Gas generator

Abstract

Gas generator for an occupant restraint system, which includes: a housing (10) that a cover plate (12); a base plate (22); and a peripheral wall (13, 23) contains, the base plate (22) is located at a position axially opposite the top plate (12), and the peripheral wall (13) contains a gas outlet opening (14) and is located between the top plate (12) and the base plate (22), where The interior of the housing (10) is divided into a first combustion chamber (30) and a second combustion chamber (40) by a partition (50) arranged to divide the interior of the housing (10) axially and radially. The first combustion chamber (30) is designed to accommodate a first gas-generating means (31) and is located on the top plate (12) side, and the second combustion chamber (40) is designed to accommodate a second gas-generating means (41) and is located on the bottom plate (22) side. a first igniter (32) and a second igniter (42) arranged on the base plate (22), the first igniter (32) is configured to ignite and burn the first gas-generating agent (31), and the second igniter (42) is configured to ignite and burn the second gas-generating agent (41), The partition (50) comprises a cylindrical section (51) and an annular section (55). The cylindrical section (51) is formed to enclose the first igniter (32) and contains a communication hole (54) for communication between the first combustion chamber (30) and the second combustion chamber (40). The annular section (55) is formed to extend radially outwards from a second opening (51b) on the cover plate (12) side of the cylindrical section (51). a first opening (51a) of the cylindrical section (51), which is opposite the second opening (51b), is in contact with the first detonator (32), and an outer periphery of the annular section (55) is in contact with the peripheral wall (13) of the housing (10), and This separates the first combustion chamber (30) and the second combustion chamber (40) from each other; characterized by the fact that the cylindrical section (51) and the ring-shaped section (55) are formed integrally.

Description

Technical area

[0001] The present invention relates to a gas generator used in an occupant restraint system such as an airbag. background

[0002] A gas generator for an occupant restraint system according to the preamble of patent claim 1 is already known from DE 11 2017 005 654 T5. Another gas generator is known from US 2004 / 0 061 319 A1.

[0003] A dual pyrogas generator, which includes an upper combustion chamber and a lower combustion chamber separated by a partition, is known as a type of gas generator that includes two igniters and two combustion chambers.

[0004] A gas generator that is Fig. 1 of US 6,199,906 B1 includes an interior space separated by a combination of three partition walls consisting of a partition plate 5, a primary combustion chamber reinforcement tube 12, and a secondary combustion chamber reinforcement tube 13 into two combustion chambers, which are a primary combustion chamber 1 and a secondary combustion chamber 2. As a result, the gas generator requires a larger number of components, and thus the number of manufacturing steps is increased. Summary of the invention

[0005] It is an object of the present invention to provide a gas generator for an occupant restraint system in which it is easier to prevent combustion gas leakage from the first combustion chamber and the second combustion chamber.

[0006] This object is achieved by the gas generator for an occupant restraint system according to patent claim 1.

[0007] The present invention provides a gas generator for an occupant restraint system, including a housing having a top plate; a bottom plate; and a peripheral wall. The bottom plate is located at a position axially opposite to the top plate, and the peripheral wall includes a gas discharge port and is located between the top plate and the bottom plate. In the gas generator, an interior space of the housing is separated into a first combustion chamber and a second combustion chamber by a partition wall arranged to axially and radially divide the interior space of the housing. The first combustion chamber is formed to accommodate a first gas generating agent and is provided on the top plate side, and the second combustion chamber is formed to accommodate a second gas generating agent and is provided on the bottom plate side.A first igniter and a second igniter are arranged on the bottom plate. The first igniter is configured to ignite and combust the first gas generating agent, and the second igniter is configured to ignite and combust the second gas generating agent. The partition wall includes a cylindrical portion and an annular portion. The cylindrical portion is formed to enclose the first igniter and includes a communication hole for communicating the first combustion chamber with the second combustion chamber. The annular portion is formed to extend radially outward from a second opening on the top plate side of the cylindrical portion.A first opening of the cylindrical portion, opposite the second opening, contacts the first igniter, and an outer periphery of the annular portion contacts the peripheral wall of the housing, thereby separating the first combustion chamber and the second combustion chamber from each other. The cylindrical portion and the annular portion are integrally formed. Short description of the drawings

[0008] The present invention will become more fully understood from the following detailed description and the accompanying drawings. However, the detailed description and drawings are for illustrative purposes only and are not intended to limit the present invention. Fig. 1 is a cross-sectional view in an X-axis direction of a gas generator according to the present invention. Fig. 2 is a cross-sectional view of only one housing shown in Fig. 1, in which a detonator is also illustrated. Fig. 3 is a cross-sectional view of a partition wall shown in Fig. 1 is illustrated. Fig. 4 is a partially enlarged cross-sectional view of the housing shown in Fig. 1 is illustrated. Description of the embodiments

[0009] The present invention provides a gas generator that has a simple structure and can be easily assembled.

[0010] In the gas generator according to an embodiment of the present invention, an interior space of a housing is vertically divided by a single partition wall into two chambers, which are an upper chamber and a lower chamber, in a state where a bottom plate of the housing is placed on a lower side and a top plate of the housing is placed on an upper side. The upper chamber is a first combustion chamber, and the lower chamber is a second combustion chamber.

[0011] The housing is made of metal such as iron or stainless steel.

[0012] A first gas generating agent in the first combustion chamber is ignited and burned by a first igniter, and the second gas generating agent in the second combustion chamber is ignited and burned by a second igniter. Any known igniter, such as an igniter in which an igniter body containing an igniting portion is integrated with a metallic collar by a resin, can be used as the first igniter and the second igniter. The first igniter and the second igniter are respectively mounted in the holes in the bottom plate.

[0013] The partition wall is a component including a cylindrical portion and an annular portion, and is made of metal such as steel or stainless steel. Although the cylindrical portion and the annular portion are preferably integrally formed, the cylindrical portion and the annular portion prepared as separate elements but joined by welding, etc., may be used. The dimensions of the cylindrical portion and the annular portion can be adjusted accordingly, allowing the cylindrical portion and the annular portion to be press-fitted into the housing.

[0014] The cylindrical portion includes a peripheral wall, a first opening on the bottom plate side, and a second opening on the top plate side. The peripheral wall includes one or a plurality of communication holes for communicating the first combustion chamber with the second combustion chamber. The communication hole is closed from the inside by a closing member such as a metallic sealing band. Therefore, when a load or pressure is applied from the inside of the cylindrical portion, it is possible to obtain a greater burst pressure on the closing member than when the closing member is fixed from the outside.

[0015] The annular portion has a shape extending radially outward from the second opening of the cylindrical portion and includes a flat surface, a curved surface, or a stepped surface, or a combination of a flat surface, a curved surface, and a stepped surface.

[0016] The cylindrical portion extends axially to enclose the first igniter, thus separating the first igniter from the second combustion chamber. The annular portion extends radially, thus vertically separating the first combustion chamber from the second combustion chamber within the housing.

[0017] The second opening of the cylindrical portion faces the inside of the first combustion chamber, and the first igniter is in contact with the first gas generating agent. However, alternatively, a transfer charge contained in a bag-shaped container or the like may be disposed between the first igniter and the first gas generating agent.

[0018] When the first igniter is actuated and a combustion product such as a flame is generated, the first gas generating agent in the first combustion chamber is ignited and burned, and thus combustion gas is generated and discharged from a gas outlet port. At this time, the actuation of the first igniter does not trigger the ignition of the second gas generating agent in the second combustion chamber. This is because the first combustion chamber and the second combustion chamber are separated by the partition wall, and the communication hole of the cylindrical portion remains closed by the closure member.

[0019] When the second igniter is activated and a combustion product, such as a flame, is generated, the second gas generating agent in the second combustion chamber is ignited and combusted, thus generating combustion gas. The combustion gas generated in the second combustion chamber breaks the closure member at the communication hole formed in the cylindrical portion of the partition wall and flows into the cylindrical portion of the partition wall. The combustion gas then flows through the first combustion chamber and is discharged from the gas outlet port.

[0020] The gas generator according to an embodiment of the present invention can be easily assembled because the first combustion chamber and the second combustion chamber are separated by the partition wall having a structure in which the cylindrical portion and the annular portion are integrated.

[0021] In addition, with the first combustion chamber and the second combustion chamber separated by a partition wall, intercomponent contact occurs only between the partition wall and the housing, and there is no contact between multiple components, unlike the gas generator disclosed in US Pat. No. 6,199,906 B1. As a result, it becomes easier to prevent combustion gas leakage from the first combustion chamber and the second combustion chamber. For example, the cylindrical portion and the annular portion can be integrally formed by pressing a plate material.

[0022] Furthermore, since the cylindrical portion and the annular portion are integrated, the pressure upon actuation is applied to the entirety of the partition wall. Thus, the partition wall is unlikely to be deformed and also unlikely to be partially destroyed, and as a result, it becomes easier to prevent combustion gas leakage from the first combustion chamber into the second combustion chamber. In addition, the annular portion functions as a reinforcing means for suppressing deformation of the second opening of the cylindrical portion. Furthermore, when the internal pressure of the first combustion chamber is increased by the combustion gas from the first gas generating means, the cylindrical portion and the annular portion are pressed toward the bottom plate as a unified body.Thus, the first opening of the cylindrical portion comes into close contact with the bottom plate of the casing and, as a result, it is possible to prevent accidental operation caused by leakage of the combustion gas from the first combustion chamber to the second combustion chamber.

[0023] In a preferable aspect of the gas generator according to the present invention, the first igniter is offset from a central axis of the housing, the cylindrical portion of the partition wall includes an annular inner projection projecting radially inward from the first opening, the annular portion of the partition wall includes an annular flat surface portion, an annular inclined surface portion, an annular wall surface portion, and a flange, the annular flat portion is formed to extend outward from the second opening of the cylindrical portion, the annular inclined surface portion is formed to extend from the annular flat surface portion and is inclined toward the cover plate, the annular wall surface portion is formed to extend from the annular inclined surface portion in a direction along the peripheral wall,and the flange is formed at an opening at one end on the cover plate side of the annular wall surface portion, and the annular inner projection is in contact with the first igniter and the bottom plate, and at least the flange is in contact with the peripheral wall of the housing, and thereby the first combustion chamber and the second combustion chamber are separated from each other.

[0024] The first igniter is offset from the central axis of the housing, the annular inner projection of the cylindrical portion of the partition wall is in contact with the first igniter (metallic collar of the first igniter) and the bottom plate, and the annular portion of the partition wall extends radially outward, separating the first combustion chamber and the second combustion chamber from each other.

[0025] Since the partition wall includes the annular inner protrusion and the annular inclined surface portion, when the internal pressure of the first combustion chamber increases, the annular inner protrusion, the annular flat surface portion of the annular portion, and the annular inclined surface portion of the annular portion are pressed toward the bottom plate as a unified body. Thus, the contact area with respect to the bottom plate and the peripheral wall of the casing increases, and this increases the contact with the bottom plate and the peripheral wall of the casing. As a result, it is possible to prevent accidental operation caused by a leak of combustion gas from the first combustion chamber to the second combustion chamber.

[0026] Additionally, since the first igniter is offset from the center axis of the housing and the first igniter contacts the annular inner protrusion and passes through the first opening, the partition wall can be prevented from rotating after being mounted in the housing, and the fastening strength can be improved. The annular inner protrusion is continuously formed 360° along the entire inner circumference of the first opening of the cylindrical portion. The flange is also continuously formed 360° along the entire circumference.

[0027] In a preferable aspect of the gas generator according to the present invention, the annular flat surface portion includes a protruding portion protruding toward the cover plate at a position axially facing an ignition portion of the second igniter, and a recessed portion corresponding to the protruding portion, and the second igniter is arranged such that the ignition portion axially faces the recessed portion.

[0028] The protruding portion and the recessed portion, which have a shape corresponding to the protruding portion, each have a curved surface, such as a hemispherical surface. The protruding portion is formed on the first combustion chamber side of the annular flat surface portion, and the recessed portion is formed at a position corresponding to the protruding portion on the second combustion chamber side of the annular flat surface portion. The recessed portion is preferably a curved surface because, in the second combustion chamber, the curved surface facilitates the diffusion of the combustion product, such as flames, generated by the actuation of the second igniter.

[0029] As described above, when the first igniter is actuated and the first gas generating agent is ignited and burned to generate combustion gas, the increased internal pressure of the first combustion chamber generates force applied in both axial directions (both the top plate direction and the bottom plate direction), pushing the annular flat surface portion and the annular inclined surface portion of the annular portion toward the bottom plate. At this time, even if the annular flat surface portion is deformed and protrudes toward the bottom plate, the recessed portion prevents the annular flat surface portion from contacting the ignition portion of the second igniter. As a result, the deformation of the annular flat surface portion does not affect the pitch of the ignition portion of the second igniter.

[0030] In a preferable aspect of the gas generator according to the present invention, the housing is formed by a combination of a diffuser shell and a closure shell. The diffuser shell includes the cover plate, a first peripheral wall containing the gas outlet opening, and a first opening opposite the cover plate. The first peripheral wall includes an annular surface portion positioned between the gas outlet opening and the first opening and defined by a difference (d2 > d1) between an inner diameter (d1) of a portion in which the gas outlet opening is formed and an inner diameter (d2) of a portion leading to the first opening. The closure shell includes the bottom plate, a second peripheral wall, and a second opening opposite the bottom plate. The second peripheral wall of the closure shell is fitted into the first peripheral wall of the diffuser shell.and the annular wall surface portion of the annular portion of the partition wall is in contact with the second peripheral wall of the closure shell, and the flange of the annular portion of the partition wall is sandwiched between an annular end surface of the second opening of the closure shell and the annular surface portion of the diffuser shell.

[0031] The housing is formed by combining the diffuser shell and the closure shell, and the second peripheral wall of the closure shell is fitted into the first peripheral wall of the diffuser shell. The diffuser shell and the closure shell are welded together at a portion where the diffuser shell contacts the closure shell.

[0032] Since the second peripheral wall of the closure shell is fitted into the first peripheral wall of the diffuser shell, the annular end surface of the second opening of the closure shell is positioned inside the housing. As a result, the flange of the partition wall is in contact with the annular end surface. In addition, the flange of the partition wall is sandwiched between the annular end surface of the second opening and the annular surface portion of the diffuser shell, and the annular wall surface portion of the partition wall is in contact with the second peripheral wall of the closure shell, thus fixing the partition wall and preventing it from moving axially and radially. As a result, when the pressure is applied to the partition wall during actuation, the partition wall is in a securely fixed state, and the close contact between the partition wall and the housing is maintained.

[0033] In a preferable aspect of the gas generator according to the present invention, a cylindrical filter is further included, a first end surface of the cylindrical filter is in contact with the cover plate, a second end surface of the cylindrical filter is in contact with the annular inclined surface portion of the annular portion of the partition wall, and a portion of an outer peripheral surface of the cylindrical filter is in contact with an annular wall surface portion, and the cylindrical filter is arranged such that a gap is formed between the portion of the outer peripheral surface and the gas discharge port formed in the peripheral wall.

[0034] Since the second end surface of the cylindrical filter is in contact with the annular inclined surface, the height of which increases radially outward, movement of the cylindrical filter is prevented even when the increased pressure inside the first combustion chamber generates a force applied radially outward to the cylindrical filter upon actuation. This maintains the gap between the cylindrical filter and the gas discharge port in the peripheral wall of the housing, and the combustion gas is discharged smoothly, which is preferable.

[0035] The gas generator according to the present invention can be easily assembled due to a structure in which the first combustion chamber on the top plate side of the housing and the second combustion chamber on the bottom plate side of the housing are separated by a single partition wall arranged to radially and axially divide the interior space of the housing. Furthermore, deformation of the partition wall can be suppressed.

[0036] The gas generator according to the present invention can be used for an airbag device mounted in an automobile.

[0037] An embodiment of a gas generator according to the present invention will be described with reference to the Fig. 1 to 4 described.

[0038] A gas generator 1 includes a housing 10 provided with a diffuser shell 11 and a closure shell 21. Both the diffuser shell 11 and the closure shell 21 are made of iron, stainless steel, or the like.

[0039] The diffuser shell 11 includes a cover plate 12, a first peripheral wall 13, and a first opening 11a. The first peripheral wall 13 includes a plurality of gas outlet openings 14 arranged at circumferentially equal intervals. The first peripheral wall 13 includes a flange 15 at the first opening 11a.

[0040] The first peripheral wall 13 includes an annular surface portion 16 positioned between the gas outlet openings 14 and the first opening 11a. The annular surface portion 16 is formed with a difference (d2 > d1) between the inner diameter (d1) of a portion in which the gas outlet openings 14 are formed and the inner diameter (d2) of a portion leading to the first opening 11a.

[0041] The plurality of gas outlet openings 14 are closed from the inside by a metallic sealing strip.

[0042] The closure shell 21 has a bottom plate 22, a second peripheral wall 23, and a second opening 21a.

[0043] Two holes spaced apart from each other are formed in the bottom plate 22 and a first igniter 32 is attached to one of the two holes and a second igniter 42 is attached to the other of the two holes.

[0044] The first igniter 32 is arranged at a position closer to a central axis X of the housing 10, but offset from the central axis X. The second igniter 42 is positioned farther away from the central axis X of the housing 10 than the first igniter 32.

[0045] In the embodiment shown in Fig. 1, the first igniter 32 is arranged in such a way that the central axis of the first igniter 32 is offset by a distance equal to 20 to 30% of the distance from the central axis X to the second peripheral wall 23. In addition, in the embodiment shown in Fig. 1, the second igniter 42 is arranged in such a manner that the central axis of the second igniter 42 is offset by a distance equal to 40 to 60% of the distance from the central axis X to the second peripheral wall 23.

[0046] In the housing 10, a portion of the inner surface of the first peripheral wall 13 of the diffuser shell 11, which is near the first opening 11a, contacts a portion of the outer surface of the second peripheral wall 23 of the closure shell 21, which is near the second opening 21a, and these portions are fixed to each other by welding. Because in the housing 10, the closure shell 21 is inserted into the diffuser shell 11, an annular end surface 24 of the second peripheral wall 23 faces the interior of the housing 10, as shown in FIGS. Fig. 1 and Fig. 4 shown.

[0047] At the portion where the diffuser shell 11 is connected to the closure shell 21, an annular groove 18 is provided, which is formed by the annular surface portion 16, the annular end surface 24 and the first peripheral wall 13.

[0048] The partition wall 50 extends in an axial direction and a radial direction, and separates the interior of the housing 10 into a first combustion chamber 30 on the cover plate 12 side and a second combustion chamber 40 on the bottom plate 22 side.

[0049] The first combustion chamber 30 accommodates a first gas generating agent 31 that is in contact with an ignition portion of the first igniter 32, and the second combustion chamber 40 accommodates a second gas generating agent 41 that is in contact with the second igniter 42. The ignition portion is a portion for accommodating an ignition charge. Upon actuation, a combustion product such as a hot gas or a flame is generated in the ignition portion. The second gas generating agent 41 is filled in a state where it is in contact with the ignition portion.

[0050] In the first combustion chamber 30, a transfer charge contained in a bag-shaped container may be arranged between the first igniter 32 and the first gas generating agent 31, as needed. The bag-shaped container used is a container that can be easily melted, torn, or broken by actuation of the first igniter or combustion of the transfer charge.

[0051] The partition wall 50 is made of metal such as stainless steel or iron. Fig. 1 and Fig. 3 illustrate an integrally formed partition wall 50. The partition wall 50 includes a cylindrical portion 51 and an annular portion 55.

[0052] The cylindrical portion 51 includes a peripheral wall 52, a first opening 51a on the bottom plate 22 side, a second opening 51b on the opposite side to the first opening 51a in an X-axis direction, and an annular inner projection 53 which is on the first opening 51a side and projects radially inward.

[0053] In the peripheral wall 52, a communication hole 54 for allowing the first combustion chamber 30 and the second combustion chamber 40 to communicate with each other after actuation is formed, and the communication hole is closed from the inside by a metallic sealing band serving as a closing member.

[0054] The annular inner projection 53 of the cylindrical portion 51 is in contact with the bottom plate 22, and an annular inner end surface 53a at the edge of the annular inner projection 53 is in contact with a metallic collar of the first igniter 32.

[0055] The annular portion 55 includes an annular flat surface portion 56 radially extending to the outside from the second opening 51b of the cylindrical portion 51, similar to the bottom plate 22, an annular inclined surface portion 57 extending from the annular flat surface portion 56 and inclined toward the top plate 12, an annular surface portion 58 formed to extend from the annular inclined surface portion 57 in a direction along the peripheral wall (the first peripheral wall 13 and the second peripheral wall 23), and a flange 59 formed at an opening of the annular wall surface portion 58.

[0056] Regarding the annular portion 55, the annular wall surface portion 58 is in contact with the second peripheral wall 23 of the closure shell 21, and the flange 59 is clamped in the annular groove 18 in a state between the annular end surface 24 and the annular surface portion 16.

[0057] In the interior of the housing 10, the first combustion chamber 30 is separated from the second combustion chamber 40 by the cylindrical portion 51 of the partition wall 50 extending in the X-axis direction and by the annular portion 55 of the partition wall 50 extending in the radial direction.

[0058] The annular flat surface portion 56 of the partition wall 50 may include a protruding portion extending toward the cover plate 12 at a position axially facing the ignition portion of the second igniter 42, and a recessed portion corresponding to the protruding portion. When the recessed portion is provided, the ignition portion of the second igniter 42 is arranged in a manner to oppose the recessed portion in the X-axis direction.

[0059] The inner diameter of the annular inner portion 53 (the annular inner end surface 53a) of the cylindrical portion 51, the outer diameter of the metallic collar of the first igniter 32, the outer diameter of the annular portion 55, an inner diameter of the casing 10, and a height of the partition wall 50, etc. are adjusted, and thus the partition wall 50 is fixed by press fitting.

[0060] In the embodiment shown in Fig. 1, a cylindrical filter 20 is arranged.

[0061] The cylindrical filter 70 has a first end surface 72 in contact with the cover plate 12, a second end surface 71 in contact with the annular inclined portion 57, and an outer peripheral surface 73, the lower portion (a portion on the bottom plate 22 side) of which is in contact with the annular wall surface portion 58. A cylindrical gap is formed between the cylindrical filter 70 and the first peripheral wall 13 containing the gas outlet openings 14.

[0062] In the embodiment shown in Fig. 1, the cover plate 12, which is opposite to the annular angled surface portion 57 in the X-axis direction, also has an inclined surface having a similar shape to the annular inclined surface portion 57. However, the cover plate 12 may have a flat shape.

[0063] Next, an embodiment of a method for assembling the gas generator 1 will be described.

[0064] The first detonator 32 is attached to one of the two holes in the bottom plate 22 of the closure shell 21 and the second detonator 42 is attached to the other of the two holes.

[0065] Next, the second gas generating agent 41 is placed in the second combustion chamber 40.

[0066] Next, the partition wall 50 is press-fitted, with the annular inner projection 53 of the cylindrical portion 51 being made to come into contact with the bottom plate 22, the annular inner end surface 53a being made to come into contact with the metallic collar of the first igniter 32, the annular wall surface portion 58 being made to come into contact with the second peripheral wall 23 of the closure shell 21, and the flange 59 being made to come into contact with the annular end surface 24.

[0067] Next, the cylindrical filter 70 is arranged, and then the first gas generating agent 31 is placed in the first combustion chamber 30.

[0068] Then, the diffuser shell 11 is fitted onto the outer side of the closure shell 21. At this time, the flange 59 of the partition wall 50 is placed within the annular groove 18 in a state where it is clamped between the annular end surface 24 and the annular surface portion 16.

[0069] Next, the section where the diffuser shell 11 contacts the closure shell 21 is welded.

[0070] Operation of an airbag device provided with a gas generator 1, such as in Fig. 1, is described.

[0071] The gas generator 1 according to the embodiment of the present invention is particularly effective in a case where the first igniter 32 is actuated first and then the second igniter 42 is actuated, or in a case where only the first igniter 32 is actuated. The following example describes the case where the first igniter 32 is actuated first and then the second igniter 42 is actuated.

[0072] When the first igniter 32 is first actuated, the first gas generating agent 31 is ignited and burned in the first combustion chamber 30 by flames etc. generated by the first igniter 32, and as a result, combustion gas is generated.

[0073] The combustion gas passes through the cylindrical filter 70 and then breaks the sealing band. As a result, the combustion gas is discharged from the gas outlet ports 14 to inflate the airbag.

[0074] When the pressure inside the first combustion chamber 30 increases due to the combustion gas, the annular inner portion 53 of the partition wall 50 is pressed against the bottom plate 22, the annular wall surface portion 58 is pressed against the second peripheral wall 23 of the closure shell 21, and the flange 59 in the annular groove 18 is pressed against the first peripheral wall 13. The communication hole 54 is closed from the inside of the peripheral wall 52 by the metallic sealing band, which withstands high burst pressure and does not break, and thus the combustion gas does not escape from the first combustion chamber 30 into the second combustion chamber 40.

[0075] With the partition wall 50 receiving the pressure upon actuation in its entirety, and in particular the annular projection 53 formed in the first opening 51a and the annular portion 55 formed in the second opening 51b, the partition wall is unlikely to be deformed in its entirety and unlikely to be partially destroyed. As a result, the combustion gas is further prevented from escaping from the first combustion chamber 30 to the second combustion chamber 40.

[0076] After a slight delay, the second igniter 42 is actuated, and the second gas generating agent 41 in the second combustion chamber 40 is ignited and burned, generating a combustion gas.

[0077] The second igniter 42 is preferably arranged in a state where the second igniter faces the partition wall 50 (the annular flat surface portion 56 of the annular portion 55). This is because when the second igniter 42 is actuated, flames, etc., resulting therefrom collide with the partition wall 50, and thus, diffusion of the flames, etc., is facilitated, improving the ignitability of the second gas generating agent 41. This arrangement is particularly preferable in an embodiment in which the recessed portion is formed in the annular flat surface portion 56 of the partition wall 50, thus forming a gap between the ignition portion of the second igniter 42 and the partition wall 50, because the effect described above appears prominent, and the partition wall does not interfere with the bursting resulting from the ignition of the second igniter 42.

[0078] The combustion gas generated in the second combustion chamber 40 enters the first combustion chamber 30 through the communication hole 54 of the cylindrical portion 51. Then, after passing through the cylindrical filter 70, the combustion gas is discharged from the gas outlet ports 14 and inflates the airbag. The pressure from the second combustion chamber 40 side easily peels off the metal sealing tape covering the communication hole 54 from the peripheral wall 52.

[0079] The scope of protection is defined only by the patent claims.

Claims

[1] Gas generator for an occupant restraint system, comprising: a housing (10) that a cover plate (12); a base plate (22); and contains a peripheral wall (13, 23), the base plate (22) is located at a position axially opposite the cover plate (12), and the peripheral wall (13) contains a gas outlet opening (14) and is located between the cover plate (12) and the base plate (22), where an interior of the housing (10) is divided into a first combustion chamber (30) and a second combustion chamber (40) by a partition wall (50) arranged to axially and radially divide the interior of the housing (10), the first combustion chamber (30) is formed to accommodate a first gas generating agent (31) and is provided on the cover plate (12) side, and the second combustion chamber (40) is formed to accommodate a second gas generating agent (41) and is provided on the bottom plate (22) side, a first igniter (32) and a second igniter (42) arranged on the base plate (22), the first igniter (32) is configured to ignite and burn the first gas generating agent (31), and the second igniter (42) is configured to ignite and burn the second gas generating agent (41), the partition wall (50) comprises a cylindrical portion (51) and an annular portion (55), the cylindrical portion (51) is formed to enclose the first igniter (32) and contains a communication hole (54) for communicating the first combustion chamber (30) with the second combustion chamber (40), and the annular portion (55) is formed to extend radially outward from a second opening (51b) on the cover plate (12) side of the cylindrical portion (51), and a first opening (51a) of the cylindrical portion (51), which is opposite to the second opening (51b), is in contact with the first igniter (32), and an outer periphery of the annular portion (55) is in contact with the peripheral wall (13) of the housing (10), and thereby the first combustion chamber (30) and the second combustion chamber (40) are separated from each other; characterized by , that the cylindrical portion (51) and the annular portion (55) are integrally formed. [2] The gas generator according to claim 1, wherein the first igniter (32) is offset from a central axis (X) of the housing (10), the cylindrical portion (51) of the partition wall (50) includes an annular inner projection (53) projecting radially inward from its first opening (51a), the annular portion (55) of the partition wall (50) includes an annular flat surface portion (56), an annular inclined surface portion (57), an annular wall surface portion (58), and a flange (59). The annular flat surface portion (56) is formed to extend outwardly from the second opening (51b) of the cylindrical portion (51). The annular inclined surface portion (57) is formed to extend from the annular flat surface portion (56) and is inclined toward the cover plate (12). The annular wall surface portion (58) is formed to extend from the annular inclined surface portion (57) in a direction along the peripheral wall (23). The flange (59) is formed at an opening at one end on the cover plate (12) side of the annular wall surface portion (58). the annular inner projection (53) is in contact with the first igniter (32) and the bottom plate (22), and at least the flange (59) is in contact with the peripheral wall (13, 23) of the housing (10), and thereby the first combustion chamber (30) and the second combustion chamber (40) are separated from each other. [3] The gas generator according to claim 2, wherein the annular flat surface portion (56) includes a projecting portion projecting toward the cover plate (12) at a position axially facing an ignition portion of the second igniter (42), and a recessed portion corresponding to the projecting portion, and the second igniter (42) is arranged such that the ignition portion faces the recessed portion axially. [4] The gas generator according to claim 2, wherein the housing (10) is formed by a combination of a diffuser shell (11) and a closure shell (21), the diffuser shell (11), the cover plate (12), a first peripheral wall (13) containing the gas outlet opening (14), and a first opening (11a) opposite the cover plate (12), the first peripheral wall (13) containing an annular surface portion (16) positioned between the gas outlet opening (14) and the first opening (11a) and formed by a difference (d2 > d1) between an inner diameter (d1) of a portion in which the gas outlet opening (14) is formed and an inner diameter (d2) of a portion leading to the first opening (11a), the closure shell (21) contains the base plate (22), a second peripheral wall (23), and a second opening (21a) opposite the base plate (22), the second peripheral wall (23) of the closure shell (21) is fitted into the first peripheral wall (13) of the diffuser shell (11), and the annular wall surface portion (58) of the annular portion (55) of the partition wall (50) is in contact with the second peripheral wall (23) of the closure shell (21), and the flange (59) of the annular portion (55) of the partition wall (50) is clamped between an annular end surface (24) of the second opening (21a) of the closure shell (21) and the annular surface portion (16) of the diffuser shell (11). [5] The gas generator according to claim 2, further comprising a cylindrical filter (70), wherein a first end surface (72) of the cylindrical filter (70) is in contact with the cover plate (12), a second end surface (71) of the cylindrical filter (70) is in contact with the annular inclined surface portion (57) of the annular portion (55) of the partition wall (50), and a portion of an outer peripheral surface (73) of the cylindrical filter (70) is in contact with an annular wall surface portion (58), and the cylindrical filter (70) is arranged such that a gap is formed between the portion of the outer peripheral surface (73) and the gas outlet opening (14) formed in the peripheral wall (13). [6] The gas generator according to claim 1, wherein the communication hole (54) is formed in the peripheral wall of the cylindrical portion (51) and is closed from the inside by a metallic closing member.

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