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 technology]

[0002] Conventionally, a widely used gas generator comprises an igniter and a gas generating agent disposed within a housing, an inner cylindrical member surrounding the igniter, a communication hole formed in the inner cylindrical member, and when the igniter is activated, the gas generating agent is burned by the combustion products discharged from the communication hole, and the combustion gas is then discharged to the outside from a plurality of gas exhaust holes formed in the housing.

[0003] The output performance of a gas generator is determined by parameters such as the amount of combustion gas discharged and the discharge time, and in order to achieve the desired output performance, it is important to burn the gas generating agent as desired. Here, the combustion performance of the gas generating agent changes depending on the surrounding temperature and pressure during combustion. In general, the higher the temperature or the higher the pressure, the more actively the gas generating agent reacts (burns). In other words, 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 to increase during combustion. 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 and low temperatures and to stabilize 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 relation to this, in order to suppress a decrease in the combustion performance of the gas generating agent at low temperatures, a technology is known in which the rupture pressure of a blocking member blocking some of the gas discharge holes is made higher than the rupture pressure of a blocking member blocking other gas discharge holes, and 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 cylindrical member is strong, it is considered that the gas generating agent in the housing burns preferentially in the vicinity of the communication holes in the circumferential direction of the inner cylindrical member. Therefore, it is presumed that the combustion of the gas generating agent is easily non-uniform due to the arrangement of the communication holes, and pressure and temperature spots (bias) occur momentarily in the housing. In particular, when the inner cylindrical member containing the ignition device is offset from the center position of the housing, the ignition environment and combustion environment of the gas generating agent differ in the circumferential direction, so that ignition spots tend to occur easily. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 11-348711 [Patent Document 2] U.S. Patent No. 6,722,694 Summary of the Invention [Problem to be solved by the invention]

[0006] In conventional gas generators, the gas exhaust holes are 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 cylindrical member as described above. Therefore, even if some gas exhaust holes are made harder to open than other gas exhaust holes by making the cleavage pressure of the blocking member different, there is a risk that not only the other gas exhaust holes but also some of the gas exhaust holes will open at low temperatures. In this case, the combustion gas in the housing will easily escape due to the extra gas exhaust holes being open, and the internal pressure of the housing will be lower than expected. As a result, the combustion performance of the gas generating agent will not be as expected, and there is a possibility that the output performance of the gas generator will not be stably obtained.

[0007] The technique of the present disclosure has been made in consideration of the above-mentioned problems, and an object of the technique is to provide a gas generator with stable output performance. [Means for solving the problem]

[0008] In order to solve the above problems, the technology disclosed herein employs the following configuration. That is, the technology of the present disclosure is a gas generator, comprising: a housing including 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 on one end side of the peripheral wall portion, and a bottom plate portion provided on the other end side of the peripheral wall portion so as to face the top plate portion, defining the first combustion chamber together with the peripheral wall portion and the top plate portion, 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, the first inner cylinder member having one or more communication holes formed in the surrounding wall portion that communicate the ignition means chamber with an outside of the first inner cylinder member; a first gas generating agent that is disposed in the first combustion chamber so as to surround the surrounding wall portion and that is combusted by combustion products discharged from the ignition means chamber through the communication hole upon activation of the first ignition device; a plurality of gas discharge holes which open when subjected to a combustion pressure to communicate the first combustion chamber with the outside of the housing, the plurality of gas discharge holes including 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 being divided in a circumferential direction of the surrounding wall portion into a combustion product discharge region in which one of the communication holes is arranged or in which the plurality of communication holes are arranged together, and a combustion product non-discharge region excluding the combustion product discharge region, the peripheral wall portion being divided in a circumferential direction of the peripheral wall portion into a communication hole corresponding region which corresponds to the combustion product discharge region and a communication hole non-corresponding region which corresponds to the combustion product non-discharge region, and of 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.

[0009] According to such a gas generator, by forming the first gas discharge hole only in the communication hole corresponding region corresponding to the combustion product discharge region, the first gas discharge hole with a low opening pressure can be made easier to open, and by forming the second gas discharge hole only in the communication hole non-corresponding region, the second gas discharge hole with a high opening pressure can be made more difficult to open. This makes it possible to more reliably open only the first gas discharge hole during low temperature operation. Therefore, it is possible to reliably increase the internal pressure of the housing and the combustion performance of the gas generating agent during low temperature operation. As a result, according to the gas generator of the present disclosure, it is possible to reduce the difference in output performance between low temperature operation and high temperature operation, and obtain stable output performance.

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

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

[0012] Moreover, in the gas generator of the present disclosure, a central axis of the surrounding wall portion and a central axis of the circumferential 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 which are the combustion product discharge regions located in line symmetry with each other about an imaginary center line passing through the central axis of the surrounding wall portion and the central axis of the circumferential wall portion when viewed in the axial direction of the surrounding wall portion, and the circumferential wall portion includes a first communication hole corresponding region which is the communication hole corresponding region associated with the first combustion product discharge region, and a second communication hole corresponding region which is the communication hole corresponding region associated with the second combustion product discharge region. and a second communication hole corresponding region which is a first gas discharge hole corresponding to the first combustion product discharge region and the second combustion product discharge region, the communication holes being formed in a line-symmetrical arrangement with the virtual center line as an axis of symmetry, and the first gas discharge holes being formed in the first communication hole corresponding region and the second communication hole corresponding region, the first gas discharge holes being formed in a line-symmetrical arrangement with the virtual center line as an axis of symmetry.

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

[0014] In addition, the gas generator of the present disclosure may further include a second ignition device, a second gas generating agent that is combusted by activation 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 arranged within the housing and forming the second combustion chamber therein, and the second inner cylinder member may be arranged so as not to be located between the combustion product discharge area and the communication hole corresponding area in the radial direction centered on the central axis of the surrounding wall portion.

[0015] Moreover, 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. Effect of the Invention

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

[0017] [Figure 1] 1 is a vertical sectional view of a gas generator according to a first embodiment. FIG. [Diagram 2] 2 is a cross-sectional view taken along line AA in FIG. 1. [Diagram 3] FIG. 4 is a cross-sectional view showing the state of the gas generator during low-temperature operation. [Figure 4]FIG. 4 is a cross-sectional view showing the state of the gas generator during high temperature operation. [Diagram 5] FIG. 2 is a cross-sectional view of a gas generator according to a first modified example of the first embodiment. [Figure 6] 11 is a perspective view of a first inner cylinder member according to a first modified example of the first embodiment. FIG. [Figure 7] FIG. 11 is a cross-sectional view of a gas generator according to a second modification of the first embodiment. [Figure 8] FIG. 11 is a vertical sectional view of a gas generator according to a second embodiment. [Figure 9] 9 is a cross-sectional view of FIG. 8 taken along line B-B. [Figure 10] FIG. 11 is a cross-sectional view of a gas generator according to a first modified example of the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Hereinafter, a gas generator according to an embodiment of the present disclosure will be described with reference to the drawings. Note that each configuration and their combination in each embodiment is merely an example, and addition, omission, substitution, and other modifications of the configuration are possible as appropriate within the scope of the present invention. The present disclosure is not limited by the embodiments, but is limited only by the claims.

[0019] <Embodiment 1> Fig. 1 is a vertical cross-sectional view of gas generator 100 according to embodiment 1. More specifically, Fig. 1 is a cross-sectional view including a housing central axis indicated by reference symbol A1 and an inner cylinder central axis indicated by reference symbol A5. Fig. 1 shows a state before gas generator 100 is activated. Gas generator 100 is an airbag gas generator used in, for example, an airbag.

[0020] [Overall configuration] As shown in FIG. 1, the gas generator 100 includes a first ignition device 4, a first inner cylindrical member 5, an enhancer charge 6, a second ignition device 7, a second inner cylindrical member 8, a filter 9, and a first gas generating agent 110. , a second gas generating agent 120, and a housing 1 that accommodates them. The gas generator 100 is configured as a so-called dual-type gas generator equipped with two ignition devices. The gas generator 100 is configured to combust the first gas generating agent 110 by activating the first igniter 41 equipped in the first ignition device 4, to combust the second gas generating agent 120 by activating the second igniter 71 equipped in the second ignition device 7, and to discharge the combustion gas, which is a combustion product of these, from a gas discharge hole 12 formed in the housing 1. Each component of the gas generator 100 will be described below. In this specification, the activation of an igniter included in an ignition device may be expressed as "the ignition device is activated" for convenience.

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

[0022] The upper shell 2 has a cylindrical upper peripheral wall portion 21 and a top plate portion 22 closing the upper end of the upper peripheral wall portion 21, which together form an internal space. The lower end of the upper peripheral wall portion 21 forms an opening of the upper shell 2. The lower end of the upper peripheral wall portion 21 is connected to a joint portion 23 extending radially outward. The lower shell 3 has a cylindrical lower peripheral wall portion 31 and a bottom plate portion 32 closing the lower end of the lower peripheral wall portion 31, which together form an internal space. The upper end of the lower peripheral wall portion 31 is connected to a joint portion 33 extending radially outward. 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 portion 23 of the upper shell 2 and the joint portion 33 of the lower shell 3 are overlapped and joined by laser welding or the like to form a short cylindrical housing 1 with both axial ends closed. The upper peripheral wall portion 21 of the upper shell 2 and the lower peripheral wall portion 31 of the lower shell 3 form a cylindrical peripheral wall portion 11 that connects the top plate portion 22 and the bottom plate portion 32. That is, the housing 1 is configured to include the cylindrical peripheral wall portion 11, the top plate portion 22 provided on one end side of the peripheral wall portion 11, and the bottom plate portion 32 provided on the other end side so as to face the top plate portion 22. The peripheral wall portion 11, the top plate portion 22, the bottom plate portion 32, and the second inner cylinder member 8 described later define a first combustion chamber 10. The first combustion chamber 10 is formed as a space in the interior space of the housing 1 excluding the second combustion chamber 20, which is the interior 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, an enhancer charge 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 exhaust holes 12 that communicate with the first combustion chamber 10 and the external space of the housing 1 are formed in a line along the circumferential direction. More specifically, the plurality of gas exhaust holes 12 are formed in the upper peripheral wall portion 21 of the peripheral wall portion 11. Before the first ignition device 4 and the second ignition device 7 are activated, the gas exhaust holes 12 are blocked by a seal tape 13 provided on the inner peripheral surface of the peripheral wall portion 11. The seal tape 13, which is an example of a blocking member, is torn by the pressure of the combustion gas, and the gas exhaust holes 12 are opened. In this specification, the pressure required to open the gas exhaust holes 12 is referred to as the "opening pressure". In this example, the opening pressure is the pressure required to tear the seal 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. 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) therein, and are actuated by the supply of an ignition current to burn the ignition charge and release the combustion product 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 simultaneously with the actuation of the first ignition device 4 or at a predetermined timing after the actuation of the first ignition device 4. The gas generator 100 can emit a large amount of combustion gas to the outside with various output profiles, as compared to a so-called single-type gas generator, by the combustion of the first gas generating agent 110 by the activation of the first ignition device 4 and the combustion of the second gas generating agent 120 by the activation of the second ignition device 7. 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 activating the second ignition device 7 when the impact is weak, or can simultaneously activate the first ignition device 4 and the second ignition device 7 when the impact is strong, depending on the impact detected by a sensor (not shown).

[0026] [Inner cylinder material] 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 cover wall portion 52 closing one end of the surrounding wall portion 51. The first ignition device 4 is fitted or press-fitted into the other end of the surrounding wall portion 51, thereby attaching the first inner cylinder member 5 to the bottom plate portion 32. 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 disposed so that the inner cylinder central axis A5 is spaced apart 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, the first ignition device 4 is surrounded by the surrounding wall portion 51, thereby forming an ignition means chamber 53 between the first inner cylinder member 5 and the first ignition device 4. The ignition means chamber 53 contains an enhancer charge 6 that burns when the first ignition device 4 is activated. The surrounding wall portion 51 of the first inner cylinder member 5 is formed with a plurality of communication holes h1 that communicate the internal space (i.e., the ignition means chamber 53) with the external space. The communication holes h1 are closed with a sealing tape (not shown) before the first ignition device 4 is activated. Instead of using a cover 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. The communication holes h1 are disposed at the same height (height from the bottom plate portion 32) as the gas discharge hole 12. However, the height of the communication holes h1 and the height of the gas discharge hole 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 cover wall portion 82 that closes one end of the surrounding wall portion 81. The second ignition device 7 is fitted or pressed into the other end of the surrounding wall portion 81, so that the second inner cylinder member 8 is attached to the bottom plate portion 32. As shown in FIG. 1, the second combustion chamber 20 is formed inside the second inner cylinder member 8, in which the second ignition device 7 and the second gas generating agent 120 that is burned by the operation of the second ignition device 7 are disposed. In addition, the surrounding wall portion 81 of the second inner cylinder member 8 is formed with a plurality of communication holes h2 that communicate the internal space (i.e., the second combustion chamber 20) with the external space (i.e., the first combustion chamber 10). The communication holes h2 are closed by a seal tape (not shown) before the second ignition device 7 is activated.

[0028] [filter] As shown in FIG. 1, the filter 9 is formed in a cylindrical shape, and is disposed in the first combustion chamber 10 so as to surround the first gas generating agent 110 and so that the gas discharge hole 12 is located outside of the filter 9 in the radial direction. In other words, the filter 9 is disposed between the first gas generating agent 110 and the gas discharge hole 12 so as to surround the first gas generating agent 110. The filter 9 is supported by having one end face (upper end face) of both end faces in the axial direction abut against the top plate portion 22 of the upper shell 2. , and the other end face (lower end face) is supported in contact with the bottom plate portion 32 of the lower shell 3. This filter 9 cools the combustion gas by removing heat from the combustion gas when the combustion gas of the first gas generating agent 110 and the second gas generating agent 120 passes through the filter 9. In addition to the function of cooling the combustion gas, the filter 9 also has a function of filtering the combustion gas by collecting combustion residues contained in the combustion gas.

[0029] [Explosive powder] As the enhancer charge 6, in addition to known black powder, a gas generating agent having good ignition properties and a higher combustion temperature than the first gas generating agent 110 can be used. The combustion temperature of the enhancer charge 6 can be set in the range of 1700 to 3000°C. As such an enhancer charge 6, for example, a known material containing nitroguanidine (34% by weight) or strontium nitrate (56% by weight) can be used. In addition, the enhancer charge 6 can be in various shapes, such as granular, pellet, cylindrical, or disk-like.

[0030] [Gas generator] A gas generating agent having a relatively low combustion temperature can be used for the first gas generating agent 110 and the second gas generating agent 120. 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. For such a first gas generating agent 110 and the second gas generating agent 120, for example, a known agent containing guanidine nitrate (41% by weight), basic copper nitrate (49% by weight), a binder, and an additive can be used. In addition, for the first gas generating agent 110 and the second gas generating agent 120, various shapes such as granular, pellet, cylindrical, and disk shapes can be adopted.

[0031] [Communication hole] Fig. 2 is a cross-sectional view taken along line AA in Fig. 1. Fig. 2 shows a cross section perpendicular to housing central axis A1 and inner cylinder central axis A5 of gas generator 100A before activation. For convenience, Fig. 2 omits illustration of first ignition device 4, second ignition device 7, joint portion 23, and joint portion 33. As shown in Fig. 2, an imaginary straight line passing through housing central axis A1 and inner cylinder central axis A5 when viewed in the axial direction of surrounding wall portion 51 is defined as an imaginary center line CL1.

[0032] As shown in FIG. 2, the plurality of communication holes h1 are arranged in a biased manner in the circumferential direction of the surrounding wall portion 51. Specifically, communication hole groups each consisting of three communication holes h1 adjacent to each other in the circumferential direction of the surrounding wall portion 51 are formed in two places in the surrounding wall portion 51. The two communication hole groups are respectively formed in positions that are symmetrical with respect to the imaginary 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 the circumferential direction into combustion product discharge regions R1a, R1b in which the plurality of communication holes h1 are arranged together, and combustion product non-discharge regions R2a, R2b excluding the combustion product discharge regions R1a, R1b. In other words, the combustion product discharge regions R1a, R1b are regions in which the communication holes are arranged, and the combustion product non-discharge regions R2a, R2b are regions in which the communication holes h1 are not arranged. The combustion product discharge regions R1a and R1b are located symmetrically with respect to the imaginary center line CL1. As shown in FIG. 2, in the axial view of the surrounding wall portion 51, a line passing from the inner cylinder central axis A5 through one end of the combustion product discharge region R1a in the circumferential direction and intersecting with the peripheral wall portion 11 is defined as a first imaginary line L1a, and a line passing from the inner cylinder central axis A5 through the other end of the combustion product discharge region R1a in the circumferential direction and intersecting with the peripheral wall portion 11 is defined as a second imaginary line L2a. Similarly, in the axial view of the surrounding wall portion 51, a line passing from the inner cylinder central axis A5 through one end of the combustion product discharge region R1b in the circumferential direction and intersecting with the peripheral wall portion 11 is defined as a first imaginary line L1b, and a line passing from the inner cylinder central axis A5 through the other end of the combustion product discharge region R1b in the circumferential direction and intersecting with the peripheral wall portion 11 is defined as a second imaginary line L2b. That is, the surrounding wall portion 51 is divided by the first imaginary straight line L1a, the second imaginary straight line L2a, the first imaginary straight line L1b, and the second imaginary straight line L2b. More specifically, in the surrounding wall portion 51, the region between the first imaginary straight line L1a and the second imaginary straight line L2a is the combustion product discharge region R1a. The area between the first virtual straight line L1b and the second virtual straight line L2b is the combustion product discharge area R1b, the area between the first virtual straight line L1a and the first virtual straight line L1b is the combustion product non-discharge area R2a, and the area between the second virtual straight line L2a and the second virtual straight line L2b is the combustion product non-discharge area R2b.

[0033] [Gas exhaust hole] 2, the peripheral wall portion 11 of the housing 1 is divided into communicating hole-corresponding regions R10a, R10b and communicating hole non-corresponding regions R20a, R20b by a first imaginary straight line L1a, a second imaginary straight line L2a, a first imaginary straight line L1b, and a second imaginary straight line L2b in the circumferential direction of the peripheral wall portion 11. When viewed in the axial direction of the surrounding wall portion 51, the first imaginary straight line L1a and the second imaginary straight line L2a define the range of the communicating hole-corresponding region R10a, the first imaginary straight line L1b and the second imaginary straight line L2b define the range of the communicating hole-corresponding region R10b, the first imaginary straight line L1a and the first imaginary straight line L1b define the range of the communicating hole non-corresponding region R20a, and the second imaginary straight line L2a and the second imaginary straight line L2b define the range of the communicating hole non-corresponding region R20b. 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 faces the communicating hole corresponding region R10a, the combustion product discharge region R1b faces the communicating hole corresponding region R10b, the combustion product non-discharge region R2a faces the communicating hole non-corresponding region R20a, and the combustion product non-discharge region R2b faces the communicating hole non-corresponding region R20b. That is, in gas generator 100, the combustion product discharge region R1a is associated with the communicating hole corresponding region R10a, the combustion product discharge region R1b is associated with the communicating hole corresponding region R10b, the combustion product non-discharge region R2a is associated with the communicating hole non-corresponding region R20a, and the combustion product non-discharge region R2b is associated with the communicating hole non-corresponding region R20b.

[0034] As shown in FIG. 2, the 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. In other words, 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) of each of the second gas discharge holes 12b is made smaller than the cross-sectional area (hole diameter) of each of the first gas discharge holes 12a. When the first gas generating agent 110 and the second gas generating agent 120 are burned, a load is applied to the seal tape 13 due to the pressure of the combustion gas. At this time, because the cross-sectional area of ​​each second gas exhaust hole 12b is smaller than the cross-sectional area of ​​each first gas exhaust hole 12a, the load acting on the portion blocking second gas exhaust hole 12b in sealing tape 13 is smaller than the load acting on the portion blocking first gas exhaust hole 12a. As a result, the opening pressure of second gas exhaust hole 12b is higher than that of first gas exhaust hole 12a, making it more difficult to open.

[0035] 2, of 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. In other words, the communication-hole corresponding regions R10a and R10b facing the combustion product discharge regions R1a and R1b in which the communication holes h1 are arranged do not have the second gas discharge holes 12b with a high opening pressure, and only the first gas discharge holes 12a with a low opening pressure are formed.

[0036] [Operation] Hereinafter, a basic operation of the gas generator 100 according to the first embodiment will be described with reference to Fig. 1. In this example, a case will be described in which the second ignition device 7 is activated with a delay from the first ignition device 4 (i.e., after the first ignition device 4 is activated).

[0037] When a sensor (not shown) detects an impact, an ignition current is supplied to the first igniter 41 of the first ignition device 4, and the first igniter 41 is activated. Then, the ignition charge housed in the first igniter 41 burns, and the combustion products such as flame and high-temperature gas 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 blocking 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 arranged 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. The combustion gas is cooled and combustion residue is collected by passing through the filter 9. The combustion gas of the first gas generating agent 110 cooled and filtered by the filter 9 breaks the seal tape 13 that has been blocking 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 is activated, the second gas generating agent 120 accommodated in the second combustion chamber 20 is combusted, generating combustion gas within the second combustion chamber 20. When the sealing tape blocking 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 through the communication hole h2 to the first combustion chamber 10. The combustion gas of the second gas generating agent 120 is cooled and filtered by the filter 9, and then discharged to the outside of the housing 1 from the gas discharge hole 12.

[0039] The combustion gas of the first gas generating agent 110 and the second gas generating agent 120 flows into an airbag (not shown) after being discharged to the outside of the housing 1. When the airbag inflates, a cushion is formed between the occupant and a hard structure, protecting the occupant from an impact.

[0040] [Regarding the correspondence between communication holes and gas exhaust holes] In general, the combustion performance of a gas generating agent tends to improve as the temperature or pressure around the gas generating agent increases. In other words, in a low temperature and low pressure environment, the combustion of the gas generating agent becomes sluggish. Therefore, in order to reduce the difference in output performance of the gas generator between operation at high temperature (hereinafter, high temperature operation) and operation at low temperature (hereinafter, low temperature operation) and to realize stabilization of the output performance, it is necessary to increase the internal pressure of the housing during low temperature operation and increase the combustion performance of the gas generating agent. 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, the internal pressure of the housing during low temperature operation can be increased and the difference in combustion performance of the gas generating agent during low temperature operation and high temperature operation can be reduced. This will be described in detail 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, a cross section corresponding to FIG. 2 is illustrated. As shown in FIGS. 3 and 4, the gas generator 100 is configured such that, during low-temperature operation, only the first gas discharge hole 12a, which has a low opening pressure among the multiple gas discharge holes 12, is opened, and during high-temperature operation, the first gas discharge hole 12a and the second gas discharge hole 12b, which has a high opening pressure, are also opened. In the gas generator 100, by opening only the first gas discharge hole 12a during low-temperature operation, the combustion gas is discharged from the first gas discharge hole 12a, but compared to the case where all the gas discharge holes 12 are opened at the same temperature, the combustion gas is more likely to be trapped inside the housing 1 (first combustion chamber 10). This increases the internal pressure of the housing 1 during low-temperature operation, improving the combustion performance of the gas generating agent. On the other hand, during high temperature operation when the combustion performance of the gas generating agent is expected to be high from the beginning, both the first gas discharge hole 12a and the second gas discharge hole 12b are opened to discharge the combustion gas, thereby preventing the internal pressure of the housing 1 from increasing excessively. By improving the combustion performance of the gas generating agent during high temperature operation and low temperature operation, the difference in output performance of the gas generator during high temperature operation and low temperature operation is reduced, thereby achieving stabilization of output performance.

[0042] Here, the arrows indicated by the symbol F1 in Fig. 3 and Fig. 4 indicate the traveling direction of the combustion products discharged from the communication hole h1. As shown in Fig. 3 and Fig. 4, the combustion products discharged from the ignition means chamber 53 through the communication hole 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, R10b, which are regions facing the combustion product discharge regions R1a, R1b in the radial direction centered on the inner cylinder central axis A5. Therefore, the first gas generating agents 110 arranged in the first combustion chamber 10 are ignited in order from those arranged on the combustion product discharge regions R1a, R1b side to the communication hole corresponding regions R10a, R10b side. As a result, most of the combustion gas of the first gas generating agent 110 flows radially from the combustion product discharge regions R1a, R1b side and collides with the communication hole corresponding regions R10a, R10b.

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

[0044] In contrast to this, in the gas generator 100, the first gas discharge hole 12a is formed only in the communication hole corresponding regions R10a, R10b that face the combustion product discharge regions R1a, R1b of the peripheral wall portion 11, and the second gas discharge hole 12b is formed only in the communication hole non-corresponding regions R20a, R20b that do not face the combustion product discharge regions R1a, R1b. Therefore, during low temperature operation, the first gas discharge hole 12a is more easily opened, and the second gas discharge hole 12b is more difficult to open. Therefore, during low temperature operation, of the first gas discharge hole 12a and the second gas discharge hole 12b, only the first gas discharge hole 12a can be more reliably opened. This makes it possible to reliably increase the internal pressure of the housing and the combustion performance of the gas generating agent during low temperature operation. As a result, the difference in output performance of the gas generator 100 during low temperature operation and high temperature operation can be reduced, and the output performance can be stabilized.

[0045] [Actions and Effects] As described above, in the gas generator 100, the multiple gas discharge holes 12 include the first gas discharge hole 12a and the second gas discharge hole 12b having a higher opening pressure than the first gas discharge hole 12a, and 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, R1b in which the multiple communicating holes h1 are arranged together, and combustion product non-discharge regions R2a, R2b excluding the combustion product discharge regions R1a, 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, R10b corresponding to the combustion product discharge regions R1a, R1b and communication hole non-corresponding regions R20a, R20b corresponding to the combustion product non-discharge regions R2a, R2b, with the first gas discharge holes 12a being formed only in the communication hole corresponding regions R10a, R10b and the second gas discharge holes 12b being formed only in the communication hole non-corresponding regions R20a, R20b. According to such a gas generator 100, by forming the first gas discharge holes 12a only in the communication hole corresponding regions R10a, R10b, it becomes easier to open the first gas discharge holes 12a, and by forming the second gas discharge holes 12b only in the communication hole non-corresponding regions R20a, R20b, it becomes more difficult to open the second gas discharge holes 12b. This makes it possible to more reliably open only first gas discharge hole 12a during low temperature operation. As a result, according to 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] Furthermore, in the gas generator 100, the first gas discharge hole 12a and the second gas discharge hole 12b are arranged in separate regions (communication hole corresponding regions R10a, R10b and communication hole non-corresponding regions R20a, R20b) in the peripheral wall portion 11. Therefore, the second gas discharge hole 12b is less susceptible to the influence of the combustion gas flowing to the first gas discharge hole 12a. This makes it possible to make the second gas discharge hole 12b less likely to open during low temperature operation. Note that, in the circumferential direction of the peripheral wall portion 11, the distance between adjacent first gas discharge holes 12a and second gas discharge holes 12b may be set to be larger than the distance between adjacent first gas discharge holes 12a in the communication hole corresponding regions R10a, R10b or the distance between adjacent second gas discharge holes 12b in the communication hole non-corresponding regions R20a, R20b.

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

[0048] Furthermore, in gas generator 100, the ranges of communication hole corresponding regions R10a, R10b are defined by first imaginary straight lines L1a, L1b and second imaginary straight lines L2a, L2b when viewed in the axial direction of surrounding wall portion 51. As a result, the communication hole corresponding regions R10a, R10b are defined as regions facing 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, and the housing central axis A1, which is the central axis of the peripheral wall portion 11, are separated from each other. That is, the first inner cylinder member 5 is disposed eccentrically with respect to the center of the housing 1. Furthermore, the surrounding wall portion 51 includes combustion product discharge regions R1a and R1b, which are positioned line-symmetrically with each other with the imaginary center line CL1 as the axis of symmetry when viewed in the axial direction. Furthermore, the peripheral wall portion 11 includes a communication hole corresponding region R10a corresponding to the combustion product discharge region R1a and a communication hole corresponding region R10b corresponding to the combustion product discharge region R1b. Furthermore, the communication hole h1 is formed in the combustion product discharge regions R1a and R1b so as to be arranged line-symmetrically with the imaginary center line CL1 as the axis of symmetry, and the first gas discharge hole 12a is formed in the communication hole corresponding regions R10a and R10b so as to be arranged line-symmetrically with the imaginary center line CL1 as the axis of symmetry. That is, in gas generator 100, the arrangement of communication hole h1 and first gas discharge hole 12a is line symmetrical with respect to imaginary center line CL1. As a result, communication hole corresponding region R10a and communication hole corresponding region R10b are positioned line symmetrically, so that when only first gas discharge hole 12a is open during low temperature operation, the thrust of the combustion gas discharged from first gas discharge hole 12a in communication hole corresponding region R10a and the thrust of the combustion gas discharged from first gas discharge hole 12a in communication hole corresponding region R10b are offset. As a result, the balance of gas generator 100 during operation is stable.

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

[0051] 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] 2 to 4, the second inner cylinder member 8, which forms the second gas generating agent 120 therein, is disposed so as not to be located between the combustion product discharge region R1a and the communicating hole corresponding region R10a or between the combustion product discharge region R1b and the communicating hole corresponding region R10b in the radial direction centered on the inner cylinder central axis A5. In other words, the second inner cylinder member 8 is disposed at a position that does not obstruct the flow of the combustion gas of the first gas generating agent 110 from the combustion product discharge regions R1a, R1b side toward the communicating hole corresponding regions R10a, R10b side. This makes it possible to more reliably open the first gas discharge holes 12a formed in the communicating hole corresponding regions R10a, R10b.

[0053] In this embodiment, the opening pressure of the first gas exhaust hole 12a and the second gas exhaust hole 12b is made different by making the cross-sectional area (hole diameter) of each of the first gas exhaust hole 12a and the second gas exhaust hole 12b different, but the present disclosure is not limited to this. For example, the strength of the blocking member blocking the gas exhaust hole may be partially adjusted to make the strength of the portion blocking the second gas exhaust hole higher than the strength of the portion blocking the first gas exhaust hole, thereby making the opening pressure of the second gas exhaust hole higher than the opening pressure of the first gas exhaust hole. Also, the opening pressure may be adjusted by both the hole diameter of each gas exhaust hole and the strength of the blocking member blocking it. The strength of the blocking member may be, for example, the material of the blocking member or the thickness including the overlapping.

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

[0055] Furthermore, in this example, the transfer charge 6 is accommodated in the ignition means chamber 53, but the gas generator of the present disclosure may be configured to ignite the first gas generating agent by increasing the type and amount of ignition charge in the first igniter 41 without using the transfer charge 6. In other words, the gas generator according to the present disclosure may be configured to discharge combustion products from the ignition means chamber through a communication hole upon activation of the first ignition device, and the "combustion products" discharged from the communication hole to ignite the first gas generating agent in the present disclosure are not limited to combustion products of the transfer charge, and may be combustion products of the ignition charge. Furthermore, a transfer charge integrated with the first igniter 41 may be used as the first ignition device.

[0056] [Modification of the first embodiment] The following describes a gas generator according to a modification of embodiment 1. In the description of the modification, differences from gas generator 100 described in Fig. 1 to Fig. 4 will be mainly described, and the same reference numerals will be used to denote the same points as in gas generator 100, and detailed description thereof will be omitted.

[0057] [Modification 1 of the first embodiment] Fig. 5 is a cross-sectional view of gas generator 100A according to Modification 1 of Embodiment 1. Fig. 5 shows a state before gas generator 100A is activated. Fig. 6 is a perspective view of a first inner cylinder member 5A according to Modification 1 of Embodiment 1. As shown in Figs. 5 and 6, gas generator 100A In the embodiment, 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 either the combustion product discharge region R1a or the combustion product discharge region R1b.

[0058] As with gas generator 100 described above, gas generator 100A shown in Fig. 5 can also achieve stabilization of output performance. Furthermore, according to gas generator 100A, since communication hole h1A is formed in the entire area of ​​combustion product discharge regions R1a, R1b, combustion products radially discharged from ignition means chamber 53 through communication hole h1A are discharged evenly toward the entire area of ​​communication hole corresponding regions R10a, R10b facing combustion product discharge regions R1a, R1b. This allows combustion gas from first gas generating agent 110 to collide uniformly against communication hole corresponding regions R10a, R10b, and first gas discharge holes 12a formed in communication hole corresponding regions R10a, R10b can be more reliably opened.

[0059] [Modification 2 of the first embodiment] FIG. 7 is a transverse sectional view of gas generator 100B according to modified example 2 of embodiment 1. FIG. 7 shows a state before activation of gas generator 100B. As shown in FIG. 7, gas generator 100B differs from gas generator 100 in that it does not have a combustion product discharge region R1b and a communication hole corresponding region R10b corresponding thereto. That is, in gas generator 100B, communication hole h1 and gas discharge hole 12 are arranged asymmetrically when imaginary center line CL1 is taken as the axis of symmetry. As exemplified by gas generator 100B, in the gas generator according to the present disclosure, the communication holes and gas discharge holes do not have to be arranged so as to be positioned line-symmetrically with respect to each other with the imaginary center line as the axis of symmetry. Gas generator 100A shown in FIG. 7 can also achieve stabilization of output performance, similar to gas generator 100 described above.

[0060] <Embodiment 2> Hereinafter, a gas generator according to embodiment 2 will be described focusing on the differences from gas generator 100, and detailed description of the same points as those in gas generator 100 will be omitted by using the same reference numerals. Fig. 8 is a vertical sectional view of gas generator 200 according to embodiment 2. Fig. 9 is a sectional view taken along line BB in Fig. 8. Figs. 8 and 9 show a state before gas generator 200 is activated.

[0061] As shown in Figures 8 and 9, gas generator 200 according to the second embodiment differs from gas generator 100 according to the first embodiment in that it does not include a second ignition device 7, a second inner cylindrical member 8, a second gas generating agent 120, and a second combustion chamber 20. In other words, gas generator 200 is configured as a so-called single-type gas generator that includes only one ignition device, the position of which is offset from the housing central axis A1. Gas generator 200 shown in Figures 8 and 9 can also achieve stabilization of output performance, similar to gas generator 100 according to the first embodiment.

[0062] [Modification 1 of the second embodiment] Fig. 10 is a transverse sectional view of gas generator 200A according to modified example 1 of embodiment 2. Fig. 10 shows a state before gas generator 200A is activated. As shown in Fig. 10, gas generator 200A differs from gas generator 200 in that an inner cylinder central axis A5 and a housing central axis A1 coincide with each other, that is, gas generator 200A is a single type in which first inner cylinder member 5 is disposed in the center of housing 1 and there is no member associated with the second combustion chamber. Gas generator 200A shown in Fig. 10 can also achieve stabilization of output performance, similar to gas generator 100 according to embodiment 1.

[0063] 10, the gas generator 200A is formed point-symmetrically when viewed in the axial direction. Specifically, the combustion product discharge region R1a and the combustion product discharge region R1b are positioned point-symmetrically with respect to the housing central axis A1 (the inner cylinder central axis A5). The through hole corresponding region R10a and the communication hole corresponding region R10b are located in point symmetry with respect to each other with the housing central axis A1 as the center of symmetry. Furthermore, the communication hole h1 is formed in the combustion product discharge regions R1a, R1b so as to be arranged in point symmetry with the housing central axis A1 as the center of symmetry, and the first gas discharge hole 12a is formed in the communication hole corresponding regions R10a, R10b so as to be arranged in point symmetry with respect to 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 located in point symmetry, 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 of the communication hole corresponding region R10a and the thrust of the combustion gas discharged from the first gas discharge hole 12a of the communication hole corresponding region R10b are offset. As a result, the balance of the gas generator 100 during operation is stable.

[0064] <Other> Although the preferred embodiments of the present disclosure have been described above, each aspect disclosed in this specification can be combined with any other feature disclosed in this specification. [Explanation of symbols]

[0065] 100,200 Gas generator 1. Housing 11 Peripheral wall section 12 Gas exhaust hole 12a First gas exhaust hole 12b First gas exhaust hole 4 1st ignition device 5 First inner cylinder member 51 Enclosure Wall 53 Ignition means chamber 6. Transfer Charge 7 Second ignition device 8 Second inner cylinder member 10 First combustion chamber 20 Second combustion chamber 110 First Gas Generator 120 Secondary Gas Generator h1 communication hole A1 Housing center axis A5 Inner cylinder center axis R1a, R1b Combustion product discharge area R2a, R2b Combustion product non-emission area R10a, R10b communicating hole corresponding area R20a, R20b Non-compatible area with connecting holes

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 on one end side of the peripheral wall portion, and a bottom plate portion provided on the other end side of the peripheral wall portion so as to face the top plate portion, the bottom plate portion defining the first combustion chamber together with the peripheral wall portion and the top plate portion, and the first ignition device being fixed thereto; 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, the first inner cylinder member having one or more communication holes formed in the surrounding wall portion that communicate the ignition means chamber with an outside of the first inner cylinder member; a first gas generating agent that is disposed in the first combustion chamber so as to surround the surrounding wall portion and that is combusted by combustion products discharged from the ignition means chamber through the communication hole upon activation of the first ignition device; a plurality of gas exhaust holes formed in the housing and opening when subjected to a combustion pressure of a gas generating agent to communicate the first combustion chamber with the outside of the housing; Equipped with the plurality of gas exhaust holes include a first gas exhaust hole and a second gas exhaust hole having an opening pressure higher than that of the first gas exhaust hole, The surrounding wall portion is divided in a circumferential direction of the surrounding wall portion into a combustion product discharge region in which one of the communication holes is arranged or in which a plurality of the communication holes are arranged together, and a combustion product non-discharge region excluding the combustion product discharge region, The peripheral wall portion is divided in a circumferential direction of the peripheral wall portion into a communication hole corresponding region corresponding to the combustion product discharge region and a communication hole non-corresponding region corresponding to the combustion product non-discharge region, the first gas discharge hole is formed only in the communication hole corresponding region and the communication hole non-corresponding region, and the second gas discharge hole is formed only in the communication hole non-corresponding region. Gas generator.

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

2. The gas generator according to claim 1.

3. The range of the communication hole corresponding region is defined, when viewed in the axial direction of the surrounding wall portion, by a first imaginary line extending from a central axis of the surrounding wall portion through one end of the combustion product discharge region in the circumferential direction of the surrounding wall portion and intersecting with the surrounding wall portion, and a second imaginary line extending from the central axis of the surrounding wall portion through the other end of the combustion product discharge region in the circumferential direction of the surrounding wall portion and intersecting with the surrounding wall portion.

3. A 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 spaced apart from each other, the surrounding wall portion includes a first combustion product discharge region and a second combustion product discharge region, which are the combustion product discharge regions located in line symmetry with each other with respect to a virtual center line passing through a central axis of the surrounding wall portion and a central axis of the peripheral wall portion when viewed in the axial direction of the surrounding wall portion, the peripheral wall portion includes a first communication hole corresponding region that is the communication hole corresponding region corresponding to the first combustion product discharge region, and a second communication hole corresponding region that is the communication hole corresponding region corresponding to the second combustion product discharge region, The first combustion product discharge region and the second combustion product discharge region are formed with the communication holes so as to be arranged symmetrically with respect to the imaginary center line, The first communication hole corresponding region and the second communication hole corresponding region are symmetrical about the virtual center line. The first gas exhaust holes are formed so as to be arranged in line symmetry with respect to the first gas exhaust hole. A gas generator according to any one of claims 1 to 3.

5. an opening pressure of the first gas discharge hole formed in the first communication hole corresponding region and an opening pressure of the first gas discharge hole formed in the second communication hole corresponding region are equal to each other; 5. The gas generator according to claim 4.

6. A second ignition device; a second gas generating agent that is combusted by activation of the second ignition device; a second combustion chamber in which the second ignition device and the second gas generating agent are disposed; a cylindrical second inner cylinder member disposed in the housing and defining the second combustion chamber therein; the second inner cylinder member is disposed so as not to be located between the combustion product discharge region and the communication hole corresponding region in a radial direction centered on a central axis of the surrounding wall portion. A 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. A gas generator according to any one of claims 1 to 6.

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