U.S. patent application number 17/238888 was filed with the patent office on 2021-11-04 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 Ryosuke FUKUYAMA, Shogo ITO, Yohei TAKASE, Kaho TAKEUCHI, Daisuke WATANABE.
Application Number | 20210340986 17/238888 |
Document ID | / |
Family ID | 1000005549320 |
Filed Date | 2021-11-04 |
United States Patent
Application |
20210340986 |
Kind Code |
A1 |
ITO; Shogo ; et al. |
November 4, 2021 |
CENTRIFUGAL COMPRESSOR
Abstract
A pressure relief passage includes a first pressure relief
passage and a second pressure relief passage. A pressure relief
hole is provided in an upper part of the first pressure relief
passage in the direction of gravitational force. The second
pressure relief passage merges with the first pressure relief
passage to form a merging portion. The cross-sectional flow area of
a stagnation portion, which is the maximum cross-sectional flow
area of the second pressure relief passage, is smaller than the
cross-sectional flow area of a connection passage, which is the
minimum cross-sectional flow area of the first pressure relief
passage.
Inventors: |
ITO; Shogo; (Kariya-shi,
JP) ; FUKUYAMA; Ryosuke; (Kariya-shi, JP) ;
TAKEUCHI; Kaho; (Kariya-shi, JP) ; WATANABE;
Daisuke; (Kariya-shi, JP) ; TAKASE; Yohei;
(Kariya-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
KABUSHIKI KAISHA TOYOTA JIDOSHOKKI |
Aichi-ken |
|
JP |
|
|
Assignee: |
KABUSHIKI KAISHA TOYOTA
JIDOSHOKKI
Aichi-ken
JP
|
Family ID: |
1000005549320 |
Appl. No.: |
17/238888 |
Filed: |
April 23, 2021 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F04D 17/10 20130101;
F04D 29/063 20130101; F04D 29/053 20130101; F04D 29/102
20130101 |
International
Class: |
F04D 17/10 20060101
F04D017/10; F04D 29/063 20060101 F04D029/063; F04D 29/10 20060101
F04D029/10; F04D 29/053 20060101 F04D029/053 |
Foreign Application Data
Date |
Code |
Application Number |
May 1, 2020 |
JP |
2020-081288 |
Claims
1. A centrifugal compressor, comprising: a low speed shaft that is
rotated by a drive source; an impeller that is attached to a high
speed shaft, which rotates at a speed higher than a speed of the
low speed shaft; a speed increaser that transmits power of the low
speed shaft to the high speed shaft; a housing that includes a
drive source chamber that accommodates the drive source, an
impeller chamber that accommodates the impeller, a speed increaser
chamber that accommodates the speed increaser, and a dividing wall
having an insertion hole through which the high speed shaft is
passed, the dividing wall dividing the impeller chamber and the
speed increaser chamber from each other; a seal member provided
between an outer circumferential surface of the high speed shaft
and an inner circumferential surface of the insertion hole; an oil
pan that stores oil supplied to the speed increaser; and a pressure
relief passage that connects an upper part of the oil pan to a
pressure relief hole that opens in an outer surface of the housing,
wherein the pressure relief passage includes a first pressure
relief passage and a second pressure relief passage, the pressure
relief hole is arranged above the first pressure relief passage in
a direction of gravitational force, the second pressure relief
passage merges with the first pressure relief passage to form a
merging portion, and a maximum cross-sectional flow area of the
second pressure relief passage is smaller than a minimum
cross-sectional flow area of the first pressure relief passage.
2. The centrifugal compressor according to claim 1, wherein the
pressure relief passage includes a detouring pressure relief
passage that extends, in a detouring manner, from a lower part of
the first pressure relief passage and is connected to an upper part
of the first pressure relief passage, and the maximum
cross-sectional flow area of the second pressure relief passage is
smaller than a minimum cross-sectional flow area of the detouring
pressure relief passage.
3. The centrifugal compressor according to claim 2, wherein the
detouring pressure relief passage and the second pressure relief
passage are connected to each other via a merging portion, the
housing includes a first side surface and a second side surface
that are opposed to each other, the merging portion is formed in an
upper region of the housing in a vicinity of the first side
surface, and the pressure relief hole is formed in an upper region
of the housing in a vicinity of the second side surface.
4. The centrifugal compressor according to claim 3, wherein the
second pressure relief passage includes a constriction between a
lower end connected to the upper part of the oil pan and an upper
end connected to the merging portion, and a cross-sectional flow
area of the constriction is smaller than a cross-sectional flow
area of the upper end and a cross-sectional flow area of the lower
end.
5. The centrifugal compressor according to claim 1, wherein the
pressure relief hole is arranged above the merging portion, and the
first pressure relief passage is arranged below the merging
portion.
6. A centrifugal compressor, comprising: a low speed shaft that is
rotated by a drive source; an impeller that is attached to a high
speed shaft, which rotates at a speed higher than a speed of the
low speed shaft; a speed increaser that transmits power of the low
speed shaft to the high speed shaft; a housing that includes a
drive source chamber that accommodates the drive source, an
impeller chamber that accommodates the impeller, a speed increaser
chamber that accommodates the speed increaser, and a dividing wall
having an insertion hole through which the high speed shaft is
passed, the dividing wall dividing the impeller chamber and the
speed increaser chamber from each other; a seal member provided
between an outer circumferential surface of the high speed shaft
and an inner circumferential surface of the insertion hole; an oil
pan that stores oil supplied to the speed increaser via an oil
passage; and a pressure relief passage that connects an upper part
of the oil pan to a pressure relief hole that opens in an outer
portion of the housing, wherein the pressure relief passage
includes a first pressure relief passage and a detouring pressure
relief passage, the pressure relief hole is arranged above the
first pressure relief passage in a direction of gravitational
force, the detouring pressure relief passage includes a detouring
pressure relief passage that extends, in a detouring manner, from a
lower part of the first pressure relief passage to a region located
in an upper part, and a minimum cross-sectional flow area of the
detouring pressure relief passage is smaller than a minimum
cross-sectional flow area of the first pressure relief passage.
Description
BACKGROUND
1. Field
[0001] The present disclosure relates to a centrifugal
compressor.
2. Description of Related Art
[0002] Japanese Laid-Open Patent Publication No. 2016-186238
discloses a centrifugal compressor. The centrifugal compressor
includes a low speed shaft, an impeller attached to a high speed
shaft, and a speed increaser that transmits power from the low
speed shaft to the high speed shaft. The centrifugal compressor
further includes a housing and a dividing wall. The housing
includes an impeller chamber, which accommodates the impeller, and
a speed increaser chamber, which accommodates the speed increaser.
The dividing wall divides the impeller chamber and the speed
increaser chamber from each other. The dividing wall has an
insertion hole through which the high speed shaft is passed. The
centrifugal compressor also includes a seal member, an oil pan, and
an oil passage. The seal member is provided between the outer
circumferential surface of the high speed shaft and the inner
circumferential surface of the insertion hole. The oil pan stores
oil to be supplied to the speed increaser. The oil passage supplies
oil stored in the oil pan to the speed increaser and returns the
oil to the oil pan. The oil supplied to the speed increaser reduces
friction and prevents seizure in sliding portions of the high speed
shaft and the speed increaser. The seal member prevents leakage of
the oil stored in the speed increaser chamber into the impeller
chamber through the insertion hole.
[0003] When gas is compressed through rotation of the impeller, the
internal pressure of the impeller chamber is increased. The
compressed gas flows from the edge of the back face of the impeller
to the clearance on the back face of the impeller. This increases
the pressure of the clearance on the back face of the impeller. The
gas may leak from the clearance on the back face of the impeller to
the speed increaser chamber through the gap between the outer
circumferential surface of the high speed shaft and the inner
circumferential surface of the insertion hole, which may increase
the pressure in the speed increaser chamber. Also, the pressure in
the impeller chamber may become lower than the pressure in the
speed increaser chamber, for example, when the impeller is rotating
at a low speed or when the centrifugal compressor is in a stopped
state. In this case, the oil in the speed increaser chamber may
leak to the impeller chamber through the gap between the outer
circumferential surface of the high speed shaft and the inner
circumferential surface of the insertion hole.
[0004] For example, Japanese Laid-Open Patent Publication No.
2019-157707 discloses a centrifugal compressor that includes a
pressure relief passage. The pressure relief passage connects an
oil pan and the outside of the centrifugal compressor (the
atmosphere side) to limit an increase in the pressure in the speed
increaser chamber. This configuration releases pressure through a
pressure relief hole of the pressure relief passage if the pressure
in the speed increaser chamber increases. This limits an increase
in the pressure in the speed increaser chamber.
[0005] Since oil is supplied to the speed increaser, the oil
accumulates in the speed increaser chamber. The oil accumulated in
the speed increaser chamber is stirred by the speed increaser. This
generates bubbles in the oil. The bubbles generated in the oil
reach the pressure relief passage from the speed increaser via the
oil pan, and are retained in the pressure relief passage. Thus,
when the bubbles in the oil are retained in the pressure relief
passage, the level of the oil rises. When the level of the oil
reaches the pressure relief hole of the pressure relief passage,
the oil may leak from the opening of the pressure relief hole.
SUMMARY
[0006] It is an objective of the present disclosure to provide a
centrifugal compressor that is capable of preventing the level of
oil from reaching a pressure relief hole of a pressure relief
passage.
[0007] This Summary is provided to introduce a selection of
concepts in a simplified form that are further described below in
the Detailed Description. This Summary is not intended to identify
key features or essential features of the claimed subject matter,
nor is it intended to be used as an aid in determining the scope of
the claimed subject matter.
[0008] In one general aspect, a centrifugal compressor includes a
low speed shaft that is rotated by a drive source, an impeller that
is attached to a high speed shaft, which rotates at a speed higher
than a speed of the low speed shaft, a speed increaser that
transmits power of the low speed shaft to the high speed shaft, a
housing, a seal member, an oil pan, and a pressure relief passage.
The housing includes a drive source chamber that accommodates the
drive source, an impeller chamber that accommodates the impeller, a
speed increaser chamber that accommodates the speed increaser, and
a dividing wall having an insertion hole through which the high
speed shaft is passed. The dividing wall divides the impeller
chamber and the speed increaser chamber from each other. The seal
member is provided between an outer circumferential surface of the
high speed shaft and an inner circumferential surface of the
insertion hole. The oil pan stores oil supplied to the speed
increaser. The pressure relief passage connects an upper part of
the oil pan to a pressure relief hole that opens in an outer
surface of the housing. The pressure relief passage includes a
first pressure relief passage and a second pressure relief passage.
The pressure relief hole is arranged above the first pressure
relief passage in a direction of gravitational force. The second
pressure relief passage merges with the first pressure relief
passage to form a merging portion. A maximum cross-sectional flow
area of the second pressure relief passage is smaller than a
minimum cross-sectional flow area of the first pressure relief
passage.
[0009] In another general aspect, a centrifugal compressor includes
a low speed shaft that is rotated by a drive source, an impeller
that is attached to a high speed shaft, which rotates at a speed
higher than a speed of the low speed shaft, a speed increaser that
transmits power of the low speed shaft to the high speed shaft, a
housing, a seal member, an oil pan, and a pressure relief passage.
The housing includes a drive source chamber that accommodates the
drive source, an impeller chamber that accommodates the impeller, a
speed increaser chamber that accommodates the speed increaser, and
a dividing wall having an insertion hole through which the high
speed shaft is passed. The dividing wall divides the impeller
chamber and the speed increaser chamber from each other. The seal
member is provided between an outer circumferential surface of the
high speed shaft and an inner circumferential surface of the
insertion hole. The oil pan stores oil supplied to the speed
increaser via an oil passage. The pressure relief passage connects
an upper part of the oil pan to a pressure relief hole that opens
in an outer portion of the housing. The pressure relief passage
includes a first pressure relief passage and a detouring pressure
relief passage. The pressure relief hole is arranged above the
first pressure relief passage in a direction of gravitational
force. The detouring pressure relief passage includes a detouring
pressure relief passage that extends, in a detouring manner, from a
lower part of the first pressure relief passage to a region located
in an upper part. A minimum cross-sectional flow area of the
detouring pressure relief passage is smaller than a minimum
cross-sectional flow area of the first pressure relief passage.
[0010] Other features and aspects will be apparent from the
following detailed description, the drawings, and the claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 is a cross-sectional side view showing a centrifugal
compressor according to an embodiment.
[0012] FIG. 2 is a cross-sectional view taken along line 2-2 in
FIG. 1.
[0013] FIG. 3 is a cross-sectional view taken along line 3-3 in
FIG. 1.
[0014] FIG. 4 is a cross-sectional view taken along line 4-4 in
FIG. 1.
[0015] FIG. 5 is a cross-sectional view taken along line 5-5 in
FIG. 1.
[0016] FIG. 6 is a cross-sectional view of a first passage and a
second passage according to a modification.
[0017] FIG. 7 is a cross-sectional view of a first passage and a
second passage according to another modification.
[0018] Throughout the drawings and the detailed description, the
same reference numerals refer to the same elements. The drawings
may not be to scale, and the relative size, proportions, and
depiction of elements in the drawings may be exaggerated for
clarity, illustration, and convenience.
DETAILED DESCRIPTION
[0019] This description provides a comprehensive understanding of
the methods, apparatuses, and/or systems described. Modifications
and equivalents of the methods, apparatuses, and/or systems
described are apparent to one of ordinary skill in the art.
Sequences of operations are exemplary, and may be changed as
apparent to one of ordinary skill in the art, with the exception of
operations necessarily occurring in a certain order. Descriptions
of functions and constructions that are well known to one of
ordinary skill in the art may be omitted.
[0020] Exemplary embodiments may have different forms, and are not
limited to the examples described. However, the examples described
are thorough and complete, and convey the full scope of the
disclosure to one of ordinary skill in the art.
[0021] A centrifugal compressor 10 according to an embodiment will
now be described with reference to FIGS. 1 to 5. The centrifugal
compressor 10 of the present embodiment is mounted on a fuel cell
vehicle that travels using a fuel cell as a power source. The
centrifugal compressor 10 supplies air to the fuel cell. In the
following description, the terms "upper," "upward," "above,"
"lower," "downward," "below," and other terms indicating vertical
positional relationships are defined with reference to the
direction of gravitational force.
[0022] As shown in FIG. 1, the centrifugal compressor 10 includes a
substantially tubular housing 11. The housing 11 includes a motor
housing member 12, a speed increaser housing member 13, a plate 14,
a compressor housing member 15, and a rear housing member 16. The
speed increaser housing member 13 is coupled to the motor housing
member 12. The plate 14 is coupled to the speed increaser housing
member 13. The compressor housing member 15 is coupled to the plate
14. The rear housing member 16 is coupled to the motor housing
member 12 on the side opposite to the speed increaser housing
member 13. The motor housing member 12 and the speed increaser
housing member 13 each have a cylindrical shape with a closed end.
The motor housing member 12, the speed increaser housing member 13,
the plate 14, the compressor housing member 15, and the rear
housing member 16 are made of metal such as aluminum, and are
arranged in that order in the axial direction of the housing
11.
[0023] The housing 11 includes a motor chamber 12c, which is a
drive source chamber accommodating an electric motor 18, a speed
increaser chamber 13c, which accommodates a speed increaser 30, and
an impeller chamber 15b, which accommodates an impeller 24. The
motor chamber 12c is defined by the inner surface of a disc-shaped
bottom wall 12a and the inner circumferential surface of a
peripheral wall 12b of the motor housing member 12, and the outer
surface of a bottom wall 13a of the speed increaser housing member
13. That is, an opening of the peripheral wall 12b on a side
opposite to the bottom wall 12a is closed by the bottom wall 13a of
the speed increaser housing member 13. The bottom wall 12a has a
tubular boss 12f protruding from the inner surface. The rear
housing member 16 is coupled to the bottom wall 12a. The rear
housing member 16 has an insertion hole 16a in a center portion. A
low speed shaft 17, which extends through the bottom wall 12a, is
passed through the insertion hole 16a. The low speed shaft 17 will
be discussed below. The motor housing member 12 and the rear
housing member 16 are fastened to each other by bolts 80. The bolts
80 extend through the rear housing member 16 and are threaded to
the bottom wall 12a of the motor housing member 12.
[0024] The speed increaser chamber 13c is defined by the inner
surface of the disc-shaped bottom wall 13a and the inner
circumferential surface of the peripheral wall 13b of the speed
increaser housing member 13, and the plate 14. That is, an opening
of the peripheral wall 13b on a side opposite to the bottom wall
13a is closed by a surface 14a of the plate 14. The bottom wall 13a
has a through-hole 13h in a center portion. The speed increaser
chamber 13c stores oil.
[0025] The impeller chamber 15b is defined by the compressor
housing member 15 and the plate 14. The compressor housing member
15 is coupled to a surface of the plate 14 on a side opposite to
the speed increaser housing member 13. The compressor housing
member 15 includes a suction port 15a, through which air, which is
fluid, is drawn in. The suction port 15a is located at in a center
portion of the end face of the compressor housing member 15 on the
side opposite to the plate 14. The suction port 15a extends in the
axial direction of the housing 11 from the center portion of that
end face of the compressor housing member 15. The impeller chamber
15b and the suction port 15a are connected to each other. The
impeller chamber 15b is substantially truncated cone-shaped with
its diameter gradually increasing as the distance from the suction
port 15a increases. A high speed shaft 31, which will be discussed
below, protrudes into the compressor housing member 15.
[0026] The plate 14 is a dividing wall that divides the impeller
chamber 15b and the speed increaser chamber 13c from each other.
The plate 14 has an insertion hole 14h, through which the high
speed shaft 31 is passed.
[0027] As shown in FIG. 1, the centrifugal compressor 10 includes
the electric motor 18, which is a drive source, the low speed shaft
17, which is rotated by the electric motor 18, the high speed shaft
31, which rotates at a speed higher than the speed of the low speed
shaft 17, and the speed increaser 30, which transmits the power of
the low speed shaft 17 to the high speed shaft 31.
[0028] The electric motor 18 includes a tubular stator 22 and a
rotor 23, which is arranged on the inner side of the stator 22. The
rotor 23 is fixed to the low speed shaft 17 and rotates integrally
with the low speed shaft 17. The stator 22 surrounds the rotor 23.
The rotor 23 includes a cylindrical rotor core 23a, which is fixed
to the low speed shaft 17, and permanent magnets (not shown), which
are provided in the rotor core 23a. The stator 22 includes a
tubular stator core 22a and a coil 22b. The stator core 22a is
fixed to the inner circumferential surface of the peripheral wall
12b of the motor housing member 12. The coil 22b is wound about the
stator core 22a. Current through the coil 22b causes the rotor 23
and the low speed shaft 17 to rotate integrally.
[0029] The axial direction of the low speed shaft 17 agrees with
the axial direction of the motor housing member 12. In this state,
the low speed shaft 17 is accommodated in the motor housing member
12. The low speed shaft 17 has a first end inserted into the boss
12f. A first bearing 19 is provided between the first end of the
low speed shaft 17 and the boss 12f. The first end of the low speed
shaft 17 is rotationally supported by the bottom wall 12a of the
motor housing member 12 with the first bearing 19. The first end of
the low speed shaft 17 is passed through the bottom wall 12a of the
motor housing member 12 and the insertion hole 16a of the rear
housing member 16, and protrudes to the outside.
[0030] The low speed shaft 17 has a second end inserted into the
through-hole 13h. A second bearing 20 is provided between the
second end of the low speed shaft 17 and the through-hole 13h. The
second end of the low speed shaft 17 is rotationally supported by
the bottom wall 13a of the speed increaser housing member 13 with
the second bearing 20. The low speed shaft 17 is thus rotationally
supported by the housing 11. The second end of the low speed shaft
17 extends from the motor chamber 12c through the through-hole 13h,
and protrudes into the speed increaser housing member 13.
[0031] A seal member 21 is provided between the second end of the
low speed shaft 17 and the inner circumferential surface of the
through-hole 13h. The seal member 21 is arranged between the second
bearing 20 and the motor chamber 12c. The seal member 21 prevents
leakage of oil stored in the speed increaser chamber 13c to the
motor chamber 12c through the gap between the outer circumferential
surface of the low speed shaft 17 and the inner circumferential
surface of the through-hole 13h.
[0032] The high speed shaft 31 is accommodated in the speed
increaser chamber 13c. An end of the high speed shaft 31 that is on
a side opposite to the motor housing member 12 extends through the
insertion hole 14h of the plate 14 and protrudes into the
compressor housing member 15. The axis of the high speed shaft 31
agrees with the axis of the low speed shaft 17.
[0033] The speed increaser 30 accelerates rotation of the low speed
shaft 17 and transmits the rotation to the high speed shaft 31. The
speed increaser 30 is of a traction drive type (a friction roller
type). The speed increaser 30 includes a ring member 32, which is
coupled to the second end of the low speed shaft 17. The ring
member 32 is made of metal. The ring member 32 includes a
disc-shaped base 33, which is coupled to the second end of the low
speed shaft 17, and a tubular portion 34, which cylindrically
extends from the outer edge of the base 33. The ring member 32 has
a cylindrical shape with a closed end. The base 33 extends in the
radial direction of the low speed shaft 17 with respect to the low
speed shaft 17. The axis of the tubular portion 34 agrees with the
axis of the low speed shaft 17.
[0034] As shown in FIG. 2, part of the high speed shaft 31 is
arranged inward of the tubular portion 34. The speed increaser 30
includes three rollers 35, which are provided between the tubular
portion 34 and the high speed shaft 31. The three rollers 35 are
arranged at predetermined intervals (for example, 120 degrees) in
the circumferential direction of the high speed shaft 31. The three
rollers 35 have the same shape. The three rollers 35 contact both
of the inner circumferential surface of the tubular portion 34 and
the outer circumferential surface of the high speed shaft 31.
[0035] As shown in FIG. 1, each roller 35 includes a columnar
roller portion 35a, a columnar first protrusion 35c, and a columnar
second protrusion 35e. The first protrusion 35c protrudes from a
first end face 35b in the axial direction of the roller portion
35a. The second protrusion 35e protrudes from a second end face 35d
in the axial direction of the roller portion 35a. The axis of the
roller portion 35a, the axis of the first protrusion 35c, and the
axis of the second protrusion 35e agree with one another. The axial
direction of the roller portion 35a of each roller 35 and the axial
direction of the high speed shaft 31 agree with each other.
[0036] As shown in FIGS. 1 and 2, the speed increaser 30 includes a
support member 39, which cooperates with the plate 14 to
rotationally support the rollers 35. The support member 39 is
arranged inward of the tubular portion 34. The support member 39
includes a disc-shaped support base 40 and three pillar-shaped
upright walls 41, which project from the support base 40. The
support base 40 is arranged to be opposed to the plate 14 in the
axial direction of the rollers 35. The three upright walls 41
extend toward the plate 14 from a surface 40a of the support base
40 that is closest to the plate 14. The three upright walls 41 are
arranged so as to fill the three spaces, each of which is defined
by the outer circumferential surfaces of adjacent two of the roller
portions 35a and the inner circumferential surface of the tubular
portion 34.
[0037] The support member 39 has three bolt insertion holes 45,
through which bolts 44 are passed. Each bolt insertion hole 45
extends in the axial direction of the rollers 35 through
corresponding one of the three upright walls 41. As shown in FIG.
1, the plate 14 has internal thread holes 46 in the surface 14a,
which is closest to the support member 39. The internal thread
holes 46 are connected to the bolt insertion holes 45. The support
member 39 is attached to the plate 14 by threading the bolts 44,
which are passed through the bolt insertion holes 45, into the
internal thread holes 46.
[0038] The plate 14 has three recesses 51 (only one of the recesses
51 is shown in FIG. 1) in the surface 14a. The three recesses 51
are arranged at predetermined intervals (for example, 120 degrees)
in the circumferential direction of the high speed shaft 31. The
three recesses 51 each receive an annular roller bearing 52.
[0039] The support base 40 has three recesses 53 (only one of the
recesses 53 is shown in FIG. 1) in the surface 40a that is closest
to the plate 14. The three recesses 53 are arranged at
predetermined intervals (for example, 120 degrees) in the
circumferential direction of the high speed shaft 31. The three
recesses 53 each receive an annular roller bearing 54.
[0040] The first protrusion 35c of each roller 35 is inserted into
the roller bearing 52 in the corresponding recess 51, and is
rotationally supported by the plate 14 with the roller bearing 52.
The second protrusion 35e of each roller 35 is inserted into the
roller bearing 54 in the corresponding recess 53, and is
rotationally supported by the support member 39 with the roller
bearing 54.
[0041] The high speed shaft 31 includes two flanges 31f, which are
arranged at positions spaced apart to be opposed to each other in
the axial direction of the high speed shaft 31. The roller portions
35a of the three rollers 35 are held by the two flanges 31f. This
prevents positional displacement of the high speed shaft 31 and the
roller portions 35a of the three rollers 35 in the axial direction
of the high speed shaft 31.
[0042] As shown in FIG. 2, the three rollers 35 are pressed against
the high speed shaft 31 and the tubular portion 34. The three
rollers 35, the ring member 32, and the high speed shaft 31 are
unitized in this state. The high speed shaft 31 is rotationally
supported by the three rollers 35.
[0043] The contacting section between the outer circumferential
surface of the roller portion 35a of each of the three rollers 35
and the inner circumferential surface of the tubular portion 34 is
referred to as a ring-side contacting section Pa, to which pressing
load is applied. The contacting section between the outer
circumferential surface of each of the three rollers 35 and the
outer circumferential surface of the high speed shaft 31 is
referred to as a shaft-side contacting section Pb, to which
pressing load is applied. The ring-side contacting sections Pa and
the shaft-side contacting sections Pb extend in the axial direction
of the high speed shaft 31.
[0044] As shown in FIG. 1, the centrifugal compressor 10 includes
the impeller 24, which is attached to the high speed shaft 31. The
impeller 24 is tubular and has a diameter that gradually decreases
from a proximal end face 24a toward a distal end face 24b. The
impeller 24 has an insertion hole 24c, which extends in the axial
direction of the impeller 24. The high speed shaft 31 can be passed
through the insertion hole 24c. The end of the high speed shaft 31
that protrudes into the compressor housing member 15 is passed
through the insertion hole 24c. The impeller 24 is attached to the
high speed shaft 31 in this state. When the high speed shaft 31
rotates, the impeller 24 rotates, so that air drawn through the
suction port 15a is compressed. The impeller 24 rotates integrally
with the high speed shaft 31 to compress the air. The proximal end
face 24a is an impeller back face.
[0045] As shown in FIG. 1, the centrifugal compressor 10 includes a
diffuser passage 25, into which the air compressed by the impeller
24 flows, and a discharge chamber 26, into which the air that has
passed through the diffuser passage 25 flows.
[0046] As shown in FIG. 1, the diffuser passage 25 is defined by
the surface of the compressor housing member 15 that is opposed to
the plate 14 and the surface of the plate 14 that is opposed to the
compressor housing member 15. The diffuser passage 25 is located
outward of the impeller chamber 15b in the radial direction of the
high speed shaft 31, surrounding the impeller chamber 15b. The
diffuser passage 25 is annular.
[0047] As shown in FIG. 1, the discharge chamber 26 is located
outward of the diffuser passage 25 in the radial direction of the
high speed shaft 31, and is connected to the diffuser passage 25.
The discharge chamber 26 is annular. The impeller chamber 15b and
the discharge chamber 26 are connected to each other by the
diffuser passage 25. Air that has been compressed by the impeller
24 flows through the diffuser passage 25 to be compressed further,
and flows to the discharge chamber 26 to be discharged from the
discharge chamber 26.
[0048] As shown in FIG. 1, the centrifugal compressor 10 includes a
seal member 71 provided in the insertion hole 14h. The seal member
71 is provided between the outer circumferential surface of the
high speed shaft 31 and the inner circumferential surface of the
insertion hole 14h. The seal member 71 is a mechanical seal. The
seal member 71 prevents leakage of oil stored in the speed
increaser chamber 13c to the impeller chamber 15b through the
insertion hole 14h.
[0049] As shown in FIG. 1, the centrifugal compressor 10 includes
an oil pan 56, an oil passage 60, an oil cooler 55, and an oil pump
57. The oil pan 56 stores oil supplied to the speed increaser 30.
The oil passage 60 supplies oil stored in the oil pan 56 to the
speed increaser 30, and returns the oil to the oil pan 56. The oil
cooler 55 cools oil flowing to the oil passage 60. The oil pump 57
pumps the oil stored in the oil pan 56 and discharges the oil.
[0050] As shown in FIG. 1, the oil passage 60 includes a first
connection passage 61, which connects the speed increaser chamber
13c and the oil cooler 55 to each other. The first connection
passage 61 has a first end, which opens in the speed increaser
chamber 13c. The first connection passage 61 has a second end,
which is connected to the oil cooler 55.
[0051] The centrifugal compressor 10 is mounted on the fuel cell
vehicle such that the opening of the first connection passage 61
that opens in the speed increaser chamber 13c is located in the
lower part.
[0052] The oil passage 60 includes a second connection passage 62,
which connects the oil cooler 55 and the oil pan 56 to each other.
The second connection passage 62 has a first end, which is
connected to the oil cooler 55. The second connection passage 62
has a second end, which opens in the oil pan 56.
[0053] The oil passage 60 includes a third connection passage 63,
which connects the oil pan 56 and the oil pump 57 to each other.
The third connection passage 63 is formed in the rear housing
member 16. The third connection passage 63 has a first end, which
protrudes into the oil pan 56. The third connection passage 63 has
a second end, which is connected to a suction port 57a of the oil
pump 57.
[0054] The oil passage 60 is connected to a discharge port 57b of
the oil pump 57. The oil passage 60 extends into the peripheral
wall 13b of the speed increaser housing member 13 via the rear
housing member 16 and the peripheral wall 12b of the motor housing
member 12. A fourth connection passage 64 has a first end, which is
connected to the discharge port 57b of the oil pump 57. The fourth
connection passage 64 has a second end, which is located inside the
peripheral wall 13b of the speed increaser housing member 13.
[0055] The oil passage 60 includes a first branch passage 65 and a
second branch passage 66, which branch from the second end of the
fourth connection passage 64. The first branch passage 65 extends
toward the motor housing member 12 from the second end of the
fourth connection passage 64, and opens in the through-hole
13h.
[0056] The second branch passage 66 extends toward the plate 14
from the second end of the fourth connection passage 64. The second
branch passage 66 opens in the peripheral wall 13b of the speed
increaser housing member 13.
[0057] The oil passage 60 includes a common passage 67, which is
connected to the second branch passage 66. The common passage 67
has a first end, which is connected to the second branch passage
66. The common passage 67 has a second end, which is located inside
the plate 14. The oil passage 60 includes a seal member-side supply
passage 69 and a speed increaser-side supply passages 70, which
branch from the second end of the common passage 67. The seal
member-side supply passage 69 has a first end, which is connected
to the common passage 67. The seal member-side supply passage 69
has a second end, which opens in the insertion hole 14h. Each speed
increaser-side supply passage 70 has a first end, which is
connected to the common passage 67. The seal member-side supply
passage 69 has a second end, which opens in a section in the
corresponding upright wall 41 that is opposed to the outer
circumferential surface of the corresponding roller portion 35a.
The speed increaser-side supply passages 70 are thus connected to
the speed increaser chamber 13c.
[0058] The centrifugal compressor 10 includes a pressure relief
passage 90, which connects the upper part of the oil pan 56 and a
pressure relief hole 90b, which opens in the outer surface of the
housing 11, to each other.
[0059] As shown in FIGS. 1, 3, and 4, the pressure relief passage
90 includes a connection passage 90a, a first buffer chamber 91, a
second buffer chamber 92, and a communicating passage 93. The
connection passage 90a, the first buffer chamber 91, the second
buffer chamber 92, and the communicating passage 93 are formed in
the rear housing member 16.
[0060] The first buffer chamber 91 is arranged above the oil pan
56. The first buffer chamber 91 has a rectangular shape extending
in the direction of gravitational force when viewed in the axial
direction of the low speed shaft 17 and in the radial direction of
the low speed shaft 17. The connection passage 90a connects the oil
pan 56 and the first buffer chamber 91 to each other. The
connection passage 90a has a first end, which opens in the upper
part in the oil pan 56. The connection passage 90a has a second
end, which opens in the lower part in the first buffer chamber 91.
The connection passage 90a has a rectangular shape extending in the
direction of gravitational force when viewed in the axial direction
of the low speed shaft 17. The connection passage 90a has a
rectangular shape extending in the direction of gravitational force
when viewed in the radial direction of the low speed shaft 17. As
shown in FIG. 1, in the axial direction of the low speed shaft 17,
the width of the connection passage 90a and the width of the first
buffer chamber 91 are the same (a width H1). In the axial direction
of the low speed shaft 17, the position of the connection passage
90a and the position of the first buffer chamber 91 agree with each
other. As shown in FIG. 3, in the radial direction of the low speed
shaft 17, a width H3 of the connection passage 90a is smaller than
a width H4 of the first buffer chamber 91.
[0061] As shown in FIGS. 1, 3, and 4, the second buffer chamber 92
is connected to the oil pan 56. The second buffer chamber 92
extends upward from the oil pan 56 and is parallel with the first
buffer chamber 91. The second buffer chamber 92 extends to a height
comparable to the height of the first buffer chamber 91 in the
direction of gravitational force.
[0062] Among the horizontal directions, which are perpendicular to
the direction of gravitational force, a direction that is
perpendicular to the low speed shaft 17 is defined as a first
horizontal direction A. As shown in FIG. 1, the second buffer
chamber 92 has a rectangular shape extending in the direction of
gravitational force when viewed in the first horizontal direction
A. In the axial direction of the low speed shaft 17, a width H2 of
the second buffer chamber 92 is the same as the width H1 of the
connection passage 90a and the first buffer chamber 91.
[0063] The connection passage 90a and the first buffer chamber 91
are displaced from the second buffer chamber 92 in the axial
direction of the low speed shaft 17. The second buffer chamber 92
is arranged between the first buffer chamber 91 and the motor
housing member 12 in the axial direction of the low speed shaft
17.
[0064] As shown in FIGS. 3 and 4, the first buffer chamber 91 and
the second buffer chamber 92 are displaced from each other in the
first horizontal direction A when viewed in the axial direction of
the low speed shaft 17.
[0065] The housing 11 has a first side surface 91a and a second
side surface 91b, which are opposed to each other in the first
horizontal direction A and define the first buffer chamber 91. The
first side surface 91a is located closest to the second buffer
chamber 92, and the second side surface 91b is located on a side
opposite to the second buffer chamber 92. The housing 11 has a
first side surface 92a and a second side surface 92b, which are
opposed to each other in the first horizontal direction A and
define the second buffer chamber 92. When the second buffer chamber
92 is viewed in the axial direction of the low speed shaft 17, the
second buffer chamber 92 is adjacent to the first side surface 91a
in the first horizontal direction A. When the second buffer chamber
92 is viewed in the axial direction of the low speed shaft 17, the
first side surface 92a is adjacent to the first side surface 91a in
the first horizontal direction A. In the first horizontal direction
A, the second side surface 92b is on the side opposite to the first
buffer chamber 91.
[0066] As shown in FIGS. 1, 3, and 4, the communicating passage 93
connects the first buffer chamber 91 and the second buffer chamber
92 to each other. The communicating passage 93 connects the upper
part of the first buffer chamber 91 and the upper part of the
second buffer chamber 92 to each other. The communicating passage
93 extends in the axial direction of the low speed shaft 17.
[0067] As shown in FIGS. 1 and 3, a rectangular pillar-shaped
protrusion 16b is arranged in the first buffer chamber 91. The
protrusion 16b has an insertion hole 16a, through which the low
speed shaft 17 is passed. In the first buffer chamber 91, the
protrusion 16b is arranged to connect two inner walls that are
opposed to each other in the axial direction of the low speed shaft
17. The protrusion 16b is formed integrally with the two inner
walls.
[0068] As shown in FIG. 3, the protrusion 16b is located halfway
between the first side surface 91a and the second side surface 91b
in the first horizontal direction A. The protrusion 16b is located
between the upper part of the first buffer chamber 91 and the lower
part of the first buffer chamber 91. The protrusion 16b is arranged
at a position below the center of the first buffer chamber 91 in
the direction of gravitational force.
[0069] The cross section of the protrusion 16b when cut in the
radial direction of the low speed shaft 17 is square. The width of
the space between the first side surface 91a and a side surface of
the protrusion 16b that is opposed to the first side surface 91a is
defined as a width W1. The width of the space between the second
side surface 91b and a side surface of the protrusion 16b that is
opposed to the second side surface 91b is defined as a width W2.
The width W1 and the width W2 are equal to each other. The width of
the space between the lower part of the first buffer chamber 91 and
a side surface of the protrusion 16b that is opposed to the lower
part of first buffer chamber 91 is defined as a width W3. The width
W3 is the same as the widths W1, W2. The widths W1, W2, W3 are
larger than the width H3 of the connection passage 90a.
[0070] The first buffer chamber 91 includes a first passage 911
formed between the protrusion 16b and the second side surface 91b.
The first buffer chamber 91 includes a second passage 912. The
second passage 912 includes a passage formed between the protrusion
16b and the lower part of the first buffer chamber 91, and a
passage formed between the protrusion 16b and the first side
surface 91a. The lower part of the first passage 911 is connected
to the connection passage 90a. The second passage 912 extends from
the first passage 911 toward the first side surface 91a and extends
upward, detouring the protrusion 16b. The first passage 911 and the
second passage 912 are connected to each other in a region in the
first buffer chamber 91 that is above the protrusion 16b. The first
passage 911 and the second passage 912 share the region in the
first buffer chamber 91 that is above the protrusion 16b. Three of
the bolts 80 that fasten the motor housing member 12 and the rear
housing member 16 together are passed through the protrusion
16b.
[0071] As shown in FIG. 1, the pressure relief hole 90b is formed
in the wall of the rear housing member 16 that is on the side
opposite to the motor housing member 12. The pressure relief hole
90b has a first end, which opens in the upper part in the first
buffer chamber 91. The pressure relief hole 90b has a second end,
which opens in the outer surface of the rear housing member 16.
That is, the first buffer chamber 91 is connected to the outside of
the housing 11 via the pressure relief hole 90b.
[0072] The pressure relief hole 90b is formed to extend in the
axial direction of the low speed shaft 17. A pressure relief pipe
94 is provided on the outer surface of the rear housing member 16
in which the pressure relief hole 90b opens. The pressure relief
pipe 94 is a tubular member that is bent in an L-shape. The
pressure relief pipe 94 has a first end, which is connected to the
pressure relief hole 90b. The pressure relief pipe 94 has a second
end, which is located above the first end of the pressure relief
pipe 94 and opens upward. A ventilation film 90c is arranged in the
second end of the pressure relief pipe 94. The ventilation film 90c
allows passage of gas but blocks liquid.
[0073] As shown in FIGS. 3 and 4, the connection passage 90a, the
first passage 911, and the region in the first buffer chamber 91
that is above the protrusion 16b form a first pressure relief
passage 95. The pressure relief passage 90 thus includes the first
pressure relief passage 95. The pressure relief hole 90b is
provided in the upper part of the first pressure relief passage
95.
[0074] The second passage 912 and the region in the first buffer
chamber 91 that is above the protrusion 16b form a detouring
pressure relief passage 97. The pressure relief passage 90 thus
includes the detouring pressure relief passage 97. The first
passage 911 and the second passage 912 share a region in the upper
part in the first buffer chamber 91. Therefore, the detouring
pressure relief passage 97 extends from the lower part of the first
pressure relief passage 95 to the region above the protrusion 16b,
detouring the protrusion 16b.
[0075] The second buffer chamber 92 and the communicating passage
93 form a second pressure relief passage 96. The pressure relief
passage 90 thus includes the second pressure relief passage 96. The
second pressure relief passage 96 is connected, by the
communicating passage 93, to the upper region in the first buffer
chamber 91 that is close to the first side surface 91a. The first
pressure relief passage 95 and the second pressure relief passage
96 extend from the oil pan 56 in a branching manner. The second
pressure relief passage 96 merges with the first pressure relief
passage 95 to form a merging portion 98. The merging portion 98
refers to a connection portion at which the first buffer chamber 91
and the communicating passage 93 are connected to each other.
[0076] The first pressure relief passage 95 and the detouring
pressure relief passage 97 share the region in the upper part in
the first buffer chamber 91. The detouring pressure relief passage
97 and the second pressure relief passage 96 are thus connected to
the merging portion 98.
[0077] The merging portion 98 is arranged in a region above the
second passage 912, which is formed in the vicinity of the first
side surface 91a. The merging portion 98 is formed in an upper
region in the vicinity of the first side surface 92a of the second
buffer chamber 92 in the first horizontal direction A. Accordingly,
the first pressure relief passage 95 and the detouring pressure
relief passage 97 are provided below the merging portion 98.
[0078] The pressure relief hole 90b is arranged in a region above
the first passage 911, which is formed in the vicinity of the
second side surface 91b. The pressure relief hole 90b is formed in
an upper region in the direction of gravitational force that is in
the vicinity of the second side surface 91b of the first buffer
chamber 91 in the first horizontal direction A.
[0079] The pressure relief hole 90b and the merging portion 98 are
spaced apart from each other in the first horizontal direction A.
When the position in the direction of gravitational force is
referred to as a height, the height of the merging portion 98 from
the oil pan 56 is smaller than the height of the pressure relief
hole 90b from the oil pan 56. That is, the pressure relief hole 90b
is arranged at a position diagonally above the merging portion 98.
That is, the pressure relief hole 90b is arranged above the merging
portion 98.
[0080] As shown FIG. 4, the second buffer chamber 92 includes a
proximal side passage 92c, an upper side passage 92d, and a
stagnation portion 92e. The proximal side passage 92c is the lower
end of the second pressure relief passage 96 and is connected to
the upper part of the oil pan 56. The stagnation portion 92e is the
upper end of the second pressure relief passage 96 and is connected
to the communicating passage 93.
[0081] The proximal side passage 92c extends upward from the oil
pan 56. The proximal side passage 92c has a first end, which is
connected to the oil pan 56. The proximal side passage 92c has a
second end, which is located above the oil pump 57. A width H5 of
the proximal side passage 92c in the first horizontal direction A
is smaller than the width H3 of the connection passage 90a.
[0082] The upper side passage 92d is connected to the proximal side
passage 92c. The upper side passage 92d extends upward from the
second end of the proximal side passage 92c. The upper side passage
92d has a first end, which is connected to the second end of the
proximal side passage 92c. The upper side passage 92d is formed to
extend among the bolts 80 that are not the three bolts 80 used to
fix the oil pump 57. A width H6 of the upper side passage 92d in
the first horizontal direction A is smaller than the width H5 of
the proximal side passage 92c. The distance in the first horizontal
direction A between the bolts 80 on the opposite sides of the upper
side passage 92d is set such that the cross-sectional flow area of
the upper side passage 92d is smaller than the cross-sectional flow
area of the proximal side passage 92c.
[0083] The stagnation portion 92e is connected to the upper side
passage 92d. The stagnation portion 92e is connected to the second
end of the upper side passage 92d. The stagnation portion 92e is
formed in the end of the second buffer chamber 92 that is on a side
opposite to the oil pan 56. A width H7 of the stagnation portion
92e is larger than the width H5 of the proximal side passage 92c
and the width H6 of the upper side passage 92d.
[0084] The stagnation portion 92e includes a wall surface 92f,
which is located on a side opposite to the upper side passage 92d
and intersects with the direction of gravitational force. The wall
surface 92f extends in the first horizontal direction A. The
stagnation portion 92e is formed in the upper part of the second
buffer chamber 92.
[0085] As shown in FIGS. 3 and 4, an upper region of the first
buffer chamber 91 in the vicinity of the first side surface 91a and
a part of the stagnation portion 92e, which is an upper region of
the second buffer chamber 92 in the vicinity of the first side
surface 92a, overlap with each other in the axial direction of the
low speed shaft 17.
[0086] The communicating passage 93 is formed in a part in which
the upper regions of the first buffer chamber 91 and the second
buffer chamber 92 overlap with each other in the axial direction of
the low speed shaft 17. The communicating passage 93 extends in the
axial direction of the low speed shaft 17. The communicating
passage 93 connects the second buffer chamber 92 and the first
buffer chamber 91 to each other on the downstream side in the
flowing direction of oil in relation to the wall surface 92f of the
stagnation portion 92e.
[0087] As shown FIG. 5, the direction in which the second buffer
chamber 92 extends and the direction in which the communicating
passage 93 extends intersect with each other. The direction in
which the second pressure relief passage 96 extends from the oil
pan 56 is bent toward the communicating passage 93. That is, the
direction in which oil flows is changed from the direction of
gravitational force to the axial direction of the low speed shaft
17.
[0088] The cross-sectional flow areas of the first pressure relief
passage 95, the second pressure relief passage 96, and the
detouring pressure relief passage 97 in the pressure relief passage
90 will now be described. The cross-sectional flow areas refer to
cross-sectional areas when the passage is cut in a direction
perpendicular to the flowing direction of oil.
[0089] As shown in FIGS. 3 and 4, in the first pressure relief
passage 95, the cross-sectional flow area of the connection passage
90a is smaller than the cross-sectional flow area of the first
passage 911. The cross-sectional flow areas of the connection
passage 90a and the first passage 911 are smaller than the
cross-sectional flow area of the region in the first buffer chamber
91 above the protrusion 16b. That is, the minimum cross-sectional
flow area of the first pressure relief passage 95 is the
cross-sectional flow area of the connection passage 90a.
[0090] In the detouring pressure relief passage 97, the
cross-sectional flow area of a passage formed between the
protrusion 16b and the lower part of the first buffer chamber 91
and the cross-sectional flow area of a passage formed between the
protrusion 16b and the first side surface 91a are the minimum
cross-sectional flow areas. In the present embodiment, the minimum
cross-sectional flow area of the detouring pressure relief passage
97 is the same as the cross-sectional flow area of the first
passage 911.
[0091] In the second pressure relief passage 96, the
cross-sectional flow area of the proximal side passage 92c is
larger than the cross-sectional flow area of the upper side passage
92d. The cross-sectional flow areas of the proximal side passage
92c and the upper side passage 92d are smaller than the
cross-sectional flow area of the stagnation portion 92e. The
cross-sectional flow areas of the proximal side passage 92c and the
upper side passage 92d are larger than the cross-sectional flow
area of the communicating passage 93. That is, the largest
cross-sectional flow area of the second pressure relief passage 96
is the cross-sectional flow area of the stagnation portion 92e. The
minimum cross-sectional flow area of the second pressure relief
passage 96 is the cross-sectional flow area of the communicating
passage 93. The cross-sectional flow area of the communicating
passage 93 is smaller than the cross-sectional flow area of the
connection passage 90a, which is the minimum cross-sectional flow
area of the first pressure relief passage 95. The cross-sectional
flow area of the upper side passage 92d is smaller than the
cross-sectional flow areas of the stagnation portion 92e and the
proximal side passage 92c. In the second pressure relief passage
96, the upper side passage 92d serves as a constriction.
[0092] The cross-sectional flow area of the stagnation portion 92e,
which is the largest cross-sectional flow area of the second
pressure relief passage 96, is smaller than the cross-sectional
flow area of the connection passage 90a, which is the minimum
cross-sectional flow area of the first pressure relief passage 95.
That is, the cross-sectional flow area of the second pressure
relief passage 96 is smaller than the cross-sectional flow area of
the first pressure relief passage 95 over the entire length in the
direction of gravitational force. The cross-sectional flow area of
the stagnation portion 92e, which is the largest cross-sectional
flow area of the second pressure relief passage 96, is smaller than
the cross-sectional flow area of the second passage 912, which is
the minimum cross-sectional flow area of the detouring pressure
relief passage 97.
[0093] An operation of the present embodiment will now be
described.
[0094] When the electric motor 18 is activated, rotation of the low
speed shaft 17 drives the oil pump 57. Then, the oil stored in the
oil pan 56 is drawn into the oil pump 57 through the third
connection passage 63 and the suction port 57a, and discharged to
the fourth connection passage 64 through the discharge port 57b.
The oil discharged to the fourth connection passage 64 flows
through the fourth connection passage 64 to be distributed to the
first branch passage 65 and the second branch passage 66.
[0095] The oil distributed to the first branch passage 65 from the
fourth connection passage 64 flows through the first branch passage
65 and into the through-hole 13h to be supplied to the seal member
21 and the second bearing 20. This ensures favorable lubrication of
the sliding portions of the seal member 21 and the low speed shaft
17, and the sliding portions of the second bearing 20 and the low
speed shaft 17.
[0096] The oil distributed to the second branch passage 66 from the
fourth connection passage 64 flows into the common passage 67 via
the second branch passage 66. Some of the oil that flows in the
common passage 67 is distributed to the seal member-side supply
passage 69, and the remaining oil flows in the speed increaser-side
supply passages 70. The oil that is distributed to the seal
member-side supply passage 69 from the common passage 67 flows in
the seal member-side supply passage 69 to flow into the insertion
hole 14h to be supplied to the seal member 71. The oil that flows
in the speed increaser-side supply passages 70 is supplied to the
outer circumferential surfaces of the roller portions 35a. This
ensures favorable lubrication of the sliding portions of the roller
portions 35a and the high speed shaft 31. The oil supplied to the
seal member 71 and the outer circumferential surfaces of the roller
portions 35a is returned to the speed increaser chamber 13c.
[0097] As shown in FIG. 1, the oil in the speed increaser chamber
13c is stirred by the speed increaser 30. This generates bubbles B
in the oil. The bubbles B in the oil generated in the speed
increaser chamber 13c reach the oil pan 56 through the oil passage
60.
[0098] As shown in FIGS. 3 and 4, the bubbles B that have reached
the oil pan 56 are retained in the oil pan 56. The retained bubbles
B raise the level of the oil stored in the oil pan 56. The level of
the oil then reaches the first pressure relief passage 95 and the
second pressure relief passage 96.
[0099] In the present embodiment, the cross-sectional flow area of
the stagnation portion 92e, which is the largest cross-sectional
flow area of the second pressure relief passage 96, is smaller than
the cross-sectional flow area of the connection passage 90a, which
is the minimum cross-sectional flow area of the first pressure
relief passage 95. That is, the cross-sectional flow area of the
second pressure relief passage 96 is smaller than the
cross-sectional flow area of the first pressure relief passage 95
over the entire length. The bubbles B in the oil stored in the oil
pan 56 are thus more likely to be drawn into the second pressure
relief passage 96 by capillary action than into the first pressure
relief passage 95. The level of the oil is thus not likely to reach
the pressure relief hole 90b in the first pressure relief passage
95.
[0100] The present embodiment has the following advantages.
[0101] (1) The cross-sectional flow area of the second pressure
relief passage 96 is smaller than the cross-sectional flow area of
the first pressure relief passage 95 over the entire length. The
bubbles B in the oil stored in the oil pan 56 are thus more likely
to be drawn into the second pressure relief passage 96 by capillary
action than into the first pressure relief passage 95. The bubbles
B in the oil are thus not likely to reach the pressure relief hole
90b in the first pressure relief passage 95. This prevents the
level of the oil from reaching the pressure relief hole 90b of the
pressure relief passage 90.
[0102] (2) The pressure relief passage 90 includes the detouring
pressure relief passage 97. Even if the level of oil reaches the
first pressure relief passage 95 in the oil pan 56, and the level
of the oil rises to the long-dash short-dash line L1 in FIGS. 3 and
4, the oil is drawn into the second pressure relief passage 96.
Also, the second pressure relief passage 96 may be filled with
bubbles, so that the bubbles B reach the first pressure relief
passage 95. Even in this case, the bubbles B are readily drawn into
the detouring pressure relief passage 97 since the largest
cross-sectional flow area of the second pressure relief passage 96
is larger than the minimum cross-sectional flow area of the
detouring pressure relief passage 97. This prevents the level of
the oil from reaching the pressure relief hole 90b of the pressure
relief passage 90.
[0103] (3) The bubbles B in the oil flowing into the second
pressure relief passage 96 reach the detouring pressure relief
passage 97 via the merging portion 98. In the present embodiment,
the pressure relief hole 90b is spaced apart from the merging
portion 98. This prevents oil that has reached the merging portion
98 from reaching the pressure relief hole 90b of the pressure
relief passage 90.
[0104] (4) The second pressure relief passage 96 has the upper side
passage 92d, which serves as a constriction. This locally reduces
the cross-sectional flow area of the second pressure relief passage
96. The bubbles B in the oil stored in the oil pan 56 thus readily
flow toward the second pressure relief passage 96. This further
reduces the amount of the bubbles B in the oil flowing into the
first pressure relief passage 95. This prevents the level of the
oil from reaching the pressure relief hole 90b of the pressure
relief passage 90.
[0105] (5) The pressure relief hole 90b is arranged above the
merging portion 98. Thus, the oil that has reached the merging
portion 98 is returned to the first pressure relief passage 95,
which is located below the merging portion 98, and is not likely to
reaching the pressure relief hole 90b. This prevents the level of
the oil from reaching the pressure relief hole 90b of the pressure
relief passage 90.
[0106] (6) The bubbles B in the oil drawn into the second pressure
relief passage 96 are crushed by the bent portion of the second
pressure relief passage 96 when reaching the communicating passage
93. When reaching the merging portion 98 from the communicating
passage 93, oil is returned to the oil pan 56 via the first
pressure relief passage 95. When reaching the merging portion 98
from the communicating passage 93, gas is discharged to the outside
of the housing 11 via the pressure relief hole 90b. That is, the
oil stored in the oil pan 56 is unlikely to gush out with the
bubbles B from the pressure relief hole 90b. This limits a
reduction in the amount of oil supplied to the speed increaser
30.
[0107] (7) The bubbles B in the oil flowing into the second
pressure relief passage 96 reach the first buffer chamber 91 via
the communicating passage 93 and the merging portion 98. In the
present embodiment, the pressure relief hole 90b is spaced apart
from the communicating passage 93 and the merging portion 98. This
prevents oil from reaching the pressure relief hole 90b from the
merging portion 98.
[0108] (8) Oil stagnates at the stagnation portion 92e. The
pressure at the stagnation portion 92e is therefore higher than the
pressure in a section of the second buffer chamber 92 on the
upstream side of the stagnation portion 92e. The bubbles B in the
oil are thus broken by the pressure at the stagnation portion
92e.
[0109] When the bubbles B that have not been removed at the
stagnation portion 92e reach the first buffer chamber 91, which is
larger than the communicating passage 93, via the communicating
passage 93, the bubbles B in the oil that has reached the first
buffer chamber 91 are removed through changes in the pressure.
Accordingly, the oil stored in the oil pan 56 is prevented from
gushing out with bubbles B from the pressure relief hole 90b of the
pressure relief passage 90. This limits a reduction in the amount
of oil supplied to the speed increaser 30.
[0110] (9) The bubbles B in the oil that has reached the stagnation
portion 92e collide with the wall surface 92f of the stagnation
portion 92e, and disappear when colliding with the wall surface
92f.
[0111] (10) The bubbles B in the oil are more likely to flow to the
second buffer chamber 92 than to the first buffer chamber 91, and
the bubbles B are removed by the stagnation portion 92e and the
bent portion of the second pressure relief passage 96. This
prevents oil from leaking from the pressure relief hole 90b.
Accordingly, the reliability of the centrifugal compressor 10 is
improved.
[0112] (11) Taking leakage of oil from the pressure relief hole 90b
into consideration, the centrifugal compressor 10 preferably stores
a great amount of oil. In this respect, the present embodiment
prevents oil leakage and thus allows for reduction in the total
amount of sealed-in oil of the centrifugal compressor 10. This
reduces the manufacturing costs of the centrifugal compressor
10.
[0113] (12) The pressure relief passage 90 is provided with the
ventilation film 90c, which allows passage of gas but blocks
liquid. The ventilation film 90c prevents foreign matter and water
from entering the centrifugal compressor 10 from the outside
through the pressure relief passage 90.
[0114] (13) Since the bubbles B in the oil are prevented from
reaching the pressure relief hole 90b, the ventilation film 90c is
prevented from being clogged.
[0115] The present embodiment may be modified as follows. The
present embodiment and the following modifications can be combined
as long as the combined modifications remain technically consistent
with each other.
[0116] The pressure relief passage 90 may be formed by the first
pressure relief passage 95 and the detouring pressure relief
passage 97, without the second pressure relief passage 96. For
example, the pressure relief passage 90 may be modified as
illustrated in FIG. 6.
[0117] As shown in FIG. 6, the first buffer chamber 91 incorporates
a second protrusion 16c, which is adjacent to the protrusion 16b in
the first horizontal direction A. In the first buffer chamber 91,
the second protrusion 16c is arranged to connect two inner walls
that are opposed to each other in the axial direction of the low
speed shaft 17. The second protrusion 16c is formed integrally with
the two inner walls.
[0118] The second protrusion 16c is located halfway between the
first side surface 91a and the protrusion 16b in the first
horizontal direction A. The second protrusion 16c is arranged in
the vicinity of the lower part of the first buffer chamber 91 in
the direction of gravitational force.
[0119] The cross section of the second protrusion 16c when cut in
the radial direction of the low speed shaft 17 is rectangular. The
width of the second protrusion 16c in the direction of
gravitational force is the same as the width of the protrusion 16b
in the direction of gravitational force. The width of the space
between a side surface of the protrusion 16b that is opposed to the
first side surface 91a and a side surface of the second protrusion
16c that is opposed to the protrusion 16b is defined as a width W4.
The width of the space between the first side surface 91a and a
side surface of the second protrusion 16c that is opposed to the
first side surface 91a is defined as a width W5. The width W4 and
the width W5 are equal to each other. The widths W4, W5 are smaller
than the width W2.
[0120] The first buffer chamber 91 includes a second passage 912.
The second passage 912 includes a passage formed between the
protrusion 16b and the lower part of the first buffer chamber 91,
and a passage formed between the protrusion 16b and the second
protrusion 16c. A third passage 913 is formed in the first buffer
chamber 91. The third passage 913 includes a passage formed between
the lower part of the first buffer chamber 91 and the set of the
protrusion 16b and the second protrusion 16c, and a passage formed
between the second protrusion 16c and the first side surface
91a.
[0121] The second passage 912 extends from the first passage 911
toward the first side surface 91a. The second passage 912 also
extends upward, detouring the protrusion 16b. The third passage 913
extends from the first passage 911 toward the first side surface
91a. The third passage 913 also extends upward, detouring the
second protrusion 16c.
[0122] The first passage 911, the second passage 912, and the third
passage 913 are connected to each other in a region in the first
buffer chamber 91 that is above the protrusion 16b and the second
protrusion 16c. The first passage 911, the second passage 912, and
the third passage 913 share the region in the first buffer chamber
91 that is above the protrusion 16b and the second protrusion
16c.
[0123] The detouring pressure relief passage 97 is formed by the
second passage 912, the third passage 913, and the region in the
first buffer chamber 91 that is above the protrusion 16b and the
second protrusion 16c. The detouring pressure relief passage 97 is
connected to the first pressure relief passage 95, detouring the
protrusion 16b and the second protrusion 16c.
[0124] The minimum cross-sectional flow area of the detouring
pressure relief passage 97 is the cross-sectional flow area of the
second passage 912 and the third passage 913. The minimum
cross-sectional flow area of the detouring pressure relief passage
97 is smaller than the minimum cross-sectional flow area of the
first pressure relief passage 95.
[0125] In this case, the cross-sectional flow area of the second
passage 912 and the third passage 913, which is the minimum
cross-sectional flow area of the detouring pressure relief passage
97, are smaller than the cross-sectional flow area of the
connection passage 90a, which is the minimum cross-sectional flow
area of the first pressure relief passage 95. Accordingly, the
bubbles B in the oil stored in the oil pan 56 are likely to be
drawn into the detouring pressure relief passage 97, in which
capillary action is more likely to occur than in the first pressure
relief passage 95. Thus, the level of the oil reaches the long-dash
short-dash line L2 in FIG. 6 in the first pressure relief passage
95. On the other hand, in the detouring pressure relief passage 97,
the level of the oil reaches the long-dash short-dash lines L3 in
FIG. 6, which are higher than the long-dash short-dash line L2. The
bubbles B in the oil are thus not likely to reach the pressure
relief hole 90b in the first pressure relief passage 95. This
prevents the level of the oil from reaching the pressure relief
hole 90b of the pressure relief passage 90.
[0126] In the modification shown in FIG. 6, the second protrusion
16c may be displaced toward the first side surface 91a, so that the
width W4 is larger than the width W5. Alternatively, the second
protrusion 16c may be displaced toward the second side surface 91b,
so that the width W5 is larger than the width W4.
[0127] As shown in FIG. 7, in the configuration in which the
pressure relief passage 90 is formed by the first pressure relief
passage 95 and the detouring pressure relief passage 97, the
protrusion 16b may be arranged to be closer to the first side
surface 91a in the first horizontal direction A, so that the width
W2 is larger than the width W1. That is, the minimum
cross-sectional flow area of the detouring pressure relief passage
97 may be the cross-sectional flow area of the second passage
912.
[0128] The pressure relief hole 90b may be arranged to be directly
above the merging portion 98 in the direction of gravitational
force. In this case, the pressure relief hole 90b is arranged above
the merging portion 98.
[0129] The pressure relief hole 90b and the merging portion 98 may
be located at the same position in the direction of gravitational
force.
[0130] The pressure relief hole 90b and the merging portion 98 may
be located at the same position in the axial direction of the low
speed shaft 17.
[0131] The oil pan 56, the oil pump 57, the oil passage 60, the
first buffer chamber 91, and the second buffer chamber 92 may be
formed in the motor housing member 12 without fastening the rear
housing member 16 to the motor housing member 12 with the bolts
80.
[0132] The connection passage 90a, the first buffer chamber 91, the
second buffer chamber 92, and the communicating passage 93 do not
necessarily need to be formed inside the rear housing member 16,
but may be formed between the rear housing member 16 and the motor
housing member 12.
[0133] The proximal side passage 92c has the second end, which is
located above the oil pump 57 in the direction of gravitational
force, in the above-described embodiment. However, the second end
of the proximal side passage 92c may be located below the oil pump
57. In this case, the first end of the upper side passage 92d may
extend to the second end of the proximal side passage 92c.
[0134] The second buffer chamber 92 may be changed to connect the
proximal side passage 92c directly to the stagnation portion
92e.
[0135] The pressure relief hole 90b may be arranged above the first
passage 911, which is formed in the vicinity of the first side
surface 91a. In this case, the pressure relief hole 90b and the
communicating passage 93 preferably do not overlap with each other
in the axial direction of the low speed shaft 17.
[0136] In the above-described embodiment, the connection passage
90a and the first buffer chamber 91 are displaced from the second
buffer chamber 92 in the axial direction of the low speed shaft 17,
and the second buffer chamber 92 is arranged closer to the motor
housing member 12 than the first buffer chamber 91 in the axial
direction of the low speed shaft 17. However, the present
disclosure is not limited to this. For example, the connection
passage 90a may be located at the same position in the axial
direction of the low speed shaft 17 as the first buffer chamber 91
and the second buffer chamber 92. In this case, the communicating
passage 93 may be changed to extend in the first horizontal
direction A, and the first buffer chamber 91 and the second buffer
chamber 92 may be connected to each other.
[0137] In the configuration in which the pressure relief passage 90
includes the first pressure relief passage 95, the second pressure
relief passage 96, and the detouring pressure relief passage 97,
the connection passage 90a may be formed by the first pressure
relief passage 95 and the first buffer chamber 91, and the
detouring pressure relief passage 97 may be formed outside the
first buffer chamber 91. In this case, the detouring pressure
relief passage 97 may be formed to connect the first pressure
relief passage 95 and the second pressure relief passage 96 to each
other.
[0138] In the configuration in which the pressure relief passage 90
includes the first pressure relief passage 95, the second pressure
relief passage 96, and the detouring pressure relief passage 97,
the detouring pressure relief passage 97 may be omitted from the
pressure relief passage 90.
[0139] In the axial direction of the low speed shaft 17, the width
H1 of the first buffer chamber 91 and the width H2 of the second
buffer chamber 92 are the same in the above-described embodiment.
However, the widths H1 and H2 may be different from each other. The
widths H1, H2 may be changed as long as the cross-sectional flow
area of the second pressure relief passage 96 is smaller than the
cross-sectional flow area of the first pressure relief passage 95
over the entire length. The same change may be made to the
above-described modifications.
[0140] The centrifugal compressor 10 may be employed in any
suitable application to compress any type of gas. For example, the
centrifugal compressor 10 may be employed in an air conditioner to
compress refrigerant gas. Further, the centrifugal compressor 10
may be mounted on any structure other than a vehicle.
[0141] Various changes in form and details may be made to the
examples above without departing from the spirit and scope of the
claims and their equivalents. The examples are for the sake of
description only, and not for purposes of limitation. Descriptions
of features in each example are to be considered as being
applicable to similar features or aspects in other examples.
Suitable results may be achieved if sequences are performed in a
different order, and/or if components in a described system,
architecture, device, or circuit are combined differently, and/or
replaced or supplemented by other components or their equivalents.
The scope of the disclosure is not defined by the detailed
description, but by the claims and their equivalents. All
variations within the scope of the claims and their equivalents are
included in the disclosure.
* * * * *