U.S. patent application number 09/874808 was filed with the patent office on 2002-12-05 for diverted flow thrust bearing.
Invention is credited to Aguilar, Scott Grover.
Application Number | 20020181811 09/874808 |
Document ID | / |
Family ID | 25364617 |
Filed Date | 2002-12-05 |
United States Patent
Application |
20020181811 |
Kind Code |
A1 |
Aguilar, Scott Grover |
December 5, 2002 |
Diverted flow thrust bearing
Abstract
A hydrodynamic thrust bearing having a series arrangement of
three differently configured land sections across the bearing axial
surface that are separated by an oil supply groove (on one side)
and an oil return or collection grove (on an opposite side).
Configured in this manner, oil is provided onto the series of land
sections by the oil supply groove and is collected after passing
over the series of land sections by the separate oil collection
groove. The use of separate oil supply and collection grooves acts
to minimize mixing, of input oil with the heated return oil,
thereby reducing oil film temperature and increasing bearing thrust
load capacity.
Inventors: |
Aguilar, Scott Grover; (La
Crescenta, CA) |
Correspondence
Address: |
Felix L. Fischer
Honeywell International Inc.
Suite 200
23326 Hawthorne Boulevard
Torrance
CA
90505
US
|
Family ID: |
25364617 |
Appl. No.: |
09/874808 |
Filed: |
June 5, 2001 |
Current U.S.
Class: |
384/123 |
Current CPC
Class: |
F16C 33/106 20130101;
F16C 33/1075 20130101; F16C 2360/24 20130101; F16C 17/047
20130101 |
Class at
Publication: |
384/123 |
International
Class: |
F16C 032/06 |
Claims
1. A hydrodynamic thrust bearing comprising: an annular bearing
body having central shaft opening and an axially-directed face at
one of the body axial ends, the face comprising: an oil supply
channel disposed adjacent a body inside diameter; an oil return
channel disposed adjacent a body outside diameter; a number of
thrust pads defined along one end surface by an oil supply groove
extending radially a partial distance across the face from the oil
supply channel, and defined along another end surface by an oil
return groove extending radially a partial distance across the face
from the oil return channel, the oil supply groove and the oil
return groove separated from one another by a separator rib that
prevents oil migration therebetween.
2. A hydrodynamic thrust bearing as defined in claim 1 wherein a
leading edge of each of the thrust pads is adjacent the oil supply
groove and the trailing edge of each pad is adjacent the oil return
groove.
Description
FIELD OF THE INVENTION
[0001] This invention relates generally to the field of
turbochargers and, more particularly, to a turbine shaft thrust
bearing having separate oil inlet and oil outlet paths across a
bearing axial surface, thereby providing improved bearing thrust
load capacity and reduced oil film temperature.
BACKGROUND OF THE INVENTION
[0002] Turbochargers for gasoline and diesel internal combustion
engines are devices known in the art that are used for pressurizing
or boosting the intake air stream, routed to a combustion chamber
of the engine, by using the heat and volumetric flow of exhaust gas
exiting the engine. Specifically, the exhaust gas exiting the
engine is routed into a turbine housing of a turbocharger in a
manner that causes an exhaust gas-driven turbine to spin within the
housing. The exhaust gas-driven turbine is mounted onto one end of
a shaft that is common to a radial air compressor mounted onto an
opposite end of the shaft. Thus, rotary action of the turbine also
causes the air compressor to spin within a compressor housing of
the turbocharger that is separate from the exhaust housing. The
spinning action of the air compressor causes intake air to enter
the compressor housing and be pressurized or boosted a desired
amount before it is mixed with fuel and combusted within the engine
combustion chamber.
[0003] The common shaft extending between the turbine and
compressor is disposed through a turbocharger center housing that
includes a bearing assembly for: (1) facilitating shaft rotation;
(2) controlling axially directed shaft thrust effects and radially
directed shaft vibrations; (3) providing necessary lubrication to
the rotating shaft to minimize friction effects and related wear;
and (4) providing a seal between the lubricated assembly and the
turbine and compressor housings. The common shaft as used in
turbocharger applications is known to have shaft-rotating speeds on
the order of 60,000 to 80,000 rpm. Under such operating conditions
it is imperative that the bearing assembly provide sufficient
lubrication to the shaft to minimize the extreme friction effects
that take place at such high rotating speeds, thereby extending
shaft service life.
[0004] A thrust bearing is installed in the turbocharger center
housing and is used to control the amount of axially directed
thrust, or thrust load, that is imposed on the turbine shaft. The
thrust bearing can either be hydrodynamic or non-hydrodynamic. As
used herein, the term "hydrodynamic" is understood to refer to
pumped oil migration, or diverted oil flow, across an axial face of
a thrust bearing, and the term "nonhydrodynamic" is understood to
refer to a type of thrust bearing that is not designed to pump oil
across an axial thrust bearing face or surface.
[0005] Hydrodynamic thrust bearings known in the art comprise an
annular body that is disposed within the turbocharger bearing
housing, around the turbine shaft. Such bearing includes an
axially-facing frontside surface that is positioned adjacent an
opposed housing member surface, and that includes a number of
grooves or channels that are disposed radially across the frontside
surface from an inside bearing diameter to an outside bearing
diameter. Each such groove is separated by a surface section or
pad.
[0006] The frontside surface, comprising the grooves and pads, is
designed to distribute lubricating oil thereover in the following
manner. Fresh oil is pumped into an inlet end of each groove
adjacent the frontside surface inside diameter, and migrates from
that groove circularly over the pad and radially towards the
frontside surface outside diameter. As the oil is moved over the
pad it is heated by the thrust bearing surface and moved towards an
adjacent groove. The heated oil enters the adjacent groove, that
was also an oil supply groove for an adjacent pad, and travels
radially outwardly along the groove to the frontside surface
outside diameter, where the heated oil exits the thrust bearing. In
this manner, oil is circulated over each thrust bearing pad, via
each groove that acts in both an oil supply and oil collection
capacity.
[0007] Hydrodynamic thrust bearings provides a thrust load capacity
that is dependent on the operating temperature of the oil film
disposed between the thrust bearing and the adjacent housing member
axial surface. It is a well known fact that the thrust load
capacity for such bearings is inversely proportional to the oil
film temperature across the bearing. It has been discovered that
the above-described hydrodynamic thrust bearings do not provide a
maximum degree of thrust load capacity because of the high oil-film
temperatures that are experienced across the bearing. A reduced
thrust load capacity has an adverse impact on turbocharger service
life as is allows undesired turbine shaft axial play that causes
premature turbine bearing and seal wear.
[0008] It is, therefore, desirable that a hydrodynamic thrust
bearing be constructed that has an improved thrust load capacity
when compared to conventional hydrodynamic thrust bearings. It is
also desired that such thrust bearing be capable increasing the
thrust load capacity without adversely impacting other performance
areas of the thrust bearing itself and the bearing assembly. It is
further desired that such thrust bearing be capable of fitment with
existing turbocharger devices without extensive redesigning.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] The details and features of the present invention will be
more clearly understood with respect to the detailed description
and the following drawings, wherein:
[0010] FIG. 1a illustrates a schematic front end view of
hydrodynamic thrust bearing constructed according to principles of
this invention;
[0011] FIG. 1b illustrates a schematic front end view of a second
embodiment of the hydrodynamic thrust bearing constructed according
to principles of this invention; and
[0012] FIG. 2 illustrates a cross-sectional side view across
section 2-2 of the hydrodynamic thrust bearing of FIG. 1.
SUMMARY OF THE INVENTION
[0013] Hydrodynamic thrust bearings, constructed according to
principles of this invention, comprise an axially-directed annular
surface that is specially designed to promote oil migration
thereacross in a manner that minimizes oil film temperature, thus
maximizing thrust load capacity. Specifically, hydrodynamic thrust
bearings of this invention comprise a series arrangement of three
differently configured land sections across the bearing axial
surface that are separated by an oil supply groove (on one side)
and an oil return or collection grove (on an opposite side).
Configured in this manner, oil is provided onto the series of land
sections by the oil supply groove and is collected after passing
over the series of land sections by the separate oil collection
groove. The use of separate oil supply and collection grooves acts
to minimize oil mixing, i.e., input oil mixing with the heated
return oil, thereby reducing oil film temperature and increasing
bearing thrust load capacity.
DETAILED DESCRIPTION OF THE INVENTION
[0014] Referring to FIG. 1 a, a hydrodynamic thrust bearing 10 of
this invention has an annular body 12 comprising an inside diameter
14 and an outside diameter 16. The inside diameter is sized to
accommodate placement of a turbine shaft (not shown), or
alternatively a shaft bearing member (not shown), therein. The
bearing includes an axially-directed face 18 that is designed to be
positioned adjacent a turbocharger bearing housing member surface
(not shown) to control the extent of axial thrust bearing
displacement within the housing.
[0015] The axially-directed face 18 comprises a repeating serial
arrangement of three land sections 20, wherein each serial
arrangement defines a thrust bearing thrust pad. An oil supply
channel 22 is disposed along the bearing inside diameter along the
axially-directed face 18, and an oil return or collection channel
24 is disposed along the bearing outside diameter along the axially
directed face 18. The series arrangements of the three land
sections 20 extend radially across the axially-directed face 18
between the oil supply and collection channels.
[0016] Each series arrangement of lands/thrust pad 20 comprises,
moving clockwise across FIG. 1a, a lower land 26, a ramp 28, and an
upper land 30. The lower land 26 is an arc section of the thrust
bearing face 18 that extends circumferentially across the face
between an oil supply groove 32 and the ramp 28. The oil supply
groove 32 is disposed a determined depth within the face 18 and
extends radially from the oil supply channel 22 thereacross. In one
bearing embodiment, the oil supply groove 32 extends radially
across the face only a partial distance and not to the oil
collection channel 24 (the embodiment shown in FIG. 1a). In another
embodiment, the oil supply groove 32 extends radially across the
face a complete distance to the oil collection channel 24 (the
embodiment shown in FIG. 1b). The oil supply groove 32 is designed
to direct supply oil from the oil supply channel 22 to the lower
land 26 for distribution across the thrust pad for forming a
thrust-load bearing oil film layer thereon.
[0017] The ramp 28 comprises an arc section of the face that
extends circumferentially across the face between the lower and 26
and the upper land 30. As best shown in FIG. 2, the ramp 28 is
configured having an upwardly directed slope moving from the lower
land to the upper land. Accordingly, oil that is passed to the ramp
from the lower land is compressed against an adjacent planar
surface of the housing before being passed to the upper land. This
oil compression is caused by the rotary action of the thrust
bearing within the housing, and is necessary for forming a desired
hydrodynamic effect between the bearing and the housing
surface.
[0018] The upper land 30, as the name implies, comprises an arc
section of the bearing face 18 that is positioned axially above
both the lower lamp 26 and the ramp 28. The upper land 30 extends
circumferentially across the face from the ramp 28 to an oil return
or collection groove 34. The oil return groove 34 is disposed a
depth within the face and extends radially inwardly a partial
distance thereacross from the oil return channel 24. The oil return
groove 24 terminates before reaching the oil supply channel 22 to
prevent the fresh supply oil from entering and mixing with the
heated return oil collected from the thrust pads. Oil entering the
oil return groove 24 is directed radially therealong to the oil
return channel 24 where it is collected and removed from the
bearing.
[0019] Thus, configured in this manner, supply oil is provided from
the oil supply channel 22 to each thrust pad 20 by a single oil
groove 32 adjacent each thrust pad lower land 26. As the thrust
bearing is rotated, the supply oil is whisked radially and
circumferentially across each thrust pad, forming a thin
hydrodynamic film layer between the bearing face and an adjacent
housing surface. Heated oil is removed from each thrust pad and
collected within the oil collection channel 24 via the oil return
groove 34 positioned adjacent each thrust pad upper land 34. As the
bearing is rotated, oil is continuously provided to the thrust
pads, used to create a desired hydrodynamic oil film layer thereon,
and is removed from the thrust pads in this manner.
[0020] To prevent the unwanted migration of oil between each oil
supply groove and an adjacent oil return groove, a separator 36 is
disposed therebetween. The separator 36 extends radially along the
bearing face 18 from the oil supply channel 22 to the oil return or
collection channel 24 and, as best shown in FIG. 2, the separator
is in the form of a rib that extends above each of the bordering
grooves to act as a barrier to prevent oil from moving
therebetween.
[0021] The use of separate oil supply and return grooves is an
important feature of this invention as it prevents the relatively
cooler supply oil from mixing together with the hot return oil
during turbocharger operation, i.e., thrust bearing rotation,
thereby both reducing the oil film temperature across the bearing
face, and improving the thrust load carrying capacity of the
bearing.
[0022] Having now described the invention in detail as required by
the patent statutes, those skilled in the art will recognize
modifications and substitutions to the specific embodiments
disclosed herein. Such modifications are within the scope and
intent of the present invention described generally as:
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