JP2005053440A - Inflator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inflator with high operation reliability.
SOLUTION: A high temperature gas generated from a gas generating agent ignited and combusted in an igniter 43 reliably destroys one first rupturable plate 47, and the high temperature gas flows into internal spaces 16a and 16b to reduce the internal pressure. Raise. As a result, the two second rupturable plates 26 and 36 are destroyed by pressurization, and pressurized gas is injected from the gas discharge ports 25 and 35.
[Selection] Figure 1

Description

  The present invention relates to an inflator suitable for use in an automobile airbag system.

  An inflator used for an air bag system mounted on an automobile is required to have certainty of operation. In particular, in the case where the inflator is of a type that inflates the airbag by releasing pressurized gas filled with high pressure, it is important to destroy the closing means (rupture disk) for enabling the release of the pressurized gas. Various attachment positions and destruction methods of the rupturable plate are known depending on the type and structure of the inflator.

  Patent Document 1 discloses an inflator 100 having an elongated shape as shown in FIG. The inflator 100 includes two containers 112 and 116, and gas discharge ports 124 and 128 on both outer sides. The gas discharge ports 124 and 128 are closed with a rupturable plate 142.

  A connecting chamber 120 is provided at the center, and the two orifices 146 and 147 are respectively closed by the rupturable plate 144 and the two containers 112 and 116 are separated. In the connection chamber 120, a main body 164 for fixing the igniter 160 is disposed from the outside in the radial direction, and the inside is filled with an ignition enhancer 168.

  The pressure generated by the operation of the igniter 160 pressurizes the inside of the connection chamber 120. By this pressurization, the two rupturable plates 144 are broken and the orifices 146 and 147 are opened. After that, as a result of pressurizing the two containers 112 and 116, the two rupturable plates 142 are opened and the gas is discharged. However, the following problems can be considered in the inflator of Patent Document 1.

  (I) In the inflator 100, the two rupturable plates 144 closing the two orifices 146 and 147 are destroyed by increasing the pressure, and the two rupturable plates 142 are also destroyed by increasing the pressure. In this way, since each of the two rupture discs is broken by pressurization in two stages, only one of the two rupture discs 144 is caused by a slight difference in thickness between the two rupture discs 144 or a difference in tensile strength. There is a possibility that only one of the rupturable plates 142 that are destroyed and further close the gas discharge ports 124 and 128 is destroyed, resulting in a single ejection, or one of the rupturable plates bursts with a delay. In such a case, it is conceivable that the inflation rate of the airbag is delayed, the airbag is not deployed evenly, and the deployment of the airbag is delayed, resulting in insufficient protection of the occupant.

(Ii) Since the two containers 112 and 116 are separated by the two rupturable plates 144, it is necessary to fill the gas from separate filling holes, and after the filling is completed, the filling holes are sealed separately. Since it is necessary, man-hours increase.
US 2003/0062713 A1

  An object of the present invention is to provide an inflator suitable for an airbag system that can discharge pressurized gas evenly from two different gas discharge ports.

The invention of claim 1 is an inflator comprising a cylindrical housing filled with pressurized gas and ignition means for releasing high temperature gas into the cylindrical housing as means for solving the problem,
The cylindrical housing is a single space inside, has gas outlets at both ends, and the ventilation path leading to each gas outlet is closed with a rupture disk,
An inflator is provided in which ignition means is attached to a portion excluding both ends of a cylindrical housing, and a path connecting the ignition means and the inside of the cylindrical housing is closed by a single rupturable plate.

  The cylindrical housing preferably has a circular cross section in the width direction, but it does not have to be a perfect circle, and may be an ellipse or a polygonal shape close to a perfect circle, depending on the shape of the space that serves as the inflator mounting portion, etc. However, it is symmetrical with respect to the central portion in the axial direction.

  The ventilation path to the gas discharge port existing in the cylindrical housing exists at both ends, and the size and length of the path are the same.

  The rupturable plates that close the path leading to the gas discharge ports at both ends are of the same material, the same thickness, the same shape, and the same area.

  As the pressurized gas, an inert gas such as argon or helium, nitrogen gas or the like is used. The filling pressure of the pressurized gas is about 10 to 67 MPa.

  In the first aspect of the present invention, since the inside of the cylindrical housing is a single space, when the rupture plate is destroyed by the operation of the ignition means, and the high temperature gas flows into the inside of the cylindrical housing, Evenly throughout the interior. For this reason, since the pressure rise in the entire inside of the cylindrical housing is also uniform, the rupture plates that block the path to the gas discharge ports at both ends are destroyed at the same time, and the pressurized gas is released evenly from the gas discharge ports at both ends. The

  As in the prior art, in a method in which two rupture discs are destroyed in two stages by pressurization, it is difficult to perform simultaneous destruction reliably, and the rupture time of the rupture disc may be shifted or a single ejection may occur. There is. However, in the present invention, one rupturable plate is reliably destroyed by the ignition means, and the two rupturable plates are destroyed by pressurization, so there is little deviation in the destruction time of the two rupturable plates.

  Moreover, since the inside of the cylindrical housing is a single space, the filling of the pressurized gas is completed with one filling, and the sealing operation of the gas filling hole after the filling is completed with one time.

  According to a second aspect of the present invention, in the inflator according to the first aspect, the ignition means includes an igniter and a gas generating agent housed in an ignition means housing serving as an ignition means chamber. Provided is the one in which the one rupturable plate is attached at a position facing directly.

  The structure of the ignition means is not particularly limited as long as it has a function of releasing a hot gas or a pressure wave (shock wave) inside the cylindrical housing. For example, an igniter (electric igniter equipped with an igniting agent) is ignited and burned by the operation of the igniter in the ignition means housing (the internal space becomes the ignition means chamber), and high temperature gas is generated. A gas containing a gas generating agent is applicable.

  The shape of the ignition means housing is not particularly limited, and the ignition means housing is integrated with the cylindrical housing by means such as welding.

  With this structure, the igniter can be easily attached, the positional relationship between the igniter and the rupturable plate can be easily adjusted, and the destructibility of the rupturable plate can be improved. Note that the rupturable plate may be either a method in which a gas generating agent is ignited and burned by an igniter and then destroyed by a high temperature gas or a shock wave generated, or a method in which the gas is destroyed only by an igniter. The following two structures can be employed as the inflator of the present invention.

  (I) In the case of a method in which a rupture disk is destroyed by an igniter and a gas generating agent, the gas generating agent is accommodated between the igniter and the rupture disk in a path communicating with the ignition means and the inside of the cylindrical housing. The In this case, the gas generating agent is accommodated in a normal pressure atmosphere.

  (Ii) In the case of the method of destroying the rupturable plate by the igniter, the gas generating agent is accommodated between the rupturable plate and the cylindrical housing in a path communicating the ignition means and the inside of the cylindrical housing. In this case, the gas generating agent is accommodated in a high-pressure atmosphere.

  According to a third aspect of the present invention, in the inflator according to the second aspect, the ignition means housing is attached by dividing the cylindrical housing into two parts, and the inside of the cylindrical housing is simply formed by the communication hole provided in the ignition means housing. Provide what forms a space.

  By attaching the ignition means in this way, the entire inflator can be made compact. Since the ignition means housing divides the cylindrical housing into two parts, the ignition means housing has a wall surface having an area equal to or larger than the cross-sectional area in the width direction of the cylindrical housing.

  In both cases (i) and (ii), the communication hole formed in the ignition means housing has a flow passage cross-sectional area that does not substantially cause a pressure loss with respect to the gas flow.

  According to a fourth aspect of the present invention, there is provided the inflator according to any one of the first to third aspects, wherein the ignition means is attached to a central portion in the axial direction of the cylindrical housing.

  Since the inflator is symmetrical, it is not necessary to define the mounting direction when mounting the inflator, so that workability is improved.

  The invention according to claim 5 is the inflator according to any one of claims 1 to 4, wherein each of the ventilation paths to the gas discharge ports at both ends is closed by one bursting plate. provide.

  If there is one ventilation path and one rupturable plate, the rupturable plate is reliably destroyed, the ventilation path is opened, and pressurized gas is released.

  A sixth aspect of the present invention provides the inflator according to any one of the first to fifth aspects, wherein the center of the ventilation path reaching the gas discharge ports at both ends coincides with the central axis of the cylindrical housing.

  Since the parts are symmetrical, manufacturing is easy, and there is no need to determine the orientation when mounting the inflator or the parts.

  A seventh aspect of the present invention provides the inflator according to any one of the first to sixth aspects, wherein the pressurized gas consists of only helium.

  Since the theoretical value of sound speed is as fast as 1010 m / s (23 ° C.), helium has a higher impact propagation speed than other pressurized gases when the rupturable plate is destroyed by the operation of the ignition means. For this reason, the timing at which the rupturable plate that closes the gas discharge port is destroyed is advanced, and the start of discharge of the pressurized gas can be accelerated.

  According to the inflator of the present invention, pressurized gas can be injected simultaneously and reliably from the gas discharge ports provided at both ends of the housing. For this reason, the operation reliability when applied to an automobile airbag system is enhanced.

(1) First Embodiment A first embodiment will be described with reference to FIG. FIG. 1 is an axial sectional view of an inflator.

  The inflator 10 includes a cylindrical housing 15 filled with a pressurized gas, and ignition means 40 for releasing high temperature gas into the internal space 16 (16a, 16b) of the cylindrical housing 15.

  The cylindrical housing 15 is closed at one end side by a diffuser cap 22. The diffuser cap 22 includes a cap portion 23 and a flange portion 24 extending outward from the opening portion of the cap portion 23, and a contact portion between the flange portion 24 and the opening portion of the cylindrical housing 15 is fixed by welding. Yes.

  The cap portion 23 of the diffuser cap 22 is provided with a required number of gas discharge ports 25. If necessary, a cylindrical filter made of a wire mesh or the like may be disposed at a position facing the gas discharge port 25 in the cap portion 23 in order to capture fragments of the second rupturable plate 26.

  The space in the cap part 23 is a ventilation path leading to the gas discharge port 25, and the disk-shaped second rupturable plate 26 (in the figure, due to pressurized gas) is located at a position where the opening part 27 of the cap part 23 is closed. It is shown in a deformed state under pressure.) Is attached. In FIG. 1, the amount of gas discharged from the gas discharge port 25 is adjusted by the opening 27 of the portion to which the second rupturable plate 26 is attached.

  The second rupturable plate 26 is fixed to the surface of the flange portion 24 by welding at the peripheral edge thereof. Since the second rupturable plate 26 blocks the ventilation path to the gas discharge port 25, the inside of the cap portion 23 communicating with the external atmosphere through the gas discharge port 25 is at normal pressure.

  The other end side opening of the cylindrical housing 15 is closed with a diffuser cap 32. The diffuser cap 32 includes a cap portion 33 and a flange portion 34 extending outward from the opening portion of the cap portion 33, and a contact portion between the flange portion 34 and the opening portion of the cylindrical housing 15 is fixed by welding. Yes.

  The cap portion 33 of the diffuser cap 32 is provided with a required number of gas discharge ports 35. In addition, in order to catch the fragments of the second rupturable plate 36, a cylindrical filter made of a wire mesh or the like may be disposed at a position facing the gas discharge port 35 in the cap portion 33 as necessary.

  The space in the cap part 33 is a ventilation path to the gas discharge port 35, and the disk-shaped second rupturable plate 36 (however, in the figure by the pressurized gas) is closed at the position where the opening part 37 of the cap part 33 is closed. It is shown in a deformed state under pressure.) Is attached. In FIG. 1, the amount of gas discharged from the gas discharge port 35 is adjusted by the opening 37 of the portion to which the second rupturable plate 36 is attached.

  The second rupturable plate 36 is fixed to the surface of the flange portion 34 by welding at the peripheral edge thereof. Since the second rupturable plate 36 blocks the ventilation path leading to the gas discharge port 35, the inside of the cap portion 33 communicating with the external atmosphere through the gas discharge port 35 is at normal pressure.

  The centers of the paths (the cap part 23 and the cap part 33, respectively) reaching the gas discharge ports on both ends coincide with the central axis of the cylindrical housing 15, and the two paths have the same size and length. By doing so, since the parts are symmetrical, manufacturing is easy and there is no need to determine the orientation when the inflator is attached.

  The two second rupturable plates 26 and 36 that close the two paths are of the same material, the same thickness, the same shape, the same area, and the same strength.

  The ignition means 40 is an ignition means housing 41 in which an igniter 43 and a gas generating agent (not shown) are accommodated in an ignition means housing 41 (the inside is an ignition means chamber 42). The inner space 16 of the cylindrical housing 15 is attached so as to be divided into two equal parts.

  The ignition means housing 41 includes a main body 41a and a lid portion 41b. In the assembly process, the first rupturable plate 47 is fixed to the stepped portion 44 of the main body 41a by welding, and then the lid portion 41b is fixed to the stepped portion 44 by welding. .

  The ignition means housing 41 and the cylindrical housing 15 are fixed by welding at the contact portion. After the igniter 43 is fitted from the opening side of the ignition means housing 41, the peripheral portion 41c is crimped and fixed.

  By attaching the ignition means 40 in this manner, the overall size of the inflator 10 can be made more compact than when it is attached to the outer peripheral surface of the cylindrical housing 15. In addition, since the inflator 10 is symmetrical, it is not necessary to define the mounting direction when the inflator 10 is mounted, and workability is improved.

  The ignition means housing 41 is provided with second communication passages 46a, 46b, 46c extending in the axial direction of the inflator 10. By the second communication passages 46a, 46b, 46c, the internal spaces 16a, 16b divided into two equal parts are connected to form a single space. The diameters of the second communication path 46a and the second communication paths 46b and 46c are different, but they may all be the same. However, the second communication passages 46a, 46b, 46c have flow passage cross-sectional areas that do not substantially cause a pressure loss with respect to the gas passing therethrough.

  The ignition means chamber 42 communicates with the second communication passage 46a through a first communication passage 45 extending in the radial direction of the inflator 10.

  The first communication passage 45 and the second communication passages 46 a, b, and c serve as a route for communicating the ignition means 40 and the internal space 16, and the first communication passage 45 is closed by the first rupturable plate 47. The first rupturable plate 47 and the igniter 43 face each other.

  In FIG. 1, the first rupturable plate 47 is destroyed by the igniter 43 and the gas generating agent. The gas generating agent is accommodated in the ignition means chamber 42 between the igniter 43 and the first rupturable plate 47. Therefore, the gas generating agent is accommodated in an atmospheric pressure atmosphere.

  As described above, the internal space 16 (16a, 16b) of the cylindrical housing 15 is a single space, and is airtight by the first rupturable plate 47, the two second rupturable plates 26, 36, and the diffuser caps 22, 32. Is maintained. Note that the pressurized gas has a gap between one of the diffuser caps 22 and 32 and the opening of the cylindrical housing 15 (provided with a gas filling hole if necessary) before the diffuser caps 22 and 32 are fixed. After filling, the welding is fixed. The pressurized gas is preferably helium alone.

  Next, the operation when the inflator 10 is incorporated in an automobile airbag system will be described.

  During the collision of the automobile, the gas generating agent in the ignition means chamber 42 is ignited and burned by the operation of the igniter 43, high temperature gas is generated, and the first rupturable plate 47 is destroyed. At this time, since the igniter 43, the ignition means chamber 42 in which the gas generating agent is accommodated, and the first rupturable plate 47 are arranged on the same line, the flame and the high-temperature gas travel straight to the first rupturable plate 47, and the destructive force Is increased.

  The hot gas flows into the internal space 16 (16a, 16b) through the first communication path 45 and the second communication paths 46a, b, c, and spreads uniformly to increase the internal pressure. Since the internal spaces 16a and 16b have the same shape and the same volume, the pressure rises evenly, and the two second rupturable plates 26 and 36 are evenly pressurized, so that they are destroyed at the same time.

  Thus, as a result of the destruction of one first rupturable plate 47 by the igniter 43 and the gas generating agent, the pressure rise in the internal spaces 16a and 16b becomes equal, and the two second rupturable plates 26, Since the pressure applied to 36 is uniform, it will be destroyed at the same time.

  Thereafter, the pressurized gas is discharged from the gas discharge ports 25 and 35 to inflate the airbag. At this time, since the same amount of gas is injected from the gas discharge ports 25 and 35, the airbag is deployed evenly.

  In addition, when only helium is used as the pressurizing gas (however, the case where a small amount of other gas is included as an impurity) is used, helium has a theoretical sound speed as fast as 1010 m / s (23 ° C). When the first rupturable plate 47 is broken by the operation of the igniter 23, the impact propagation speed is higher than that of other pressurized gases. For this reason, from the destruction of the first rupturable plate 47, the timing at which the two second rupturable plates 26, 36 that close the gas discharge ports 25, 35 at both ends are broken is earlier, and the start of discharge of the pressurized gas is accelerated. Can do.

(2) Second Embodiment A second embodiment will be described with reference to FIG. FIG. 1 is an axial cross-sectional view of the inflator 100.

  Since the inflator 100 has the same structure as that of the inflator 10 shown in FIG. 1 except for the ignition means 50, the same parts are denoted by the same reference numerals and description thereof is omitted.

  The ignition means 50 is configured such that an igniter 53 and a gas generating agent (not shown) are accommodated in an ignition means housing 51 (the inside is an ignition means chamber). The internal space 16 (16a, 16b) of the housing 15 is attached so as to be divided into two equal parts. The ignition means housing 51 and the cylindrical housing 15 are fixed by welding at the contact portion. After the igniter 53 is fitted from the opening side of the ignition means housing 51, the peripheral portion 51c is crimped and fixed.

  The ignition means housing 51 includes a main body 51a and a lid portion 51b. In the assembly process, the first rupturable plate 57 is fixed to the stepped portion 59 of the main body 51a by welding, and then the lid portion 51b is fixed by attachment welding. .

  By attaching the ignition means 50 in this way, the overall size of the inflator 100 can be made more compact than when it is attached to the outer peripheral surface of the cylindrical housing 15. In addition, since the inflator 100 is symmetrical, it is not necessary to define the mounting direction when the inflator 100 is mounted, so that workability is improved.

  The ignition means chamber includes a storage space for the igniter 53 and a storage space 54 for the gas generating agent. A first communication passage 55 is provided between the two spaces, and the first communication passage 55 is closed by a first rupturable plate 57. Has been. The first rupturable plate 57 and the igniter 53 face each other.

  The ignition means housing 51 is provided with second communication passages 56a and 56b that communicate the internal spaces 16a and 16b with the gas generating agent storage space 54. The second communication passages 56a and 56b allow the internal space 16a, 16b is a single space.

  In FIG. 2, the first rupturable plate 57 is destroyed only by the igniter 53, and the gas generating agent is accommodated in the gas generating agent accommodating space 54 between the first rupturable plate 57 and the internal space 16. The gas generating agent is accommodated in a pressurized atmosphere.

  The operation of the inflator 100 is the same as the operation of the inflator 10 except that the method of breaking the first rupturable plate 47 is different. Further, the mechanism for adjusting the amount of gas discharged from the diffuser caps 22 and 32 and the cross-sectional area of the second communication passages 56a and 56b are the same as those of the inflator 10.

An axial sectional view of an inflator. The axial direction sectional drawing of the inflator of another form.

Explanation of symbols

10, 100 inflator
15 Tubular housing
22, 32 Diffuser cap
25, 35 Gas outlet
26, 36 2nd rupture disc
40 Ignition means
43 Igniter
47 1st rupture disc

Claims (7)

A tubular housing filled with pressurized gas, and an inflator comprising ignition means for releasing hot gas into the tubular housing;
The cylindrical housing is a single space inside, has gas outlets at both ends, and the ventilation path leading to each gas outlet is closed with a rupture disk,
An inflator in which an ignition means is attached to a portion excluding both ends of a cylindrical housing, and a path connecting the ignition means and the inside of the cylindrical housing is closed by a single rupturable plate.   The ignition means is an ignition means housing in which an ignition means and a gas generating agent are accommodated in an ignition means chamber, and the one bursting plate is attached to a position facing the igniter in the ignition means chamber. The inflator according to claim 1.   The inflator according to claim 2, wherein the ignition means housing is attached by dividing the cylindrical housing into two parts, and the inside of the cylindrical housing forms a single space by a communication hole provided in the ignition means housing.   The inflator according to any one of claims 1 to 3, wherein the ignition means is attached to an axially central portion of the cylindrical housing.   The inflator according to any one of claims 1 to 4, wherein there is one ventilation path to each of the gas discharge ports at both ends, and each is closed by a single rupturable plate.   The inflator according to any one of claims 1 to 5, wherein the center of the ventilation path leading to the gas discharge ports at both ends coincides with the central axis of the cylindrical housing. The inflator according to any one of claims 1 to 6, wherein the pressurized gas consists of only helium.

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