DIFFUSOR FOR A GAS GENERATOR, GAS GENERATOR WITH SUCH DIFFUSOR AND MANUFACTURING METHOD FOR SUCH DIFFUSOR

Abstract

The disclosure relates to a diffusor for a gas generator of an airbag module, comprising a substantially tubular base body with a longitudinal axis, a baffle cap axially connected to the base body at a first end of the diffusor and a connecting device configured at a second end of the diffusor opposite to the first end. At least one outflow opening is formed in an outer wall of the tubular base body such that gas can flow out of an interior of the diffusor substantially in parallel to a longitudinal axis in the direction of the first end and the second end from the diffusor. The baffle cap is free from an outflow opening. The disclosure further relates to a gas generator comprising such a diffusor, as well as an airbag module including such a gas generator. Moreover, a method for manufacturing the diffusor is also proved.

Claims

1. A diffusor for a gas generator of an airbag module, comprising a substantially tubular base body with a longitudinal axis, a baffle cap axially connected to the base body at a first end of the diffusor and a connecting device formed at a second end of the diffusor opposite to the first end, wherein in an outer wall of the tubular base body, at least one outflow opening is formed such that gas can flow out of an interior of the diffusor substantially in parallel to the longitudinal axis toward the first and second ends from the diffusor, the baffle cap being free from an outflow opening.

2. The diffusor according to claim 1, wherein the at least one outflow opening is formed as a first outflow opening and as a second outflow opening and the baffle cap is configured to be dome-shaped.

3. The diffusor according to claim 2, wherein the first outflow opening and the second outflow opening are formed by one single tab which is formed by two parallel notches extending perpendicularly to the longitudinal axis in the outer wall of the tubular base body and by deforming the region therebetween in a radially outward direction.

4. The diffusor according to claim 3, wherein the tab is gill-shaped, the tab comprising two semidome-shaped elevations, and wherein the connecting device configured at the second end of the diffusor includes a taper.

5. The diffusor according to claim 4, wherein a curvature of the elevations slopes toward the first and second outflow openings so that a radial proportion of a flow of the gas out of the interior of the diffusor can be reduced by the first outflow opening and the second outflow opening, and the flow can be substantially formed to be exclusively axial.

6. The diffusor according to claim 2, wherein the first outflow opening is formed by a first tab and the second outflow opening is formed by a second tab, wherein the first and second tabs are formed by two parallel notches extending perpendicularly to the longitudinal axis and by deforming part of the regions directed by each of the notches to the first or second end in a radially inward direction.

7. The diffusor according to claim 6, wherein the first and second tabs are gill-shaped, wherein each of the first and second tabs comprises a semidome-shaped recess.

8. The diffusor according to claim 3, wherein the tab or the first and second tabs is/are formed to be symmetrical with respect to the longitudinal axis and/or a transverse axis.

9. The diffusor according to claim 2, wherein the first outflow opening which is directed toward the first end has a larger opening area than the second outflow opening which is directed toward the second end, wherein the opening area of the first and second outflow openings is designed so that a mass flow of the gas through the first outflow opening is substantially equal to the mass flow of gas through the second outflow opening.

10. The diffusor according to any claim 2, wherein the base body includes an inwardly directed bottom curvature on a side radially opposed to the first and second outflow openings.

11. The diffusor according to claim 2, wherein two or more first and second outflow openings are distributed in a circumferential direction.

12. A gas generator for an airbag module comprising a tubular housing and a diffusor according to claim 1, which is arranged at a first end of the gas generator.

13. The gas generator according to claim 12, wherein the housing of the gas generator includes at its first end a taper in which taper of the diffusor can engage in a complementary manner.

14. The gas generator according to claim 12, wherein a diameter of the gas generator and a diameter of the diffusor are substantially equal and/or the gas generator is a pyrotechnic gas generator or a hybrid gas generator.

15. An airbag module comprising a gas generator, an airbag inflatable by the gas generator and a fastening device for attaching the airbag module to a vehicle, wherein the gas generator is configured according to claim 12.

16. A vehicle safety system, comprising a gas generator, an airbag inflatable by a same as part of an airbag module, and an electronic control unit by which the gas generator can be activated when a release situation is given, wherein the gas generator is configured according to any one of the claims 12 to 14.

17. A method for manufacturing a diffusor comprising the following steps of: a. providing a tubular base body including an outer wall and including a baffle cap axially connected to the base body which forms a first end of the diffusor, b. introducing two parallel notches extending in a radial direction to an outer wall of the base body and having a first length, wherein the notches have a depth of the wall of the base body. c. plastically deforming, one single tab or a first tab and a second tab in a region or regions adjacent to the notches.

18. The method according to claim 17, wherein the plastic deformation is carried out either from an interior of the diffusor to radially outside by a mandrel having one or two semidome-shaped bulge(s) or from an exterior of the diffusor to radially inside by application of an impressing tool having one or two semidome-shaped bulge(s).

19. The diffusor according to claim 5, wherein the tab or the first and second tabs is/are formed to be symmetrical with respect to the longitudinal axis and/or a transverse axis.

20. The diffusor according to claim 5, wherein the base body includes an inwardly directed bottom curvature on a side radially opposed to the first and second outflow openings.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0032] In the following, the disclosure shall be illustrated in detail by the exemplary arrangements with reference to the attached Figures, wherein:

[0033] FIG. 1 shows a tubular gas generator comprising a diffusor according to the disclosure in a first configuration;

[0034] FIG. 2 shows a longitudinal section of the tubular gas generator according to FIG. 1;

[0035] FIG. 3 shows a magnified cutout of FIG. 2;

[0036] FIG. 4 shows a diffusor according to the disclosure in the first exemplary configuration;

[0037] FIG. 5 shows a longitudinal section of the diffusor according to FIG. 4;

[0038] FIG. 6 shows a longitudinal section of a diffusor according to the disclosure in a second exemplary configuration;

[0039] FIG. 7 shows a diffusor according to the disclosure in a third exemplary configuration;

[0040] FIG. 8 shows a longitudinal section of the diffusor according to FIG. 7;

[0041] FIG. 9 shows a longitudinal section of a diffusor according to the disclosure in a fourth exemplary configuration;

[0042] FIG. 10 shows a longitudinal section of a diffusor according to the disclosure in a fifth exemplary configuration;

[0043] FIG. 11 shows a diffusor according to the disclosure in a sixth exemplary configuration; and

[0044] FIG. 12 shows a longitudinal section of the diffusor according to FIG. 11.

DETAILED DESCRIPTION

[0045] FIGS. 1 to 3 illustrate a gas generator 50 comprising a diffusor 10 according to the disclosure as set forth in a first configuration. FIGS. 4 and 5 show only the diffusor 10 of the first exemplary configuration. The gas generator 50 is configured as a tubular gas generator. The gas generator has a tubular housing 51 with a longitudinal axis 56 at the second end of which an igniter housing 53 including an igniter 52 is arranged. A diaphragm 55 may be arranged in an area of a taper of the housing 5. Another diaphragm 54 may be arranged in an area of a first end of the housing 51. The diffusor 10 includes a tubular base body 11 with a longitudinal axis 16 extending in extension of the longitudinal axis 56 of the housing 51 of the gas generator 50. A baffle cap 12 is connected, axially adjacent to the tubular base body 11, to a first end 13 of the diffusor 10. The tubular base body 11 of the diffusor 10 has a substantially cylindrical outer contour. In addition, the baffle cap 12 axially connected to the base body 11 is to be understood such that the baffle cap 12 is adjacent in the axial direction, i.e., along and, resp., in parallel to the longitudinal axis 16 of the base body 11, to the latter, either as an independent component part or formed integrally with the base body. In the case of an independent component part, the baffle cap 12 may be screwed, crimped, roller-burnished, or adhesively connected, such as by laser or friction welding, to the base body 11, for example. The housing 51 of the gas generator 50 and the tubular base body 11 of the diffusor 10 expediently have a similar, particularly equal, diameter. The diffusor 10 is connected to the housing 51 by crimping or radially circumferential roller-burnishing, for example.

[0046] In a region of the tubular base body 11 of the diffusor 10, a tab 20 having two elevations 23 is visible. A first outflow opening 21 and a second outflow opening 22 through which gas can flow out or flow off from the interior of a diffusor 10 into an outer region of the diffusor 10 are disposed between the elevations 23 and the tubular base body 11. As is evident from the longitudinal section in FIG. 2, each of the surface areas of the first outflow opening 21 and the second outflow opening 22 has a surface normal in parallel to the longitudinal axis 16 of the diffusor 10. In a region of the wall of the diffusor 10 substantially opposed to the tab 20, a bottom curvature 24 is disposed in the wall of the diffusor 10.

[0047] The operating mode of the gas generator 50 is as follows: When the igniter 52 is ignited or activated, in an interior of the gas generator, gas is generated and/or released so that a corresponding gas flow is generated or forms which moves or is directed along the longitudinal axis 56 of the tubular housing 51 of the gas generator 50 and bursts or opens the diaphragm 55 and, after that, the diaphragm 54. Then the gas flow or the entire amount of gas comprised by the gas flow flows into the diffusor 10 and, resp., is forwarded there. In the diffusor 10, part of the gas or of the gas flow is deflected by the bottom curvature 24 and the baffle cap 12 and, thus, is guided to the second outflow opening 22, thus causing part of the gas flow or part of the amount of gas to leave the outflow opening 22 largely in parallel to the longitudinal axis 56 of the gas generator and, resp., largely in parallel to the longitudinal axis 16 of the base body 11 of the diffusor 10. Another part of the gas flow is guided, after the gas flowing into the diffusor 10, directly through the elevation 23 to the first outflow opening 21 and leaves the diffusor 10 largely in parallel to the longitudinal axis 16. The gas flows which leave the diffusor 10 through the first outflow opening 21 and the second outflow opening 22 extend substantially in opposite directions so that an intended shearing neutrality is maintained for the gas generator 50 with respect to its gas outflow when it is activated.

[0048] The diffusor 10 shown in FIGS. 4 and 5 is manufactured from a tubular base body 11 comprising a baffle cap 12 integrally connected to the base body 11 by providing the base body 11 initially with two parallel notches extending perpendicularly to the longitudinal axis 16. In so doing, the base body 11 is cut continuously from outside over its entire wall thickness along an appropriate radially circumferentially extending region. Such cutting which produces the respective notches can be carried out by known material abrasion methods such as sawing, cutting, milling or laser treatment. After that, in the base body 11, a tab 22 having two elevations 23 is formed by a forming tool in the form of a mandrel provided with two semidome-shaped bulges, by the mandrel being appropriately pressed or moved outwards. As an option, a complementarily shaped counter-holding tool can be positioned or guided from outside. Said plastic forming of the tab 22 helps appropriately stretch, expand or also work-harden the material of the diffusor in or at the adjacent region of forming. Further, the diffusor 10 may be provided with a peripheral taper 15 in the region of its second end 14 and/or with a bottom curvature 24 in the region of its first end 13 which is arranged on a side opposite to the tab 20. The diffusor 10 thus can be attached with its peripheral taper 15 onto or to the gas generator 50 for further fastening thereto so that its taper 15 engages in and/or is fixed to a taper or recess of the gas generator 50 appropriately geometrically formed to be complementary in the fastening region with the diffusor 10.

[0049] As an alternative to this, however, the peripheral taper 15 of the diffusor 10 can be introduced to the latter only when the diffusor 10 is mounted or fastened to the gas generator 50. Accordingly, before being mounted, the diffusor 10 has a substantially cylindrically shaped second end 14 without a taper and is then positioned, in an appropriate axial fastening position, on the gas generator 10 which includes a corresponding complementary recess. Only then is the diffusor 10 formed onto the complementary recess of the gas generator 50 at its second end 14 in a radially inward direction, for example by radially peripheral roller-burnishing, so that the recess 15 is formed on the diffusor 10.

[0050] FIG. 6 illustrates a longitudinal section of a diffusor 10 according to a second exemplary configuration. Deviating from the longitudinal section of a diffusor 10 according to the first exemplary configuration shown in FIG. 5, the elevations 23 are provided with first and second flow directing areas 33, 34. The flow directing area 33 is formed to slope toward the first end 13, while the flow directing area 34 is configured to slope toward the second end 14. In this way, a respective outwardly sloping curvature is formed which prevents a flow component of the gas flowing out of the diffusor from forming with a radial component when it flows out of the first outflow opening 21 and the second outflow opening 22. In other words, gas flowing out of the diffusor that might have a small radially directed outflow component is virtually “forced” by the flow directing areas 33, 34 to continue flowing in an outflow direction substantially exclusively in parallel to the longitudinal axis 16 of the diffusor.

[0051] FIGS. 7 and 8 illustrate a diffusor 10 according to a third exemplary configuration. The diffusor 10 has a tubular base body 11 with a longitudinal axis 16. The diffusor 10 includes a tab 20 in a portion of the base body 11. The tab 20 has a larger radial distance from the longitudinal axis 16 than the remaining base body 11 so that a first outflow opening 21 and a second outflow opening 22 are formed. In a longitudinal section, a wall of the tab 20 is parallel to the longitudinal axis 16. Each of the surface areas of the first outflow opening 21 and the second outflow opening 22 has a surface normal in parallel to the longitudinal axis 16. The diffusor 10 may include a bottom curvature 24 also according to the third exemplary configuration. In the area of the second end 14 of the diffusor 10, the diffusor 10 may optionally include a taper 15 for fastening to the gas generator 50.

[0052] A fourth exemplary configuration of a diffusor 10 shown in FIG. 9 is a modification of the third exemplary configuration. In the area of the first outflow opening 21 and the second outflow opening 22, the tab 20 includes flow directing areas 33 and 34. In this case, too, the flow directing areas 33 and 34 serve for delimiting a radial flow component and, resp., producing a substantially exclusively parallel outflow direction of a gas out of the interior of the diffusor 10.

[0053] In FIG. 10, a diffusor 10 according to a fifth exemplary configuration is shown. The fifth exemplary configuration is another modification of the third exemplary configuration shown in FIGS. 7 and 8. In the fifth exemplary configuration, it is visible in the longitudinal section that the tab 20 has an inclination or an angle with respect to the longitudinal axis 16. The inclination of the tab 20 is selected so that the second outflow opening 22 has a smaller opening area than the first outflow opening 21. The smaller opening area of the second outflow opening 22 can help reduce a mass flow of gas exiting through the second outflow opening 22. Thus, the mass flows can be set as desired, in particular to be equal, through the first outflow opening 21 and the second outflow opening 22 by selecting the inclination of the tab 20.

[0054] FIGS. 11 and 12 illustrate a diffusor 10 according to a sixth exemplary configuration. In the sixth exemplary configuration, the diffusor 10 has a tubular base body 11 comprising a baffle cap 12 at a first end 13 of the diffusor 10. In the base body 11, a first tab 20a and a second tab 20b are arranged or configured. The first tab 20a and the second tab 20b have a smaller distance from the longitudinal axis 16 than the remaining base body 11, i.e., they extend inwards. Each of the first and second tabs 20a, b has a semidome-shaped recess 25. A region of the tubular base body 11 is arranged between the ends of the first tab and the second tab 20a, b. A first outflow opening 21 is arranged between an end of the first tab 20a and the region of the tubular base body 11, a second outflow opening 22 is arranged between an end of the second tab 20b and the region of the tubular base body 11. The outflow openings 21 and 22 show a surface normal in parallel to the longitudinal axis 16.

[0055] A diffusor 10 according to the sixth exemplary configuration is manufactured by providing a tubular base body 11 comprising a baffle cap 12. Two parallel notches are introduced to the base body 11 perpendicularly to the longitudinal axis 16 of the base body 11. Regions located outside of each of the parallel notches introduced are impressed radially inwardly by a forming tool so that a first tab 20a and a second tab 20b are produced. The region between the two tabs 20a, b is not deformed so that here a region of the base body 11 is practically maintained or retained as a remainder which, when viewed per se, takes the shape of an arc or a cutout of an arc. The outer wall of the base body 11 in this exemplary arrangement of the diffusor includes, when viewed per se or viewed without the afore-mentioned formed arc, merely one single opening to the outside or one single outflow opening which is correspondingly slit-shaped along a region of the circumference of the base body 11. If the tubular base body 11 is viewed concerning the option of different gas flow paths or gas flow directions and, accordingly, in particular the afore-mentioned formed arc is also viewed, however, the single outflow opening can be regarded as a configuration of the afore-mentioned first and second outflow openings 21, 22.