Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Vehicle subsystem or accessory control
Reexamination Certificate
1998-06-11
2001-04-17
Nguyen, Tan (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Vehicle subsystem or accessory control
C280S732000, C180S268000
Reexamination Certificate
active
06219605
ABSTRACT:
The invention relates to a method and an air bag system for depleting the kinetic energy of a vehicle occupant in case of a vehicle accident involving heavy, negative acceleration, the air bag system comprising a control unit for inflating an air bag which activates the air bag system on the basis of electric signals of an acceleration sensor provided in the vehicle.
One such method and air bag system is known from EP 0 449 506 A1.
Should the vehicle be involved in a crash situation, so-called air bag inflators generate gas for inflating an air bag which then protects the vehicle occupants from impact with rigid internal parts of the vehicle such as the steering wheel. The physics involved in this simply mean that the vehicle occupant accelerated by the vehicle collision is decelerated or intercepted by the relatively soft air bag, with a gas mass flowing through so-called vent holes from the air bag for this purpose. Accordingly, the air bag has the task of depleting the kinetic energy of the occupant as “softly” as possible over a short distance.
Current air bag concepts mostly make use of inflators of the pyrotechnic type. Pyrotechnic-type inflators function in general such that an igniter in the inflator is ignited by a current pulse produced by a sensor system recognizing a vehicle crash situation. This ignition is boosted by a so-called booster charge generating hot particles which then impinge the surface of the gas generant mostly provided in the form of pellets which then automatically ignites and deflagrates in the so-called combustion chamber under a high pressure, thereby producing the gas for inflating the air bag. Since, in addition to a pure gas, fluid or solid constituents materialize during combustion, the gas flow is cleaned by corresponding filters in the filter chamber before emerging from the inflator.
The important thing in this respect is always ensuring complete combustion so that always the same amount of gas is generated once combustion of the gas generant has been initiated. Furthermore, the temperature of the generated gas is substantially influenced only by the ambient temperature existing on ignition of the gas generant, i.e. quite simply the cushioning performance provided by the air bag system is mainly influenced by the ambient temperature.
The air bag system known from EP 0 449 506 A1 comprises a two-stage inflator device for inflating the air bag. The two-stage configuration of the inflator device results in the air bag being initially slowly inflated in part in a first stage before being fully inflated as quickly as possible in a second stage. Between the first stage and the second stage of inflation a time delay is provided, designed to permit a more gentle cushioning of the vehicle occupant by the air bag. The known air bag is, nevertheless, totally inflated and with a high internal pressure so that it cannot be excluded that the vehicle occupant seated in front of the air bag is injured by the severe impact with the air bag.
In the case of the air bag system according to the teaching of EP 0 455 435 A2 the gas initially flows slowly into the air bag, and then fully inflates the air bag with maximum inflow velocity. This is also why no adaptation of the inflated air bag to the vehicle occupant seated in front of the air bag can be achieved by this two-stage configured air bag system, as a result of which with this air bag system too, injuries of the vehicle occupant seated in front of the air bag cannot be totally excluded, especially in the case of children.
Known from U.S. Pat. No. 5,219,178 is a further air bag system in which the gas produced for inflating the air bag is generated in two different chambers and in succession, as a result of which it can be achieved that as compared to prior art a greater amount of gas can be generated for inflating the air bag. Due to the two-stage inflator device the air bag is nevertheless always inflated to the same degree of hardness. Thus, in the case of this known air bag system too, a smaller and lighter vehicle occupant, for example a child, seated in front of the air bag may suffer injuries.
The present invention is thus based on the object of sophisticating the known method and air bag system such that, on the one hand optimum protection of the vehicle occupant seated in front of the air bag is assured and, on the other, injury of the vehicle occupant is avoided as far as possible.
This object is achieved by a method and an air bag system in which further sensor elements are provided by means of which such parameters are sensed which determine the individual kinetic energy of the vehicle occupant, and electrical signals representing these parameters are transmitted by the sensor elements to an electronic analyzer connected to the control unit, this electronic analyzer calculating on the basis of these signals a point in time t
4
at which the vehicle occupant is likely to come into contact with the inflated air bag of the air bag system, the electronic analyzer calculating on the basis of the established point in time t
4
a prior point in time t
2
at which the inflation of the air bag is to commence and which point in time t
2
is signalled to the control unit which activates inflation of the air bag at the point in time t
2
.
A very good characterization of the vehicle occupant seated in front of the air bag can be achieved by the sensor elements for the electronic control, so that optimum protection of the vehicle occupant is assured by the point in time of activation of the air bag system being matched to the vehicle occupant seated in front of the air bag and to the current circumstances of the crash situation. The air bag system is controllable by the method in accordance with the invention such that the necessary soft cushioning effect is always achieved for the vehicle occupant.
A further substantial advantage of the solution in accordance with the invention is that due to the point in time t
2
being established individually, the same components of the sensor system and inflators of the air bag system can also be put to use in totally different vehicles without it being necessary to adapt the hardware.
Especially preferred is a variant of the method in accordance with the invention, in which the electronic analyzer calculates on the basis of the signals from the sensors also a point in time t
3
located between the points in time t
2
and t
4
, at which point in time t
3
inflation of the air bag is to be completed and which is signalled to the control unit, the control unit then controlling the inflation process of the air bag such that the air bag is fully inflated at the point in time t
3
.
In one preferred embodiment of this variant of the method it is provided for that the ambient temperature of the air bag system is sensed by sensor elements and that the electronic analyzer establishes therefrom the likely degree of airbag inflation on completion of inflation and takes it into account in calculating the optimum point in time t
3
.
Preferably, use is made of control signals from the sensor elements for controlling ignition processes and/or starting a gas generating reaction. Gas generation may also occur intermittently, for example, by using a multi-stage inflator and thus can be configured variably to a major extent. As a result of this, differing degrees of airbag inflation can be produced and the cushioning effect can thus be adapted with the aid of the sensor elements to the kinetic energy of the vehicle occupant seated in front of the air bag.
Furthermore, the time profile of gas generation may be varied over a broad range by corresponding control signals,. this likewise contributing towards adjusting the cushioning effect optimally to the kinetic energy of the vehicle occupant.
The control unit regulates the amount of gas, the rate and pressure of inflation and adapts these variables determining the inflation response of the air bag specifically to the vehicle occupant characterized by the sensed parameters.
Particularly preferred also is a variant of the method in which c
Bauer Hermann
Bender Richard
Furst Franz
Nguyen Tan
Tarolli, Sundheim, Covell Tummino & Szabo L.L.P.
Tran Dalena
TRW Airbag Systems GmbH & Co. KG
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