an actuator coupled with the ring valve and the
plurality of vein shafts to sequentially control movement of the
ring valve and rotational angles of the veins.
5. The gas compressor of claim 4, wherein: the ring valve maintains
a gap G of a condition described below from the end of the impeller
in the radial direction of the impeller,
0.002D.ltoreq.G.ltoreq.0.0080D wherein, D represents a diameter
(mm) at the outlet of the impeller.
6. The gas compressor of claim 5, wherein: an outer wall of the
shroud is parallel to the edge surface and the ring valve slidably
moves on the outer wall of the shroud while contacting the outer
wall of the shroud.
7. The gas compressor of claim 6, wherein: in the impeller, spaces
among the blades are in communication with each other over the wing
surface inside the shroud.
8. The gas compressor of claim 6, wherein: in the impeller, the
spaces among the blades are separated from each other by a cover
plate on the wing surface.
9. The gas compressor of claim 4, wherein: the actuator includes an
inner guide ring surrounding the vein shaft; a plurality of ball
levers penetrating the inner guide ring and the vein shaft in the
radial direction of the impeller to couple the inner guide ring and
the vein shaft with each other; an outer guide ring surrounding the
inner guide ring, integrally connected with the ring valve by a
connector, and having a slant sliding hole; and a fixing pin fixed
to the inner guide ring through the slant sliding hole, wherein the
gas compressor further includes a diffuser frame supporting the
vein shaft, the inner guide ring, and the ring valve.
10. The gas compressor of claim 9, wherein: the vein shaft has a
cavity penetrating the vein shaft in the radial direction of the
impeller and the inner guide ring has a plurality of openings
facing the cavity in the radial direction of the impeller.
11. The gas compressor of claim 10, wherein: each of the plurality
of ball levers includes a ball member closely attached to a side
wall of the opening of the inner guide ring and a support member
inserted to the cavity to be fixed to the vein shaft.
12. The gas compressor of claim 9, wherein: the actuator further
includes a stop member controlling a rotational speed of the inner
guide ring; a control handle fixed to the outer guide ring; and an
elastic member installed between the diffuser frame and the fixing
pin.
13. The gas compressor of claim 12, wherein: the stop member
includes a pair of first bars positioned with a distance in the
circumferential direction on one surface of the inner guide ring;
and a second bar fixed to the diffuser frame and protruding so that
a part thereof is positioned between the pair of first bars.
14. The gas compressor of claim 4, wherein: the actuator includes a
link member fixed to the vein shaft; a guide shaft fixed to the
link member with a distance from the vein shaft; and a control
member rotating the vein shaft by moving the guide shaft while
forming a first guide groove receiving the guide shaft on one
surface thereof.
15. The gas compressor of claim 14, wherein: the first guide groove
is formed in the radial direction of the impeller, and the control
member further includes a second guide groove formed in a
circumferential direction of the control member while being linked
with the first guide groove.
16. The gas compressor of claim 15, further comprising: a diffuser
frame supporting the ring valve, and the vein shaft and the control
member while surrounding the ring valve, wherein in the diffuser
frame, the slant sliding hole is formed in a region overlapping
with the ring valve.
17. The gas compressor of claim 16, wherein: the control member
further includes a third guide groove formed on an inner surface of
the control member while being linked with the second guide groove,
and the actuator further includes a fixing key of which one end is
fixed to the ring valve by penetrating the slant sliding hole and
the other end is received in the third guide groove.
18. The gas compressor of claim 16, wherein: in the diffuser frame,
a plurality of vein holes which the vein shaft penetrates are
formed in a direction parallel to the rotation shaft and the slant
sliding hole is spaced apart from the vein hole between two
adjacent vein holes.
19. The gas compressor of claim 14, wherein: the control member is
connected with a control unit sensing an operational condition of
the gas compressor to be operated by a command from the control
unit.
20. The gas compressor of claim 4 wherein: the actuator includes a
first actuator coupled with the plurality of vein shafts to control
the rotational angles of the veins; and a second actuator coupled
with the ring valve to control the movement of the ring valve, and
the first actuator includes a link member fixed to the vein shaft;
a guide shat fixed to the link member with a distance from the vein
shaft; and a control member rotating the vein shaft by moving the
guide shaft while forming the first guide groove receiving the
guide shaft on one surface thereof.
21. The gas compressor of claim 20, wherein: the first guide is
formed in the radial direction of the impeller, and the control
member further includes a second guide groove formed in the
circumferential direction of the control member while being linked
with the first guide groove.
22. The gas compressor of claim 20, wherein: the ring valve has an
extension ring on an outer surface thereof, and the second actuator
includes a first nozzle spraying compressed air to the one surface
of the extension ring toward the diffuser passage; and a second
nozzle spraying compressed air to one opposite surface of the
extension ring which is faraway from the diffuser passage.
23. The gas compressor of claim 22, further comprising: a top cover
installed between the diffuser frame and the ring valve, wherein
the first nozzle is formed throughout the top cover and the
diffuser frame and the second nozzle is formed on the top
cover.
24. The gas compressor of claim 22, wherein: the control member,
and the first and second nozzles are connected with the control
unit sensing the operational condition of the gas compressor to be
operated by the command from the control unit.
25. A method for controlling a flow rate of a gas compressor
including a ring valve installed in a diffuser passage connected
with an outlet of an impeller, a plurality of veins installed in a
circumferential direction of the diffuser passage outside the ring
valve, vein shafts fixed to the plurality of veins, respectively,
and an actuator coupled with the ring valve and the vein shaft, the
method comprising: sealing the diffuser passage by closing the ring
valve in initial operation and reducing an area of the diffuser
passage outside the ring valve by closing the plurality of veins;
opening the diffuser passage by opening the ring valve for rated
operation; and increasing the area of the diffuser passage outside
the ring valve by opening the plurality of veins.
26. The method of claim 25, further comprising: for stopping the
operation after the increasing of the area of the diffuser passage,
reducing the area of the diffuser passage outside the ring valve by
closing the plurality of veins; and sealing the diffuser passage by
closing the ring valve.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims priority to and the benefit of
Korean Patent Application Nos. 10-2009-0019013 and 10-2009-0019011
filed in the Korean Intellectual Property Office on Mar. 5, 2009
and Mar. 5, 2009, the entire contents of which are incorporated
herein by reference.
BACKGROUND OF THE INVENTION
[0002] (a) Field of the Invention
[0003] The present invention relates to a gas compressor, and more
particularly, to a variable diffuser system installed on a diffuser
passage connected with an impeller outlet to prevent stall and
surge, and a method for controlling a flow rate of the gas
compressor using the same.
[0004] (b) Description of the Related Art
[0005] In general, a gas compressor accelerates and compresses gas
with a centrifugal compression force of an impeller by passing the
gas through the impeller that is rotating. A diffuser passage is
connected with an impeller outlet to convert kinetic energy into
pressure energy of gas by decelerating high-speed and high-pressure
gas discharged from the impeller while reducing noise and improving
blowing efficiency.
[0006] When a flow rate of gas that passes through the impeller is
reduced or a pressure difference between an inlet and an outlet of
the impeller decreases, an air current becomes instable. Therefore,
a counter current is generated in the diffuser passage, and as a
result, stall and surge phenomena appear. Moreover, when the flow
rate of gas is further reduced or the pressures at the inlet and
the outlet of the impeller are the same as each other, a surge mode
in which a complete counter current is periodically generated in
the diffuser passage starts to thereby significantly deteriorate
compressor efficiency.
[0007] Therefore, there was presented a variable diffuser that can
vary an area of the diffuser passage so as to minimize the stall
and the surge and control the flow rate. A general variable
diffuser is constituted by a plurality of veins placed in a
circumferential direction of the diffuser passage. In the variable
diffuser, the area of the diffuser passage is reduced as the flow
rate is reduced or the pressure difference between the inlet and
the outlet of the impeller decreases, and in the reverse case, the
area of the diffuser passage is extended so as to stabilize the air
current.
[0008] However, the impeller outlet cannot be fully sealed with the
variable diffuser in the related art and gas flows backwards
through a space between the impeller and the variable diffuser.
Therefore, there is a limit in preventing the stall and the surge.
Further, the variable diffuser in the related art is limited in a
flow rate control range and a maximum flow rate range which can be
controlled with the variable diffuser in the related art is
approximately 45% of a rated flow rate.
[0009] The above information disclosed in this Background section
is only for enhancement of understanding of the background of the
invention and therefore it may contain information that does not
form the prior art that is already known in this country to a
person of ordinary skill in the art.
SUMMARY OF THE INVENTION
[0010] The present invention has been made in an effort to provide
a gas compressor and a method for controlling a flow rate of the
gas compressor that can effectively prevent stall and surge by
preventing gas from flowing backwards by modifying a variable
diffuser system.
[0011] Further, the present invention has been made in an effort to
provide a gas compressor and a method for controlling a flow rate
of the gas compressor that can extend a maximum flow rate range
which can be controlled by modifying a variable diffuser
system.
[0012] An exemplary embodiment of the present invention provides a
gas compressor including: i) an impeller fixed to a rotation shaft
and having a plurality of blades each including a wing surface and
an edge surface on an outer circumferential surface thereof; ii) a
shroud surrounding the wing surface and having an outer wall
parallel to the edge surface; and iii) a ring valve installed on a
diffuser passage connected with an outlet of the impeller to open
and close the diffuser passage and maintaining a gap from the end
of the impeller in a radial direction of the impeller. The ring
valve slidably moves on the outer wall of the shroud while
contacting the outer wall of the shroud.
[0013] The ring valve may maintain a gap G of a condition described
below from the end of the impeller in the radial direction of the
impeller,
0.002D.ltoreq.G.ltoreq.0.0080D
[0014] wherein, D represents a diameter (mm) at the outlet of the
impeller.
[0015] The gas compressor may further include a plurality of veins
installed in a circumferential direction of the diffuser passage
outside the ring valve in the diffuser passage.
[0016] Another exemplary embodiment of the present invention
provides a gas compressor including: i) an impeller fixed to a
rotation shaft and having a plurality of blades each including a
wing surface and an edge surface on an outer circumferential
surface thereof; ii) a shroud surrounding the wing surface; iii) a
ring valve installed on a diffuser passage connected with an outlet
of the impeller and moving in a direction parallel to the rotation
shaft to open and close the diffuser passage; iv) a plurality of
veins installed in a circumferential direction of the diffuser
passage outside the ring valve in the diffuser passage and each
having a vein shaft; and v) an actuator coupled with the ring valve
and the plurality of vein shafts to sequentially control movement
of the ring valve and rotational angles of the veins.
[0017] The ring valve may maintain a gap G of a condition described
below from the end of the impeller in the radial direction of the
impeller,
0.002D.ltoreq.G.ltoreq.0.0080D
[0018] wherein, D represents a diameter (mm) at the outlet of the
impeller. An outer wall of the shroud may be parallel to the edge
surface and the ring valve may slidably move on the outer wall of
the shroud while contacting the outer wall of the shroud.
[0019] In the impeller, spaces among the blades may be in
communication with each other over the wing surface inside the
shroud. On the contrary, in the impeller, the spaces among the
blades may be separated from each other by a cover plate on the
wing surface.
[0020] The actuator may include: i) an inner guide ring surrounding
the vein shaft; ii) a plurality of ball levers penetrating the
inner guide ring and the vein shaft in the radial direction of the
impeller to couple the inner guide ring and the vein shaft with
each other; iii) an outer guide ring surrounding the inner guide
ring, integrally connected with the ring valve by a connector, and
having a slant sliding hole; and iv) a fixing pin fixed to the
inner guide ring through the slant sliding hole. The gas compressor
may further include a diffuser frame supporting the vein shaft, the
inner guide ring, and the ring valve.
[0021] The vein shaft may have a cavity penetrating the vein shaft
in the radial direction of the impeller and the inner guide ring
may have a plurality of openings facing the cavity in the radial
direction of the impeller. Each of the plurality of ball levers may
include a ball member closely attached to a side wall of the
opening of the inner guide ring and a support member inserted to
the cavity to be fixed to the vein shaft.
[0022] The actuator may further include: i) a stop member
controlling a rotational speed of the inner guide ring; ii) a
control handle fixed to the outer guide ring; and iii) an elastic
member installed between the diffuser frame and the fixing pin.
[0023] The stop member may include; a pair of first bars positioned
with a distance in the circumferential direction on one surface of
the inner guide ring; and a second bar fixed to the diffuser frame
and protruding so that a part thereof is positioned between the
pair of first bars.
[0024] On the contrary, the actuator may include: i) a link member
fixed to the vein shaft; ii) a guide shaft fixed to the link member
with a distance from the vein shaft; and iii) a control member
rotating the vein shaft by moving the guide shaft while forming a
first guide groove receiving the guide shaft on one surface
thereof.
[0025] The first guide groove may be formed in the radial direction
of the impeller, and the control member may further include a
second guide groove formed in a circumferential direction of the
control member while being linked with the first guide groove. The
gas compressor may further include a diffuser frame supporting the
ring valve, and the vein shaft and the control member while
surrounding the ring valve, and in the diffuser frame, the slant
sliding hole may be formed in a region overlapping with the ring
valve.
[0026] The control member may further include a third guide groove
formed on an inner surface of the control member while being linked
with the second guide groove. The actuator may further include a
fixing key of which one end is fixed to the ring valve by
penetrating the slant sliding hole and the other end is received in
the third guide groove.
[0027] In the diffuser frame, a plurality of vein holes which the
vein shaft penetrates may be formed in a direction parallel to the
rotation shaft and the slant sliding hole may be spaced apart from
the vein hole between two adjacent vein holes. The control member
may be connected with a control unit sensing an operational
condition of the gas compressor to be operated by a command from
the control unit.
[0028] On the contrary, the actuator may include: i) a first
actuator coupled with the plurality of vein shafts to control the
rotational angles of the veins; and ii) a second actuator coupled
with the ring valve to control the movement of the ring valve. The
first actuator may include: i) a link member fixed to the vein
shaft; ii) a guide shaft fixed to the link member with a distance
from the vein shaft; and iii) a control member rotating the vein
shaft by moving the guide shaft while forming a first guide groove
receiving the guide shaft on one surface thereof.
[0029] The first guide groove may be formed in the radial direction
of the impeller, and the control member may further include a
second guide groove formed in a circumferential direction of the
control member while being linked with the first guide groove.
[0030] The ring valve may have an extension ring on an outer
surface thereof, and the actuator may include: i) a first nozzle
spraying compressed air to one surface of the extension ring toward
the diffuser passage; and ii) a second nozzle spraying compressed
air to one opposite surface of the extension ring which is faraway
from the diffuser passage.
[0031] The gas compressor may further include a top cover installed
between the diffuser frame and the ring valve. The first nozzle may
be formed throughout the top cover and the diffuser frame and the
second nozzle is formed on the top cover. The control member, and
the first and second nozzles may be connected with the control unit
sensing the operational condition of the gas compressor to be
operated by the command from the control unit.
[0032] Yet another exemplary embodiment of the present invention
provides a method for controlling a flow rate of a gas compressor,
including; i) sealing a diffuser passage by closing a ring valve in
initial operation and reducing an area of the diffuser passage
outside the ring valve by closing a plurality of veins; ii) opening
the diffuser passage by opening the ring valve for rated operation;
and iii) increasing the area of the diffuser passage outside the
ring valve by opening the plurality of veins.
[0033] The method may further include; for stopping the operation
after the increasing of the area of the diffuser passage, i)
reducing the area of the diffuser passage outside the ring valve by
closing the plurality of veins; and ii) sealing the diffuser
passage by closing the ring valve.
BRIEF DESCRIPTION OF THE DRAWINGS
[0034] FIG. 1 is a partial cross-sectional view of a gas compressor
according to a first exemplary embodiment of the present
invention.
[0035] FIG. 2 is a partially enlarged diagram of the gas compressor
shown in
[0036] FIG. 1.
[0037] FIG. 3 is a plan view schematically showing an impeller and
a ring valve in the gas compressor shown in FIG. 1.
[0038] FIG. 4 is a plan view schematically showing an impeller and
a ring valve in a gas compressor according to a comparative
example.
[0039] FIG. 5 is a graph showing measurement of a vibration state
depending on variation of a gap between a ring valve and the end of
an impeller.
[0040] FIGS. 6 and 7 are exploded perspective views of a variable
diffuser system in the gas compressor shown in FIG. 1.
[0041] FIG. 8 is a cross-sectional view of an outer guide ring, a
ring valve, and a connector in the variable diffuser system shown
in FIG. 7.
[0042] FIG. 9 is a perspective view of a combined state of the
variable diffuser system in the gas compressor shown in FIG. 1.
[0043] FIGS. 10 to 13 are schematic diagrams of a variable diffuser
system shown to describe a method for controlling a flow rate in
the gas compressor according to the first exemplary embodiment of
the present invention.
[0044] FIG. 14 is a partial cross-sectional view of a gas
compressor according to a second exemplary embodiment of the
present invention.
[0045] FIG. 15 is a partially enlarged diagram of the gas
compressor shown in FIG. 14.
[0046] FIG. 16 is an exploded perspective view of a variable
diffuser system in the gas compressor shown in FIG. 14.
[0047] FIG. 17 is a partially enlarged diagram of FIG. 16.
[0048] FIG. 18 is a perspective view showing a combined state of a
diffuser frame and a ring valve shown in FIG. 17.
[0049] FIG. 19 is a right side view of the variable diffuser system
in the gas compressor shown in FIG. 14.
[0050] FIG. 20 is a partially enlarged perspective view showing a
part of a control member, and a guide shaft and a fixation key in a
configuration of the variable diffuser system shown in FIG. 19.
[0051] FIGS. 21 to 23 are perspective views showing states of a
ring valve and a vein at points (a), (b), and (c) shown in FIG. 19,
respectively.
[0052] FIG. 24 is a partial cross-sectional view of a gas
compressor according to a third exemplary embodiment of the present
invention.
[0053] FIG. 25 is an exploded perspective view of a variable
diffuser system in the gas compressor shown in FIG. 24.
[0054] FIG. 26 is a right side view of the variable diffuser system
shown in FIG. 24.
[0055] FIG. 27 is a partially enlarged diagram of the gas
compressor shown in FIG. 24.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0056] The present invention will be described more fully
hereinafter with reference to the accompanying drawings, in which
exemplary embodiments of the invention are shown. As those skilled
in the art would realize, the described embodiments may be modified
in various different ways, all without departing from the spirit or
scope of the present invention.
[0057] FIG. 1 is a partial cross-sectional view of a gas compressor
100 according to a first exemplary embodiment of the present
invention.
[0058] Referring to FIG. 1, the gas compressor 100 of the first
exemplary embodiment includes a rotation shaft 11, an impeller 12,
a shroud 13, a ring valve 14, a plurality of veins 15 (one vein is
shown in FIG. 1), and an actuator 20. The gas compressor 100 shown
in FIG. 1 has bilateral symmetry around a center line (A-A line) of
the rotation shaft 11.
[0059] The impeller 12 is fixed to the rotation shaft 11 and the
rotation shaft 11 is coupled to a rotation shaft of a motor (not
shown). A plurality of blades 16 having a curved radial pattern are
formed on an external circumferential surface of the impeller 12.
The blade 16 includes a wing surface 161 formed at a predetermined
curvature and an edge surface 162 connected to the wing surface 161
and parallel to the rotation shaft 11. The shroud 13 is installed
to surround the impeller 12 at a predetermined gap from the wing
surface 161 of the blade 16.
[0060] When a motor operates to rotate the impeller 12, external
gas flows into the rotating impeller 12 and is accelerated and
compressed while passing through spaces among the blades 16 and
thereafter, the external gas is discharged outside the edge
surfaces 162 of the blades 16. In FIG. 1, a flow-in direction and a
discharge direction of gas are indicated by arrows. In the
exemplary embodiment, an outlet of the impeller represents a
vicinity of the end of the impeller 12 where the compressed gas is
discharged.
[0061] A diffuser passage 17 is positioned outside the outlet of
the impeller 12. The diffuser passage 17 as a space formed between
a discharge scroll 18 and a diffuser frame 30 is provided to have a
ring shape having a predetermined height and a predetermined width.
The diffuser passage 17 is connected with an internal passage of
the discharge scroll 18 and converts kinetic energy into pressure
energy of gas by diffusing and decelerating the high-speed and
high-pressure gas discharged from the impeller 12.
[0062] In the exemplary embodiment, the ring valve 14, the
plurality of veins 15, and the actuator 20 constitute a variable
diffuser system. The ring valve 14 operates to open and close the
diffuser passage 17 and prevents stall and surge by sealing the
diffuser passage 17 at initial operation. The plurality of veins 15
operate to vary a rotational angle and stabilizes an air current by
varying an area of the diffuser passage 17 outside the ring valve
14. The actuator 20 is mechanically coupled with the ring valve 14
and the plurality of veins 15 to sequentially control the movement
of the ring valve 14 and the rotational angle of the vein 15.
[0063] FIG. 2 is a partially enlarged diagram of the gas compressor
100 shown in FIG. 1 and shows a state in which the ring valve 14
descends toward the discharge scroll 18 to seal the diffuser
passage 17. FIG. 3 is a plan view schematically showing the
impeller 12 and the ring valve 14 in the gas compressor 100 shown
in FIG. 1.
[0064] Referring to FIGS. 2 and 3, an outer wall 131 of the shroud
13 is parallel to the edge surface 162 of the blade 16 and
maintains a predetermined gap from the edge surface 162 and the end
of the impeller 12 in a radial direction of the impeller 12.
Herein, the `radial direction` represents a direction rambling over
in a direction perpendicular to the rotation shaft 11 from the
center of the impeller 12.
[0065] The ring valve 14 contacts the outer wall of the shroud 13
and slides on the outer wall 131 of the shroud 13 to open or close
the diffuser passage 17. Therefore, when the ring valve 14 descends
toward the discharge scroll 18 to seal the diffuser passage 17, the
ring valve 14 maintains the predetermined gap from the edge surface
162 and the end of the impeller 12.
[0066] In the exemplary embodiment, the gap G (see an enlarged
circle of FIG. 2, and FIG. 3) between the ring valve 14 and the end
of the impeller 12 measured in the radial direction of the impeller
12 is set to meet the following condition according to a diameter D
(mm) (see FIG. 3) at the outlet of the impeller 12.
0.002D.ltoreq.G.ltoreq.0.0080D (1)
[0067] A minimum value of the gap G is set by considering
limitations such as thermal expansion of the impeller 12 and the
ring valve 14 and a radial clearance of the rotation shaft 11. That
is, when the gap G is less than 0.002 D, the impeller 12 and the
ring valve 14 may contact each other by the thermal expansion of
the impeller 12 and the ring valve 14 and it is difficult to
precisely adjust the clearance between the rotation shaft 11 and
the impeller 12 during installation. Further, when assembly
precision is low, the impeller 12 may hit the ring valve 14 while
the gas compressor 100 operates.
[0068] A maximum value of the gap G is set by considering
functionality of the ring valve 14 preventing the stall and the
surge. That is, when the gap G is more than 0.008 D, gas flows
backwards through a space between the impeller 12 and the ring
valve 14 to cause the stall and the surge, and as a result,
stability and efficiency of the gas compressor 100 deteriorates
significantly. The gas compressor 100 of the first exemplary
embodiment may implement high efficiency as the gap G between the
ring valve 14 and the end of the impeller 12 is set to be closer to
the minimum value in the range of Condition (1).
[0069] The diameter D at the outlet of the impeller 12 may be in
the range of 10 to 800 mm and in this case, the gap G between the
ring valve 14 and the end of the impeller 12 may be set to the
range of 0.02 to 6.4 mm according to Condition (1). When the gas
compressor 100 is a high-speed gas compressor of 7,000 rpm or more,
although the gap G may vary depending on rated air volume and
pressure, the gap G may be 0.2 mm if the diameter D at the outlet
of the impeller 12 is 50 mm and the gap G may be 2 mm if the
diameter D at the outlet of the impeller 12 is 500 mm.
[0070] FIG. 4 is a plan view schematically showing an impeller 12
and a ring valve 14' in a gas compressor according to a comparative
example in which a gap G2 between the ring valve 14' and the end of
the impeller 12 is more than 0.008 D. Referring to FIGS. 3 and 4,
the reason why a difference in stability and efficiency is
generated between the gas compressor of the exemplary embodiment
that meets Condition (1) and the gas compressor of the comparative
example that does not meet Condition (1) will be described. In
FIGS. 3 and 4, arrow B represents a rotational direction of the
impeller 12.
[0071] First, referring to FIG. 3, in the gas compressor 100 of the
exemplary embodiment, the ring valve 14 maintains the gap G that
meets Condition (1) from the end of the impeller 12 on the
circumference of the impeller 12. For example, when the diameter D
at the outlet of the impeller 12 is 200 mm, the gap G is set to the
range of 0.4 to 1.6 mm.
[0072] In the gas compressor 100 of the exemplary embodiment, when
the ring valve 14 descends to seal the diffuser passage 17, the
impeller 12 is completely surrounded by the shroud 13 and the ring
valve 14 except for an inlet into which external gas flows. When
initial operation starts in this state, gas compressed in spaces 19
among the blades 16 cannot be discharged outside the impeller 12
and just continuously rotates in the same space while the gas
cannot flow backwards against the impeller 12 due to centrifugal
force.
[0073] In FIG. 3, a rotational direction of the compressed gas is
indicated by a dotted arrow. Therefore, the entirety of the spaces
19 among the blades 16 is filled with the compressed gas and
external gas cannot be suctioned at the inlet of the impeller 12
any more.
[0074] As a result, while gas is not additionally suctioned other
than a minimum amount of gas suctioned at initial operation, since
a rotation speed of the gas compressor increases up to a rated
rotation speed, no-load operation can be implemented and the stall
and surge caused due to the backflow of gas can be prevented.
Further, even in the case where gas flows backwards to the impeller
12 due to a problem in a used place connected with the discharge
scroll 18, the backflow of gas can be prevented by sealing the
diffuser passage 17 with the ring valve 14, thereby effectively
suppressing the stall and the surge.
[0075] Referring to FIG. 4, in the gas compressor of the
comparative example, the ring valve 14' maintains the gap G2 that
does not meet Condition (1) from the end of the impeller 12 on the
circumference of the impeller 12. For example, when the diameter D
at the outlet of the impeller 12 is 200 mm, the gap G2 is more than
1.6 mm.
[0076] In the case of the comparative example, gas flows backwards
through a space between the impeller 12 and the ring valve 14'.
That is, compressed gas in the spaces 19 among the blades 16 when
the impeller 12 rotates flows backwards to spaces among other
blades in a direction opposite to a rotation direction of the
impeller 12 through a space between the impeller 12 and the ring
valve 14' to flows toward the inlet of the impeller 12. In FIG. 4,
a flow direction of the compressed gas is indicated by an arrow.
Therefore, in the gas compressor of the comparative example,
no-load operation cannot be implemented, and the stall and surge
caused due to the backflow of gas are permitted.
[0077] FIG. 5 is a graph showing measurement of a vibration state
depending on variation of a gap G between a ring valve and the end
of an impeller. In the gas compressor used in an experiment, the
diameter D at the outlet of the impeller is 200 mm, the height of
the blade is 18 mm, and the experiment is performed under room
temperature and atmospheric pressure conditions. The gap G between
the ring valve and the end of the impeller is 0.4 mm or more
according to Condition (1) and a vibration value of the impeller is
measured while extending the gap by each 0.2 mm.
[0078] Referring to FIG. 5, as the gap G between the ring valve and
the end of the impeller increases, the vibration value gradually
increases, but a range in which the gap G is equal to or less than
1.6 mm belongs to a normal operation range. On the contrary, it can
be verified that the vibration value increase rapidly while the gap
G is more than 1.6 mm to enter an initial stall and surge region.
From the result of FIG. 5, stability and efficiency are
significantly deteriorated in the gas compressor of the comparative
example that does not meet Condition 1.
[0079] In the gas compressor 100 of the first exemplary embodiment,
the ring valve 14 basically has a flow rate control function and
more primarily serves as a valve that closes the entire outlet of
the impeller 12 so that the compressed gas cannot deviate from the
impeller 12. Therefore, the backflow of gas is prevented by using
the ring valve 14 to effectively prevent the stall and the
surge.
[0080] The actuator 20 is mechanically coupled with the ring valve
14 and the plurality of veins 15 and sequentially control the
movement of the ring valve 14 and the rotational angle of the vein
15. Next, a coupling structure of the ring valve 14, the plurality
of veins 15, and the actuator 20 will be described.
[0081] FIGS. 6 and 7 are exploded perspective views of a variable
diffuser system in the gas compressor 100 shown in FIG. 1.
[0082] Referring to FIGS. 6 and 7, the plurality of veins 15 are
arranged at regular intervals in a circumferential direction of the
diffuser passage 17 at one portion of the diffuser frame 30. A vein
shaft 21 is fixed to each vein 15 and a cavity 211 penetrating the
vein shaft 21 is formed on the vein shaft 21 in a radial
direction.
[0083] The diffuser frame 30 includes a first flange 31 and a
second flange that are spaced apart from each other, and a
connection flange 33 connecting an inner end of the second flange
32 with an inner end of the first flange 31. A plurality of first
openings 301 for mounting the vein shaft 21 are arranged in the
first and second flanges 31 and 32 at regular intervals in a
circumferential direction.
[0084] The actuator 20 includes an inner guide ring 22 surrounding
the plurality of vein shafts 21, a plurality of ball levers 23
coupling the inner guide ring 22 with the vein shafts 21, an outer
guide ring 24 integrally connected with the ring valve 14 while
surrounding the inner guide ring 22, and a plurality of fixing pins
25 coupling the outer guide ring 24 with the inner guide ring
22.
[0085] A plurality of second openings 221 penetrating the inner
guide ring 22 in the radial direction of the impeller 12 are
arranged in the inner guide ring 22 at regular intervals in the
circumferential direction. When the vein shaft 21 penetrates the
first openings 301 of the diffuser frame 30 to be coupled to the
diffuser frame 30, the inner guide ring 22 is placed outside the
connection flange 33 and the second flange 32 to surround the
plurality of vein shafts 21. In this case, the cavity 211 of the
vein shaft 21 and the second openings 221 of the inner guide ring
22 are placed to face each other in the radial direction.
[0086] The ball lever 23 penetrates the second openings 221 of the
inner guide ring 22 and the cavity 211 of the vein shaft 21 to be
fixed to the vein shaft 21. The ball lever 23 includes a ball
member 231 closely attached to a side wall of the second opening
221 of the inner guide ring 22 and a support member 232 inserted
into the cavity 211 to be fixed to the vein shaft 21. Therefore,
when the inner guide ring 22 rotates, the vein shaft 21 rotates
together in link with the inner guide ring 22 through the ball
lever 23.
[0087] A stop member 26 controlling a rotational speed of the inner
guide ring 22 is installed in the diffuser frame 30 and the inner
guide ring 22. The stop member 26 includes a pair of first bars 27
positioned on one surface of the inner guide ring 22 with a
distance from each other in the circumferential direction and a
second bar 28 fixed to the diffuser frame 30 and protruding so that
a portion thereof is positioned between the pair of first bars 27.
The pair of first bars 27 are positioned spaced apart from each
other by a maximum rotational distance of the inner guide ring 22
and the rotation of the inner guide ring 22 is limited while any
one of the pair of first bars 27 is suspended to the second bar
28.
[0088] Meanwhile, an inner space into which a fixing screw 29 is
inserted is formed in the vein shaft 21 to strongly fasten the ball
lever 23 with the fixing screw 29. Further, a plurality of third
openings 331 penetrating the connection flange 33 in the radial
direction of the impeller 12 are formed in the connection flange
33. At the time of disassembling the variable diffuser system, the
ball lever 23 is pushed out by pushing a tool into the third
opening 331 from the inside of the connection flange 33 to thereby
separate the ball lever 23 from the vein shaft 21.
[0089] The outer guide ring 24 is positioned in parallel to the
ring valve 14 and is formed integrally with the ring valve 14 by a
connector 34. FIG. 8 is a cross-sectional view of the outer guide
ring 24, the ring valve 14, and the connector 34 in the variable
diffuser system shown in FIG. 7. Referring to FIG. 8, the outer
guide ring 24 is lower than the ring valve 14 and the connector 34
integrally connects the end of the ring valve 14 and the end of the
outer guide ring 24.
[0090] Referring back to FIGS. 6 and 7, one or more slant sliding
holes 35 are formed in the outer guide ring 24. As one example,
four slant sliding holes 35 may be arranged in the circumferential
direction of the outer guide ring 24. The fixing pins 25 are
provided as many as the slant sliding holes 35 and each of the
fixing pins 25 is fixed to the inner guide ring 22 through the
slant sliding hole 35.
[0091] FIG. 9 is a perspective view of a combined state of the
variable diffuser system in the gas compressor 100 shown in FIG.
1.
[0092] Referring to FIG. 9, an elastic member 36 is installed
between the diffuser frame 30 and the fixing pin 25. One end of the
elastic member 36 is fixed to the diffuser frame 30 and the
opposite end of the elastic member 36 is fixed to the fixing pin
25. The elastic member 36 exerts force to pull the fixing pin 25 in
a clockwise direction (based on the figure) by using restoration
force.
[0093] In addition, a control handle 37 is attached to the outer
guide ring 24 to control the rotation of the outer guide ring 24 by
operating the control handle 37. The control handle 37 is connected
with a control unit 38 that senses operational conditions of the
gas compressor 100 such as a flow rate of gas passing through the
impeller 12, a difference in pressure between the inlet and the
outlet of the impeller 12, the backflow of gas caused due to a
problem in a used place, and is operated by a command from the
control unit 38.
[0094] Referring to FIGS. 9 to 13, a method for controlling the
flow rate of the gas compressor 100 using the variable diffuser
system will be described. A `clockwise direction` and a
`counterclockwise direction` to be described below are based on the
figures.
[0095] FIGS. 10 and 11 show states of the ring valve 14 and the
vein 15 for initial operation. Referring to FIGS. 10 and 11, the
outer guide ring 24 and the ring valve 14 descend in the initial
operation, such that the ring valve 14 seals the diffuser passage
17. In addition, the plurality of veins 15 maintain a closed state
to minimize an area of the diffuser passage 17 outside the ring
valve 14 (step S1).
[0096] In this case, a fixing pin 25 is positioned at an upper end
of a slant sliding hole 35. In addition, an elastic member 36 pulls
the fixing pin 25 in the clockwise direction by using restoration
force, but the inner guide ring 22 cannot be moved in the clockwise
direction any longer by the stop member 26. Therefore, an angle of
the vein 15 is limited at a designed minimum flow rate
position.
[0097] As described above, when the operation of the gas compressor
100 starts with the diffuser passage 17 sealed with the ring valve
14, no-load operation can be implemented as described above with
reference to FIG. 3. Further, the stall and the surge can be
suppressed by preventing the backflow of the compressed gas.
[0098] Thereafter, the control handle 37 and the outer guide ring
24 are rotated in the counterclockwise direction for rated
operation. Therefore, as shown in FIG. 9, the fixing pin 25 serves
as a slant guide, such that the outer guide ring 24 ascends from
the diffuser frame 30. Therefore, the ring valve 14 ascends to open
the diffuser passage 17 (step S2).
[0099] In this case, since the elastic member 36 pulls the fixing
pin 25 in the clockwise direction, the inner guide ring 22 and the
vein 15 linked therewith maintain the minimum flow rate position
without moving. In step S2, the fixing pin 25 is positioned at a
lower end of the slant sliding hole 35.
[0100] Thereafter, the control handle 37 and the outer guide ring
24 are further rotated in the counterclockwise direction.
Therefore, as shown in FIGS. 12 and 13, the outer guide ring 24
overcomes the restoration force of the elastic member 36 applied to
the fixing pin 25 without variation in height, and pulls and
rotates the fixing pin 25 in the counterclockwise direction. As a
result, the vein 15 is opened while the fixing pin 25, and the
inner guide ring 22 and the vein shaft 21 move to increase an area
of the diffuser passage 17 (step S3). During this process, the
fixing pin 25 moves until the rotation of the inner guide ring 22
is stopped by the stop member 26.
[0101] Next, an operational sequence for the stop is opposite to
the above-mentioned process.
[0102] That is, in FIG. 12, when the control handle 37 rotates in
the clockwise direction, the elastic member 36 pulls the fixing pin
25 in the clockwise direction, such that the fixing pin 25 cannot
serve as the slant guide with respect to the outer guide ring 24.
Therefore, the outer guide ring 24 may just rotate in the clockwise
direction without variation in height and the fixing pin 25 pulled
by the restoration force of the elastic member 36 moves in the
clockwise direction to close the vein 15 (step S4, see FIG. 9).
During this process, the fixing pin 25 moves until the rotation of
the inner guide ring 22 is stopped by the stop member 26.
[0103] In addition, in FIG. 9, when the control handle 37 is
further rotated in the clockwise direction, the fixing pin 25
serves as the slant guide, and as a result, the outer guide ring 24
and the ring valve 14 descend to seal the diffuser passage 17 as
shown in FIG. 11 (step S5). Therefore, even for a period from the
rated operation to the stopping of the impeller 12, the surge can
be effectively suppressed.
[0104] As described above, in the gas compressor 100 of the
exemplary embodiment, since the ring valve 14 and the plurality of
veins 15 are together controlled by using a single actuator 20, a
mechanical configuration for the control can be simplified.
Further, in the gas compressor 100 of the exemplary embodiment,
since the ring valve 14 and the vein 15 are sequentially driven, a
flow rate range which can be controlled with the variable diffuser
system may be extended to the maximum 100%. In the exemplary
embodiment, a flow rate control range of the ring valve 14 is
approximately in the range of 0 to 45% and a flow rate control
range of the vein 15 is approximately in the range of 45 to
100%.
[0105] Meanwhile, in FIGS. 1 to 3, a structure in which spaces
among blades 16 can be in communication with each other over a wing
surface 161 inside a shroud 13 is shown, but a structure in which a
cover plate (not shown) is fixed to the wing surface 161 to
separate the spaces among the blades 16 from each other on the wing
surface 161 can also be applied.
[0106] That is, in the case of the latter, the spaces among the
blades 16 are separated by the cover plate except for an inlet of
the impeller 12 into which gas flows and an outlet (an edge
surface) through which compressed gas is discharged. The cover
plate rotates together with the impeller 12 and maintains a
distance from the shroud 13 inside the shroud 13. In the case of
the latter, the shape of the gas compressor 100 is the same as the
structure of the above-mentioned exemplary embodiment except for
the cover plate and a gap G between the ring valve 14 and the end
of the impeller 12 also meet Condition (1) described above.
[0107] FIG. 14 is a partial cross-sectional view of a gas
compressor 200 according to a second exemplary embodiment of the
present invention and FIG. 15 is a partially enlarged diagram of
the gas compressor 200 shown in FIG. 14 and shows a state in which
a ring valve 141 descends toward a discharge scroll 18 to seal a
diffuser passage 17.
[0108] Referring to FIGS. 14 and 15, the gas compressor 200 of the
second exemplary embodiment includes a rotation shaft 11, an
impeller 12, a shroud 132, a ring valve 141, a plurality of veins
15 (one vein is shown in FIG. 14), and an actuator 40.
[0109] The gas compressor 200 of the second exemplary embodiment
has the same configuration as the gas compressor 100 of the first
exemplary embodiment except for the shapes of the ring valve 141,
and the actuator 40 and the diffuser frame 50. The same reference
numerals refer to the same members as the first exemplary
embodiment and members different from the first exemplary
embodiment will be primarily described below.
[0110] FIG. 16 is an exploded perspective view of a variable
diffuser system in the gas compressor 200 shown in FIG. 14 and FIG.
17 is a partially enlarged diagram of FIG. 16.
[0111] Referring to FIGS. 16 and 17, the plurality of veins 15 are
arranged at regular intervals in a circumferential direction of the
diffuser passage 17 at one portion of the diffuser frame 50 and a
vein shaft 21 is fixed to each vein 15.
[0112] The diffuser frame 50 includes a ring-shaped flange 51 and a
cylindrical support portion 52 extending from the inside of the
flange 51 with a predetermined height. The flange 51 is placed to
face the discharge scroll 18 inside the shroud 132 to form the
diffuser passage 17 between the flange 51 and the discharge scroll
18. The support portion 52 extends in a direction farther from the
discharge scroll 18 from the inside of the flange 51.
[0113] A plurality of vein holes 53 penetrating the support portion
52 in a direction parallel to the rotation shaft 11 are formed in
the support portion 52. In addition, each vein shaft 21 is inserted
into the vein hole 53, such that the vein 15 and the vein shaft 21
are supported by the diffuser frame 50. In this case, the length of
the vein shaft 21 is larger than the height of the support portion
52 and after the vein shaft 21 is coupled to the diffuser frame 50,
the end of the vein shaft 21 protrudes outside the support portion
52.
[0114] The end of the vein shaft 21 is fixed to one end of a link
member 41 and a guide shaft 42 is fixed to one opposite end of the
link member 41 with a predetermined distance from the vein shaft
21. The link member 41 and the guide shaft 42 are provided as many
as the vein shafts 21 and the guide shaft 42 is shorter than the
vein shaft 21. As the vein shaft 21 is connected with the guide
shaft 42 through the link member 41, when the guide shaft 42
rotatably moves around the vein shaft 21, the vein shaft 21 rotates
to control opening and closing degrees of the vein 15.
[0115] The ring valve 141 is coupled to the inside of the support
portion 52 and an outer surface of the ring valve 141 is closely
attached to an inner surface of the support portion 52. A plurality
of slant sliding holes 54 penetrating the support portion 52 in the
radial direction of the impeller 12 are formed in the support
portion 52. The slant sliding hole 54 is positioned between two
adjacent vein holes 53 not to be connected with the vein hole 53
and placed to be slant in a direction parallel to the rotation
shaft 11.
[0116] FIG. 18 is a perspective view showing a combined state of
the diffuser frame 50 and the ring valve 141 shown in FIG. 17.
[0117] Referring to FIG. 18, after the ring valve 141 is coupled to
the inside of the support portion 52, a plurality of fixing keys 55
penetrate the slant sliding holes 54 outside the support portion 52
and thereafter, are fixed to the ring valve 141. In this case, the
end of the fixing key 55 protrudes outside the support portion 52.
In addition, the width of the fixing key 55 is smaller than that of
the slant sliding hole 54, such that the fixing key 55 moves in a
longitudinal direction of the slant sliding hole 54.
[0118] When the fixing key 55 is positioned at the end of the slant
sliding hole 54 which is faraway from the flange 51, the ring valve
141 is positioned with a distance from the discharge scroll 18 to
open the diffuser passage 17. On the contrary, when the fixing key
55 is positioned at the end of the slant sliding hole 54 toward the
flange 51, the ring valve 141 contacts the discharge scroll 18 to
seal the diffuser passage 17. The former is indicated by a solid
line and the latter is indicated by dotted lines.
[0119] Referring back to FIGS. 16 and 17, a ring-shaped control
member 43 is installed outside the support portion 52. The control
member 43 is coupled with the fixing key 55 to move the fixing key
55, thereby controlling forward and backward movements of the ring
valve 141. At the same time, the control member 43 is coupled with
even the guide shaft 42 to rotatably move the guide shaft 42,
thereby controlling a rotational angle of the vein 15. In the gas
compressor 200 of the second exemplary embodiment, the control
member 43, the plurality of link members 41, the plurality of guide
shafts 42, and the plurality of fixing keys 55 constitute the
actuator 40.
[0120] A plurality of guide grooves 433 are formed on one surface
of the control member 43 in the radial direction. In addition,
second guide grooves 432 connected with the first guide grooves 431
are formed in a circumferential direction of the control member 43.
The first and second guide grooves 431 and 432 are provided as many
as the vein shafts 21. Further, third guide grooves 433 are formed
on an inner surface of the control member 43 in a thickness
direction of the control member 43. The third guide grooves 433 are
provided as many as the fixing keys 55 and are finked with the
second guide grooves 432.
[0121] The guide shaft 42 is received in the first and second guide
grooves 431 and 432 to move along the first and second guide
grooves 431 and 432 when the control member 43 rotates. The fixing
key 55 is received in the third guide groove 433 to move along the
third guide groove 433 when the control member 43 rotates. A
control handle 37 transmitting rotating power to the control member
43 is positioned on an outer surface of the control member 43. The
control handle 37 is connected with the control unit 38 to be
operated by the command from the control unit 38.
[0122] FIG. 19 is a right side view of the variable diffuser system
in the gas compressor 200 shown in FIG. 14 and FIG. 20 is a
partially enlarged perspective view showing a part of the control
member 43 and the guide shaft 42 and the fixing key 55 in a
configuration of the variable diffuser system shown in FIG. 19.
[0123] Referring to FIGS. 19 and 20, the control member 43
sequentially controls the position of the ring valve 141 and the
rotational angle of the vein 15 depending on the rotational
direction and the rotational angle. That is, a movement amount of
the ring valve 141 is controlled through the rotation of the
control member 43 in a first section between point (a) and point
(b). In addition, the rotational angle of the vein 15 is controlled
through the rotation of the control member 43 in a second section
between point (b) and point (c).
[0124] First, the fixing key 55 at point (a) is positioned at the
end of the slant sliding hole 54 toward the discharge scroll 18
(see a dotted line mark of FIG. 18). Therefore, the ring valve 141
contacts the discharge scroll 18 to seal the diffuser passage 17.
In this case, the end of the fixing key 55 is positioned at the end
of the third guide groove 433 toward the discharge scroll 18.
Further, the guide shaft 42 at point (a) is positioned at the end
of the second guide groove 432 which is faraway from the first
guide groove 431. In this state, a slant angle of the vein 15 to a
tangent line of the outer surface of the ring valve 141 is
minimized to reduce an area of the diffuser passage 17.
[0125] When the control handle 37 moves toward point (b) from point
(a) to rotate the control member 43 in the counterclockwise
direction, the fixing key 55 moves in a direction which is faraway
from the discharge scroll 18 along the third guide groove 433.
Therefore, the ring valve 141 moves backwards to open the diffuser
passage 17.
[0126] The position of the guide shaft 42 does not vary in a first
section, but the guide shaft 42 is positioned at the end of the
second guide groove 432 which is linked with the first guide groove
431 at point (b) due to the rotation of the control member 43.
Since the position of the guide shaft 42 does not vary in the first
section, the vein 15 maintains the closed state as it is. As
described above, in the first section, the movement amount of the
ring valve 14 can be controlled without variation in rotational
angle of the vein 15.
[0127] When the control handle 37 moves toward point (c) from point
(b) to further rotate the control member 43 in the counterclockwise
direction, the guide shaft 42 slidably moves along the first guide
groove 431 to rotate the vein shaft 21. Therefore, the vein 15
rotates so that the slant angle of the vein 15 to the tangent line
of the outer surface of the ring valve 141 is maximized, thereby
increasing the area of the diffuser passage 17.
[0128] The position of the fixing key 55 does not vary in the
second section, but the fixing key 55 is positioned at the end of
the second guide groove 432 which is linked with the first guide
groove 431 at point (c) due to the rotation of the control member
43. Since the position of the fixing key 55 does not vary in the
second section, the ring valve 141 maintains the opened state as it
is. As described above, in the second section, the rotational angle
of the vein 15 can be controlled without the movement of the ring
valve 141.
[0129] Referring to FIGS. 21 to 23, a method for controlling the
flow rate using the variable diffuser system will be described.
[0130] FIG. 21 is a perspective view showing states of the ring
valve 141 and the vein 15 at point (a) shown in FIG. 19.
[0131] Referring to FIG. 21, in initial operation, the ring valve
141 ascends from the diffuser frame 50 to seal the diffuser passage
17. In addition, the plurality of veins 15 maintain the closed
state to reduce an area of the diffuser passage 17 outside the ring
valve 141 (step S1). As described above, when the operation of the
gas compressor 200 starts with the diffuser passage 17 sealed with
the ring valve 141, no-load operation can be implemented. Further,
stall and surge can be suppressed by preventing backflow of
compressed gas.
[0132] FIG. 22 is a perspective view showing states of the ring
valve 141 and the vein 15 at point (b) shown in FIG. 19.
[0133] Referring to FIG. 22, when the control handle 37 and the
control member 43 are rotated in the counterclockwise direction
(based on FIG. 19) for rated operation, the fixing key 55 moves
backwards the ring valve 141 while moving along the third guide
groove 433 to open the diffuser passage 17 at the position of the
ring valve 141 (step S2). In this case, the plurality of veins 15
maintain an initial state as it is.
[0134] FIG. 23 is a perspective view showing states of the ring
valve 141 and the vein 15 at point (c) shown in FIG. 19.
[0135] Referring to FIG. 23, when the control handle 37 and the
control member 43 are further rotated in the counterclockwise
direction (based on FIG. 19), the guide shaft 42 rotates the vein
shaft 21 while moving along the first guide groove 431. Therefore,
the plurality of veins 15 moves to the maximum flow rate position
to open the diffuser passage 17 (step S3).
[0136] The rated operation is performed in step S3 and the area of
the diffuser passage 17 is varied for stabilization of air current
by controlling the vein 15 depending on an operational state sensed
by the control unit 38. Further, when the backflow of gas toward
the impeller, which is caused due to a problem in a used place is
sensed in the rated operation, the variable diffuser system returns
to an initial position shown in FIG. 11 to seal the diffuser
passage 17 with the ring valve 141, thereby preventing the
surge.
[0137] An operational sequence for the stop is in reverse order to
the above-mentioned process.
[0138] When the control handle 37 and the control member 43 are
rotated in the clockwise direction (based on FIG. 19), the area of
the diffuser passage 17 is reduced while the vein 15 is closed as
shown in FIG. 22 (step S4). Thereafter, when the control handle 37
and the control member 43 are further rotated in the clockwise
direction (based on FIG. 19), the ring valve 141 ascends from the
diffuser frame 50 to seal the diffuser passage 17 as shown in FIG.
21 (step S5). Therefore, even for a period from the rated operation
to the stopping of the impeller 12, the surge can be effectively
suppressed.
[0139] FIG. 24 is a partial cross-sectional view of a gas
compressor 300 according to a third exemplary embodiment of the
present invention.
[0140] Referring to FIG. 24, the gas compressor 300 of the third
exemplary embodiment has a configuration in which a plurality of
veins 15 and a ring valve 142 are controlled by different actuators
unlike the second exemplary embodiment. That is, the gas compressor
300 of the third exemplary embodiment includes a first actuator 60
coupled with the vein shaft 21 to control the rotational angle of
the vein 15, and a second actuator 70 controlling forward and
backward movements of the ring valve 142 by using compressed
air.
[0141] Basic configurations and operations of the vein 15 and the
ring valve 142 are same as in the second exemplary embodiment
except for the structures of the first and second actuators 60 and
70. The same reference numerals refer to the same members as the
second exemplary embodiment and members different from the second
exemplary embodiment will be primarily described below.
[0142] FIG. 25 is an exploded perspective view of a variable
diffuser system in the gas compressor 300 shown in FIG. 24 and FIG.
26 is a right side view of the variable diffuser system shown in
FIG. 24.
[0143] Referring to FIGS. 25 and 26, the shapes of the vein 15 and
the vein shaft 21 are the same as in the second exemplary
embodiment. The shape of a diffuser frame 56 is the same as in the
second exemplary embodiment except that a slant sliding hole is not
formed in the support portion 52 but a first nozzle 71 to be
described below is formed in the diffuser frame 56.
[0144] A plurality of first guide grooves 441 are formed on one
surface of a control member 44 in a radial direction. After the
vein shaft 21 is coupled to the diffuser frame 56, the end thereof
protrudes outside the support portion 52, and the end of the vein
shaft 21 is fixed to one end of a link member 41. A guide shaft 42
is fixed to one opposite end of the link member 41 with a
predetermined distance from the vein shaft 21. The guide shaft 42
is received in the first guide groove 441 and the link member 41 is
placed in parallel to the radial direction. A control handle 37
transmitting rotating power to the control member 44 is positioned
on an outer surface of the control member 44.
[0145] In the third exemplary embodiment, the plurality of link
members 41, the plurality of guide shafts 42, and the control
member 44 constitute the first actuator 60. When the control member
44 is rotated in the clockwise direction (based on FIG. 26), the
area of the diffuser passage 17 is increased by rotating the vein
shaft 21 and the vein 15 in the same direction while the guide
shaft 42 rotates along the first guide groove 441 in the clockwise
direction. On the contrary, when the control member 44 is rotated
in the counterclockwise direction (based on FIG. 26), the area of
the diffuser passage 17 is decreased by rotating the vein shaft 21
and the vein 15 in the same direction while the guide shaft 42
rotates along the first guide groove 441 in the counterclockwise
direction.
[0146] FIG. 27 is a partially enlarged diagram of the gas
compressor 300 shown in FIG. 24 and shows a state in which the ring
valve 142 moves forwards toward the discharge scroll 18 to seal the
diffuser passage 17.
[0147] Referring to FIGS. 25 and 27, an extension ring 143 is
formed on an outer surface of the ring valve 142 and the outer
surface of the extension ring 143 is coupled to the inside of the
support portion 152 to be closely attached to an inner surface of
the support portion 52. A top cover 45 is installed between the
support portion 52 and the ring valve 142 and the top cover 45 is
fixed to the support portion 52 through screw connection. The ring
valve 142 maintains a gap G from the end of the impeller 12, which
meets Condition (1) in the radial direction of the impeller 12 at
the outlet of the impeller 12 like the second exemplary
embodiment.
[0148] The second actuator 70 includes a first nozzle 71 which is
formed in the top cover 45 and the support portion 52 and sprays
compressed air toward one surface (a left side surface of the
extension ring based on FIG. 27) of the extension ring 143 toward
the diffuser passage 17, and a second nozzle 72 which is formed on
the top cover 45 and sprays compressed air toward the other surface
(a right side surface of the extension ring based on FIG. 27) of
the extension ring 143 which is faraway from the diffuser passage
17.
[0149] Therefore, when the first nozzle 71 is opened to spray the
compressed air through the first nozzle 71, the extension ring 143
moves backwards the ring valve 142 by receiving force in a
direction which is faraway from the discharge scroll 18 to open the
diffuser passage 17. On the contrary, when the second nozzle 72 is
opened to spray the compressed air through the second nozzle 72,
the extension ring 143 moves forwards the ring valve 142 by
receiving force toward the discharge scroll 18 to seal the diffuser
passage 17.
[0150] In the variable diffuser system of the third exemplary
embodiment, the control handle 37 of the first actuator 60 and the
first and second nozzles 71 and 72 of the second actuator 70 are
connected with the control unit 38 to operate sequentially
according to the command from the control unit 38. The method for
controlling the flow rate of the gas compressor 300 using the ring
valve 142 and the plurality of veins 15 is the same as in the
second exemplary embodiment.
[0151] Meanwhile, in FIGS. 12 and 27, a structure in which the
spaces among the blades 16 can be in communication with each other
over the wing surface 161 inside the shroud 132 is shown, but a
structure in which a cover plate (not shown) is fixed to the wing
surface 161 to separate the spaces among the blades 16 from each
other on the wing surface 161 can also be applied.
[0152] While this invention has been described in connection with
what is presently considered to be practical exemplary embodiments,
it is to be understood that the invention is not limited to the
disclosed embodiments, but, on the contrary, is intended to cover
various modifications and equivalent arrangements included within
the spirit and scope of the appended claims.
* * * * *