IGNITING UNIT, ESPECIALLY FOR AN INFLATOR, INFLATOR, AIRBAG MODULE, VEHICLE SAFETY SYSTEM AND METHOD OF MANUFACTURING AN IGNITING UNIT

Abstract

The invention relates to an igniting unit (10), especially for an inflator, comprising an electric igniter (11) including a first inner cap (12) which forms a space (14) for being filled with a booster propellant charge with a second outer cap (13). In accordance with the invention, the second cap (13) is an electrically non-conductive insulating cap.

Claims

1. An igniting unit (10) for an inflator, comprising: an electric igniter (11) comprising a first inner cap (12) with a space (17) filled with a pyrotechnical charge; a second outer cap (13), wherein the first inner cap (12) forms a space (14) with the second outer cap (13); and an inert material provided in the space (14).

2. The igniting unit (10) according to claim 1, wherein the inert material is the sole material provided in the space (14).

3. The igniting unit (10) according to claim 1, further comprising a pyrotechnically activatable booster propellant charge that is provided in the space (14) in addition to the inert material.

4. The igniting unit (10) according to claim 3, wherein the inert material comprises at one of a separate layer of inert material and an individual molding of inert material.

5. The igniting unit (10) according to claim 1, wherein the inert material is selected from the group consisting of Borates, boric oxides, calcium carbonate, molecular sieves, silicates, and mixtures thereof.

6. The igniting unit (10) according to claim 1, wherein the electric igniter (11) is a prefabricated igniter comprising a bridge wire (18) connected to two pins (19) in an electrically conductive manner, wherein the electric igniter (11) is one of a GTMS (glass to metal seal) igniter whereby with the aid of a metallic ring (20) and a pressure glazing (21) the pins (19) are connected to the first inner cap (12) and a PTMS (plastic to metal seal) igniter comprising a plastic body (28) in which the two pins (19) are embedded whereby the plastic body (28) is connected to the first inner cap (12).

7. The igniting unit according to claim 1, wherein the second cap (13) comprises an electrically non-conductive insulating cap and preferably is connected to the electric igniter (11) by plastic insert molding.

8. The igniting unit according to claim 7, wherein the second cap (13) is connected to the electric igniter (11) by plastic insert molding.

9. The igniting unit according to claim 1, wherein the second cap (13) is made, at least in portions, of a plastic material or a metal material.

10. The igniting unit according to claim 9, wherein the second cap (13) is connected to the electric igniter (11) by a material connection comprising at least one of laser welding, ultrasonic welding, a positive (interference) connection, a friction-type connection, press-fitting, and adhesive bonding.

11. An inflator comprising an igniting unit according to claim 1.

12. An airbag module comprising an igniting unit according to claim 1.

13. An airbag module comprising an inflator according to claim 11.

14. A vehicle safety system comprising an igniting unit of claim 1.

15. A vehicle safety system comprising an inflator of claim 11.

16. A vehicle safety system comprising an airbag module according to claim 12.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Hereinafter the invention shall be illustrated by way of embodiments with reference to the enclosed schematic Figures in which:

[0028] FIG. 1: shows a longitudinal sectional view across an igniter unit comprising a GTMS (glass to metal seal) igniter;

[0029] FIG. 2: shows a longitudinal sectional view across an igniter unit comprising a PTMS (plastic to metal seal) igniter;

[0030] FIG. 3: shows a longitudinal sectional view across another embodiment of an igniter unit comprising a PTMS (plastic to metal seal) igniter.

DESCRIPTION

[0031] FIG. 1 illustrates an igniting unit 10, especially for an inflator (not shown), an electric igniter 11 including a first cap 12 which delimits a space 14 for being filled with a booster propellant charge with a second cap 13. According to the invention, the second cap 13 is in the form of an electrically non-conductive insulating cap.

[0032] The electric igniter 11 can be an electrically/pyrotechnically prefabricated standard igniter. So called GTMS (glass to metal seal) standard igniters and PTMS (plastic to metal seal) standard igniters are known. FIG. 1 includes an electric igniter of the GTMS standard igniter type. The electric igniter 11 includes a cap 12 which may be manufactured of metal and/or plastic. The first cap 12 comprises a side or peripheral wall 15 and a cover 16. The cover 16 is in the form of a flat end wall. The peripheral wall 15, on the other hand, has a rotation-cylindrical, especially circular-cylindrical shape. The cover 16 as well as the upper third of the peripheral wall 15 of the first cap delimit a space 17 filled with pyrotechnical charge, wherein also plural beds/layers of pyrotechnics are possible. There is equally provided an electrically conductive bridge wire 18 projecting into the space 17 and into the pyrotechnical charge, respectively. The bridge wire is connected, preferably welded, to the two pins 19 in an electrically conductive manner. With the aid of a metallic ring 20 and a pressure glazing 21 the pins 19 are connected to the first cap 12 of the electric igniter 11.

[0033] Summing up, the first cap 12, the space 17 filled with pyrotechnics, the bridge wire 18, the pins 19 as well as the metallic ring 20 and the pressure glazing 21 form the electric igniter 11. This electric igniter 11 is a prefabricated known GTMS standard igniter, as mentioned already.

[0034] The second cap 13 which is formed as electric insulating cap and is preferably made of plastic material, but which could also be made of metal, forms the outer cap of the igniting unit 10. The outer cap or second cap 13 in turn comprises a peripheral wall 22, which in the shown example is circular-cylindrical, as well as a cover 23 which is a substantially flat end wall. An orifice 27 into which the electric igniter 11 and the first cap 12 of the electric igniter 11, resp., projects is formed on the side of the second cap 13 opposed to the cover 23.

[0035] Opposed to the cover 23 of the second cap 13 the orifice 27 is formed. The inner diameter or the opening width of the peripheral wall 22 of the second cap 13 is larger than the outer diameter of the peripheral wall 15 of the first cap 12 so that the electric igniter 11 and the first cap 12 of the electric igniter 11, resp., can be inserted or press-fitted into the orifice 27 of the second cap 13.

[0036] Both caps 12 and 13 are formed to be preferably rotationally symmetric relative to the central axis M. Furthermore, the first cap 12 of the electric igniter 11 is formed concentrically with respect to the central axis M and to the second cap 13.

[0037] The space 14 for being filled with a booster propellant charge or booster charge, resp., is thus delimited or formed by the first cap 12 and the second cap 13. Especially the space 14 is formed by the cover 16 of the first cap 12 as well as the cover 23 and the peripheral 22 of the second cap.

[0038] In particular it is not provided that parts of the booster propellant charge are provided between the peripheral wall 22 of the second cap 13 and the peripheral wall 15 of the first cap 12 in the area in which the two caps 12, 13 are press-fitted into each other. In other words, in this area there is provided no gap, at least no such gap into which parts of the propellant charge might get. Due to the strongly enlarged representation of FIG. 1 this could be interpreted in a misleading manner. Consequently, the outer diameter of the peripheral wall 15 of the first cap 12 is smaller only to such extent, compared to the inner diameter of the peripheral wall 22 of the second cap 13, that the two caps 12, 13 can be easily pressed into each other in terms of process.

[0039] The space 14 is configured so that it can be filled with 30 to 1500 mg, especially 200 to 1200 mg, especially 300 to 1000 mg, in particular 350 to 500 mg of booster propellant charge.

[0040] During manufacture of the igniting unit 10 according to the invention, first the second cap 13 made of plastic which is formed as outer cap is filled with the booster charge. After that the electric igniter 11, especially the first cap 12 of the electric igniter 11 is press-fitted into the second cap 13 and the orifice 27 of the second cap 13, resp., so that the first cap 12 and the second cap 13 form the space 14 which is already filled with the booster propellant charge. Subsequently, the plastic cap 13 is connected to the electric igniter 11 by plastic insert molding.

[0041] A plastic base 24 connecting the outer cap or second cap 13 to the electric igniter 11 is formed by plastic insert molding. The first cap 12 includes an inclined end flange 25. The second cap 13 also includes such inclined end flange 26. During plastic insert molding plastic material flows into the clearance formed by the two end flanges 25 and 26 so that a proper connection of the outer plastic cap 13 to the electric igniter 11 is provided.

[0042] When the second cap 13 is made of plastic and is connected to the electric igniter 11 with the aid of plastic insert molding and consequently the plastic base 24 is formed, the igniting unit 10 is configured to be electrically insulated, i.e. electrically non-conductive, with the exception of the two electrically conductive pins 19.

[0043] Each of the FIGS. 2 and 3 shows an igniting unit 10, especially for an inflator (not shown) which substantially corresponds to the structure of FIG. 1, but especially comprises an electric igniter 11 of the PTMS (plastic to metal seal) type standard igniter described in the foregoing. The individual components of the igniting units 10 of the FIGS. 2 and 3 having the same function as those of FIG. 1 are provided with identical reference numerals and the description of figures of FIG. 1 is referred to in this respect.

[0044] Especially the following substantial differences are resulting for the FIGS. 2 and 3 compared to FIG. 1:

[0045] In the electric igniter 11 (PTMS standard igniter) in FIGS. 2 and 3 the first cap 12 is substantially made completely of plastic and not of metal. The restriction substantially has to be understood to the effect that the first cap 12 may be made of a plastic material which is merely doped with minimal metallic particles so as to meet particular requirements concerning electrostatics and electrostatic discharges, however no large-surface continuous metallic areas on or in the first cap 12 are meant in this case.

[0046] Another crucial difference consists in the fact that the two electrically conductive pins 19 in FIGS. 2 and 3 are not connected to a metal ring or fastened in a pressure glazing, i.e. they are not connected to the first cap of the electric igniters with the aid of a metal ring as well as a pressure glazing. Rather, in each of the FIGS. 2 and 3 both pins 19 are embedded in a plastic body 28 or a surrounded by the same by injection-molding. The plastic body 28 is configured so that in the area opposite to the bridge wire 18 it has a pre-shaped conical geometry that is advantageous to the further mounting of the igniting unit 10, e.g. in an inflator.

[0047] In contrast to this, in FIG. 1 the plastic base 24 of the igniting unit 10 must first be manufactured, in addition to the electric igniter 11 there, by a separate plastic insert molding process.

[0048] The plastic body 28 of the FIGS. 2 and 3 is connected to the first cap 12, especially by ultrasonic welding, and together with the latter forms an enclosing outer housing of the prefabricated electric igniter 11, wherein, as afore-described, the two pins 19 are embedded in the plastic body and extend across the same in parallel to the central axis M. Further in the inner space 17 of the electric igniter 11 two beds or layers of pyrotechnics are shown which are also referred to as primary and secondary charges and may have different chemical compositions.

[0049] When manufacturing the igniting unit 10 according to the invention of FIGS. 2 and 3, analogously to FIG. 1 first the second cap 13 in the form of an outer cap is filled with the booster charge. Subsequently the electric igniter 11, especially the first cap 12 of the electric igniter 11 is press-fitted into the second cap 13 and the orifice 27 of the second cap 13, resp., so that the first cap 12 and the second cap 13 form the space 14 which is filled already with the booster propellant charge.

[0050] By such pressing operation the second cap 13 is already connected to the electric igniter 11. Finally the cap 13 can be further connected to the igniter 11 by material connection by laser or ultrasonic welding. Concerning the afore-mentioned pressing operation also a parallel or subsequent bonding process is imaginable.

[0051] FIGS. 2 and 3 differ by the illustrated form of the second cap 13 which in FIG. 3 includes an inclined end flange 26 that is adjacent to a complementary inclined end flange 25 of the first cap 12 of the electric igniter 11

[0052] Hereby, when further mounting the igniting unit 10 of FIG. 3 for example into a retaining component (not shown), a beading connection can be provided by beading an area of the retaining component which exerts a retaining force on the inclined end flange 26, the retaining force causing sufficient force connection of the end flange 26 to the end flange 25. Thus the afore-mentioned laser or ultrasonic welding process for connecting the second cap 13 to the first cap 12 might be dispensed with, where appropriate.

[0053] The inflators, airbag modules and vehicle safety systems according to the invention are provided with igniting units 10 according to the invention in accordance with the embodiment shown in FIGS. 1 to 3.

LIST OF REFERENCE NUMERALS

[0054] 10 igniting unit [0055] 11 electric igniter [0056] 12 first cap [0057] 13 second cap [0058] 14 space [0059] 15 peripheral wall [0060] 16 cover [0061] 17 space [0062] 18 bridge wire [0063] 19 pin [0064] 20 metallic ring [0065] 21 pressure glazing [0066] 22 peripheral wall [0067] 23 cover [0068] 24 plastic base [0069] 25 inclined end flange [0070] 26 inclined end flange [0071] 27 orifice [0072] 28 plastic body [0073] M central axis