Land vehicles – Wheeled – Attachment
Reexamination Certificate
2000-08-07
2002-03-05
Dickson, Paul N. (Department: 3618)
Land vehicles
Wheeled
Attachment
C280S731000
Reexamination Certificate
active
06352280
ABSTRACT:
The invention relates to a steering wheel comprising a steering wheel skeleton consisting of a hub, spokes and a steering wheel rim, and an airbag module housed therein, which for actuation of the horn is arranged displaceably against a return force by the required contact path parallel to the steering wheel axis, at least two upwardly open fork-like support sites having locating holes extending approximately perpendicularly to the steering wheel axis being embodied in the steering wheel skeleton, downwardly angled mounting shackles having elongated holes extending in the direction of the steering wheel axis being embodied on or attached to a generator support of the airbag module in a way corresponding with the support sites, and the airbag module being joined to the steering wheel skeleton by means of retaining pins inserted in the locating holes and through the elongated holes. A steering wheel according to the preamble is known from JP-A-09/18 33 50.
Numerous proposals have already been made for attaching an airbag module within a steering wheel. If the steering wheels are attached by means of a nut screwed onto the thread end of the steering column during the final assembly, the airbag module cannot be inserted until the steering wheel has been assembled because it occupies the central region above the steering wheel hub which must remain freely accessible for screwing on the nut. If what is called integrated airbags shall be provided where the steering wheel is supplied together with the finally assembled airbag and mounted on the steering column, another steering wheel attachment must be supplied, for which proposals have also been made already. However, their handling creates more difficulty than that of the common steering wheel attachment which has a central nut and is tested a million times over.
With this version the airbag module cannot be installed—as stated already—until the steering wheel has been placed on the steering column and is attached thereto. For the attachment of the airbag module within the steering wheel, bolt connections must then be made available whose possible access cannot be provided on the top side of the steering wheel for optical reasons. The insertion of screws and the actuation of bolt connections from the rear side of the steering wheel are always difficult and time-consuming because of the spatial confinement. Since the automotive industry is striving for increasingly shorter final assembly times today, bolt connections and particularly those which have to be actuated from the rear side of the steering wheel, are considered extremely disadvantageous.
Therefore, it has also been tried already to attach airbag modules to the steering wheel by means of what is called snap-in or clip connections. However, it turned out that conventional connections of this kind are not suitable because they are not able to receive what is called the “ejection forces” occurring when an airbag is actuated or because these connections disengage as a result of the dynamic load. In the closed position, such connections are usually pretensioned to a certain degree, so that the snap-in or clip connection is secured and cannot disengage under standard conditions. However, when an airbag is inflated explosively, such connections are loaded within the meaning of an elimination of pretension, so that they can no longer reach reliably behind the snap-in protrusions when the directly following load occurs in the direction of pretension.
If the airbag cover shall be used for actuating the horn, the entire airbag module will have to be arranged displaceably by the required contact path within the steering wheel parallel to the steering wheel axis. For these uses, snap-in or latching connections are out of account because a permanent pretension of these connections is incompatible with the movability of the air bag required for closing the horn contacts in terms of design. Nevertheless, there is also a demand for reducing the time spent for installing the steering wheel and the airbag during the final assembly, if possible, and at the same time for reducing the space required for housing the airbag for such cases as well.
Therefore, the object is to provide a possibility according to which steering wheel and airbag module can be assembled finally as time-saving and space-saving as possible by retaining the common central attachment of the steering wheel to the steering column.
In order to achieve this object, it is proposed in connection with a steering wheel of the initially mentioned kind that sheet sections acting as leaf springs are arranged between the generator support and the steering wheel skeleton, which when in the assembled state support, at their end sides, on abutments at the steering wheel skeleton and pretension the airbag module against the horn actuation direction, plastics elements or a surrounding plastics ring being arranged between the sheet sections and the abutments and in the area of the fork-like support sites the retaining pins serve as an abutment for the plastics elements and the plastics ring, respectively.
With this proposal the steering-wheel can readily be placed on the steering column as usual and be bolted therewith before the airbag module is installed. The latter can be inserted in the pot-shaped steering wheel from above and be attached by retaining pins which can be inserted on the rear side of the steering wheel approximately perpendicularly to the steering wheel axis. The use of elongated holes enables the movability in the direction of the steering wheel axis, which is required for the actuation of the horn. For pretensioning the airbag module against the horn actuation direction, it is possible to return to known solutions.
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patent: 5593178 (1997-01-01), Shiga et al.
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patent: 6122992 (2000-09-01), Papandreou
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patent: 09183350 (1997-07-01), None
patent: 9815431 (1998-04-01), None
Dickson Paul N.
Draper Deanna
Tarolli, Sundheim, Covell Tummino & Szabo L.L.P.
TRW Automotive Safety Systems GmbH & Co. KG
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