U.S. patent application number 13/492972 was filed with the patent office on 2012-12-20 for turbocharger, notably for a combustion engine.
This patent application is currently assigned to AKTIEBOLAGET SKF. Invention is credited to Nicolas Berruet, Richard Corbett, Samuel VIAULT, Jeroen Wensing.
Application Number | 20120321491 13/492972 |
Document ID | / |
Family ID | 44343960 |
Filed Date | 2012-12-20 |
United States Patent
Application |
20120321491 |
Kind Code |
A1 |
VIAULT; Samuel ; et
al. |
December 20, 2012 |
TURBOCHARGER, NOTABLY FOR A COMBUSTION ENGINE
Abstract
The turbocharger comprises a shaft 14, a housing 12, a turbine
wheel 20 and a compressor wheel 22 mounted onto the shaft, and at
least a rolling bearing 18 disposed between the shaft and the
housing and comprising an inner ring 26, an outer ring 28 and at
least one row of rolling elements 30 disposed into a rolling space
40 defined between the rings. A damping space 38 is defined between
an outer surface 28a of the outer ring and a bore 16 of the housing
inside which a lubricant is located.
Inventors: |
VIAULT; Samuel; (SAINT
ANTOINE DU ROCHER, FR) ; Wensing; Jeroen; (Houten,
NL) ; Berruet; Nicolas; (Artannes sur indre, FR)
; Corbett; Richard; (FONDETTES, FR) |
Assignee: |
AKTIEBOLAGET SKF
Goteborg
SE
|
Family ID: |
44343960 |
Appl. No.: |
13/492972 |
Filed: |
June 11, 2012 |
Current U.S.
Class: |
417/406 |
Current CPC
Class: |
F16C 19/184 20130101;
F16F 15/0237 20130101; F01D 25/164 20130101; F01D 25/183 20130101;
F05D 2220/40 20130101; F16C 27/045 20130101; F02C 6/12 20130101;
F16C 2360/24 20130101 |
Class at
Publication: |
417/406 |
International
Class: |
F01D 25/18 20060101
F01D025/18; F01D 1/06 20060101 F01D001/06 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 17, 2011 |
EP |
11305761.6 |
Claims
1. A turbocharger comprising; a shaft (14), a housing (12), a
turbine wheel (20) and a compressor wheel (22) mounted onto the
shaft, and at least a rolling bearing (18) disposed between the
shaft and the housing and comprising; an inner ring (26), an outer
ring (28) and at least one row of rolling elements (30) disposed
into a rolling space (40) defined between the rings, and wherein a
damping space (38) is defined between an outer surface (28a) of the
outer ring and a bore (16) of the housing inside which a lubricant
is located.
2. The turbocharger according to claim 1, further comprising at
least two sealing means (42, 44; 50, 52) closing at least the
rolling space (40).
3. The turbocharger according to claim 2, wherein the sealing means
(42, 44) close the damping and the rolling spaces.
4. The turbocharger according to claim 2, wherein the sealing means
(42, 44) are disposed radially between the shaft (14) and the
housing (12).
5. The turbocharger according to claim 2, wherein the sealing means
(50, 52) are disposed radially between the inner and outer
rings.
6. The turbocharger according to claim 5, wherein the sealing means
(50, 52) only close the rolling space (40).
7. The turbocharger according to claim 6, wherein the rolling space
(40) is filled with a lubricant distinct from the lubricant located
in the damping space (38).
8. The turbocharger according to claim 1, further comprising
passage means for the lubricant putting the damping space (38) and
the rolling space (40) into communication.
9. The turbocharger according to claim 8, wherein the passage means
comprise a gap (39) between the outer ring and the housing.
10. The turbocharger according to claim 8, wherein the passage
means comprise holes made in the thickness of the outer ring.
11. The turbocharger according to claim 1, wherein the lubricant
located inside the damping space (38) is grease.
12. The turbocharger according to claim 1, wherein the axial length
of the rolling bearing (18) ranges between 30% and 95% of the axial
dimension of the housing (12), and preferably ranges between 70%
and 80%.
Description
CROSS-REFERENCE
[0001] This application claims priority to European Patent
Application No. EP11305761.6 filed on Jun. 17, 2011.
FIELD OF THE INVENTION
[0002] The present invention relates to the field of turbochargers,
and in particular those used in combustion engines for automotive
vehicles.
BACKGROUND OF THE INVENTION
[0003] In such application, a turbocharger is used to enhance the
combustion engine performance by blowing compressed air into the
cylinders of said engine.
[0004] A turbocharger generally comprises a housing, a shaft
extending through an opening formed on the housing, a turbine wheel
mounted on a first end portion of the shaft and located in an
exhaust gases passage of the combustion engine, a compressor wheel
mounted on an opposite second end portion of said shaft and located
in an admission gases passage of the engine, and rolling bearings
disposed between the shaft and the housing. When the turbine wheel
is rotated by the flow of the exhaust gases, the shaft and the
compressor wheel are rotated which leads to a compression of the
admission gases introduced into the cylinders of the combustion
engine.
[0005] The engine oil may be used for the lubrication of the
rolling bearings. However, when the combustion engine stops, the
delivery of engine oil is shut off. This causes a strong
temperature increase of the residual oil located between the shaft
and the rolling bearing near to the turbine wheel. The cooling of
said rolling bearing is thus not satisfactory. Otherwise, the
engine oil may contain foreign matter, for example small metal
particles, thereby causing a premature wear of the rolling
bearings.
[0006] To overcome these drawbacks, European patent application
EP-A2-2 042 758 discloses a turbocharger comprising a tank for
storing a specific lubricating oil for the rolling bearings, said
tank being formed within the housing. A tube is provided between
the storage tank and the space where are housed the rolling
bearings to supply by capillary action the lubricating oil. In the
disclosed turbocharger, an intermediate bearing casing is also
mounted between the rolling bearings and the housing, said casing
being equipped with damper rings to reduce the transmission of
vibrations emitted by the turbine and compression wheels.
[0007] This leads to a complex structure of the turbocharger as
well as an increase of the mounting cost.
[0008] One aim of the present invention is therefore to overcome
the aforementioned drawbacks.
SUMMARY OF THE INVENTION
[0009] It is a particular object of the present invention to
provide a turbocharger which is simple to manufacture and economic,
while guaranteeing good sealing and damping properties.
[0010] In one embodiment, the turbocharger comprises a shaft, a
housing, a turbine wheel and a compressor wheel mounted onto the
shaft, and at least a rolling bearing disposed between the shaft
and the housing and comprising an inner ring, an outer ring and at
least one row of rolling elements disposed into a rolling space
defined between the rings. A damping space is defined between an
outer surface of the outer ring and a bore of the housing inside
which a lubricant is located.
[0011] In one embodiment, the turbocharger further comprises at
least two sealing means closing at least the rolling space.
[0012] In one embodiment, the turbocharger further comprises at
least two sealing means closing the damping space and the rolling
space.
[0013] In one embodiment, the turbocharger further comprises
passage means for the lubricant putting the damping space and the
rolling space into communication.
[0014] In one embodiment, the sealing means are axially offset
outwards with respect to the passage means.
[0015] The passage means may comprise a gap between the outer ring
and the housing. Alternatively or in combination, the passage means
comprise holes made in the thickness of the outer ring. The
lubricant located inside the damping space may be grease.
[0016] In one embodiment, the sealing means are disposed radially
between the shaft and the housing.
[0017] In another embodiment, the sealing means are disposed
radially between the inner and outer rings. The sealing means may
only close the rolling space. The rolling space may be filled with
a lubricant distinct from the lubricant located in the damping
space.
[0018] In one embodiment, the axial length of the rolling bearing
ranges between 30% and 95% of the axial dimension of the housing,
and preferably ranges between 70% and 80%.
BRIEF DESCRIPTIONS OF THE DRAWINGS
[0019] The present invention and its advantages will be better
understood by studying the detailed description of specific
embodiments given by way of non-limiting examples and illustrated
by the appended drawings on which:
[0020] FIG. 1 is an axial section of a turbocharger according to a
first example of the invention, and
[0021] FIG. 2 is an axial section of a turbocharger according to a
second example of the invention.
DETAILED DESCRIPTION OF THE INVENTION
[0022] As illustrated on the FIG. 1, which illustrates an
embodiment of a turbocharger 10 according to an example of the
invention, the turbocharger comprises a housing 12, a shaft 14
extending along a longitudinal axis 14a through a cylindrical bore
or opening 16 of the housing, a rolling bearing 18 mounted onto the
shaft 14 and disposed into the bore 16, a turbine wheel 20 fixed at
one end of the shaft 14 and a compressor wheel 22 fixed at an
opposite end of said shaft. The housing 12 comprises a cap 24 fixed
at one axial end. In the disclosed embodiment, the axial length of
the rolling bearing 18 ranges between 60% and 90% of the axial
dimension of the bore 16 of the housing, and more precisely between
70% and 80%.
[0023] The rolling bearing 18 comprises an inner ring 26 and an
outer ring 28 between which are housed two rows of rolling elements
30 and 32, which in this case are balls, and two annular cages 34,
36 respectively maintaining the circumferential spacing of the
rolling elements 30, 32. The axis 18a of the rolling bearing is
coaxial with the axis 14a of the shaft of the turbocharger.
[0024] The inner and outer rings 26, 28 are concentric and
symmetric with respect to a transverse radial plane passing through
the centre of the rolling bearing. The rings 26, 28 are of the
solid type. A "solid ring" is to be understood as a ring obtained
by machining with removal of material (by machining, grinding) from
metal tube stock, bar stock, rough forgings and/or rolled
blanks.
[0025] The outer ring 28 comprises an outer cylindrical surface 28a
delimited by opposite radial lateral surfaces 28b and 28c, the
radial surface 28c axially come into contact with a radial shoulder
of the housing 12. The outer ring 28 also comprises a bore 28d of
cylindrical shape from which are formed toroidal raceways (not
referenced) having in cross-section a concave internal profile
adapted to the rolling elements 30, 32. The raceways are
symmetrical with respect to the transverse radial plane passing
through the centre of the rolling bearing.
[0026] An annular radial gap or space 38 exists between the outer
surface 28a of the outer ring and the bore 16 of the housing. The
annular space 38 is delimited radially by the outer ring 28 and the
bore 16 of the housing, and axially by the radial shoulder of said
housing and the cap 24. An annular axial space or gap 39 is defined
between the radial surface 28b of the outer ring and the cap
24.
[0027] In the disclosed embodiment, the inner ring 26 is made in
two parts which are identical, symmetrical with respect to the
transverse radial plane of symmetry of the rolling bearing and
mounted axially fixedly one against the other. The inner ring 26 is
here composed of two identical half-rings.
[0028] Alternatively, the inner ring may be made into one part. The
inner ring 26 has a bore 26a of cylindrical shape into which the
shaft 14 is mounted. Said bore is delimited by opposite radial
lateral surfaces 26b and 26c, which are respectively coplanar with
the lateral surfaces 28b, 28c of the outer ring. The radial surface
26c axially bears against a radial shoulder of the shaft 14. The
inner ring 26 also comprises an exterior cylindrical surface 26d
onto which first and second toroidal circular raceways (not
referenced) are formed. The said raceways have in cross-section a
concave internal profile adapted to the rolling elements 30 and 32,
the said raceways being directed radially outwards. The raceways
are symmetrical with respect to the transverse radial plane passing
through the centre of the rolling bearing.
[0029] An annular rolling space 40 is defined between the inner and
outer rings 26, 28 in which the rolling elements 30, 32 and the
associated cages 34, 36 are housed. The rolling space 40 is
delimited radially by the exterior surface 26d of the inner ring
and the bore 28d of the outer ring, and axially by the radial
surfaces 26b, 28b and 26c, 28c of said rings.
[0030] The turbocharger 10 is further provided with a sealing ring
42 mounted radially between the shaft 14 and the cap 24 and axially
disposed between the compressor wheel 22 and the rolling bearing
18, and with an annular sealing ring 44 disposed radially between
the shoulder of said shaft 14 and the bore 16 of housing and
axially mounted between the rolling bearing 18 and the turbine
wheel 20. The sealing ring 42 is located axially between the radial
surfaces 26b, 28b of the inner and outer rings and the compressor
wheel 22, the sealing ring 44 being located axially between the
radial surfaces 26c, 28c of said rings and the turbine wheel 20.
The sealing rings 42, 44 are identical to one another and apply a
static sealing with the shaft 14 and a dynamic sealing respectively
with the cap 24 and the housing 12. The sealing rings 42, 44 are
fitted into grooves (not referenced) provided on the exterior
surface of the shaft 14, extend radially and respectively come into
sliding contact with the cap 24 and the housing 12. Alternatively,
the sealing rings may remain at a small distance from said cap and
housing. The sealing rings 42, 44 are made from metal,
advantageously from a thin metal sheet blank. Alternatively, the
sealing rings may be made by moulding a synthetic material such as
an elastomer. The sealing rings 42, 44 are continuous in the
circumferential direction. To facilitate there fitting into the
grooves of the shaft 14, each of the sealing rings may
alternatively be open at a point of its circumference.
[0031] The sealing rings 42, 44 close from the outside the rolling
space 40 of the rolling bearing and the annular space 38 defined
between the outer ring 28 of said bearing and the bore 16 of the
housing. A single lubricant 46, such as grease, may be used to fill
the annular radial spaces 38, 40. The lubricant 46 disposed into
the radial space 38 may enable to damp the vibrations emitted by
the rotation of the turbine and compressor wheels 20, 22. The
transmission of the vibrations emitted by said wheels to the
housing 12 may be limited. The radial space 38 filled with
lubricant 46 acts as a damping space. The damping space 38
communicates with the rolling space 40 via the axial annular gap 39
defined between the outer ring 28 and the cap 24. Said gap 39 forms
passage means for the lubricant 46 communicating with the damping
space 38 and the rolling space 40. The sealing ring 42, 44 have a
dual function, namely to preventingress of undesirable external
polluting elements into the rolling bearing 18 and to keep the
lubricant 46 into the damping space 38 and the rolling space 40.
The lubricant 46 is introduced during the assembly of the
turbocharger.
[0032] In the disclosed embodiment, the axial gap 39 for the
lubricant enables to put the damping space 38 and the rolling space
40 into communication. Alternatively or in combination, it could
also be possible to made radial through-holes in the thickness of
the outer ring 28 to form passage means for the lubricant between
the damping space 38 and the rolling space 40.
[0033] The embodiment shown on FIG. 2, in which identical parts are
given identical references, differs from the previous embodiment in
that the radial surface 28b of the outer ring axially comes into
contact with the cap 24 of the housing, and in that the rolling
bearing 18 further comprises annular sealing rings 50, 52 disposed
radially between the inner and outer rings 26, 28. The sealing
rings 50, 52 are fitted inside annular grooves (not referenced)
formed radially towards the inside from the exterior surface 26d of
the inner ring, respectively in the vicinity of the radial surfaces
26b, 26c. The sealing rings 50, 52 are symmetrical with one another
relative to the transverse radial plane of symmetry of the rolling
bearing. Each sealing ring 50, 52 extends radially towards the
outer ring 28 and comes into sliding contact with the bore 28d of
said ring. Alternatively, the sealing rings may remain at a small
distance from said bore. The sealing rings 50, 52 are made from
metal or from a synthetic material.
[0034] The sealing ring 50 is axially situated on the compressor
wheel side and the sealing ring 52 on the turbine wheel side. The
sealing ring 50 is located axially between the row of rolling
elements 30 and the radial surfaces 26b, 28b of the inner and outer
rings, the sealing ring 52 being mounted axially between the row of
rolling elements 32 and the radial surfaces 26c, 28c of said rings.
In this embodiment, the rolling space 40 inside which are housed
the rolling elements 30, 32 and the cages 34, 36 is axially
delimited by the radial sealing rings 50, 52. The closed rolling
space 40 is filled which a lubricant 54, such as grease. The
lubricant 54 may be distinct from the lubricant 46 used into the
damping space 38. The sealing rings 50, 52 only close the rolling
space 40, the damping space 38 being closed by the outer ring 28,
the housing 12 and the cap 24. The damping space 38 and the rolling
space 40 are not in communication with one another.
[0035] In another embodiment, with such sealing rings 50, 52 and
the axial contact between the radial surface 28b of the outer ring
and the cap 24, it could also be possible to made radial
through-holes in the thickness of said outer ring axially between
the rows of rolling elements 30, 32 to obtain passage means for the
lubricant putting the damping space 38 and the rolling space 40
into communication. In this case, the sealing rings close the two
spaces 38, 40 and the lubricant 46, 54 is the same for both
spaces.
[0036] In another variant, the turbocharger 10 may be not provided
with sealing rings 42, 44, 50, 52 and the rolling bearing 18 is
directly lubricated by the engine oil.
[0037] It should be noted that the embodiments illustrated and
described were given merely by way of non-limiting indicative
examples and that modifications and variations are possible within
the scope of the invention. The invention applies not only to
turbocharger comprising an angular contact ball rolling bearing
with a double rows of balls but also to turbocharger comprising
other types of rolling bearing, for example rolling bearing having
four points contact and/or with a single row of balls or with at
least three rows of balls.
[0038] Furthermore, the invention applies to rolling bearings
comprising a plurality of inner rings and/or a plurality of outer
rings. Finally, it has to be made clear that by a turbocharger it
is also meant a waste heat recovery turbine, a turbo-compound or a
compressor.
* * * * *