U.S. patent application number 14/573902 was filed with the patent office on 2016-06-23 for dual thrust bearing for a turbocharger.
This patent application is currently assigned to Electro-Motive Diesel, Inc.. The applicant listed for this patent is Electro-Motive Diesel, Inc.. Invention is credited to Raji REXAVIER, Gary R. SVIHLA, Alan R. WIEDMEYER.
Application Number | 20160177960 14/573902 |
Document ID | / |
Family ID | 56128905 |
Filed Date | 2016-06-23 |
United States Patent
Application |
20160177960 |
Kind Code |
A1 |
SVIHLA; Gary R. ; et
al. |
June 23, 2016 |
DUAL THRUST BEARING FOR A TURBOCHARGER
Abstract
A dual thrust bearing is disclosed. The dual thrust bearing may
have a shell. The shell may extend from a compressor end to a
turbine end opposite the compressor end. The shell may have a shell
bore extending from the compressor end to the turbine end. The
shell bore may be configured to receive a journal bearing. The
shell may also have a first thrust bearing face disposed adjacent
the compressor end. In addition, the shell may have a second thrust
bearing face disposed adjacent the turbine end.
Inventors: |
SVIHLA; Gary R.; (Burr
Ridge, IL) ; WIEDMEYER; Alan R.; (Aurora, IL)
; REXAVIER; Raji; (Plainfield, IL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Electro-Motive Diesel, Inc. |
LaGrange |
IL |
US |
|
|
Assignee: |
Electro-Motive Diesel, Inc.
LaGrange
IL
|
Family ID: |
56128905 |
Appl. No.: |
14/573902 |
Filed: |
December 17, 2014 |
Current U.S.
Class: |
417/407 |
Current CPC
Class: |
F04D 29/624 20130101;
F16C 17/10 20130101; F04D 29/0513 20130101; F04D 25/024 20130101;
F16C 2360/24 20130101 |
International
Class: |
F04D 29/051 20060101
F04D029/051; F04D 29/40 20060101 F04D029/40; F04D 25/04 20060101
F04D025/04 |
Claims
1. A dual thrust bearing, comprising: a shell extending from a
compressor end to a turbine end opposite the compressor end, the
shell including: a shell bore extending from the compressor end to
the turbine end, the shell bore being configured to receive a
journal bearing; a first thrust bearing face disposed adjacent the
compressor end; and a second thrust bearing face disposed adjacent
the turbine end.
2. The dual thrust bearing of claim 1, wherein the shell further
includes a flange disposed adjacent the compressor end, the flange
is configured to attach the dual thrust bearing to a bearing
housing, and the first thrust bearing face is disposed on the
flange.
3. The dual thrust bearing of claim 2, wherein the first thrust
bearing face includes a plurality of thrust pad sections disposed
circumferentially on the first thrust bearing face, each thrust pad
section extending circumferentially from a leading end to a
trailing end and extending radially from an inner wall to an outer
wall.
4. The dual thrust bearing of claim 3, wherein the thrust pad
sections include: a first thrust pad section; a second thrust pad
section; and a drain separating the first thrust pad section from
the second thrust pad section, the drain extending radially from
adjacent the inner wall to a flange outer surface.
5. The dual thrust bearing of claim 4, wherein the drain has a
first axial depth adjacent the inner wall and a second axial depth
smaller than the first axial depth adjacent the outer surface of
the flange.
6. The dual thrust bearing of claim 3, the thrust pad section
includes: a slot disposed adjacent the leading end; a thrust pad
disposed adjacent the trailing end; and a ramp disposed between the
slot and the thrust pad.
7. The dual thrust bearing of claim 6, wherein the ramp has a first
axial depth adjacent the slot and a second axial depth smaller than
the first axial depth adjacent the thrust pad.
8. The dual thrust bearing of claim 6, wherein the thrust pad
section further includes a rim extending circumferentially along
the outer wall from adjacent the slot to adjacent the thrust
pad.
9. The dual thrust bearing of claim 6, wherein the slot extends
radially from an inner slot end disposed adjacent the inner wall to
an outer slot end disposed adjacent the outer wall, and the slot
includes an inlet disposed adjacent the inner slot end, the inlet
being configured to dispense a metered amount of oil into the
slot.
10. A bearing assembly, comprising: a shell extending from a
compressor end to a turbine end opposite the compressor end; a
shell bore extending from the compressor end to the turbine end; a
first thrust bearing face disposed on the compressor end of the
shell; a second thrust bearing face disposed on the turbine end of
the shell; and a journal bearing disposed within the shell
bore.
11. The bearing assembly of claim 10, further including: an
impeller cap having a cap portion, a shaft portion disposed within
the journal bearing, an impeller cap bore, and an impeller step
face; a shaft disposed within the impeller cap bore; and a thrust
washer disposed on the shaft adjacent the turbine end.
12. The bearing assembly of claim 11, wherein the impeller step
face is disposed opposite the first thrust bearing face and axially
separated from the first thrust bearing face by a first gap; and
the thrust washer has a thrust washer front face disposed opposite
the second thrust bearing face and being axially separated from the
second thrust bearing face by a second gap.
13. The bearing assembly of claim 10, further including a flange
configured to mount the shell to a bearing housing, the first
thrust bearing face being disposed on a portion of the flange.
14. The bearing assembly of claim 13, further including: a wall of
the bearing housing, the wall having a front face and a rear face;
a fastener hole extending from the front face to the rear face; a
backing plate disposed adjacent the rear face; and a fastener
extending through the flange and the wall and threadingly engaged
with the backing plate to mount the shell to the bearing
housing.
15. The bearing assembly of claim 14, further including: an
alignment cavity in the wall, the alignment cavity extending from
the front face towards the rear face; and an alignment pin
extending from a knob portion to a stud portion, the knob portion
being received in the alignment cavity and the stud portion being
received in a pin recess in the journal bearing.
16. The bearing assembly of claim 13, wherein the first thrust
bearing face includes a plurality of thrust pad sections disposed
circumferentially on the first thrust bearing face, each thrust pad
section extending circumferentially from a leading end to a
trailing end and extending radially from an inner wall to an outer
wall.
17. The bearing assembly of claim 16, wherein the thrust pad
section includes: a slot disposed adjacent the leading end; a
thrust pad disposed adjacent the trailing end; and a ramp disposed
between the slot and the thrust pad.
18. The bearing assembly of claim 17, wherein the ramp has a
generally flat surface disposed at an angle relative to the thrust
pad.
19. The bearing assembly of claim 16, wherein the thrust pad
sections include: a first thrust pad section; a second thrust pad
section; and a drain separating the first thrust pad section from
the second thrust pad section, the drain extending radially from
adjacent the inner wall to a flange outer surface.
20. A turbocharger, comprising: a turbine housing; a turbine wheel
disposed within the turbine housing and configured to be rotated by
exhaust received from an engine; a compressor housing; a shaft
attached to the turbine wheel, the shaft extending from the turbine
housing to the compressor housing; a compressor impeller disposed
within the compressor housing, the compressor impeller being
configured to be driven by the turbine wheel via the shaft; a
bearing housing connecting the turbine housing with the compressor
housing; a bearing assembly disposed within the bearing housing,
the bearing assembly including: a shell extending from a compressor
end to a turbine end; a shell bore in the shell extending from the
compressor end to the turbine end; a journal bearing extending from
the compressor end to the turbine end, the journal bearing being
disposed within the shell bore; a thrust washer disposed on the
shaft adjacent the turbine end; a first thrust bearing face
disposed on the compressor end of the shell, the first thrust
bearing face being axially separated from the compressor impeller
by a first gap; and a second thrust bearing face disposed on the
turbine end of the shell, the second thrust bearing face being
axially separated from the thrust washer by a second gap.
Description
TECHNICAL FIELD
[0001] The present disclosure relates generally to a dual thrust
bearing and, more particularly, to a dual thrust bearing for a
turbocharger.
BACKGROUND
[0002] Internal combustion engines, for example, diesel engines,
gasoline engines, or natural gas engines employ turbochargers to
deliver compressed air for combustion in the engine. A turbocharger
compresses air flowing into the engine, helping to force more air
into combustion chambers of the engine. The increased supply of air
allows for increased fuel combustion in the combustion chambers of
the engine, resulting in an increased power output from the
engine.
[0003] A typical turbocharger includes a shaft, a turbine wheel
connected to one end of the shaft, a compressor wheel connected to
the other end of the shaft, and bearings to support the shaft.
Separate housings connected to each other enclose the compressor
wheel, the turbine wheel, and the bearings. Exhaust from the engine
expands over the turbine wheel and rotates the turbine wheel. The
turbine wheel in turn rotates the compressor wheel via the shaft.
The compressor wheel receives cool air from the ambient and forces
compressed air into combustion chambers of the engine.
[0004] The flows of exhaust and compressed air over the turbine
wheel and the compressor wheel, respectively, exert radial and
axial loads on the shaft. Turbochargers typically include at least
two separate journal bearings and two separate thrust bearings to
counter the radial and axial loads, respectively, generated by the
compressor and turbine portions of the turbocharger. Proper
functioning of the turbocharger requires accurate positioning or
centering of the different types of bearings within the bearing
housing. Maintaining two separate thrust bearings, however, adds
complexity and increases the volume of the turbocharger. In
particular, use of separate bearings increases the dimensional
tolerance stack for the turbocharger, requiring larger clearances
between the rotating parts. The larger clearances in turn make it
difficult to minimize leakage of oil from the turbocharger to the
ambient and leakage of dust and ambient air into the
turbocharger.
[0005] One attempt to address some of the problems described above
is disclosed in U.S. Pat. No. 6,017,184 of Aguilar et al. that
issued on Jan. 25, 2000 ("the '184 patent"). In particular, the
'184 patent discloses an integrated bearing system with journal and
thrust bearings incorporated in a single unit centrally pinned to
the bearing housing. The '184 patent discloses that the bearing is
carried within a bearing case bore of the center housing and that
thrust surfaces are located at opposite ends of the bearing. One
thrust surface of the bearing engages a thrust runner on the
turbine wheel hub, whereas the other thrust surface of the bearing
engages a thrust surface integrated into the hub of a compressor
wheel.
[0006] Although the '184 patent discloses an integrated bearing
that includes a journal bearing and thrust surfaces on opposing
ends of the bearing, the disclosed bearing may still be less than
optimal. In particular, thrust loads on the bearing of the '184
patent may be reacted on the alignment pin or on a shoulder of the
center housing. Unequal thrust loads on the two thrust faces of the
bearing of the '184 patent may skew the bearing relative to an axis
of rotation of the bearing, which in turn may constrain the
rotation of the shaft within the journal portion of the bearing. In
addition, because the integrated bearing of the '184 patent
directly attaches to the center housing, a typical rotor failure
may damage both the bearing and the mounting surfaces of the center
housing, requiring expensive and time consuming repairs or
replacement of the center housing.
[0007] The dual thrust bearing of the present disclosure solves one
or more of the problems set forth above and/or other problems of
the prior art.
SUMMARY
[0008] In one aspect, the present disclosure is directed to a dual
thrust bearing. The dual thrust bearing may include a shell. The
shell may extend from a compressor end to a turbine end opposite
the compressor end. The shell may include a shell bore extending
from the compressor end to the turbine end. The shell bore may be
configured to receive a journal bearing. The shell may also include
a first thrust bearing face disposed adjacent the compressor end.
In addition, the shell may include a second thrust bearing face
disposed adjacent the turbine end.
[0009] In another aspect, the present disclosure is directed to a
bearing assembly. The bearing assembly may include a shell
extending from a compressor end to a turbine end opposite the
compressor end. The bearing assembly may also include a shell bore
extending from the compressor end to the turbine end. Further, the
bearing assembly may include a first thrust bearing face disposed
on the compressor end of the shell. The bearing assembly may also
include a second thrust bearing face disposed on the turbine end of
the shell. In addition, the bearing assembly may include a journal
bearing disposed within the shell bore
[0010] In yet another aspect, the present disclosure is directed to
a turbocharger. The turbocharger may include a turbine housing. The
turbocharger may also include a turbine wheel disposed within the
turbine housing. The turbine wheel may be configured to be rotated
by exhaust received from an engine. The turbocharger may also
include a compressor housing. Further the turbocharger may include
a shaft attached to the turbine wheel. The shaft may extend from
the turbine housing to the compressor housing. A compressor
impeller may be disposed within the compressor housing. The
compressor impeller may be configured to be driven by the turbine
wheel via the shaft. The turbocharger may include a bearing housing
connecting the turbine housing with the compressor housing. The
turbocharger may also include a bearing assembly disposed within
the bearing housing. The bearing assembly may include a shell
extending from the compressor end to the turbine end. The bearing
assembly may also include a shell bore in the shell extending from
the compressor end to the turbine end. Further, the bearing
assembly may include a journal bearing extending from a compressor
end to a turbine end. The journal bearing may be disposed within
the shell bore. The bearing assembly may include a thrust washer
disposed on the shaft adjacent the turbine end. The bearing
assembly may also include a first thrust bearing face disposed on
the compressor end of the shell. The first thrust bearing face may
be axially separated from the compressor impeller by a first gap.
The bearing assembly may further include a second thrust bearing
face disposed on the turbine end of the shell. The second thrust
bearing face may be axially separated from the thrust washer by a
second gap.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 is a cut-away view of an exemplary disclosed
turbocharger;
[0012] FIG. 2 is a cut-away view of an exemplary disclosed bearing
assembly for the turbocharger of FIG. 1;
[0013] FIG. 3 is a cut-away view of an exemplary disclosed dual
thrust bearing for the turbine bearing assembly of FIG. 2;
[0014] FIG. 4 is a cut-away view of an exemplary disclosed thrust
bearing face of the dual thrust bearing of FIG. 3;
[0015] FIG. 5 is another cut-away view of the exemplary disclosed
thrust bearing face of FIG. 4; and
[0016] FIG. 6 is a cut away view of another exemplary disclosed
thrust bearing face of the dual thrust bearing of FIG. 3.
DETAILED DESCRIPTION
[0017] FIG. 1 illustrates an exemplary embodiment of a turbocharger
10. Turbocharger 10 may be used with an engine (not shown) of a
machine that performs some type of operation associated with an
industry such as railroad, marine, power generation, mining,
construction, farming, or another industry known in the art. As
shown in FIG. 1, turbocharger 10 may include compressor stage 12
and turbine stage 14. Shaft 16 may extend between compressor stage
12 and turbine stage 14. Shaft 16 may be supported by one or more
bearing assemblies 18 and/or bearings 20. Compressor stage 12 may
embody a fixed geometry compressor impeller 22 connected to shaft
16 and configured to compress air received from an ambient to a
predetermined pressure level before the air enters the engine for
combustion. Air may enter compressor housing 24 via compressor
inlet 26 and exit compressor housing 24 via compressor outlet 28.
As air moves through compressor stage 12, compressor impeller 22
may force compressed air into the engine. Compressing the air may
heat the air, which in turn may heat compressor impeller 22,
compressor housing 24, bearing housing 38, and other components of
the turbocharger located near compressor stage 12.
[0018] Turbine stage 14 may be a fixed geometry turbine. Turbine
stage 14 may include turbine housing 30 and turbine wheel 32, which
may be attached to shaft 16. Exhaust gases exiting the engine may
enter turbine housing 30 via turbine inlet 34 and exit turbine
housing 30 via turbine outlet 36. As the hot exhaust gases move
through turbine housing 30 and expand against the blades of turbine
wheel 32, turbine wheel 32 may rotate compressor impeller 22 via
shaft 16. The hot exhaust gases may also heat turbine housing 30,
which in turn may heat compressor housing 24, bearing housing 38,
and other components of the turbocharger attached to or located
near turbine housing 30.
[0019] FIG. 2 illustrates a cut-away view of an exemplary
embodiment of a bearing assembly 18 for turbocharger 10. Bearing
assembly 18 may include bearing housing 38, dual thrust bearing 50,
journal bearing 52, alignment pin 54, impeller cap 56, and thrust
washer 58. Bearing housing 38, dual thrust bearing 50, journal
bearing 52, alignment pin 54, impeller cap 56, and thrust washer 58
may be disposed around a rotational axis 60 of bearing assembly 18.
As illustrated in FIG. 2, bearing housing 38 may engage with dual
thrust bearing 50 at first bore 70 and second bore 72. Bearing
housing 38 may also include a wall 74, which may extend radially
towards rotational axis 60. Wall 74 may have a front face 78 and a
rear face 80. Wall 74 may include one or more fastener holes 76,
which may extend from front face 78 to rear face 80 of wall 74.
Fastener hole 76 may be configured to receive fastener 82, which
may be configured to attach dual thrust bearing 50 to bearing
housing 38. Bearing housing 38 may also include an alignment cavity
84 that may extend axially from front face 78 of wall 74 towards
rear face 80 to a depth "l.sub.1," which may be shorter than a
thickness "l.sub.2" of wall 74. Alignment cavity 84 may be
generally cylindrical and may have a longitudinal axis 86, which
may be disposed generally parallel to rotational axis 60.
[0020] Dual thrust bearing 50 may include shell 100 that may extend
from compressor end 102 to turbine end 104. Shell 100 may include a
generally cylindrical shell bore 106 that may extend from
compressor end 102 to turbine end 104. Shell bore 106 may be
configured to receive journal bearing 52. Shell 100 may include a
flange 108 that may be configured to mount dual thrust bearing 50
to bearing housing 38. Flange 108 may be disposed adjacent
compressor end 102. Flange 108 may have a flange front face 110 and
a flange rear face 112 opposite flange front face 110. Flange rear
face 112 may be disposed between flange front face 110 and turbine
end 104. Flange 108 may have a thickness "l.sub.3," which may be
smaller than a length "L" of shell 100. Flange 108 may have a
flange outer surface 114 that may engage with first bore 70 of
bearing housing 38. In one exemplary embodiment, flange outer
surface 114 may engage with first bore 70 of bearing housing 38 via
an interference fit. It is contemplated, however, that flange outer
surface 114 may engage with first bore 70 of bearing housing 38 via
a clearance fit.
[0021] Flange 108 may also include one or more fastener holes 116.
In one exemplary embodiment as illustrated in FIG. 2, fastener hole
116 may be a stepped through hole, which may be configured to
receive fastener 82. Fastener 82 may pass through fastener hole 116
in flange 108 and fastener hole 76 in wall 74 of bearing housing
38. Fastener 82 may threadingly engage with threaded hole 118 in
back plate 120 to attach dual thrust bearing 50 to bearing housing
38. Although FIG. 2 illustrates only one back plate 120, it is
contemplated that bearing assembly 18 may include any number of
back plates 120, each of which may include threaded holes 118
configured to threadingly engage with fasteners 82. It is also
contemplated that flange 108 may be attached to wall 74 of bearing
housing 38 using bolts (not shown) that may engage with fasteners
82.
[0022] Shell 100 may also include a hub 130 disposed adjacent
turbine end 104. Hub 130 may have a hub front face 132 and a hub
rear face 134 opposite hub front face 132. Hub front face 132 may
be disposed between hub rear face 134 and flange rear face 112. Hub
130 may have an axial length "l.sub.4" between hub front face 132
and hub rear face 136. Length l.sub.4 may be smaller than length L
of shell 100. Hub 130 may have a hub outer surface 136 that may
engage with second bore 72 of bearing housing 38 via a clearance
fit. Hub 130 may also include a circumferential groove 138 disposed
on hub outer surface 136. Seal member 140 may be disposed within
groove 138 between hub outer surface 136 and second bore 72 of
bearing housing 38. In one exemplary embodiment as illustrated in
FIG. 2, seal member 140 may be an O-ring. It is contemplated,
however, that seal member 140 may be a gasket or any other type of
sealing element known in the art.
[0023] Shell 100 may have a first thrust bearing face 142 adjacent
compressor end 102. First thrust bearing face 142 may be disposed
on flange front face 110 of shell 100. First thrust bearing face
142 may be axially separated from compressor impeller 22 by first
gap 144. Shell 100 may also have a second thrust bearing face 146
disposed adjacent turbine end 104. Second thrust bearing face 146
may be disposed on hub rear face 134. Second thrust bearing face
146 may be axially separated from thrust washer 58 by second gap
148. Shell 100 may include a recess 150 disposed between flange
rear face 112 and to hub front face 132. Recess 150 may be
generally annular and may have a recess inner surface 152 that may
have an outer diameter "D.sub.1," which may be smaller than a
diameter "D.sub.2" of hub outer surface 136. Pressurized oil may be
supplied from an oil pump (not shown) via passageways (not shown)
in bearing housing 38 to recess 150. Oil may flow from recess 150
through passageways (not shown) in shell 100 to shell bore 106 and
first and second thrust bearing faces 142, 146.
[0024] Journal bearing 52 may be disposed within shell bore 106
between compressor end 102 and turbine end 104. Journal bearing 52
may have a generally cylindrical shape, which may have a journal
outer surface 152 and a journal inner surface 154. Journal outer
surface 152 may engage with shell bore 106 via an interference fit.
It is contemplated, however, that journal outer surface 152 may
engage with shell bore 106 via a clearance fit. Journal bearing 52
may include pin recess 156 disposed on journal outer surface 152.
Pin recess 156 may be configured to receive alignment pin 54. Pin
recess 156 may have a generally cylindrical shape. It is
contemplated, however, that pin recess 158 may have an elliptical,
triangular, square, polygonal or any other shape known in the
art.
[0025] Alignment pin 54 may have a knob portion 162, which may be
received in alignment cavity 84. In one exemplary embodiment as
illustrated in FIG. 2, knob portion 162 of alignment pin 54 may
have a generally spherical shape, which may be configured to
slidingly engage with alignment cavity 84. It is contemplated,
however, that knob portion 162 of alignment pin 54 may have an
oval, cuboidal, or any other shape that matches a shape of the
alignment cavity 84. Alignment pin 54 may extend from the knob
portion to a stud portion 164, which may engage with pin recess 158
via an clearance fit. Stud portion 164 of alignment pin 54 may have
a cross-section that matches a shape of pin recess 156 to allow
engagement of alignment pin 54 with journal bearing 52. In one
exemplary embodiment as illustrated in FIG. 2, knob portion 162 of
alignment pin 54 may engage with alignment cavity 84 to help
prevent rotation of journal bearing 52 around rotational axis 60.
Alignment cavity 84 may also limit lateral movement of alignment
pin 54 along rotational axis 60, which may help prevent axial
movement of journal bearing 52 within dual thrust bearing 50.
[0026] Compressor impeller 22 may include an impeller cap 56, which
may include a cap portion 166 and a shaft portion 168. Cap portion
166 of impeller cap 56 may be connected to compressor impeller 22
so that compressor impeller 22 rotates with impeller cap 56. Shaft
portion 168 of impeller cap 56 may be attached to cap portion 166.
Shaft portion 168 of impeller cap 56 may be disposed within journal
bearing 52. Cap portion 166 of impeller cap 56 may have an outer
diameter "D.sub.3," which may be larger than an outer diameter
"D.sub.4" of shaft portion 168 of impeller cap 56. Cap portion 166
of impeller cap 56 may transition from diameter D.sub.1 to diameter
D.sub.2 of shaft portion 168 via impeller step 170. Impeller step
170 may have an impeller step face 172, which may be disposed
opposite to and spaced apart from first thrust bearing face 142 of
dual thrust bearing 50. In one exemplary embodiment as illustrated
in FIG. 2, impeller step face 172 may be separated from first
thrust bearing face 142 via first gap 144.
[0027] Impeller cap 56 may also include an impeller cap bore 176
configured to receive shaft 16. Shaft 16 may engage with impeller
cap bore 176 via an interference fit, a keyed joint, a welded
joint, a threaded joint, or by any other type of attachment known
in the art. Shaft 16 may include shaft step 178 disposed adjacent
turbine end 104. Shaft 16 may transition from a diameter "D.sub.5"
within impeller cap bore 176 to a diameter "D.sub.6" adjacent
turbine end 104. In one exemplary embodiment as shown in FIG. 2,
diameter D.sub.6 may be larger than diameter D.sub.5. Shaft step
178 may have shaft step face 180 disposed opposite to and axially
separated from hub rear face 134.
[0028] Thrust washer 58 may be disposed on shaft portion 168 of
impeller cap 56 adjacent turbine end 104. In one exemplary
embodiment as illustrated in FIG. 2, thrust washer 58 may be
disposed between shaft step face 180 and hub rear face 134. Thrust
washer 58 may be attached to shaft portion 168 and may be
configured to rotate with shaft 16. Thrust washer 58 may be
attached to shaft 16 via an interference fit, a keyed joint, a
welded joint, a threaded joint, or by any other type of attachment
known in the art. Thrust washer 58 may have a thrust washer front
face 182 and a thrust washer rear face 184. Thrust washer front
face 182 may be disposed adjacent to and axially spaced apart from
second thrust bearing face 146 via second gap 148. Thrust washer
rear face 184 may abut shaft step face 180. Pressurized oil may
flow via passageways (not shown) in shell 100 to first and second
gaps 144, 148. Pressurized oil in first and second gaps 144, 148
may flow circumferentially and radially over first and second
thrust bearing faces 142, 146, respectively to help counter axial
loads on shaft 16.
[0029] FIG. 3 illustrates a cut-away view showing portions of first
thrust bearing face 142. First thrust bearing face 142 may extend
radially between an inner wall 192 and an outer wall 194. Inner
wall 192 may have a diameter smaller than a diameter of outer wall
194. First thrust bearing face 142 may include a plurality of
thrust pad sections 196 circumferentially disposed on first thrust
bearing face. Adjacent thrust pad sections 196 may be
circumferentially separated by radially extending drains 198. Each
thrust pad section 196 may extend circumferentially from a leading
end 200 to a trailing end 202. Thrust pad section 196 may include
slot 204, thrust pad 206, ramp 208, and rim 210. Slot 204 may be
disposed adjacent leading end 200 of thrust pad section 196. In one
exemplary embodiment as illustrated in FIG. 3, slot 204 may extend
radially from an inner slot end 212 disposed adjacent inner wall
192 to an outer slot end 214 disposed adjacent outer wall 194. As
illustrated in FIG. 3, inner slot end 212 and outer slot end 214
may not extend all the way to inner wall 192 and outer wall 194,
respectively. Slot 204 may also have rounded edges at inner and
outer slot ends 212, 214. Slot 204 may be shallow relative to
thickness l.sub.3 of flange 108. Slot 204 may include an inlet 216.
In one exemplary embodiment as illustrated in FIG. 3, inlet 216 may
be disposed nearer inner slot end 212 compared to outer slot end
214. Inlet 216 may have a generally circular shape. It is
contemplated, however, that inlet 216 may have an elliptical,
polygonal, or any other type of shape known in the art. Inlet 216
may be configured to allow pressurized oil to flow from recess 150
via passageways (not shown) in shell 100 into slot 204. In one
exemplary embodiment, a size of inlet 216 may be selected to allow
a metered amount of oil to flow through inlet 216 first thrust
bearing face 142.
[0030] Thrust pad 206 may be located adjacent trailing end 202 of
thrust pad section 196. Thrust pad 206 may extend between an inner
edge 218 and an outer edge 220, forming a generally flat surface in
a plane orthogonal to rotational axis 60. For example, inner edge
218 may be circumferentially spaced closer to outer edge 220
adjacent inner wall 192 as compared to adjacent outer wall 194.
Outer edge 220 of thrust pad 206 may abut drain 198. Thrust pad 206
may have a generally flat surface which may be disposed generally
orthogonal to rotational axis 60.
[0031] Ramp 208 may extend circumferentially from adjacent slot 204
to thrust pad 206. FIG. 4 illustrates a cut-away view showing
portions of thrust pad section 196. As illustrated in FIG. 4, ramp
208 may extend from leading edge 222 adjacent slot 204 to trailing
edge 224 that abuts inner edge 218 of thrust pad 206. Ramp 208 may
have a generally flat surface, which may be disposed at an angle
relative to thrust pad 206. For example, ramp 208 may be disposed
at an axial depth "h.sub.1" adjacent slot 204 and at an axial depth
"h.sub.2" adjacent thrust pad 206. In one exemplary embodiment as
shown in FIG. 4, axial depth h.sub.2 may be smaller than axial
depth h.sub.1. Oil entering slot 204 via inlet 216 may sweep or
flow over ramp 208 and thrust pad 206 before entering drain 198. As
also shown in FIG. 4, rim 210 of thrust pad section 196 may extend
circumferentially along outer wall 194 from adjacent slot 204 to
adjacent thrust pad 206. Rim 210 may prevent oil sweeping over ramp
208 from flowing radially outward, thereby helping to generate
increased thrust pressure on thrust pad section 196. Rim 210 may
also help direct oil flow from ramp 208 towards drain 198.
[0032] Returning to FIG. 3, drain 198 may be disposed between
adjacent thrust pad sections 196 and may circumferentially separate
adjacent thrust pad sections 196. For example, drain 198 may extend
circumferentially from a trailing end 202 of a thrust pad section
196 to a leading end 200 of an adjacent thrust pad section 196.
Drain 198 may also extend radially from adjacent inner wall 192 of
thrust pad section 196 to adjacent flange outer surface 114. In one
exemplary embodiment as illustrated in FIG. 3, drain 198 may have a
generally rectangular channel cross section. It is contemplated,
however, that drain 198 may have a cross-section of square,
semi-circular or any other shape known in the art. FIG. 5
illustrates another cut-away view of thrust pad section 196. As
illustrated in FIG. 5, drain 198 may have a first axial depth
"h.sub.3" along rotational axis 60 adjacent inner wall 192 of
thrust pad section 196. Drain 198 may have a second axial depth
"h.sub.4" adjacent flange outer surface 114. In one exemplary
embodiment as illustrated in FIG. 5, axial depth h.sub.4 may be
smaller than axial depth h.sub.3. Drain 198 may help to drain the
metered amount of oil dispensed via inlet 216 by directing the oil
radially outward and away from first thrust bearing face 142.
Dispensing and draining a metered amount of oil from each thrust
pad section 196, may help ensure that dual thrust bearing 50 does
not experience excessive thrust pressure on first thrust bearing
face 142.
[0033] FIG. 6 illustrates a cut-away view showing details of second
thrust bearing face 146 of dual thrust bearing 50. Second thrust
bearing face 146 may extend radially between an inner wall 232 and
an outer wall 234. Inner wall 232 may have a diameter smaller than
a diameter of outer wall 234. Like first thrust bearing face 142,
second thrust bearing face 146 may also include a plurality of
thrust pad sections 236 circumferentially disposed on second thrust
bearing face 146. Adjacent thrust pad sections 236 on second thrust
bearing face 146 may be circumferentially separated by radially
extending drains 238. Each thrust pad section 236 may include slot
240, thrust pad 242, ramp 244, and rim 246, each of which may have
a structure and function similar to slot 204, thrust pad 206, ramp
208, and rim 210, respectively, as described above with respect to
first thrust bearing face 142. Like slot 204, slot 240 may also
include an inlet 250 disposed within slot 240 and configured to
dispense pressurized oil to slot 240. Drain 238 may extend radially
from adjacent inner wall 232 of thrust pad section 236 to adjacent
outer wall 234. Drain 238 may have a structure and function similar
to that of drain 198 as described above with respect to first
thrust bearing face 142.
INDUSTRIAL APPLICABILITY
[0034] The disclosed dual thrust bearing 50 may be implemented in
any turbocharger 10 in which shaft 16 is subjected to axial and
radial loads during operation. The disclosed dual thrust bearing 50
may offer a compact bearing assembly 18 that includes a journal
bearing 52 to help support radial loads on shaft 16 and a dual
thrust bearing 50 to help support axial loads produced by
compressor stage 12 and turbine stage 14.
[0035] Disposing journal bearing 52 between first and second thrust
bearing faces 142, 146 of dual thrust bearing 50 may also help
reduce a volume of bearing housing 38 required to accommodate
bearing assembly 18. Additionally, attaching dual thrust bearing 50
to wall 74 of bearing housing 38 via fasteners 82 may help reduce a
number of portions of bearing housing 38 that may be required to
engage with dual thrust bearing 50 to position dual thrust bearing
50 within bearing housing 38. Reducing the number of portions of
bearing housing 38 that engage with dual thrust bearing 50 may help
relax machining tolerances on bearing housing 38 by reducing the
number of portions of bearing housing 38 required to be concentric
with shaft 16 and dual thrust bearing 50. The disclosed dual thrust
bearing 50 may also help reduce or eliminate damage to bearing
housing 38 in the event of a failure of compressor impeller 22.
Failure of compressor impeller 22 may cause off-axis rotation of
impeller cap 56, causing shaft portion 168 of impeller cap 56 to
come into contact with journal inner surface 156. Further, the
off-axis rotation may cause impeller step face 172 and thrust
washer front face 182 to come into contact with first and second
thrust bearing faces 142, 146, respectively. Such contact may cause
mechanical damage to journal bearing 52, alignment pin 54, and
first and second thrust bearing faces 142, 146 of dual thrust
bearing 50. However, because dual thrust bearing 50 remains
securely fastened to bearing housing 38 via fasteners 82, little to
no damage may be imparted to first and second bores 70, 72, wall
74, or other surfaces of bearing housing 38. Reducing or
eliminating the damage caused to bearing housing 38 may help to
reduce the expense and the amount of time required to repair
turbocharger 10.
[0036] A temperature of the oil may increase as the oil flows over
journal outer surface 154, journal inner surface 156, and first and
second thrust bearing faces 142, 146. The disclosed dual thrust
bearing 50 may help to reduce an amount of increase in oil
temperature. Referring to FIGS. 2, 3, and 6, during operation of
turbocharger 10, pressurized oil may flow from recess 150 via
passageways in shell 100 to journal outer surface 154 and first and
second thrust bearing faces 142, 146. Pressurized oil may also flow
axially along journal inner surface 156 to first and second thrust
bearing faces 142, 146. The oil may wipe across ramps 208 and
thrust pads 206 of a thrust pad section 196 of first thrust bearing
face 142 and flow into drains 198 without wiping over the surfaces
of an adjacent thrust pad section 196. Oil may similarly flow over
a thrust pad section 236 of second thrust bearing face 146 and flow
into drain 238 without flowing over an adjacent thrust pad section
236 of second thrust bearing face 146. By preventing a flow of oil
over more than one thrust pad section 196 or 236, the disclosed
dual thrust bearing 50 may help to reduce an amount of heating of
the oil as the oil flows over first and second thrust bearing faces
142, 146.
[0037] The disclosed dual thrust bearing 50 may also help to cool
bearing housing 38, which in turn may help to reduce temperature of
both the compressor impeller 22 and bearing housing adjacent to the
turbine journal bearing 20. For example, heat generated through
compressing intake air may increase a temperature of compressor
impeller 22, compressor housing 24, and bearing housing 38.
Compressor impeller 22 may be further heated by heat radiating back
from compressor housing 24 and bearing housing 38 to compressor
impeller 22. Rotation of impeller cap 56 and thrust washer 58 may
impart centrifugal force on the oil in first and second gaps 144,
148. Drains 198 and 238 may help to fling the oil radially outward
towards the walls of bearing housing 38 to provide improved cooling
of bearing housing 38 during operation of turbocharger 10. Cooling
bearing housing 38 in this manner may help to reduce heating of
compressor impeller 22, which may help to increase the operating
life of compressor impeller 22.
[0038] It will be apparent to those skilled in the art that various
modifications and variations can be made to the disclosed dual
thrust bearing. Other embodiments will be apparent to those skilled
in the art from consideration of the specification and practice of
the disclosed dual thrust bearing. It is intended that the
specification and examples be considered as exemplary only, with a
true scope being indicated by the following claims and their
equivalents.
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