JP7630399B2 - Gas generator and gas exhaust method - Google Patents

Description

The present invention relates to a gas generator and a gas discharge method.

Conventionally, a gas generator has been proposed that includes a long cylindrical metal housing body, a metal holder to which an igniter is attached, and a bottomed cylindrical storage chamber defining member that defines a gas generating agent storage chamber in which a gas generating agent is stored (for example, Patent Document 1). In this technology, when gas generated by combustion of the gas generating agent passes through this filter, it functions as a cooling means that cools the gas by removing the high temperature heat of the gas, and also functions as a removal means that removes slag (residue) contained in the gas. In addition, a plurality of gas outlets are provided along the circumferential and axial directions in the housing body part that defines the filter chamber. The gas outlets direct the gas after passing through the filter to the outside of the housing.

A cylinder-type gas generator has also been proposed that includes a housing including a long, bottomed, cylindrical first housing member, an igniter, a partition plate, a partition member, a transfer charge, a gas generating agent, and a filter (for example, Patent Document 2). The partition member is a bottomed, cylindrical member disposed in the working gas generation chamber, and has a cylindrical portion, a bottom portion, a first communication hole, and a hollow portion. The gas generating agent is contained in the working gas generation chamber except for the hollow portion. In addition, it is said that a force directed radially outward of the housing is applied to the partition plate due to the internal pressure during operation, suppressing the movement of the partition plate.

JP 2017-193192 A JP 2010-260387 A

Generally, the output of a gas generator changes depending on the environmental temperature when it is activated. In other words, as the environmental temperature rises, the combustion speed of the gas generating agent increases, and even with gas generators of the same specifications, the temperature of the combustion gas output during activation tends to be higher in a high-temperature environment.

The technology disclosed herein provides a technology for reducing the difference in output caused by differences in environmental temperature in a gas generator.

In addition, if a gap occurs between the filter and the housing in a gas generator, there is a risk of a short pass occurring, in which the generated combustion gas is discharged from the gas exhaust hole of the housing without passing through the filter. In addition, the occurrence of a short pass can be prevented, for example, by performing full circumference welding without any gaps, but this requires a lot of time and effort in the manufacturing process. Therefore, the technology disclosed herein may have the objective of suppressing the occurrence of a short pass with a simple configuration instead of or in addition to the above objective.

The gas generator of the present disclosure comprises: a housing extending from one end side to the other end side forming an outer shell container; an ignition device attached to the housing; a combustion chamber formed inside the housing and accommodating a gas generating agent to be ignited by the ignition device; a cup-shaped diffuser section provided on the other end side of the housing and including a closed end with a closed end and a side wall having a plurality of gas discharge holes; a filter at least a portion of which is accommodated inside the diffuser section, the filter having a hollow flow path therein extending from the combustion chamber side to the closed end side, the flow path including a first section having one end connected to the combustion chamber and a second section connected to the other end of the first section; and a blocking section that closes the section between the first section and the second section when the combustion pressure of the gas generating agent during operation is less than a predetermined critical threshold value, and opens the first section and the second section when the combustion pressure is equal to or greater than the critical threshold value. In addition, the side wall of the diffuser section includes a first side wall region located around the first section and a second side wall region located around the second section, and one or more gas exhaust holes are provided in each of the first side wall region and the second side wall region.

In the gas generator of the present disclosure, the blocking section can switch between a closed state and a communicating state between the first section and the second section in the filter depending on the internal pressure of the combustion chamber. In addition, the diffuser section has one or more gas exhaust holes in each of the first side wall region located around the first section and the second side wall region located around the second section. Therefore, depending on the internal pressure of the combustion chamber, the part of the filter through which the combustion gas discharged from the gas exhaust hole passes can be switched. When the combustion pressure of the gas generating agent during operation is less than a predetermined critical threshold, the blocking section blocks the area between the first section and the second section, and when the combustion pressure is equal to or greater than the critical threshold, the blocking section connects the first section and the second section. Therefore, when the environmental temperature is high and the internal pressure of the combustion chamber is high, the area of the filter through which the combustion gas flows can be increased, and the cooling efficiency can be improved. On the other hand, when the environmental temperature is low and the internal pressure of the combustion chamber is low, the area of the filter through which the combustion gas flows is reduced, suppressing cooling. The output of a gas generator is affected by the ambient temperature, but the gas generator disclosed herein can reduce the difference in output caused by differences in ambient temperature.

The filter may have an inner diameter of the second section smaller than the inner diameter of the first section, a step at the boundary between the first and second sections, and the blocking section may include a cleavage section that blocks the space between the combustion chamber and the first section before activation, has a diameter equal to or smaller than the inner diameter of the first section and larger than the inner diameter of the second section, and is formed to be punched by a pressure equal to or greater than an activation threshold value that is smaller than a critical threshold value. When the combustion pressure is equal to or greater than the activation threshold value and less than the critical threshold value, the cleavage section is punched by the combustion pressure and moves to the step section, thereby blocking the space between the first and second sections, and when the combustion pressure further reaches or exceeds the critical threshold value, at least a portion of the cleavage section moves over the step section to the second section by the combustion pressure, thereby connecting the first and second sections.

The filter may have an inner diameter of the second section smaller than the inner diameter of the first section, a step at the boundary between the first and second sections, the blocking section includes a cleavage section that blocks the space between the combustion chamber and the first section before activation, the diameter of which is equal to or smaller than the inner diameter of the first section and larger than the inner diameter of the second section, and is formed to be punched at a pressure equal to or greater than an activation threshold value that is smaller than a critical threshold value, the cleavage section has a through hole and a sealing member that closes the through hole and cleaves at a pressure equal to or greater than the critical threshold value, and when the combustion pressure is equal to or greater than the activation threshold value and less than the critical threshold value, the cleavage section is punched by the combustion pressure and moves to the step section, thereby blocking the space between the first and second sections, and when the combustion pressure further reaches or exceeds the critical threshold value, the sealing member is cleaved by the combustion pressure to open the through hole, thereby establishing communication between the first and second sections.

The blocking section may also include a first blocking member that blocks the space between the combustion chamber and the first section before activation, and communicates between the combustion chamber and the first section when the combustion pressure is equal to or greater than an activation threshold that is smaller than a critical threshold, and less than the critical threshold, and a second blocking member that blocks the space between the first section and the second section before activation, and communicates between the first section and the second section when the combustion pressure is equal to or greater than the critical threshold.

In addition, the blocking portion may include a sealing member that blocks the gas exhaust hole provided in the first sidewall region before activation and ruptures when the combustion pressure is equal to or greater than an activation threshold value that is smaller than a critical threshold value and is less than the critical threshold value, and a blocking member that blocks the space between the first section and the second section before activation and connects the first section and the second section when the combustion pressure is equal to or greater than the critical threshold value.

The blocking portion may also be provided with a weakened portion that is thinned to conform to the shape of the tearing portion. This makes it easier to punch out the tearing portion as intended.

The total opening area of the gas exhaust holes provided in the second sidewall region may be larger than the total opening area of the gas exhaust holes provided in the first sidewall region. When the gas generator has multiple gas exhaust holes, the amount of combustion gas discharged per unit time from each of the gas exhaust holes varies depending on the area of the gas exhaust hole. By increasing the total opening area of the gas exhaust holes provided around the radial periphery of the second section located on the closed end side of the diffuser section, a large amount of combustion gas can be circulated through the part of the filter on the closed end side of the diffuser section, and the cooling efficiency of the entire combustion gas discharged from the gas exhaust holes can be improved.

The gas discharge method according to the present disclosure also includes supplying an ignition current to ignite the ignition device and burn the gas generating agent, and closing the first section and the second section with a blocking section when the combustion pressure is less than a predetermined critical threshold, and opening the first section and the second section when the combustion pressure is equal to or greater than the critical threshold.

The gas generator of the present disclosure in accordance with another aspect includes a cylindrical housing that forms an outer shell container and extends from one end to the other end, an ignition device attached to the housing, a combustion chamber formed inside the housing and containing a gas generating agent that is ignited by the ignition device, a cylindrical diffuser portion that is inserted into one end of the housing and has a gas exhaust hole, a main body portion that is contained in the diffuser portion, and a filter having a flange portion that protrudes radially outward from the inner circumference of the diffuser portion at the housing side end of the main body portion, and a first annular surface of the surface of the flange portion that faces the main body portion abuts against the housing side end of the diffuser portion.

The flange portion of the filter is abutted against the end of the diffuser portion inserted into the housing, so the gap between the diffuser portion and the filter can be blocked. This prevents the combustion gas generated by the gas generating agent from passing between the diffuser portion and the filter and being discharged from the gas exhaust hole without passing through the filter. In other words, the occurrence of short passes can be suppressed with a simple configuration.

The flange portion may have a second annular surface facing the rear side of the first annular surface and an annular circumferential surface connecting the first and second annular surfaces, and the annular circumferential surface may abut against the inner circumference of the housing. By abutting the annular circumferential surface of the flange portion against the inner circumference of the housing, it is possible to prevent short-passing of the combustion gas and suppress the combustion gas from being discharged from the gas exhaust hole without passing through the filter.

The main body of the filter may have a recess extending from the housing side along the axial direction of the diffuser, and the housing may include an orifice plate inside that divides the combustion chamber from the recess and has a through hole that connects the combustion chamber to the recess. The combustion chamber and the filter may be divided in this manner, for example.

The outer diameter of the orifice plate may be smaller than the outer diameter of the flange portion, and the outer periphery of the second annular surface of the flange portion may be exposed to the housing side. In this way, the combustion gas can be introduced into the filter from the outer periphery of the flange portion as well.

The diffuser portion may have a closed end on the opposite side to the housing, the filter may abut against the closed end, the recess of the filter may be a through hole, and the filter may be thicker on the closed end side than on the housing side. The combustion gas that collides with the closed end of the diffuser portion passes through a filter located nearby and is discharged from a gas discharge hole. In particular, a relatively large amount of the combustion gas whose flow rate has increased after passing through the orifice plate reaches the closed end of the diffuser portion, passes through a filter located nearby, and is discharged from a gas discharge hole. By increasing the thickness of the filter on the closed end side as described above, the cooling performance on the closed end side of the filter can be improved.

The ignition device is attached to the other end of the housing, and is provided with a retainer that divides the space in which the ignition device is disposed from the combustion chamber and has an opening, and holds the gas generating agent within the combustion chamber. The retainer may have a flat plate portion that supports the gas generating agent and a connection portion that is provided on the outer periphery of the flat plate portion and abuts against the inner periphery of the housing, and may have a through hole on the periphery of the flat plate portion. A gap that extends relatively linearly toward the diffuser portion is formed between the gas generating agent and the inner periphery of the housing, and the combustion gas that passes through the through hole provided on the periphery of the flat plate portion is easily able to flow in the axial direction of the housing along the inner periphery of the housing.

The ignition device is attached to the other end side of the housing, and is provided with a retainer that divides the space in which the ignition device is disposed from the combustion chamber and has an opening, and holds the gas generating agent in the combustion chamber. The retainer may have a flat plate portion that supports the gas generating agent, a step portion that is provided along the outer periphery of the flat plate portion and spaced apart from the inner periphery of the housing, and a connection portion that abuts against the inner periphery of the housing, and may have a through hole in the step portion. A gap that extends relatively linearly toward the diffuser portion is formed between the gas generating agent and the inner periphery of the housing, and the combustion gas that passes through the through hole provided in the step portion of the retainer provided along the outer periphery of the flat plate portion passes through the retainer toward the inner periphery of the housing, and is more likely to flow in the axial direction of the housing along the inner periphery of the housing.

The ignition device is attached to the other end side of the housing, and is provided with a retainer that divides the space in which the ignition device is disposed from the combustion chamber and has an opening, and holds the gas generating agent in the combustion chamber. The retainer has an outer diameter smaller than the inner diameter of the housing, and has a flat plate portion that supports the gas generating agent, a connection portion that abuts against the inner circumference of the housing, and an annular inclined surface that is tapered from the outer periphery of the flat plate portion to the connection portion, and may have a through hole in the annular inclined surface. A gap that extends relatively linearly toward the diffuser portion is formed between the gas generating agent and the inner circumference of the housing, and the combustion gas that passes through the through hole provided in the annular peripheral surface that is tapered from the outer periphery of the flat plate portion passes through the retainer toward the inner circumference of the housing, and is easily allowed to flow in the axial direction of the housing along the inner circumference of the housing.

This disclosure provides a technology for reducing the difference in output caused by differences in environmental temperature in a gas generator.

FIG. 1 is a schematic axial cross-sectional view showing an example of a gas generator according to an embodiment. FIG. 2 is a partial cross-sectional view showing the diffuser portion and its surroundings. FIG. 3 is a plan view of the blocking member as viewed from the diffuser portion side. FIG. 4 is a partial cross-sectional view showing an example of a state in which the blocking member is torn open and the first portion is moved. FIG. 5 is a partial cross-sectional view showing an example of a state in which the first portion of the blocking member is further cleaved. FIG. 6 is a diagram showing a schematic diagram of the flow of combustion gas in the example of FIG. FIG. 7 is a diagram showing a schematic diagram of the flow of combustion gas in the example of FIG. FIG. 8 is a schematic partial axial cross-sectional view showing an example of a gas generator according to the second embodiment. FIG. 9 is a partial cross-sectional view showing an example of a state in which the blocking portion is cleaved and the first portion is moved. FIG. 10 is a partial cross-sectional view showing an example of a state in which the sealing tape is further torn. FIG. 11 is a schematic partial axial cross-sectional view showing an example of a gas generator according to the third embodiment. FIG. 12 is a schematic partial axial cross-sectional view showing an example of a gas generator according to the fourth embodiment. FIG. 13 is a schematic axial cross-sectional view showing an example of a gas generation device according to another embodiment. FIG. 14 is a partial cross-sectional view showing the diffuser portion and its surroundings. FIG. 15 is a schematic diagram for explaining the movement path of the combustion gas in the diffuser portion. FIG. 16 is a schematic diagram for explaining the movement path of the combustion gas in the combustion chamber. FIG. 17 is a schematic axial cross-sectional view showing an example of a gas generation device according to the sixth embodiment, which is a modification of the fifth embodiment. FIG. 18 is a schematic axial cross-sectional view showing an example of a gas generation device according to the seventh embodiment, which is a modification of the fifth embodiment.

Embodiments of the present disclosure will be described below with reference to the drawings. Note that each configuration and combination of configurations in each embodiment is merely an example, and additions, omissions, substitutions, and other modifications of configurations are possible as appropriate without departing from the spirit of the present invention. The present disclosure is not limited to the embodiments, but is limited only by the claims.

<Embodiment 1>
Fig. 1 is a schematic axial cross-sectional view showing an example of a gas generator according to this embodiment. The gas generator 1 can be used as a gas generating device for inflating an airbag, for example. The gas generator 1 in Fig. 1 includes a cylindrical housing 2, an ignition device 3 attached to one axial end side of the housing 2, and a diffuser portion 4 formed on the other end side of the housing 2.

The ignition device 3 is a device that is ignited by an ignition current, and is the same as that used in known gas generators. For example, the ignition device 3 has a metal cup body 31 that contains an ignition charge and is sealed, and a pair of conductive pins 32, 32 for receiving a current supply from the outside, which are fixed to a metal igniter holder 33 with a resin member 34. The igniter holder 33 of the ignition device 3 is attached to an opening on one end side of the housing 2 in the axial direction, for example, by full circumference welding. Full circumference welding is a ring-shaped welding that continues in the circumferential direction, and refers to a state in which the space between the two members to be welded is sealed without any gaps.

The housing 2 is, for example, a cylindrical member with a substantially uniform inner and outer diameter, and forms the outer shell of the gas generator 1. The material of the housing 2 is, for example, a metal. A cup-shaped partition wall 5 is disposed inside the housing 2 at a predetermined distance from the ignition device 3.

In other words, the partition wall 5 is a bottomed cylindrical member, and the side includes a large diameter portion 51 having a large diameter and a small diameter portion 52 having a small diameter. The outer diameter of the large diameter portion 51 of the partition wall 5 is approximately the same as the inner diameter of the housing 2. Therefore, the housing 2 can accommodate the partition wall 5 so that the bottom portion 53 is located on the diffuser portion 4 side. The housing 2 and the outer periphery of the large diameter portion 51 may be welded to each other, or may be connected by an engagement portion (not shown) such as a projection and recess that engages with each other, which is provided on the inner periphery of the housing 2 and the outer periphery of the large diameter portion 51. In addition, one or more through holes 54 of a predetermined shape are formed in the bottom portion 53 of the partition wall 5. The through holes 54 pass through the combustion products of the gas generating agent described later. A through hole may also be provided in the side portion of the small diameter portion 52 of the partition wall 5. The partition 5 also divides the internal space of the housing 2 into a first combustion chamber 21 (also referred to as an "enhancer chamber") formed between the ignition device 3 and the partition 5, and a second combustion chamber 22 formed between the partition 5 and a diffuser portion. Note that the side portion (large diameter portion 51 or small diameter portion 52) of the partition 5 may be extended to an extent that the partition 5 and the ignition device 3 come into contact with each other, so that the partition 5 and the ignition device 3 form the first combustion chamber 21.

The first combustion chamber 21 accommodates a first gas generating agent 61 (also referred to as an "enhancer agent" or "enhancer"). The second combustion chamber 22 accommodates a second gas generating agent 62. The gas generating agents (the first gas generating agent 61 and the second gas generating agent 62) include known compositions, such as guanidine nitrate (41% by weight), basic copper nitrate (49% by weight), and binders and additives. The individual shapes of the gas generating agents may be, for example, pellet-shaped, disk-shaped, columnar, or single-hole cylindrical with a through hole. However, the gas generating agent is not limited to the above. In addition, the first gas generating agent 61 and the second gas generating agent 62 may be gas generating agents of the same type, shape, and size, or may be gas generating agents of different types, shapes, and sizes. In addition, the first gas generating agent 61 may not be filled in the first combustion chamber 21, and the second gas generating agent 62 may be ignited by the ignition device 3. Also, for example, the partition wall 5 may not be provided, and the ignition device 3 may be in contact with and surrounded by the second gas generating agent 62 .

The diffuser section 4 is a cup-shaped member that is attached to close the other end of the housing 2, and houses the filter 7 inside. In other words, the diffuser section 4 is a bottomed cylinder, and is arranged so that its open end faces the second combustion chamber 22. That is, the diffuser section 4 has a side wall 41 and a closed end 42, and the open end side of the side wall 41, which is opposite to the closed end 42, is connected to the housing 2. In the example of FIG. 1, the outer diameter of the side wall 41 is approximately the same as the inner diameter of the housing 2, and a part of the open end side of the side wall 41 is housed in the housing 2. The open end side of the side wall 41 may be fixed to the housing 2 by crimping, or the diffuser section 4 and the housing 2 may be welded. The diffuser section 4 may be formed integrally with the housing 2, for example, by drawing.

As shown in FIG. 1, one or more gas discharge holes 43 are formed in the side wall 41 of the diffuser section 4. In the example of FIG. 1, the gas discharge holes 43 include a first gas discharge hole 431 (also referred to as a "first gas discharge hole group"), a second gas discharge hole 432 (also referred to as a "second gas discharge hole group"), and a third gas discharge hole 433 (also referred to as a "third gas discharge hole group"). The number of the first gas discharge holes 431, the number of the second gas discharge holes 432, and the number of the third gas discharge holes 433 are each one or more. In the present embodiment, a plurality of first gas discharge holes 431, a plurality of second gas discharge holes 432, and a plurality of third gas discharge holes 433 are provided, and the numbers of each are equal. The plurality of first gas discharge holes 431, the plurality of second gas discharge holes 432, and the plurality of third gas discharge holes 433 are formed at equal intervals in the circumferential direction of the diffuser section 4. Further, from the open end side (the side of the second combustion chamber 22) of the diffuser section 4 toward the closed end side, the first gas discharge hole 431, the second gas discharge hole 432, and the third gas discharge hole 433 are positioned in this order, and the opening area (i.e., diameter) per discharge hole increases as the hole gets farther from the second combustion chamber 22. Therefore, in this embodiment, the total opening area increases in the order of the first gas discharge hole 431, the second gas discharge hole 432, and the third gas discharge hole 433. Here, the "total opening area" refers to the sum of the opening areas of one or more gas discharge holes 43 (i.e., the sum of the opening areas of the gas discharge holes included in the first gas discharge hole group, the sum of the opening areas of the gas discharge holes included in the second gas discharge hole group, and the sum of the opening areas of the gas discharge holes included in the third gas discharge hole group).

In addition, a storage space for storing the filter 7 is formed inside the cup-shaped diffuser section 4. At least a portion of the filter 7 is stored in the storage space of the diffuser section 4. When the combustion gas generated by the gas generating agents 61 and 62 passes through the filter 7, the filter 7 functions as a cooling section that cools the combustion gas and also filters the combustion gas by collecting the combustion residue of the combustion gas.

2 is a partial cross-sectional view showing the diffuser section and its surroundings. The filter 7 is cylindrical with an outer diameter that is approximately the same as the inner diameter of the diffuser section 4, and extends from the open end side of the diffuser section 4 toward the closed end 42 side. In addition, a hollow flow path (71, 72) through which the combustion gas passes is provided inside the filter 7. The flow path includes a first section 71 located on the open end side of the diffuser section 4 and a second section 72 located on the closed end side of the diffuser section 4. In addition, of the side wall 41 of the diffuser section 4, the radial periphery of the first section 71 (i.e., the region of the side wall 41 corresponding to the first section 71) is referred to as the first side wall region, and the radial periphery of the second section 72 (i.e., the region of the side wall 41 corresponding to the second section 72) is referred to as the second side wall region. In other words, the radially surrounding portion of the side wall 41 of the diffuser section 4 around the first section 71 is a portion of the side wall 41 located radially outward from the first section 71 in a direction perpendicular to the axial direction. Similarly, the radially surrounding portion of the side wall 41 of the diffuser section 4 around the second section 72 is a portion of the side wall 41 located radially outward from the second section 72 in a direction perpendicular to the axial direction. The gas discharge hole 431 and the gas discharge hole 432 are located in the first side wall region, and the gas discharge hole 433 is located in the second side wall region. The first section 71 and the second section 72 are in communication with each other, and the combustion gas can flow from the first section 71 to the second section 72. The inner diameter of the second section 72 is smaller than the inner diameter of the first section 71. Thus, the filter 7 has a step 73 at the boundary between the first section 71 and the second section 72. The end of the second section 72 on the closed end side of the diffuser section 4 is closed by the body of the filter 7, and the flow path does not have to pass through the filter 7. The body portion of the filter 7 includes a first region 74 located radially outside the first section 71 and a second region 75 located radially outside the second section 72. Since the filter 7 has a constant outer diameter, the thickness of the first region 74 is thinner than the thickness of the second region 75.

The filter 7 may be, for example, a flat-woven metal wire placed in a mold and compressed into a cylindrical shape, with through holes corresponding to the first section 71 and the second section 72. The filter 7 may also be a rod-shaped core formed into the shape of the first section 71 and the second section 72, with metal wire wound in multiple layers and the wires crossing each other to form a columnar shape with a mesh. The filter 7 may also be a sheet-shaped porous plate such as expanded metal, punched metal, metal lath, flat-woven wire mesh, or tatami-woven wire mesh rolled up into a cylindrical shape with through holes corresponding to the first section 71 and the second section 72.

As described above, the filter 7 is a metallic filter whose main body, excluding the first section 71 and the second section 72, is solid and formed into a cylindrical shape as a whole. The metal may be stainless steel, iron, or the like, and may be plated or coated with copper, nickel, or the like. The term "solid" refers to the inclusion of a metal material at a predetermined density in order to collect the combustion residue of the combustion gas and to cool the combustion gas. In other words, the combustion gas can pass not only through the above-mentioned flow path, but also through the first and second sections 74 and 75 of the filter 7, which function as cooling sections. However, the combustion gas flows more easily through the first and second sections 71 and 72 than through the first and second sections 74 and 75.

The filter 7 also has a flange portion 76 that protrudes from the diffuser portion 4 toward the second combustion chamber 22 and has an outer diameter larger than the inner diameter of the diffuser portion 4. When the filter 7 is inserted into the diffuser portion 4, the flange portion 76 abuts against the open end of the diffuser portion 4. A gap is provided between the flange portion 76 and the housing 2.

The gas generator 1 is also provided with a cutoff section 8 between the second combustion chamber 22 and the diffuser section 4. The cutoff section 8 according to this embodiment is a single disk-shaped metal member, and closes the diffuser section 4 side of the second combustion chamber 22. That is, the diameter of the cutoff section 8 is approximately the same as the inner diameter of the second combustion chamber 22, and the housing 2 and the cutoff section 8 are welded all around from the outside of the housing 2. In FIG. 2, the welded points are shown as black triangles.

3 is a plan view of the blocking member seen from the diffuser section side. The blocking section 8 shown in FIGS. 2 and 3 has three concentric sections with different thicknesses in the axial direction of the gas generator 1. As can be seen from FIG. 2, the central first section 81 is thicker than the second section 82 located around the first section 81. The diameter of the first section 81 is smaller than the inner diameter of the first section 71 and larger than the inner diameter of the second section 72. A part of the first section 81 on the diffuser section 4 side is inserted into the first section 71. The third section 83 located around the second section 82 protrudes toward the diffuser section 4 side and is sandwiched between the housing 2 and the flange section 76 of the filter 7. The first section 81 is a cleavage section that is punched out at the boundary with the second section 82 by the combustion pressure of the gas generating agents 61, 62 when the gas generator 1 is activated. Between the first portion 81 and the second portion 82, a weakened portion such as a groove or notch where the thickness of the blocking portion 8 is thinned may be provided partially or entirely around the circumference.

The cutoff portion 8 is cleaved in stages in response to an increase in the internal pressure of the first combustion chamber 21 and the second combustion chamber 22 due to the combustion gas. Specifically, when the internal pressure first reaches a first threshold, it is cleaved along the boundary between the first portion 81 and the second portion 82, and the first portion 81 is punched out. The first threshold is the combustion pressure value due to the gas generating agent generated when the gas generator 1 is activated, and is also referred to as the activation threshold in this disclosure. Then, the first portion 81 of the cutoff portion 8 moves to the step portion 73 at the boundary between the first portion 81 and the second portion 82 due to the flow of the combustion gas.

Figure 4 is a partial cross-sectional view showing an example of a state in which the blocking member is cleaved and the first portion is moved. In the state of Figure 4, the first portion 81 of the blocking portion 8 blocks the inflow of combustion gas from the first section 71 to the second section 72. The combustion pressure caused by the gas generating agent gradually increases beyond the first threshold value at room temperature, but is set so as not to exceed the second threshold value described below. Therefore, when operating at room temperature, the first portion 81 does not cleave and continues to block the second section. Also, when operating in a high temperature environment, after the first threshold value described above occurs, the first portion 81 further reaches a pressure equal to or greater than the second threshold value, and this pressure is applied to the first portion 81. Therefore, the first portion cleaves, and the first section 71 and the second section 72 communicate with each other. The second threshold value is also referred to as a critical threshold value in this disclosure.

Figure 5 is a partial cross-sectional view showing an example of a state in which the first portion of the blocking member is further torn. In Figure 5, the center of the first portion 81 is further punched out, and a part of the first portion 81 moves toward the closed end side of the diffuser section 4. The first portion 81 may further include a fragile portion (not shown) such as a groove or notch designed to be torn by a pressure equal to or greater than a second threshold value. The first portion 81 may be capable of breaking by a pressure equal to or greater than the second threshold value to connect the first section 71 and the second section 72. For example, as shown in Figure 5, a part of the first portion 81 may not be punched out, and the entire first portion 81 may be bent and move to the second section 72. As described above, the blocking section 8 is torn in stages to block or open the space between the first section 71 and the second section 72.

<Operation>
When the gas generator 1 is mounted on, for example, an airbag of an automobile, a connector (not shown) is connected to the pair of conductive pins 32, 32, and power can be supplied to the ignition device 3. In this state, when a sensor (not shown) mounted on the automobile or the like detects an impact, the ignition device 3 is activated by an ignition current supplied to the pair of conductive pins 32, 32. The ignition device 3 burns the ignition charge in the cup body 31 and releases the combustion product to the outside of the cup body 31. The first gas generating agent 61 is ignited by the flame and combustion gas, which are the combustion products of the ignition charge. The first gas generating agent 61 generates combustion gas as a combustion product, and the combustion gas passes through the through hole 54 of the partition wall 5 to ignite the second gas generating agent 62 in the second combustion chamber 22. The second gas generating agent 62 also generates combustion gas as a combustion product.

The example of FIG. 4 described above, in other words, represents the state when the gas generator 1 is operated. FIG. 6 is a diagram showing the flow of the combustion gas in the example of FIG. 4. When the environment in which the gas generator 1 operates is equal to or lower than a predetermined temperature, the reaction rate of the combustion of the gas generating agent is relatively small. At this time, the pressure inside the first combustion chamber 21 and the second combustion chamber 22 is designed to exceed the first threshold value described above and rise to a value lower than the second threshold value described above. Therefore, when the pressure of the combustion gas in the first combustion chamber 21 and the second combustion chamber 22 reaches the first threshold value, the periphery of the first part 81 of the blocking part 8 is torn, and the first part 81 remains in the step part 73. Then, the flow of the combustion gas is blocked between the first section 71 and the second section 72 by the first part 81 of the blocking part 8. Therefore, as shown in FIG. 6, the combustion gas passes mainly through the first region 74 of the filter 7, where it is filtered and cooled, and is discharged mainly from the first gas discharge hole 431 and the second gas discharge hole 432 of the diffuser section 4. Note that a portion of the combustion gas also flows into the second region 75 of the main body of the filter 7, and is also discharged from the third gas discharge hole 433, but the amount is relatively small. Therefore, the proportion of the combustion gas passing through the second region 75 is very small, and excessive cooling is suppressed.

The example of Fig. 5 described above, in other words, represents the operation of the gas generator 1 in an environment higher than a predetermined temperature. Fig. 7 is a diagram showing a schematic view of the flow of the combustion gas in the example of Fig. 5. When the environment in which the gas generator 1 operates is higher than a predetermined temperature, the reaction rate of the combustion of the gas generating agent is higher than that of the examples shown in Figs. 4 and 6. The temperature of the generated combustion gas is also higher than that of the combustion gas generated during operation at normal temperature. At this time, the pressure inside the first combustion chamber 21 and the second combustion chamber 22 is designed to exceed the above-mentioned second threshold value after reaching the first threshold value. Therefore, the pressure of the combustion gas in the first combustion chamber 21 and the second combustion chamber 22 breaks the periphery of the first portion 81 of the interrupter 8, and the first portion 81 of the interrupter 8 moves to the step portion 73 of the filter 7, and the first portion 81 is further broken, so that the first section 71 and the second section 72 communicate with each other. Therefore, as shown in FIG. 7 , the combustion gas passes through the first region 74 and the second region 75 of the filter 7, is filtered and cooled, and is discharged from the first gas discharge hole 431, the second gas discharge hole 432, and the third gas discharge hole 433 of the diffuser section 4.

＜Effects＞
In general, the output of a gas generator changes depending on the environmental temperature at the time of operation. That is, when the environmental temperature rises, the combustion speed of the gas generating agent also rises, so that even gas generators of the same specifications tend to have higher output at the time of operation in a high-temperature environment. In this embodiment, in an environment at or above a predetermined temperature (FIG. 7), the temperature of the combustion gas generated in the first combustion chamber 21 and the second combustion chamber 22 is higher than in an operation in an environment below the predetermined temperature (FIG. 6). On the other hand, in the example of FIG. 7, a wider portion of the filter 7 can be used as a cooling section, and thus the cooling efficiency is higher than in the example of FIG. 6. This suppresses the rise in the temperature of the combustion gas, and the difference in the output performance of the gas generator due to the difference in the environmental temperature at the time of operation can be suppressed. In the example of FIG. 6, the area of the filter 7 through which the combustion gas flows is narrowed, and the cooling of the combustion gas is suppressed compared to the example of FIG. 7. The combustion gas discharged from the gas generator 1 is discharged from the first combustion chamber 21 and the second combustion chamber 22.
Since the gas generator 1 of the present disclosure has a temperature obtained by mixing the combustion gas discharged from the gas exhaust hole 431, the combustion gas discharged from the second gas exhaust hole 432, and the combustion gas discharged from the third gas exhaust hole 433, the difference in output due to differences in environmental temperature can be reduced.

<Embodiment 2>
8 is a schematic partial axial cross-sectional view showing an example of a gas generator according to a second embodiment. In this embodiment, the blocking unit 8 is different from that of the first embodiment. Therefore, the same components as those of the first embodiment described above are given the corresponding reference numerals or are not shown in the drawings.

8 has a through hole 84 in the center of the first portion 81, and the through hole 84 is blocked by a sealing tape 85. The sealing tape 85 is, for example, a sealing member in which an adhesive layer is formed on one side of an aluminum foil or a stainless steel foil. In this embodiment, the sealing tape 85 is designed to require a larger force to tear than the boundary between the first portion 81 and the second portion 82. That is, as in the first embodiment, the boundary between the first portion 81 and the second portion 82 of the blocking portion 8 is torn when the internal pressure of the first combustion chamber 21 and the second combustion chamber 22 exceeds a first threshold value due to the combustion gas. In addition, the sealing tape 85 is torn when the internal pressure of the first combustion chamber 21 and the second combustion chamber 22 exceeds a second threshold value that is greater than the first threshold value due to the combustion gas. The breaking strength of the sealing tape 8 can be adjusted by changing the material or thickness of the sealing tape 8, or by stacking two or more sealing tapes 85. In this embodiment, the strength of the first part 81, the second part 82, and the sealing tape 85 can be designed separately, making the design easier.

9 is a partial cross-sectional view showing an example of a state in which the blocking portion is torn and the first portion is moved. In this embodiment, when the first portion 81 of the blocking portion 8 moves to the step portion 73 of the filter 7, it blocks the inflow of combustion gas from the first section 71 to the second section 72. FIG. 10 is a partial cross-sectional view showing an example of a state in which the sealing tape is further torn. When pressure equal to or greater than the second threshold value described above is applied, the sealing tape 85 is further torn, the through hole 84 is opened, and the first section 71 and the second section 72 are connected to each other. As described above, the blocking portion 8 is torn in stages to close or open the space between the first section 71 and the second section 72. The gas generator 1 according to this embodiment also allows the size of the portion of the filter 7 used as a cooling portion to be changed in stages according to the environmental temperature.

<Embodiment 3>
11 is a schematic partial axial cross-sectional view showing an example of a gas generator according to the third embodiment. In this embodiment, a filter 7 and a blocking section 8 are different from those in the first and second embodiments. Furthermore, the same components as those in the first and second embodiments described above are given corresponding reference numerals or are not shown in the drawings.

In this embodiment, the blocking section 8 includes a first blocking member 86 and a second blocking member 87 which are separate bodies. The first region 74 and the second region 75 of the filter 7 are formed as separate bodies, and the second blocking member 87 is disposed between them. The first blocking member 86 is a component corresponding to the blocking section 8 in the first embodiment, and is designed to break open when the pressure during combustion exceeds at least a first threshold value. In this embodiment, the portion of the first blocking member 86 which is punched out when breaking open is smaller than the inner diameter of the first section 71 and the inner diameter of the second section 72. In this embodiment, the inner diameter of the first section 71 and the inner diameter of the second section 72 may be the same, or the inner diameter of the second section 72 may be larger than the inner diameter of the first section 71. The second blocking member 87 is a disk-shaped metal member and is disposed between the first region 74 and the second region 75 of the filter 7. The diameter of the second shutoff member 87 is substantially the same as the inner diameter of the diffuser portion 4, and the diffuser portion 4 and the second shutoff member 87 may be welded from the outside of the diffuser portion 4. The second shutoff member 87 is designed to be ruptured at a pressure equal to or greater than a second threshold value that is greater than the first threshold value. Therefore, the shutoff portion 8 according to this embodiment also ruptures in stages according to the pressure, and can sequentially open the space between the second combustion chamber 22 and the first section 71, and the space between the first section 71 and the second section 72. Thus, the gas generator 1 according to this embodiment also makes it possible to change in stages the size of the portion of the filter 7 used as a cooling section according to the environmental temperature. Note that a filter 7 may be used in which the first region 74 and the second region 75 of the filter 7 are arranged to be in contact with each other, and an annular groove for holding the second shutoff member 87 is provided between the first region 74 and the second region 75.

<Embodiment 4>
12 is a schematic partial axial cross-sectional view showing an example of a gas generator according to a fourth embodiment. In this embodiment, a filter 7 and a blocking section 8 are different from those in the other embodiments. Also, the same components as those in the other embodiments described above are given the corresponding reference numerals or are not shown in the drawings.

In this embodiment, as in the third embodiment, the first region 74 and the second region 75 of the filter 7 are formed as separate bodies, with a gap between them. The inner diameter of the first section 71 and the inner diameter of the second section 72 may be the same, or the inner diameter of the second section 72 may be larger than the inner diameter of the first section 71. The second combustion chamber 22 in the housing 2 and the first section 71 of the filter 7 are connected, and the first section 71 is also filled with the second gas generating agent 62. The second combustion chamber 22 and the first section 71 may be partitioned, for example, with a wire mesh (not shown) with a mesh size smaller than that of the second gas generating agent 62, so that only the second combustion chamber 22 is filled with the second gas generating agent 62.

The blocking section 8 according to this embodiment includes a sealing tape 88 and a third blocking member 89. The sealing tape 88 according to this embodiment is also, for example, an aluminum foil or a stainless steel foil with an adhesive layer formed on one side. The sealing tape 88 blocks all the gas exhaust holes 431 and the gas exhaust holes 432 provided around the radial direction of the first section 71. The sealing tape 88 according to this embodiment is designed to break open when the combustion pressure exceeds a first threshold value. The third blocking member 89 is a member similar to the second blocking member 87 according to the third embodiment. That is, the third blocking member 89 is also a disk-shaped metal member and is disposed between the first region 74 and the second region 75 of the filter 7. The diameter of the third blocking member 89 is approximately the same as the inner diameter of the diffuser section 4, and the diffuser section 4 and the third blocking member 89 are welded all around from the outside of the diffuser section 4. The third blocking member 89 is designed to break open at a pressure equal to or greater than a second threshold value that is greater than the first threshold value.

As described above, in the gas generator 1 according to this embodiment, the second combustion chamber 22 and the first section 71 are initially open. Furthermore, depending on the pressure, the sealing tape 88 that blocks the gas exhaust hole 431 and the gas exhaust hole 432 and the third blocking member 89 between the first section 71 and the second section 72 are gradually torn open, and the gas exhaust hole 43 is opened. Therefore, with the gas generator 1 according to this embodiment, the size of the portion of the filter 7 used as a cooling section can also be gradually changed depending on the environmental temperature.

<Embodiment 5>
13 is a schematic axial cross-sectional view showing an example of a gas generating device according to another embodiment. In this embodiment, the same components as those in the above-mentioned embodiment are given the same reference numerals or are not shown.

In the present embodiment, the blocking portion 8 is an orifice plate having an opening provided in advance in the center, and does not cleave in stages in response to the internal pressure of the gas generator 1. Moreover, inside the housing 2, a hollow portion 23 that does not hold a gas generating agent is formed in place of the first combustion chamber 21. That is, the housing 2 is partitioned by the partition 5 into the hollow portion 23 formed between the ignition device 3 and the partition 5, and a combustion chamber 24 formed between the partition 5 and the diffuser portion 4.

In this embodiment, the periphery of the blocking portion 8 does not abut against the inner circumference of the housing 2. In addition, a crank-shaped boundary is formed between the filter 7 and the housing 2 and the diffuser portion 4 in a vertical cross-sectional view. The outer diameter of the blocking portion 8 is smaller than the inner diameter of the housing 2, and the third portion 83 is not provided. A gap is provided between the outer periphery of the blocking portion 8 and the housing 2. Such a blocking portion 8 may be sandwiched between the filter 7 and the gas generating agent 6, or the blocking portion 8 and the filter 7 may be welded at least in part. If the filter 7 has a through hole or a recess, the first portion 81 of the blocking portion 8 may be inserted into the through hole or recess of the filter 7 to be aligned. In addition, the blocking portion 8 has one or more through holes 84, and in this embodiment, it is not blocked by a seal member or the like. In this configuration, the gas generator 1 according to this embodiment suppresses the combustion gas from being discharged from the gas exhaust hole 43 of the diffuser portion 4 without passing through the filter 7.

In this embodiment, the filter 7 also has a first region 74 and a second region 75 (the first region 74 and the second region 75 are collectively referred to as the "main body") and a flange portion 76. The flange portion 76 of the filter 7 abuts against the open end of the diffuser portion 4 when the filter 7 is inserted into the diffuser portion 4. FIG. 14 is a partial cross-sectional view showing the diffuser portion and its surroundings. The flange portion 76 of the filter 7 includes a first annular surface 761 that abuts against the open end of the diffuser portion 4 when the filter 7 is inserted into the diffuser portion 4, a second annular surface 762 that is opposite to the first annular surface 761 and faces the combustion chamber 24, and an annular circumferential surface 763 that connects the first annular surface 761 and the second annular surface 762 and faces the outer circumferential direction.

The first annular surface 761 abuts against the open end of the diffuser section 4. In particular, when the gas generator 1 is activated, the combustion gas generated by the combustion of the gas generating agent 6 increases the internal pressure of the combustion chamber 24, and the filter 7 is urged toward the diffuser section 4. At this time, since there is no gap between the first annular surface 761 and the open end of the diffuser section 4, the combustion gas is prevented from being discharged without passing through the filter 7 along the crank-shaped boundary between the filter 7 and the housing 2 and the diffuser section 4 in a vertical cross-sectional view. At least a portion of the first annular surface 761 may be welded to the open end of the diffuser section 4.

The annular circumferential surface 763 may also be press-fitted so as to abut against the inner circumference of the housing 2. This configuration also prevents the combustion gas from being discharged without passing through the filter 7 along the crank-shaped boundary between the filter 7 and the housing 2 and the diffuser section 4 in a vertical cross-sectional view.

In addition, the area along the outer periphery of the second annular surface 762 (also called the "outer periphery") is exposed to the combustion chamber 24 without being covered by the blocking portion 8. Therefore, the combustion gas also enters the filter 7 from the outer periphery of the second annular surface 762. FIG. 15 is a schematic diagram for explaining the movement path of the combustion gas in the diffuser portion. In FIG. 15, the dashed arrows illustrate the movement path of the combustion gas in the diffuser portion 4. The combustion gas that enters the filter 7 from the outer periphery of the second annular surface 762 passes through the filter 7 for a relatively longer distance or more times than the combustion gas that passes through the through holes 84 of the blocking portion 8 and enters the filter 7 from the flow path in the filter 7. Therefore, it can be said that the cooling efficiency of the combustion gas and the collection effect of the combustion residue are improved by introducing the combustion gas into the filter 7 from the outer periphery of the second annular surface 762.

In addition, a part of the combustion gas that passes through the through holes 84 of the blocking section 8 and enters the flow path in the filter 7 collides with the closed end 42 of the diffuser section 4, changes direction, passes through the filter 7, and is discharged from the gas discharge hole 43. By configuring the filter 7 and the closed end 42 of the diffuser section 4 to abut against each other, it is possible to suppress the combustion gas from being discharged along the boundary between the filter 7 and the closed end 42 without passing through the filter 7. In addition, the flow velocity of the combustion gas increases after passing through the through holes 84 of the blocking section 8, which is an orifice plate, and a relatively large amount of the combustion gas reaches the closed end 42 of the diffuser section 4. By making the thickness of the filter 7 thicker on the closed end 42 side than on the open end side of the diffuser section 4, it is possible to improve the cooling efficiency of the combustion gas that reaches the closed end 42 and the collection effect of the combustion residue. In this embodiment, the flow path formed inside the filter 7 may be a recess that is blocked on the closed end 42 side of the diffuser section 4 instead of a through hole, and the filter 7 may not have the flow path (71, 72).

In this embodiment, the housing 2 is divided by the partition 5 into a hollow portion 23 formed between the ignition device 3 and the partition 5, and a combustion chamber 24 formed between the partition 5 and the diffuser portion 4. The hollow portion 23 does not contain a gas generating agent, but may be filled with a gas generating agent as shown in FIG. 1. The combustion chamber 24 holds a gas generating agent 6 therein. The gas generating agent 6 is formed of a known composition and burns to generate combustion gas. The gas generating agent 6 may be the same as the first gas generating agent 61 or the second gas generating agent 62, or may be different.

The partition 5 presses the granular gas generating agent 6 contained in the combustion chamber 24 toward the diffuser portion 4, and functions as a holder (also called a "retainer") that prevents the gas generating agent 6 from swinging. That is, the partition 5 is, for example, press-fitted into the housing 2, and the large diameter portion 51 of the side of the partition 5 functions as a connection portion that abuts against the inner circumference of the housing 2. In addition, the bottom portion 53 of the partition 5 is a flat plate portion, and presses the granular gas generating agent 6 contained in the combustion chamber 24 toward the diffuser portion 4.

The partition wall 5 does not have a through hole 54 in the center of the bottom 53, but has it closer to the periphery. For example, multiple through holes 54 are provided along the periphery of the bottom 53. Figure 16 is a schematic diagram for explaining the movement path of the combustion gas in the combustion chamber. Granular gas generating agent 6 is filled in the combustion chamber 24. The shape of the gas generating agent 6 is, for example, cylindrical, and irregular gaps are formed between the gas generating agents 6. The size and shape of the gas generating agent 6 are not limited to those shown in the figure.

When the combustion gas flows through the combustion chamber 24, it moves between the gas generating agents 6 packed in a complicated manner, so the path length is longer than the length of the housing 2. However, since the inner circumferential surface of the housing 2 and the gas generating agents 6 do not intertwine with each other, a gap is formed that extends relatively linearly along the inner circumferential surface of the housing 2 to the diffuser portion 4. Therefore, as shown by the dashed arrow in FIG. 16, the combustion gas can flow relatively linearly along the inner circumferential surface of the housing 2 in the axial direction of the housing 2. As described above, by providing the through hole 54 near the outer periphery of the bottom 53 of the partition wall 5, the combustion product of the ignition device 3 that passes through the through hole 54 can easily flow along the inner circumferential surface of the housing 2 in the combustion chamber 24, thereby shortening the time from the activation of the gas generator 1 to the discharge of the combustion gas. In this case, of course, the through hole 54 may also be present in the center of the bottom 53.

<Embodiment 6>
17 is a schematic axial cross-sectional view showing an example of a gas generating device according to a sixth embodiment, which is a modified example of embodiment 5. In this embodiment, the same components as those in the above-mentioned embodiments are given the corresponding reference numerals or are not shown.

FIG. 17 shows the igniter, the hollow portion, and the surroundings. The partition wall 5 of the gas generator 1 according to this embodiment has a through hole 54 in the small diameter portion 52 of the side portion. Moreover, the partition wall 5 does not have a through hole 54 in the bottom portion 53. With such a partition wall 5, the combustion product of the ignition device 3 is discharged from the hollow portion 23 to the combustion chamber 24 toward the inner circumference of the housing 2. Therefore, the combustion product of the ignition device 3 is easily passed through the path along the inner circumference surface of the housing 2 indicated by the dashed arrow in FIG. 16. That is, the time from the activation of the gas generator 1 to the discharge of the combustion gas can be shortened. Note that the gas generating agent 6 does not exist in the annular space between the small diameter portion 52 and the housing 2. That is, the length between the small diameter portion 52 and the housing 2, or the length of the small diameter portion 52 in the axial direction of the housing 2 is smaller than the diameter and height of the gas generating agent 6, which is, for example, cylindrical.

<Embodiment 7>
18 is a schematic axial cross-sectional view showing an example of a gas generating device according to a seventh embodiment, which is a modified example of embodiment 5. In this embodiment, the same components as those in the above-mentioned embodiments are given the corresponding reference numerals or are not shown.

18 shows the igniter, the hollow portion, and the surroundings. The partition wall 5 of the gas generator 1 according to this embodiment does not have a small diameter portion 52 on its side, and has an annular inclined surface 55 tapered from the large diameter portion 51 to the outer edge of the bottom portion 53. The annular inclined surface 55 has a through hole 54. The partition wall 5 does not have a through hole 54 at the bottom portion 53. Even with such a partition wall 5, the combustion product of the ignition device 3 is discharged from the hollow portion 23 to the combustion chamber 24 toward the inner circumference of the housing 2. Therefore, the combustion product of the ignition device 3 is easily passed through the path along the inner circumference surface of the housing 2 shown by the dashed arrow in FIG. 16. That is, the time from the activation of the gas generator 1 to the discharge of the combustion gas can be shortened. There is no gas generating agent 6 in the annular space between the annular inclined surface 55 and the housing 2. That is, the radial length or axial length of the housing 2 in the annular space is smaller than the diameter and height of the gas generating agent 6, which is, for example, cylindrical.

＜Other＞
Although the embodiments of the gas generator according to the present disclosure have been described above, each aspect disclosed herein may be combined with other features disclosed herein. For example, the first blocking member 86 and the second blocking member 87 in Fig. 11 and the third blocking member 89 in Fig. 12 may each have a through hole and a sealing tape that closes the through hole, and the sealing tape may be ruptured when a predetermined pressure is applied.

In the above-described embodiment, the first gas exhaust hole 431, the second gas exhaust hole 432, and the third gas exhaust hole 433 have larger opening areas as they are further from the second combustion chamber 22. The total opening area of the gas exhaust holes provided in the second side wall region located around the second section 72 may be larger than the total opening area of the gas exhaust holes provided in the first side wall region located around the first section 71 in the side wall of the diffuser section. When the internal pressure of the gas generator 1 is sufficiently high, the ratio of the amount of combustion gas discharged from each gas exhaust hole 43 per unit time corresponds to the ratio of the areas of the gas exhaust holes 43. Therefore, by increasing the opening area of the third gas exhaust hole 433, in a state in which the first section 71 and the second section 72 are connected, the combustion gas can be passed through the second region 75 of the filter 7 as much as possible, thereby improving the cooling efficiency. The gas exhaust holes 43 in the second sidewall region may have a larger opening area (diameter) than the gas exhaust holes 43 in the first sidewall region, or the opening area (diameter) per exhaust hole may be the same and the number of gas exhaust holes 43 may be greater in the second sidewall region. Also, the opening ratio of the gas exhaust holes 43 relative to the area of the diffuser section 4 may be higher in the second sidewall region than in the first sidewall region. However, the opening area and shape of the gas exhaust holes 43 are not limited to those shown in the figure, and for example, all the opening areas may be the same, or the opening ratio may be higher in the first sidewall region than in the second sidewall region.

The cutoff section 8 of the gas generator 1 may be configured to switch the area of the filter 7 used as a cooling section between three or more stages depending on the internal pressure of the combustion chamber. The gas generator 1 may also be incorporated into a device other than an airbag.

The first combustion chamber 21 and the second combustion chamber 22 shown in the first to fourth embodiments may be applied to the fifth to seventh embodiments, and the hollow portion 23 and the combustion chamber 24 shown in the fifth to seventh embodiments may be applied to the first to fourth embodiments.

1: Gas generator 2: Housing 21: First combustion chamber 22: Second combustion chamber 23: Hollow portion 24: Combustion chamber 3: Ignition device 4: Diffuser portion 41: Side wall 42: Closed end 43 (431-433): Gas exhaust hole 5: Partition wall 6: Gas generating agent 61: First gas generating agent 62: Second gas generating agent 7: Filter 71: First section 72: Second section 73: Step portion 74: First region 75: Second region 8: Shut-off portion 81: First portion 82: Second portion 83: Third portion 84: Through hole 85: Sealing tape 86: First shut-off member 87: Second shut-off member 88: Sealing tape 89: Third shut-off member

Claims (16)

a housing extending from one end to the other end forming an outer shell;
an ignition device mounted to the housing;
a combustion chamber formed within the housing and containing a gas generating agent that is ignited by the ignition device;
a diffuser portion provided on the other end side of the housing and including a closed end and a side wall having a plurality of gas discharge holes;
a filter at least a portion of which is accommodated inside the diffuser portion, the filter having a hollow flow passage extending from the combustion chamber side to the closed end side, the flow passage including a first section having one end connected to the combustion chamber and a second section connected to the other end of the first section;
a blocking unit that closes the gap between the first section and the second section when a combustion pressure of the gas generating agent during activation is less than a predetermined critical threshold, and that opens the gap between the first section and the second section when the combustion pressure is equal to or greater than the critical threshold;
Equipped with
a sidewall of the diffuser portion includes a first sidewall region located around the first section and a second sidewall region located around the second section, and one or more of the gas discharge holes are provided in each of the first sidewall region and the second sidewall region. The filter has an inner diameter of the second section that is smaller than an inner diameter of the first section, and has a step portion at a boundary between the first section and the second section,
the blocking portion includes a cleavage portion that blocks the space between the combustion chamber and the first section before activation, has a diameter equal to or smaller than an inner diameter of the first section and larger than an inner diameter of the second section, and is formed to be punched out by a pressure equal to or greater than an activation threshold value that is smaller than the critical threshold value,
When the combustion pressure is equal to or greater than the activation threshold value and less than a critical threshold value, the combustion pressure causes the cleavage portion to be punched and move to the step portion, thereby closing the gap between the first section and the second section;
2. The gas generator according to claim 1, wherein, when the combustion pressure further reaches or exceeds the critical threshold value, the combustion pressure causes at least a part of the cleavage portion to move beyond the step portion into the second section, thereby connecting the first section and the second section. The filter has an inner diameter of the second section that is smaller than an inner diameter of the first section, and has a step portion at a boundary between the first section and the second section,
the blocking portion includes a cleavage portion that blocks the space between the combustion chamber and the first section before activation, has a diameter equal to or smaller than an inner diameter of the first section and larger than an inner diameter of the second section, and is formed to be punched out by a pressure equal to or greater than an activation threshold value that is smaller than the critical threshold value,
The cleavage portion has a through hole and a sealing member that closes the through hole and cleaves when a pressure equal to or greater than the critical threshold value is applied,
When the combustion pressure is equal to or greater than the activation threshold value and less than a critical threshold value, the combustion pressure causes the cleavage portion to be punched and move to the step portion, thereby closing the gap between the first section and the second section;
2. The gas generator according to claim 1, wherein, when the combustion pressure further reaches or exceeds the critical threshold value, the sealing member is ruptured by the combustion pressure to open the through hole, thereby establishing a state of communication between the first section and the second section. 2. The gas generator according to claim 1, wherein the blocking section includes: a first blocking member that blocks the gap between the combustion chamber and the first section before activation and that ruptures at an activation threshold value at which the combustion pressure is lower than the critical threshold value to connect the combustion chamber and the first section; and a second blocking member that blocks the gap between the first section and the second section before activation and that connects the first section and the second section when the combustion pressure further exceeds the critical threshold value. 2. The gas generator according to claim 1, wherein the blocking portion includes: a sealing member that blocks the gas discharge hole provided in the first sidewall region before activation and that ruptures when the combustion pressure reaches an activation threshold value that is lower than the critical threshold value; and a blocking member that blocks the space between the first section and the second section before activation and, when the combustion pressure further exceeds the critical threshold value, connects the first section and the second section. The gas generator according to claim 2 or 3, wherein the interrupting portion includes a weakened portion formed by thinning the interrupting portion along a shape of the cleavage portion. 7. The gas generator according to claim 1, wherein a total opening area of the gas discharge holes provided in the second side wall region is larger than a total opening area of the gas discharge holes provided in the first side wall region. A gas discharge method performed by a gas generator, comprising the steps of:
The gas generator is
a housing extending from one end side to the other end side forming an outer shell container;
an ignition device mounted to the housing;
a combustion chamber formed within the housing and containing a gas generating agent that is ignited by the ignition device;
a diffuser portion provided on the other end side of the housing and including a closed end and a side wall having a plurality of gas discharge holes;
a filter at least a portion of which is accommodated inside the diffuser portion, the filter having a hollow flow passage extending from the combustion chamber side to the closed end side, the flow passage including a first section having one end connected to the combustion chamber and a second section connected to the other end of the first section;
a blocking section that, when a combustion pressure of the gas generating agent during activation is less than a predetermined critical threshold, blocks a section between the first section and the second section, and, when the combustion pressure exceeds the critical threshold, connects the first section to the second section;
Equipped with
a side wall of the diffuser portion includes a first side wall region located around the first section and a second side wall region located around the second section, and one or more of the gas discharge holes are provided in each of the first side wall region and the second side wall region,
The gas discharge method is
supplying an ignition current to ignite the ignition device and burn the gas generating agent;
a blocking state between the first section and the second section by the blocking section when the combustion pressure is less than a predetermined critical threshold, and a connecting state between the first section and the second section when the combustion pressure is equal to or greater than the critical threshold. A cylindrical housing that forms an outer shell and extends from one end to the other end;
an ignition device mounted to the housing;
a combustion chamber formed within the housing and containing a gas generating agent that is ignited by the ignition device;
a cylindrical diffuser portion inserted into one end side of the housing and having a gas discharge hole;
a filter including a main body portion accommodated in the diffuser portion and a flange portion at an end portion of the main body portion facing the housing, the flange portion protruding radially outward beyond an inner periphery of the diffuser portion;
Equipped with
a first annular surface of the surface of the flange portion facing the main body portion abuts against an end of the diffuser portion on the housing side. The flange portion has a second annular surface facing a back side of the first annular surface, and an annular circumferential surface connecting the first annular surface and the second annular surface,
The gas generator according to claim 9 , wherein the annular circumferential surface abuts against an inner periphery of the housing. The main body of the filter has a recess extending from the housing side along an axial direction of the diffuser portion,
11. The gas generator according to claim 9 or 10, further comprising an orifice plate disposed inside the housing, the orifice plate defining the combustion chamber and the recess and having a through hole communicating between the combustion chamber and the recess. The main body of the filter has a recess extending from the housing side along an axial direction of the diffuser portion,
an orifice plate is provided inside the housing, the orifice plate partitioning the combustion chamber and the recess and having a through hole communicating the combustion chamber and the recess;
The gas generator according to claim 10 , wherein an outer diameter of the orifice plate is smaller than an outer diameter of the flange portion, and an outer periphery of the second annular surface of the flange portion is exposed to a side of the housing. The diffuser portion has a closed end on the opposite side to the housing,
13. The gas generator according to claim 11, wherein the filter abuts against the closed end, the recess of the filter is a through hole, and the thickness of the filter is greater on the closed end side than on the housing side. The ignition device is attached to the other end side of the housing,
a retainer that divides a space in which the ignition device is disposed and the combustion chamber, the retainer having an opening and that holds the gas generating agent within the combustion chamber;
14. The gas generator according to claim 9, wherein the retainer has a flat plate portion supporting the gas generating agent, and a connection portion provided on an outer periphery of the flat plate portion and abutting against an inner periphery of the housing, and has a through hole in a peripheral portion of the flat plate portion. The ignition device is attached to the other end side of the housing,
a retainer that divides a space in which the ignition device is disposed and the combustion chamber, the retainer having an opening and that holds the gas generating agent within the combustion chamber;
14. The gas generator according to claim 9, wherein the retainer has a flat plate portion supporting the gas generating agent, a stepped portion provided along an outer periphery of the flat plate portion and spaced from an inner periphery of the housing, and a connection portion abutting against the inner periphery of the housing, and the stepped portion has a through hole. The ignition device is attached to the other end side of the housing,
a retainer that divides a space in which the ignition device is disposed and the combustion chamber, the retainer having an opening and that holds the gas generating agent within the combustion chamber;
14. The gas generator according to any one of claims 9 to 13, wherein the retainer has an outer diameter smaller than an inner diameter of the housing, and includes a flat plate portion supporting the gas generating agent, a connection portion abutting against an inner circumference of the housing, and an annular inclined surface tapered from an outer periphery of the flat plate portion to the connection portion, and the annular inclined surface has a through hole.

Images