Title: Secondary air turbocharger with sound absorbing insulating material
Abstract: A secondary air induction system (1) for an internal combustion engine of a motor vehicle, including a turbine (2) and a compressor (3), in which a turbine wheel (4) of the turbine (2) and a compressor wheel (5) of the compressor (3) are mounted on a rotatable common shaft (6) supported by a bearing assembly (8) including at least one roller bearing (17) inside a turbocharger housing (7). An insulating or noise damping material (9) externally encloses at least a portion of the housing (7) to provide sound insulation in the area of the bearing assembly (8).
Patent Number: 6,899,531 Issued on 05/31/2005 to Hummel
| Inventors:
|
Hummel; Karl-Ernst (Bietigheim-Bissingen, DE)
|
| Assignee:
|
Mann & Hummel GmbH (Ludwigsburg, DE)
|
| Appl. No.:
|
719027 |
| Filed:
|
November 24, 2003 |
Foreign Application Priority Data
| Nov 25, 2002[DE] | 102 54 859 |
| Current U.S. Class: |
417/407; 60/397; 415/119; 415/177; 417/406 |
| Intern'l Class: |
F04B 017/00; F16D031/02 |
| Field of Search: |
417/407,406
60/602,396,397
415/119,406,177,178,175
|
References Cited [Referenced By]
U.S. Patent Documents
| 3059415 | Oct., 1962 | Birmann.
| |
| 3256689 | Jun., 1966 | Zeek.
| |
| 3310940 | Mar., 1967 | Oetliker.
| |
| 3845619 | Nov., 1974 | O'Neill.
| |
| 3849022 | Nov., 1974 | Amann et al.
| |
| 3928963 | Dec., 1975 | Devers et al.
| |
| 4504188 | Mar., 1985 | Traver et al.
| |
| 4508486 | Apr., 1985 | Tinker.
| |
| 5199846 | Apr., 1993 | Fukasaku et al.
| |
| 2004/0109759 | Jun., 2004 | Korner.
| |
| Foreign Patent Documents |
| 24 46 834 | Apr., 1976 | DE.
| |
| 123140 | Nov., 1976 | DE.
| |
| 10022052 | Mar., 2001 | DE.
| |
| 60033000 | Feb., 1985 | JP.
| |
| WO-97 4894/3 | Dec., 1997 | WO.
| |
Primary Examiner: Trieu; Thai-Ba
Attorney, Agent or Firm: Crowell & Moring LLP
Claims
1. A secondary air turbocharger for an internal combustion engine of a motor
vehicle, said turbocharger comprising a turbine and a compressor, wherein a turbine
wheel of the turbine and a compressor wheel of the compressor are mounted on a
rotatable common shaft supported by a bearing assembly inside a turbocharger housing,
said bearing assembly comprising at least one roller bearing, and at least a portion
of the housing being enclosed externally in the area of the bearing assembly by
a sound absorbing insulating material of synthetic resin foam for noise suppression.
2. A secondary air turbocharger according to claim 1, wherein the turbocharger
housing has a smaller diameter in the area of the bearing assembly than in the
area of the turbine and the compressor, and the insulating material encloses the
area of the bearing assembly between the turbine and the compressor.
3. A secondary air turbocharger according to claim 2, wherein said synthetic
resin foam is a polyurethane foam.
4. A secondary air turbocharger according to claim 1, wherein the insulating
material contains at least one fiber selected from the group consisting of glass
fibers and mineral fibers.
5. A secondary air turbocharger according to claim 1, further comprising a shell
externally enclosing the insulating material.
6. A secondary air turbocharger according to claim 5, wherein the shell is provided
as a mold into which a synthetic resin foam is injected.
7. A secondary air turbocharger according to claim 6, wherein the shell comprises
two interconnectable half shells.
8. A secondary air turbocharger according to claim 7, wherein the two half shells
are constructed as a one-piece, injection-molded synthetic resin component and
are joined by a film hinge in the area of a parting line and have at least one
snap connector in the area of an opposite parting line.
9. A secondary air turbocharger for an internal combustion engine of a motor
vehicle, said turbocharger comprising a turbine and a compressor, wherein a turbine
wheel of the turbine and a compressor wheel of the compressor are mounted on a
rotatable common shaft supported by a bearing assembly inside a turbocharger housing;
said bearing assembly comprising at least one roller bearing, at least a portion
of the housing being enclosed externally in the area of the bearing assembly by
a sound absorbing insulating material, and wherein the insulating material at least
substantially completely encloses the housing in the area of the turbine, the bearing
assembly and the compressor.
10. A secondary air turbocharger for an internal combustion engine of a motor
vehicle, said turbocharger comprising a turbine and a compressor, wherein a turbine
wheel of the turbine and a compressor wheel of the compressor are mounted on a
rotatable common shaft supported by a bearing assembly inside a turbocharger housing;
said bearing assembly comprising at least one roller bearing, at least a portion
of the housing being enclosed externally in the area of the bearing assembly by
a sound absorbing insulating material, and wherein the synthetic resin foam contains
at least one sound absorbing filler.
Description
BACKGROUND OF THE INVENTION
The present invention relates to a secondary air induction system for an internal
combustion engine of a motor vehicle comprising a turbine and a compressor, with
a turbine wheel of the turbine and a compressor wheel of the compressor rotatably
mounted on a common shaft inside a turbocharger housing.
As a rule, turbocharger comprise two flow machines, namely, a turbine and a compressor,
which are mounted on a common shaft. An air or gas stream produced as a result
of a pressure difference drives the turbine, which in turn drives the compressor,
which draws in air and pre-compresses it. The shaft is normally supported by oil
lubricated friction bearings.
To prevent problems during cold start and in a warm-up period of internal combustion
engines in motor vehicles, the engines are provided with secondary air induction
systems in the form of turbocharger. The turbine of the secondary air induction
system is driven, for example, by the pressure difference across a throttle valve
in an air intake channel of the internal combustion engine. The turbine, in turn,
drives the compressor, which is used to introduce fresh air into the exhaust system
of the internal combustion engine. The oxygen content in the fresh air stream leads
to an oxidation of the pollutants in the exhaust system. In addition to the resulting
removal of pollutants, the thermal energy released during oxidation heats the catalytic
converter more quickly to the desired operating temperature.
With systems becoming increasingly complex and undesirably heavy and limited
space available in the engine compartment, a suitable secondary air induction system
must be small and light. To achieve a sufficient degree of effectiveness, it must
be designed to operate at a high speed. This is associated with undesirably high
noise generation In addition, the shaft bearings for the turbocharger should be
independent of external lubrication.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the invention to provide an improved
secondary air induction system for an internal combustion engine of a motor vehicle.
Another object of the invention is to provide a secondary air induction system
which has a compact, lightweight construction.
A further object of the invention is to provide a secondary air induction system
which can operate at a lower noise level.
These and other objects are achieved in accordance with the present invention
by providing a secondary air turbocharger for an internal combustion engine of
a motor vehicle, the turbocharger comprising a turbine and a compressor, wherein
a turbine wheel of the turbine and a compressor wheel of the compressor are mounted
on a rotatable common shaft supported by a bearing assembly inside a turbocharger
housing; the bearing assembly comprising at least one roller bearing, and at least
a portion of the housing being enclosed externally in the area of the bearing assembly
by a sound absorbing insulating material.
To this end, a secondary air induction system is proposed having a shaft supported
by at least one roller bearing and a housing which is at least partially enclosed
externally in the bearing area by a sound insulating or damping material that absorbs
noise. Turbochargers make a considerable amount of noise. This is particularly
true if the common shaft is supported by roller bearings, which are preferred for
secondary air induction systems. It has been discovered that providing an insulating
material on the outside, at least in the area of the roller bearing assembly, dampens
the noise very effectively. The housing of the turbocharger can tightly enclose
the turbine, the compressor and the bearing assembly and can be constructed with
thin walls. This provides a space and weight saving structure. Because of the typically
complex shape of the housing, the insulating material can be primarily disposed
in corresponding recesses. As a result, the insulating material does not substantially
add to the overall volume. Existing turbocharger designs can be retrofitted to
include the sound absorbing design according to the invention without requiring
any structural changes.
Closer investigation has shown that the main source of the noise is the shaft
bearing. The arrangement of a secondary air induction system remote from the engine
lubricating oil circuit leads to the bearing assembly being constructed with lifetime-lubricated
roller bearings, e.g. ball bearings, the rolling noise of which contributes substantially
to noise generation.
In one advantageous embodiment of the invention in which the housing is surrounded
in the bearing area by insulating material, a surprisingly significant reduction
in noise level is achieved. Particularly if the housing has a smaller diameter
in the area of the bearing assembly than in the area of the turbine and the compressor,
it is advantageous to enclose the area of the bearing assembly between the turbine
and the compressor with insulating material. In addition to providing effective
damping of the bearing noise, this arrangement also provides at least partial damping
of the turbine and compressor noise. Filling the space between the turbine and
the compressor with insulating material does not enlarge the overall contour of
the turbocharger, so that no additional installation space is required.
In an advantageous further embodiment of the invention the housing is enclosed
with insulating material in the area of the turbine and/or the compressor. It has
been found that in addition to the bearing noise, the aerodynamic noise of the
high-speed turbine or the compressor contributes significantly to the operating
noise of the turbocharger. Arranging the insulating material on the outside of
this area substantially reduces the noise level even if the walls of the housing
are thin.
In an advantageous further embodiment of the invention, the housing is at least
substantially completely enclosed with insulating material in the area of the bearing
assembly, the turbine and the compressor. As a result, the entire turbocharger
is at least substantially completely externally encapsulated. The outer contour
of the insulating material needs to be only slightly larger than the outer contour
of the housing. The complex outer shape nevertheless offers many spaces that can
be filled with insulating material. Despite the high noise damping effect, the
outer contour and thus the required overall structural volume are not significantly increased.
All of the embodiments according to the invention have in common that in addition
to the actual insulation provided by the insulating material in which the sound
energy is dissipated in the material itself, the insulating material also prevents
natural vibration of parts of the housing wall. As a result, the housing of the
turbocharger can have very thin walls to save material and can be light in weight,
without wall vibrations increasing the noise level.
A suitable noise damping material has been found to be a synthetic resin form,
e.g., a polyurethane (PU) foam. Advantageously, the synthetic resin foam is provided
with sound absorbing fillers. Such a foam has a good damping effect and can be
readily processed using simple and inexpensive tools. Alternatively, glass fibers
and/or mineral fibers, such as mineral wool or the like, may be used as noise damping materials.
In one advantageous further embodiment of the invention, a shell encloses the
insulating material on the outside. This shell can provide an additional noise
damping effect. The shell moreover protects the insulating material, which may
be quite soft, against damage. Advantageously, the shell also can function as a
mold into which the polyurethane foam is injected. As the polyurethane foam cures,
it firmly bonds to the shell, so that the shell serves as a "lost" mold. This eliminates
the need for an additional mold and saves costs. As an alternative, it may also
be advantageous to place the turbocharger into a suitable mold without a shell
and to inject the polyurethane foam around it.
The shell advantageously is comprised of two interconnectable half shells. This
makes it easier to mount the shell to the fully assembled turbocharger. In particular,
the two half shells may be constructed as a one-piece component and are provided
with a film hinge in the area of a parting line and with at least one snap connector
in the area of the opposite parting line. The shell is advantageously made of synthetic
resin material (i.e., plastic), particularly by injection molding. This facilitates
assembly, which can be done manually or automatically by shutting the open half
shells around the turbocharger housing with the aid of the film hinge and closing
them with the snap connectors. The film hinge simultaneously forms a seal against
polyurethane foam leakage without adding to the complexity of the structure.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be described in further detail hereinafter with reference
to illustrative preferred embodiments shown in the accompanying drawings, in which:
FIG. 1 is a schematic partially cut-away view of a turbocharger provided as
a secondary air induction system, with a foam cover enclosing the area of the bearing
assembly between the turbine and the compressor;
FIG. 2 is an interior view of the arrangement depicted in FIG. 1, including
the details of a shell enclosing the insulating material;
FIG. 3 is a cross-section view of shell depicted in FIG. 2;
FIG. 4 is a partially cut-away view of a variant of the arrangement shown in
FIG. 1 with an insulating material which substantially completely encloses the
housing of the turbocharger, and
FIG. 5 is an exterior view of the arrangement depicted in FIG. 4, showing details
of the shell enclosing the insulating material.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
FIG. 1 is a schematic, partially cut-way view of a secondary air induction system
1 for an internal combustion engine of a motor vehicle comprising a turbine
2, a compressor and a housing
7. A turbine wheel
4 of the
turbine
2, a compressor wheel
5 of the compressor
3, a shaft
6 and a bearing assembly
8 are arranged inside the housing
7,
as indicated by broken line. The turbine wheel
4 and the compressor wheel
5 are mounted on the common shaft
6 so as to be rotatable together
about an axis
18 with the aid of the bearing assembly
8. In the illustrated
embodiment, the bearing assembly
8 is formed by two lifetime-lubricated
ball bearings
17.
In the area of the turbine
2, the housing
7 encloses the turbine
wheel
4, in the area of the compressor
3 the compressor wheel
5,
and in the area of the bearing assembly
8 the ball bearings
17 and
the shaft
6. In the area of the turbine
2, the housing also has an
inlet tube
22 and an outlet tube
21. In the area of the compressor
8, an inlet tube
19 and a discharge tube
20 are provided on
the housing
7.
The turbine
2 is connected with an intake tract of the internal combustion
engine (not shown), such that a pressure difference created across a throttle valve
causes a partial air stream to flow through the turbine
2 as generally indicated
by arrow
24 and thereby rotatably drives the turbine wheel
4. The
rotation of the turbine wheel
4 is transmitted via the shaft
6 to
the compressor wheel
5, such that a secondary air stream is drawn into the
inlet tube
19 and propelled out of te discharge tube
20 as generally
indicated by arrow
23 toward an engine exhaust system (not shown).
A portion of the housing
7 is provided externally with an insulating material
9 for sound absorption. The housing
7 has a smaller diameter in the
area of the bearing assembly
8 than in the area of the turbine
2
and the compressor
3. The housing
7 is enclosed with the insulating
material
9 in the area of the bearing assembly
8 between the turbine
2 and the compressor
8. The insulating material
9, in turn,
is enclosed on the outside by an annular hell
10 located between the turbine
2 and the compressor
3.
In the illustrated embodiment, the insulating material
9 comprises a polyurethane
foam that is provided with sound-absorbing fillers. It is also possible to use
an insulating material
9 that contains glass fibers and/or mineral fibers.
FIG. 2 is an exterior view of the arrangement depicted in FIG. 1, according
to which the shell
10 is constructed of two half shells
11 and
12.
The two half shells
11 and
12 are joined along a parting line
15
by snap connectors
16. In the area of the parting line
15 an injection
opening
25 is provided for injecting the polyurethane foam used as the insulating
material
9 (FIG.
1). The shell
10 serves as a "lost" injection
mold for injection molding of the polyurethane foam.
FIG. 3 is a cross-sectional view showing details of the shell
10 according
to FIGS. 1 and 2. The two half shells
11 and
12 are formed as one-piece
or integral component and are pivotably interconnected by a film hinge
14
in the area of a parting line
13 opposite the parting line
15. The
two half shells
11 and
12, the film binge
14 and the snap
connectors
16 are produced as a one-piece injection-molded synthetic resin component.
When the snap connectors
16 are open, the two half shells
11 and
12 can be pivoted in relation to one another. When folded open, the two
half shells
11 and
12 can be disposed around the housing
7
of the secondary air induction system
1 (FIGS.
1 and
2). Folding
the two half shells
11 and
12 together and closing the snap connectors
16 creates a substantially tight mold for the polyurethane foam surrounding
the area of the bearing assembly
8 (FIG.
1).
FIG. 4 shows a schematic partially cut-away view of a variant of the arrangement
according to FIGS. 1 to
3 in which the housing
7 is at least substantially
completely enclosed by the insulating material
9 in the area of the bearing
assembly
8, the turbine
2 and the compressor
3. The insulating
material
9 is enclosed radially on the outside and also on its end faces
by a correspondingly shaped substantially cylindrical shell
10. Only the
inlet tube
19, the discharge tube
20, the outlet tube
21 and
the inlet tube
22 protrude from the insulating material
9 or the
shell
10. Suitable annular seals
26 may be provided to seal the shell
10 relative to the inlet tube
19 and the outlet tube
21.
FIG. 5 is an exterior view of the arrangement depicted in FIG. 4, according
to which the two half shells
11 and
12 are joined by a plurality
of snap connectors
16 along a parting line
15 extending diagonally
and at an angle from the discharge connection
20 to the injection connection
22.
With respect to the remaining features and reference numerals, the arrangement
shown in FIGS. 4 and 5 corresponds to that shown in FIG. 1 through 3.
The foregoing description and examples have been set forth merely to illustrate
the invention and are not intended to be limiting. Since modifications of the described
embodiments incorporating the spirit and substance of the invention may occur to
persons skilled in the art, the invention should be construed broadly to include
all variations within the scope of the appended claims and equivalents thereof.
*
