Igniter support, subassembly, gas generator, and method for manufacturing a gas generator

Abstract

The invention describes an igniter support (22) for an igniter unit (20) of a gas generator (10), comprising a first holder element (30) made from a first material and a second holder element (32) made from a second material different from the first material. Both holder elements (30, 32) can be positively coupled to each other. Further, a subassembly (16), a gas generator (10) and a method for manufacturing a gas generator (10) are described.

Claims

1. An igniter support (22) for an igniter unit (20) of a gas generator (10), comprising a first holder element (30) made from a first material and a second holder element (32) made from a second material different from the first material, wherein both holder elements (30, 32) are adapted to be positively coupled to each other, especially to be at least partially positively nested, wherein the first holder element (30) has an axial contact surface (64) for the second holder element (32) on an end face associated with the second holder element (32), and/or the second holder element (32) has axially protruding projections (76), especially wherein the projections (76) have an axial pressure surface (78) via which they interact with an axial contact surface (64) of the first holder element (30).

2. The igniter support (22) according to claim 1, wherein the first holder element (30) is made from metal and can be assembled with the igniter unit (20) to form a prefabricated assembly group, and wherein the second holder element (32) is made from plastic material.

3. The igniter support (22) according to claim 1, wherein both holder elements (30, 32) are positively coupled in the circumferential direction and/or in the radial direction.

4. The igniter support (22) according to claim 1, wherein the first holder element (30) includes axially protruding lugs (68) at the end face associated with the second holder element (32).

5. The igniter support (22) according to claim 4, wherein the projections (76) and/or the lugs (68) include bearing surfaces (80, 72) provided in the circumferential direction for orientating the holder elements (32, 30).

6. An igniter support (22) for an igniter unit (20) of a gas generator (10), comprising: a first holder element (30) made from a first material and a second holder element (32) made from a second material different from the first material, wherein both holder elements (30, 32) are adapted to be positively coupled to each other, wherein the second holder element (32) has at least one detent element (42) arranged radially outside and being especially hook-shaped, and wherein the detent element (42) extends from an end face of the second holder element (32) which is remote from the first holder element (30).

7. The igniter support (22) according to claim 1, wherein the second holder element (32) includes, on the inner face thereof, an undercut (52) for the igniter unit (20).

8. A subassembly (16) comprising an igniter support (22) according to claim 1 and an igniter unit (20).

9. The subassembly (16) according to claim 8, wherein the first holder element (30) is formed at least in some areas so that the igniter unit (20) is received at least partly by the first holder element (30), and/or in that the igniter unit (20) is bonded at least in some areas with the first holder element (30).

10. The subassembly (16) according to claim 8, wherein the igniter unit (20) comprises a socket (26) which is inserted in the second holder element (32) or which is attached to the second holder element (32) by injection molding to form an integral component with the latter.

11. A gas generator (10) comprising a subassembly (16) according to claim 8, including a gas generator housing (12) in which the subassembly (16) is at least partially received, the gas generator housing (12) including at least one stop face (54) for the subassembly (16).

12. The gas generator (10) according to claim 11, wherein the gas generator housing (12) in an end section (14) includes at least one opening (40) via which the subassembly (16) is fixed in position on the gas generator housing (12).

13. The gas generator (10) according to claim 11, wherein the gas generator (10) is a pyrotechnical gas generator, a hybrid gas generator, a belt tensioner or an actuator the gas generator housing (12) being tube-shaped or toroid-shaped.

14. A method for manufacturing a gas generator (10), comprising the following steps of: providing a gas generator housing (12), providing a subassembly (16) according to claim 8, and inserting the subassembly (16) into the gas generator housing (12).

15. The method according to claim 14, wherein the igniter (24) is fastened to the first holder element (30) by partially forming the first holder element (30) and/or in that a socket (26) is inserted into or attached by injection-molding to the second holder element (32).

16. The igniter support (22) according to claim 1, wherein the projections (76) have an axial pressure surface (78) via which they interact with an axial contact surface (64) of the first holder element (30).

17. An igniter support (22) for an igniter unit (20) of a gas generator (10), comprising a first holder element (30) made from a first material and including axially protruding lugs (68) a second holder element (32) made from a second material different from the first material and including axially protruding projections (76), wherein both holder elements (30, 32) are positively coupled to each other-when the lugs (68) and the projections (78) are interdigitated with one another.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Further advantages and characteristics of the invention will be evident from the following description and the drawings that will be referred to, wherein:

(2) FIG. 1 shows a sectional view of a gas generator according to the invention in the area of a subassembly according to the invention,

(3) FIG. 2 shows a sectional view of the gas generator according to the invention of FIG. 1 rotated about 90° vis-à-vis FIG. 1,

(4) FIG. 3 shows another sectional view of the gas generator according to the invention of FIGS. 1 and 2 in a sectional plane different from FIG. 1,

(5) FIG. 4 shows a top view onto a first holder element of an igniter support according to the invention,

(6) FIG. 5 shows a perspective view of the first holder element of FIG. 4,

(7) FIG. 6 shows a perspective view of a second holder element of an igniter support according to the invention, and

(8) FIG. 7 shows another perspective view of the second holder element of FIG. 6.

DESCRIPTION

(9) In FIGS. 1 to 3, a gas generator 10 adapted to generate inflation gas for an airbag that helps protect a vehicle occupant of an automotive vehicle in the case of crash is illustrated partially in different sectional views.

(10) The gas generator 10 comprises a gas generator housing 12 that is shown merely partially in the Figures. In the shown embodiment, it is a tube-shaped gas generator housing 12 so that the entire gas generator 10 is substantially tube-shaped.

(11) The gas generator 10 has a longitudinal axis S which also defines an axial direction of the gas generator 10, i.e. starting from an axial end portion 14 in the direction of a first holder element 30, as illustrated by the arrow symbols in FIGS. 1-3, so that the gas generator 10 shows a substantially cylindrical design. The gas generator 10 moreover may be substantially symmetric with respect to the longitudinal axis S.

(12) There is represented merely the axial end section 14 of the gas generator 10 in which a subassembly 16 which seals the gas generator housing 12 is arranged on a gas generator housing 12 so that a gas-tight combustion chamber 18 to which the subassembly 16 is adjacent is formed in the gas generator housing 12. The combustion chamber may hold a propellant (not shown) which is ignited and burnt upon activation of the gas generator 10 to produce gas, for example for inflating an airbag. The propellant may consist of a filling of individual propellant bodies such as e.g. compressed propellant pellets or extruded bodies, but may also be in the form of a monolithic molded body or in the form of lined up disks or rings.

(13) The subassembly 16 includes an igniter unit 20 as well as an igniter support 22 which supports or holds the igniter unit 20 at least partially within the gas generator housing 12. The igniter support 22 forms the interface between the gas generator housing 12 and the igniter unit 20. In general, the igniter support 22 helps to safeguard that the igniter unit 20 takes a desired position with respect to the gas generator housing 12.

(14) The igniter unit 20 comprises an igniter 24 that protrudes partially into the combustion chamber 18 as well as a socket 26 that may also be referred to as retainer into which a plug (not shown) can be plugged to electrically contact the igniter 24 and, resp., couple the latter to a controller adapted to control and, resp., activate the igniter unit 20. For this purpose, the igniter 24 includes contact pins 28 which are received within or surrounded by the socket 26. For example, the socket 26 is a plastic part.

(15) Each of the igniter 24 and the socket 26 is held by the igniter support 22, as is evident from FIGS. 1 to 3.

(16) To this end, the igniter support 22 includes the first holder element 30 and a second holder element 32 which are formed separately from each other and are positively coupled to each other, especially in the circumferential direction and in the radial direction. The two holder elements 30, 32 are moreover made from different materials.

(17) In the shown embodiment, the first holder element 30 is made from metal so that it is electrically conductive, whereas the second holder element 32 is made from plastic material which is not electrically conductive. The two holder elements 30, 32 are illustrated in detail in each of the FIGS. 4 to 7.

(18) The first holder element 30 serves for fixing the igniter 24 within the gas generator housing 12. For this purpose, the first holder element 30 has an axially protruding annular retaining portion 34 which is collar-shaped. The retaining portion 34 may be (plastically) formed at its free end so as to receive the igniter 24 in a safe position, especially the retaining portion 34 is beaded or crimped, particularly radially inwardly onto a corresponding circumferential area of the igniter. Preferably, merely a lower area, viz. an area facing the contact pins 28, of the igniter 24 is held by the retaining portion 34 so that an upper area, viz. an area remote from the contact pins 28, of the igniter 24 extends into the combustion chamber 18, wherein the upper area can be opened upon activation of the igniter 24 and can release hot gases and, resp., particles that are adapted to ignite the propellant (not shown) in the combustion chamber.

(19) Alternatively, or additionally to the described (plastic) forming of the retaining portion 34, it is also possible that the igniter 24 is fixed or fastened in the first holder element 30 by means of bonding. Between the igniter 24 and the first holder element 30 a sealing element 36 may be inserted to increase tightness in the joining area. The sealing element 36 in the illustrated embodiment is an O-ring pinched between the igniter 24 and the first holder element 30.

(20) The first holder element 30 thus forms a seat 38 for the igniter 24 and the sealing element 36 via the retaining portion 34.

(21) It is further evident from FIG. 1 that the gas generator housing 12 in the end section 14 has two openings 40 through each of which a detent element 42 of the igniter support 22, especially of the second holder element 32, extends. In the shown embodiment, the detent elements 42 are hook-shaped, which is why they can also be referred to as detent hooks. There may be introduced even more than two openings 40, in particular three or four openings, to a sidewall of the gas generator housing 12, preferably being radially circumferential. The shape of the openings 40 may be designed to be round, especially circular, or circumferentially slit-shaped or rectangular, wherein here also the shapes of the openings 40 may be different from each other, wherein e.g. a shape of one opening 40 may be different from that of all further openings 40 in order to obtain sort of a positioning or marking option of the gas generator housing 12.

(22) Each of the detent elements 42 extends from an end face 44 of the second holder element 32, which is remote from the first holder element 30, in the direction of the first holder element 30, each of the detent elements 42 comprising a spring portion 46 which provides, inter alia, a desired elasticity of the detent elements 42. Adjacent to the spring portion 46, there is provided a respective detent portion 48 forming a corresponding detent surface 50 which, in the locked condition of the detent element 42 in the opening 40, rests against the edge of the corresponding opening 40.

(23) Furthermore, it is evident from FIG. 1 that the second holder element 32 has an undercut 52 in which the igniter unit 20, especially the socket 26, is partially received. The undercut 52 ensures the socket 26 and thus the igniter unit 20 to be arranged true to position in the igniter support 22. The second holder element 32 consequently serves for positioning the socket 26.

(24) As a consequence, the igniter 24 of the igniter unit 20 is positioned via the first holder element 30 and the socket 26 of the igniter unit 20 is positioned via the second holder element 32 in a desired way inside the gas generator housing 12. Accordingly, the igniter support 22 serves for positioning and connecting the igniter unit 20 within the gas generator housing 12.

(25) FIG. 2 illustrates that the gas generator housing 12 has two stop faces 54 for the subassembly 16, especially for the second holder element 32, so that the subassembly adopts a predefined position with respect to the gas generator housing 12 when the subassembly 16 is inserted into the gas generator housing 12, especially press-fitted in the axial end section 14. The second holder element 32 may include a radially protruding step 56 via which the subassembly 16 then abuts on corresponding stop faces 54. The step 56 may be a radially protruding pressing lug configured to be resilient and, resp. plastically deformable in the radial direction.

(26) The two stop faces 54 may be designed differently as regards their axial position, thus allowing a defined orientation in the circumferential direction of the subassembly 16, especially of the second holder element 32, to be fixed in the gas generator housing 12. Also, the stop faces 54 can have different widths. The step 56 and, resp., corresponding steps 56 are designed differently in an analogous manner.

(27) FIG. 3 demonstrates how a ground contact of the igniter unit 20, especially of the socket 26, is produced via a separately formed ground element 58 with the gas generator housing 12. The first holder element 30 made from metal to which the ground element 58 is connected is utilized for the electric connection. The ground element 58 can be designed in the form of a ground claw which appropriately claws into the first holder element 30 to contact a circumferential inner area of the first holder element 30 in an electrically conducting manner.

(28) In general, the ground element 58 may be part of a metal insert being surrounded by the socket 26 made from plastic material. The metal insert may serve, in addition to establishing a ground contact, also for forming a short circuit element which short-circuits the contact pins 28 of the igniter 24 in an electrically conducting manner, unless a plug is plugged in the socket 26. As soon as a plug is plugged into the socket 26, the short circuit element is pressed away by the contact pins 28 in such a way that the previously electrically conducting short circuit between the two contact pins 28 is neutralized.

(29) In FIGS. 4 and 5, the first holder element 30 is illustrated in detail. It is evident from the Figures that the first holder element 30 has a substantially annular base 60 having a longitudinal axis S1 that extends centrally through a recess 62 in the base 60 in the axial direction.

(30) The recess 62 is moreover surrounded by a collar edge 63 designed in ring shape.

(31) The first holder element 30 furthermore has an axial contact surface 64 which is reset against a radially outer edge zone 66. The axial contact surface 64 is moreover reset even against the collar edge 63 extending, just as the edge zone 66, in the axial direction over the contact surface 64. Each of the collar edge 63, the axial contact surface 64 and the edge zone 66 faces the second holder element 32 in the assembled condition of the igniter support 22, viz. when the first holder element 30 is coupled to the second holder element 32 (cf. FIGS. 1 to 3).

(32) The collar edge 63 as well as the edge zone 66 are arranged substantially concentrically around the longitudinal axis S1 so that therebetween a recessed free space is formed which is axially delimited by the contact surface 64.

(33) From the axial contact surface 64 four lugs 68 project in the axial direction, i.e. in the direction of the second holder element 32, when the igniter support 22 is in the assembled condition. The lugs 68 are ramp-shaped, wherein they are rising in the axial direction from radially outside to radially inside, in the direction of the second holder element. In addition, the lugs 68 start from the edge zone 66 from radially outside to radially inside, and thus from a position raised vis-à-vis the axial contact surface 64. The lugs may enclose also other geometric three-dimensional shapes, however, and may be rectangular or cube-shaped, for example.

(34) The lugs 68 have centering surfaces 70 that are bent radially inwardly. Each of the centering surfaces 70 of the lugs 68 constitutes a segment of a surface area of a cylinder, with the socket 26 of the igniter unit 20 being centered via the centering surfaces 70. The centering surfaces 70 form especially segments of a joint surface area of one single cylinder, thereby accordingly facilitating centering of the socket 26.

(35) From FIG. 3, it is moreover resulting that the lugs 68, preferably the centering surfaces 70 thereof, serve for contacting the ground element 58. Hence, the ground element 58 abuts on at least one of the centering surfaces 70 to establish the electric connection.

(36) Further, the lugs 68 have respective contact surfaces 72 in the circumferential direction via which the lugs 68 interact with the second holder element 32 to configure a form closure in the circumferential direction, as will be explained hereinafter.

(37) In the shown embodiment, one of the lugs 68 (at the top left in FIG. 4) has a width unlike that of the other lugs 68, thereby ensuring orientation of the two holder elements 30, 32 relative to each other when the latter are assembled.

(38) The second holder element 32 shown in detail in FIGS. 6 and 7 equally has a substantially annular base body 73 including a central recess so that also the second holder element 32 has a longitudinal axis S2 which extends along the axial direction.

(39) The base body 73 has an axial end face 74 facing, in the assembled condition, the first holder element 30 (see FIG. 3), with the lug 68 and the end face 74 respectively contacting each other. The axial end face 74 is reset in the axial direction vis-à-vis an outer edge 75 which is configured two times partly circular.

(40) Moreover, in the shown embodiment, four projections 76 which together form an axial pressure surface 78 that is accordingly parallel to the axial end face 74 protrude in the axial direction from the axial end face 74. Respective opposing projections 76 are designed to be identical.

(41) On the axial pressure surface 78, especially on the respective projections 76, there are moreover formed pressing lugs 79 which protrude in the axial direction vis-à-vis the pressure surface 78.

(42) The second holder element 32 is pressed, in the assembled condition of the first and second holder elements 30, 32, against the first holder element 30 in such a way that the pressing lugs 79 which are axially protruding are pressed onto the axial contact surface 64 of the first holder element 30, thereby bringing about the form closure in the axial direction (see FIGS. 1 to 3).

(43) In addition, the lugs 68 of the first holder element 30 may be pressed onto the axial end face 74 of the second holder element 32. Therefore, the lugs 68 of the first holder element 30 may equally be perceived as pressing lugs.

(44) The lugs 68 of the first holder element 30 and the projections 76 of the second holder element 32 are dimensioned so that therebetween free spaces are formed in which the projections 76 and, resp., the lugs 68 may appropriately engage. Accordingly, the two holder elements 30, 32 at least partly engage in their assembled condition, viz. via their lugs 68 and projections 76.

(45) The axially protruding projections 76 equally include, when viewed in the circumferential direction, bearing surfaces 80 via which the second holder element 32 makes a form closure in the circumferential direction with the bearing surfaces 72 of the first holder element 30 so that the two holder elements 30, 32 substantially cannot be rotated relative to each other.

(46) Both the lugs 68 and the projections 76 have at their respective ends opposed in the circumferential direction two bearing surfaces 72 (relating to the lugs 68) and 80 (relating to the projections 76).

(47) The projections 76 of the second holder element 32 are moreover received by form closure between the outer edge 66 and the collar edge 63 of the first holder element 30 in the radial direction so that the two holder elements 30, 32 in the assembled condition are substantially fixed relative to each other in the radial direction.

(48) It is further evident from FIG. 7 that the second holder element 32 has radially protruding spring lugs 82 via which the second holder element 32 is supported and centered in the radial direction in the condition installed in the gas generator housing 12. The radially protruding spring lugs 82 also serve for compensating manufacturing tolerances which cannot be avoided during manufacture.

(49) Moreover, the radially protruding spring lugs 82 may interact with the stop faces 54 of the gas generator housing 12 in the axial direction. The spring lugs 82 are configured such that at an axial pressure they do not compress in the radial direction, that is why the subassembly 16 can abut on the stop faces 54 in the axial direction so that the subassembly 16 is at the intended location as regards its axial position.

(50) Generally, the two holder elements 30, 32 are substantially symmetric, with the longitudinal axes S1, S2 thereof in the mounted condition coinciding with the longitudinal axis S of the gas generator 10.

(51) Thus, there are provided a gas generator 10, a subassembly 16 comprising the igniter unit 20 as well as the igniter support 22 by which an electric contact and, resp., a ground contact can be easily established, wherein the igniter support 22 in addition can be produced in a cost-efficient and simple manner.

(52) For manufacturing the gas generator 10 at first the single parts can be provided, i.e. the gas generator housing 12 as well as the subassembly 16, wherein the latter may equally be provided in the dismounted condition, i.e. the igniter unit 20 comprising the igniter 24 and the socket 26, as well as the igniter support 22 comprising the first and second holder elements 30 and 32.

(53) When manufacturing the gas generator housing 12, preferably in one production step the openings 40 and the stop faces 54 are formed in the gas generator housing 12 to minimize possible manufacturing tolerances. Further, the gas generator housing 12 has an inner diameter that constitutes a press-fit for the first holder element 30 when the latter is inserted or press-fitted into the gas generator housing 12.

(54) Before this, however, the igniter 24 is coupled to the first holder element 30 by inserting the igniter 24 and the sealing element 36 into the seat 38 and subsequently forming, especially beading, the retaining portion 34 of the first holder element 30. Alternatively, or additionally, the igniter 24 may also be glued and, resp., inserted into the first holder element 30 and may be bonded with the same.

(55) Subsequently, the socket 26 is inserted into the second holder element 32 which is then assembled with the first holder element 30. Here, the holder elements 30, 32 align with each other in the circumferential direction so that they engage at least partially via their lugs 68 and, resp., projections 76. At the same time, the socket 26 is centered via the centering surfaces 70. It is also imaginable that initially the second holder element 32 is coupled to or nested with the first holder element 30 and after that the socket 26 is inserted into the second holder element 32.

(56) In addition, the at least one ground element 58 can be coupled or brought into contact with the first holder element 30, especially with one of the centering surfaces 70. Accordingly, the ground element 58 may already be an integral part of the socket 26.

(57) Then the subassembly 16 manufactured before and comprising the igniter unit 20 as well as the igniter support 22 is inserted through the open end of the gas generator housing 12 into the latter until the subassembly 16 axially abuts on the stop faces 54 of the gas generator housing 12 via the second holder element 32, especially via a respective step.

(58) The detent elements 42 of the second holder element 32 then snap substantially simultaneously into the corresponding openings 40 in the gas generator housing 12 so that the subassembly 16 is (pre)fixed.

(59) Subsequently, a welded connection can further be formed between the gas generator housing 12 and the first holder element 30 so that the subassembly 16 is fixed in its final position.

(60) By the welded connection at the latest, an electric connection is established between the first holder element 30 and the gas generator housing 12, wherein typically said electric connection was given already before due to the press-fit.

(61) Alternatively, the socket 26 may be integrated, i.e. injected or attached by injection molding, already in one piece in the second holder element 32 so that merely one single plastic component is present which at the same time is part of the igniter support 22 and of the igniter unit 20.

(62) Furthermore, the two holder elements 30, 32 may also be inserted successively and each individually into the gas generator housing 12, viz. initially the first holder element 30 and subsequently the second holder element 32. The ground contact can be established by ground elements 58 in the form of ground claws which claw into the already inserted first holder element 30.

(63) When press-fitting the second holder element 32, the latter presses the first holder element 30 along the press-fit formed in the gas generator housing 12 until the second holder element 32 abuts on the stop face(s). In so doing, also the corresponding detent elements 42 lock in the openings 40 in a way analogous to the afore-described embodiment. As an alternative to that, mounting can be carried out as follows. The sealing element 36 is inserted into the first holder element 30, then the igniter 24 is equally inserted into the first holder element 30, axially onto the sealing element 36. Now the igniter 24 is fastened to the first holder element 30 by crimping the retaining portion 34 of the first holder element 30 for forming a prefabricated assembly group.

(64) The assembly group prefabricated in this way is now inserted into the gas generator housing 12 at the axial end section 14 thereof and is fastened by welding the first holder element 30 to the gas generator housing 12.

(65) After that, the second holder element 32 is inserted into the generator housing 12 in the direction of the prefabricated assembly group and is aligned with the first holder element 30 in the radial direction, the second holder element 32 being fixed to the gas generator housing 12 by locking the detent elements 42 of the second holder element 32 in the corresponding openings 40 within the gas generator housing 12.

(66) Finally, the socket 26 having an integrated ground element 58 is inserted into the second holder element 32. As an alternative to that, the socket 26 may be manufactured just by injecting or attaching by injection-molding the socket 26 to the second holder element 32, with a ground element 58 being also injected into the socket 26.