U.S. patent application number 14/659742 was filed with the patent office on 2015-09-24 for turbo type fluid machine.
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 Toshiro FUJII, Nobuaki HOSHINO, Hajime KURITA, Hironao YOKOI.
Application Number | 20150267717 14/659742 |
Document ID | / |
Family ID | 52780827 |
Filed Date | 2015-09-24 |
United States Patent
Application |
20150267717 |
Kind Code |
A1 |
FUJII; Toshiro ; et
al. |
September 24, 2015 |
TURBO TYPE FLUID MACHINE
Abstract
A turbo type compressor of the present invention comprises a
housing, a rotating shaft, and first and second impellers. The
rotating shaft is supported by the housing to be rotatable around a
rotational axis. A cylinder portion is provided on the rear end
side of the rotating shaft. The rotating shaft is supported by a
first radial foil bearing provided on the radially outer
circumference of the cylinder portion and a second radial foil
bearing provided on the radially inner circumference of the
cylinder portion.
Inventors: |
FUJII; Toshiro; (Kariya-shi,
JP) ; KURITA; Hajime; (Kariya-shi, JP) ;
HOSHINO; Nobuaki; (Kariya-shi, JP) ; YOKOI;
Hironao; (Kariya-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
KABUSHIKI KAISHA TOYOTA JIDOSHOKKI |
Kariya-shi |
|
JP |
|
|
Assignee: |
KABUSHIKI KAISHA TOYOTA
JIDOSHOKKI
Kariya-shi, Aichi-ken
JP
|
Family ID: |
52780827 |
Appl. No.: |
14/659742 |
Filed: |
March 17, 2015 |
Current U.S.
Class: |
415/220 |
Current CPC
Class: |
F16C 17/042 20130101;
F16C 17/024 20130101; F16C 17/10 20130101; F04D 29/321 20130101;
F04D 29/663 20130101; F04D 17/12 20130101; F04D 29/059 20130101;
F04D 29/668 20130101; F04D 29/053 20130101; F04D 19/002 20130101;
F04D 29/522 20130101; F04D 29/057 20130101; F04D 29/5806 20130101;
F04D 25/06 20130101; F16C 2360/44 20130101 |
International
Class: |
F04D 29/66 20060101
F04D029/66; F04D 29/32 20060101 F04D029/32; F04D 29/053 20060101
F04D029/053; F04D 29/52 20060101 F04D029/52; F04D 19/00 20060101
F04D019/00; F04D 29/059 20060101 F04D029/059 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 19, 2014 |
JP |
2014-056806 |
Claims
1. A turbo type fluid machine comprising: a rotating shaft
supported by a housing to be rotatable around a rotational axis;
and an impeller coupled to the rotating shaft, wherein the turbo
type fluid machine discharges fluid along with rotation of the
impeller, wherein the rotating shaft includes a cylinder portion,
and the rotating shaft is supported by a first radial foil bearing
provided on a radially outer circumference of the cylinder portion
and a second radial foil bearing provided on a radially inner
circumference of the cylinder portion.
2. The turbo type fluid machine according to claim 1, wherein the
first radial foil bearing includes a first top foil and a first
bump foil located on a radially outer circumference side of the
first top foil and capable of elastically supporting the first top
foil, the first top foil includes, at one end, a first rotation
stop portion for preventing the first top foil from rotating with
respect to the housing, the second radial foil bearing includes a
second top foil and a second bump foil located on a radially inner
circumference side of the second top foil and capable of
elastically supporting the second top foil, the second top foil
includes, at one end, a second rotation stop portion for preventing
the second top foil from rotating with respect to the housing, and
the rotational axis is arranged such that the rotational axis does
not cross an imaginary straight line that connects the first
rotation stop portion and the second rotation stop portion.
3. The turbo type fluid machine according to claim 1, wherein the
cylinder portion is provided at one end of the rotating shaft, the
housing includes a bottomed cylindrical portion and a convex
portion projecting into the cylinder portion from a bottom surface
of the bottomed cylindrical portion, the first radial foil bearing
is provided on a radially inner circumference of the bottomed
cylindrical portion, and the second radial foil bearing is provided
on a radially outer circumference of the convex portion.
4. The turbo type fluid machine according to claim 3, wherein the
cylinder portion includes a disk-shaped first supported portion
extending from one end of the rotating shaft in a direction
orthogonal to the rotational axis and a cylindrical second
supported portion extending further apart from the one end of the
rotating shaft from an outer circumferential edge of the first
supported portion in parallel with the rotational axis, a first
thrust foil bearing is provided on a surface of the first supported
portion on the side of the rotating shaft, and a second thrust foil
bearing is provided on a surface of the first supported portion on
the opposite side of the rotating shaft.
Description
TECHNICAL FIELD
[0001] The present invention relates to a turbo type fluid
machine.
BACKGROUND ART
[0002] Japanese Patent Application Laid-Open No. 2009-257165
discloses a conventional turbo type fluid machine. The turbo type
fluid machine includes a rotating shaft supported by a housing to
be rotatable around a rotational axis and an impeller coupled to
the rotating shaft. In the turbo type fluid machine, fluid is
discharged by rotation of the impeller. The rotating shaft is
supported by two radial foil bearings provided in the front and the
rear in a rotational axis direction.
[0003] The radial foil bearings include top foils located on the
outer circumference side of the rotating shaft and bump foils
located on the outer circumference sides of the top foils and
capable of elastically supporting the top foils.
[0004] In the radial foil bearings, when the rotational speed of
the rotating shaft is low, the outer circumferential surface of the
rotating shaft and the top foils slide with each other. On the
other hand, when the rotational speed of the rotating shaft
increases, since the dynamic pressure of the fluid acts between the
outer circumferential surface of the rotating shaft and the top
foils, the outer circumferential surface of the rotating shaft and
the top foils change into a noncontact state in the radial
direction. The rotating shaft rotates at a low coefficient of
friction in the radial direction. Therefore, the turbo type fluid
machine achieves high power performance. A wear of rotating shaft
and the like are less in the radial direction. Therefore, the turbo
type fluid machine achieves high durability.
[0005] However, when the turbo type fluid machine explained above
is mounted on, for example, a vehicle, it is likely that the
rotating shaft is swung by vibration or the like and the dynamic
pressure is less effective on the radial foil bearings. In this
case, the outer circumferential surface of the rotating shaft may
be brought into contact with the radial foil bearings, and not only
noise and vibration may occur in the radial foil bearings and the
rotating shaft but also the wear may occur to spoil durability.
[0006] Therefore, in order to increase a load capacity of the
radial foil bearings by increasing the area of a portion where the
dynamic pressure occurs, the lengths in the rotational axis
direction of the rotating shaft and the radial foil bearings may be
increased or the radiuses thereof may be increased, which, however,
increases the size of the turbo type fluid machine. In this case,
for example, mounting performance on a vehicle or the like is
spoiled.
[0007] The present invention has been devised in view of the
conventional circumstances, and it is an object of the invention to
provide a turbo type fluid machine that less easily causes noise
and vibration and is capable of achieving excellent durability
while realizing a reduction in size.
SUMMARY OF THE INVENTION
[0008] A turbo type fluid machine of the present invention is a
turbo type fluid machine comprising: a rotating shaft supported by
a housing to be rotatable around a rotational axis; and an impeller
coupled to the rotating shaft. The turbo type fluid machine
discharges fluid along with rotation of the impeller. The rotating
shaft includes a cylinder portion. The rotating shaft is supported
by a first radial foil bearing provided on the radially outer
circumference of the cylinder portion and a second radial foil
bearing provided on the radially inner circumference of the
cylinder portion.
[0009] Other aspects and advantages of the present invention will
be apparent from the embodiments disclosed in the following
description and the attached drawings, the illustrations
exemplified in the drawings, and the concept of the invention
disclosed in the entire description and drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 is a sectional view of a turbo type compressor in an
embodiment 1.
[0011] FIG. 2 is an A-A sectional view of FIG. 1, according to the
turbo type compressor in the embodiment 1.
[0012] FIG. 3 is a B-B sectional view of FIG. 1, according to the
turbo type compressor in the embodiment 1.
[0013] FIG. 4 is a schematic diagram showing a control mechanism,
according to the turbo type compressor in the embodiment 1.
[0014] FIG. 5 is a sectional view of a turbo type compressor in an
embodiment 2.
[0015] FIG. 6 is a B-B sectional view of FIG. 1 of the turbo type
compressor in which a first radial foil including three keys and a
second radial foil including two keys are provided, according to
the turbo type compressor in the embodiment 3.
DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS
[0016] Embodiments 1 to 3 embodying the present invention are
explained below with reference to the drawings.
Embodiment 1
[0017] As shown in FIG. 1, a turbo type compressor 100, which is a
turbo type fluid machine, includes a housing 1, a rotating shaft 3
having a rotational axis O as a center axis, an electric motor 5, a
first impeller 7, and a second impeller 9.
[0018] The housing 1 includes a front housing 11, an end plate 13,
and a rear housing 15.
[0019] The front housing 11 includes a first front housing 11a, a
second front housing 11b, a third front housing 11c, and a fourth
front housing 11d. In the front housing 11, the first front housing
11a, the second front housing 11b, the third front housing 11c, and
the fourth front housing 11d are joined in this order from the
front end side toward the rear end side. In the front housing 11,
first and second impeller chambers 17 and 19, first and second
diffusers 21 and 23, first and second discharge chambers 25 and 27,
a motor chamber 29, first and second suction ports 31 and 33, an
intermediate pressure port 35, and a discharge port 37 are formed.
In the second front housing 11b, a first shaft hole 41a extending
in the rotational axis O direction is formed.
[0020] The first impeller chamber 17 is formed on the front end
side of the front housing 11. The first impeller chamber 17 is
formed by the first front housing 11a and the second front housing
11b. The first impeller chamber 17 is formed in a circular
truncated cone shape curved such that a generatrix approaches the
rotational axis O from the rear side toward the front side of the
front housing 11.
[0021] The second impeller chamber 19 is formed further in the rear
than the first impeller chamber 17 in the front housing 11. The
second impeller chamber 19 is formed by the second front housing
11b and the third front housing 11c. The second impeller chamber 19
is formed in a circular truncated cone shape curved such that a
generatrix approaches the rotational axis O from the front side
toward the rear side of the front housing 11. The second impeller
chamber 19 is formed in a similar shape smaller than the first
impeller chamber 17.
[0022] The first diffuser 21 is formed on the front end side of the
second front housing 11b and located on the outer circumference
side of the first impeller chamber 17. The first diffuser 21
communicates with the first impeller chamber 17 in a part where the
inner diameter of the first impeller chamber 17 is the largest.
[0023] The second diffuser 23 is formed on the front end side of
the third front housing 11c and located on the outer circumference
side of the second impeller chamber 19. The second diffuser 23
communicates with the second impeller chamber 19 in a part where
the inner diameter of the second impeller chamber 19 is the
largest. The second diffuser 23 is formed in a diameter smaller
than the first diffuser 21.
[0024] The first discharge chamber 25 is formed by the first front
housing 11a and the second front housing 11b. The first discharge
chamber 25 is located on the outer circumference side of the first
diffuser 21 and communicates with the first diffuser 21. The first
discharge chamber 25 is an annular space and is formed such that
the sectional area thereof gradually enlarges in the rotational
axis O direction. The first discharge chamber 25 communicates with
the first impeller chamber 17 via the first diffuser 21.
[0025] The second discharge chamber 27 is formed by the second
front housing 11b and the third front housing 11c. The second
discharge chamber 27 is located on the outer circumference side of
the second diffuser 23 and communicates with the second diffuser
23. The second discharge chamber 27 is an annular space and is
formed such that the sectional area thereof gradually enlarges in
the rotational axis O direction. Since the second impeller chamber
19 and the second diffuser 23 are respectively smaller in diameter
than the first impeller chamber 17 and the first diffuser 21, the
second discharge chamber 27 is located further on the inner
circumference side of the front housing 11 than the first discharge
chamber 25. The second discharge chamber 27 communicates with the
second impeller chamber 19 via the second diffuser 23.
[0026] The second discharge chamber 27 communicates with the
discharge port 37. The discharge port 37 is formed by the second
front housing 11b and the third front housing 11c and radially
extends from the second discharge chamber 27. The discharge port 37
causes the second discharge chamber 27 and the outside of the front
housing 11 to communicate with each other.
[0027] The motor chamber 29 is formed in the fourth front housing
11d. The motor chamber 29 extends in the rotational axis O
direction.
[0028] In the fourth front housing 11d, a boss 51 is formed on the
front end side of the motor chamber 29. The boss 51 extends toward
the rear end side of the motor chamber 29 in the rotational axis O
direction. A second shaft hole 51a coaxial with the first shaft
hole 41a is formed in the boss 51. A third radial foil bearing 43
is provided in the second shaft hole 51a.
[0029] The first suction port 31 is formed on the front end side of
the first front housing 11a. The first suction port 31 extends in
the rotational axis O direction. The front end side of the first
suction port 31 opens to the front end surface of the first front
housing 11a. The rear end side of the first suction port 31
communicates with the first impeller chamber 17.
[0030] The second suction port 33 is formed to extend across the
rear end side of the third front housing 11c and the front end side
of the fourth front housing 11d. The rear end side of the second
suction port 33 communicates with the motor chamber 29 on the front
end side of the boss 51. On the other hand, the front end side of
the second suction port 33 communicates with the second impeller
chamber 19. The second suction port 33 communicates with the second
shaft hole 51a. That is, the second suction port 33 causes the
motor chamber 29 and the second impeller chamber 19 to communicate
with each other.
[0031] The intermediate pressure port 35 is formed further on the
outer circumference side than the second discharge chamber 27 to
extend across the second to fourth front housings 11b, 11c, and 11d
in the rotational axis O direction. The front end of the
intermediate pressure port 35 communicates with the first discharge
chamber 25. The rear end of the intermediate pressure port 35
communicates with the motor chamber 29. That is, the intermediate
pressure port 35 causes the first discharge chamber 25 and the
motor chamber 29 to communicate with each other in the rotational
axis O direction.
[0032] The end plate 13 is joined to the rear end of the fourth
front housing 11d. That is, the end plate 13 closes the rear end of
the motor chamber 29. In the endplate 13, a third shaft hole 13a
coaxial with the first and second shaft holes 41a and 51a is
formed. A third shaft supporting surface 13b orthogonal to the
rotational axis O is formed at the rear end of the end plate 13. A
third key groove 13c, which extends in a direction orthogonal to
the rotational axis O, is recessed in the third shaft supporting
surface 13b.
[0033] The rear housing 15 is located in the rear of the housing 1
and jointed to the rear end side of the end plate 13. The rear
housing 15 sandwiches the endplate 13 in conjunction with the
fourth front housing 11d. The rear housing 15 includes a columnar
convex portion 15a extending front from the rear in the rotational
axis O direction. A fourth shaft supporting surface 15b orthogonal
to the rotational axis O and facing the third shaft supporting
surface 13b is formed at the front end of the convex portion 15a. A
fourth key groove 15t, which extends in a direction orthogonal to
the rotating shaft 3, is recessed in the fourth shaft supporting
surface 15b. The rear housing 15 corresponds to a bottomed
cylindrical portion.
[0034] In the rear housing 15, an annular radial space 15c
extending in the rotational axis O direction to surround the outer
circumference of the convex portion 15a and a disk-shaped thrust
space 15d linked to the front end of the radial space 15c and
formed by the rear housing 15 and the end plate 13 are formed. The
front end of the radial space 15c and the thrust space 15d
communicate with each other.
[0035] A first shaft supporting surface 15f coaxial with the
rotational axis O is formed on the inner circumferential surface of
the rear housing 15, that is, the outer circumferential surface of
the radial space 15c. A second shaft supporting surface 15e coaxial
with the rotational axis O and located further on the rotational
axis O side than the first shaft supporting surface 15f is formed
on the outer circumferential surface of the convex portion 15a,
that is, the inner circumferential surface of the radial space 15c.
As shown in FIG. 3, a first key groove 15g, which extends in the
rotational axis O direction, is recessed in the first shaft
supporting surface 15f. A second key groove 15h, which extends in
the rotational axis O direction, is recessed in the second shaft
supporting surface 15e.
[0036] As shown in FIG. 1, the rotating shaft 3 includes a rotating
shaft main body 3a, a small diameter portion 3b integrated with the
rotating shaft main body 3a and located on the front end side of
the rotating shaft main body 3a, and a cylinder portion 3c located
on the rear end side of the rotating shaft main body 3a. The
rotating shaft main body 3a is formed in a columnar shape. The
small diameter portion 3b is formed in a columnar shape smaller in
diameter than the rotating shaft main body 3a.
[0037] The rotating shaft 3 is inserted through the housing 1 and
supported to be rotatable around the rotational axis O. The front
end side of the rotating shaft main body 3a is inserted through the
second shaft hole 51a and rotatably supported by the third radial
foil bearing 43. On the other hand, the rear end side of the
rotating shaft main body 3a is inserted through a third shaft hole
13a. A gap 73, into which a refrigerant serving as fluid can be
flowed, is provided between the rotating shaft main body 3a and the
third shaft hole 13a. The small diameter portion 3b is inserted
through the first shaft hole 41a.
[0038] The cylinder portion 3c includes a disk-shaped first
supported portion 55 extending from the rear end of the rotating
shaft main body 3a in a direction orthogonal to the rotational axis
O and a cylindrical second supported portion 53 extending rearward,
further apart from the rear end of the rotating shaft main body 3a,
from the outer circumferential edge of the first supported portion
55 in parallel with the rotational axis O. The second supported
portion 53 and the first supported portion 55 are integrated. The
cylinder portion 3c is opened on the rear end side of the second
supported portion 53 and is formed in a bottomed cylindrical shape
having the first supported portion 55 as a bottom.
[0039] The electric motor 5 is provided in the motor chamber 29.
The electric motor 5 includes a stator 5a and a rotor 5b. The
stator 5a is fixed to the inner wall of the motor chamber 29. The
stator 5a is electrically connected to a not-shown battery. The
rotor 5b is located on the inner circumference side of the stator
5a. The rotor 5b is fixed to the rotating shaft main body 3a.
[0040] The first impeller 7 is press-fit into the front end side of
the small diameter portion 3b in the rotating shaft 3 and provided
in the first impeller chamber 17. The first impeller 7 is capable
of rotating in the first impeller chamber 17 along with the
rotation of the rotating shaft 3. The first impeller 7 is formed in
a circular truncated cone shape curved such that a generatrix
approaches the rotational axis O. In the first impeller 7, a
plurality of blades 70 are provided at a predetermined interval. A
portion formed in a small diameter of the first impeller 7 is
located at the front end of the small diameter portion 3b. A
portion formed in a large diameter of the first impeller 7 is
located near the motor chamber 29.
[0041] The second impeller 9 is press-fit into the rear end side of
the small diameter portion 3b in the rotating shaft 3 and provided
in the second impeller chamber 19. The second impeller 9 is capable
of rotating in the second impeller chamber 19 along with the
rotation of the rotating shaft 3. The second impeller 9 is formed
in a circular truncated cone shape curved such that a generatrix
approaches the rotational axis O. The second impeller 9 is formed
in a shape similar to the shape of the first impeller 7. A portion
formed in a small diameter of the second impeller 9 is located at
the rear end of the small diameter portion 3b. A portion formed in
a large diameter of the second impeller 9 is located near the first
impeller 7. That is, in the front housing 11, the portion formed in
the large diameter of the first impeller 7 and the portion formed
in the large diameter of the second impeller 9 are arranged to face
each other. In the second impeller 9, a plurality of blades 90 are
provided at a predetermined interval.
[0042] On the outer circumference side of the second supported
portion 53, a first shaft supported surface 53a coaxial with the
rotational axis O and facing the first shaft supporting surface 15f
is formed. A first radial foil bearing 57 is provided between the
first shaft supporting surface 15f and the first shaft supported
surface 53a. The first radial foil bearing 57 is installed to the
inner circumferential surface of the rear housing 15, that is, the
first shaft supporting surface 15f.
[0043] The first radial foil bearing 57 includes, as shown in FIG.
3, a first top foil 57a located on the outer circumference side of
the first shaft supported surface 53a and displaceable with respect
to the first shaft supporting surface 15f and a first bump foil 57b
located on the outer circumference side of the first top foil 57a
and displaced with respect to the first shaft supporting surface
15f to be capable of elastically supporting the first top foil
57a.
[0044] As the first top foil 57a, a metal thin plate is curved in a
substantially arc shape. The first top foil 57a includes one gap
57s slenderly extending in the front-rear direction. The first top
foil 57a is located on the outer circumference side of the second
supported portion 53 and surrounds the first shaft supported
surface 53a.
[0045] At one end of the first top foil 57a, a first key 57k
engaged in the first key groove 15g is formed. The first key 57k is
a small piece projecting from the end edge of the first top foil
57a, which forms the gap 57s, in the radial outer direction. The
first key 57k engages in the first key groove 15g to thereby stop
or prevent rotation of the first top foil 57a in a radial space
15c. The other end of the first top foil 57a is formed as a free
end. The first key 57k corresponds to a first rotation stop
portion.
[0046] As the first bump foil 57b, a metal thin plate, on which a
plurality of curved portions 57w are formed, is curved in a
substantially arc shape. The first bump foil 57b is elastically
deformed to crush the curved portions 57w or is restored to the
original shape to thereby be displaced with respect to the first
shaft supporting surface 15f to be capable of elastically
supporting the first top foil 57a.
[0047] On the inner circumference side of the second supported
portion 53, a second shaft supported surface 53b coaxial with the
rotational axis O and facing the second shaft supporting surface
15e is formed. A second radial foil bearing 59 is provided between
the second shaft supporting surface 15e and the second shaft
supported surface 53b. The second radial foil bearing 59 is
installed to the outer circumferential surface of the convex
portion 15a in the rear housing 15, that is, the second shaft
supporting surface 15e.
[0048] The second radial foil bearing 59 includes a second top foil
59a located on the outer circumference side of the second shaft
supporting surface 15e and displaceable with respect to the second
shaft supporting surface 15e and a second bump foil 59b located on
the inner circumference side of the second top foil 59a and
displaced with respect to the second shaft supporting surface 15e
to be capable of elastically supporting the second top foil
59a.
[0049] As the second top foil 59a, a metal thin plate is curved in
a substantially arc shape. The second top foil 59a includes one gap
59s slenderly extending in the front-rear direction. The second top
foil 59a is located on the inner circumferential side of the second
supported portion 53 and surrounds the second shaft supporting
surface 15e.
[0050] At one end of the second top foil 59a, a second key 59k
engaged in the second key groove 15h is formed. The second key 59k
is a small piece projecting from the end edge of the second top
foil 59a, which forms the gap 59s, in the radial inner direction.
The second key 59k engages in the second key groove 15h to thereby
stop of prevent rotation of the second top foil 59a in the radial
space 15c. The other end of the second top foil 59a is formed as a
free end. The second key 59k corresponds to a second rotation stop
portion.
[0051] As the second bump foil 59b, a metal thin plate, on which a
plurality of curved portions 59w are formed, is curved in a
substantially arc shape. The second bump foil 59b is elastically
deformed to crush the respective curved portions 59w or restored to
the original shape to thereby be displaced with respect to the
second shaft supporting surface 15e to be capable of elastically
supporting the second top foil 59a.
[0052] The first key 57k and the second key 59k shift from each
other by about 45.degree. centering on the rotational axis O.
Therefore, the first key 57k and the second key 59k and the
rotational axis O are respectively arranged such that the
rotational axis O does not cross an imaginary straight line L1 that
connects the first key 57k and the second key 59k, or is absent on
the imaginary straight line L1 that connects the first key 57k and
the second key 59k.
[0053] As shown in FIG. 1, on the front end side of the first
supported portion 55, a third shaft supported surface 55a
orthogonal to the rotational axis O and facing the third shaft
supporting surface 13b is formed. A first thrust foil bearing 61 is
provided between the third shaft supporting surface 13b and the
third shaft supported surface 55a. The first thrust foil bearing 61
is installed to the rear end side of the end plate 13, that is, the
third shaft supporting surface 13b.
[0054] On the rear end side of the first supported portion 55, a
fourth shaft supported surface 55b orthogonal to the rotational
axis O and facing the fourth shaft supporting surface 15b is
formed. A second thrust foil bearing 63 is provided between the
fourth shaft supporting surface 15b and the fourth shaft supported
surface 55b. The second thrust foil bearing 63 is installed to the
front end side of the convex portion 15a in the rear housing 15,
that is, the fourth shaft supporting surface 15b. The first thrust
foil bearing 61 is provided on the one end side of the first
supported portion 55, which is the side near the first and second
impellers 7 and 9, and the second thrust foil bearing 63 is
provided on the other end side of the first supported portion
55.
[0055] As shown in FIG. 2, the first thrust foil bearing 61
includes eight third top foils 61a located on one end side of the
third shaft supported surface 55a and displaceable with respect to
the third shaft supporting surface 13b and eight third bump foils
61b located on one end sides of the respective third top foils 61a
and displaced with respect to the third shaft supporting surface
13b to be capable of elastically supporting the respective third
top foils 61a.
[0056] The respective third top foils 61a are made of metal thin
plates and arranged radially from the rotational axis O. Gaps 61s
in eight places slenderly extending radially from the rotational
axis O are provided among the respective third top foils 61a. The
respective third top foils 61a are located on the front end side of
the third shaft supported surface 55a. In other words, the
respective third top foils 61a are located on the rear end side of
the third shaft supporting surface 13b.
[0057] At one ends of the respective third top foils 61a, as shown
in FIG. 1 and FIG. 2, third keys 13k engaged in the third key
grooves 13c are formed. The third keys 13k are small pieces
projecting from the end edges of the respective third top foils
61a, which form the gaps 61s, toward the end plate 13 in the
rotational axis O direction. The respective third keys 13k engage
in the respective third key grooves 13c to thereby stop rotation of
the respective third top foils 61a in the thrust space 15d. The
other ends of the respective third top foils 61a are formed as free
ends.
[0058] The respective third bump foils 61b are wavy plate-shaped
metal thin plates on which a plurality of curved portions are
formed. The respective third bump foils 61b are elastically
deformed to crush the curved portions or restored to the original
shape to thereby be displaced with respect to the respective third
shaft supporting surfaces 13b and capable elastically supporting
the respective third top foils 61a.
[0059] The second thrust foil bearing 63 includes eight fourth top
foils 63a located on one end side of the fourth shaft supporting
surface 15b and displaceable with respect to the fourth shaft
supporting surface 15b and eight fourth bump foils 63b located on
the other end side of the fourth top foils 63a and displaced with
respect to the fourth shaft supporting surface 15b to be capable of
elastically supporting the fourth top foils 63a.
[0060] The respective fourth top foils 63a are made of metal thin
plates and arranged radially from the rotational axis O. Gaps 63s
in eight places slenderly extending radially from the rotational
axis O are provided among the respective fourth top foils 63a. The
respective fourth top foils 63a are located on the rear end side of
the fourth shaft supported surface 55b. In other words, the
respective fourth top foils 63a are located on the front end side
of the fourth shaft supporting surface 15b.
[0061] At one ends of the respective fourth top foils 63a, fourth
keys 15k engaged in the fourth key grooves 15t are formed. The
fourth keys 15k are small pieces projecting from the end edges of
the respective fourth top foils 63a, which form the gaps 63s,
toward the convex portion 15a in the rotational axis O direction.
The respective fourth keys 15k engage in the respective fourth key
grooves 15t to thereby stop rotation of the respective fourth top
foils 63a in the thrust space 15d. The other ends of the respective
fourth top foils 63a are formed as free ends.
[0062] The respective fourth bump foils 63b are wavy plate-shaped
metal thin plates on which a plurality of curved portions are
formed. The respective fourth bump foils 63b are elastically
deformed to crush the curved portions or restored to the original
shape to thereby be displaced with respect to the respective fourth
shaft supporting surfaces 15b to be capable of elastically
supporting the respective fourth top foils 63a.
[0063] In the turbo type compressor 100, as shown in FIG. 4, a pipe
103 connected to a condenser 101 is connected to the discharge port
37. The condenser 101 is connected to an evaporator 109 via a pipe
105 and an expansion valve 107. The evaporator 109 is connected to
the first suction port 31 through a pipe 111. A refrigeration
circuit of an air-conditioning apparatus for a vehicle is
configured by the turbo type compressor 100, the evaporator 109,
the expansion valve 107, the condenser 101, and the like.
[0064] In the turbo type compressor 100 configured as explained
above, a driving force for rotating the rotor 5b around the
rotational axis O is generated by energization to the stator 5a and
the rotating shaft 3 rotates. Consequently, the first impeller 7
rotates in the first impeller chamber 17. The second impeller 9
rotates in the second impeller chamber 19. Therefore, the
refrigerant passed through the evaporator 109 is sucked from the
first suction port 31 through the pipe 111 and reaches the first
impeller chamber 17.
[0065] The first impeller 7 rotates in the first impeller chamber
17 to thereby increase kinetic energy of the refrigerant in the
first impeller chamber 17. The first impeller 7 converts, through
the first diffuser 21, the kinetic energy of the refrigerant into
pressure energy to compress the refrigerant and discharges the
compressed refrigerant to the first discharge chamber 25.
Consequently, the pressure of the refrigerant in the first
discharge chamber 25 changes to an intermediate pressure. The
refrigerant having the intermediate pressure circulates from the
first discharge chamber 25 to the intermediate pressure port 35 and
flows into the motor chamber 29 as indicated by a solid line arrow
in FIG. 1.
[0066] The refrigerant flown into the motor chamber 29 is sucked
from the second suction port 33 into the second impeller chamber 19
as indicated by a solid line arrow. In this case, the refrigerant
circulating through the second suction port 33 is sucked into the
second impeller chamber 19. The second impeller 9 rotates in the
second impeller chamber 19 to thereby increase kinetic energy of
the refrigerant in the second impeller chamber 19. The second
impeller 9 converts, through the second diffuser 23, the kinetic
energy of the refrigerant into pressure energy to compress the
refrigerant and discharges the refrigerant to the second discharge
chamber 27. The refrigerant in the second discharge chamber 27 is
discharged from the discharge port 37 to the condenser 101. The
refrigerant passes through the expansion valve 107 and the
evaporator 109 and is again sucked into the first impeller chamber
17 from the first suction port 31. In this way, cooling of a
vehicle interior is performed.
[0067] While the cooling is performed, in the turbo type compressor
100, since the refrigerant flown in from the intermediate pressure
port 35 is led to the motor chamber 29, it is possible to cool the
electric motor 5 that generates heat during actuation.
[0068] In the turbo type compressor 100, the refrigerant flowing to
the motor chamber 29 passes through the gap 73 and flows into the
thrust space 15d. The refrigerant flown into the thrust space 15d
can flow into a space between the third shaft supported surface 55a
and the third shaft supporting surface 13b, a space between the
first shaft supported surface 53a of the radial space 15c and the
first shaft supporting surface 15f, a space between the second
shaft supported surface 53b and the second shaft supporting surface
15e, and a space between the fourth shaft supported surface 55b and
the fourth shaft supporting surface 15b in order.
[0069] In the turbo type compressor 100, in FIG. 1 and FIG. 3, when
the rotational speed of the rotating shaft 3 is low, the first
shaft supported surface 53a and the first radial foil bearing 57
slide with each other and the second shaft supported surface 53b
and the second radial foil bearing 59 slide with each other. On the
other hand, when the rotational speed of the rotating shaft 3
increases, the dynamic pressure of the refrigerant acts between the
first shaft supported surface 53a of the second supported portion
53 in the rotating shaft 3 and the first top foil 57a in the first
radial foil bearing 57. The dynamic pressure of the refrigerant
also acts between the second shaft supported surface 53b of the
second supported portion 53 and the second top foil 59a in the
second radial foil bearing 59. With the dynamic pressure, the first
and second top foils 57a and 59a displace with respect to the first
and second shaft supporting surfaces 15f and 15e. The first and
second bump foils 57b and 59b displace with respect to the first
and second shaft supporting surface 15f and 15e and elastically
support the first and second top foils 57a and 59a. Consequently,
the first shaft supported surface 53a and the first top foil 57a
separate from each other and the second shaft supported surface 53b
and the second top foil 59a separate from each other. That is, the
second supported portion 53 of the rotating shaft 3 and the first
and second top foils 57a and 59a separate from each other. In this
way, the first and second shaft supported surfaces 53a and 53b are
supported by the first and second radial foil bearings 57 and 59 in
a noncontact state.
[0070] In this case, in the turbo type compressor 100, the
rotational axis O is absent on the imaginary straight line L1 that
connects the first key 57k of the first top foil 57a in the first
radial foil bearing 57 and the second key 59k of the second top
foil 59a in the second radial foil bearing 59.
[0071] Therefore, in the turbo type compressor 100, even if the
refrigerant flows out from the gap 57s of the first top foil 57a
and the dynamic pressure of the refrigerant is less effective
between the first shaft supported surface 53a and the first top
foil 57a, the dynamic pressure of the refrigerant acts between the
second shaft supported surface 53b and the second top foil 59a
located on an imaginary straight line that connects the gap 57s and
the rotational axis O. In the turbo type compressor 100, even if
the refrigerant flows out from the gap 59s of the second top foil
59a and the dynamic pressure of the refrigerant is less effective
between the second shaft supported surface 53b and the second top
foil 59a, the dynamic pressure of the refrigerant acts between the
first shaft supported surface 53a and the first top foil 57a
located on a straight line that connects the gap 59s and the
rotational axis O.
[0072] Therefore, even if the first shaft supported surface 53a of
the second supported portion 53 in the rotating shaft 3 approaches
the gap 57s of the first top foil 57a, the second shaft supported
surface 53b of the second supported portion 53 hardly approaches
the gap 59s of the second top foil 59a.
[0073] The rotating shaft 3 rotates at a low coefficient of
friction in the radial direction. Therefore, the turbo type
compressor 100 achieves high power performance. The wear of the
rotating shaft 3 and the like are less in the radial direction.
Therefore, the turbo type compressor 100 achieves high
durability.
[0074] In the turbo type compressor 100, in FIG. 1 and FIG. 2, when
the rotational speed of the rotating shaft 3 is low, the third
shaft supported surface 55a and the first thrust foil bearing 61
slide with each other and the fourth shaft supported surface 55b
and the second thrust foil bearing 63 slide with each other. On the
other hand, when the rotational speed of the rotating shaft 3
increases, the dynamic pressure of the refrigerant acts between the
third shaft supported surface 55a of the first supported portion 55
in the rotating shaft 3 and the third top foil 61a in the first
thrust foil bearing 61. The dynamic pressure of the refrigerant
also acts between the fourth shaft supported surface 55b of the
first supported portion 55 and the fourth top foil 63a in the
second thrust foil bearing 63. With the dynamic pressure, the third
and fourth top foils 61a and 63a displace with respect to the third
and fourth shaft supporting surfaces 13b and 15b. The third and
fourth bump foils 61b and 63b displace with respect to the third
and fourth shaft supporting surfaces 13b and 15b and elastically
support third and fourth top foils 61a and 63a. Consequently, the
third shaft supported surface 55a and the third top foil 61a
separate from each other and the fourth shaft supported surface 55b
and the fourth top foil 63a separate from each other. That is, the
first supported portion 55 of the rotating shaft 3 and the third
and fourth top foils 61a and 63a separate from each other. In this
way, the third and fourth shaft supported surfaces 55a and 55b are
supported by the first and second thrust foil bearings 61 and 63 in
a noncontact state.
[0075] Further, in the turbo type compressor 100, even if the
rotating shaft 3 is swung by vibration or the like, the dynamic
pressure acts in each of the first and second radial foil bearings
57 and 59 and the first and second thrust foil bearings 61 and 63.
The area of a portion where the dynamic pressure is generated is
large compared with the conventional turbo type compressor. That
is, load capacities of the first and second radial foil bearings 57
and 59 and the first and second thrust foil bearings 61 and 63 are
large.
[0076] In particular, in the first and second radial foil bearings
57 and 59, the rotating shaft 3 easily changes to the noncontact
state with respect to the first and second shaft supported surfaces
53a and 53b of the second supported portion 53 in the radial
direction by the dynamic pressure generated on the inner side and
the dynamic pressure generated on the outer side, that is, the
dynamic pressure generated on the first shaft supported surface 53a
and the dynamic pressure generated on the second shaft supported
surface 53b.
[0077] Therefore, in the turbo type compressor 100, in the radial
direction, noise and vibration are less easily caused on the first
and second shaft supporting surfaces 15f and 15e and the first and
second shaft supported surfaces 53a and 53b and the wear is less
easily caused.
[0078] In the turbo type compressor 100, since the second thrust
foil bearing 63 is located in the cylinder portion 3c of the
rotating shaft 3, it is possible to reduce the length in the
rotational axis O direction by at least the thickness of the second
thrust foil bearing 63. Therefore, in the turbo type compressor
100, an increase in the size of the housing 1 is suppressed.
[0079] Therefore, the turbo type compressor 100 less easily causes
noise and vibration and is capable of achieving excellent
durability while realizing a reduction in size.
[0080] In the turbo type compressor 100, the first radial foil
bearing 57 is provided between the first shaft supporting surface
15f and the first shaft supported surface 53a. The second radial
foil bearing 59 is provided between the second shaft supporting
surface 15e and the second shaft supported surface 53b. In the
turbo type compressor 100, since the first and second radial foil
bearings 57 and 59 are adopted, management of the gaps formed
between the first and second radial foil bearings 57 and 59 and the
first and second shaft supported surfaces 53a and 53b is
simplified. Therefore, in the turbo type compressor 100, it is easy
to install together the first and second radial foil bearings 57
and 59.
[0081] In the turbo type compressor 100, the cylinder portion 3c of
the rotating shaft 3 is inserted between the first radial foil
bearing 57 provided on the radially inner circumference of the rear
housing 15 and the second radial foil bearing 59 provided on the
radially outer circumference of the convex portion 15a. Therefore,
the installation of the cylinder portion 3c can be easy.
Embodiment 2
[0082] As shown in FIG. 5, in an end plate 213, a boss 214
extending toward the motor chamber 29 in the rotational axis O
direction is formed. In the boss 214, a third shaft hole 213a
extending in the rotational axis O direction is formed. In the
third shaft hole 213a, a first shaft supporting surface 215f
coaxial with the rotational axis O is formed. A first radial foil
bearing 257 is provided on the first shaft supporting surface 215f.
A gap 214s is present between the front end side of the boss 214
and the rear end side of the rotor 5b.
[0083] On the rear end surface of the endplate 213, an annular
third shaft supporting surface 213b capable of supporting a first
thrust foil bearing 261 is formed.
[0084] In a rear housing 215, an annular thrust space 215d recessed
from the front end side toward rearward is formed. On the rear end
side of the thrust space 215d, that is, on the front end face in
the rear housing 215, an annular fourth shaft supporting surface
215b capable of supporting a second thrust foil bearing 263 is
formed.
[0085] In the rear housing 215, a disk-shaped supporting plate 255
and first and second thrust foil bearings 261 and 263 are provided.
The supporting plate 255 is press-fit into the rear end side of a
rotating shaft main body 203a. On the front end side of the
supporting plate 255, an annular third shaft supported surface 255a
facing the third shaft supporting surface 213b is formed. On the
rear end side of the supporting plate 255, an annular fourth shaft
supported surface 255b facing the fourth shaft supporting surface
215b is formed. The first thrust foil bearing 261 is provided
between the third shaft supporting surface 213b and the third shaft
supported surface 255a. The second thrust foil bearing 263 is
provided between the fourth shaft supporting surface 215b and the
fourth shaft supported surface 255b.
[0086] The rear housing 215 includes a columnar convex portion 215a
extending frontward from the rear in the rotational axis O
direction. On the outer circumferential surface of the convex
portion 215a, a second shaft supported surface 253b coaxial with
the rotational axis O is formed.
[0087] On the outer circumferential surface on the rear end side in
the rotating shaft main body 203a, a first shaft supported surface
253a facing the first shaft supporting surface 215f is formed. The
first radial foil bearing 257 is provided between the first shaft
supporting surface 215f and the first shaft supported surface 253a.
In the rotating shaft main body 203a, a recessed portion 203c
extending frontward from the rear end is formed. The recessed
portion 203c has a cylindrical shape opened on the rear end side
and is coaxial with the rotational axis O. The inner diameter of
the recessed portion 203c is larger than the diameter of the convex
portion 215a. The convex portion 215a is inserted into the recessed
portion 203c. On the inner circumferential surface of the recessed
portion 203c, a second shaft supporting surface 215e facing the
second shaft supported surface 253b is formed. A second radial foil
bearing 259 is provided between the second shaft supporting surface
215e and the second shaft supported surface 253b. The other
components in a turbo type compressor 200 are the same as the
components of the turbo type compressor 100 in the embodiment
1.
[0088] In the turbo type compressor 200, a refrigerant flown in
from the gap 214s can flow into a space between the first shaft
supported surface 253a and the first shaft supporting surface 215f,
a space between the third shaft supported surface 255a and the
third shaft supporting surface 213b, a space between the fourth
shaft supported surface 255b and the fourth shaft supporting
surface 215b, and a space between the second shaft supported
surface 253b and the second shaft supporting surface 215e in
order.
[0089] In the turbo type compressor 200, the first radial foil
bearing 257 is provided on the first shaft supporting surface 215f.
The second radial foil bearing 259 is arranged in the recessed
portion 203c, which is the inner side of the first radial foil
bearing 257. Therefore, portions where the dynamic pressure is
generated in the first radial foil bearing 257 and the second
radial foil bearing 259 radially overlap so that shaft length is
not extended. The other action and effects in the turbo type
compressor 200 are the same as the action and effects of the turbo
type compressor 100 in the embodiment 1.
Embodiment 3
[0090] In a turbo type compressor 300 shown in FIG. 6, in a first
shaft supporting surface 315f of the rear housing 315, three first
key grooves 315g, 316g, and 317g, which extend in the rotational
axis O direction, are recessed at equal intervals. The first key
groove 315g is located above the first shaft supporting surface
315f. The first key groove 316g is located on the lower right side
of the first shaft supporting surface 315f. The first key groove
317g is located on the lower left side of the first shaft
supporting surface 315f. In a second shaft supporting surface 315e
of the rear housing 315, two second key grooves 315h and 316h,
which extend in the rotational axis O direction, are recessed in
symmetrical positions centering on the rotational axis O. The
second key groove 315h is located on the right side. The second key
groove 316h is located on the left side.
[0091] Three first radial foil bearings 356, 357, and 358 are
provided between the first shaft supporting surface 315f and the
first shaft supported surface 53a. The first radial foil bearings
356, 357, and 358 include first top foils 356a, 357a, and 358a and
first bump foils 356b, 357b, and 358b. In the first top foils 356a,
357a, and 358a, first keys 356k, 357k, and 358k engaged in the
first key grooves 315g, 316g, and 317g are formed. The first keys
356k, 357k, and 358k engage in the first key grooves 315g, 316g,
and 317g to thereby stop rotation of the first top foils 356a,
357a, and 358a in the radial space 15c. A gap 356s slenderly
extending in the front-rear direction is formed between the other
end side of the first top foil 358a and one end side of the first
top foil 356a. A gap 357s slenderly extending in the front-rear
direction is formed between the other end side of the first top
foil 356a and one end side of the first top foil 357a. A gap 358s
slenderly extending in the front-rear direction is formed between
the other end side of the first top foil 357 and one end side of
the first top foil 358a.
[0092] Two second radial foil bearings 359 and 360 are provided
between the second shaft supporting surface 315e and the second
shaft supported surface 53b. The second radial foil bearings 359
and 360 include second top foils 359a and 360a and second bump
foils 359b and 360b. In the second top foils 359a and 360a, second
keys 359k and 360k engaged in the second key grooves 315h and 316h
are formed. The second keys 359k and 360k engage in the second key
grooves 315h and 316h to thereby stop rotation of the second top
foils 359a and 360a in the radial space 15c. A gap 359s slenderly
extending in the front-rear direction is formed between one end
side of the second top foil 359a and the other end side of the
second top foil 360a. A gap 360s slenderly extending in the
front-rear direction is formed between the other end side of the
second top foil 359a and one end side of the second top foil
360a.
[0093] The first keys 356k, 357k, and 358k and the second keys 359k
and 360k shift from each other by about 30.degree. or by about
90.degree. centering on the rotational axis O. Therefore, the first
key 356k, the rotational axis O, the second key 360k, and the first
key 357k are respectively arranged such that the rotational axis O
is absent on an imaginary straight line L2 that connects the first
key 356k, the second key 360k, and the first key 357k. The first
key 356k, the rotational axis O, the second key 360k, and the first
key 357k are also respectively arranged such that the rotational
axis O is absent on an imaginary straight line L3 that connects the
first key 357k and the second key 359k. Further, the first key
356k, the rotational axis O, the second key 360k, and the first key
357k are also respectively arranged such that the rotational axis O
is absent on an imaginary straight line L4 that connects the first
key 358k, the second key 359k, and the first key 356k. The first
key 356k, the rotational axis O, the second key 360k, and the first
key 357k are also respectively arranged such that the rotational
axis O is absent on an imaginary straight line L5 that connects the
first key 358k and the second key 360k. The other components in the
turbo type compressor 300 are the same as the components of the
turbo type compressor 100 in the embodiment 1.
[0094] In the turbo type compressor 300, when the first key 356k
and the rotational axis O are connected by an imaginary straight
line, the gaps 359s and 360s of the second radial foil bearings 359
and 360 are absent on the imaginary straight line. When the first
key 357k and the rotational axis O are connected by an imaginary
straight line, the gaps 359s and 360s are absent on the imaginary
straight line. Further, when the first key 358k and the rotational
axis O are connected by an imaginary straight line, the gaps 359s
and 360s are absent on the imaginary straight line. That is, the
rotational axis O is absent on the imaginary straight lines L2, L3,
L4, and L5 that connect the first keys 356k, 357k, and 358k of the
first top foils 356a, 357a, and 358a in the first radial foil
bearings 356, 357, and 358 and the second keys 359k and 360k of the
second top foils 359a and 360a in the second radial foil bearings
359 and 360.
[0095] Therefore, in the turbo type compressor 300, even if the
refrigerant flows out from the gaps 356s, 357s, and 358s and the
dynamic pressure of the refrigerant is less effective between the
first shaft supported surface 53a and the first top foils 356a,
357a, and 358a, the dynamic pressure of the refrigerant acts
between the second shaft supported surface 53b and the second top
foils 359a and 360a located on extended lines of the imaginary
straight lines that connect the gaps 356s, 357s, and 358s and the
rotational axis O. In the turbo type compressor 300, even if the
refrigerant flows out from the gaps 359s and 360s and the dynamic
pressure of the refrigerant is less effective between the second
shaft supported surface 53b and the second top foils 359a and 360a,
the dynamic pressure of the refrigerant acts between the first
shaft supported surface 53a and the first top foils 358a and 359a
located on extended lines of the imaginary straight lines that
connect the gaps 359s and 360s and the rotational axis O.
Therefore, even if the second shaft supported surface 53b of the
second supported portion 53 in the rotating shaft 3 approach the
gaps 359s and 360s of the second top foils 359a and 360a, the first
shaft supported surface 53a of the second supported portion 53
hardly approaches the gaps 356s, 357s, and 358s of the first top
foils 356a, 357a, and 358a. The other action and effects in the
turbo type compressor 300 are the same as the action and effects of
the turbo type compressor 100 in the embodiment 1.
[0096] The present invention is explained above according to the
embodiments 1 to 3. However, the present invention is not limited
to the embodiments 1 to 3. It goes without saying that the present
invention can be changed as appropriate and applied without
departing from the gist of the present invention.
[0097] For example, in the embodiments, the turbo type compressors
100, 200, and 300 have the two stages of the compression phases by
the first and second impellers 7 and 9. However, the turbo type
compressors 100, 200, and 300 may have one compression process or
may have three or more compression phases.
[0098] In the embodiments, the present invention can be embodied as
a turbo type blower and the like besides the turbo type
compressor.
[0099] Further, in the embodiments, other shaft supporting surfaces
and other shaft supported surfaces may be further provided coaxial
with the rotational axis O and on the rotational axis O sides or
the outer circumference sides of the first and second shaft
supporting surfaces 15f, 215f, 315f, 15e, 215e, and 315e and the
first and second shaft supported surfaces 53a, 253a, 53b, and 253b.
Other radial foil bearings may be further provided between the
shaft supporting surfaces and the shaft supported surfaces.
[0100] In the embodiments, the first radial foil bearings 57, 257,
356, 357, and 358 including the one first top foil 57a and the one
first bump foil 57b and the three first top foils 356a, 357a, and
358a and the three first bump foils 356b, 357b, and 358b are used.
However, the first radial foil bearing may include two first top
foils and first bump foils or may include four first top foils and
first bump foils. As the second radial foil bearings 59, 259, 359,
and 360, second bump foils including three or more second top foils
and three or more second bump foils may be used. The first and
second thrust foil bearings 61, 261, 63, and 263 including two or
more first and second top foils and two or more first and second
bump foils may be used.
[0101] Further, in the embodiments, the first and second rotation
stop portions are not limited to the first and second keys 57k,
356k, 357k, 358k, 59k, 359k, and 360k. Various rotation stop means
can be adopted. For example, at least one of the first and second
top foils 57a, 356a, 357a, 358a, 59a, 359a, and 360a and the first
and second bump foils 57b, 356b, 357b, 358b, 59b, 359b, and 360b
may be welded to the first and second shaft supporting surfaces
15f, 215f, 315f, 15e, 215e, and 315e to stop rotation of the first
and second radial foil bearings 57, 257, 356, 357, 358, 59, 259,
359, and 360. At least one of the first and second top foils 57a,
356a, 357a, 358a, 59a, 359a, and 360a and the first and second bump
foils 57b, 356b, 357b, 358b, 59b, 359b, and 360b may be fit in the
first and second shaft supporting surfaces 15f, 215f, 315f, 15e,
215e, and 315e. The same applies to the third and fourth keys 13k
and 15k of the first and second thrust foil bearings 61, 261, 63,
and 263.
* * * * *