JP2008068792A - Gas generator for seat belt retractor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gas generator in which the rise of the output at the initial operation is small. <P>SOLUTION: The inside of a cup member 20 covered on an igniter assembly 10 is separated into three combustion chambers 41, 42, 43 by a first partition 31 and a second partition 32. During the operation, a second gas generating agent 52 in the second combustion chamber 42 burns first, and gas generating agents in the other two combustion chambers 42, 43 burn later. Thus, the rise of the output in the initial operation is suppressed. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a gas generator for a seat belt retractor.

In various vehicles such as automobiles, a seat belt having a pretensioner mechanism for protecting the occupant by pulling the seat belt is employed in order to protect the occupant from an impact generated at the time of a collision.
Generally, such a pretensioner for a seat belt includes a mechanism for pulling the seat belt and a gas generator for operating the mechanism, and a small gas generator having a small overall volume is used. ing. This small gas generator includes an ignition device such as an igniter and a gas generating agent that burns by the ignition device and generates combustion gas. Generally, the small gas generator is in contact with the ignition device in a cup-shaped member. The gas generating agent is filled.

  A small gas generator for a pretensioner is described in Patent Document 1, for example. In the small gas generator described in this document, the inside of the cup-shaped member that accommodates the gas generating agent is a single space, and the single space is filled with the gas generating agent. Moreover, the weak part which is cleaved when exhausting combustion gas is provided in the surrounding wall part of the cup-shaped member.

  In the small gas generator of Patent Document 1, the ignition of the ignition device causes the gas generating agent filled in the cup-shaped member to ignite and burn almost simultaneously, generating combustion gas in an instant, It is destroyed and combustion gas is released from it.

However, when such a small gas generator that generates combustion gas at once is installed in the seat belt retractor, a large amount of gas is supplied to the seat belt retractor in a short time, so the load on the seat belt retractor It is easy to take. For this reason, it becomes necessary to increase the strength of the parts or to make the assembly strong, which increases the manufacturing cost.
JP 2005-225274 A

  It is an object of the present invention to provide a small gas generator that has a relatively slow rise in output and is difficult to apply a load to a retractor.

[Claim 1]
As a means for solving the problems, the present invention
A gas generator having an igniter assembly in which one igniter having an igniter is fixed to an igniter collar, and an outer cup member covering at least a portion including the igniter of the igniter,
The inside of the cup member is separated into two or more combustion chambers by one or more partition members, and a gas generating agent is accommodated in the one or more combustion chambers,
Provided is a gas generator for a seat belt retractor in which combustion of a gas generating agent in another combustion chamber is started by generating heat in one combustion chamber by the operation of the igniter.

  In the present invention, the term “outer cup member” refers to an outer cup member and an inner cup member when one or more other cup members are arranged as a partition member inside the cup member. It is used to distinguish the cup member (inner cup member).

  The partition member used by this invention should just be what can isolate | separate the inside of an outer side cup member into several space (combustion chamber), and can be made into disk shape, cup shape, and other desired shapes. There are two or more combustion chambers, and it is sufficient that the gas generating agent is accommodated in at least one combustion chamber. Therefore, the gas generating agent may be accommodated in all the combustion chambers, or there may be combustion chambers in which the gas generating agent is not accommodated. An ignition portion of an igniter is disposed in the combustion chamber that does not contain the gas generating agent. The volume and shape of the plurality of combustion chambers separated by the partition member are not particularly limited, and the composition, amount, and shape of the gas generating agent accommodated in each combustion chamber are not particularly limited.

  In the gas generator for a seat belt retractor according to the present invention, the gas generating agent in one combustion chamber is ignited and burned by the operation of the igniter, or the igniter of the igniter is separated by the partition member. The ignition agent in the ignition part is ignited and combusted to generate heat (flame, high-temperature gas, etc.), whereby the gas generating agent in the other combustion chamber is ignited and combustion is started.

  In addition, since each combustion chamber is separated, there is no hole communicating between the combustion chambers, and due to heat generation in one combustion chamber (as described above, heat generation by combustion of a gas generating agent or combustion of an ignition agent), When the partition member generates heat at high temperature (heat conduction through the partition member), or the partition member is burned out or deformed, the gas is transferred to the gas generating agent in another combustion chamber. In addition, a communication hole is provided in the partition member that separates the combustion chambers, and the communication hole is closed with a seal tape, and the heat is generated in one combustion chamber to destroy the seal tape and open the communication hole. The gas generating agent in another combustion chamber may be ignited and combusted through the formed communication hole.

  Therefore, the entire amount of the gas generating agent accommodated in the cup member is not ignited and burned at a time, but gradually ignited and burned. Combustion is suppressed, and the amount of gas generated in the initial stage of operation is suppressed (that is, rising of the initial output is suppressed).

  And since the rise of the output of the operation | movement initial stage is suppressed in this way, the load to the seatbelt retractor to combine becomes small and it becomes unnecessary to make the components strength of a retractor high. Therefore, the manufacturing cost of the retractor can be suppressed.

  The gas generating agent accommodated in each combustion chamber may be the same in shape and filling amount, or may be different. When the shape of the gas generant is different for each combustion chamber, if the area per unit mass of the gas generant that burns late is increased, the load on the seat belt retractor is kept small and the output rise at the initial stage of operation is increased. Complementing the delay, an output comparable to that of a conventional gas generator can be obtained, and the time to reach the output can be made the same.

  In addition, depending on the way the partition plates are arranged and the amount of the gas generating agent filled in each combustion chamber, it can be made into a gas generator with various output forms. Generator can be provided.

[Claim 2]
The present invention provides other means for solving the problems,
The inside of the outer cup member is separated by two partition members so that three combustion chambers are formed in the axial direction, and among the three combustion chambers, an intermediate combustion chamber includes the ignition portion. A gas generator for a seat belt retractor according to claim 1, wherein a gas generating agent is accommodated in all the combustion chambers.

  When three combustion chambers are formed in the axial direction in this way, the structure is simple and the assembly is facilitated. Further, since the combustion of the gas generating agent is started from the intermediate combustion chamber including the igniter of the igniter, the gas generating agent in the combustion chamber can be burned almost simultaneously in both adjacent combustion chambers. All three combustion chambers are filled with a gas generating agent.

[Claim 3]
In another aspect of the present invention, the inside of the outer cup member is separated into two combustion chambers by one partition member, the ignition portion is located in one combustion chamber, and the partition member is 2 The gas for a seat belt retractor according to claim 1, further comprising: a communication hole communicating with one combustion chamber, wherein the transfer of heat to another combustion chamber is adjusted by adjusting an opening area of the communication hole. Provide a generator.

  The communication hole may be opened or may be closed with an aluminum tape or the like that is easily broken during operation.

  Since the communication hole is formed in the partition member that separates the two combustion chambers, a combustion product such as a flame or a high-temperature gas generated in one combustion chamber enters the other combustion chamber through the communication hole, and The gas generating agent inside is ignited and burned.

  In the present invention, by adjusting the opening area of the communication hole to control the amount of combustion products flowing from one combustion chamber into the other combustion chamber, combustion at the initial stage of operation is suppressed, and the initial gas is suppressed. The generation amount is suppressed (that is, the rise of the initial output is suppressed).

[Claim 4]
In another aspect of the present invention, the inside of the outer cup member is separated into two combustion chambers by one partition member, the ignition portion is located in one combustion chamber, and the partition member is 2 The seat according to any one of claims 1 to 3, wherein the seat has a communication hole communicating with one combustion chamber, and adjusts an opening position of the communication hole to adjust a transfer of heat to another combustion chamber. A gas generator for a belt retractor is provided.

  The communication hole may be opened or may be closed with an aluminum tape or the like that is easily broken during operation.

  Since the communication hole is formed in the partition member that separates the two combustion chambers, a combustion product such as a flame or a high-temperature gas generated in one combustion chamber enters the other combustion chamber through the communication hole, and The gas generating agent inside is ignited and burned.

  At this time, the gas generating agent in the vicinity of the communication hole is ignited and burned first, and the gas generating agent at a position away from the communication hole is ignited and burned with a delay. For this reason, by adjusting the formation position of the communication hole of the partition member, the gas generation amount existing in the vicinity of the communication hole is reduced, and the amount of the gas generating agent at the position away from the communication hole is increased. Combustion is suppressed, and an initial gas generation amount is suppressed (that is, an initial output rise is suppressed).

[Claim 5]
The present invention provides other means for solving the problems,
The one partition member is an inner cup member that covers the ignition part, and the outer cup member is further covered outside the inner cup member,
The inner cup member includes an outer wall surface having the communication hole and an outer wall surface not having the communication hole, and an interval between the outer wall surface having the communication hole and the inner wall surface of the outer cup member is the communication hole. The gas generator for a seat belt retractor according to claim 3 or 4, wherein the gas generator is smaller than an interval between an outer wall surface that does not include the inner wall surface and an inner wall surface of the outer cup member.

  Thus, when the relationship between the outer wall surface having the communication hole and the inner wall surface of the outer cup member is smaller than the interval between the outer wall surface having no communication hole and the inner wall surface of the outer cup member, When the gas generating agent is stored in the outer wall surface having the communication hole and the inner wall surface of the outer cup member, the amount of the gas generating agent existing between the outer wall surface having no communication hole and the outer cup member is larger. Less than the amount of gas generant present between the wall surfaces.

  Therefore, as described above, by adjusting the opening area of the communication hole or the opening position of the communication hole, the initial combustion is suppressed and the initial gas generation amount is suppressed (that is, the initial output rise is suppressed). )

[Claim 6]
In another aspect of the present invention, the outer wall surface having the communication hole of the inner cup member is a bottom surface, and the outer wall surface not having the communication hole of the inner cup member is a peripheral surface. The gas generator for a seat belt retractor according to claim 5, wherein an outer wall surface having the communication hole of the inner cup member is a peripheral surface, and an outer wall surface not having the communication hole of the inner cup member is a bottom surface. To do.

  By appropriately setting the size and shape of the outer cup member and the inner cup member disposed in the outer cup member, and adjusting the position of the communication hole formed in the inner cup member, the above-mentioned "outer wall surface having the communication hole" The distance between the inner wall surface of the outer cup member and the inner wall surface of the outer cup member can be satisfied.

  According to the gas generator of the present invention, combustion at the initial stage of operation can be suppressed, and rising of the initial output can be suppressed without lowering the maximum output. Therefore, the retractor with a simple structure can be easily assembled without increasing the strength of the combined seat belt retractor more than necessary. Furthermore, since the operating performance of the gas generator can be adjusted according to the retractor, it is possible to provide a gas generator having a wide range of application to the retractor.

(1) Gas generator of FIG. 1 FIG. 1 is a longitudinal sectional view of a gas generator 1 for a seat belt retractor.

  In the igniter assembly 10, an electric igniter 11 is fitted and fixed to an igniter collar 12. The igniter 11 has an ignition part 13 filled with an ignition agent (for example, one containing zirconium and perchlorate), and is connected to an external power source via a conductive pin 14. The igniter collar 12 is made of metal, and the igniter 11 is fixed by caulking the opening peripheral edge 15 (caulking portion 15).

  The cup member 20 has a circular cross section in the width direction, a flange 21 is formed in the opening, and a weakened portion 22 formed with a smaller thickness than the other peripheral wall portions on the peripheral wall portion. Is formed. The cup member 20 is fixed to the igniter collar 12 by caulking the annular protrusion 16 of the igniter collar 12 at the flange 21, and the inside is blocked from the external atmosphere.

  The interior of the cup member 20 is separated into a first combustion chamber 41, a second combustion chamber 42, and a third combustion chamber 43 by the first partition plate 31 and the second partition plate 32. The first combustion chamber 41 is densely filled with the first gas generating agent 51, the second combustion chamber 42 is densely filled with the second gas generating agent 52, and the third combustion chamber 43 is filled with the third gas generating agent. 53 is closely packed. The first partition plate 31 and the second partition plate 32 are formed of stainless steel plates having a thickness of 0.5 mm. All the gas generating agents have the same composition ratio, the same shape, and the same size.

  The first partition plate 31 has a disk shape, is supported on one surface by the first gas generating agent 51 filled in the first combustion chamber 41, and the second gas filled in the second combustion chamber 42. The other surface is supported by the generating agent 52 and the ignition part 13.

  The second partition plate 32 has an annular flat plate portion 32 a and an annular projection portion 32 b formed vertically from the hole, and the inner circumferential surface of the annular projection portion 32 b abuts on a partial circumferential surface of the ignition portion 13. The remaining peripheral surface of the ignition part 13 is exposed in the second combustion chamber 42. One surface of the annular flat plate portion 32a is supported by the second gas generating agent 52 filled in the second combustion chamber 42, and the third gas generating agent 53 and the caulking portion 15 filled in the third combustion chamber 43 The other side is supported.

  Next, operation | movement of the gas generator 1 for seatbelt retractors is demonstrated. When the igniter 11 is activated, combustion products are generated from the ignition unit 13. This first ignites the second gas generating agent 52 present in the second combustion chamber 42. Thereby, the weak part 22 of the cup member 20 peripheral wall part is cleaved, and the combustion gas is discharged from the cleaved part. At the same time, the heat of combustion in the second combustion chamber 42 is transmitted through the partition plates 31 and 32, and the first gas generating agent 51 in the first combustion chamber 41 and the third gas generating agent 53 in the third combustion chamber 43 are ignited and burned. Is started.

  In the gas generator of FIG. 1, the combustion heat in the second combustion chamber 42 is transmitted through the partition plates 31 and 32, whereby the first gas generating agent 51 and the third gas generating agent 53 are ignited and burned. 31 and 32 are provided with communication holes closed with a seal tape, and the seal tape is cleaved to open the communication holes, whereby the first gas generating agent 51 and the third gas generating agent 53 are ignited and burned. You may do it.

  In this way, the second gas generating agent 52 is ignited and combusted first, and the first gas generating agent 51 and the third gas generating agent 53 are ignited and combusted with a delay. The amount of gas generation is suppressed (that is, the rise of the initial output is suppressed). This suppresses the load on the pretensioner to which the gas generator 1 is assembled, and it becomes unnecessary to increase the component strength of the pretensioner, so that assembly is facilitated.

(2) Gas Generator of FIG. 2 FIG. 2 is a longitudinal sectional view of a gas generator 2 for seat belt retractor which is another embodiment. The same numbers as those in FIG. 1 mean the same components. In the present embodiment, since the inner cup member 60 is used, the “cup member 20” is referred to as the “outer cup member 20”.

  In FIG. 2, an inner cup member 60 is used as a partition member, and the inner cup member 60 is fitted into the ignition part 13 from the opening side by adjusting the inner diameter and the outer diameter of the ignition part 13 of the igniter. It is. The inner cup member 60 is made of stainless steel having a thickness of 0.5 mm. A space between the inner cup member 60 and the outer cup member 20 serves as a combustion chamber 44, and the gas generating agent 54 is closely packed.

  The inner cup member 60 has a peripheral surface 61 and a bottom surface 62, and an opening 63 is formed at the center of the bottom surface 62. Since the opening 63 is a hole through which the generated combustion product is discharged when the igniter 11 is operated, the amount of combustion product released per hour can be controlled by increasing or decreasing the opening area. . The opening 63 may remain open when the diameter of the opening 63 is smaller than the minimum length of the gas generating agent 54, but when the diameter is larger, the opening 63 may prevent the gas generating agent 54 from entering the internal space 64. It is closed with a sealing tape such as aluminum. In the space 64 surrounded by the ignition part 13 and the inner cup member 60, the gas generating agent 54 does not exist, but a gas generating agent that acts as a transfer agent or a transfer agent for assisting the ignition of the gas generating agent 54 is generated. An agent may be arranged.

  The distance between the bottom surface 62 of the inner cup member 60 and the bottom surface 20b of the outer cup member 20 is set to be smaller than the distance between the peripheral surface 61 of the inner cup member 60 and the peripheral surface 20a of the outer cup member 20. ing. For this reason, the filling amount per unit volume of the gas generating agent 54 is smaller on the bottom surface 62 side of the inner cup member than on the peripheral surface 61 side of the inner cup member.

  Next, the operation of the seat belt retractor gas generator 2 will be described. When the igniter 11 is activated, a combustion product is generated from the igniter 13 and discharged from the opening 63 of the inner cup member toward the bottom surface 20b of the outer cup member. At this time, the discharge amount is controlled by the opening area of the opening 63.

  First, the gas generating agent 54 facing the opening 63 between the bottom surface 62 of the inner cup member and the bottom surface 20b of the outer cup member is ignited and burned, and the fragile portion 22 is cleaved by a small amount of generated gas. Release gas to the outside. Subsequently, the gas generating agent 54 between the peripheral surface 61 of the inner cup member and the peripheral surface 20a of the outer cup member is ignited and burned. The gas generated thereby is also released to the outside from the fragile portion 22 that has been cleaved.

  In this way, the gas generating agent 54 at the position facing the opening 63 is ignited and burned first, and the gas generating agent 54 at a position away from the opening 63 is ignited and burned with a delay. Combustion is suppressed, and the initial gas generation amount is suppressed (that is, the rising of the initial output is suppressed). This suppresses the load on the pretensioner to which the gas generator 2 is assembled, and it is not necessary to increase the component strength of the pretensioner, so that assembly is facilitated.

(3) Gas Generator of FIG. 3 FIG. 3 is a longitudinal sectional view of a gas generator 3 for a seat belt retractor which is another embodiment. The same numbers as those in FIG. 1 mean the same components. In the present embodiment, since the inner cup member 70 is used, the “cup member 20” is referred to as the “outer cup member 20”.

  In FIG. 3, an inner cup member 70 is used as a partition member, and the inner cup member 70 is fitted into the ignition part 13 from the opening side by adjusting the inner diameter and the outer diameter of the ignition part 13 of the igniter. It is. The inner cup member 70 is made of stainless steel having a thickness of 0.5 mm. A space between the inner cup member 70 and the outer cup member 20 serves as a combustion chamber 45, and the gas generating agent 55 is tightly filled.

  The inner cup member 70 has a peripheral surface 71 and a bottom surface 72, and a plurality of openings 73 are formed in the peripheral surface 72 at equal intervals. Since the opening 73 is a hole through which the generated combustion product is released when the igniter 11 is activated, the amount of combustion product released per hour can be controlled by increasing or decreasing the opening area. . The opening 73 may remain open when the diameter of the opening 73 is smaller than the minimum length of the gas generating agent 55, but when the diameter is larger, the opening 73 may prevent the gas generating agent 55 from entering the internal space 74. It is closed with a sealing tape such as aluminum. The gas generating agent 55 does not exist in the space 74 surrounded by the ignition part 13 and the inner cup member 70, but a transfer agent for assisting the ignition of the gas generating agent 55 may be arranged.

  The distance between the peripheral surface 71 of the inner cup member 70 and the peripheral surface 20a of the outer cup member 20 is set to be smaller than the distance between the bottom surface 72 of the inner cup member 70 and the bottom surface 20b of the outer cup member 20. ing. For this reason, the filling amount per unit volume of the gas generating agent 55 is smaller on the peripheral surface 71 side of the inner cup member than on the bottom surface 72 side of the inner cup member.

  Next, the operation of the seat belt retractor gas generator 3 will be described. When the igniter 11 is actuated, combustion products are generated from the ignition part 13 and discharged from the opening 73 of the inner cup member toward the peripheral surface 20a of the outer cup member. At this time, the discharge amount is controlled by the opening area of the opening 73.

  Then, the gas generating agent 55 that first faces the opening 73 and is between the peripheral surface 71 of the inner cup member and the peripheral surface 20a of the outer cup member is ignited and burned, and the outer cup member 20 is formed with a small amount of generated gas. Cleavage and release gas to the outside. 1 and FIG. 2, when the fragile portion is provided, the fragile portion is cleaved, and then the gas generating agent 55 located between the bottom surface 72 of the inner cup member and the bottom surface 20b of the outer cup member is ignited. Burned. The gas generated thereby is also released from the cleaved portion of the cup member 20.

  Thus, the gas generating agent 55 at the position facing the opening 73 is ignited and burned first, and the gas generating agent 55 at a position away from the opening 73 is ignited and burned with a delay. Combustion is suppressed, and the initial gas generation amount is suppressed (that is, the rising of the initial output is suppressed). This suppresses the load on the pretensioner to which the gas generator 3 is assembled, and it is not necessary to increase the component strength of the pretensioner, so that assembly is facilitated.

Example 1 and Comparative Example 1
1 and the gas generator 1 shown in FIG. 1 except that the first and second partition members 31 and 32 are not used. A closed tank combustion test was conducted. The results are shown in FIG.

<Tank combustion test>
A gas generator is fixed in a SUS (stainless steel) tank having an internal volume of 27 ml, the tank is sealed at room temperature, and then connected to an external ignition electric circuit. Separately, a pressure transducer installed in the tank is used to measure the change in pressure in the tank for a period of 0 to 50 milliseconds, with the time when the ignition electric circuit switch is turned on (application of the ignition current) being zero. Each measurement data is finally converted into a tank pressure / time curve by computer processing to obtain a curve (tank curve) for evaluating the performance of the gas generant molding.

  Compared with the gas generator of Comparative Example 1, the gas generator of Example 1 was suppressed from rising in the initial output, but there was almost no difference in the maximum output.

Example 2 and Comparative Example 2
The same well-known 60 L tank combustion test as in Example 1 using the gas generator 2 shown in FIG. 2 and the same comparative gas generator except that the gas generator 2 shown in FIG. 2 does not have the inner cup member 60. Went. The results are shown in FIG.

  Compared with the gas generator of Comparative Example 2, the gas generator of Example 2 was suppressed from rising in the initial output, but the maximum output was not different.

The longitudinal cross-sectional view of the gas generator of this invention. The longitudinal cross-sectional view of the gas generator of other embodiment. Furthermore, the longitudinal cross-sectional view of the gas generator of other embodiment. The figure which shows the result of the 27 ml closed tank combustion test in Example 1 and Comparative Example 1. The figure which shows the result of the 27 ml closed tank combustion test in Example 2 and Comparative Example 2.

Explanation of symbols

1, 2, 3 Gas generator 10 Igniter assembly 11 Igniter 12 Igniter collar 20 Cup member (outer cup member)
31 1st partition member 32 2nd partition member 41 1st combustion chamber 42 2nd combustion chamber 43 3rd combustion chamber 51 1st gas generating agent 52 2nd gas generating agent 53 3rd gas generating agent

Claims (6)

A gas generator having an igniter assembly in which one igniter having an igniter is fixed to an igniter collar, and an outer cup member covering at least a portion including the igniter of the igniter,
The inside of the cup member is separated into two or more combustion chambers by one or more partition members, and a gas generating agent is accommodated in the one or more combustion chambers,
A gas generator for a seat belt retractor in which combustion of a gas generating agent in another combustion chamber is started by generating heat in one combustion chamber by the operation of the igniter.   The inside of the outer cup member is separated by two partition members so that three combustion chambers are formed in the axial direction, and among the three combustion chambers, an intermediate combustion chamber includes the ignition portion. The gas generator for a seat belt retractor according to claim 1, wherein a gas generating agent is accommodated in all the combustion chambers.   The inside of the outer cup member is separated into two combustion chambers by one partition member, the ignition part is located in one combustion chamber, and the partition member has a communication hole for communicating the two combustion chambers. The gas generator for a seat belt retractor according to claim 1, wherein the flame transfer to the other combustion chamber is adjusted by adjusting an opening area of the communication hole.   The inside of the outer cup member is separated into two combustion chambers by one partition member, the ignition part is located in one combustion chamber, and the partition member has a communication hole for communicating the two combustion chambers. And the gas generator for seatbelt retractors in any one of Claims 1-3 which adjusts the heat transfer to another combustion chamber by adjusting the opening position of the said communicating hole. The one partition member is an inner cup member that covers the ignition part, and the outer cup member is further covered outside the inner cup member,
The inner cup member includes an outer wall surface having the communication hole and an outer wall surface not having the communication hole, and an interval between the outer wall surface having the communication hole and the inner wall surface of the outer cup member is the communication hole. The gas generator for a seat belt retractor according to claim 3 or 4, wherein the gas generator is smaller than an interval between an outer wall surface that does not have a gap and an inner wall surface of the outer cup member. The outer wall surface having the communication hole of the inner cup member is a bottom surface, the outer wall surface not having the communication hole of the inner cup member is a peripheral surface, or the outer wall surface having the communication hole of the inner cup member is The gas generator for a seat belt retractor according to claim 5, wherein an outer wall surface that is a peripheral surface and does not have a communication hole of the inner cup member is a bottom surface.

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