JP2010064668A - Inflater and airbag device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a small inflater capable of adjusting rising of a pressure increase in generation gas of a gas generating agent and adjusting combustion time. <P>SOLUTION: The inflater 1 has a housing 10 forming a combustion space 15 inside, an initiator 18 arranged via a holder 17 in an installation hole formed in a base side housing 10A, an ignition control sleeve 20 having the other end locked on and held by a part of the holder 17 so that one end secures a predetermined clearance between a cover side housing 10E and itself, and the gas generating agent 35 filled in the inside-outside combustion spaces 15 partitioned by the ignition control sleeve 20. This inflater 1 jets the generation gas outside the housing 10 from a jetting hole 13 by passing through a filter 30 of the outermost side surface in the combustion space 15 by igniting the gas generating agent 35 outside of the sleeve 20 via a clearance with the cover side housing 10B side after igniting the gas generating agent 35 in the sleeve 20. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an inflator and an airbag device, and more particularly to an inflator capable of controlling the ignition start time and the rising tendency of output in a compact shape and an airbag device equipped with the inflator.

  The airbag device is attached to a steering base or an instrument panel, and is intended to restrain the target occupant by rapidly inflating the airbag into a predetermined shape by a gas ejected from an inflator during a collision or the like. A normal inflator includes a housing of various shapes having a combustion chamber for burning a gas generating agent (propellant) therein, a filter attached to an exhaust side of the combustion chamber, and an ignition device for igniting and burning the propellant ( Initiator) and the like. When the initiator is activated in response to the operation signal and a flame is injected into the combustion chamber via the transfer agent, the propellant is ignited and burned by the flame, and high-temperature and high-pressure gas is generated. After passing through the filter, this gas is discharged to the outside from a gas ejection hole formed in the housing, and the airbag is inflated into a deployed shape according to the purpose of restraining the passenger. The filter is formed, for example, by forming a steel wire into a cylindrical shape, and serves to lower the temperature of the high-temperature gas and remove slag (combustion residue, burnout) mixed in the gas.

Various types of reaction mechanisms for inflator gas generation have been proposed. For example, the gas generator disclosed in Patent Document 1 is filled with a transfer agent (booster propellant) in a loading cylinder and ignited. The flame energy of the transfer agent ignited by the ignition of the vessel (initiator) was injected from the flame outlet provided on the end face of the loading cylinder toward the upper lid, and was stored in the space between the upper lid and the flame outlet Efficient gas generation is realized by selectively burning the gas generating agent (main propellant) and then causing the surrounding gas generating agent to burn.
JP 2002-370607 A

  In the gas generator disclosed in Patent Document 1, boron nitrate or the like that ignites more sensitively than the gas generating agent is used as the transfer agent accommodated in the loading cylinder. A large amount of the transfer agent is required to burn the agent reliably. Accordingly, there is a problem that the volume of the loading cylinder to be accommodated increases, and the appearance of the entire inflator also increases.

  In the conventional inflator disclosed in Patent Document 1, the main propellant filled in the housing is controlled by controlling the flame injection direction of a transfer agent or the like housed in a cylindrical body provided at the center of the housing. It was characterized by increasing the gas generation efficiency by the main propellant by burning the gas stepwise or selectively. Therefore, it is necessary to provide a partition space for filling and containing the contents (igniting agents) having a capacity necessary for combustion, so that it is difficult to reduce the size of the inflator.

  As a proposal for downsizing the inflator, the cylindrical body that contains the transfer agent (booster propellant) is removed, and the initiator uses a strong igniting agent such as ZPP (zirconium / potassium perchlorate mixture), A structure in which the main propellant is ignited directly by the initiator is also conceivable. However, in this case, since the ignition start time (TTFG) of the main propellant is delayed and the rising tendency of the output after ignition becomes steep, it is difficult to adjust the gas pressure and the amount of gas generated, and the airbag is inflated. Control cannot be performed well. Accordingly, an object of the present invention is to solve the above-mentioned problems, use an appropriate initiator, adjust the duration of gas generation without delaying the start of ignition of the main propellant, and reduce the size of the inflator. The object is to provide an airbag device.

  To achieve the above object, according to the present invention, a substantially bowl-shaped base side housing and a cover side housing are combined to form a combustion space therein, and the base side housing is formed in the housing. An initiator provided in the mounting hole via the holder, and an ignition control sleeve whose one end is locked and held by a part of the holder so that a predetermined gap is secured between the end and the cover-side housing; And an inflator comprising a gas generating agent filled in internal and external combustion spaces defined by the ignition control sleeve, wherein the cover after the gas generating agent in the ignition control sleeve is ignited by the initiator The gas generating agent outside the sleeve is ignited through a gap with the side housing side, and the generated gas passes through a filter held on the outermost surface in the combustion space, And characterized in that the ejection holes formed on the serial cover side housing to eject out of the housing.

  Changing the amount of clearance between one end of the ignition control sleeve and the cover side housing side, the ignition start time of the gas generating agent outside the ignition control sleeve, and the rising slope of the gas pressure ejected from the ejection hole immediately after the start of ignition Can be controlled. Thereby, the inflation timing of the airbag can be adjusted, and occupant restraint can be optimized.

  The inside and outside combustion spaces are preferably filled with the same type of gas generating agent. By using a gas generating agent that ensures a sufficient amount of gas generation, the filling volume of the gas generating agent can be reduced, and the inflator can be downsized.

  It is preferable that the size of the gas generant filled in the ignition control sleeve is smaller than the size of the gas generant filled outside the ignition control sleeve. Thereby, the rising tendency of the pressure of the gas ejected from the inflator immediately after the inflator gas is generated can be adjusted.

  The filter is a ring-shaped body having a width substantially equal to the height direction of the combustion space, and is a substantially bowl-shaped holder provided in the housing. Preferably, the generated gas is held so as not to permeate, and the generated gas permeates the entire length in the width direction from one end to the other end in the width direction of the filter. Thereby, the temperature reduction of the high temperature generated gas and the removal of the slag can be reliably performed.

  In the airbag device using the inflator described above, the inflator is held at a predetermined base portion of a vehicle body via a fixing member, and the folded airbag covers the gas ejection hole of the inflator. The airbag is fixed to the fixing member as described above, and the airbag can be inflated and deployed with a predetermined deployment tendency due to gas generation from the ejection hole of the inflator when a collision is detected. According to this airbag device, a small inflator can be used for the steering base or the like, and the effect of easily controlling the deployment tendency of the airbag at the time of a collision can be achieved.

  As described above, according to the present invention, it is possible to provide a small inflator capable of adjusting the rise of the pressure rise of the generated gas of the gas generating agent (propellant) and adjusting the combustion time.

  Hereinafter, an inflator according to an embodiment of the present invention will be described with reference to the examples shown in FIGS.

  FIG. 1 is a cross-sectional view of the inflator of this embodiment. The housing 10 of the inflator 1 shown in the figure has a flat cylindrical shape, and a container structure in which a base side housing 10A having a flat circular hook-shaped portion and an opening side of the cover side housing 10B are fitted face to face. Consists of. A peripheral flange 11 is formed on the edge of the circular flange portion of the base-side housing 10A. A mounting hole 12 is formed in the peripheral flange 11, and a mouth portion of a folded airbag (not shown) is fixed to the peripheral flange 11 via a fixing bolt or the like (not shown). The entire inflator 1 is held by a steering base (not shown) or the like via a retainer (not shown) attached to the peripheral flange 11. On the side surface of the cover-side housing 10B, there are arranged, as will be described later, jet holes 13 for the generated gas at a predetermined pitch so that the jet holes 13 are exposed from the peripheral flange 11 of the base-side housing 10A as shown in FIG. The combustion space 15 is formed inside the housing 10 which is fitted and attached to the inner diameter portion of the base-side housing 10A. For any of the housings 10A and 10B, a molded product obtained by drawing a steel plate having a thickness of about 2.0 mm into a bowl shape can be used.

  A circular hole 16 capable of accommodating an initiator 18 (described later) is formed at the center of the disk portion of the base-side housing 10A, and a substantially cylindrical holder 17 is fitted from the circular hole 16 toward the combustion space 15. It is worn. An initiator 18 is mounted on the inner periphery of the holder 17 so that the electrode terminal 18a is exposed to the outside. A predetermined amount of ZPP is charged in the initiator 18 as an ignition agent. An ignition current from an airbag operation control unit (not shown) (not shown) is applied to the electrode terminal 18 a of the initiator 18. Further, the base portion of the ignition control sleeve 20 is fitted so as to be in contact with the collar 17 a on the outer peripheral surface of the holder 17 in the housing 10. The ignition control sleeve 20 is a carbon steel cylinder having a wall thickness of about 1 mm and a diameter of φ25 mm. The cylinder length is the cover side housing 10B (exactly, the outer holder 25B of the filter holder 25) as shown in FIG. It is set to a length that secures a clearance d between the inner surface and the inner surface. As will be described later, the clearance d functions as a parameter for performing propellant ignition control according to the design specifications of the inflator 1. The size of the inflator 1 is different depending on the gas generation capacity, and the volume of the combustion space 15 is also different. At this time, the proper diameter of the ignition control sleeve 20 used by being fitted to the holder 17 is assumed to have a diameter of about 10 to 35 mm. Further, it is necessary to make the wall thickness such that the sleeve 20 does not deform during combustion in the ignition control sleeve 20. Therefore, it is preferable to maintain the rigidity of the sleeve 20 by setting the thickness to about 0.5 to 1.5 mm corresponding to the diameter.

  A filter holder 25 that holds a filter 30 described later is accommodated in the combustion space 15. The filter holder 25 is a circular rod-shaped body formed by molding low-carbon steel having a thickness of 0.5 mm, and includes an inner holder 25A and an outer holder 25B having substantially the same shape and different diameters. The inner holder 25A has a hook shape in contact with the inner surface of the base side housing 10A and the inner peripheral surface of the filter 30, and is fitted into the outer edge of the collar 17a of the holder 17 located at the center of the base side housing 10A. It is fixed to. The outer holder 25B has a hook shape that contacts the inner surface of the cover-side housing 10B and the outer peripheral surface of the filter 30, and is fixed to the inner surface of the cover-side housing 10B.

  Also in the inflator 1 of the present invention, the filter 30 is mounted in order to remove slag mixed in the generated gas, similarly to the conventional inflator. The filter 30 of the present embodiment is made of a ring-shaped body having a predetermined width obtained by press-molding a metal mesh made of the same shape and material as in the prior art or a bundle of finely and randomly curved wires. The diameter and width of the ring are set according to the height of the combustion space 15 of the housing.

  In the present invention, the combustion state of the gas generated in the inflator 1 and the exhaust path to the outside of the generated gas are set as shown in FIG. 2 (in the figure, illustration of the propellant is omitted for explanation). is doing). That is, in this inflator 1, gas permeation holes are not formed on the peripheral surface of the inner holder 25A and the peripheral surface of the outer holder 25B. For this reason, the generated gas is sent to the end of the filter 30 from the gap 26 at the end of the peripheral surface of the inner holder 25 </ b> A as shown by the broken line in FIG. After that, gas passes through the gas passage 28 formed between the outer peripheral surface of the outer holder 25B and the inner peripheral surface of the cover-side housing 10B from the gap 27 at the outer end of the filter 30, and the gas jet formed in the cover-side housing 10B. It is ejected from the hole 13 to the outside of the inflator 1. Since the filter 30 is completely transmitted through such a gas path (shown by a broken line in FIG. 2), slag mixed in the gas can be removed with high efficiency. In this embodiment, considering the gas transmission efficiency at the position of the filter 30, the filter 30 is formed to have a thickness of about 3.0 to 6.0 mm and a width of about 25 to 35 mm.

  In the inflator 1 of the present invention, a propellant 35 as a gas generating agent is filled in the ignition control sleeve 20 in the inflator 1 and the combustion space 15 outside thereof. In the present embodiment, a flat tablet-shaped propellant 35 is used, and predetermined ratio amounts are packed in the combustion space 15 inside and outside the sleeve 20. In particular, the initiator 18 protrudes into the ignition control sleeve 20, and the propellant 35 is ignited early by the ignition of the initiator 18 to generate gas. Is packed to be about 1.5 to 5 g. Further, the other propellant 35 is filled with a predetermined amount in the annular combustion space 15 between the inner holder 25 </ b> A of the filter holder 25 and the outer periphery of the ignition control sleeve 20. In this example, the tablet size of propellant 35 (diameter φ, thickness h) was all normal size φ6.35 mm × h3.175 mm. The tablet-like propellant 35 includes guanidine-nitrate (Gu-Ni), aminotetrazole (5AT), ammonium perchlorate (AP), and ammonium nitrate (AN) gas generating agents. Is preferably selected and used in consideration of the amount of gas generated according to the airbag volume, the thermal power specifications, the volume of the space in which the medicine can be filled, and the like.

  A gas generation mechanism during operation of the inflator 1 having the configuration shown in FIG. 1 will be described with reference to FIG. In the present invention, a predetermined amount of ZPP (zirconium / potassium perchlorate), which is a relatively strong igniter, is loaded as the initiator 18, and the igniter is ignited by applying an ignition current from an ignition control unit (not shown). The propellant 35 in the ignition control sleeve 20 is ignited by the high-temperature flame generated at the time of ignition. The combustion flame and high-temperature gas generated in the sleeve 20 spread in the combustion space 15 in the outer peripheral portion through a clearance portion opened in a circular shape between the tip of the sleeve 20 and the outer holder 25B side. Along with this, the propellant 35 filled in the combustion space 15 on the outer periphery continues to burn, and finally the propellant 35 in the combustion space 15 generates combustion gas having a volume sufficient to inflate an unillustrated airbag. Let As shown in FIG. 2, the combustion gas is sent to the end of the filter 30 from the gap 26 at the peripheral end of the inner holder 25 </ b> A, and permeates the filter 30 along the width direction (longitudinal direction). Air that is blown out of the inflator 1 through a gas passage 28 formed between the outer peripheral surface of the filter 30 and the inner peripheral surface of the cover-side housing 10B, is blown out of the inflator 1 through a gas discharge hole 13 formed in the cover-side housing 10B. The bag expands and deploys.

  Here, the gas passage area (usually the diameter of the sleeve 20 has a clearance) through which the combustion flame of the propellant 35 and the high-temperature gas in the sleeve 20 pass when being transmitted to the tip of the sleeve 20 and the cover-side housing 10B side. Since it is determined, the pressure change of the generated gas due to the difference in the magnitude (depending on the clearance d) will be described with reference to FIG. The figure shows the pressure change over time (ms) from the ignition start time (TTFG: Time To Fire Gas) in the external combustion space 15 when the clearance d is changed to 0.5, 1.5, 6.0 mm. It is a relational graph showing (kPa). When the clearance is increased by using the same amount of propellant 35 (d> 4 mm), the pressure rise, the peak pressure, and the peak arrival time can be shortened. For example, this type of inflator is preferably used in an airbag apparatus that needs to restrain an occupant from the early stage of deployment. On the other hand, there is a case where it is required to restrain the occupant gently without performing rapid occupant restraint due to the space of the passenger compartment. In that case, it is possible to cope with this by delaying the rising of the generation of gas pressure from the inflator. As described above, in the present invention, the ignition control sleeve 20 is provided, and the clearance with the cover-side housing 10B at the distal end position thereof is adjusted, so that the same propellant 35 is used to control the speed of the pressure increase. can do. Thus, according to the inflator 1 of the present invention, the rise of the pressure rise can be controlled without increasing the size of the inflator, and the output characteristics of the inflator in accordance with the deployment tendency required for each type of airbag device can be obtained. Can be realized.

  FIG. 3 shows that the diameter of the ignition control sleeve 20 is increased from the beginning, and the amount of propellant 35i that is ignited when ignited by the initiator 18 is increased to fill the propellant 35o in the combustion space 15 outside the sleeve 20. This is a modification example in which gas is generated by reducing the amount. According to this modification, even when the clearance d is the same, the combustion energy generated in the ignition control sleeve 20 in the initial stage increases, and the rise in pressure rise during combustion by the propellant 35o in the external combustion space 15 occurs. You can change the trend. Specifically, in the setting range of φ10 to 35 mm, the pressure rising speed increases as the diameter increases. When it becomes more than φ35mm, it tends to be slow. At this time, if the diameter of the ignition control sleeve 20 is increased, the volume of the sleeve 20 is increased. Therefore, if the propellant 35i is filled with the same gap density, the filling amount of the propellant 35i filled in the sleeve 20 is increased and external combustion is performed. Although the filling amount of the propellant 35o filled in the space 15 is reduced, the balance of the filling amounts of the propellants 35i and 35o filled in the spaces may be adjusted by adjusting the gap density at the time of filling. .

In general, it is known that the burning rate (the rising tendency of the pressure increase shown in FIG. 5) is proportional to the total surface area of the filled propellant 35. When filling the same amount (mass) of the drug, the use of the propellant 35 having a small shape increases the total surface area and increases the burning rate. However, it is necessary to continue the combustion time to some extent and inflate the airbag to a predetermined shape at an appropriate timing during that time. Therefore, an embodiment for improving the ignitability will be described with reference to FIGS.
In the inflator 1 shown in FIG. 4, the ignition control sleeve 20 is filled with a tablet-shaped propellant 35s having a small particle size (φ4.76 mm × h1.524 mm in this embodiment), and the above-described ordinary combustion space 15 is filled with the above-described ordinary This type is filled with tablet-shaped propellant 35n. Other configurations are the same as those in FIG. FIG. 6 is a graph comparing the ignition properties of the inflator 1 when the clearance d of the ignition control sleeve 20 is set to 0.5 mm and the conventional ignition properties of a normal size. As shown in the figure, when the ignition control sleeve 20 is filled with a small-sized tablet-shaped propellant 35s, the rise in pressure rises compared to when the sleeve 20 is filled with a normal-sized propellant 35n. Can be expedited. In this embodiment, the rise to the peak can be shortened by about 5 to 10 ms, and the combustion speed at the initial stage can be made more linear. Therefore, even with this configuration, the rise of the pressure of the inflator can be increased. It becomes possible to control.

  As described above, by reducing the size of the propellant 35 to be used and packing it in the ignition control sleeve 20, the volume of the ignition control sleeve 20 can be reduced when the equivalent ignition property is obtained. It is possible to further reduce the size of the inflator 1 as a whole. In the above description, the flat cylindrical inflator 1 whose cross-sectional view is shown in FIG. 1 is described as an example. However, if the gas generating mechanism is the same inflator, the ignition control sleeve 20 is provided, and the combustion time If this control is possible, the housing can have various shapes.

  The inflator 1 described above can be used in various airbag devices that are installed in various parts of an automobile or the like. Hereinafter, an embodiment applied to a driver airbag device 40 will be described with reference to FIGS. FIG. 7 is a cross-sectional view showing a schematic configuration of the airbag device 40 provided in the steering base 41. As shown in the figure, in the airbag device 40, the housing 10 of the inflator 1 and the airbag 43 folded on the front surface thereof are accommodated in the module cover 42, and the base side housing 10A of the inflator 1 is fixed. The bolt 44 is integrally fixed to the steering base 41 at the end of the steering rod together with the support portion of the steering wheel 46 via a retainer 45 having a predetermined shape as a fixing member. An opening edge 43 a of the air bag 43 is also closely fixed to the base portion 41 with a fixing bolt 48 so as to cover the gas ejection hole 13 of the inflator 1. From this state, when a sensor of a collision detection unit (not shown) detects a collision to the extent that the airbag is deployed, gas is generated in the inflator 1 with a gas pressure controlled to a predetermined rising property as described above, and the housing 10 Gas is ejected from the gas ejection holes 13. As a result, the airbag 43 can be inflated and deployed into a shape as shown in FIG. 8 with a predetermined deployment tendency by expanding a tear line (not shown) of the module cover 42 from the inside. Thus, by using the inflator 1 described above, the airbag device 40 provided in the steering base can be made compact, and the airbag 43 can be appropriately inflated and deployed in accordance with the size and shape of the passenger compartment space. Properties can be set.

Sectional drawing which showed the cross section of one Example of the inflator of this invention. Sectional drawing which showed typically the ignition and gas generation state in the inflator shown in FIG. Sectional drawing which showed the modification of the ignition control sleeve of the inflator shown in FIG. Sectional drawing which showed the example of filling of the propellant with which it fills in an inflator. The graph which showed the relationship between the elapsed time at the time of the inflator operation | movement when changing the clearance d, and generated gas pressure. The graph which showed the relationship between the elapsed time at the time of the inflator operation | movement at the time of changing the size of the propellant in a sleeve, and generated gas pressure. Sectional drawing which showed the internal structure of the airbag apparatus equipped with the inflator of this invention. The partial cross section figure which showed the inflated and deployed state of the airbag of the airbag apparatus shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inflator 10 Housing 10A Base side housing 10B Cover side housing 13 Gas ejection hole 15 Combustion space 17 Holder 18 Initiator 20 Ignition control sleeve 25 Filter holder 25A Inner holder 25B Outer holder 30 Filter 35, 35i, 35o, 35s, 35n Propellant d Clearance 40 Airbag device 43 Airbag

Claims (6)

A housing in which a combustion space is formed by combining a substantially bowl-shaped base side housing and a cover side housing, and an initiator provided in a mounting hole formed in the base side housing in the housing via a holder An ignition control sleeve having one end secured to a part of the holder so that a predetermined gap is secured between the cover-side housing and an internal / external combustion defined by the ignition control sleeve An inflator comprising a gas generating agent filled in a space,
After the gas generating agent in the ignition control sleeve is ignited by the initiator, the gas generating agent outside the sleeve is ignited through a gap with the cover side housing side, and the generated gas is the outermost surface in the combustion space. An inflator characterized in that it passes through a filter held by the cover and is ejected from an ejection hole formed in the cover-side housing to the outside of the housing.   Changing the amount of clearance between one end of the ignition control sleeve and the cover side housing side, the ignition start time of the gas generating agent outside the ignition control sleeve, and the rising slope of the gas pressure ejected from the ejection hole immediately after the start of ignition The inflator according to claim 1, wherein the inflator is controlled.   The inflator according to claim 1 or 2, wherein the same type of gas generating agent is filled in the internal and external combustion spaces.   The inflator according to any one of claims 1 to 3, wherein a size of the gas generating agent filled in the ignition control sleeve is smaller than a size of the gas generating agent filled outside the ignition control sleeve.   The filter is a ring-shaped body having a width substantially equal to the height direction of the combustion space, and is a substantially bowl-shaped holder provided in the housing. The inflator according to any one of claims 1 to 4, wherein the inflator is held so as not to permeate, and the generated gas permeates the entire length in the width direction from one end to the other end in the width direction of the filter.   The inflator according to claim 1 is held at a predetermined base portion of the vehicle body via a fixing member, and the folded airbag is fixed to the fixing member so that the edge of the opening covers the gas ejection hole of the inflator An airbag apparatus according to claim 1, wherein the airbag exhibits a predetermined deployment tendency and can be inflated and deployed by generating gas from the ejection hole of the inflator when a collision is detected.

Images