U.S. patent application number 13/080965 was filed with the patent office on 2012-02-09 for impeller and centrifugal compressor including the same.
Invention is credited to Kil Young KIM.
Application Number | 20120034078 13/080965 |
Document ID | / |
Family ID | 45556290 |
Filed Date | 2012-02-09 |
United States Patent
Application |
20120034078 |
Kind Code |
A1 |
KIM; Kil Young |
February 9, 2012 |
IMPELLER AND CENTRIFUGAL COMPRESSOR INCLUDING THE SAME
Abstract
Provided is an impeller of a centrifugal compressor including: a
hub fixed to a rotation shaft; and a plurality of blades extending
outward from a center portion of the hub on one surface of the hub,
wherein a length of the blade is greater than a straight length
between an inlet end of the blade and an outlet end thereof.
Assuming that an outlet angle formed along a longitudinal direction
of the blade at the outlet end of the blade is .beta. and an
inclination angle of the blade from the one surface of the hub at
the outlet end of the blade is .gamma., the following equation is
satisfied:
1<sin(.beta.-20.degree.)+cos(.gamma.-40.degree.)<1.5.
Inventors: |
KIM; Kil Young; (Seoul,
KR) |
Family ID: |
45556290 |
Appl. No.: |
13/080965 |
Filed: |
April 6, 2011 |
Current U.S.
Class: |
415/208.1 ;
416/223R |
Current CPC
Class: |
F04D 29/284 20130101;
F04D 29/30 20130101 |
Class at
Publication: |
415/208.1 ;
416/223.R |
International
Class: |
F01D 5/14 20060101
F01D005/14; F01D 9/02 20060101 F01D009/02 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 9, 2010 |
KR |
10-2010-0076399 |
Claims
1. An impeller of a centrifugal compressor comprising: a hub fixed
to a rotation shaft; and a plurality of blades extending outward
from a center portion of the hub on one surface of the hub, wherein
a length of the blade is greater than a straight length between an
inlet end of the blade and an outlet end thereof, and assuming that
an outlet angle formed along a longitudinal direction of the blade
at the outlet end of the blade is .beta. and an inclination angle
of the blade from the one surface of the hub at the outlet end of
the blade is .gamma., the following equation is satisfied:
1<sin(.beta.-20.degree.)+cos(.gamma.-40.degree.)<1.5.
2. The impeller according to claim 1, wherein the outlet angle is
in a range of 20.degree. to 70.degree..
3. The impeller according to claim 1, wherein the inclination angle
is in a range of 40.degree. to 90.degree..
4. A centrifugal compressor comprising: an impeller which is fixed
to a rotation shaft to be rotated at high speed; and a diffuser
which converts kinetic energy of a compressible medium that is
increased by the impeller into pressure energy, wherein the
impeller comprises: a hub fixed to the rotation shaft; and a
plurality of blades extending outward from a center portion of the
hub on one surface of the hub, a length of the blade is greater
than a straight length between an inlet end of the blade and an
outlet end thereof, and assuming that an outlet angle formed along
a longitudinal direction of the blade at the outlet end of the
blade is .beta. and an inclination angle of the blade from the one
surface of the hub at the outlet end of the blade is .gamma., the
following equation is satisfied:
1<sin(.beta.-20.degree.)+cos(.gamma.-40.degree.)<1.5.
5. The centrifugal compressor according to claim 4, wherein the
outlet angle is in a range of 20.degree. to 70.degree..
6. The centrifugal compressor according to claim 4, wherein the
inclination angle is in a range of 40.degree. to 90.degree..
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims priority to Korean Patent
Application No. 10-2010-0076399, filed on Aug. 9, 2010, and all the
benefits accruing therefrom under 35 U.S.C. .sctn.119, the contents
of which in its entirety are herein incorporated by reference.
BACKGROUND
[0002] 1. Field
[0003] This disclosure relates to a centrifugal compressor, and
more particularly, to an impeller which adds velocity energy to a
compressible medium while rotating at high speed.
[0004] 2. Description of the Related Art
[0005] A compressor is a device for compressing gas by applying
mechanical energy and is necessary for an air-conditioning
apparatus such as a refrigerator to compress a cooling medium.
There are different kinds of compressors, including a reciprocating
compressor, a screw compressor, a centrifugal compressor, and the
like. Particularly, the centrifugal compressor rotating at high
speed has been widely used since fluctuation of a discharge gas
does not occur and reductions in size and weight are easily
achieved.
[0006] In general, a centrifugal compressor used in a freezer
includes a casing having a cooling medium inlet port on one side,
an impeller which is provided inside the casing for compressing a
cooling medium flowing therein, a diffuser for converting kinetic
energy of the cooling medium compressed by the impeller into
pressure energy, and a volute for transferring the cooling medium
passing through the diffuser to a discharge duct. The cooling
medium flowing through the cooling medium inlet port of the
centrifugal compressor is compressed by the impeller and the
diffuser, passes through the volute and the discharge duct, and
then is transferred to a condenser.
[0007] The impeller which may be considered as the heart of the
centrifugal compressor includes a number of blades and applies
centrifugal force to the compressible medium (the cooling medium)
by rotating at high speed. Thus, there is a problem in that noise
occurs.
SUMMARY
[0008] This disclosure provides an impeller which has an optimal
structure to minimize noise and a centrifugal compressor including
the same.
[0009] In one aspect, there is provided an impeller of a
centrifugal compressor including: a hub fixed to a rotation shaft;
and a plurality of blades extending outward from a center portion
of the hub on one surface of the hub, wherein a length of the blade
is greater than a straight length between an inlet end of the blade
and an outlet end thereof. Assuming that an outlet angle formed
along a longitudinal direction of the blade at the outlet end of
the blade is .beta. and an inclination angle of the blade from the
one surface of the hub at the outlet end of the blade is .gamma.,
Equation (1) is satisfied:
1<sin(.beta.-20.degree.)+cos(.gamma.-40.degree.)<1.5 (1)
[0010] The outlet angle .beta. may be in a range of 20.degree. to
70.degree..
[0011] The inclination angle .gamma. may be in a range of
40.degree. to 90.degree..
[0012] In another aspect, there is provided a centrifugal
compressor including: an impeller which is fixed to a rotation
shaft to be rotated at high speed; and a diffuser which converts
kinetic energy of a compressible medium that is increased by the
impeller into pressure energy, wherein the impeller satisfies
Equation (1).
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] The above and other aspects, features and advantages of the
disclosed exemplary embodiments will be more apparent from the
following detailed description taken in conjunction with the
accompanying drawings in which:
[0014] FIG. 1 is a cross-sectional view illustrating a centrifugal
compressor according to an embodiment;
[0015] FIG. 2 is a perspective view of an impeller according to an
embodiment;
[0016] FIG. 3 is a front view of the impeller for illustrating an
outlet angle of a blade;
[0017] FIG. 4 is a partial side view of the impeller for
illustrating an inclination angle of the blade;
[0018] FIG. 5 is a graph showing a change in noise level depending
on a value of sin(.beta.-20).degree.+cos(.gamma.-40.degree.) in
regard to the outlet angle .beta. and the inclination angle .gamma.
of the blade;
[0019] FIG. 6 is a graph showing a change in noise level depending
on the outlet angle of the blade; and
[0020] FIG. 7 is a graph showing a change in noise level depending
on the inclination angle of the blade.
DETAILED DESCRIPTION
[0021] Exemplary embodiments now will be described more fully
hereinafter with reference to the accompanying drawings, in which
exemplary embodiments are shown. This disclosure may, however, be
embodied in many different forms and should not be construed as
limited to the exemplary embodiments set forth therein. Rather,
these exemplary embodiments are provided so that this disclosure
will be thorough and complete, and will fully convey the scope of
this disclosure to those skilled in the art. In the description,
details of well-known features and techniques may be omitted to
avoid unnecessarily obscuring the presented embodiments.
[0022] The terminology used herein is for the purpose of describing
particular embodiments only and is not intended to be limiting of
this disclosure. As used herein, the singular forms "a", "an" and
"the" are intended to include the plural forms as well, unless the
context clearly indicates otherwise. Furthermore, the use of the
terms a, an, etc. does not denote a limitation of quantity, but
rather denotes the presence of at least one of the referenced item.
It will be further understood that the terms "comprises" and/or
"comprising", or "includes" and/or "including" when used in this
specification, specify the presence of stated features, regions,
integers, steps, operations, elements, and/or components, but do
not preclude the presence or addition of one or more other
features, regions, integers, steps, operations, elements,
components, and/or groups thereof.
[0023] Unless otherwise defined, all terms (including technical and
scientific terms) used herein have the same meaning as commonly
understood by one of ordinary skill in the art. It will be further
understood that terms, such as those defined in commonly used
dictionaries, should be interpreted as having a meaning that is
consistent with their meaning in the context of the relevant art
and the present disclosure, and will not be interpreted in an
idealized or overly formal sense unless expressly so defined
herein.
[0024] In the drawings, like reference numerals in the drawings
denote like elements. The shape, size and regions, and the like, of
the drawing may be exaggerated for clarity.
[0025] Hereinafter, a centrifugal compressor according to an
embodiment of the present disclosure will be described in detail
with reference to the accompanying drawings.
[0026] FIG. 1 is a cross-sectional view illustrating a centrifugal
compressor according to an embodiment. FIG. 2 is a perspective view
of an impeller according to an embodiment. FIG. 3 is a front view
of the impeller for illustrating an outlet angle of a blade. FIG. 4
is a partial side view of the impeller for illustrating an
inclination angle of the blade. And, FIG. 5 is a graph showing a
change in noise level depending on a value of
sin(.beta.-20.degree.)+cos(.gamma.-40.degree.) in regard to the
outlet angle .delta. and the inclination angle .gamma. of the
blade.
[0027] Referring to FIG. 1, the centrifugal compressor 100
according to an embodiment includes a casing 10, a rotation shaft
20 which penetrates the center of the casing 10 to be connected to
a motor, an impeller 30 which is fixed to the rotation shaft 20 to
be rotated so as to cause a compressible medium such as a cooing
medium to flow therein, and a diffuser 40 which is disposed at a
predetermined interval from the impeller 30 to convert kinetic
energy of the compressible medium into pressure energy.
[0028] On one side of the casing 10, there is provided an inlet
port 12 through which the compressible medium flows and which is
disposed in a longitudinal direction of the rotation shaft 20. An
inlet guide vane (IGV) 50 for controlling an inflow of the cooling
medium is provided in the inlet port 12. A bearing member 60 for
supporting the rotation shaft 20 is provided on the rear of the
impeller 30.
[0029] The cooling medium compressed by the impeller 30 and the
diffuser 40 is directed to the discharge duct through the volute
70.
[0030] In the centrifugal compressor 100 having the above-described
configuration, the impeller 30 includes, as illustrated in FIG. 2,
a hub 32 which is directly fixed to the rotation shaft 20, and
blades 34 which protrude from one surface of the hub 32 for
inducing a flow of the cooling medium. The hub 32 may have various
shapes such as a disk shape or a columnar shape having a width
increasing in an axial direction in which the cooling medium
flows.
[0031] A plurality of the blades 34 extend outward from the center
portion of the hub 32 in a radial direction at predetermined
intervals. Each blade 34 may extend in a streamline shape, and
accordingly, an actual length (curve length) of the blade 34 may be
greater than a straight length between an inlet end 342 and an
outlet end 344 of the blade 34.
[0032] The shape of the blade 34 has a great effect on the flow of
the cooling medium. Particularly, the outlet angle .beta. and the
inclination angle .gamma. of the blade 34 are factors having a
great effect on generation of noise due to the flow of the cooling
medium.
[0033] As illustrated in FIG. 3, the outlet angle .beta. of the
blade 34 refers to an angle between a longitudinal direction
(tangential direction) of the blade 34 and a tangential direction
of the hub 32 at a point where the outlet end 344 of the blade 34
meets an outermost portion of the hub 32. As illustrated in FIG. 4,
the inclination angle .gamma. refers to an angle between a height
direction of the blade 34 and a tangential direction of the one
surface of the hub 32 at the outlet end 344 of the blade 34.
[0034] The impeller 30 of the centrifugal compressor 100 according
to an embodiment satisfies Equation (1) in regard to the outlet
angle .beta. and the inclination angle .gamma. of the blade 34.
1<sin(.beta.-20.degree.)+cos(.gamma.-40.degree.)<1.5 (1)
[0035] The applicant discovered that noise generation by the
impeller 30 is minimized when the outlet angle .beta. and the
inclination angle .gamma. of the blade 34 satisfy Equation (1).
[0036] As illustrated in FIG. 5, in regard to the outlet angle
.beta. and the inclination angle .gamma. of the blade 34, the noise
generation is reduced when the value of
sin(.beta.-20.degree.)+cos(.gamma.-40.degree.) is in the range of 1
to 1.5.
[0037] FIG. 6 is a graph showing a change in noise level depending
on the outlet angle of the blade. FIG. 7 is a graph showing a
change in noise level depending on the inclination angle of the
blade.
[0038] Referring to FIG. 6, when the outlet angle .beta. of the
blade 34 approaches 90.degree., pressure at the outlet end 344 of
the blade 34 is increased, and thus the level of noise
(blade-passing frequency (BPF) noise) is very high. However, the
noise level is sharply reduced when the outlet angle .beta. is
70.degree. and is maintained at a predetermined level. Meanwhile,
when the outlet angle .beta. is smaller than 20.degree., a
difference in speed between the cooling medium flowing along the
outer surface of the blade 34 and the cooling medium flowing along
the inner surface thereof increases rapidly at the outlet end 344
of the blade 34, and thus the noise level is increased again.
Therefore, in the centrifugal compressor 100 according to the
embodiment, the outlet angle .beta. may have a value in the range
of 20.degree. to 70.degree..
[0039] Referring to FIG. 7, the noise level is maintained at a
predetermined level or a smaller level when the inclination angle
.gamma. of the blade 34 is in the range of 40.degree. to
90.degree.. However, when the inclination angle .gamma. is smaller
than 40.degree., a difference in speed between the cooling medium
flowing along the outer surface of the blade 34 and the cooling
medium flowing along the inner surface thereof is increased, so
that the noise level increases rapidly. Therefore, in the
centrifugal compressor 100 according to the embodiment, the
inclination angle .gamma. may have a value in the range of
40.degree. to 90.degree..
[0040] In the foregoing description, a single-stage centrifugal
compressor has been described. However, this disclosure is not
limited thereto. The number of the stages of the centrifugal
compressor may be changed differently.
[0041] The centrifugal compressor according to the present
disclosure includes the impeller which has an optimal shape based
on the outlet angle and the inclination angle, so that there are
advantages of high reliability in designing and a reduction in
noise of the centrifugal compressor.
[0042] While the exemplary embodiments have been shown and
described, it will be understood by those skilled in the art that
various changes in form and details may be made thereto without
departing from the spirit and scope of this disclosure as defined
by the appended claims.
[0043] In addition, many modifications can be made to adapt a
particular situation or material to the teachings of this
disclosure without departing from the essential scope thereof.
Therefore, it is intended that this disclosure not be limited to
the particular exemplary embodiments disclosed as the best mode
contemplated for carrying out this disclosure, but that this
disclosure will include all embodiments falling within the scope of
the appended claims.
* * * * *