Gas generator

Abstract

The present invention improves the structure of a gas generator capable of taking in and sending out external air. This gas generator comprises: a housing that accommodates a gas source for generating gas through an operation of an igniter and is provided with a gas discharge hole for discharging the gas; and a cover that covers a part of the housing and forms a flow passage for gas, between the cover and the housing, along the housing. The gas discharge hole is formed to communicate the inside of the housing and the inside of the flow passage and discharge the gas toward one end side of the flow passage. When the gas is discharged from the gas discharge hole of the housing, an outlet for the gas is formed on one end side of the flow passage, and an intake port for taking in the external air is formed on the other end side of the flow passage.

Description

Gas generator

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

[0002] Various gas generators have been proposed. Patent Document 1 discloses an example in which the ventilation opening is part of a venturi nozzle (see, for example, FIG. 4a). That is, an air conduction element is disposed inside a base portion and forms a venturi tube together with a part of the base portion. The venturi tube has a minimum diameter at the position of the ventilation opening. The ventilation opening allows additional outside air to be drawn in while the gas generator releases combustion gas and the airbag is deployed.

[0003] DE 102011108795

[0004] For example, when additional external air is taken in by the Venturi effect, it is possible to deliver more gas than the amount of combustion gas generated by the combustion of the gas generating agent used. However, a volume is required to form the Venturi tube, which makes it difficult to miniaturize the device as a whole.

[0005] The technique of the present disclosure aims to improve the structure of a gas generator that can take in and deliver external air.

[0006] (Aspect 1) A gas generator comprising: a housing that accommodates a gas source that generates gas due to activation of an igniter, the housing being provided with a gas discharge hole for discharging the gas; and a cover that covers a portion of the housing and forms a gas flow passage between the housing and the cover and the housing, the gas discharge hole communicating between the interior of the housing and the interior of the flow passage and being formed to discharge the gas toward one end of the flow passage, wherein when the gas is discharged from the gas discharge hole of the housing, an outlet for the gas is formed at one end of the flow passage and an intake port for taking in outside air is formed at the other end of the flow passage. (Aspect 2) In the gas generator according to Aspect 1, the flow passage may have a constricted portion between the cover and the gas discharge hole, the cross-sectional area of ​​which is narrowed, and the gas discharged from the gas discharge hole and the outside air taken in from the intake port may be configured to merge in the vicinity of the constricted portion. (Aspect 3) In the gas generator according to aspect 2, the gas discharge hole may be formed by a guide portion that guides the discharge direction of the gas so that the gas is discharged toward one end of the flow passage, and the throttle portion may be formed between the guide portion and the cover. (Aspect 4) In the gas generator according to aspect 3, the guide portion may be a throttle portion that gradually reduces the cross-sectional area of ​​the gas discharge hole, and the gas discharged from the gas discharge hole and the outside air taken in from the intake port may be configured to join together in the vicinity of the throttle portion. (Aspect 5) In the gas generator according to any one of aspects 1 to 4, the housing may include a top surface portion, a bottom surface portion, and a side periphery connecting the top surface portion and the bottom surface portion, and the gas discharge hole may be provided in the side periphery, and the cover may be configured to cover at least the outer periphery of the gas discharge hole in the side periphery.(Aspect 6) In the gas generator according to Aspect 5, a plurality of the gas discharge holes are formed in the circumferential direction on a side peripheral portion of the housing, and a guide portion for guiding the discharge direction of the gas so as to discharge the gas toward one end of the flow passage is formed around the gas discharge hole as a separate member from the housing, the guide portion may be provided at each of the plurality of gas discharge holes, and a throttle portion for reducing the cross-sectional area of ​​the transverse cross section may be formed between the guide portion and the cover. (Aspect 7) In the gas generator according to Aspect 5, a plurality of the gas discharge holes are formed in the circumferential direction on a side peripheral portion of the housing, and a guide portion for guiding the discharge direction of the gas so as to discharge the gas toward one end of the flow passage is formed around the gas discharge hole, and the guide portion has an inclined surface that covers at least two or more adjacent gas discharge holes of the plurality of gas discharge holes from the outside, and a throttle portion for reducing the cross-sectional area of ​​the transverse cross section may be formed between the guide portion and the cover. (Aspect 8) In the gas generator according to Aspect 7, a plurality of the gas discharge holes may be formed in the side peripheral portion, and the guide portion may have a cylindrical portion connected to the inclined surface, and the cylindrical portion may be fixed to the side peripheral portion. (Aspect 9) In the gas generator according to Aspect 7, the gas source may be a solid molded product of gas generating agent that generates gas by combustion, and unevenness may be formed on at least one of the side of the guide portion facing the gas discharge hole or the cover on a side closer to the tip than the upper end of the inclined surface. (Aspect 10) In the gas generator according to Aspect 5, a plurality of the gas discharge holes are formed circumferentially on a side peripheral portion of the housing, and a guide portion is formed around the gas discharge holes to guide the discharge direction of the gas so that the gas is discharged toward one end side of the flow passage, and the guide portion includes: a surrounding wall portion that covers at least two or more adjacent gas discharge holes of the plurality of gas discharge holes from the outside; a cylindrical portion that abuts against the side peripheral portion from the outside to fix the guide portion to the housing; and a connecting portion that connects the cylindrical portion and the surrounding wall portion, and a constriction portion that narrows the cross-sectional area of ​​the transverse section may be formed between the surrounding wall portion and the cover.(Aspect 11) In the gas generator according to Aspect 10, the gas source may be a solid molded article of gas generating agent that generates gas by combustion, and the guide portion may have irregularities formed on the side facing the gas discharge hole. (Aspect 12) In the gas generator according to Aspect 5, a plurality of the gas discharge holes may be formed in the side peripheral portion along the circumferential direction thereof, and the cover may be cylindrical with repeated irregularities in the circumferential direction, and the flow passage may be formed between the cover and the side peripheral portion at a position corresponding to the gas discharge hole. (Aspect 13) In the gas generator according to Aspect 5 or 12, the housing may have a flange portion extending radially outward from the side peripheral portion, and the flange portion may have a through-hole that functions as the intake port on the other end side of the flow passage. (Aspect 14) In the gas generator according to any one of Aspects 5, 12, and 13, the gas discharge holes may be formed in a plurality of locations along the circumferential direction of the side periphery, the housing may include a flange portion extending radially outward from the side periphery, the cover may be cylindrical, and may include repeated irregularities in the circumferential direction of the cover to form the flow passage between the side periphery of the housing and the cover, and may include irregularities that extend the flow passage radially outward from the cover along the flange portion, and the intake port may be formed at an end of the extending direction.

[0007] The contents described in the means for solving the problems can be combined as much as possible within the scope of the problems and technical ideas of this disclosure.

[0008] According to the present disclosure, it is possible to improve the structure of a gas generator that can take in and deliver external air.

[0009] FIG. 1 is an exploded perspective view showing an example of the configuration of a gas generator. FIG. 2 is a perspective view of the assembled gas generator as seen obliquely from above. FIG. 3 is a perspective view of the assembled gas generator as seen obliquely from below. FIG. 4 is a schematic partial cross-sectional view showing an example of the gas generator as attached to an airbag. FIG. 5 is a contour diagram showing the results of velocity distribution by simulation. FIG. 6 is a contour diagram showing the results of pressure distribution by simulation. FIG. 7 is an exploded perspective view showing an example of the configuration of a gas generator. FIG. 8 is a schematic partial cross-sectional view of an example of the gas generator as attached to an airbag. FIG. 9 is a partial cross-sectional view of a gas generator according to a third embodiment. FIG. 10 is a perspective view for explaining a guide member according to a modified example. FIG. 11 is a diagram showing another modified example of the guide member. FIG. 12 is a diagram showing another modified example of the guide member.

[0010] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Note that each configuration and combination thereof in each embodiment is an example, and addition, omission, substitution, and other modifications of the configuration are possible as appropriate within the scope of the gist of the present invention. The present disclosure is not limited by the embodiments, but is limited only by the claims.

[0011] <Embodiment 1> Fig. 1 is an exploded perspective view showing an example of the configuration of a gas generator. Fig. 2 is a perspective view of the assembled gas generator as seen obliquely from above. Fig. 3 is a perspective view of the assembled gas generator as seen obliquely from below. In Figs. 1 to 3, the upward and downward directions of the gas generator are indicated by arrows for convenience. The gas generator 1 is, for example, a device for discharging gas to deploy an airbag, but is not limited to this. The gas generator 1 may be used for driving a seat belt retractor, a current breaker, an actuator, or the like. That is, the illustrated gas generator 1 is in a disk shape whose height direction is shorter than its outer diameter in a plan view (top view), but may also be in a cylindrical shape whose axial length is longer than its outer diameter in a plan view (outer diameter of a cross section), or the like.

[0012] The gas generator 1 includes a housing 2 and a cover 3. The housing 2 is a housing that houses a gas source that generates gas upon activation of an igniter that is ignited by an externally supplied current. The housing 2 is formed, for example, from metal. The gas source may contain a solid gas generating agent that burns to generate combustion products such as gas, or pressurized gas, or both. The gas generating agent may be a known agent containing, for example, guanidine nitrate, basic copper nitrate, a binder, an additive, etc. The gas generating agent may also be in various shapes, such as granular, pellet, cylindrical, or disk-shaped. The pressurized gas may be a known agent such as a mixture of argon, helium, etc.

[0013] The housing 2 has an upper surface (upper surface portion) 21, a side surface (peripheral portion) 22, and a bottom surface (bottom surface portion) 23. As shown in the figure, the housing 2 may include chamfered portions or stepped portions, but is generally cylindrical (disc-shaped). The housing 2 may be formed, for example, by combining two bottomed cylindrical members (shells). The side surface 22 has a plurality of gas exhaust holes 221 formed along the circumferential direction. The gas exhaust holes 221 are formed so as to exhaust gas upward from the side surface 22. That is, the gas exhaust holes 221 are formed in the side surface 22 of the housing 2 by a guide portion 222 that covers the sides and bottom of the side surface 22. The guide portion 222 is formed so as to extend radially outward of the housing 2 in an upward direction.

[0014] Furthermore, the housing 2 may have a flat flange portion 24 that extends radially outward from the side surface 22. The flange portion 24 can be used, for example, to attach the gas generator 1 to some kind of object. The flange portion 24 according to the present embodiment is provided with a through hole 241 and a through hole 242. A plurality of through holes 241 are provided inside the flange portion 24 along the side surface 22. Note that the through holes 241 are provided at positions in the circumferential direction of the housing 2 that correspond to the gas discharge holes 221 of the side surface 22 (on the radial extension of the gas discharge holes 221 in a plan view). The through holes 242 are provided on the outside of the flange portion 24. The through holes 242 are, for example, through holes for passing bolts for attaching the gas generator 1 to some kind of object, or female thread portions, etc.

[0015] The cover 3 is a cylindrical member that can cover a portion of the side surface 22 of the housing 2. The cover 3 can be formed of metal, resin, or the like. The cover 3 includes a large-diameter portion 31 and a small-diameter portion 32, which are connected by a connecting portion 33. That is, the cover 3 includes repeated concave and convex portions in its circumferential direction. The cover 3 also has a flange portion 34 at its lower end that extends radially outward. The large-diameter portion 31, the small-diameter portion 32, and the connecting portion 33 each extend along the axial direction of the cylindrical cover 3. The inner diameter of the small-diameter portion 32 is approximately the same as the outer diameter of the side surface 22 of the housing 2. As shown in FIG. 2 , when the cover 3 is attached to the housing 2, a gas flow passage 35 is formed between the side surface 22 of the housing 2, the large-diameter portion 31, and the connecting portion 33. The number and circumferential spacing of the gas exhaust holes 221 of the housing 2 and the large diameter portions 31 of the cover 3 are the same so that gas can be exhausted from the gas exhaust holes 221 of the housing 2 into the flow passage 35. In addition, the through-holes 241 provided in the flange portion 24 of the housing 2 are also located at positions corresponding to the flow passage 35.

[0016] FIG. 4 is a schematic partial cross-sectional view showing an example of a gas generator attached to an airbag. The same reference numerals are used to denote components shown in FIGS. 1 to 3 , and descriptions thereof will be omitted. In the example of FIG. 4 , a cover 3 is attached around the side surface 22 of the housing 2. The housing 2 and cover 3 are fixed to an attachment target 4 using fasteners such as bolts 41 and nuts 42. The attachment target 4 is an object to which the gas generator 1 is attached, such as the base plate of an airbag module. In the example of FIG. 4 , the attachment target 4 is sandwiched and fixed between the flange portion 24 of the housing 2 and the flange portion 34 of the cover 3. However, the flange portion 24 of the housing 2 and the flange portion 34 of the cover 3 may be overlapped so as to be in contact with each other, and the attachment target 4 may be connected to either the top or bottom (the flange portion 24 side of the housing 2 or the flange portion 34 side of the cover 3). Similarly, the end of the folded airbag 5 is also connected to the flange portion 34 of the cover 3 with fasteners, covering the upper side of the gas generator 1. Therefore, when the gas generator 1 is activated, gas is discharged from the gas generator 1 into the airbag 5. Note that, as shown in Fig. 4 , the bolts 41 may be provided so as to pass through the flange portion 34 in Fig. 2. That is, the flange portion 34 in Fig. 2 is modified in shape to cover the through-hole 242 in the flange portion 24 of the housing 2, and holes are formed in the flange portion 34 at positions corresponding to the through-hole 242. Then, the housing 2 of the gas generator may be fixed to the mounting object 4 with the bolts 41 and nuts 42 so as to pass through both the through-hole 242 and the holes in the flange portion 34.

[0017] The flow passage 35 is formed along the side surface 22 of the housing 2 from an upper end 351 on one end side to a lower end 352 on the other end side. The upper end 351 opens above the gas generator (in other words, the interior of the airbag 5). The lower end 352 opens toward the flange portion 24. A through-hole 241 is provided in the flange portion 24 at a position corresponding to the flow passage 35, and the through-hole 241 connects the flow passage 35 (in other words, the interior of the airbag 5) with the outside of the airbag 5. The gas discharge hole 221 of the housing 2 is located within the flow passage 35 (between the upper end 351 and the lower end 352). When gas is discharged upward from the gas discharge hole 221 into the flow passage 35, external air can be drawn into the flow passage 35 below a junction 353 where the gas junction joins with the flow path of the gas discharged from the housing 2, and a mixed gas can be delivered into the airbag 5. In this case, the through-hole 241 functions as an air intake port for taking in external air (fresh air) toward the lower end 352 of the flow passage 35. In this way, a large amount of fresh air can be sent into the airbag 5 by utilizing the gas flow generated by the gas source inside the housing 2.

[0018] As shown in FIG. 4 , the gas discharge hole 221 has a portion where the cross-sectional area gradually decreases between an upstream side 2211 corresponding to the inside of the housing 2 and a downstream side 2212 corresponding to the outside of the housing 2. Furthermore, because the guide portion 222 protrudes radially outward, the flow passage 35 has a narrowed choke portion 354 between the cover 3 and the guide portion 222. The gas discharged from the gas discharge hole 221 has a sufficiently high discharge speed, and the flow rate reduces the pressure at the choke portion 354 in the flow passage 35, and outside air is drawn in from the lower end 352 of the flow passage 35. At this time, because the cross-sectional area of ​​the flow passage 35 is narrowed by the choke portion 354, the outside air taken in from the through hole 241 flows faster at the choke portion 354. At the same time, the pressure near the lower end 352 of the flow passage 35 decreases, further increasing the intake of outside air via the through hole 241. This rapid flow of gas from the gas discharge hole 221 causes a pressure drop at the throttling portion, and also causes outside air to be introduced into the flow passage 35 via the through-hole 241. Therefore, when gas is discharged upward from the gas discharge hole 221 into the flow passage 35, outside air can be drawn into the flow passage 35 from below the junction 353 where the gas flows and meets the flow path of the gas discharged from the housing 2, and the mixed gas can be delivered into the airbag 5.

[0019] FIG. 5 is a contour diagram showing the results of the velocity distribution obtained by the simulation. FIG. 6 is a contour diagram showing the results of the pressure distribution obtained by the simulation. In the examples of FIGS. 5 and 6, the space from the upstream side of the gas discharge hole 221 to the outside of the housing 2 was analyzed. As shown in FIG. 6, the gas pressure decreases at the exit of the gas discharge hole 221. Also, as shown in FIG. 5, the mixed gas flows from below the flow path 35 to above the flow path 35, drawing in outside air. Note that the simulation did not take into account the airbag, and the pressure is low above the flow path 35 because it is an open space.

[0020] As described above, the cover 3 of this embodiment forms a flow passage 35 along the housing 2, thereby preventing the gas generator 1 from becoming larger in the radial direction of the housing 2, and by drawing in outside air, it is possible to deliver more gas than the amount of gas generated from the gas source.

[0021] <Embodiment 2> In the above-described embodiment, outside air is taken in by providing the through-holes 241 in the flange portion 24 of the housing 2, but the present invention is not limited to this example. That is, an intake path for introducing outside air from outside the airbag 5 may be formed without providing the through-holes 241. In this embodiment, the shape of the cover 3 forms the intake path so that the flow passage 35 extends along the flange portion 24 between the cover 3 and the flange portion 24.

[0022] Fig. 7 is an exploded perspective view showing an example of the configuration of a gas generator. Fig. 8 is a schematic partial cross-sectional view showing an example of a gas generator attached to an airbag. Note that the same reference numerals are used to denote the same components as those shown in embodiment 1, and descriptions thereof will be omitted.

[0023] The cover 3A according to this embodiment is also a cylindrical member capable of covering a portion of the side surface 22 of the housing 2. The cover 3A also includes a large-diameter portion 31A and a small-diameter portion 32A, with the large-diameter portion 31A and the small-diameter portion 32A connected by a connecting portion 33A. However, instead of the flange portion 34 described in the first embodiment, the cover 3A includes a first portion 34A formed by extending the lower end of the large-diameter portion 31A radially outward, a second portion 34B formed by extending the lower end of the small-diameter portion 32A radially outward, and a third portion 34C formed by extending the lower end of the connecting portion 33A radially outward. The first portion 34A is located higher than the second portion 34B. Furthermore, the structure in which the third portion 34C connects the first portion 34A and the second portion 34B is repeated in an annular fashion to form the flange according to this embodiment.

[0024] The inner diameter of the small diameter portion 32A is approximately the same as the outer diameter of the side surface 22 of the housing 2. When the cover 3A is attached to the housing 2, a gas flow passage 35A is formed between the side surface 22 of the housing 2, the large diameter portion 31A, and the connecting portion 33A. The cover 3A also includes irregularities on its radially outward side for extending the flow passage 35A. That is, when the cover 3A is attached to the housing 2, the second portion 34B contacts the flange portion 24 of the housing 2, and gaps 35B are formed between the first portion 34A and the third portion 34C and the flange portion 24. The gaps 35B are also in communication with the flow passage 35A. Note that, for example, the second portion 34B, the flange portion 24, and the airbag 5 may be fixed to the attachment object 4 using bolts 41 and nuts 42 shown in FIG. 8. That is, the second portion 34B is modified in shape to cover the through-hole 242 in the flange portion 24 of the housing 2, and a hole is formed in the second portion 34B at a position corresponding to the through-hole 242. The housing 2 of the gas generator may then be fixed to the attachment object 4 with a bolt 41 and a nut 42 that pass through both the through-hole 242 and the hole in the second portion 34B (so that the attachment object 4 is sandwiched between the second portion 34B and the flange portion 24). The first portion 34A then forms a gap 35B between the airbag 5 and the attachment object 4. Therefore, the gap 35B can function as an intake path for taking external air from outside the airbag 5 into the airbag 5.

[0025] The cover 3A of this embodiment also forms a flow passage 35A mainly along the housing 2, thereby preventing the gas generator 1 from becoming larger in the radial direction of the housing 2, and by drawing in external air, it is possible to deliver more gas than the amount of gas generated from the gas source.

[0026] <Variations> The flow passage 35 according to embodiment 1 and the flow passage 35A according to embodiment 2 need only extend upward from at least the vicinity of the gas exhaust hole 221, and the shapes of the cover 3 and the cover 3A are not particularly limited as long as an air intake port for taking in outside air can be formed on the lower side.

[0027] A check valve may be added to the through-hole 241 according to the first embodiment or the gap 35B according to the second embodiment so as to allow air to flow into the airbag 5 and prevent air from flowing out of the airbag 5. In this way, the shape of the airbag 5 after inflation can be maintained.

[0028] Gas generator 1 and an object to which gas is to be supplied may be connected via a pipe or a hose. Furthermore, the structure for fixing gas generator 1 to an object to which it is to be attached is not limited to the embodiment described above, and housing 2 does not have to have flange portion 24.

[0029] <Embodiment 3> Figure 9 is a partial cross-sectional view of a gas generator 1B in which flange portion 24 of housing 2B is fixed by being sandwiched between an attachment object 4 and a cover 3B. Figure 10 is a perspective view for explaining a guide member 6 according to a modified example. Flange portion 24, attachment object 4, and cover 3B are fixed by forming through holes in locations that do not interfere with the intake port, which serves as an air intake port, and fastening them with nuts through which bolts are passed. Note that the same reference numerals are used for the components shown in embodiment 1, and description thereof will be omitted.

[0030] Gas generator 1B is formed by press-fitting guide member 6, which is separate from housing 2B, into side surface 22 (peripheral side portion) of housing 2B. Furthermore, a cylindrical cover 3B is disposed radially outward of guide member 6 in top view of housing 2B. Guide member 6 can be formed of metal, resin, or the like. Furthermore, a plurality of gas discharge holes 221 are formed in side surface 22 of housing 2B along the circumferential direction of housing 2B, but housing 2B according to this embodiment does not include guide portion 222 of the above-described embodiment. That is, in gas generator 1B, guide member 6 is not formed integrally with housing 2B. Guide member 6 includes a cylindrical portion 61 abutting side surface 22 of the housing, and an inclined surface (guide portion) 62 extending from the cylindrical portion toward cover 3B. Furthermore, a throttle portion 354 is formed in the gap between the tip of inclined surface 62 and cover 3B. Furthermore, guide member 6 is attached to housing 2B by press-fitting cylindrical portion 61 into side surface 22 of gas generator 1B. The cylindrical portion 61 is located below each gas discharge hole 221 on the side surface 22 of the housing. The inclined surface 62 is disposed so as to face the gas discharge holes 221 at an angle.

[0031] The inclined surface 62 of the guide member 6 according to this embodiment has a funnel-like shape that extends 360° in top view, surrounding all of the gas discharge holes 221 from the outside. However, the inclined surface 62 may be formed at a position facing each of the gas discharge holes 221. Therefore, the cylindrical portion 61 may be formed as a single, continuous annular portion in the circumferential direction, and the multiple inclined surfaces 62 may extend radially from the upper end of the cylindrical portion 61 (in the circumferential direction, multiple inclined surfaces 62 are formed at positions corresponding to the gas discharge holes 221). In the modified example shown in FIG. 10 , the entire guide member 6 is formed of an elastic material such as metal, and is divided at one location in the circumferential direction, including the cylindrical portion 61 and the inclined surface 62. The cylindrical portion 61 in FIG. 10 functions like an arc-shaped leaf spring and is press-fitted or expanded into the side surface 22 of the housing 2B. That is, the cylindrical portion 61 can be fastened and fixed to the side surface 22 of the housing 2B by utilizing the contraction force (the force that deforms the cylindrical portion 61 in the direction of reducing its diameter) acting on the cylindrical portion 61. The inclined surface 62 in FIG. 10 also surrounds all of the plurality of gas discharge holes 221 from the outside.

[0032] FIG. 11 shows another modified example of the guide member. The guide member 6A is cylindrical, with multiple tubular portions 61A with a constant diameter and inclined surfaces 62A that increase in diameter upward, arranged alternately in the circumferential direction. The inclined surfaces 62A are formed at positions and with sizes corresponding to the multiple gas discharge holes 221 formed in the side surface 22 of the housing 2B. The guide member 6A is attached to the housing 2B so that the gas discharge holes 221 correspond one-to-one to the inclined surfaces 62A. The inner circumferential surface of the tubular portion 61A extending between adjacent inclined surfaces 62A contacts the side surface 22 of the housing. The guide member 6A of FIG. 11 may be formed of an elastic material and divided at a single location in the circumferential direction, as shown in FIG. 10. In this case, the division point can be provided in the tubular portion 61A between the inclined surfaces 62A.

[0033] In the third embodiment and its modifications, when gas generator 1B is used that includes, as a gas source, a molded article of a solid gas generating agent that generates gas upon combustion, asperities 63 ( FIG. 9 ) may be formed on the side of inclined surface 62 or 62A facing the gas discharge hole (inner peripheral surface). When asperities 63 are formed, even if combustion residues are contained in the generated combustion gas, the residues are more likely to be captured by asperities 63. Asperities 63 may be formed, for example, in the form of multiple protrusions or annular protrusions (grooves) on inclined surface 62 or 62A, or a wire mesh may be laid on inclined surface 62 or 62A (welded to the inner peripheral surface of the inclined surface). Furthermore, asperities 36 may also be formed on at least one surface of inclined surface 62 or 62A that is distal to the upper end (i.e., the side surface of the gas flow path) of inclined surface 62 or 62A, which is located downstream of the gas flow path. Asperities 36 may also be formed by forming multiple protrusions or grooves, or by laying a wire mesh. In this case, the tip side of the cover 3B may be inclined inward in the circumferential direction so that residues can be easily captured by the unevenness 36 portion.

[0034] Fig. 12 shows another modified example of the guide member. The configuration of the guide member differs between Fig. 12 and Fig. 9 . Gas generator 1C of Fig. 12 includes guide member 6B. Guide member 6B is also fixed to side surface 22 of the housing by press fitting or other methods. Guide member 6B of Fig. 12 includes surrounding wall portion 65 that covers from the outside multiple gas discharge holes 221 formed in side surface 22 of housing 2B, a cylindrical portion 61B that abuts against side surface 22 of housing 2B, and an inclined surface (connecting portion) 62B that connects the cylindrical portion and the surrounding wall portion. Surrounding wall portion 65 extends upward (in the direction of the central axis of gas generator 1C), and the gap between surrounding wall portion 65 and cover 3B forms throttle portion 354. In FIG. 12 , the surrounding wall portion 65 is formed continuously 360° in the circumferential direction so as to cover all of the multiple gas discharge holes 221 formed in the side surface 22 of the housing 2B, and the connecting portion 62B is also formed continuously in the circumferential direction accordingly. Furthermore, the connecting portion 62B and the inner surface of the surrounding wall portion 65 (the surface facing the gas discharge holes (opposing surface)) may be uneven. The unevenness of the guide member 6B may be formed by forming annular grooves or irregularities on the surface, similar to the unevenness 63 in FIG. 9 , or by welding a wire mesh to the opposing surface. The guide member 6B shown in FIG. 12 may also be formed with a notch in the circumferential direction as shown in FIG. 10 , and the cylindrical portion 61B may be tightened and fixed to the side surface 22 of the housing 2B using a contraction force acting on the cylindrical portion 61B. Furthermore, as shown in FIG. 11 , the surrounding wall portion 65 and the connecting portion 62B may be positioned and shaped to correspond to each of the multiple gas discharge holes 221.

[0035] <Others> Although the embodiments according to the present disclosure have been described above, each aspect disclosed herein can be combined with other features disclosed herein. Furthermore, the gas generator can be used for devices that provide impact mitigation means or lifesaving means, such as airbag devices worn on the human body, airbag devices mounted on drones, and devices for inflating floats such as life jackets, or devices for securing survival space for crime prevention and disaster prevention purposes, in addition to deploying airbags in vehicles.

[0036] 1: gas generator 2: housing, 21: upper surface, 22: side surface, 221: gas discharge hole, 2211: upstream side, 2212: downstream side, 222: guide portion, 23: bottom surface, 24: flange portion, 241: through hole, 242: through hole 3, 3A: cover, 31, 31A: large diameter portion, 32, 32A: small diameter portion, 33, 33A: connection portion, 34, 34A to 34C: flange portions (34A: first portion, 34B: second portion, 34C: third portion), 35, 35A: flow passage, 351: upper end, 352: lower end, 353: junction, 35B: gap 4: attachment object 5: airbag

Claims

1. A gas generator comprising: a housing that accommodates a gas source that generates gas due to the activation of an igniter, and that is provided with a gas exhaust hole for exhausting the gas; and a cover that covers a part of the housing and forms a gas flow passage between the housing and the cover, the gas exhaust hole connecting the inside of the housing with the inside of the flow passage, and is formed to exhaust the gas toward one end of the flow passage, and when the gas is exhausted from the gas exhaust hole of the housing, an outlet for the gas is formed at one end of the flow passage, and an intake port for taking in outside air is formed at the other end of the flow passage.

2. A gas generator as set forth in claim 1, wherein the flow passage has a constricted section between the cover and the gas discharge hole where the cross-sectional area of ​​the passage is narrowed, and the gas discharged from the gas discharge hole and the outside air taken in from the intake port join together in the vicinity of the constricted section.

3. A gas generator as set forth in claim 2, wherein the gas discharge hole is formed by a guide portion that guides the gas discharge direction so that the gas is discharged toward one end of the flow passage, and the throttle portion is formed between the guide portion and the cover.

4. A gas generator according to claim 3, wherein the guide portion is a constriction portion that gradually reduces the cross-sectional area of ​​the transverse cross section of the gas discharge hole, and the gas discharged from the gas discharge hole and the outside air taken in from the intake port join together in the vicinity of the constriction portion.

5. A gas generator as set forth in claim 1, wherein the housing has a top surface, a bottom surface, and a side periphery connecting the top surface and the bottom surface, the gas discharge hole is provided in the side periphery, and the cover covers at least the outer periphery of the gas discharge hole in the side periphery.

6. A gas generator according to claim 5, wherein a plurality of said gas discharge holes are formed in the circumferential direction on the side peripheral part of said housing, and further wherein a guide section for guiding the gas discharge direction so as to discharge said gas towards one end side of said circulation passage is formed around said gas discharge holes as a separate member from said housing, said guide section is provided at each of the plurality of gas discharge holes, and a constricted section having a constricted cross-sectional area is formed between said guide section and said cover.

7. A gas generator according to claim 5, wherein a plurality of said gas discharge holes are formed circumferentially on the side peripheral part of said housing, and further wherein a guide section is formed around said gas discharge holes to guide the gas discharge direction so that the gas is discharged towards one end of said flow passage, said guide section having an inclined surface covering at least two or more adjacent gas discharge holes from the outside, and wherein a constricted section having a constricted cross-sectional area is formed between said guide section and said cover.

8. A gas generator according to claim 7, wherein a plurality of said gas discharge holes are formed in said side peripheral portion, and said guide portion has a cylindrical portion connected to said inclined surface, said cylindrical portion being fixed to said side peripheral portion.

9. The gas generator according to claim 7, wherein the gas source is a solid molded article of gas generating agent that generates gas by combustion, and wherein irregularities are formed on at least one of the side of the guide portion facing the gas discharge hole and the side of the cover closer to the tip than the upper end of the inclined surface.

10. The gas generator according to claim 5, wherein a plurality of the gas discharge holes are formed circumferentially on the side peripheral part of the housing, and a guide part is formed around the gas discharge hole for guiding the gas discharge direction so that the gas is discharged toward one end side of the circulation passage, and the guide part includes: a surrounding wall part that covers at least two or more adjacent gas discharge holes of the plurality of gas discharge holes from the outside together; a cylindrical part that abuts against the side peripheral part from the outside and fixes the guide part to the housing; and a connecting part that connects the cylindrical part and the surrounding wall part, and a constricted part that narrows the cross-sectional area of ​​its transverse cross section is formed between the surrounding wall part and the cover.

11. A gas generator according to claim 10, wherein the gas source is a solid molded article of gas generating agent that generates gas by combustion, and the guide portion has irregularities formed on the side facing the gas discharge hole.

12. A gas generator according to claim 5, wherein a plurality of the gas discharge holes are formed in the side periphery along the circumferential direction thereof, and the cover is cylindrical with repeated concaves and convexes in the circumferential direction, and the flow passage is formed between the cover and the side periphery at a position corresponding to the gas discharge holes.

13. A gas generator according to claim 5, wherein the housing has a flange portion extending radially outward from the side periphery, and the flange portion has a through-hole that functions as the intake port on the other end side of the flow passage.

14. A gas generator according to claim 5, wherein a plurality of said gas discharge holes are formed in said side peripheral portion along its circumferential direction, said housing has a flange portion extending radially outward from said side peripheral portion, said cover is cylindrical and includes repeated irregularities in the circumferential direction of said cover to form said flow passage between said side peripheral portion of said housing and said cover, and includes irregularities that extend said flow passage radially outward from said cover along said flange portion, and said intake port is formed at an end of said extending direction.

Images