Title: Acoustical heat shield
Abstract: A heat shield includes an inner portion, an outer portion, first and second insulating portions, and a deflecting portion. The inner portion includes a reflective material to reflect thermal energy that radiates from a heat/acoustic source. The outer portion includes a rigid material to provide structural support for the heat shield. The first and second insulating portions are intermediately positioned between the inner and outer portions. The deflecting portion is intermediately positioned between the first and second insulating portions to deflect acoustics from the heat/acoustic source. A method for manufacturing the heat shield is also disclosed.
Patent Number: 6,966,402 Issued on 11/22/2005 to Matias, et al.
| Inventors:
|
Matias; Calin (London, CA);
Boogemans; Mark (Belmont, CA);
Kirkwood; Jason (Belleville, MI)
|
| Assignee:
|
DANA Corporation (Toledo, OH)
|
| Appl. No.:
|
452895 |
| Filed:
|
June 2, 2003 |
| Current U.S. Class: |
181/290; 181/286; 181/296; 181/240; 60/323; 428/174; 428/201; 428/138; 442/378; 442/381; 442/394 |
| Intern'l Class: |
E04B 001/82; F01N 007/14; B32B 003/10; B32B 015/14 |
| Field of Search: |
181/290,292,294,286,296,207,240
|
References Cited [Referenced By]
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| 4709781 | Dec., 1987 | Scherzer.
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| 5057176 | Oct., 1991 | Bainbridge.
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| 5100733 | Mar., 1992 | Yoshida et al.
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| 5139839 | Aug., 1992 | Lim.
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| 5196253 | Mar., 1993 | Mueller et al.
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| 5334806 | Aug., 1994 | Avery.
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| 5424139 | Jun., 1995 | Shuler et al.
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| 5464952 | Nov., 1995 | Shah et al.
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| 5590524 | Jan., 1997 | Moore, III et al.
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| 5665943 | Sep., 1997 | D'Antonio.
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| 5792539 | Aug., 1998 | Hunter.
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| 5945643 | Aug., 1999 | Casser.
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| 6026846 | Feb., 2000 | Wolf et al.
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| 6251498 | Jun., 2001 | Fukushima et al.
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| 6305494 | Oct., 2001 | Pfaffelhuber et al.
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| 6328513 | Dec., 2001 | Niwa et al.
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| 6451447 | Sep., 2002 | Ragland et al.
| |
| 6465110 | Oct., 2002 | Boss et al.
| |
| 6581720 | Jun., 2003 | Chen et al.
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| 6681890 | Jan., 2004 | Chen et al.
| |
| 2004/0142152 | Jul., 2004 | Chen et al.
| |
| Foreign Patent Documents |
| 2 152 431 | Aug., 1985 | GB.
| |
| 09049426 | Feb., 1997 | JP.
| |
| 09242561 | Sep., 1997 | JP.
| |
| 2001065363 | Mar., 2001 | JP.
| |
| WO-90/1216/8 | Oct., 1990 | WO.
| |
| WO-97/3674/3 | Oct., 1997 | WO.
| |
Other References
International Search Report (2 pages).
|
Primary Examiner: Martin; Edgardo San
Claims
1. A heat shield comprising:
an inner portion and outer portion, wherein the inner portion includes a reflective
material to reflect thermal energy that radiates from a heat/acoustic source, wherein
the outer portion includes a rigid material to provide structural support for the
heat shield;
first and second insulating portions intermediately positioned between the inner
and outer portions; and
a deflecting portion intermediately positioned between the first and second insulating
portions that deflects acoustics from the heat/acoustic source.
2. The heat shield according to claim 1, wherein the deflecting portion material
is constructed of steel.
3. The heat shield according to claim 1, wherein dimples and air pockets are
formed on an upper surface and lower surface of the deflecting portion.
4. The heat shield according to claim 3, wherein the dimples may be formed to
a geometric shape, wherein the geometric shape is selected from the group consisting
of a spherical shape, a pyramid shape, a conical shape, and a trapezoidal shape.
5. The heat shield according to claim 3, wherein the dimples are distributed
in offset rows and columns.
6. The heat shield according to claim 3, wherein the dimples are distributed
in a uniform row and column pattern.
7. The heat shield according to claim 3, wherein the dimples are distributed
in a randomized non-uniform pattern.
8. The heat shield according to claim 3, wherein the dimples and air gaps are
symmetrically disposed about a plane.
9. The heat shield according to claim 3, wherein the dimples and air gaps are
non-symmetrically disposed about a plane.
10. The heat shield according to claim 3, wherein the dimples include perforations
disposed about dimple peaks located on the upper surface of the deflecting portion,
and about dimple valleys located on the lower surface of the deflecting portion.
11. The heat shield according to claim 10, wherein the deflecting portion includes
a thickness defined by the dimple peaks on an upper surface to the dimple valleys
on a lower surface.
12. The heat shield according to claim 1, wherein the deflecting portion may
comprise a high-density wire mesh or honeycomb-shaped surface.
13. The heat shield according to claim 1, wherein the inner portion material
includes aluminized clad, the outer portion material includes aluminized steel,
and the insulating portions includes a mineral fiber material.
14. The heat shield according to claim 1, wherein the heat/acoustic source is
an exhaust manifold.
15. The heat shield according to claim 14, wherein the heat shield is spaced
from the exhaust manifold by a predetermined distance so as to form an air gap
between the exhaust manifold and the heat shield.
16. The heat shield according to claim 1 further comprising at least one isolator
that damps vibrations applied to the heat shield from the heat/acoustic source.
17. The heat shield according to claim 16, wherein the isolator includes top
and bottom cold rolled steel washers crimped about a stainless steel mesh that
are positioned about an outer periphery of a low bearing tube.
18. A method for manufacturing a heat shield comprising the steps of:
blanking an outer portion to form a hemmed portion;
positioning a first insulating portion over the outer portion;
positioning an acoustic and heat deflecting portion over the first insulating
portion;
positioning a second insulating portion over the deflecting portion;
positioning an inner portion over the second insulating portion; and
hemming the hemmed portion of the outer portion about a periphery of the heat
shield defined by the first insulating portion, the deflecting portion, the second
insulating portion, and the inner portion.
19. The method according to claim 18 further comprising the step of forming said
deflecting portion by blanking a rigid material in a press or die having a textured
surface so as to produce dimples and air gaps on the deflecting portion.
20. The method according to claim 18 further comprising the step of forming the
heat shield to a contour of a component that shields acoustics and heat.
21. The method according to claim 18 further comprising the step of forming passages
in the heat shield.
22. A heat shield comprising:
an inner portion having a first thickness approximately equal to 0.15 nm and
an outer portion having a first thickness approximately equal to 0.40 mm, wherein
the inner portion includes a reflective material to reflect thermal energy that
radiates from a heat/acoustic source, and wherein the outer portion includes a
rigid material to provide structural support for the heat shield;
a first insulating portion having a first thickness approximately equal to 0.92
mm and a second insulating portion having a first thickness approximately equal
to 0.92 mm, intermediately positioned between the inner and outer portions; and
a deflecting portion that includes a first thickness approximately equal to 0.91
mm, intermediately positioned between the first and second insulating portions
that deflects acoustics from the heat/acoustic source.
Description
BACKGROUND OF THE INVENTION
1. Field of Invention
The present invention relates to improvements in heat shields for internal combustion
engines, and more particularly to heat shields having improved acoustic and heat
dampening features.
2. Description of the Prior Art
Those skilled in the art will appreciate the issues involved in the dampening
of undesirable acoustics and heat generated by automotive components, such as,
for example, exhaust manifolds. Known heat shields that provide acoustic dampening
may include multiple aluminum foil layers with embossments. Typically, the embossments
are positioned in a staggered relationship to contact and space opposing foil layers.
However, because the embossments directly contact the opposing foil layers, undesirable
noise issues, such as rattle, may occur as a result of the vibrations of the embossments
against the foil layers.
Other known heat shields comprise a three-layer structure including inner and
outer metal layers with an intermediately disposed sound and heat shielding layer.
Such three-layer heat shields have design restrictions that require the inner and
outer layers to include different thicknesses so as to provide resonant frequencies
that dampen undesirable acoustics. Even further, such three-layer heat shields
undesirably require that the intermediately disposed sound and heat shielding layer
includes a relatively large thickness in comparison to the inner and outer layers
to fully damp the sound and heat to operable levels.
Thus, there is a need for an alternative heat shield that may overcome the
undesirable fallbacks of traditional heat shields.
SUMMARY OF THE INVENTION
The disclosed invention provides a heat shield including an inner portion, an
outer portion, first and second insulating portions, and a deflecting portion.
The inner portion includes a reflective material to reflect thermal energy that
radiates from a heat/acoustic source. The outer portion includes a rigid material
to provide structural support for the heat shield. The first and second insulating
portions are intermediately positioned between the inner and outer portions. The
deflecting portion is intermediately positioned between the first and second insulating
portions to deflect acoustics from the heat/acoustic source.
The disclosed invention also provides a method for manufacturing the heat shield.
The method includes the steps of blanking the outer portion to form a hemmed portion,
positioning the first insulating portion over the outer portion, positioning the
deflecting portion over the first insulating portion, positioning the second insulating
portion over the deflecting portion, positioning the inner portion over the second
insulating portion, and hemming the hemmed portion of the outer portion about a
periphery of the heat shield defined by the first insulating portion, the deflecting
portion, the second insulating portion, and the inner portion.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an exploded perspective view of a heat shield according to one embodiment
of the invention.
FIG. 2 is an assembled side view of a portion of the heat shield of Figure of
FIG. 1.
FIG. 3A is a magnified view of a surface of the heat shield portion that opposes
an insulation portion of the heat shield, which is referenced from line 3
of FIG. 1.
FIGS. 3B-3D are magnified views of alternative embodiments of the heat shield
surface illustrated in FIG. 3A.
FIG. 4A is a cross-sectional view of the heat shield portion of FIG. 3A, taken
along lines 4—4 of FIG. 2.
FIGS. 4B-4D are cross-sectional views of alternate embodiments of the heat
shield surface illustrated in FIG. 4A, which corresponds to the magnified views
illustrated in FIGS. 3B-3D.
FIG. 5 is a perspective view of an isolator adapted for coupling to the heat
shield illustrated in FIG. 1.
FIGS. 6A-6H illustrates an assembly process for forming the heat shield of
FIG. 1.
DETAILED DESCRIPTION OF THE EMBODIMENTS
Referring initially to FIG. 1, components comprising a heat shield
10
in accordance with the present invention are shown in exploded form. As illustrated,
the heat shield
10 includes an inner portion
12 and outer portion
14 that are spaced by insulating portions
16,
18 with an intermediately
positioned deflecting portion
20. The outer portion
14 is constructed
from a rigid material to provide structural support for the heat shield
10,
and, as seen more clearly in FIG. 2, the inner portion
12 comprises a reflective
material to reflect undesirably produced thermal energy, or heat, which is generally
shown at H, that radiates from a heat/acoustic source
32. The deflecting
portion
20 includes a material that is defined by a plurality of dimples
22 and dual air pockets
24 (FIGS. 3A-4D) that deflect undesirably
produced acoustics, A, from the heat/acoustic source
32.
According to the illustrated embodiment, the inner portion
12, the
outer portion
14, and the insulating portions
16,
18 preferably
each includes aluminized clad, aluminized steel, and mineral fibers, respectively,
to provide adequate heat absorption, structural support, and insulation. As seen
in FIG. 2, the inner and outer portions
12,
14 include first and
second thickness, T
1 and T
2, and the insulating portions
16,
18 include third and forth thicknesses, T
3 and T
4. The thicknesses
T
1, T
2, T
3 and T
4 may include any desirable thickness.
For example, thickness, T
1, may preferably range between approximately 0.15
mm-0.40 mm, thickness, T
2, may preferably range between approximately 0.30
mm-0.60 mm, and thicknesses, T
3, T
4, may preferably range between
approximately 0.50 mm-3.00 mm. Although any desirable thickness not included in
any of the ranges listed may be incorporated in the design of the heat shield
10,
the above described thickness ranges provide optimal weight and performance characteristics
of the heat shield
10.
In conjunction with the illustrated embodiment of the heat shield
10,
the
thickness, T
1, may be approximately equal to 0.15 mm, the thickness, T
2,
may be approximately equal to 0.40 mm, the thickness, T
3, may be approximately
equal to 0.92 mm, and the thickness, T
4, may be approximately equal to 0.92
mm. The thickness, T
1, of the inner portion
12 is thinner in comparison
to the thickness, T
2, of the outer portion
14 to decrease the overall
weight of the heat shield
10. Aside from weight considerations, the primary
function of the inner portion
12 is to provide a reflective surface as opposed
to a relatively thicker, rigid surface that the outer portion
12 defines
at T
2. Although the insulation portions
16,
18 in the described
example have the same thicknesses, T
3, T
4, it is important to consider
that the insulation portions
16,
18 may have any desirable thickness.
Also, other thickness values for T
1 , T
2, T
3, and T
4
that do not fall within the preferable ranges listed above may be implemented in
other embodiments; however, greater thicknesses of T
1, T
2, T
3,
and T
4 may undesirably introduce clearance issues and increase the cost
and weight of the heat shield
10.
Other embodiments of the heat shield
10 may comprise inner and outer
portions
12,
14 that include any other desirable materials such as
stainless steel, nickel, or the like. Even further, the insulating portions
16,
18 may include any other desirable fiber, such as graphite fiber, ceramic
fiber, or the like. Although alternate materials such as ceramic fiber, graphite
fiber, and nickel perform adequately when implemented in the design of the above-described
heat shield
10, ceramic fiber, graphite fiber, and nickel tend to also increase
the overall cost and weight of the heat shield
10. Yet even further, mineral
fibers are preferable for implementation in the design of the heat shield
10
in favor of ceramic and graphite fibers because mineral fibers are nearly 100% recyclable.
Referring now to FIG. 2, the deflecting portion
20 includes any
desirable rigid material, such as steel, having any desirable thickness, T
5,
which is measured from the dimple peak
26 on an upper surface
28
to the dimple valley
29 on a lower surface
30. As illustrated, the
dimples
22 and air pockets
24 are formed on an upper surface
28
and lower surface
30 of the deflecting portion
20. The thickness,
T
5, may range from approximately 0.90 mm-1.50 mm. According to the illustrated
embodiment, the thickness, T
5, is approximately equal to 0.91 mm.
Functionally, the dimples
22 and air gaps
24 function
in the dissipation of undesirable noise energy, or acoustics, A, that radiate from
the heat/acoustic source
32, which may be an automotive component, such
as an exhaust manifold. If the heat/acoustic source
32 is an exhaust manifold,
it is preferable to space the exhaust manifold and heat shield
10 by a distance,
D, such that an air gap, G, (FIG. 2) is formed between the exhaust manifold and
the heat shield
10. The distance, D, may be any desirable length. One possible
implementation of the heat shield
10 may include a distance, D, from the
acoustic/heat source
32 that falls between the range of approximately 8.0
mm-15.0 mm.
The dissipation of the acoustics, A, is illustrated in FIG. 2 such that the acoustics,
A, travel in a path from the heat/acoustics source
32 and are deflected
or broken-up upon encountering the deflecting portion
20. The insulating
portions
16,
18 complement the function of the deflecting portion
20 by providing pre- and post-damping of the acoustics, A, while also functioning
in isolating the inner, outer, and deflecting portions
12,
14,
20.
If the insulating portions
16,
18 were not included in the design
of the heat shield
10, the inner, outer and deflecting portions
12,
14,
20, may otherwise produce inherently undesirable acoustics, such
as rattle, that would typically occur as a result of the vibrations emitted from
the inner, outer, and deflecting portions
12,
14,
20. Even
further, the insulating portions
16,
18 provide a secondary barrier
to absorb the undesirable acoustics, A, that may not be entirely damped by the
deflecting portion
20 in the event that the noise energy of the acoustics,
A, increase past the design threshold of the deflecting portion
20.
Referring to FIGS. 3A-3D, the dimples
22 may have any desirable
shape that functions in the dissipation of acoustics, A, and heat, H. For example,
the dimples
22 may have a generally spherical (FIG.
3A), pyramid
(FIG.
3B), conical (FIG.
3C), or trapezoidal shapes (FIG.
3D).
As illustrated, the dimples
22 are distributed in an offset row and column
pattern; however, the dimples
22 may alternatively comprise a uniform row
and column distribution or a randomized non-uniform distribution.
As seen in the illustrated embodiment, the deflecting portion
20 generally
includes an even distribution dimples
22 and air gaps
22. In this
example, because there is an even distribution of dimples
22 and air gaps
24, acoustic and heat dissipation performance is matched (i.e. there is
an approximate one-to-one ratio of dimples
22 and air gaps
24). However,
if the amount of dimples
22 is decreased (i.e. a larger air gap field is
created), acoustic dissipation may be compromised in favor of providing improved
heat absorption characteristics as a result of the heat, H, being forced to travel
through more air. Conversely, the dimples
22 may be formed to a shape that
minimizes the air gaps
24, and the acoustic dissipation characteristics
may improved as the heat absorption characteristics may be compromised.
As seen more clearly in FIGS. 4A and 4B, the dimples
22 and air gaps
24
may be symmetrically disposed about a plane, P. Alternatively, as seen in FIGS.
4C and 4D, the dimples
22 and air gaps
24 may be disposed in a non-symmetric
pattern. Referring to each of the illustrated embodiments in FIGS. 4A-4D, the deflecting
portion
20 may also include perforations
34 that are generally disposed
about the dimple peaks
26 and valleys
29 on the upper and lower surfaces
28,
30 of the deflecting portion
20. Functionally, the perforations
34 may increase the size of the air gap
24 by permitting each air
gap
24 to be bounded by each insulating portion
16,
18 about
the deflecting portion
20. Also, the perforations
34 may permit compression
of the dimples
22 about opposing perforation surfaces
31 if an undesirable
load is applied to the heat shield
10.
Although generally symmetric or non-symmetric geometric shapes are suggested
for the dimples
22, it is contemplated that the dimples
22 may include
other shapes or designs including perforations
34 or openings that do not
necessarily face the insulating portions
16,
18 in a perpendicular
relationship. For example, the deflecting portion
20 may comprise a texture
or grain that creates dimple-like features including minimized air gaps
24.
One possible deflecting portion
20 may include a high-density wire mesh.
In this instance, the deflecting portion
20 does not necessarily include
symmetric or geometrically controlled dimples
22 and air passages or gaps
24, but rather, a textured surface to dissipate acoustics, A, as well as
minimized air passages or gaps
24 that assists in the absorption of heat,
H. Another embodiment of the absorption portion
20 may include a generally
honeycomb-shaped surface. While a honeycomb-shaped surface may increase heat absorption
performance and structural rigidity of the heat shield
10 by providing air
gaps
24, the honeycomb design may compromise the overall performance of
the acoustic dampening by providing relatively flat upper and lower surfaces
28,
30 that do no include dimples
22.
If desired, the heat shield
10 may also include isolators
36 that
assist in damping vibrations applied to the heat shield
10 from the heat/acoustic
source
32. As illustrated in FIG. 5, the isolator
36 includes top
and bottom cold rolled steel washers
38,
40 crimped about a stainless
steel mesh
42 positioned about an outer periphery of a low bearing tube
44. Essentially, the isolator
36 is fastened to the heat shield
10
via grooves that may be formed in the inner portion
12 that interlocks with
the steel mesh
42. Once interlocked on the heat shield
10, the isolators
36 are positioned in an opposing relationship to the acoustic/heat source
32. According to one embodiment of the invention, the isolator
36
may include a diameter approximately equal to 20.0 mm and a height approximately
equal to 5.0 mm.
Referring now to FIGS. 6A-6H, a process for assembling the heat shield
10 is illustrated. First, as seen in FIG. 6A, the outer portion
14
is blanked to form a hemmed portion
46 for subsequent closing to form a
hemmed edge
48 (FIG.
6D). Then, as seen in FIGS. 6B and 6C, a blank
of steel or other suitable rigid material
20a is inserted into a
press or die
50 having a textured surfaces
52 corresponding to the
desired shape of the dimples
22. After inserting the steel blank
20a,
the press or die
50 is closed to form the deflecting portion
20 including
the dimples
22. Prior to forming the dimples
22, the steel blank
20a may include any desirable thickness, T
6, that ranges between
approximately 0.15 mm-0.40 mm. As stated above, after the press or die
50
is closed, the dimples
22 define the thickness, T
5, that may range
between 0.90 mm-1.50 mm.
Next, as seen in FIG. 6D, the insulating portion
18 is positioned over
the outer portion
14; the deflecting portion
20 is positioned over
the insulating portion
18; the insulating portion
16 is positioned
over the deflecting portion
20; and the inner portion
12 is positioned
over the insulating portion
16. After the portions
12,
14,
16,
18,
20 are properly positioned, the hemmed portion
46
is pre-closed, as see in FIG. 6D, so that the outer portion
14 may be subsequently
closed in a beading step to form the hemmed edge
48, as seen in FIGS. 6E
and 6F. Although shown in a partial side view, it is important to note that the
hemming process illustrated in FIGS. 6A-6F includes the hemmed structural edge
48 about the entire periphery of the heat shield
10 to fully secure
each portion
12,
16,
18,
20 stacked therein.
Then, if desired, heat shield
10 may be formed to a desired contour,
such as, for example, the contour of an exhaust manifold (FIG.
6G), and
subsequently stamped or punch to include passages
54 for fasteners, such
as bolts (FIG.
6H). Although steps illustrated in FIGS. 6B and 6C are directed
to the formation of the dimples
22, it is contemplated that the deflecting
portion
20 may be a preformed component, that is, if a wire mesh is implemented,
and the dimple formation steps illustrated in FIGS. 6B and 6C may be eliminated.
The heat shield
10 may include additional bracket attachments (not shown)
that comprise the same components of the heat shield
10. Essentially, the
bracket may be riveted to the heat shield
10 to provide a heat shield extension,
for other components close to the acoustic/heat source
32. As stated above,
if the acoustic/heat source
32 is an exhaust manifold, the bracket may shield
other automotive components from the manifold, such as a spark plug. In an automotive
application as explained above, the heat shield
10, may withstand thermal
temperatures of approximately 650° C. (1202° F.) for exhaust manifolds
that have operating temperatures as high as 900° C. (1652° F.). If the
inner portion
12, which provides the primary heat reflecting barrier, includes
nickel rather than aluminum, the heat shield
10 may withstand temperatures
higher than 650° C. (1202° F.). The heat shield
10 includes a
material formation and composition that includes strength characteristics, corrosion
resistance, and other user parameters. For example, the materials described above
provide resistance to corrosion as a result of constituents including: the elements,
salt, engine fluids, and high temperatures of the manifold.
It is to be understood that the above description is intended to be illustrative
and not limiting. Many embodiments will be apparent to those skilled in the art
upon reading the above description. The scope of the invention should be determined,
however, not with reference to the above description, but with reference to the
appended claims with full scope of equivalents to which such claims are entitled.
*
