CN117396371A - Gas generator and gas discharge method - Google Patents
Gas generator and gas discharge method Download PDFInfo
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- CN117396371A CN117396371A CN202180098327.5A CN202180098327A CN117396371A CN 117396371 A CN117396371 A CN 117396371A CN 202180098327 A CN202180098327 A CN 202180098327A CN 117396371 A CN117396371 A CN 117396371A
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Abstract
The difference in output due to the difference in ambient temperature is reduced in the gas generator. The gas generator is provided with: an ignition device mounted on one end side of the housing; a combustion chamber formed in the housing and containing a gas generating agent; a cup-shaped diffusion part formed at the other end side of the housing and having a plurality of gas discharge holes; a filter, at least a part of which is accommodated in the interior of the diffusion section, wherein the filter has a hollow flow path extending from the open end side to the closed end side of the diffusion section, and the flow path includes a first section having one end connected to the combustion chamber and a second section having the other end connected to the first section; and a cutoff unit that, when the combustion pressure of the gas generating agent during operation is less than a predetermined critical threshold, closes the first section and the second section, and when the combustion pressure is greater than or equal to the critical threshold, opens the first section and the second section.
Description
Technical Field
The present invention relates to a gas generator and a gas discharge method.
Background
Conventionally, there has been proposed a gas generator including: a metal housing main body having a long tubular shape; a metal holder to which an igniter is assembled; and a bottomed tubular housing chamber defining member defining a gas generating agent housing chamber in which a gas generating agent is housed (for example, patent document 1). In this technique, when the gas generated by combustion of the gas generating agent passes through the filter, the gas acts as a cooling means for cooling the gas by capturing the heat of the gas at a high temperature, and also acts as a removal means for removing the residue (slag) and the like contained in the gas. In addition, a plurality of gas ejection ports are provided in the circumferential direction and the axial direction in a part of the housing main body defining the filter chamber. The gas outlet port guides the gas after passing through the filter to the outside of the housing.
In addition, a cylindrical gas generator is proposed, which comprises: a housing including a first housing member in the shape of a long bottomed cylinder, an igniter, a partition plate, a partitioning member, a powder, a gas generating agent, and a filter (for example, patent document 2). The partitioning member is configured by 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 a portion of the working gas generating chamber other than the hollow portion. Further, the cylindrical gas generator is provided with: the inner pressure during operation applies a force to the partition plate toward the radial outside of the housing, thereby suppressing movement of the partition plate.
Prior art literature
Patent literature
Patent document 1: japanese patent laid-open publication No. 2017-193192
Patent document 2: japanese patent application laid-open No. 2010-260387
Disclosure of Invention
Problems to be solved by the invention
In general, the output of a gas generator varies according to the ambient temperature at the time of operation. That is, when the ambient temperature increases, the combustion speed of the gas generating agent increases, and even in the case of the gas generator of the same specification, the temperature of the combustion gas output during operation tends to increase in a high-temperature environment.
The technology of the present disclosure is to provide a technology for reducing a difference in output due to a difference in ambient temperature in a gas generator.
In the gas generator, if a gap is formed between the filter and the housing, a short circuit (short path) may occur in which the generated combustion gas is discharged from the gas discharge hole of the housing so as not to pass through the filter. Further, for example, the occurrence of short-circuiting can be suppressed by performing the whole-cycle welding without any gap, but the manufacturing process is troublesome. Accordingly, the technology of the present disclosure may also aim to suppress occurrence of short circuits with a simple configuration, instead of or in addition to the above-described object.
Solution for solving the problem
The gas generator of the present disclosure includes: a housing forming a housing container extending from one end side to the other end side; an ignition device assembled to the housing; a combustion chamber formed in the interior of the housing and accommodating a gas generating agent to be ignited by the ignition device; a cup-shaped diffusion part provided at the other end side of the housing, the diffusion part including a closed end having a closed end and a side wall having a plurality of gas discharge holes; a filter, at least a part of which is accommodated in the interior of the diffusion section, wherein the filter has a hollow flow path extending from the combustion chamber side to the closed end side, and the flow path includes a first section having one end connected to the combustion chamber and a second section having the other end connected to the first section; and a cutoff unit that, when the combustion pressure of the gas generating agent during operation is less than a predetermined critical threshold, closes the first section and the second section, and when the combustion pressure is greater than or equal to the critical threshold, opens the first section and the second section. The side wall of the diffusion 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 discharge holes are provided in each of the first and second side wall regions.
In the gas generator of the present disclosure, the cutoff portion can switch between the first section and the second section in the filter to the closed state or the communication state according to the internal pressure of the combustion chamber. The diffusion portion is provided with one or more gas discharge holes in each of a first side wall region located around the first section and a second side wall region located around the second section. Therefore, the portion of the filter through which the combustion gas to be discharged from the gas discharge hole passes can be switched according to the internal pressure of the combustion chamber. When the combustion pressure of the gas generating agent during operation is less than a predetermined critical threshold, the cutoff unit closes the space between the first section and the second section, and when the combustion pressure is equal to or greater than the critical threshold, the cutoff unit communicates the first section and the second section, so that when the ambient 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 ambient 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, and cooling is suppressed. The output of the gas generator is affected by the ambient temperature, and according to the gas generator of the present disclosure, the difference in output due to the difference in ambient temperature can be reduced.
In the filter, the second section may have an inner diameter smaller than that of the first section, and the boundary between the first section and the second section may have a stepped portion, and the cut-off portion may include a cleavage portion formed by: before operation, the combustion chamber is blocked from the first section, the diameter of the cracking part is smaller than the inner diameter of the first section and larger than the inner diameter of the second section, the cracking part is punched out under the pressure above the operation threshold value smaller than the critical threshold value, when the combustion pressure is above the operation threshold value and smaller than the critical threshold value, the cracking part is punched out by the combustion pressure and moves to the step part, thereby blocking the space between the first section and the second section, when the combustion pressure further reaches the critical threshold value or more, at least part of the cracking part passes over the step part by the combustion pressure and moves to the second section, and the first section and the second section are in a communicating state.
In the filter, the second section may have an inner diameter smaller than that of the first section, and the boundary between the first section and the second section may have a stepped portion, and the cut-off portion may include a cleavage portion formed by: before operation, the combustion chamber is closed with the first section, the diameter of the cracking part is smaller than the inner diameter of the first section and larger than the inner diameter of the second section, the cracking part is punched out under the pressure above the operation threshold value smaller than the critical threshold value, the cracking part is provided with a through hole and a sealing component, the sealing component closes the through hole and cracks under the pressure above the critical threshold value, when the combustion pressure is above the operation threshold value and smaller than the critical threshold value, the cracking part is punched out by the combustion pressure and moves towards the step part, thereby closing the first section and the second section, when the combustion pressure further reaches the critical threshold value or higher, the sealing component cracks by the combustion pressure, so that the through hole is opened, and the first section and the second section are in a communicating state.
Further, the cutting unit may include: a first shut-off member that closes between the combustion chamber and the first section before operation, and that communicates the combustion chamber with the first section when the combustion pressure is equal to or higher than an operation threshold value that is smaller than a critical threshold value and lower than the critical threshold value; and a second shut-off member that closes the first section and the second section before operation, and that communicates the first section and the second section when the combustion pressure is equal to or higher than a critical threshold value.
Further, the cutting unit may include: a sealing member that closes a gas discharge hole provided in the first side wall region before operation, and that cracks when the combustion pressure is equal to or higher than an operation threshold value that is smaller than a critical threshold value and is smaller than the critical threshold value; and a shut-off member that closes the first section and the second section before operation, and that communicates the first section and the second section when the combustion pressure is equal to or higher than a critical threshold value.
Further, the cut portion may have a weakened portion that thins the cut portion along the shape of the cleavage portion. In this way, the cracked portion is easily punched out as intended.
Further, the total opening area of the gas discharge holes provided in the second side wall region may be larger than the total opening area of the gas discharge holes provided in the first side wall region. In the case where the gas generator has a plurality of gas discharge holes, the amount of combustion gas per unit time discharged from each gas discharge hole varies depending on the area of the gas discharge hole. By increasing the total opening area of the gas discharge holes provided in the radial direction surrounding the second section located on the closed end side of the diffuser, a large amount of combustion gas can be circulated to the portion on the closed end side of the diffuser in the filter, and the cooling efficiency of the entire combustion gas discharged from the gas discharge holes can be improved.
Further, the gas discharge method of the present disclosure includes: supplying an ignition current to ignite the ignition device to burn the gas generating agent; and a blocking unit configured to block the first section and the second section when the combustion pressure is less than a predetermined critical threshold, and to communicate the first section and the second section when the combustion pressure is greater than or equal to the critical threshold.
In another aspect, a gas generator according to the present disclosure includes: a cylindrical housing forming a housing container extending from one end side to the other end side; an ignition device assembled to the housing; a combustion chamber formed inside the housing, for accommodating a gas generating agent to be ignited by the ignition device; a cylindrical diffusion part inserted into one end of the housing and having a gas discharge hole; and a filter having a main body portion accommodated in the diffusion portion, and having a flange portion protruding radially outward from an inner circumferential direction of the diffusion portion at an end portion on a case side of the main body portion, wherein a first annular surface of a surface of the flange portion facing the main body portion side abuts against the end portion on the case side of the diffusion portion.
The flange portion of the filter is brought into contact with the end portion of the diffusion portion inserted into the case, so that the gap between the diffusion portion and the filter can be closed. Therefore, the combustion gas generated by the gas generating agent is suppressed from being discharged from the gas discharge hole without passing through the filter, between the diffuser portion and the filter. That is, the occurrence of short-circuiting can be suppressed by a simple configuration.
Further, the flange portion may have: a second annular surface facing a back side of the first annular surface; and an annular peripheral surface connecting the first annular surface and the second annular surface, the annular peripheral surface being in contact with the inner periphery of the housing. By abutting the annular peripheral surface of the flange portion against the inner periphery of the housing, the short circuit of the combustion gas can be prevented, and the combustion gas can be suppressed from being discharged from the gas discharge hole so as not to pass through the filter.
The main body of the filter may have a recess extending in the axial direction of the diffuser from the housing side, and the housing may have an orifice plate that defines a combustion chamber and the recess and has a through hole that communicates the combustion chamber with the recess. The combustion chamber and the filter may be divided as such, for example.
Further, the outer diameter of the orifice plate may be smaller than the outer diameter of the flange portion, and the outer peripheral portion 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 peripheral portion of the flange portion.
The diffusion portion may have a closed end with an end closed on the side opposite to the case, the filter may be in contact with the closed end, and the recess of the filter may be a through hole, and the thickness of the filter may be thicker on the closed end side than on the case side. The combustion gas that collides with the closed end of the diffuser portion passes through the filter existing in the vicinity thereof and is discharged from the gas discharge hole. In particular, a large portion of the combustion gas whose flow rate increases after passing through the orifice plate reaches the closed end of the diffuser portion, and the large portion passes through the filter in the vicinity thereof to be discharged from the gas discharge hole. By thickening the thickness of the filter at the closed end side as described above, the cooling performance at the closed end side of the filter can be improved.
The ignition device may be mounted on the other end side of the housing, the gas generator may include a holder that defines a space in which the ignition device is disposed and a combustion chamber, and has an opening, the holder may hold the gas generating agent in the combustion chamber, the holder may include a flat plate portion that supports the gas generating agent, and a connection portion that is provided on an outer periphery of the flat plate portion and abuts against an inner periphery of the housing, and the flat plate portion may include a through hole at a peripheral edge portion thereof. A gap extending relatively straightly toward the diffuser is formed between the gas generating agent and the inner periphery of the case, and combustion gas passing through the through holes provided in the peripheral edge portion of the flat plate portion easily flows in the axial direction of the case along the inner periphery of the case.
The ignition device may be mounted on the other end side of the housing, and the gas generator may include a holder that defines a space in which the ignition device is disposed and a combustion chamber, and has an opening, the holder may hold the gas generating agent in the combustion chamber, the holder may include a flat plate portion that supports the gas generating agent, a stepped portion that is provided along an outer periphery of the flat plate portion so as to be separated from an inner periphery of the housing, and a connection portion that is in contact with the inner periphery of the housing, and the stepped portion may have a through hole. A gap extending relatively straightly toward the diffuser is formed between the gas generating agent and the inner periphery of the case, and combustion gas passing through a through hole provided in a step portion of the retainer provided along the outer periphery of the flat plate portion easily passes through the retainer toward the inner periphery of the case, and flows in the axial direction of the case along the inner periphery of the case.
The ignition device may be mounted on the other end side of the housing, the gas generator may include a holder that defines a space in which the ignition device is disposed and a combustion chamber, and has an opening, the holder may hold the gas generating agent in the combustion chamber, the holder may include a flat plate portion having an outer diameter smaller than an inner diameter of the housing and supporting the gas generating agent, a connection portion abutting against an inner periphery of the housing, and an annular inclined surface having a slope extending from an outer periphery of the flat plate portion toward the connection portion, and the annular inclined surface may have a through hole. A gap extending relatively straightly toward the diffuser is formed between the gas generating agent and the inner periphery of the housing, and combustion gas passing through a through hole provided in an annular peripheral surface having a slope connected from the outer periphery of the flat plate portion easily passes through the retainer toward the inner periphery of the housing, and flows in the axial direction of the housing along the inner periphery of the housing.
Advantageous effects
According to the present disclosure, a technique for reducing a difference in output due to a difference in ambient temperature in a gas generator can be provided.
Drawings
Fig. 1 is an axial schematic cross-sectional view showing an example of a gas generator according to the embodiment.
Fig. 2 is a partial cross-sectional view showing the diffuser and its surroundings.
Fig. 3 is a plan view of the cutoff member when viewed from the diffuser side.
Fig. 4 is a partial cross-sectional view showing an example of a state in which the cutoff member is broken 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 cutoff member is further cracked.
Fig. 6 is a diagram schematically showing the flow of the combustion gas in the example of fig. 4.
Fig. 7 is a diagram schematically showing the flow of the combustion gas in the example of fig. 5.
Fig. 8 is an axial partial schematic 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 first portion is moved by the cleavage of the cleavage portion.
Fig. 10 is a partial cross-sectional view showing an example of a state in which the seal tape is further cracked.
Fig. 11 is an axial partial schematic cross-sectional view showing an example of a gas generator according to the third embodiment.
Fig. 12 is an axial partial schematic cross-sectional view showing an example of a gas generator according to the fourth embodiment.
Fig. 13 is an axial schematic cross-sectional view showing an example of a gas generator according to another embodiment.
Fig. 14 is a partial cross-sectional view showing the diffuser and its surroundings.
Fig. 15 is a schematic diagram for explaining a movement path of the combustion gas in the diffuser portion.
Fig. 16 is a schematic diagram for explaining a movement path of the combustion gas in the combustion chamber.
Fig. 17 is an axial schematic cross-sectional view showing an example of a gas generator according to a modification of the sixth embodiment and embodiment 5.
Fig. 18 is an axial schematic cross-sectional view showing an example of a gas generator according to a modification of the seventh embodiment and embodiment 5.
Detailed Description
Embodiments of the present disclosure will be described below with reference to the accompanying drawings. The configurations and combinations thereof in the embodiments are examples, and the configurations may be added, omitted, substituted, and other modifications as appropriate without departing from the scope of the present invention. The present disclosure is not limited by the embodiments, but only by the claims.
< embodiment 1>
Fig. 1 is an axial schematic cross-sectional view showing an example of a gas generator according to the present embodiment. The gas generator 1 can be used, for example, as a gas generating device for inflating an airbag. The gas generator 1 of fig. 1 includes: a cylindrical housing 2; an ignition device 3 mounted on one axial end side of the housing 2; and a diffusion 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 a known gas generator. For example, the ignition device 3 has: a metallic cup 31 which accommodates an initiating explosive and is sealed; and a pair of conductive pins 32, 32 for receiving supply of electric current from the outside, wherein the cup 31 and the pair of conductive pins 32, 32 are fixed to the metallic igniter holder 33 by a resin member 34. The igniter holding portion 33 of the ignition device 3 is attached to the opening portion on one end side in the axial direction of the housing 2 by, for example, welding over the entire circumference. The full-circle welding is annular welding that is continuous in the circumferential direction, and refers to a state in which two members to be welded are closed without any gap.
The housing 2 is, for example, a cylindrical member having an inner diameter and an outer diameter that are substantially uniform, and forms a housing container of the gas generator 1. The material of the housing 2 is, for example, metal. A cup-shaped partition wall 5 is disposed in the housing 2 at a predetermined distance from the ignition device 3.
In other words, the partition wall 5 is a bottomed tubular member, and its side portion 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 substantially the same as the inner diameter of the housing 2. Therefore, the housing 2 can accommodate the partition wall 5 such that the bottom 53 is located on the diffusion portion 4 side. The outer periphery of the housing 2 and the large diameter portion 51 may be welded, or may be connected by an engagement portion (not shown) such as a recess and projection provided on the inner periphery of the housing 2 and the outer periphery of the large diameter portion 51, which engage with each other. Further, at least one through hole 54 of a predetermined shape is formed in the bottom 53 of the partition wall 5. The through hole 54 is through which combustion products of a gas generating agent described later pass. The small diameter portion 52 of the partition wall 5 may be provided with a through hole at a side portion thereof. Further, the partition wall 5 divides the internal space of the housing 2 into a first combustion chamber 21 (also referred to as "reinforcing chamber") formed between the ignition device 3 and the partition wall 5 and a second combustion chamber 22 formed between the partition wall 5 and the diffusion portion. The side portion (large diameter portion 51 or small diameter portion 52) of the partition wall 5 may be extended to the extent that the partition wall 5 is in contact with the ignition device 3, and the first combustion chamber 21 may be formed by the partition wall 5 and the ignition device 3.
The first combustion chamber 21 contains a first gas generant 61 (also referred to as "charge transfer" or "enhancer"). The second combustion chamber 22 contains a second gas generant 62. The gas generating agent (the first gas generating agent 61 and the second gas generating agent 62) includes a known composition, and is formed of guanidine nitrate (41 wt%), basic copper nitrate (49 wt%), a binder, an additive, and the like, for example. For the shape of each gas generating agent, for example, a granular, disk-like, columnar, single-hole columnar shape having a through hole may be used. However, the gas generating agent is not limited to the above gas generating agent. The first gas generating agent 61 and the second gas generating agent 62 may be the same type, the same shape, and the same size, or may be different types, different shapes, and different sizes. The first gas generating agent 61 may be not filled in the first combustion chamber 21, but the second gas generating agent 62 may be ignited by the ignition device 3. For example, the ignition device 3 may be in contact with the second gas generating agent 62 without providing the partition wall 5 and may be surrounded by the partition wall.
The diffuser 4 is a cup-shaped member fitted to close the other end side of the housing 2, and accommodates the filter 7 therein. In other words, the diffuser 4 is cylindrical with a bottom, and is disposed with its open end facing the second combustion chamber 22. That is, the diffusion section 4 has a side wall 41 and a closed end 42, and an open end side, which is a side opposite to the closed end 42, of the side wall 41 is connected to the housing 2. In the example of fig. 1, the outer diameter of the side wall 41 is substantially the same as the inner diameter of the housing 2, and a part of the open end side of the side wall 41 is accommodated in the housing 2. The open end side of the side wall 41 may be fixed to the housing 2 by caulking, or the diffuser 4 and the housing 2 may be welded. The diffusion section 4 may be integrally formed with the housing 2 by, for example, drawing.
As shown in fig. 1, one or more gas discharge holes 43 are formed in the side wall 41 of the diffuser 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 one or more, respectively. 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 number of each of them is equal. Further, 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 formed at equal intervals in the circumferential direction of the diffuser portion 4, respectively. Further, the first gas discharge holes 431, the second gas discharge holes 432, and the third gas discharge holes 433 are arranged in this order from the open end side (the second combustion chamber 22 side) of the diffuser 4 toward the closed end side, and the opening area (i.e., diameter) of each discharge hole increases as the distance from the second combustion chamber 22 increases. Therefore, in the present embodiment, the total opening area of the first gas discharge hole 431, the second gas discharge hole 432, and the third gas discharge hole 433 is increased in this order. Here, the "total opening area" refers to the sum of the opening areas of the one or more gas discharge holes 43 (i.e., each of 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).
Further, a receiving space for receiving the filter 7 is formed in the cup-shaped diffusion portion 4. At least a part of the filter 7 is accommodated in the accommodation space of the diffuser 4. When the combustion gas generated by the gas generating agents 61, 62 passes through the filter 7, the filter 7 functions as a cooling unit that cools the combustion gas, and the combustion gas is filtered by capturing combustion residues of the combustion gas.
Fig. 2 is a partial cross-sectional view showing the diffuser and its surroundings. The filter 7 has a cylindrical shape having an outer diameter substantially equal to the inner diameter of the diffuser 4, and extends from the open end side of the diffuser 4 toward the closed end 42 side. In addition, hollow flow paths (71, 72) through which combustion gas passes are provided in the filter 7. The flow path includes a first section 71 located on the open end side of the diffuser 4 and a second section 72 located on the closed end side of the diffuser 4. The portion of the sidewall 41 of the diffusion section 4 around the radial direction of the first section 71 (i.e., the region of the sidewall 41 corresponding to the first section 71) is referred to as a first sidewall region, and the portion of the sidewall 41 of the diffusion section 4 around the radial direction of the second section 72 (i.e., the region of the sidewall 41 corresponding to the second section 72) is referred to as a second sidewall region. In other words, the portion around the first section 71 in the radial direction of the side wall 41 of the diffusion section 4 is a portion of the side wall 41 located on the outer side of the first section 71 in the radial direction orthogonal to the axial direction thereof. Similarly, a portion around the second section 72 in the radial direction of the side wall 41 of the diffusion section 4 is a portion of the side wall 41 located on the outer side of the second section 72 in the radial direction orthogonal to the axial direction thereof. 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 communicates with the second section 72, and the combustion gas can flow from the first section 71 into the second section 72. Further, the inner diameter of the second section 72 is smaller than the inner diameter of the first section 71. Therefore, the filter 7 has a stepped portion 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 diffusion section 4 may be closed by the body of the filter 7, and the flow path may not pass through the filter 7. The main body portion of the filter 7 comprises a first zone 74 present radially outside the first section 71 and a second zone 75 present radially outside the second section 72. The outer diameter of the filter 7 is constant, and therefore the thickness of the first region 74 is thinner than the thickness of the second region 75.
The filter 7 may be obtained by accommodating a member obtained by plain weaving a metal wire in a molding die, compression molding the member into a cylindrical shape, and providing through holes corresponding to the first section 71 and the second section 72. Further, the filter 7 may be obtained by winding a metal wire rod around a rod-shaped core material formed in the shape of the first section 71 and the second section 72 in a multi-layer manner, and forming the wire rod into a column shape having a mesh by crossing the wire rod. Further, the filter 7 may be obtained by rolling up a sheet-like porous plate such as expanded metal, punched metal, a metal mesh plate, a plain woven metal mesh, or a densely woven metal mesh into a cylindrical shape, and providing the obtained member with through holes corresponding to the first section 71 and the second section 72.
As described above, the filter 7 is a metal filter having a solid body except the first section 71 and the second section 72 and formed in a cylindrical shape as a whole. The metal may be stainless steel, iron, or the like, or may be plated or coated with copper, nickel, or the like. The term "solid" means that a metal material is contained at a predetermined density in order to collect combustion residues of combustion gas and cool the combustion gas. That is, the combustion gas can pass through not only the flow path but also the first region 74 and the second region 75 of the filter 7 functioning as the cooling portion. However, compared to the first region 74 and the second region 75, the combustion gas easily flows in the first section 71 and the second section 72.
The filter 7 further includes a flange 76, and the flange 76 protrudes from the diffuser 4 toward the second combustion chamber 22 and has an outer diameter larger than an inner diameter of the diffuser 4. In a state where 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 76 and the housing 2.
The gas generator 1 is provided with a cutoff portion 8 between the second combustion chamber 22 and the diffusion portion 4. The cutoff portion 8 of the present embodiment is a disk-shaped metal member, and closes the diffusion portion 4 side of the second combustion chamber 22. That is, the diameter of the cutoff portion 8 is substantially the same as the inner diameter of the second combustion chamber 22, and the casing 2 and the cutoff portion 8 are welded over the entire circumference from the outside of the casing 2. In fig. 2, the welded portions are shown by way of example with black triangles.
Fig. 3 is a plan view of the cutoff member when viewed from the diffuser side. The cutoff portion 8 shown in fig. 2 and 3 is provided with three portions having different thicknesses in the axial direction of the gas generator 1 concentrically. As can be seen from fig. 2, the central first portion 81 is thicker than the second portion 82 located around the first portion 81. Further, the diameter of the first portion 81 is smaller than the inner diameter of the first section 71 and larger than the inner diameter of the second section 72. The first portion 81 has a part on the diffusion portion 4 side inserted into the first section 71. The third portion 83 located around the second portion 82 protrudes toward the diffuser 4 side and is sandwiched between the housing 2 and the flange 76 of the filter 7. The first portion 81 is a split portion that is punched out at the boundary with the second portion 82 by the combustion pressure of the gas generating agents 61, 62 when the gas generator 1 is in operation. A fragile portion such as a groove or a slit for thinning the thickness of the cutoff portion 8 may be provided locally or entirely between the first portion 81 and the second portion 82.
The cutoff portion 8 is broken in stages according to an increase in the internal pressure of the first combustion chamber 21 and the second combustion chamber 22 caused by the combustion gas. Specifically, when the internal pressure first reaches the first threshold value, the cutoff portion 8 is broken along the boundary between the first portion 81 and the second portion 82, and the first portion 81 is die-cut. The first threshold value is a combustion pressure value of the gas generating agent generated when the gas generator 1 is operated, also referred to as an operation threshold value in the present disclosure. The first portion 81 of the cutoff portion 8 moves to the step 73 at the boundary between the first portion 81 and the second portion 82 by the flow of the combustion gas.
Fig. 4 is a partial cross-sectional view showing an example of a state in which the cutoff member is broken and the first portion is moved. In the state of fig. 4, the first portion 81 of the cutoff portion 8 cuts off the inflow of the combustion gas from the first section 71 to the second section 72. The combustion pressure of the gas generating agent is set in advance as: in the room temperature state, the first threshold value is exceeded and gradually increases, but the second threshold value, which will be described later, is not exceeded. Therefore, when operating at room temperature, the first portion 81 is not broken but continues to block the second section. In addition, in the operation under the high temperature environment, after the first threshold is generated in the first portion 81, a pressure equal to or higher than a second larger threshold is further reached, and the pressure is applied to the first portion 81. Thus, the first portion is cracked, and the first section 71 communicates with the second section 72. The second threshold is also referred to as a critical threshold in this disclosure.
Fig. 5 is a partial cross-sectional view showing an example of a state in which the first portion of the cutoff member is further cracked. In fig. 5, the center of the first portion 81 is further punched, and a part of the first portion 81 is moved toward the closed end side of the diffuser 4. The first portion 81 may further include a frangible portion (not shown) such as a groove or a slit designed to be broken by a pressure equal to or higher than the second threshold value. The first portion 81 may be configured to rupture at a pressure equal to or higher than the second threshold value to allow the first section 71 to communicate with the second section 72. For example, instead of punching out a part of the first portion 81 as shown in fig. 5, the whole first portion 81 may be bent and moved toward the second section 72. As described above, the cutting portion 8 is broken in stages to close or open the space between the first section 71 and the second section 72.
< action >
In a state where 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, so that the ignition device 3 can be supplied with electricity. In this state, when a sensor (not shown) mounted on an automobile or the like senses an impact, the ignition device 3 is operated by an ignition current supplied to the pair of conductive pins 32, 32. The ignition device 3 burns the primary explosive in the cup 31 and discharges the combustion product to the outside of the cup 31. Further, the first gas generating agent 61 is ignited by a flame, combustion gas, which is a combustion product of the primary explosive. Further, the first gas generating agent 61 generates combustion gas as a combustion product, and the combustion gas ignites the second gas generating agent 62 of the second combustion chamber 22 through the through holes 54 of the partition wall 5. In addition, the second gas generating agent 62 also generates combustion gas as a combustion product.
In other words, the example of fig. 4 shows a state when the gas generator 1 is operated. Fig. 6 is a diagram schematically 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 low. At this time, the pressures inside the first combustion chamber 21 and the second combustion chamber 22 are designed to exceed the first threshold value and rise to a value lower than the second threshold value. Therefore, at the point in time 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 portion 81 of the cutoff portion 8 is cracked, and the first portion 81 stays at the stepped portion 73. Further, between the first section 71 and the second section 72, the flow of the combustion gas is interrupted by the first portion 81 of the interruption portion 8. Accordingly, as shown in fig. 6, the combustion gas is filtered and cooled mainly through the first region 74 in the filter 7, and is discharged mainly from the first gas discharge holes 431 and the second gas discharge holes 432 of the diffuser 4. A part of the combustion gas also flows into the second region 75 in the main body portion of the filter 7 and is discharged from the third gas discharge hole 433, but the amount thereof is small. Therefore, the proportion of the combustion gas passing through the second region 75 is very small, and thus excessive cooling is suppressed.
In other words, the example of fig. 5 shows the operation of the gas generator 1 in an environment higher than a predetermined temperature. Fig. 7 is a diagram schematically showing 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 example shown in fig. 4 and 6. The temperature of the generated combustion gas is also higher than the temperature of the combustion gas generated when operating at normal temperature. At this time, the pressures inside the first combustion chamber 21 and the second combustion chamber 22 are designed to exceed the above-described second threshold value after reaching the first threshold value. Therefore, the periphery of the first portion 81 of the cutoff portion 8 is cracked by the pressure of the combustion gas of the first combustion chamber 21 and the second combustion chamber 22, the first portion 81 of the cutoff portion 8 moves to the step 73 of the filter 7, and the first portion 81 is further cracked, and the first section 71 communicates with the second section 72. Accordingly, as shown in fig. 7, the combustion gas is filtered and cooled through the first region 74 and the second region 75 in the filter 7, 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 4.
< Effect >
In general, the output of a gas generator varies according to the ambient temperature at the time of operation. That is, when the ambient temperature increases, the combustion rate of the gas generating agent increases, and therefore, even in the case of the same specification gas generator, the output during operation is easily increased in a high temperature environment. In the present embodiment, the temperature of the combustion gas generated in the first combustion chamber 21 and the second combustion chamber 22 is higher in the environment (fig. 7) at a predetermined temperature or higher than in the environment (fig. 6) at a temperature lower than the predetermined temperature. On the other hand, in the example of fig. 7, a wider portion of the filter 7 can be used as a cooling portion than in the example of fig. 6, and therefore the cooling efficiency becomes high. This suppresses the rise in the temperature of the combustion gas, and can suppress the variation in the output performance of the gas generator due to the variation in the ambient temperature during operation. In the example of fig. 6, the region of the filter 7 through which the combustion gas flows is narrowed, and cooling of the combustion gas is suppressed as compared with the example of fig. 7. The combustion gas discharged from the gas generator 1 has a temperature at which the combustion gas discharged from the first gas discharge hole 431, the combustion gas discharged from the second gas discharge hole 432, and the combustion gas discharged from the third gas discharge hole 433 are mixed, and according to the gas generator 1 of the present disclosure, a difference in output due to a difference in ambient temperature can be reduced.
< embodiment 2>
Fig. 8 is an axial partial schematic cross-sectional view showing an example of a gas generator according to the second embodiment. In the present embodiment, the cutoff portion 8 is different from the first embodiment. Accordingly, the same components as those of the first embodiment are denoted by the corresponding reference numerals or omitted from illustration.
The cutoff portion 8 in fig. 8 has a through hole 84 in the center of the first portion 81, and the through hole 84 is closed by a seal tape 85. The seal tape 85 is a seal member having an adhesive layer formed on one surface of an aluminum foil or a stainless steel foil, for example. Further, in the present embodiment, the sealing tape 85 is designed to require a large force for cracking as compared to the boundary of the first portion 81 and the second portion 82. That is, as in the first embodiment, when the internal pressure of the first combustion chamber 21 and the second combustion chamber 22 exceeds the first threshold value due to the combustion gas, the boundary between the first portion 81 and the second portion 82 is broken in the cutoff portion 8. When the internal pressure of the first combustion chamber 21 and the second combustion chamber 22 becomes equal to or higher than the second threshold value higher than the first threshold value due to the combustion gas, the seal tape 85 is broken. The breaking strength of the seal tape 8 may be adjusted by changing the material and thickness of the seal tape 8 or by overlapping two or more seal tapes 85. In the present embodiment, the first portion 81, the second portion 82, and the seal tape 85 can be individually designed in strength, and thus can be said to be easy to design.
Fig. 9 is a partial cross-sectional view showing an example of a state in which the first portion is moved by the cleavage of the cleavage portion. In the present embodiment, the first portion 81 of the cutoff portion 8 cuts off the inflow of the combustion gas from the first section 71 to the second section 72 when moving to the step 73 of the filter 7. Fig. 10 is a partial cross-sectional view showing an example of a state in which the seal tape is further broken. When the pressure equal to or higher than the second threshold value is applied, the seal tape 85 is further broken, and the through hole 84 is opened, so that the first section 71 communicates with the second section 72. As described above, the cutting portion 8 is broken in stages to close or open the space between the first section 71 and the second section 72. The size of the portion of the filter 7 serving as the cooling portion can be changed stepwise according to the ambient temperature by the gas generator 1 of the present embodiment.
< embodiment 3>
Fig. 11 is an axial partial schematic cross-sectional view showing an example of a gas generator according to the third embodiment. In the present embodiment, the filter 7 and the cutoff portion 8 are different from the first embodiment and the second embodiment. The same components as those of the first and second embodiments are denoted by the corresponding reference numerals or omitted from illustration.
In the present embodiment, the cutoff portion 8 includes a first cutoff member 86 and a second cutoff member 87 that are separate. 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 therebetween. The first cutoff member 86 is a component corresponding to the cutoff portion 8 in the first embodiment, and is designed to crack when the pressure at the time of combustion exceeds at least the first threshold value. In the present embodiment, the portion of the first cutting member 86 that is cut out at the time of cracking is smaller than the inner diameter of the first section 71 and the inner diameter of the second section 72. In the present embodiment, the inner diameter of the first section 71 may be the same as the inner diameter of the second section 72, 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 cut-off member 87 may be substantially the same as the inner diameter of the diffusion portion 4, and the diffusion portion 4 and the second cut-off member 87 may be welded from the outside of the diffusion portion 4. Further, the second cutoff member 87 is designed to fracture at a pressure above a second threshold that is greater than the first threshold. Therefore, the cutoff portion 8 of the present embodiment can also be broken in stages according to the pressure, so that the second combustion chamber 22 and the first section 71 and the second section 72 are opened in sequence. Therefore, with the gas generator 1 of the present embodiment, the size of the portion of the filter 7 serving as the cooling portion can be changed stepwise according to the ambient temperature. The following filter 7 may be used: the filter 7 is arranged such that the first region 74 meets the second region 75, and an annular groove for holding the second blocking member 87 is provided between the first region 74 and the second region 75.
< embodiment 4>
Fig. 12 is an axial partial schematic cross-sectional view showing an example of a gas generator according to the fourth embodiment. In the present embodiment, the filter 7 and the cutoff portion 8 are different from the other embodiments. The same components as those of the other embodiments are denoted by the corresponding reference numerals or omitted from illustration.
In the present embodiment, as in the third embodiment, the first region 74 and the second region 75 of the filter 7 are formed as separate pieces with a gap therebetween. The inner diameter of the first section 71 may be the same as the inner diameter of the second section 72, 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 is provided to communicate with the first section 71 of the filter 7, 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 by a metal mesh (not shown) having a mesh smaller than the second gas generating agent 62, for example, and only the second combustion chamber 22 may be filled with the second gas generating agent 62.
The cutoff portion 8 of the present embodiment includes a seal tape 88 and a third cutoff member 89. The sealing tape 88 of the present embodiment is also a sealing tape in which an adhesive layer is formed on one surface of an aluminum foil or a stainless steel foil, for example. The seal tape 88 closes all the gas discharge holes 431 and 432 provided around the radial direction of the first section 71. Further, the sealing band 88 of the present embodiment is designed to crack when the combustion pressure exceeds a first threshold. The third cutoff member 89 is the same member as the second cutoff member 87 of the third embodiment. That is, the third cutting 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 cutoff member 89 is substantially the same as the inner diameter of the diffusion portion 4, and the diffusion portion 4 and the third cutoff member 89 are welded from the outside of the diffusion portion 4 over the entire circumference. Further, the third interception member 89 is designed to crack at a pressure above a second threshold value greater than the first threshold value.
As described above, in the gas generator 1 of the present embodiment, the second combustion chamber 22 is initially opened from the first section 71. Further, the sealing tape 88 closing the gas discharge hole 431 and the gas discharge hole 432 and the third shut-off member 89 between the first section 71 and the second section 72 are broken stepwise according to the pressure, so that the gas discharge hole 43 is opened. Therefore, with the gas generator 1 of the present embodiment, the size of the portion of the filter 7 serving as the cooling portion can be changed stepwise according to the ambient temperature.
< embodiment 5>
Fig. 13 is an axial schematic cross-sectional view showing an example of a gas generator according to another embodiment. In the present embodiment, the same constituent elements as those of the above embodiment are denoted by the corresponding reference numerals or omitted drawings.
In the present embodiment, the cutoff portion 8 is a perforated plate having a hole in the center in advance, and is not a cutoff portion that is broken in stages according to the internal pressure of the gas generator 1. In addition, a hollow portion 23 that does not hold a gas generating agent is formed in the interior of the housing 2 instead of the first combustion chamber 21. That is, the casing 2 is divided by the partition wall 5 into a hollow portion 23 formed between the ignition device 3 and the partition wall 5 and a combustion chamber 24 formed between the partition wall 5 and the diffusion portion 4.
In the present embodiment, the periphery of the cutoff portion 8 is not in contact with the inner periphery of the housing 2. A crank-shaped boundary is formed between the filter 7 and the housing 2 and the diffuser 4 when viewed in longitudinal section. The outer diameter of the cutoff 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 cutoff portion 8 and the housing 2. Such a cutoff portion 8 may be sandwiched between the filter 7 and the gas generating agent 6, or the cutoff portion 8 and the filter 7 may be welded at least in part. When the filter 7 has a through hole or a recess, the first portion 81 of the cutoff portion 8 may be inserted into the through hole or the recess of the filter 7 to perform alignment. The cutoff portion 8 has one or more through holes 84, and is not shielded by a sealing member or the like in the present embodiment. In such a configuration, the gas generator 1 of the present embodiment suppresses the combustion gas from being discharged from the gas discharge holes 43 of the diffuser portion 4 so as not to pass through the filter 7.
In the present 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 also collectively referred to as "body portion") and a flange portion 76. In addition, in a state in which the filter 7 is inserted into the diffusion section 4, the flange 76 of the filter 7 abuts against the open end of the diffusion section 4. Fig. 14 is a partial cross-sectional view showing the diffuser and its surroundings. The flange portion 76 of the filter 7 includes: the first annular surface 761 is in contact with the open end of the diffusion section 4 in a state in which the filter 7 is inserted into the diffusion section 4; a second annular surface 762 located on the opposite side of the first annular surface 761 and facing the combustion chamber 24 side; and an annular peripheral surface 763 connecting the first annular surface 761 and the second annular surface 762, facing the outer peripheral direction.
The first annular surface 761 abuts against the open end of the diffuser 4. In particular, when the gas generator 1 is operated, 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 biased in the direction of the diffuser 4. At this time, the gap between the first annular surface 761 and the open end of the diffuser 4 disappears, and therefore, the combustion gas is suppressed from being discharged along the crank-shaped boundary when viewed in longitudinal section between the filter 7 and the housing 2 and diffuser 4 without passing through the filter 7. At least a part of the first annular surface 761 may be welded to the open end of the diffuser 4.
The annular peripheral surface 763 may be press-fitted so as to abut against the inner periphery of the housing 2. With this configuration, the combustion gas is also suppressed from being discharged along the crank-shaped boundary between the filter 7 and the housing 2 and the diffuser 4 when viewed in longitudinal section without passing through the filter 7.
In addition, a region along the outer periphery (also referred to as an "outer periphery") of the second annular surface 762 is exposed to the combustion chamber 24 without being covered by the cutoff portion 8. Therefore, the combustion gas also enters the filter 7 from the outer peripheral portion of the second annular surface 762. Fig. 15 is a schematic diagram for explaining a movement path of the combustion gas in the diffuser portion. In fig. 15, a movement path of the combustion gas in the diffuser 4 is shown by way of example with a broken-line arrow. The combustion gas having entered the filter 7 from the outer peripheral portion of the second annular surface 762 passes through the filter 7 a longer distance or a larger number of times than the combustion gas having entered the filter 7 from the flow path in the filter 7 through the through hole 84 of the shut-off portion 8. Therefore, it can be said that by introducing the combustion gas into the filter 7 from the outer peripheral portion of the second annular surface 762, the cooling efficiency of the combustion gas and the trapping effect of the combustion residues are improved.
In addition, a part of the combustion gas that has penetrated through the through hole 84 of the shut-off portion 8 and entered the flow path in the filter 7 collides with the closed end 42 of the diffuser portion 4 and changes direction, and passes through the filter 7 and is discharged from the gas discharge hole 43. By the filter 7 being in contact with the closed end 42 of the diffuser 4, the combustion gas is prevented from being discharged along the boundary between the filter 7 and the closed end 42 without passing through the filter 7. After the combustion gas passes through the through-holes 84 of the cutoff portion 8, which is a perforated plate, the flow rate of the combustion gas increases, and a large amount of the combustion gas reaches the closed end 42 of the diffuser portion 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 4, the cooling efficiency of the combustion gas reaching the closed end 42 and the trapping effect of the combustion residues can be improved. In the present embodiment, the flow path formed in the filter 7 may be a recess that is closed at the closing end 42 side of the diffuser 4, instead of a through hole, and the filter 7 may not have the flow paths (71, 72).
In the present embodiment, the casing 2 is divided by the partition wall 5 into a hollow portion 23 formed between the ignition device 3 and the partition wall 5 and a combustion chamber 24 formed between the partition wall 5 and the diffusion portion 4. The hollow portion 23 does not contain the gas generating agent, but may be filled with the gas generating agent as shown in fig. 1. Further, the combustion chamber 24 holds the 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 wall 5 functions as a holder (also referred to as a "holder") for pressing the granular gas generating agent 6 stored in the combustion chamber 24 in the direction of the diffuser 4 to restrict the shaking of the gas generating agent 6. That is, the partition wall 5 is pressed into the housing 2, for example, and the large diameter portion 51 in the side portion of the partition wall 5 functions as a connecting portion that abuts against the inner periphery of the housing 2. The bottom 53 of the partition wall 5 is a flat plate portion, and presses the granular gas generating agent 6 stored in the combustion chamber 24 toward the diffusion portion 4.
The partition wall 5 does not have a through hole 54 in the center of the bottom 53, but has a through hole 54 near the outer periphery of the bottom 53. For example, a plurality of through holes 54 are provided along the outer periphery of the bottom 53. Fig. 16 is a schematic diagram for explaining a movement path of the combustion gas in the combustion chamber. The combustion chamber 24 is filled with a granular gas generating agent 6. The gas generating agent 6 is, for example, cylindrical in shape, and gaps are irregularly 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 drawings.
In the case of combustion gas flowing in the combustion chamber 24, it moves through between the staggered-fill gas generants 6, and thus has a path length longer than the length of the housing 2. However, since the inner peripheral surface of the case 2 and the gas generating agent 6 do not intersect with each other, a gap is formed which extends relatively straight along the inner peripheral surface of the case 2 to the diffuser 4. Therefore, as shown by the broken-line arrows in fig. 16, the combustion gas can flow relatively straightly in the axial direction of the casing 2 along the inner peripheral surface of the casing 2. By providing the through-holes 54 near the outer periphery of the bottom 53 of the partition wall 5 as described above, the combustion products of the ignition device 3 passing through the through-holes 54 easily flow along the inner peripheral surface of the housing 2 in the combustion chamber 24, and the time from the operation of the gas generator 1 to the discharge of the combustion gas can be shortened. In this case, of course, the through hole 54 may also be provided at the center of the bottom 53.
< embodiment 6>
Fig. 17 is an axial schematic cross-sectional view showing an example of a gas generator according to a modification of the sixth embodiment and embodiment 5. In the present embodiment, the same constituent elements as those of the above embodiment are denoted by the corresponding reference numerals or omitted drawings.
Fig. 17 shows an igniter, a hollow portion and the surroundings thereof. The partition wall 5 of the gas generator 1 of the present embodiment has a through hole 54 in the small diameter portion 52 in the side portion. The partition wall 5 does not have a through hole 54 at the bottom 53. In the case of such a partition wall 5, the combustion products of the ignition device 3 are discharged from the hollow portion 23 toward the inner circumferential combustion chamber 24 of the casing 2. Therefore, the combustion products of the ignition device 3 easily pass through a path along the inner peripheral surface of the housing 2 as indicated by a broken-line arrow in fig. 16. That is, the time from the operation of the gas generator 1 to the discharge of the combustion gas can be shortened. The gas generating agent 6 is not present 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 in the axial direction of the housing 2 of the small diameter portion 52 is smaller than the diameter and the height of the gas generating agent 6, which is, for example, cylindrical.
< embodiment 7>
Fig. 18 is an axial schematic cross-sectional view showing an example of a gas generator according to a modification of the seventh embodiment and embodiment 5. In the present embodiment, the same constituent elements as those of the above embodiment are denoted by the corresponding reference numerals or omitted drawings.
Fig. 18 shows an igniter and a hollow portion and its surroundings. The partition wall 5 of the gas generator 1 of the present embodiment does not have the small diameter portion 52 at the side portion thereof, but has an annular inclined surface 55 having a slope connecting from the large diameter portion 51 toward 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 53. Even with such a partition wall 5, combustion products of the ignition device 3 are discharged from the hollow portion 23 toward the inner circumferential combustion chamber 24 of the housing 2. Therefore, the combustion products of the ignition device 3 easily pass through a path along the inner peripheral surface of the housing 2 as indicated by a broken-line arrow in fig. 16. That is, the time from the operation of the gas generator 1 to the discharge of the combustion gas can be shortened. The gas generating agent 6 is not present in the annular space between the annular inclined surface 55 and the housing 2. That is, the radial length or the axial length of the casing 2 of the annular space is smaller than the diameter and the height of the gas generating agent 6 having a cylindrical shape, for example.
< others >
The embodiments of the gas generator of the present disclosure have been described above, but the aspects disclosed in the present specification may be combined with other features disclosed in the present specification. For example, the first cutting member 86 and the second cutting member 87 in fig. 11, and the third cutting member 89 in fig. 12 may each have a through hole and a sealing tape closing the through hole, and the sealing tape may be broken by a predetermined pressure.
Further, in the above-described embodiment, the further the first gas discharge hole 431, the second gas discharge hole 432, and the third gas discharge hole 433 are from the second combustion chamber 22, the larger the opening areas thereof are respectively. It may be: the total opening area of the gas discharge holes provided in the side wall of the diffusion portion in the second side wall region located around the second section 72 is larger than the total opening area of the gas discharge holes provided in the side wall of the diffusion portion in the first side wall region located around the first section 71. When the internal pressure of the gas generator 1 is sufficiently high, the ratio of the amounts per unit time of the amounts of the combustion gas discharged from the respective gas discharge holes 43 corresponds to the ratio of the areas of the respective gas discharge holes 43. Therefore, by increasing the opening area of the third gas discharge hole 433, the combustion gas can be made to pass through the second region 75 of the filter 7 as much as possible in the state where the first region 71 and the second region 72 are communicated, and the cooling efficiency can be improved. The opening area (diameter) of each of the gas discharge holes 43 provided in the second side wall region may be larger than the opening area (diameter) of each of the gas discharge holes 43 provided in the first side wall region, or the number of the gas discharge holes 43 may be increased in the second side wall region by making the opening area (diameter) of each of the gas discharge holes the same. The opening ratio of the gas discharge holes 43 to the area of the diffuser 4 may be higher in the second side wall region than in the first side wall region. However, the opening area and shape of the gas discharge hole 43 are not limited to those shown in the drawings, and for example, the opening area may be the same in all the regions, or the opening ratio of the first side wall region may be higher than that of the second side wall region.
The cutoff portion 8 of the gas generator 1 may be configured to switch the region of the filter 7 serving as the cooling portion in three or more stages according to the internal pressure of the combustion chamber. The gas generator 1 may be incorporated in a device other than the airbag.
The first combustion chamber 21 and the second combustion chamber 22 shown in embodiment modes 1 to 4 may be applied to embodiment modes 5 to 7, or the hollow portion 23 and the combustion chamber 24 shown in embodiment modes 5 to 7 may be applied to embodiment modes 1 to 4.
Description of the reference numerals
1: a gas generator;
2: a housing;
21: a first combustion chamber;
22: a second combustion chamber;
23: a hollow portion;
24: a combustion chamber;
3: an ignition device;
4: a diffusion section;
41: a sidewall;
42: a closed end;
43 (431-433): a gas discharge hole;
5: a partition wall;
6: a gas generating agent;
61: a first gas generant;
62: a second gas generant;
7: a filter;
71: a first section;
72: a second section;
73: a step portion;
74: a first region;
75: a second region;
8: a cutting part;
81: a first portion;
82: a second portion;
83: a third section;
84: a through hole;
85: a sealing tape;
86: a first cutoff member;
87: a second cutoff member;
88: a sealing tape;
89: and a third cutoff member.
Claims (16)
1. A gas generator, the gas generator comprising:
a housing forming a housing container extending from one end side to the other end side;
an ignition device mounted to the housing;
a combustion chamber formed inside the housing and accommodating a gas generating agent to be ignited by the ignition device;
a diffusion section provided at the other end side of the housing, the diffusion section including a closed end having a closed end and a side wall having a plurality of gas discharge holes;
a filter at least a part of which is accommodated in the diffusion section, wherein the filter has a hollow flow path extending from the combustion chamber side to the closed end side, and the flow path includes a first section having one end connected to the combustion chamber and a second section having the other end connected to the first section; and
a cutoff unit that, when the combustion pressure of the gas generating agent during operation is less than a predetermined critical threshold, closes the space between the first section and the second section, and when the combustion pressure is equal to or greater than the critical threshold, opens the first section and the second section to be in communication,
The side wall of the diffusion part comprises a first side wall area positioned around the first section and a second side wall area positioned around the second section, and more than one gas discharge hole is respectively arranged in the first side wall area and the second side wall area.
2. The gas generator of claim 1, wherein,
in the filter, the inner diameter of the second section is smaller than the inner diameter of the first section, a step part is arranged at the boundary between the first section and the second section,
the cutoff portion includes a cleavage portion formed as: before operation, closing the space between the combustion chamber and the first section, wherein the diameter of the cracking part is smaller than the inner diameter of the first section and larger than the inner diameter of the second section, the cracking part is punched out under the pressure above the operation threshold value smaller than the critical threshold value,
when the combustion pressure is equal to or higher than the operation threshold value and lower than a critical threshold value, the crack is punched out by the combustion pressure and moves toward the step portion, thereby closing the space between the first section and the second section,
when the combustion pressure further exceeds the critical threshold, at least a part of the cleavage portion moves over the step portion and toward the second section by the combustion pressure, and the first section and the second section are placed in communication.
3. The gas generator of claim 1, wherein,
in the filter, the inner diameter of the second section is smaller than the inner diameter of the first section, a step part is arranged at the boundary between the first section and the second section,
the cutoff portion includes a cleavage portion formed as: before operation, closing the space between the combustion chamber and the first section, wherein the diameter of the cracking part is smaller than the inner diameter of the first section and larger than the inner diameter of the second section, the cracking part is punched out under the pressure above the operation threshold value smaller than the critical threshold value,
the cleavage portion has a through hole and a sealing member that closes the through hole and cleaves at a pressure equal to or higher than the critical threshold value,
when the combustion pressure is equal to or higher than the operation threshold value and lower than a critical threshold value, the crack is punched out by the combustion pressure and moves toward the step portion, thereby closing the space between the first section and the second section,
when the combustion pressure further exceeds the critical threshold, the seal member is broken by the combustion pressure, and the through-hole is opened, so that the first section and the second section are in communication.
4. The gas generator of claim 1, wherein,
the cutoff portion includes: a first shut-off member that closes between the combustion chamber and the first section before operation, and that breaks when the combustion pressure is an operation threshold value smaller than the critical threshold value, thereby allowing the combustion chamber to communicate with the first section; and a second shut-off member that closes between the first section and the second section before operation, and communicates the first section with the second section when the combustion pressure further exceeds the critical threshold.
5. The gas generator of claim 1, wherein,
the cutoff portion includes: a sealing member that closes the gas discharge hole provided in the first side wall region before operation, and that cracks when the combustion pressure is an operation threshold value smaller than the critical threshold value; and a shut-off member that closes between the first section and the second section before operation, and communicates the first section with the second section when the combustion pressure further exceeds the critical threshold value.
6. A gas generator according to claim 2 or 3, wherein,
The cut-off portion includes a weakened portion that thins the cut-off portion along the shape of the cleavage portion.
7. The gas generator according to any one of claims 1 to 6, wherein,
the total opening area of the gas discharge holes provided in the second side wall region is larger than the total opening area of the gas discharge holes provided in the first side wall region.
8. A gas discharge method for a gas generator, wherein the gas generator comprises:
a housing forming a housing container extending from one end side to the other end side;
an ignition device mounted to the housing;
a combustion chamber formed inside the housing and accommodating a gas generating agent to be ignited by the ignition device;
a diffusion section provided at the other end side of the housing, the diffusion section including a closed end having a closed end and a side wall having a plurality of gas discharge holes;
a filter at least a part of which is accommodated in the diffusion section, wherein the filter has a hollow flow path extending from the combustion chamber side to the closed end side, and the flow path includes a first section having one end connected to the combustion chamber and a second section having the other end connected to the first section; and
A cutoff unit that, when the combustion pressure of the gas generating agent during operation is less than a predetermined critical threshold value, closes the first section and the second section, and when the combustion pressure exceeds the critical threshold value, opens the first section and the second section,
the side wall of the diffusion part comprises a first side wall area positioned around the first section and a second side wall area positioned around the second section, more than one gas exhaust hole is respectively arranged in the first side wall area and the second side wall area,
the gas discharge method includes:
supplying an ignition current to ignite the ignition device to burn the gas generating agent; and
when the combustion pressure is less than a predetermined critical threshold, the blocking portion closes the first section and the second section, and when the combustion pressure is equal to or greater than the critical threshold, the first section and the second section are placed in communication.
9. A gas generator, the gas generator comprising:
a cylindrical housing forming a housing container extending from one end side to the other end side;
An ignition device mounted to the housing;
a combustion chamber formed inside the housing and accommodating a gas generating agent to be ignited by the ignition device;
a cylindrical diffusion section inserted into one end side of the housing and having a gas discharge hole; and
a filter having a main body portion accommodated in the diffusion portion and having a flange portion protruding radially outward from an inner periphery of the diffusion portion at an end portion of the main body portion on the housing side,
a first annular surface of the flange portion facing the main body portion side is in contact with an end portion of the diffusion portion on the housing side.
10. The gas generator of claim 9, wherein,
the flange portion has: a second annular surface facing a back side of the first annular surface; and an annular peripheral surface connecting the first annular surface and the second annular surface,
the annular peripheral surface is in contact with the inner periphery of the housing.
11. The gas generator according to claim 9 or 10, wherein,
the main body portion of the filter has a recess extending from the housing side in an axial direction of the diffuser portion,
an orifice plate is provided in the housing, the orifice plate dividing the combustion chamber and the recess, and having a through hole for communicating the combustion chamber with the recess.
12. The gas generator of claim 10, wherein,
the main body portion of the filter has a recess extending from the housing side in an axial direction of the diffuser portion,
an orifice plate is provided in the housing, the orifice plate dividing the combustion chamber and the recess, and having a through hole for communicating the combustion chamber with the recess,
the outer diameter of the orifice plate is smaller than the outer diameter of the flange portion, and the outer peripheral portion of the second annular surface of the flange portion is exposed to the housing side.
13. The gas generator according to claim 11 or 12, wherein,
the diffuser portion has an end-blocked end on the opposite side of the housing,
the filter is abutted against the closed end, the concave portion of the filter is a through hole, and the thickness of the filter is thicker at the closed end side than at the shell side.
14. The gas generator according to any one of claims 9 to 13, wherein,
the ignition device is mounted on the other end side of the housing,
the gas generator has a holder that divides a space in which the ignition device is disposed and the combustion chamber, and has an opening, the holder holds the gas generating agent in the combustion chamber,
The retainer has a flat plate portion for 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 edge portion of the flat plate portion.
15. The gas generator according to any one of claims 9 to 13, wherein,
the ignition device is mounted on the other end side of the housing,
the gas generator has a holder that divides a space in which the ignition device is disposed and the combustion chamber, and has an opening, the holder holds the gas generating agent in the combustion chamber,
the retainer includes a flat plate portion for supporting the gas generating agent, a stepped portion provided along an outer periphery of the flat plate portion so as to be separated from an inner periphery of the housing, and a connection portion that abuts against the inner periphery of the housing, and the stepped portion has a through hole.
16. The gas generator according to any one of claims 9 to 13, wherein,
the ignition device is mounted on the other end side of the housing,
the gas generator has a holder that divides a space in which the ignition device is disposed and the combustion chamber, and has an opening, the holder holds the gas generating agent in the combustion chamber,
The retainer has a flat plate portion having an outer diameter smaller than an inner diameter of the housing and supporting the gas generating agent, a connection portion abutting against an inner periphery of the housing, and an annular inclined surface having a slope connecting from an outer periphery of the flat plate portion toward the connection portion, and the annular inclined surface has a through hole.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2021-086440 | 2021-05-21 | ||
| JP2021154784A JP2022179278A (en) | 2021-05-21 | 2021-09-22 | Gas generator and gas discharge method |
| JP2021-154784 | 2021-09-22 | ||
| PCT/JP2021/048950 WO2022244294A1 (en) | 2021-05-21 | 2021-12-28 | Gas generator and gas discharge method |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN117396371A true CN117396371A (en) | 2024-01-12 |
Family
ID=89437765
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202180098327.5A Pending CN117396371A (en) | 2021-05-21 | 2021-12-28 | Gas generator and gas discharge method |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN117396371A (en) |
-
2021
- 2021-12-28 CN CN202180098327.5A patent/CN117396371A/en active Pending
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