U.S. patent application number 11/981160 was filed with the patent office on 2008-03-13 for assembly having steering wheel and gasbag module.
This patent application is currently assigned to TRW Automotive Safety Systems GmbH. Invention is credited to Andreas Heil, Michael Schneider.
Application Number | 20080060946 11/981160 |
Document ID | / |
Family ID | 33521718 |
Filed Date | 2008-03-13 |
United States Patent
Application |
20080060946 |
Kind Code |
A1 |
Heil; Andreas ; et
al. |
March 13, 2008 |
Assembly having steering wheel and gasbag module
Abstract
An assembly having a steering wheel (10) and a gasbag module
(16) that is connected to the steering wheel (10) includes a
generator support (20) formed of plastic for attaching a gas
generator (34). The generator support (20) in a predetermined area
is reinforced by a metal layer that is produced by electroplating
to a layer thickness sufficient to increase the strength of the
generator support (20) and the metal layer constitutes at least one
electrically conductive contact element (28).
Inventors: |
Heil; Andreas;
(Ashaffenburg, DE) ; Schneider; Michael;
(Sulzbach, DE) |
Correspondence
Address: |
TAROLLI, SUNDHEIM, COVELL, & TUMMINO L.L.P.
1111 LEADER BLDG.
526 SUPERIOR AVENUE
CLEVELAND
OH
44114-1400
US
|
Assignee: |
TRW Automotive Safety Systems
GmbH
|
Family ID: |
33521718 |
Appl. No.: |
11/981160 |
Filed: |
October 31, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11191570 |
Jul 28, 2005 |
|
|
|
11981160 |
Oct 31, 2007 |
|
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Current U.S.
Class: |
205/205 |
Current CPC
Class: |
H05K 1/11 20130101; H05K
1/0284 20130101; B60R 21/2037 20130101; B60Q 5/003 20130101 |
Class at
Publication: |
205/205 |
International
Class: |
C25D 5/56 20060101
C25D005/56 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 3, 2004 |
DE |
10 2004 037 462.7 |
Claims
1. A method for manufacturing an assembly comprising a steering
wheel (10) and a gasbag module (16) connected to the steering wheel
(10), the gasbag module (16) including a generator support (20)
formed of plastic for attaching a gas generator (34), the method
comprising the steps of: pretreating a surface of the generator
support (20) made of plastic in a predetermined area for generating
a surface roughness, and electroplating the pretreated surface to
form an adherently bonded, electrically conductive metal layer to a
layer thickness effective for increasing a strength of the
generator support.
2. The method of claim 1, wherein the pretreatment of the surface
includes a chemical etching and/or plasma etching.
3. The method of claim 1, further comprising a step of
electrolessly plating a metal onto said pretreated surface prior to
said electroplating step.
4. The method of claim 1, wherein the metal layer forms at least
one electrical contact element (28).
5. The method of claims 1, wherein the metal layer (32) is
deposited on a latching element (22) that is arranged on the
generator support (20).
6. The method of claim 1, wherein the metal layer is deposited in a
layer thickness of between 100 .mu.m and 2 mm.
Description
TECHNICAL FIELD
[0001] The present invention relates to an assembly having a
steering wheel and a gasbag module that is connected to the
steering wheel, the gasbag module including a support part formed
of plastic for attaching a gas generator.
BACKGROUND OF THE INVENTION
[0002] Gasbag modules are a component part of vehicle occupant
restraint systems and can be arranged, for example, in the steering
wheel to protect the driver. However, in this context, problems
arise with respect to the spatial arrangement of the contacts for
activating a horn signal, because a separate activation lever is
often hard to reach for the driver and in critical situations
cannot be located. According to the so-called "floating horn"
principle, gasbag modules are therefore arranged on the steering
wheel such that the horn signal can be activated by pressure that
is exerted by the driver on the gasbag module. In this context, one
contact is arranged on the gasbag module and one contact on the
steering wheel, and the gasbag module is connected to the steering
wheel by elastic spacers. In this way, the contacts can be closed
when a pressure is exerted on the gas bag module from a motion of
the gasbag module in the direction of the steering wheel, and in
this way the horn or another electrical function element can be
activated.
[0003] From DE 199 27 032 A1, an assembly is known that operates in
accordance with this principle and that has a steering wheel and a
gasbag module. The gasbag module includes a plastic generator
support, which is manufactured in an injection molding process and
into which a wire element is injected. The wire element has
hoop-shaped segments, which are provided with plastic sleeves for
electrical insulation and which engage in latching hooks that are
arranged on the steering wheel for the purpose of attaching the
gasbag module. The generator support also has one or more recesses,
in which the wire element is accessible and is not electrically
insulated. In these recesses, the wire element constitutes a
contact that activates the horn and that cooperates with an
electrically conductive opposite contact on the steering wheel.
When the contact and the opposite contact are closed through
pressure being exerted on the gasbag module in the direction of the
steering wheel, the electrical horn is activated.
SUMMARY OF THE INVENTION
[0004] It is an object of the present invention to provide a simply
designed and mechanically sturdy assembly having a steering wheel
and a gasbag module that is connected to the steering wheel, the
gasbag module including a generator support formed of plastic for
attaching a gas generator. According to the present invention, the
generator support in a predetermined area is reinforced by a metal
layer that is produced by electroplating to a layer thickness
effective to increase the strength of the generator support, the
metal layer constituting at least one electrically conductive
contact element.
[0005] The present invention therefore combines in one component
the functions of an electrical contact with a mechanical
reinforcement of the plastic generator support. In this way, it is
possible to manufacture the generator support so as to have a
reduced wall thickness and at the same time to assure the
mechanical load-carrying capacity even at boundary conditions at
high or low temperatures. In addition, the gas generator can be
manufactured with a less complex geometry, because the metal layers
perform the task of electrical leads and therefore no additional
components need to be integrated. Furthermore, the metal coating
improves the heat resistance and mechanical characteristics of the
generator support. Finally, the use of metal-coated plastics also
results in savings of weight.
[0006] It is especially preferred if the electrically conductive
contact element formed from the metal layer is a part of a
conducting track that is arranged on the generator support. In this
way, the opposite contacts on the steering wheel can also be
configured variably. These opposite contacts can be a fixed contact
element, e.g., a contact rivet, or a spring contact. The electrical
contact element preferably functions to activate an electrical
horn, in that it cooperates with the opposite contact on the
steering wheel in accordance with the so-called "floating horn"
principle.
[0007] In addition, it is preferable that the generator support
comprises a latching element, by which the generator support is
fixed in position on the steering wheel. The latching element can
specifically include a plastic latching hook that is formed
integrally with the generator support, the latching hook snapping
into a corresponding recess in the steering wheel or the steering
wheel skeleton. According to the present invention, the latching
hook is also reinforced by a metal layer that is formed by
electroplating. The metal layer on the latching hook and the metal
layer forming the electrical contact element can be applied in one
method step. They can constitute a functional unit, but they are
preferably kept electrically insulated from each other. Finally,
the gas generator can also have an exterior housing made of
plastic, which, for increasing the strength of the housing, can be
reinforced at least partially by a metal layer that is formed by
electroplating. The electrically conductive metal layer can
function particularly advantageously as a ground contact.
[0008] Reinforcing metal layers can be flexibly applied to plastics
through electroplating, and the process can be used in a simple
manner for forming separate metal layers that are electrically
insulated from each other in any shape and at any locations on the
generator support or other plastic parts of the gasbag module.
Therefore, the subject matter of the present invention is also a
method to manufacture an assembly having a steering wheel and a
gasbag module connected to the steering wheel, the surface of the
plastic generator support being pretreated in a predetermined area
for generating a surface roughness, and metal being then deposited
by electrolysis on the pretreated area to form an adherently bonded
metal layer in a layer thickness effective to increase the strength
of the generator support.
[0009] The thickness of the metal layers applied to the generator
support or to the plastic housing of the gas generator is
determined by the mechanical stresses to be expected on the
specific components, and it can be adjusted in wide ranges through
method parameters of the electrolytic deposition process such as
the duration of the electroplating, the strength of the current,
and the concentration of the electrolyte. The metal layers are
preferably between 100 .mu.m and about 2 mm thick. In layer
thicknesses less than 100 .mu.m, no improvement of the strength of
the generator support is to be expected. Layer thicknesses of more
than about 2 mm may be too expensive. The electrically conductive
metal layer can be applied to any plastic. Thermoplastic plastics
are preferred, specifically fiberglass-reinforced or
carbon-fiber-reinforced thermoplastics, due to their good strength
properties.
[0010] The pretreating of the plastic surface preferably includes a
chemical etching and/or a plasma etching, so that undercuts are
produced for the mechanical cramping of the metal layer on the
plastic surface. Then, the pretreated plastic surface in the areas
designated for coating is activated, for example using colloidal
palladium, and, for generating sufficient electrical conductivity,
is provided with a metal layer that is deposited by electroless
plating. The layer thickness of the metal layer that is deposited
by electroless plating can be up to 10 .mu.m. The metal layer that
is generated in this way is then reinforced by an electroplating
process using a suitable electrolyte, to arrive at the final layer
thickness.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 depicts a partial sectional view of the assembly
according to the present invention;
[0012] FIG. 2 depicts a top view of the lower side of a generator
support from the assembly according to FIG. 1; and
[0013] FIG. 3 depicts a schematic sectional view of the generator
support from FIG. 2.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0014] In FIG. 1, a steering wheel 10 is depicted, having an
exterior covering 12 made of plastic and a steering wheel skeleton
14 made of metal. On a central section of steering wheel skeleton
14, a gasbag module 16 is arranged. Gas bag module 16 includes a
driver-side cover 18 and a generator support 20 that is arranged on
the steering wheel side and that in a familiar manner is connected
in the area of a side wall to cover 18. On the base of generator
support 20, which is made of plastic, specifically a
fiberglass-reinforced or carbon-fiber-reinforced thermoplastic, one
or more latching hooks 22 are integrally formed, which snap into a
corresponding support 24 on the steering wheel skeleton and thus
fix generator support 20 and gasbag module 16 in position on the
steering wheel skeleton.
[0015] In addition, between the base of generator support 20 and
steering wheel skeleton 14, one or more elastic spacers 26 are
arranged, for example, a spiral spring, which adjust the distance
between steering wheel skeleton 14 and the base of generator
support 20. In addition, on the base of generator support 20, an
electrical contact element 28 is provided, which cooperates with an
opposite contact 30, for example a contact rivet, that is facing
the contact element 28 and is arranged on steering wheel skeleton
14.
[0016] In the idle position, spacer 26 presses latching hook 22
against support 24, so that electrical contact element 28 is
maintained at a defined distance from opposite contact 30. As a
result of a pressure on cover 18 in the direction of the steering
wheel, spacer 26 is compressed and a circuit is closed between
electrical contact element 28 and opposite contact 30. In this way,
an electrical function element, for example, an electrical horn,
can be activated.
[0017] Electrical contact element 28 on the base of generator
support 20 is applied through electroplating. In the embodiment
depicted in FIG. 2, by way of example, electrical contact element
28 is shown as part of a printed circuit that is made up of a
plurality of conducting tracks. In this manner, opposite contacts
30 can be variably placed on steering wheel skeleton 14. The layer
thickness of electrical contact element 28 and of the conducting
tracks is up to roughly 2 mm and is dimensioned such that the
strength of thin-walled generator support 20 is sufficient for the
stresses that arise under the conditions of use.
[0018] FIG. 3 shows that latching hooks 22 can also be reinforced
by a metal layer 32 that is deposited through electroplating. Metal
layer 32 and electrical contact element 28 in this embodiment are
electrically insulated from each other. The layer thickness of the
metal that is deposited onto latching hooks 22 is also up to about
2 mm.
[0019] Finally, gas generator 34, which is schematically depicted
in FIG. 1, can have an external housing 38 made of plastic, which
at least in some areas can be reinforced by a metal layer 40 that
is deposited by electroplating at a thickness of up to 2 mm, the
metal layer 40 increasing the strength of the plastic housing and
at the same time being able to perform the function of an
electrical lead or a ground contact.
[0020] To produce electrical contact element 28 on the base of
generator support 20, and, if appropriate, to deposit metal layer
32 onto latching hooks 22 and metal layer 40 on gas generator
housing 38, the plastic surface of generator support 20 or housing
38 is pretreated with a chemical etching in the areas in which the
electroplating is to be later carried out, in order to achieve
sufficient surface roughness and to generate undercuts for the
mechanical cramping of the metal layer to the plastic surface. In
place of the chemical etching, a plasma etching or a combination of
both methods can be employed. By pretreating the surface,
reaction-inhibiting oxide layers and impurities are also
removed.
[0021] Following the pretreatment of the plastic surface, the
roughened areas, for preparation for the electroplating, are
activated, for example, by being dipped into a solution of
colloidal palladium, rinsed, and, in an electroless process,
provided with a conductive metal layer. For this purpose, the
pretreated and activated plastic surface is dipped into a bath
which contains both a metal salt as well as a reducing agent. By
way of example, combinations of nickel salts with hypophosphite, or
copper salts and an organic reducing agent such as formaldehyde are
suitable. In this way, conductive metal layers are produced in a
desired pattern with layer thicknesses of up to 10 .mu.m. No metal
deposition occurs on plastic surfaces that are not roughened or
activated.
[0022] The conductive metal layers that are produced in this manner
are then connected to a current as the cathode in a suitable
electrolyte and are reinforced to the desired layer thickness by
electroplating. In this way, different electrically conductive
metals, such as nickel, copper, chromium, or silver, and
combinations thereof can be applied. With good adhesive strength,
the overall layer thickness can be up to 2 mm. The electrically
conductive metal layers at this thickness increase the strength of
the basic plastic component and at the same time can be used as
electrical contact elements and leads.
* * * * *