Gas generator

Abstract

To provide a gas generator that has a stable output performance.SOLUTION: A gas generator has a plurality of gas discharge holes including first gas discharge holes and second gas discharge holes higher in an opening pressure than the first gas discharge holes. An enclosure wall part is sectioned, in a peripheral direction of the enclosure wall part, into a combustion product discharge region where one communication hole is arranged or a plurality of communication holes is arranged together and a combustion product non-discharge region excluding the combustion product discharge region. A peripheral wall part is sectioned, in a peripheral direction of the peripheral wall part, into a communication hole corresponding region which is caused to correspond to the combustion product discharge region and a communication hole non-corresponding region which is caused to correspond to the combustion product non-discharge region, wherein the first gas discharge holes are formed only in the communication hole corresponding region and the second gas discharge holes are formed only in the communication hole non-corresponding region.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a gas generator.

Background Art

[0002] Conventionally, an igniter and a gas generating agent are arranged inside a housing, the igniter is surrounded by an inner cylinder member, a communication hole is formed in the inner cylinder member, and by operating the igniter, the gas generating agent is burned by combustion products discharged from the communication hole, and a gas generator that discharges the combustion gas to the outside through a plurality of gas discharge holes formed in the housing has been widely used.

[0003] The output performance of a gas generator is defined by parameters such as the discharge amount and discharge time of its combustion gas. In order to make the output performance the desired performance, it is important to burn the gas generating agent as desired. Here, the combustion performance of the gas generating agent changes according to the ambient temperature and pressure during combustion. Generally, the higher the temperature or the higher the pressure, the more actively the gas generating agent reacts (burns). That is, the higher the temperature or pressure, the better the combustion performance of the gas generating agent, and the easier it is for the internal pressure of the housing during combustion to increase. On the other hand, in a low-temperature and low-pressure environment, the combustion of the gas generating agent becomes inactive. Therefore, in order to reduce the difference in the output performance of the gas generator between high-temperature and low-temperature times and achieve stabilization of the output performance, it is necessary to increase the internal pressure of the housing at low temperatures and improve the combustion performance of the gas generating agent. In connection with this, in order to suppress the decrease in the combustion performance of the gas generating agent at low temperatures, the cracking pressure of a closing member that closes some gas discharge holes is made higher than the cracking pressure of a closing member that closes other gas discharge holes, and a technique is known in which only the other gas discharge holes are opened at low temperatures to increase the internal pressure of the housing (for example, Patent Document 1).

[0004] Here, since the momentum of the combustion products discharged from the communication holes of the inner cylinder member is strong, it is considered that the gas generating agent in the housing burns preferentially starting from those near the communication holes in the circumferential direction of the inner cylinder member. Therefore, due to the arrangement of the communication holes, the combustion of the gas generating agent is likely to become non-uniform, and it is presumed that pressure and temperature spots (biases) instantaneously occur in the housing. In particular, when the inner cylinder member accommodating the ignition device is unevenly distributed with respect to the central position of the housing, the ignition environment and combustion environment of the gas generating agent differ in the circumferential direction, so there is a tendency for ignition spots to easily occur.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] In conventional gas generators, gas discharge holes were not arranged in the housing in consideration of the uneven combustion of the gas generating agent caused by the arrangement of the communication holes of the inner cylinder member as described above. Therefore, even if the cracking pressure of the closing member is made different to make some gas discharge holes more difficult to open than other gas discharge holes, there is a risk that not only the other gas discharge holes but also the some gas discharge holes will open at low temperatures. If this happens, the combustion gas in the housing is likely to escape due to the opening of the extra gas discharge holes, so the internal pressure of the housing becomes lower than expected. As a result, the combustion performance of the gas generating agent does not reach the expected level, and there is a possibility that the output performance of the gas generator cannot be stably obtained.

[0007] The technology of the present disclosure has been made in view of the above problems, and its object is to provide a gas generator with stable output performance.

Means for Solving the Problems

[0008] To solve the above problems, the technology of the present disclosure adopts the following configuration. That is, the technology of the present disclosure is a gas generator, which includes a first ignition device, a first combustion chamber in which the first ignition device is disposed, a cylindrical peripheral wall portion, a top plate portion provided at one end side of the peripheral wall portion, and a bottom plate portion provided at the other end side of the peripheral wall portion so as to face the top plate portion, and together with the peripheral wall portion and the top plate portion, defines the first combustion chamber and to which the first ignition device is fixed. A first inner cylinder member including a cylindrical surrounding wall portion surrounding the first ignition device and forming an ignition means chamber between the first ignition device and the first inner cylinder member, and a first inner cylinder member in which one or more communication holes communicating the ignition means chamber with the outside of the first inner cylinder member are formed in the surrounding wall portion. A first gas generating agent disposed in the first combustion chamber so as to surround the surrounding wall portion and combusted by combustion products discharged from the ignition means chamber through the communication holes by the operation of the first ignition device. A plurality of gas discharge holes formed in the housing and communicating the first combustion chamber with the outside of the housing by opening in response to the combustion pressure of the gas generating agent. The plurality of gas discharge holes include a first gas discharge hole and a second gas discharge hole having a higher opening pressure than the first gas discharge hole. The surrounding wall portion is divided in the circumferential direction of the surrounding wall portion into a combustion product discharge region where one of the communication holes is disposed or a plurality of the communication holes are collectively disposed, and a combustion product non-discharge region excluding the combustion product discharge region. The peripheral wall portion is divided in the circumferential direction of the peripheral wall portion into a communication hole corresponding region associated with the combustion product discharge region and a communication hole non-corresponding region associated with the combustion product non-discharge region. Among the communication hole corresponding region and the communication hole non-corresponding region, the first gas discharge hole is formed only in the communication hole corresponding region, and the second gas discharge hole is formed only in the communication hole non-corresponding region. It is a gas generator.

[0009] According to such a gas generator, by forming the first gas discharge holes only in the communication hole corresponding region associated with the combustion product discharge region, it is easier to open the first gas discharge holes with a low opening pressure, and by forming the second gas discharge holes only in the non-communication hole corresponding region, it is possible to make it more difficult to open the second gas discharge holes with a high opening pressure. Thereby, it becomes possible to surely open only the first gas discharge holes during low-temperature operation. Therefore, the internal pressure of the housing and the combustion performance of the gas generant during low-temperature operation can be surely enhanced. As a result, according to the gas generator of the present disclosure, the difference in output performance between low-temperature operation and high-temperature operation can be reduced, and stable output performance can be obtained.

[0010] Further, in the gas generator of the present disclosure, the communication hole corresponding region may be a region of the peripheral wall portion that faces the combustion product discharge region in the radial direction centered on the central axis of the surrounding wall portion.

[0011] Further, in the gas generator of the present disclosure, the range of the communication hole corresponding region may be defined by a first virtual straight line that intersects the peripheral wall portion from the central axis of the surrounding wall portion through one end portion in the circumferential direction of the surrounding wall portion of the combustion product discharge region in a view in the axial direction of the surrounding wall portion, and a second virtual straight line that intersects the peripheral wall portion from the central axis of the surrounding wall portion through the other end portion in the circumferential direction of the surrounding wall portion of the combustion product discharge region.

[0012] Further, in the gas generator of the present disclosure, the central axis of the surrounding wall portion and the central axis of the peripheral wall portion are separated from each other, and the surrounding wall portion includes a first combustion product discharge region and a second combustion product discharge region that are axially symmetric with respect to each other with a virtual center line passing through the central axis of the surrounding wall portion and the central axis of the peripheral wall portion as a symmetry axis in a view in the axial direction of the surrounding wall portion, and the peripheral wall portion includes a first communication hole corresponding region that is the communication hole corresponding region associated with the first combustion product discharge region and the communication hole corresponding region associated with the second combustion product discharge region It includes a second communication hole corresponding region, and the communication holes are formed in the first combustion product discharge region and the second combustion product discharge region so as to be symmetrically arranged with respect to the virtual center line as the axis of symmetry. The first gas discharge holes may be formed in the first communication hole corresponding region and the second communication hole corresponding region so as to be symmetrically arranged with respect to the virtual center line as the axis of symmetry.

[0013] Further, in the gas generator of the present disclosure, the opening pressure of the first gas discharge hole formed in the first communication hole corresponding region and the opening pressure of the first gas discharge hole formed in the second communication hole corresponding region may be configured to be equal to each other.

[0014] Further, the gas generator of the present disclosure further includes a second ignition device, a second gas generating agent that burns by the operation of the second ignition device, a second combustion chamber in which the second ignition device and the second gas generating agent are arranged, and a cylindrical second inner cylinder member disposed in the housing, the second inner cylinder member forming the second combustion chamber inside thereof. The second inner cylinder member may be arranged so as not to be located between the combustion product discharge region and the communication hole corresponding region in the radial direction centered on the central axis of the surrounding wall portion.

[0015] Further, in the gas generator of the present disclosure, the communication hole may be formed as a single hole extending in the circumferential direction of the surrounding wall portion across the combustion product discharge region.

Advantages of the Invention

[0016] According to the technology of the present disclosure, it is possible to provide a gas generator with stable output performance.

Brief Description of the Drawings

[0017]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Mode for Carrying Out the Invention

[0018] Hereinafter, the gas generator according to the embodiment of the present disclosure will be described with reference to the drawings. Note that each configuration and their combinations in each embodiment are examples, and within the scope not departing from the gist of the present invention, addition, omission, substitution, and other changes of the configuration can be made as appropriate. The present disclosure is not limited by the embodiments, but is limited only by the scope of the claims.

[0019] <Embodiment 1> FIG. 1 is a longitudinal sectional view of a gas generator 100 according to Embodiment 1. More specifically, FIG. 1 is a sectional view including the housing central axis indicated by reference sign A1 and the inner cylinder central axis indicated by reference sign A5. In FIG. 1, the state before the operation of the gas generator 100 is shown. The gas generator 100 is, for example, a gas generator for an airbag used in an airbag.

[0020] [Overall Configuration] As shown in FIG. 1, the gas generator 100 includes a first ignition device 4, a first inner cylinder member 5, a primer 6, a second ignition device 7, a second inner cylinder member 8, a filter 9, and a first gas generating agent 110 It includes a second gas generator 120 and a housing 1 that houses these components. The gas generator 100 is configured as a so-called dual-type gas generator equipped with two ignition devices. Also, the gas generator 100 burns the first gas generator 110 by operating the first igniter 41 provided in the first ignition device 4, and burns the second gas generator 120 by operating the second igniter 71 provided in the second ignition device 7, and is configured to discharge combustion gas, which is a combustion product of these, from a gas discharge hole 12 formed in the housing 1. Hereinafter, each component of the gas generator 100 will be described. In this specification, for convenience, the operation of the igniter included in the ignition device may be expressed as "the ignition device operates".

[0021] [Housing] The housing 1 is formed in a short cylindrical shape including a cylindrical peripheral wall portion indicated by reference numeral 11 with both axial ends of the peripheral wall portion 11 closed, by joining a metal upper shell 2 and a lower shell 3, each formed in a bottomed substantially cylindrical shape, with their open ends facing each other. The housing central axis A1 in FIG. 1 is the central axis of the peripheral wall portion 11. Here, the direction along the housing central axis A1 is defined as the vertical direction of the gas generator 100, the upper shell 2 side (i.e., the upper side in FIG. 1) is defined as the upper side of the gas generator 100, and the lower shell 3 side (i.e., the lower side in FIG. 1) is defined as the lower side of the gas generator 100.

[0022] The upper shell 2 has a cylindrical upper peripheral wall portion 21 and a top plate portion 22 that closes the upper end of the upper peripheral wall portion 21, and an internal space is formed by these. An opening of the upper shell 2 is formed by the lower end portion of the upper peripheral wall portion 21. A joint portion 23 extending radially outward is connected to the lower end portion of the upper peripheral wall portion 21. The lower shell 3 has a cylindrical lower peripheral wall portion 31 and a bottom plate portion 32 that closes the lower end of the lower peripheral wall portion 31, and an internal space is formed by these. A joint portion 33 extending radially outward is connected to the upper end portion of the lower peripheral wall portion 31. The bottom plate portion 32 is formed with a first mounting hole 32a for mounting the first ignition device 4 to the bottom plate portion 32 and a second mounting hole 32b for mounting the second ignition device 7 to the bottom plate portion 32.

[0023] The joint 23 of the upper shell 2 and the joint 33 of the lower shell 3 are overlapped and joined by laser welding or the like, thereby forming a short cylindrical housing 1 with both axial ends closed. A cylindrical peripheral wall portion 11 that connects the top plate portion 22 and the bottom plate portion 32 is formed by the upper peripheral wall portion 21 of the upper shell 2 and the lower peripheral wall portion 31 of the lower shell 3. That is, the housing 1 includes a cylindrical peripheral wall portion 11, a top plate portion 22 provided on one end side of the peripheral wall portion 11, and a bottom plate portion 32 provided on the other end side so as to face the top plate portion 22. The first combustion chamber 10 is defined by the peripheral wall portion 11, the top plate portion 22, the bottom plate portion 32, and a second inner cylinder member 8 described later. The first combustion chamber 10 is formed as a space in the internal space of the housing 1 excluding the second combustion chamber 20 which is the internal space of the second inner cylinder member 8. In the first combustion chamber 10, a first ignition device 4, a first inner cylinder member 5, a primer 6, a filter 9, and a first gas generating agent 110 are arranged. The central axis of the first combustion chamber 10 coincides with the housing central axis A1.

[0024] Here, in the housing 1, a plurality of gas discharge holes 12 that communicate the first combustion chamber 10 and the external space of the housing 1 are formed side by side along the circumferential direction. More specifically, the plurality of gas discharge holes 12 are formed in the upper peripheral wall portion 21 of the peripheral wall portion 11. The gas discharge holes 12 are closed by a sealing tape 13 provided on the inner peripheral surface of the peripheral wall portion 11 in a state before the first ignition device 4 and the second ignition device 7 operate. When this sealing tape 13, which is an example of a closing member, is cleaved by the pressure of the combustion gas, the gas discharge holes 12 open. In this specification, the pressure required to open the gas discharge holes 12 is referred to as the "opening pressure". In the case of this example, the opening pressure is the pressure required for the cleavage of the sealing tape 13.

[0025] [Ignition Device] As shown in FIG. 1, the first ignition device 4 is fixed to a first mounting hole 32a formed in the bottom plate portion 32 of the lower shell 3. The first ignition device 4 includes a first igniter 41. The second ignition device 7 is fixed to a second mounting hole 32b formed in the bottom plate portion 32 of the lower shell 3. Further, the second ignition device 7 includes a second igniter 71. The first igniter 41 and the second igniter 71 each contain an ignition charge (not shown) inside, and by operating by supplying an ignition current, the ignition charge is burned and its combustion products are released to the outside. The first ignition device 4 and the second ignition device 7 operate independently of each other. When the second ignition device 7 operates, the second ignition device 7 operates at the same time as the operation of the first ignition device 4 or at a predetermined timing after the operation of the first ignition device 4. The gas generator 100 can release a large amount of combustion gas to the outside in various output profiles by the combustion of the first gas generating agent 110 due to the operation of the first ignition device 4 and the combustion of the second gas generating agent 120 due to the operation of the second ignition device 7, as compared with a so-called single-type gas generator. Note that the second ignition device 7 does not always operate, and the gas generator 100 can operate only the first ignition device 4 without operating the second ignition device 7 when the impact sensed by a sensor (not shown) is weak, or can operate the first ignition device 4 and the second ignition device 7 simultaneously when the impact is strong.

[0026] [Inner cylinder member] The first inner cylinder member 5 is a cylindrical member extending from the bottom plate portion 32 toward the top plate portion 22. The first inner cylinder member 5 includes a cylindrical surrounding wall portion 51 and a lid wall portion 52 that closes one end of the surrounding wall portion 51. The first inner cylinder member 5 is attached to the bottom plate portion 32 by fitting or press-fitting the first ignition device 4 into the other end of the surrounding wall portion 51. The inner cylinder central axis A5 in FIG. 1 is the central axis of the surrounding wall portion 51. As shown in FIG. 1, in the gas generator 100, the first inner cylinder member 5 is arranged such that the inner cylinder central axis A5 is separated from the housing central axis A1 of the peripheral wall portion 11, and the inner cylinder central axis A5 is parallel to the housing central axis A1. As shown in FIG. 1, since the first ignition device 4 is surrounded by the surrounding wall portion 51, an ignition means chamber 53 is formed between the first inner cylinder member 5 and the first ignition device 4. The ignition means chamber 53 houses a transfer fire powder 6 that burns by the operation of the first ignition device 4. Further, a plurality of communication holes h1 that communicate the internal space (i.e., the ignition means chamber 53) and the external space are formed in the surrounding wall portion 51 of the first inner cylinder member 5. The communication holes h1 are closed by a sealing tape (not shown) in a state before the first ignition device 4 operates. Instead of using the lid wall portion, for example, the surrounding wall portion 51 with an open upper end may be joined to the top plate portion of the housing by welding or the like. Also, the communication holes h1 are arranged at a position having the same height (height from the bottom plate portion 32) as the gas discharge holes 12. However, the height of the communication holes h1 and the height of the gas discharge holes 12 may be different.

[0027] The second inner cylinder member 8 is a cylindrical member extending from the bottom plate portion 32 toward the top plate portion 22, and includes a cylindrical surrounding wall portion 81 and a lid wall portion 82 that closes one end portion of the surrounding wall portion 81. The second inner cylinder member 8 is attached to the bottom plate portion 32 by fitting or press-fitting the second ignition device 7 into the other end portion of the surrounding wall portion 81. As shown in FIG. 1, inside the second inner cylinder member 8, a second combustion chamber 20 is formed in which the second ignition device 7 and a second gas generating agent 120 that burns by the operation of the second ignition device 7 are arranged. Further, a plurality of communication holes h2 that communicate the internal space (i.e., the second combustion chamber 20) and the external space (i.e., the first combustion chamber 10) are formed in the surrounding wall portion 81 of the second inner cylinder member 8. The communication holes h2 are closed by a sealing tape (not shown) in a state before the second ignition device 7 operates.

[0028] [Filter] As shown in FIG. 1, the filter 9 is formed in a cylindrical shape, surrounds the first gas generating agent 110, and is disposed in the first combustion chamber 10 such that the gas discharge holes 12 are located outside in the radial direction thereof. That is, the filter 9 is disposed between the first gas generating agent 110 and the gas discharge holes 12 so as to surround the first gas generating agent 110. One end surface (upper end surface) of the filter 9 in the axial direction abuts against and is supported by the top plate portion 22 of the upper shell 2 , and the other end surface (lower end surface) abuts against and is supported by the bottom plate portion 32 of the lower shell 3. When the combustion gas of the first gas generating agent 110 or the second gas generating agent 120 passes through the filter 9, the filter 9 cools the combustion gas by taking away the heat of the combustion gas. Further, in addition to the cooling function of the combustion gas, the filter 9 has a function of filtering the combustion gas by collecting combustion residues contained in the combustion gas.

[0029] [Transfer gunpowder] As the transfer gunpowder 6, in addition to known black powder, a gas generating agent with good ignition properties and a combustion temperature higher than that of the first gas generating agent 110 can be used. The combustion temperature of the transfer gunpowder 6 can be set in the range of 1700 to 3000°C. As such transfer gunpowder 6, for example, known ones containing nitroguanidine (34% by weight) and strontium nitrate (56% by weight) can be used. Also, the transfer gunpowder 6 can adopt various shapes such as granular, pellet-shaped, columnar, disk-shaped, etc.

[0030] [Gas generating agent] For the first gas generating agent 110 and the second gas generating agent 120, a gas generating agent with a relatively low combustion temperature can be used. The combustion temperature of the first gas generating agent 110 and the second gas generating agent 120 can be set in the range of 1000 to 1700°C. As such first gas generating agent 110 and second gas generating agent 120, for example, known ones containing guanidine nitrate (41% by weight), basic copper nitrate (49% by weight), and a binder and additives can be used. Also, the first gas generating agent 110 and the second gas generating agent 120 can adopt various shapes such as granular, pellet-shaped, columnar, disk-shaped, etc.

[0031] [Communication hole] Figure 2 is a cross-sectional view taken along the line A-A of Figure 1. In Figure 2, a cross-section orthogonal to the housing central axis A1 and the inner cylinder central axis A5 of the gas generator 100A before operation is shown. Also, in Figure 2, for the sake of convenience, the illustration of the first ignition device 4, the second ignition device 7, the joint portion 23, and the joint portion 33 is omitted. As shown in Figure 2, a virtual straight line passing through the housing central axis A1 and the inner cylinder central axis A5 in the axial view of the surrounding wall portion 51 is defined as the virtual center line CL1.

[0032] As shown in FIG. 2, the plurality of communication holes h1 are arranged offset in the circumferential direction of the surrounding wall portion 51. Specifically, communication hole groups each consisting of three communication holes h1 that are close to each other in the circumferential direction of the surrounding wall portion 51 are formed at two locations on the surrounding wall portion 51. The two communication hole groups are formed at positions that are line-symmetric with respect to the virtual center line CL1 as the axis of symmetry. As a result, the surrounding wall portion 51 of the first inner cylinder member 5 is divided in its circumferential direction into combustion product discharge regions R1a, R1b where the plurality of communication holes h1 are grouped together, and combustion product non-discharge regions R2a, R2b excluding the combustion product discharge regions R1a, R1b. That is, the combustion product discharge regions R1a, R1b are regions where the communication holes are arranged, and the combustion product non-discharge regions R2a, R2b are regions where the communication holes h1 are not arranged. The combustion product discharge regions R1a, R1b are positioned line-symmetrically with respect to the virtual center line CL1 as the axis of symmetry. Here, as shown in FIG. 2, in the axial view of the surrounding wall portion 51, a straight line that passes through one end portion in the circumferential direction of the combustion product discharge region R1a from the inner cylinder central axis A5 and intersects the peripheral wall portion 11 is defined as the first virtual straight line L1a, and a straight line that passes through the other end portion in the circumferential direction of the combustion product discharge region R1a from the inner cylinder central axis A5 and intersects the peripheral wall portion 11 is defined as the second virtual straight line L2a. Similarly, in the axial view of the surrounding wall portion 51, a straight line that passes through one end portion in the circumferential direction of the combustion product discharge region R1b from the inner cylinder central axis A5 and intersects the peripheral wall portion 11 is defined as the first virtual straight line L1b, and a straight line that passes through the other end portion in the circumferential direction of the combustion product discharge region R1b from the inner cylinder central axis A5 and intersects the peripheral wall portion 11 is defined as the second virtual straight line L2b. That is, the surrounding wall portion 51 is divided by the first virtual straight line L1a, the second virtual straight line L2a, the first virtual straight line L1b, and the second virtual straight line L2b. More specifically, in the surrounding wall portion 51, the region between the first virtual straight line L1a and the second virtual straight line L2a is the combustion product discharge region R1a , the region between the first virtual straight line L1b and the second virtual straight line L2b is the combustion product discharge region R1b, the region between the first virtual straight line L1a and the first virtual straight line L1b is the combustion product non-discharge region R2a, and the region between the second virtual straight line L2a and the second virtual straight line L2b is the combustion product non-discharge region R2b.

[0033] [Gas discharge hole] As shown in FIG. 2, the peripheral wall portion 11 of the housing 1 is divided into communication hole corresponding regions R10a and R10b and communication hole non-corresponding regions R20a and R20b in the circumferential direction of the peripheral wall portion 11 by a first virtual straight line L1a, a second virtual straight line L2a, a first virtual straight line L1b, and a second virtual straight line L2b. In the axial view of the surrounding wall portion 51, the range of the communication hole corresponding region R10a is defined by the first virtual straight line L1a and the second virtual straight line L2a, the range of the communication hole corresponding region R10b is defined by the first virtual straight line L1b and the second virtual straight line L2b, the range of the communication hole non-corresponding region R20a is defined by the first virtual straight line L1a and the first virtual straight line L1b, and the range of the communication hole non-corresponding region R20b is defined by the second virtual straight line L2a and the second virtual straight line L2b. Therefore, as shown in FIG. 2, in the radial direction centered on the inner cylinder central axis A5, which is the central axis of the surrounding wall portion 51, the combustion product discharge region R1a and the communication hole corresponding region R10a face each other, the combustion product discharge region R1b and the communication hole corresponding region R10b face each other, the non-combustion product discharge region R2a and the communication hole non-corresponding region R20a face each other, and the non-combustion product discharge region R2b and the communication hole non-corresponding region R20b face each other. That is, in the gas generator 100, the communication hole corresponding region R10a is associated with the combustion product discharge region R1a, the communication hole corresponding region R10b is associated with the combustion product discharge region R1b, the communication hole non-corresponding region R20a is associated with the non-combustion product discharge region R2a, and the communication hole non-corresponding region R20b is associated with the non-combustion product discharge region R2b.

[0034] Also, as shown in FIG. 2, the plurality of gas discharge holes 12 formed in the peripheral wall portion 11 of the housing 1 include a first gas discharge hole 12a and a second gas discharge hole 12b having different opening pressures. The second gas discharge hole 12b is configured to have a higher opening pressure than the first gas discharge hole 12a. That is, the second gas discharge hole 12b is configured to be more difficult to open than the first gas discharge hole 12a. Specifically, the cross-sectional area (hole diameter) per one of the second gas discharge holes 12b is made smaller than the cross-sectional area (hole diameter) per one of the first gas discharge holes 12a. When the first gas generating agent 110 and the second gas generating agent 120 burn, a load acts on the sealing tape 13 due to the pressure of the combustion gas. At this time, since the cross-sectional area per one of the second gas discharge holes 12b is smaller than the cross-sectional area per one of the first gas discharge holes 12a, the load acting on the portion of the sealing tape 13 that closes the second gas discharge hole 12b is smaller than the load acting on the portion that closes the first gas discharge hole 12a. As a result, the second gas discharge hole 12b has a higher opening pressure than the first gas discharge hole 12a and is more difficult to open.

[0035] Then, as shown in FIG. 2, among the communication hole corresponding regions R10a, R10b and the communication hole non-corresponding regions R20a, R20b, the first gas discharge holes 12a are formed only in the communication hole corresponding regions R10a, R10b, and the second gas discharge holes 12b are formed only in the communication hole non-corresponding regions R20a, R20b. That is, in the communication hole corresponding regions R10a and R10b facing the combustion product discharge region R1a or the combustion product discharge region R1b where the communication hole h1 is disposed, the second gas discharge holes 12b having a high opening pressure are not formed, and only the first gas discharge holes 12a having a low opening pressure are formed.

[0036] [Operation] Hereinafter, the basic operation of the gas generator 100 according to Embodiment 1 will be described with reference to FIG. 1. In this example, the case where the second ignition device 7 operates after the first ignition device 4 (that is, after the first ignition device 4 operates) will be described.

[0037] When a sensor (not shown) senses an impact, an ignition current is supplied to the first igniter 41 of the first ignition device 4, and the first igniter 41 operates. Then, the ignition charge housed in the first igniter 41 burns, and flames, high-temperature gases, etc., which are the combustion products, are released into the ignition means chamber 53. As a result, the transfer charge 6 housed in the ignition means chamber 53 burns, and combustion gas is generated in the ignition means chamber 53. When the seal tape that has been closing the communication hole h1 of the surrounding wall portion 51 is broken by the pressure of the combustion gas of the transfer charge 6, the combustion gas is discharged to the outside of the ignition means chamber 53 through the communication hole h1. Then, the combustion gas of the transfer charge 6 comes into contact with the first gas generating agent 110 disposed around the surrounding wall portion 51, and the first gas generating agent 110 is ignited. When the first gas generating agent 110 burns, high-temperature and high-pressure combustion gas is generated in the first combustion chamber 10. When this combustion gas passes through the filter 9, the combustion gas is cooled and combustion residues are collected. The combustion gas of the first gas generating agent 110 that has been cooled and filtered by the filter 9 breaks the seal tape 13 that has been closing the gas discharge hole 12 and is discharged from the gas discharge hole 12 to the outside of the housing 1.

[0038] Next, when the second igniter 71 of the second ignition device 7 operates, the second gas generating agent 120 housed in the second combustion chamber 20 burns, and combustion gas is generated in the second combustion chamber 20. When the seal tape that has been closing the communication hole h2 of the surrounding wall portion 81 is broken by the pressure of the combustion gas of the second gas generating agent 120, the combustion gas is discharged to the first combustion chamber 10 through the communication hole h2. The combustion gas of the second gas generating agent 120 is cooled and filtered by the filter 9 and then discharged from the gas discharge hole 12 to the outside of the housing 1.

[0039] After the combustion gases of the first gas generating agent 110 and the second gas generating agent 120 are discharged to the outside of the housing 1, they flow into an airbag (not shown). When the airbag expands, a cushion is formed between the occupant and the rigid structure, and the occupant is protected from the impact.

[0040] [Regarding the correspondence between the communication hole and the gas discharge hole] Generally, the combustion performance of a gas generant tends to improve as the surroundings of the gas generant are at a higher temperature or pressure. That is, in a low-temperature and low-pressure environment, the combustion of the gas generant becomes inactive. Therefore, in order to reduce the difference in the output performance of the gas generator between operation at high temperature (hereinafter referred to as high-temperature operation) and operation at low temperature (hereinafter referred to as low-temperature operation) and to achieve stabilization of the output performance, it is necessary to increase the internal pressure of the housing during low-temperature operation and enhance the combustion performance of the gas generant. In the gas generator 100, by arranging the communication hole h1, the first gas discharge hole 12a, and the second gas discharge hole 12b as described above, it is possible to increase the internal pressure of the housing during low-temperature operation and reduce the difference in the combustion performance of the gas generant between low-temperature operation and high-temperature operation. The details will be described below.

[0041] FIG. 3 is a cross-sectional view showing the state of the gas generator 100 during low-temperature operation. FIG. 4 is a cross-sectional view showing the state of the gas generator 100 during high-temperature operation. In FIGS. 3 and 4, the cross-section corresponding to FIG. 2 is shown. As shown in FIGS. 3 and 4, in the gas generator 100, only the first gas discharge hole 12a having a low opening pressure among the plurality of gas discharge holes 12 opens during low-temperature operation, and the second gas discharge hole 12b having a high opening pressure also opens together with the first gas discharge hole 12a during high-temperature operation. In the gas generator 100, by opening only the first gas discharge hole 12a during low-temperature operation, while discharging the combustion gas from the first gas discharge hole 12a, the combustion gas is more likely to accumulate inside the housing 1 (the first combustion chamber 10) compared to the case where all the gas discharge holes 12 open at the same temperature. Thereby, the internal pressure of the housing 1 during low-temperature operation is increased, and the combustion performance of the gas generant is enhanced. On the other hand, during high-temperature operation when it is expected that the combustion performance of the gas generant is high from the beginning, by opening both the first gas discharge hole 12a and the second gas discharge hole 12b to discharge the combustion gas, an excessive increase in the internal pressure of the housing 1 is suppressed. In this way, in the gas generator 100, by enhancing the combustion performance of the gas generant during low-temperature operation the difference in the output performance of the gas generator between high-temperature operation and low-temperature operation is reduced, and stabilization of the output performance is achieved.

[0042] Here, the arrows indicated by the reference symbol F1 in FIGS. 3 and 4 represent the traveling directions of the combustion products discharged from the communication holes h1. As shown in FIGS. 3 and 4, the combustion products discharged from the ignition means chamber 53 through the communication holes h1 by the operation of the first ignition device 4 are discharged radially around the inner cylinder central axis A5 which is the central axis of the surrounding wall portion 51. That is, the combustion products are discharged toward the communication hole corresponding regions R10a and R10b which are regions facing the combustion product discharge regions R1a and R1b in the radial direction centered on the inner cylinder central axis A5. Therefore, the first gas generating agent 110 disposed in the first combustion chamber 10 is ignited in order from the ones disposed on the combustion product discharge regions R1a and R1b sides to the communication hole corresponding regions R10a and R10b sides. As a result, most of the combustion gas of the first gas generating agent 110 flows radially from the combustion product discharge regions R1a and R1b sides and collides with the communication hole corresponding regions R10a and R10b.

[0043] If the second gas discharge holes 12b are formed in the communication hole corresponding regions R10a or the communication hole corresponding regions R10b, even during low-temperature operation, the second gas discharge holes 12b may be opened by the pressure of the combustion gas colliding with the communication hole corresponding regions R10a or the communication hole corresponding regions R10b. Then, the second gas discharge holes 12b may be additionally opened in addition to the first gas discharge holes 12a, and the internal pressure of the housing may not become as high as expected. Conversely, if the first gas discharge holes 12a are formed in the non-communication hole corresponding regions R20a or the non-communication hole corresponding regions R20b, the first gas discharge holes 12a may not be opened during low-temperature operation. Then, the number of the opened first gas discharge holes 12a may be insufficient, and the internal pressure of the housing may become excessively high. In any case, the combustion performance of the gas generating agent cannot be obtained as expected, and it becomes difficult to stabilize the output performance.

[0044] On the other hand, in the gas generator 100, the first gas discharge holes 12a are formed only in the communication hole corresponding regions R10a and R10b of the peripheral wall portion 11 that face the combustion product discharge regions R1a and R1b, and the second gas discharge holes 12b are formed only in the communication hole non-corresponding regions R20a and R20b of the peripheral wall portion 11 that do not face the combustion product discharge regions R1a and R1b. Therefore, during low-temperature operation, the first gas discharge holes 12a are more likely to open, and the second gas discharge holes 12b are less likely to open. Accordingly, during low-temperature operation, only the first gas discharge holes 12a can be more reliably opened out of the first gas discharge holes 12a and the second gas discharge holes 12b. Thereby, the internal pressure of the housing and the combustion performance of the gas generant during low-temperature operation can be surely increased. As a result, the difference in output performance of the gas generator 100 between low-temperature operation and high-temperature operation can be reduced, and the output performance can be stabilized.

[0045] [Function and Effect] As described above, in the gas generator 100, the plurality of gas discharge holes 12 include the first gas discharge holes 12a and the second gas discharge holes 12b having an opening pressure higher than that of the first gas discharge holes 12a. The surrounding wall portion 51 of the first inner cylinder member 5 is divided in the circumferential direction of the surrounding wall portion 51 into combustion product discharge regions R1a and R1b in which a plurality of communication holes h1 are collectively arranged, and combustion product non-discharge regions R2a and R2b excluding the combustion product discharge regions R1a and R1b. The peripheral wall portion 11 of the housing 1 is divided in the circumferential direction of the peripheral wall portion 11 into communication hole corresponding regions R10a and R10b associated with the combustion product discharge regions R1a and R1b, and communication hole non-corresponding regions R20a and R20b associated with the combustion product non-discharge regions R2a and R2b. The first gas discharge holes 12a are formed only in the communication hole corresponding regions R10a and R10b, and the second gas discharge holes 12b are formed only in the communication hole non-corresponding regions R20a and R20b. According to such a gas generator 100, by forming the first gas discharge holes 12a only in the communication hole corresponding regions R10a and R10b, the first gas discharge holes 12a are made more likely to open, and by forming the second gas discharge holes 12b only in the communication hole non-corresponding regions R20a and R20b, the second gas discharge holes 12b are made less likely to open This is possible. As a result, during low-temperature operation, it becomes possible to more reliably open only the first gas discharge hole 12a. Consequently, according to the gas generator 100, as described above, the difference in output performance between low-temperature operation and high-temperature operation can be reduced, and stable output performance can be obtained.

[0046] Also, in the gas generator 100, on the peripheral wall portion 11, the first gas discharge hole 12a and the second gas discharge hole 12b are separately arranged in different regions (the communication hole corresponding regions R10a, R10b and the non-communication hole corresponding regions R20a, R20b). Therefore, the second gas discharge hole 12b is less likely to be affected by the combustion gas flowing into the first gas discharge hole 12a. As a result, it is possible to make it more difficult to open the second gas discharge hole 12b during low-temperature operation. In the circumferential direction of the peripheral wall portion 11, the distance between adjacent first gas discharge holes 12a within the communication hole corresponding regions R10a, R10b and the distance between adjacent second gas discharge holes 12b within the non-communication hole corresponding regions R20a, R20b may be set to be larger than the distance between the adjacent first gas discharge hole 12a and the second gas discharge hole 12b.

[0047] Also, in the gas generator 100, the communication hole corresponding regions R10a, R10b are formed as regions that face the combustion product discharge regions R1a, R1b in the radial direction centered on the inner cylinder central axis A5 of the peripheral wall portion 11. As a result, the communication hole corresponding regions R10a, R10b are associated with the combustion product discharge regions R1a, R1b.

[0048] Furthermore, in the gas generator 100, in the axial view of the surrounding wall portion 51, the ranges of the communication hole corresponding regions R10a, R10b are defined by the first virtual straight lines L1a, L1b and the second virtual straight lines L2a, L2b. As a result, the communication hole corresponding regions R10a, R10b are defined as regions that face the combustion product discharge regions R1a, R1b in the radial direction centered on the inner cylinder central axis A5.

[0049] Furthermore, in the gas generator 100, the inner cylinder central axis A5, which is the central axis of the surrounding wall portion 51, is separated from the housing central axis A1, which is the central axis of the peripheral wall portion 11. That is, the first inner cylinder member 5 is eccentrically arranged with respect to the center of the housing 1. Further, the surrounding wall portion 51 includes combustion product discharge regions R1a and R1b that are symmetric with respect to each other with the virtual center line CL1 as the axis of symmetry in the axial view. Further, the peripheral wall portion 11 includes a communication hole corresponding region R10a associated with the combustion product discharge region R1a and a communication hole corresponding region R10b associated with the combustion product discharge region R1b. Furthermore, communication holes h1 are formed in the combustion product discharge regions R1a and R1b so as to be symmetric with respect to the virtual center line CL1, and first gas discharge holes 12a are formed in the communication hole corresponding regions R10a and R10b so as to be symmetric with respect to the virtual center line CL1. That is, in the gas generator 100, the arrangements of the communication holes h1 and the first gas discharge holes 12a are symmetric with respect to the virtual center line CL1. According to this, since the communication hole corresponding region R10a and the communication hole corresponding region R10b are symmetrically located, when only the first gas discharge hole 12a is opened during low-temperature operation, the thrust of the combustion gas discharged from the first gas discharge hole 12a in the communication hole corresponding region R10a and the thrust of the combustion gas discharged from the first gas discharge hole 12a in the communication hole corresponding region R10b are canceled out. As a result, the balance of the gas generator 100 during operation becomes stable.

[0050] Furthermore, in the gas generator 100, the opening pressure of the first gas discharge hole 12a formed in the communication hole corresponding region R10a is equal to the opening pressure of the first gas discharge hole 12a formed in the communication hole corresponding region R10b that is symmetric with the communication hole corresponding region R10a. By making the opening pressures of the first gas discharge holes 12a that are symmetric with respect to each other equal in this way, the positions of the first gas discharge holes 12a that open during low-temperature operation become symmetric. As a result, the balance of the gas generator 100 during operation becomes more stable. In addition to this, in the gas generator 100, the second gas discharge holes 12b formed in the non-communication hole corresponding regions R20a and R20b also have a virtual center line Since it is symmetrically arranged with respect to CL1, the balance of the gas generator 100 during operation becomes even more stable.

[0051] Note that the combustion product discharge region R1a corresponds to the "first combustion product discharge region" according to the present disclosure, the combustion product discharge region R1b corresponds to the "second combustion product discharge region" according to the present disclosure, the communication hole corresponding region R10a corresponds to the "first communication hole corresponding region" according to the present disclosure, and the communication hole corresponding region R10b corresponds to the "second communication hole corresponding region" according to the present disclosure.

[0052] Also, as shown in FIGS. 2 to 4, the second inner cylinder member 8 that forms the second gas generating agent 120 inside is arranged so as not to be located between the combustion product discharge region R1a and the communication hole corresponding region R10a or between the combustion product discharge region R1b and the communication hole corresponding region R10b in the radial direction centered on the inner cylinder central axis A5. That is, the second inner cylinder member 8 is arranged at a position that does not obstruct the flow from the combustion product discharge regions R1a and R1b sides of the combustion gas of the first gas generating agent 110 toward the communication hole corresponding regions R10a and R10b sides. Thereby, the first gas discharge holes 12a formed in the communication hole corresponding regions R10a and R10b can be opened more reliably.

[0053] In this example, the opening pressures of the first gas discharge hole 12a and the second gas discharge hole 12b are made different by varying the cross-sectional area (hole diameter) per one of the first gas discharge hole 12a and the second gas discharge hole 12b, but the present disclosure is not limited to this. For example, the strength of the closing member that closes the gas discharge hole is partially adjusted, and the strength of the part that closes the second gas discharge hole is made higher than the strength of the part that closes the first gas discharge hole, so that the opening pressure of the second gas discharge hole may be made higher than the opening pressure of the first gas discharge hole. Also, the opening pressure may be adjusted by both the hole diameter of each gas discharge hole and the strength of the closing member that closes it. Note that the strength of the closing member is, for example, adjustment of the material of the closing member or the thickness including lamination.

[0054] In this example, a plurality (three) of communication holes h1 are arranged in each of the combustion product discharge regions R1a and R1b. However, the number of communication holes arranged in the combustion product discharge region according to the present disclosure is not particularly limited. Only one communication hole may be arranged in the combustion product discharge region instead of a plurality. Further, in the present disclosure, the number and arrangement of the communication holes in the surrounding wall portion are not limited to those shown in FIG. 2 and the like. In the above example, the communication hole h1 may be formed at a location other than the combustion product discharge region R1a or the combustion product discharge region R1b. Also, the communication hole formed in the surrounding wall portion is not limited to a plurality, and may be only one.

[0055] In this example, the primer 6 is housed in the ignition means chamber 53. However, the gas generator of the present disclosure may be configured to ignite the first gas generating agent by increasing the type and amount of the ignition powder of the first igniter 41 without using the primer 6. That is, the gas generator according to the present disclosure may be configured to discharge combustion products from the ignition means chamber through the communication hole by the operation of the first ignition device. In the present disclosure, the "combustion products" discharged from the communication hole and igniting the first gas generating agent are not limited to the combustion products of the primer, and may be the combustion products of the ignition powder. Also, a primer integrated with the first igniter 41 may be used as the first ignition device.

[0056] [Modification Example 1 of Embodiment 1] Hereinafter, a gas generator according to a modification example of Embodiment 1 will be described. In the description of the modification example, the differences from the gas generator 100 described with reference to FIGS. 1 to 4 will be mainly described, and the same points as those of the gas generator 100 will be denoted by the same reference numerals, and detailed description thereof will be omitted.

[0057] [Modification Example 1 of Embodiment 1] FIG. 5 is a cross-sectional view of a gas generator 100A according to Modification Example 1 of Embodiment 1. FIG. 5 shows a state before the operation of the gas generator 100A. FIG. 6 is a perspective view of the first inner cylinder member 5A according to Modification Example 1 of Embodiment 1. As shown in FIGS. 5 and 6, the gas generator 100A In this case, one communication hole h1A is disposed in each of the combustion product discharge regions R1a and R1b. The communication hole h1A is formed as a single hole extending in the circumferential direction of the surrounding wall portion 51 across each of the combustion product discharge region R1a or the combustion product discharge region R1b.

[0058] Also with the gas generator 100A shown in FIG. 5, similar to the above-described gas generator 100, stabilization of output performance can be achieved. Further, according to the gas generator 100A, since the communication holes h1A are formed in the entire combustion product discharge regions R1a and R1b, the combustion products radially discharged from the ignition means chamber 53 through the communication holes h1A are evenly discharged toward the entire communication hole corresponding regions R10a and R10b facing the combustion product discharge regions R1a and R1b. Thereby, the combustion gas of the first gas generating agent 110 can be uniformly collided against the communication hole corresponding regions R10a and R10b, and the first gas discharge holes 12a formed in the communication hole corresponding regions R10a and R10b can be more surely opened.

[0059] [Modification Example 2 of Embodiment 1] FIG. 7 is a cross-sectional view of a gas generator 100B according to Modification Example 2 of Embodiment 1. In FIG. 7, a state before the operation of the gas generator 100B is shown. As shown in FIG. 7, the gas generator 100B is different from the gas generator 100 in that it does not have the combustion product discharge region R1b and the corresponding communication hole corresponding region R10b. That is, in the gas generator 100B, when the virtual center line CL1 is used as the axis of symmetry, the communication holes h1 and the gas discharge holes 12 are asymmetrically arranged. As exemplified by the gas generator 100B, in the gas generator according to the present disclosure, the communication holes and the gas discharge holes do not have to be arranged symmetrically with respect to each other with the virtual center line as the axis of symmetry. Also with the gas generator 100A shown in FIG. 7, similar to the above-described gas generator 100, stabilization of output performance can be achieved.

[0060] <Embodiment 2> Hereinafter, the gas generator according to Embodiment 2 will be described with a focus on the differences from the gas generator 100, and the same parts as those of the gas generator 100 will be denoted by the same reference numerals, and detailed description thereof will be omitted. FIG. 8 is a longitudinal sectional view of the gas generator 200 according to Embodiment 2. FIG. 9 is a sectional view taken along line B-B of FIG. 8. FIGS. 8 and 9 show the state of the gas generator 200 before operation.

[0061] As shown in FIGS. 8 and 9, the gas generator 200 according to Embodiment 2 is different from the gas generator 100 according to Embodiment 1 in that it does not include a second ignition device 7, a second inner cylinder member 8, a second gas generating agent 120, and a second combustion chamber 20. That is, the gas generator 200 is configured as a so-called single type gas generator having only one ignition device, and the position thereof is offset from the housing central axis A1. Also with the gas generator 200 shown in FIGS. 8 and 9, it is possible to realize stabilization of output performance, similar to the gas generator 100 according to Embodiment 1.

[0062] [Modification Example 1 of Embodiment 2] FIG. 10 is a cross-sectional view of the gas generator 200A according to Modification Example 1 of Embodiment 2. FIG. 10 shows the state of the gas generator 200A before operation. As shown in FIG. 10, the gas generator 200A is different from the gas generator 200 in that the inner cylinder central axis A5 coincides with the housing central axis A1, that is, the first inner cylinder member 5 is disposed at the center of the housing 1, and there is no member associated with the second combustion chamber, being of a single type. Also with the gas generator 200A shown in FIG. 10, it is possible to realize stabilization of output performance, similar to the gas generator 100 according to Embodiment 1.

[0063] Furthermore, as shown in FIG. 10, the gas generator 200A is formed to be point-symmetrical in the axial direction view. Specifically, the combustion product discharge region R1a and the combustion product discharge region R1b are point-symmetric to each other with the housing central axis A1 (inner cylinder central axis A5) as the center of symmetry, and are connected The through-hole corresponding region R10a and the communication hole corresponding region R10b are point-symmetric to each other with the housing central axis A1 as the center of symmetry. Further, communication holes h1 are formed in the combustion product discharge regions R1a and R1b so as to be point-symmetric with the housing central axis A1 as the center of symmetry, and first gas discharge holes 12a are formed in the communication hole corresponding regions R10a and R10b so as to be point-symmetric with the housing central axis A1 as the center of symmetry. According to this, since the communication hole corresponding region R10a and the communication hole corresponding region R10b are point-symmetrically located, when only the first gas discharge hole 12a is opened during low-temperature operation, the thrust of the combustion gas discharged from the first gas discharge hole 12a in the communication hole corresponding region R10a and the thrust of the combustion gas discharged from the first gas discharge hole 12a in the communication hole corresponding region R10b cancel each other out. As a result, the balance of the gas generator 100 during operation becomes stable.

[0064] <Others> As described above, the preferred embodiments of the present disclosure have been described. However, each aspect disclosed in this specification can be combined with any other features disclosed in this specification.

Description of Reference Numerals

[0065] 100, 200 Gas generators 1 Housing 11 Peripheral wall portion 12 Gas discharge hole 12a First gas discharge hole 12b First gas discharge hole 4 First ignition device 5 First inner cylinder member 51 Surrounding wall portion 53 Ignition means chamber 6 Transfer powder 7 Second ignition device 8 Second inner cylinder member 10 First combustion chamber 20 Second combustion chamber 110 First gas generating agent 120 Second gas generating agent h1 Communication hole A1 Housing central axis A5 Inner cylinder central axis R1a, R1b Combustion product discharge region R2a, R2b Combustion product non-discharge region R10a, R10b Communication hole corresponding region R20a, R20b Communication hole non-corresponding region

Claims

1. a first ignition device; a first combustion chamber in which the first ignition device is disposed; a housing including a cylindrical peripheral wall portion, a top plate portion provided at one end side of the peripheral wall portion, and a bottom plate portion provided at the other end side of the peripheral wall portion so as to face the top plate portion, and defining the first combustion chamber together with the peripheral wall portion and the top plate portion and fixing the first ignition device; a first inner cylinder member including a cylindrical surrounding wall portion surrounding the first ignition device and forming an ignition means chamber between the first ignition device and the outside of the first inner cylinder member, and one or more communication holes communicating the ignition means chamber with the outside of the first inner cylinder member being formed in the surrounding wall portion; a first gas generating agent disposed in the first combustion chamber so as to surround the surrounding wall portion and combusted by combustion products discharged from the ignition means chamber through the communication holes by the operation of the first ignition device; a plurality of gas discharge holes formed in the housing and communicating the first combustion chamber with the outside of the housing by opening in response to the combustion pressure of the gas generating agent; comprising; the plurality of gas discharge holes include a first gas discharge hole and a second gas discharge hole having a higher opening pressure than the first gas discharge hole; the surrounding wall portion is divided in the circumferential direction of the surrounding wall portion into a combustion product discharge region in which one of the communication holes is disposed or a plurality of the communication holes are collectively disposed, and a combustion product non-discharge region excluding the combustion product discharge region; the peripheral wall portion is divided in the circumferential direction of the peripheral wall portion into a communication hole corresponding region associated with the combustion product discharge region and a communication hole non-corresponding region associated with the combustion product non-discharge region; among the communication hole corresponding region and the communication hole non-corresponding region, the first gas discharge hole is formed only in the communication hole corresponding region, and the second gas discharge hole is formed only in the communication hole non-corresponding region; a gas generator.

2. The communication hole corresponding region is a region of the peripheral wall portion that faces the combustion product discharge region in the radial direction centered on the central axis of the surrounding wall portion. The gas generator according to claim 1. The gas generator according to claim 1.

3. The range of the communication hole corresponding region is defined in the axial view of the surrounding wall portion by a first virtual straight line that intersects the peripheral wall portion from the central axis of the surrounding wall portion through one end portion in the circumferential direction of the combustion product discharge region of the surrounding wall portion, and a second virtual straight line that intersects the peripheral wall portion from the central axis of the surrounding wall portion through the other end portion in the circumferential direction of the combustion product discharge region of the surrounding wall portion. The gas generator according to claim 1 or 2.

4. The central axis of the surrounding wall portion and the central axis of the peripheral wall portion are separated from each other, the surrounding wall portion includes a first combustion product discharge region and a second combustion product discharge region that are symmetrically located with respect to each other with a virtual center line passing through the central axis of the surrounding wall portion and the central axis of the peripheral wall portion as the axis of symmetry in the axial direction view of the surrounding wall portion, the peripheral wall portion includes a first communication hole corresponding region that is the communication hole corresponding region associated with the first combustion product discharge region and a second communication hole corresponding region that is the communication hole corresponding region associated with the second combustion product discharge region, the communication holes are formed in the first combustion product discharge region and the second combustion product discharge region so as to be symmetrically arranged with the virtual center line as the axis of symmetry, in the first communication hole corresponding region and the second communication hole corresponding region, the first gas discharge holes are formed so as to be symmetrically arranged with the virtual center line as the axis of symmetry. The gas generator according to any one of claims 1 to 3.

5. The opening pressure of the first gas discharge hole formed in the first communication hole corresponding region is equal to the opening pressure of the first gas discharge hole formed in the second communication hole corresponding region. The gas generator according to claim 4.

6. A second ignition device; A second gas generating agent that burns by the operation of the second ignition device; A second combustion chamber in which the second ignition device and the second gas generating agent are arranged; A cylindrical second inner cylinder member disposed in the housing, and the second inner cylinder member forms the second combustion chamber inside it; the second inner cylinder member is arranged so as not to be located between the combustion product discharge region and the communication hole corresponding region in the radial direction centered on the central axis of the surrounding wall portion. The gas generator according to any one of claims 1 to 5.

7. The communication hole is formed as a single hole extending in the circumferential direction of the surrounding wall portion across the combustion product discharge region. The gas generator according to any one of claims 1 to 6.

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