U.S. patent application number 09/971251 was filed with the patent office on 2005-08-04 for thin, double-wall molded seat frame system.
Invention is credited to Glance, Bradley M., Glance, Patrick M..
Application Number | 20050168041 09/971251 |
Document ID | / |
Family ID | 34810955 |
Filed Date | 2005-08-04 |
United States Patent
Application |
20050168041 |
Kind Code |
A1 |
Glance, Patrick M. ; et
al. |
August 4, 2005 |
Thin, double-wall molded seat frame system
Abstract
A seat frame for a vehicle or other seating comprises a seat
back and a seat pan formed of molded double wall members having
thin, substantially closed exterior walls and a substantially open
interior. The exterior walls include front and back sections having
a cavity therebetween, secured together to form a hollow, box beam
type of structure. Integrally formed, spaced cup-shaped standoffs
extend between the front and back sections between side walls
thereof and provide internal reinforcement of the seat member
between the side walls. The seat back includes a cavity for a seat
back reinforcement member for either a restraint or non-restraint
seat.
Inventors: |
Glance, Patrick M.;
(Plymouth, MI) ; Glance, Bradley M.; (Plymouth,
MI) |
Correspondence
Address: |
VARNUM, RIDDERING, SCHMIDT & HOWLETT LLP
333 BRIDGE STREET, NW
P.O. BOX 352
GRAND RAPIDS
MI
49501-0352
US
|
Family ID: |
34810955 |
Appl. No.: |
09/971251 |
Filed: |
October 4, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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60237926 |
Oct 4, 2000 |
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Current U.S.
Class: |
297/452.18 ;
297/452.2; 297/452.65 |
Current CPC
Class: |
B60N 2/68 20130101 |
Class at
Publication: |
297/452.18 ;
297/452.65; 297/452.2 |
International
Class: |
A47C 007/02 |
Claims
I claim:
1. In a seat frame comprising a seat back and a seat pan, the
improvement wherein at least one seat member of the group
consisting of the seat pan and seat back comprises a molded double
wall member having a substantially closed exterior wall and a
substantially open interior, with the exterior wall comprising
opposed front and back sections having a cavity therebetween, the
front and back sections fitting together and being secured together
to form a hollow, box beam type of structure.
2. A seat frame according to claim 1 wherein at least one of the
front and back sections includes integrally formed, spaced
cup-shaped standoffs extending between the front and back sections
at positions between the side walls thereof, such that the
standoffs provide internal reinforcement of the seat member between
the side walls.
3. A seat frame according to claim 2 wherein the standoffs include
individually formed, conical, cup-shaped energy absorbing
cells.
4. A seat frame according to claim 3 wherein aligned standoffs are
formed in the back and front sections, such that inner ends of
aligned standoffs are adjacent each other when the front and back
sections are interconnected.
5. A seat frame according to claim 1 wherein the at least one seat
member comprises the seat pan, the seat pan being formed in a
generally rectangular shape and having a hollow peripheral frame
comprising a front member back member and side members, the frame
having an open interior, the front, back, and side members being
box beam members formed of the front and back sections, the front
section being an upper section and the back section being a lower
section, the frame including interior standoffs extending
vertically between the upper and lower sections.
6. A seat frame according to claim 1 wherein the at least one seat
member includes the seat back.
7. A seat frame according to claim 6 wherein the seat back includes
a hollow cavity for a seat back reinforcement member.
8. A seat frame according to claim 7 wherein the cavity is formed
along a vertical side of the seat back and is shaped to receive a
seat back reinforcement tower formed of a material dissimilar from
the seat back.
9. A seat frame according to claim 6 wherein the seat back
comprises a generally rectangular frame having upper and lower
frame members and side frame members, with each frame member having
a box beam configuration with a substantially hollow interior, the
frame having interior standoffs reinforcing front and back surfaces
of the frame between frame side walls.
10. A seat frame according to claim 9 wherein the standoffs include
spaced, cup-shaped energy absorbers mounted in at least one of the
front and back members and extending in a direction between the
members.
11. A seat frame according to claim 1 wherein a plurality of
standoffs are formed on the interior of one of the front and back
sections of the seat back, the other of the front and back sections
of the seat back including standoffs that are aligned with the
standoffs in the one section, outer ends of the aligned standoffs
being substantially abutting each other, the standoffs comprising
elongated, hollow projections.
12. A seat frame according to claim 9 wherein the frame has at
least a partially open portion interior of the frame members, the
frame members surrounding the open interior.
13. A seat frame according to claim 1 wherein the front section is
contoured for serving as a support for the body of a person seated
in the seat, while the back section is provided with a different
surface contour that is designed to provide an acceptable
configuration for attachment in a vehicle, the different surface
contours not requiring substantial additional material in the seat
member because of the hollow seat member construction.
Description
CROSS-REFERENCES TO RELATED APPLICATIONS
[0001] This application is based on and claims the benefit of the
filing date of co-pending U.S. Provisional Patent Application Ser.
No. 61/237,926, entitled Thin, Double-Wall Molded Seat Frame System
and filed on Oct. 4, 2000, by Patrick M. Glance and Bradley M.
Glance, the disclosure of which is incorporated here by
reference.
BACKGROUND OF THE INVENTION
[0002] The invention relates to vehicular seating generally and
more particularly to a new vehicular seat frame.
[0003] Today automotive seat frames, for example, are constructed
from a number of materials and manufacturing technologies. Most
seat frames and seat backs are fabricated from steel tubing. Front
bucket seat pans (a lower seat frame utilized to mount a seat lower
cushion) are commonly stamped steel with a steel seat spring
suspension, although a technology limitation of steel seating
frames is their large mass. Some seat frames utilize aluminum or
magnesium, which has lighter mass, but is more expensive. Some seat
pans are molded, glass-filled polypropylene or other molded resin
systems.
[0004] Many automotive rear folding seats are blow molded,
high-density polyethylene, or other resin. Some rear folding seat
backs that double as a load floor in a down position, are
compression molded, glass filled polypropylene, blow molded high
density polyethylene, blow molded ABS/polycarbonate, or other resin
system. Some front seat back frame/trim covers are also molded
glass filled polypropylene, polycarbonate, or other resin.
[0005] A technology limitation of molded seat frames is their
relatively large molding thickness, typically about 3 mm with
ranges from about 6 to about 2 mm. The large molding thickness
results in a slow molding cycle time, and greater material usage,
which directly results in a higher seat frame cost. A low resin
tensile strength also contributes to larger molding thickness that
is required to meet structural seat back load requirements. This is
a technology limitation and natural consequence of plastic seat
frames.
[0006] These technology limitations have resulted in steel seat
back frames weighing 6 to 8 pounds and costing $8 to $12, while
steel bucket seat frame assemblies weigh between 4 to 6 pounds, and
cost between $4 to $6. Aluminum fabrications are usually half the
mass, but double the cost of steel. Magnesium frames usually cost
more than aluminum.
[0007] Molded seat frames are typically expensive compared to steel
frames, but are utilized for specialty, niche applications where
the molded surface doubles as a styling show surface, a load floor,
or is utilized to reduce mass in conjunction with metal
reinforcement. Molded seat frames often have a lower mass than
their steel counterparts, at a higher cost. Lower mass is useful in
improving vehicle fuel economy and may be a factor in the safety
consideration.
[0008] Of course, the above comments assume that all the seat frame
alternatives are designed to the same or similar structural
requirements. Regardless, a need for an alternative construction
that reduces mass at no cost penalty is clearly desired.
BRIEF SUMMARY OF THE INVENTION
[0009] In accordance with the present invention, a molded seat
frame that lowers mass compared to conventional metal, but is cost
competitive, comprises a thin, double-wall injection molded seat
frame system. Theoretical studies indicate that a double wall
injection molded, talc-filled high density polypropylene seat back,
molded in a 1 mm wall thickness, will result in a 60% mass
reduction, and a 25% cost reduction versus current technology steel
frame systems. The key to this savings is the use of the design
principle of a closed box section with a thin wall structure that
has continuous design stand-offs between the double walls to resist
"thin wall buckling."
[0010] The large area enclosed in a continuous jointed container is
an extremely strong and efficient structure, especially during
torsional loading. The characteristic analogy in nature is an
eggshell, but with added integral, inter-connecting "stand-offs" to
reinforce the thin outer shell, and improve structural
strength.
[0011] A basic principle of this invention is the use of a thin
wall enclosed structure that is molded from two halves and jointed
to create a structure with internal reinforcements either molded-in
or "placed" in the structure. This approach has advantages for
improved product simplification, reduced mass, improved structure,
and incorporation of dissimilar materials and reinforcement within
the assembly.
[0012] For example, one design scenario is the use of an injection
molding 1 mm thick, filled plastic in a half cavity shape. At the
same time, a corresponding 1 mm half cavity shape may be molded and
then the two joined by hot plate welding, sonic welding, bonding,
or other joining technology. The injection molded two half design
approach produces a product that is similar to a blow molded seat
frame construction, but the injection molding has further
advantages of better component thickness control, thinner wall,
faster cycle time, and use of larger varieties of resins. It is
possible to mold resins such as polyethylene terephthalate (PET),
polybutylene terephthalate (PBT), thermosets, and glass-filled
nylon, for example, which cannot be blow molded. The basic design
concept also has application for metal die casting, such as zinc
and magnesium and vacuum injection molding.
[0013] Although the invention is described for automotive or over
land vehicular seating, the basic invention has application for all
vehicular seating applications including without limitation air,
marine, bus, and rail. The invention may also be applied to office,
home, and theatre seating, for example. The specific design
sketches are for bucket seating, but the same principle applies for
bench seating and couches.
[0014] These and other features, objects, and benefits of the
invention will be recognized by one having ordinary skill in the
art and by those who practice the invention, from the
specification, the claims, and the drawing figures.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING
[0015] FIG. 1 is a perspective view of a double wall seat frame
assembly, constructed in accordance with the present invention.
[0016] FIG. 2 is a perspective view as in FIG. 1 but also showing
the internal construction of the assembly.
[0017] FIG. 3 is a fragmentary top plan view showing a left half of
a seat pan of a thin, double wall molded seat frame system of the
invention, the right half being a mirror image thereof;
[0018] FIG. 4 is a front elevational view thereof;
[0019] FIG. 5 is a left side elevational view thereof;
[0020] FIG. 6 is a right rear perspective view thereof;
[0021] FIG. 7 is an exploded right front perspective view thereof,
showing top and bottom portions of an injection molded seat pan
ready to be joined at a common weld flange and at the base of
various stand-offs;
[0022] FIG. 8 is a fragmentary left back perspective view of a left
half of a seat back frame system of the invention, the right half
being a mirror image thereof;
[0023] FIG. 9 is a fragmentary left front perspective view of the
right half of the seat back frame of FIG. 8;
[0024] FIG. 10 is an exploded view of the view of FIG. 9, showing
the front and rear portions of the seat back frame separated;
and
[0025] FIG. 11 is a perspective view of a tower reinforcement
member for an integrated safety belt restraint system.
[0026] FIG. 12 is a perspective view of a tower reinforcement
member for a seat that does not have an integrated safety belt
restraint system.
DETAILED DESCRIPTION OF THE INVENTION
[0027] A preferred embodiment of a thin, double wall molded seat
frame system according to the invention is generally shown in the
drawing figures and discussed below.
[0028] Referring to the drawings, FIG. 1 is a perspective view of a
double wall seat frame assembly 10 constructed in accordance with
the present invention. Seat frame assembly includes a seat back 12,
a seat pan 14 and a recliner mechanism 16 interconnecting the seat
back and seat frame. The recliner mechanism is known.
[0029] A reinforcement tower 18 extends through an internal cavity
20 on one side of the seat back. In FIG. 1, tower 18 is a restraint
tower for a seat that incorporates an integral restraint system,
wherein the safety belt is attached directly to the seat back. A
seat belt retractor housing 22 is mounted on the top of tower 18.
Where an integral restraint system is not employed, a conventional
reinforcement tower 24 (FIG. 13) is employed instead of the longer
restraint tower 18. The shorter reinforcement tower can terminate
at the upper end of recess 20. These components are known.
[0030] Seat pan 14 comprises a generally rectangular frame having a
front frame member 26, a rear frame member 28, and side frame
members 30, defining an open interior portion 32. A conventional
resilient insert 34 can be inserted in opening 32. The insert may
be formed of conventional insert material, the insert being
conventional.
[0031] Side frame member 30 and rear frame member 28 include
reinforcement ribs 36 in an upper surface thereof. The seat pan has
recessed fastener attachment areas 38 in the corners thereof for
attaching the seat pan to a seat support structure in a vehicle.
Front frame member 26 has an elevated contoured portion 40 that
provides a desirable contour for leg support at the front edge of
the seat pan.
[0032] The construction of the seat pan 14 is shown in more detail
in FIGS. 3-7. As shown in FIG. 7, seat pan 14 is formed from a pair
of molded, opposed cavity sections that are joined together to form
a box beam having a generally open interior. The cavity sections
comprise front or upper section 42 and a back or lower section 44.
These are formed separately and bonded together by hot plate
welding, sonic welding, chemical bonding or other joining
technology to form a hollow seat pan construction.
[0033] Upper section 42 has an upper surface 46, outer sidewall 48,
and inner sidewall 50, with the rear side of the upper section
being open. Lower section 44 covers the open rear side of the upper
section and has flanges 45 and 47 at inner and outer peripheral
edges that engage and are secured to the sidewalls of the upper
section to form a closed box beam.
[0034] Independently spaced, conical, cup-shaped projections 52,
preferably with a circular cross section, extend downwardly from
the upper surface of upper section 42 in the interior of the front
and rear members 26 and 28. These form standoffs that reinforce the
interior portions of the seat pan. The standoffs in the upper
section of the seat pan desirably are opposed by corresponding
standoffs 54 that extend upwardly from at least the front portion
of lower frame section 44. Lower standoffs 54 can also be upwardly
extending cup-shaped conical projections. The lower projections are
shorter than the upper projections in the illustrated embodiment.
The ends of the conical projections can abut each other, as shown
in FIG. 6 and can be bonded together if desired when the seat frame
is assembled. As shown in FIG. 6, the assembled seat pan comprises
a continuous peripheral sidewall, with a hollow interior reinforced
by spaced standoffs. This reduces mass dramatically while retaining
a desirable contour with desirable strength characteristics.
[0035] Desirably, the seat pan is formed by injection molding,
although other molding techniques will work. A satisfactory resin
for the present invention is a talc-filled high density
polyethylene (HDPE), but other materials are satisfactory.
[0036] The construction of seat back 12 is shown in FIGS. 8-12. For
exemplary purposes, the illustrated seat back is of a type that is
capable of use for an integral restraint mechanism. It should be
understood that the seat back can also be a non-restraint type seat
back. Seat back 12 is formed of the same double wall, welded,
closed construction as the seat pan, with the seat back being
formed in separate front and back sections 56 and 58. The front
section has a front surface 60 and sidewalls 62 extending
rearwardly to an open side 64. Back section 58 covers open side 64
and has a back surface 66 and flanges 68 that mate with the
sidewalls of the front section. The sidewalls are welded or
otherwise fastened to the flanges in a conventional manner to form
a closed member having a hollow interior.
[0037] Cup-shaped standoffs 90 are formed between the sidewalls at
various locations in order to provide internal reinforcement for
the seat back at positions between the sidewalls. In the
illustrated embodiment, the standoffs are generally rectangularly
shaped, with opposing standoffs being formed on the inner sides of
the back and front sections. The standoffs may abut each other and
be fastened together when the opposed sections of the seat back are
fastened together. It is contemplated that the standoffs could be
in one section or the other but not both sections in appropriate
cases.
[0038] The seat back of the present invention is formed in the
shape of a rectangular frame having side members 92, bottom member
94, and a top member 96. Desirably, an integral head rest 98 is
mounted on the top of top member 96. The integral head rest
includes side members 100 and a top member 102 extending between
the tops of the side members. An opening 104 is formed in the
interior of the head rest. Similarly, an opening 106 is formed in
the interior of the seat back 14. An insert 108 formed of a plastic
rattan material or other flexible material can cover the opening
106. An attachment flange 110 can surround the interior edge of
opening 106 for attaching the rattan insert or the like. The
attachment flange can be formed of an elastic material such as a
Flex-o-lator brand product.
[0039] One of the side members 92 of the seat back can have a
hollow tower insert cavity 20 therein for insertion of either a
restraint tower 18 or a non-restraint tower 24. The restraint
towers desirably are formed of aluminum tube. A restraint tower is
somewhat thicker than a non-restraint lower, with the restraint
tower desirably being 2.2 mm thick and the aluminum material in the
non-restraint tower being about 1 mm thick.
[0040] With the seat back and seat pan formed in the foregoing
manner, the seat has a desirable outer configuration and an inner
configuration that facilitates mounting in the vehicle, and yet the
structure is lightweight, strong, and relatively inexpensive.
[0041] A particular bucket seat assembly is shown in the present
invention. It should be understood that various other types of seat
configurations could be employed without departing from the spirit
and scope of the present invention.
[0042] Among the advantages of the present invention, the seat is a
hollow, internally reinforced, integrated structure created from
two molded cavities which are joined together to form a closed
section container shape. This provides desirable strength, weight,
and expense characteristics.
[0043] Another advantage of the present invention is that the seat
frame pan and seat back are formed in two cavity halves, which are
molded together to form a closed box section. It is desired that
the walls of the two cavities, in each case, are relatively thin
(typically about 1 mm) and hence flexible, with internal, molded
standoffs reinforcing the outer walls when the two cavities are
joined together. Notwithstanding the extremely thin walls, the seat
frame pan and seat back provide good structural performance.
[0044] The seat frame pan and seat back can be formed from a number
of different manufacturing processes, such as injection molding,
twin sheet vacuum forming, vacuum die casting, casting, or
compression molding. The seat frame pan may be formed of a number
of different materials, such as high density polyethylene,
polypropylene, acrylonitrile butadiene styrene, polycarbonate,
sheet molding compound, PBT, PET, or metal such as magnesium, zinc
alloy, or aluminum. Talc filled HDPE is typical. The seat back can
be made of comparable materials.
[0045] As shown in FIG. 10, the formation of the seat back in two
sections also facilitates incorporation of the reinforcement
structure formed of metal. In such a case, the reinforcement cavity
20 can be formed between the front and back sections, with the
reinforcement member in the form of tower 18 or 24 being positioned
between the front and back sections before the back sections are
welded or bonded together. The tower and other similar metal
members for attachment or other purposes can thus be incorporated
into the seat frame or seat back during the manufacturing process,
thus facilitating attachment of the seat frame assembly to a
vehicle. It should be understood that the reinforcement tower or
other reinforcement member does not have to be inserted in the mold
cavity prior to joining the two molded halves. Instead, the
reinforcement member could be inserted after the product has been
formed and attached by interference fit, adhesion, or mechanical
fasteners. Even when the tower is inserted into the mold when the
sections are attached together, such fasteners may be used to
maintain the position of the tower in the seat back or the
like.
[0046] It will be understood by one having ordinary skill in the
art and by those who practice the invention, that various
modifications and improvements may be made without departing from
the spirit of the disclosed concept. Various relational terms,
including left, right, front, back, top, and bottom, for example,
are used in the detailed description of the invention and in the
claims only to convey relative positioning of various elements of
the claimed invention. The scope of protection afforded is to be
determined by the claims and by the breadth of interpretation
allowed by law.
* * * * *