Note: Descriptions are shown in the official language in which they were submitted.
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TITLE
A E1GHT-WEIGHT AIR DUCT FOR VENTILATION, AIR CONDITIONING AND
HEATING FOR USE IN A VEHICLE AND A METHOD OF MANUFACTURING SAME
FIELD OF THE DISCLOSURE AND BACKGROUND
Air ducts in vehicles such as automobiles arc typically injection-moulded with
tale-filled
polypropylene or blow moulded with unfilled polyethylene. The prior art air
ducts arc typically
made of solid plastic walls with a thickness of between 1.0 to 2.0 mm.
However, in order to
achieve higher fuel economy for vehicles, weight reduction of such plastic
parts is desirable.
Recently, a few processes to manufacture light-weight air duets for the
automotive industry have
= appeared on the market. Some arc: foaming blow-moulding [US Patent iiLlS
8,448,671 B2] of a
mixed resin which includes such polymers as a polypropylene-based resin for
foaming and
styrene-ba.sed thermoplastic elastomers; twin sheet foam thetTrioforming, and
felt compression
processing (compression moulding, or the like). The industry is continually
working to lower the
material density and to reduce wall thickness of air ducts to reduce air duct
weight. There is
therefore a need for an air duct that combines weight reduction, preferably
>50% weight
reduction compared to prior art air ducts, improved structural strength and at
an acceptable cost.
Automotive manufacturers look for many characteristics and specifications in
an air duct. Some
are mandatory to meet automotive safety requirements such as, but not limited
to, chemical
resistance, heat resistance, whereas others are preferred such as, but not
limited to, acoustic
attenuation and insulation of the air duct, and acceptable cost of
manufacturing the air duct_
Methods to manufacture articles of polypropylene resin pre-expanded foam beads
arc known in
the an. Steam chest moulding is a prior art process used to manufacture light
weight plastic parts.
In some instances, expanded foam beads are injected into a custom designed
steam chest mould,
where individual beads are fused together under steam, heat and pressure. When
released from
the mould, the solid moulded object has features as per the custom designed
steam chest mould
to serve the desired application.
Other moulding methods for particles or beads made of various plastics capable
of melting at
low temperature are known. For example, particle moulding processing has been
used to form
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automobile vehicles passenger seats (from expanded polypropylene beads), spare
tire trays and
tool boxes in a vehicle trunk, sun visors, as well as vehicle bumper energy
absorbing systems
that include moulded foam and at least one integral reinforcing member.
Typically, in the prior
art, all are examples of parts designed and fabricated in single pieces. There
is therefore also a
need for a method allowing for the design, the fabrication and the assembly of
the formed air
duct sections of polypropylene resin pre-expanded foam beads via steam chest
moulding to form
an air duct.
Finally, there is a need for a light weight air duct that is mechanically
resistant (having good
structural strength), and which exhibits improved acoustic attenuation and
insulation properties,
while keeping the cost of the duct at an acceptable level.
SUMMARY
According to one aspect, there is provided a method of fabricating a part for
use in an air duct,
formed of pre-expanded foam beads, preferably an air duct part, preferably for
a vehicle, more
preferably for an automotive vehicle, said method comprising the steps of:
i) injecting pre-expanded foam beads into at least one mould having a
shape of a part for
use in an air duct; preferably an air duct section part;
ii) injecting steam into the at least one mould for a period of time
sufficient for the pre-
expanded foam beads to partially melt and fuse together;
iii) cooling the at least one mould; preferably by allowing said at least
one mould to cool,
more preferably by introducing cooling to said at least mould; and
iv) removing the part from said at least one mould.
In one embodiment, said pre-expanded foam beads enter in direct contact with
at least one mould
surface, preferably a plurality of mould surfaces of the at least one mould
and melt during said
step of injecting steam into the at least one mould, formint,, at least one
part wall and wall
surface, preferably one air duct part wall surface, on each of said at least
one mould surface,
preferably on each of said mould surfaces, preferably said air duct part wall
surface is a thin
layer of plastic, preferably with air gaps between said pre-expanded foam
beads forming said
wall surfaces. In one embodiment said formed wall surfaces are substantially
air tight. In
another embodiment said formed wall surfaces are substantially non-porous. In
another
embodiment, said formed wall surfaces are substantially porous.
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in another embodiment, said pre-expanded foam beads arc selected from a group
consisting of
expanded polypropylene, expanded polyethylene, expanded polystyrene, expanded
thermoplastic
urethane and combinations thereof.
In another embodiment, prior to said injecting steam, each of said pre-
expanded foam beads is of
a particle size with an average diameter range between about 1.5 ram and about
8 nirm
In another embodiment, each of said pre-expanded foam beads has a spherical
diameter between
about 1.5 mm and about 6 mm, prior to step ii.
In another embodiment, each of said pm-expanded foam beads has a spherical
diameter between
about 6 nun and about 8 mm, prior to step ii.
In another embodiment, each of said pre-expanded foam beads has a non-
spherical diameter
between about 1.5 mm and about 8mm, prior to said step ii, and said pre-
expanded foam beads
comprise non-spherical shapes.
In another embodiment, each of said pre-expanded foam beads may be of a shape
including
spherical, ellipsoidal, cylindrical, rectangular, cubic, other polyhedral
shapes, irregular shapes
and combinations thereof.
In another embodiment, each of said pre-expanded foam beads has an average
density, prior to
said injecting step of said pre-expanded foam beads into at least one mould,
between about I
pound per cubic feet to about 12 pounds per cubic feet.
In another embodiment, said at least one wall of the air duct has a thickness
of at least about 0,6
mm,
According to another aspect, there is provided an air duct assembly method
whereas at least one
of said air duct parts described herein, made by steam chest moulding, is
fastened together with
at least another air duct part, preferably made by steam chest moulding,
forming an air duct,
preferably fastened together forming an air duct with at least one
substantially air tight wall,
more preferably forming an air duct with substantially air tight walls. In
another embodiment,
forming an air duct with at least one porous wall, preferably a plurality of
porous walls. In one
embodiment, said air duct parts are fastened together by a fastening method
selected from the
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group consisting of pressure-snapping geometrically engaging surfaces,
welding, gluing,
brackets, screwing, bolting and combinations thereof
In one embodiment the produced air duct may serve for at least one of:
i) a ventilation, heating, cooling (air-conditioning) system and
combinations thereof, for a
vehicle cabin;
ii) cooling batteries;
iii) cooling brakes; and
iv) an air induction system of a vehicle, such as an automotive vehicle, a
truck, a train, a
bus, a recreational vehicle and an airplane.
According to yet another embodiment, there is provided an air duct assembly
method, said
method comprising fastening together at least one section of an air duct
manufactured as
described herein to at least another section of an air duct forming an air
duct with a substantially
air-tight wall, using a fastening method selected from the group consisting of
pressure-snapping
geometrically engaging surfaces, welding, gluing, installing brackets,
screwing, bolting and
combinations thereof.
According to yet another embodiment, there is provided an air duct assembly
method, said
method comprising fastening together at least one section of an air duct
manufactured as
described herein using porous pre-expanded foam beads, resulting in an air
duet section with a
porous wall, to another air duct section forming an air duct, using a
fastening method selected
from the group consisting of pressure-snapping geometrically engaging
surfaces, welding,
installing brackets, screwing, bolting and combinations thereof.
According to yet another aspect, there is provided an air duct part, whenever
produced by the
method described herein.
According to yet another aspect, there is provided an air duct, whenever
produced by the method
described herein.
BRIEF DESCRIPTION OF THE FIGURES
Figure 1 depicts the manufacturing process flow chart of the fabrication of a
section of an air
duet according to one embodiment.
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Figure 2 depicts two sections of an air duct according to Example l which is
according to an
embodiment, comprising a lower section and an upper section of an air duct
moulded separately.
Figure 3 depicts the air duct sections of Figure 2, after assembly of the
lower section with the
upper section of an air duct and installation of additional components and
their specific location.
Figure 4 depicts two sections of an air duct according to Example 2 which is
according to an
embodiment, comprising a lower section and an upper section of an air duct
which are moulded
separately.
Figure 5 depicts the air duct of Figure 4, after assembly of the lower section
with the upper
section of an air duct.
Figure 6 depicts two sections of an air duct according to Example 3 with
components according
to an embodiment, comprising a lower section and an upper section of an air
duct which are
moulded separately.
Figure 7 depicts the air duct of Figure 6, after assembly of the lower section
with the upper
section of an air duct and installation of additional components.
Figure 8 depicts two sections of an air duct of Example 4 with components
according to an
embodiment, comprising a lower section and an upper section of an air duct
which arc moulded
separately, whereas the lower section further includes a protrusion to assist
in the positioning of
the air duct cormctly in a vehicle and reducing, preferably removing the need
of polyurethane
insulation shims.
Figure 9 depicts the air duct of Figure 8, after assembly of the lower section
with the upper
section of an air duct.
Figure 10 depicts two sections of an air duct of Example 5 whit components
according to an
embodiment, comprising a lower section and an upper section of an air duct
which are moulded
separately.
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Figure II depicts the air duct of Figure 10, after assembly of thc lower
section with the upper
section of an air duct.
Figure 12 depicts the air duct of Figure 11, with additional air ducts to
bring air from the air
-- conditioning/heating unit to the car passenger cabin through the instrument
panel.
Figure 13 depicts the push pin of Figures 2, 3, 6 & 7.
Figure 14 depicts the transmission loss chart of Example I.
DETAILED DESCRIPTION
1.0
Referring now to Figure I, there is illustrated a process flow diagram of a
manufacturing
sequence used to produce at least one section of an air duet in accordance
with one embodiment
further described in the detailed description herein.
-- The purpose of this manufacturing sequence is to produce, by steam chest
moulding, at least one
section of a desired air duct and then, assemble air duct sections together to
form an air duct.
In one embodiment, the manufacturing sequence comprises the steps of: (I) pre-
closing the
mould cavity; (2) filling the mould cavity with the pre-expanded foam beads as
described
-- hereunder; (3) completely closing the mould cavity; (4) introducing steam,
preferably pulsing
steam into the mould cavity to melt and fuse the beads together: (5) cooling,
preferably by
pulsing a cooling mist into the mould cavity, preferably directly among the
melted and fused
beads; (6) opening the mould and; (7) and removing the melted and fused beads
shaped in a
section of an air duct from the mould cavity.
In some embodiments, at least one section of an air duct made by steps 1 to 7
above, is
assembled together in a subsequent step (5) with another section of an air
duct forming an air
duet which includes a channel allowing air to move from an inlet of the air
duct, through the
channel of the air duct and out through the outlet of the air duct.
According to one embodiment, the moulding system used herein is a steam chest
moulding
system. A steam chest moulding system comprises a shape moulding machine, a
steam boiler
and accumulator, a water cooling chiller and a compressed air aectunulator.
Such systems are
widely available in the plastics industry. The present description is
illustrative in maimer and is
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to be understood that the terminology used herein is intended to be
illustrative rather than in a
limiting sense.
The shape moulding machine comprises a mould (preferably made of metal)
comprising at least
two mould parts (or two mould cavities) (one of the two mould parts is also
called the movable
cavity side and the other mould part is called the stationary cavity side);
the interior surfaces of
each mould have at least one core vent, preferably a plurality of core vents;
at least one steam
nozzle, preferably a plurality of' steam nozzles; at least one tilling
injector, preferably a plurality
of filling injectors; and at least one ejector, preferably a plurality of
ejectors mounted on a back
1.0 plate in a manner as will be apparent to a person skilled in the art.
Each of such cavities may
have a plurality of removable cores to allow opening of the mould and removal
of the moulded
section of the air duct upon completion of the steam chest injection mould
process. Some
sections of the air duct may be inanufa.ctured using; a single mould having a
plurality of cavities.
For example, the upper and lower section of an air duet may be moulded side by
side in a dual-
cavity mould.
The shape of an air duct section is designed as per steam chest moulding
specifications (one
preferred process limitation is the draft angle) and vehicle specifications
(location, spacing,
routing, technical specifications), to form an air duct. To be able to form
the final air duct, at
least two sections of an air duct, preferably multi-sections of air duct parts
are typically required
to be assembled together. In some embodiments, the air duct section has a wall
thickness in the
range of from about 2 mm to about 80 mm. In one embodiment, each section of
the air duct has a
wall thickness of 6 mm. In a preferred embodiment, the air duct section has a
wall thickness of
at least 0.6 mm based on the size of the beads used, although thinner walls
are possible if smaller
beads are used.
Design of the air duct may include an improvement to wall stiffness (ribs,
thickness), increased
insulation characteristics (extra wall thickness) or other wanted
characteristics in a vehicle
(weight reduction, increased energy absorption, sealing between two air
ducts). The design may
also include features such as at least one quarter wave resonator or the like,
at least one
Helmholtz resonator or the like, and at least one smooth radius to reduce air
turbulence
throughout the air duet, such as a smooth radius at an elbow (or a plurality
thereof) or the like to
improve acoustic properties of the air duct. The design may also be selected
according to the
surrounding environment of the at least one selected area of the air duct
and/or to accommodate
other components, such as wires, metal brackets, or the like.
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installation tabs and mounting holes may also be designed in the wall of the
air duct section to
facilitate installation of the air duct. A tab may be moulded into the wall
structure of the air duct
section or may be added after the moulding operation with a method selected
from the group
consisting of pressure-snapping geometrically engaging surfaces, welding,
gluing, installing
brackets, screws, bolts and combinations thereof When the tab is added after
the moulding
operation, the tab may be made of metal, plastic and combinations thereof,
although any suitable
material may be used. Mounting holes on the air duct are preferred to be of
sufficient diameter
to facilitate push-pin installation. Preferably the material surrounding
the mounting hole is
sufficient to reduce any tearing proximate the mounting hole.
Referring still to Figure 1, one example of the preferred embodiment comprises
the following,
steps:
The first step is to partially close the mould. In this embodiment, the mould
has a "telescope"
built into it. Telescope is a term known to a person of ordinary skill in the
art of steam chest
moulding and is an extra metal depth that has zero and/or proximate zero
degrees of draft, at all
parting line surfaces. It is typically around 25min deep. This will allow the
mould to be opened
upon the initial filling step.
In one embodiment, a reinforcement insert may be pre-installed in the mould
cavity in either the
movable cavity or stationary cavity or both. The insert may be made of any
suitable material
preferably metal or plastic, or both. Installing the insert in the mould
before the injection step
creates a mechanical and chemical bond between the insert and the pre-expanded
foam beads as
an integrated final piece. In one embodiment, the reinforcement insert serves
to increase the
stiffness of installation points of the air duct part.
In the second step, pre-expanded foam beads are injected into the mould. Due
to the telescope
formed in the mould, extra foam beads are injected into the mould tool. The
pre-expanded. foam
beads may have a density from about 1 pound per cubic foot to about 15 pounds
per cubic foot
prior to the injecting step, preferably from about I to 12 pounds per cubic
foot. In general, a
lower density of the pre-expanded foam beads results in a lower density of the
air duct section
moulded from the beads.
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Filling injectors supply pressurized pre-expanded foam heads from a filling
tank into the mould
cavity. Filling of the mould cavity occurs because of a pressure gradient
between the filling
device and the interior of the mould itself, the latter being at a lower
pressure then the filling
injector pressure. The pressure within the mould cavity is increased by
filling the cavity with
= beads, but may also be increased by closing the mould over the beads (next
step). Both methods
allow a certain control over the density of the moulding material and allow
for an increase in the
strength (such as stiffness).
The pre-expanded foam beads used in steam chest moulding may have a large
range of shapes
including spherical, ellipsoidal, cylindrical, rectangular, cubic, other
polyhedral shapes as well as
irregular or other shapes. The pre-expanded foam beads may have imperfections
and
irregularities, such as dents, bumps, imperfectly aligned edges, corners or
sides, and so forth.
When non-spherical pre-expanded foam beads are used, for example ellipsoidal
beads, the
largest major diameter of a cross-section taken perpendicular to the
longitudinal axis of the
ellipsoid is defined as the diameter of the pre-expanded foam beads. In a
preferred embodiment
particular preference is given to heads of a spherical shape.
Each of the pre-expanded foam beads may have a diameter of from about 1.5 mm
to about 8 mm,
preferably from about 3 mm to about 6 mm. Each of the pre-expanded foam beads
preferably
have a compact outer skin. Here, reference to a compact outer skin means that
the foam cells in
the outer region of each of the pre-expanded foam beads are smaller than those
in the interior
region. Particular preference is given to the outer region of the pre-expanded
foam beads having
no pores, which will result in a substantially non-porous air duct section.
In an alternative embodiment, a porous air duct section is achieved by using
pre-expanded
porous beads as raw material and by controlling the moulding parameters, such
as the steam
pressure and temperature of the mould, in order to avoid complete melting of
the beads. In such
embodiments, a portion of air may pass through the wall of the resulting air
duct section. Such a
porous air duct may be desirable in some applications, including, for example,
but not limited to,
noise control.
In one embodiment, said pre-expanded foam beads are selected from a group
consisting of
expanded polypropylene, expanded polyethylene, expanded polystyrene, expanded
thermoplastic
urethane and combinations thereof In one embodiment, said pre-expanded foam
beads may be
closed cell, porous or combinations thereof
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In the third step, the mould is fully "closed" such that the partition lines
touch together on the
pre-expanded foam beads. This is called "crack fill" and is one of two main
pre-expanded foam
beads moulding techniques known in the industry. The hydraulics of a moulding
press, or the
like is used to compress the pre-expanded foam beads during the fill stage to
enhance final shape
and performance. Once the mould is closed a locking pin may be inserted to
keep the mould
closed.
The prc-expandcd foam beads density may have increased during the crack fill
step and the final
section of an air duct resulting may preferably have a density of from about 1
pound per cubic
foot to about 15 pounds per cubic foot after injection step, most preferably
from about 1 pound
per cubic foot to about 12 pounds per cubic foot. However, a resultant higher
density may also
be possible. in general, the density of the final moulded air duct section
increases during this step
compared to the density of the pre-expanded foam beads previously introduced
into the air duct
section mould.
In one embodiment, a thinner wall thickness may be obtained by compressing and
heating the
desired areas during this step. The density of the desired areas may increase
as high as 30 pounds
per cubic foot. However, the maximum density that may be achieved is a
function of the density
of the starting material as understood by a person of ordinary skill.
In one embodiment, an aesthetic wall surface may be obtained by compressing
and heating the
desired areas during this step. The resulting wall surface may have a
substantially smooth surface
on the outer skin, or may have a desired textured surface.
In the fourth step, steam, preferably superheated steam, is introduced under
pressure into the
mould via a. steam nozzle, for a suitable period of time allowing for fusion
of the particle foam
beads. The particle foam beads are then fused in the mould with the help of
the steam. Steam, in
this embodiment, is water steam heated to temperatures higher than 100 Celsius
at a pressure
which may reach 00 pounds per square inch. When the fusing temperature is
reached locally, the
particle- foam beads arc fused together.
After the fusing step, in the fifth step, the mould is cooled, allowing for
cooling and hardening of
the moulded air duct section. Once cooled to achieve sufficient mechanical
rigidity for
subsequent handling, the moulded air duct section is removed from the mould
cavity by opening
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the mould. The mould cooling method may be by spraying a suitable coolant, in
one
embodiment the coolant is water, through nozzles onto the backside of the
cavity of the mould.
In another embodiment, the mould is allowed to cool naturally over time (such
as by air-
cooling).
In the sixth step, the mould is opened so as to create enough space between
the two cavities,
movable and stationary, allowing removal of the air duct section from the
mould.
In the seventh step, the lrioulded air duct section is removed, or de-moulded,
from the mould
1.0 with the help of' ejectors. A suitable draft angle previously
incorporated into the design of the
mould and air duct ensures an easy ejection phase. Ejection can be done by
using one or a
plurality of ejections pins (ejectors) or other suitable ejection methods as
understood by a person
of ordinary skill.
In the eighth step (optional), at least one of said sections of an air duct
described herein is
fastened to another section of an air duct to form an air duct, preferably an
air-tight air duct. In
one embodiment, said fastening method is selected from the group consisting of
pressure-
snapping geometrically engaging surfaces, welding, gluing, installing
brackets, screwing, bolting
and combinations thereof.
In .a preferred embodiment, infrared welding may be used for fastening one
section to another
section. Infrared welding is the process of joining plastic components with
the use of electric
quartz glass infrared emitters known to persons of ordinary skill in the art.
With the two sections
in place, the emitters allow for the joint surfaces of each section to be
heated above the melting
point of' the pre-expanded foam beads and after removing the emitters, both
sections of the air
duct, are squeezed together for a sufficient period of time allowing for the
joint surfaces of the
two sections to fuse together.
Preliminary testing has shown air ducts fabricated by some embodiments herein
exhibit at least
one, preferably a plurality of:
a. Reduced weight of final product when using pre-expanded foam beads
described herein
in comparison to the prior art solid and soft blow moulded foam: in some eases
resulting
in a weight reduction of up to 80%;
b. Increased thermal insulation properties when using pre-expanded foam beads
described
herein when compared to the prior art solid and soft blow moulded foam;
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C.
Increased audio insulation properties, also known as noise attenuation
properties, when
using pre-expanded foam beads described herein when compared to the prior art
solid
and soft blow moulded foam. In some cases noise attenuation levels are
improved in
comparison to the prior art (for example, as measured by ASTM E2611);
d. Achieve or surpass common requirements for automotive air ducts, such as,
but not
limited to, heat resistance, chemical resistance and odours;
c. 100% recyclable;
f. Withstand multiple impacts without substantial damag,,c; and/or
g. Strong enough to bear structural support for other surrounding parts.
The air duct described herein may serve for the ventilation, heating and
cooling (air-
conditioning) system of automotive vehicles as well as other vehicles (e.g.
truck, train, bus,
recreational vehicles, airplanes, etc.). One advantage of such an air duct is
its relative lightness
compared to solid plastic air ducts of similar dimension of the prior art.
Furthermore, the random
fusing of the. pre-expanded foam beads within the walls of the air duct make
the duct sufficiently
rigid and suitable for automotive applications where loading, vibration and
temperature changes
are likely to happen. An example of such loading is when a passenger of an
automotive vehicle
places their feet on the top surface or extremity of an air duct in the
vehicle. Other examples
include having the air duct supporting fully or partially the weight of other
components typically
used in vehicles.
EXAMPLE 1
Referring now to Figures 2 and 3, the air duct (20) in this preferred
embodiment has the function
to bring the air from the HVAC front module to the knees of the second row
passenger through
the central console of an automobile. The walls have a thickness of about 5 mm
(compared to
the prior art conventional solid duct wall thickness of 1.5 mm). Without
compromising the
required inner surface area of a conventional solid duet, the extra space
needed for the wall
thickness is taken by increasing the outside dimensions of the air duct part
while keeping the
same inner surface area and the CFM needed. The air duct is designed in two
sections of an air
duct, lower (21) and upper (22), and the joining line (25) is located on the
two opposite corners
of the air duct sections to maximize the perpendicular moulding surface of the
mould opening.
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An open cell foam strip (23) of very low density is attached with conventional
adhesive to the
outer side of the inlet air duet region (23'). The open cell foam strip (23)
reduces any air leaking
proximate the inlet air duct region (23') after assembling the air duct to the
FIVAC module (not
shown).
A push-pin (24) is installed through an oval opening in the lower side of the
inlet. This push-pin
has an extra length shoulder (best seen in Figure .13) to accommodate the
extra wall thickness of
the present air duct versus a conventional solid duct. This push-pin (24)
secures the air duct in
place inside the vehicle.
In one preferred embodiment, an air duct (20) for the automotive industry is
fabricated, using
pre-expanded polypropylene (ePP) in steam chest moulding as described above.
More
specifically, in this embodiment, two cavities in a mould, one cavity
corresponding In a lower
section (21) and another cavity corresponding to an upper section (22) of an
air duct. Such mould
allowing removal of a moulded air duct section from the cavity once the entire
steam chest
injection mould process is completed. As will he apparent to a person skilled
in the art, each of
such cavities may have a plurality of removable parts to allow opening of the
mould and removal
of the moulded air duct section upon completion of the steam chest injection
mould process,
One non-limiting example of commercially available pre-expanded foam beads
suitable for
making a section of an air duct is Ncopolcn P ¨ D-00401B1m which is available
from Concepp
Technologies Inc. The pre-expanded foam beads have a diameter between about 3
and about 6
mm. In this example, the density of the pre-expanded polypropylene foam beads
prior to the
injection step is about 5 pounds per cubic foot.
The final density after completion of the steam chest moulding process may be
between about 5
and about 12 pounds per cubic foot. In one embodiment, the resulting air duct
section had a final
density of 6 pounds per cubic foot.
In a preferred embodiment; to obtain a strong welding joint of the two
sections of an air duet (21,
22) in pre-expanded polypropylene bead, infrared emitters arc used to form a
joint such that the
infrared emitters power is set between 60 to 90% of its maximum power to allow
for a surface
temperature of the joining edges (25) of each section (21, 22) of at least 250
F but not higher
than 350 F. The time needed to reach this range of temperature is less than 7
seconds. Once this
temperature range is achieved, both joining edges (25) are quickly squeeze
together, with a small
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overlap (in one embodiment less than I mm of overlap) of the joining edges,
creating a
compressing three for as long as needed to obtain a joint The joint is then
cooled. In this
embodiment, cooling time is in the range of 10 sec to 30 ace.
-- The air duct made by Example 1 weighs about 93 g (contrasted to 334 g for
an air duct
manufactured from conventional blow moulding process with solid walls). In
this instance, a
weight reduction of 72% was achieved. Typical industry testing (combustion
behavior, mildew
growth, odors characteristic, temperature and chemical resistance) passed
successfully.
-- Thermal conductivity of HDPE is normally between 0.46 to 0.51 W1(m.K.)
(0.39-
0.44 Kcal/m.hr.C). Thermal conductivity of ePP (PP pre-expanded foam beads) is
around
0.042 Kcallm.hr.C. It is expected that the temperature delta between the
outlet and the inlet of an
air duet may be smaller for an air duct made with ePP (PP pre-expanded foam
beads) when
compared to the same air duct made of solid EIPDE. Condensation issues on the
air duct wall
-- may be less and passenger ambient air comfort may be improved with an OP
air duct versus an
.HDPE air duet. Testing showed that temperature loss when hot air was passed
through the air
duet was smaller with the present air duct versus an air duct made by the
typical material used in
the conventional duct fabrication.
-- Transmission loss was tested on this air duct example per the ASTM E261 1.
Results show a
better transmission loss (TL) in a range of 100 to 4100 HZ at the outlet of an
air duct made with
ePP (PP pre-expanded foam beads) in steam chest moulding when compared to the
same air duct
made by blow moulding HDPE solid (best seen in Figure 14).
-- EXAMPLE 2
Referring now to Figures 4 and 5, the air duct (40) in this example has the
fimction to bring the
air from the second HVAC rear module to the roof duct of a vehicle such as a
van or another
large automotive vehicle. The walls have a thickness of about 5 mm (an
increase of about 3_5
mm wall thickness compared to a conventional solid duet). Without compromising
the required
-- inner surface area of a conventional solid duct, she extra space needed for
the wall thickness is
taken by increasing the outside dimensions of the air duct part white keeping
the same inner
surface area and the CFM needed. The air duct (40) is designed in two sections
of an air duct,
lower (41) and upper (42), and the _joining line (44) maximizes the
perpendicular moulding
surface of the mould opening_ This helps to obtain a 5 min wall thickness on
all walls of the air
-- duct manufactured with a telescope mould.
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In this example, an air duct (40) for the automotive industry is fabricated,
using porous pre-
expanded polypropylene (cPP) foam beads using steam chest moulding. More
specifically, in
this embodiment, two cavities in a mould, one cavity corresponding to the
lower section (41) and
the other cavity corresponding to the upper section (42) of an air duct. Such
mould allows for the
removal of a moulded air duct section from the cavity once the entire
injection process is
completed. As will be apparent to a person skilled in the art, each of such
cavities may have a
plurality of removable parts to allow opening of the mould and removal of the
moulded air duct
section upon completion of the injection mould process.
to
En this example, pro-expanded polypropylene foam beads (ePP) have a diameter
between about 3
mm and about 6 mm and the density, prior to injection, is about 3 pounds per
cubic foot.
In this example, lower section (41) and upper section (42) of an air duct arc
assembled together
using injectiweld DraderTm plastic welding adding more weight than IR welding
or hot glue.
The air duct made by this example weighs about 85 g (contrasted to 250 g for
an air duct
manufactured from conventional blow moulding process with solid walls). The
weight reduction
is 66% in this case.
EXAMPLE 3
Referring now to Figures 6 and 7, the air duct in this example (60) functions
to bring the air from
the HVAC front modulo to the feet of a passenger in the front area of a
vehicle. The walls have a
thickness between about 4 mm and about 8 mm. This is an average increase of
4.0 ram
compared to the conventional prior art solid air duct. Without compromising
the required inner
surface area of a conventional solid duct, the extra space needed for the wall
thickness is taken
by increasing the outside dimensions of the air duct part while keeping the
same inner surface
area and the CFM needed. The air duet is designed in two sections, a lower
section (dl) and a
upper section (62). In this example, the upper section (62) is a 'Li' shape
and the lower section
(61) of an air duct is of a shape to accommodate the upper section and the
shape of the location
in the vehicle where the duct will be installed.
The visible side (63) of the lower section (61) also has an aesthetic
appealing surface and
replaces the hush panel (not shown). Lower section (61) of an air duct has at
least one
calibration hole (65) to diffuse air to the passenger feet. Usually,
polyurethane foam is installed
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on the prior art solid hush panel. Due to the properties and low density of
the pre-expanded
polypropylene (cPP), polyurethane foam is not mandatory in this design.
Push-pins (64) are installed Through hole openings (64') in the lower section
(61). Push-pins
(64) have an extra length shoulder to accommodate the extra wall thickness
versus the
conventional solid duct. The push-pins serve to secure the assembled air duct
(Figure 7) in place
inside the vehicle.
In this example, an air duct (60) Ibr the automotive industry is fabricated,
using pre-expanded
polypropylene (ePP) via steam chest moulding as described herein. More
specifically, in this
embodiment, two cavities in a mould, each cavity corresponding to the lower
section (61) and
the upper section (62) of an air duct. Such that said mould allows removal of
a moulded air duct
section from the cavity once the entire injection process is completed. As
will be apparent to a
person skilled in the art, each of such cavities may have a plurality of
removable parts to allow
opening of the mould and removal of the moulded air duct section upon
completion of the
injection mould process.
In this example, an aesthetically appealing surface is obtained by compressing
and licatinv, the
outer surface areas (63) during this injection and cooling step. The resulting
wall having a
substantially smooth surface on the outer skin. In an another embodiment,
texture may be applied
to die outer surface with the same method.
In this example, pre-expanded polypropylene foam beads have a diameter between
about 3 mm
and about 6 mm and the density, prior to injection, is about 5 pounds per
cubic foot.
In this example, lower section (61) and upper section (62) of an air duct are
assembled together
using hot glue applied along the joining line (65') to allow the lower section
(61) and upper
section (62) to be joined together, forming an air duct.
The air duct of this example weighs about 93 g (contrasted to 220 g for an air
duct manufactured
from conventional blow moulding process with solid walls). The weight
reduction is 58% in this
case.
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The energy absorption of the air duct made of pre-expanded polypropylene beads
by the process
disclosed herein may exhibit a distinct advantage in case of a collision or
impact. In particular,
the air duct may serve to reduce any impact to the knees of a passenger in a
vehicle.
EXAMPLE 4
Referring now to Figures 8 and 9, the air duct (80) in this example functions
to bring the air from
the HVAC front module to the second row area of a vehicle proximate the knees
of the second
row passenger, through the central console of an automobile. The walls have a
thickness of
about 5 mm. This is an increase of 4.0 mm compared to the conventional prior
art solid duct.
Without compromising the required inner surface area of a conventional solid
duct, the extra.
space needed for the wall thickness is taken by increasing the outside
dimensions of the air duct
part while keeping the same inner surface area and the CFM needed. The air
duct is design in
two sections of an air duct, lower (81) and upper (82). In this instance, each
of the lower (81)
and upper (82) sections are 'W' in shape to assemble 2 walls face-to-face in
an effective way
while increasing the length of the joining line while maintaining good shape
for moulding.
The design also included a protrusion (83) to replace polyurethane foam (PUR)
used in
conventional air ducts of the prior art. The protrusion (83) has two
functions: (i) to level the car
floor under the air duct, and (ii) to improve thermal insulation to reduce,
preferably prevent,
condensation on the duct.
In this example, an air duct (80) for the automotive industry is fabricated,
using pre-expanded
polypropylene (cPP) via steam chest moulding as described herein. More
specifically, in this
embodiment, two cavities arc used in a mould, each cavity corresponding to the
lower section
(SI) and the upper section (82) of an air duct, such that said mould allows
for the removal of a
moulded air duct section from the cavity once the entire steam chest injection
process is
completed. As will be apparent to a person skilled in the art, each of such
cavities may have a
plurality of removable parts to allow opening of the mould and removal of the
moulded air duct
section upon completion of the steam chest injection mould process.
In the example. pre-expanded polypropylene foam beads have a diameter of
between about 3
mm and about 6 mm and the density, prior to injection, is about 5 pounds per
cubic feet.
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In this example, the lower section (81) and upper section (82) of the air duct
are assembled
together using adhesive (such as hot glue) applied along the joining lines
(84) allowing the lower
(81) and upper (82) sections to be joined together.
The air duct thereby made weighs about 190 g (contrasted to 271 g for an air
duct manufactured
from conventional blow moulding process with solid walls and with polyurethane
foam).
Weight reduction is 30% in this case.
Another benefit is also observed during installation of the air duct of this
example in a vehicle;
only one installation step is needed instead of two_ Previously, car
manufacturers would install
PUR foam first and the air duct over the PUR foam. With the integral
protrusion, the duct made
with this design may be installed without the PUR foam.
The structural strength property of the pre-expanded polypropylene was
demonstrated in this
example. The protrusion (83) of the lower section of the air duct is capable
of handling loads
with little loss in form or shape.
EXAMPLE 5
Referring now to Figures 10, 11 and 12, the air duct in this example (100)
functions to bring the
air from the HVAC front module to multi conventional air duets in the
instrument panel of an
automobile. The walls of 100 have a general thickness of 5 mm but may be more
or less in some
specific areas. This is a general increase of 4mm compared to the prior art
solid air duct
Without compromising the required Miler surface area of a conventional solid
duct, the extra
space needed for the wall thickness is taken by increasino. the outside
dimensions of the air duct
part while keeping the same inner surface area and the CFN1 needed. The air
duet (100) is design
in two sections, a lower section (101) and a upper section (102). Lower
section (101) has a `1.1'
shape and the upper section (102) is more flat. Both sections of an air duct
were assembled face-
to-face to form an air duct. The air duct (100) is designed to direct the air
from the FTVAC unit
to the front windshield defroster duct (110), passenger side window heating
duct (111), driver
side window heating duct (116), A.C. cross car duct right wing (112), A.C.
cross car duct left
wing (115), central A.C. right duct (113) and central A.C. right duct (114).
In this example, 110
to 116 are conventional solid air ducts showing that the overall duct assembly
may be a
combination of conventional solid air ducts and an air duct made as described
in the present
disclosure.
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Lower section (101) may incorporate a resonance chamber to absorb noise coming
from the air
blower.
=
Upper section (102) includes a groove or channel (103) to direct and maintain
at least one wire,
reducing or eliminating the need of a retaining clip typically used in the
prior art to harness wires
or the like.
In this example, an air duct (100) for the automotive industry is fabricated,
using pre-expanded
polypropylene (ePP) via steam chest moulding as described herein. More
specifically, in this
embodiment, two cavities in a mould, each cavity corresponding to the lower
section (101) and
the upper section (102) of an air duct, such mould allowing for the removal of
a moulded air duct
section from the cavity once the entire steam chest injection mould process is
completed. As will
be apparent to a parson skilled in the art, each of such cavities may have a
plurality of removable
parts to allow opening of the mould and removal of the moulded air duct
section =upon
completion of the steam chest injection mould process.
in the example, pre-expanded polypropylene foam beads have a diameter from
about 3 mm and
about 6 mm and the density, prior to injection, is 5pounds per cubic foot.
In this example, lower section (101) and upper section (102) of an air duct
(100) are assembled
together using hot glue.
The air duct thereby made in this example weighs 323g compared to the 390g for
an air duct
manufactured by conventional blow moulding process with solid walls. Weight
reduction is
17% in this case.
Referring now to Figure 13, pin 24 is depicted showing an extra length
shoulder to accommodate
the extra thickness of the walls of the air duet section made by the process
described herein.
Referring now to Figure 14, transmission loss of Example 1 was tested against
the prior art using
ASTM E261 (although other transmission loss protocols as understood by a
person of ordinary,
skill may be used), and one can see that in some frequencies, more sound
decibels arc stopped by
the wall of an air duct manufactured by steam chest moulding of cPP, then the
prior art.
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Many modifications and variations are possible in light of the above.
Therefore, within thc scope
of the appended claims, the present disclosure may be practiced other than as
specifically
described.
The present disclosure has been described in an illustrative manner. It is to
be understood that the
terminology, which has been used, is illustrative of preferred embodiments
rather than limitative.
RECTIFIED SHEET (RULE 91 . 1 )
