Patent Application
20250085091
The present invention relates to a gas generator.
A known widely used gas generator fills a gas generating agent in a combustion chamber formed in a housing, burns the gas generating agent by an igniter to generate combustion gas, and discharges the combustion gas to the exterior from a gas discharge port provided in the housing. To cool the generated combustion gas and trap residues in such a gas generator, a tubular filter may be disposed between the combustion chamber and the gas discharge port.
Patent Document 1 discloses a gas generator including an ignitable material arranged to produce gas, a sub-assembly formed of a first component and a second component that are fixed by friction welding, a third component fixed to the first component or the second component by friction welding, and a tubular filter.
Patent Document 1: US 2019/001917 A
The aforementioned gas generator is configured such that combustion gas flows from the inside to the outside of a cylindrical filter. Since combustion residues are filtered out when the combustion gas passes through the filter, the amount of combustion residues contained in the combustion gas (hereinafter, also referred to as a contained residue amount) is large on the inflow side of the filter, and the contained residue amount is small on the outflow side of the filter. Therefore, in a configuration where the combustion gas flows from the inner peripheral surface to the outer peripheral surface of the cylindrical filter, the contained residue amount when the combustion gas flows into the inner peripheral surface narrower than the outer peripheral surface is large, and the contained residue amount when the combustion gas passes through the relatively wide outer peripheral surface is small. As a result, the filter cannot be efficiently used, and a technique for improving the use efficiency of the filter is required.
The technique according to the present disclosure has been made in view of the above circumstances, and an object thereof is to provide a technique that improves the use efficiency of a filter in a gas generator.
To solve the above problem, the technique of the present disclosure adopts the following configuration. In other words, a gas generator according to an aspect of the present disclosure includes: a housing; an ignition unit disposed in the housing; a gas generating agent that is accommodated in a combustion chamber in the housing and that generates a combustion gas upon operation of the ignition unit; a discharge port provided in the housing and configured to discharge the combustion gas generated in the housing to an outside; and a filter disposed between the discharge port and the gas generating agent. The filter extends in an axial direction, at least an outer peripheral portion on one end surface of the filter in the axial direction is connected to an inner wall surface of the housing to surround the discharge port, a portion that is at least a part of an outer peripheral surface of the filter around an axis and extends over the entire circumference is an inflow portion of the combustion gas, and the inflow portion is disposed to be in communication with the combustion chamber.
The gas generator according to an aspect of the present disclosure may further include a partition wall member partitioning the housing into the combustion chamber in which the gas generating agent is accommodated and a filter chamber in which the filter is disposed, the partition wall member being provided with, in a part of the partition wall member, a communication hole configured to allow the combustion chamber and the filter chamber to be in communication with each other. A second end surface opposite to a first end surface connected to the inner wall surface of the housing in the axial direction of the filter may be connected to the partition wall member.
In the gas generator according to an aspect of the present disclosure, the housing may include a tubular peripheral wall portion extending along the axial direction, a first wall portion closing one end of the tubular peripheral wall portion, and a second wall portion closing the other end of the tubular peripheral wall portion. The communication hole may be formed in the first wall portion in a direction in which the combustion gas is released in a direction orthogonal to the first wall portion.
In the gas generator according to an aspect of the present disclosure, the housing may include a tubular peripheral wall portion extending along the axial direction, a first wall portion in which the discharge port is formed and which closes one end of the tubular peripheral wall portion, and a second wall portion closing the other end of the tubular peripheral wall portion. A groove portion may be disposed in an inner surface of the first wall portion along a circumferential direction, and the communication hole may be disposed at a position in which the combustion gas is released toward the groove portion.
In the gas generator according to an aspect of the present disclosure, the housing may include a tubular peripheral wall portion extending along the axial direction, a first wall portion in which the discharge port is formed and which closes one end of the tubular peripheral wall portion, and a second wall portion closing the other end of the tubular peripheral wall portion. The partition wall member may be formed such that a portion not connected to the filter protrudes toward the first wall portion of the housing with respect to a portion connected to the filter.
In the gas generator according to an aspect of the present disclosure, the housing may include a peripheral wall portion having a tubular shape. The communication hole may be formed in a direction in which the combustion gas is released toward the peripheral wall portion.
In the gas generator according to an aspect of the present disclosure, the filter may be formed in a cylindrical shape.
In the gas generator according to an aspect of the present disclosure, the housing may include a tubular peripheral wall portion extending along the axial direction, a first wall portion closing one end of the tubular peripheral wall portion, and a second wall portion closing the other end of the tubular peripheral wall portion. One end surface of the filter in the axial direction may be connected to the first wall portion, and the other end surface of the filter may be connected to the second wall portion.
According to the present disclosure, a gas generator including a filter can provide improved use efficiency of the filter.
A gas generator according to an embodiment of the present disclosure will be described below with reference to the drawings. It should be noted that the respective configurations and the combinations thereof in the respective embodiments are merely examples, and additions, omissions, substitutions, and other changes to the configurations can be made as appropriate without departing from the gist of the present invention. The present invention is not limited by the embodiments and is limited only by the claims.
As illustrated in
The housing 1 is a member that accommodates the inner tubular member 5, the filter 6, the ignition device 7, the partition wall member 8, the transfer charge 110, and the gas generating agent 120. The housing 1 is provided with an upper container 2 and a lower container 3 made of a metal each formed in a bottomed substantially tubular shape, and is formed in a short tubular shape in which both axial ends are closed by joining the upper container 2 and the lower container 3 in a state where opening ends face each other. The upper container 2 and the lower container 3 define a combustion chamber 10, and constitute a container 20 in which the gas generating agent 120 and the like are disposed. The housing 1 also includes an outer shell member 4 externally fitted to the gas discharge side of the container 20, that is, the upper side in the present example.
The upper container 2 includes an upper peripheral wall portion 21 that has a tubular shape and a top plate portion 22 that closes an upper end of the upper peripheral wall portion 21, thereby forming an internal space. An opening of the upper container 2 is formed on the lower end side of the internal space. The lower container 3 includes a lower peripheral wall portion 31 that has a tubular shape and a bottom plate portion 32 that closes a lower end of the lower peripheral wall portion 31 and to which the ignition device 7 is fixed, thereby forming an internal space. An opening of the lower container 3 is formed in an upper end portion of the internal space.
A joining portion 23 as an opening side end portion of the upper container 2 and a joining portion 33 as an opening side end portion of the lower container 3 are overlapped and joined by laser welding or the like to form the container 20 having a short cylindrical shape with both axial ends closed. The upper peripheral wall portion 21 of the upper container 2 and the lower peripheral wall portion 31 of the lower container 3 form a peripheral wall portion 12 of the container 20. In other words, the container 20 includes the peripheral wall portion 12 having a tubular shape, the top plate portion 22 disposed on one end side of the peripheral wall portion 12, and the bottom plate portion 32 disposed on the other end side of the peripheral wall portion 12. The top plate portion 22 corresponds to a “first wall portion” according to the present disclosure. The bottom plate portion 32 corresponds to a “second wall portion” according to the present disclosure.
The top plate portion 22 of the container 20 is provided with a discharge port 25 extending through the container 20 from the inside to the outside and configured to discharge the combustion gas generated in the container 20 to the outside. The position of the discharge port 25 is not particularly limited, but in the present embodiment, the discharge port 25 is disposed at the center of the top plate portion 22 in a plan view. In other words, the discharge port 25 is formed concentrically with the peripheral wall portion 12.
The ignition device 7 and the inner tubular member 5 are disposed in the lower container 3, and a lower end of the inner tubular member 5 is joined to the bottom plate portion 32 of the lower container 3. The inner tubular member 5 is a tubular member extending from the bottom plate portion 32 toward the top plate portion 22 to surround the ignition device 7.
The inner tubular member 5 is disposed concentrically with the peripheral wall portion 12, and an inner space thereof serves as a fire transfer chamber 50 and an outer space thereof serves as the combustion chamber 10. The partition wall member 8 formed in a substantially disc-like shape is disposed on the upper side of the inner tubular member 5 to define upper surfaces of the fire transfer chamber 50 and the combustion chamber 10. The partition wall member 8 defines the combustion chamber 10 and the fire transfer chamber 50 on the lower side and a filter chamber 60 on the upper side in the container 20. A plurality of communication holes 81 for enabling the combustion chamber 10 and the filter chamber 60 to be in communication with each other are disposed in the partition wall member 8 at a location near the outer edge thereof. The number and arrangement of the communication holes 81 are not particularly limited, but in the present embodiment, the plurality of communication holes 81 are disposed in the radial direction of the partition wall member 8, and the plurality of communication holes 81 are disposed at equal intervals along the circumferential direction of the partition wall member 8. Each of the communication holes 81 is formed along the axial direction of the housing 1 and is formed in a direction in which the combustion gas is released in a direction orthogonal to the direction in which the top plate portion 22 extends. In other words, the communication hole 81 of the present embodiment is formed in a direction along the center axis C. Also, in a case where the top plate portion 22 has a spherical shape, the discharge direction of the combustion gas may be a direction along the center axis C or may be a direction (radial direction) perpendicular to a tangential line on the spherical surface.
The ignition device 7 is disposed in the fire transfer chamber 50 inside the inner tubular member 5, and the transfer charge 110 is made to fill the space around the ignition device 7. Further, the combustion chamber 10 outside the inner tubular member 5 is filled with the gas generating agent 120. A plurality of communication holes 52 for enabling the fire transfer chamber 50 as the internal space to be in communication with the combustion chamber 10 as the external space are formed in the inner tubular member 5 along the circumferential direction. Each of the communication holes 52 is closed by a seal tape (not illustrated) in a state before the ignition device 7 is activated. When the ignition device 7 is activated, the seal tape is raptured by the pressure of the combustion gas, and the fire transfer chamber 50 and the combustion chamber 10 are in communication with each other. Note that the communication hole 52 only needs to enable the interior and the exterior of the fire transfer chamber 50 to be in communication with each other when at least the ignition device 7 is activated and does not need to be closed with a seal tape.
The filter 6 is disposed in the filter chamber 60 in the container 20. The shape of the filter 6 is not particularly limited, and may be, for example, tubular or columnar. Note that the filter 6 of the present embodiment has a columnar shape. In addition, although the filter 6 of the present embodiment is disposed at the center of the filter chamber 60 to cover the discharge port 25, the configuration is not limited thereto. The filter 6 may be disposed at a position between the discharge port 25 and the gas generating agent 120 through which the combustion gas passes. In other words, the discharge port 25 is formed within a projection region of a cross-sectional shape of the filter 6 orthogonal to the center axis C.
The filter 6 has an upper surface 61 in contact with the top plate portion 22 of the container 20 and a lower surface 63 in contact with an upper surface of the partition wall member 8, and the filter 6 is sandwiched between the top plate portion 22 and the partition wall member 8. A recessed portion 82 having substantially the same shape as the lower portion of the filter 6 is disposed on the upper surface of the partition wall member 8, and the lower portion of the filter 6 is fitted into the recessed portion 82 and thereby is positioned.
The container 20 is filled with a pressurized inert gas (hereinafter, also referred to as pressurized gas), and the discharge port 25 is closed by a rupturable plate 26. A seal member 53 having a cup shape is disposed to cover the space around the ignition device 7, and thus airtightness in an opening portion of the bottom plate portion 32 to which the ignition device 7 is attached is maintained. The seal member 53 is made of, for example, a metal and is joined to the bottom plate portion 32 by welding or the like. The seal member 53 has rigidity that can withstand the pressure of the inert gas, and is configured to rupture by operation of the ignition device 7. Here, examples of the inert gas include argon, helium, and a mixture thereof. The gas generator 100 of the present embodiment is a hybrid gas generator configured to discharge pressurized gas and combustion gas during operation.
The outer shell member 4 attached on the gas discharge side of the container 20 includes a peripheral wall portion 41 having a tubular shape, a top plate portion 42 closing an upper end of the peripheral wall portion 41, and a flange portion 43 extended in the radial direction from a lower end of the peripheral wall portion 41. The outer shell member 4 is externally fitted to an upper portion of the container 20 and is joined to an outer surface of the peripheral wall portion 12. In a state where the outer shell member 4 is joined to the container 20 as just described, the outer shell member 4 forms a discharge side space 44 serving as a discharge path of the combustion gas between the outer shell member 4 and the top plate portion 22 of the container 20. In the peripheral wall portion 41 of the outer shell member 4, a plurality of gas discharge ports 11 enabling the discharge side space 44 and the external space to be in communication with each other are formed side by side along the circumferential direction.
As illustrated in
The attachment member 72 is a member that is interposed between the igniter 71 and the bottom plate portion 32 to fix the igniter 71 to the bottom plate portion 32. The attachment member 72 includes resin that covers a lower portion of the igniter 71, and forms a connector insertion space into which a connector (not illustrated) for supplying power from an external power supply to the pair of energizing pins 712 and 713 can be inserted. Note that fixing of the igniter 71 to the bottom plate portion 32 and the relationship between the attachment member 72 and the bottom plate portion 32 are not limited to those of
The filter 6 according to the present example is formed by radially stacking annular metal plates in which multiple holes are formed. For example, the filter 6 may be formed by concentrically stacking tubular metal plates or by spirally winding a metal plate in a plan view so as to be stacked in the radial direction. Alternatively, the filter 6 may be formed by stacking disc-shaped porous metal plates in the axial direction. Examples of the porous metal plate serving as a material of the filter 6 include expanded metal, lath metal, perforated metal, and wire. Note that in
In addition to a known black powder, a gas generating agent having good ignition quality and a higher combustion temperature than the gas generating agent 120 can be used as the transfer charge 110. The combustion temperature of the transfer charge 110 can be set in a range of 1700° C. to 3000° C. As the transfer charge 110, a known transfer charge containing, for example, nitroguanidine (34 wt. %) and strontium nitrate (56 wt. %) can be used. In addition, various shapes, such as a granular shape, a pellet shape, a columnar shape, and a disc shape, can be adopted for the transfer charge 110.
As the gas generating agent 120, a gas generating agent having a relatively low combustion temperature can be used. The combustion temperature of the gas generating agent 120 can be set in the range of 1000° C. to 1700° C. As the gas generating agent 120, a known agent including, for example, guanidine nitrate (41 wt %), basic copper nitrate (49 wt %), a binder, and an additive can be used. The gas generating agent 120 may have any of a variety of shapes, such as a granular shape, a pellet shape, a columnar shape, or a disc shape.
The operation of the gas generator 100 according to the first embodiment will be described below. First, description will be made with reference to
In the gas generator 100 of the present embodiment, at least the outer peripheral portion of the one end surface 61 of the filter 6 is connected to an inner wall surface of the top plate portion 22 to surround the discharge port 25, and the outer peripheral surface 62 is disposed to be in communication with the combustion chamber 10. As a result, the combustion gas passes through the outer peripheral surface 62 of the filter 6 at the initial stage of inflow when the amount of combustion residues contained therein (hereinafter, also referred to as a contained residue amount) is large, and passes through the inner portion while being filtered with the contained residue amount decreasing. In other words, as the combustion gas passes inward from the inflow portion formed entirely in the circumferential direction of the outer peripheral surface 62 of the filter 6, the contained residue amount decreases due to filtration, and the combustion gas temperature also decreases. In addition, the cross-sectional area in the filter radial direction with which the combustion gas comes into contact also gradually decreases. In other words, a contact area of the filter corresponding to the contained residue amount and the gas temperature is provided. Therefore, the use efficiency of the filter 6 can be improved, and the performance of the gas generator 100 can be improved. Further, by improving the use efficiency of the filter 6, the same filter performance as that of a known filter can be achieved by the small filter 6, and thus the gas generator 100 can be reduced in size.
Furthermore, in the gas generator 100 of the present embodiment, the filter 6 may include a plurality of layers in the radial direction, and the density of the inner layers may be higher than that of the outer layers. As a result, the use efficiency of the filter 6 can be further improved.
Further, in the gas generator 100 of the present embodiment, the communication hole 81 of the partition wall member 8 is formed in a direction in which the combustion gas is released in a direction orthogonal to the extension direction of the top plate portion 22. Thus, the combustion gas generated in the combustion chamber 10 is first brought into contact with the top plate portion 22 to allow large residues and highly adhesive residues to adhere to the top plate portion 22, and then the combustion gas flows into the filter 6. As a result, the use efficiency of the filter 6 is further improved.
Furthermore, in the gas generator 100 of the present embodiment, the upper surface 61 of the filter 6 is disposed in contact with the top plate portion 22, and the lower surface 63 of the filter 6 is disposed in contact with the recessed portion 82 of the partition wall member 8. As a result, the combustion gas is prevented from flowing between the upper surface 61 and the top plate portion 22 or between the lower surface 63 and the partition wall member 8, that is, a so-called “short path” is prevented, and the use efficiency of the filter 6 can be improved. Note that in the first embodiment, a gap may be formed between the lower surface 63 and the partition wall member 8 as long as a short path between the upper surface 61 of the filter 6 and the top plate portion 22 is prevented.
As illustrated in
As described above, according to the present embodiment, the combustion gas generated in the combustion chamber 10 is discharged toward the groove portion 222, and remains in the groove portion 222 and thereafter flows into the filter 6. Therefore, large residues or highly adhesive residues in the combustion gas are removed by the groove portion 222, and the use efficiency of the filter 6 can be improved. Recesses and protrusions may be further disposed on the surface of the groove portion 222 to increase the contact area with the combustion gas.
As illustrated in
As described above, according to the present embodiment, since the combustion chamber 10 is formed to be larger than the gas generator 100 of the first embodiment, the filling amount of the gas generating agent 120 and the pressurized gas can be increased, and the performance of the gas generator 300 can be improved.
As illustrated in
As described above, according to the present embodiment, the combustion gas generated in the combustion chamber 10 is released toward the peripheral wall portion 12, hits the peripheral wall portion 12, and thereafter flows into the filter 6. Therefore, large residues and highly adhesive residues in the combustion gas adhere to the peripheral wall portion 12 to be removed, and the use efficiency of the filter 6 can be improved.
As illustrated in
As described above, according to the present embodiment, the combustion gas generated in the combustion chamber 10 passes through the filter 6A from the outside to the inside thereof. Therefore, the use efficiency of the filter 6 can be improved. Note that in the present embodiment, the configurations other than the filter 6A are the same as those of the first embodiment, but are not limited thereto and may be the same as those of the second to fourth embodiments.
In the present embodiment, the container 20 is not filled with pressurized gas, and a lower end of the discharge port 25 is closed by a seal tape 27. In other words, the seal tape 27 is disposed in the internal space of the filter 6A such that the seal tape 27 and the filter 6A do not interfere with each other.
When the igniter 71 is activated and the transfer charge 110 and the gas generating agent 120 burn to generate combustion gas, the seal tape closing the communication hole 52 ruptures, and thus the combustion gas passes through the filter 6A, is discharged from the discharge port 25, and is released via the discharge side space 44 from the gas discharge port 11 to the outside of the housing 1.
As described above, according to the present embodiment, the combustion gas generated in the combustion chamber 10 passes through the filter 6A from the outside to the inside thereof. Therefore, the use efficiency of the filter 6 can be improved.
As illustrated in
The housing 1 is a member that accommodates the filter 6B, the ignition device 7, and the gas generating agent 120. The housing 1 is provided with the upper container 2 and the lower container 3 made of a metal each formed in a bottomed substantially tubular shape, and is formed in a short tubular shape in which both axial ends are closed by joining the upper container 2 and the lower container 3 in a state where opening ends face each other. The upper container 2 and the lower container 3 define a combustion chamber 10A, and constitute the container 20 in which the gas generating agent 120 and the like are disposed. The housing 1 also includes the outer shell member 4 externally fitted to the gas discharge side of the container 20, that is, the upper side in the present example.
The top plate portion 22 of the container 20 is provided with the discharge port 25 extending through the container 20 from the inside to the outside and configured to discharge the combustion gas generated in the container 20 to the outside.
The filter 6B having a tubular shape is disposed in the container 20 to divide the internal space of the container 20 into an inner space and an outer space, and the outer space serves as the combustion chamber 10A. The filter 6B includes a through hole formed from an upper surface 61B to a lower surface 63B at the center portion in the radial direction, and the discharge port 25 is formed to face a region (an internal space) formed by the through hole.
The ignition device 7 is disposed in the combustion chamber 10A in the lower container 3, and the gas generating agent 120 is made to fill the space around the ignition device 7.
The filter 6B is a tubular member formed of a metallic material. The upper surface 61B is in contact with the top plate portion 22 to surround the discharge port 25, the lower surface 63B is in contact with the bottom plate portion 32, and the filter 6B is sandwiched between the top plate portion 22 and the bottom plate portion 32.
The seal tape 27 is disposed at the center of the inner surface side of the top plate portion 22 to cover the discharge port 25, thereby closing the discharge port 25. In other words, the seal tape 27 is disposed in the internal space of the filter 6B such that the seal tape 27 and the filter 6B do not interfere with each other.
When the igniter 71 is activated, the ignition charge accommodated in the cup body 711 of the igniter 71 burns, and a flame, a high-temperature gas, and the like, which are combustion products, are released to the outside of the cup body 711. Thus, the gas generating agent 120 accommodated in the combustion chamber 10A burns, and a high-temperature and high-pressure combustion gas is generated. Then, the pressure in the container 20 increases, and the seal tape 27 closing the discharge port 25 ruptures, and thus the combustion gas is discharged from the discharge port 25 via the filter 6B. At this time, the combustion gas passes through the filter 6B, and thus the combustion gas is cooled, and combustion residues are trapped. The pressurized gas and the combustion gas discharged from the discharge port 25 to the discharge side space 44 hit the top plate portion 42 of the outer shell member 4, are deflected in the radial direction of the housing 1, and are released from the gas discharge port 11 to the outside of the housing 1. The pressurized gas and the combustion gas are released to the outside of the housing 1 and thereafter flow into an airbag (not illustrated). This causes the airbag to inflate, and thus a cushion is formed between an occupant and a rigid structure, and the occupant is protected from an impact.
In the gas generator 700 of the present embodiment, one end surface 61B of the filter 6B is connected to the inner wall surface of the top plate portion 22 to surround the discharge port 25, and an outer peripheral surface 62B is disposed to be in communication with the combustion chamber 10A. As a result, the combustion gas passes through the outer peripheral surface 62B of the filter 6B at the initial stage of inflow at which the contained residue amount therein is large, and passes toward an inner peripheral surface 68 of the filter 6B while being filtered with the contained residue amount decreasing. In other words, as the combustion gas flows toward the inner peripheral surface 68 from an inflow portion formed entirely in the circumferential direction of the outer peripheral surface 62B of the filter 6B, the contained residue amount decreases due to filtration, and the combustion gas temperature also decreases. In addition, the cross-sectional area in the filter radial direction with which the combustion gas comes into contact also gradually decreases. In other words, a contact area of the filter corresponding to the contained residue amount and the gas temperature is provided. Therefore, the use efficiency of the filter 6B can be improved, and the performance of the gas generator 700 can be improved.
In addition, in the gas generator 700 of the present embodiment, the upper surface 61B of the filter 6B is disposed in contact with the top plate portion 22, and the lower surface 63B of the filter 6B is disposed in contact with the bottom plate portion 32. As a result, the combustion gas is prevented from flowing between the upper surface 61B and the top plate portion 22 or between the lower surface 63B and the bottom plate portion 32, that is, a so-called “short path” is prevented, and the use efficiency of the filter 6B can be improved. Note that in the gas generators illustrated in
Suitable embodiments according to the present disclosure have been described above, but each embodiment disclosed in the present specification can be combined with each of features disclosed in the present specification.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2022-088770 | May 2022 | JP | national |
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/JP2023/017062 | May 2023 | WO |
| Child | 18954939 | US |
