U.S. patent application number 15/768922 was filed with the patent office on 2019-02-21 for centrifugal compressor.
This patent application is currently assigned to KABUSHIKI KAISHA TOYOTA JIDOSHOKKI. The applicant listed for this patent is KABUSHIKI KAISHA TOYOTA JIDOSHOKKI. Invention is credited to Satoru EGAWA, Toshiro FUJII, Nobuaki HOSHINO, Takahito KUNIEDA, Hironao YOKOI.
Application Number | 20190055954 15/768922 |
Document ID | / |
Family ID | 58557014 |
Filed Date | 2019-02-21 |
United States Patent
Application |
20190055954 |
Kind Code |
A1 |
EGAWA; Satoru ; et
al. |
February 21, 2019 |
CENTRIFUGAL COMPRESSOR
Abstract
A centrifugal compressor includes a rotary shaft, an electric
motor, which has a rotor, a tubular boss, through which the rotary
shaft extends, and a radial bearing. The rotor has a rotor end
face, which is an end face in an axial direction of the rotary
shaft. The boss has a boss end face, which is an end face in the
axial direction of the rotary shaft. The rotor end face and the
boss end face face each other in the axial direction of the rotary
shaft. A thrust bearing is arranged between the rotor end face and
the boss end face to receive thrust force generated by rotation of
the impeller.
Inventors: |
EGAWA; Satoru; (Kariya-shi,
JP) ; HOSHINO; Nobuaki; (Kariya-shi, JP) ;
FUJII; Toshiro; (Kariya-shi, JP) ; YOKOI;
Hironao; (Kariya-shi, JP) ; KUNIEDA; Takahito;
(Kariya-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
KABUSHIKI KAISHA TOYOTA JIDOSHOKKI |
Kariya-shi, Aichi-ken |
|
JP |
|
|
Assignee: |
KABUSHIKI KAISHA TOYOTA
JIDOSHOKKI
Kariya-shi, Aichi-ken
JP
|
Family ID: |
58557014 |
Appl. No.: |
15/768922 |
Filed: |
October 18, 2016 |
PCT Filed: |
October 18, 2016 |
PCT NO: |
PCT/JP2016/080860 |
371 Date: |
April 17, 2018 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F04D 29/5806 20130101;
F04D 29/057 20130101; F04D 29/0513 20130101; F04D 25/0606 20130101;
F04D 25/06 20130101; F04D 17/125 20130101; F04D 17/10 20130101 |
International
Class: |
F04D 29/051 20060101
F04D029/051; F04D 17/10 20060101 F04D017/10; F04D 25/06 20060101
F04D025/06 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 20, 2015 |
JP |
2015-206507 |
Claims
1. A centrifugal compressor comprising: a rotary shaft; an electric
motor, which includes a rotor attached to the rotary shaft and
rotates the rotary shaft; an impeller, which rotates as the rotary
shaft rotates, thereby compressing fluid; a housing, which
accommodates the rotary shaft, the electric motor, and the
impeller; a tubular boss, which is provided in the housing and
through which the rotary shaft extends; and a radial bearing, which
is provided between the boss and the rotary shaft and rotationally
supports the rotary shaft, wherein the rotor has a rotor end face,
which is an end face in an axial direction of the rotary shaft, the
boss has a boss end face, which is an end face in the axial
direction of the rotary shaft, the rotor end face and the boss end
face face each other in the axial direction of the rotary shaft,
and the centrifugal compressor comprises a thrust bearing, which is
arranged between the rotor end face and the boss end face and
receives thrust force generated by rotation of the impeller.
2. The centrifugal compressor according to claim 1, wherein the
boss is a first boss, the centrifugal compressor further comprises
a second boss, which makes a pair with the first boss, the first
boss and the second boss are arranged to face each other in the
axial direction of the rotary shaft with the rotor in between, the
rotor has a first rotor end face as the rotor end face and a second
rotor end face, which is located on a side opposite to the first
rotor end face in the axial direction of the rotary shaft, the
first boss has a first boss end face as the boss end face, the
first boss end face and the first rotor end face facing each other
in the axial direction of the rotary shaft, the second boss has a
second boss end face as the boss end face, the second boss end face
and the second rotor end face facing each other in the axial
direction of the rotary shaft, the thrust bearing is a first thrust
bearing provided between the first rotor end face and the first
boss end face, and the centrifugal compressor further comprises a
second thrust bearing provided between the second rotor end face
and the second boss end face.
3. The centrifugal compressor according to claim 2, wherein the
rotor includes a plurality of magnetic steel sheets, which is
laminated in the axial direction of the rotary shaft, first and
second holding plates, which hold the magnetic steel sheets in
between in the axial direction of the rotary shaft, a rivet, which
includes a barrel and first and second heads, wherein the barrel is
inserted through the magnetic steel sheets and the first and second
holding plates, and the first and second heads have a diameter
greater than that of the barrel and are arranged at opposite ends
of the barrel in the axial direction of the rotary shaft, a first
spacer, which has a first contact surface contacting a plate
surface of the first holding plate, the first rotor end face, which
is arranged on a side opposite to the first contact surface, and a
first accommodating portion, which accommodates the first head, and
a second spacer, which has a second contact surface contacting a
plate surface of the second holding plate, the second rotor end
face, which is arranged on a side opposite to the second contact
surface, and a second accommodating portion, which accommodates the
second head.
4. The centrifugal compressor according to claim 3, wherein the
first thrust bearing is a non-contact type hydrodynamic bearing,
which receives the thrust force in a non-contact state in which
hydrodynamic pressure generated by rotation of the rotor creates a
clearance between the first thrust bearing and the first rotor end
face, the second thrust bearing is a non-contact type hydrodynamic
bearing, which receives the thrust force in a non-contact state in
which hydrodynamic pressure generated by rotation of the rotor
creates a clearance between the second thrust bearing and the
second rotor end face, and the first rotor end face and the second
rotor end face are smoother than the plate surfaces of the first
and second holding plates.
5. The centrifugal compressor according to claim 1, wherein the
thrust bearing includes a thrust top foil, which is arranged
between the boss end face and the rotor end face at a position
closer to the rotor end face than to the boss end face and supports
the rotor in a non-contact state when the rotary shaft rotates, and
a thrust bump foil, which is arranged between the boss end face and
the rotor end face at a position closer to the boss end face than
to the rotor end face and is elastically deformed to support the
thrust top foil in a displaceable manner in the axial direction of
the rotary shaft.
6. The centrifugal compressor according to claim 5, wherein the
radial bearing includes a radial top foil, which is arranged
outward of an outer circumferential surface of the rotary shaft in
a radial direction of the rotary shaft and supports the rotary
shaft in a non-contact state when the rotary shaft rotates, and a
radial bump foil, which is arranged outward of the radial top foil
in the radial direction of the rotary shaft and elastically
supports the radial top foil, wherein the thrust bearing has a
shape of a loop having an inner diameter longer than a diameter of
the rotary shaft, a space is provided inward of the thrust bearing
in the radial direction of the rotary shaft, and the space causes a
radial clearance, which is provided between the radial top foil and
the radial bump foil, and a thrust clearance, which is provided
between the thrust top foil and the thrust bump foil, to
communicate with each other.
7. The centrifugal compressor according to claim 1, further
comprising: a drive circuit, which drives the electric motor; and a
circuit case, which defines a circuit chamber that accommodates the
drive circuit and is attached to the housing from the axial
direction of the rotary shaft, wherein the housing includes a motor
chamber, which accommodates the electric motor and into which fluid
is drawn, and a partition wall, which partitions the motor chamber
and the circuit chamber from each other, and the drive circuit
exchanges heat with the fluid in the motor chamber via the
partition wall.
8. The centrifugal compressor according to claim 6, wherein an
inner edge of the thrust bearing protrudes further inward than an
inner circumferential surface of the boss in the radial direction
of the rotary shaft.
Description
TECHNICAL FIELD
[0001] The present invention relates to a centrifugal
compressor.
BACKGROUND ART
[0002] A centrifugal compressor includes, for example, a rotary
shaft, an electric motor that rotates the rotary shaft, an impeller
that compresses fluid by rotating with the rotation of the rotary
shaft, a housing that accommodates the rotary shaft, the electric
motor, and the impeller. For example, refer to Patent Document 1.
Patent Document 1 also describes that a centrifugal compressor has
a flange portion as a thrust liner, which integrally rotates with
the rotary shaft, and two thrust bearings, which hold the flange
portion in between.
PRIOR ART DOCUMENT
Patent Document
[0003] Patent Document 1: Japanese Laid-Open Patent Publication No.
2009-257165
SUMMARY OF THE INVENTION
Problems that the Invention is to Solve
[0004] Since the thrust liner rotates as the rotary shaft rotates,
windage loss occurs at the thrust liner. For this reason, there is
a concern that the efficiency of the centrifugal compressor will be
degraded.
[0005] Accordingly, it is an objective of the present invention to
provide a centrifugal compressor that is capable of improving
efficiency.
Means for Solving the Problems
[0006] To achieve the foregoing objective, a centrifugal compressor
is provided that includes a rotary shaft, an electric motor, which
includes a rotor attached to the rotary shaft and rotates the
rotary shaft, an impeller, which rotates as the rotary shaft
rotates, thereby compressing fluid, a housing, which accommodates
the rotary shaft, the electric motor, and the impeller, a tubular
boss, which is provided in the housing and through which the rotary
shaft extends, and a radial bearing, which is provided between the
boss and the rotary shaft and rotationally supports the rotary
shaft. The rotor has a rotor end face, which is an end face in an
axial direction of the rotary shaft. The boss has a boss end face,
which is an end face in the axial direction of the rotary shaft.
The rotor end face and the boss end face face each other in the
axial direction of the rotary shaft. The centrifugal compressor
includes a thrust bearing, which is arranged between the rotor end
face and the boss end face and receives thrust force generated by
rotation of the impeller.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] FIG. 1 is a cross-sectional view schematically illustrating
a centrifugal compressor and a vehicle air conditioner.
[0008] FIG. 2 is an enlarged cross-sectional view showing the rotor
and the thrust bearing.
[0009] FIG. 3 is a cross-sectional view schematically illustrating
a vehicle air conditioner according to a modification.
MODES FOR CARRYING OUT THE INVENTION
[0010] Hereinafter, a centrifugal compressor according to one
embodiment will be described with reference to the drawings. In the
present embodiment, the centrifugal compressor is mounted in a
vehicle. For the illustrative purposes, a rotary shaft 12 is shown
in the side view in FIGS. 1 to 3. Also, for the illustrative
purposes, the thicknesses of magnetic steel sheets 51, holding
plates 52, 53, spacers 55, 56, and thrust bearings 91, 92 are shown
to be different from the actual dimensions.
[0011] As shown in FIG. 1, a centrifugal compressor 10 has a
housing 11, which constitutes the outer shell thereof. The housing
11 has a substantially cylindrical shape as a whole. The housing 11
is made of a material having heat conductivity such as metal.
[0012] The centrifugal compressor 10 includes, as components
accommodated in the housing 11, a rotary shaft 12, an electric
motor 13, which rotates the rotary shaft 12, and first and second
impellers 14, 15, which are attached to the rotary shaft 12. The
rotary shaft 12 has a main body 12a and a distal end portion 12b,
which has a smaller diameter than the main body 12a and to which
the first and second impellers 14, 15 are attached.
[0013] The housing 11 includes a front housing member 20. The front
housing member 20 defines first and second impeller chambers A1,
A2, which respectively accommodate the first and second impellers
14, 15. The front housing member 20 is composed of three parts 21
to 23. The parts 21 to 23 are unitized by holding the middle part
23 in between by the first part 21 and the second part 22 in the
axial direction Z of the rotary shaft 12.
[0014] The first part 21 substantially has a tubular shape having a
first compressor through-hole 21a, which extends in the axial
direction Z through the rotary shaft 12. The first part 21 has
first and second end faces 21b, 21c, which are positioned on the
opposite sides in the axial direction Z of the rotary shaft 12. The
first compressor through-hole 21a opens in the first and second end
faces 21b, 21c of the first part 21. The first end face 21b of the
first part 21 contacts the middle part 23. The first compressor
through-hole 21a is shaped as a truncated cone the diameter of
which gradually decreases from the opening in the first end face
21b to an intermediate position in the axial direction Z of the
rotary shaft 12. The first compressor through-hole 21a has a
columnar shape the diameter of which is constant from the
intermediate position to the opening in the second end face
21c.
[0015] The second part 22 substantially has a tubular shape the
axial direction of which coincides with the axial direction Z of
the rotary shaft 12. The second part 22 has first and second end
faces 22a, 22b, which are positioned on the opposite sides in the
axial direction Z of the rotary shaft 12. The first end face 22a of
the second part 22 contacts the middle part 23. A recess 22c is
provided in the second end face 22b. A second compressor
through-hole 22d is provided in the bottom of the recess 22c. The
second compressor through-hole 22d extends in the axial direction Z
of the rotary shaft 12 through the bottom of the recess 22c. The
second compressor through-hole 22d is shaped as a truncated cone
the diameter of which gradually decreases from the opening that
faces the middle part 23 to an intermediate position in the axial
direction Z of the rotary shaft 12. The second compressor
through-hole 22d has a columnar shape the diameter of which is
constant from the intermediate position to the opening of the
middle part 23.
[0016] The middle part 23 is substantially shaped as a disc the
thickness direction of which coincides with the axial direction Z
of the rotary shaft 12. The middle part 23 has a first middle part
end face 23a and a second middle part end face 23b. The first
middle part end face 23a contacts the first end face 21b of the
first part 21. The second middle part end face 23b is located on
the opposite side to the first middle part end face 23a and
contacts the first end face 22a of the second part 22. The inner
surface of the first compressor through-hole 21a and the first
middle part end face 23a define a first impeller chamber A1. The
inner surface of the second compressor through-hole 22d and the
second middle part end face 23b define a second impeller chamber
A2. That is, the middle part 23 partitions the first impeller
chamber A1 and the second impeller chamber A2 from each other.
[0017] The middle part 23 has a middle part through-hole 23c,
through which the rotary shaft 12 is inserted. The distal end
portion 12b of the rotary shaft 12 is arranged to extend through
the middle part through-hole 23c and is arranged across the two
impeller chambers A1, A2. A first impeller 14 is attached to part
of the distal end portion 12b of the rotary shaft 12 that is
arranged in the first impeller chamber A1. A second impeller 15 is
attached to part of the distal end portion 12b of the rotary shaft
12 that is arranged in the second impeller chamber A2.
[0018] The first impeller 14 is substantially shaped as a truncated
cone the diameter of which gradually decreases from a proximal end
face 14a toward a distal end face 14b and is arranged in the first
impeller chamber A1 along the inner surface of the first compressor
through-hole 21a. Likewise, the second impeller 15 is substantially
shaped as a truncated cone the diameter of which gradually
decreases from a proximal end face 15a toward a distal end face 15b
and is arranged in the second impeller chamber A2 along the inner
surface of the second compressor through-hole 22d. The proximal end
faces 14a, 15a of the impellers 14, 15 are opposed to each
other.
[0019] The front housing member 20 (specifically, the first part
21) has a first suction port 30, through which fluid is drawn in.
The first suction port 30 opens in the second end face 21c of the
first compressor through-hole 21a. That is, the first compressor
through-hole 21a constitutes the first suction port 30 and the
first impeller chamber A1. The fluid drawn in from the first
suction port 30 flows into the first impeller chamber A1.
[0020] As shown in FIG. 1, the front housing member 20 has a first
diffuser passage 31 and a first discharge chamber 32. The first
diffuser passage 31 is arranged outward of the first impeller
chamber A1 in the radial direction of the rotary shaft 12. The
first discharge chamber 32 communicates with the first impeller
chamber A1 via the first diffuser passage 31. The first diffuser
passage 31 has an annular shape that surrounds the first impeller
14. The first discharge chamber 32 is arranged outward of the first
diffuser passage 31 in the radial direction of the rotary shaft 12
and communicates with a first discharge port 33 provided in the
front housing member 20.
[0021] Likewise, the front housing member 20 has a second diffuser
passage 34 and a second discharge chamber 35. The second diffuser
passage 34 is arranged outward of the second impeller chamber A2 in
the radial direction of the rotary shaft 12. The second discharge
chamber 35 communicates with the second impeller chamber A2 via the
second diffuser passage 34. The fluid in the second discharge
chamber 35 is discharged from a second discharge port 36 provided
in the front housing member 20.
[0022] As shown in FIG. 1, the housing 11 includes a motor housing
41 and an end plate 42, which define a motor chamber A3 that
accommodates the electric motor 13.
[0023] The motor housing 41 has a tubular shape with one end closed
that has, for example, a bottom portion 41a and opening on the side
opposite to the bottom portion 41a. The axial direction of the
motor housing 41 coincides with the axial direction Z of the rotary
shaft 12. The end plate 42 is shaped as a disc the diameter of
which is equal to the outer diameter of the motor housing 41. The
thickness direction of the end plate 42 coincides with the axial
direction Z of the rotary shaft 12. The motor housing 41 and the
end plate 42 are assembled with the open end of the motor housing
41 abutting against a first plate surface 42a of the end plate 42.
The open end of the motor housing 41 is closed by the end plate 42.
The motor chamber A 3 is defined the motor housing 41 and the end
plate 42.
[0024] The rotary shaft 12 extends through the bottom portion 41a
of the motor housing 41. The bottom portion 41a has bottom
through-holes 41b, which allow the motor chamber A3 and the second
impeller chamber A2 to communicate with each other. The bottom
through-holes 41b are arranged across both the portion of the
bottom portion 41a of the motor housing 41 that overlaps with the
main body 12a as viewed from the axial direction Z of the rotary
shaft 12 and a portion surrounding that overlapping portion. The
bottom through-holes 41b overlap with the recess 22c of the second
part 22 as viewed from the axial direction Z of the rotary shaft
12. The motor chamber A3 and the second impeller chamber A2
communicate with each other via the bottom through-holes 41b and
the recess 22c of the second part 22. The bottom through-holes 41b
are not continuously provided over the entire circumference of the
rotary shaft 12 but are spaced apart at predetermined intervals in
the circumferential direction of the rotary shaft 12.
[0025] As shown in FIG. 2, the electric motor 13 has a rotor 50
attached to the rotary shaft 12 (more specifically, to the main
body 12a of the rotary shaft 12). The rotor 50 has a tubular shape
(specifically, a cylindrical shape) as a whole and the axial
direction of the rotor 50 is the axial direction Z of the rotary
shaft 12. The rotor 50 has first and second rotor end faces 50a,
50b, which are positioned on the opposite sides in the axial
direction Z of the rotary shaft 12. The rotor 50 includes magnetic
steel sheets 51 laminated in the axial direction Z of the rotary
shaft 12 and first and second holding plates 52, 53, which hold the
magnetic steel sheets 51 in between in the axial direction Z of the
rotary shaft 12. The first and second holding plates 52, 53 make a
pair. In the present embodiment, the magnetic steel sheets 51 and
the first and second holding plates 52, 53 have the same shape,
which is an annular shape as viewed from the axial direction Z of
the rotary shaft 12. For the illustrative purposes, the side toward
the magnetic steel sheets 51 in the axial direction Z of the rotary
shaft 12 will be referred to as the inner side, and the side away
from the magnetic steel sheets 51 in the axial direction Z of the
rotary shaft 12 will be referred to as the outer side in the
following description.
[0026] The rotor 50 has rivets 54, or coupling members that couple
the magnetic steel sheets 51 and the first and second holding
plates 52, 53 together. Each rivet 54 includes a barrel 54a and
first and second heads 54b, 54c. The barrel 54a is inserted through
the magnetic steel sheets 51 and the first and second holding
plates 52, 53. The first and second heads 54b, 54c are provided at
the opposite ends in the axial direction Z of the barrel 54a. One
of the first and second heads 54b, 54c is formed in advance before
the swaging process and the other is formed by crushing the distal
end of the barrel 54a by swaging.
[0027] The magnetic steel sheets 51 and the first and second
holding plates 52, 53 are coupled together by being held between
the first and second heads 54b, 54c. Specifically, the magnetic
steel sheets 51 and the first and second holding plates 52, 53 have
through-holes 51a, 52a, 52a, which extend therethrough in the axial
direction Z of the rotary shaft 12. These through-holes 51a, 52a,
53a have the same shape and communicate with each other in the
axial direction Z of the rotary shaft 12. The barrels 54a are
inserted through the through-holes 51a, 52a, 53a. The first and
second heads 54b, 54c have greater diameters than those of the
through-holes 51a, 52a, 53a. The holding plates 52, 53 have holding
inner surfaces 52b, 53b, which contact the magnetic steel sheets
51. The first and second heads 54b, 54c are caught on holding outer
surfaces 52c, 53c on the side opposite to the holding inner
surfaces 52b, 53b. As a result, the magnetic steel sheets 51 and
the first and second holding plates 52, 53 are unitized. The first
and second holding plates 52, 53 are fixed to the rotary shaft 12
so as to rotate integrally with the rotary shaft 12. Therefore, as
the rotary shaft 12 rotates, the magnetic steel sheets 51 and the
first and second holding plates 52, 53 rotate integrally. In this
case, the first and second heads 54b, 54c protrude from the first
and second holding outer surfaces 52c, 53c.
[0028] As shown in FIG. 1, the rivets 54 are spaced apart from each
other in the circumferential direction of the rotary shaft 12 in
the present embodiment. The first holding outer surface 52c
corresponds to a plate surface of a first holding plate, and the
second holding outer surface 53c corresponds to a plate surface of
a second holding plate.
[0029] As shown in FIG. 2, the rotor 50 has first and second
spacers 55, 56, which are provided outward of the first and second
holding plates 52, 53 in the axial direction Z of the rotary shaft
12. The first and second spacers 55, 56 are shaped as discs the
thickness direction of which coincides with the axial direction Z
of the rotary shaft 12. The diameter of the first and second
spacers 55, 56 is equal to that of the magnetic steel sheets 51 and
the first and second holding plates 52, 53. The thickness of the
first and second spacers 55, 56 is greater than that of the first
and second heads 54b, 54c.
[0030] The first spacer 55 has a first contact surface 55a, which
contacts the first holding outer surface 52c. The surface of the
first spacer 55 on the side opposite to the first contact surface
55a constitutes the first rotor end face 50a.
[0031] The second spacer 56 has a second contact surface 56a, which
contacts the second holding outer surface 53c. The surface of the
second spacer 56 on the side opposite to the second contact surface
56a constitutes the second rotor end face 50b.
[0032] The first and second spacers 55, 56 have first and second
recesses 55b, 56b as accommodating portions that accommodate the
first and second heads 54b, 54c. The first recess 55b corresponds
to a first accommodating portion, and the second recess 56b
corresponds to a second accommodating portion. The first and second
recesses 55b, 56b are recessed from the first and second contact
surfaces 55a, 56a toward the outer sides in the axial direction Z.
The depth of the first and second recesses 55b, 56b is set to be
within the range less than the thickness of the first and second
spacers 55, 56 and greater than the thickness of the first and
second heads 54b, 54c. Therefore, the first and second rotor end
faces 50a, 50b are flat surfaces on which no recesses corresponding
to the first and second recesses 55b, 56b are formed.
[0033] The first and second spacers 55, 56 are fixed to the first
and second holding plates 52, 53 with the first and second heads
54b, 54c accommodated in the first and second recesses 55b, 56b and
the first and second contact surfaces 55a, 56a contacting the first
and second holding outer surfaces 52c, 53c. The first and second
holding plates 52, 53 and the first and second spacers 55, 56 may
be fixed together by any suitable means such as adhesion and
engagement.
[0034] The first rotor end face 50a is configured to be smoother
than the plate surfaces of the magnetic steel sheets 51 and the
plate surface of the first holding plate 52 (more specifically, the
first holding outer surface 52c), and the second rotor end face 50b
is configured to be smoother than the plate surfaces of the
magnetic steel sheets 51 and the plate surface of the second
holding plate 53 (more specifically, the second holding outer
surface 53c). In other words, the surface roughness (for example,
the arithmetic average roughness) of the first and second rotor end
faces 50a, 50b is less than that of the first and second holding
outer surfaces 52c, 53c.
[0035] A method for manufacturing the rotor 50 according to the
present embodiment will be briefly described. The method for
manufacturing the rotor 50 includes a lamination step of laminating
the magnetic steel sheets 51 and the first and second holding
plates 52, 53 and an insertion step of inserting the barrels 54a of
the rivets 54 into the laminated body. Each rivet 54 in the
insertion step only has the head is provided at one end of the
opposite ends in the axial direction Z of the barrel 54a.
[0036] The method for manufacturing the rotor 50 further includes a
swaging step of coupling the laminated body together by crushing
the distal end of the barrel 54a of the rivet 54 (specifically, the
end in the axial direction Z of the barrel 54a opposite to the
head). By this swaging step, a head is formed at the distal end of
the barrel 54a, so that the first and second heads 54b, 54c are
formed at the opposite ends in the axial direction Z of the barrel
54a.
[0037] Thereafter, the method for manufacturing the rotor 50
includes a step of attaching and fixing the first and second
spacers 55, 56 to the first and second holding plates 52, 53. In
this process, the first and second spacers 55, 56 are attached to
the first and second holding plates 52, 53 such that the first and
second heads 54b, 54c are accommodated in the first and second
recesses 55b, 56b of the first and second spacers 55, 56.
[0038] As shown in FIG. 1, the electric motor 13 includes a stator
57, which is arranged outward of the rotor 50 in the radial
direction of the rotary shaft 12 and fixed to the motor housing 41.
The rotor 50 and the stator 57 are arranged on the same axis as the
rotary shaft 12 and face each other in the radial direction of the
rotary shaft 12. The stator 57 has a cylindrical stator core 58 and
a coil 59 wound around the stator core 58. As a current flows
through the coil 59, the rotor 50 and the rotary shaft 12 rotate
integrally.
[0039] The motor housing 41 also has a second suction port 60. The
second suction port 60 is located closer to the end plate 42 than
to the electric motor 13 in the motor housing 41. As fluid flows in
from the second suction port 60, the motor chamber A3 is filled
with the fluid.
[0040] The centrifugal compressor 10 includes an inverter 61 as a
drive circuit that drives the electric motor 13 and an inverter
case (circuit case) 62 used to define an inverter chamber (circuit
chamber) A4 that accommodates the inverter 61. The inverter case 62
has a tubular shape with one end open and the other end closed and
is attached to the housing 11 from the axial direction Z of the
rotary shaft 12. The end plate 42 has a second plate surface 42b,
which is on the side opposite to the first plate surface 42a. The
open end of the inverter case 62 and the second plate surface 42b
of the end plate 42 abut against each other, and the opening of the
inverter case 62 is closed by the end plate 42. The inverter
chamber A4 is defined by the inverter case 62 and the end plate 42.
The inverter chamber A4 and the motor chamber A3 are partitioned
from each other by an end plate 42. In other words, the end plate
42 functions as a partition wall that partitions the motor chamber
A3 and the inverter chamber A4 from each other.
[0041] This configuration allows the inverter 61 and the fluid in
the motor chamber A3 to exchange heat via the end plate 42.
Therefore, the heat generated in the inverter 61 is transferred to
the motor chamber A3 through the end plate 42 and absorbed by the
fluid in the motor chamber A3.
[0042] As shown in FIG. 1, first and second bosses 71, 72, through
which the rotary shaft 12 (specifically, the main body 12a)
extends, are provided in the motor chamber A3 in the housing 11.
The first and second bosses 71, 72 make a pair. The first and
second bosses 71, 72 have a tubular shape, specifically, a
cylindrical shape having an inner diameter greater than the outer
diameter of the main body 12a of the rotary shaft 12 and an outer
diameter that is equal to the outer diameter of the rotor 50. The
axes of the bosses 71, 72 coincide with the axis of the main body
12a. The first and second bosses 71, 72 are arranged to face each
other in the axial direction Z of the rotary shaft 12 with the
rotor 50 in between.
[0043] The first boss 71 rises from the first plate surface 42a of
the end plate 42 in the axial direction Z of the rotary shaft 12,
specifically toward the first rotor end face 50a. The distal end
face of the first boss 71, specifically the end face of the first
boss 71 in the axial direction Z of the rotary shaft 12, is defined
as a first boss end face 71a. The first boss end face 71a and the
first rotor end face 50a are arranged so as to face each other
while being spaced apart from each other in the axial direction Z
of the rotary shaft 12. A portion of the main body 12a of the
rotary shaft 12 opposite to the side where the distal end portion
12b is provided is inserted through the first boss 71.
[0044] The second boss 72 rises from the bottom portion 41a of the
motor housing 41 in the axial direction Z of the rotary shaft 12,
specifically toward the second rotor end face 50b. The distal end
face of the second boss 72, specifically the end face of the second
boss 72 in the axial direction Z of the rotary shaft 12, is defined
as a second boss end face 72a. The second boss end face 72a and the
second rotor end face 50b are arranged so as to face each other
while being spaced apart from each other in the axial direction Z
of the rotary shaft 12. A portion of the main body 12a of the
rotary shaft 12 on the side where the distal end portion 12b is
provided is inserted through the second boss 72.
[0045] As described above, the bottom through-holes 41b are
arranged at predetermined intervals in the circumferential
direction of the rotary shaft 12. Therefore, the bottom portion 41a
of the motor housing 41 and the second boss 72 are unitized via a
part where no bottom through-holes 41b are provided in the portion
of the bottom portion 41a that overlaps with the second boss 72 as
viewed from the axial direction Z of the rotary shaft 12.
[0046] The bottom through-holes 41b are arranged across both the
portion that overlaps with the second boss 72 as viewed from the
axial direction Z of the rotary shaft 12 and the portion
surrounding that overlapping portion. Therefore, the fluid in the
motor chamber A3 flows to the second impeller chamber A2 through
the openings of the bottom through-holes 41b around the second boss
72.
[0047] As shown in FIGS. 1 and 2, the bosses 71, 72 include first
and second radial bearings 81, 82, respectively. Specifically, the
first and second radial bearings 81, 82 are provided between inner
circumferential surfaces 71b, 72b of the bosses 71, 72 and outer
circumferential surface 12c of the rotary shaft 12 (more
specifically, the main body 12a) to rotationally support the rotary
shaft 12.
[0048] The first and second radial bearings 81, 82 are, for
example, flexible non-contact type hydrodynamic bearings. For
example, the first radial bearing 81, which is arranged between the
first boss 71 and the rotary shaft 12, includes a radial top foil
83, which is arranged outward of the outer circumferential surface
12c of the rotary shaft 12 in the radial direction of the rotary
shaft 12. When the rotary shaft 12 rotates, the radial top foil 83
supports the rotary shaft 12 in a non-contact state. The radial top
foil 83 is configured to be displaceable in the radial direction of
the rotary shaft 12, while being configured not to rotate with
rotation of the rotary shaft 12. Specifically, the radial top foil
83 does not have a completely continuous loop shape but has a
tubular shape with a part missing. The radial top foil 83 has
opposite ends in the circumferential surface, one of which is a
fixed end fixed to the inner circumferential surface 71b of the
first boss 71, and the other one of which is a free end that is
located on the side opposite to the fixed end and is spaced apart
from the fixed end in the circumferential direction. In this case,
while being restricted from rotating, the radial top foil 83 is
displaceable through elastic deformation so that the clearance is
provided between the radial top foil 83 and the outer
circumferential surface 12c of the rotary shaft 12.
[0049] The first radial bearing 81 includes a radial bump foil 84,
which is arranged outward of the radial top foil 83 in the radial
direction of the rotary shaft 12 and elastically supports the
radial top foil 83. The radial bump foil 84 has protrusions
protruding inward in the radial direction of the rotary shaft 12
and surrounds the radial top foil 83 with the protrusions
contacting the radial top foil 83. The radial bump foil 84
elastically supports the radial top foil 83 in a state of being
movable in the radial direction of the rotary shaft 12 by causing
the protrusions to be crushed or restore the original shapes. A
radial clearance 85 exists between the radial top foil 83 and the
radial bump foil 84. The radial clearance 85 opens in the axial
direction Z of the rotary shaft 12.
[0050] With this configuration, when the rotary shaft 12 rotates,
the hydrodynamic pressure generated by the rotation of the rotary
shaft 12 rotationally supports the rotary shaft 12 in a non-contact
state, in which a clearance exists between the radial top foil 83
and the outer circumferential surface 12c of the rotary shaft 12.
The second radial bearing 82, which is provided between the second
boss 72 and the rotary shaft 12 operates in the same manner.
[0051] As shown in FIGS. 1 and 2, the centrifugal compressor 10 has
the first and second thrust bearings 91, 92, which receive the
thrust force generated by the rotation of the impellers 14, 15. The
thrust bearings 91, 92 are provided in the motor chamber A3 and on
the opposite sides of the rotor 50 in the axial direction Z of the
rotary shaft 12. Specifically, the first thrust bearing 91 is
provided between the first rotor end face 50a and the first boss
end face 71a, and the second thrust bearing 92 is provided between
the second rotor end face 50b and the second boss end face 72a.
[0052] In the present embodiment, the first and second thrust
bearings 91, 92 are non-contact type hydrodynamic bearings, which
receive thrust force in a non-contact state in which the
hydrodynamic pressure generated by the rotation of the rotor 50
creates clearances between the first and second thrust bearings 91,
92 and the first and second rotor end faces 50a, 50b.
[0053] The first and second thrust bearings 91, 92 have the same
configuration except for being symmetrical. Thus, the first thrust
bearing 91 will be described in detail, and a detailed description
of the second thrust bearing 92 will be omitted.
[0054] The first thrust bearing 91 has the shape of a loop as a
whole (in particular, an annular shape). The first thrust bearing
91 has a thrust top foil 93 and a thrust bump foil 94. The thrust
top foil 93 is arranged between the first boss end face 71a and the
first rotor end face 50a at a position closer to the first rotor
end face 50a than to the first boss end face 71a. The thrust bump
foil 94 is arranged between the first rotor end face 50a and the
first boss end face 71a at a position closer to the first boss end
face 71a than to the first rotor end face 50a.
[0055] The thrust top foil 93 is constituted by arranging, for
example, thin sectoral top foil parts in the circumferential
direction of the rotary shaft 12, so that the thrust top foil 93
has the shape of a loop as a whole (in particular, an annular
shape). The thrust top foil 93 is configured to be displaceable in
the axial direction Z of the rotary shaft 12, while being
configured not to rotate with rotation of the rotary shaft 12. For
example, one end in the circumferential direction of each top foil
part is a fixed end fixed to the first boss end face 71a, while the
other end is a free end.
[0056] The thrust bump foil 94 is constituted by arranging, for
example, sectoral bump foil parts in the circumferential direction
of the rotary shaft 12, so that the thrust bump foil 94 has the
shape of a loop as a whole (in particular, an annular shape). The
bump foil parts have protrusions protruding in the axial direction
Z of the rotary shaft 12 and are fixed to the first boss end face
71a with the protrusions contacting the thrust top foil 93 (more
specifically, the top foil parts). The thrust bump foil 94
elastically supports the thrust top foil 93 in a state of being
movable in the axial direction Z of the rotary shaft 12 by causing
the protrusions to be crushed or restore the original shapes. A
thrust clearance 95 exists between the thrust top foil 93 and the
thrust bump foil 94. The thrust clearance 95 opens in the radial
direction of the rotary shaft 12. That is, fluid can flow between
the inside and the outside of the first thrust bearing 91 in the
radial direction through the thrust clearance 95.
[0057] With this configuration, when the rotary shaft 12 rotates,
the rotor 50 is supported by the first thrust bearing 91
(specifically, the thrust top foil 93) in a non-contact state, in
which a clearance exists between the thrust top foil 93 and the
first rotor end face 50a by hydrodynamic pressure. In this case,
the first thrust bearing 91 receives the thrust force acting in the
axial direction Z of the rotary shaft 12.
[0058] The outer diameter of the first thrust bearing 91, in
particular, the outer diameter of the thrust top foil 93 and the
thrust bump foil 94, is set to be equal to the outer diameter of
the rotor 50 and the first boss 71. The inner diameter of the first
thrust bearing 91, in particular, the inner diameter of the thrust
top foil 93 and the thrust bump foil 94, is set to be greater than
the outer diameter of the main body 12a of the rotary shaft 12.
Therefore, an inner space A5, which communicates with the thrust
clearance 95, is provided inward of the first thrust bearing 91 in
the radial direction of the rotary shaft 12, specifically, between
the first thrust bearing 91 and the rotary shaft 12. The first
radial bearing 81 includes opposite ends in the axial direction Z,
one of which is closer to the first rotor end face 50a and exposed
to the inner space A5 of the first thrust bearing 91. That is, the
thrust clearance 95 and the radial clearance 85 communicate with
each other through the inner space A5 of the first thrust bearing
91. The inner space A5 corresponds to a space provided inward of
the thrust bearing in the radial direction of the rotary shaft.
[0059] As shown in FIG. 2, the inner diameter of the first thrust
bearing 91 is set to be smaller than the inner diameter of the
first boss 71 in the present embodiment. In other words, the first
thrust bearing 91 has an inner edge 91a, which separates from the
outer circumferential surface 12c of the rotary shaft 12 and
protrudes further inward than the inner circumferential surface 71b
of the first boss 71 in the radial direction of the rotary shaft
12.
[0060] As shown in FIG. 1, the centrifugal compressor 10
constitutes part of a vehicle air conditioner 100. That is, the
fluid to be compressed in the centrifugal compressor in the present
embodiment is refrigerant.
[0061] In addition to the centrifugal compressor 10, the vehicle
air conditioner 100 also includes a condenser 101, a gas-liquid
separator 102, an expansion valve 103, and an evaporator 104. The
condenser 101, the gas-liquid separator 102, the expansion valve
103, and the evaporator 104 are connected together via piping.
Also, the condenser 101 is connected to the first discharge port
33, and the evaporator 104 is connected to the second suction port
60. The vehicle air conditioner 100 also has a pipe 105 that
connects the second discharge port 36 and the first suction port 30
to each other.
[0062] Next, as an operation of the present embodiment, the flow of
fluid in the centrifugal compressor 10 and the vehicle air
conditioner 100 configured as described above will be
described.
[0063] When the impellers 14, 15 rotate with rotation of the rotary
shaft 12, relatively low-pressure fluid (hereinafter, referred to
as suction fluid) discharged from the evaporator 104 is drawn in
from the second suction port 60. In this case, the motor chamber A3
is a low-pressure space. The suction fluid drawn into the motor
chamber A3 moves toward the second impeller chamber A2. Then, the
suction fluid is routed from the second impeller chamber A2 to the
second discharge chamber 35 through the second diffuser passage 34
by the centrifugal action of the second impeller 15, and is
discharged from the second discharge port 36. The pressure of the
fluid present in the second discharge chamber 35 is higher than the
pressure of the suction fluid. The fluid discharged from the second
discharge port 36 is referred to as an intermediate-pressure
fluid.
[0064] Some of the suction fluid in the motor chamber A3 is
supplied to the first and second thrust bearings 91, 92 provided
between the first and second rotor end faces 50a, 50b and the first
and second boss end faces 71a, 72a, and is supplied to the first
and second radial bearings 81, 82 through the thrust clearance 95
of the first and second thrust bearings 91, 92 and the inner space
A5. In such a situation, rotation of the rotary shaft 12 generates
hydrodynamic pressure in the first and second thrust bearings 91,
92 and the first and second radial bearings 81, 82. As a result,
the rotary shaft 12 is supported in a non-contact state both in the
radial direction and the axial direction Z of the rotary shaft 12.
In this case, the first and second thrust bearings 91, 92 receive
thrust force.
[0065] In addition, as shown in FIG. 1, the intermediate-pressure
fluid is drawn into the first suction port 30 via the pipe 105. The
intermediate-pressure fluid is routed from the first impeller
chamber A1 to the first discharge chamber 32 through the first
diffuser passage 31 by the centrifugal action of the first impeller
14, and is discharged from the first discharge port 33. The
pressure of the fluid discharged from the first discharge port 33
is higher than the pressure of the intermediate-pressure fluid.
[0066] The present embodiment, which has been described above,
achieves the following advantages.
[0067] (1) The centrifugal compressor 10 includes the rotary shaft
12, the rotor 50 attached to the rotary shaft 12, the electric
motor 13, which rotates the rotary shaft 12, the impellers 14, 15,
which rotate as the rotary shaft 12 rotates to compress fluid, and
the housing 11, which accommodates the rotary shaft 12, the
electric motor 13, and the impellers 14, 15. In addition, the
centrifugal compressor 10 is provided in the housing 11 and
includes the first and second bosses 71, 72, through which the
rotary shaft 12 extends.
[0068] The first radial bearing 81, which rotationally supports the
rotary shaft 12, is arranged between the first boss 71 and the
rotary shaft 12. The second radial bearing 82, which rotationally
supports the rotary shaft 12, is arranged between the second boss
72 and the rotary shaft 12.
[0069] The rotor 50 has first and second rotor end faces 50a, 50b,
which are positioned on the opposite sides in the axial direction Z
of the rotary shaft 12. In the axial direction Z of the rotary
shaft 12, the first rotor end face 50a faces the first boss end
face 71a, which is the end face of the first boss 71 in the axial
direction Z of the rotary shaft 12. In the axial direction Z of the
rotary shaft 12, the second rotor end face 50b faces the second
boss end face 72a, which is the end face of the second boss 72 in
the axial direction Z of the rotary shaft 12.
[0070] The first and second thrust bearings 91, 92, which receive
thrust force, are arranged between the first and second rotor end
faces 50a, 50b and the first and second boss end faces 71a,
72a.
[0071] With this configuration, the rotor 50 functions as a thrust
liner that supports the first and second thrust bearings 91, 92.
This configuration provides a dedicated thrust liner and reduces
the windage loss as compared with a configuration in which the
rotor 50 and the thrust liner both rotate. This increases the
efficiency.
[0072] Also, in order to suppress wear, a space is normally
provided between the rotor 50, which rotates, and the first and
second bosses 71, 72, which do not rotate. This space is likely to
become a dead space. In this regard, the present embodiment
provides the first and second thrust bearings 91, 92 between the
rotor 50 and the first and second bosses 71, 72, respectively, so
that the dead space is effectively utilized. Further, since it is
unnecessary to provide a dedicated chamber for accommodating the
first and second thrust bearings 91, 92 and the thrust liner, the
size of the centrifugal compressor 10 is reduced.
[0073] (2) Further, in a configuration in which a thrust liner is
provided at the proximal end of the rotary shaft 12, the assembling
directions at the time of manufacture include two directions: the
direction from first and second impellers 14, 15 toward the
electric motor 13 and the direction opposite to the first
direction. In contrast, the present embodiment has only one
assembling direction, which is a direction from the first and
second impellers 14, 15 toward the electric motor 13. This
facilitates the manufacture of the centrifugal compressor 10.
[0074] (3) The first and second thrust bearings 91, 92 are
respectively provided on the opposite sides of the rotor 50 in the
axial direction Z of the rotary shaft 12. Specifically, the first
and second bosses 71, 72 are arranged to face each other in the
axial direction Z of the rotary shaft 12 with the rotor 50 in
between. The first thrust bearing 91 is provided between the first
boss end face 71a of the first boss 71 and the first rotor end face
50a, which face each other in the axial direction Z of the rotary
shaft 12. Also, the second thrust bearing 92 is provided between
the second boss end face 72a of the second boss 72 and the second
rotor end face 50b, which face each other in the axial direction Z
of the rotary shaft 12.
[0075] This configuration is capable of receiving both the thrust
force in a first direction from the first thrust bearing 91 toward
the second thrust bearing 92 and the thrust force in a second
direction, which is the opposite direction to the first
direction.
[0076] (4) The rotor 50 includes the magnetic steel sheets 51
laminated in the axial direction Z of the rotary shaft 12, the
first and second holding plates 52, 53 holding the magnetic steel
sheets 51 in between in the axial direction Z of the rotary shaft
12, and the rivets 54 coupling the magnetic steel sheets 51 and the
first and second holding plates 52, 53 together. Each rivet 54
includes a barrel 54a and first and second heads 54b, 54c. The
barrel 54a is inserted through the magnetic steel sheets 51 and the
first and second holding plates 52, 53. The first and second heads
54b, 54c are provided at the opposite ends in the axial direction Z
of the rotary shaft 12 in of the barrel 54a.
[0077] The rotor 50 includes the first and second spacers 55, 56.
The first and second spacers 55, 56 have the first and second
contact surface 55a, 56a, which contact the holding outer surfaces
52c, 53c of the first and second holding plates 52, 53, and the
first and second rotor end faces 50a, 50b, which are arranged on
the side opposite to the first and second contact surfaces 55a,
56a.
[0078] Further, the first and second spacers 55, 56 have the first
and second recesses 55b, 56b as first and second accommodating
portions, in which the first and second heads 54b, 54c are
accommodated. With this configuration, the first and second thrust
bearings 91, 92 are respectively arranged between the first and
second spacers 55, 56 and the first and second bosses 71, 72.
[0079] In this case, the first and second heads 54b, 54c of the
rivets are accommodated in the first and second recesses 55b, 56b.
As a result, the first and second heads 54b, 54c are unlikely to
interfere with the first and second thrust bearings 91, 92.
[0080] Therefore, in the configuration in which the magnetic steel
sheets 51 and the holding plates 52, 53 are coupled together by the
rivets 54, the first and second thrust bearings 91, 92 are
installed in a favorable manner.
[0081] Particularly, in a case of the thrust bearings 91, 92, which
are non-contact type hydrodynamic bearings that receive thrust
force generated during rotation of the rotor 50 in a non-contact
state, turbulence caused by the heads 54b, 54c in the flow of fluid
generated by the rotation of the rotor 50 prevents thrust force
from being properly received.
[0082] In contrast, in the present embodiment, since the first and
second heads 54b, 54c are accommodated in the first and second
recesses 55b, 56b, the first and second heads 54b, 54c are unlikely
to cause turbulence. This configuration prevents thrust force from
being received in an improper manner due to the structure of
coupling the magnetic steel sheets 51 and the first and second
holding plates 52, 53 together.
[0083] (5) It is also conceivable to form recesses, for example, in
the first and second holding plates 52, 53. However, due to the
characteristics of the rivet 54, it is necessary to perform swaging
to crush the distal ends of the inserted barrel 54a to form heads.
If the first and second holding plates 52, 53 had recesses, the
swaging process would be difficult to perform, and the coupling
(swaging) by the rivets 54 would be likely to be insufficient.
[0084] In contrast, the configuration of the present embodiment
includes the first and second spacers 55, 56 separately from the
first and second holding plates 52, 53. Thus, the first and second
spacers 55, 56 can be attached after the above-mentioned swaging
process. This eliminates the above-described drawbacks.
[0085] (6) The magnetic steel sheets 51 and the first and second
spacers 55, 56 are annular as viewed from the axial direction Z of
the rotary shaft 12. The first and second thrust bearings 91, 92
are annular and overlapped with the first and second spacers 55, 56
as viewed from the axial direction Z of the rotary shaft 12.
[0086] Since this configuration suppresses variation of the
centrifugal force generated in the rotor 50 during rotation
depending on the position in the circumferential direction, the
rotor 50 is allowed to rotate in a stable manner. Also, since the
first and second thrust bearings 91, 92 are annular in accordance
with the magnetic steel sheets 51 and the first and second spacers
55, 56, the areas of the first and second thrust bearings 91, 92
can be easily increased as compared with the case of elliptical
shapes. This increases the magnitude of the force that can be
received by the first and second thrust bearings 91, 92.
[0087] (7) The first and second thrust bearings 91, 92
(specifically, the thrust top foil 93) are non-contact type
hydrodynamic bearings, which receive thrust force in a non-contact
state in which the hydrodynamic pressure generated by the rotation
of the rotor 50 creates clearances between the first and second
thrust bearings 91, 92 and the first and second rotor end faces
50a, 50b. In this case, if recesses and protrusions were provided
on the first and second rotor end faces 50a, 50b, the recesses and
protrusions could cause turbulence in the flow of fluid that would
generate hydrodynamic pressure between the first and second rotor
end faces 50a, 50b and the first and second thrust bearings 91, 92.
This would disadvantageously lower the hydrodynamic pressure.
[0088] In contrast, the first and second rotor end faces 50a, 50b
of the present embodiment are smoother than the plate surfaces of
the first and second holding plates 52, 53 (specifically, the first
and second holding outer surfaces 52c, 53c). This eliminates the
above-described drawbacks and thus allows the first and second
thrust bearings 91, 92 to operate in a favorable manner.
[0089] (8) The first and second thrust bearings 91, 92 have the
thrust top foils 93, which are arranged at positions closer to the
first and second rotor end faces 50a, 50b than to the first and
second boss end faces 71a, 72a. The thrust top foils 93 support the
rotor 50 in a non-contact state when the rotary shaft 12
rotates.
[0090] The first and second thrust bearings 91, 92 have the thrust
bump foils 94, which are arranged at positions closer to the first
and second boss end faces 71a, 72a than to the first and second
rotor end faces 50a, 50b. The thrust bump foils 94 are elastically
deformed to support the thrust top foils 93 in a displaceable
manner in the axial direction Z of the rotary shaft 12. This
configuration allows the thrust bump foils 94 to be elastically
deformed, so that the thrust force is received in a favorable
manner.
[0091] Also, when vibration in the axial direction Z of the rotary
shaft 12 occurs in the centrifugal compressor 10, the vibration is
absorbed by elastic deformation of the thrust bump foils 94. This
configuration restricts sliding contact between the first and
second rotor end faces 50a, 50b and the first and second boss end
faces 71a, 72a due to the vibration in the axial direction Z of the
rotary shaft 12. The vibration is thus dealt with in a favorable
manner.
[0092] (9) The first and second radial bearings 81, 82 each have a
radial top foil 83, which is provided outward of the outer
circumferential surface 12c of the rotary shaft 12 in the radial
direction of the rotary shaft 12, and a radial bump foil 84, which
is provided outward of the radial top foil 83 in the radial
direction of the rotary shaft 12. The radial top foils 83 support
the rotary shaft 12 in a non-contact state when the rotary shaft 12
rotates. The radial bump foils 84 elastically support the radial
top foils 83. The first and second thrust bearings 91, 92 are
shaped as a loop having an inner diameter longer than the diameter
of the rotary shaft 12. The inner space A5 is provided inward of
the first and second thrust bearings 91, 92 in the radial direction
of the rotary shaft 12.
[0093] In this configuration, the radial clearance 85, which is
open in the axial direction Z of the rotary shaft 12 in the first
radial bearing 81, and the thrust clearance 95, which is opened in
the radial direction of the rotary shaft 12 in the first thrust
bearing 91, communicate with each other through the inner space A5
of the first thrust bearing 91.
[0094] As a result, the fluid in the motor chamber A3 (the suction
fluid in the present embodiment) is supplied to the first radial
bearing 81 via the thrust clearance 95 of the first thrust bearing
91 and the inner space A5. Thus, when the rotary shaft 12 rotates,
the necessary hydrodynamic pressure is generated in the first
radial bearing 81.
[0095] Thus, the configuration eliminates the drawback caused by
the first thrust bearing 91 being arranged between the first boss
end face 71a and the first rotor end face 50a. Specifically, it is
possible to prevent the first thrust bearing 91 from restricting
the supply of fluid to the first radial bearing 81, so that the
operation of the first radial bearing 81 will not be hampered. The
second radial bearing 82 and second thrust bearing 92 achieve the
same advantage.
[0096] (10) Particularly, the first thrust bearing 91 has an inner
edge 91a, which separates from the outer circumferential surface
12c of the rotary shaft 12 and protrudes further inward than the
inner circumferential surface 71b of the first boss 71 in the
radial direction of the rotary shaft 12. Since this configuration
increases the area of the first thrust bearing 91, the receivable
thrust force is increased. The second thrust bearing 92 achieves
the same advantage.
[0097] (11) The centrifugal compressor 10 includes the inverter 61,
which drives the electric motor 13, and the inverter case 62, which
defines the inverter chamber A4. The inverter chamber A4
accommodates the inverter 61. The inverter case 62 is attached to
the housing 11 in the axial direction Z of the rotary shaft 12. The
housing 11 includes the motor chamber A3, which accommodates the
electric motor 13 and into which fluid is drawn from the second
suction port 60, and the end plate 42, which functions as a
partition wall partitioning the motor chamber A3 and the inverter
chamber A4 from each other.
[0098] This configuration allows the inverter 61 to exchange heat
with the fluid in the motor chamber A3 via the end plate 42.
Accordingly, the inverter 61 can be cooled by using the fluid in
the motor chamber A3.
[0099] Particularly, the present embodiment has no thrust chamber
that accommodates a thrust bearing and a thrust liner between the
inverter chamber A4 and motor chamber A3. Accordingly, the inverter
61 can be cooled by using the fluid in the motor chamber A3 in a
favorable manner. This suppresses the generation of heat by the
inverter 61.
[0100] (12) The centrifugal compressor 10 includes the first
impeller 14 and the second impeller 15, which are arranged such
that the end faces 14a, 15a face each other. The suction fluid is
drawn into the motor chamber A3 from the second suction port 60. In
addition, the motor chamber A3 communicates with the second
impeller chamber A2, which accommodates the second impeller 15, and
the second impeller 15 compresses the suction fluid, which has been
drawn into the second impeller chamber A2 from the motor chamber
A3. The first impeller 14 is configured to compress the
intermediate-pressure fluid, which has been compressed by the
second impeller 15.
[0101] This configuration fills the motor chamber A3 with the
suction fluid, the pressure of which is relatively low. This
reduces the windage loss of the rotor 50 provided in the motor
chamber A3.
[0102] The above-described embodiment may be modified as
follows.
[0103] As shown in FIG. 3, the first discharge port 33 and the
second suction port 60 may be omitted. In this case, the
centrifugal compressor 10 may include an intermediate pressure port
110, which connects the first discharge chamber 32 and the motor
chamber A3 to each other. The intermediate pressure port 110
extends in the radial direction Z of the rotary shaft 12 through
the middle part 23, the second part 22, and the bottom portion 41a
of the motor housing 41. Also, the condenser 101 is connected to
the second discharge port 36, and the first suction port 30 is
connected to the evaporator 104.
[0104] In this configuration, the fluid that is discharged from the
evaporator 104 and drawn from the first suction port 30 is
discharged from the second discharge port 36 after passing through
the first impeller chamber A1, the first diffuser passage 31, the
first discharge chamber 32, the intermediate pressure port 110, the
motor chamber A3, the second impeller chamber A2, the second
diffuser passage 34, and the second discharge chamber 35 in the
order. In this case, the motor chamber A3 is filled with the
intermediate-pressure fluid.
[0105] Either one of the first and second thrust bearings 91, 92
may be omitted.
[0106] The first and second thrust bearings 91, 92 may have
different structures.
[0107] The first boss 71 may have a through-hole extending
therethrough in the radial direction of the rotary shaft 12. This
through-hole preferably connects the space between the first radial
bearing 81 and the end plate 42 to the space on the outer side of
the first boss 71 in the radial direction of the rotary shaft 12.
This allows fluid to be supplied to the first radial bearing 81 in
a more favorable manner.
[0108] The outer diameter of the rotor 50 may be different from the
outer diameter of the first and second bosses 71, 72. In this case,
the outer diameter of the thrust bearing 91, 92 is preferably
shorter than or equal to the shorter of the outer diameter of the
rotor 50 and the outer diameter of the first and second bosses 71,
72.
[0109] Further, the inner diameter of the first and second thrust
bearings 91, 92 may be set to be greater than or equal to the inner
diameter of the first and second bosses 71, 72.
[0110] The magnetic steel sheets 51 may be non-annular as viewed
from the axial direction Z of the rotary shaft 12. This increases
the saliency of the rotor 50. In this configuration, the spacers
55, 56 are preferably annular as viewed from the axial direction Z
of the rotary shaft 12. This allows the first and second thrust
bearings 91, 92 to receive thrust force in a favorable manner,
while increasing the saliency of the rotor 50.
[0111] The present invention is not limited this, but the first and
second holding plates 52, 53 and the first and second spacers 55,
56 may also be non-annular in correspondence with the shape of the
magnetic steel sheets 51. Also, the bosses 71, 72 may have a
tubular shape that is non-circular as viewed from the axial
direction Z of the shaft 12.
[0112] The first and second spacers 55, 56 may be omitted. In this
case, the first and second holding outer surfaces 52c, 53c of the
first and second holding plates 52, 53 constitute the first and
second rotor end faces 50a, 50b. Also, the first and second holding
outer surfaces 52c, 53c of the first and second holding plates 52,
53 may have recesses that accommodate the first and second heads
54b, 54c. Further, only one of the first and second spacers 55, 56
may be omitted.
[0113] The accommodating portions are not limited to recesses, but
may be through-holes extending through the first and second spacers
55, 56 in the thickness direction.
[0114] Other than the rivets 54, any configuration may be used to
couple the magnetic steel sheets 51 and the first and second
holding plates 52, 53 together and cause these to rotate integrally
with the rotor 50. In short, any configuration may be employed as
long as the magnetic steel sheets 51 and the first and second
holding plates 52, 53 are fixed to the rotary shaft 12 so as to
rotate integrally with the rotor 50 while being coupled
together.
[0115] In the above-described embodiment, the first and second
thrust bearings 91, 92 are of a foil type having the thrust top
foils 93 and the thrust bump foils 94. The present invention is not
limited this, and any configuration can be employed as long as
thrust force can be received. The same applies to the radial
bearings 81, 82.
[0116] Either one of the first and second impellers 14, 15 may be
omitted. In this case, the diffuser passage and the discharge
chamber that correspond to the omitted impeller may be omitted.
[0117] The centrifugal compressor 10 may be mounted on any
structure other than a vehicle.
[0118] In the above-described embodiment, the centrifugal
compressor 10 is used as a part of the vehicle air conditioner 100.
The present invention is not limited to this, and the compressor 10
may be used for other purposes. For example, if the vehicle is a
fuel cell vehicle (FCV), which mounts a fuel cell, the centrifugal
compressor 10 may be used in a supplying device that supplies air
to the fuel cell. That is, the fluid to be compressed may be any
fluid such as refrigerant or air. The fluid device is not limited
to the vehicle air conditioner 100, but may be any device.
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