HOUSING ARRANGEMENT FOR A GAS PRODUCER

The available invention concerns a housing arrangement for a gas producer, in particular for air bag modules in motor vehicles, with an internal preferably cylindrical housing for the admission of a propellant, a filter unit surrounding extent-laterally the internal housing and the internal housing and the filter unit surrounding outside housings, whereby both the internal housing and the outside housing exhibit a discharge opening, by which the gases developing with the burn of the propellant inside housings from the housing arrangement for blowing a Luftsacks up stream out can.

Since with the burn of the propellant freely becoming gases relatively hot and with combustion residues can be loaded, with gas producers a filter unit is usually planned, by which the flowing through incineration gases are cleaned. Beyond that a heat exchange with the flowing through incineration gas takes place when flowing through a such filter unit, so that this is cooled at the same time in the desired way.

Since however the discharge openings of the outside housing with well-known gas producers in all rule radially escape-end to the appropriate discharge openings of the internal housing are arranged, the filter way for the gases is relatively short, since these flow through the filter unit arranged between the internal housing and the outside housing exclusively in radial direction. Accordingly Kühl-und filter effect of well-known gas producers is relatively small. This excluding radial flow of the filter unit brings beyond that the additional disadvantage with itself that due to excluding radial flow the filter unit is not completely used, what in unwanted way a thermal overloading of the filter unit mean at the same time can.

It would be possible for the balancing of these disadvantages to increase the radial expansion of the filter unit. A such enlargement of the filter unit is not acceptable however due to the associated additional costs as well as the increased space requirement in all rule.

Accordingly the invention the task is the basis to create a housing arrangement for a gas producer which makes a maximization for the filter and cooling efficiency possible of a filter unit without an enlargement their radial dimensions.

This task is solved with a housing arrangement for a gas producer, which exhibits the characteristics of the requirement 1 or alternatively the characteristics of the requirement 11. Both the housing arrangement in accordance with requirement 1 and the housing arrangement in accordance with requirement 11 thereby the fundamental thought is the basis that the filter and cooling efficiency of the filter unit can be increased by the fact that this is not only flowed through on direct radial way; rather the invention the realization is the basis that the cool and filter effect can be increased by the fact that the filter unit in at least one of the two other cylindrical coordinate directions - thus in circumferential direction and/or alternatively in axial direction - is flowed through.

During the housing arrangement in accordance with requirement 1 it is intended for the maximization of the filter length that the discharge openings planned to the respective extent extent of the internal housing and the outside housing are in such a manner relatively to each other arranged that the filter unit can be flowed through by gases in circumferential direction of the housing arrangement, the leaking out the internal housing.

Gases the leaking out the internal housing do not flow through thus directly in radial direction the filter unit, in order to withdraw on shortest way from the outside housing; rather the gases withdrawing from the internal housing enter radial direction into the filter unit, which they flow through then in circumferential direction of the housing arrangement, before they can withdraw from the discharge opening of the outside housing. For the increase of the cool and filter effect it is thus not necessary to increase the radial dimension of the filter unit. Rather the radial dimension of the filter unit can be maintained or even reduced, since the cool and filter effect are increased simply by the fact that the discharge opening of the internal housing is as far as possible from the discharge opening of the outside housing in circumferential direction distant, since thereby gases before leaking out the outside housing, the leaking out the internal housing, must put a longer filter way back. Since the gases flow here along the extent walls along of the inside and the outside housing, with it not only an intensive heat exchange with the filter unit, but in particular also with the two housing walls, arises which means a particularly effective cooling that gases.

In accordance with a preferential execution form of the available invention the discharge openings of the internal housing and the outside housing can be transferred in circumferential direction of the housing arrangement in such a manner and relatively to each other arranged that the filter unit of gases before leaking out the outside housing, the leaking out the internal housing, is flow throughable over a length of curve in circumferential direction of the housing arrangement, which corresponds an angle of at least 45°. A good cool and filter effect can be perhaps already obtained during a flow of the filter unit over a length of curve, which corresponds to a smaller angle than 45°, however it proves as favourable to flow through the filter unit over a length of curve which corresponds to a larger angle than 45°.

In principle it would be desirable to flow through the filter unit over a length of curve which corresponds to an angle of approximately 360°. Since such flow of the filter unit can be guaranteed however only with the help of additional measures, on which in the following it is entered still more exactly it is intended in accordance with a particularly preferred execution form that the discharge openings of the internal housing and the outside housing are in such a manner relatively to each other arranged that the filter unit of gases before leaking out the outside housing, the leaking out the internal housing, is flow throughable over a length of curve in circumferential direction of the housing arrangement, which corresponds an angle of exactly 180°. For this exactly in each case one discharge opening can be trained to the extent extent of the internal housing and to the extent extent of the outside housing, whereby the discharge opening of the internal housing under an angle of 180° is arranged transferred to the discharge opening of the outside housing.

Since the discharge opening of the internal housing and the outside housing thus on each other opposite sides of the housing arrangement are arranged, the housing arrangement experiences two each other against-arranged impetuses due to out these two openings withdrawing gases, so that the housing arrangement is essentially thrust neutral.

The thrust neutrality of the housing arrangement according to invention can be still further improved in accordance with a further execution form, as both to the extent extent of the internal housing and to the extent extent of the outside housing in each case two discharge openings present at opposite sides of the respective housing are trained, whereby the discharge openings of the internal housing are arranged under an angle of 90° transferred to the discharge openings of the outside housing in each case. With this execution form both the impetuses arising when leaking out the internal housing and the impetuses arising when withdrawing from the outside housing waive themselves, so that during the activation of a gas producer with the housing arrangement according to invention no resulting impetus affects these.

As was mentioned already before, it would be desirable to be able to flow through the filter unit with gases the leaking out the internal housing over a length of curve which corresponds approximately to an angle of 360°. So that during an appropriate arrangement of the discharge opening of the internal housing and the outside housing gases the leaking out the internal housing do not flow however on the direct way of the discharge opening of the internal housing to the discharge opening of the outside housing, it is intended in accordance with a further execution form that in the annular gap between the internal housing and the outside housing a flow obstacle extending in axial direction of the housing arrangement is intended and in such a manner arranged that the filter unit of gases the leaking out the internal housing is flow throughable in only one circumferential direction. This execution form proves in particular as favourable if the discharge opening of the outside housing and the discharge opening of the internal housing in circumferential direction are very near together arranged and the flow obstacle is arranged between the two discharge openings in circumferential direction regarded, since then gas the leaking out the internal housing is forced to flow through the filter unit in circumferential direction regarded on the longer way.

The flow obstacle can form by a separate and/or additional body extending in axial direction of the housing arrangement; since thereby however the total weight of the housing arrangement increases in unwanted way, it is intended in accordance with a preferential execution form that the flow obstacle forms by a radial extension of the internal housing extending in axial direction of the housing arrangement. Radial extending of this extension is selected in such a way with the fact that the internal housing within the range of the radial extension with the outside housing arrives in plant, so that here a gas flow in circumferential direction is prevented.

With the filter unit it can act in principle over metal filters approximately at will trained. For example the filter unit can be trained as a metal woven filter, which can be composed of several winding situations from wire mat fabric (with and without Tressen). Likewise it would be possible to train the filter unit in form of a pressed Drahtgestricks which exists metal wire converted from one to a kind sock, and which was afterwards injected. Likewise it would be possible to train the filter unit in form of a wound rectangular wire filter which consists of a rectangular wire rolled up to a coil, with which the individual turns is slightly from each other beabstandet.

Since the Drahtfilter in front specified are relatively cost-intensive in the production however and exhibit beyond that a relatively large radial extending, it is intended in accordance with a further preferential execution form that the filter unit is formed by a stretching sheet metal and/or a stretching lattice or by a sheet metal provided with rasterförmig arranged formations, which is arranged only einlagig in the annular gap between the internal housing and the outside housing. With the formations of the sheet metal mentioned it can act for example over out of the sheet metal punched out noses, which as with a friction iron in or reciprocal stands out from the sheet metal level, so that the gases can flow through in such a way produced openings in the sheet metal.

As it was described already before it is intended during the housing arrangement according to invention that the internal housing and the outside housing possess only in each case or two discharge openings. So that with the burn of the propellant freely becoming gases taken up by the internal housing within shortest time the internal housing and the outside housing it can leak out nevertheless it is intended in accordance with a further execution form that the discharge opening of the internal housing exhibits, a schlitzförmige shape oblong in circumferential direction whereas to each other the discharge opening of the outside housing of several, locally grouped leaking out holes neighbouring in axial direction of the outside housing consists. The schlitzförmige arrangement of the discharge opening of the internal housing proves thereby in particular as favourable if the housing arrangement in axial direction regards a shape penetrated relatively exhibits, since in axial direction only relatively little place is then available for the training of the discharge opening. In contrast to this it proves as favourable to form the discharge opening of the outside housing from several smaller leaking out holes since a diffuser effect can be obtained thereby at the same time.

Alternatively to the housing arrangement according to requirement 1 it is intended during the housing arrangement according to requirement 11 that its filter unit of gas the leaking out the internal housing is flow throughable over as large a distance as possible in axial direction of the housing arrangement. For this the internal housing is on one side open in axial direction, whereby to the extent extent of the outside housing several discharge openings are trained, which are in such a manner arranged relative to or open side of the internal housing that the filter unit of gases the leaking out the open side of the internal housing is essentially completely flow throughable in axial direction of the housing arrangement.

Because the internal housing is on one side open in axial direction, flows thus the leaking out gases to an axial end stop of the outside housing, of where out they flow in the annular gap between the internal housing and the outside housing and/or in the filter up to that, arranged therein, the end stop mentioned front wall present of the outside housing, in order to withdraw there from the outside housing, to which to the extent extent neighbouring to the front wall mentioned the discharge openings mentioned can be preferably planned. It can be guaranteed furthermore by on one side open training of the internal housing that the gases can distribute themselves over the entire interior extent of the outside housing and thus the structure of housing within ranges limited to extent extent not to flow through.

Thus, without having, both in axial and in radial direction to leak out at the same time be able to plan additional radial discharge openings, the internal housing in axial direction a smaller length can exhibit the gases from the internal housing as both the outside housing and the filter unit. This execution form makes possible to be led it that the gases, as soon as they leak out the internal housing in axial direction can enter the filter unit, in order by this in axial direction to the discharge openings of the outside housing.

With the internal housing it can concern for example a cylindrical pipe, which is taken up concentrically by the outside housing and directly with the front wall of the outside housing, within the range of those the discharge openings of the outside housing is intended, is connected. Likewise it would be however possible to lock the internal housing at the open side in axial direction facing the side by a ground and/or a cover which is in plant with the front wall mentioned of the outside housing.

Also with the execution form of the housing arrangement according to invention, with which the filter unit in axial direction is flowed through, here in speech, it is to be trained in principle possible, the filter unit in form of the Drahtfilter mentioned already before. It proves however also here particularly favourably to train the filter unit by a stretching sheet metal and/or a stretching lattice or by a sheet metal provided with rasterförmig arranged formations which is arranged einlagig in the annular gap between the internal housing and the outside housing, since thereby the dimensions of the housing arrangement according to invention can be kept small in the desired way.

In the following the invention with reference to the attached figures is more near described. In all figures are resemble or each other appropriate elements by same reference numbers marked, how:

Fig. 1

a radial cut by a housing arrangement in accordance with a first execution form, flow throughable in circumferential direction, shows;

Fig. 2

a radial cut by a housing arrangement in accordance with a second execution form, flow throughable in circumferential direction, shows;

Fig. 3

an axial cut by a housing arrangement in accordance with a third execution form, flow throughable in axial direction, shows; and

Fig. 4

a perspective sectional view of a gas producer using the housing arrangement of the Fig. 3 shows.

In the Fig. 1 represented housing arrangement 10 covers an exterior hollowcylindrical housing 12, which is reciprocally locked in axial direction. Within the outside housing 12 essentially concentrically in addition an internal essentially hollowcylindrical housing 14 is arranged, which extends in axial direction over the entire length of the outside housing 12 away and rests each other thus with its two faces opposite in axial direction against the axial end stops of the outside housing 12 closely. Beyond that the housing arrangement 10 covers a filter unit 16, which is arranged in the annular gap formed between the outside housing 12 and the internal housing 14.

Like the Fig. 1 to be taken knows, exhibits the outside housing 12 to its extent extent only one discharge opening 18, which, locally grouped leaking out holes neighbouring from a multiplicity in axial direction (not recognizable) builds itself up to each other. The internal housing 14 exhibits likewise a discharge opening 20, which possesses, a schlitzförmige shape oblong in circumferential direction. But in the way according to invention the discharge openings are 18, 20 not radially escape-end rather under an angle of for instance 220° transferred to each other arranged.

The discharge openings 18, 20 are transferred to each other arranged thereby therefore under as large an angle as possible, so that from the internal housing 14 by its discharge opening 20 leaking out gases G one möglicht must put long way back, before they can leave the outside housing 12 by its discharge opening 18.

A so long flow path that gases G is therefore desirable, thus in the annular gap between the internal housing 14 and the outside housing 12 flowing gases G as for a long time as possible with the filter unit 16 and the extent walls of the inside and the outside housing 14, 12 in contact, in order to be as strongly as possible cooled down and by any combustion residues cleaned. The cooling efficiency is reached thereby in particular by the heat exchange that gases with the metallically trained filter unit as well as the extent walls of the outside and the internal housing 12, 14.

The filter effect is essentially based there against on the filter effect of the filter unit 16, which is formed in the represented execution form by a sheet metal provided with rasterförmig arranged nasenförmigen formations 17, which einlagig in the annular gap between the internal housing 14 and the outside housing 12 is arranged. With the nasenförmigen formations 17 of the filter unit 16 it can act thereby for example over into the sheet metal of the filter unit stamped and sheet metal sections curved from the sheet metal level, so that the filter unit 16 within the range of the respective formation 17 possesses a small opening, by which the gases G the filter unit 16 in radial direction flow through can. The formations 17 curved from the sheet metal level serve thus as support means for the combustion residues transported of the gases G, so that the gases G can leak out essentially freely from any combustion residues the discharge opening 18 of the outside housing 12.

So that out of the discharge opening 20 of the internal housing 14 leaking out gases flow actually also over the desired long filter way to the discharge opening 18 of the outside housing 12, a flow obstacle extending in axial direction of the housing arrangement 10 is been careful in the annular gap between the outside housing 12 and the internal housing 14, which forms in the represented execution form by a radial extension 22 of the internal housing 14 extending in axial direction of the housing arrangement 10. The radial extension 22 stands thereby with the outside housing 12 in plant, so that the gases G at the radial extension 22 cannot move by. The radial extension 22 of the internal housing 14 is in particular in such a manner arranged between the discharge opening 18 of the outside housing and the discharge opening 20 of the internal housing 14 thereby that from the discharge opening 20 of the internal housing 14 leaking out gases G are compelling to flow through the filter unit 16 on the long flow path which corresponds to an angle of for instance 220°, under which the discharge openings 18, 20 are transferred to each other arranged.

In the Fig. to 2 represented housing arrangement 10 essentially before corresponds with reference to the Fig. 1 represented housing arrangement, why in the following only with the differences one deals. In contrast to in the Fig. 1 represented housing arrangement points the housing arrangement 10 the Fig. 2 and/or its internal housing 14 no radial extension 22 up. The renouncement of the radial extension 22 became with in the Fig. it leads 1 represented housing arrangement to the fact that the gases G flow also over the shorter way into the annular gap between the internal housing 14 and the outside housing 12 of the discharge opening 20 of the internal housing 14 to the discharge opening 18 of the outside housing 12, so that the gases flowing this way would be less strongly cooled down and cleaned.

In order to work against this effect, are with in the Fig. 2 represented housing arrangement 10 the discharge openings 18, 20 of the outside housing 12 and the internal housing 14 under an angle of 180° to each other arranged. From the discharge opening 20 leaking out gases G can thus against and in clockwise direction the filter unit 16 flow through, in order to arrive at the discharge opening 18, whereby both flow and/or filter and cooling way are equivalent long. By appropriate dimensioning of the filter unit 16 can thus be guaranteed that no gas portions leave the discharge opening 18, which not sufficiently cleaned and cooled is. Beyond that brings in the Fig. 2 represented execution form of a housing arrangement 10 the advantage with itself that a gas producer realized with this housing arrangement 10 is thrust neutral, which is to due to each other facing discharge openings 18, 20.

Also in the Fig. 3 represented housing arrangement 10 and/or in the Fig. 4 using in the Fig. 3 represented housing arrangement realized gas producer 30 exhibits a concentric arrangement of a hollowcylindrical outside housing 12, an internal hollowcylindrical housing 14 and a likewise hollowcylindrical and/or circular filter unit 16, which between the internal housing 14 and the outside housing 12 is arranged. In contrast to the housing arrangements of the Fig. however the Fig extends 1 and 2 during the housing arrangement 10. 3 and 4 the internal housing 14 not over the entire axial length of the outside housing 12 away. Rather the internal housing 14 extends only about over three quarters of the axial length of the filter unit 16 as well as the outside housing 12.

Like the Fig. to be taken the outside housing 12 limited at its lower surface by a solid base plate 24 can do, is 3 and 4, which is embraced by the outside housing 12 and/or its lower edge, which for this for example through flanges one transformed. On the base plate 24 opposite side the outside housing 12 limited by a front wall 32 is, to which the internal housing 14 over a umgebördelten edge section 34 can be fastened. Optionally this umgebördelte edge section 34 of the internal housing 14 can embrace a head end plate 28. On that the head end plate 28 and/or the umgebördelten edge section 34 of the internal housing 14 opposite side is the internal housing 14 open and exhibits in particular no delimitation surface extending in radial direction.

On one side open training of the internal housing thereby 14 made possible that the incineration gases, for which propellant taken up with the burn by the internal housing 14 develops can flow unhindered into the range of the housing arrangement 10, in that the housing arrangement 10 in radial direction regarded only the outside housing 12 and the filter unit 16 covers. The gases 16 can thus within this range, within which the housing arrangement 10 does not possess an internal housing wall, over which in this radial direction penetrate entire extent of the filter unit 16 unhindered and essentially flow afterwards in axial direction over the entire length of the housing arrangement 10 to the discharge openings 18 of the outside housing 12, which are front wall 32 of the outside housing 12 opposite in the represented execution form in direct proximity the base plate 24.

By on one side open training of the internal housing those can escape freely from like an explosion becoming gases G unhindered and optimally distributed from the internal housing 14. The gases G become subsequently, by the filter unit 16, which in their structure with reference to the Fig. 1 descriptive filter unit corresponds, cleaned and cooled, before they can escape over over the extent of the outside housing 12 distributed discharge openings 18. As flow path thereby the entire extent of the annular gap between the internal housing 14 and the outside housing 12 is available, whereby the leaking out gases G are particularly effectively cooled and cleaned.

10

Housing arrangement

12

exterior housing

14

internal housing

16

Filter unit

18

Discharge opening of 12

20

Discharge opening of 14

22

radial extension of 14

24

Base plate

26

Fuze

28

Head end plate

30

Gas producer

32

Front wall

34

umgebördelter edge section

G

leaking out gases