U.S. patent application number 13/806664 was filed with the patent office on 2013-05-23 for system and method of forming variable density seating materials.
The applicant listed for this patent is Brent T. Hodge, William W. Li, Ryoko Yamasaki. Invention is credited to Brent T. Hodge, William W. Li, Ryoko Yamasaki.
Application Number | 20130125313 13/806664 |
Document ID | / |
Family ID | 45469788 |
Filed Date | 2013-05-23 |
United States Patent
Application |
20130125313 |
Kind Code |
A1 |
Yamasaki; Ryoko ; et
al. |
May 23, 2013 |
System And Method Of Forming Variable Density Seating Materials
Abstract
A system and method of forming seating materials having variable
density gradient for high hardness ratio of high-to-low deflection,
and more specifically to forming foam materials for vehicle seats
having variable density gradient that allow greater comfort across
a wider range of occupant weights.
Inventors: |
Yamasaki; Ryoko; (Ypsilanti,
MI) ; Hodge; Brent T.; (Brighton, MI) ; Li;
William W.; (Ypsilanti, MI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Yamasaki; Ryoko
Hodge; Brent T.
Li; William W. |
Ypsilanti
Brighton
Ypsilanti |
MI
MI
MI |
US
US
US |
|
|
Family ID: |
45469788 |
Appl. No.: |
13/806664 |
Filed: |
July 13, 2011 |
PCT Filed: |
July 13, 2011 |
PCT NO: |
PCT/US11/43825 |
371 Date: |
February 4, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61363820 |
Jul 13, 2010 |
|
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Current U.S.
Class: |
5/653 ;
264/41 |
Current CPC
Class: |
B29C 44/0446 20130101;
A47C 7/021 20130101 |
Class at
Publication: |
5/653 ;
264/41 |
International
Class: |
A47C 7/02 20060101
A47C007/02 |
Claims
1. A method of forming a seat cushion comprising: providing an
uncured foam material; providing a mold having at least two mold
members which cooperate to form a mold cavity and wherein one of
said at least two mold members includes at least one moveable
member capable of extending from a retracted position to and
extended position within said mold cavity and wherein said moveable
member decreases the volume of said mold cavity in said extended
position; inserting said uncured foam material within said mold
cavity; allowing said uncured foam material to partially cure to an
intermediate state; moving said at least one moveable member to
said extended position and wherein in said extended position a mold
surface of said moveable member engages said uncured foam material
in said intermediate state; allowing said uncured foam material in
said intermediate state to cure to a final state; and removing the
seat cushion formed from said foam material in a final state.
2. The method of claim 1 wherein said step of moving said at least
one moveable member includes the step of creating a density
gradient in said uncured foam in said intermediate state.
3. The method of claim 1 wherein said step of providing an uncured
foam material further includes the steps of inserting said uncured
foam material into a portion of the mold cavity defined by one of
said mold members and closing the mold halves to create said mold
cavity including said uncured foam material.
4. The method of claim 3 wherein said step of inserting said
uncured foam material into a portion of the mold cavity further
includes the step of inserting the providing a substantially
homogenous foam material.
5. The method of claim 1 wherein at least one of said mold members
does not include a moveable member and wherein said step of
inserting said uncured foam material further includes the step of
inserting the uncured foam material into said mold member without
said moveable member.
6. The method of claim 1 wherein said moveable member in said
retracted position does not engage said uncured foam material.
7. The method of claim 1 wherein said step of allowing said uncured
foam material to partially cure to an intermediate state further
includes the step of applying heat for a specified amount of
time.
8. The method of claim 1 wherein said step of allowing said uncured
foam material to partially cure further includes the step of
allowing said uncured foam material to expand to at least contact
said moveable member in said intermediate state and wherein said
uncured foam material when initially placed in said mold member
does not touch said moveable member.
9. The method of claim 1 wherein said step of moving said at least
one moveable further includes the step of creating a density
gradient in said foam material.
10. The method of claim 1 wherein said step of allowing said
uncured foam material in said intermediate state to cure to a final
state further includes the step of maintaining said moveable member
in said extended state.
11. The method of claim 1 wherein said step of allowing said
uncured foam material in said intermediate state to cure to a final
state further includes the step of retracting said moveable member
to a position between said extended state and said retracted
state.
12. The method of claim 1 wherein said step of allowing said
uncured foam to partially cure includes the step of allowing said
uncured foam to substantially fill said mold cavity.
13. The method of claim 12 wherein said step of moving said at
least one moveable member to said extended position and wherein in
said extended position a mold surface of said moveable member
engages said uncured foam material in said intermediate state,
includes the step of reducing the volume of said mold cavity as
said at least one moveable member moves to said extended position
and wherein the seat cushion has a volume substantially equal to
the reduced volume mold cavity.
14. A seat cushion comprising: a foam material having an outer
surface include a first surface and an opposing second surface and
wherein said foam has a variable density gradient between said
first surface and said second surface and wherein said foam
material has a density that is greater at said second surface than
at said first surface and wherein said seat cushion is formed by a
process comprising: providing an uncured foam material; providing a
mold having at least two mold members which cooperate to form a
mold cavity and wherein one of said at least two mold members
includes at least one moveable member capable of extending from a
retracted position to and extended position within said mold cavity
and wherein said moveable member decreases the volume of said mold
cavity in said extended position; inserting said uncured foam
material within said mold cavity; allowing said uncured foam
material to partially cure to an intermediate state; moving said at
least one moveable member to said extended position and wherein in
said extended position a mold surface of said moveable member
engages said uncured foam material in said intermediate state;
allowing said uncured foam material in said intermediate state to
cure to a final state; and removing the seat cushion formed from
said foam material in a final state.
15. The seat cushion of claim 12 wherein said density gradient
varies exponentially between said first surface and said second
surface.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This U.S. National Stage Patent Application claims the
benefit of International Application serial number PCT/US11/43825
filed Jul. 13, 2011, entitled "System And Method Of Forming
Variable Density Seating Materials" and U.S. Provisional Patent
Application Serial No. 61/363,820 filed Jul. 13, 2010, entitled
"System And Method Of Forming Variable Density Seating Materials,"
the entire disclosures of the applications being considered part of
the disclosure of this application, and hereby incorporated by
reference.
BACKGROUND
[0002] 1. Field of the Invention
[0003] The present invention generally relates to a system and
method of forming seating materials having a variable density
gradient and more specifically to forming foam materials for
vehicle seats having a variable density gradient that allow greater
comfort across a wider range of occupant weights, and the use of
single foam formulations across a wide range of types of vehicle
seats having significantly different desired performance
characteristics.
[0004] 2. Related Art
[0005] Vehicle manufacturers must make their vehicle seats
comfortable to a wide range of vehicle occupants having
significantly different weights and sizes. The manufacturer of a
vehicle seat must consider a weight range from that of a small
child who no longer needs a booster seat through the upper weight
and size range of adults. A lighter occupant and a heavier occupant
would find the same vehicle seat to perform significantly
different, and each occupant would prefer very different hardness
and more specifically the amount of deflection of seating
materials. For example, the static comfort of a seating foam, such
as a polyurethane seating foam, depends greatly on the hardness and
density of the foam, especially at high deflection. Although
vehicle manufacturers attempt to select the hardness of the foam to
provide desired static comfort for a wide range of occupant
weights, it is difficult to please every occupant due to the
variation between occupant weights and thereby the amount of
deflection which is related to the occupant's penetration into the
foam while sitting upon the seat. More specifically, a soft foam
material is likely to provide a comfortable seat for a light
occupant, while most heavy occupants would feel bottomed out, feel
frame components, or feel uncomfortable in the same seat.
Conversely, a harder foam generally ensures a comfortable seating
material for a heavy occupant, but also results in less deflection,
which causes lighter occupants to find the seat not comfortable,
such as the seat being too hard, causing them to sit on top of the
foam, and not sink, at least partially, into the foam. While
manufacturers may adjust the hardness of the foam to that preferred
by an average user, the more displaced the vehicle occupant is in
weight from the average user, the less comfortable they find the
vehicle seat. Therefore, in a single material, a single piece of
foam construction seat, to date manufactures are limited in their
ability to provide a comfortable seating surface for a wide range
of occupant weights.
[0006] The variance in comfort of seating materials or desired
performance of seating materials may also vary depending on the
desired application, vehicle type, target consumer, and vehicle
manufacturer preferences. For example, in many sport or performance
cars, it is desirable to have a firmer seat than in luxury
cars.
[0007] Originally, to address the desire for different seating
characteristics, and in particular the hardness of the foam, most
manufacturers created a wide variety of foam formulations. While
these different foam formulations allowed variations in the
properties of the particular seat to be addressed, it did not solve
any of the above described problems related to the differences
between occupants of the vehicle seats. In addition, the demand for
increased comfort and increased durability, as well as an expanded
range of required properties, limit the ability of manufacturers to
address all desired properties with only changing the foam
formulation. Furthermore, as the range of required properties
increase and the desire of high hardness foam for some individuals
and low hardness foam for comfort for other individuals, these
competing dynamic comfort issues caused the foam formulations used
to not be as well-balanced chemical mixes as traditional foam
formulations and therefore caused difficulty during the
manufacturing process. Also, many of these unique foam formulations
required specialty chemicals which increased raw material costs and
at times required additional manufacturing equipment and processes
which increased the cost of the vehicle seat.
[0008] To address the above shortcomings and a wider weight range
of vehicle occupants, some manufacturers have created a two-part
foam assembly for the seating material, which requires time
consuming and expensive manufacturing processes. Therefore, due to
the cost of assembly of multiple slabs of foam having different
densities, its application across a wide range of vehicle seats is
currently limited. The two-part seat material may be formed by two
methods. The first is to generally apply a separately soft layer of
foam to a harder molded foam wherein the soft slab of foam is
closest to the A surface or seating surface of the seat material.
In such a method of forming a two-part foam seating material, first
the harder foam seat material is molded and then a second softer
seat material is molded or cut from slabstock foam with the desired
shape. Then, the two parts are glued together with an adhesive,
which increases production costs significantly due to the extra
labor, equipment, materials and space needed. As manufactures also
strive to improve the environmental aspects of the manufacturing
process as well as the recyclability of the materials, the use of
an adhesive to glue the soft die cut slabstock foam or separately
molded piece to the harder molded foam is generally not desirable.
For example, in using the two-part seating material, the adhesive
may make it more difficult to recycle the seat at the end of the
life cycle and it is difficult to find environmentally friendly
adhesives with desired performance characteristics over the life
cycle of the seat.
[0009] The second method some seating manufacturers have also
developed is a mold-in process to form a two-part seating material
that eliminates the need for the adhesive. Even though the need for
the adhesive is eliminated, significant disadvantages also occur in
the molding process that significantly slow the line speed and
processing time for each seating material. More specifically, many
manufacturers use a method of foam production that pours multiple
formulations within one mold, typically in layers to achieve high
hardness bolsters while maintaining a softer insert near the A
surface. The additional formulations and processing steps require
additional space to store the different components that are used in
the mold, additional equipment space, and additional demands are
placed on the operators of the manufacturing process. Furthermore,
no suitable technology has been found to date to prevent
contamination of the mold-in slab from the liquid polyurethane
chemical blends mixing during foaming process. More specifically,
many times the different layers of foam would have uncontrollable
or undesirable blending or be outside of their desired layer
boundaries such as a hard foam formulation intruding upon an area
where a soft foam formulation is desired and even worse, at times
intruding only partially, causing an uneven feeling of hardness or
hard spots in the vehicle seat. Though many manufacturers adjusted
the pour processes to attempt to prevent such quality issues, this
often added complexity, and cost in the manufacturing process and
also limited at times the types of formulations that may be used
with each other. This contamination or mixing of formulations
typically negates the comfort benefit found in providing a
slab-molded two-part material seating slab.
[0010] In vehicle seats that used a backing material such as
placing a precut cloth-like material in the mold and then directly
molding foam to the material other problems may occur. These
methods are typically used to produce a strong B surface bond for
increased durability as well as other performance characteristics
but are difficult to use with multiple foam formulations as well as
the above described two-part mold in process. More specifically,
molding to a backing material in the mold may create a number of
issues during the foam molding process, such as movement of the
backing material as multiple layers are injected, as well as the
undesirable mixing of various types of materials.
SUMMARY
[0011] The present invention generally relates to a system and
method of forming seating materials having variable density
gradient for high hardness ratio of high-to-low deflection. More
specifically to forming foam materials for vehicle seats having
variable density gradient that allow greater comfort across a wider
range of occupant weights.
[0012] The present invention uses a method to create a variable
hardness seating material with only minimal tooling changes and
limited to no reduction in manufacturing efficiency. First, the
material is placed in a mold and then expanded to fill the mold.
Unlike prior molds, the present invention uses molds that have
larger cavity areas in which moveable plates or mold sections rest.
With the mold cavities filled with the expanded foam and
approaching the cured state, the moveable plate compresses the seat
to the final size, such that the areas closest to the moveable
plate are compressed to have greater densities. This creates a
variable density seat with greater differential in hardness between
low and high deflections. The seat foam is more comfortable to a
wide range of occupant weights, deflecting as desired for the
lighter weight occupants while providing sufficient support for
heavier occupants in order to prevent the sensation known as
"bottoming out."
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] Various exemplary embodiments of the systems and methods
according to the present disclosure will be described in detail,
with reference to the following figures, wherein:
[0014] FIG. 1 illustrates an exemplary seating mold with an A
surface being on the bottom side and the initial location of the
mold materials after the mold of the present invention is
closed;
[0015] FIG. 2 illustrates the mold in FIG. 1 with the foam seating
material expanded to completely fill the mold cavity and a moveable
plate in a first position;
[0016] FIG. 3 illustrates the mold of FIG. 2 wherein the moveable
plate has moved from the first position to a second position, which
compresses the seating material providing the illustrated increased
density gradient on the backside of the seating material;
[0017] FIG. 4 illustrates an exemplary graph of strain in
millimeters relative to an applied force to the seating material of
the present invention compared to that of a conventional seating
material;
[0018] FIG. 5 illustrates an exemplary graph of frequency versus
transmissibility using the same formulation, density and thickness
wherein transmissibility has the same formulation density and
thickness;
[0019] FIG. 6 illustrates deflection versus hardness with the same
formulation, thickness and weight; and
[0020] FIG. 7 illustrates an exemplary graph of a load deflection
curve with the deflector percentage versus force and more
specifically illustrating that a similar load deflection curve may
be obtained using a foam that is only 70 mm and 1,096 g versus
conventional foam that is 96 mm and 1,220 g.
DETAILED DESCRIPTION
[0021] The present invention generally relates to a system and
method of forming a seat (not illustrated). The seat generally
includes a seating material that provides support to the vehicle
occupant, such as the illustrated foam base 10. The foam base 10
includes an A surface 12, a back surface 13 and bolsters 18. As
further illustrated in FIG. 3, the cross sectional view shows a
density gradient area 14, having a higher density area 15 and a
lower density area 16 in the final foam base 10 configuration.
[0022] The seat, specifically the foam base 10, is generally formed
in a mold. While the seat material, in particular the foam base 10,
may be formed in any style, size, or configuration, the Figures
show an exemplary seat and the present invention is applicable to
other styles and configurations. In addition, the mold 20 would
vary in style, shape, size, and configuration as desired to form
the particular desired seating material and in addition to the
illustrated foam base 10. The mold 20 generally includes a base 24
and sidewalls 26 into which the foam material is placed for the
mold process to begin. The illustrated mold 20 generally includes
bolster cavities 28 and a main cavity 30 which are confined by the
sidewalls 26, base 24, and an upper plate 32. As illustrated in
FIG. 2, the upper plate 32 may have a first or retracted position
34, and as further illustrated in FIG. 3, a second or extended
position 36. The illustrated mold 20 is for forming a base 10 of a
seat and different molds may be used for different styles, shapes,
sizes and configurations, as well as different molds to be required
for the seating materials for the upper back of a seat, or for
example, a rear seat of a vehicle. In addition, even though not
illustrated, other portions of the mold may include additional
moveable plates to vary the density of other portions of the seat
such as a moveable plate in the bolster area (not illustrated) to
provide different densities in the bolster area.
[0023] The present invention, and in particular the process of
forming the seat, starts similar to other seat forming processes in
that the mold is open and a mold material such as a polyurethane
seating foam initial material is placed or inserted in the mold in
desired quantities and then the mold is closed. The mold, depending
upon the type of material used, may be preheated to a desired
temperature before the material is placed into the mold. The
material 11 may be any type of material commonly used or desirable
for use in forming the seating structure. The present invention as
illustrated in FIG. 4 compares a conventional polyurethane foam
seat base to a polyurethane foam seat base that incorporates the
present invention. With the polyurethane foam material 11 being
placed in the mold in the desired quantities, the process of
expanding the foam to fill the mold starts as illustrated in FIG.
2. More specifically, the material in FIG. 2 has filled the mold
and has reached a state of semi-cure and normally would be allowed
to stay in the mold without change for some additional specified
time period. The mold 20 of the present invention includes an
enlarged cavity area such as the illustrated main cavity 30 wherein
in the initial position as illustrated in FIG. 2 the foam fills a
greater area than desired for the final seat base 10 as illustrated
in FIG. 3. Once the mold material has completely filled the mold
cavity 30 for the desired time, the inner plate 32 is moved from
the first position 34 as illustrated in FIG. 2 to the second
position 36 as illustrated in FIG. 3. Upon the movement of the
upper plate 32 to the second position 36, the mold cavity forms the
final desired shape and size of the seat base 10. As illustrated in
FIG. 3, by moving the upper plate 32 from the first position 34 to
the second position 36, the area closest to the upper plate 32 of
the foam base 10 has the highest density area 15. In comparison,
the lowest density area 16 is furthest away from the upper plate 32
and is approximately the A surface 12 which is engaged against the
A mold surface 24. The density of the foam in the main cavity 30
may vary on a gradual even density gradient but is expected that
the increase in density is more of an exponential nature than a
linear nature. More specifically, the lower density area 16 extends
further into the foam base 10 and as it approaches the back surface
13, the density substantially increases quickly to the high density
area 15. As the graph illustrates in FIG. 4, the present invention
allows for low hardness at low deflection and then increased
hardness at a higher rate than a conventional seat foam as the
deflection increases. The present invention as illustrated in FIG.
4 provides a better static comfort for a wider range of occupant
weights while eliminating expensive two-part foam seating
materials. Furthermore, the present invention may use less material
and have less overall mass by providing high density in only the
sections where needed.
[0024] The mold 20 is only one style of a particular foam base 10,
and other styles may be used which in addition include other areas
that include moveable plates in addition to the illustrated upper
plate or in place of the upper plate, such that the density
gradient could have greater adjustment to particular seat styles,
shapes or configurations allowing for the complete tailoring of a
particular seat for the most comfortable possible position. For
example, the cavity of the bolster cavity 28 could be intentionally
enlarged and include a moveable bolster plate (not illustrated)
that increases the density on the outer boundaries of the bolsters
to provide more support when needed.
[0025] In addition, for molds such as those that form the upper
back of the seating material to provide comfort along the complete
upper back, the moveable plate may not have uniform compression
along the length of the upper back (not illustrated). Therefore, it
is possible through using multiple plates across a surface to
create various density gradients where desired to increase seating
comfort. Another example, though not illustrated for a seating base
such as the illustrated foam base 10, would be to provide a larger
cavity near the rear surface of the seat than the front edge of the
seat and then compresses such that the density gradient also varies
between the rear of the foam base to the front of the foam base.
The front, where less weight is placed by the legs, would have a
softer, more comfortable seating position, while the seat would
allow greater support in the foam base where the most weight is
placed by a particular user. This would increase seating comfort
and reduce fatigue of the vehicle operator.
[0026] It is important to note in FIG. 7 that both the mass and
thickness provide a reduction in vehicle weight and also provides
increased cabin space.
[0027] The foregoing invention has been described in accordance
with the relevant legal standards, thus the description is
exemplary rather than limiting in nature. Variations and
modifications to the disclosed embodiment may become apparent to
those skilled in the art and fall within the scope of the
invention.
* * * * *