U.S. patent application number 16/491325 was filed with the patent office on 2020-01-30 for impeller and rotary machine.
This patent application is currently assigned to MITSUBISHI HEAVY INDUSTRIES COMPRESSOR CORPORATION. The applicant listed for this patent is MITSUBISHI HEAVY INDUSTRIES COMPRESSOR CORPORATION. Invention is credited to Yuya Konno.
Application Number | 20200032810 16/491325 |
Document ID | / |
Family ID | 63675706 |
Filed Date | 2020-01-30 |
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United States Patent
Application |
20200032810 |
Kind Code |
A1 |
Konno; Yuya |
January 30, 2020 |
IMPELLER AND ROTARY MACHINE
Abstract
An impeller includes: a disc portion fixed to a rotary shaft
that rotates around an axis line; a cover portion disposed to face
the disc portion; and a plurality of blade portions provided
between the disc portion and the cover portion. The impeller
includes a first segment configured of a first disc portion that is
a portion of the disc portion on one side of the axis line, a
second segment in which a second disc portion that is a portion of
the disc portion on another side of the axis line, the cover
portion, and the blade portions are integrally configured, and a
bonding layer configured to bond the first disc portion of the
first segment and the second disc portion of the second segment
with a bonding agent.
Inventors: |
Konno; Yuya; (Tokyo,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
MITSUBISHI HEAVY INDUSTRIES COMPRESSOR CORPORATION |
|
|
|
|
|
Assignee: |
MITSUBISHI HEAVY INDUSTRIES
COMPRESSOR CORPORATION
Tokyo
JP
|
Family ID: |
63675706 |
Appl. No.: |
16/491325 |
Filed: |
March 26, 2018 |
PCT Filed: |
March 26, 2018 |
PCT NO: |
PCT/JP2018/011963 |
371 Date: |
September 5, 2019 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F04D 29/266 20130101;
F05D 2230/23 20130101; F04D 29/284 20130101; F04D 29/023 20130101;
F05D 2300/603 20130101; F04D 29/28 20130101 |
International
Class: |
F04D 29/28 20060101
F04D029/28 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 27, 2017 |
JP |
2017-060409 |
Claims
1. An impeller, comprising: a disc portion fixed to a rotary shaft
that rotates around an axis line; a cover portion disposed to face
the disc portion; and a plurality of blade portions provided
between the disc portion and the cover portion, wherein the
impeller includes a first segment configured of a first disc
portion that is a portion of the disc portion on one side of the
axis line, a second segment in which a second disc portion that is
a portion of the disc portion on another side of the axis line, the
cover portion, and the blade portions are integrally configured,
and a bonding layer configured to bond the first disc portion of
the first segment and the second disc portion of the second segment
with a bonding agent.
2. The impeller according to claim 1, wherein the first segment is
made of a metal material or a fiber-reinforced plastic, and the
second segment is made of a metal material or a fiber-reinforced
plastic.
3. The impeller according to claim 1, wherein the first segment is
made of a metal material, and the second segment is made of a
fiber-reinforced plastic.
4. The impeller according to claim 1, wherein both of the first
segment and the second segment are made of a fiber-reinforced
plastic.
5. The impeller according to claim 1, wherein both of the first
segment and the second segment are made of a metal material.
6. The impeller according to claim 1, wherein the impeller is fixed
to the rotary shaft through the first disc portion of the first
segment.
7. The impeller according to claim 6, wherein the first segment is
made of a metal material and is fitted to the rotary shaft with an
interference.
8. The impeller according to claim 6, wherein the first segment is
made of a fiber-reinforced plastic and is fitted to the rotary
shaft with a bonding agent.
9. The impeller according to claim 1, wherein a film made of a
metallic salt is provided on a surface on which the bonding layer
is to be provided, of each of the first segment and the second
segment each made of a metal material.
10. The impeller according to claim 1, wherein a mechanical fitting
structure is provided between the first disc portion of the first
segment and the second disc portion of the second segment.
11. A rotary machine comprising the impeller according to claim
1.
12. The impeller according to claim 2, wherein the impeller is
fixed to the rotary shaft through the first disc portion of the
first segment.
13. The impeller according to claim 3, wherein the impeller is
fixed to the rotary shaft through the first disc portion of the
first segment.
14. The impeller according to claim 2, wherein a film made of a
metallic salt is provided on a surface on which the bonding layer
is to be provided, of each of the first segment and the second
segment each made of a metal material.
15. The impeller according to claim 2, wherein a mechanical fitting
structure is provided between the first disc portion of the first
segment and the second disc portion of the second segment.
16. A rotary machine comprising the impeller according to claim
2.
17. A rotary machine comprising the impeller according to claim 3.
Description
TECHNICAL FIELD
[0001] The present invention relates to an impeller used in a
rotary machine.
BACKGROUND ART
[0002] For example, a rotary machine such as an industrial
compressor, a turbo refrigerator, and a small gas turbine includes
an impeller in which a plurality of blades are attached to a disc
fixed to a rotary shaft. The rotary machine applies pressure energy
and speed energy to gas through rotation of the impeller.
[0003] As the impeller, a so-called closed impeller in which a
cover is integrally attached to the blades has been well-known. The
closed impeller includes an impeller assembled by bonding a
plurality of members. The impeller including such a bonding
structure tends to be reduced in performance of the impeller
because of low quality of a flow path shape. Patent Literature 1
proposes to configure the impeller as a single piece in order to
address the issue.
[0004] In Patent Literature 1, in the impeller including a disc
portion, blade portions, and a cover portion, the disc portion
includes a first member (first segment) and a second member (second
segment) that are divided at a division surface orthogonal to an
axis line inside the blade portion in the radial direction. Patent
Literature 1 proposes to bond the first segment and the second
segment at the division surface.
[0005] According to the proposition by Patent Literature 1, it is
possible to improve the quality of the flow path shape and to
easily attach/detach the impeller with respect to the rotary
shaft.
CITATION LIST
Patent Literature
[0006] Patent Literature 1: JP 2015-101967 A
SUMMARY OF INVENTION
Technical Problem
[0007] In Patent Literature 1, the first segment and the second
segment are bonded at the division surface by brazing or friction
stir welding. The bonding method is based on the premise that the
first segment and the second segment in Patent Literature 1 are
each made of a metal material. In other words, in Patent Literature
1, a choice of the material to be applied to the first segment and
the second segment is limited.
[0008] Accordingly, an object of the present invention is to
provide an impeller and a rotary machine that make it possible to
expand a range of choices of a material to be applied to the first
segment and the second segment.
Solution to Problem
[0009] An impeller according to the present invention includes a
disc portion fixed to a rotary shaft that rotates around an axis
line, a cover portion disposed to face the disc portion; and a
plurality of blade portions provided between the disc portion and
the cover portion.
[0010] The impeller according to the present invention includes a
first segment configured of a first disc portion that is a portion
of the disc portion on one side of the axis line; a second segment
in which a second disc portion that is a portion of the disc
portion on another side of the axis line, the cover portion, and
the blade portions are integrally configured; and a bonding layer
configured to bond the first disc portion of the first segment and
the second disc portion of the second segment with a bonding
agent.
[0011] In the impeller according to the present invention, the
first disc portion of the first segment and the second disc portion
of the second segment are bonded with the bonding agent.
Accordingly, the range of choices of the material of the first
segment and the second segment is expanded to include a
fiber-reinforced plastic without being limited to a metal material.
In other words, in the impeller according to the present invention,
the first segment can be made of a metal material or a
fiber-reinforced plastic, and the second segment can be made of a
metal material or a fiber-reinforced plastic.
[0012] In the impeller according to the present invention, the
first segment can be made of a metal material, and the second
segment can be made of a fiber-reinforced plastic, as a specific
choice of the material.
[0013] Further, in the impeller according to the present invention,
both of the first segment and the second segment can be made of a
fiber-reinforced plastic.
[0014] Further, in the impeller according to the present invention,
both of the first segment and the second segment can be made of a
metal material.
[0015] The impeller according to the present invention can be fixed
to the rotary shaft through the first disc portion of the first
segment.
[0016] In a case where the first segment is made of a metal
material, the first segment can be fitted to the rotary shaft with
an interference.
[0017] In a case where the first segment is made of a
fiber-reinforced plastic, the first segment can be fitted to the
rotary shaft with a bonding agent.
[0018] In the impeller according to the present invention, in a
case where both of the first segment and the second segment are
made of a metal material, a film made of metallic salt is
preferably provided on a surface on which the bonding layer is to
be provided.
[0019] Further, in the impeller according to the present invention,
a mechanical fitting structure is preferably provided between the
first disc portion of the first segment and the second disc portion
of the second segment.
[0020] The present invention also provides a rotary machine
including any of the above-described impellers.
Advantageous Effects of Invention
[0021] In the impeller according to the present invention, the
first segment and the second segment are bonded with the bonding
agent layer. Thus, according to the present invention, the material
configuring the first segment and the second segment is selectable
without being limited to a metal material, which expands the range
of material choices. Therefore, for example, the fiber-reinforced
plastic that is lower in weight than the metal material can be used
for the first segment or the second segment. Thus, according to the
present invention, it is possible to reduce the weight of the
impeller as compared with a case where the impeller is wholly
fabricated from a metal material.
BRIEF DESCRIPTION OF DRAWINGS
[0022] FIG. 1 is a cross-sectional view illustrating a centrifugal
compressor according to a first embodiment of the present
invention.
[0023] FIG. 2 is a perspective view illustrating an impeller
according to the first embodiment.
[0024] FIG. 3 is a half cross-sectional view illustrating the
impeller according to the first embodiment.
[0025] FIGS. 4A to 4C are cross-sectional views illustrating a
procedure of manufacturing the impeller according to the first
embodiment.
[0026] FIG. 5 is a flowchart illustrating the procedure of
manufacturing the impeller according to the first embodiment.
[0027] FIG. 6 is a cross-sectional view illustrating an impeller
according to a second embodiment.
[0028] FIGS. 7A to 7C are cross-sectional views illustrating a
procedure of manufacturing the impeller according to the second
embodiment.
[0029] FIG. 8 is a flowchart illustrating the procedure of
manufacturing the impeller according to the second embodiment.
[0030] FIGS. 9A and 9B are cross-sectional views illustrating an
impeller according to a modification of each of the first
embodiment and the second embodiment.
DESCRIPTION OF EMBODIMENTS
First Embodiment
[0031] A centrifugal compressor 100 that is an example of a rotary
machine according to a first embodiment of the present invention is
described below with reference to accompanying drawings.
Configuration of Centrifugal Compressor 100
[0032] As illustrated in FIG. 1, the centrifugal compressor 100
according to the first embodiment includes a casing 102 and a
rotary shaft 101 that is supported by the casing 102 through a
journal bearing 103 and a thrust bearing 104. The rotary shaft 101
is supported so as to be rotatable around an axis line O, and a
plurality of impellers 1 that are arranged in the axis line O
direction are attached to the rotary shaft 101.
[0033] As illustrated in FIG. 2, each of the impellers 1 compresses
gas G that is sucked from a suction port 3 while the gas G passes
through a flow path 105 provided inside the impeller 1. The suction
port 3 opens on one side in the axis line O direction. Each of the
impellers 1 discharges the compressed gas G from a discharge port 4
toward outside in a radial direction.
[0034] The impellers 1 use centrifugal force derived from rotation
of the rotary shaft 101 to stepwisely compress the gas G supplied
from the flow path 105 on upstream side provided in the casing 102,
and cause the compressed gas G to flow toward the flow path 105 on
downstream side.
[0035] As illustrated in FIG. 1, the casing 102 includes, on front
side (F) in the axis line O direction of the rotary shaft 101, a
suction port 106 to take in the gas G from the outside. Further,
the casing 102 includes, on rear side (R) in the axis line O
direction, a discharge port 107 that causes the gas G to flow out
to the outside.
[0036] In the centrifugal compressor 100, when the rotary shaft 101
rotates, the gas G flows into the flow path 105 from the suction
port 106, the gas G is stepwisely compressed by the impellers 1,
and the compressed gas G is discharged from the discharge port 107.
FIG. 1 illustrates an example in which six impellers 1 are provided
in series on the rotary shaft 101; however, it is sufficient to
provide at least one impeller 1 on the rotary shaft 101. Note that,
in the following description, a case where only one impeller 1 is
provided on the rotary shaft 101 is described as an example, to
simplify the description.
Configuration of Impeller 1
[0037] As illustrated in FIG. 2 and FIG. 3, the impeller 1 includes
a disc portion 30, blade portions 40, and a cover portion 50.
[0038] The disc portion 30 is attached to the rotary shaft 101 by
being fitted to the rotary shaft 101 from outside in the radial
direction. As illustrated in FIG. 3, the disc portion 30 includes a
first disc portion 31 and a second disc portion 35 that are divided
in the axis line O direction at a bonding layer BL orthogonal to
the axis line O. The first disc portion 31 and the second disc
portion 35 are bonded with the bonding layer BL.
[0039] The first disc portion 31 includes a substantially
cylindrical shape with the axis line O as a center. The first disc
portion 31 includes, at the front end part 33 side on the front
side (F) of the axis line O, a grip part A that is fitted to the
rotary shaft 101 with an interference. At this time, to fit the
first disc portion 31 to the rotary shaft 101 with the interference
at the grip part A, cold fitting or shrink fitting is adoptable.
The impeller 1 according to the present embodiment is fixed to the
rotary shaft 101 at only the grip part A.
[0040] The first disc portion 31 includes an outer peripheral
surface 34 that is gradually increased in diameter toward the rear
side (R) of the axis line O. The outer peripheral surface 34 has a
curved surface recessed outward in a cross-section including the
axis line O.
[0041] A rear end surface 32 of the first disc portion 31 on the
rear side (R) of the axis line O is bonded to the second disc
portion 35 with the bonding layer BL containing a bonding
agent.
[0042] The second disc portion 35 includes a disc shape that
extends outward in the radial direction from a rear end part 36
side that is opposite to the front end part 33 side in the axis
line O direction.
[0043] An inner-diameter-side region 38 on a front end surface 37
of the second disc portion 35 is bonded to the rear end surface 32
of the first disc portion 31 with the bonding layer BL. The rear
end surface 32 and the inner-diameter-side region 38 of the front
end surface 37 configure the bonding layer BL orthogonal to the
axis line O.
[0044] An epoxy resin bonding agent, an anaerobic strong sealant,
or the like is applied to the bonding layer BL. Note that, when the
impeller 1 is assumed to be exposed to temperature of, for example,
about 200.degree. C., it is necessary for the bonding agent to be
applied to have heat resistance of 200.degree. C.
[0045] As illustrated in FIG. 2, the plurality of blade portions 40
are arranged at predetermined intervals in a circumferential
direction of the disc portion 30.
[0046] As illustrated in FIG. 3, each of the blade portions 40 is
formed to have a substantially constant plate thickness, and
protrudes from the front end surface 37 of the disc portion 30
toward the front side (F) in the axis line O direction. Further,
each of the blade portions 40 has a slightly tapered shape toward
the outside in the radial direction in a side view.
[0047] As illustrated in FIG. 2, each of the blade portions 40 is
formed so as to be directed to rear side in a rotation direction R
of the impeller 1 as going toward the outside in the radial
direction of the disc portion 30 as viewed from the axis line O
direction. Further, each of the blade portions 40 is formed so as
to be curved in a recessed shape toward the rear side in the
rotation direction R as viewed from the axis line O direction. The
example in which each of the blade portions 40 is curved as viewed
from the axis line O direction has been described here; however, it
is sufficient for each of the blade portions 40 to extend to the
rear side in the rotation direction R as being closer to the
outside in the radial direction. For example, each of the blade
portions 40 may be linearly formed as viewed from the axis line O
direction.
[0048] As illustrated in FIG. 3, the cover portion 50 is disposed
to face the disc portion 30, and covers the blade portions 40 from
the front end part 33 side in the axis line O direction.
[0049] A rear end surface 52 of the cover portion 50 in the axis
line O direction is formed integrally with front side edges 41 of
the respective blade portions 40. The cover portion 50 is formed in
a plate shape in which a thickness dimension on the outside in the
radial direction is slightly small, as with the thickness dimension
of the disc portion 30. The cover portion 50 includes a bent part
51 that is bent toward the front side in the axis line O direction
at positions of inside ends 42 of the respective blade portions
40.
[0050] The impeller 1 including the above-described configuration
includes the bonding layer BL that is disposed on the inside in the
radial direction of the blade portions 40. Further, the front end
part 33 of the first disc portion 31 is disposed to protrude toward
the front side (F) in the axis line O direction more than a front
end edge 53 of the bent part 51. Moreover, in the impeller 1, the
flow path 105 through which the gas G flows is formed by the outer
peripheral surface 34 of the first disc portion 31, the front end
surface 37 of the second disc portion 35, side surfaces 43 of the
blade portions 40, and a rear end surface 52 of the cover portion
50.
[0051] The impeller 1 includes a first segment SG1 and a second
segment SG2. The first segment SG1 includes the first disc portion
31 that is a portion of the disc portion 30 on one side of the axis
line O. Further, the second segment SG2 includes the second disc
portion 35 that is a portion of the disc portion 30 on the other
side of the axis line O, the blade portions 40, and the cover
portion 50.
[0052] In the impeller 1 according to the first embodiment, the
first segment SG1 is made of a metal material such as precipitation
hardening stainless steel, whereas the second segment SG2 is made
of fiber-reinforced plastic (FRP). As the reinforcing fiber, for
example, carbon fiber or glass fiber is used. In particular, carbon
fiber-reinforced plastic (CFRP) that includes the carbon fiber as
the reinforcing fiber is high in strength and elasticity and is
excellent in corrosion resistance, as compared with the other
FRPs.
Method of Manufacturing Impeller 1
[0053] Next, a method of manufacturing the above-described impeller
1 is described with reference to FIGS. 4A-4C and FIG. 5.
[0054] First, the first segment SG1 is fabricated by casting,
cutting, or the like (FIG. 4A and step S101 in FIG. 5).
[0055] In addition, the second segment SG2 in which the second disc
portion 35, the blade portions 40, and the cover portion 50 are
integrated is fabricated (FIG. 4A and step S103 in FIG. 5). The
second segment SG2 made of the fiber-reinforced plastic is
integrally fabricated by injection molding.
[0056] Note that the first segment SG1 and the second segment SG2
are fabricated in this order for convenience; however, the first
segment SG1 and the second segment SG2 may be fabricated in reverse
order.
[0057] Next, the first segment SG1 (first disc portion 31) is
fitted to and fixed to the rotary shaft 101 (FIG. 4B and step S105
in FIG. 5). The fitting can be performed by shrink fitting. In the
shrink fitting, the first segment SG1 is heated to cause thermal
expansion in the radial direction, and the thermally-expanded first
segment SG1 is fitted to the rotary shaft 101. After the first
segment SG1 is cooled to the room temperature, the first segment
SG1 and the rotary shaft 101 are fitted to each other with an
interference.
[0058] Next, a bonding agent B is applied on the rear end surface
32 of the first segment SG1 (first disc portion 31) fitted to the
rotary shaft 101 and on the front end surface 37
(inner-diameter-side region 38) of the second segment SG2 (second
disc portion 35) that has been separately fabricated (FIG. 4B and
step S107 in FIG. 5). Note that the bonding agent B may be applied
on any one of the rear end surface 32 and the front end surface
37.
[0059] After the bonding agent B is applied on the rear end surface
32 and the front end surface 37, the second segment SG2 is fitted
to the rotary shaft 101 and is then pushed in until the rear end
surface 32 of the first segment SG1 and the front end surface 37
abut on each other. The first segment SG1 and the second segment
SG2 are held while a load is applied between the rear end surface
32 and the front end surface 37 until the bonding agent B is cured.
As a result, bonding of the first segment SG1 and the second
segment SG2 is completed (FIG. 4C and step S109 in FIG. 5).
Effects of First Embodiment
[0060] In the impeller 1, the first segment SG1 and the second
segment SG2 are bonded with the bonding agent. As a result, a range
of choices of the material to be applied to the second segment SG2
is expanded, and the second segment SG2 can be fabricated from the
fiber-reinforced plastic that has a light weight as compared with a
metal material. Accordingly, the weight reduction of the impeller 1
is achieved as compared with the case where the whole body is
fabricated from a metal material. Thus, according to the present
embodiment, it is possible to provide the high-efficiency
centrifugal compressor 100.
[0061] In addition, in the impeller 1, the first disc portion 31
that is the first segment SG1 is made of the metal material.
Therefore, the first disc portion 31 can be fitted to the rotary
shaft 101 with necessary strength only by performing, for example,
shrink fitting with an interference. Thus, the impeller 1 does not
require a mechanical fitting structure such as a key and a key
groove, which facilitates manufacture of the impeller 1.
[0062] In addition, the bonding layer BL formed by the bonding
agent on each of the first segment SG1 and the second segment SG2
can be maintained through bonding of the rear end surface 32 and
the front end surface 37 each on which the bonding agent has been
applied, in the atmosphere. Accordingly, the first embodiment
facilitates the bonding work as compared with brazing that uses
heat treatment furnace in which temperature is controlled in
vacuum.
[0063] In addition, in the case of the brazing, the work from
charge of the impeller in the heat treatment furnace to completion
of the brazing takes few days. In contrast, bonding with the
bonding agent from application to curing takes only one day. Thus,
according to the present embodiment, it is possible to manufacture
the impeller 1 in a short time.
[0064] Further, the bonding with the bonding agent can be performed
at ambient temperature without heating. Therefore, deformation of
the impeller 1 due to heat does not occur. Thus, according to the
present embodiment, it is possible to provide the impeller 1 with
high accuracy in shape and dimension.
[0065] In addition, the bonding with the bonding agent is
performable in the atmosphere. Therefore, the bonding condition is
finely correctable before curing. Thus, the impeller 1 according to
the present embodiment is higher in accuracy of the shape and the
dimension.
Second Embodiment
[0066] Next, a second embodiment of the present invention is
described.
[0067] An impeller 2 according to the second embodiment is
different from the impeller 1 according to the first embodiment in
that the first disc portion 31 configuring the first segment SG1 is
also made of the fiber-reinforced plastic, in addition to the
second segment SG2. The impeller 2 is described below with
reference to FIG. 6 while focusing on differences with the impeller
1. Note that, in FIG. 6, configurations and components similar to
those of the impeller 1 are denoted by the same reference numerals
as the impeller 1.
[0068] In the impeller 2, the first disc portion 31 made of the
fiber-reinforced plastic is fixed to the rotary shaft 101 with the
bonding agent. To complement fixing strength by the bonding agent,
in the impeller 2, the rotary shaft 101 and the first disc portion
31 respectively include key grooves S1 and S2, and a key K is
inserted into the key grooves S1 and S2. The key grooves S1 and S2
and the key K can be provided, for example, at a part corresponding
to the grip part A. A part between the rotary shaft 101 and the
first disc portion 31 other than the part where the key grooves S1
and S2 and the key K are provided is bonded by the bonding agent
B.
[0069] In the impeller 2, the first disc portion 31 is bonded to
the rotary shaft 101 with the bonding agent at the grip part A. The
second segment SG2 is bonded, with the bonding layer BL, to the
first segment SG1 that includes the first disc portion 31 fixed to
the rotary shaft 101 with the bonding agent. The bonding is similar
to the bonding in the impeller 1 according to the first
embodiment.
Method of Manufacturing Impeller 2
[0070] Next, a method of manufacturing the impeller 2 is described
with reference to FIGS. 7A-7C and FIG. 8.
[0071] First, the first disc portion 31 configuring the first
segment SG1 is fabricated by injection molding with use of the
fiber-reinforced plastic (step S201 in FIG. 8). The key groove S2
is previously formed on an inner periphery of the first disc
portion 31.
[0072] In addition, the second segment SG2 in which the second disc
portion 35, the blade portions 40, and the cover portion 50 are
integrated is integrally fabricated by injection molding with use
of the fiber-reinforced plastic (step S203 in FIG. 8).
[0073] Next, the first segment SG1 (first disc portion 31) is
fitted to the rotary shaft 101 (FIG. 7A and step S205 in FIG.
8).
[0074] The key groove S1 is previously provided in the rotary shaft
101 and the key K has been inserted into the key groove S1. In
addition, the bonding agent B has been applied on the outer
peripheral surface of the first disc portion 31 corresponding to
the grip part A.
[0075] The first segment SG1 is fitted to the rotary shaft 101 such
that the key K is inserted into the key groove S2. When the key K
is pushed in until abutting on an innermost part of the key groove
S2 (right side in figure), the fitting work of the first disc
portion 31 and the rotary shaft 101 ends.
[0076] Note that the key K can be previously fixed to the key
groove S1 of the rotary shaft 101 with the bonding agent.
[0077] Further, the fixing of the first disc portion 31 and the
rotary shaft 101 with the bonding agent may be performed only at
the part of the key grooves S1 and S2 and the key K as long as the
bonding strength is sufficient.
[0078] The subsequent bonding of the first segment SG1 (first disc
portion 31) and the second segment SG2 (second disc portion 35)
with the bonding agent is similar to the bonding according to the
first embodiment (FIG. 7C and steps S207 and S209 in FIG. 8).
Effects of Second Embodiment
[0079] The impeller 2 according to the second embodiment uses the
first segment SG1 (first disc portion 31) made of the
fiber-reinforced plastic. Thus, according to the second embodiment,
further weight reduction of the impeller 2 is achieved, which makes
it possible to provide the high-efficiency centrifugal compressor
100.
[0080] In addition, the second embodiment does not require heating
to bond the first segment SG1 and the second segment SG2 to the
rotary shaft 101. Therefore, the bonding work is easier than the
bonding work in the first embodiment.
[0081] In addition, as compared with the case where the first disc
portion 31 is fitted to the rotary shaft 101 by, for example, the
shrink fitting, the time necessary for bonding of the first disc
portion 31 and the rotary shaft 101 with the bonding agent is
short. Thus, according to the second embodiment, it is possible to
manufacture the impeller 2 in a time shorter than the first
embodiment.
[0082] Although the preferred embodiments of the present invention
have been described above, the configurations described in the
above-described embodiments may be selected or appropriately
modified in addition to the above description without departing
from the scope of the present invention.
[0083] In the first embodiment and the second embodiment, at least
one of the first segment SG1 and the second segment SG2 is
fabricated from the fiber-reinforced plastic. The present
invention, however, is not limited thereto, and both of the first
segment SG1 and the second segment SG2 may be fabricated from a
metal material. In other words, the present invention includes a
choice in which the first segment SG1 is formed from a metal
material or a fiber-reinforced plastic and the second segment SG2
is formed from a metal material or a fiber-reinforced plastic.
[0084] The present invention can adopt means for enhancing strength
of the bonding between the first segment SG1 and the second segment
SG2 with the bonding layer BL.
[0085] For example, in a case where both of the first segment SG1
and the second segment SG2 are made of an iron-based metal
material, phosphate treatment can be performed on the rear end
surface 32 and the front end surface 37 on which the bonding agent
is to be applied. A thin film of metallic salt such as zinc
phosphate with micron order is formed on the metal surface by the
phosphate treatment. The surface is roughened because the film has
a columnar shape, which increases the bonding strength of the
bonding agent.
[0086] As the phosphate treatment, zinc phosphate treatment,
calcium phosphate treatment, and iron phosphate treatment are
well-known. The zinc phosphate treatment that is performable even
at the ambient temperature is preferable.
[0087] Further, to enhance the bonding strength between the first
disc portion 31 of the first segment SG1 and the second disc
portion 35 of the second segment SG2, a mechanical fitting
structure may be provided between the first disc portion 31 and the
second disc portion 35.
[0088] For example, as illustrated in FIGS. 9A and 9B, a fitting
structure 39 includes a recess 39A provided on the rear end surface
32 of the first disc portion 31 and a protrusion 39B provided on
the front end surface 37 of the second disc portion 35. The
protrusion 39B is inserted into the recess 39A to configure the
fitting structure 39.
[0089] The fitting structure 39 is provided at each of four
positions with an interval of 90 degrees in the circumferential
direction of the first disc portion 31 and the second disc portion
35.
[0090] In addition, in the impellers 1 and 2 of the embodiments, a
boundary surface between the first disc portion 31 and the second
disc portion 35 extends along a direction orthogonal to the axis
line O; however, the present invention is not limited thereto, and
the boundary surface may be inclined with respect to the axis line
O.
REFERENCE SIGNS LIST
[0091] 1, 2 Impeller [0092] 3 Suction port [0093] 4 Discharge port
[0094] 30 Disc portion [0095] 31 First disc portion [0096] 32 Rear
end surface [0097] 33 Front end part [0098] 34 Outer peripheral
surface [0099] 35 Second disc portion [0100] 36 Rear end part
[0101] 37 Front end surface [0102] 38 Inner-diameter-side region
[0103] 39 Fitting structure [0104] 39A Recess [0105] 39B Protrusion
[0106] 40 Blade portion [0107] 41 Front side edge [0108] 42 Inside
end [0109] 43 Side surface [0110] 50 Cover portion [0111] 51 Bent
part [0112] 52 Rear end surface [0113] 53 Front end edge [0114] 100
Centrifugal compressor [0115] 101 Rotary shaft [0116] 102 Casing
[0117] 103 Journal bearing [0118] 104 Thrust bearing [0119] 105
Flow path [0120] 106 Suction port [0121] 107 Discharge port [0122]
A Grip part [0123] B Bonding agent [0124] BL Bonding layer [0125] K
Key [0126] S1, S2 Key groove [0127] SG1 First segment [0128] SG2
Second segment [0129] O Axis line [0130] R Rotation direction
[0131] G Gas
* * * * *