Land vehicles – Wheeled – Attachment
Reexamination Certificate
1998-12-03
2001-12-04
Rice, Kenneth R. (Department: 2167)
Land vehicles
Wheeled
Attachment
C280S728200
Reexamination Certificate
active
06325411
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a device for suspending a mobile module in a motor vehicle, according to the preamble of appended claim
1
. In particular, the invention relates to a device in which an airbag module in the steering wheel device of the vehicle is adjusted to function as a tuned vibration attenuator.
BACKGROUND OF THE INVENTION
Modern motor vehicles are often equipped with at least one airbag in order to protect those travelling in the vehicle. In a known manner, this airbag is arranged to, in case of a collision with the vehicle, be activated by means of an acceleration sensor and to be inflated by means of a gas generator, so that gas flows into the airbag which is then formed to a soft cushion which suppresses the forward motion of the person travelling in the vehicle. As regards the driver of the vehicle, he is normally protected by means of an airbag which is arranged in the hub of the steering wheel of the vehicle. For this purpose, an airbag module which comprises the airbag and the gas generator used for inflating the airbag can be arranged in the hub of the steering wheel.
When the engine idles the steering wheel normally vibrates at a certain frequency, which frequency is ca. 30-40 Hz in modern vehicles. If an airbag module of the above-mentioned kind is arranged in the steering wheel, a considerable weight is added, which might cause the natural frequency of the steering system of the vehicle to decrease. In case of unfavourable circumstances which i.a. depend on the choice of idling rpm of the engine, the natural frequency can interact with the idling frequency of the engine, thus causing greatly amplified vibrations in the steering wheel.
These amplified vibrations are naturally perceived as something negative by those travelling in the vehicle, in particular by the driver of the vehicle since he is holding the wheel.
There is thus a need for an improved suspension of an airbag module arranged in the steering wheel of a vehicle which enables the vibrations in the steering system and the wheel to decrease. In particular, it is desirable to ensure that the frequency of resonance for the airbag module does not coincide with the vibration frequency at the idling rpm of the vehicle.
The airbag module is furthermore arranged to activate an airbag in a predetermined manner. In particular, it is necessary for the airbag, when triggered, to be inflated in a well defined direction relative to the person intended to be protected. A drawback of known suspension devices for airbag modules is that there is a risk that the airbag is inflated somewhat obliquely, e.g. in the wrong direction relative to the person. As a result, the airbag will not have the intended protective effect. For this reason, there is a need for devices which provide a correct guidance of the airbag when inflating.
A previously known device which relates to a suspension device for an airbag module is shown in patent document U.S. Pat. No. 5,024,464. This device comprises an airbag module which is arranged at a steering wheel via an elastic organ. The airbag module then functions as a vibration attenuator which causes a reduction of the vibrations in the steering wheel. The elastic organ comprises a stop element in the shape of a stud, around which an elastic casing-like element is arranged. The stop element prevents the airbag module from moving upwards more than a certain distance.
SUMMARY OF THE INVENTION
A main object of the present invention is to solve the above-mentioned problem, and to provide an improved device which in particular is intended for vibration attenuating suspension of a mobile module, preferably an airbag module in a steering wheel device in a motor vehicle. This is obtained by means of a device of the initially mentioned kind, the characteristics of which will become evident from appended claim
1
.
A further object of the invention is to provide a device for correct guidance of an airbag module when inflating an airbag. This object is obtained by means of a device, the characteristics of which will become evident from appended claim
14
.
The invention is intended for the suspension of a mobile module, e.g. an airbag module, relative to a steering wheel device in a motor vehicle and comprises an attenuating element for the attenuation of vibrations, which attenuating element in turn comprises a body of elastic material which is fixedly attached to a part of said module, and which is fixedly attached to said steering wheel device. In this way, efficient attenuation of vibrations is enabled, as is a simple fitting of the module in the steering wheel device. In particular, the area, the thickness, the shearing module and similar parameters of the element can be controlled, so that the airbag module vibrates in counter-phase relative to the vibrations of the steering system, which causes reduced vibrations in the steering wheel. The vibration frequency of the airbag module can be tuned by choice of material and elastic properties of the attenuating element.
In particular, the frequency of resonance of the airbag module is prevented from coinciding with the idling rpm of the vehicle. In this way, the airbag module can be made to function as a tuned vibration attenuator, which vibrates in counter-phase relative to the rest of the steering wheel device, thus reducing vibrations.
The term “steering wheel device” here relates not only to the steering wheel as such, but also to its corresponding parts in the wheel/steering system of the vehicle, e.g. the hub of the wheel, the spokes and the console parts.
Advantageous embodiments will become evident from the appended dependent claims.
REFERENCES:
patent: 5024464 (1991-06-01), Kawaguchi et al.
patent: 5383682 (1995-01-01), Nagata et al.
patent: 5593178 (1997-01-01), Shiga et al.
patent: 0572125 (1993-12-01), None
patent: 0 636 808 A1 (1995-02-01), None
patent: 4-143143 (1992-05-01), None
patent: 6-270817 (1994-09-01), None
patent: 96/24511 A2 (1996-08-01), None
Fosse Tore
Rigner Lars
Jasmin Lynda
Kilpatrick & Stockton LLP
Rice Kenneth R.
Volvo Car Corporation
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