U.S. patent application number 14/593361 was filed with the patent office on 2016-07-14 for noise attenuating member for noise attenuating units in engines.
This patent application is currently assigned to DAYCO IP HOLDINGS, LLC. The applicant listed for this patent is Rex Bravo, David E. Fletcher, Brian M. Graichen, Denis Vashuk. Invention is credited to Rex Bravo, David E. Fletcher, Brian M. Graichen, Denis Vashuk.
Application Number | 20160201531 14/593361 |
Document ID | / |
Family ID | 56234832 |
Filed Date | 2016-07-14 |
United States Patent
Application |
20160201531 |
Kind Code |
A1 |
Fletcher; David E. ; et
al. |
July 14, 2016 |
NOISE ATTENUATING MEMBER FOR NOISE ATTENUATING UNITS IN ENGINES
Abstract
Noise attenuating members for use in noise attenuating units for
engine systems are disclosed that include a core, having an
interior surface defining a hollow inner cavity and a plurality of
radial openings, and a porous material disposed about an exterior
surface of the core. The porous material may be a strip which is
engaged with the exterior of the core and wrapped around the core
to form a plurality of layers of porous material. A noise
attenuating unit is disclosed to include a housing, having an
internal cavity, first port, and second port, and an attenuating
member disposed within the internal cavity. A method of making a
noise attenuating member is disclosed that includes providing a
core having an hollow cavity and radial openings, providing a strip
of porous material, and wrapping the strip of porous material about
the core to form one or more layers.
Inventors: |
Fletcher; David E.; (Flint,
MI) ; Graichen; Brian M.; (Leonard, MI) ;
Vashuk; Denis; (Saint Clair Shores, MI) ; Bravo;
Rex; (Detroit, MI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Fletcher; David E.
Graichen; Brian M.
Vashuk; Denis
Bravo; Rex |
Flint
Leonard
Saint Clair Shores
Detroit |
MI
MI
MI
MI |
US
US
US
US |
|
|
Assignee: |
DAYCO IP HOLDINGS, LLC
Springfield
MO
|
Family ID: |
56234832 |
Appl. No.: |
14/593361 |
Filed: |
January 9, 2015 |
Current U.S.
Class: |
181/252 ;
29/896.2 |
Current CPC
Class: |
F01N 13/007 20130101;
F01N 1/085 20130101; F02M 35/1277 20130101; F01N 1/10 20130101;
F02M 35/1211 20130101; F02M 35/1272 20130101; F01N 1/082 20130101;
F02M 35/10229 20130101; F01N 3/22 20130101 |
International
Class: |
F01N 1/24 20060101
F01N001/24; F01N 13/18 20060101 F01N013/18 |
Claims
1. A noise attenuating member comprising: a core defining a hollow
cavity for fluid flow therethrough, the core being a hollow
cylindrical grid defining a plurality of radial openings; and a
porous material disposed about an exterior of the core; wherein
fluid flow through the hollow cavity and the radial openings passes
through the porous material.
2. The noise attenuating member of claim 1, wherein the porous
material comprises a plurality of layers of the porous material
disposed about the core.
3. The noise attenuating member of claim 2, wherein the plurality
of layers of porous material comprises a continuous strip thereof
wound about the exterior of the core.
4. The noise attenuating member of claim 3, wherein the continuous
strip of porous material has a first end folded over onto itself
for engagement with the exterior of the core.
5. The noise attenuating member of claim 1, wherein each of the
plurality of radial openings is larger than a pore size of the
porous material.
6. (canceled)
7. The noise attenuating member of claim 1 wherein the core further
comprises a plurality of protrusions extending outward from the
exterior of the core.
8. The noise attenuating member of claim 7, wherein each protrusion
includes one or more features that retain the porous material
against the exterior of the core.
9. The noise attenuating member of claim 1, wherein the porous
material comprises one or more of metal, carbon fiber, ceramic,
plastic, and glass.
10. The noise attenuating member of claim 9, wherein the porous
material is a wire, a wool, a matrix of woven particles, a matrix
of matted particles, a matrix of sintered particles, a woven
fabric, a matted fabric, a mesh, a sponge, or combinations
thereof.
11. The noise attenuating member of claim 9, wherein the porous
material comprises metal and is one or more of a metal wire mesh, a
metal wire wool, and a metal wire felt.
12. A noise attenuating unit connectable to become part of a fluid
flow path comprising: a housing defining an internal cavity and
having a first port and a second port, each connectable to a fluid
flow path and in fluid communication with one another through the
internal cavity; and an attenuating member seated in the internal
cavity of the housing within the flow of the fluid communication
between the first port and the second port and the fluid
communication between the first port and the second port includes
fluid flow through the attenuating member, the attenuating member
comprising: a core defining a hollow cavity for fluid flow
therethrough, the core being a hollow cylindrical grid defining a
plurality of radial openings; and a porous material disposed about
an exterior of the core; wherein fluid flow through the hollow
cavity and the radial openings passes through the porous
material.
13. The noise attenuating unit of claim 12, wherein the housing is
a two-part housing having a first housing portion and a second
housing portion.
14. The noise attenuating unit of claim 12, wherein the fluid flow
path from the first port to the second port travels axially through
the attenuating member.
15. the noise attenuating unit of claim 12, wherein the fluid flow
path from the first port to the second port travels through the
attenuating member from the hollow cavity radially outward through
the porous material.
16. The noise attenuating unit of claim 12, wherein the housing is
integrated with a Venturi apparatus for generating vacuum.
17. (canceled)
18. A method for making a noise attenuating member comprising:
providing a core defining a hollow cavity for fluid flow
therethrough and defining a plurality of radial openings, wherein
the core has a plurality of protrusions extending outward from the
exterior thereof; providing a strip of porous material, the strip
having a first end and a second end; engaging the porous material
with the protrusions to retain the porous material against the
core; and wrapping the strip of porous material about the core
beginning from the first end to form one or more lavers of porous
material thereabout.
19. A method for making a noise attenuating member comprising:
providing a core defining a hollow cavity for fluid flow
therethrough and defining a plurality of radial openings; providing
a strip of porous material, the strip having a first end and a
second end; folding the first end of the strip of porous material
over onto itself; and wrapping the strip of porous material about
the core beginning from the first end to form one or more layers of
porous material thereabout.
20. The method of claim 18, further comprising adjusting a tension
applied to the strip of porous material during wrapping to change
the density of the one or more layers of porous material wrapped
about the core.
21. The noise attenuating member of claim 1 wherein the plurality
of radial openings define a void space of at least 50% of a
theoretical exterior surface area of the core.
22. The noise attenuating member of claim 1 wherein each of the
plurality of radial openings has an area of at least 0.7 times a
cross-sectional area of the hollow cavity.
23. A noise attenuating member comprising: a core defining a hollow
cavity for fluid flow therethrough and defining a plurality of
radial openings, the core including a plurality of protrusions
extending outward from the exterior of the core; and a porous
material disposed about an exterior of the core; wherein fluid flow
through the hollow cavity and the radial openings passes through
the porous material.
Description
TECHNICAL FIELD
[0001] This application relates to noise attenuation in engine
systems such as internal combustion engines, more particularly to
the inclusion of a noise attenuating member in a housing configured
for insertion in a fluid flow path of an engine.
BACKGROUND
[0002] Engines, for example vehicle engines, often include
aspirators and/or check valves. Typically, the aspirators are used
to generate a vacuum that is lower than engine manifold vacuum by
inducing some of the engine air to travel through a venturi. The
aspirators may include check valves therein or the system may
include separate check valves. When the check valves are separate
they are typically included downstream between the source of vacuum
and the device using the vacuum.
[0003] During most operating conditions of an aspirator or check
valve the flow is classified as turbulent. This means that in
addition to the bulk motion of the air there are eddies
superimposed. These eddies are well known in the field of fluid
mechanics. Depending on the operating conditions the number,
physical size, and location of these eddies is continuously
varying. One result of these eddies being present on a transient
basis is that they generate pressure waves in the fluid. These
pressure waves are generated over a range of frequencies and
magnitudes. When these pressure waves travel through the connecting
holes to the devices using this vacuum, different natural
frequencies can become excited. These natural frequencies are
oscillations of either the air or the surrounding structure. If
these natural frequencies are in the audible range and of
sufficient magnitude then the turbulence generated noise can become
heard, either under the hood, and or in the passenger compartment.
Such noise is undesirable and new apparatus are needed to eliminate
or reduce the noise resulting from the turbulent air flow.
SUMMARY
[0004] In one aspect, a noise attenuating member is disclosed that
includes a core defining a hollow cavity for fluid flow
therethrough and a porous material disposed about an exterior of
the core. The core defines a plurality of radial openings. Fluid
flow through the hollow cavity and the radial openings passes
through the porous material, which dissipates turbulent eddies in
the fluid flow to attenuate noise caused by the fluid flow.
[0005] In another aspect, the porous material includes a plurality
of layers of the porous material disposed about the core. In one
embodiment, the plurality of layers of porous material includes a
continuous strip of porous material wound about the exterior of the
core. In another embodiment, the continuous strip of porous
material has a first end folded over onto itself for engagement
with the exterior of the core.
[0006] In another aspect, the core has a plurality of radial
openings that are larger than a pore size of the porous material.
In another aspect, the core is generally a hollow cylindrical grid.
In another aspect, the core includes a plurality of protrusions
extending outward from the exterior of the core. In one embodiment,
each of the protrusions includes one or more features that retain
the porous material against the exterior of the core.
[0007] In another aspect, the porous material includes one or more
of metal, ceramic, carbon fiber, plastic, and glass. The porous
material includes one or more of a wire, a wool, a matrix of woven
particles, a matrix of matted particles, a matrix of sintered
particles, a woven fabric, a matted fabric, a sponge, a mesh, or
combinations thereof. In one aspect, the porous material is metal
and is one or more of a metal wire mesh, a metal wire wool, and a
metal wire felt.
[0008] In another aspect, a noise attenuating unit connectable to
become part of a fluid flow path includes a housing defining an
internal cavity and having a first port and a second port, which
are both connectable to a fluid flow path and in fluid
communication with one another through the internal cavity. The
noise attenuating unit also includes an attenuating member seated
in the internal cavity of the housing within the flow of the fluid
communication between the first port and the second port. The fluid
communication between the first port and the second port includes
fluid flow through the attenuating member. The attenuating member
includes a core defining a hollow cavity for fluid flow
therethrough and defining a plurality of radial openings. The
attenuating member also includes a porous material disposed about
an exterior of the core such that fluid flow through the hollow
cavity and the radial openings passes through the porous
material.
[0009] In another aspect, the noise attenuating unit includes a
housing that is a two-part housing having a first housing portion
and a second housing portion. In another aspect, the fluid flow
path from the first port to the second port travels axially through
the attenuating member. In another aspect, the fluid flow path from
the first port to the second port travels through the attenuating
member from the hollow cavity radially outward through the porous
material. In another aspect, the housing of the noise attenuating
unit is integrated with a Venturi apparatus for generating
vacuum.
[0010] In another aspect, a method for making a noise attenuating
member is disclosed to include providing a core defining a hollow
cavity for fluid flow therethrough and defining a plurality of
radial openings; providing a strip of porous material, the strip
having a first end and a second end; and wrapping the strip of
porous material about the core, beginning from the first end to
form one or more layers of porous material thereabout. In another
aspect of the method, the core has a plurality of protrusions
extending outward from the exterior thereof, and wrapping the
porous material about the core includes engaging the porous
material with the protrusions to retain the porous material against
the core. In another aspect, the method includes folding the first
end of the strip of porous material over onto itself before
wrapping the strip of porous material about the core. In another
aspect, the method includes adjusting a tension applied to the
strip of porous material during wrapping/winding to change the
density of the one or more layers of porous material wrapped about
the core.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 is a front perspective view of a noise attenuation
unit connectable to become part of a fluid flow path.
[0012] FIG. 2 is a longitudinal, cross-sectional view of the noise
attenuation unit of FIG. 1.
[0013] FIG. 3 is a front, perspective view of one embodiment of a
noise attenuating member for use in the noise attenuation unit of
FIGS. 1-2.
[0014] FIG. 4 is a longitudinal, cross-sectional view of the noise
attenuating member of FIG. 3.
[0015] FIG. 5 is top plan view of the noise attenuating member of
FIG. 3.
[0016] FIG. 6 is a front perspective view of a core of the noise
attenuating member of FIG. 3.
[0017] FIG. 7 is a front elevation view of the core of FIG. 6.
[0018] FIG. 8 is top plan view of the core of FIG. 6.
[0019] FIG. 9 is a front perspective view of a strip of porous
material used to assemble one embodiment of a noise attenuating
member.
[0020] FIG. 10 is a front perspective view of the strip of porous
material of FIG. 9 with the first end folder over.
[0021] FIG. 11 is a front perspective view of the strip of porous
material of FIG. 9 being wound about a core.
DETAILED DESCRIPTION
[0022] The following detailed description will illustrate the
general principles of the invention, examples of which are
additionally illustrated in the accompanying drawings. In the
drawings, like reference numbers indicate identical or functionally
similar elements.
[0023] As used herein "fluid" means any liquid, suspension,
colloid, gas, plasma, or combinations thereof.
[0024] As used herein "radial" means in a direction generally
outward from the central portion of an object and does not imply
any particular shape, i.e., the shape is not limited to circular,
cylindrical, or spherical.
[0025] FIG. 1 is front perspective view of a noise attenuating
unit, generally identified by reference number 10, for use in an
engine, for example, in a vehicle's engine. The engine may be an
internal combustion engine, and the vehicle and or engine may
include a device requiring a vacuum. Check valves and or aspirators
are often connected to an internal combustion engine before the
engine throttle and after the engine throttle. The engine and all
its components and/or subsystems are not shown in the figures and
it is understood that the engine components and/or subsystems may
include any components common to an internal combustion engine. The
brake boost system is one example of a subsystem that can be
connected to an aspirator and/or check valves. In another
embodiment, any one of a fuel vapor purge systems, exhaust gas
recirculation system, a crankcase ventilation system and/or a
vacuum amplifier may be connected to an aspirator and/or check
valve. The fluid flow within the aspirator and/or check valves, in
particular when a Venturi portion is included, is generally
classified as turbulent. This means that in addition to the bulk
motion of the fluid flow, such as air or exhaust gases, there are
pressure waves traveling through the assembly and different natural
frequencies can become excited thereby resulting in turbulence
generated noise. The noise attenuation unit 10 disclosed herein
attenuates such turbulence generated noise.
[0026] Referring to FIGS. 1 and 2, the noise attenuation unit 10
may be disposed in, and thereby becomes part of, any fluid flow
path(s) within an engine in need of noise attenuation, and is
typically positioned in the flow path downstream of the source of
the noise. The noise attenuating unit 10 includes a housing 14
defining an internal cavity 16 enclosing a noise attenuating member
20 therein. The noise attenuating member 20 typically fits
securely, at least axially, within the internal cavity 16
sandwiched between a first seat 26 and a second seat 28. As
illustrated in FIG. 2, the noise attenuating member 20 has a
generally close fit with the interior side wall 17 of the cavity
16, but such a construction is not required. In another embodiment
(not shown), there may be a gap defined between the interior side
wall 17 of the cavity 16 and an outermost radial surface 78 of the
noise attenuating member 20 defined by the porous material 42. The
housing defines a first port 22 in fluid communication with the
internal cavity 16 and a second port 24 in fluid communication with
the internal cavity 16. The exterior surfaces of the housing 14
that define the first and second ports 22, 24 both include fitting
features 32, 34 for connecting the noise attenuating unit 10 into a
fluid flow path of the engine. For example, in one embodiment both
fitting features 32, 34 are insertable into a hose or conduit and
the fitting features provide a secure fluid-tight connection
thereto.
[0027] The housing 14, as shown in FIG. 2, may be a multiple piece
housing with a plurality of pieces connected together with a
fluid-tight seal. The multiple pieces may include a first housing
portion 36 that includes the first port 22 and a male end 23 and a
second housing portion 38 that includes the second port 24 and a
female end 25. The male end 23 is received in the female end 25
with a sealing member 18 therebetween to provide a fluid-tight seal
between the portions 36, 38. In other embodiments, the first
housing portion 36 and the second housing portion 38 have a
container and cap-type construction.
[0028] In the embodiment of FIG. 2, the first port 22 and the
second port 24 are positioned opposite one another to define a
generally linear flow path through the noise attenuation unit 10,
but is not limited to this configuration. In another embodiment,
the first and second ports 22, 24 may be positioned relative to one
another at an angle of less than 180 degrees. In one embodiment,
the second port 24 may be positioned generally 90 degrees relative
to the first port 22 such that the fluid flow passes through the
noise attenuating member 20 from an inner cavity of a core of the
noise attenuating member 20 radially outward through the porous
material disposed about the core of the noise attenuating member
20.
[0029] Referring again to FIG. 2, the noise attenuating member 20
is dimensioned for a tight fit within the housing thereby the fluid
flow through the internal cavity 16 is only available through the
noise attenuating member 20 itself and any bores it may include.
The noise attenuating member 20 is porous such that fluid flow
through the unit 10 is restricted the least amount possible, but
sound (turbulence generated noise) is attenuated. Additional
examples of noise attenuating units having noise attenuating
members can be found in co-pending U.S. patent application Ser. No.
14/565,075, filed Dec. 9, 2014, which is incorporated herein by
reference in its entirety. The noise attenuating member of the
present disclosure may also be incorporated directly into a check
valve assembly or vacuum producing assembly. Examples of check
valve and vacuum producing assemblies that can include a noise
attenuating member are included in co-pending U.S. patent
application Ser. No. 14/509,612, filed Oct. 8, 2014, which is
incorporated herein by reference in its entirety.
[0030] Referring now to FIGS. 3-5, the noise attenuating member 20
includes a core 40 and a porous material 42 disposed about the core
40. In the embodiment shown in FIGS. 3-5, the core 40 is hollow and
includes an inner surface 46 defining an inner hollow cavity 48,
and an exterior surface 50 facing outward from the core 40. The
core 40 has a plurality of radial openings 52 to allow for fluid to
flow radially outward from the inner cavity 48 of the core 40,
through the radial openings 52, and into and through the porous
material 42 disposed about the exterior surface 50 of the core 40.
The porous material 42 includes a plurality of pores (not shown) to
allow fluid to pass into and through the porous material 42. The
noise attenuating member 20 may have a first end 54 and a second
end 56, relative to an axial direction of the noise attenuating
member 20. For fluid flow directed parallel to a center axis 58 of
the noise attenuating member 20, the fluid flow may be in a
direction from the first end 54 to the second end 56 or in a
direction from the second end 56 to the first end 54. For radial
fluid flow through the noise attenuating member 20, the fluid flow
may flow into the inner cavity 48 from either or both of the first
end 54 and second end 56 and then flow radially outward through the
radial openings 52 and into/through the porous material 42. In one
embodiment (not shown), the core 40 may be solid and may have the
porous material 42 disposed about the exterior surface 50 of the
core 40 such that fluid flow through the noise attenuating member
20 parallel to a center axis 58 of the noise attenuating member 20
is all directed through the porous material.
[0031] Referring now to FIGS. 6-8, the core 40 of the noise
attenuating member 20 is illustrated. The interior surface 46 and
the exterior surface 50 of the core 40 have a general
cross-sectional shape, relative to the center axis 58 of the noise
attenuating member 20, that may be any convenient shape, including,
but not limited to, circular, square, rectangular, polygonal,
multi-faceted, or other shape. The interior surface 46 and the
exterior surface 50 may have similar cross-sectional shapes, or the
cross-sectional shapes of the surfaces 46, 50 may be different. In
one embodiment shown in FIGS. 6-8, the core 40, notwithstanding the
plurality of radial openings 52, may be an annular cylinder, for
which the cross-sectional shape of both the interior surface 46 and
exterior surface 50 are generally circular. In one embodiment, the
cross-sectional shapes (notwithstanding the radial openings 52) of
the interior surface 46 and the exterior surface 50 may change
along a length L of the core 40. A width W and the length L of the
core 40 may be selected based on the configuration and dimensions
of the housing 14 of the noise attenuation unit 10 into which the
noise attenuating member 20 is to be incorporated.
[0032] The core 40 may be constructed of any suitable material,
including, but not limited to, metal, plastic, ceramic, carbon
fiber, glass, fiberglass, wood, rubber, or combinations thereof,
and may have one or more surface coatings to prevent deterioration
of the core 40. In one embodiment, the core 40 is constructed of a
rigid material. In one embodiment, the material of the core 40 is
not degraded or deteriorated by operating conditions of the fluid
system into which it is installed, specifically the elevated
temperatures and vibrations that occur in an engine. In one
embodiment, the core material is selected to withstand elevated
temperatures. In another embodiment, the core material is selected
to resist corrosion from moisture and other corrosive
compounds.
[0033] The radial openings 52 through the core 40 may be any
convenient shape, including, but not limited to, circular, square,
rectangular, polygonal, multi-faceted, or other shape. The radial
openings 52 may all have the same shape and size, or one or more of
the radial openings 52 may have a shape and/or size that is
different from the other radial openings 52. In the embodiment
shown in FIG. 6, the radial openings 52 may have the same general
shape, which is generally rectangular with rounded corners. In
other embodiments, the radial openings 52 may be generally circular
in cross-section. The radial openings 52 may be any convenient size
and may be selected to increase exposure of the fluid flow to the
porous material 42 as the fluid flows through the inner cavity 48.
The radial openings 52 are larger in size than the pores of the
porous material 42 disposed about the core 40, but are not so large
that the core 40 is deformed into the inner cavity 48 by a weight
or force exerted on the core 40 by the porous material 42. In one
embodiment, each of the radial openings 52 may have an area in a
range of about 0.7 to about 1.5 times a cross-sectional area of the
inner cavity 48. In another embodiment, each of the radial openings
52 may be in a range of about 0.9 to about 1.3 times the
cross-sectional area of the inner cavity 48. In another embodiment,
each of the radial openings 52 may have an area that is in a range
of about 1.0 to about 1.2 times the cross-sectional area of the
inner cavity 48.
[0034] The radial openings 52 may be distributed along the entire
length L of the core, from the first end 54 to the second end 56 of
the noise attenuating member 20, and may be distributed angularly
along an outer cross-sectional circumference 60 of the core 40. In
the embodiment of FIGS. 6 and 7, the radial openings 52 are
distributed evenly throughout the core 40 in both the axial and
angular directions. In one embodiment, the radial openings 52 may
not be evenly spaced but may be positioned to manipulate the flow
dynamics through the noise attenuating member 20. In the embodiment
illustrated in FIG. 6, the core 40 has a total of 12 radial
openings 52 arranged in three sections of four radial openings 52
that are distributed evenly about the outer circumference of the
core 40. The three sections are axial sections with respect to the
axial length L of the core 40. The four radial openings 52 in each
section are aligned radially about the outer circumference of the
core 40, and the radial openings 52 are also aligned with the
radial openings 52 of an adjacent section. In one embodiment (not
shown), the radial openings 52 may be offset or staggered with
respect to either or both of radial openings 52 of the same section
or different sections. In other embodiments, the core 40 may have
more or less than three sections of radial openings 52 and may have
more or less than four radial openings 52 per section.
[0035] A total void space of the exterior surface 50 of the core 40
may be defined as the sum of the cross-sectional areas of the
radial openings 52, and a theoretical outer surface area of the
core 40 may be defined as the surface area of the exterior surface
50 of the core 40 without the radial openings 52. In one
embodiment, the total void space represented by the radial openings
52 may be in a range of about 50% to about 95% of the theoretical
exterior surface area of the core 40. In another embodiment, the
total void space represented by the plurality of radial openings 52
may be in a range of about 60% to about 90% of the theoretical
exterior surface area of the core 40. In another embodiment, the
total void space may be in a range of about 70% to about 80% of the
theoretical exterior surface area of the core 40. In the embodiment
illustrated in FIG. 6, the total void space is about 75% of the
theoretical exterior surface area of the core 40. In one
embodiment, the core 40 may be a support structure resembling a
hollow cylindrical grid/framework. In another embodiment, the core
40 may be a hollow cylindrical grid made up of wall segments
connected or coupled together to define the plurality of radial
openings 52. The core 40 may be a cylindrical lattice of integrated
wall portions defining the plurality of openings 52. In one
embodiment, the core 40 may include a plurality of pieces that are
coupled together or engaged to make the core 40.
[0036] Still referring to FIGS. 6-8, the core 40 may have a
plurality of protrusions 62 extending radially outward from the
exterior surface 50 of the core 40. Each of the protrusions 62 may
include a feature 64 (or retaining feature), as shown in FIG. 8,
that retains the porous material 42 against the exterior 50 of the
core 40. Examples of the retaining feature 64 include, but are not
limited to, barbs, notches, ribs, textured surfaces, other
protruding features, or combinations thereof. In one embodiment,
the feature 64 includes one or more barbs that catch on the porous
material 42 coupling it to the exterior surface 50 of the core 40.
The protrusions 62 may be distributed along the entire exterior 50
of the core 40, the distribution being both axial and angular. In
one embodiment, the protrusions 62 may be concentrated in a
specified region of the exterior surface 50 of the core 40, such as
a region where the porous material 42 is first attached prior to
being wound around the core 40.
[0037] As shown in FIGS. 6-8, the core 40 has end surfaces 68
facing generally in opposing axial directions and positioned at the
first end 54 and second end 56 of the noise attenuating member 20.
One or both of the end surfaces 68 of the core 40 may have one or
more engagement features 66 for engagement of the core 40 with a
machine during one or more assembly operations. In one embodiment,
the engagement features 66 may include one or more shoulders 67
against which a drive surface of a drive mechanism may engage to
rotate the core 40 during assembly operations. In another
embodiment, the engagement features 66 may be one or more tabs,
pins, or other protrusions that are received in a drive mechanism
to engage the drive mechanism with the core 40 for rotation
therewith during assembly operations. In one embodiment, more than
one type of engagement feature 66 may be used for engagement with a
drive mechanism.
[0038] Referring back to FIGS. 3-5, the porous material 42 disposed
about the core 40 may have pores (not shown) with a pore size that
is less than the radial openings 52 in the core 40, but large
enough to not unduly restrict or interfere with fluid flow such as,
for example, air flow through the system. The pores may be a
network of hollow channels in a porous material 42, such as the
channels propagating through a sponge material, or may also be an
interconnected matrix of void spaces extending through the porous
material 42, such as the void spaces between fibers of a woven
fabric or between layers of a wire mesh. The porous material 42 can
be made from a variety of materials including, but not limited to,
metals, plastics, ceramics, glass, or combinations thereof. The
porous material 42 may be a wire, a wool, a matrix of woven
particles, a matrix of matted particles, a matrix of sintered
particles, a woven fabric, a matted fabric, a mesh, a sponge, or
combinations thereof. Porous material 42 made from metals include,
but are not limited to, metal wire mesh, metal wire wool, metal
wire felt, or combinations thereof. In one embodiment, the porous
material 42 is a wire mesh. In another embodiment, the porous
material 42 may be a woven plastic or nylon fabric. The porous
character of the sound attenuating member 20 causes the noise
pressure waves propagating through the fluid to attenuate by
interfering with themselves. In one embodiment, the porous material
42 is not harmed (does not deteriorate) by operating temperatures
of an engine based on placement of the noise attenuating member 20
in the engine system. Additionally, the porous material 42 is not
harmed by the vibrations experienced during operating conditions of
the engine.
[0039] The porous material 42 may be formed as a plurality of
layers of porous material 42 wound around the core 40. Referring
now to FIGS. 9-11, the porous material 42 may be a continuous strip
70 (strip) of porous material having a first end 72 and a second
end 74. The first end 72 may be coupled to the exterior 50 of the
core 40, and the strip 70 may be wound around the exterior 50 of
the core 40 until the porous material 42 reaches a specified
thickness, which may depend upon the geometry of the noise
attenuating unit 10 into which the noise attenuating member 20 is
to be incorporated. In one embodiment, the first end 72 of the
strip 70 may be engaged with the protrusions 62 extending from the
exterior 50 of the core 40 such that the protrusions 62 extend
through the strip 70 of porous material to hold the strip 70 in
engagement with the core 40. In one embodiment, the first end 72 of
the strip 70 may be folded over onto itself so that a portion of
the strip 70 that engages with the core 40/protrusions 62 has two
layers of porous material, which may act to improve or strengthen
the engagement of the strip 70 with the core 40. Tension on the
strip 70 during the winding process may change the density of the
porous material 42 disposed about the core 40. More tension on the
strip 70 results in denser layers of porous material 42, and
likewise, less tension results in less dense layers of porous
material 42. Following winding, the second end 74 of the strip 70
is then secured to an outermost layer 76 of porous material 42, or
other structure, to keep the strip 70 from unwinding from the core
40. The second end 74 may be welded, fastened, adhered, taped or
otherwise attached to the outermost layer 76 of porous material 42.
In one embodiment, the second end 74 is welded to the outermost
layer 76 of porous material 42.
[0040] Still referring to FIGS. 9-11, a method of making a noise
attenuating member 20 includes providing a core 40 having an
interior surface 46 that defines an inner hollow cavity 48 for
fluid flow therethrough, providing a strip 70 of porous material 42
having a first end 72 and a second end 74, and wrapping the strip
70 of porous material 42 about the core 40 beginning from the first
end 72 to form one or more layers of porous material 42 disposed
about the core 40. The core 40 is provided having a plurality of
radial openings 52 extending therethrough. The axial end surfaces
68 of the core 40 can have engagement features 66 to allow for
engagement of the core 40 with a machine capable of rotating the
core 40 during the assembly operations. In some embodiments, the
method of making a noise attenuating member 20 includes the steps
of engaging the core 40 with a machine capable of rotating the core
40 about an axis. In some embodiments, the center axis 58 is the
center of rotation for the core 40. As shown in FIG. 10, the method
may include folding over the first end 72 of the strip 70 so that
the first end 72 of the strip 70 has two layers of material. The
method also includes engaging the first end 72 of the porous
material 42 with the exterior surface 50 of the core 40. In one
embodiment, the first end 72 of the strip 70 may be engaged with
the protrusions 62, and the retaining features 64 thereon, securing
the first end 72 of the strip 70 to the exterior surface 50 of the
core 40. In other embodiments, the first end 72 of the strip 70 may
be curled over, crimped tight to, or crimp welded to the exterior
50 of the core 40.
[0041] Referring to FIG. 11, the core 40 may be rotated to wind the
strip 70 of porous material 42 about the core 40 to form one or
more layers of porous material 42 disposed about the core 40. In
some embodiments, the method may further include applying tension
to the strip 70 and adjusting the tension to achieve a specified
density of the porous material 42 wound around the core 20. Upon
winding the strip 70 about the core 40, the second end 74 of the
strip 70 may be secured to an outermost layer 76 of porous material
42, such as through welding, sintering, fastening, or adhering, for
example. In some embodiments, the core 40 may have multiple pieces
such that assembling the core 40 happens prior to engaging the
first end 72 of the strip 70 with the exterior surface 50.
[0042] Referring back to FIG. 2, the assembled noise attenuating
member 20 may be installed in a noise attenuation unit 10, which
may be incorporated into a fluid flow system requiring sound
attenuation. In operation, fluid flows into the noise attenuation
unit 10 through the first port 22 and through the noise attenuating
member 20. Some of the fluid flows directly into the porous
material 42, where the flow through the plurality of pores disrupts
the turbulent flow eddies entering the noise attenuation unit 10.
In the inner hollow cavity 48 of the core 40, the turbulent nature
of the flow also causes fluid to flow radially through the radial
openings 52 in the core 40 and into the porous material 42, which
further dissipates the turbulent eddies that give rise to sound
vibrations. The fluid flow exits from the porous material 42 and
out of the noise attenuation unit 10 through the second port
24.
[0043] The noise attenuating member 20 of the present application
may produce repeatable attenuation with minimal interference with
fluid flow through the system. The core 40 provides a support for
the porous material 42 to keep the porous material 42 in place
within the noise attenuating unit 10 into which it is installed.
The hollow internal cavity 48 of the core 40 may provide a straight
flow path through the noise attenuating member 20, which may reduce
the pressure drop across the noise attenuating member 20 compared
to existing noise attenuating devices. The core 40 provides support
for the porous material 42 to keep the porous material 42 from
being drawn into the flow path and interfering with the fluid flow
through the noise attenuating unit 10. Providing a means of
engagement of the strip 70 of porous material 42 with the core 40
may also reduce the welding that must be performed on a noise
attenuating member 20 and thus maintain fluid flow through the
noise attenuating member.
[0044] Having described the invention in detail and by reference to
specific embodiments thereof, it will be apparent that numerous
modifications and variations are possible without departing from
the spirit of the invention as defined by the following claims.
* * * * *