Gas generator for an airbag system with radial partition

Abstract

Gas generator (1) for an airbag device, comprising: a housing (10) with a cover plate (12), a base plate (22) axially opposite the cover plate (12) and a circumferential wall (13) which is arranged between the cover plate (12) and the base plate (22) and is provided with a gas discharge opening (14); a partition (50) which is provided with a first connecting hole (51) which includes a single through-hole (51), wherein the partition (50) is arranged radially in the housing (10) to divide an interior of the housing (10) into a first combustion chamber (30) on one side of the top plate (12) which accommodates a first gas-generating means (31) and a second combustion chamber (40) on one side of the bottom plate (22) which accommodates a second gas-generating means (41); a first igniter (32) for burning the first gas-generating agent (31) and a second igniter (42) for burning the second gas-generating agent (41), wherein the first and second igniters (32, 42) are attached to the base plate (22); characterized by the fact that the gas generator (1) further comprises a cylindrical guide element (60) arranged between the first igniter (32) and the first connecting hole (51) of the partition (50) and provided with a second connecting hole (65) in a cylindrical wall (64) thereof, wherein the cylindrical guide element (60) is arranged such that it surrounds the first detonator (32), such that a first end opening (61) of it is arranged on the side of the base plate (22) and a second end opening (62) of it is connected to the first connecting hole (51) of the partition (50), the second end opening (62) or the first connecting hole (51) is closed by a first closing element (57), wherein the second end opening (62) or the first connecting hole (51) is adjacent to the first combustion chamber (30), wherein the second connecting hole (65) is closed by a second closing element (67), wherein the second connecting hole (65) is adjacent to the second combustion chamber (40), and a breaking pressure of the first closing element (57) is set lower than a breaking pressure of the second closing element (67).

Description

Technical area

[0001] The present invention relates to a gas generator for a radial partition type airbag device mounted in an automobile. Description of the state of the art

[0002] A gas generator for an airbag device according to the preamble of claim 1 and a gas generator for an airbag device according to the preamble of claim 2 are already known from JP 2003-063349 A. Further gas generators are described in JP 2003-312434 A and US 2008 / 0257195 A1.

[0003] A gas generator in which an interior of a housing is vertically separated by a partition wall is known.

[0004] The Fig. 1 to 3 in US Pat. No. 7,950,693 B2 disclose a gas generator in which a partition plate 36 is disposed within a housing 12 to form a first chamber 40 on top of the housing 12 and a second chamber 42 on the bottom. Igniters 74 and 94 are arranged to combust a gas generating agent in the respective chambers. A hole 46 through which a cup 82 passes and an opening 44 into which a plug element 50 is inserted are formed in the partition plate 36. When the igniter 74 is actuated, the cup 82 is ruptured, causing the gas generating agent in the first chamber 40 to be ignited and combusted. When the igniter 94 is actuated, the gas generated in the second chamber 42 flows directly into the first chamber 40 through the opened opening 44, since the plug element 50 blocking the opening 44 of the separating wall 36 is pulled out.

[0005] It is an object of the present invention to provide a gas generator for an airbag device which is capable of actuating a first igniter and a second igniter with a time difference and igniting and burning a first gas generating agent and a second gas generating agent separately, and in which the second gas generating agent is prevented from being ignited and burned by the first igniter actuated first.

[0006] This object is achieved by the gas generator for an airbag device according to claim 1 and the gas generator for an airbag device according to claim 2. Preferred embodiments are claimed in the dependent claims. Summary of the invention

[0007] A first aspect of the present invention (hereinafter referred to as "the first aspect") provides a gas generator for an airbag device, including: a housing having a top plate, a bottom plate disposed axially opposite the top plate, and a peripheral wall disposed between the top plate and the bottom plate and provided with a gas discharge opening; a partition wall provided with a first communication hole including a single through-hole, the partition wall being radially disposed in the casing to divide an interior of the casing into a first combustion chamber on the top plate side accommodating a first gas generating agent and a second combustion chamber on the bottom plate side accommodating a second gas generating agent; a first igniter for burning the first gas generating agent and a second igniter for burning the second gas generating agent, the first and second igniters being attached to the base plate; a cylindrical guide member disposed between the first igniter and the first connecting hole of the partition wall and provided with a second connecting hole in a cylindrical wall thereof, wherein the cylindrical guide member is arranged to enclose the first igniter so that a first end opening thereof is arranged on the side of the bottom plate and a second end opening thereof is connected to the first communication hole of the partition wall, the second end opening or the first communication hole is closed by a first closure member, wherein the second end opening or the first communication hole is adjacent to the first combustion chamber, wherein the second communication hole is closed by a second closure member in a state in which the second communication hole faces the second combustion chamber, and a breaking pressure of the first closure member is set lower than a breaking pressure of the second closure member.

[0008] A second aspect of the present invention (hereinafter referred to as "the second aspect") provides a gas generator for an airbag device, comprising: a housing having a top plate, a bottom plate disposed axially opposite the top plate, and a peripheral wall disposed between the top plate and the bottom plate and provided with a gas discharge opening; a partition wall provided with a first communication hole including a single through-hole, the partition wall being radially disposed in the casing to divide an interior of the casing into a first combustion chamber on the top plate side accommodating a first gas generating agent and a second combustion chamber on the bottom plate side accommodating a second gas generating agent; a first igniter for burning the first gas generating agent and a second igniter for burning the second gas generating agent, the first and second igniters being attached to the base plate; a cylindrical guide member disposed between the first igniter and the first connecting hole of the partition wall and provided with a second connecting hole in a cylindrical wall thereof, wherein the cylindrical guide member is arranged to enclose the first igniter so that a first end opening thereof is arranged on the bottom plate side and a second end opening side thereof enters the first communication hole and faces an interior of the first combustion chamber, and wherein the second end opening is closed by a first closure member, wherein the second end opening is adjacent to the first combustion chamber, wherein the second communication hole is closed by a second closure member in a state in which the second communication hole faces the second combustion chamber, and wherein a breaking pressure of the first closure member is set lower than a breaking pressure of the second closure member. Brief description of the drawings

[0009] The present invention will be more fully understood from the following detailed description and the accompanying drawings which are given for illustrative purposes only and thus are not limitative of the present invention and wherein: [ Fig. 1] Fig. Figure 1 shows an axial cross-sectional view of a gas generator of the present invention; [ Fig. 2] Fig. Figure 2 shows a partial cross-sectional view of a housing of the gas generator according to Fig. 1; [ Fig. 3] Fig. 3 is a schematic plan view including a partial cross-sectional view showing a positional relationship between a second communication hole and a second igniter (portions unnecessary for showing the positional relationship are omitted); [ Fig. 4] Fig. Fig. 4 shows in (a) a front view illustrating an embodiment of a second closure member of a gas generator, and in (b) an explanatory diagram of an operation when the second closure member shown in (a) is used; and [ Fig. 5] Fig. Figure 5 shows an axial cross-sectional view of a gas generator, which differs from that shown in Fig. 1 shown embodiment of the gas generator. Detailed description of the invention

[0010] The present invention provides a gas generator for an airbag device capable of actuating a first igniter and a second igniter with a time difference and igniting and burning a first gas generating agent and a second gas generating agent separately, and preventing the second gas generating agent from being ignited and burned by the first igniter actuated first.

[0011] When a bottom plate of a housing is arranged on the bottom side and a top plate thereof is arranged on the top side in the gas generator of the present invention, an interior of the housing is vertically divided by a partition wall into two combustion chambers, i.e., a first combustion chamber on the top side and a second combustion chamber on the bottom side. The first igniter and the second igniter are attached to holes formed in the bottom plate, respectively.

[0012] The first igniter and the first combustion chamber (the first gas generating agent) are connected to each other via a cylindrical guide member, and the first igniter and the first gas generating agent are not in contact with each other. A disposition state of the cylindrical guide member is not limited as long as a first end opening is located on the bottom plate side and a second end opening or a first communication hole faces the first combustion chamber. For example, the second end opening and the first communication hole may abut each other to form a single hole. In this case, by closing the second end opening or the first communication hole with a first closure member, a path extending from an interior of the cylindrical guide member to the first combustion chamber is closed.A known transfer charge or a gas generating agent acting as a known transfer charge can be accommodated inside the cylindrical guide element if required.

[0013] The housing, the partition and the cylindrical guide element are made of metal such as iron or stainless steel.

[0014] Since the second igniter is arranged within the second combustion chamber, the second igniter and the second gas generating agent are in contact with each other.

[0015] As the first closure member that closes the second end opening of the cylindrical guide member and as the second closure member that closes a second communication hole formed in a cylindrical wall of the cylindrical guide member, a metallic adhesive tape in which an adhesive layer is formed on a metallic band made of stainless steel, aluminum, or the like is applied to close the second end opening and the communication hole, respectively. Instead of closing the second end opening of the cylindrical guide member with the first closure member, the first communication hole of the partition wall may be closed with the first closure member.Furthermore, with respect to the second end opening and the second communication hole, a bag container or a cup container made of aluminum (a bag container or a cup container filled with a transfer charge) may be arranged within the cylindrical guide member, and portions of the bag container facing the second end opening and the second communication hole may be used as the first closure member and the second closure member, respectively. In this case, the first closure member and the second closure member are integrally formed.

[0016] When the first igniter is actuated and combustion products such as flames are generated (when using the transfer charge, combustion products such as flames are generated by combustion of the transfer charge), an increase in pressure inside the cylindrical guide member causes the first closure member, which closes the second end opening, to rupture, and the combustion products enter the first combustion chamber, igniting and combusting the first gas generating agent. The combustion gas produced by the combustion of the first gas generating agent is released from a gas discharge opening formed in a peripheral wall of the casing. The pressure generated inside the cylindrical guide member is higher than a rupture pressure of the first closure member but lower than a rupture pressure of the second closure member.

[0017] When the second igniter is actuated and combustion products are generated, the second gas generating agent is immediately ignited and burned, generating combustion gas. The generated combustion gas first breaks the second closure member of the second communication hole formed in the cylindrical wall of the cylindrical guide member and enters the cylindrical guide member, enters the first combustion chamber from the opened first communication hole, and is then discharged from the gas discharge port formed in the peripheral wall of the casing. Since the second closure member corresponds to a fragile portion and the partition wall has no means to allow direct communication between the first combustion chamber and the second combustion chamber, the second closure member is always broken when the pressure inside the second combustion chamber increases.

[0018] As described above, in the gas generator according to the present invention, the second sealing element is broken with good reproducibility when the gas generating agent burns in the second combustion chamber. Therefore, unlike the invention disclosed in US Pat. No. 7,950,693 B, it is unnecessary to adjust the dimensions and shapes of a can and a through hole for connecting the first combustion chamber to the second combustion chamber with high working accuracy.

[0019] Furthermore, in the gas generator according to the present invention, a relationship represented as "rupture pressure of a first sealing member < fracture pressure of a second sealing member" is satisfied. The first sealing member is ruptured first at the time of actuation, pressure drops after the preliminary rupture of the first sealing member, and thus the second sealing member is never ruptured when the first igniter is actuated. Accordingly, the entry of the combustion gas from the first combustion chamber into the second combustion chamber is prevented by utilizing a fracture pressure difference between the sealing members. This makes it possible to prevent a malfunction such as the second gas generating agent being ignited and burned inside the second combustion chamber by actuating the first igniter with a straightforward and simple structure.The breaking pressures can be adjusted by distinguishing the specifications (material, thickness, etc.) of the respective closure elements or by distinguishing the diameters of the respective holes to be covered by the closure elements. Alternatively, both the specifications of the closure elements and the diameters of the holes can be distinguished.

[0020] A gas generator of the second aspect is the same as the gas generator of the first aspect, except that a positional relationship between a first communication hole and the second end opening side of a cylindrical guide member is different. The second end opening side of a cylindrical guide member includes an aspect in which the second end opening side of the cylindrical guide member enters the first communication hole and faces an interior space of the first combustion chamber, and an aspect in which the second end opening side enters the first communication hole, extends beyond the first communication hole, and is located inside the first combustion chamber. Here, the second end opening of the cylindrical guide member is located outside the partition wall and is located inside the first combustion chamber and faces the ceiling plate.The gas generator of the second aspect works similarly to the gas generator of the first aspect.

[0021] In a preferred aspect of the gas generator according to the present invention (the first aspect and the second aspect), the second communication hole of the cylindrical guide member is formed only on a surface of the cylindrical wall opposite to a surface facing the second igniter.

[0022] When the second igniter is actuated, the second gas generating agent within the second combustion chamber is ignited and successively combusted from the vicinity of the second igniter. At this point, if the second communication hole formed in the cylindrical wall of the cylindrical guide member faces the second igniter, a situation occurs that at a point where part of the second gas generating agent is combusted in the second combustion chamber, only the second gas generating agent present between the second igniter and the second communication hole is preferentially combusted, and the second gas generating agent present at other locations is less likely to combust.Furthermore, the second closure member may be directly exposed to the ignition energy (high-temperature gas, flames, pressure, etc.) generated upon actuation of the second igniter and may be ruptured before the pressure in the second combustion chamber rises to a predetermined pressure. In this case, the combustion performance of the entire second gas generating agent is impaired. If the second communication hole is opened and a combustion gas leak occurs, leaving a portion of the second gas generating agent unburned as described above, it is conceivable that a problem of delayed combustion of the unburned second gas generating agent may occur.In view of this, by forming the second communication hole of the cylindrical guide member only on a surface (a radially opposite surface) opposite to a surface facing the second igniter of the cylindrical wall, as in the present aspect, the combustion gas generated in the second combustion chamber contacts substantially all of the second gas generating agent in the second combustion chamber until the combustion gas reaches the second communication hole, thereby promoting combustion of all of the second gas generating agent. A too short distance between the second communication hole and the peripheral wall of the casing results in a reduced amount or absence of the second gas generating agent between the second communication hole and the peripheral wall, which undesirably results in the second closure member taking a longer time to break.

[0023] In a further preferred aspect of the gas generator according to the present invention (the first aspect and the second aspect), the first closure member and the second closure member are made of a same material and have a same thickness, and the second communication hole is formed in plurality, and a hole diameter of each of the second communication holes is smaller than a hole diameter of the second end opening.

[0024] The present aspect is one of the simplest means for satisfying the relationship expressed as "breaking pressure of the first locking element < breaking pressure of the second locking element." Since the present aspect only involves adjusting the sizes of the second end opening and the hole diameters of the second connecting holes, the present aspect is easier to implement than adjusting the sizes and shapes of the opening 44 and the plug element 50 in US7950693B.

[0025] The following can be listed as further means: a method for setting the hole diameter of the first connecting hole and the hole diameter of each of the second connecting holes to a same hole diameter and for adjusting a size relationship between strengths (tensile strengths) of the first closure member and the second closure member; a method for adjusting a size relationship between the hole diameter of the first connection hole and the hole diameter of each of the second connection holes and for further adjusting a size relationship between strengths (tensile strengths) of the first closure element and the second closure element; and a method of applying a score to the first closure element to make the first closure element more breakable.

[0026] In another preferred aspect of the gas generator according to the present invention (the first aspect and the second aspect), when the breaking pressure of the second sealing element is 1, the breaking pressure of the first sealing element is not more than 0.90.

[0027] When the relationship expressed as "breaking pressure (p1) of the first locking element < breaking pressure (p2) of the second locking element" is satisfied, p1 / p2 ≤ 0.90 increases reliability and is therefore preferable. Regarding p1 / p2, for example, when the first locking element and the second locking element are the same and an area of ​​the second end opening is twice the area of ​​each of the second connecting holes, p1 / p2 = 0.5, because the first locking element is subjected to twice the pressure exerted on the second locking element.

[0028] In a further preferred aspect of the gas generator according to the present invention (the first aspect and the second aspect), the second end opening of the cylindrical guide member has an inwardly projecting annular surface, wherein the first closure member is arranged on the annular surface from the inside and closes the second end opening and the second closure element is arranged from the inside on the cylindrical wall of the cylindrical guide element and closes the second connecting hole.

[0029] The first closure member is arranged to face an ignition portion (a portion in which an ignition charge is accommodated) of the first igniter, and when the first closure member is arranged on an inner side of the annular surface, the first closure member is less likely to break even when exposed to ignition energy (high-temperature gas, flames, pressure, and the like) generated at the time of actuation of the igniter.Furthermore, when comparing a case where the second sealing element is applied from the outside of the cylindrical guide member and a case where the second sealing element is applied from the inside of the cylindrical guide member, when the first igniter is operated in the same manner and the second sealing element is pressurized from the inside, the case where the second sealing element is applied from the inside is preferable because the second sealing element is less likely to be broken and the combustion performance of the transfer charge is maintained within the cylindrical guide member.

[0030] Alternatively, the first closure element can be arranged on the outside of the cylindrical guide element, as long as the breaking pressure of the second closure element is kept higher than the breaking pressure of the first closure element. In this case, the first closure element can close either the inside or the outside of the first connection hole.

[0031] Since the magnitude ratio between the rupture pressure of the first closure member closing the second end opening and the rupture pressure of the second closure member closing the second communication hole is defined, with the gas generator according to the present invention, in the first igniter, when the first igniter is first actuated, only the first closure member is ruptured, the second closure member is not ruptured, and the second gas generating agent within the second combustion chamber is not ignited and burned.

[0032] The gas generator according to this invention is usable as a gas generator for an airbag device mounted in an automobile.

[0033] Embodiments of the present invention: An embodiment of a gas generator according to the present invention will be described with reference to Fig. 1 described.

[0034] A gas generator 1 comprises a housing 10 with a diffuser housing 11 and a closure housing 21. The diffuser housing 11 and the closure housing 21 are both made of a metal such as iron or stainless steel. The diffuser housing 11 includes a cover plate 12 and an upper peripheral wall 13, and a plurality of gas discharge openings 14 are formed in the upper peripheral wall 13 at regular intervals in the circumferential direction. The upper peripheral wall 13 has a flange 15 at one of its openings. The plurality of gas discharge openings 14 are closed from the inside with a metallic sealing band.

[0035] The breechblock housing 21 includes a bottom plate 22 and a lower peripheral wall 23. Two spaced-apart holes are formed in the bottom plate 22, and a first igniter 32 and a second igniter 42 are mounted at each of the two holes. The first igniter 32 is arranged at a position closer to the central axis X of the housing 10, and the second igniter 42 is arranged at a position farther away from the central axis X of the housing 10 compared to the first igniter 32. In the Fig. 1, the first igniter 32 is arranged such that a center axis of the first igniter 32 lies in a range of 20% to 30% of a distance from the center axis X to the lower peripheral wall 23. Furthermore, in the embodiment shown in Fig. 1, the second igniter 42 is arranged such that a central axis of the second igniter 42 lies in a range of 40% to 60% of the distance from the central axis X to the lower peripheral wall 23.

[0036] In the housing 10, an inner surface 13a near the opening of the upper peripheral wall 13 of the diffuser housing 11 and an outer surface 23a near an opening of the lower peripheral wall 23 of the closure housing 21 are in contact with each other, and the contact portion is welded and fixed in this state. As shown in Fig. 2, in the housing 10, the closure housing 21 is inserted into the diffuser housing 11 so that an annular stepped surface 24 is formed between the upper peripheral wall 13 and an annular end surface of the lower peripheral wall 23.

[0037] An interior of the housing 10 is divided by a radially arranged partition wall 50 into a first combustion chamber 30 on the cover plate side 12 and a second combustion chamber 40 on the base plate side 22. A first gas-generating agent 31 is housed in the first combustion chamber 30, and a second gas-generating agent 41 is housed in the second combustion chamber 40.

[0038] The partition wall 50 has a first communication hole 51 arranged eccentrically to the central axis X of the casing 10 toward the peripheral wall (the upper peripheral wall 13 and the lower peripheral wall 23), and the first communication hole is a single through-hole. The partition wall 50 has a flat surface 52, an outer annular wall 53 extending from an outer peripheral edge of the flat surface 52 toward the cover plate 12, and an outer annular surface 54 protruding radially outward from the outer annular wall 53. Furthermore, the partition wall 50 has an inner annular wall 55 extending from the flat surface 52 toward the cover plate 12 along a cylindrical guide member 60 arranged in the second combustion chamber 40, and an inner annular surface 56 protruding radially inward from the inner annular wall 55.In the partition wall 50, the outer annular surface 54 abuts the annular stepped surface 24 and the inner annular surface 56 abuts an annular surface 63 of the cylindrical guide element 60.

[0039] In the Fig. In the embodiment shown in Figure 1, a cylindrical filter 70 is arranged. In the cylindrical filter 70, a first end surface 71 abuts the cover plate 12, a second end surface 72 abuts the flat surface 52, and a lower part (on the side of the bottom plate 22) of an outer peripheral surface 73 abuts the outer annular wall 53. A cylindrical gap is formed between the cylindrical filter 70 and the upper peripheral wall 13, which is provided with the gas discharge openings 14.

[0040] The cylindrical guide member 60 is arranged between the first igniter 32 and the first communication hole 51 of the partition wall 50 so as to enclose the first igniter 32. In the cylindrical guide member 60, a first end opening 61 abuts the bottom plate 22, and a second end opening 62 is arranged to communicate with the first communication hole 51 of the partition wall 50 and face the first combustion chamber. The radially inwardly projecting annular surface 63 is formed at the second end opening 62. The annular surface 63 is adjacent to a bottom surface (a surface on the bottom plate 22 side) of the inner annular surface 56 of the partition wall 50. The second end opening 62 (an opening of the annular surface 63) has a size equal to or larger than that of the first communication hole 51 (an opening of the inner annular surface 56).In the cylindrical guide member 60, a plurality of second communication holes 65 are formed in a cylindrical wall 64 opposite the second combustion chamber 40. Although the plurality of second communication holes 65 may be formed at regular intervals in the cylindrical wall 64 in the circumferential direction, as shown in FIGS. Fig. 1 and Fig. 3, the plurality of second communication holes 65 are preferably formed only in a surface radially opposite a surface of the cylindrical wall 64 facing the second igniter 42. An interior of the cylindrical guide member 60 is a receiving space for the first igniter 32, and when a transfer charge is housed in the cylindrical guide member 60, a remaining space without the first igniter 32 is a transfer charge chamber 66.

[0041] A first closure member 57, formed from a metallic adhesive tape and applied from the inside to the annular surface 63 of the cylindrical guide member 60, closes the second end opening 62, thus closing the first communication hole 51 between the interior of the cylindrical guide portion 60 and the first combustion chamber before actuation. The first closure member 57 can be applied from the inside to the inner annular surface 56 of the first communication hole 51. However, it is preferable to apply the first closure member 57 to the annular surface 63 of the cylindrical guide member 60 because a distance to the first igniter 32 is reduced and the first closure member 57 is more easily broken. A diameter of the second end opening 62 is larger than an opening diameter of each of the second communication holes 65.The plurality of second communication holes 65 are closed from the inside of the cylindrical wall 64 by a second closure member 67 formed of a metallic adhesive tape.

[0042] The same metallic adhesive tape of the same thickness is used for the first closure member 57 and the second closure member 67. A hole diameter (about 1 to 2 mm) of each of the plurality of second communication holes 65 is sufficiently smaller than a hole diameter (about 5 to 10 mm) of the first communication hole 51. Therefore, a breaking pressure of the first closure member 57 is lower than a breaking pressure of the second closure member 67, and when the breaking pressure of the second closure member 67 is 1 at the time of actuation of the first igniter 32, the breaking pressure of the first closure member 57 ranges from 0.1 to 0.4.

[0043] Fig. 4 shows a further embodiment of the second closure element 67.

[0044] In the second sealing member 67, an inverted U-shaped cut (or a slit) 68 is formed in a region including the plurality of second communication holes 65 (a region 67a) therein. However, even though the cut (or the slit) 68 is formed, the relationship represented as "breaking pressure of the first sealing member 57 < breaking pressure of the second sealing member 67" is satisfied. Since the second sealing member 67 is applied to the cylindrical wall 64 from the inside, the cut 68 is not broken even if pressure is applied from the inside at the time of actuation of the first igniter 32.

[0045] Next, an embodiment of a method for constructing the gas generator 1 will be described.

[0046] The first igniter 32 and the second igniter 42 are mounted on the two holes in the base plate 22 of the breechblock 21. The cylindrical guide element 60 is then attached to the first igniter 32. The second gas generating agent 41 is housed in the second combustion chamber 40. The partition wall 50 is then arranged such that the outer annular surface 54 abuts the annular stepped surface 24, the outer annular wall 53 abuts the lower peripheral wall 23, the inner annular surface 56 abuts the annular surface 63, and the inner annular wall 55 abuts the cylindrical wall 64. At this point, since the respective center axes of the first communication hole 51 and the second end opening 62 coincide and the size of the second end opening 62 is larger than the size of the first communication hole 51 (size of the first communication hole 51 < size of the second end opening 62), the entire first communication hole 51 is opened when the first closure member 57 is broken.Subsequently, after the cylindrical filter 70 is arranged, the first gas generating agent 31 is accommodated. Subsequently, the closure housing 21 is covered by the diffuser housing 11, and their contact portion is welded.

[0047] A function of the Fig. The gas generator 1 shown in Figure 1 is described below when mounted on an airbag device. The gas generator 1 according to the present invention has an advantageous effect when the first igniter 32 is activated first and the second igniter 42 is activated with a delay, or when only the first igniter 32 is activated. The following example describes the case where the first igniter 32 is activated first and the second igniter 42 is activated with a delay.

[0048] When the first igniter 32 is first actuated by flames and the like generated by the first igniter 32, the transfer charge within the transfer charge chamber 66 is ignited and burned to generate combustion products. The combustion products generated within the transfer charge chamber 66 rupture the first closure member 57 to open the first communication hole 51, and the combustion products enter the first combustion chamber 30 to ignite and burn the first gas generating agent. At this point, the first closure member 57 is always ruptured and opened first because the second closure member 67 is fixed from the inside of the cylindrical wall 64, and the relationship represented as "rupture pressure of the first closure member 57 < rupture pressure of the second closure member 67" is satisfied.The second closure element 67 is not opened because the combustion products then escape into the first combustion chamber 30 and the pressure in the transfer loading chamber 66 drops.

[0049] The combustion gas produced by the combustion of the first gas generating agent 31 flows through the cylindrical filter 70, breaks the sealing band and is discharged through the gas discharge openings 14 to inflate an airbag.

[0050] When the second igniter 42 is actuated, the second gas generating agent 41 is ignited and burned to generate a combustion gas. The ignitability of the second gas generating agent 41 is preferably improved because the second igniter 42 is arranged to oppose the partition wall 50, and flames and the like generated at the time of actuation are more likely to collide with the partition wall 50 and spread. The second gas generating agent 41 is ignited and successively burned from near the second igniter 42, and since the second communication holes 65 of the cylindrical guide member 60 are formed on the surface opposite a surface facing the second igniter 42, an unburned portion of the second gas generating agent 41 is ignited and burned during the process, and the combustion gas of the second gas generating agent 41 flows to the second communication holes 65.This improves the combustibility of the entire second gas generating agent 41 within the second combustion chamber 40.

[0051] When the second communication holes 65 are opened by breaking the second closure member 67, the combustion gas within the second combustion chamber 40 enters the transfer charging chamber 66, passes through the first communication hole 51 and flows into the first combustion chamber 30, passes through the cylindrical filter 70 and is discharged through the gas discharge openings 14 to further inflate the airbag.

[0052] In the gas generator according to the present invention, no means are provided in the partition wall 50 that enable direct communication between the first combustion chamber 30 and the second combustion chamber 40. Therefore, the combustion gas of the second gas generating means 41 always flows through the second communication holes 65. Therefore, since the pressure of the second combustion chamber 40 always increases at the time of actuation, the second closure element 67 is broken with good reproducibility.

[0053] Particularly, in the structure in which the combustion gas of the second gas generating agent 41 always flows through the second communication holes 65, when the first igniter 32 and the second igniter 42 are simultaneously actuated, even if a failure occurs in the first igniter 32, at least the second igniter 42 is actuated, and it is possible to achieve approximately the same performance as when both igniters 32 and 42 are simultaneously actuated. This is because, in particular, the combustion gas of the second gas generating agent 41 ignites the transfer charge in the transfer charge chamber 66 and the first gas generating agent 31 in the first combustion chamber 30, thus realizing a combustion state similar to that in which both igniters 32 and 42 are simultaneously actuated.

[0054] When the second closure element 67, as in (a) of the Fig. 4, is formed during the combustion of the second gas generating agent, the second closure element 67 is formed at the cut 68, as shown in (b) of the Fig. 4, and the portion 67a bends inward to open the second communication holes 65.

[0055] In this way, a fracture pressure difference between the first closure element 57 and the second closure element 67 reliably prevents a malfunction caused by the combustion products, such as combustion gas, of the first gas generating agent 31 flowing into the second combustion chamber 40.

[0056] A gas generator according to another embodiment of the present invention will be described with reference to Fig. 5 described.

[0057] One in Fig. 5 is the same as the gas generator 1A shown in Fig. 1, except that a positional relationship between a first communication hole 151 of a partition wall 150 and the second end opening side 162 of a cylindrical guide member 160 is different. The same numerals as in Fig. 1 represent the same parts as those in Fig. 1.

[0058] An interior of the housing 10 is divided by the radially arranged partition wall 150 into the first combustion chamber 30 on the side of the cover plate 12 and the second combustion chamber 40 on the side of the base plate 22. A first gas-generating agent 31 is housed in the first combustion chamber 30, and a second gas-generating agent 41 is housed in the second combustion chamber 40.

[0059] The partition wall 150 has a first communication hole 151 arranged eccentrically to the central axis X of the casing 10 toward the peripheral wall (the upper peripheral wall 13 and the lower peripheral wall 23), and the first communication hole is a single through hole. The partition wall 150 has a flat surface 152, an outer annular wall 153 extending from an outer peripheral edge portion of the flat surface 152 toward the cover plate 12, and an outer annular surface 154 protruding radially outward from the outer annular wall 153. Furthermore, the partition wall 150 has an inner annular wall 155 extending from the flat surface 152 toward the cover plate 12 along the cylindrical guide member 160 arranged in the second combustion chamber 40. In the partition wall 150, the outer ring surface 154 lies on the ring-shaped stepped surface 24 (see Fig. 2) and the inner annular wall 155 abuts a cylindrical wall 164 of the cylindrical guide element 160 on the side of the second end opening 162.

[0060] The cylindrical guide member 160 is arranged between the first igniter 32 and the first communication hole 151 of the partition wall 150 so as to enclose the first igniter 32. A first end opening 161 of the cylindrical guide member 160 abuts the base plate 22, and the second end opening side 162 passes through the first communication hole 151 of the partition wall 150 and is arranged so that the second end opening 162 is located within the first combustion chamber 30. An annular surface 163 is formed on the second end opening 162 and projects radially inward. A plurality of second communication holes 165 are formed in the cylindrical guide member 160 in the cylindrical wall 164 facing the second combustion chamber 40. The plurality of second communication holes 165 may be formed at regular intervals in the circumferential direction in the cylindrical wall 164, but, as shown in Fig. 5 (and also in Fig. 3), the plurality of second communication holes 65 are preferably formed only on a surface radially opposite a surface of the cylindrical wall 164 facing the second igniter 42. An interior of the cylindrical guide member 160 is a receiving space for the first igniter 32, and when a transfer charge is housed therein, a remaining space excluding the first igniter 32 is a transfer charge chamber 166.

[0061] In the Fig. In the embodiment shown in Figure 5, the second end opening 162 is closed by a first closure member 167 formed of a metallic adhesive tape applied from the inside to the annular surface 163 of the cylindrical guide member 160, and the interior of the cylindrical guide member 160 is sealed before actuation by the first combustion chamber 30. A diameter of the second end opening 162 is larger than an opening diameter of each of the second communication holes 165. The plurality of second communication holes 165 are closed from the inside of the cylindrical wall 164 by a second closure member 167 made of a metallic adhesive tape.

[0062] The Fig. The gas generator 1A shown in Figure 5 operates similarly to the one shown in Fig. 1 shown gas generator 1. The arrangements of the cylindrical guide elements, the second end openings and the second connecting holes in the Fig.The embodiments shown in Figures 1 to 5 are not limited to those in the above embodiments, as long as the inflow of the combustion gas from the first combustion chamber into the second combustion chamber is prevented by utilizing a fracture pressure difference between the closure elements.

Claims

[1] Gas generator (1) for an airbag device, comprising: a housing (10) with a cover plate (12), a base plate (22) axially opposite the cover plate (12) and a peripheral wall (13) arranged between the cover plate (12) and the base plate (22) and provided with a gas discharge opening (14); a partition wall (50) provided with a first communication hole (51) including a single through-hole (51), the partition wall (50) being arranged radially in the housing (10) to divide an interior of the housing (10) into a first combustion chamber (30) on a side of the top plate (12) accommodating a first gas generating agent (31) and a second combustion chamber (40) on a side of the bottom plate (22) accommodating a second gas generating agent (41); a first igniter (32) for burning the first gas generating agent (31) and a second igniter (42) for burning the second gas generating agent (41), the first and second igniters (32, 42) being attached to the base plate (22); characterized by , that the gas generator (1) further comprises a cylindrical guide element (60) arranged between the first igniter (32) and the first connection hole (51) of the partition wall (50) and provided with a second connection hole (65) in a cylindrical wall (64) thereof, wherein the cylindrical guide member (60) is arranged to enclose the first igniter (32) so that a first end opening (61) thereof is arranged on the side of the bottom plate (22) and a second end opening (62) thereof is connected to the first communication hole (51) of the partition wall (50), the second end opening (62) or the first communication hole (51) is closed by a first closure element (57), wherein the second end opening (62) or the first communication hole (51) is adjacent to the first combustion chamber (30), wherein the second communication hole (65) is closed by a second closure element (67), wherein the second communication hole (65) is adjacent to the second combustion chamber (40), and a breaking pressure of the first closure element (57) is set lower than a breaking pressure of the second closure element (67). [2] Gas generator (1A) for an airbag device, comprising: a housing (10) with a cover plate (12), a base plate (22) axially opposite the cover plate (12) and a peripheral wall (13) arranged between the cover plate (12) and the base plate (22) and provided with a gas discharge opening (14); a partition wall (150) provided with a first communication hole (151) including a single through-hole (151), the partition wall (150) being arranged radially in the housing (10) to divide an interior of the housing (10) into a first combustion chamber (30) on a side of the top plate (12) accommodating a first gas generating agent (31) and a second combustion chamber (40) on a side of the bottom plate (22) accommodating a second gas generating agent (41); a first igniter (32) for burning the first gas generating agent (31) and a second igniter (42) for burning the second gas generating agent (41), the first and second igniters (32, 42) being attached to the base plate (22); characterized by , that the gas generator (1A) further comprises a cylindrical guide element (160) arranged between the first igniter (32) and the first connection hole (151) of the partition wall (150) and provided with a second connection hole (165) in a cylindrical wall (164) thereof, wherein the cylindrical guide member (160) is arranged to enclose the first igniter (32) such that a first end opening (161) thereof is arranged on the side of the bottom plate (22) and a second end opening side (162) thereof enters the first communication hole (151) and faces an interior of the first combustion chamber (30), wherein the second end opening (162) is closed by a first closure element (157), wherein the second end opening (162) is adjacent to the first combustion chamber (30), wherein the second communication hole (165) is closed by a second closure element (167), wherein the second communication hole (165) is adjacent to the second combustion chamber (40), and wherein a breaking pressure of the first closure element (157) is set lower than a breaking pressure of the second closure element (167). [3] Gas generator (1, 1A) according to claim 1 or 2, wherein the second communication hole (65, 165) of the cylindrical guide member (60, 160) is formed only on one side of the cylindrical wall (64, 164), opposite to a side facing the second igniter (42). [4] The gas generator (1, 1A) according to any one of claims 1 to 3, wherein the first closure member (57, 157) and the second closure member (67, 167) are made of a same material and have a same thickness, and the second communication hole (65, 165) is formed in plurality, and a hole diameter of each of the second communication holes (65, 165) is smaller than a hole diameter of the second end opening (62, 162). [5] Gas generator (1, 1A) according to one of claims 1 to 4, wherein, when the breaking pressure of the second closure element (67, 167) is 1, the breaking pressure of the first closure element (57, 157) is not more than 0.

90. [6] Gas generator (1, 1A) according to one of claims 1 to 5, wherein the second end opening (62, 162) of the cylindrical guide member (60, 160) has an inwardly projecting annular surface, the first closure member (57, 157) is arranged on the annular surface from the inside and closes the second end opening (62, 162), and the second closure member (67, 167) is arranged on the cylindrical wall (64, 164) of the cylindrical guide member (60, 160) from the inside and closes the second communication hole (65, 165). [7] The gas generator (1, 1A) according to claim 1 or 2, wherein the second communication hole (65, 165) includes a plurality of second communication holes (65, 165), and an inverted U-shaped cut or slit (68) is formed in a region including the plurality of second communication holes (65, 165) therein.

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