U.S. patent application number 09/127681 was filed with the patent office on 2002-04-18 for method of forming a motor vehicle instrument panel with a flexibly tethered air bag deployment door.
Invention is credited to FARRINGTON, STEPHEN D., GALLAGHER, MICHAEL J., GRAY, JOHN D..
Application Number | 20020043788 09/127681 |
Document ID | / |
Family ID | 46276256 |
Filed Date | 2002-04-18 |
United States Patent
Application |
20020043788 |
Kind Code |
A1 |
GALLAGHER, MICHAEL J. ; et
al. |
April 18, 2002 |
METHOD OF FORMING A MOTOR VEHICLE INSTRUMENT PANEL WITH A FLEXIBLY
TETHERED AIR BAG DEPLOYMENT DOOR
Abstract
A method of forming a motor vehicle instrument panel with a
flexibly tethered air bag deployment door comprises the steps of
molding an instrument panel with a first plastics material to a
desired shape and with an integral air bag deployment door whose
opening is defined by a tear seam formed by a groove molded in one
side of the panel and with an integral mounting/hinge flange that
extends from an inside surface of the door, and forming a bonded
layer of second plastics material on one side of the flange and the
inside surface of a potentially frangible portion of the door. The
second plastics material has the physical characteristic of
remaining ductile to a substantial degree at low temperatures
substantial below the temperature at which the first plastics
material becomes brittle and as a result the bonded layer forms a
tether that connects the frangible door portion to the
mounting/hinge flange in a flexible manner when this door portion
breaks away from the flange because of embrittlement of the first
plastics material at the low temperatures on tearing of the tear
seam and opening movement of the door by an inflating air bag
pressing against the inside surface of the frangible door
portion.
Inventors: |
GALLAGHER, MICHAEL J.;
(HAMPTON, NH) ; GRAY, JOHN D.; (UNION, NH)
; FARRINGTON, STEPHEN D.; (KINGSTON, NH) |
Correspondence
Address: |
Steven J. Grossman
HAYES, SOLOWAY, HENNESSEY, GROSSMAN & HAGE, P.C.
175 Canal Street
Manchester
NH
03101
US
|
Family ID: |
46276256 |
Appl. No.: |
09/127681 |
Filed: |
July 31, 1998 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
09127681 |
Jul 31, 1998 |
|
|
|
08426104 |
Apr 21, 1995 |
|
|
|
Current U.S.
Class: |
280/728.3 ;
280/732 |
Current CPC
Class: |
B29C 39/123 20130101;
B60R 2011/0094 20130101; B60R 13/0846 20130101; B60R 11/02
20130101; B60R 2011/0007 20130101; B60R 13/0275 20130101; B60R
13/0815 20130101; B29L 2031/3038 20130101; B60R 21/2165 20130101;
B60R 11/0211 20130101; B29C 37/0057 20130101; B60R 2011/0045
20130101; B60R 11/0205 20130101; B60R 2011/0276 20130101; B60R
2011/0092 20130101; B60R 2011/0043 20130101; B60R 11/0252 20130101;
B60R 21/216 20130101; B60R 2011/0096 20130101; B60R 2013/0287
20130101; B29C 45/16 20130101; B60R 13/0262 20130101; B60R
2021/21537 20130101; B60R 2011/0005 20130101; B60R 11/0229
20130101; B60R 2011/0082 20130101 |
Class at
Publication: |
280/728.3 ;
280/732 |
International
Class: |
B60R 021/16 |
Claims
What is claimed is:
1. A method of forming a motor vehicle instrument panel with an
integral air bag deployment door comprising the steps of: molding
an instrument panel with a first plastics material to a desired
shape and with an integral air bag deployment door whose opening is
at least partially defined by a tear seam formed by a groove molded
in one side of the panel; and forming a flexible bonded door
tethering layer of a second plastics material on an inside surface
of at least one of the instrument panel and door, and spanning a
frangible portion thereof at the inside surface wherein the second
plastics material has the characteristics of bonding to the first
plastics material and remaining ductile to a substantial degree at
low temperatures substantially below the temperature at which the
first plastics material becomes brittle to thereby form a flexible
tether that retains the frangible portion when the frangible
portion breaks away because of embrittlement of the first plastics
material at the low temperatures on tearing of the tear seam and
opening movement of the door by an inflating air bag pressing
against the inside surface of the door and wherein the tethering
layer is formed by injection molding the second plastics material
against the inside surface.
2. A method of forming a motor vehicle instrument panel with an
integral air bag deployment door comprising the steps of: molding
an instrument panel with a first plastics material to a desired
shape and with an integral air bag deployment door whose opening is
at least partially defined by a tear seam formed by a groove molded
in one side of the panel; and forming a flexible bonded door
tethering layer of a second plastics material on an inside surface
of at least one of the instrument panel and door, and spanning a
frangible portion thereof at the inside surface wherein the second
plastics material has the characteristics of bonding to the first
plastics material and remaining ductile to a substantial degree at
low temperatures substantially below the temperature at which the
first plastics material becomes brittle to thereby form a flexible
tether that retains the frangible portion when the frangible
portion breaks away because of embrittlement of the first plastics
material at the low temperatures on tearing of the tear seam and
opening movement of the door by an inflating air bag pressing
against the inside surface of the door and forming the tethering
layer by forming a mask having an opening conforming to a perimeter
of a desired tethering layer, laying the mask against the inside
surface, and spraying the second plastics material through the
opening in the mask and onto the inside surface to form the bonded
layer.
3. A method of forming a motor vehicle instrument panel with an
integral air bag deployment door comprising the steps of: molding
an instrument panel with a first plastics material to a desired
shape and with an integral air bag deployment door whose opening is
at least partially defined by a tear seam formed by a groove molded
in one side of the panel; and forming a flexible bonded door
tethering layer of a second plastics material on an inside surface
of at least one of the instrument panel and door, and spanning a
frangible portion thereof at the inside surface wherein the second
plastics material has the characteristics of bonding to the first
plastics material and remaining ductile to a substantial degree at
low temperatures substantially below the temperature at which the
first plastics material becomes brittle to thereby form a flexible
tether that retains the frangible portion when the frangible
portion breaks away because of embrittlement of the first plastics
material at the low temperatures on tearing of the tear seam and
opening movement of the door by an inflating air bag pressing
against the inside surface of the door and wherein the tethering
layer is formed by gravity molding the second plastics material on
the inside surface.
4. A method of forming a motor vehicle instrument panel with an
integral flexibly tethered air bag deployment door comprising the
steps of: molding an instrument panel with a first plastics
material to a desired shape and with an integral air bag deployment
door whose opening is at least partially defined by a tear seam
formed by a groove molded in one side of the panel; and forming a
flexible bonded door tethering layer of a second plastics material
on an inside surface of at least one of the instrument panel and
door, and spanning a frangible portion thereof at the inside
surface wherein the second plastics material has the
characteristics of bonding to the first plastics material and
remaining ductile to a substantial degree at low temperatures
substantially below the temperature at which the first plastics
material becomes brittle to thereby form a flexible tether that
retains the frangible portion when the frangible portion breaks
away because of embrittlement of the first plastics material at the
low temperatures on tearing of the tear seam and opening movement
of the door by an inflating air bag pressing against the inside
surface of the door and wherein the tethering layer is formed by
reaction injection molding the second plastics material on the
inside surface.
5. A method of forming a motor vehicle instrument panel with an
integral air bag deployment door comprising the steps of: molding
an instrument panel with a first plastics material to a desired
shape and with an integral air bag deployment door whose opening is
at least partially defined by a tear seam formed by a groove molded
in one side of the panel; and forming a flexible bonded door
tethering layer of a second plastics material on an inside surface
of at least one of the instrument panel and door, and spanning a
frangible portion thereof at the inside surface wherein the second
plastics material has the characteristics of bonding to the first
plastics material and remaining ductile to a substantial degree at
low temperatures substantially below the temperature at which the
first plastics material becomes brittle to thereby form a flexible
tether that retains the frangible portion when the frangible
portion breaks away because of embrittlement of the first plastics
material at the low temperatures on tearing of the tear seam and
opening movement of the door by an inflating air bag pressing
against the inside surface of the door and wherein the tethering
layer is formed by resin transfer molding the second plastics
material on the inside surface.
6. A method of forming a motor vehicle instrument panel with an
integral air bag deployment door comprising the steps of: molding
an instrument panel with a first plastics material to a desired
shape and with an integral air bag deployment door whose opening is
at least partially defined by a tear seam formed by a groove molded
in one side of the panel; and forming a flexible bonded door
tethering layer of a second plastics material on an inside surface
of at least one of the instrument panel and door, and spanning a
frangible portion thereof at the inside surface wherein the second
plastics material has the characteristics of bonding to the first
plastics material and remaining ductile to a substantial degree at
low temperatures substantially below the temperature at which the
first plastics material becomes brittle to thereby form a flexible
tether that retains the frangible portion when the frangible
portion breaks away because of embrittlement of the first plastics
material at the low temperatures on tearing of the tear seam and
opening movement of the door by an inflating air bag pressing
against the inside surface of the door and wherein the tethering
layer is formed by locating an injection mold tool against the
inside surface, and injection molding the second plastics material
in the mold tool against the inside surface.
7. A method of forming a motor vehicle instrument panel with an
integral air bag deployment door comprising the steps of: molding
an instrument panel with a first plastics material to a desired
shape and with an integral air bag deployment door whose opening is
at least partially defined by a tear seam formed by a groove molded
in one side of the panel; and forming a flexible bonded door
tethering layer of a second plastics material on an inside surface
of at least one of the instrument panel and door, and spanning a
frangible portion thereof at the inside surface wherein the second
plastics material has the characteristics of bonding to the first
plastics material and remaining ductile to a substantial degree at
low temperatures substantially below the temperature at which the
first plastics material becomes brittle to thereby form a flexible
tether that retains the frangible portion when the frangible
portion breaks away because of embrittlement of the first plastics
material at the low temperatures on tearing of the tear seam and
opening movement of the door by an inflating air bag pressing
against the inside surface of the door and wherein the tethering
layer is formed by locating a low pressure mold tool against the
inside surface, and molding the second plastics material in the
mold tool on the inside surface at a low pressure less than high
pressure injection molding.
8. A cover assembly for concealing an inflatable air bag system of
a motor vehicle, the assembly comprising: an instrument panel
comprising a first plastics material and configured to mount in the
passenger compartment of the motor vehicle; an air bag door panel
comprising the first plastics material and formed with the
instrument panel as a single integral panel, the door panel being
at least partially surrounded by the instrument panel; and a hinge
panel connected to an inside surface of the integral panel in a
layered disposition, the hinge panel being insert molded into an
inside surface of at least one of the instrument panel and the door
panel portions of the integral panel.
9. A cover assembly as defined in claim 8 in which a foam layer is
disposed over the integral panel and a plastic skin layer is
disposed over the foam layer.
10. A cover assembly as defined in claim 8 in which the hinge panel
spans a panel juncture zone between the door panel and the
instrument panel.
11. A cover assembly as defined in claim 10 in which the panel
juncture zone includes a styling groove separating at least a
portion of the door panel and the instrument panel.
12. A cover assembly as defined in claim 11 in which the styling
groove is configured to function as a tear seam.
13. A cover assembly as defined in claim 10 in which the panel
juncture zone includes a weakened tear seam separating at least a
portion of the door panel and the instrument panel.
14. A cover assembly as defined in claim 13 in which the hinge
panel includes a hinge panel edge aligned with at least a portion
of the tear seam.
15. A cover assembly as defined in claim 8 in which the hinge panel
comprises a second plastics material.
16. A cover assembly as defined in claim 15 in which the second
plastics material is more ductile and less brittle at low
temperatures than the first plastics material.
17. A cover assembly as defined in claim 8 in which the hinge panel
comprises metal.
18. A cover assembly as defined in claim 8 in which the door panel
includes a hinge flange extending transversely inward from the
inside surface, the hinge flange configured to secure the door
panel to a structural member, the hinge panel spanning the hinge
flange and door panel in a layered disposition, a portion of the
hinge panel being attached to the hinge flange.
19. A cover assembly as defined in claim 8 in which: the instrument
panel includes a collar extending transversely inward from the
inside surface and from around the door panel, the collar defining
a door-collar interface along the region where the collar extends
from the integral panel; and the hinge panel spans the door-collar
interface, one portion of the hinge panel being attached to the
collar and another portion of the hinge panel being attached to the
door panel.
20. A cover assembly for concealing an inflatable air bag system of
a motor vehicle, the assembly comprising: an instrument panel
comprising a first plastics material and configured to mount in the
passenger compartment of the motor vehicle; an air bag door panel
comprising the first plastics material and formed with the
instrument panel as a single integral panel, the door panel being
at least partially surrounded by the instrument panel; and a hinge
panel connected to an inside surface of the integral panel in a
layered disposition, the hinge panel spanning a panel juncture zone
between the door panel and the instrument panel.
21. A cover assembly as defined in claim 20 in which the hinge
panel comprises a second plastics material and is attached to the
inside surface of the integral panel and is insert-molded into an
inside surface of at least one of the instrument panel and the door
panel.
22. A cover assembly as defined in claim 21 in which the second
plastics material is more ductile and less brittle at low
temperatures than the first plastics material.
23. A cover assembly as defined in claim 20 in which at least a
portion of the panel juncture zone includes a styling groove.
24. A cover assembly as defined in claim 20 in which at least a
portion of the panel juncture zone includes a weakened tear
seam.
25. A cover assembly as defined in claim 24 in which the hinge
panel includes a peripheral hinge panel edge aligned with at least
a portion of the tear seam.
26. A cover assembly as defined in claim 20 in which the hinge
panel comprises metal.
27. A cover assembly as defined in claim 20 in which: the
instrument panel includes a collar extending transversely inward
from the inside surface and from around the door panel defining a
door-collar interface; and the hinge panel spans the door-collar
interface, a portion of the hinge panel being attached to the
collar.
28. A method for making an air bag cover assembly, the assembly
including an instrument panel comprising a first plastics material
and configured to mount in a motor vehicle passenger compartment,
an air bag door panel comprising the first plastics material and
formed with the instrument panel as a single integral panel, the
door panel being at least partially surrounded by the instrument
panel, and a hinge panel connected to an inside surface of the
integral panel in a layered disposition, the hinge panel being
insert molded into an inside surface of at least one of the
instrument panel and the door panel; the method comprising the
steps of: providing a mold having first and second mold portions,
the first and second mold portions forming a mold cavity when
closed together, the mold cavity having a shape complementing the
shape of the integral panel and hinge panel; forming the hinge
panel; placing the hinge panel in the second mold portion; closing
the mold; introducing the first plastics material into the mold
cavity in molten form; allowing the molten first plastics material
to conform to the shape of the mold cavity and to cure in the mold
cavity; and opening the mold and removing the completed assembly
from the mold.
29. The method of claim 28 in which the step of forming the hinge
panel includes the step of forming a hinge panel comprising a
second plastics material.
30. The method of claim 29 in which the step of forming the hinge
panel includes the step of providing a second plastic material that
is more ductile and less brittle at low temperatures than the first
plastics material.
31. The method of claim 28 in which the hinge panel comprises sheet
metal.
32. The method of claim 28 in which the step of placing the hinge
panel includes the step of placing the hinge panel in the second
mold portion in a position spanning a portion of the mold
configured to form the panel juncture zone between the instrument
panel and door panel portions of the integral panel.
33. The method of claim 28 in which the step of providing a mold
includes the step of shaping the lower surface of the mold cavity
to form a hinge-flange that protrudes transversely inward from the
door panel portion of the integral panel and in which the step of
placing the hinge panel includes the step of placing the hinge
panel in the second mold portion in a position spanning a portion
of the mold configured to form a flange juncture zone between the
hinge-flange and the door panel.
Description
TECHNICAL FIELD
[0001] This invention relates to motor vehicle instrument panels
having an integral air bag deployment door defined by a tear seam
and more particularly to a tether for a potentially frangible air
bag door when it is separated at very low temperatures from the
instrument panel and then because of cold embrittlement from a
flexible hinge that is integral with the door and normally provides
through bending movement for opening swinging movement of the door
and its retention to the vehicle structure at higher
temperatures.
BACKGROUND OF THE INVENTION
[0002] Presently, most passenger side air bag doors are formed in
an air bag cover that is separate from the instrument panel because
the latter is made of various commercially available thermoplastic
materials that are particularly well suited to meeting the
requirements of its application but are not well suited to meeting
the requirements of an air bag door that is defined by a tear seam
formed in a single layer instrument panel. For example, the
plastics materials used to make such an instrument panel must have
a certain degree of stiffness and high heat resistance to meet the
requirements of its application but the materials that are
currently available for such an application do not retain ductility
and become embrittled at very low or cold temperatures. This lack
of low temperature ductility is undesirable for air bag deployment
where the air bag door is formed integral with and defined by a
tear seam that is formed in the instrument panel and is torn to
provide an air bag deployment opening in the panel by the force of
the inflating air bag acting on the panel in the area of the tear
seam. Styrene-maleic anhydride, polypropylene, polycarbonate,
polyphenylene oxide and polyurethane are examples of thermoplastic
materials that are suitable for such an instrument panel but have
not exhibited the required ductility for such a tear-open air bag
door at very low temperatures and as a result a portion or portions
of the door may fracture and separate from the instrument panel on
deployment of the air bag and undesirably enter the space of the
passenger compartment. To meet extreme low temperature
requirements, many various designs of an air bag deployment door
have been proposed wherein the door is made separate from the panel
and is installed as a hinged door assembly on the instrument panel
so that the door is not prone to fracture from cold embrittlement
by the force of the inflating air bag as it freely swings open on
its hinge from the force of the air bag.
[0003] Costs can be reduced, quality can be improved and styling
can be enhanced by molding the instrument panel and the air bag
cover including an integral air bag deployment door in one piece at
the same time out of the same commercially available material. That
is provided that the normal material requirements for the
instrument panel are not sacrificed while the safe assured
operability of the integral air bag deployment door is still
somehow retained at reasonable cost even though its plastics
material is not well suited thereto.
SUMMARY OF THE PRESENT INVENTION
[0004] In the present invention, a molded motor vehicle instrument
panel made of a thermoplastic material well suited for the primary
purpose of such a panel has an integral air bag deployment door for
a passenger side air bag that is safely retained to the vehicle
structure in a very cost effective manner. The air bag door is
defined by a tear seam in the panel and is normally retained by an
integral flexible mounting/hinge flange to a part of the vehicle
structure when the seam is torn by the inflating air bag and
wherein this flange which before was integral with both the door
and the panel is then separated from the main body of the panel
while remaining integral with the door and bends to allow the door
to swing open to allow deployment of the air bag through an opening
in the instrument panel while retaining same to the vehicle
structure as the door is then free of the instrument panel. At very
low temperatures, a portion of the air bag door can break away from
the mounting/hinge flange where it joins therewith because of
plastic embrittlement at these low temperatures and the high
bending stresses encountered at this juncture.
[0005] This separation of the broken door portion from the vehicle
structure is prevented by bonding a layer of second plastics
material over the juncture zone and an adjoining inside surface of
the potentially frangible door portion and an adjoining one side of
the mounting/hinge flange. The second plastics material has the
physical characteristic of remaining ductile to a substantial
degree at low temperatures substantially below the temperature at
which the first plastics material becomes brittle. The bonded layer
thus forms a tether that tethers the frangible door portion to the
mounting/hinge flange in a flexible manner when this door portion
breaks away from the flange because of embrittlement of the first
plastics material at the low temperatures on tearing of the tear
seam and opening movement of the door by the inflating air bag
pressing against the inside surface of the frangible door portion.
This allows the broken door portion to continue movement in it
opening direction to allow continued deployment of the air bag
while the broken door portion remains connected by the flexible
tether to the mounting/hinge flange and thereby the vehicle
structure.
[0006] The instrument panel and the air bag deployment door
tethering layer may be formed in various ways including injection
molding the panel and injection molding, spraying or low pressure
molding the tethering layer in a second step. Such formation of the
tether in place as a bonded layer is particularly advantageous from
both a cost and production standpoint as it becomes integral with
the instrument panel and there is no need to inventory a separate
tether that must then be fastened by some form of fastening means
to both the mounting/hinge flange and the door. Furthermore, the
bonding of the tethering layer to the inside surface of the door
hides its presence from view which is desirable from an appearance
or styling standpoint.
[0007] It is therefore an object of the present invention to
provide a new and improved method of forming a motor vehicle
instrument panel with an integral air bag deployment door and a
flexible tether for the door.
[0008] Another object is to provide a new and improved method of
forming a motor vehicle instrument panel with an integral air bag
deployment door and a flexible tether for the door at low cost and
of high quality and to meet certain styling desires.
[0009] Another object is to provide a method of forming a motor
vehicle instrument panel with a tethered air bag deployment door
wherein the panel including the door is formed of a plastics
material suited to meet the requirements of an instrument panel and
the tether is formed of a layer of plastics material that spans a
potential fracture zone in the door and remains ductile at low
temperatures that cause embrittlement of the door that could result
in the fracturing of a portion of the door at thus fracture zone on
air bag deployment and loss of its retention to the vehicle
structure but for the tethering layer.
[0010] Another object is to provide a method of forming a motor
vehicle instrument panel including an air bag deployment door that
is defined by a tear seam molded in the panel wherein the panel is
formed of a plastics material suited to its requirements and the
door is retained to the vehicle structure on breaking away at very
cold temperatures by a flexible layer of plastics material that is
formed in place over an inside surface of the door and one side of
a mounting/hinge flange that is molded integral with the inside
surface of the door and normally retains the air bag door to the
vehicle structure on opening movement.
[0011] Another object is to provide a low cost, high quality motor
vehicle instrument panel with flexibly tethered air bag deployment
door produced by the above method.
[0012] A second aspect of the present invention includes an
automotive air bag cover assembly comprising a hinge panel that is
connected, in a layered disposition, to an inside surface of at
least one of the integral air bag cover and instrument panel. The
instrument panel comprises a first plastics material and is
configured to mount in the passenger compartment of the motor
vehicle. The air bag door panel also comprises the first plastics
material and is formed with the instrument panel as a single
integral panel. The door panel is at least partially surrounded by
the instrument panel. One object of this second aspect of the
present invention is to simplify and accelerate the manufacture of
hinged integral panels by providing a hinge panel that is insert
molded into an inside surface of at least one of the instrument
panel and the door panel.
[0013] Another object of the second aspect of the present invention
is to provide a hinge panel to act as a primary hinge between the
door panel and the instrument panel during air bag deployment. The
hinge panel spans a panel juncture zone between the door panel and
the instrument panel.
[0014] Another object of the second aspect of the present invention
is to aid in bending the first plastics material at the hinge
location by providing a panel juncture zone that includes a styling
groove separating at least a portion of the door panel and the
instrument panel. The styling groove may also function as a tear
seam.
[0015] Another object of the second aspect of the present invention
is to guide tearing around the door panel when the air bag inflates
by providing a panel juncture zone that includes a weakened tear
seam separating at least a portion of the door panel and the
instrument panel.
[0016] Another object of the second aspect of the present invention
is to provide a hinge that includes a hinge panel edge aligned with
at least a portion of the tear seam to act in guiding tearing along
the tear seam as the door is forced open during air bag
inflation.
[0017] Another object of the second aspect of the present invention
is to prevent hinge panel fracture at low temperatures by providing
a hinge panel comprising a second plastics material that is more
ductile and less brittle at low temperatures than the first
plastics material.
[0018] Another object of the second aspect of the present invention
is to prevent hinge panel fracture by providing a hinge panel
comprising metal.
[0019] Another object of the second aspect of the present invention
is to provide a means of securing the door panel to a structural
member during deployment by providing a hinge flange that extends
transversely inward from the inside surface of the door panel. The
hinge flange is configured to secure the door panel to a structural
member. The hinge panel spans a juncture zone between the hinge
flange and door panel in a layered disposition with a portion of
the hinge panel being attached to the hinge flange.
[0020] Another object of the second aspect of the present invention
is to provide a means for supporting an air bag canister assembly
on the instrument panel by providing a collar that extends
transversely inward from the inside surface of the instrument panel
and from around the door panel. The collar defines a door-collar
interface along the region where the collar extends from the panel.
The hinge panel spans the door-collar interface, one portion of the
hinge panel being attached to the collar and another portion of the
hinge panel being attached to the door panel.
[0021] Another object of the second aspect of the present invention
is to provide a method for making an air bag cover assembly. The
method includes providing a mold having first and second mold
portions. The first and second mold portions form a mold cavity
when closed together. The mold cavity has a shape that complements
the shape of the integral instrument and door panel and the hinge
panel. After being formed separately, the hinge panel is placed in
the second mold portion. The mold is then closed and the first
plastics material is introduced into the mold cavity in molten
form. The molten first plastics material is then allowed to conform
to the shape of the mold cavity and to solidify in the mold cavity.
The mold is then opened and the completed assembly is removed from
the mold.
[0022] The method may also include formation of the hinge panel
from the second plastics material and the selection of a second
plastic material that is more ductile and less brittle at low
temperatures than the first plastics material.
[0023] The method may alternatively include the provision of a
hinge panel comprising metal. In applications where an edge of the
hinge panel is aligned with a tear seam to guide tearing along the
tear seam, metal is generally preferred over plastic due to
increased rigidity which aids in evenly distributing door opening
forces along a tear seam to promote more uniform tear seam fracture
and subsequent door opening.
[0024] The method may also include the placement of the hinge panel
on the mold cavity surface of the second mold portion in a position
spanning a portion of the mold configured to form the panel
juncture zone between the instrument panel and door panel portions
of the integral panel. The mold cavity surface of the second mold
portion may be shaped to form a hinge-flange that protrudes
transversely inward from the door panel portion of the integral
panel. In this case, the hinge panel is placed on the mold cavity
surface of the second mold portion in a position spanning a portion
of the mold configured to form a flange juncture zone between the
hinge-flange and the door panel.
[0025] These and other objects, advantages and features of the
present invention will become more apparent from the following
description and the accompanying drawings wherein:
BRIEF DESCRIPTION OF THE DRAWINGS
[0026] FIG. 1 is a perspective view of a motor vehicle instrument
panel including integral air bag deployment door with a flexible
tether made according to the present invention and as installed in
a motor vehicle over an air bag system;
[0027] FIG. 2 is an enlarged view taken along the line 2-2 in FIG.
1 when looking in the direction of the arrows;
[0028] FIG. 3 is a view taken along the line 3-3 in FIG. 2 when
looking in the direction of the arrows;
[0029] FIG. 4 is a view like FIG. 2 but showing the air bag door
opened and broken during the deployment of the air bag at a very
low temperature;
[0030] FIG. 5 is a fragmentary perspective view of mold tools used
to mold the flexible tethering layer in FIGS. 2 and 3 and includes
a sectional view of the instrument panel as molded and then located
between these tools for the molding of the flexible tethering
layer;
[0031] FIG. 6 is view taken along the line 66 in FIG. 5 when
looking in the direction of the arrows;
[0032] FIG. 7 is a sectional view of the instrument panel as molded
without the flexible tethering layer and includes a diagrammatic
view of spraying apparatus for forming the flexible tethering
layer;
[0033] FIG. 8 is a cross-sectional side view of a motor vehicle
instrument panel constructed according to the invention and
including an integral air bag deployment door in a closed position,
a plastic insert molded hinge and an integral mounting/hinge
flange;
[0034] FIG. 9 is a cross-sectional side view of the instrument
panel of FIG. 8 with the air bag deployment door being moved out of
the closed position by an inflating air bag;
[0035] FIG. 10 is a cross-sectional side view of the instrument
panel of FIGS. 8 and 9 with the air bag deployment door being
fractured as it is moved out of the closed position by an inflating
air bag;
[0036] FIG. 11 is a perspective view of a motor vehicle instrument
panel including integral air bag deployment door having a plastic
insert molded hinge constructed according to the present invention
and as installed in a motor vehicle over an air bag system;
[0037] FIG. 12 is a cross-sectional side view of the instrument
panel and air bag system of FIG. 11 with the air bag deployment
door in a closed position;
[0038] FIG. 13 is a cross-sectional side view of the instrument
panel and air bag system of FIG. 11 with the air bag deployment
door being moved out of the closed position by air bag
inflation;
[0039] FIG. 14 is a cross-sectional side view of a motor vehicle
instrument panel constructed according to the invention and
including an integral air bag deployment door and including a metal
insert molded hinge; and
[0040] FIG. 15 is a cross-sectional side view of a motor vehicle
instrument panel constructed according to the invention and
including a collar extending transversely inward from an inside
surface of the instrument panel, an integral air bag deployment
door in a closed position and a plastic insert molded hinge.
DETAILED DESCRIPTION OF THE DRAWINGS
[0041] Referring to FIGS. 1-4, there is illustrated a molded
instrument panel air bag cover assembly 10 for concealing an
inflatable air bag system of a motor vehicle. The motor vehicle
structure is generally designated as 11. Alternative embodiments of
the instrument panel cover assembly 10 are generally shown at 10a
in FIGS. 8-10, 10b in FIGS. 11-14, and 10c in FIG. 15. Reference
numerals with the suffix "a" in FIGS. 8-10, the suffix "b" in FIGS.
11-14 and the suffix "c" in FIG. 15 designate the alternative
configuration of each element common to the embodiment of FIGS.
1-4. Unless the description indicates otherwise, where the
description uses a reference numeral to refers to an element in
FIGS. 1-4, I intend that portion of the description to apply
equally to elements in FIGS. 8-10, 11-14 and 15; indicated by the
same reference numeral with the suffix "a", "b" or "C";
respectively.
[0042] The cover assembly 10 has a contoured section 12 on the
driver side for the installation of an instrument cluster (not
shown) and an air bag deployment door 14 of rectangular shape on
the passenger side that is defined by a tear seam 16 molded in the
cover assembly. The tear seam 16 may be formed by a groove either
in the face of the panel as shown or by a similar groove in the
back side of the panel to hide the tear seam from view as is well
known in the art. The cover assembly covers an air bag system 18
that is located behind the cover assembly directly behind the air
bag door 14 and is mounted on a sheet metal portion 20 of the
vehicle structure at the front of the passenger compartment. The
air bag system 18 is of a conventional type that includes an
inflatable air bag 22, a gas generator 24 and a controller 26 that
includes a vehicle impact sensor and triggers ignition of the gas
generator to inflate the air bag for deployment into the passenger
space 28 directly in front of a passenger seated on this side.
[0043] The cover assembly 10 is a molded one-piece part of
generally uniform wall thickness and is formed of a suitable
thermoplastic material such as styrene-maleic anhydride,
polypropylene, polycarbonate, polyphenylene oxide and polyurethane
that provides sufficient stiffness so that the panel is
self-supporting to maintain the desired shape and has sufficient
heat resistance to resist deformation due to heat in its interior
vehicle environment where it is located immediately behind the
windshield (not shown). The cover assembly may be molded in various
conventional ways including injection molding as is well known in
the art. The groove forming the tear seam 16 is made deep enough in
relation to the wall thickness of the cover assembly and the
strength of the plastic material used so as to sufficiently weaken
the wall section at the tear seam to the point that it is torn by
the force of the inflating air bag acting against the back or
inside surface of the air bag door and creates on its separation
from the cover assembly an opening 30 therein for the deployment of
the air bag as illustrated in FIG. 4 and described in more detail
later.
[0044] The cover assembly 10 is fastened to portions of the vehicle
structure 11 at various locations outside the area of the air bag
door with one such location being shown in FIG. 2 wherein a sheet
metal screw 32 fastens the panel at a lower edge thereof beneath
the air bag door to a sheet metal portion 34 of the vehicle
structure. In addition, it will be understood that similar screws
or other conventional type fasteners are used at other locations
outside the area of the air bag door to securely fasten the cover
assembly in place on the vehicle structure.
[0045] The air bag deployment door 14 in the cover assembly 10 is
separately fastened to the vehicle structure by an elongated
mounting/hinge flange 36 that is molded integral with the back
inside surface of the door and extends horizontally along
substantially the entire length and adjacent to the upper edge
thereof as seen in FIGS. 1-3. The flange 36 has a flat rectangular
portion 38 that extends inwardly of the door a substantial distance
and terminates in a flat, rectangular, angled, horizontally
extending, distal portion 40 that is fastened along its length by
bolts 42 to a sheet metal portion 44 of the vehicle structure. The
flange 36 is also formed with a controlled thickness and is capable
of elastic bending to a significant degree in the rectangular
portion 38 in a certain substantial temperature range and down to a
certain low temperature (e.g. -20.degree. F.) without breaking and
thereby act as a cantilever hinge to normally provide for outward
swinging opening movement of the door when the door is separated
along the tear seam from the cover assembly for air bag deployment.
Prior to such air bag door separation, the flange 36 acts to fasten
the cover assembly to the vehicle structure at the air bag door and
also provides support for the latter against a pushing force such
as from a passenger which could otherwise push the door inward and
separate the door from the cover assembly along the tear seam.
[0046] The flange 36 is designed to normally hinge and retain the
air bag door 14 to the vehicle structure during its outward opening
movement when the tear seam 16 is torn by the force of the
inflating air bag and in doing so is highly stressed at its
juncture 48 with the door as the flange portion 38 bends to effect
swinging movement of the door. However, at very low or cold
temperatures such as -20.degree. F. and below, the typical plastic
material suitable for the cover assembly in its primary application
can become brittle to the point where the lower and major portion
46 of the door, that is forced by the inflating air bag to bend
outward about the horizontally extending juncture 48 of the door
with the flange 36, may fracture or break off at this highly
stressed location or zone (see FIG. 4) and enter into the passenger
space 28. This is prevented in a very cost effective manner by the
strategic addition of a flexible door tethering layer 50 of
controlled thickness that is formed in place over the one side 52
of the mounting/hinge flange 36 adjoining the potential fracture
zone 48, over this zone, and over the inside surface 54 of the
potentially frangible door portion 46. The material forming the
door tethering layer 50 is a flexible plastics material of a
prescribed controlled thickness that is formed in place as
described in more detail latter, bonds in its formation without an
added adhesive to the material of the cover assembly, and remains
flexible or ductile at temperatures substantially below that at
which the material of the cover assembly 10 including the integral
air bag deployment door 14 becomes brittle. Examples of such
material for the tethering layer 50 that will remain flexible or
ductile at temperatures as low as -60.degree. F. are polyurethane
elastomers, polyester elastomers, and polyolefin elastomers. In
addition, it will be understood of course that the tethering
material while well suited for its application is not suited to
meet the stiff requirements of the cover assembly.
[0047] The flexible tethering layer 50 extends horizontally
substantially the entire length of the mounting/hinge flange 36 and
is bonded to the side 52 of the flat flange portion 38 at a margin
portion 56 of the tethering layer that extends laterally to the
distal flange portion 40 so as to maximize the bonding area on this
side of the potential fracture zone 48 and thereby maximize the
retention of the tethering layer to the flange 36. The tethering
layer 50 spans and is bonded to the potential fracture zone 48 at
an intermediate portion 58 of the tethering layer and is bonded to
the inside surface 54 of the potentially frangible air bag door
portion 46 at a margin portion 60 that extends laterally to near
the lower edge of the door so as to maximize the bonding area of
the tethering layer with this door portion and its retention to the
flange 36.
[0048] Referring to FIG. 4, the tethering layer 50 at its
intermediate portion 58 that spans the potential fracture zone
flexes when door breakage occurs because of cold plastic
embrittlement to permit the broken door portion 46 to continue to
swing outward and upward about the line of fracture at the flange
36 to provide for continued air bag deployment while retaining the
broken door portion safely to the vehicle structure with the
tethering layer 50 and flange 36. The bonded retention of the
tethering layer over substantially the entire inside surface of the
separated door portion 46 and that of the bending portion 38 of the
flange 36 maximizes the retention forces available from the
tethering layer 50 across the door fracture to retain the broken
door portion 46 to the flange 36 and thus to the vehicle structure.
And the controlled thickness of the tethering layer 50 is
determined in relation to the tensile strength of it plastics
material so as to not fail in bending tension at its intermediate
portion 58 at the greatest anticipated forces acting thereon from
the propelled mass of the broken door portion 46. However, it will
also be understood that the intermediate bending portion 58 of the
tether layer 50 could have a greater thickness than the adjoining
margin portions 58 and 60 for greater tensile strength as necessary
in a particular application to conserve material and/or space.
[0049] The cover assembly 10 including the integral air bag
deployment door 14 and the mounting/hinge flange 36 is molded in
one-piece at one time of the same plastics material such as that
previously described which is suitable for the primary purpose of
an cover assembly wherein it must be sufficiently stiff for self
support and resistant to heat. The cover assembly 10 is molded in a
conventional manner well known in the art and may be formed for
example in an injection mold or reaction injection mold whose mold
cavity completely defines the surfaces of the cover assembly
including the groove defining the tear seam 16 in either the
outside or inside surface.
[0050] Referring to FIGS. 5 and 6, there is shown the appearance
side mold tool 70 of an injection mold used to mold the appearance
or front side of cover assembly 10 which is shown in place as
molded thereby in these illustrative views and wherein the flexible
tethering layer is yet to be formed. And it will be understood that
the injection mold for the cover assembly 10 further includes
another mold tool (not shown) that defines the back side of the
panel and cooperates with the mold tool 70 to form a mold cavity
into which the plastics material for the panel is injected in
molten form under pressure in a conventional manner. With the
molded cover assembly 10 left in place in the mold tool 70 and the
back side mold tool moved out of the way, the air bag deployment
door tethering layer 50 may then be formed in place with an
injection mold tool 72 that seats against the inside surface of the
cover assembly over the area in which the tethering layer 50 is to
be formed and which includes the side 52 of the mounting/hinge
flange 36 and the inside surface 54 of the frangible door portion
46. It will also be understood that the cover assembly could be
supported by a dedicated support tool that is much smaller than the
cover assembly mold tool 70 and has a similar support surface that
just spans the area of the outer side of the molded cover assembly
opposite where the tethering layer is to be formed. The injection
mold tool 72 is formed on its molding side with a tethering layer
defining cavity 74 that is closed by the side 52 of the
mounting/hinge flange 36 and the inside surface 54 of the frangible
door portion 46 and defines therewith a closed mold cavity 76 that
defines the entirety of the tethering layer shape.
[0051] The mold tools 70 and 72 with the cover assembly 10 located
there between are clamped together in a conventional type plastics
injection molding machine (not shown) and the tethering plastics
material as earlier described is injected in molten form under high
pressure in a conventional manner through a passage 78 in the mold
tool 72 into the closed mold cavity 76 to form the flexible
tethering layer 50. It will also be understood that a low pressure
mold tool with a tethering layer defining mold cavity like the
cavity 74 in mold tool 72 but with the low pressure mold tool
suitably adapted in a conventional manner for gravity molding,
reaction injection molding, or resin transfer molding of the
tethering layer with reactive components of the plastics material
can also be used to mold the tethering layer in place on the inside
surface of the cover assembly. In either case, the plastics
material forming the tethering layer bonds without an added
adhesive to the inside surface of the cover assembly to form a
strong attachment thereto over the entire extensive interface
between the tethering layer 50 and both the mounting/hinge flange
36 and the frangible door portion 46.
[0052] The tethering layer 50 may also be formed in place on the
inside surface of the cover assembly by spraying the tether forming
plastics material as illustrated in FIG. 7. This is preferably
accomplished with a mask 80 of controlled thickness that is laid
against the side 52 of the mounting/hinge flange 36 and the inside
surface 54 of the frangible door portion 46 in interfacing
relationship therewith and has an opening 82 that defines the
periphery of the tethering layer 50. The mask 80 has the desired
thickness of the tethering layer or a slightly greater thickness
and may be formed of metal or plastic and either be flexible so as
to readily conform to the surface to be masked or be preformed with
the required interfacing shape. The mask 80 is held in place by
suitable means such as by flanges 84 fixed to a robot arm and the
outer surface 86 of the mask is coated with a suitable release
agent such as silicone to prevent the tether forming plastics
material from adhering thereto.
[0053] With the mask 80 held in place on the inside surface of the
cover assembly, the tether forming plastics material is sprayed
through the mask opening 82 onto the unmasked area of the panel to
form the tethering layer 50 using a conventional type plastics
spraying system 88 that includes a suitable mixing head 90 having a
spray wand 92. The spraying system 88 operates in a conventional
manner to effect spraying on command and wherein reactive
components of the plastics material are delivered to the mixing
head 90 by separate lines 94 and 96 and these components are mixed
in the mixing head just prior to spraying with the wand 92. The
mixing head 90 may be manipulated by an operator or a robot and the
mixed plastics material is dispensed from the mixing head through
the spray wand onto the unmasked area of side 52 of the
mounting/hinge flange 36 and the inside surface 54 of the frangible
door portion 46 as illustrated in FIG. 7 to form the tethering
layer to the desired controlled thickness. Then on setting of the
sprayed plastics material, the mask is removed leaving the
tethering layer in place and bonded without adhesive to the cover
assembly.
[0054] Summarizing examples of the plastics materials that can be
used in the above molding processes to form the tethering layer;
the gravity molding material can be a thermoset material such as
polyurethane, the resin transfer molding material can be a
thermoset material such as polyester, the reaction injection
molding material can be a thermoset material such as polyurethane,
the spray molding material can be a thermoset material such as
polyurethane, and the injection molding material can be
thermoplastic material such as polyolefin.
[0055] As shown in FIGS. 8-10, 11-14 and 15, respectively, the
second, third and fourth embodiments 10a-c of the cover assembly 10
each comprise an instrument panel generally indicated at 100a-c. In
each of these embodiments the instrument panel 100a-c comprises a
first plastics material and is configured to mount in the passenger
compartment of the motor vehicle. An air bag door panel shown at
14a-c also comprises the first plastics material and is formed with
the instrument panel 100a-c as a single integral and unitary panel
14a-c, 100a-c. The door panel 14a-c is at least partially
surrounded by the instrument panel 100a-c.
[0056] In each of the second through fourth embodiments, a hinge
panel, shown at 50a-c, is connected to an inside surface 102a-c of
the unitary panel 14a-c, 100a-c in a layered disposition. The
inside surface 102a-c is disposed opposite an outside or "class A"
surface 104a-c of the unitary panel 14a-c, 100a-c. The hinge panel
50a-c comprises a second plastics material that is more ductile and
less brittle at low temperatures than the first plastics material.
The hinge panel 50a-c is insert molded into an inside surface of at
least one of the instrument panel 100a-c and the door panel 14a-c.
As shown at 50b' in FIG. 14, in other embodiments the hinge panel
50 may comprise sheet metal or both sheet metal and plastic. Metal
is especially advantageous as a component of an aft edge of the
hinge panel aligned with a tear seam due to increased rigidity
which aids in distributing door opening forces more evenly along
the tear seam to promote more uniform tear seam fracture and
subsequent door opening.
[0057] As shown in FIGS. 8-15, the hinge panel 50a-c includes a
hinge panel aft edge 110a-c aligned with an aft portion of the tear
seam 16a relative to the direction of door opening during air bag
inflation. The alignment of the aft portion of the tear seam 16a
and the hinge panel aft edge 110a-c helps to guide tearing along
the tear seam 108.
[0058] As shown in FIGS. 8-10, the door panel 14a of the second
embodiment includes a hinge flange 36a extending transversely
inward from the inside surface 54a. As is described in detail with
respect to the first embodiment, above, the hinge flange 36a is
configured to secure the door panel 14a to a structural member 44a.
The hinge panel 50a spans a flange juncture zone, shown at 112a in
FIGS. 8-10, where the hinge flange 36a integrally extends from the
inside surface of the door panel 14a. The hinge panel 50a acts as a
secondary hinge and a tether in the event the door panel 14a should
fracture at the flange juncture zone 112a--or at any other point
spanned by the hinge panel 50a. The hinge panel 50a is attached to
the hinge flange 36a and door panel 14a in a layered disposition by
insert molding.
[0059] As is also shown in FIGS. 8-10, a forward tear seam portion
108a of the weakened tear seam 16a runs parallel to and adjacent
the panel juncture zone 112a of the second embodiment. The forward
tear seam portion 108a delineates a boundary between a forward
portion of the door panel 14a and the instrument panel 100a. The
forward tear seam portion 108a completes a full 360.degree. tear
seam path for the tear seam 16a that defines the entire outline of
the air bag door panel 14a. Therefore, upon air bag inflation, the
entire door panel 14a is torn free of the instrument panel 100a and
is tethered only by the hinge flange 36a. Alternatively, the
forward tear seam portion 108a may be omitted.
[0060] As shown in FIGS. 11-14, the hinge panel 50b of the third
embodiment spans a panel juncture zone 106b between the door panel
14b and the instrument panel 100b. The hinge panel 50b acts as a
secondary hinge between the door panel 14b and the instrument panel
100b during air bag deployment. The hinge panel 50b may lie flush
with the inside surface. However, in other embodiments, the hinge
panel 50b may be molded in a raised position to allow for a
constant thickness of the first material over the unitary panel
14b, 100b.
[0061] As shown in FIGS. 11-14, the panel juncture zone 106b of the
third embodiment may include a styling groove 108b separating at
least a portion of the door panel 14b and the instrument panel
100b. The styling groove 108b may be formed by methods other than
injection molding such as laser scoring, cutting or melting. The
styling groove 108b promotes upward bending of the first plastics
material at the hinge location by removing material that would
otherwise impede such upward bending.
[0062] As shown in FIG. 14, a urethane foam layer 120 may be
disposed over the unitary panel 14b and a plastic skin layer 122
may be disposed over the foam layer. While the foam and skin layers
120, 122 are shown on the unitary panel 14b of the embodiment of
FIG. 14, such layers may also be included in any embodiment of the
invention.
[0063] As shown in FIG. 15, the instrument panel 100c of the fourth
embodiment includes a collar 114 that integrally extends
transversely inward from the inside surface 102c and from around
the door panel 14c. The collar 114 defines a door-collar interface
116 along a region where the collar 114c extends from the unitary
panel 14c, 100c. The collar 114 forms a sleeve for receiving an air
bag canister assembly 18c. In other embodiments, the collar 114 may
serve as a guide chute for a deploying air bag. The hinge panel 50c
spans the door-collar interface 116. An inner portion 56c of the
hinge panel 50c is attached to the collar 114 and an outer portion
60c of the hinge panel 50c is attached to the door panel 14. A
styling groove 108c may be aligned with the portion of the
door-collar interface 116 that the hinge panel 50c spans. The
styling groove 108c is formed into the outside or "class A" surface
104c to aid upward bending of the door panel 14c.
[0064] In practice, air bag cover assemblies 10a-c can be made by
first providing a mold having first and second mold portions. The
first and second mold portions form a mold cavity when closed
together. The mold cavity has a shape that complements the shape of
whichever unitary panel 14a-c, 100a-c and hinge panel 50a-c is to
be formed. A hinge panel 50a-c is formed from the second plastics
material, metal or a combination thereof and is placed in the
second mold portion. The hinge panel 50 is placed in a portion of
the mold cavity in the second mold portion in a position spanning a
portion of the mold configured to form the juncture zone 112a, 106b
or interface 116 between the door panel 14a-c and either the
instrument panel 100b of the second embodiment, the hinge flange
36a of the third embodiment or the collar 114 of the fourth
embodiment.
[0065] For example, to form a cover assembly 10a according to the
second embodiment, i.e., a hinge-flange version of the invention,
the mold cavity surface of the second mold portion is shaped to
receive the hinge-flange 36a. The hinge panel 50a is placed on the
mold cavity surface of the second mold portion in a position
spanning a portion of the mold configured to form the flange
juncture zone 112a between the hinge-flange 36a and the door panel
14a. In this case, the mold cavity surface of the second mold
portion has a shape complementing that of the inside surface 102a
of the unitary panel 14a, 100a. The mold is then closed by
positioning the first mold portion on the lower mold portion. The
first mold portion includes a mold cavity surface shaped to
complement the shape of the outside or "class A" surface 104a of
the unitary panel 14a, 100a. The first plastics material is then
introduced into the mold cavity in molten form. The molten first
plastics material is allowed to conform to the shape of the mold
cavity and to solidify in the mold cavity. The mold is then opened
and the completed assembly 10a is removed from the mold with the
hinge panel 50a molded into the unitary panel 14a, 100a as shown in
FIG. 8.
[0066] The invention has been described in an illustrative manner
with respect to presently preferred embodiments, and it is to be
understood that the terminology that has been used is intended to
be in the nature of words of description rather than words of
limitation. obviously, many modifications and variations of the
present invention in light of the above teachings may be made. It
is therefore to be understood that within the scope of the appended
claims, the invention may be practiced otherwise than as
specifically shown and described.
* * * * *