Vehicle occupant restraint system

Details Vehicle occupant restraint system Vehicle occupant restraint system

1999-03-23

2001-02-20

Mai, Lanna (Department: 3619)

Land vehicles

Wheeled

Attachment

C280S735000, C280S731000, C280S743100

Reexamination Certificate

active

06189928

ABSTRACT:

BACKGROUND OF THE INVENTION
A typical vehicle occupant restraint system includes a gas bag transposable from a space-saving, folded resting condition into a deployed condition.
When necessary, the gas bag is transposed by means of an inflator from the folded resting condition into the deployed condition in which it restrains a vehicle occupant as specified. In the deployed condition the shape of the gas bag as well as its position in the vehicle interior relative to the vehicle occupant is usually dictated by the position, number and length of the catch straps arranged in the interior of the gas bag.
Because of the velocity with which the gas bag needs to be deployed so that it attains its optimum position in due time to cushion the vehicle occupant, injuries may occur if the wall of the gas bag during deployment impinges part of the body of the vehicle occupant. This problem is aggravated more particularly when the vehicle occupant happens to be not in his usual position at the point in time of activation of the gas bag, it being in this usual position that he has a predetermined minimum spacing away from the gas bag. Namely, the closer the vehicle occupant is located to the folded gas bag, the greater the likelihood of being hit by wall parts of the gas bag before the gas bag has attained its fully deployed condition, and the greater the energy of the wall parts with which the vehicle occupant comes into contact. Another problem in this respect is that one and the same gas bag needs to restrain vehicle occupants differing in constitution, i.e. to reliably restrain, for example, a heavy male vehicle occupant the gas bag needs to be designed substantially more voluminous than in the case of restraining for example a lighter female vehicle occupant. Accordingly, it is sometimes the case that the gas bag is deployed with unnecessarily high energy which increases the risk of injury.
The object of the invention is to provide a vehicle occupant restraint system including a gas bag posing as small a risk of injury as possible even in the case of an unfavorable vehicle occupant constitution or seating position.
BRIEF SUMMARY OF THE INVENTION
For this purpose, the invention provides a vehicle occupant restraint system including a gas bag transposable from a space-saving, folded resting condition into a deployed condition. A restraint means is provided which is capable of decelerating at least part of the wall of the gas bag in a controlled manner. The restraint means contains at least one coiling device. At least one catch strap is arranged in the interior of the gas bag and influences the shape of the gas bag in the deployed condition. The catch strap is at least in part accommodated on the restraint means when the gas bag is in the resting condition. The catch strap decisively influences by its length the shape of the gas bag in the deployed condition, i.e. the longer the catch strap the further the gas bag is able to deploy in the direction of the vehicle occupant. By adapting the length of the catch strap to the respective situation during deployment of the gas bag, it can be prevented that wall parts of the gas bag impinge parts of the body of the vehicle occupant with high energy, in other words severely hit the vehicle occupant. This adaptations is achieved by means of the coiling device which allows to adapt the length of the catch strap available during deployment in a simple manner to the requirements in each case by withdrawal of the catch strap from the coiling device being halted at an earlier or later point in time. Thereby, the part of the wall of the gas bag facing the vehicle occupant is unable to move toward the vehicle occupant without its velocity being decelerated, especially towards the end of the deployment, so that the risk of injury posed by the wall is minimized. Deceleration in a controlled manner, as provided by the restraint means, is here understood to be a deceleration as a function of parameters which are predeterminable by design.
In accordance with another preferred embodiment it may be provided for the coiling device comprises a braking mechanism capable of producing a deceleration of the catch strap and thus of the wall of the gas bag controlled in travel and time, following a specific deployment of the gas bag, up to standstill. This can be achieved simply by sensing either the length of the catch strap withdrawn from the coiling device or the time taken for withdrawing the catch strap and commencing deceleration as of a specific point in time. As a result of this, the wall of the gas bag is decelerated towards the end of the deployment action when there is an added risk of the vehicle occupant being hit, so that any impact occurs with diminished kinetic energy of the wall.
As an alternative, in accordance with the preferred embodiment, it may be provided for that the restraint means contains a sensor and the coiling device comprises a blocking mechanism which, controlled by an external signal of the sensor, causes deceleration of the wall up to standstill by means of the catch strap. The signal generated by the sensor then limits the length of the catch strap to a value at which the forward movement of the wall parts of the gas bag in the direction of the vehicle occupant is terminated in due time so that impingement of the wall parts of the gas bag with parts of the body of the vehicle occupant is either completely avoided or occurs at least at a significantly diminished velocity.
In this aspect it may be provided for that the sensor is capable of sensing the diving action of parts of the body of the vehicle occupant to be restrained into the gas bag, and of generating a signal thereupon. A sensor in this context is understood to be a sensing device, an analyzing device and a device for outputting a signal as a function of the actions sensed by the sensing device and analyzed by the analyzing device. By means of the sensor the deployment action can be adapted optimally to the respective situation. If, for instance, the sensor senses that the vehicle occupant is seated very near to the deployed gas bag or that a contact has already occurred between the wall of the gas bag and the vehicle occupant, the sensor is caused to output a signal which prevents any further increase in the length of the catch strap. In this way it is assured that the gas bag does not further deploy toward the vehicle occupant.
The sensor may comprise a contact surface area on the outer surface area of the gas bag facing the vehicle occupant to be restrained. The contact surface area forms in this case the sensing device by means of which on first contact between the wall of the gas bag and the vehicle occupant to be restrained the signal can be generated, whereupon a further increase in length of the catch strap is prevented. Thus, it is avoided that the gas bag deploys further toward the vehicle occupant. This reduces the energy with which the wall of the gas bag hits parts of the body of the vehicle occupant.
It may also be provided for that the sensor senses an approach of the gas bag outer surface area facing the vehicle occupant to be restrained and generates the signal before the outer surface area attains the vehicle occupant. In this way the deployment of the gas bag in the direction of the vehicle occupant is limited before vehicle occupant body parts are hit by the wall of the gas bag.
As an alternative it may also be provided for that the sensor contains a position sensor which senses the position of a vehicle occupant. Such a position sensor serving as the sensing device may contain an ultrasonic transceiver furnishing specific information as to the seating position of the vehicle occupant, on the basis of which it can be defined up to which size or in which shape the gas bag is preferably to be deployed.
In accordance with yet another preferred embodiment of the invention it is furthermore provided for that the gas bag features a variable filling volume. In this way the shape of the gas bag in the deployed condition can be further adapted to the respective situ

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