Gas generator

0001The invention relates to a gas generator, with a pyrotechnic biasing propellant containing a combustion chamber and the propellant charge Bias unit.

0002The set in an inflator for vehicle occupant restraint systems Propellant is mechanically biased so that it while the years of driving operation can not move. Especially in a tablet form Propellant filling this is important because the tablets would mutually rub together and wear out. The previously used Biasing units are for example springs or foam inserts. On pyrotechnical gas generator is usually closed by welding, said here must be ruled out that while by Funkensprung the welding of the pyrotechnic propellant charge is ignited.

0003The invention provides a gas generator which is easy to fill and its Items can be easily welded together.

0004The gas generator according to the invention of the aforementioned type is characterized by a holding means in the biasing unit a predetermined position secured, holds compressed position and the releasable is designed to release the bias unit selectively, so that they in a Release position arrives in which it exerts a biasing force on the propellant charge.

0005The hitherto conventional biasing units, including springs, were usually first introduced into the combustion chamber, and then the propellant was introduced into the pushed combustion chamber under application of external forces, so that the Spring compressed. Still other systems before saw that the Blind Combustion chamber after the filling of the propellant charge closed with a lid is, on the inside of the bias unit sits.

0006The invention, however, provides that the bias unit of the filling Gas generator due to the holding device in a compressed position is held without being here exerts the biasing force on the propellant charge. In this position is the bias unit more compressed than in the subsequent Release position, in which it only the biasing force on the propellant charge exercises and results in a non-position-secured position, consisting of a balance of power between the bias unit and the counterpressure of the propellant results. Due to the location secured, compressed position, the Propellant are filled without and subsequently during the filling Closing the combustion chamber pressure in the propellant be exercised have to be. In addition, allowed before the compressed position, the combustion chamber their close not completely fill with propellant charge, so that the propellant charge during Close the combustion chamber, in particular by welding this Joint may be sufficiently spaced. Thus, there is no Risk of ignition of the propellant charge during the closing of the generator or the Combustor. Only after closing the holding device can be released, whereby the biasing unit reaches the release position.

0007The holding device according to the preferred embodiment, a mechanical Latch that at, for example, on the combustion chamber wall, Outer housing of the gas generator or, in the preferred embodiment engaging another portion of the bias unit, so that this in latter case, forms a self-contained unit, which itself in the holds compressed position stable.

0008The bias unit should be a pre-assembled unit, is indicated as such can be used in the compressed position in the combustion chamber, which facilitates assembly.

0009eg The bias unit has a propellant charge the facing front wall, a propellant charge the remote backplane and an intervening elastic spring element is so constructed of very few parts.

0010The front and the rear wall are selectively by the holding means in the compressed position firmly and at a constant distance from each other connected and are in the release position decoupled. "Decoupled" Namely, the front and the rear wall are disengaged from each other so that the Front wall can move freely against the propellant charge.

0011The holding means includes, for example, projecting from the front wall Appendages, for example, attack on the rear wall. Of course one could also be reversed the rear wall carrying the projections which engage the front wall.

0012For easy and quick release is preferably provided that the holding device a rotation lock, in particular bayonet and having Turn the shutter reaches the release position.

0013The combustion chamber is bounded on the outside by a combustion chamber wall, wherein the bias unit at one axial end of the preferably elongate, cylindrical combustion chamber is located. The opposite end of the combustion chamber is the filling side of the propellant charge and the side of the combustion chamber or of the entire generator, in particular by the after filling Welding is closed.

0014The bias unit is particularly on the axial end in befüllseitige introduced the combustion chamber and is located laterally on the latter to stable, so that the Movement of the bias unit can only be in one direction.

0015The bias unit is unsecured housed in the combustion chamber, as An embodiment provides, that a positive connection between the combustion chamber wall and the biasing unit is not required. The Bias unit is rather between an axial end of the combustion chamber wall and the propellant charge clamped.

0016The invention is not limited to pure pyrotechnic inflators. The preferred embodiment even provides an elongated hybrid inflator before, in which the combustion chamber of a gas-filled pressure chamber surrounded.

0017Further features and advantages of the invention will become apparent from the following Description and from the following drawings, to which reference is taken. In the drawings:<ul><li>Figure 1 is a schematic partially sectioned view of an inventive Gas generator,</li><li>2 shows a slightly modified form of the already illustrated in Figure 1 Combustor liner with integrated bias unit, and</li><li>Figure 3 is a plan view of the rear wall of the employed in the invention Bias unit.</li></ul>

00181 shows a hybrid gas generator 10 is shown, elongated with one, cylindrical outer housing 12 that encloses a pressure chamber filled with a pressurized medium 13, for example a noble gas such as argon or Helium is filled. The outer housing 12 has an elongated shape and has a peripheral wall 14 extending in the axial direction A at both ends of the inflator 10 tapered.

0019At an axial filling end of the gas generator 10 are a cup-shaped Lid 15 and an ignition unit 16 connected to it, which by known conventional hybrid inflators. In the example shown here is the ignition unit 16 opposite to the pressure chamber by a membrane 17 closed, which is destroyed upon activation of the igniting unit sixteenth At the the opposite axial end of the gas generator 10 are outflow openings 22 and a throttle device 18 and provided a closure membrane 20th After opening the closure membrane 20, the pressure chamber is fluidly connected via the throttle device 18 with the discharge ports 22, so that Gas can escape from the gas generator 10th

0020Inside the outer housing 12 is an elongated combustion-chamber wall 24 was added as an insert, in which the combustion chamber 25 is formed is filled with a tablet-shaped propellant 26th The propellant charge 26 is housed exclusively in the combustion chamber 25th A first axial end 28 the combustion chamber 25 adjacent to the throttle device 18, while a second axial end 29 of the combustor 25, also known as the filling end, on the part of Ignition unit 16 is located.

0021The combustion chamber wall 24 is produced by a perforated plate and limited the combustion chamber radially outward. The combustion chamber wall 24 has the first End 28 large flow openings 32 and ends on the first end 28 in a frustoconical chamfer 34. Throughout its entire circumference , the tubular combustion chamber wall 24 additionally smaller openings 40 on.

0022At the second end 29 a chamfer 45 is also provided with which the combustion chamber wall 24 at the conically tapering in this area Peripheral wall 14 rests. By the chamfers 34, 45 is the combustion chamber wall 24 both radially and axially fixed in position in the outer casing 12th

0023In the area of ​​the end 28 50 is a biasing unit in the combustion chamber 25 and ensures that the propellant charge is biased 26th

0024The bias unit 50 consists of three parts, as in Figure 2 it easier to is seen, namely a front wall 52 in Figure 1 in two positions is shown, a provided with a large flow opening, annular Rear wall 54 and a between the walls 52, 54 arranged, symbolically Spring shown 56 that seeks to track the two walls 52, 54 axially apart from each other. The front wall 52 is formed crown-shaped, and has on the rear wall 54 facing, integrally molded finger-like extensions its outer edge, namely the circumference four longer, the rear wall 54 in a position (compressed position) engages behind projections 58, and between the longer projections 58 in contrast to these at the free end not angled, short extensions 60 that the frontal free end of the Rear wall 54 in the so-called compressed position of the bias unit 50 rest.

0025The bias unit 50 is a self-contained, pre-assembled unit, wherein the appendages 58, 60 a holding device between the two walls 52, 54 and form part of a bayonet fitting, so generally a rotary closure, are. The angled longer extensions 58 project namely through the Outer edge of the rear wall 54 in sections recesses provided 62 (See FIG. 3) through which to Durchsteckausnehmungen 64 radially inwardly expand.

0026The bias unit 50 is assembled as follows. In the cup-shaped Front wall 52 is inserted, the spring 56th Subsequently, from the back fitted from the rear wall 54, the long projections 58 with the recesses 64 are aligned, so that the rear wall 54 near the front wall 52 against pressed the spring force and then twisted like a bayonet closure can be and so the projections 58 finally in the areas of the recesses 62 are. In this state, the bias unit 50 is a self self-contained unit with a compressed spring contained therein, wherein the Front and rear walls 52, 54 secured in position on a fixed distance are held.

0027To facilitate the rotation of the front wall 52 and rear wall 54 to one another is the flow-through opening 66 in the rear wall 54 as a hexagon executed. Alternatively, of course, this flow-through opening 66 is greater be carried out and instead, in the front wall 52 a recess or Recess be formed for the insertion of a tool.

0028In this compressed position the bias unit 50 is the axial inserted from end 29 into the combustion chamber 25, wherein the outer diameter of the walls 52, 54 on the inner diameter of the combustion chamber wall 24 almost matched clearance-free. The inwardly directed hook-shaped ends of the long extensions 58 are then on a shoulder in the region of the chamfer 34 to (left position of the front wall 52 in Figure 1). This insertion of the bias unit 50 is carried out with opened gas generator when the end 29 to top shows. Then, the propellant is filled 26 with the combustion chamber 25 is not completely filled. Finally, the unit is taken from the cover 15 and Ignition unit 16 on top of the not yet closed opening in the outer housing placed. Finally, peripheral wall 14 and cover 15 in accordance as welded before the erected state of the gas generator. Due to the compressed, compact bias unit is as much additional volume in the combustion chamber 25 for the grain 26 available, that this at Welding does not come into contact with the lid 15, so that a gap is between the propellant charge bed and the cover 15th

0029After welding is on the left, on the open side by a Hex tool, the rear wall 54 is rotated, so that the extensions 58 from the can emerge recesses 64 and the front wall 52 axially in the direction of arrow presses against the propellant according to Figure 1 and is decoupled from the rear wall 54 is. The then resulting, shown in Figure 1 right position Front wall 52 is the so-called release position, in which the bias unit 50 a biasing force to the grain 26 exerts, the case moves to the right and is clamped between the cover 15 and the front wall 52nd

0030Subsequently, the gas generator 10 with compressed gas from the left, open is Front side filled and finally by the unit of throttle device 18 and closure membrane 20 is closed. This closure is preferably carried out also by welding.

0031In the embodiment of Figure 2 only the first end 28 is somewhat otherwise formed. The bias unit 50 is shown in the release position, for purposes of clarity, the propellant charge is omitted 26th