U.S. patent application number 13/724943 was filed with the patent office on 2014-06-26 for turbo wheel and shaft assembly.
This patent application is currently assigned to GM GLOBAL TECHNOLOGY OPERATIONS LLC. The applicant listed for this patent is GM GLOBAL TECHNOLOGY OPERATIONS LLC. Invention is credited to Louis P. BEGIN, Huaxin LI.
Application Number | 20140178188 13/724943 |
Document ID | / |
Family ID | 50878880 |
Filed Date | 2014-06-26 |
United States Patent
Application |
20140178188 |
Kind Code |
A1 |
LI; Huaxin ; et al. |
June 26, 2014 |
Turbo Wheel And Shaft Assembly
Abstract
A turbine wheel and shaft assembly is provided for a
turbocharger including a turbine wheel including a body portion
supporting a plurality of blades on a first axial face thereof. A
hub extends from a body portion on a second axial face. A shaft is
welded to the hub at a weld location spaced from the second axial
face. The weld location is spaced axially from the second axial
face by a distance sufficient to provide a significant reduction in
the residual stresses in the welded parts. This design is intended
to mitigate turbine wheel imbalance problems.
Inventors: |
LI; Huaxin; (Rochester
Hills, MI) ; BEGIN; Louis P.; (Rochester,
MI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
GM GLOBAL TECHNOLOGY OPERATIONS LLC |
Detroit |
MI |
US |
|
|
Assignee: |
GM GLOBAL TECHNOLOGY OPERATIONS
LLC
Detroit
MI
|
Family ID: |
50878880 |
Appl. No.: |
13/724943 |
Filed: |
December 21, 2012 |
Current U.S.
Class: |
415/185 |
Current CPC
Class: |
F01D 5/3061 20130101;
F01D 5/025 20130101; F05D 2220/40 20130101 |
Class at
Publication: |
415/185 |
International
Class: |
F01D 5/30 20060101
F01D005/30 |
Claims
1. A turbine wheel and shaft assembly for a turbocharger,
comprising: a turbine wheel including a body portion supporting a
plurality of blades on a first axial face thereof and a hub
extending from said body portion on a second axial face, said hub
having a diameter; a shaft welded to said hub at a weld location
spaced from said second axial face, wherein said weld location is
spaced axially from said second axial face of said body portion by
a distance that is at least 50 percent of said diameter.
2. The turbine wheel and shaft assembly according to claim 1,
wherein said shaft includes a cylindrical body and a radially
extending flange portion at an end thereof that is welded to said
hub of said turbine wheel.
3. The turbine wheel and shaft assembly according to claim 1,
wherein said shaft is hollow.
4. The turbine wheel and shaft assembly according to claim 1,
wherein said hub includes a hollow portion therein.
5. A turbocharger, comprising: a housing including an inlet for
receiving an engine exhaust gas flow, a turbine chamber and an
outlet for exhaust gas discharge; a turbine wheel and shaft
assembly disposed in said turbine chamber and including a turbine
wheel having a body portion supporting a plurality of blades on a
first axial face thereof and a hub extending from said body portion
on a second axial face opposite the first axial face, said hub
having a diameter, and a shaft having a first end welded to said
hub at a weld location spaced from said second axial face, wherein
said weld location is spaced axially from said second axial face of
said body portion by a distance that is at least 50 percent of said
diameter.
6. The turbocharger according to claim 5, wherein said shaft
includes a cylindrical body and a radially extending flange portion
at the first end thereof that is welded to said hub of said turbine
wheel.
7. The turbocharger according to claim 5, wherein said shaft is
hollow.
8. The turbo charger according to claim 5, wherein said hub
includes a hollow portion therein.
9. The turbo charger according to claim 5, further comprising a
compressor wheel attached to a second end of said shaft and
disposed in a compressor chamber.
10. The turbo charger according to claim 5, further comprising a
seal disposed between said second axial face of said turbine wheel
and said weld location.
11. An engine, comprising: an engine structure defining a plurality
of cylinders receiving a respective piston therein and having inlet
and exhaust passages in communication with each of the cylinders; a
turbocharger comprising: a housing including an inlet for receiving
an engine exhaust gas flow from said exhaust passages, a turbine
chamber and an outlet for exhaust gas discharge; a turbine wheel
and shaft assembly disposed in said turbine chamber and including a
turbine wheel having a body portion supporting a plurality of
blades on a first axial face thereof and a hub extending from said
body portion on a second axial face opposite the first axial face,
said hub having a diameter, and a shaft welded to said hub at a
weld location spaced from said second axial face, wherein said weld
location is spaced axially from said second axial face of said body
portion by a distance that is at least 50 percent of said
diameter.
12. The engine according to claim 11, wherein said shaft includes a
cylindrical body and a radially extending flange portion at an end
thereof that is welded to said hub of said turbine wheel.
13. The engine according to claim 11, wherein said shaft is
hollow.
14. The engine according to claim 11, wherein said hub includes a
hollow portion therein.
15. The engine according to claim 11, further comprising a
compressor wheel attached to a second end of said shaft and
disposed in a compressor chamber.
16. The engine according to claim 15, wherein said compressor
chamber is in communication with an air inlet and a compressed air
outlet that is in communication with said inlet passages of said
cylinders.
17. The engine according to claim 11, further comprising a seal
disposed between said second axial face of said turbine wheel and
said weld location.
Description
FIELD
[0001] The present disclosure relates to a turbocharger for
engines, and more particularly, to a turbo wheel and shaft assembly
for improved turbocharger performance.
BACKGROUND AND SUMMARY
[0002] This section provides background information related to the
present disclosure which is not necessarily prior art.
[0003] Turbo charged engines utilize compressed air which results
in a larger quantity of air being forced into the engine, creating
more power. The energy used to drive the turbo compressor is
extracted from waste exhaust gases. As the exhaust gases leave the
engine, they are directed through a turbine wheel placed in the
exhaust flow. The gases drive the turbine wheel, which is directly
connected via a shaft to a compressor wheel. Increased exhaust gas
flow drives the turbine wheel faster, providing the engine more
air, thereby producing more power. Therefore, the turbocharger uses
the extraction of energy from the exhaust gas to improve the engine
efficiency.
[0004] Turbochargers are usually seen as power enhancement on
performance cars, but today, turbochargers are becoming more
regularly used to provide greater torque on small capacity engines.
The advantages of using a turbocharged engine include improved fuel
efficiency and reduced exhaust emissions. The components of the
turbocharger generally include a housing defining a compressor
chamber and a turbine chamber, a compressor wheel is disposed in
the compressor chamber, and a turbine wheel is disposed in the
turbine chamber. A turbine shaft is provided for connecting between
the turbine wheel and the compressor wheel.
[0005] With reference to FIG. 4, a conventional turbine wheel and
shaft assembly is shown wherein the turbine wheel includes a body
portion 110 having a plurality of veins 112 extending from a first
axial face thereof. A turbine shaft 114 is welded to the back
surface of the turbine wheel body 110 at a weld location 118. A
problem with current turbine wheel and shaft assemblies can be the
imbalance of a turbine wheel that can cause noise and customer
complaints. To address the problem of turbine wheel imbalance,
turbine wheels and shaft assemblies are commonly balanced after the
weld process is completed by rotating the assembly on a balancing
machine which identifies the imbalances that can be corrected by
removing material at different locations on the turbine wheel in
order to obtain a balanced turbine wheel and shaft assembly.
[0006] It has been a discovery of the present invention, however,
that as the seam between the turbine wheel and turbine shaft is
welded, residual stresses are formed in the turbine wheel and
shaft. These residual stresses are directly related to the heat put
into the components during the welding process. The weld operation
is performed utilizing a focused beam such as via electron beam
welding, although laser welding or friction welding could also be
used. After the weld process is completed, a defocused beam can be
utilized to broaden the heating operation to relieve some of the
residual stresses imparted to the turbine wheel and shaft. However,
the turbine wheels and shaft assemblies that have been properly
balanced after the welding process are placed in use in a
turbocharger in which the temperatures can exceed 600.degree. C.
The heating of the turbine wheel and shaft assembly can cause the
residual stresses from the welding process to relax that can result
in wheel distortion. According to the theory of the discovery of
the present application, because the weld location 118 is so close
to the turbine wheel, a large amount of heat is required to
adequately relieve the residual stresses in the large mass of the
turbine wheel.
[0007] Accordingly, it is the intent of the present application to
move the weld location further away from the mass of the turbine
wheel body so that the weld is moved away from the large mass of
the turbine wheel and a defocused beam can more easily relieve the
residual stresses in the weld location. In addition, by moving the
weld location away from the body of the turbine wheel, the weld can
be placed in a lower operation temperature location to minimize the
effects of weld residual stress relaxation on the wheel imbalance
mitigation. Accordingly, the present disclosure provides a turbine
wheel and shaft assembly for a turbocharger including a turbine
wheel including a body portion supporting a plurality of blades on
a first axial face thereof. A hub extends from the body portion on
the second axial face. The hub has a predetermined diameter and a
length. A shaft is welded to the hub at a weld location spaced from
the axial face. The weld location is spaced axially from the second
axial face of the body portion by a distance that is at least 50
percent, and more preferably, at least 75 percent of the diameter
of the hub.
[0008] Further areas of applicability will become apparent from the
description provided herein. The description and specific examples
in this summary are intended for purposes of illustration only and
are not intended to limit the scope of the present disclosure.
DRAWINGS
[0009] The drawings described herein are for illustrative purposes
only of selected embodiments and not all possible implementations,
and are not intended to limit the scope of the present
disclosure.
[0010] FIG. 1 is a schematic view of an engine utilizing a
turbocharger, according to the principles of the present
disclosure;
[0011] FIG. 2 is a cross-sectional view of a turbine wheel and
shaft assembly according to the principles of the present
disclosure;
[0012] FIG. 3 is a cross-sectional view of a turbine wheel and
shaft assembly according to an alternative embodiment of the
present disclosure; and
[0013] FIG. 4 is a cross-sectional view of a prior art turbine
wheel and shaft assembly.
[0014] Corresponding reference numerals indicate corresponding
parts throughout the several views of the drawings.
DETAILED DESCRIPTION
[0015] Example embodiments will now be described more fully with
reference to the accompanying drawings.
[0016] Example embodiments are provided so that this disclosure
will be thorough, and will fully convey the scope to those who are
skilled in the art. Numerous specific details are set forth such as
examples of specific components, devices, and methods, to provide a
thorough understanding of embodiments of the present disclosure. It
will be apparent to those skilled in the art that specific details
need not be employed, that example embodiments may be embodied in
many different forms and that neither should be construed to limit
the scope of the disclosure. In some example embodiments,
well-known processes, well-known device structures, and well-known
technologies are not described in detail.
[0017] The terminology used herein is for the purpose of describing
particular example embodiments only and is not intended to be
limiting. As used herein, the singular forms "a," "an," and "the"
may be intended to include the plural forms as well, unless the
context clearly indicates otherwise. The terms "comprises,"
"comprising," "including," and "having," are inclusive and
therefore specify the presence of stated features, integers, steps,
operations, elements, and/or components, but do not preclude the
presence or addition of one or more other features, integers,
steps, operations, elements, components, and/or groups thereof. The
method steps, processes, and operations described herein are not to
be construed as necessarily requiring their performance in the
particular order discussed or illustrated, unless specifically
identified as an order of performance. It is also to be understood
that additional or alternative steps may be employed.
[0018] When an element or layer is referred to as being "on,"
"engaged to," "connected to," or "coupled to" another element or
layer, it may be directly on, engaged, connected or coupled to the
other element or layer, or intervening elements or layers may be
present. In contrast, when an element is referred to as being
"directly on," "directly engaged to," "directly connected to," or
"directly coupled to" another element or layer, there may be no
intervening elements or layers present. Other words used to
describe the relationship between elements should be interpreted in
a like fashion (e.g., "between" versus "directly between,"
"adjacent" versus "directly adjacent," etc.). As used herein, the
term "and/or" includes any and all combinations of one or more of
the associated listed items.
[0019] With reference to FIG. 1, a schematic view of a turbocharged
engine according to the principles of the present disclosure will
now be described. The engine 10 includes an engine structure 12
having a cylinder 14 therein. A piston 16 is provided within the
cylinder 14 and is connected to a crankshaft 18 as is known in the
art. The cylinder 14 defines a combustion chamber 20 that is in
communication with an intake port 22, an exhaust port 24, and a
fuel injector 26. The intake port 22 receives a compressed air flow
30 from a compressor 32 of a turbocharger 34. The exhaust port 24
is in communication with an engine exhaust gas flow passage 36
which is in communication with a turbine 38 of the turbocharger 34.
As the engine exhaust gas flow 36 passes through the turbine 38, a
turbine wheel 40 is caused to rotate within a turbine housing 42
and drives a turbine shaft 44 which is connected to a compressor
wheel 46 of the compressor 32. Therefore, the exhaust gas flow 36
causes rotation of the turbo charger turbine wheel 40 and
compressor wheel 46 which then compresses the intake air 48 that is
delivered to the air intake 22 of the engine. A compressed air
cooler 49 can cool the compressed air delivered to the air intake
22 and can include a fan 50.
[0020] According to the principles of the present disclosure, the
turbine wheel 40 and shaft 44 are assembled in a unique manner that
eliminates the imbalance problem of welded turbo wheel and shaft
assemblies. In particular, as shown in FIG. 2, the turbine wheel 40
includes a body portion 52 that supports a plurality of blades 54
on a first axial face 56 thereof. A hub 58 extends from the body
portion 52 on the second axial face 60. The hub 58 has a
predetermined diameter D. The shaft 44 is welded to the hub 58 at a
weld location 62 that is spaced from the second axial face 60 by a
distance d.sub.w. According to a preferred aspect of the present
disclosure, the weld location 62 is spaced axially from the second
axial face by a distance d.sub.w that is at least 50 percent, and
more preferably, at least 75 percent of the diameter D of the hub
58. With this preferred weld distance spaced from the body portion
52 of the turbine wheel 40, the weld location 62 is moved away from
the large mass portion of the body 52 so that less heat is put into
the parts and, therefore, less residual stress is created.
Furthermore, when the weld area is heated with a defocused beam,
stress relief in the smaller mass regions surrounding the weld
location 62 are more effective at relieving the residual stresses
that had been created during the welding process. Furthermore, the
weld location 62 being spaced a distance d.sub.w away from the body
52 of the turbine wheel moves the weld location 62 to a lower
operation temperature location within the turbocharger 34 to
minimize the effects of weld residual stress relaxation on the
wheel imbalance mitigation. There is typically a piston ring seal
located adjacent to the current practice weld location that
prevents oil from exiting the bearing housing. Moving the weld
location to position 62 locates the weld on the oil wetted side of
the piston ring seal 63 (shown schematically in FIG. 1), thereby
placing the welded location 62 in a significantly cooler
location.
[0021] To further reduce the residual stresses, it is advantageous
to also reduce the mass of the shaft 44 by providing a hollow
cylindrical shaft. In addition, the hub 58 can also be hollowed out
in order to reduce the mass in the weld region to thereby eliminate
distortion of the parts. It is noted that the removal of the
additional mass by providing a hollow shaft 44 and a hollow region
within the hub 58 is optional, although it can increase the cooling
rates of the parts while also reducing the residual stresses that
are generated during the welding process. In the embodiment shown
in FIG. 2, the shaft 44 is provided with an annular flange portion
64 at its end where it is welded to the hub portion 58 of the
turbine wheel 40. The weld location 62 is provided at the interface
between the flange 64 and the hub 58 as illustrated.
[0022] According to an alternative embodiment as illustrated in
FIG. 3, the weld location 62' can be provided between the hub
portion 58 and the unflanged end of the shaft 44'. It is noted that
at this location, the weld diameter can be reduced to the diameter
of the shaft 44' so that less circumferential area of welding is
required thereby providing less residual stress in the resultant
welded parts. It is noted that the amount of hollow region within
the hub 58 can be extended into the body portion 52 of the turbine
wheel 40. With these additional modifications, the turbine wheel
and shaft weight can be reduced thereby further reducing the turbo
wheel inertia and to provide wheel imbalance mitigation. According
to the principles of the present disclosure, the imbalance induced
noise issues can be eliminated or significantly reduced by the
proposed design configurations thereby significantly improving part
quality and performance.
[0023] The foregoing description of the embodiments has been
provided for purposes of illustration and description. It is not
intended to be exhaustive or to limit the disclosure. Individual
elements or features of a particular embodiment are generally not
limited to that particular embodiment, but, where applicable, are
interchangeable and can be used in a selected embodiment, even if
not specifically shown or described. The same may also be varied in
many ways. Such variations are not to be regarded as a departure
from the disclosure, and all such modifications are intended to be
included within the scope of the disclosure.
* * * * *