U.S. patent application number 12/745308 was filed with the patent office on 2011-01-20 for heat shield and turbocharger having a heat shield.
This patent application is currently assigned to CONTINENTAL AUTOMOTIVE GMBH. Invention is credited to Ralf Boening, Holger Faeth, Christian Uhlig, Robert Vetter.
Application Number | 20110014036 12/745308 |
Document ID | / |
Family ID | 40427875 |
Filed Date | 2011-01-20 |
United States Patent
Application |
20110014036 |
Kind Code |
A1 |
Boening; Ralf ; et
al. |
January 20, 2011 |
HEAT SHIELD AND TURBOCHARGER HAVING A HEAT SHIELD
Abstract
A heat shield, in particular for a turbocharger, has a disk or a
pot shape which is stepped once or multiple times. The disc or pot
shape has an outer edge, and the outer edge is provided with at
least one opening section. The opening section forms a web section
with the outer edge, said web section being bent outward in order
to form a spring arm. The web section is either designed as closed
or as open at one point.
Inventors: |
Boening; Ralf; (Reiffelbach,
DE) ; Faeth; Holger; (Fussgoenheim, DE) ;
Uhlig; Christian; (Worms, DE) ; Vetter; Robert;
(Worms, DE) |
Correspondence
Address: |
LERNER GREENBERG STEMER LLP
P O BOX 2480
HOLLYWOOD
FL
33022-2480
US
|
Assignee: |
CONTINENTAL AUTOMOTIVE GMBH
Hannover
DE
|
Family ID: |
40427875 |
Appl. No.: |
12/745308 |
Filed: |
November 18, 2008 |
PCT Filed: |
November 18, 2008 |
PCT NO: |
PCT/EP08/65760 |
371 Date: |
October 5, 2010 |
Current U.S.
Class: |
415/177 |
Current CPC
Class: |
F05D 2220/40 20130101;
F16F 1/324 20130101; F02C 6/12 20130101; F16F 1/328 20130101; F02C
7/24 20130101 |
Class at
Publication: |
415/177 |
International
Class: |
F04D 29/58 20060101
F04D029/58 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 28, 2007 |
DE |
10 2007 057 309.1 |
Claims
1-17. (canceled)
18. A heat shield, comprising: a disc or pot shape formed with one
or more steps; said disc or pot shape having an outer rim formed
with at least one slotted section; a web section formed between
said slotted section and said outer rim, said web section being
bent outwards in order to form a spring arm and said web section
being either closed or open at one point.
19. The heat shield according to claim 18, wherein said web section
has a shape selected from the group consisting of elongated,
circular, and oval shapes.
20. The heat shield according to claim 18, wherein said web section
has a uniform thickness or at least one or more segments having a
different thickness.
21. The heat shield according to claim 18, wherein said web section
is one, two, three, four, or more web sections arranged in a track
on said outer rim.
22. The heat shield according to claim 18, wherein said disc or pot
shape has at least one or more additional tracks, said tracks each
having one, two, three, four, or more web sections.
23. The heat shield according to claim 22, wherein said tracks each
has a common number or a different number of web sections.
24. The heat shield according to claim 18, wherein said web
sections of one track or of a plurality of tracks are substantially
identical in terms of shape, size, and/or arrangement.
25. The heat shield according to claim 18, wherein said web
sections of one track or of a plurality of tracks are substantially
different in terms of shape, size, and/or arrangement.
26. The heat shield according to claim 18, wherein at least one or
more web sections are open at one end, and the respective said
segment of said web section is bent outwards.
27. The heat shield according to claim 18, wherein at least one or
more web sections are open at a center thereof, and the respective
said segment of said web section is bent outwards.
28. The heat shield according to claim 18, wherein said web
sections of at least two or more tracks are arranged mutually
offset or partly offset from one another.
29. The heat shield according to claim 18, wherein said web
sections of at least two or more tracks are substantially in line
with one another.
30. The heat shield according to claim 18, wherein the respective
said web section or a segment of said web section is bent outwards
by a predetermined amount, setting a predetermined spring
displacement of said spring arm.
31. The heat shield according to claim 30, wherein said web
sections or said segments of said web sections are bent outwards by
a common amount.
32. The heat shield according to claim 30, wherein said web
sections or said segments of said web sections are bent outwards by
mutually different amounts.
33. The heat shield according to claim 18, wherein said outer rim
of said disc is curved outwardly with a uniform curvature.
34. The heat shield according to claim 18, wherein said outer rim
of said disc is curved outwardly with a stepped contour having one,
two, or more steps.
35. The heat shield according to claim 18, formed of a
heat-resistant or high temperature-resistant material configured
according to an intended use thereof.
36. The heat shield according to claim 18, formed of a
heat-resistant or high temperature-resistant metal or metal
alloy.
37. The heat shield according to claim 18, formed of a turned part,
or of a bent metal part, or of a bent sheet metal part.
38. The heat shield according to claim 18, wherein said web section
or said segment of said web section is bent outwards substantially
tangentially.
39. The heat shield according to claim 18, formed with a
through-hole for fixing or centering the heat shield on a
turbocharger.
40. A turbocharger, comprising a heat shield according to claim
18.
41. The turbocharger according to claim 40, which further comprises
a bearing housing, a turbine housing, and a compressor housing, and
wherein said heat shield is disposed between said bearing housing
and said turbine housing and/or between said bearing housing and
said compressor housing.
Description
[0001] The invention relates to a heat shield, in particular in a
turbocharger, and a turbocharger having such a heat shield, to
protect a bearing system of the turbocharger from heat penetrating
by means of a warm or hot medium such as hot exhaust gas.
[0002] Turbochargers normally have a housing, in which a turbine
wheel and a compressor wheel are mounted by radial bearings on a
shaft so that they can rotate on the shaft. The shaft can reach
rotational speeds of up to 300,000 rpm for example. In order to be
able to absorb axial forces that arise, at least one axial bearing
can also be provided, for example. The bearings are here lubricated
by a suitable lubricating oil.
[0003] The high exhaust-gas temperatures in the turbocharger mean
that a large amount of heat penetrates the bearing system. This
results in coking of the lubricating oil for lubricating the
bearings, and in the worst case in total failure of the bearing
system. A shield between the turbine and the bearing system reduces
the heat penetration and avoids coking of the lubricating oil.
[0004] It is already known from the prior art to provide a heat
shield that is fitted either in series or in a parallel arrangement
between the bearing housing and the turbine housing. When the heat
shield is arranged in series, the thickness tolerance affects the
axial contour gap between turbine wheel and turbine housing, which
has a negative impact on the turbine efficiency. In a parallel
arrangement, the heat shield must be designed as a spring, which
enables adjustment for component tolerances and the thermal
expansion of components. The spring is formed either by three or
more spring arms arranged radially outwards or by a circumferential
collar. As described in even greater detail below with reference to
FIGS. 3 and 5 by way of example, such a spring has the
disadvantage, however, that the spring arms can easily break off
and the circumferential collar has a high spring force for a small
spring deflection.
[0005] Hence it is the object of the present invention to provide
an improved heat shield or, more precisely, a turbocharger having
an improved heat shield, with which the heat penetrating a bearing
system of the turbocharger can be reduced.
[0006] This object is achieved by a heat shield having the features
of claim 1.
[0007] As claimed in claim 1, according to the invention a heat
shield is provided, in particular for a turbocharger, said heat
shield being designed in the form of a disc or a pot shape
containing one or more steps, [0008] said disc or said pot shape
having an outer rim, said outer rim being provided with at least
one slotted section, [0009] said slotted section forming a web
section with the outer rim, said web section being bent outwards
(preferably in an axial direction i.e. towards the turbine housing
or towards the bearing housing) in order to form a spring arm, said
web section being designed either to be closed or to be open at one
point.
[0010] The flange on the outer rim can also be discontinuous in the
circumferential direction.
[0011] The heat shield here has the advantage that as a result of
the web section, which is bent outwards as a spring arm, a longer
spring arm can be implemented than is the case in the known heat
shields, whose spring arms are relatively short. The longer spring
arms in turn enable a flat shape for the force-deflection curve,
i.e. the spring force remains constant over the working range of
the spring. Thanks to the flat curve, the axial spring displacement
can be chosen to be relatively large, thereby enabling adjustment
for tolerances and for thermal expansion without a reduction in the
spring force. It can thereby be guaranteed that the heat shield
with its spring arm or spring arms does not become loose.
[0012] Advantageous embodiments and developments of the invention
follow from the subclaims and the description with reference to the
drawings.
[0013] According to one embodiment of the invention, the web
section has, for example, an elongated, circular and/or oval shape.
In principle, the web section can have any shape. The crucial
factor is that the web section can be bent sufficiently outwards in
order to form a spring arm having a suitable spring force and a
suitable spring deflection. The longer the slot section is chosen
to be, for example, the longer the web section also accordingly
becomes, and the further the web section can be bent outwards. The
shape and length of the web section is chosen here, for example, so
that the web section can be bent outwards sufficiently while
enabling a sufficient spring force to be achieved.
[0014] In a further embodiment according to the invention, the web
section has a uniform thickness or at least one or more segments
having a different thickness. In other words, the thickness of the
web section can be designed to remain constant or can vary.
[0015] In another embodiment according to the invention, the heat
shield can have one or a multiplicity of web sections, said web
sections being all arranged in a track on the outer rim. The web
sections can also be radially offset within a track. In this
context, it is possible to provide not just one track having at
least one or a multiplicity of web sections, but at least two or a
multiplicity of tracks. The web sections of a track can also have
an identical or different design. The same also applies to the web
sections where there are a plurality of tracks; for instance the
web sections of two or more tracks can have an identical or
different design depending on the function and application. The web
sections of the tracks can be arranged here with a mutual offset,
for example, or be arranged substantially in line. In this way it
is possible to implement a multiplicity of heat shields having
spring arms, which can be adapted, for example, to suit the
physical circumstances or different applications and functions.
[0016] In a further embodiment according to the invention, one or
more web sections can be designed to be open at one end or, for
example, in the center or in another position of the web. The
respective segment of the web section is bent outwards accordingly
in this case. The respective web section or a segment of the web
section is here bent outwards by a predetermined amount, for
example, in order to set a predetermined spring displacement of the
spring arm. Owing to the fact that the web section can here be bent
outwards tangentially, a greater spring deflection can be achieved
than in the known heat shields having their spring arms that can be
bent only at a slight angle.
[0017] In a further embodiment, the web sections or the segments of
the web sections for one track or a plurality of tracks can be bent
outwards, for example, by the same amount or by different amounts
depending on the function and application or physical
circumstances.
[0018] According to a further embodiment according to the
invention, the disc-shaped heat shield within the outer rim is
designed to curve outwards. Here the curvature can be designed to
be continuous or stepped, for example in the form of one, two or
more steps. This curvature can be provided, for example, in order
for the heat shield to fit suitably between the bearing housing and
the impeller housing of a turbocharger. In principle, however, it
is also possible for the heat shield to have a substantially flat
design, apart from the spring arms that are bent outwards. In
principle, the heat shield can have any shape depending on the
function, application or physical circumstances.
[0019] In another embodiment according to the invention, the heat
shield is made of a heat-resistant or high-temperature resistant
material depending on its place of use. In other words, the
heat-shield material is also selected according to what
temperatures the heat shield is exposed to. This means that it can
be sufficient, for example, where temperatures are not so high, to
use a heat-resistant material, whereas at high temperatures a
high-temperature resistant material is practical. Such a
heat-resistant or high-temperature resistant material may be, for
example, a suitable metal or a suitable metal alloy or another
suitable material or material combination provided that these are
suitable for forming spring arms.
[0020] According to a further embodiment according to the
invention, the heat shield can be made, for example, as a turned
part or a bent (sheet-)metal part. The invention is not restricted
to these methods, however.
[0021] The invention is described in greater detail below with
reference to the exemplary embodiments shown in the schematic
diagrams of the drawings, in which:
[0022] FIG. 1 shows a section of a "sandwich" heat shield according
to the prior art in its installed state;
[0023] FIG. 2a-c shows three perspective views of the "sandwich"
heat shield according to FIG. 1;
[0024] FIG. 3 shows a section of a "spring-arm" heat shield
according to the prior art in its installed state;
[0025] FIG. 4a-c shows three perspective views of the spring-arm
heat shield according to FIG. 1;
[0026] FIG. 5 shows a section of a heat shield having
circumferential flange according to the prior art in its installed
state;
[0027] FIG. 6a-c shows three perspective views of the heat shield
having circumferential flange according to FIG. 5;
[0028] FIG. 7a-c shows three perspective views of a wave-spring
heat shield according to the invention;
[0029] FIG. 8 shows a section of a wave-spring heat shield
according to the invention in its installed state, with the turbine
housing and the bearing housing being connected together by a screw
fastening;
[0030] FIG. 9 shows a section of the wave-spring heat shield
according to FIG. 7a-7c in its installed state, with the turbine
housing and the bearing housing being connected together by a
clamp-band fastening; and
[0031] FIG. 10 shows a graph in which are compared the
force-displacement curves of the wave-spring heat shield and the
spring heat shield having radially arranged spring arms.
[0032] In all figures, identical or functionally equivalent
elements and devices have been given the same reference numerals,
unless otherwise stated.
[0033] FIG. 1 shows a section of a "sandwich" heat shield 10
according to the prior art in its installed state. The "sandwich"
heat shield 10 here lies between a turbine housing 12 and a bearing
housing 14 of a turbocharger 16, and is braced axially in series
with these components either by a screw fastening or by a
clamp-band fastening.
[0034] The "sandwich" heat shield 10, however, has the problem that
that the thickness tolerance of the heat shield 10 affects the
axial contour gap 18 between a turbine wheel 20 of the turbocharger
16 and the turbine housing 12. The contour gap 18 in turn affects
the thermodynamics and hence the efficiency of the turbine. A
larger axial distance must be provided between the turbine wheel 20
and the turbine housing 12 as a result of the thickness tolerance
of the "sandwich" heat shield 10, which can be made as a
sheet-metal part or turned part. Hence the turbine has a lower
efficiency.
[0035] FIGS. 2a and 2c show the "sandwich" heat shield 10 in two
perspective views, with the views each showing the "sandwich" heat
shield 10 from the side that has the contact surface 22 for the
turbine housing 12. In addition, FIG. 2b shows a side view of the
"sandwich" heat shield 10, with the flat contact surface 24 for the
bearing housing and the flat contact surface 26 for the turbine
housing being shown. The "sandwich" heat shield 10 is here curved
outwards in two steps on the turbine-housing side, and has a hole
34 in order to be mounted on the bearing housing 14 or on the shaft
28 of the turbocharger 16.
[0036] In addition, FIG. 3 shows a section of a "spring-arm" heat
shield 10 according to the prior art in its installed state. The
turbine housing 12 here lies axially directly against the bearing
housing 14. In this case, the spring-arm heat shield 10 is braced
in parallel between the bearing housing 14 and the turbine housing
12, and hence has no effect on the contour gap 18. FIG. 3 shows a
contact surface 22 for the turbine housing 12 against the bearing
housing 14, for example with a clamp-band fastening. It also shows
an arm 30, having radial spring action, of the heat shield 10, as
clamped between the bearing housing 14 and the turbine housing 12.
In addition, the figure shows an axial gap 32 between the turbine
housing 12 and the bearing housing 14, which is defined by the
contact surface 22.
[0037] FIGS. 4a and 4c show a perspective view of the spring-arm
heat shield 10, said spring-arm heat shield 10 being shown from the
side that faces the turbine wheel when in its installed state. The
heat shield 10 here has three spring arms 30, which are bent
outwards. In addition, FIG. 4b shows a side view of the spring-arm
heat shield 10. The heat shield 10 is here curved outwards on the
turbine-wheel side and has a hole 34 in the center in order to be
mounted on the shaft 30 of the turbocharger 16 or on the bearing
housing 14.
[0038] The spring-arm heat shield 10 has the disadvantage that
rapid heating of the components causes the components to expand
very rapidly. The short spring arms 30, constrained by the physical
space, are attached by a very small corner radius, which, under
expansion, can result in excessive thermo-mechanical stresses and
to deformation of the components in this corner radius. An
excessive stress of this kind can cause the spring arms 30 to crack
or to break off entirely. The heat shield 10 thereby becomes loose
and can co-rotate and hence lose the heat-shielding function. In
this case it can also come into contact with the turbine wheel,
which will result in total failure of the turbocharger.
[0039] Another problem with the short spring arms 30 is the steep
force-deflection curve of the spring, which means that the spring
force rises very steeply over the working range for a small change
in deflection, as shown in FIG. 10. To prevent the spring force
from becoming too high, and hence increasing the risk of plastic
deformation of the spring arms 30 and of difficult assembly, the
maximum possible spring deflection, and hence also the working
range, is very small. The fact that the spring must cover the
tolerance chain and dynamic thermal expansion of the installation
space while being defined by the steep force-deflection curve and
the limited spring deflection/working range means that there can be
a loss in pretension force during operation. This problem is known
in the prior art, and results time and again in failure of the
turbocharger.
[0040] In addition, FIG. 5 shows a section of a heat shield 10
having a circumferential flange 36 according to the prior art in
its installed state. The heat shield 10 is here installed in the
same way as the heat shield 10 having the spring arms 30. In this
case the turbine housing 12 lies axially directly against the
bearing housing 14, with, for example, a contact surface 22 for the
turbine housing 12 against the bearing housing 14 being provided
with the use of a clamp-band fastening. The heat shield 10 having
the circumferential rim 36 is braced in parallel between the
bearing housing 14 and the turbine housing 12, in other words its
circumferential flange 36 is held under spring tension. The heat
shield 10 thereby has no effect on the contour gap 18 between the
turbine wheel 20 and the turbine housing 12. In addition, FIG. 5
shows an axial gap 32 between the turbine housing 12 and the
bearing housing 14, which is defined by the contact surface 22 for
the turbine housing 12.
[0041] FIGS. 6a and 6c show a respective perspective view of the
heat shield 10 having circumferential flange 36, with the heat
shield 10 being shown from the side that faces the turbine wheel
when in its installed state. In addition, FIG. 6b shows a side view
of the heat shield 10. In this case, the heat shield 10 has a
stepped curvature 38 that curves outwards towards the turbine
wheel, and a spring-action flange 36. In addition, a hole 34 is
provided in order to mount the heat shield 10 on the shaft of the
turbocharger or on the bearing housing 14.
[0042] FIGS. 7a and 7c now show a perspective view of a wave-spring
heat shield 100 according to the invention from the side that faces
a turbine wheel when in its installed state. The wave-spring heat
shield 100 has, for example, a hole 34 for mounting the heat shield
100 on a turbocharger 16. In addition, the wave-spring heat shield
100 is shown in a side view in FIG. 7b.
[0043] The wave-spring heat shield 100 according to the invention
has a circumferential rim or flange 40, on which are arranged, for
example, three web sections 42, which are curved outwards in order
for each to provide a spring-action section, or more precisely a
spring arm 30. The web sections 42 are here each formed in the
circumferential rim 40 by making a corresponding slotted section 44
in the rim 40. For the elongated web sections 42, as are shown in
FIGS. 7a and 7c, an elongated web section 42 is accordingly
provided radially on the circumferential rim 40 of the heat shield
100, with, in each case, an elongated slotted section 44 being
provided for this purpose radially on the circumferential rim 40 in
order to form the respective web section 42. The web section 42 can
have a constant thickness in each case, as is shown in FIGS. 7a and
7c, or can be designed to have a thickness that varies along the
length, depending on the function or application.
[0044] The respective web sections 42 are bent outwards, for
example curved outwards substantially tangentially, in order to
produce a spring arm 30 having a suitable spring displacement. The
spring displacement in this case can be designed to be larger than
the spring displacement, for example, of the heat shield 10 having
a circumferential flange 36, as is shown in FIGS. 5 and 6.
[0045] The wave-spring heat shield 100 can here have at least one,
two, three or more web sections 42, which are bent outwards as
spring arms 30. The web sections 42 can be arranged radially on the
circumferential rim 40 of the heat shield 100 either evenly, as is
shown in FIGS. 7a and 7c, or irregularly, depending on the function
or application. The web sections 42 can each be designed to have an
identical or different shape and/or size. In addition, instead of
one track 46 having web sections 42, as is shown in FIGS. 7a and
7c, it is also possible to provide two, three and more tracks, each
having at least one or more web sections 42. In FIG. 7a, a second
track 46 having an additional web section 42 is indicated by a
dashed line, with the web sections 42 of the two tracks 46 being
arranged substantially in line, for example. Alternatively, the web
sections 42 can also be mutually offset or partially offset from
each other (not shown).
[0046] Furthermore, the web sections 42 of the tracks 46 can each
be designed to have an identical or different shape and/or size,
for example. For instance, the outer track 46 can have the longest
web sections 42, and the innermost track 46 the shortest web
sections 42 and vice versa, it being possible for the web sections
42 of the tracks 46 to have the same shape or a different shape and
size, for example. In addition, the web sections 42 of one track 46
or a plurality of tracks 46 can be designed to have an identical or
different level of curvature, in other words to have the same or a
different spring displacement. In principle, the web sections 42 of
one track 46, and the web sections 42 of a plurality of tracks 46
can be as varied as required depending on the function and
application, for example.
[0047] FIG. 8 now shows a section of the wave-spring heat shield
100 in its installed state, with the turbine housing 12 and the
bearing housing 14 being connected together via a screw fastening,
for example. FIG. 8 also shows a corresponding contact surface 22
of the turbine housing 12.
[0048] Substantially longer spring arms 30 for the same
installation space can be achieved by the bent-outwards web
sections 42, or more precisely by the tangential arrangement of the
spring arms 30. The longer spring arms 30 in turn enable a flat
shape of the force-displacement curve, as is shown in FIG. 10, i.e.
the spring force remains constant over the working range of the
spring. Thanks to the flat curve, the axial spring displacement can
be chosen to be very large, thereby enabling adjustment for
tolerances and for thermal expansion without a reduction in the
spring force. It is thereby always guaranteed that the spring will
not become loose.
[0049] The level of the spring force in the working range can be
defined by the shape of the spring arms 30, or in other words, by
the shape and bending of the web sections 42. It is also
conceivable to design the spring arms 30 so that, unlike the case
shown in FIGS. 7a and 7c, they are not closed in the
circumferential direction. Instead, the spring arm 30 can also be
designed to be open at one end or, for example, in the center, as
is indicated by a dashed line in FIGS. 7a and 7c. This allows one
or both section(s) of the spring arm to be bent even further
outwards in order to achieve a longer spring deflection, it being
possible to bend the two sections of the spring arm 30 outwards by
an equal or different amount.
[0050] In addition, FIG. 9 shows a section of the wave-spring heat
shield 100 in its installed state, with the turbine housing 12 and
the bearing housing 14 being connected via a clamp-band fastening,
for example. FIG. 9 also shows a corresponding contact surface 22
of the turbine housing 12 and also an axial gap 32 between the
turbine housing 12 and the bearing housing 14. The wave-spring heat
shield 100 is here mounted by its hole 34 on the shaft 28 of the
turbocharger 16 or on a projection of the bearing housing 14. The
figure shows a web section 42, which is bent forwards, preferably
substantially tangentially, in order to form the spring arm 30,
with the bearing housing 14 and the turbine housing 12 being braced
against each other via a clamp-band fastening, for example. In this
case, the wave-spring heat shield 100 has a stepped pot shape,
although it can also be designed as a disc, for example, with the
web sections being bent outwards accordingly in order to form
spring arms. Hence the embodiments made above also apply
accordingly to a wave-spring heat shield 100 in the form of a
disc.
[0051] Although the present invention has been described above with
reference to the preferred exemplary embodiments, it is not
restricted to these, but can be modified in a variety of ways. The
embodiments described above, in particular individual features of
these embodiments, can also be combined with each other.
* * * * *