Land vehicles – Wheeled – Attachment
Reexamination Certificate
1999-07-08
2001-05-08
Johnson, Brian L. (Department: 3618)
Land vehicles
Wheeled
Attachment
C280S740000, C280S737000
Reexamination Certificate
active
06227567
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to an airbag module with a gas distributor.
BACKGROUND OF THE INVENTION
Intelligent restraining systems or airbag systems for motor vehicles using various sensors to determine whether a vehicle occupant is located directly in the space where the airbag is deployed have been under development for some time. When the airbag is deployed the quantity of gas flowing into the airbag will be reduced as much as possible, in order to avoid any injuries owing to the airbag. To date, multistage gas generators have been used predominantly to set the quantity of the gas flowing into the airbag. In these multistage gas generators, the total quantity of gas generant is subdivided into a plurality of units that are ignited either all at the same time or with a time offset, or of which only individual units are ignited. In the case of so-called hybrid gas generators, the ignition of only one stage ensures that the entire compressed gas already flows into the airbag. The ignition of a second, or further stages then leads only to a rise in temperature and thus a rise in pressure of the gas, but increases the volume of gas only insignificantly. However, the mass of gas exerts a substantial influence on the energy of the unfolding airbag, and is therefore also attended by a possible risk of injury to a vehicle occupant from the airbag.
The two-stage gas generators used to date are of very complicated construction, with the result that these gas generators also entail increased production costs. Furthermore, particularly in the case of the hybrid gas generators, it is difficult to reduce the volume of the gas flowing into the airbag, should this be desired.
Also known are airbag modules in which gas distribution devices are arranged on the gas generator. These gas distribution devices provide outflow openings that are sealed by means of flaps. These flaps can be opened if appropriate, with the result that some of the gas flows off not into the airbag, but into the environment through the outflow openings. The volume of the gas flowing into the airbag can therefore be reduced. However, such a gas distribution device permits only indirect, and thus imprecise, setting of the volume of gas flowing into the airbag. The mass of gas flowing into the airbag can be reduced by this device only to a specific value, a further reduction beyond this value being impossible.
It is the object of the invention to create an improved airbag module that has a gas distributor and permits a more precise setting of the mass of gas entering the airbag.
The object is achieved by means of an airbag module with a gas distributor that is arranged between a gas generator and an airbag.
In the airbag module according to the invention, a gas distributor is arranged between a gas generator and an airbag. The gas distributor has at least a first and a second flow path for a gas. At least one valve device for opening or closing the respective flow path is arranged in each case in the flow paths. In this case, the first flow path connects the gas generator to the airbag, while the second flow path is not connected to the airbag. Because of this arrangement, it is possible, by appropriately driving or setting the valve devices, for the gas generated by the gas generator to be introduced specifically into the airbag through the first flow path, or to be led off from the airbag through the second flow path. It is possible for a superfluous quantity of gas which is not required to fill the airbag or, because of a specific position of a vehicle occupant, is not desired to be led off via the second flow path so that it does not flow into the airbag. It is also possible to reduce the cross section of the first flow path by means of a valve device located therein, and thus to reduce the quantity and/or mass of the gas flowing into the airbag. When the valve device in the first flow path is completely closed, it is possible virtually entirely to prevent gas flowing into the airbag. Depending on the configuration of the valve device, it is then only a residual quantity of gas that flows into the airbag. As a rule, this residual quantity cannot be avoided, since no sealing means which could seal completely are provided on the valve devices used here. However, such a residual quantity of gas, for example 20% of the normal quantity which flows into the airbag, is insignificant, since it cannot fill the airbag to such an extent that the latter can pose a risk of injury to a vehicle occupant.
The second flow path advantageously connects the gas generator to at least one outflow opening. This outflow opening is advantageously arranged such that the outflowing gas flows away from the vehicle occupant. In the case of a driver's or passenger's airbag, such an outflow opening is therefore preferably positioned such that the gas flowing out through it is led off into the instrument panel of the motor vehicle. Thus, a superfluous quantity of gas, which is not required in a specific case to fill the airbag because the latter is not to be completely filled owing to a specific position of the vehicle occupant to be protected, can be safely disposed of without the risk of injury to the vehicle occupant from hot gas which is led off into the environment.
The valve devices are preferably coupled in such a way that the total flow cross section of the flow paths remains constant in each position of the valve devices. It can be ensured in this way that when one of the valve devices is being closed the total flow cross section through which the gas generated by the gas generator can flow off is not reduced to such an extent as to cause an impermissible increase in the gas pressure in the gas generator or the gas distributor. Given appropriate coupling of the valve devices, it can be ensured that when one valve device reduces the cross section of a flow path, the other valve device simultaneously enlarges the cross section of the other flow path by the same amount so that the total flow cross section remains essentially constant, and actuating the valve devices cannot lead to an increase in the internal pressure in the gas generator and in the gas distributor.
It is preferred to provide at least one explosive propellant charge for actuating the valve devices. Such a propellant charge comprises, for example, a detonating pill that, like the gas generator as well, can be ignited electrically by an appropriate control device. The propellant charge then abruptly generates a specific quantity of gas that, for example, can drive in the valve device a piston that actuates the latter to change the flow cross section in the appropriate flow path. The actuation of the valve devices by propellant charges has the advantage of permitting an exceptionally rapid actuation of the valve devices such as is required in the case of an airbag module whose airbag is deployed in a few milliseconds. In a way that is also preferred, the propellant charges actuate the valve devices in such a way that the latter virtually completely seal or completely open the appropriate flow path. Absolutely tight sealing of the flow paths is mostly not necessary, and so it is possible to do without expensive seals.
It is expedient to provide locking means for locking the valve devices in predetermined valve positions. These locking means permit the valve devices to be fixed in their end positions so that they cannot move back unintentionally, for example because of vibrations which are acting on the airbag module, something which could lead to re-release or resealing of the corresponding flow path, and thus to malfunctioning of the airbag module. The locking means are preferably constructed in the form of latching or clamping means which reliably retain the valve devices in the appropriate positions.
The valve devices of the first and the second flow paths advantageously have at least one common, movable slide, it being the case that the first flow path is open and the second flow path is closed in a first position of the slide, and the first flow pat
Breed Automotive Technology Inc.
Drayer Lonnie R.
Johnson Brian L.
Luby Matthew
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