Land vehicles – Wheeled – Attachment
Patent
1997-11-12
2000-08-01
Culbreth, Eric
Land vehicles
Wheeled
Attachment
280736, B60R 2126
Patent
active
060955589
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a gas generator of sheet-metal constructional type for a motor vehicle passenger protection device.
Such a gas generator of the type described is known from DE-A1-41 21 039. Said gas generator is constructed concentrically, a combustion chamber with a gas-generating charge being disposed around an ignition chamber with an igniter and an ignition charge and the combustion chamber being surrounded by an expansion chamber. The expansion chamber contains a dust-collecting space and a cooling/expansion space. The gas escaping through discharge apertures from the combustion chamber is divided into a primary flow and a secondary flow. The primary flow is forced into the dust-collecting space, while the purified gas is conveyed through the cooling/filter space into the gas pocket of the air bag. By increasing the velocity of the escaping gas, a high separation efficiency is attainable. This is achieved by the intrinsic discharge energy of the gas.
SUMMARY OF THE INVENTION
The object underlying the invention is to improve a gas generator in such a way that low manufacturing costs, low weight and good recycling properties are combined with a small overall size.
This object is achieved according to the invention by having the sheet metal parts forming the combustion chamber and the expansion chamber connected to one another exclusively by metal-forming techniques. By metal-forming techniques are understood flanging, edge-rolling, riveting, wobble riveting, caulking, pressing and reaming.
By connecting the individual sheet metal parts exclusively by means of metal-forming techniques, it is possible to achieve low manufacturing costs simultaneously with a smaller overall size and a lower weight. Furthermore, by virtue of good recycling properties disposal is guaranteed.
In a preferred embodiment, the combustion chamber is formed by two sheet metal parts, of which the inner part comprises a cylindrical inner wall with a bottom piece bent over at right angles at one end and the outer part comprises a cylindrical outer wall with a top piece bent over at right angles at one end.
According to the invention, the ignition chamber is a prefabricated ignition element which is disposed in the cylindrical inner wall of the inner part of the combustion chamber. In this way, an extremely compact structural shape with few parts is achieved.
According to the invention, the sheet metal parts are steel plates, e.g. special steel 1.4301 or 1.4303 having a wall thickness of preferably around 1.0 to 1.5 mm.
The gas-generating charge in the combustion chamber is advantageously disposed in a hermetically sealed storage container. The latter is preferably made of aluminium and is manufactured by extrusion or deep drawing and is absolutely impervious to external moisture. The wall thickness of the storage container is preferably around 0.2 to 0.5 mm.
Spin-generating outlet apertures are disposed between the combustion chamber and the expansion chamber. In a preferred embodiment, these outlet apertures take the form of cowl-shaped protuberances of the cylindrical outer wall of the outer part of the combustion chamber. Such protuberances are formed by cutting into and pressing out the combustion chamber wall. Compared to prior art, it is therefore possible to dispense with an additional structural part.
The expansion chamber advantageously comprises a separation chamber adjoining the outlet apertures and a filter chamber lying, in the sense of the flow direction, downstream thereof, the escaping gas being redirected through about 180.degree. upon passing from the separation chamber to the filter chamber. As a result of such abrupt change in direction and in cooperation with the high centrifugal force caused by rotation of the escaping gas, a large proportion of the liquid and solid particles, which do not follow the change in direction, are separated from the gas flow.
The filter chamber is preferably occupied by a filter structure. As a result, a further filtering and cooling of the gas
REFERENCES:
patent: 5398967 (1995-03-01), Carothers et al.
patent: 5501487 (1996-03-01), Trevillyan et al.
patent: 5531474 (1996-07-01), Osborne et al.
Bayer Karl
Brede Uwe
Culbreth Eric
Dynamit Nobel GmbH Explosivstoff-und Systemtechnik
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