U.S. patent application number 10/109430 was filed with the patent office on 2002-10-03 for oil control device.
Invention is credited to McEwen, James.
Application Number | 20020141862 10/109430 |
Document ID | / |
Family ID | 9911995 |
Filed Date | 2002-10-03 |
United States Patent
Application |
20020141862 |
Kind Code |
A1 |
McEwen, James |
October 3, 2002 |
Oil control device
Abstract
An oil control device for incorporation in a system for sealing
the passage of a rotating shaft (3) through an opening. The oil
control device comprises an annular member (10) for rotation with
said shaft (3) and provided with a circumferentially spaced array
of passages (24, 18) for centrifugally displacing fluid away from
said shaft (3) as it rotates. The passages (24, 18) comprise
channels which are open along their length.
Inventors: |
McEwen, James; (West
Yorkshire, GB) |
Correspondence
Address: |
Gary M. Gron
Law Offices - 60701
Cummins Inc.
P.O. Box 3005
Columbus
IN
47202-3005
US
|
Family ID: |
9911995 |
Appl. No.: |
10/109430 |
Filed: |
March 28, 2002 |
Current U.S.
Class: |
415/111 ;
415/175 |
Current CPC
Class: |
F04D 29/063 20130101;
F01D 25/18 20130101; F02C 6/12 20130101; F01D 25/186 20130101; F04D
25/04 20130101; F16C 2360/24 20130101; F05D 2220/40 20130101; F16C
17/26 20130101 |
Class at
Publication: |
415/111 ;
415/175 |
International
Class: |
F04D 029/06 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 30, 2001 |
GB |
0108119.9 |
Claims
Having thus described the invention, what is novel and desired to
be secured by Letters Patent of the United States is:
1. An oil control device for incorporation in a system for sealing
the passage of a rotating shaft through an opening, the oil control
device comprising an annular member for rotation with said shaft
and provided with a circumferentially spaced array of passages for
centrifugally displacing fluid away from said shaft as it rotates,
wherein said passages comprise channels which are open along their
length.
2. An oil control device according to claim 1, wherein said annular
member defines at least one generally radially extending face in
which a plurality of said channels are formed.
3. An oil control device according to claim 2, wherein the annular
member comprises a central cylindrical body portion and a
surrounding annular portion, and wherein said at least one face is
defined by said annular portion.
4. An oil control device according to claim 3, wherein said at
least one face is defined at an axial end of said annular
portion.
5. An oil control device according to claim 4, wherein said annular
portion defines first and second oppositely facing axial end faces
each of which is provided with an array of said channels.
6. An oil control device according to claim 5, wherein said annular
portion has an axially extending part which is radially spaced from
said body portion defining an annular gap therebetween.
7. An oil control device according to claim 6, wherein at least
some of said channels in the or each face communicate with said
annular gap.
8. An oil control device according to claim 1, wherein at least one
of said channels is substantially straight.
9. An oil control device according to claim 8, wherein said
substantially straight channel extends radially from the axis of
rotation of the shaft and oil control device.
10. An oil control device according to claim 8, wherein said
straight channel is angularly off-set relative to radial lines
extending from the axis of rotation of the oil control device, such
that said channel is swept relative to the direction of
rotation.
11. An oil control device according to claim 1, wherein at least
some of said channels are curvilinear.
12. An oil control device according to claim 11, wherein said
curvilinear channels have a constant radius of curvature.
13. An oil control device according to claim 11, wherein said
curvilinear channels have a radius of curvature which varies along
the length of said channels in a direction away from the centre of
axis of rotation.
14. An oil control device according to claim 13, wherein said
channels have a constant cross-sectional area.
15. An oil control device according to claim 13, wherein the
cross-sectional area of at least some of said channels varies along
the length of the respective channel in a direction away from the
axis rotation of the oil control device.
16. An oil control device according to claim 15, wherein the width
of said channels varies to give said varied cross-sectional
area.
17. An oil control device according to claim 15, wherein the depth
of said channels varies to give said varying cross-sectional
area.
18. A seal system according to claim 1 further comprising a
turbocharger comprising a compressor housing and a bearing housing
separated by a wall, a rotating shaft mounted on bearing systems
housed within said bearing housing, said shaft extending through
said wall into from the bearing housing into the compressor
housing, said oil control device being mounted to said shaft on the
bearing housing side of said wall to help prevent leakage of
lubricant from the bearing housing into the compressor housing.
19. A turbocharger according to claim 18, wherein said wall is a
compressor back plate, adapted for mating co-operation with the oil
control device.
20. A turbocharger according to claim 19, wherein said oil control
device has a first generally radially extending axial end face
which is in running engagement with said plate, at least some of
said channels being defined in said first end face.
Description
[0001] TECHNICAL FIELD
[0002] The present invention relates to an oil control device. The
invention provides an oil control device particularly suitable for
incorporation in a system for sealing the passage of a rotational
shaft through a wall separating adjacent chambers subject to
differential fluid pressures. Particularly, but not exclusively,
the invention relates to an oil control device for incorporation in
the thrust bearing sealing system of a compressor, such as a
turbocharger compressor.
BACKGROUND OF THE INVENTION
[0003] Turbochargers are well known devices for supplying air to
the intake of an internal combustion engine at pressures above
atmospheric (boost pressures). A conventional turbocharger
essentially comprises an exhaust gas driven turbine wheel mounted
on a rotatable shaft within a turbine housing. Rotation of the
turbine wheel rotates a compressor wheel mounted on the other end
of the shaft within a compressor housing. The compressor wheel
delivers compressed air to the intake manifold of the engine,
thereby increasing engine power.
[0004] The turbocharger shaft is conventionally supported by
journal and thrust bearings, including appropriate lubricating
systems, located within a central bearing housing connected between
the turbine and compressor wheel housings. It is well known that
providing an effective sealing system to prevent oil leakage from
the central bearing housing into the compressor or turbine housing
is problematical. This is particularly the case at the compressor
end of the turbocharger since at low boost pressures there can be a
significant drop in pressure from the bearing housing to the
compressor housing which encourages oil leakage into the compressor
housing.
[0005] In a conventional turbocharger design, the shaft passes from
the bearing housing to the compressor housing through an
appropriate passage in a compressor housing back plate, or oil seal
plate, with a thrust bearing assembly located adjacent the plate
within the bearing housing. It is oil supplied to the thrust
bearing assembly which can leak into the compressor housing. To
combat this, it is conventional to incorporate in such thrust
bearing assemblies a seal assembly including an oil control device
(often referred to within the turbocharger industry as an "oil
slinger"). An oil slinger is an annular component which rotates
with the shaft and comprises a number of radially extending
passages which effectively act as vanes for slinging oil away from
the shaft and in particular away from the passage from the bearing
housing into the compressor housing. An annular splash chamber
located around the thrust bearing and sealing assembly collects the
oil for re-circulation within the lubrication system. For instance
the splash chamber may be provided with drainage channels to drain
oil to a sump.
[0006] Many such thrust bearing sealing systems are known, for
instance an example of a typical system is disclosed in U.S. Pat.
No. 4,157,834. In this particular system the oil slinger component
is integral with a thrust collar component of the thrust bearing
assembly. In other arrangements the oil slinger may be a discrete
component suitably mounted for rotation with the shaft. The present
invention relates to the configuration of an oil slinger which may
be either a discrete component or an intregal part of another
component such as a part of a thrust bearing and/or sealing
assembly.
SUMMARY OF THE INVENTION
[0007] It is an object of the present invention to provide an oil
slinger which is simpler, and hence cheaper, to manufacture than
conventional designs. A further object is to provide an oil slinger
with improved pumping efficiency compared with conventional
designs.
[0008] According to a first aspect of the present invention there
is provided an oil slinger for incorporation in a system for
sealing the passage of a rotating shaft through an opening, the oil
slinger comprising an annular member for rotation with said shaft
and provided with a circumferentially spaced array of passages for
centrifugally displacing fluid away from said shaft as it rotates,
wherein said passages comprise channels which are open along their
length.
[0009] As is discussed further below, forming the oil slinging
passages as open channels provides a number of benefits over
conventional designs in which the oil slinging passages are radial
holes drilled into the oil slinger. Manufacture of the oil slinger
is simplified as a number of known techniques can be used, such as
sintering or injection moulding, which are more efficient than the
machining required to manufacture conventional oil slingers. In
addition to reducing the cost of manufacture, the manufacturing
ease enables the configuration of the passages to be varied so that
the pumping characteristic of the oil slinger can be "tuned". Open
channels are also subject to lower stresses than drilled holes and
accordingly durability of the oil slinger may be increased.
[0010] Preferably the annular member defines at least one generally
radially extending face in which a plurality of said channels are
formed.
[0011] In a preferred embodiment the annular member comprises a
central cylindrical body portion and a surrounding annular portion,
wherein said at least one face is defined by the annular portion,
for instance at an axial end thereof.
[0012] The annular portion preferably has an axially extending part
which is radially spaced from said body portion defining an annular
gap therebetween. In use the annular gap may receive a flange of an
oil seal plate or the like which defines said openings. In this
embodiment at least some of said channels in the or each face
communicate with said annular gap.
[0013] The channels may have a variety of configurations. For
instance one or more of said channels may be substantially
straight, and may be either radial or be swept backwards or
forwards relative to the direction of rotation of the oil
slinger.
[0014] Alternatively at least some of said channels may be
curvilinear with either a constant or varying radius of
curvature.
[0015] The channels may have a constant cross-sectional area or a
cross-sectional area which increases or decreases along the length
of the respective channel in a direction away from the axis
rotation of the oil slinger, depending on the desired pumping
characteristic. A varying cross-sectional area may for instance be
provided by varying the width and/or depth of respective
channels.
[0016] According to a second aspect of the present invention there
is provided a seal system for sealing the passage of a rotating
shaft through an opening in a wall the system comprising an oil
slinger in accordance with the first aspect of the present
invention mounted for rotation with said shaft.
[0017] For instance the invention provides a sealing system for
sealing passage of a rotatable shaft through an opening in a wall
from leakage of lubricant supplied to a thrust bearing assembly
associated with said shaft, the system comprising an oil slinger
according to the first aspect of the present invention mounted for
rotation with said shaft between said wall and said thrust bearing
assembly.
[0018] Although oil slingers in accordance with the present
invention may have many varied applications they are particularly
suitable for incorporation in the sealing systems of turbochargers.
Accordingly, a third aspect of the present invention provides a
turbocharger comprising a compressor housing and a bearing housing
separated by a wall, a rotating shaft mounted on bearing systems
housed within said bearing housing, said shaft extending through
said wall from the bearing housing into the compressor housing, and
an oil slinger according to the first aspect of the invention
mounted to said shaft on the bearing housing side of said wall to
help prevent leakage of lubricant from the bearing housing into the
compressor housing.
[0019] The wall may be a compressor back plate, or separate oil
seal plate, adapted for mating co-operation with the oil slinger.
Preferably the oil slinger has a first generally radially extending
axial end face which is in running engagement with said plate (at
least some of said channels preferably being defined in said first
end face), and/or a second generally radially extending axial end
face which faces said thrust bearing assembly (at least some of
said channels preferably being formed in said second end face).
SUMMARY OF THE DRAWINGS
[0020] An embodiment of the present invention will now be
described, by way of example only, with reference to the
accompanying drawings, in which:
[0021] FIG. 1 is an axial cross-section through a turbocharger
bearing housing incorporating the present invention;
[0022] FIG. 2 is an enlargement of the compressor end of the
bearing housing of FIG. 1, showing detail of the location of an oil
slinger in accordance with the present invention;
[0023] FIGS. 3 and 4 are perspective views showing opposite sides
of the oil slinger in isolation;
[0024] FIG. 5 is a perspective view showing the oil slinger of
FIGS. 3 and 4 together with an oil seal plate shown in FIGS. 1 and
2; and
[0025] FIG. 6 is a radial cross-section of the oil slinger/oil seal
plate combination of FIG. 5.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0026] Referring to the drawings, FIG. 1 is an axial cross-section
through parts of a turbocharger incorporating the present
invention. The illustrated turbocharger comprises a compressor
wheel 1 and turbine wheel 2 mounted to opposite ends of a common
shaft 3 which extends through a central bearing housing 4. Much of
the detail of the bearing housing and the bearing arrangements is
not important to enable the understanding or implementation of the
present invention and so will not be described in depth. Such
details may be entirely conventional.
[0027] In general, the bearing housing 4 has a central portion
which houses journal bearing assemblies 5 and 6 located towards the
compressor and turbine ends of the bearing housing respectively.
The compressor end of the bearing housing itself houses a thrust
bearing assembly 7 and terminates in a radially extending diffuser
section 8 which forms the diffuser portion of the compressor (a
compressor cover (not shown) being bolted to the diffuser section
around the compressor wheel 1). The chamber in which the compressor
wheel rotates (referred to hereinafter as the compressor housing)
is separated from the bearing housing by an oil seal plate 9 which
sits within the diffuser section 8 of the bearing housing 4. The
oil seal plate 9 is part of an oil seal system which further
incorporates an oil slinger 10 in accordance with the present
invention. Further details of these components will now be
described with particular reference to FIGS. 2 to 6.
[0028] The oil seal system comprising the oil seal plate 9 and oil
slinger 10 separates the compressor housing from the bearing
housing and sits between the compressor wheel 1 and the thrust
bearing assembly 7. The oil seal system is provided to prevent oil
which must be supplied to the thrust bearing assembly 7 from
leaking into the compressor housing, particular at low compressor
speeds at which there will be a pressure drop from the bearing
housing to the compressor housing.
[0029] The oil seal plate is fixed in position within the housing
whereas the oil slinger 10 is mounted for rotation with the shaft
3, and thus rotates relative to the oil seal plate 9. The oil
slinger 10 and oil seal plate 9 mate together in a generally
conventional configuration to provide a labyrinthine passage from
the bearing housing to the compressor housing to protect against
oil leakage. Details of the oil seal plate 9 and oil slinger 10,
and the co-operation between the two, will now be described with
additional reference to FIGS. 3 to 6. FIGS. 3 and 4 are perspective
views of the oil slinger 10 (not to scale with FIG. 1 or FIG. 2)
looking in opposite axial directions. FIGS. 5 and 6 show the oil
slinger 10 and oil seal plate 9 mated together, FIG. 6 being a
radial cross-section of the view shown in FIG. 5.
[0030] From the drawings it will be seen that the oil seal plate
comprises an annular disc 11 having a central aperture 12 defined
by an axially extending annular flange 13 which extends into the
bearing housing 4. The flange 13 surrounds the shaft 3 but with an
annular gap therebetween.
[0031] The oil seal plate 9 has a second annular flange 14
extending axially into the bearing housing 4 from adjacent its
outer periphery. The second flange 14 has both a greater axial and
radial dimension than the first flange 13 and bears against the
thrust bearing assembly 7. An annular shoulder 15 is defined
between the flange 14 and outer periphery of the disc 11 and
provides an annular seat for an O-ring 16 which provides a seal
between the radially outer extent of the oil seal plate 9 and the
bearing housing 4. A third annular flange 17 extends radially from
the compressor side of the oil seal plate 9 approximately midway
between the central aperture 12 and the outer periphery of the disc
11.
[0032] Turning now to the oil slinger 10 in accordance with an
embodiment of the present invention, this comprises a central
cylindrical body 18 and a radially stepped annular portion which
essentially comprises a radially extending flange portion 19 and a
radially enlarged axially extending portion 20. The enlarged
portion 20 surrounds part of the body 18 adjacent the flange
portion 19 thereby defining an annular slot 21 which receives the
annular flange 12 of the oil seal plate 9 such that the body 18 of
the oil slinger 10 extends into the central aperture 12 of the oil
seal plate 9. The radial surface 22 of the enlarged portion 20 of
the oil slinger 10 is radially stepped providing an axially raised
portion which lies in running engagement with the surface of the
disc 11 of the oil seal plate 9 around the flange 12. An annular
groove 22 is provided in the external surface of the body 18 of the
oil slinger 10 within which sits an sealing ring 23 which provides
a seal between the oil slinger 10 and the flange 12 of the oil seal
plate 9.
[0033] The oil slinging function is provided by two axially spaced
circumferential arrays of oil slinging passages defined by open
channels formed in opposing end faces of the annular portion of the
oil slinger 10. A first set of oil slinging channels 24 is provided
in the axial end face 22 of the enlarged portion 20 of the annular
portion of the oil slinger 10, extending between respective
openings in the radially inner and outer surfaces of the enlarged
portion 20. In the illustrated embodiment there are ten channels 24
circumferentially spaced around the enlarged portion 20. The
channels 24 do not extend exactly radially, but in this case are
swept forward at a slight angle.
[0034] The second set of oil slinging passages comprises channels
25 formed in the flange portion 19 of the oil slinger 10, each
extending between a respective opening in the outer surface of the
flange portion 19 and an opening into the annular slot 21. Again in
this embodiment there are ten channels 25 which are swept forward
at a slight angle.
[0035] In operation the oil slinger 10 seals the passage of the
shaft 3 from the bearing housing 4 into the compressor housing. The
central cylindrical body 18 of the oil slinger extends between the
compressor wheel 1 and a thrust collar 7a which is a part of the
thrust bearing assembly 7. As mentioned above, the raised portion
of the face 22 of the enlarged portion of the oil slinger 10 is in
running engagement with the oil seal plate 9. The channels 24 thus
sweep across the surface of the disc 11 of the oil seal plate 9.
Similarly, the channels 25 formed in the opposing face of the
annular portion 19 of the oil slinger 10 sweep across a surface of
the thrust bearing 7. Rotation of the oil slinger channels 24, 25
creates a positive pressure difference across the oil seal plate so
that any oil which might tend to leak between the oil seal plate 9
and oil slinger 10 is centrifugal accelerated by the rotation of
the oil slinger channels 24, 25 and thrown into a splash chamber
defined within the bearing housing (between the inner annular
surface of the oil seal plate flange 14 and the outer surface of
the oil slinger 10). The displaced oil then drains away for
re-circulation in a conventional manner.
[0036] The basic operation of the oil slinger 10 of the present
invention is essentially the same as that of prior art oil
slingers. The fundamental difference between the present invention
and the prior art, however, is that the oil slinging passages are
formed by open channels as opposed to the radial holes provided in
conventional oil slingers. By adopting an open channel
configuration manufacture of the oil slinger is greatly simplified.
In particular, it is possible to vary the exact configuration of
the channels without difficulty whereas with conventional oil
slingers in which the oil slinging passages are formed by holes
drilled into the oil slinger it would be extremely difficult to
deviate from a simple arrangement of exactly radially extending
passages (as are found in the prior art). In contrast, with the
present invention a number of features of the characteristics of
the channels can be readily altered to "tune" the pumping
characteristics of the oil slinger. For instance the channels can
be angled relative to radial lines extending from the centre of the
oil slinger as shown in the embodiment described above. The
channels can thus be swept either forwards or backwards relative to
the intended direction of rotation of the oil slinger. Similarly,
curved channels could be employed rather than simple straight
channels as illustrated.
[0037] In the illustrated embodiment the channels have parallel
sides. As a further modification the sides could taper or the depth
of each channel could increase or decrease along its length. It
will also be appreciated that two or more of the aforementioned
features could be combined and that neighbouring channels could
have different configurations.
[0038] There are a number of existing manufacturing techniques that
could be readily employed in the production of oil slingers in
accordance with the present invention including sintering and
injection moulding techniques. Such techniques are relatively low
cost compared to the machining required to produce conventional oil
slinger designs. Oil slingers in accordance with the present
invention can therefore be manufactured more cheaply and
efficiently than existing oil slinger designs.
[0039] A further advantage is that the open oil slinger channels
are not subject to the same degree of stressing as the simple
drilled holes of conventional oil slingers and can therefore be
made more durable than conventional oil slingers.
[0040] It will be appreciated that a number of modifications can be
made to the specific example described, in addition to the possible
features mentioned above. For instance, channels may be provided in
one rather than both of the opposing faces of the annular portion
of the oil slinger, and the number of channels in the or each array
may vary from the number illustrated. The oil slinger illustrated
is a discrete component but could be integral with other parts of
the oil seal or thrust bearing assembly. For instance, the oil
slinger could be integral with the thrust bearing collar 7a. In
addition, the detailed configuration of the oil slinger 10 may
vary, for instance to match varying configurations of oil seal
plate 9. Furthermore, in different turbocharger arrangements the
oil slinger 10 may co-operate with a backplate of the compressor
housing rather than with a separate oil seal plate as in the
illustrated embodiment.
[0041] Other possible modifications will be readily apparent to the
appropriately skilled person.
* * * * *