U.S. patent application number 10/869097 was filed with the patent office on 2005-02-24 for compressor of turbo machine and its compressor wheel.
Invention is credited to Inaba, Keiichi, Nishiyama, Toshihiko.
Application Number | 20050042105 10/869097 |
Document ID | / |
Family ID | 32737747 |
Filed Date | 2005-02-24 |
United States Patent
Application |
20050042105 |
Kind Code |
A1 |
Nishiyama, Toshihiko ; et
al. |
February 24, 2005 |
Compressor of turbo machine and its compressor wheel
Abstract
The invention provides a compressor of a turbo machine and its
compressor wheel that do not easily undergo breaking even when
rotated at a high number of revolutions. The compressor of the
turbo machine includes a male screw portion integrally formed on a
main body portion of the compressor wheel and a male screw portion
disposed at a distal end of a shaft for driving the compressor
wheel that are coupled with each other through a sleeve equipped at
one of the ends thereof with a female screw portion capable of
meshing with the male screw portion of the compressor wheel and at
the other end with a female screw portion capable of meshing with
the male screw portion of the shaft.
Inventors: |
Nishiyama, Toshihiko;
(Oyama-City, JP) ; Inaba, Keiichi; (Yuki-City,
JP) |
Correspondence
Address: |
VARNDELL & VARNDELL, PLLC
106-A S. COLUMBUS ST.
ALEXANDRIA
VA
22314
US
|
Family ID: |
32737747 |
Appl. No.: |
10/869097 |
Filed: |
June 17, 2004 |
Current U.S.
Class: |
416/183 |
Current CPC
Class: |
F04D 29/266 20130101;
F04D 29/284 20130101; F16D 1/06 20130101 |
Class at
Publication: |
416/183 |
International
Class: |
F04D 029/38 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 18, 2003 |
JP |
2003-172790 |
Mar 24, 2004 |
JP |
2004-086046 |
Claims
What is claimed is:
1. A compressor of a turbo machine comprising: a compressor wheel
male screw portion integrally disposed on a main body portion of a
compressor wheel; a shaft male screw portion disposed at a distal
end of a driving shaft of the compressor wheel; and a sleeve
equipped at one of the ends thereof with a compressor wheel-side
female screw portion capable of meshing with the compressor wheel
male screw and at the other end thereof with a shaft-side female
screw portion capable of meshing with the shaft male screw portion;
the compressor wheel screw portion and the shaft male screw portion
being coupled with each other through the sleeve.
2. The compressor of a turbo machine as defined in claim 1, wherein
a diameter of the compressor wheel male screw portion is greater
than a diameter of the shaft male screw portion.
3. The compressor of a turbo machine as defined in claim 1, wherein
at least one of centering between the compressor wheel and the
sleeve and centering between the sleeve and the shaft is made by
means of a spigot joint arrangement.
4. The compressor of a turbo machine as defined in claim 2, wherein
at least one of centering between the compressor wheel and the
sleeve and centering between the sleeve and the shaft is made by
means of a spigot joint arrangement.
5. The compressor of a turbo machine as defined in claim 1, which
further comprises a seal groove formed around an outer
circumferential portion of the sleeve and a seal ring fitted into
the seal groove so as to prevent leakage of air and oil between a
back surface chamber of the compressor wheel and a bearing
chamber.
6. The compressor of a turbo machine as defined in claim 2, which
further comprises a seal groove formed around an outer
circumferential portion of the sleeve and a seal ring fitted into
the seal groove so as to prevent leakage of air and oil between a
back surface chamber of the compressor wheel and a bearing
chamber.
7. The compressor of a turbo machine as defined in claim 3, which
further comprises a seal groove formed around an outer
circumferential portion of the sleeve and a seal ring fitted into
the seal groove so as to prevent leakage of air and oil between a
back surface chamber of the compressor wheel and a bearing
chamber.
8. The compressor of a turbo machine as defined in claim 4, which
further comprises a seal groove formed around an outer
circumferential portion of the sleeve and a seal ring fitted into
the seal groove so as to prevent leakage of air and oil between a
back surface chamber of the compressor wheel and a bearing
chamber.
9. The compressor of a turbo machine as defined in claim 5, which
further comprises a thrust bearing fixed to a non-rotary member not
executing revolution in synchronism with the shaft and a disk-like
thrust collar fixed to the shaft, and wherein the thrust collar and
the sleeve sandwich the thrust bearing between them.
10. The compressor of a turbo machine as defined in claim 6, which
further comprises a thrust bearing fixed to a non-rotary member not
executing revolution in synchronism with the shaft and a disk-like
thrust collar fixed to the shaft, and wherein the thrust collar and
the sleeve sandwich the thrust bearing between them.
11. The compressor of a turbo machine as defined in claim 7, which
further comprises a thrust bearing fixed to a non-rotary member not
executing revolution in synchronism with the shaft and a disk-like
thrust collar fixed to the shaft, and wherein the thrust collar and
the sleeve sandwich the thrust bearing between them.
12. The compressor of a turbo machine as defined in claim 8, which
further comprises a thrust bearing fixed to a non-rotary member not
executing revolution in synchronism with the shaft and a disk-like
thrust collar fixed to the shaft, and wherein the thrust collar and
the sleeve sandwich the thrust bearing between them.
13. A compressor wheel of a compressor of a turbo machine, wherein
a distal end of a cylindrical portion of a back surface-side disk
portion of a compressor wheel is a male screw processed portion.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] This invention relates to a compressor of a turbo machine
and its compressor wheel.
[0003] 2. Description of the Related Art
[0004] A compressor of a turbo machine of the type that is rotated
by a turbine wheel via a shaft by utilizing energy of an exhaust
gas as means for increasing an intake amount of an engine by
compressing air and drives a centrifugal type compressor wheel
coupled with a shaft is known as a turbo charger.
[0005] FIG. 7 is a sectional side view of the turbo charger 11
according to the prior art. The turbo charger 11 includes an
exhaust-side unit 12 for taking out energy of revolution from the
exhaust gas of an engine and an intake-side unit 13 for compressing
air by this energy of revolution and sending compressed air into
the engine.
[0006] A turbine wheel 14 is imparted with energy and is rotated by
the exhaust gas inflowing from an exhaust inflow passage 19. A
centrifugal type compressor wheel 16 for compressing air is fitted
on the opposite side to the turbine wheel 14 of a shaft 23
(hereinafter called a "distal end side of the shaft 23") through
the shaft 23. A fitting hole 25 penetrates through a center of the
compressor wheel 16. The shaft 23 is fitted into the fitting hole
25 with slight loose fit or tight fit. The compressor wheel 16 is
fixed to the shaft 23 as a nut 26 is fastened to a male screw
portion 40 formed at a distal end of the shaft 23.
[0007] FIG. 8 is a sectional side view of the compressor wheel 16
shown in FIG. 7. A main body portion 29 of the compressor wheel 16
includes an inlet-side disk portion 29A and a back surface-side
disk portion 29B. A plurality of vane portions 18 are arranged on
the outside of the main body portion 29 and the fitting hole 25
penetrates through the center of the main body portion 29.
[0008] To accomplish lightweight, the compressor wheel 16 is
produced from a casting such as an aluminum alloy. Because rotating
speed of the compressor wheel 16 reaches high values of dozens of
thousands of rounds per minute (rpm), centrifugal force resulting
from the high-speed revolution imparts an extremely high tensile
strength in a radial direction and sometimes invites breaking of
the compressor wheel 16. It is known that this breaking is likely
to particularly develop in the inner wall of the fitting hole 25 as
the starting point.
[0009] To solve this problem, a technology described in Patent
Reference (JP-A-5-504178), for example, is known.
[0010] FIG. 9 is a sectional view of a compressor wheel 16
according to this Patent Reference. A fitting hole penetrating
through the compressor wheel 16 is not disposed but a fitting hole
42 having a female screw is formed at its lower part. A male screw
is formed at a distal end 54 of a shaft 23. A male screw is formed
at the distal end 54 of the shaft 23. The shaft 23 and the
compressor wheel 16 are coupled with each other as the distal end
54 is screwed into the fitting hole 42.
[0011] However, the prior art technology shown in FIG. 8 is not
free from the following problem. In other words, it has been
confirmed that breaking of the inner wall of the fitting hole 25 in
the compressor wheel 16 occurs particularly frequently in the
proximity of the maximum outer circumferential portion 30 at which
the outer circumferential portion of the compressor wheel 16
becomes maximal in an axial direction.
[0012] According to the prior art shown in FIG. 9, the fitting hole
42 is disposed in the proximity of the maximum outer
circumferential portion 30 in the axial direction. Therefore, when
rotating speed is increased, breaking may occur from near the
maximum outer circumferential portion 30.
[0013] Particularly when an engine equipped with the turbo charger
11 using the compressor wheel 16 is used for work machines such as
construction machines, a high load state such as a loading
operation (that is, a high rotating speed of the turbocharger) and
a state almost free from the load (that is, a low rotating speed)
are repeated within short time intervals. As a result, the stress
amplitude applied to the compressor wheel 16 becomes high and
breaking is more likely to occur.
[0014] A technology called "EGR (Exhaust Gas Recirculation)" has
been adopted in recent years as a counter-measure for reducing
nitrogen oxides (NOx) contained in an exhaust gas of a Diesel
engine. This technology returns a part of the exhaust gas emitted
from the engine to an intake system of the engine for
re-circulation. To accomplish EGR, it is necessary to secure fresh
air for combustion capacity in a cylinder where the quantity of
fresh air becomes smaller by the re-circulation amount of the
exhaust gas and to achieve a higher-pressure ratio of the turbo
charger 11. In other words, the compressor wheel 16 must be rotated
at a higher rotating speed. The prior art technology is not yet
sufficient and a compressor wheel 16 having higher durability has
been desired.
SUMMARY OF THE INVENTION
[0015] In view of the problems described above, the invention aims
at providing a compressor of a turbo machine exhibiting less
breaking even when rotated at a high rotating speed and its
compressor wheel.
[0016] To accomplish this object, a compressor of a turbo machine
according to the invention includes a male screw portion integrally
formed on a main body portion of a compressor wheel and a male
screw portion disposed at a distal end of a shaft for driving the
compressor wheel that are coupled with each other through a sleeve
equipped at one of the ends thereof with a female screw portion
capable of meshing with the male screw portion of the compressor
wheel and at the other end with a female screw portion capable of
meshing with the male screw portion of the shaft.
[0017] In the invention, a diameter of the male screw portion of
the compressor wheel may be greater than a diameter of the male
screw portion of the shaft.
[0018] In the invention, at least either one of centering between
the compressor wheel and the sleeve and centering between the
sleeve and the shaft may be made in a spigot joint arrangement.
[0019] In the invention, a seal groove may be formed around an
outer circumferential portion of the sleeve and a seal ring may be
fitted into the seal groove so as to prevent leakage of air and oil
between a back surface chamber of the compressor wheel and a
bearing chamber.
[0020] The invention may also have a construction which includes a
thrust bearing fixed to a non-rotary member not executing
revolution in synchronism with the shaft and a disk-like thrust
collar fixed to the shaft, and wherein the thrust collar and the
sleeve sandwich the thrust bearing between them.
[0021] In the invention, a distal end of a cylindrical portion of a
back surface-side disk portion of the compressor wheel is a male
screw processed portion.
[0022] The following can be listed up as the effects of the
invention.
[0023] The fitting hole or aperture for coupling with the shaft
need not be disposed in the compressor wheel main body portion. As
a result, the stress acting on the compressor wheel becomes small
and breaking becomes less even when the compressor wheel is rotated
at a high number of revolutions.
[0024] The compressor wheel is formed in many cases of a material
having a lower intensity than the shaft to reduce the weight.
Therefore, when the male screw portion of the compressor wheel is
rendered thick, the problem that the male screw portion of the
compressor wheel is particularly likely to be broken becomes small
and overall durability can be improved.
[0025] When the rotation balance of the compressor wheel and the
turbine wheel is individually adjusted and these wheels are
assembled, a centering error after assembly becomes small.
Therefore, the frequency of re-adjustment of the rotation balance
of the compressor of the turbo machine becomes small.
[0026] Members for sealing air and oil need not be disposed
separately, and air and oil can be sealed with a compact
construction.
[0027] It is also possible to support the thrust bearing with a
simple construction and to effectively bear the force in the thrust
direction that acts on the shaft.
[0028] Because breaking of the compressor wheel becomes more
difficult to occur and durability can be improved, the pressure
ratio of the turbo charger using this compressor wheel can be
increased.
BRIEF DESCRIPTION OF THE DRAWINGS
[0029] FIG. 1 is a side view of a compressor wheel according to the
invention;
[0030] FIG. 2 is a sectional view of FIG. 1;
[0031] FIG. 3 is a sectional view of a turbo charger according to
the invention;
[0032] FIG. 4 is a detailed view of a portion P in FIG. 3;
[0033] FIG. 5 is a flowchart showing a procedure for assembling the
compressor wheel;
[0034] FIG. 6 is a graph showing the relation between an inner
diameter of a known fitting hole and a magnitude of a stress;
[0035] FIG. 7 is a sectional side view of a turbo charger according
to a prior art;
[0036] FIG. 8 is a sectional side view of a compressor wheel shown
in FIG. 7; and
[0037] FIG. 9 is a sectional view of another compressor wheel
according to the prior art.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0038] A preferred embodiment of the invention will be hereinafter
explained in detail with reference to the accompanying
drawings.
[0039] Referring to FIG. 3, an exhaust-side unit 12 includes an
exhaust-side housing 15 and a turbine wheel 14 having a plurality
of vanes and supported by a shaft 23.
[0040] The exhaust-side housing 15 has an exhaust inflow passage 19
for supplying an exhaust gas to the turbine wheel 14. The exhaust
inflow passage 19 is formed into an annular shape in such a manner
as to encompass the outer periphery of the turbine wheel 14 and is
connected to an engine exhaust flow passage through which the
exhaust gas emitted from an engine, not shown, flows. The
exhaust-side housing 15 has also an exhaust outflow port 21 for
emitting the exhaust gas after imparting energy to the turbine
wheel 14. The exhaust outflow port 21 is formed substantially into
a cylindrical shape that is concentric with the center of
revolution of the turbine wheel 14. An opening on the opposite side
to the exhaust outflow port 21 is closed by an exhaust-side inner
plate 22.
[0041] The shaft 23 is formed integrally with the turbine wheel 14.
The shaft 23 penetrates through the exhaust-side inner plate 22 and
is rotatably supported by a bearing 24. The turbine wheel 14 and
the shaft 23 are ordinarily formed of a nickel base super-alloy,
carbon steel or alloy steel.
[0042] A compressor wheel 16 is accommodated inside an intake-side
housing 17. The intake-side housing 17 has an intake inflow port 27
for sucking air into the compressor wheel 16. The intake inflow
port 27 is formed substantially into a cylindrical shape that is
concentric with the center of revolutions of the compressor wheel
16. An opening on the opposite side to the intake inflow port 27 is
closed by an intake-side inner plate 55.
[0043] Air that is compressed by the compressor wheel 16 is
centrifugally discharged and is supplied to a feed port of the
engine, not shown, while passing through an intake exhaust passage
28 annularly formed in such a manner as to encompass the outer
peripheral portion of the compressor wheel 16.
[0044] The vanes 18 include full vanes 18A having a large width in
an axial direction of the vanes and intermediate vanes 18B in which
a vane inlet starts from an intermediate part in the axial
direction with respect to the full vanes 18A. These full vanes 18A
and intermediate vanes 18B are alternately arranged.
[0045] A group of rotary members including the turbine wheel 14,
the compressor wheel 16 and the shaft 23 will be hereinafter called
the "rotary members". A group of stationary members including the
intake-side housing 17, the exhaust-side housing 15 and a bearing
housing 45 will be hereinafter called the "non-rotary members". A
penetrating direction of the fitting hole 25 will be called the
"axial direction".
[0046] As shown in FIGS. 1 and 2, a main body portion 29 of the
compressor wheel 16 according to the invention is solid and does
not have any fitting holes or apertures.
[0047] A portion for sucking air into the compressor wheel 16 will
be called a"compressor wheel inlet portion 35" and a portion for
discharging air in a radial direction will be called a "compressor
wheel outlet portion 33". A curve surface of an intermediate
portion between the compressor wheel inlet portion 35 and the
compressor wheel outlet portion 33 will be called a "disk center
portion 34".
[0048] A portion in the axial direction at which the outer
peripheral portion of the compressor wheel 16 becomes maximal will
be called the "maximum outer peripheral portion 30". The main body
portion 29 of the compressor wheel 16 has an inlet-side disk
portion 29A and a rear surface-side disk portion 29B. A cylindrical
portion 43 is integrally arranged on the rearmost portion of the
rear surface-side disk portion 29B while its axis is in alignment
with the main body portion 29. A male screw 44 having a smaller
diameter than that of the cylindrical portion 43 is integrally
formed at the lower end of the cylindrical portion 43. The male
screw 44 will be called a "compressor wheel male screw portion
44".
[0049] Processing for securing a width across flats or nut-like
processing, for example, is applied to the outer peripheral portion
of the compressor wheel inlet portion 35 of the compressor wheel 16
and this portion can be clamped by use of a wrench, or the
like.
[0050] Referring to FIGS. 3 and 4, the distal end portion 60 of the
shaft 23 fixed to the turbine wheel 14 is precisely machined into a
cylindrical shape that is concentric with the shaft 23. This
cylindrical portion will be called a "shaft cylindrical portion
60". A male screw 46 is formed at a further distal end of the shaft
cylindrical portion 60. This male screw 46 will be called a "shaft
male screw portion 46". The outer diameter of the shaft male screw
portion 46 is smaller than the outer diameter of the compressor
wheel male screw portion 44. The shaft male screw portion 46 and
the compressor wheel screw portion 44 are connected to each other
through a sleeve 49 having female screws at both of its ends.
[0051] As shown in FIG. 4, spigot joint processing is applied to
the inner peripheral portion 58 at the end of the sleeve 49 on the
side of the shaft 23 with respect to the shaft cylindrical portion
60. A female screw 53 (hereinafter called a "shaft-side female
screw portion 53") meshing with the shaft male screw portion 46 is
formed at the depth of the inner peripheral portion 58 (on the side
of the compressor wheel 16).
[0052] Spigot joint processing is applied to the inner peripheral
portion 57 at the end of the sleeve 49 on the side of the
compressor wheel 16 with respect to the cylindrical portion 43
formed on the rear surface of the compressor wheel 16. A female
screw 52 (hereinafter called a "compressor wheel-side female screw
portion 52") meshing with the compressor wheel male screw portion
44 is formed at the depth of the inner peripheral portion 57 (on
the side of the shaft 23).
[0053] Incidentally, the shaft-side female screw portion 53 and the
compressor wheel-side female screw portion 52 in the sleeve 49 are
shown penetrated but they need not always be penetrated. Processing
for securing a width across flats or nut-like processing, for
example, is applied to the outer peripheral portion 61 of the of
the sleeve 49 on the side of the compressor wheel 16 and this
portion can be clamped by use of a wrench, or the like. A seal
groove 50 is formed in the entire outer peripheral portion at an
intermediate part of the sleeve 49 in the axial direction and a
seal ring 51 formed of an FC material, etc, is fitted into the seal
groove 50. The seal ring 51 is formed in such a manner that when
force for reducing the diameter is applied, the outer peripheral
portion of the sealing ring 51 tightly fits into the inner
peripheral portion of the intake-side inner plate 55.
[0054] The bearing 24 is accommodated in a bearing box 63 of the
bearing housing 45 that connects the intake-side housing 17 and the
exhaust-side housing 15. An oil-feed port 59 is formed in the
bearing housing 45 to supply a lubricant to the bearing 24 and the
thrust bearing 48.
[0055] FIG. 5 is a flowchart showing the procedure for assembling
the compressor wheel 16 into the shaft 23. First, a disk-like
thrust collar 47 having a round hole at its center is fitted to the
shaft 23 supported by the bearing 24 (Step S11).
[0056] Next, the thrust bearing 48 is fitted to the bearing housing
45 (Step S12). An oil passage 56 through which lubricant oil flows
is disposed in the thrust bearing 48.
[0057] The sleeve 49 is screwed into the shaft 23 (Step S13). In
this instance, the sleeve 49 is screwed into the shaft male screw
portion 46 while the outer peripheral portion 61 of the sleeve 49
processed into the nut shape is clamped by the wrench, or the like.
In consequence, the sleeve 49 and the thrust collar 47 rotate
integrally with the shaft 23.
[0058] Next, the intake side inner plate 55 is fixed to the bearing
housing 45 (Step S14). Consequently, the thrust bearing 48 is fixed
to the non-rotary members while being sandwiched between the
bearing housing 45 and the intake-side inner plate 55.
[0059] As a result, the thrust bearing 48 fixed to the non-rotary
members in Step S13 is sandwiched between the thrust collar 47 and
the sleeve 49 as the rotary members rotating integrally with the
shaft 23. Therefore, the force imparted in the thrust direction of
the shaft 23 during revolution is received by the thrust bearing 48
and the position in the axial direction is limited. When the sleeve
49 is screwed in Step S14, the outer peripheral portion of the seal
ring 51 comes into adhesion with the inner peripheral portion of
the intake-side inner plate 55. Consequently, the oil for
lubricating the bearing 24 and the thrust bearing 48 is prevented
from flowing out to the space (called a "back surface chamber 62")
of the back surface of the compressor wheel 16.
[0060] Next, the compressor wheel 16 is screwed into the sleeve 49
(Step S15). In this instance, the nut-like processed portion of the
compressor wheel inlet portion 35 of the compressor wheel 16 and
the nut-like processed portion of the outlet portion of the turbine
wheel 14 are screwed to each other while being clamped by the
wrench, or the like. The compressor wheel 16 and the shaft 23 are
thus coupled with each other.
[0061] As explained above, in the invention, the compressor wheel
male screw portion 44 is arranged round the outer periphery of the
cylindrical portion 43 at the rearmost surface portion of the back
surface-side disk portion 29B of the compressor wheel 16. The
impeller male screw portion 44 and the shaft male screw portion 46
disposed at the distal end of the shaft 23 are connected to each
other through the sleeve 49 having the female screw portions 52 and
53 at both of its ends.
[0062] Therefore, even when the compressor wheel 16 is solid, the
compressor wheel 16 and the shaft 23 can be connected to each
other. For this reason, the stress acting on the compressor wheel
16 becomes small and breakage does not occur even at a high
rotating speed.
[0063] FIG. 6 is a graph showing the relation between the inner
diameter .PHI. of the fitting hole 25 of the compressor wheel 16
and the magnitude of the stress T acting on the compressor wheel 16
at the maximum outer circumference portion 30 at which the outer
circumferential portion of the compressor wheel 16 becomes maximal
in the axial direction of the rotary shaft of the compressor wheel
16 in the prior art technology. In the graph, the stress T is small
when the inner diameter of the fitting hole 25 is 0 and becomes
extremely great when the inner diameter is excessively small. At a
certain inner diameter D or above, the stress T becomes greater
with the increase of the inner diameter of the fitting hole 25.
Therefore, it can be understood that when the fitting hole 25 does
not exist and the compressor wheel 16 is solid as in the present
invention, the stress becomes small.
[0064] According to the invention, the diameter of the compressor
wheel male screw portion 44 formed integrally with the compressor
wheel 16 is greater than the diameter of the shaft male screw
portion 46 formed at the distal end of the shaft 23. The compressor
wheel 16 and the compressor wheel male screw portion 44 are formed
of a casting of an aluminum alloy, for example. On the other hand,
the shaft 23 and the shaft male screw portion 46 are formed of a
hard material such as iron or its alloy. Therefore, when the
thickness of the casting of the aluminum alloy having a lower
strength is increased, it is possible to prevent the problem that
one of them is particularly likely to be broken.
[0065] Furthermore, the shaft male screw portion 46 is formed at
the distal end portion of the shaft 23 and the sleeve 49 having the
female screw portion 53 is screwed to the shaft male screw portion
46. This configuration makes it possible to reduce the outer
diameter of the portion of the shaft 23, which is supported by the
shaft 24, when compared to the configuration in which, for example,
a female screw is disposed in the shaft 23. Therefore, because the
speed of the outer peripheral portion of the shaft 23 becomes
lower, the rotation frictional loss with the bearing 24 becomes
smaller and breaking of the shaft 23 and the bearing 24 does not
easily occur.
[0066] The seal groove 50 is disposed around the outer
circumferential portion of the sleeve 49 and the oil can be sealed
by a compact construction. Because the sleeve 49 and the compressor
wheel 16 are centered with each other in the spigot joint,
unbalance during revolution can be reduced.
[0067] Incidentally, the outer circumferential portion of the
compressor wheel inlet portion 35 of the compressor wheel 16 is
sufficient so long as the compressor wheel 16 can be fixed when
screwed to the sleeve 49 and may have a bolt shape having a
hexagonal boss, for example.
[0068] The invention has been explained about only its application
example to the turbo charger but can be similarly applied to other
turbo machines and mechanical driving centrifugal compressors such
as a micro-gas turbine.
* * * * *